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Sample records for gamma spectrometry spectra

  1. Study of different filtering techniques applied to spectra from airborne gamma spectrometry

    SciTech Connect

    Wilhelm, Emilien; Gutierrez, Sebastien; Reboli, Anne; Menard, Stephanie; Nourreddine, Abdel-Mjid; Arbor, Nicolas

    2015-07-01

    One of the features of spectra obtained by airborne gamma spectrometry is low counting statistics due to the short acquisition time (1 s) and the large source-detector distance (40 m). It leads to considerable uncertainty in radionuclide identification and determination of their respective activities from the windows method recommended by the IAEA, especially for low-level radioactivity. The present work compares the results obtained with filters in terms of errors of the filtered spectra with the window method and over the whole gamma energy range. The results are used to determine which filtering technique is the most suitable in combination with some method for total stripping of the spectrum. (authors)

  2. Study of different filtering techniques applied to spectra from airborne gamma spectrometry.

    PubMed

    Wilhelm, Emilien; Gutierrez, Sébastien; Arbor, Nicolas; Ménard, Stéphanie; Nourreddine, Abdel-Mjid

    2016-11-01

    One of the features of the spectra obtained by airborne gamma spectrometry is the low counting statistics due to a short acquisition time (1 s) and a large source-detector distance (40 m) which leads to large statistical fluctuations. These fluctuations bring large uncertainty in radionuclide identification and determination of their respective activities from the window method recommended by the IAEA, especially for low-level radioactivity. Different types of filter could be used on spectra in order to remove these statistical fluctuations. The present work compares the results obtained with filters in terms of errors over the whole gamma energy range of the filtered spectra with the window method. These results are used to determine which filtering technique is the most suitable in combination with some method for total stripping of the spectrum.

  3. EML Gamma Spectrometry Data Evaluation Program

    SciTech Connect

    Decker, Karin M.

    2001-01-01

    This report presents the results of the analyses for the third EML Gamma Spectrometry Data Evaluation Program (October 1999). This program assists laboratories in providing more accurate gamma spectra analysis results and provides a means for users of gamma data to assess how a laboratory performed on various types of gamma spectrometry analyses. This is accomplished through the use of synthetic gamma spectra. A calibration spectrum, a background spectrum, and three sample spectra are sent to each participant in the spectral file format requested by the laboratory. The calibration spectrum contains nuclides covering the energy range from 59.5 keV to 1836 keV. The participants are told fallout and fission product nuclides could be present. The sample spectra are designed to test the ability of the software and user to properly resolve multiplets and to identify and quantify nuclides in a complicated fission product spectrum. The participants were asked to report values and uncertainties as Becquerel per sample with no decay correction. Thirty-one sets of results were reported from a total of 60 laboratories who received the spectra. Six foreign laboratories participated. The percentage of the results within 1 of the expected value was 68, 33, and 46 for samples 1, 2, and 3, respectively. From all three samples, 18% of the results were more than 3 from the expected value. Eighty-three (12%) values out of a total of 682 expected results were not reported for the three samples. Approximately 30% of these false negatives were due the laboratories not reporting 144Pr in sample 2 which was present at the minimum detectable activity level. There were 53 false positives reported with 25% of these responses due to problems with background subtraction. The results show improvement in the ability of the software or user to resolve peaks separated by 1 keV. Improvement is still needed either in the analysis report produced by the software or in the review of these

  4. 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.

  5. Low-level gamma-ray spectrometry

    SciTech Connect

    Brodzinski, R.L.

    1990-10-01

    Low-level gamma-ray spectrometry generally equates to high-sensitivity gamma-ray spectrometry that can be attained by background reduction, selective signal identification, or some combination of both. Various methods for selectively identifying gamma-ray events and for reducing the background in gamma-ray spectrometers are given. The relative magnitude of each effect on overall sensitivity and the relative cost'' for implementing them are given so that a cost/benefit comparison can be made and a sufficiently sensitive spectrometer system can be designed for any application without going to excessive or unnecessary expense. 10 refs., 8 figs.

  6. Photon energy conversion efficiency in gamma-ray spectrometry.

    PubMed

    Švec, Anton

    2016-01-01

    Photon energy conversion efficiency coefficient is presented as the ratio of total energy registered in the collected spectrum to the emitted photon energy. This parameter is calculated from the conventional gamma-ray histogram and in principle is not affected by coincidence phenomena. This feature makes it particularly useful for calibration and measurement of radionuclide samples at close geometries. It complements the number of efficiency parameters used in gamma-ray spectrometry and can partly change the view as to how the gamma-ray spectra are displayed and processed.

  7. Airborne Gamma-Spectrometry in Switzerland

    NASA Astrophysics Data System (ADS)

    Butterweck, Gernot; Bucher, Benno; Rybach, Ladislaus

    2008-08-01

    Airborne gamma-spectrometry is able to obtain fast radiological information over large areas. The airborne gamma-spectrometry unit deployed in Switzerland by the Swiss National Emergency Operations Centre (NEOC) consists of a Swiss army Super Puma helicopter equipped with four NaI-Detectors with a total volume of 17 liters, associated electronics and a real-time data evaluation and mapping unit developed by the Swiss Federal Institute of Technology (ETH) and the Paul Scherrer Institut (PSI). The operational readiness of the airborne gamma-spectrometry system is validated in annual exercises of one week duration. Data from 2005 and 2006 exercises are represented in maps of 137Cs activity concentration for two towns located in southern and western Switzerland. An indicator of man-made radioactivity (MMGC ratio) is demonstrated for an area with four different types of nuclear installations. The intercomparison between airborne gamma-spectrometry and ground measurements showed good agreement between both methods.

  8. Airborne Gamma-Spectrometry in Switzerland

    SciTech Connect

    Butterweck, Gernot; Bucher, Benno; Rybach, Ladislaus

    2008-08-07

    Airborne gamma-spectrometry is able to obtain fast radiological information over large areas. The airborne gamma-spectrometry unit deployed in Switzerland by the Swiss National Emergency Operations Centre (NEOC) consists of a Swiss army Super Puma helicopter equipped with four NaI-Detectors with a total volume of 17 liters, associated electronics and a real-time data evaluation and mapping unit developed by the Swiss Federal Institute of Technology (ETH) and the Paul Scherrer Institut (PSI). The operational readiness of the airborne gamma-spectrometry system is validated in annual exercises of one week duration. Data from 2005 and 2006 exercises are represented in maps of {sup 137}Cs activity concentration for two towns located in southern and western Switzerland. An indicator of man-made radioactivity (MMGC ratio) is demonstrated for an area with four different types of nuclear installations. The intercomparison between airborne gamma-spectrometry and ground measurements showed good agreement between both methods.

  9. Spectra of {gamma} rays feeding superdeformed bands

    SciTech Connect

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

    1995-08-01

    The spectrum of {gamma}rays coincident with SD transitions contains the transitions which populate the SD band. This spectrum can provide information on the feeding mechanism and on the properties (moment of inertia, collectivity) of excited SD states. We used a model we developed to explain the feeding of SD bands, to calculate the spectrum of feeding {gamma}rays. The Monte Carlo simulations take into account the trigger conditions present in our Eurogam experiment. Both experimental and theoretical spectra contain a statistical component and a broad E2 peak (from transitions occurring between excited states in the SD well). There is good resemblance between the measured and calculated spectra although the calculated multiplicity of an E2 bump is low by {approximately}30%. Work is continuing to improve the quality of the fits, which will result in a better understanding of excited SD states. In addition, a model for the last steps, which cool the {gamma} cascade into the SD yrast line, needs to be developed. A strong M1/E2 low-energy component, which we believe is responsible for this cooling, was observed.

  10. 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.

  11. 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.

  12. Gamma-ray Output Spectra from 239 Pu Fission

    DOE PAGES

    Ullmann, John

    2015-05-25

    Gamma-ray multiplicities, individual gamma-ray energy spectra, and total gamma energy spectra following neutron-induced fission of 239Pu were measured using the DANCE detector at Los Alamos. Corrections for detector response were made using a forward-modeling technique based on propagating sets of gamma rays generated from a paramaterized model through a GEANT model of the DANCE array and adjusting the parameters for best fit to the measured spectra. The results for the gamma-ray spectrum and multiplicity are in general agreement with previous results, but the measured total gamma-ray energy is about 10% higher. A dependence of the gamma-ray spectrum on the gamma-raymore » multplicity was also observed. Global model calculations of the multiplicity and gamma energy distributions are in good agreement with the data, but predict a slightly softer total-energy distribution.« less

  13. A code to simulate nuclear reactor inventories and associated gamma-ray spectra.

    PubMed

    Cresswell, A J; Allyson, J D; Sanderson, D C

    2001-01-01

    A computer code has been developed to simulate the gamma-ray spectra that would be measured by airborne gamma spectrometry (AGS) systems from sources containing short-lived fission products. The code uses simple numerical methods to simulate the production and decay of fission products and generates spectra for sodium iodide (NaI) detectors using Monte Carlo codes. A new Monte Carlo code using a virtual array of detectors to reduce simulation times for airborne geometries is described. Spectra generated for a short irradiation and laboratory geometry have been compared with an experimental data set. The agreement is good. Spectra have also been generated for airborne geometries and longer irradiation periods. The application of this code to generate AGS spectra for accident scenarios and their uses in the development and evaluation of spectral analysis methods for such situations are discussed.

  14. Pulsar gamma-rays: Spectra luminosities and efficiencies

    NASA Technical Reports Server (NTRS)

    Harding, A. K.

    1980-01-01

    The general characteristics of pulsar gamma ray spectra are presented for a model where the gamma rays are produced by curvature radiation from energetic particles above the polar cap and attenuated by pair production. The shape of the spectrum is found to depend on pulsar period, magnetic field strength, and primary particle energy. By a comparison of numerically calculated spectra with the observed spectra of the Crab and Vela pulsars, it is determined that primary particles must be accelerated to energies of about 3 x 10 to the 7th power mc sq. A genaral formula for pulsar gamma ray luminosity is determined and is found to depend on period and field strength.

  15. Parametric Studies for 233U Gamma Spectrometry

    SciTech Connect

    Scheffing, C.C.; Krichinsky, A.

    2004-01-01

    Quantification of special nuclear material is a necessary aspect to assuring material accountability and is often accomplished using non-destructive gamma spectrometry. For 233U, gamma rays are affected by matrix and packaging attenuation and by a strong Compton continuum from decay products of 232U (inherently found in 233U) that obscure 233U gamma photopeaks. This project, based on current work at the national repository for separated 233U located at Oak Ridge National Laboratory (ORNL), explores the effects of various parameters on the quantification of 233U– including material form and geometry. Using an attenuation correction methodology for calculating the mass of 233U from NDA analysis, a bias of almost 75% less than the actual 233U mass was identified. The source of the bias needs to be understood at a more fundamental level for further use of this quantification method. Therefore, controlled experiments using well characterized packages of 233U were conducted at the repository and are presented in this paper.

  16. In-flight, online processing and mapping of airborne gamma spectrometry data

    NASA Astrophysics Data System (ADS)

    Bucher, Benno; Rybach, Ladislaus; Schwarz, Georg

    2005-03-01

    Airborne gamma spectrometry is a technique especially useful for environmental monitoring and emergency preparedness. Because time is a critical factor in emergency response a fast data processing and mapping software is needed, which also supports online monitoring and data processing features. Therefore a new online data processing and mapping software was developed, which also displays successfully the gamma spectra, the ground activity and the topographical data. The software was successfully tested during various survey flights.

  17. Composite mapping experiences in airborne gamma spectrometry.

    PubMed

    Bucher, B

    2014-08-01

    During an international intercomparison exercise of airborne gamma spectrometry held in Switzerland 2007 teams from Germany, France and Switzerland were proving their capabilities. One of the tasks was the composite mapping of an area around Basel. Each team was mainly covering the part of its own country at its own flying procedures. They delivered the evaluated data in a data format agreed in advance. The quantities to be delivered were also defined in advance. Nevertheless, during the process to put the data together a few questions raised: Which dose rate was meant? Had the dose rate to be delivered with or without cosmic contribution? Activity per dry or wet mass? Which coordinate system was used? Finally, the data could be put together in one map. For working procedures in case of an emergency, quantities of interest and exchange data format have to be defined in advance. But the procedures have also to be proved regularly.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  19. A COMPARISON OF GADRAS SIMULATED AND MEASURED GAMMA RAY SPECTRA

    SciTech Connect

    Jeffcoat, R.; Salaymeh, S.

    2010-06-28

    Gamma-ray radiation detection systems are continuously being developed and improved for detecting the presence of radioactive material and for identifying isotopes present. Gamma-ray spectra, from many different isotopes and in different types and thicknesses of attenuation material and matrixes, are needed to evaluate the performance of these devices. Recently, a test and evaluation exercise was performed by the Savannah River National Laboratory that required a large number of gamma-ray spectra. Simulated spectra were used for a major portion of the testing in order to provide a pool of data large enough for the results to be statistically significant. The test data set was comprised of two types of data, measured and simulated. The measured data were acquired with a hand-held Radioisotope Identification Device (RIID) and simulated spectra were created using Gamma Detector Response and Analysis Software (GADRAS, Mitchell and Mattingly, Sandia National Laboratory). GADRAS uses a one-dimensional discrete ordinate calculation to simulate gamma-ray spectra. The measured and simulated spectra have been analyzed and compared. This paper will discuss the results of the comparison and offer explanations for spectral differences.

  20. The width of gamma-ray burst spectra

    NASA Astrophysics Data System (ADS)

    Axelsson, Magnus; Borgonovo, Luis

    2015-03-01

    The emission processes active in the highly relativistic jets of gamma-ray bursts (GRBs) remain unknown. In this paper, we propose a new measure to describe spectra: the width of the EFE spectrum, a quantity dependent only on finding a good fit to the data. We apply this to the full sample of GRBs observed by Fermi/Gamma-ray Burst Monitor (GBM) and Compton Gamma-ray Observatory/Burst and Transient Source Experiment (BATSE). The results from the two instruments are fully consistent. We find that the median widths of spectra from long and short GRBs are significantly different (chance probability <10-6). The width does not correlate with either duration or hardness, and this is thus a new, independent distinction between the two classes. Comparing the measured spectra with widths of spectra from fundamental emission processes - synchrotron and blackbody radiation - the results indicate that a large fraction of GRB spectra are too narrow to be explained by synchrotron radiation from a distribution of electron energies: for example, 78 per cent of long GRBs and 85 per cent of short GRBs are incompatible with the minimum width of standard slow cooling synchrotron emission from a Maxwellian distribution of electrons, with fast cooling spectra predicting even wider spectra. Photospheric emission can explain the spectra if mechanisms are invoked to give a spectrum much broader than a blackbody.

  1. Qualitative and quantitative validation of the SINBAD code on complex HPGe gamma-ray spectra

    SciTech Connect

    Rohee, E.; Coulon, R.; Normand, S.; Carrel, F.; Dautremer, T.; Barat, E.; Montagu, T.; Jammes, C.

    2015-07-01

    Radionuclides identification and quantification is a serious concern for many applications as safety or security of nuclear power plant or fuel cycle facility, CBRN risk identification, environmental radioprotection and waste measurements. High resolution gamma-ray spectrometry based on HPGe detectors is a performing solution for all these topics. During last decades, a great number of software has been developed to improve gamma spectra analysis. However, some difficulties remain in the analysis when photoelectric peaks are folded together with a high ratio between theirs amplitudes, when the Compton background is much larger compared to the signal of a single peak and when spectra are composed of a great number of peaks. This study deals with the comparison between conventional methods in radionuclides identification and quantification and the code called SINBAD ('Spectrometrie par Inference Non parametrique Bayesienne Deconvolutive'). For many years, SINBAD has been developed by CEA LIST for unfolding complex spectra from HPGe detectors. Contrary to conventional methods using fitting procedures, SINBAD uses a probabilistic approach with Bayesian inference to describe spectrum data. This conventional fitting method founded for example in Genie 2000 is compared with the nonparametric SINBAD approach regarding some key figures of merit as the peak centroid evaluation (identification) and peak surface evaluation (quantification). Unfriendly cases are studied for nuclides detection with closed gamma-rays energies and high photoelectric peak intensity differences. Tests are performed with spectra from the International Atomic Energy Agency (IAEA) for gamma spectra analysis software benchmark and with spectra acquired at the laboratory. Results show that SINBAD and Genie 2000 performances are quite similar with sometimes best results for SINBAD with the important difference that to achieve same performances the nonparametric method is user-friendly compared to the

  2. Nature of the Pygmy Resonance in Continuous Gamma-Spectra

    SciTech Connect

    Rekstad, J; Siem, S; Bernstein, L; Schiller, A; Garrett, P; Nelson, R; Guttormsen, M; Algin, E; Voinov, A

    2003-12-01

    Two-step-cascade spectra of the {sup 171}Yb(n, {gamma}{gamma}){sup 172}Yb reaction have been measured using thermal neutrons. They are compared to calculations based on experimental values of the level density and radiative strength function obtained from the {sup 173}Yb({sup 3}He,{alpha}{gamma}){sup 172}Yb reaction. The multipolarity of a 6.5(15) {mu}{sub N}{sup 2} resonance at 3.3(1) MeV in the strength function is determined to be M1 by this comparison.

  3. Formation of cyclotron lines in gamma-ray burst spectra

    NASA Technical Reports Server (NTRS)

    Alexander, S. G.; Meszaros, P.

    1989-01-01

    A transmission model of gamma-ray burst sources is studied using the relativistic QED magnetic-resonant opacities including multiple photon scattering, incorporated into a discrete-ordinate radiative-transport scheme. The physics of the cyclotron line-producing region is discussed in general, and the expected line profiles, relative harmonic strengths, and polarizations are indicated under various conditions. The calculated spectra for these models show good agreement with the spectra reported from Ginga for GB 880205 and GB 870303.

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

    PubMed

    Korun, M; Vodenik, B; Zorko, B

    2017-03-01

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

  5. Features in the spectra of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Stanek, Krzysztof Z.; Paczynski, Bohdan; Goodman, Jeremy

    1993-01-01

    Gravitational lensing of cosmological gamma-ray bursts by objects in the mass range about 10 exp 17 to 10 exp 20 g (femtolensing) may introduce complicated interference patterns that might be interpreted as absorption or emission lines in the bursts' spectra. This phenomenon, if detected, may be used as a unique probe of dark matter in the universe. The BATSE spectral data should allow one to detect such spectral features or to put significant upper limits on the cosmic density of a dark matter component that may be in the femtolensing range. Software to generate theoretical spectra has been developed, and it is accessible over the computer network with anonymous ftp.

  6. Gamma spectrometry of the minor bodies of the solar system

    SciTech Connect

    Surkov, Yu.A.; Moskaleva, L.P.; Manvelyan, O.S.

    1987-01-01

    The authors investigate the possibility of determining the elemental composition of the surfaces of minor bodies of the solar system (asteroids, the Martian satellites Phobos and Deimos, etc.) using spacecraft-based ..gamma..-spectrometry. The dependence of ..gamma..-photon flux on altitude above the body was calculated for body radii from 13 to 500 km. Estimates were made of the sensitivity of the determination of basic rock-forming elements with respect to changes in geometry of a factor of two, using ..gamma..-spectrometry with a 100 mm by 100 mm crystal of NaI(Tl). Finally, the time required to determine the stipulated characteristic ..gamma..-radiation of surface rocks with the given precision was derived as a function of altitude.

  7. 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.

  8. Magnetic photon splitting and gamma ray burst spectra

    NASA Technical Reports Server (NTRS)

    Baring, Matthew G.

    1992-01-01

    The splitting of photons into two photons becomes both possible and significant in magnetic fields in excess of 10(exp 12) Gauss. Below the threshold energy, 2m sub e c(exp 2) for single photon pair production, splitting can be an astronomically observable phenomenon evident in gamma ray burst spectra. In such circumstances, it was found that magnetic photon splitting reprocesses the gamma ray burst continuum by degrading the photon energy, with a net effect that is quite similar to pair cascade reprocessing of the spectrum. Results are presented for the spectral modifications due to splitting, taking into account the different probabilities for splitting for different polarization modes. Unpolarized and polarized pair cascade photon spectra form the input spectra for the model, which calculates the resulting splitting reprocessed spectra numerically by solving the photon kinetic equations for each polarization mode. This inclusion of photon polarizations is found to not alter previous predictions that splitting produce a significant flattening of the hard X ray continuum and a bump at MeV energies below a pair production turnover. The spectrum near the bump is always strongly polarized.

  9. New shield for gamma-ray spectrometry

    NASA Technical Reports Server (NTRS)

    Brar, S. S.; Gustafson, P. F.; Nelson, D. M.

    1969-01-01

    Gamma-ray shield that can be evacuated, refilled with a clean gas, and pressurized for exclusion of airborne radioactive contaminants effectively lowers background noise. Under working conditions, repeated evacuation and filling procedures have not adversely affected the sensitivity and resolution of the crystal detector.

  10. Energetic solar electron spectra and gamma-ray observations

    NASA Astrophysics Data System (ADS)

    Dröge, Wolfgang

    1996-06-01

    We analyze solar energetic electron events measured with particle detectors on board of the ISEE-3 (ICE) and Helios 1 and 2 spacecraft. Energy spectra in the range 0.1 to tens of MeV are generated applying the results of a careful re-examination of the electron response function of the instruments. The spectral shapes of events observed simultaneously, among them five on all three s/c, are in very good agreement inspite of the sometimes considerable difference in azimuthal and radial distances of the s/c with respect to the flare. These findings suggest that transport processes at the Sun and in the interplanetary medium depend only weakly on the electron energy and that the observed spectra are representative of the accelerated electron spectra at the Sun. A comparison of the electron spectra with SMM gamma-ray spectra gives evidence for the existence of different acceleration and emission mechanism in flares with long (LDEs) and short duration (SDEs) soft X-ray emission.

  11. Demonstrating the European capability for airborne gamma spectrometry: results from the eccomags exercise.

    PubMed

    Sanderson, D C W; Cresswell, A J; Scott, E M; Lang, J J

    2004-01-01

    Airborne gamma spectrometry (AGS) is being increasingly recognised as an important means for mapping environmental radioactivity in emergency response. Progress has been made in recent years towards methodological convergence and cooperation between European teams. Recently, an international comparison was undertaken in SW Scotland in 2002 to evaluate AGS and ground-based methods. Teams from 18 institutions in 10 European countries attended, collecting some 140,000 AGS spectra, with 750 laboratory gamma spectrometry analyses and 120 in situ observations from the ground sites. Comparisons between AGS and ground-based methods have confirmed the validity of AGS protocols. A composite mapping task, where AGS teams recorded data over adjacent parts of a 90 x 40 km2 area within a few days, confirmed the ability of teams to work together in an effective manner. This paper provides a summary of the results of the exercise. These demonstrate the operational capabilities of European AGS teams and confirm the quantitative nature of the method.

  12. 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.

  13. Cyclotron scattering lines in gamma-ray burst spectra

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.; Preece, Robert D.

    1989-01-01

    If cyclotron scattering, rather than absorption, is responsible for the line features observed recently in two gamma-ray burst spectra (Murakami et al., 1988), then the second and higher harmonics are due to resonant scattering events that excite the electron to Landau levels above the ground state. Here, relativistic Compton scattering cross sections are used to estimate the expected ratio of third to second harmonics in the presence of Doppler broadening. At the field strength (1.7 TG) required to give first and second harmonics at 19 keV and 38 keV, there should be no detectable third harmonic in the spectrum.

  14. The Extragalactic Background Light and Absorption in Gamma Ray Spectra

    NASA Astrophysics Data System (ADS)

    Gilmore, Rudy C.

    2008-03-01

    Recent state-of-the-art semi-analytic models (SAMs) can now accurately model the history of galaxy formation and evolution. These SAMs utilize a 'forward evolution' approach and include all of the important processes for determining photon emission from galaxies, such as cooling and shock heating of gas, galaxy mergers, star formation and aging, supernova and AGN feedback, and the reprocessing of light by dust. I will be presenting our group's latest prediction of the extra-galactic background light based on this work and will discuss the implications for the attenuation of VHE gamma rays from distant sources due to pair-production. These results will be compared to recent limits placed on the EBL by observations of GeV and TeV blazar spectra by experiments such as H.E.S.S., MAGIC and VERITAS. The implications for reconstructing the intrinsic spectra of distant blazars will be addressed.

  15. 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

  16. 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.

  17. Gamma-ray Output Spectra from 239 Pu Fission

    SciTech Connect

    Ullmann, John

    2015-05-25

    Gamma-ray multiplicities, individual gamma-ray energy spectra, and total gamma energy spectra following neutron-induced fission of 239Pu were measured using the DANCE detector at Los Alamos. Corrections for detector response were made using a forward-modeling technique based on propagating sets of gamma rays generated from a paramaterized model through a GEANT model of the DANCE array and adjusting the parameters for best fit to the measured spectra. The results for the gamma-ray spectrum and multiplicity are in general agreement with previous results, but the measured total gamma-ray energy is about 10% higher. A dependence of the gamma-ray spectrum on the gamma-ray multplicity was also observed. Global model calculations of the multiplicity and gamma energy distributions are in good agreement with the data, but predict a slightly softer total-energy distribution.

  18. The low energy spectra of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Bussard, R. W.; Lamb, F. K.

    1982-01-01

    The implications of observed gamma-ray burst spectra for the physical conditions and geometries of the sources are examined. It is noted that an explanation of the continua in terms of optically thin thermal bremsstrahlung requires a relatively large area but a fairly shallow depth. On the other hand, a spectrum similar to that observed could be produced by rapid flickering of sources with less extreme geometries if each flicker emits a Comptonized thermal spectrum. Either field inhomogeneities or plasma motions are required to interpret the low energy features as cyclotron extinction. An alternative explanation is photoelectric absorption by heavy atoms; this requires a field strength high enough to make one-photon electron positron annihilation possible. Observational tests of these possibilities are proposed

  19. On the Energy Spectra of Individual Terrestrial Gamma ray Flashes

    NASA Astrophysics Data System (ADS)

    Mailyan, B. G.; Briggs, M. S.; Cramer, E. S.; Connaughton, V.; Dwyer, J. R.; Fitzpatrick, G.

    2015-12-01

    The Fermi Gamma-ray Burst Monitor (GBM) receives enough photons from some TGFs that spectral fitting of individual TGFs is possible. Previous TGF spectral fits relied upon summing the data from many TGFs. However, this spectral analysis of individual GBM TGFs is difficult because the number of photons is only adequate and because the extreme intensity of TGFs requires the analysis to correct for spectral distortions caused by pulse pileup. For each TGF in the sample, we compare Monte Carlo simulated TGF spectra to the observed detector counts. For each comparison, the best fit intensity is found, including correcting the predicted spectrum for pulse pileup. Using likelihood, we determine which of the simulations are consistent with each TGF, thus constraining the properties (e.g., altitude, beam width, etc.) of the TGF.

  20. Gamma-Ray Bursts, Collisionless Shocks and Synthetic Spectra

    NASA Astrophysics Data System (ADS)

    Hededal, Christian

    2005-06-01

    The radiation from afterglows of gamma-ray bursts (GRB) is generated in collisionless plasma shocks. The two main ingredients behind the radiation are high-energy, non-thermal electrons and a strong magnetic field. I argue that in order to make the right conclusions about gamma-ray burst and afterglow parameters from observations, it is crucial to have a firm understanding of the microphysics of collisionless shock. I present the results of self-consistent, three-dimensional particle-in-cell computational simulations of the collision of weakly magnetized plasma shells: The experiments show how a plasma instability generates a magnetic field in the shock. The field has strength up to percents of the equipartition value. The experiments also reveal a new, non-thermal electron acceleration mechanism that differs substantially from Fermi acceleration. Finally, I present the results from a new numerical tool that enables us to extract synthetic radiation spectra directly from the experiments. The preliminary results differ from synchrotron radiation but are consistent with GRB afterglow observations. I conclude that strong magnetic field generation, non-thermal particle acceleration and the emission of radiation that is consistent with GRB afterglow observations, are all unavoidable consequences of the collision between two relativistic plasma shells.

  1. Martian Provinces From Neutron and Gamma Spectrometry

    NASA Astrophysics Data System (ADS)

    Gasnault, O.

    2003-12-01

    This study intends to identify and characterize the major provinces at the surface of Mars. We used the data from the Neutron Spectrometer (NS) and the Gamma-ray Sensor Head (GSH) aboard Mars Odyssey. NS data help to define broad provinces that should present uniform composition. GSH data can be then summed over these provinces to derive their chemical compositions with good statistics. At the present stage, we manage to conduct the first step that identifies the provinces, while the second step is still under progress to characterize them. Variations in NS epithermal and fast neutron data are largely dominated by the distribution of hydrogen and carbon at the surface or at shallow depths. Neutrons are also affected by the presence of an atmosphere. To limit these effects, we chose frost free data (i.e. measured during the summer at high-latitudes), between -60 and +60 degrees latitude, and corrected for atmospheric thickness (normalization to 16 g/cm2). On the other hand, it has been demonstrated that neutron fluxes can be used as a proxy for composition: thermal neutrons are strongly attenuated by absorbing elements such as iron, titanium, chlorine, gadolinium, and samarium; on the contrary, the fast neutron flux increases in presence of high-atomic mass elements such as iron or titanium. For a dry and airless body it is known that the ratio of epithermal over fast neutron counts is correlated to the ratio of thermal over fast neutron counts. This correlation leads to a unique parameter, which characterizes the various soil compositions. A similar behaviour has been observed within our subset of NS data. Effects of hydrogen and carbon are quite obvious, allowing us to focus on secondary components, which are driven by soil composition. From there, we derived four provinces besides the poles. The first province is made of H-rich equatorial regions (Arabia Terra and south of Lucus Planum). The second and third provinces are found north and south of the crustal

  2. Broadband turbulent spectra in gamma-ray burst light curves

    SciTech Connect

    Van Putten, Maurice H. P. M.; Guidorzi, Cristiano; Frontera, Filippo

    2014-05-10

    Broadband power density spectra offer a window to understanding turbulent behavior in the emission mechanism and, at the highest frequencies, in the putative inner engines powering long gamma-ray bursts (GRBs). We describe a chirp search method alongside Fourier analysis for signal detection in the Poisson noise-dominated, 2 kHz sampled, BeppoSAX light curves. An efficient numerical implementation is described in O(Nnlog n) operations, where N is the number of chirp templates and n is the length of the light-curve time series, suited for embarrassingly parallel processing. For the detection of individual chirps over a 1 s duration, the method is one order of magnitude more sensitive in signal-to-noise ratio than Fourier analysis. The Fourier-chirp spectra of GRB 010408 and GRB 970816 show a continuation of the spectral slope with up to 1 kHz of turbulence identified in low-frequency Fourier analysis. The same continuation is observed in an average spectrum of 42 bright, long GRBs. An outlook on a similar analysis of upcoming gravitational wave data is included.

  3. Airborne gamma spectrometry--towards integration of European operational capability.

    PubMed

    Toivonen, Harri

    2004-01-01

    Airborne gamma spectrometry is an excellent tool for finding out in a timely manner the extent and magnitude of the dispersion of radioactive materials resulting from a nuclear disaster. To utilise existing European airborne monitoring capabilities for multilateral assistance in an accident is a complex administrative and technical matter. Several international exercises have been organised demonstrating the capability to cooperate. However, efficient mutual assistance between European countries requires conceptual work, standards and harmonisation of software. A unified radiological vocabulary and data exchange format in XML need to be developed. A comprehensive database is essential for data assimilation. An operations centre is needed for management and planning of surveys.

  4. Gamma ray spectrometry of LDEF samples at SRL

    NASA Technical Reports Server (NTRS)

    Winn, Willard G.

    1992-01-01

    A total of 31 samples from the Long Duration Exposure Facility (LDEF), including materials of aluminum, vanadium, and steel trunnions were analyzed by ultra-low-level gamma spectrometry. The study quantified particle induced activations of Na-22, Sc-46, Cr-51, Mn-54, Co-56, Co-57, Co-58, and Co-60. The samples of trunnion sections exhibited increasing activity toward the outer end of the trunnion and decreasing activity toward its radial center. The trunnion sections did not include end pieces, which were reported to collect noticeable Be-7 on their leading surfaces. No significant Be-7 was detected in the samples analyzed.

  5. In-situ gamma spectrometry in environmental monitoring.

    PubMed

    Kluson, J

    2010-01-01

    In-situ gamma spectrometry (scintillation or semiconductor) can be used effectively for monitoring natural and man-made radionuclide concentrations, together with the corresponding photon fields, in the environment and in workplaces. It is applied in operational and emergency monitoring of nuclear facilities, waste storage facilities and the uranium industry, in radioactive contamination measurements and mapping, environmental, radiohygienic and radiation safety studies, etc. Methods for processing and interpreting data, experimental techniques (ground or airborne arrangement), calibration and verification and examples of applications are discussed in this paper.

  6. Initial recommendations for restricting gamma-ray spectrometry measurements of radionuclides for on-site inspections

    SciTech Connect

    Buckley, W F; Kreek, S A; Wild, J F

    1998-11-06

    The US paper "Radionuclide Sampling, Sample Handling and Analytical Laboratory Equipment for Comprehensive Test Ban Treaty On-Site Inspections," CTBT/PC/V/OSI/WSII/PR/29 identified the radionuclides of interest to an OS1 as 144Ce, 147Nd, 141Ce, 149Ba140La), 95 Zr(95Nb), 131mXe, 133mXe, 133gXe, 135gXe, and 37Ar. All of these nuclides (except 37Ar) can be measured via some form of conventional or coincidence-based gamma-ray spectrometry. The non-gaseous radionuclides [144Ce, 147Nd, 141Ce, 140Ba(140La), and 95Zr(95Nb)] can be measured via conventional high-resolution gamma-ray spectrometry using a shielded, high-purity germanium (HPGe) detector. The gaseous radionuclides 131mXe, 133mXe, 133gXe, and 135gXe are best measured (after separation from their homologous elements) via a gamma & beta/electron coincidence technique such as that described in CTBT/WGB/TL-11/5 which could utilize either a HPGe or low-resolution (NaI(TI)) gamma-ray spectrometer to detect the gamma-ray/x-ray and a plastic scintillator to detect the beta particle/electron from the decay of the various Xe isotopes. The US paper CTBT/PC/V/IOSI/WSII/PR/29 (and other papers) identified a need to limit the information that can be extracted from high-resolution gamma-ray spectra to ensure that only information relevant to an OSI is accessible. The term "blinding" has been used to describe the need to limit the information available to the Inspection Team from the high-resolution gamma-ray measurement. A better term is "measurement restriction"; the need for restricting the information is particularly relevant to conventional high-resolution gamma-ray spectrometry measurements, but not to the gamma & beta/electron coincidence-type measurements

  7. Monitoring radioactive plumes by airborne gamma-ray spectrometry

    SciTech Connect

    Grasty, R.L.; Hovgaard, J.; Multala, J.

    1996-06-01

    Airborne gamma-ray spectrometer surveys using large volume sodium-iodide detectors are routinely flown throughout the world for mineral exploration and geological mapping. Techniques have now been developed to detect and map man-made sources of radiation. In Canada, airborne gamma-rays surveys have been flown around nuclear reactors to map {sup 41}Ar plumes from nuclear reactors and to calculate the dose rate at ground level. In May 1986, the Finnish Geological survey aircraft flew through a radioactive plume from the Chernobyl nuclear accident. As the aircraft flew through the plume, the aircraft became increasingly contaminated. By measuring the final aircraft contamination, the activity of the plume could be separated from the contamination due to the aircraft. Within 1 h of encountering the plume, the aircraft activity was comparable to the maximum levels found in the plume. From an analysis of the gamma-ray spectra, the concentration of {sup 131}I and {sup 140}La within the plume were calculated as a function of time.

  8. Reconstruction of distribution functions of fast ions and runaway electrons in fusion plasmas using gamma-ray spectrometry with applications to ITER

    NASA Astrophysics Data System (ADS)

    Shevelev, A. E.; Khilkevitch, E. M.; Kiptily, V. G.; Chugunov, I. N.; Gin, D. B.; Doinikov, D. N.; Naidenov, V. O.; Litvinov, A. E.; Polunovskii, I. A.; Contributors, JET-EFDA

    2013-12-01

    Gamma-ray spectrometry on ITER can provide information both on confined fusion alpha particles for optimization of plasma heating and runaway electrons, which is important for safe reactor operations. For the purpose of deconvolution of gamma-ray spectra recorded in fusion plasma experiments the DeGaSum code has been developed. The code can be applied for processing of both spectra of monoenergetic gamma rays, which are born in nuclear reactions produced by alpha particles and other fast ions, and continuous bremsstrahlung spectra generated by runaway electrons in the MeV range in the plasma and reactor structure materials. Gamma-ray spectrometer response functions and bremsstrahlung spectra generated by electrons in the MeV energy range are calculated and used in the DeGaSum code. The deconvolution of the discrete spectra allows the identification of nuclear reactions, which give rise to gamma rays, and the calculation of their intensities. By applying the code for continuous hard x-ray spectra, the runaway electron energy distribution can be inferred. It can provide the maximal energy of runaway electrons with accuracy, which satisfies the ITER project requirements. The code has been used for processing of spectra recorded in JET experiments. An application of the deconvolution technique for gamma-ray emission measurements on ITER is discussed.

  9. Guide to plutonium isotopic measurements using gamma-ray spectrometry

    SciTech Connect

    Lemming, J.F.; Rakel, D.A.

    1982-08-26

    Purpose of this guide is to assist those responsible for plutonium isotopic measurements in the application of gamma-ray spectrometry. Objectives are to promote an understanding of the measurement process, including its limitations and applicability, by reviewing the general features of a plutonium spectrum and identifying the quantities which must be extracted from the data; to introduce state-of-the-art analysis techniques by reviewing four isotopic analysis packages and identifying their differences; to establish the basis for measurement control and assurance by discussing means of authenticating the performance of a measurement system; and to prepare for some specific problems encountered in plutonium isotopic analyses by providing solutions from the practical experiences of several laboratories. 29 references, 12 figures, 17 tables.

  10. MCRaT Simulations of Long Gamma Ray Burst Spectra and Light Curves

    NASA Astrophysics Data System (ADS)

    Parsotan, T.; Lazzati, D.

    2016-10-01

    We present the results of the Monte Carlo Radiation Transfer, MCRaT, simulations of long gamma ray bursts from a variety of stellar progenitors and jet properties, including variable engines. We also compare the resulting spectra to observed data.

  11. High-resolution gamma-ray spectrometry in uranium exploration

    USGS Publications Warehouse

    Moxham, Robert M.; Tanner, Allan B.

    1977-01-01

    Sedimentary-type uranium deposits accumulate at favorable sites along a migration path which may be kilometers in length. Their source is a large volume of rock from which the uranium has been leached. The geochemical mobilities and half lives of uranium and its daughter products vary widely so that they are transported from the source rocks, at different rates, along the migration path to their ultimate site. The radioactive disequilibrium resulting from this process has been well documented in the immediate vicinity of ore deposits, and disequilibrium is commonly recorded on gamma-ray logs up the hydraulic gradient from uranium ore. Little is known about the state of secular equilibrium in the leached host rocks, which often represent the only part of the migration path that is at or near the surface and is thus most accessible to the exploration geophysicist. High-resolution gamma-ray spectrometry provides a means of investigating the disequilibrium associated with uranium leaching and migration. Direct measurement of uranium can be made by this method, and the equivalent weight percents can be determined for six of the seven daughter-product decay groups that characterize the state of radioactive equilibrium. The technique has been used quantitatively in laboratory studies, where the results compare favorably with radiochemical analyses; field experiments suggest that semi-quantitative data may be obtained at the outcrop.

  12. BATSE Observations of Gamma-Ray Burst Spectra. Part 3; Low-Energy Behavior of Time-Averaged Spectra

    NASA Technical Reports Server (NTRS)

    Preece, R. D.; Briggs, M. S.; Pendleton, G. N.; Paciesas, W. S.; Matteson, J. L.; Band, D. L.; Skelton, R. T.; Meegan, C. A.

    1996-01-01

    We analyze time-averaged spectra from 86 bright gamma-ray bursts from the first 5 years of the Burst And Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory to determine whether the lowest energy data are consistent with a standard spectra form fit to the data at all energies. The BATSE Spectroscopy Detectors have the capability to observe photons as low as 5 keV. Using the gamma-ray burst locations obtained with the BATSE Large Area Detectors, the Spectroscopy Detectors' low-energy response can be modeled accurately. This, together with a postlaunch calibration of the lowest energy Spectroscopy Detector discriminator channel, which can lie in the range 5-20 keV, allows spectral deconvolution over a broad energy range, approx. 5 keV to 2 MeV. The additional coverage allows us to search for evidence of excess emission, or for a deficit, below 20 keV. While no burst has a significant (greater than or equal to 3 sigma) deficit relative to a standard spectra model, we find that 12 bursts have excess low-energy emission, ranging between 1.2 and 5.8 times the model flux, that exceeds 5 sigma in significance. This is evidence for an additional low-energy spectral component in at least some bursts, or for deviations from the power-law spectral form typically used to model gamma-ray bursts at energies below 100 keV.

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

    SciTech Connect

    Hoots, S.; Wadsworth, D.

    1984-06-01

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

  14. Computer simulation of gamma-ray spectra from semiconductor detectors

    NASA Astrophysics Data System (ADS)

    Lund, Jim C.; Olschner, Fred; Shah, Kanai S.

    1992-12-01

    Traditionally, researchers developing improved gamma ray detectors have used analytical techniques or, rarely, computer simulations to predict the performance of new detectors. However, with the advent of inexpensive personal computers, it is now possible for virtually all detector researchers to perform some form of numerical computation to predict detector performance. Although general purpose code systems for semiconductor detector performance do not yet exist, it is possible to perform many useful calculations using commercially available, general purpose numerical software packages (such as `spreadsheet' programs intended for business use). With a knowledge of the rudimentary mechanics of detector simulation most researchers, including those with no programming skills, can effectively use numerical simulation methods to predict gamma ray detector performance. In this paper we discuss the details of the numerical simulation of gamma ray detectors with the hope of communicating the simplicity and effectiveness of these methods. In particular, we discuss the steps involved in simulating the pulse height spectrum produced by a semiconductor detector.

  15. Cadium-Zinc-Telluride (CZT) Gamma Ray Spectrometry

    SciTech Connect

    William Quam

    2001-09-01

    This report describes CZT crystals and their use in large arrays for generation of gamma ray spectra. Laboratory spectra will be shown together with spectra accumulated by various battery powered portable instruments (see Appendix A). One of these portable instruments was specifically constructed to minimize power consumption and yet provide reasonable isotope identification capability. Detailed data will be presented covering gamma energy resolution, gamma peak shapes, system background, and detector efficiency. Nearly all data were taken with very small crystals of CZT; cubes 5 mm on a side. A few spectra will be presented from cylindrical crystals of about the same size (see Appendix A). The small crystal size leads to low counting rates and extended counting times for reliable isotope identification. We have addressed this problem by using arrays of CZT crystals, initially two crystals and, at present, arrays of eight crystals. Data will be shown relating spectral parameters for these two arrays. System MDA is one way of combining resolution, efficiency, and background that will enable direct comparison of various detector types for individual isotope identification. We have calculated the MDA for an early dual crystal array and the current eight crystal array. Data derived from each array will be presented. In addition, it is possible to extrapolate the MDA methodology to much larger arrays. A 32-crystal array is under construction and extrapolations to 256 and 1024 crystals are considered possible. Estimated MDA values for these larger arrays are also presented. Several 8-crystal arrays have been constructed and versions have been incorporated into portable instruments. Descriptions of these small instruments are given covering physical size, weight, and general configuration. These instruments have been tested for shock and temperature effects and data will be presented on the results of these tests. The MDA concept will also allow extrapolation to large

  16. Use of airborne gamma-ray spectrometry for kaolin exploration

    NASA Astrophysics Data System (ADS)

    Tourlière, B.; Perrin, J.; Le Berre, P.; Pasquet, J. F.

    2003-08-01

    Airborne gamma-ray spectrometry was used to define targets with kaolin potential in the Armorican Massif of Brittany, France. This exploration method is based on the principle that kaolinite, an aluminosilicate clay mineral constituting kaolin, is formed by the hydrolysis of potash feldspar with the elimination of potassium. Therefore, potassium contrast between favourable host-rock such as a leucogranite and kaolin occurrence is likely a significant pathfinder. As the relationship between the potassium-40 recorded by an airborne gamma-ray spectrometer and total potassium is constant, such data provide us a direct measurement of the potassium content of the ground flown over. Our study tested this by calculating, for each geological unit, the difference between the measured and average potassium content calculated for a given geological formation. The study was based on (i) a recent (1998) high-definition airborne geophysical survey over the Armorican Massif undertaken on behalf of the French Government, and (ii) new geological compilation maps covering the same region. Depleted zones, where the measured potassium is less than the average potassium content calculated target areas with high potential of containing kaolin, provided that the unit was originally rich in potash feldspar. By applying this method to the entire Armorican Massif, it was possible to identify 150 potassium-depleted zones, including 115 that were subjected to rapid field checks and 36 that contained kaolin (21 new discoveries). This method, which is both safe for the environment and easy to use, is therefore a good tool for rapidly defining targets with kaolin potential at a regional scale. The method may also have possibilities in exploring for other types of deposit characterised by an enrichment or depletion in U, K and/or Th.

  17. Demonstration of lightweight gamma spectrometry systems in urban environments.

    PubMed

    Cresswell, A J; Sanderson, D C W; Harrold, M; Kirley, B; Mitchell, C; Weir, A

    2013-10-01

    Urban areas present highly complex radiation environments; with small scale features resulting from different construction materials, topographic effects and potential anthropogenic inputs from past industrial activity or other sources. Mapping of the radiation fields in urban areas allows a detailed assessment of exposure pathways for the people who live and work there, as well as locating discrete sources of activity that may warrant removal to mitigate dose to the general public. These areas also present access difficulties for radiometric mapping using vehicles or aircraft. A lightweight portable gamma spectrometry system has been used to survey sites in the vicinity of Glasgow to demonstrate the possibilities of radiometric mapping of urban areas, and to investigate the complex radiometric features such areas present. Variations in natural activity due to construction materials have been described, the presence of (137)Cs used to identify relatively undisturbed ground, and a previously unknown NORM feature identified. The effect of topographic enclosure on measurements of activity concentration has been quantified. The portable system is compared with the outputs that might be expected from larger vehicular or airborne systems. For large areas airborne surveys are the most cost effective approach, but provide limited spatial resolution, vehicular surveys can provide sparse exploratory data rapidly or detailed mapping of open areas where off-road access is possible. Backpack systems are ideally suited to detailed surveys of small areas, especially where vehicular access is difficult.

  18. PWR and BWR spent fuel assembly gamma spectra measurements

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  19. PWR and BWR spent fuel assembly gamma spectra measurements

    SciTech Connect

    Vaccaro, S.; Tobin, Stephen J.; Favalli, Andrea; Grogan, Brandon R.; Jansson, Peter; Liljenfeldt, Henrik; Mozin, Vladimir; Hu, Jianwei; Schwalbach, P.; Sjoland, A.; Trellue, Holly; Vo, D.

    2016-07-17

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

  20. PWR and BWR spent fuel assembly gamma spectra measurements

    DOE PAGES

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

    2016-07-17

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

  1. Waste Characterization Using Gamma Ray Spectrometry with Automated Efficiency Optimization - 13404

    SciTech Connect

    Bosko, A.; Venkataraman, R.; Bronson, F.L.; Ilie, G.; Russ, W.R.

    2013-07-01

    Gamma ray spectrometry using High Purity Germanium (HPGe) detectors is commonly employed in assaying radioactive waste streams from a variety of sources: nuclear power plants, Department of Energy (DOE) laboratories, medical facilities, decontamination and decommissioning activities etc. The radioactive material is typically packaged in boxes or drums (for e.g. B-25 boxes or 208 liter drums) and assayed to identify and quantify radionuclides. Depending on the origin of the waste stream, the radionuclides could be special nuclear materials (SNM), fission products, or activation products. Efficiency calibration of the measurement geometry is a critical step in the achieving accurate quantification of radionuclide content. Due to the large size of the waste items, it is impractical and expensive to manufacture gamma ray standard sources for performing a measurement based calibration. For well over a decade, mathematical efficiency methods such as those in Canberra's In Situ Object Counting System (ISOCS) have been successfully employed in the efficiency calibration of gamma based waste assay systems. In the traditional ISOCS based calibrations, the user provides input data such as the dimensions of the waste item, the average density and fill height of the matrix, and matrix composition. As in measurement based calibrations, the user typically defines a homogeneous matrix with a uniform distribution of radioactivity. Actual waste containers can be quite nonuniform, however. Such simplifying assumptions in the efficiency calibration could lead to a large Total Measurement Uncertainty (TMU), thus limiting the amount of waste that can be disposed of as intermediate or low activity level waste. To improve the accuracy of radionuclide quantification, and reduce the TMU, Canberra has developed the capability to optimize the efficiency calibration using the ISOCS method. The optimization is based on benchmarking the efficiency shape and magnitude to the data available in the

  2. Early detection of radioactive fallout by gamma spectrometry.

    PubMed

    Aage, H K; Korsbech, U; Bargholz, K

    2003-01-01

    Radioactive fallout should be detected as early as possible. A new and efficient method for detection of low-level irradiation from manmade radioactivity is developed. Radiation abnormalities are detectable down to air kerma rates of 0.5 to 1.0 nGy h(-1) for 137Cs and even lower for 131I. For multi-gamma energy radioactivity the detection level is 2.6-3.5 nGy h(-1). A standard NaI detector and a 512-channel analyser are used together with noise adjusted singular value decomposition (NASVD). Statistical noise is removed and the measured spectra are reproduced using spectral components produced by NASVD. Stripping is not used and false alarms due to washout of atmospheric radon progeny are almost eliminated. Detection levels and the criteria for setting warning and alarm levels are discussed. The method may also be useful in other situations, for example where low-level signals from radioactive sources need to be detected.

  3. A broadband gamma-ray spectrometry using novel unfolding algorithms for characterization of laser wakefield-generated betatron radiation

    SciTech Connect

    Jeon, Jong Ho Nakajima, Kazuhisa Pathak, Vishwa Bandhu; Cho, Myung Hoon; Yoo, Byung Ju; Shin, Kang Woo; Kim, Hyung Taek; Sung, Jae Hee; Lee, Seung Ku; Choi, Il Woo; Rhee, Yong Joo; Shin, Jung Hun; Jo, Sung Ha; Hojbota, Calin; Cho, Byeoung Ick; Nam, Chang Hee

    2015-12-15

    We present a high-flux, broadband gamma-ray spectrometry capable of characterizing the betatron radiation spectrum over the photon energy range from 10 keV to 20 MeV with respect to the peak photon energy, spectral bandwidth, and unique discrimination from background radiations, using a differential filtering spectrometer and the unfolding procedure based on the Monte Carlo code GEANT4. These properties are experimentally verified by measuring betatron radiation from a cm-scale laser wakefield accelerator (LWFA) driven by a 1-PW laser, using a differential filtering spectrometer consisting of a 15-filter and image plate stack. The gamma-ray spectra were derived by unfolding the photostimulated luminescence (PSL) values recorded on the image plates, using the spectrometer response matrix modeled with the Monte Carlo code GEANT4. The accuracy of unfolded betatron radiation spectra was assessed by unfolding the test PSL data simulated with GEANT4, showing an ambiguity of less than 20% and clear discrimination from the background radiation with less than 10%. The spectral analysis of betatron radiation from laser wakefield-accelerated electron beams with energies up to 3 GeV revealed radiation spectra characterized by synchrotron radiation with the critical photon energy up to 7 MeV. The gamma-ray spectrometer and unfolding method presented here facilitate an in-depth understanding of betatron radiation from LWFA process and a novel radiation source of high-quality photon beams in the MeV regime.

  4. A broadband gamma-ray spectrometry using novel unfolding algorithms for characterization of laser wakefield-generated betatron radiation.

    PubMed

    Jeon, Jong Ho; Nakajima, Kazuhisa; Kim, Hyung Taek; Rhee, Yong Joo; Pathak, Vishwa Bandhu; Cho, Myung Hoon; Shin, Jung Hun; Yoo, Byung Ju; Hojbota, Calin; Jo, Sung Ha; Shin, Kang Woo; Sung, Jae Hee; Lee, Seung Ku; Cho, Byeoung Ick; Choi, Il Woo; Nam, Chang Hee

    2015-12-01

    We present a high-flux, broadband gamma-ray spectrometry capable of characterizing the betatron radiation spectrum over the photon energy range from 10 keV to 20 MeV with respect to the peak photon energy, spectral bandwidth, and unique discrimination from background radiations, using a differential filtering spectrometer and the unfolding procedure based on the Monte Carlo code GEANT4. These properties are experimentally verified by measuring betatron radiation from a cm-scale laser wakefield accelerator (LWFA) driven by a 1-PW laser, using a differential filtering spectrometer consisting of a 15-filter and image plate stack. The gamma-ray spectra were derived by unfolding the photostimulated luminescence (PSL) values recorded on the image plates, using the spectrometer response matrix modeled with the Monte Carlo code GEANT4. The accuracy of unfolded betatron radiation spectra was assessed by unfolding the test PSL data simulated with GEANT4, showing an ambiguity of less than 20% and clear discrimination from the background radiation with less than 10%. The spectral analysis of betatron radiation from laser wakefield-accelerated electron beams with energies up to 3 GeV revealed radiation spectra characterized by synchrotron radiation with the critical photon energy up to 7 MeV. The gamma-ray spectrometer and unfolding method presented here facilitate an in-depth understanding of betatron radiation from LWFA process and a novel radiation source of high-quality photon beams in the MeV regime.

  5. Recovery and reanalysis of archived airborne gamma spectrometry data from the 1991 Dounreay survey.

    PubMed

    Cresswell, A J

    2012-01-01

    Archived Airborne Gamma Spectrometry (AGS) data from the 1991 NIREX characterisations of Caithness have been recovered. The separate gamma spectrometry and positional data streams for approximately 120,000 measurements have been combined into a single data stream using the European Radiometrics and Spectrometry (ERS) data format. An analysis using working calibration coefficients and spectral stripping procedure has verified that the original survey recorded high quality data. The converted data stream is in a format more accessible to future research use, including evaluation of environmental change in the Caithness region.

  6. An iron absorption model of gamma-ray burst spectra

    NASA Technical Reports Server (NTRS)

    Liang, Edison P.; Kargatis, Vincent E.

    1994-01-01

    Most gamma-ray bursts (GRBs) exhibit deficits of X-rays below approximately 200 keV. Here we consider a spectral model in which the burst source is shielded by an optically thick layer of circumburster material (CBM) rich in iron-group elements whose photoelectric absorption opacity exceeds the Thomson opacity below approximately 120 keV. For power-law distributions of absorption depths along the lines of sight the absorbed spectrum can indeed mimic the typial GRB spectrum. This model predicts that (a) the spectrum should evolve monotonically from hard to soft during each energy release, which is observed in most bursts, especially in fast rise exponential decay bursts; (b) Fe spectral features near 7 keV may be present in some bursts; and (c) the ratio of burst distances to the CBM and to Earth should be approximately 10(exp -11) if the spectral evolution is purely due to Fe stripping by the photons.

  7. Measurement and calculation of characteristic prompt gamma ray spectra emitted during proton irradiation.

    PubMed

    Polf, J C; Peterson, S; McCleskey, M; Roeder, B T; Spiridon, A; Beddar, S; Trache, L

    2009-11-21

    In this paper, we present results of initial measurements and calculations of prompt gamma ray spectra (produced by proton-nucleus interactions) emitted from tissue equivalent phantoms during irradiations with proton beams. Measurements of prompt gamma ray spectra were made using a high-purity germanium detector shielded either with lead (passive shielding), or a Compton suppression system (active shielding). Calculations of the spectra were performed using a model of both the passive and active shielding experimental setups developed using the Geant4 Monte Carlo toolkit. From the measured spectra it was shown that it is possible to distinguish the characteristic emission lines from the major elemental constituent atoms (C, O, Ca) in the irradiated phantoms during delivery of proton doses similar to those delivered during patient treatment. Also, the Monte Carlo spectra were found to be in very good agreement with the measured spectra providing an initial validation of our model for use in further studies of prompt gamma ray emission during proton therapy.

  8. Distribution of iron&titanium on the lunar surface from lunar prospector gamma ray spectra

    SciTech Connect

    Prettyman, T. H.; Feldman, W. C.; Lawrence, David J. ,; Elphic, R. C.; Gasnault, O. M.; Maurice, S.; Moore, K. R.; Binder, A. B.

    2001-01-01

    Gamma ray pulse height spectra acquired by the Lunar Prospector (LP) Gamma-Ray Spectrometer (GRS) contain information on the abundance of major elements in the lunar surface, including O, Si, Ti, Al, Fe, Mg, Ca, K, and Th. With the exception of Th and K, prompt gamma rays produced by cosmic ray interactions with surface materials are used to determine elemental abundance. Most of these gamma rays are produced by inelastic scattering of fast neutrons and by neutron capture. The production of neutron-induced gamma rays reaches a maximum deep below the surface (e.g. {approx}140 g/cm{sup 2} for inelastic scattering and {approx}50 g/cm{sup 2} for capture). Consequently, gamma rays sense the bulk composition of lunar materials, in contrast to optical methods [e.g. Clementine Spectral Reflectance (CSR)], which only sample the top few microns. Because most of the gamma rays are produced deep beneath the surface, few escape unscattered and the continuum of scattered gamma rays dominates the spectrum. In addition, due to the resolution of the spectrometer, there are few well-isolated peaks and peak fitting algorithms must be used to deconvolve the spectrum in order to determine the contribution of individual elements.

  9. The gamma-ray spectra of 5-carbon alkane isomers in the positron annihilation process

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoguang; Zhu, Yinghao; Liu, Yang

    2016-05-01

    The gamma-ray spectra of pentane (C5H12) and its two isomers, i.e., 2-Methylbutane (CH3C(CH3)HC2H5) and 2,2-Dimethylpropane (C(CH3)4) have been studied theoretically in the present work. The recent experimental gamma-ray spectra of these three molecules show that they have the same Doppler shifts, although their molecular structures are dramatically different. In order to reveal why the gamma-ray spectra of these molecules are less sensitive to the molecular structures, the one-dimensional gamma-ray spectra and spherically averaged momentum (SAM) distributions, the two-dimensional angular correlation of annihilation radiation (ACAR), and the three-dimensional momentum distributions of the positron-electron pair are studied. The one-centered momentum distributions of the electrons are found to play more important role than the multi-centered coordinate distributions. The present theoretical predictions have confirmed the experimental findings for the first time. The dominance of the inner valence electrons in the positron-electron annihilation process has also been suggested in the present work.

  10. Effects of axion-photon mixing on gamma-ray spectra from magnetized astrophysical sources

    SciTech Connect

    Hochmuth, Kathrin A.; Sigl, Guenter

    2007-12-15

    Astrophysical {gamma}-ray sources come in a variety of sizes and magnetizations. We deduce general conditions under which {gamma}-ray spectra from such sources would be significantly affected by axion-photon mixing. We show that, depending on strength and coherence of the magnetic field, axion couplings down to {approx}(10{sup 13}GeV){sup -1} can give rise to significant axion-photon conversions in the environment of accreting massive black holes. Resonances can occur between the axion mass term and the plasma frequency term as well as between the plasma frequency term and the vacuum Cotton-Mouton shift. Both resonances and nonresonant transitions could induce detectable features or even strong suppressions in finite energy intervals of {gamma}-ray spectra from active galactic nuclei. Such effects can occur at keV to TeV energies for couplings that are currently allowed by all experimental constraints.

  11. An MS-DOS-based program for analyzing plutonium gamma-ray spectra

    SciTech Connect

    Ruhter, W.D.; Buckley, W.M.

    1989-09-07

    A plutonium gamma-ray analysis system that operates on MS-DOS-based computers has been developed for the International Atomic Energy Agency (IAEA) to perform in-field analysis of plutonium gamma-ray spectra for plutonium isotopics. The program titled IAEAPU consists of three separate applications: a data-transfer application for transferring spectral data from a CICERO multichannel analyzer to a binary data file, a data-analysis application to analyze plutonium gamma-ray spectra, for plutonium isotopic ratios and weight percents of total plutonium, and a data-quality assurance application to check spectral data for proper data-acquisition setup and performance. Volume 3 contains the software listings for these applications.

  12. ON WEAK REDSHIFT DEPENDENCE OF GAMMA-RAY SPECTRA OF DISTANT BLAZARS

    SciTech Connect

    Essey, Warren; Kusenko, Alexander

    2012-05-20

    Line-of-sight interactions of cosmic rays provide a natural explanation of the hard gamma-ray spectra of distant blazars, which are believed to be capable of producing both gamma rays and cosmic rays. For sources with redshifts z {approx}> 0.1, secondary gamma rays produced in cosmic-ray interactions with background photons close to an observer can dominate over primary gamma rays originating at the source. The transition from one component to another is accompanied by a change in the spectral index depending on the source redshift. We present theoretical predictions and show that they agree with the data from Fermi Large Area Telescope. This agreement, combined with the spectral data from Atmospheric Cherenkov Telescopes, provides evidence of cosmic-ray acceleration by active galactic nuclei and opens new opportunities for studying photon backgrounds and intergalactic magnetic fields.

  13. Total Absorption Gamma-ray Spectrometer (TAGS) Intensity Distributions from INL's Gamma-Ray Spectrometry Center

    DOE Data Explorer

    Greenwood, R. E.

    A 252Cf fission-product source and the INL on-line isotope separator were used to supply isotope-separated fission-product nuclides to a total absorption -ray spectrometer. This spectrometer consisted of a large (25.4-cm diameter x 30.5-cm long) NaI(Tl) detector with a 20.3-cm deep axial well in which is placed a 300-mm2 x 1.0-mm Si detector. The spectra from the NaI(Tl) detector are collected both in the singles mode and in coincidence with the B-events detected in the Si detector. Ideally, this detector would sum all the energy of the B- rays in each cascade following the population of daughter level by B- decay, so that the event could be directly associated with a particular daughter level. However, there are losses of energy from attenuation of the rays before they reach the detector, transmission of rays through the detector, escape of secondary photons from Compton scattering, escape of rays through the detector well, internal conversion, etc., and the measured spectra are thus more complicated than the ideal case and the analysis is more complex. Analysis methods have been developed to simulate all of these processes and thus provide a direct measure of the B- intensity distribution as a function of the excitation energy in the daughter nucleus. These data yield more accurate information on the B- distribution than conventional decay-scheme studies for complex decay schemes with large decay energies, because in the latter there are generally many unobserved and observed but unplaced rays. The TAGS data have been analyzed and published [R. E. Greenwood et al., Nucl Instr. and metho. A390(1997)] for 40 fission product-nuclides to determine the B- intensity distributions. [Copied from the TAGS page at http://www.inl.gov/gammaray/spectrometry/tags.shtml]. Those values are listed on this page for quick reference.

  14. 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.

  15. Simulation of gamma-ray spectra for a variety of user-specified detector designs

    NASA Technical Reports Server (NTRS)

    Rester, A. C., Jr.

    1994-01-01

    The gamma-ray spectrum simulation program BSIMUL was designed to allow the operator to follow the path of a gamma-ray through a detector, shield and collimator whose dimensions are entered by the operator. It can also be used to simulate spectra that would be generated by a detector. Several improvements have been made to the program within the last few months. The detector, shield and collimator dimensions can now be entered through an interactive menu whose options are discussed below. In addition, spectra containing more than one gamma-ray energy can now be generated with the menu - for isotopes listed in the program. Adding isotopes to the main routine is also quite easy. Subroutines have been added to enable the operator to specify the material and dimensions of a collimator. This report details the progress made in simulating gamma-ray spectra for a variety of user-specified detector designs. In addition, a short discussion of work done in the related areas of pulse shape analysis and the spectral analysis is included. The pulse shape analysis and spectral analysis work is being performed pursuant to the requirements of contract F-94-C-0006, for the Advanced Research Projects Agency and the U.S. Air Force.

  16. The Dortmund Low Background Facility - Low-background gamma ray spectrometry with an artificial overburden.

    PubMed

    Gastrich, Holger; Gößling, Claus; Klingenberg, Reiner; Kröninger, Kevin; Neddermann, Till; Nitsch, Christian; Quante, Thomas; Zuber, Kai

    2016-06-01

    The Dortmund Low Background Facility is an instrument for low-level gamma ray spectrometry with an artificial overburden of ten meters of water equivalent, an inner shielding, featuring a neutron absorber, and an active muon veto. An integral background count rate between 40keV and 2700keV of (2.528±0.004)counts/(kgmin) enables low-background gamma ray spectrometry with sensitivities in the range of some 10mBq/kg within a week of measurement time.

  17. Inclusive gamma-ray spectra from psi/3095/ and psi-prime/3684/ decays

    NASA Technical Reports Server (NTRS)

    Biddick, C. J.; Burnett, T. H.; Masek, G. E.; Miller, E. S.; Smith, J. G.; Stronski, J. P.; Sullivan, M. K.; Vernon, W.; Badtke, D. H.; Barnett, B. A.

    1977-01-01

    Inclusive gamma-ray experiments were carried out in a e(+)e(-) colliding-beam apparatus with NaI(Tl) arrays as detectors. The inclusive gamma-ray spectra, after cosmic-ray background subtraction, are shown as histograms for the decays of the psi(3095) and psi-prime(3684). The psi spectrum has no significant narrow structure, while the psi-prime spectrum shows at least four peaks. Three major radiative decays of the psi-prime(3684) are found, and their respective branching fractions are computed.

  18. Measurement of Branching Fractions and Mass Spectra of B to K pi pi gamma

    SciTech Connect

    Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Tisserand, V.; Zghiche, A.; Grauges, E.; Palano, A.; Pappagallo, M.; Pompili, A.; Chen, J.C.; Qi, N.D.; Rong, G.; Wang, P.; Zhu, Y.S.; Eigen, G.; Ofte, I.; Stugu, B. /Bergen U. /LBL, Berkeley /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /Bristol U. /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UCLA /UC, Riverside /UC, San Diego /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /Ferrara U. /INFN, Ferrara /Frascati /Genoa U. /INFN, Genoa /Harvard U. /Heidelberg U. /Imperial Coll., London /Iowa U. /Iowa State U. /Orsay, LAL /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT, LNS /McGill U. /Milan U. /INFN, Milan /Mississippi U. /Montreal U. /Mt. Holyoke Coll. /Naples U. /INFN, Naples /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /Paris U., VI-VII /Pennsylvania U. /Perugia U. /INFN, Perugia /Pisa U. /Pisa, Scuola Normale Superiore /INFN, Pisa /Prairie View A-M /Princeton U. /Rome U. /INFN, Rome /Rostock U. /Rutherford /DAPNIA, Saclay /South Carolina U. /SLAC /Stanford U., Phys. Dept. /SUNY, Albany /Tennessee U. /Texas U. /Texas U., Dallas /Turin U. /INFN, Turin /Trieste U. /INFN, Trieste /Valencia U., IFIC /Vanderbilt U. /Victoria U. /Warwick U. /Wisconsin U., Madison /Yale U.

    2005-07-12

    The authors present a measurement of the partial branching fractions and mass spectra of the exclusive radiative penguin processes B {yields} K{pi}{pi}{gamma} in the range m{sub K{pi}{pi}} < 1.8 GeV/c{sup 2}. They reconstruct four final states: K{sup +}{pi}{sup -}{pi}{sup +}{gamma}, K{sup +}{pi}{sup -}{pi}{sup 0}{gamma}, K{sub S}{sup 0}{pi}{sup -}{pi}{sup +}{gamma}, and K{sub S}{sup 0}{pi}{sup +}{pi}{sup 0}{gamma}, where K{sub S}{sup 0} {yields} {pi}{sup +}{pi}{sup -}. Using 232 million e{sup +}e{sup -} {yields} B{bar B} events recorded by the BABAR experiment at the PEP-II asymmetric-energy storage ring, they measure the branching fractions {Beta}(B{sup +} {yields} K{sup +}{pi}{sup -}{pi}{sup +}{gamma}) = (2.95 {+-} 0.13(stat.) {+-} 0.20(syst)) x 10{sup -5}, {Beta}(B{sup 0} {yields} K{sup +}{pi}{sup -}{pi}{sup 0}{gamma}) = (4.07 {+-} 0.22(stat.) {+-} 0.31(syst.)) x 10{sup -5}, {Beta}(B{sup 0} {yields} K{sup 0}{pi}{sup +}{pi}{sup -}{gamma}) = (1.85 {+-} 0.21(stat.) {+-} 0.12(syst.)) x 10{sup -5}, and {Beta}(B{sup +} {yields} K{sup 0}{pi}{sup +}{pi}{sup 0}{gamma}) = (4.56 {+-} 0.42(stat.) {+-} 0.31(syst.)) x 10{sup -5}.

  19. PHASE-AVERAGED SPECTRA AND LUMINOSITIES OF GAMMA-RAY EMISSIONS FROM YOUNG ISOLATED PULSARS

    SciTech Connect

    Li, X.; Jiang, Z. J.; Zhang, L.

    2013-03-10

    We study the phase-averaged spectra and luminosities of {gamma}-ray emissions from young, isolated pulsars within a revised outer gap model. In the revised version of the outer gap, there are two possible cases for the outer gaps: the fractional size of the outer gap is estimated through the photon-photon pair process in the first case (Case I), and is limited by the critical field lines in the second case (Case II). The fractional size is described by Case I if the fractional size at the null charge surface in Case I is smaller than that in Case II, and vice versa. Such an outer gap can extend from the inner boundary, whose radial distance to the neutron star is less than that of the null charge surface to the light cylinder for a {gamma}-ray pulsar with a given magnetic inclination. When the shape of the outer gap is determined, assuming that high-energy emission at an averaged radius of the field line in the center of the outer gap, with a Gaussian distribution of the parallel electric field along the gap height, represents typical emission, the phase-averaged {gamma}-ray spectrum for a given pulsar can be estimated in the revised model with three model parameters. We apply the model to explain the phase-averaged spectra of the Vela (Case I) and Geminga (Case II) pulsars. We also use the model to fit the phase-averaged spectra of 54 young, isolated {gamma}-ray pulsars, and then calculate the {gamma}-ray luminosities and compare them with the observed data from Fermi-LAT.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  1. Pulser injection with subsequent removal for gamma-ray spectrometry

    DOEpatents

    Hartwell, Jack K.; Goodwin, Scott G.; Johnson, Larry O.; Killian, E. Wayne

    1990-01-01

    An improved system for gamma-ray spectroscopy characterized by an interface module that controls the injection of electronic pulses as well as separation logic that enables storage of pulser events in a region of the spectrum of a multichannel analyzer distinct from the region reserved for storage of gamma-ray events. The module accomplishes this by tagging pulser events (high or low) injected into the amplification circuitry, adding an offset to the events so identified at the time the events are at the output of the analog to digital converter, and storing such events in the upper portion of the spectrum stored in the multichannel analyzer. The module can be adapted for use with existing gamma-ray spectroscopy equipment to provide for automatic analyses of radioisotopes.

  2. Chemical effects of CeL(gamma4) emission spectra for Ce compounds.

    PubMed

    Hayashi, Hisashi; Takehara, Yuki; Kawamura, Naomi; Mizumaki, Masaichiro

    2010-01-01

    High-resolution CeL(gamma4) emission spectra of CeF(3), Ce(2)S(3), CeF(4), and CeO(2) have been measured using a multicrystal, multidetector spectrometer. The spectra exhibited substantial differences depending on the chemical environment of the Ce ions. By comparing the observed CeO(2) spectrum with the band calculations, we determined that the observed chemical effects of the main emission line were primarily attributable to the transitions of the Ce5p band; the high-energy tail at around 6.539 keV was assigned to the ligand p-->Ce2s cross transition. Further, a key difference between CeL(gamma4) and EuL(gamma4) is discussed with reference to CeL(1)- and EuL(1)-X-ray absorption fine-structures (XAFS). Possible applications of CeL(gamma4) emissions to material characterization are also suggested.

  3. Use of MCNP + GADRAS in Generating More Realistic Gamma-Ray Spectra for Plutonium and HEU Objects

    SciTech Connect

    Rawool-Sullivan, Mohini; Mattingly, John; Mitchell, Dean

    2012-08-07

    The ability to accurately simulate high-resolution gamma spectra from materials that emit both neutrons and gammas is very important to the analysis of special nuclear materials (SNM), e.g., uranium and plutonium. One approach under consideration has been to combine MCNP and GADRAS. This approach is expected to generate more accurate gamma ray spectra for complex three-dimensional geometries than can be obtained from one-dimensional deterministic transport simulations (e.g., ONEDANT). This presentation describes application of combining MCNP and GADRAS in simulating plutonium and uranium spectra.

  4. The spectra program library: A PC based system for gamma-ray spectra analysis and INAA data reduction

    USGS Publications Warehouse

    Baedecker, P.A.; Grossman, J.N.

    1995-01-01

    A PC based system has been developed for the analysis of gamma-ray spectra and for the complete reduction of data from INAA experiments, including software to average the results from mulitple lines and multiple countings and to produce a final report of analysis. Graphics algorithms may be called for the analysis of complex spectral features, to compare the data from alternate photopeaks and to evaluate detector performance during a given counting cycle. A database of results for control samples can be used to prepare quality control charts to evaluate long term precision and to search for systemic variations in data on reference samples as a function of time. The entire software library can be accessed through a user-friendly menu interface with internal help.

  5. Development of a Tool for the Rapid Quantitative Analysis of Multiple Gamma Spectra

    SciTech Connect

    HODGE, CHRISTOPHERA.

    2004-06-28

    Often multiple gamma spectra are acquired for the quantitative measurement of process holdup, filter banks, waste containers, D and D objects, or other such items. These spectra can represent data for single items, background data, and multiple assays of the same item or multiple areas representative of a single process area. The spectra are often collected under differing circumstances with regard to attenuating materials, distances, assay times, relative backgrounds, and many other such parameters. Quantitative results, and associated errors, are often dependent on multiple calibration constants, assays of varying isotopes, source geometries (point, line, or area), background averaging, Compton effects, and the accurate analysis, i.e. region of interest, of the raw gamma spectra. A tool has been developed to assist in this endeavor. The calculations have been quality checked so that the tool can readily be used with assurance that the calculations are consistent and correct. This tool allows for multiple spectra (up to 150) to be compared and manipulated. The tool has features for: dynamic average background subtraction; accounting for varying Compton effects; different calibration constants; up to three attenuating materials; any gamma energy; and variance in collection parameters such as distance, angle, assay times, and isotope. Selections of point, line, or area calculations are easily specified. The tool has a report writer that allows for averaging over multiple assays, graphing of activity (e.g., graphing activity in a sump allows the hot spots to be identified), and presentation of results with associated error components or MLDs. The resulting database allows for easy self-documentation and archiving.

  6. Airborne gamma-ray spectrometry in uranium exploration

    NASA Astrophysics Data System (ADS)

    Raghuwanshi, S. S.

    1992-07-01

    Uranium exploration is of paramount importance to India to maximize the indigeneous resources to meet the ever increasing demand for energy. Comprehensive regional and local zones of uranium mineralization are needed to be resolved. Such data comprise information on radioactivity in various energy ranges and on lithological knowledge. Airborne gamma-ray spectrometric techniques are particularly suited to provide spatial information. This review briefly discusses the conventional data presentation, statistically significant maps and the schemes suitable for classification of mineralized zones. A brief introduction is provided to airborne gamma-ray data, their acquisition, analysis, processing and interpretation to bring out their role in designing suitable models of uranium resources. State-of-the-art in uranium exploration covers radiometric mapping through airborne gamma-ray surveys. Through the examples of the Indian work done during this decade, the state-of-the-art and its usefulness in the country has been illustrated. It is concluded that the high sensitivity airborne gamma-ray spectrometric surveys coupled with modern methods of data analysis can further narrow down the targets.

  7. Digital approach to high rate gamma-ray spectrometry

    SciTech Connect

    Korolczuk, Stefan; Mianowski, Slawomir; Rzadkiewicz, Jacek; Sibczynski, Pawel; Swiderski, Lukasz; Szewinski, Jaroslaw; Zychor, Izabella

    2015-07-01

    Basic concepts and preliminary results of creating high rate digital spectrometry system using efficient ADCs and latest FPGA are presented as well as a comparison with commercially available devices. The possibility to use such systems, coupled to scintillators, in plasma experiments is discussed. (authors)

  8. Characterization of coal and charcoal by alpha-particle and gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Carrasco Lourtau, A. M.; Rubio Montero, M. P.; Jurado Vargas, M.

    2015-11-01

    Although coal and charcoal have similar physical and chemical characteristics, there are several crystallographic procedures used to distinguish and characterize them. But if the matrix is crushed, there is no standard procedure to distinguish coal from charcoal. In this work, a procedure to characterize coal and charcoal samples based on the radioactive content is proposed. The first assay is by gamma-ray spectrometry, which allows a part of the radioactive content to be determined rapidly and non-destructively. Then, alpha-particle spectrometry is applied to assay the content of those radionuclides which are difficult to determine precisely by gamma-ray spectrometry. This second technique requires prior chemical purification of the carbon sample in order to separate the corresponding radionuclides of interest.

  9. Comparison of new and existing algorithms for the analysis of 2D radioxenon beta gamma spectra

    DOE PAGES

    Deshmukh, Nikhil; Prinke, Amanda; Miller, Brian; ...

    2017-01-13

    The aim of this study is to compare radioxenon beta–gamma analysis algorithms using simulated spectra with experimentally measured background, where the ground truth of the signal is known. We believe that this is among the largest efforts to date in terms of the number of synthetic spectra generated and number of algorithms compared using identical spectra. We generate an estimate for the minimum detectable counts for each isotope using each algorithm. The paper also points out a conceptual model to put the various algorithms into a continuum. Finally, our results show that existing algorithms can be improved and some newermore » algorithms can be better than the ones currently used.« less

  10. Some applications of gamma absorptiometry and spectrometry for the control of nuclear materials

    NASA Astrophysics Data System (ADS)

    Guery, M.

    1991-02-01

    In nuclear fuels, and neutrons absorbers used in control rods, the thermal power generated is locally dependent on the concentration of the fissile or absorbing nucleus. In order to control the homogeneity of such materials, non-destructive methods using either gamma absorptiometry or gamma spectrometry were developed; some applications of these methods are presented in this paper. The fuel of the High Temperature Reactor (HTR) is frequently composed of UO 2 and ThO 2 spherical particles dispersed in a carbon matrix; the axial distribution of the particles along the fuel rods can be controlled in two ways: with gamma absorptiometry the heavy elements atoms (U+Th) can be detected but without discrimination between U and Th; with gamma spectrometry, separate distributions of uranium and thorium, deduced from the intensity of characteristic gamma rays are obtained. In nuclear power plants (PWR, FBR) the control rods are made usually with boron carbide (B 4C) pellets. By mean of gamma absorptiometry scanning the density distribution along the axis and the radius of the pellets are obtained. The originality of the method consists in the use of a self-calibration process, then the knowledge of the mass absorption coefficient is not required to perform the examinations. A computerized apparatus has been developed for these controls.

  11. Detection of Anomalous Gamma-Ray Spectra for On-Site Inspection

    SciTech Connect

    Seifert, Carolyn E.; Myjak, Mitchell J.; Pfund, David M.

    2009-05-29

    This work aims to solve some of the technical and logistical challenges inherent in performing On Site Inspection activities under the authority of the Comprehensive Nuclear-Test-Ban Treaty. Inspectors require equipment that can reliably identify the radionuclide signatures of nuclear test explosions amid a background of environmental contamination. Detection of these radiation anomalies by mobile search teams in the air or on the ground can narrow the search field and target specific areas for more detailed inspection or sampling. The need to protect confidential information of the inspected State Party, especially regarding past nuclear testing activities, suggests that full access to measured gamma-ray spectra should be limited. Spectral blinding techniques---in which only a fraction of the information derived from the spectra is displayed and stored---have the potential to meet the needs of both the OSI team and the State Party. In this paper, we describe one such algorithm that we have developed for identifying anomalous spectra from handheld, mobile, or aerial sensors. The algorithm avoids potential sensitivities by reducing the gamma-ray spectrum into a single number that is displayed and stored. A high value indicates that the spectrum is anomalous. The proposed technique does not rely on identifying specific radionuclides, operates well in the presence of high background variability, and can be configured to ignore specific spectral components. In previous work, the algorithm has proven very effective in classifying gamma-ray spectra as anomalous or not, even with poor statistical information. We performed a limited simulation of an airborne search scenario to demonstrate the potential algorithm for OSI missions. The technique successfully detected an injected source of interest whose count rate was an order of magnitude below background levels. We also configured the algorithm to ignore 137Cs as irrelevant to the mission. The resulting alarm metrics were

  12. Experimental and MCNP simulated gamma-ray spectra for the UNCOSS neutron-based explosive detector

    NASA Astrophysics Data System (ADS)

    Eleon, C.; Perot, B.; Carasco, C.; Sudac, D.; Obhodas, J.; Valkovic, V.

    2011-02-01

    In the frame of the FP7 UNCOSS project (Underwater Coastal Sea Surveyor), whose aim is to develop a neutron-based explosive detection system to identify unexploded ordnance (UXO) lying on the sea bottom, the choice of the gamma-ray detector is essential to reach the optimal performances. This paper presents comparative tests between the two candidates: NaI(Tl) and LaBr 3(Ce) detectors, in favour to the 3 in.×3 in. LaBr 3(Ce); thus, confirming the choice previously performed by numerical simulation because of its higher fast timing properties, spectral resolution, and efficiency per volume unit. The gamma-ray spectra produced by 14 MeV tagged neutron beams on the elements of interest (C, O, N, Al, Fe, Si, and Ca) have also been recorded with this detector in order to unfold the spectrum of the interrogated object into elementary contributions. A qualitative comparison with the gamma-ray spectra simulated with the MCNPX computer code and the ENDFB/VII.0 nuclear library has also been performed to validate the numerical model. An additional quantitative validation has been performed with an explosive-like material (ammonium acetate).

  13. Superluminal cascade spectra of TeV {gamma}-ray sources

    SciTech Connect

    Tomaschitz, Roman . E-mail: tom@geminga.org

    2007-03-15

    Astrophysical radiation sources are scrutinized in search of superluminal {gamma}-rays. The tachyonic spectral densities generated by ultra-relativistic electrons in uniform motion are fitted to the high-energy spectra of Galactic supernova remnants, such as RX J0852.0-4622 and the pulsar wind nebulae in G0.9+0.1 and MSH 15-52. The superluminal spectral maps of the unidentified TeV {gamma}-ray sources HESS J1303-631, TeV J2032+4130 and HESS J1825-137 are inferred from EGRET, HEGRA and HESS data. Tachyonic cascade spectra are quite capable of generating the spectral curvature seen in double-logarithmic plots, as well as the extended spectral plateaus defined by EGRET flux points in the GeV band. The curvature of the TeV spectra is intrinsic, caused by the Boltzmann factor in the source densities. The spectral averaging with thermal and exponentially cut power-law electron densities can be done in closed form, and systematic high- and low-temperature expansions of the superluminal spectral densities are derived. Estimates on the electron/proton populations generating the tachyon flux are obtained from the spectral fits, such as power-law indices, temperature and source counts. The cutoff temperatures of the source densities suggest ultra-high-energy protons in MSH 15-52, HESS J1825-137 and TeV J2032+4130.

  14. The effect of Compton scattering on gamma-ray spectra of the 2005 January 20 flare

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Gan, Wei-Qun

    2012-10-01

    Gamma-ray spectroscopy provides a wealth of information about accelerated particles in solar flares, as well as the ambient medium with which these energetic particles interact. The neutron capture line (2.223 MeV), the strongest in the solar gamma-ray spectrum, forms in the deep atmosphere. The energy of these photons can be reduced via Compton scattering. With the fully relativistic GEANT4 toolkit, we have carried out Monte Carlo simulations of the transport of a neutron capture line in solar flares, and applied them to the flare that occurred on 2005 January 20 (X7.1/2B), one of the most powerful gamma-ray flares observed by RHESSI during the 23rd solar cycle. By comparing the fitting results of different models with and without Compton scattering of the neutron capture line, we find that when including the Compton scattering for the neutron capture line, the observed gamma-ray spectrum can be reproduced by a population of accelerated particles with a very hard spectrum (s <= 2.3). The Compton effect of a 2.223 MeV line on the spectra is therefore proven to be significant, which influences the time evolution of the neutron capture line flux as well. The study also suggests that the mean vertical depth for neutron capture in hydrogen for this event is about 8 g cm-2.

  15. Gamma-ray spectrometry of LDEF samples at SRL

    SciTech Connect

    Winn, W.G.

    1991-07-22

    A total of 31 samples from the Long Duration Exposure Facility (LDEF), including materials of aluminum, vanadium, and steel trunnions were analyzed by ultra-low-level gamma spectroscopy. The study quantified particle induced activations of {sup 22}Na, {sup 46}Sc, {sup 51}Cr, {sup 54}Mn, {sup 56}Co, {sup 57}Co, {sup 58}Co, and {sup 60}Co. The samples of trunnion sections exhibited increasing activity toward the outer end of the trunnion and decreasing activity toward its radial center. The trunnion sections did not include end pieces, which have been reported to collect noticeable {sup 7}Be on their leading surfaces. No significant {sup 7}Be was detected in the samples analyzed. The Underground Counting Facility at Savannah River Laboratory (SRL) was used in this work. The facility is 50 ft. underground, constructed with low-background shielding materials, and operated as a clean room. The most sensitive analyses were performed with a 90%-efficient HPGe gamma-ray detector, which is enclosed in a purged active/passive shield. Each sample was counted for one to six days in two orientations to yield more representative average activities for the sample. The non-standard geometries of the LDEF samples prompted the development of a novel calibration method, whereby the efficiency about the samples surfaces (measured with point sources) predicted the efficiency for the bulk sample.

  16. The Imprint of the Extragalactic Background Light in the Gamma-Ray Spectra of Blazars

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Allafort, A.; Schady, P.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bottacini, E.; Bouvier, A.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Gehrels, N.; Guirec, S.; Hays, E.; McEnery, J. E.; Perkins, J. S.; Scargle, J. D.; Troja, E.

    2012-01-01

    The light emitted by stars and accreting compact objects through the history of the universe is encoded in the intensity of the extragalactic background light (EBL). Knowledge of the EBL isimportant to understand the nature of star formation and galaxy evolution, but direct measurements of the EBL are limited by galactic and other foreground emissions. Here, we report an absorption feature seen in the combined spectra of a sample of gamma-ray blazars out to a redshift of z approx. 1.6. This feature is caused by attenuation of gamma rays by the EBL at optical to ultraviolet frequencies and allowed us to measure the EBL flux density in this frequency band.

  17. 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.

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

    SciTech Connect

    Ji Chuncheng; Kegel, G.H.R.; Egan, J.J.; DeSimone, D.J.; Alimeti, A.; Roldan, C.F.; McKittrick, T.M.; Kim, D.-S.; Chen, X.; Tremblay, S.E.

    2005-05-24

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

  19. Radiation anomaly detection algorithms for field-acquired gamma energy spectra

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ron; Guss, Paul; Mitchell, Stephen

    2015-08-01

    The Remote Sensing Laboratory (RSL) is developing a tactical, networked radiation detection system that will be agile, reconfigurable, and capable of rapid threat assessment with high degree of fidelity and certainty. Our design is driven by the needs of users such as law enforcement personnel who must make decisions by evaluating threat signatures in urban settings. The most efficient tool available to identify the nature of the threat object is real-time gamma spectroscopic analysis, as it is fast and has a very low probability of producing false positive alarm conditions. Urban radiological searches are inherently challenged by the rapid and large spatial variation of background gamma radiation, the presence of benign radioactive materials in terms of the normally occurring radioactive materials (NORM), and shielded and/or masked threat sources. Multiple spectral anomaly detection algorithms have been developed by national laboratories and commercial vendors. For example, the Gamma Detector Response and Analysis Software (GADRAS) a one-dimensional deterministic radiation transport software capable of calculating gamma ray spectra using physics-based detector response functions was developed at Sandia National Laboratories. The nuisance-rejection spectral comparison ratio anomaly detection algorithm (or NSCRAD), developed at Pacific Northwest National Laboratory, uses spectral comparison ratios to detect deviation from benign medical and NORM radiation source and can work in spite of strong presence of NORM and or medical sources. RSL has developed its own wavelet-based gamma energy spectral anomaly detection algorithm called WAVRAD. Test results and relative merits of these different algorithms will be discussed and demonstrated.

  20. GAMMA-RAY BURST SPECTRA AND SPECTRAL CORRELATIONS FROM SUB-PHOTOSPHERIC COMPTONIZATION

    SciTech Connect

    Chhotray, Atul; Lazzati, Davide

    2015-04-01

    One of the most important unresolved issues in gamma-ray burst (GRB) physics is the origin of the prompt gamma-ray spectrum. Its general non-thermal character and the softness in the X-ray band remain unexplained. We tackle these issues by performing Monte Carlo simulations of radiation–matter interactions in a scattering dominated photon–lepton plasma. The plasma—initially in equilibrium—is driven to non-equilibrium conditions by a sudden energy injection in the lepton population, mimicking the effect of a shock wave or the dissipation of magnetic energy. Equilibrium restoration occurs due to an energy exchange between the photons and leptons. While the initial and final equilibrium spectra are thermal, the transitional photon spectra are characterized by non-thermal features such as power-law tails, high energy bumps, and multiple components. Such non-thermal features are observed at infinity if the dissipation occurs at small to moderate optical depths, and the spectrum is released before thermalization is complete. We model the synthetic spectra with a Band function and show that the resulting spectral parameters are similar to observations for a frequency range of 2–3 orders of magnitude around the peak. In addition, our model predicts correlations between the low-frequency photon index and the peak frequency as well as between the low- and high-frequency indices. We explore baryon and pair-dominated fireballs and reach the conclusion that baryonic fireballs are a better model for explaining the observed features of GRB spectra.

  1. Environmental Protection Agency (EPA) airborne gamma spectrometry system for environmental and emergency response surveys

    NASA Astrophysics Data System (ADS)

    Cardarelli, John, II; Thomas, Mark; Curry, Timothy

    2010-08-01

    The EPA Airborne Spectral Photometric Environmental Collection Technology (ASPECT) Program provides airborne ortho-rectified imagery, video, chemical and now radiological information directly to emergency response personnel via a commercial satellite link onboard the aircraft. EPA initiated the ASPECT Gamma Emergency Mapper GEM Project in 2008 to improve its airborne gamma-screening and mapping capability for monitoring any ground-based gamma contamination. This paper will provide an overview of the system, which can be configured to carry six 2"x4"x16" NaI(Tl) detectors and two 3"x3" LaBr3(Ce) detectors or eight 2"x4"x16" NaI(Tl) detectors. The paper will provide an overview of the analysis of gamma radiation spectra, system limitations, and emergency response applications.

  2. Development of isotope dilution gamma-ray spectrometry for plutonium analysis

    SciTech Connect

    Li, T.K.; Parker, J.L. ); Kuno, Y.; Sato, S.; Kurosawa, A.; Akiyama, T. )

    1991-01-01

    We are studying the feasibility of determining the plutonium concentration and isotopic distribution of highly radioactive, spent-fuel dissolver solutions by employing high-resolution gamma-ray spectrometry. The study involves gamma-ray plutonium isotopic analysis for both dissolver and spiked dissolver solution samples, after plutonium is eluted through an ion-exchange column and absorbed in a small resin bead bag. The spike is well characterized, dry plutonium containing {approximately}98% of {sup 239}Pu. By using measured isotopic information, the concentration of elemental plutonium in the dissolver solution can be determined. Both the plutonium concentration and the isotopic composition of the dissolver solution obtained from this study agree well with values obtained by traditional isotope dilution mass spectrometry (IDMS). Because it is rapid, easy to operate and maintain, and costs less, this new technique could be an alternative method to IDMS for input accountability and verification measurements in reprocessing plants. 7 refs., 4 figs., 4 tabs.

  3. BATSE observations of gamma-ray burst spectra. I - Spectral diversity

    NASA Technical Reports Server (NTRS)

    Band, D.; Matteson, J.; Ford, L.; Schaefer, B.; Palmer, D.; Teegarden, B.; Cline, T.; Briggs, M.; Paciesas, W.; Pendleton, G.

    1993-01-01

    We studied the time-averaged gamma-ray burst spectra accumulated by the spectroscopy detectors of the Burst and Transient Source Experiment. The spectra are described well at low energy by a power-law continuum with an exponential cutoff and by a steeper power law at high energy. However, the spectral parameters vary from burst to burst with no universal values. The break in the spectrum ranges from below 100 keV to more than 1 MeV, but peaks below 200 keV with only a small fraction of the spectra breaking above 400 keV; it is therefore unlikely that a majority of the burst spectra are shaped directly by pair processes, unless bursts originate from a broad redshift range. The correlations among burst parameters do not fulfill the predictions of the cosmological models of burst origin. No correlations with burst morphology or the spatial distribution were found. We demonstrate the importance of using a complete spectral description even if a partial description (e.g., a model without a high-energy tail) is statistically satisfactory.

  4. The potential of gamma-ray spectrometry as supplementary information for mapping central European soils

    NASA Astrophysics Data System (ADS)

    Schuler, U.; Bock, M.; Baritz, R.; Willer, J.; Pickert, E.; Kardel, K.; Herrmann, L.

    2012-04-01

    Permanently updated soil maps are needed inter alia for the prediction of landslide hazards, flooding and drought effects, land degradation monitoring, and precision farming. Since comprehensive and intensive field mapping is not affordable, alternative mapping approaches are required. A promising tool, with quite unrecognised potential for modern soil science is gamma-ray spectrometry. As the radioelements potassium, thorium and uranium respond differently to soil forming processes, it should be possible to infer from their concentration on weathering status, and after calibration on soil properties and types. This paper aims to investigate the potential of airborne gamma spectrometry for mapping of central European soils and soil properties. The study was conducted for a test site in Southern Saxony, Germany, 140*85 km wide, representing diverse soil landscapes. Seven different petrographic training and validation areas were chosen each. To assess the potential of gamma-ray spectrometry as additional data layer, predictions were carried out (i) with and (ii) without radiometric data. The outputs were compared with independent soil information of the validation areas. Both prediction runs used the following predictors: elevation, slope, curvature, planform curvature, profile curvature, terrain ruggedness index, relative altitude, vertical distance above drainage network, wetness index, and convergence index. As additional predictor parent material derived from a reclassification of the official geological map (1:1M scale) was used. As radiometric properties potassium, thorium and uranium were used. The radiometric raster datasets were generated by universal kriging using relative altitude as covariate. Training and validation datasets were selected from a comprehensive dataset representing more than 14.000 point data. Point data include soil types and substrates, and for more than 800 sites soil profiles with analysed texture, pH, exchangeable cations, nutrients

  5. Determination of impurities in (124)I samples by high resolution gamma spectrometry.

    PubMed

    de Almeida, M C M; da Silva, R L; Delgado, J U; Poledna, R; de Araújo, M T F; Laranjeira, A S; de Veras, E; Braghirolli, A M S; dos Santos, G R; Lopes, R T

    2016-03-01

    (124)I is a radionuclide used in the diagnosis of tumors. The National Health Agency requires identification and activity measurement of impurities. Using gamma spectrometry with an efficiency calibrated high-purity germanium detector, impurities (125)I and (126)I in an (1)(24)I production sample were identified. Activity ratios of (125)I and (126)I to (124)I were approximately 0.5% and 98%, respectively.

  6. Predicted TeV Gamma-ray Spectra and Images of Shell Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Reynolds, S. P.

    1999-04-01

    One supernova remnant, SN 1006, is now known to produce synchrotron X-rays (Koyama et al., 1995, Nature, 378, 255), requiring 100 TeV electrons. SN 1006 has also been seen in TeV gamma rays (Tanimori et al., 1998, ApJ, 497, L25), almost certainly due to cosmic-microwave-background photons being upscattered by those same electrons. Other young supernova remnants should also produce high-energy electrons, even if their X-ray synchrotron emission is swamped by conventional thermal X-ray emission. Upper limits to the maximum energy of shock-accelerated electrons can be found for those remnants by requiring that their synchrotron spectrum steepen enough to fall below observed thermal X-rays (Reynolds and Keohane 1999, ApJ, submitted). For those upper-limit spectra, I present predicted TeV inverse-Compton spectra and images for assumed values of the mean remnant magnetic field. Ground-based TeV gamma-ray observations of remnants may be able to put even more severe limits on the presence of highly energetic electrons in remnants, raising problems for conventional theories of galactic cosmic-ray production in supernova remnants. Detections will immediately confirm that SN 1006 is not alone, and will give mean remnant magnetic field strengths.

  7. Cyclotron resonant scattering in the spectra of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Wang, J. C. L.; Lamb, D. Q.; Loredo, T. J.; Wasserman, I. M.; Salpeter, E. E.

    1989-01-01

    Fits of theoretical spectra from Monte Carlo radiation-transfer calculations to dips at approximately 20 and 40 keV in a spectrum of the gamma-ray burst source GB 880 205 give best-fit values and 68 percent-confidence intervals for the magnetic field of (1.71 + or - 0.07) x 10 to the 12th G, the electron density of (1.2 + or - 0.6) x 10 to the 21st electrons/cm-squared, and the cosine of the viewing angle relative to the field of 0.31 + or - 0.05. The dips observed at approximately 20 keV in the spectra are interpreted as cyclotron resonant scattering, in which electrons undergo radiative 0 to 1 to 0 Landau transitions initiated by photons near the first harmonic. Physical self-consistency fixes the temperature, and the equilibrium temperature equals 5.3 + 0.3 or - 0.2 keV. These results suggest that this gamma-ray burst and many others which exhibit a low-energy dip originate from strongly magnetic neutron stars and are galactic in origin.

  8. Measurements of gamma radiation levels and spectra in the San Francisco Bay Area

    NASA Astrophysics Data System (ADS)

    Lo, B. T.; Brozek, K. P.; Angell, C. T.; Norman, E. B.

    2011-10-01

    Much of the radiation received by an average person is emitted by naturally-occurring radioactive isotopes from the thorium, actinium, and uranium decay series, or potassium. In this study, we have measured gamma radiation levels at various locations in the San Francisco Bay Area and the UC Berkeley campus from spectra taken using an ORTEC NOMAD portable data acquisition system and a large-volume coaxial HPGe detector. We have identified a large number of gamma rays originating from natural sources. The most noticeable isotopes are 214Bi, 40K, and 208Tl. We have observed variations in counting rates by factors of two to five between different locations due to differences in local conditions - such as building, concrete, grass, and soil compositions. In addition, in a number of outdoor locations, we have observed 604-, 662-, and 795-keV gamma rays from 134,137Cs, which we attribute to fallout from the recent Fukushima reactor accident. The implications of these results will be discussed. This work was supported in part by a grant from the U. S. Dept. of Homeland Security.

  9. Testing of regolith of celestial bolides with active neutron gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Vostrukhin, Andrey; Mitrofanov, Igor; Golovin, Dmitry; Litvak, Maxim; Sanin, Anton

    2015-04-01

    Current space instruments for studying planet's surface include gamma ray spectrometers that detect natural radioactive isotopes as well as gamma-rays induced in subsurface by galactic cosmic rays. When measuring from celestial body's surface, statistics and amount of detected elements can be dramatically increased with active methods, where soil exposed to artificial flux of particles. One good example is the Russian Dynamic Albedo of Neutron (DAN) instrument onboard Martian Science Laboratory mission (Curiosity rover) developed in 2005-2011. It is the first active neutron spectrometer flown to another planet as part of a landed mission to investigate subsurface water distribution and which has now successfully operated for more than two years on the Martian surface. Presentation describes a number of space instruments for different landers and rovers being developed in Russian Space Research Institute for studying Moon and Mars, as well as method of active neutron and gamma spectrometry overview.

  10. A Case Study Correlating Innovative Gamma Ray Scanning Detection Systems Data to Surface Soil Gamma Spectrometry Results - 13580

    SciTech Connect

    Thompson, Shannon; Rodriguez, Rene; Billock, Paul; Lit, Peter

    2013-07-01

    HydroGeoLogic (HGL), Inc. completed a United States Environmental Protection Agency (USEPA) study to characterize radiological contamination at a site near Canoga Park, California. The characterized area contained 470 acres including the site of a prototype commercial nuclear reactor and other nuclear design, testing, and support operations from the 1950's until 1988 [1]. The site history included radiological releases during operation followed by D and D activities. The characterization was conducted under an accelerated schedule and the results will support the project remediation. The project has a rigorous cleanup to background agenda and does not allow for comparison to risk-based guidelines. To target soil sample locations, multiple lines of evidence were evaluated including a gamma radiation survey, geophysical surveys, historical site assessment, aerial photographs, and former worker interviews. Due to the time since production and decay, the primary gamma emitting radionuclide remaining is cesium-137 (Cs-137). The gamma ray survey covered diverse, rugged terrain using custom designed sodium iodide thallium-activated (NaI(Tl)) scintillation detection systems. The survey goals included attaining 100% ground surface coverage and detecting gamma radiation as sensitively as possible. The effectiveness of innovative gamma ray detection systems was tested by correlating field Cs-137 static count ratios to Cs-137 laboratory gamma spectrometry results. As a case study, the area encompassing the former location of the first nuclear power station in the U. S. was scanned, and second by second global positioning system (GPS)-linked gamma spectral data were evaluated by examining total count rate and nuclide-specific regions of interest. To compensate for Compton scattering from higher energy naturally occurring radionuclides (U-238, Th-232 and their progeny, and K-40), count rate ratios of anthropogenic nuclide-specific regions of interest to the total count rate were

  11. Use of Gamma Spectrometry Method for Environmental Monitoring in the area of NPP

    NASA Astrophysics Data System (ADS)

    Thinova, L.; Cechak, T.; Kluson, J.; Trojek, T.

    2006-05-01

    It is generally not possible to correctly determine the long and short term impact of human activity upon the environment, without thorough processing of data, obtained through monitoring. It was confirmed that such impact on the environment must be monitored over a long time period. The data obtained must be of high quality, an attribute assured by present state of scientific knowledge. One of the well established methods for monitoring atmospheric deposition of radionuclides in the environment is laboratory and in situ gamma spectrometry. With the aim to monitor an occurrence of a one-time escape or persistent release of fission products into the air, resulting from an operation of a nuclear plant, two types of monitoring are performed: i/ measurement of samples from the environment (Schreber moss, forest humus, pine bark, mushrooms and forest berries) using laboratory gamma spectrometry method in the range up to 3 MeV (those data are used for the trend analysis and for the construction of the contaminationmaps); ii/ in situ gama spectrometry for assessment dosimetry and spectrometry characteristic of photon-fields (those data are used for the dose rate calculation).

  12. Application of blind source separation to gamma ray spectra acquired by GRaND around Vesta

    NASA Astrophysics Data System (ADS)

    Mizzon, H.; Toplis, M. J.; Forni, O.; Prettyman, T. H.; Raymond, C. A.; Russell, C. T.

    2012-12-01

    The bismuth germinate (BGO) scintillator is one of the sensors of the gamma ray and neutron detector (GRaND)1 on board the Dawn spacecraft, that has spent just over one year in orbit around the asteroid 4-Vesta. The BGO detector is excited by energetic gamma-rays produced by galactic cosmic rays (GCR) or energetic solar particles interacting either with Vesta and/or the Dawn spacecraft. In detail, during periods of quiet solar activity, gamma ray spectra produced by the scintillator can be considered as consisting of three signals: i) a contribution of gamma-rays from Vesta produced by GCR interactions at the asteroid's surface, ii) a contribution from the spacecraft excited by neutrons coming from Vesta, and iii) a contribution of the spacecraft excited by local interaction with galactic cosmic rays. While the first two contributions should be positive functions of the solid angle of Vesta in the field of view during acquisition, the last one should have a negative dependence because Vesta partly shields the spacecraft from GCR. This theoretical mix can be written formally as: S=aΩSV+bΩSSCNV+c(4π-Ω)SSCGCR (1) where S is the series of recorded spectra, Ω is the solid angle, SV is the contribution of gamma rays coming from Vesta, SSCNV is the contribution of gamma rays coming from the spacecraft excited by the neutron coming from Vesta and SSCGCR is the contribution of gamma rays coming from the spacecraft excited by GCR. A blind source separation method called independent component analysis enables separating additive subcomponents supposing the mutual statistical independence of the non-Gaussian source signals2. Applying this method to BGO spectra acquired during the first three months of the low-altitude measurement orbit (LAMO) reveals two main independent components. The first one is dominated by the positron electron annihilation peak and is positively correlated to the solid angle. The second is negatively correlated to the solid angle and displays peaks

  13. [Investigation of JinKui ShenQi pills by ultraviolet spectra and tandem mass spectrometry].

    PubMed

    Li, Wen-lan; Sun, Zhi; Cheng, Bin; Ji, Yu-bin; Bai, Jing

    2008-08-01

    On the base of establishing the fingerprint of JinKui ShenQi pills, the ultraviolet spectra-mass spectrometry/mass spectrometry, method was used to identify the fingerprint. Seperation was performed on the Symmetry Shield RP18 (5 microm, 4. 6 mm X 15 mm) analytical column with mobile phase consisting of 1% acetic acid and acetonitrile with gradient elute at the flow rate of 1.0 mL x min(-1), and the ultraviolet detection wavelength was set at 248 nm. Using the above-mentioned chromatographic condition, the fingerprint of different samples was established and the same fingerprint was defined. The fingerprints of different samples were compared with similarity evaluation software published by Pharmacopeia committee codex (2004A). The mass spectrograph with API-ESI ionization source was used, setting the flow rate at 0.5 mL x min(-1) after splitting stream. The pressure of atomization room was 50 Psi, the flow rate of dry gas was 9.0 L x min(-1), the capillary voltage was 4 kV, and the transmission voltage was 70 V. The negative scanner mode was chosen, scan scope was 100-2000, using ion trap to analyze quasimolecular ion peak and the selected fragment ion, and TIC chromatography and second order mass chromatogram were recorded. The major constituents among in JinKui ShenQi pills from different origins were separated well by HPLC. Although there was difference among different origins, they showed nineteen identical characteristic absorption bands. Three fingerprints chemical compositions such as loganin, cinnamal and paeonol were identified based on the retention time and ultraviolet spectra of standard preparation. According to their ultraviolet spectra, molecular weight and fragmentation information, ten peaks in the fingerprint were identified by ultraviolet spectroscopy-mass, spectrometry/massg spectrometry. They are 1,2,3-tri-O-galloyl-glucose, loganin, paeoniflorin, 1,2,3,6-tetro-O-galloyl-glucose, soya-cerebroside, cornuside, and PGG, benzoyl

  14. EPR spectra induced by gamma-irradiation of some dry medical herbs

    NASA Astrophysics Data System (ADS)

    Yordanov, N. D.; Lagunov, O.; Dimov, K.

    2009-04-01

    The radiation-induced EPR spectra in some medical herbs are reported. The samples studied are: (i) leaves of nettle, common balm, peppermint and thyme; (ii) stalks of common balm, thyme, milfoil, yarrow and marigold; (iii) blossoms of yarrow and marigold; (iv) blossoms and leaves of hawthorn and tutsan; and (v) roots of common valerian, nettle, elecampane (black and white), restharrows and carlina. Before irradiation all samples exhibit one weak anisotropic singlet EPR line with effective g-value of 2.0050±0.0002. The radiation-induced spectra fall into three groups. EPR spectra of irradiated blossoms of yarrow and marigold, stalks of common balm, thyme, tutsan and yarrow as well as roots of common valerian, nettle and elecampane (black and white) show "cellulose-like" EPR spectrum typical for irradiated plants. It is characterized by one intense central line with g=2.0050±0.0005 and two weak satellite lines situated ca. 30 G left and right to it. EPR spectra of gamma-irradiated restharrows and carlina are complex. They may be represented by one triplet corresponding to the "cellulose-like" EPR spectrum, one relatively intense singlet, situated in the center of the spectrum, and five weak additional satellite lines left and right to the center. The last spectrum was assigned as "carbohydrate-like" type. Only one intense EPR singlet with g=2.0048±0.0005 was recorded after irradiation of leaves of nettle and common balm. The lifetime of the radiation-induced EPR spectra was followed for a period of 3 months.

  15. Measurement of gamma radiation levels in soil samples from Thanjavur using gamma-ray spectrometry and estimation of population exposure.

    PubMed

    Senthilkumar, B; Dhavamani, V; Ramkumar, S; Philominathan, P

    2010-01-01

    This study assesses the level of terrestrial gamma radiation and associated dose rates from the naturally occurring radionuclides (232)Th, (238)U and (40)K in 10 soil samples collected from Thanjavur (Tamil Nadu, India) using gamma-ray spectrometry. The activity profile of radionuclides has clearly showed the existence of low level activity in Thanjavur. The geometric mean activity concentrations of (232)Th, (238)U and (40)K is 42.9+/-9.4 Bq.kg(-1), 14.7+/-1.7 Bq.kg(-1) and 149.5+/-3.1 Bq.kg(-1) respectively are derived from all the soil samples studied. The activity concentration of (232)Th, (238)U and (40)K in soil is due to the presence of metamorphic rocks like shale, hornblende-biotite gneiss and quartzofeldspathic gneiss in these areas. Gamma absorbed dose rates in air outdoors were calculated to be in the range between 32 nGy.h(-1) and 59.1 nGy.h(-1) with an arithmetic mean of 43.3 +/-9 nGy.h(-1). This value is lesser than the population weighted world-averaged of 60 nGy.h(-1). Inhabitants of Thanjavur are subjected to external gamma radiation exposure (effective dose) ranging between 39.2 and 72.6 muSv.y(-1) with an arithmetic mean of 53.1+/-11 muSv.y(-1). The values of the external hazard index determined from the soil radioactivity of the study area are less than the recommended safe levels.

  16. Spectra of X-ray and Gamma-ray Bursts Produced by Stepping Lightning Leaders

    NASA Astrophysics Data System (ADS)

    Celestin, Sebastien; Xu, Wei; Pasko, Victor

    2013-04-01

    Terrestrial gamma-ray flashes (TGFs) are bursts of high-energy photons originating from the Earth's atmosphere in association with thunderstorm activity. TGFs were serendipitously discovered by BATSE detector aboard the Compton Gamma-Ray Observatory originally launched to perform observations of celestial gamma-ray sources [Fishman et al., Science, 264, 1313, 1994]. These events have also been detected by the RHESSI satellite [Smith et al., Science, 307, 1085, 2005], the AGILE satellite [Marisaldi et al., JGR, 115, A00E13, 2010], and the Fermi Gamma-ray Space Telescope [Briggs et al., JGR, 115, A07323, 2010]. Moreover, measurements have correlated TGFs with initial development stages of normal polarity intra-cloud lightning that transports negative charge upward (+IC) [e.g, Lu et al., JGR, 116, A03316, 2011]. Photon spectra corresponding to well-established model of relativistic runaway electron avalanches (RREAs) usually provide a very good agreement with satellite observations [Dwyer and Smith, GRL, 32, L22804, 2005]. However, it has been suggested that high-potential +IC lightning leaders could produce a sufficient number of energetic electrons to explain TGFs [Celestin and Pasko, JGR, 116, A03315, 2011] and Xu et al. [GRL, 39, L08801, 2012] have shown that this mechanism could explain the TGF spectrum for lightning potentials higher than 100 MV. In addition to TGFs, X-ray bursts are produced by negative lightning leaders in association with stepping processes and are observed from the ground [Dwyer et al., GRL, 32, L01803, 2005]. However, the energy spectrum of X-ray bursts from lightning is still poorly known, mainly due to the low fluence detected from the ground. In this work, we use Monte Carlo models to study the acceleration of runaway electrons in the electric field produced around lightning leader tip and the associated bremsstrahlung photon spectra observed by low-orbit satellites in the case of high potential +IC discharges and from the ground in the

  17. Assay for uranium and determination of disequilibrium by means of in situ high resolution gamma-ray spectrometry

    USGS Publications Warehouse

    Tanner, Allan B.; Moxham, Robert M.; Senftle, F.E.

    1977-01-01

    Two sealed sondes, using germanium gamma-ray detectors cooled by melting propane, have been field tested to depths of 79 m in water-filled boreholes at the Pawnee Uranium Mine in Bee Co., Texas. When, used as total-count devices, the sondes are comparable in logging speed and counting rate with conventional scintillation detectors for locating zones of high radioactivity. When used with a multichannel analyzer, the sondes are detectors with such high resolution that individual lines from the complex spectra of the uranium and thorium series can be distinguished. Gamma rays from each group of the uranium series can be measured in ore zones permitting determination of the state of equilibrium at each measurement point. Series of 10-minute spectra taken at 0.3- to 0.5-m intervals in several holes showed zones where maxima from the uranium group and from the 222Rn group were displaced relative to each other. Apparent excesses of 230Th at some locations suggest that uranium-group concentrations at those locations were severalfold greater some tens of kiloyears, ago. At the current state of development a 10-minute count yields a sensitivity of about 80 ppm U308. Data reduction could in practice be accomplished in about 5 minutes. The result is practically unaffected by disequilibrium or radon contamination. In comparison with core assay, high-resolution spectrometry samples a larger volume; avoids problems due to incomplete core recovery, loss of friable material to drilling fluids, and errors in depth and marking; and permits use of less expensive drilling methods. Because gamma rays from the radionuclides are accumulated simultaneously, it also avoids the problems inherent in trying to correlate logs made in separate runs with different equipment. Continuous-motion delayed-gamma activation by a 163-?g 252Cf neutron source attached to the sonde yielded poor sensitivity. A better neutron-activation method, in which the sonde is moved in steps so as to place the detector

  18. 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.

  19. A convenient method for discriminating between natural and depleted uranium by gamma-ray spectrometry.

    PubMed

    Shoji, M; Hamajima, Y; Takatsuka, K; Honoki, H; Nakajima, T; Kondo, T; Nakanishi, T

    2001-08-01

    A convenient method for discriminating between natural and depleted uranium reagent was developed by measuring and analyzing the gamma-ray spectra of some reagents with no standard source. The counting rates (R) of photoelectric peaks of gamma-rays from nuclides with the same radioactivity divided by their emission probability (B) are expressed as a function of gamma-ray energy. The radioactivities of 234Th and 234mPa and 21.72 times that of 235U are equal to the radioactivity of 235U in natural uranium. Therefore, the plot of 21.72-fold R/B for 235U should be on a curve fitted to the points for 234Th and 234mPa in natural uranium. Depleted uranium with a 235U isotopic composition of less than 0.68% could be discriminated from natural uranium in the case of a reagent containing 4.0 g of uranium.

  20. The Study of Equilibrium factor between Radon-222 and its Daughters in Bangkok Atmosphere by Gamma-ray Spectrometry

    NASA Astrophysics Data System (ADS)

    Rujiwarodom, Rachanee

    2010-05-01

    To study the Equilibrium between radon-222 and its daughters in Bangkok atmosphere by Gamma-ray spectrometry, air sample were collected on 48 activated charcoal canister and 360 glass fiber filters by using a high volume jet-air sampler during December 2007 to November 2008.The Spectra of gamma-ray were measured by using a HPGe (Hyper Pure Germanium Detector). In the condition of secular equilibrium obtaining between Radon-222 and its decay products, radon-222 on activated charcoal canister and its daughters on glass fiber filters collected in the same time interval were calculated. The equilibrium factor (F) in the open air had a value of 0.38 at the minimum ,and 0.75 at the maximum. The average value of equilibrium factor (F) was 0.56±0.12. Based on the results, F had variations with a maximum value in the night to the early morning and decreased in the afternoon. In addition, F was higher in the winter than in the summer. This finding corresponds with the properties of the Earth atmosphere. The equilibrium factor (F) also depended on the concentration of dust in the atmosphere. People living in Bangkok were exposed to average value of 30 Bq/m3 of Radon-222 in the atmosphere. The equilibrium factor (0.56±0.12) and the average value of Radon-222 showed that people were exposed to alpha energy from radon-222 and its daughters decay at 0.005 WL(Working Level) which is lower than the safety standard at 0.02 WL. Keywords: Radon, Radon daughters , equilibrium factor, Gamma -ray spectrum analysis ,Bangkok ,Thailand

  1. Gamma-ray spectra and doses from the Little Boy replica

    SciTech Connect

    Moss, C.E.; Lucas, M.C.; Tisinger, E.W.; Hamm, M.E.

    1984-01-01

    Most radiation safety guidelines in the nuclear industry are based on the data concerning the survivors of the nuclear explosions at Hiroshima and Nagasaki. Crucial to determining these guidelines is the radiation from the explosions. We have measured gamma-ray pulse-height distributions from an accurate replica of the Little Boy device used at Hiroshima, operated at low power levels near critical. The device was placed outdoors on a stand 4 m from the ground to minimize environmental effects. The power levels were based on a monitor detector calibrated very carefully in independent experiments. High-resolution pulse-height distributions were acquired with a germanium detector to identify the lines and to obtain line intensities. The 7631 to 7645 keV doublet from neutron capture in the heavy steel case was dominant. Low-resolution pulse-height distributions were acquired with bismuth-germanate detectors. We calculated flux spectra from these distributions using accurately measured detector response functions and efficiency curves. We then calculated dose-rate spectra from the flux spectra using a flux-to-dose-rate conversion procedure. The integral of each dose-rate spectrum gave an integral dose rate. The integral doses at 2 m ranged from 0.46 to 1.03 mrem per 10/sup 13/ fissions. The output of the Little Boy replica can be calculated with Monte Carlo codes. Comparison of our experimental spectra, line intensities, and integral doses can be used to verify these calculations at low power levels and give increased confidence to the calculated values from the explosion at Hiroshima. These calculations then can be used to establish better radiation safety guidelines. 7 references, 7 figures, 2 tables.

  2. Gamma-ray burst prompt emission light curves and power density spectra in the ICMART model

    SciTech Connect

    Zhang, Bo; Zhang, Bing E-mail: zhang@physics.unlv.edu

    2014-02-20

    In this paper, we simulate the prompt emission light curves of gamma-ray bursts (GRBs) within the framework of the Internal-Collision-induced MAgnetic Reconnection and Turbulence (ICMART) model. This model applies to GRBs with a moderately high magnetization parameter σ in the emission region. We show that this model can produce highly variable light curves with both fast and slow components. The rapid variability is caused by many locally Doppler-boosted mini-emitters due to turbulent magnetic reconnection in a moderately high σ flow. The runaway growth and subsequent depletion of these mini-emitters as a function of time define a broad slow component for each ICMART event. A GRB light curve is usually composed of multiple ICMART events that are fundamentally driven by the erratic GRB central engine activity. Allowing variations of the model parameters, one is able to reproduce a variety of light curves and the power density spectra as observed.

  3. An innovative method for extracting isotopic information from low-resolution gamma spectra

    SciTech Connect

    Miko, D.; Estep, R.J.; Rawool-Sullivan, M.W.

    1998-12-01

    A method is described for the extraction of isotopic information from attenuated gamma ray spectra using the gross-count material basis set (GC-MBS) model. This method solves for the isotopic composition of an unknown mixture of isotopes attenuated through an absorber of unknown material. For binary isotopic combinations the problem is nonlinear in only one variable and is easily solved using standard line optimization techniques. Results are presented for NaI spectrum analyses of various binary combinations of enriched uranium, depleted uranium, low burnup Pu, {sup 137}Cs, and {sup 133}Ba attenuated through a suite of absorbers ranging in Z from polyethylene through lead. The GC-MBS method results are compared to those computed using ordinary response function fitting and with a simple net peak area method. The GC-MBS method was found to be significantly more accurate than the other methods over the range of absorbers and isotopic blends studied.

  4. Effective absorbing column density in the gamma-ray burst afterglow X-ray spectra

    NASA Astrophysics Data System (ADS)

    Campana, S.; Bernardini, M. G.; Braito, V.; Cusumano, G.; D'Avanzo, P.; D'Elia, V.; Ghirlanda, G.; Ghisellini, G.; Melandri, A.; Salvaterra, R.; Tagliaferri, G.; Vergani, S. D.

    2014-07-01

    We investigate the scaling relation between the observed amount of absorption in the X-ray spectra of gamma-ray burst afterglows and the absorber redshift. Through dedicated numerical simulations of an ideal instrument, we establish that this dependence has a power-law shape with index 2.4. However, for real instruments, this value depends on their low-energy cut-off, spectral resolution and on the detector spectral response in general. We thus provide appropriate scaling laws for specific instruments. Finally, we discuss the possibility to measure the absorber redshift from X-ray data alone. We find that 105-106 counts in the 0.3-10 keV band are needed to constrain the redshift with 10 per cent accuracy. As a test case, we discuss the XMM-Newton observation of GRB 090618 at z = 0.54. We are able to recover the correct redshift of this burst with the expected accuracy.

  5. GRABGAM: A Gamma Analysis Code for Ultra-Low-Level HPGe SPECTRA

    SciTech Connect

    Winn, W.G.

    1999-07-28

    The GRABGAM code has been developed for analysis of ultra-low-level HPGe gamma spectra. The code employs three different size filters for the peak search, where the largest filter provides best sensitivity for identifying low-level peaks and the smallest filter has the best resolution for distinguishing peaks within a multiplet. GRABGAM basically generates an integral probability F-function for each singlet or multiplet peak analysis, bypassing the usual peak fitting analysis for a differential f-function probability model. Because F is defined by the peak data, statistical limitations for peak fitting are avoided; however, the F-function does provide generic values for peak centroid, full width at half maximum, and tail that are consistent with a Gaussian formalism. GRABGAM has successfully analyzed over 10,000 customer samples, and it interfaces with a variety of supplementary codes for deriving detector efficiencies, backgrounds, and quality checks.

  6. Comparison of measured and calculated neutron and gamma-ray energy spectra behind an in-line shielded duct

    SciTech Connect

    Santoro, R.T.; Alsmiller, R.G. Jr.; Barnes, J.M.; Chapman, G.T.; Tang, J.S.

    1982-05-01

    Integral experiments that measure the transport of approx. 14 MeV neutrons through a 0.30-m-diameter duct having a length-to-diameter ratio of 2.83 that is partially plugged with a 0.15 m diameter, 0.51 m long shield comprised of alternating layers of stainless steel type 304 and borated polyethylene have been carried out at the Oak Ridge National Laboratory. Measured and calculated neutron and gamma ray energy spectra are compared at several locations relative to the mouth of the duct. The measured spectra were obtained using an NE-213 liquid scintillator detector with pulse shape discrimination methods used to simultaneously resolve neutron and gamma ray events. The calculated spectra were obtained using a computer code network that incorporates two radiation transport methods: discrete ordinates (with P/sub 3/ multigroup cross sections) and Monte Carlo (with continuous point cross sections). The two radiation transport methods are required to account for neutrons that singly scatter from the duct to the detectors. The calculated and measured neutron energy spectra above 850 keV agree with 5 to 50% depending on detector location and neutron energy. The calculated and measured gamma ray energy spectra above 750 keV are also in favorable agreement, approx. 5 to 50%, depending on detector location and gamma ray energy.

  7. The Multi-Isotope Process Monitor: Multivariate Analysis of Gamma Spectra

    SciTech Connect

    Orton, Christopher R.; Rutherford, Crystal E.; Fraga, Carlos G.; Schwantes, Jon M.

    2011-10-30

    The International Atomic Energy Agency (IAEA) has established international safeguards standards for fissionable material at spent fuel reprocessing plants to ensure that significant quantities of nuclear material are not diverted from these facilities. Currently, methods to verify material control and accountancy (MC&A) at these facilities require time-consuming and resource-intensive destructive assay (DA). The time delay between sampling and subsequent DA provides a potential opportunity to divert the material out of the appropriate chemical stream. Leveraging new on-line nondestructive assay (NDA) techniques in conjunction with the traditional and highly precise DA methods may provide a more timely, cost-effective and resource efficient means for MC&A verification at such facilities. Pacific Northwest National Laboratory (PNNL) is developing on-line NDA process monitoring technologies, including the Multi-Isotope Process (MIP) Monitor. The MIP Monitor uses gamma spectroscopy and pattern recognition software to identify off-normal conditions in process streams. Recent efforts have been made to explore the basic limits of using multivariate analysis techniques on gamma-ray spectra. This paper will provide an overview of the methods and report our on-going efforts to develop and demonstrate the technology.

  8. GEANT4 calibration of gamma spectrometry efficiency for measurements of airborne radioactivity on filter paper.

    PubMed

    Alrefae, Tareq

    2014-11-01

    A simple method of efficiency calibration for gamma spectrometry was performed. This method, which focused on measuring airborne radioactivity collected on filter paper, was based on Monte Carlo simulations using the toolkit GEANT4. Experimentally, the efficiency values of an HPGe detector were calculated for a multi-gamma disk source. These efficiency values were compared to their counterparts produced by a computer code that simulated experimental conditions. Such comparison revealed biases of 24, 10, 1, 3, 7, and 3% for the radionuclides (photon energies in keV) of Ce (166), Sn (392), Cs (662), Co (1,173), Co (1,333), and Y (1,836), respectively. The output of the simulation code was in acceptable agreement with the experimental findings, thus validating the proposed method.

  9. Evaluation of radiological data of some saturated fatty acids using gamma ray spectrometry

    NASA Astrophysics Data System (ADS)

    Kore, Prashant S.; Pawar, Pravina P.; Palani Selvam, T.

    2016-02-01

    Radiological parameters such as mass attenuation coefficients (μm), total attenuation cross section (σtot), molar extinction coefficient (ε), mass energy absorption coefficient (μen/ρ) and effective electronic cross section (σt, el) of saturated fatty acids, namely butyric acid (C4H8O2), caproic acid (C6H12O2), enanthic acid (C7H14O2), caprylic acid (C8H16O2), pelargonic acid (C9H18O2) and valeric acid (C5H10O2) were measured using NaI(Tl)-based gamma spectrometry. Radioactive sources used in the study are 57Co, 133Ba, 137Cs, 54Mn, 60Co and 22Na. Gamma ray transmission method in a narrow beam good geometry set up was used in the study. The measured data were compared against Win-XCOM-based data. The agreement is within 1%.

  10. Fluence Evaluations For Applications of In Situ Gamma-Ray Spectrometry in Non-Flat Terrain

    SciTech Connect

    Miller, Kevin M.

    1999-02-28

    Evaluations of gamma-ray fluence are made for source geometries that depart from the flat ground geometry that is used in standard applications of in situ spectrometry. Geometries considered include uniform source distributions for soil mounds on top of flat terrain, cylindrical wells, and rectangular trenches. The results indicate that scaling the standard fluence values for flat terrain by the ratio of solid angle subtended by the soil to 2π leads to fluence estimates that are accurate to within a few percent. Practical applications of in situ spectrometry in non-flat terrain also appears to be simplified by the fact that the angular correction factor for a typical coaxial detector in these geometries may typically be about the same as that computed for flat ground.

  11. A new technique for processing airborne gamma ray spectrometry data for mapping low level contaminations.

    PubMed

    Aage, H K; Korsbech, U; Bargholz, K; Hovgaard, J

    1999-12-01

    A new technique for processing airborne gamma ray spectrometry data has been developed. It is based on the noise adjusted singular value decomposition method introduced by Hovgaard in 1997. The new technique opens for mapping of very low contamination levels. It is tested with data from Latvia where the remaining contamination from the 1986 Chernobyl accident together with fallout from the atmospheric nuclear weapon tests includes 137Cs at levels often well below 1 kBq/m2 equivalent surface contamination. The limiting factors for obtaining reliable results are radon in the air, spectrum stability and accurate altitude measurements.

  12. Precipitation correction of airborne gamma-ray spectrometry data using monitoring profiles: methodology and case study

    NASA Astrophysics Data System (ADS)

    Ahl, Andreas; Motschka, Klaus; Slapansky, Peter

    2014-08-01

    Variations of soil moisture content caused by precipitation often complicate the interpretation of airborne gamma-ray spectrometry data. This is particularly the case in repeated surveys designed to monitor the change of near surface abundances of radioactive elements or in large and time-consuming surveys. To counter this precipitation effect we propose a correction method based on repeated survey flights over a monitoring profile. Assuming that the weather and the soil conditions at the monitoring profile are representative for the survey area, the weather dependent effect of soil moisture can be observed and sufficiently corrected.

  13. Measurements of activation induced by environmental neutrons using ultra low-level gamma-ray spectrometry.

    PubMed

    Martínez Canet, M J; Hult, M; Köhler, M; Johnston, P N

    2000-03-01

    The flux of environmental neutrons is being studied by activation of metal discs of selected elements. Near the earth's surface the total neutron flux is in the order of 10(-2) cm(-2)s(-1), which gives induced activities of a few mBq in the discs. Initial results from this technique, involving activation at ground level for several materials (W, Au, Ta, In, Re, Sm, Dy and Mn) and ultra low-level gamma-ray spectrometry in an underground laboratory located at 500 m.w.e., are presented. Diffusion of environmental neutrons in water is also measured by activation of gold at different depths.

  14. Characterisation of uranium(VI) sorption by two environmental fungal species using gamma spectrometry.

    PubMed

    Gargarello, R; Cavalitto, S; Di Gregorio, D; Niello, J Fernández; Huck, H; Pardo, A; Somacal, H; Curutchet, G

    2008-12-01

    Uranium(VI) sorption by two highly uranium-resistant air-borne fungi in a low-pH medium was measured by means of gamma spectrometry. Growth kinetics and stoichiometry of the two fungal species were also studied. Results show acceptable growth rates in synthetic medium with glucose and ammonia as carbon and nitrogen sources, respectively. Typical oxidative metabolism of carbohydrates was found. In vivo uptake of the radionuclide was negligible, but biosorption dry biomass presented a remarkable performance. The fungal strains showed potential for use in bioremediation.

  15. Nuclear chemistry of returned lunar samples: Nuclide analysis by gamma-ray spectrometry

    NASA Technical Reports Server (NTRS)

    Okelley, G. D.

    1975-01-01

    Primordial and cosmogenic radionuclide concentrations are determined nondestructively by gamma-ray spectrometry in soil and rock samples from the returned Apollo 17 sample collection from Taurus-Littrow and Descartes. Geochemical evidence in support of field geology speculation concerning layering of the subfloor basalt flows is demonstrated along with a possible correlation of magmatic fractionation of K/U as a function of depth. The pattern of radionuclide concentrations observed in these samples is distinct due to proton bombardment by the intense solar flares of August 4-9, 1972. Such radionuclide determinations are used in determining lunar sample orientation and characterizing solar flare activity.

  16. Development and calibration of a real-time airborne radioactivity monitor using direct gamma-ray spectrometry with two scintillation detectors.

    PubMed

    Casanovas, R; Morant, J J; Salvadó, M

    2014-07-01

    The implementation of in-situ gamma-ray spectrometry in an automatic real-time environmental radiation surveillance network can help to identify and characterize abnormal radioactivity increases quickly. For this reason, a Real-time Airborne Radioactivity Monitor using direct gamma-ray spectrometry with two scintillation detectors (RARM-D2) was developed. The two scintillation detectors in the RARM-D2 are strategically shielded with Pb to permit the separate measurement of the airborne isotopes with respect to the deposited isotopes.In this paper, we describe the main aspects of the development and calibration of the RARM-D2 when using NaI(Tl) or LaBr3(Ce) detectors. The calibration of the monitor was performed experimentally with the exception of the efficiency curve, which was set using Monte Carlo (MC) simulations with the EGS5 code system. Prior to setting the efficiency curve, the effect of the radioactive source term size on the efficiency calculations was studied for the gamma-rays from (137)Cs. Finally, to study the measurement capabilities of the RARM-D2, the minimum detectable activity concentrations for (131)I and (137)Cs were calculated for typical spectra at different integration times.

  17. Measurement of uranium series radionuclides in rock and groundwater at the Koongarra ore deposit, Australia, by gamma spectrometry

    SciTech Connect

    Yanase, Nobuyuki; Sekine, Keiichi

    1995-12-31

    Gamma spectrometry without any self-absorption correction was developed to measure low energy gamma rays emitted by uranium and actinium series radionuclides in rock samples and groundwater residues collected at the Koongarra ore deposit, Australia. Thin samples were prepared to minimize the self-absorption by uranium in the samples. The present method gave standard deviations of 0.9 to 18% for the measurements of concentrations of uranium and actinium series radionuclides. The concentrations of {sup 238}U, {sup 230}Th and {sup 235}U measured by gamma spectrometry were compared with those by alpha spectrometry that requires a complicated chemical separation procedure. The results obtained by both methods were in fairly good agreement, and it was found that the gamma spectrometry is applicable to rock and groundwater samples having uranium content sup to 8.1% (10{sup 3} B1/g) and 3 Bq/l of {sup 238}U, respectively. The detection limits were calculated to be of the order of 10{sup {minus}2} Bq/g for rock samples and 10{sup {minus}1} Bq/l for groundwater samples. The concentrations of uranium and actinium series radionuclides can be determined precisely in these samples using gamma spectrometry without any self-absorption correction.

  18. Combinatorial Approach for Large-scale Identification of Linked Peptides from Tandem Mass Spectrometry Spectra*

    PubMed Central

    Wang, Jian; Anania, Veronica G.; Knott, Jeff; Rush, John; Lill, Jennie R.; Bourne, Philip E.; Bandeira, Nuno

    2014-01-01

    The combination of chemical cross-linking and mass spectrometry has recently been shown to constitute a powerful tool for studying protein–protein interactions and elucidating the structure of large protein complexes. However, computational methods for interpreting the complex MS/MS spectra from linked peptides are still in their infancy, making the high-throughput application of this approach largely impractical. Because of the lack of large annotated datasets, most current approaches do not capture the specific fragmentation patterns of linked peptides and therefore are not optimal for the identification of cross-linked peptides. Here we propose a generic approach to address this problem and demonstrate it using disulfide-bridged peptide libraries to (i) efficiently generate large mass spectral reference data for linked peptides at a low cost and (ii) automatically train an algorithm that can efficiently and accurately identify linked peptides from MS/MS spectra. We show that using this approach we were able to identify thousands of MS/MS spectra from disulfide-bridged peptides through comparison with proteome-scale sequence databases and significantly improve the sensitivity of cross-linked peptide identification. This allowed us to identify 60% more direct pairwise interactions between the protein subunits in the 20S proteasome complex than existing tools on cross-linking studies of the proteasome complexes. The basic framework of this approach and the MS/MS reference dataset generated should be valuable resources for the future development of new tools for the identification of linked peptides. PMID:24493012

  19. The use of gamma spectrometry in the determination of fission products migration in irradiated fuel

    SciTech Connect

    2015-07-01

    Non destructive examinations realized in hot cells of LECA STAR facility give main data on irradiated fuel rods and pins. Among those examinations, gamma spectrometry allows access to fuel, inside the cladding, thanks to gamma rays of fission products such as {sup 137}Cs, {sup 154}Eu coming from pellets... From those gamma scannings we can detect the position and the length of the fuel column and of its pellets, calculate local burnup.. In the database of our lab we have already such gamma scannings on hundreds of rods or pins with different fuels, claddings and irradiations conditions (under nominal or non nominal). We have detected that in specific cases, an unusual shape of the {sup 137}Cs scanning (distribution quite different from those of {sup 154}Eu) can be explained by the migration of this isotope, moving to the cold sides of the pellet. This phenomenon is mainly associated with an increasing of the pellet's temperature. Based on our observations, we have developed a quantitative approach of the changes on the {sup 137}Cs scannings through the calculation of appropriate 'indicators'. Those calculations allow us to be able to localize, quantify and compare the {sup 137}Cs migration all along rods or pins. Those migration results are so quickly and easily achievable from gamma measurements and can then be easily correlated to other observations realized with destructive examinations, puncturing and calculations, already realized or to come. Because such a migration is the result of temperature increasing in the pellets, our indicators can be directly associated with this local temperature. In perspective, thermically activated phenomena such as geometrical changes in the shape of the pellets, fission gas release... can also indirectly be deduced from our indicators. (authors)

  20. Determination of radionuclide levels in rainwater using ion exchange resin and gamma-spectrometry.

    PubMed

    Jungck, Matthias H A; Andrey, Jean-Louis; Froidevaux, Pascal

    2009-04-01

    The evaluation of radioactivity accidentally released into the atmosphere involves determining the radioactivity levels of rainwater samples. Rainwater scavenges atmospheric airborne radioactivity in such a way that surface contamination can be deduced from rainfall rate and rainwater radioactivity content. For this purpose, rainwater is usually collected in large surface collectors and then measured by gamma-spectrometry after such treatments as evaporation or iron hydroxide precipitation. We found that collectors can be adapted to accept large surface (diameter 47mm) cartridges containing a strongly acidic resin (Dowex AG 88) which is able to quantitatively extract radioactivity from rainwater, even during heavy rainfall. The resin can then be measured by gamma-spectrometry. The detection limit is 0.1Bq per sample of resin (80g) for (137)Cs. Natural (7)Be and (210)Pb can also be measured and the activity ratio of both radionuclides is comparable with those obtained through iron hydroxide precipitation and air filter measurements. Occasionally (22)Na has also been measured above the detection limit. A comparison between the evaporation method and the resin method demonstrated that 2/3 of (7)Be can be lost during the evaporation process. The resin method is simple and highly efficient at extracting radioactivity. Because of these great advantages, we anticipate it could replace former rainwater determination methods. Moreover, it does not necessitate the transportation of large rainwater volumes to the laboratory.

  1. Construction and testing of a neutron and gamma spectrometry system using pulse shape discrimination with an organic scintillator

    NASA Astrophysics Data System (ADS)

    Pope, Robert S.

    1993-03-01

    The goal of this thesis was to construct and test a neutron detector to measure the energy spectrum of 1 to 14-MeV neutrons in the presence of gammas. A spectrometer based on the process of pulse shape discrimination (PSD) was constructed, in which the scintillator NE-213 was used. The primary neutron/gamma sources used were 78-mCi and 4.7-Ci Pu-239Be sources, while 4.7-micro-Ci and 97.6-micro-Ci Na-22 gamma sources were used for energy calibration and additional testing of the detector. Proton recoil spectra and Compton electron spectra were unfolded with the neutron and gamma unfolding code FORIST to generate the incident neutron and gamma spectra, respectively. FORIST, which was written for a CDC computer, was modified to run on a VAX 6420. The experimental spectra were compared to those in the literature. The locations of the peaks in the Pu-239Be spectrum agreed with the literature to within 8.3%, the Pu-239Be gamma spectrum agreed to within 0.7%, while the Na-22 gamma spectrum agreed exactly. Uncertainties in the detection system and unfolding procedure are on the order of 5-10%. This thesis is intended to be a summary of the relevant literature and a user's guide to the PSD spectrometer.

  2. Rapid determination of (237)Np in soil samples by multi-collector inductively-coupled plasma mass spectrometry and gamma spectrometry.

    PubMed

    Yi, Xiaowei; Shi, Yanmei; Xu, Jiang; He, Xiaobing; Zhang, Haitao; Lin, Jianfeng

    A radiochemical procedure is developed for the determination of (237)Np in soil with multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) and gamma-spectrometry. (239)Np (milked from (243)Am) was used as an isotopic tracer for chemical yield determination. The neptunium in the soil is separated by thenoyl-trifluoracetone extraction from 1 M HNO3 solution after reducing Np to Np(IV) with ferrous sulfamate, and then purified with Dowex 1 × 2 anion exchange resin. (239)Np in the resulting solution is measured with gamma-spectrometry for chemical yield determination while the (237)Np is measured with MC-ICP-MS. Measurement results for soil samples are presented together with those for two reference samples. By comparing the determined value with the reference value of the (237)Np activity concentration, the feasibility of the procedure was validated.

  3. An analysis of nuclear fuel burnup in the AGR-1 TRISO fuel experiment using gamma spectrometry, mass spectrometry, and computational simulation techniques

    SciTech Connect

    Harp, Jason M.; Demkowicz, Paul A.; Winston, Philip L.; Sterbentz, James W.

    2014-09-03

    AGR 1 was the first in a series of experiments designed to test US TRISO fuel under high temperature gas-cooled reactor irradiation conditions. This experiment was irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) and is currently undergoing post irradiation examination (PIE) at INL and Oak Ridge National Laboratory. One component of the AGR 1 PIE is the experimental evaluation of the burnup of the fuel by two separate techniques. Gamma spectrometry was used to non destructively evaluate the burnup of all 72 of the TRISO fuel compacts that comprised the AGR 1 experiment. Two methods for evaluating burnup by gamma spectrometry were developed, one based on the Cs 137 activity and the other based on the ratio of Cs 134 and Cs 137 activities. Burnup values determined from both methods compared well with the values predicted from simulations. The highest measured burnup was 20.1% FIMA for the direct method and 20.0% FIMA for the ratio method (compared to 19.56% FIMA from simulations). An advantage of the ratio method is that the burnup of the cylindrical fuel compacts can determined in small (2.5 mm) axial increments and an axial burnup profile can be produced. Destructive chemical analysis by inductively coupled mass spectrometry (ICP MS) was then performed on selected compacts that were representative of the expected range of fuel burnups in the experiment to compare with the burnup values determined by gamma spectrometry. The compacts analyzed by mass spectrometry had a burnup range of 19.3% FIMA to 10.7% FIMA. The mass spectrometry evaluation of burnup for the four compacts agreed well with the gamma spectrometry burnup evaluations and the expected burnup from simulation. For all four compacts analyzed by mass spectrometry, the maximum range in the three experimentally determined values and the predicted value was 6% or less. Furthermore, the results confirm the accuracy of the nondestructive burnup evaluation from gamma spectrometry

  4. An analysis of nuclear fuel burnup in the AGR-1 TRISO fuel experiment using gamma spectrometry, mass spectrometry, and computational simulation techniques

    DOE PAGES

    Harp, Jason M.; Demkowicz, Paul A.; Winston, Philip L.; ...

    2014-09-03

    AGR 1 was the first in a series of experiments designed to test US TRISO fuel under high temperature gas-cooled reactor irradiation conditions. This experiment was irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) and is currently undergoing post irradiation examination (PIE) at INL and Oak Ridge National Laboratory. One component of the AGR 1 PIE is the experimental evaluation of the burnup of the fuel by two separate techniques. Gamma spectrometry was used to non destructively evaluate the burnup of all 72 of the TRISO fuel compacts that comprised the AGR 1 experiment. Two methodsmore » for evaluating burnup by gamma spectrometry were developed, one based on the Cs 137 activity and the other based on the ratio of Cs 134 and Cs 137 activities. Burnup values determined from both methods compared well with the values predicted from simulations. The highest measured burnup was 20.1% FIMA for the direct method and 20.0% FIMA for the ratio method (compared to 19.56% FIMA from simulations). An advantage of the ratio method is that the burnup of the cylindrical fuel compacts can determined in small (2.5 mm) axial increments and an axial burnup profile can be produced. Destructive chemical analysis by inductively coupled mass spectrometry (ICP MS) was then performed on selected compacts that were representative of the expected range of fuel burnups in the experiment to compare with the burnup values determined by gamma spectrometry. The compacts analyzed by mass spectrometry had a burnup range of 19.3% FIMA to 10.7% FIMA. The mass spectrometry evaluation of burnup for the four compacts agreed well with the gamma spectrometry burnup evaluations and the expected burnup from simulation. For all four compacts analyzed by mass spectrometry, the maximum range in the three experimentally determined values and the predicted value was 6% or less. Furthermore, the results confirm the accuracy of the nondestructive burnup evaluation from gamma

  5. Inter-pulse high-resolution gamma-ray spectra using a 14 MeV pulsed neutron generator

    USGS Publications Warehouse

    Evans, L.G.; Trombka, J.I.; Jensen, D.H.; Stephenson, W.A.; Hoover, R.A.; Mikesell, J.L.; Tanner, A.B.; Senftle, F.E.

    1984-01-01

    A neutron generator pulsed at 100 s-1 was suspended in an artificial borehole containing a 7.7 metric ton mixture of sand, aragonite, magnetite, sulfur, and salt. Two Ge(HP) gamma-ray detectors were used: one in a borehole sonde, and one at the outside wall of the sample tank opposite the neutron generator target. Gamma-ray spectra were collected by the outside detector during each of 10 discrete time windows during the 10 ms period following the onset of gamma-ray build-up after each neutron burst. The sample was measured first when dry and then when saturated with water. In the dry sample, gamma rays due to inelastic neutron scattering, neutron capture, and decay were counted during the first (150 ??s) time window. Subsequently only capture and decay gamma rays were observed. In the wet sample, only neutron capture and decay gamma rays were observed. Neutron capture gamma rays dominated the spectrum during the period from 150 to 400 ??s after the neutron burst in both samples, but decreased with time much more rapidly in the wet sample. A signal-to-noise-ratio (S/N) analysis indicates that optimum conditions for neutron capture analysis occurred in the 350-800 ??s window. A poor S/N in the first 100-150 ??s is due to a large background continuum during the first time interval. Time gating can be used to enhance gamma-ray spectra, depending on the nuclides in the target material and the reactions needed to produce them, and should improve the sensitivity of in situ well logging. ?? 1984.

  6. Cosmic veto gamma-spectrometry for Comprehensive Nuclear-Test-Ban Treaty samples

    NASA Astrophysics Data System (ADS)

    Burnett, J. L.; Davies, A. V.

    2014-05-01

    The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is supported by a global network of monitoring stations that perform high-resolution gamma-spectrometry on air filter samples for the identification of 85 radionuclides. At the UK CTBT Radionuclide Laboratory (GBL15), a novel cosmic veto gamma-spectrometer has been developed to improve the sensitivity of station measurements, providing a mean background reduction of 80.8% with mean MDA improvements of 45.6%. The CTBT laboratory requirement for a 140Ba MDA is achievable after 1.5 days counting compared to 5-7 days using conventional systems. The system consists of plastic scintillation plates that detect coincident cosmic-ray interactions within an HPGe gamma-spectrometer using the Canberra LynxTM multi-channel analyser. The detector is remotely configurable using a TCP/IP interface and requires no dedicated coincidence electronics. It would be especially useful in preventing false-positives at remote station locations (e.g. Halley, Antarctica) where sample transfer to certified laboratories is logistically difficult. The improved sensitivity has been demonstrated for a CTBT air filter sample collected after the Fukushima incident.

  7. The 124Sb activity standardization by gamma spectrometry for medical applications

    NASA Astrophysics Data System (ADS)

    de Almeida, M. C. M.; Iwahara, A.; Delgado, J. U.; Poledna, R.; da Silva, R. L.

    2010-07-01

    This work describes a metrological activity determination of 124Sb, which can be used as radiotracer, applying gamma spectrometry methods with hyper pure germanium detector and efficiency curves. This isotope with good activity and high radionuclidic purity is employed in the form of meglumine antimoniate (Glucantime) or sodium stibogluconate (Pentostam) to treat leishmaniasis. 124Sb is also applied in animal organ distribution studies to solve some questions in pharmacology. 124Sb decays by β-emission and it produces several photons (X and gamma rays) with energy varying from 27 to 2700 keV. Efficiency curves to measure point 124Sb solid sources were obtained from a 166mHo standard that is a multi-gamma reference source. These curves depend on radiation energy, sample geometry, photon attenuation, dead time and sample-detector position. Results for activity determination of 124Sb samples using efficiency curves and a high purity coaxial germanium detector were consistent in different counting geometries. Also uncertainties of about 2% ( k=2) were obtained.

  8. NMIS with Imaging and Gamma Ray Spectrometry for Pu, HEU, HE and Other Materials

    SciTech Connect

    Mihalczo, John T; Mullens, James Allen

    2012-03-01

    The Nuclear Material Identification System (NMIS) has been under development at ORNL and the National Nuclear Security Administration (NNSA) Y-12 National Security Complex since 1984. In the mid-1990s, what is now the US Department of Energy (DOE) Office of Nuclear Verification (ONV) realized that it was a useful technology for future arms control treaty applications and supported further development of the system. In 2004, fast-neutron imaging was incorporated into the system. In 2007, the ONV decided to develop a fieldable version of the system, designated as FNMIS, for potential use in future treaties. The FNMIS is being developed to be compatible with the eventual incorporation of gamma-ray spectrometry and an information barrier. This report addresses how and what attributes could be determined by the FNMIS system with gamma-ray spectrometry. The NMIS is a time-dependent coincidence system that incorporates tomographic imaging (including mapping of the fission sites) and gamma-ray spectrometry. It utilizes a small, lightweight (30 lb), portable deuterium-tritium (DT) neutron (14.1 MeV) generator (4 x 10{sup 7} neutrons/second) for active interrogation and can also perform passive interrogation. A high-purity germanium (HPGe) gamma-ray detector with multichannel analysis can be utilized in conjunction with the source for active interrogation or passively. The system uses proton recoil scintillators: 32 small 2.5 x 2.5 x 10.2-cm-thick plastic scintillators for imaging and at least two 2 x 2 arrays of 27 x 27 x 10-cm-thick plastic scintillators that detect induced fission radiation. The DT generator contains an alpha detector that time and directionally tags a fan beam of some of the neutrons emitted and subdivides it into pixels. A fast (1 GHz) time correlation processor measures the time-dependent coincidence among all detectors in the system. A computer-controlled scanner moves the small detectors and the source appropriately for scanning a target object for

  9. F-GAMMA: On the phenomenological classification of continuum radio spectra variability patterns of Fermi blazars

    NASA Astrophysics Data System (ADS)

    Angelakis, E.; Fuhrmann, L.; Nestoras, I.; Fromm, C. M.; Perucho-Pla, M.; Schmidt, R.; Zensus, J. A.; Marchili, N.; Krichbaum, T. P.; Ungerechts, H.; Sievers, A.; Riquelme, D.; Pavlidou, V.

    2012-07-01

    The F-GAMMA program is a coordinated effort to investigate the physics of Active Galactic Nuclei (AGNs) via multi-frequency monitoring of Fermi blazars. In the current study we show and discuss the evolution of broad-band radio spectra, which are measured at ten frequencies between 2.64 and 142 GHz using the Effelsberg 100-m and the IRAM 30-m telescopes. It is shown that any of the 78 sources studied can be classified in terms of their variability characteristics in merely 5 types of variability. It is argued that these can be attributed to only two classes of variability mechanisms. The first four types are dominated by spectral evolution and can be described by a simple two-component system composed of: (a) a steep quiescent spectral component from a large scale jet and (b) a time evolving flare component following the "Shock-in-Jet" evolutionary path. The fifth type is characterised by an achromatic change of the broad band spectrum, which could be attributed to a different mechanism, likely involving differential Doppler boosting caused by geometrical effects. Here we present the classification, the assumed physical scenario and the results of calculations that have been performed for the spectral evolution of flares.

  10. BATSE observations of gamma-ray burst spectra. 2: Peak energy evolution in bright, long bursts

    NASA Technical Reports Server (NTRS)

    Ford, L. A.; Band, D. L.; Matteson, J. L.; Briggs, M. S.; Pendleton, G. N.; Preece, R. D.; Paciesas, W. S.; Teegarden, B. J.; Palmer, D. M.; Schaefer, B. E.

    1995-01-01

    We investigate spectral evolution in 37 bright, long gamma-ray bursts observed with the Burst and Transient Source Experiment (BATSE) spectroscopy detectors. High-resolution spectra are chracterized by the energy of the peak of nu F(sub nu), and the evolution of this quantity is examined relative to the emission intensity. In most cases it is found that this peak energy either rises with or slightly precedes major intensity increases and softens for the remainder of the pulse. Interpulse emission is generally harder early in the burst. For bursts with multiple intensity pulses, later spikes tend to be softer than earlier ones, indicating that the energy of the peak of nu F(sub nu) is bounded by an envelope which decays with time. Evidence is found that bursts in which the bulk of the flux comes well after the event which triggers the instrument tend to show less peak energy variability and are not as hard as several bursts in which the emission occurs promptly after the trigger. Several recently proposed burst models are examined in light of these results and no qualitative conflicts with the observations presented here are found.

  11. Peak fitting and identification software library for high resolution gamma-ray spectra

    NASA Astrophysics Data System (ADS)

    Uher, Josef; Roach, Greg; Tickner, James

    2010-07-01

    A new gamma-ray spectral analysis software package is under development in our laboratory. It can be operated as a stand-alone program or called as a software library from Java, C, C++ and MATLAB TM environments. It provides an advanced graphical user interface for data acquisition, spectral analysis and radioisotope identification. The code uses a peak-fitting function that includes peak asymmetry, Compton continuum and flexible background terms. Peak fitting function parameters can be calibrated as functions of energy. Each parameter can be constrained to improve fitting of overlapping peaks. All of these features can be adjusted by the user. To assist with peak identification, the code can automatically measure half-lives of single or multiple overlapping peaks from a time series of spectra. It implements library-based peak identification, with options for restricting the search based on radioisotope half-lives and reaction types. The software also improves the reliability of isotope identification by utilizing Monte-Carlo simulation results.

  12. Hydride formation and thermal desorption spectra of hydrogen of cathodically charged single-phase gamma titanium aluminide

    SciTech Connect

    Takasaki, Akito; Furuya, Yoshio

    1999-02-05

    The authors have previously reported thermal desorption spectra of hydrogen obtained from cathodically charged two-phase (Ti{sub 3}Al ({alpha}{sub 2}) + TiAl ({gamma})) titanium aluminides by means of thermal desorption spectroscopy (TDS), in which hydrogen ion current (H{sub 2}{sup +}) corresponding to hydrogen evolution rate during heating was measured by a quadrupole mass spectrometer in an ultra-high vacuum condition. Several accelerated hydrogen evolutions (TDS peak temperatures) have been observed in a series of TDS measurement, and then the authors have suggested that these peaks were dependent on the microstructures ({alpha}{sub 2} and {gamma} phases) as well as dissociation of the hydride phase which formed during cathodic charging. A comparison with the TDS spectra from other series of titanium aluminides, such as a single-phase {gamma} alloy, might give clearer views of the microstructural dependence on hydrogen evolution kinetics. In this paper, hydride formation, hydrogen uptake and hydrogen evolution kinetic of a cathodically charged single-phase {gamma} titanium aluminide are investigated, and these results are compared with the previous ones obtained in two-phase ({alpha}{sub 2} + {gamma}) titanium aluminides.

  13. Numerical simulations of planetary gamma-ray spectra induced by galactic cosmic rays

    SciTech Connect

    Masarik, J.; Reedy, R.C.

    1994-07-01

    The fluxes of cosmic-ray-produced gamma rays escaping from Mars were calculated using the LAHET Code System and basic nuclear data for {gamma}-ray production. Both surface water content and atmospheric thickness strongly affect the fluxes of {gamma}-ray lines escaping from Mars.

  14. Seven years of gamma-ray spectrometry interlaboratory comparisons in Switzerland.

    PubMed

    Bailat, Claude; Buchillier, Thierry; Caffari, Yvan; Nedjadi, Youcef; Spring, Philippe; Estier, Sybille; Bochud, François

    2010-01-01

    Since the 1990s, regular comparisons of gamma-ray spectrometry in Switzerland were organized to improve laboratory abilities to measure the radioactivity in the environment and food stuffs at typical routine levels. The activity concentration of the test samples and the evaluation of the associated uncertainties remained each year the main required test result. Over the years, the comparisons used certified reference solutions as well as environmental samples. The aim of this study is to research the effect of the comparisons on measurement quality. An analysis of the seven last interlaboratory comparisons revealed that the Swiss measurement capability is up to date. In addition, the results showed that the participants now have an improved evaluation of the uncertainties associated with their measurement.

  15. Recent developments in ultra low-level gamma-ray spectrometry at IRMM

    PubMed

    Hult; Martinez Canet MJ; Kohler; das Neves J; Johnston

    2000-07-01

    IRMM performs ultra low-level gamma-ray spectrometry in the underground laboratory HADES, located at the SCK-CEN site in Mol, Belgium. Recently a third low-background coaxial HPGe detector was put into operation. The detector has 60% relative efficiency and better background characteristics than the two previous detectors: The shield comprises 14 cm of lead with 21OPb specific activity of 20 Bq kg(-1) and 14 cm of freshly produced electrolytic copper. The background count rate integrated from 40 to 2700 keV is 394 +/- 2 counts per day. Details of the background and the shield are presented together with applications to nuclear safeguards and material selection.

  16. A review of the nationwide proficiency test on natural radioactivity measurements by gamma spectrometry.

    PubMed

    Şahin, N K; Yeltepe, E; Yücel, Ü

    2016-03-01

    This study is the review of the first proficiency test on radioactivity measurement organized in Turkey by Sarayköy Nuclear Research and Training Center (SANAEM) of Turkish Atomic Energy Authority (TAEK) in 2013. The objective of the test was to determine (226)Ra, (232)Th and (40)K activity concentrations in natural soil samples using gamma-ray spectrometry. The bulk material consisting of uranium- and thorium-rich soil and sand was milled, mixed thoroughly and sieved. Homogeneity of the final mix was tested with 6 randomly taken samples. 16 proficiency test samples were distributed to 16 participating laboratories. 12 laboratories reported results. The results were evaluated on the accuracy and precision criteria adopted by the IAEA Proficiency Testing Group. The percentage of acceptable scores was 49%. Some recommendations have been provided to the laboratories to improve the quality of their results. It is planned to extend these proficiency tests periodically for various radionuclides in various matrices.

  17. Summary of gamma spectrometry on local air samples from 1985--1995

    SciTech Connect

    Winn, W.G.

    1997-04-02

    This report summarizes the 1985--1995 results of low-level HPGe gamma spectrometry analysis of high-volume air samples collected at the Aiken Airport, which is about 25 miles north of SRS. The author began analyzing these samples with new calibrations using the newly developed GRABGAM code in 1985. The air sample collections were terminated in 1995, as the facilities at the Aiken Airport were no longer available. Air sample measurements prior to 1985 were conducted with a different analysis system (and by others prior to 1984), and the data were not readily available. The report serves to closeout this phase of local NTS air sample studies, while documenting the capabilities and accomplishments. Hopefully, the information will guide other applications for this technology, both locally and elsewhere.

  18. Gamma-ray spectrometry in the cascade area of a gas centrifuge enrichment plant

    SciTech Connect

    Lauppe, W.D.; Richter, B.; Stein, G.

    1985-01-01

    In the frame of the programme of the Federal Republic of Germany in support of the IAEA, measurements were performed in the SP4 gas centrifuge enrichment plant in Almelo, the Netherlands. The objective was the investigation of the applicability of non-destructive ..gamma..-spectrometry equipment - presently available to the IAEA - at uranium-hexafluoride cascade piping for the purpose of measuring the uranium enrichment. The measurement locations were chosen at the product pipework between the top of a cascade and the first valve, which is inside the cascade area. Taking account of the results of the Hexapartite Safeguards Project, the measurement method should be capable of giving a go/no go result on current and preceding production of high-enriched uranium. The paper gives a description of the acquired measurement method and evaluation. The measurement results are discussed and conclusions are drawn.

  19. Semi-automated structural analysis of high resolution magnetic and gamma-ray spectrometry airborne surveys

    NASA Astrophysics Data System (ADS)

    Debeglia, N.; Martelet, G.; Perrin, J.; Truffert, C.; Ledru, P.; Tourlière, B.

    2005-08-01

    A user-controlled procedure was implemented for the structural analysis of geophysical maps. Local edge segments are first extracted using a suitable edge detector function, then linked into straight discontinuities and, finally, organised in complex boundary lines best delineating geophysical features. Final boundary lines may be attributed by a geologist to lithological contacts and/or structural geological features. Tests of some edge detectors, (i) horizontal gradient magnitude (HGM), (ii) various orders of the analytic signal ( An), reduced to the pole or not, (iii) enhanced horizontal derivative (EHD), (iv) composite analytic signal (CAS), were performed on synthetic magnetic data (with and without noise). As a result of these comparisons, the horizontal gradient appears to remain the best operator for the analysis of magnetic data. Computation of gradients in the frequency domain, including filtering and upward continuation of noisy data, is well-suited to the extraction of magnetic gradients associated to deep sources, while space-domain smoothing and differentiation techniques is generally preferable in the case of shallow magnetic sources, or for gamma-ray spectrometry analysis. Algorithms for edge extraction, segment linking, and line following can be controlled by choosing adequate edge detector and processing parameters which allows adaptation to a desired scale of interpretation. Tests on synthetic and real case data demonstrate the adaptability of the procedure and its ability to produce basic layer for multi-data analysis. The method was applied to the interpretation of high-resolution airborne magnetic and gamma-ray spectrometry data collected in northern Namibia. It allowed the delineation of dyke networks concealed by superficial weathering and demonstrated the presence of lithological variations in alluvial flows. The output from the structural analysis procedure are compatible with standard GIS softwares and enable the geologist to (i) compare

  20. CHIH-DFT determination of the molecular structure and infrared and ultraviolet spectra of gamma-solanine.

    PubMed

    Glossman-Mitnik, Daniel

    2007-01-01

    Glycoalkaloids are toxic secondary plant metabolites found in potatoes, tomatoes, and eggplants and they are considered potential precursors of steroids for applications in bionanotechnology. In this work, we make use of a new model chemistry within density functional theory, which is called CHIH-DFT, to calculate the molecular structure of gamma-solanine, as well to predict its infrared (IR) and ultraviolet (UV-vis) spectra, and some other electronic parameters.

  1. Short versus long gamma-ray bursts: spectra, energetics, and luminosities

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Nava, L.; Ghisellini, G.; Celotti, A.; Firmani, C.

    2009-03-01

    We compare the spectral properties of 79 short and 79 long Gamma-Ray Bursts (GRBs) detected by BATSE and selected with the same limiting peak flux. Short GRBs have a low-energy spectral component harder and a peak energy slightly higher than long GRBs, but no difference is found when comparing short GRB spectra with those of the first 1-2 s emission of long GRBs. These results confirm earlier findings for brighter GRBs. The bolometric peak flux of short GRBs correlates with their peak energy in a similar way to long bursts. Short and long GRBs populate different regions of the bolometric fluence-peak energy plane, short bursts being less energetic by a factor similar to the ratio of their durations. If short and long GRBs had similar redshift distributions, they would have similar luminosities yet different energies, which correlate with the peak energy E_peak for the population of long GRBs. We also test whether short GRBs are consistent with the E_peak-E_iso and E_peak-L_iso correlations for the available sample of short (6 events) and long (92 events) GRBs with measured redshifts and E^obs_peak: while short GRBs are inconsistent with the E_peak-E_iso correlation of long GRBs, they could follow the E_peak-L_iso correlation of long bursts. All the above indications point to short GRBs being similar to the first phases of long bursts. This suggests that a similar central engine (except for its duration) operates in GRBs of different durations.

  2. Investigation of the soil-plant transfer of primordial radionuclides in tomatoes by low-level gamma-ray spectrometry.

    PubMed

    Köhler, M; Gleisberg, B; Niese, S

    2000-01-01

    The paper presents actual data from investigations of the soil-plant transfer of the primordial radionuclides 40K, 238U, 226Ra, 210Pb and 227Ac for tomatoes growing at soils from former uranium mining areas. The analysis were carried out using low-level gamma-ray spectrometry in a 47 m deep underground laboratory. For tomato fruits transfer factors of (0.0007 +/- 0.0006) for 235U, (0.0021 +/- 0.0017) for 226Ra, (0.0015 +/- 0.0009) for 210Pb and (0.0018 +/- 0.0012) for 227Ac were obtained. The investigation of the soil-plant transfer by low-level gamma-ray spectrometry is often limited by the Compton-continuum from the always present high-energy gamma-ray emitter 40K.

  3. Measurement and calculation of fast neutron and gamma spectra in well defined cores in LR-0 reactor.

    PubMed

    Košťál, Michal; Matěj, Zdeněk; Cvachovec, František; Rypar, Vojtěch; Losa, Evžen; Rejchrt, Jiří; Mravec, Filip; Veškrna, Martin

    2017-02-01

    A well-defined neutron spectrum is essential for many types of experimental topics and is also important for both calibration and testing of spectrometric and dosimetric detectors. Provided it is well described, such a spectrum can also be employed as a reference neutron field that is suitable for validating selected cross sections. The present paper aims to compare calculations and measurements of such a well-defined spectra in geometrically similar cores of the LR-0 reactor with fuel containing slightly different enrichments (2%, 3.3% and 3.6%). The common feature to all cores is a centrally located dry channel which can be used for the insertion of studied materials. The calculation of neutron and gamma spectra was realized with the MCNP6 code using ENDF/B-VII.0, JEFF-3.1, JENDL-3.3, ROSFOND-2010 and CENDL-3.1 nuclear data libraries. Only minor differences in neutron and gamma spectra were found in the comparison of the presented reactor cores with different fuel enrichments. One exception is the gamma spectrum in the higher energy region (above 8MeV), where more pronounced variations could be observed.

  4. Critical review of gamma spectrometry detection approaches for in-plant surface deposition monitoring

    SciTech Connect

    Gregorich, Carola

    2015-07-01

    Surface deposition of activated corrosion product on oxide layers of light-water reactor primary system components is the primary source for ex-core radiation fields and personnel radiation exposure. Understanding the deposition mechanism and what factors influence the deposition and release behaviors are crucial for developing effective radiation field reduction measures. One of the available tools to assess the surface deposition is in-plant gamma spectrometry, which has been performed for several decades using either sodium iodide (NaI) or high-purity germanium (HPGe) detectors. Lately, the much more mobile cadmium-zinc-telluride (CZT) detectors are increasingly employed by stations because of their ease in use and handling. However, all of these gamma detectors face the same challenges; namely large-geometry samples of inconsistent sample compositions and sometimes gaps in the information necessary to establish proper efficiency calibrations. This paper reviews current measurements and efficiency calibration approaches taken in the industry. The validity of the measurement results and the feasibility of the data's use in understanding source term behavior is examined. Suggestions are made for the development of a more robust deposit characterization and radiation field monitoring program. (authors)

  5. An airborne gamma-ray spectrometry survey of nuclear sites in Belgium.

    PubMed

    Sanderson, D C W; Cresswell, A J; Hardeman, F; Debauche, A

    2004-01-01

    As part of a wider study to define the existing background levels in Belgium an airborne gamma-ray survey was conducted in two areas associated with nuclear sites. In the Mol area, the survey zone included areas surrounding the SCK-CEN nuclear research centre, and its associated neighbourhood which includes radioactive waste stores, fuel manufacture and fabrication facilities and an international accelerator laboratory. In the vicinity of Fleurus, the survey included the IRE complex with radiochemical laboratories, irradiation facilities and stores, and isotope production accelerators. The survey was conducted using a twin engined helicopter equipped with a combined scintillation and semiconductor spectrometer. The system was installed and tested in the UK, and then transferred to Belgium for operations. The complete survey was conducted successfully within 1 week. The results provide a comprehensive record of the radiation environment of the nuclear sites at time of survey, and show a range of signals associated with the types of activity present in each area. They confirm that radiation fields are largely confined to the operational sites, and provide a traceable record against which future changes could be assessed. The demonstration of efficient deployment between two European countries, coupled with rapid mapping of many different radiometric signals around these sites confirms the utility of the airborne gamma spectrometry approach for accurate definition of enhanced radiation fields. This has important implications for emergency response.

  6. A simple gamma spectrometry method for evaluating the burnup of MTR-type HEU fuel elements

    NASA Astrophysics Data System (ADS)

    Makmal, T.; Aviv, O.; Gilad, E.

    2016-10-01

    A simple method for the evaluation of the burnup of a materials testing reactor (MTR) fuel element by gamma spectrometry is presented. The method was applied to a highly enriched uranium MTR nuclear fuel element that was irradiated in a 5 MW pool-type research reactor for a total period of 34 years. The experimental approach is based on in-situ measurements of the MTR fuel element in the reactor pool by a portable high-purity germanium detector located in a gamma cell. To corroborate the method, analytical calculations (based on the irradiation history of the fuel element) and computer simulations using a dedicated fuel cycle burnup code ORIGEN2 were performed. The burnup of the MTR fuel element was found to be 52.4±8.8%, which is in good agreement with the analytical calculations and the computer simulations. The method presented here is suitable for research reactors with either a regular or an irregular irradiation regime and for reactors with limited infrastructure and/or resources. In addition, its simplicity and the enhanced safety it confers may render this method suitable for IAEA inspectors in fuel element burnup assessments during on-site inspections.

  7. Determination of (241)Pu by the method of disturbed radioactive equilibrium using 2πα-counting and precision gamma-spectrometry.

    PubMed

    Alekseev, I; Kuzmina, T

    2016-04-01

    A simple technique is proposed for the determination of the content of (241)Pu, which is based on disturbance of radioactive equilibrium in the genetically related (237)U←(241)Pu→(241)Am decay chain of radionuclides, with the subsequent use of 2πα-counting and precision gamma-spectroscopy for monitoring the process of restoration of that equilibrium. It has been shown that the data on dynamics of accumulation of the daughter (241)Am, which were obtained from the results of measurements of α- and γ-spectra of the samples, correspond to the estimates calculated for the chain of two genetically related radionuclides, the differences in the estimates of (241)Pu radioactivity not exceeding 2%. Combining the different methods of registration (2πα-counting, semiconductor alpha- and gamma-spectrometry) enables the proposed method to be efficiently applied both for calibration of (241)Pu-sources (from several hundreds of kBq and higher) and for radioisotopic analysis of plutonium mixtures. In doing so, there is a deep purification of (241)Pu from its daughter decay products required due to unavailability of commercial detectors that could make it possible, based only on analysis of alpha-spectra, to conduct quantitative analysis of the content of (238)Pu and (241)Am.

  8. Neutron-capture gamma-ray data for obtaining elemental abundances from planetary spectra.

    SciTech Connect

    Reedy, Robert; Frankle, S. C.

    2001-01-01

    Determination of elemental abundances is a top scientific priority of most planetary missions. Gamma-ray spectroscopy is an excellent method to determine elemental abundances using gamma rays made by nuclear reactions induced by cosmic-ray particles and by the decay of radioactive nuclides [Re73,Re78]. Many important planetary gamma rays are made by neutron-capture reactions. However, much of the data for the energies and intensities of neutron-capture gamma rays in the existing literature [e.g. Lo81] are poor [RF99,RF00]. With gamma-ray spectrometers having recently returned data from Lunar Prospector and NEAR and soon to be launch to Mars, there is a need for good data for neutron-capture gamma rays.

  9. Efficiency transfer using the GEANT4 code of CERN for HPGe gamma spectrometry.

    PubMed

    Chagren, S; Ben Tekaya, M; Reguigui, N; Gharbi, F

    2016-01-01

    In this work we apply the GEANT4 code of CERN to calculate the peak efficiency in High Pure Germanium (HPGe) gamma spectrometry using three different procedures. The first is a direct calculation. The second corresponds to the usual case of efficiency transfer between two different configurations at constant emission energy assuming a reference point detection configuration and the third, a new procedure, consists on the transfer of the peak efficiency between two detection configurations emitting the gamma ray in different energies assuming a "virtual" reference point detection configuration. No pre-optimization of the detector geometrical characteristics was performed before the transfer to test the ability of the efficiency transfer to reduce the effect of the ignorance on their real magnitude on the quality of the transferred efficiency. The obtained and measured efficiencies were found in good agreement for the two investigated methods of efficiency transfer. The obtained agreement proves that Monte Carlo method and especially the GEANT4 code constitute an efficient tool to obtain accurate detection efficiency values. The second investigated efficiency transfer procedure is useful to calibrate the HPGe gamma detector for any emission energy value for a voluminous source using one point source detection efficiency emitting in a different energy as a reference efficiency. The calculations preformed in this work were applied to the measurement exercise of the EUROMET428 project. A measurement exercise where an evaluation of the full energy peak efficiencies in the energy range 60-2000 keV for a typical coaxial p-type HpGe detector and several types of source configuration: point sources located at various distances from the detector and a cylindrical box containing three matrices was performed.

  10. gamma-Irradiation effects on the thermal decomposition behaviour and IR absorption spectra of piperacillin

    NASA Astrophysics Data System (ADS)

    Mahfouz, R. M.; Gaffar, M. A.; Abu El-Fadl, A.; Hamad, Ar. G. K.

    2003-11-01

    The thermal decomposition behaviour of unirradiated and pre-gamma-irradiated piperacillin (pipril) as a semi-synthetic penicillin antibiotic has been studied in the temperature range of (273-1072 K). The decomposition was found to proceed through three major steps both for unirradiated and gamma-irradiated samples. Neither appearance nor disappearance of new bands in the IR spectrum of piperacillin was recorded as a result of gamma-irradiation but only a decrease in the intensity of most bands was observed. A degradation mechanism was suggested to explain the bond rupture and the decrease in the intensities of IR bands of gamma-irradiated piperacillin.

  11. Gamma-ray spectrometry of granitic suites of the Paranaguá Terrane, Southern Brazil

    NASA Astrophysics Data System (ADS)

    Weihermann, Jessica Derkacz; Ferreira, Francisco José Fonseca; Cury, Leonardo Fadel; da Silveira, Claudinei Taborda

    2016-09-01

    The Paranaguá Terrane, located in the coastal portion of the states of Santa Catarina, Paraná and São Paulo in Southern Brazil is a crustal segment constituted mainly by an igneous complex, with a variety of granitic rocks inserted into the Serra do Mar ridge. The average altitude is approximately 1200 m above sea level, with peaks of up to 1800 m. Due to the difficulty of accessing the area, a shortage of outcrops and the thick weathering mantle, this terrane is understudied. This research aims to evaluate the gamma-ray spectrometry data of the granitic suites of the Paranaguá Terrane, in correspondence with the geological, petrographical, lithogeochemical, relief and mass movement information available in the literature. Aerogeophysical data were acquired along north-south lines spaced at 500 m, with a mean terrain clearance of 100 m. These data cover potassium (K, %), equivalent in thorium (eTh, ppm) and equivalent in uranium (eU, ppm). After performing a critical analysis of the data, basic (K, eU, eTh) and ternary (R-K/G-eTh/B-eU) maps were generated and then superimposed on the digital elevation model (DEM). The investigation of the radionuclide mobility across the relief and weathering mantle consisted of an analysis of the schematic profiles of elevation related with each radionuclide; a comparison of the K, eU and eTh maps with their 3D correspondents; and the study of mass movements registered in the region. A statistical comparison of lithogeochemical (K, U, Th) and geophysical (K, eU, eTh) data showed consistency in all the granitic suites studied (Morro Inglês, Rio do Poço and Canavieiras-Estrela). Through gamma-ray spectrometry, it was possible to establish relationships between scars (from mass movements) and the gamma-ray responses as well as the radionuclide mobility and the relief and to map the granitic bodies.

  12. Application of low-background gamma-ray spectrometry to monitor radioactivity in the environment and food.

    PubMed

    Khan, A J; Semkow, T M; Beach, S E; Haines, D K; Bradt, C J; Bari, A; Syed, U-F; Torres, M; Marrantino, J; Kitto, M E; Menia, T; Fielman, E

    2014-08-01

    The results are described of an upgrade of the low-background gamma-ray spectrometry laboratory at New York State Department of Health by acquiring sensitivity to low-energy gamma rays. Tuning of the spectrometer and its low-energy response characteristics are described. The spectrometer has been applied to monitor the environment by measuring aerosols and water in New York State contaminated by the 2011 Fukushima accident plume. In addition, the spectrometer has been used to monitor radioactivity in food by performing a study of cesium in Florida milk.

  13. Uncertainty of gamma-ray spectrometry measurement of environmental samples due to uncertainties in matrix composition, density and sample geometry.

    PubMed

    Kaminski, S; Jakobi, A; Wilhelm, Chr

    2014-12-01

    This paper is intended to identify the uncertainties of activities in environmental samples measured with gamma-ray spectrometry that result from uncertainties in matrix composition, density and geometrical dimensions of the sample. For that purpose efficiencies were calculated for a wide range of environmental matrices such as fresh and ashed food samples, water samples and soil samples. Compositions were mainly taken from literature. Densities and geometry parameters were varied in a range occurring in practice. Considered energies cover a range from 46.5keV to 2000keV. Finally, a couple of recommendations in respect to gamma-ray spectrometric measurements of environmental samples are given.

  14. Gamma Spectra Resulting From the Annihilation of Positrons with Electrons in Single, Selected Core Levels of Cu, Ag and Au

    SciTech Connect

    Kim, S; Eshed, A; Goktepeli, S; Sterne, P A; Koymen, A R; Chen, W C; Weiss, A H

    2005-07-25

    The {gamma}-ray energy spectra due to positron annihilation with the 3p core-level of Cu, the 4p core-level of Ag, and 5p core level of Au were obtained separately from the total annihilation spectrum by measuring the energies of {gamma}-rays time coincident with Auger electrons emitted as a result of filling the core-hole left by annihilation. The results of these measurements are compared to the total annihilation spectra and with LDA based theoretical calculations. A comparison of area normalized momentum distributions with the individual cores extracted from the Doppler measurements shows good qualitative agreement, however, in all three spectra, the calculated values of the momentum density appears to fall below the measured values as the momentum increases. The discrepancies between theory and experiment are well outside the statistical uncertainties of the experiment and become more pronounced with increasing Z going down the column from Cu to Ag to Au. The comparison with the experimental results clearly indicates that the calculations are not predicting the correct ratio of high momentum to low momentum spectral weight and suggest the need to improve the treatment of many body electron-positron correlation effects in annihilation as they pertain to core levels.

  15. Gamma-ray spectrometry across the Aalenian-Bajocian boundary in the Lusitanian Basin (Western Portugal)

    NASA Astrophysics Data System (ADS)

    Santos, Marisa; Henriques, Helena; Pena, Rui

    2016-04-01

    supply, which has enabled the faunal recovery, as well as the raise of deep infaunal foraminifers recorded at the latest part of the Discites Biochron. This could be related to the increase of calcareous nannofossil fluxes that coincide with a positive shift in carbon isotope compositions of bulk carbonate in the earliest Bajocian reported by some authors for the Murtinheira and other Iberian sections. In basin analysis of carbonate platforms the integration of major biotic turnovers and gamma-ray spectrometry data can be a useful tool in the improvement of correlation between wells and outcrops. Moreover, they assist in the interpretation of depositional environment and paleoclimatic constrains assigned to a basin.

  16. Hints of the Existence of Axion-Like-Particles From the Gamma-Ray Spectra of Cosmological Sources

    SciTech Connect

    Sanchez-Conde, M.A.; Paneque, D.; Bloom, E.; Prada, F.; Dominguez, A.; /IAA, Granada /Seville U.

    2009-06-23

    Axion Like Particles (ALPs) are predicted to couple with photons in the presence of magnetic fields. This effect may lead to a significant change in the observed spectra of gamma-ray sources such as AGNs. Here we carry out a detailed study that for the first time simultaneously considers in the same framework both the photon/axion mixing that takes place in the gamma-ray source and that one expected to occur in the intergalactic magnetic fields. An efficient photon/axion mixing in the source always means an attenuation in the photon flux, whereas the mixing in the intergalactic medium may result in a decrement and/or enhancement of the photon flux, depending on the distance of the source and the energy considered. Interestingly, we find that decreasing the value of the intergalactic magnetic field strength, which decreases the probability for photon/axion mixing, could result in an increase of the expected photon flux at Earth if the source is far enough. We also find a 30% attenuation in the intensity spectrum of distant sources, which occurs at an energy that only depends on the properties of the ALPs and the intensity of the intergalactic magnetic field, and thus independent of the AGN source being observed. Moreover, we show that this mechanism can easily explain recent puzzles in the spectra of distant gamma-ray sources, like the possible detection of TeV photons from 3C 66A (a source located at z=0.444) by MAGIC and VERITAS, which should not happen according to conventional models of photon propagation over cosmological distances. Another puzzle is the recent published lower limit to the EBL intensity at 3.6 {micro}m (which is almost twice larger as the previous one), which implies very hard spectra for some detected TeV gamma-ray sources located at z=0.1-0.2. The consequences that come from this work are testable with the current generation of gamma-ray instruments, namely Fermi (formerly known as GLAST) and imaging atmospheric Cherenkov telescopes like

  17. 137Cs measurement uncertainties and detection limits for airborne gamma spectrometry (AGS) data analysed using a spectral windows method.

    PubMed

    Cresswell, A J; Sanderson, D C W; White, D C

    2006-02-01

    The uncertainties associated with airborne gamma spectrometry (AGS) measurements analysed using a spectral windows method, and associated detection limits, have been investigated. For individual short measurements over buried 137Cs activity detection limits of 10 kBq m(-2) are achieved. These detection limits are reduced for superficial activity and longer integration times. For superficial activity, detection limits below 1 kBq m(-2) are achievable. A comparison is made with the detection limits for other data processing methods.

  18. Overview of reaction mechanisms for calculating the high energy component of fast-nucleon induced gamma spectra

    SciTech Connect

    Dietrich, F.S.

    1995-02-21

    This presentation reviews the current status of quantum mechanical models for understanding the high-energy component of gamma spectra resulting from radiative capture of fast nucleons; i.e., the part of the spectrum that is not amenable to standard statistical model (Hauser-Feshbach) treatments. These models are based on the direct-semidirect (DSD) model and its variants. Included are recent results on the extension of the DSD model to unbound final states, a discussion of problems and improvements in understanding the form factors in this model, and a brief discussion of a model closely related to the DSD, the pure-resonance model.

  19. Neutron Capture Cross Sections and Gamma Emission Spectra from Neutron Capture on 234,236,238U Measured with DANCE

    NASA Astrophysics Data System (ADS)

    Ullmann, J. L.; Mosby, S.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Jandel, M.; Kawano, T.; O'Donnell, J. M.; Rundberg, R. S.; Vieira, D. J.; Wilhelmy, J. B.; Wu, C.-Y.; Becker, J. A.; Chyzh, A.; Baramsai, B.; Mitchell, G. E.; Krticka, M.

    2014-05-01

    A new measurement of the 238U(n, γ) cross section using a thin 48 mg/cm2 target was made using the DANCE detector at LANSCE over the energy range from 10 eV to 500 keV. The results confirm earlier measurements. Measurements of the gamma-ray emission spectra were also made for 238U(n, γ) as well as 234,236U(n, γ). These measurements help to constrain the radiative strength function used in the cross-section calculations.

  20. Comparison of airborne and terrestrial gamma spectrometry measurements - evaluation of three areas in southern Sweden.

    PubMed

    Kock, Peder; Samuelsson, Christer

    2011-06-01

    The Geological Survey of Sweden (SGU) has been conducting airborne gamma spectrometry measurements of natural radioactivity in Sweden for more than 40 years. Today, the database covers about 80% of the country's land surface. This article explores the first step of putting this data into use in radioactive source search at ground level. However, in order to be able to use the airborne background measurements at ground level, SGU data must be validated against terrestrial data. In this work, we compare the SGU data with data measured by a portable backpack system. This is done for three different areas in southern Sweden. The statistical analysis shows that a linear relationship and a positive correlation exist between the air and ground data. However, this linear relationship could be revealed only when the region possessed large enough variations in areal activity. Furthermore, the activity distributions measured show good agreement to those of SGU. We conclude that the SGU database could be used for terrestrial background assessment, given that a linear transfer function is established.

  1. Detection of /sup 210/Pb in the lungs of smokers by in-vivo gamma spectrometry

    SciTech Connect

    Berger, C.D.; Lane, B.H.

    1982-09-01

    Since mainstream smoke is highly enriched in /sup 210/Pb, alpha radiation from inhaled cigarette smoke particles has been proposed as a cancer-producing agent in cigarette smokers. /sup 210/Po and /sup 210/Pb have been observed in tobacco, cigarette smoke and in the lungs of smokers. Since /sup 210/Pb is highly enriched in mainstream smoke, there have been estimates of yearly excesses of /sup 210/Pb in the lungs of one-pack-a-day smokers of 3 to 10 pCi (0.11 to 0.37 Bq). The ORNL Whole Body Counter was used to verify this estimate by the methodology of high-resolution, in vivo gamma spectrometry. Measurements were made on 113 adult male non-radiation workers who have either smoked at least one pack of cigarettes per day for at least five years, or have never smoked cigarettes. An analysis-of-variance table was generated based on the Pb-ratio for each individual which revealed that there was no statistically significant increase in the amount of /sup 210/Pb in the lungs of smokers over those of non-smokers. Sources of error are also discussed.

  2. Low-background gamma-ray spectrometry in the Garching underground laboratory

    NASA Astrophysics Data System (ADS)

    Hofmann, M.; Mannel, T.; Sivers, M. V.

    2013-08-01

    We describe two setups that were built for low-background gamma-ray spectrometry in the Garching Underground Laboratory (˜ 10 m.w.e.). Both setups are based on HPGe detectors surrounded by several layers of passive shielding as well as an active muon veto. The first setup (GEM) comprises a single HPGe detector surrounded by a NaI(Tl) scintillation detector that serves as anti-Compton veto. The second setup (LoAx) consists of two smaller HPGe detectors which are arranged face-to-face to cover a large solid angle around the sample. The detection efficiency of both systems is determined using a calibrated Monte-Carlo simulation. The count rate finally achieved in the energy range 40-2700keV is 10250±26cts/day for the GEM setup, and 5258±27cts/day and 6876±31cts/day between 20-1500keV for the two detectors of the LoAx setup. This leads to detection sensitivities of a few mBq/kg for U and Th at both screening stations.

  3. Particle Acceleration Inside Thunderstorms and the Variation in Source Spectra of Terrestrial Gamma-ray Flashes

    NASA Astrophysics Data System (ADS)

    Cramer, Eric; Dwyer, Joseph R.; Briggs, Michael S.; Rassoul, Hamid K.

    2016-03-01

    One of the unresolved questions in the atmospheric sciences is the origin of Terrestrial Gamma-ray Flashes (TGFs). These flashes are short but intense gamma ray bursts emanating from Earth's atmosphere. This phenomenon has been observed by gamma ray detectors on orbiting satellites, e.g. NASA Fermi, intended to study astrophysical phenomena such as Gamma-ray Bursts. TGFs are thought to originate inside thunderstorms where electrons can be accelerated and emit radiation in the multi MeV range due to bremsstrahlung interactions with air molecules. These so called ``runaway electrons'' are seeded from cosmic ray air showers hitting the Earth's atmosphere from (extra) galactic sources. In this work, we present a Monte Carlo model that simulates particle physics inside a thunderstorm region. The subsequent transport of high energy gamma rays through the Earth's atmosphere and up to satellite orbit is also included. We show that by varying both the potential difference and the ambient electric field inside the thundercloud, different electron and photon energy distributions are produced. This effect may be detectable by orbiting spacecraft, and therefore serves as a method to remote sense the electric fields that exist inside thunderstorms.

  4. SPECTRA OF COSMIC RAY ELECTRONS AND DIFFUSE GAMMA RAYS WITH THE CONSTRAINTS OF AMS-02 AND HESS DATA

    SciTech Connect

    Chen, Ding; Jin, Hong-Bo; Huang, Jing

    2015-10-01

    Recently, AMS-02 reported their results of cosmic ray (CR) observations. In addition to the AMS-02 data, we add HESS data to estimate the spectra of CR electrons and the diffuse gamma rays above TeV. In the conventional diffusion model, a global analysis is performed on the spectral features of CR electrons and the diffuse gamma rays by the GALRPOP package. The results show that the spectrum structure of the primary component of CR electrons cannot be fully reproduced by a simple power law and that the relevant break is around 100 GeV. At the 99% confidence level (C.L.) the injection indices above the break decrease from 2.54 to 2.35, but the ones below the break are only in the range of 2.746–2.751. The spectrum of CR electrons does not need to add TeV cutoff to also match the features of the HESS data. Based on the difference between the fluxes of CR electrons and their primary components, the predicted excess of CR positrons is consistent with the interpretation that these positrons originate from a pulsar or dark matter. In the analysis of the Galactic diffuse gamma rays with the indirect constraint of AMS-02 and HESS data, it is found that the fluxes of Galactic diffuse gamma rays are consistent with the GeV data of the Fermi-Large Area Telescope (LAT) in the high-latitude regions. The results indicate that inverse Compton scattering is the dominant component in the range of hundreds of GeV to tens of TeV, respectively from the high-latitude regions to the low ones, and in all of the regions of the Galaxy the flux of diffuse gamma rays is less than that of CR electrons at the energy scale of 20 TeV.

  5. Analysis of gamma-irradiated melon, pumpkin, and sunflower seeds by electron paramagnetic resonance spectroscopy and gas chromatography-mass spectrometry.

    PubMed

    Sin, Della W M; Wong, Yiu Chung; Yao, Wai Yin

    2006-09-20

    Seeds of melon (Citrullus lanatus var. sp.), pumpkin (Cucurbita moschata), and sunflower (Heliantus annus) were gamma-irradiated at 1, 3, 5, and 10 kGy and analyzed by electron paramagnetic resonance (EPR) and gas chromatography-mass spectrometry (GC-MS) according to EN1787:2000 and EN1785:2003, respectively. Distinguishable triplet signals due to the presence of induced cellulose radicals were found at 2.0010-2.0047 g in the EPR spectra. The gamma-irradiated radiolytic markers of 2-dodecylcyclobutanone (2-DCB) and 2-tetradecylcyclobutanone (2-TCB) were identified in all irradiated seed samples. Both the free radicals and the alkylcyclobutanones were found to increase with irradiation dose. In general, linear relationships between the amount of radicals and irradiation dosage could be established. Studies at an ambient temperature (20-25 degrees C) in a humidity-controlled environment showed a complete disappearance of the cellulosic peaks for irradiated samples upon 60 days of storage. Such instability behavior was considered to render the usefulness of using EPR alone in the determination of irradiated seed samples. On the other hand, 2-DCB and 2-TCB were also found to decompose rapidly (>85% loss after 120 days of storage), but the radiolytic markers remained quantifiable after 120 days of postirradiation storage. These results suggest that GC-MS is a versatile and complimentary technique for the confirmation of irradiation treatment to seeds.

  6. Effect of different thickness of material filter on Tc-99m spectra and performance parameters of gamma camera

    NASA Astrophysics Data System (ADS)

    Nazifah, A.; Norhanna, S.; Shah, S. I.; Zakaria, A.

    2014-11-01

    This study aimed to investigate the effects of material filter technique on Tc-99m spectra and performance parameters of Philip ADAC forte dual head gamma camera. Thickness of material filter was selected on the basis of percentage attenuation of various gamma ray energies by different thicknesses of zinc material. A cylindrical source tank of NEMA single photon emission computed tomography (SPECT) Triple Line Source Phantom filled with water and Tc-99m radionuclide injected was used for spectra, uniformity and sensitivity measurements. Vinyl plastic tube was used as a line source for spatial resolution. Images for uniformity were reconstructed by filtered back projection method. Butterworth filter of order 5 and cut off frequency 0.35 cycles/cm was selected. Chang's attenuation correction method was applied by selecting 0.13/cm linear attenuation coefficient. Count rate was decreased with material filter from the compton region of Tc-99m energy spectrum, also from the photopeak region. Spatial resolution was improved. However, uniformity of tomographic image was equivocal, and system volume sensitivity was reduced by material filter. Material filter improved system's spatial resolution. Therefore, the technique may be used for phantom studies to improve the image quality.

  7. Gamma-Ray Emission Spectra as a Constraint on Calculations of 234 , 236 , 238U Neutron-Capture Cross Sections

    NASA Astrophysics Data System (ADS)

    Ullmann, J. L.; Krticka, M.; Kawano, T.; Bredeweg, T. A.; Baramsai, B.; Couture, A.; Haight, R. C.; Jandel, M.; Mosby, S.; O'Donnell, J. M.; Rundberg, R. S.; Vieira, D. J.; Wilhelmy, J. B.; Becker, J. A.; Wu, C. Y.; Chyzh, A.

    2015-10-01

    Calculations of the neutron-capture cross section at low neutron energies (10 eV through 100's of keV) are very sensitive to the nuclear level density and radiative strength function. These quantities are often poorly known, especially for radioactive targets, and actual measurements of the capture cross section are usually required. An additional constraint on the calculation of the capture cross section is provided by measurements of the cascade gamma spectrum following neutron capture. Recent measurements of 234 , 236 , 238U(n, γ) emission spectra made using the DANCE 4 π BaF2 array at the Los Alamos Neutron Science Center will be presented. Calculations of gamma-ray spectra made using the DICEBOX code and of the capture cross section made using the CoH3 code will also be presented. These techniques may be also useful for calculations of more unstable nuclides. This work was performed with the support of the U.S. Department of Energy, National Nuclear Security Administration by Los Alamos National Security, LLC (Contract DE-AC52-06NA25396) and Lawrence Livermore National Security, LLC (Contract DE-AC52-07NA2734).

  8. Identification of isobaric product ions in electrospray ionization mass spectra of fentanyl using multistage mass spectrometry and deuterium labeling.

    PubMed

    Wichitnithad, Wisut; McManus, Terence J; Callery, Patrick S

    2010-09-15

    Isobaric product ions cannot be differentiated by exact mass determinations, although in some cases deuterium labeling can provide useful structural information for identifying isobaric ions. Proposed fragmentation pathways of fentanyl were investigated by electrospray ionization ion trap mass spectrometry coupled with deuterium labeling experiments and spectra of regiospecific deuterium labeled analogs. The major product ion of fentanyl under tandem mass spectrometry (MS/MS) conditions (m/z 188) was accounted for by a neutral loss of N-phenylpropanamide. 1-(2-Phenylethyl)-1,2,3,6-tetrahydropyridine (1) was proposed as the structure of the product ion. However, further fragmentation (MS(3)) of the fentanyl m/z 188 ion gave product ions that were different from the product ion in the MS/MS fragmentation of synthesized 1, suggesting that the m/z 188 product ion from fentanyl includes an isobaric structure different from the structure of 1. MS/MS fragmentation of fentanyl in deuterium oxide moved one of the isobars to 1 Da higher mass, and left the other isobar unchanged in mass. Multistage mass spectral data from deuterium-labeled proposed isobaric structures provided support for two fragmentation pathways. The results illustrate the utility of multistage mass spectrometry and deuterium labeling in structural assignment of isobaric product ions.

  9. Neanderthal skeleton from Tabun: U-series data by gamma-ray spectrometry.

    PubMed

    Schwarcz, H P; Simpson, J J; Stringer, C B

    1998-12-01

    The Neanderthal hominid Tabun C1, found in Israel by Garrod & Bate, was attributed to either layer B or C of their stratigraphic sequence. We have used gamma-ray spectrometry to determine the 230Th/234U and 231Pa/235U ratios of two bones from this skeleton, the mandible and a femur. The ages calculated from these ratios depend on the uranium uptake history of the bones. Assuming a model of early U (EU) uptake the age of the Tabun C1 mandible is 34+/-5 ka. The EU age of the femur is 19+/-2 ka. The femur may have experienced continuous (linear) U uptake which would give an age of 33+/-4 ka, in agreement with the mandible's EU age, but implies marked inhomogeneity in U uptake history at the site. These new age estimates for the skeleton suggest that it was younger than deposits of layer C. This apparent age is less than those of other Neanderthals found in Israel, and distinctly younger than the ages of the Skhul and Qafzeh burials. This suggests that Neanderthals did not necessarily coexist with the earliest modern humans in the region. All of the more complete Neanderthal fossils from Israel are now dated to the cool period of the last glacial cycle, suggesting that Neanderthals may have arrived in this region as a result of the southward expansion of their habitable range. The young age determined for the Tabun skeleton would suggest that Neanderthals survived as late in the Levant as they did in Europe.

  10. The radioactivity measurements in soils and fertilizers using gamma spectrometry technique.

    PubMed

    Boukhenfouf, Wassila; Boucenna, Ahmed

    2011-04-01

    Because of their mineral content, soils are naturally radioactive and one of the sources of radioactivity other than those of natural origin is mainly due to the extensive use of fertilizers. The main aim of this paper is to evaluate the fluxes of natural radionuclides in local production of phosphate fertilizers to determine the content of radioactivity in several commercial fertilizers produced in Algeria and to estimate their radiological impact in a cultivated soil even for the long-term exposure due to their application. For these purposes, virgin and fertilized soils were collected from outlying Setif region in Algeria and from phosphate fertilizers used in this area. Gamma spectrometry was exploited to determine activity concentration due to naturally occurring (226)Ra, (232)Th and (40)K in five types of samples (two different sorts of fertilizers, virgin and fertilized soils and well water used for irrigation) taken from Setif's areas. The results show that these radionuclides were present in an average concentration of 134.7 ± 24.1, 131.8 ± 16.7, 11644 ± 550 Bq/kg for the first fertilizer NPK and 190.3 ± 30, 117.2 ± 10.3, 5312 ± 249 Bq/kg for the second fertilizer (NPKs). For the virgin and the fertilized soils, the corresponding values were respectively 47.01 ± 7.3, 33 ± 7, 329.4 ± 19.7 Bq/kg and 53.2 ± 10.6, 50.0 ± 7, 311.4 ± 18.7 Bq/kg. For well water, the values were 1.93 and 0.12 Bq/kg; however the third value was below the Minimum Detectable Activity (MDA). The radium equivalent activity (Raeq) and the representative level index I(γr) for all samples were also calculated. The data were discussed and compared with those given in the literature.

  11. Gamma-ray spectra from low-energy positron annihilation processes in molecules

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoguang; Wang, Meishan; Zhu, Yinghao; Liu, Yang; Yang, Chuanlu; Wang, Dehua

    2016-11-01

    The theoretical γ -ray spectra from positron-electron annihilation process in a wide variety of atoms and molecules are studied. The theoretical Doppler broadened γ -ray spectra for core, inner valence, and outer valence electrons of these molecules are studied systematically. The present results show that the experimental γ -ray spectra agree well with inner valence electrons, especially the lowest occupied valence orbital electrons rather than the outer valence electrons. These inner valence electrons show a strong correlation with the corresponding available experimental measurements. These findings are interesting because the outer valence electrons have been supposed to have larger probability annihilating with positrons rather than the inner valence electrons. The present work also suggests that the accurate positron wave functions must be involved to identify the dominance of the bound electrons clearly in positron-electron annihilation process.

  12. A Compton filter to improve photopeak intensity evaluation in gamma ray spectra

    NASA Astrophysics Data System (ADS)

    da Costa, P. C. L.; Dantas, C. C.; Lira, C. A. B. O.; dos Santos, V. A.

    2004-11-01

    A procedure for filtering the photopeak intensity from the Compton continuum interference is described. A continuum energy region of up to 0.478 and the 0.662 MeV photopeak are well defined in a cesium-137 theoretical spectrum. The filter was applied to a high intensity Compton region in the gamma spectrum obtained by the attenuation measurements in laboratory experiments. A Cs-137 (γ = 0.662 MeV) source, of 4 m Ci, steel tubes and a NaI detector was utilized for measuring the catalyst density in a collimated gamma beam. Such an assembly simulates the measuring conditions for gamma tomography in the riser of a FCC-fluid catalyst cracking unit. A Canberra multichannel data acquisition, records the gamma spectrum whose data file is exported to the Matlab software. Following the spectrum reconstruction, the peak area evaluation in both systems, shows a good agreement. Based on the Fourier transform equation, a filtering method for the photopeak, using Matlab functions, was developed. By means of a lowpass filter that lets the low frequencies pass, but not the high frequencies. The filtering results in a significant reduction in the interference from the Compton effect on the photopeak. For little interference and also for a high continuum background under a nonsymmetrical photopeak the filtering works. After the filtering process the peak becomes fairly similar to a Gaussian curve and the liquid counts are enhanced. The associated standard deviation decreases by a factor of 4, while the resolution of the 0.662 MeV photopeak, is kept within detector characteristics.

  13. Comment on "Gamma-ray spectra from low-energy positron annihilation processes in molecules"

    NASA Astrophysics Data System (ADS)

    Green, D. G.; Gribakin, G. F.

    2017-03-01

    In the article by Ma et al. [Phys. Rev. A 94, 052709 (2016), 10.1103/PhysRevA.94.052709], γ -ray spectra for positron annihilation on molecules were calculated in the independent-particle approximation with the positron wave function set to unity. Based on comparisons with experimental data, they concluded that inner valence electrons play a dominant role in positron annihilation. These conclusions are incorrect and resulted from fallacious analysis that ignored the known effect of the positron wave function on the spectra.

  14. Methylation of gamma-carboxylated Glu (Gla) allows detection by liquid chromatography-mass spectrometry and the identification of Gla residues in the gamma-glutamyl carboxylase

    PubMed Central

    Hallgren, K. W.; Zhang, D.; Kinter, M.; Willard, B.; Berkner, K. L.

    2013-01-01

    Gamma-carboxylated Glu (Gla) is a post-translational modification required for the activity of vitamin K-dependent (VKD) proteins that has been difficult to study by mass spectrometry due to the properties of this negatively-charged residue. Gla is generated by a single enzyme, the gamma-glutamyl carboxylase, which has broad biological impact because VKD proteins have diverse functions that include hemostasis, apoptosis, and growth control. The carboxylase also contains Glas, of unknown function, and is an integral membrane protein with poor sequence coverage. To locate these Glas, we first established methods that resulted in high coverage (92%) of uncarboxylated carboxylase. Subsequent analysis of carboxylated carboxylase identified a Gla-peptide (729-758) and a missing region (625-647) that was detected in uncarboxylated carboxylase. We therefore developed an approach to methylate Gla, which efficiently neutralized Gla and improved mass spectrometric analysis. Methylation eliminated CO2 loss from Gla, increased the ionization of Gla-containing peptide, and appeared to facilitate trypsin digestion. Methylation of a carboxylated carboxylase tryptic digest identified Glas in the 625-647 peptide. These studies provide valuable information for testing the function of carboxylase carboxylation. The methylation approach for studying Gla by mass spectrometry is an important advance that will be broadly applicable to analyzing other VKD proteins. PMID:22536908

  15. Mapping the spatial distribution and activity of (226)Ra at legacy sites through Machine Learning interpretation of gamma-ray spectrometry data.

    PubMed

    Varley, Adam; Tyler, Andrew; Smith, Leslie; Dale, Paul; Davies, Mike

    2016-03-01

    Radium ((226)Ra) contamination derived from military, industrial, and pharmaceutical products can be found at a number of historical sites across the world posing a risk to human health. The analysis of spectral data derived using gamma-ray spectrometry can offer a powerful tool to rapidly estimate and map the activity, depth, and lateral distribution of (226)Ra contamination covering an extensive area. Subsequently, reliable risk assessments can be developed for individual sites in a fraction of the timeframe compared to traditional labour-intensive sampling techniques: for example soil coring. However, local heterogeneity of the natural background, statistical counting uncertainty, and non-linear source response are confounding problems associated with gamma-ray spectral analysis. This is particularly challenging, when attempting to deal with enhanced concentrations of a naturally occurring radionuclide such as (226)Ra. As a result, conventional surveys tend to attribute the highest activities to the largest total signal received by a detector (Gross counts): an assumption that tends to neglect higher activities at depth. To overcome these limitations, a methodology was developed making use of Monte Carlo simulations, Principal Component Analysis and Machine Learning based algorithms to derive depth and activity estimates for (226)Ra contamination. The approach was applied on spectra taken using two gamma-ray detectors (Lanthanum Bromide and Sodium Iodide), with the aim of identifying an optimised combination of detector and spectral processing routine. It was confirmed that, through a combination of Neural Networks and Lanthanum Bromide, the most accurate depth and activity estimates could be found. The advantage of the method was demonstrated by mapping depth and activity estimates at a case study site in Scotland. There the method identified significantly higher activity (<3 Bq g(-1)) occurring at depth (>0.4m), that conventional gross counting algorithms

  16. Cosmic Infrared Background From Population III Stars and Its Effect on Spectra of High-z Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Kashlinsky, A.

    2005-01-01

    We discuss the contribution of Population III stars to the near-IR (NIR) cosmic infrared background (CIB) and its effect on spectra of high-z, high-energy gamma-ray bursts (GRBs) and other sources. It is shown that if Population III is composed of massive stars, the claimed NIR CIB excess will be reproduced if only approx. 4% plus or minus 2% of all baryons went through these stars. Regardless of the precise amount of the NIR CIB due to them, they likely left enough photons to provide a large optical depth for high-energy photons from distant GRBs. Observations of such GRBs are expected following the planned launch of NASA's GLAST mission. Detecting such damping in the spectra of high-z GRBs will then provide important information on the emissions from the Population III epoch, and the location of this cutoff may serve as an indicator of the GRBs' redshifts. We also point out the difficulty of unambiguously detecting the CIB part originating from Population III in spectra of low-z blazars.

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

    NASA Astrophysics Data System (ADS)

    Jeon, Jong Ho; Nakajima, Kazuhisa; Kim, Hyung Taek; Rhee, Yong Joo; Pathak, Vishwa Bandhu; Cho, Myung Hoon; Shin, Jung Hun; Yoo, Byung Ju; Jo, Sung Ha; Shin, Kang Woo; Hojbota, Calin; Bae, Lee Jin; Jung, Jaehyung; Cho, Min Sang; Sung, Jae Hee; Lee, Seong Ku; Cho, Byoung Ick; Choi, Il Woo; Nam, Chang Hee

    2016-07-01

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

  18. Light curves and spectra from off-axis gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Salafia, O. S.; Ghisellini, G.; Pescalli, A.; Ghirlanda, G.; Nappo, F.

    2016-10-01

    If gamma-ray burst prompt emission originates at a typical radius, and if material producing the emission moves at relativistic speed, then the variability of the resulting light curve depends on the viewing angle. This is due to the fact that the pulse evolution time-scale is Doppler contracted, while the pulse separation is not. For off-axis viewing angles θview ≳ θjet + Γ-1, the pulse broadening significantly smears out the light-curve variability. This is largely independent of geometry and emission processes. To explore a specific case, we set up a simple model of a single pulse under the assumption that the pulse rise and decay are dominated by the shell curvature effect. We show that such a pulse observed off-axis is (i) broader, (ii) softer and (iii) displays a different hardness-intensity correlation with respect to the same pulse seen on-axis. For each of these effects, we provide an intuitive physical explanation. We then show how a synthetic light curve made by a superposition of pulses changes with increasing viewing angle. We find that a highly variable light curve (as seen on-axis) becomes smooth and apparently single-pulsed (when seen off-axis) because of pulse overlap. To test the relevance of this fact, we estimate the fraction of off-axis gamma-ray bursts detectable by Swift as a function of redshift, finding that a sizeable fraction (between 10 per cent and 80 per cent) of nearby (z < 0.1) bursts are observed with θview ≳ θjet + Γ-1. Based on these results, we argue that low-luminosity gamma-ray bursts are consistent with being ordinary bursts seen off-axis.

  19. The gamma-ray blazar quest: new optical spectra, state of art and future perspectives

    NASA Astrophysics Data System (ADS)

    Massaro, F.; Álvarez Crespo, N.; D'Abrusco, R.; Landoni, M.; Masetti, N.; Ricci, F.; Milisavljevic, D.; Paggi, A.; Chavushyan, V.; Jiménez-Bailón, E.; Patiño-Álvarez, V.; Strader, J.; Chomiuk, L.; La Franca, F.; Smith, Howard A.; Tosti, G.

    2016-10-01

    We recently developed a procedure to recognize γ-ray blazar candidates within the positional uncertainty regions of the unidentified/unassociated γ-ray sources (UGSs). Such procedure was based on the discovery that Fermi blazars show peculiar infrared colors. However, to confirm the real nature of the selected candidates, optical spectroscopic data are necessary. Thus, we performed an extensive archival search for spectra available in the literature in parallel with an optical spectroscopic campaign aimed to reveal and confirm the nature of the selected γ-ray blazar candidates. Here, we first search for optical spectra of a selected sample of γ-ray blazar candidates that can be potential counterparts of UGSs using the Sloan Digital Sky Survey (SDSS DR12). This search enables us to update the archival search carried out to date. We also describe the state-of-art and the future perspectives of our campaign to discover previously unknown γ-ray blazars.

  20. Extensions of the direct-semidirect model for calculating the high energy component of fast-nucleon induced gamma spectra

    SciTech Connect

    Dietrich, F S

    2000-05-22

    This section reviews extensions and variations of the direct-semidirect (DSD) model for understanding the high-energy component of gamma spectra resulting from radiative capture of fast nucleons; i.e., the part of the spectrum that is not amenable to standard statistical model (Hauser-Feshbach) treatments. We describe recent results on the extension of the DSD model to unbound final states, including comparison with proton and neutron capture data. The importance of including convective-current magnetic radiation to explain proton capture angular distributions in the 30 MeV region is shown. We conclude with a brief discussion of a model closely related to the DSD, the pure-resonance model.

  1. Gamma spectrometry efficiency calibration using Monte Carlo methods to measure radioactivity of 137Cs in food samples.

    PubMed

    Alrefae, T

    2014-12-01

    A simple method of efficiency calibration for gamma spectrometry was performed. This method, which focused on measuring the radioactivity of (137)Cs in food samples, was based on Monte Carlo simulations available in the free-of-charge toolkit GEANT4. Experimentally, the efficiency values of a high-purity germanium detector were calculated for three reference materials representing three different food items. These efficiency values were compared with their counterparts produced by a computer code that simulated experimental conditions. Interestingly, the output of the simulation code was in acceptable agreement with the experimental findings, thus validating the proposed method.

  2. (239)Pu, (240)Pu, and (241)Am determination in hot particles by low level gamma-spectrometry.

    PubMed

    Jiménez-Ramos, M C; Hurtado, S; Chamizo, E; García-Tenorio, R; León-Vintró, L; Mitchell, P I

    2010-06-01

    A nondestructive method based on low-energy, high-resolution photon spectrometry is presented which allows accurate determination of (239)Pu, (240)Pu, and (241)Am (as a daughter of (241)Pu) activities in radioactive particles containing relatively high levels of plutonium isotopes. The proposed method requires only one measurement for the establishment of an absolute efficiency curve. Since the density and composition of the radioactive particles of interest may vary, a self-absorption correction is required for the accurate determination of isotopic activities and ratios. This correction is carried out for each individual particle using the convenient gamma-ray emissions of (241)Am.

  3. Use of a Shielded High Resolution Gamma Spectrometry System to Segregate LLW from Contact Handleable ILW Containing Plutonium - 13046

    SciTech Connect

    Lester, Rosemary; Wilkins, Colin; Chard, Patrick; Jaederstroem, Henrik; LeBlanc, Paul; Mowry, Rick; MacDonald, Sanders; Gunn, William

    2013-07-01

    Dounreay Site Restoration Limited (DSRL) have a number of drums of solid waste that may contain Plutonium Contaminated Material. These are currently categorised as Contact Handleable Intermediate Level Waste (CHILW). A significant fraction of these drums potentially contain waste that is in the Low Level Waste (LLW) category. A Canberra Q2 shielded high resolution gamma spectrometry system is being used to quantify the total activity of drums that are potentially in the LLW category in order to segregate those that do contain LLW from CHILW drums and thus to minimise the total volume of waste in the higher category. Am-241 is being used as an indicator of the presence of plutonium in the waste from its strong 59.54 keV gamma-ray; a knowledge of the different waste streams from which the material originates allows a pessimistic waste 'fingerprint' to be used in order to determine an upper limit to the activities of the weak and non-gamma-emitting plutonium and associated radionuclides. This paper describes the main features of the high resolution gamma spectrometry system being used by DSRL to perform the segregation of CHILW and LLW and how it was configured and calibrated using the Canberra In-Situ Object Counting System (ISOCS). It also describes how potential LLW drums are selected for assay and how the system uses the existing waste stream fingerprint information to determine a reliable upper limit for the total activity present in each measured drum. Results from the initial on-site commissioning trials and the first measurements of waste drums using the new monitor are presented. (authors)

  4. ON THERMALIZATION IN GAMMA-RAY BURST JETS AND THE PEAK ENERGIES OF PHOTOSPHERIC SPECTRA

    SciTech Connect

    Vurm, Indrek; Piran, Tsvi; Lyubarsky, Yuri

    2013-02-20

    The low-energy spectral slopes of the prompt emission of most gamma-ray bursts (GRBs) are difficult to reconcile with radiatively efficient optically thin emission models irrespective of the radiation mechanism. An alternative is to ascribe the radiation around the spectral peak to a thermalization process occurring well inside the Thomson photosphere. This quasi-thermal spectrum can evolve into the observed non-thermal shape by additional energy release at moderate to small Thomson optical depths, which can readily give rise to the hard spectral tail. The position of the spectral peak is determined by the temperature and Lorentz factor of the flow in the thermalization zone, where the total number of photons carried by the jet is established. To reach thermalization, dissipation alone is not sufficient and photon generation requires an efficient emission/absorption process in addition to scattering. We perform a systematic study of all relevant photon production mechanisms searching for possible conditions in which thermalization can take place. We find that a significant fraction of the available energy should be dissipated at intermediate radii, {approx}10{sup 10} to a few Multiplication-Sign 10{sup 11} cm, and the flow there should be relatively slow: the bulk Lorentz factor could not exceed a few tens for all but the most luminous bursts with the highest E {sub pk} values. The least restrictive constraint for successful thermalization, {Gamma} {approx}< 20, is obtained if synchrotron emission acts as the photon source. This requires, however, a non-thermal acceleration deep below the Thomson photosphere transferring a significant fraction of the flow energy to relativistic electrons with Lorentz factors between 10 and 100. Other processes require bulk flow Lorentz factors of order of a few for typical bursts. We examine the implications of these results to different GRB photospheric emission models.

  5. Searching for narrow absorption and emission lines in XMM-Newton spectra of gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Campana, S.; Braito, V.; D'Avanzo, P.; Ghirlanda, G.; Melandri, A.; Pescalli, A.; Salafia, O. S.; Salvaterra, R.; Tagliaferri, G.; Vergani, S. D.

    2016-08-01

    We present the results of a spectroscopic search for narrow emission and absorption features in the X-ray spectra of long gamma-ray burst (GRB) afterglows. Using XMM-Newton data, both EPIC and RGS spectra, of six bright (fluence > 10-7 erg cm-2) and relatively nearby (z = 0.54-1.41) GRBs, we performed a blind search for emission or absorption lines that could be related to a high cloud density or metal-rich gas in the environ close to the GRBs. We detected five emission features in four of the six GRBs with an overall statistical significance, assessed through Monte Carlo simulations, of ≲ 3.0σ. Most of the lines are detected around the observed energy of the oxygen edge at ~ 0.5 keV, suggesting that they are not related to the GRB environment but are most likely of Galactic origin. No significant absorption features were detected. A spectral fitting with a free Galactic column density (NH) testing different models for the Galactic absorption confirms this origin because we found an indication of an excess of Galactic NH in these four GRBs with respect to the tabulated values.

  6. Analysis of gamma-ray spectra from foils activated in a range-thick lead target by 800-MeV protons. Final technical report

    SciTech Connect

    Laird, C.E.; Mullins, D.H.

    1995-06-12

    Approximately 400 gamma-ray spectra have been analyzed to obtain the types and quantities of radioisotopes produced when 800-MeV protons interact with a range-thick lead target. These spectra were obtained from the radioactive decay of product isotopes in lead disks placed at various depths and radial positions within the target. These spectra were analyzed with the computer code HYPERMET and the photopeak areas were reduced to nuclei produced per incident proton per cubic centimeter of material. Product nuclei ranged from atomic mass 160 to mass 206 and over a range of half lives from a few minutes to several weeks. The results of this analysis have been outlined in this report and transmitted on computer disk to Los Alamos National Laboratory. The consistency of these analyses have been confirmed by a comparison of photopeak areas obtained at LANL with the computer code GAMANAL with those from HYPERMET for two gamma-ray spectra. Also, the nuclear production per proton per cm{sub 3} obtained from these two spectra analyzed both at LANL and at EKU have been found to agree to within the statistical accuracy of the peak-fitting programs. This analysis of these 400 gamma-ray spectra has determined the nuclear production per incident proton per cm{sub 3} at five regularly-spaced radial positions and depths up to 40 cm into a range-thick lead target.

  7. 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

  8. Production altitude and time delays of the terrestrial gamma flashes: Revisiting the Burst and Transient Source Experiment spectra

    NASA Astrophysics Data System (ADS)

    Østgaard, N.; Gjesteland, T.; Stadsnes, J.; Connell, P. H.; Carlson, B.

    2008-02-01

    On the basis of the RHESSI results it has been suggested that terrestrial gamma flashes (TGFs) are produced at very low altitudes. On the other hand some of the Burst and Transient Source Experiment (BATSE) spectra show unabsorbed fluxes of X rays in the 25-50 keV energy range, indicating a higher production altitude. To investigate this, we have developed a Monte Carlo code for X-ray propagation through the atmosphere. The most important features seen in the modeled spectra are (1) a low-energy cutoff which moves to lower energies as TGFs are produced at higher altitudes, (2) a high-energy cutoff which moves to lower energies as TGFs are observed at larger zenith angles, and (3) time delays are observed for TGFs produced at <=20 km (and some at 30 km) altitude when observed at larger zenith angle than the half-angle defining the initial isotropic X-ray beam. This is a pure Compton effect. The model results and an optimization procedure are used to estimate production altitudes of the BATSE TGFs. The main findings are (1) half or more of the BATSE TGFs are produced at low altitudes, <=20 km, (2) a significant portion of the BATSE TGFs are produced at higher altitudes, 30 km to 40 km, (3) for the TGFs produced at <=20 km (and some at 30 km) altitudes the dispersion signatures can be explained as a pure Compton effect, and (4) the softening of the BATSE spectra for increasing zenith angles and the time dispersions both indicate that the initial TGF distribution is beamed.

  9. Dating of sediments from four Swiss prealpine lakes with (210)Pb determined by gamma-spectrometry: progress and problems.

    PubMed

    Putyrskaya, V; Klemt, E; Röllin, S; Astner, M; Sahli, H

    2015-07-01

    In this paper the most important problems in dating lake sediments with unsupported (210)Pb are summarized and the progress in gamma-spectrometry of the unsupported (210)Pb is discussed. The main topics of these studies concern sediment samples preparation for gamma-spectrometry, measurement techniques and data analysis, as well as understanding of accumulation and sedimentation processes in lakes. The vertical distributions of artificial ((137)Cs, (241)Am, (239)Pu) and natural radionuclides ((40)K, (210,214)Pb, (214)Bi) as well as stable trace elements (Fe, Mn, Pb) in sediment cores from four Swiss lakes were used as examples for the interpretation, inter-comparison and validation of depth-age relations established by three (210)Pb-based models (CF-CSR, CRS and SIT). The identification of turbidite layers and the influence of the turbidity flows on the accuracy of sediment dating is demonstrated. Time-dependent mass sedimentation rates in lakes Brienz, Thun, Biel and Lucerne are discussed and compared with published data.

  10. Thermospray liquid-chromatography mass spectrometry of thiol radioprotective agents: Characteristics spectra. Scientific report

    SciTech Connect

    Walden, T.L.; Buchner, J.; Pizzitola, V.; Blakeley, W.F.

    1988-01-01

    Ethiofos (S-2(3-aminopropylamino)ethylphosphorothioic acid or WR-2721) is currently being evaluated in clinical radiotherapy trials (Kligerman et al., 1980) because of its potential for enhancing the efficacy of radiotherapy (Kligerman et al., 1980; Yuhas and Storer, 1969). For proper drug usage and pharmacological studies, it is necessary to assess the stability of the aminothiol and the presence of impurities or decomposition products. In addition, monitoring the plasma levels of WR-2721 and its metabolites should improve the therapeutic usefulness of WR-2721. Several high-performance liquid chromatography (HPLC) methodologies have been developed that are applicable for routine analysis of aminothiols and endogeneous cellular thiols (Newton et al., 1981; Swynnerton et al., 1984). One of these methodologies, electrochemical detection, permits the simultaneous detection of the free thiol and the disulfides (Swynnerton et al. 1984). Mass spectrometry (MS) is a sensitive technique that can confirm purity and provide useful structural information. Using a thermospray interface, samples can be introduced into the mass spectrometer from a liquid chromatograph (LC) (Vestal, 1984). The interface thermally nebulizes the eluant into a high-pressure region of the mass spectrometer where a variety of soft-ionization techniques may be used to ionize the analyte molecules. The feasibility of LC coupled to MS-detection was studied for the analysis of thiol-containing radioprotective agents, including glutathione, WR-2721, and WR-1065, the dephosphorylated sulfhydryl form of WR-2721, which has been shown to be its active radioprotective metabolite (Calabro-Jones et al., 1983).

  11. Data quality objectives for surface-soil cleanup operation using in situ gamma spectrometry for concentration measurements.

    PubMed

    Fong, S H; Alvarez, J L

    1997-02-01

    In situ gamma spectrometry is an efficient method for monitoring the progress of cleanup activities for radioactive contaminants in surface soil and for evaluating the attainment of cleanup standards. However, desired data precision and accuracy must be specified for such a detection system prior to the operation to ensure that the level of uncertainty associated with the concentration measurements is acceptable. A method for developing data quality objectives is described in this paper for in situ gamma spectrometry to achieve numerical goals for data precision and accuracy for cleanup operations. Concentration measurement for a radionuclide at its cleanup level must have a precision commensurate with the importance of cleanup decisions. The 95% lower limit of detection of the system is suggested to be about one tenth the expected system response at the cleanup level. The count time required to achieve the preferred 95% lower limit of detection, and hence the desired precision, can then be determined. The accuracy error arises from the overall calibration factor, which relates the detector responses (e.g., count rate) to physical quantities of interest (e.g., radionuclide soil concentration). The major source of error for the calibration factor using in situ gamma spectrometry is the misidentification of the type of the depth profile of radionuclide concentration in soil. If surrogate radionuclides are used, such as 241Am for plutonium, the variation in the concentration ratio would be another significant source of error. Soil sampling programs performed prior to a cleanup operation will greatly reduce the accuracy error for an in situ detection system, and the analysis of system errors may determine the degree of sampling required. The planning of such a program is discussed in the study. Uncertainty analysis using a Latin Hypercube sampling technique for the calibration factor is also demonstrated. The quantitative result of the uncertainty analysis is useful

  12. A method for the comparison of performance of gamma-ray spectrometry calibration cocktails.

    PubMed

    Legarda, F; Los Arcos, J M; Herranz, M

    2004-01-01

    In order to make quantitative assessments about the usefulness of different gamma-ray emitting radionuclide cocktails to carry out efficiency calibrations of gamma-ray spectrometers, a method has been developed that allows the comparison of their different performances and to optimize the choice of gamma energy lines for the radionuclides within a specific cocktail. The method has been applied to compare different cocktail configurations obtained from measurements made in the laboratory with monoenergetic radionuclides, and their relative performances are presented and discussed.

  13. Gamma-Ray Emission Spectra as a Constraint on Calculations of 234,236,238U Neutron-Capture Cross Sections

    SciTech Connect

    Ullmann, John Leonard; Kawano, Toshihiko; Bredeweg, Todd Allen; Baramsai, Bayarbadrakh; Couture, Aaron Joseph; Haight, Robert Cameron; Jandel, Marian; Mosby, Shea Morgan; O'Donnell, John M.; Rundberg, Robert S.; Vieira, David J.; Wilhelmy, Jerry B.; Becker, John A.; Wu, Ching-Yen; Krticka, Milan

    2015-05-28

    Neutron capture cross sections in the “continuum” region (>≈1 keV) and gamma-emission spectra are of importance to basic science and many applied fields. Careful measurements have been made on most common stable nuclides, but physicists must rely on calculations (or “surrogate” reactions) for rare or unstable nuclides. Calculations must be benchmarked against measurements (cross sections, gamma-ray spectra, and <Γγ>). Gamma-ray spectrum measurements from resolved resonances were made with 1 - 2 mg/cm2 thick targets; cross sections at >1 keV were measured using thicker targets. The results show that the shape of capture cross section vs neutron energy is not sensitive to the form of the strength function (although the magnitude is); the generalized Lorentzian E1 strength function is not sufficient to describe the shape of observed gamma-ray spectra; MGLO + “Oslo M1” parameters produces quantitative agreement with the measured 238U(n,γ) cross section; additional strength at low energies (~ 3 MeV) -- likely M1-- is required; and careful study of complementary results on low-lying giant resonance strength is needed to consistently describe observations.

  14. Portable microcomputer for the analysis of plutonium gamma-ray spectra. Volume II. Software description and listings. [IAEAPU

    SciTech Connect

    Ruhter, W.D.

    1984-05-01

    A portable microcomputer has been developed and programmed for the International Atomic Energy Agency (IAEA) to perform in-field analysis of plutonium gamma-ray spectra. The unit includes a 16-bit LSI-11/2 microprocessor, 32-K words of memory, a 20-character display for user prompting, a numeric keyboard for user responses, and a 20-character thermal printer for hard-copy output of results. The unit weights 11 kg and has dimensions of 33.5 x 30.5 x 23.0 cm. This compactness allows the unit to be stored under an airline seat. Only the positions of the 148-keV /sup 241/Pu and 208-keV /sup 237/U peaks are required for spectral analysis that gives plutonium isotopic ratios and weight percent abundances. Volume I of this report provides a detailed description of the data analysis methodology, operation instructions, hardware, and maintenance and troubleshooting. Volume II describes the software and provides software listings.

  15. Mathematical model of gamma-ray spectrometry borehole logging for quantitative analysis

    USGS Publications Warehouse

    Schimschal, Ulrich

    1981-01-01

    A technique for analyzing gamma-ray spectral-logging data has been developed, in which a digital computer is used to calculate the effects of gamma-ray attentuation in a borehole environment. The computer model allows for the calculation of the effects of lithology, porosity, density, and the thickness of a horizontal layer of uniformly distributed radioactive material surrounding a centralized probe in a cylindrical borehole. The computer program also contains parameters for the calculation of the effects of well casing, drilling fluid, probe housing, and losses through the sodium-iodide crystal. Errors associated with the commonly used mathematical assumption of a point detector are eliminated in this model. (USGS)

  16. Low-background gamma-ray spectrometry for the international monitoring system

    DOE PAGES

    Greenwood, L. R.; Cantaloub, M. G.; Burnett, J. L.; ...

    2016-12-28

    PNNL has developed two low-background gamma-ray spectrometers in a new shallow underground laboratory, thereby significantly improving its ability to detect low levels of gamma-ray emitting fission or activation products in airborne particulate in samples from the IMS (International Monitoring System). Furthermore, the combination of cosmic veto panels, dry nitrogen gas to reduce radon and low background shielding results in a reduction of the background count rate by about a factor of 100 compared to detectors operating above ground at our laboratory.

  17. Low-background gamma-ray spectrometry for the international monitoring system.

    PubMed

    Greenwood, L R; Cantaloub, M G; Burnett, J L; Myers, A W; Overman, C T; Forrester, J B; Glasgow, B G; Miley, H S

    2016-12-28

    PNNL has developed two low-background gamma-ray spectrometers in a new shallow underground laboratory, thereby significantly improving its ability to detect low levels of gamma-ray emitting fission or activation products in airborne particulate in samples from the IMS (International Monitoring System). The combination of cosmic veto panels, dry nitrogen gas to reduce radon and low background shielding results in a reduction of the background count rate by about a factor of 100 compared to detectors operating above ground at our laboratory.

  18. 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.

  19. Spatially-Dependent Measurements of Surface and Near-Surface Radioactive Material Using In situ Gamma Ray Spectrometry (ISGRS) For Final Status Surveys

    SciTech Connect

    J. A. Chapman, A. J. Boerner, E. W. Abelquist

    2006-11-15

    In-situ, high-resolution gamma-ray spectrometry (ISGRS) measurements were conducted at the Oak Ridge Institute for Science and Education (ORISE) field laboratory in Oak Ridge, Tennessee. The purpose of these tests was to provide analytical data for assessing how “fit for use” this technology is for detecting discrete particles in soil.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  1. Radiological Mapping of the Alkaline Intrusive Complex of Jombo, South Coastal Kenya by In-Situ Gamma-Ray Spectrometry

    NASA Astrophysics Data System (ADS)

    Kaniu, Ian; Darby, Iain G.; Kalambuka Angeyo, Hudson

    2016-04-01

    Carbonatites and alkaline intrusive complexes are rich in a variety of mineral deposits such as rare earth elements (REEs), including Nb, Zr and Mn. These are often associated with U and Th bearing minerals, including monazite, samarskite and pyrochlore. Mining waste resulting from mineral processing activities can be highly radioactive and therefore poses a risk to human health and environment. The Jombo complex located in Kenya's south coastal region is potentially one of the richest sources of Nb and REEs in the world. It consists of the main intrusion at Jombo hill, three associated satellite intrusions at Mrima, Kiruku and Nguluku hills, and several dykes. The complex is highly heterogeneous with regard to its geological formation as it is characterized by alkaline igneous rocks and carbonatites which also influence its radio-ecological dynamics. In-situ gamma spectrometry offers a low-cost, rapid and spatially representative radioactivity estimate across a range of landscapes compared to conventional radiometric techniques. In this work, a wide ranging radiological survey was conducted in the Jombo complex as follow up on previous studies[1,2], to determine radiation exposure levels and source distributions, and perform radiological risk assessments. The in-situ measurements were carried out using a 2.0 l NaI(Tl) PGIS-2 portable detector from Pico Envirotec Inc integrated with GPS, deployed for ground (back-pack) and vehicular gamma-ray spectrometry. Preliminary results of radiological distribution and mapping will be presented. [1] Patel, J. P. (1991). Discovery and Innovation, 3(3): 31-35. [2] Kebwaro, J. M. et. al. (2011). J. Phys. Sci., 6(13): 3105-3110.

  2. In-situ ground gamma spectrometry — an effective tool for geological mapping (the Male Karpaty Mts., Slovakia)

    NASA Astrophysics Data System (ADS)

    Mojzeš, Andrej; Porubčanová, Barbara

    2016-06-01

    This contribution presents the results of profile in-situ gamma spectrometry measurements that sought to determine the content of natural radionuclides 40K, 238U and 232Th in a near surface horizon of rocks, their weathering cover and soils in the area of the Malé Karpaty Mts. It is widely established that the exploration of radioactivity of bedrocks and cover rocks can be a very effective and useful tool for both geological mapping, for identifying deposits of mineral resources, and even addressing the issues of structural and tectonic geology. This assertion is equally confirmed by the ground gamma spectrometry measurements carried out as part of this case study on larger scales, seeking more detailed geological structure solutions. The results obtained provide a welcome addition to an already existing database, which monitors the content of naturally occurring radionuclides individually for every rock lithotype of the Western Carpathians, by elaborating on the data collected by previous research and by updating this database for any future needs. The presented results confirmed the low to medium radioactivity levels of rocks and soils in the studied area. The highest values were detected in granitoids and metamorfic phyllitic rocks of the Malé Karpaty Mts. core; the lowest values were detected in carbonates, arenaceous sediments and, above all, amphibolite bodies. In this way, the presented results of the interpreted profile (P5) confirm the model of local geological structure as represented on the most up-to-date edition of the geological map of the Male Karpaty Mts. (Polak et al. 2011).

  3. The Application of High-Resolution Gamma-Ray Spectrometry (HRGS) to Nuclear Safeguards, Nonproliferation, and Arms Control Activities

    SciTech Connect

    Kane, Walter R.; Lemley, James R.; Forman, Leon

    1997-12-31

    While well-developed methodologies exist for the employment of high- resolution gamma ray spectrometry (HRGS) in determining the isotopic composition of plutonium samples, the potential capabilities of such measurements in determining the properties of nuclear materials otherwise remain largely unexploited. These measurements contain information sufficiently detailed such that not only can the isotopic composition of uranium and plutonium materials be determined, but the details of the spectrum obtained will depend reproducibly upon other factors including the total mass, density, chemical composition, and geometrical configuration of the material, and for certain materials, the elapsed time since chemical processing. The potential thus exists to obtain a `gamma-ray fingerprint` for typical containers or assemblies of nuclear material which will then serve to identify that class of item in a later confirmatory measurement. These measurements have the additional advantage that, by comparison with active interrogation techniques which usually require the introduction of some extraneous form of radiation or other intrusive activity, they are totally passive, and thus impose only minimal additional safety or regulatory burdens on the operators. In the application of these measurements to the verification of treaty-limited items, where the information acquired may be sensitive in nature, the use of the CIVET (Controlled Intrusiveness Verification Technique) approach, where a computer-based interface is employed to limit access to the information obtained, may be followed.

  4. Gamma spectrometry and chemical characterization of ceramic seeds with samarium-153 and holmium-166 for brachytherapy proposal.

    PubMed

    Valente, Eduardo S; Campos, Tarcísio P R

    2010-12-01

    Ceramic seeds were synthesized by the sol-gel technique with Si:Sm:Ca and Si:Ho:Ca. One set of seeds was irradiated in the TRIGA type nuclear reactor IPR-R1 and submitted to instrumental neutron activation analysis (INAA), K(0) method, to determine mass percentage concentration of natural samarium and holmium in the seed as well as to determine all existing radionuclides and their activities. Attention was paid to discrimination of Si-31, Ca-40, Ca-45, Ca-47, Ca-49, Sm-145, Sm-155, Sm-153 and Ho-166. A second sample was submitted to atomic emission spectrometry (ICP-AES) also to determine samarium and holmium concentrations in weight. A third sample was submitted to X-ray fluorescence spectrometry to qualitatively determine chemical composition. The measured activity was due to Sm-153 and Ho-166 with a well-characterized gamma spectrum. The X-ray fluorescence spectrum demonstrated that there is no discrepancy in seed composition. The maximum ranges in the water of beta particles from Sm-153 and Ho-166 decay were evaluated, as well as the dose rate and total dose delivered within the volume delimited by the range of the beta particles. The results are relevant for investigation of the viability of producing Sm-153 and Ho-166 radioactive seeds for use in brachytherapy.

  5. Measurement of gamma radiation levels in soil samples from Thanjavur using γ-ray spectrometry and estimation of population exposure

    PubMed Central

    Senthilkumar, B.; Dhavamani, V.; Ramkumar, S.; Philominathan, P.

    2010-01-01

    This study assesses the level of terrestrial gamma radiation and associated dose rates from the naturally occurring radionuclides 232Th, 238U and 40K in 10 soil samples collected from Thanjavur (Tamil Nadu, India) using γ-ray spectrometry. The activity profile of radionuclides has clearly showed the existence of low level activity in Thanjavur. The geometric mean activity concentrations of 232Th, 238U and 40K is 42.9±9.4 Bq.kg−1, 14.7±1.7 Bq.kg−1 and 149.5±3.1 Bq.kg−1 respectively are derived from all the soil samples studied. The activity concentration of 232Th, 238U and 40K in soil is due to the presence of metamorphic rocks like shale, hornblende-biotite gneiss and quartzofeldspathic gneiss in these areas. Gamma absorbed dose rates in air outdoors were calculated to be in the range between 32 nGy.h−1 and 59.1 nGy.h−1 with an arithmetic mean of 43.3 ±9 nGy.h−1. This value is lesser than the population weighted world-averaged of 60 nGy.h−1. Inhabitants of Thanjavur are subjected to external gamma radiation exposure (effective dose) ranging between 39.2 and 72.6 μSv.y−1 with an arithmetic mean of 53.1±11 μSv.y−1. The values of the external hazard index determined from the soil radioactivity of the study area are less than the recommended safe levels. PMID:20177570

  6. Characterisation of imperial college reactor centre legacy waste using gamma-ray spectrometry

    SciTech Connect

    Shuhaimi, Alif Imran Mohd

    2016-01-22

    Waste characterisation is a principal component in waste management strategy. The characterisation includes identification of chemical, physical and radiochemical parameters of radioactive waste. Failure to determine specific waste properties may result in sentencing waste packages which are not compliant with the regulation of long term storage or disposal. This project involved measurement of intensity and energy of gamma photons which may be emitted by radioactive waste generated during decommissioning of Imperial College Reactor Centre (ICRC). The measurement will use High Purity Germanium (HPGe) as Gamma-ray detector and ISOTOPIC-32 V4.1 as analyser. In order to ensure the measurements provide reliable results, two quality control (QC) measurements using difference matrices have been conducted. The results from QC measurements were used to determine the accuracy of the ISOTOPIC software.

  7. Characterisation of imperial college reactor centre legacy waste using gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Shuhaimi, Alif Imran Mohd

    2016-01-01

    Waste characterisation is a principal component in waste management strategy. The characterisation includes identification of chemical, physical and radiochemical parameters of radioactive waste. Failure to determine specific waste properties may result in sentencing waste packages which are not compliant with the regulation of long term storage or disposal. This project involved measurement of intensity and energy of gamma photons which may be emitted by radioactive waste generated during decommissioning of Imperial College Reactor Centre (ICRC). The measurement will use High Purity Germanium (HPGe) as Gamma-ray detector and ISOTOPIC-32 V4.1 as analyser. In order to ensure the measurements provide reliable results, two quality control (QC) measurements using difference matrices have been conducted. The results from QC measurements were used to determine the accuracy of the ISOTOPIC software.

  8. Gamma ray spectrometry logs as a hydrocarbon indicator for clastic reservoir rocks in Egypt.

    PubMed

    Al-Alfy, I M; Nabih, M A; Eysa, E A

    2013-03-01

    Petroleum oil is an important source for the energy in the world. The Gulf of Suez, Nile Delta and South Valley are important regions for studying hydrocarbon potential in Egypt. A thorium normalization technique was applied on the sandstone reservoirs in the three regions to determine the hydrocarbon potentialities zones using the three spectrometric radioactive gamma ray-logs (eU, eTh and K% logs). The conventional well logs (gamma-ray, deep resistivity, shallow resistivity, neutron, density and sonic logs) are analyzed to determine the net pay zones in these wells. Indices derived from thorium normalized spectral logs indicate the hydrocarbon zones in petroleum reservoirs. The results of this technique in the three regions (Gulf of Suez, Nile Delta and South Valley) are in agreement with the results of the conventional well log analyses by ratios of 82%, 78% and 71% respectively.

  9. Using gamma spectrometry indicators to detect and quantify fission products changes in irradiated fuel

    SciTech Connect

    Loubet, L.; Martella, Th.

    2015-07-01

    A new analysis method based on gamma scanning of fission products on irradiated rods is presented. Indicators calculated from this method can be used for the qualitative treatment and comparison of irradiated rods from PWR, SFR or and MTR. Differences in the behavior of fission products (FP) can thus be quantified. Phenomena such as migration or geometrical changes in pellets should thus benefit from these accurate, yet quickly and easily achievable results. (authors)

  10. Ultraviolet and infrared absorption spectra of Cr2O3 doped-sodium metaphosphate, lead metaphosphate and zinc metaphosphate glasses and effects of gamma irradiation: a comparative study.

    PubMed

    Marzouk, M A; ElBatal, F H; Abdelghany, A M

    2013-10-01

    The effects of gamma irradiation on spectral properties of Cr2O3-doped phosphate glasses of three varieties, namely sodium metaphosphate, lead metaphosphate and zinc metaphosphate have been investigated. Optical spectra of the undoped samples reveal strong UV absorption bands which are attributed to the presence of trace iron impurities in both the sodium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV near visible bands due to combined absorption of both trace iron impurities and divalent lead ions. The effect of chromium oxide content has been investigated. The three different Cr2O3-doped phosphate glasses reveal spectral visible bands varying in their position and intensity and splitting due to the different field strengths of the Na(+), Pb(2+), Zn(2+) cations, together with the way they are housed in the network and their effects on the polarisability of neighboring oxygens ligands. The effects of gamma irradiation on the optical spectral properties of the various glasses have been compared. The different effects for lead and zinc phosphate are related to the ability of Pb(2+), and Zn(2+) to form additional structural units causing stability of the network towards gamma irradiation. Also, the introduction of the transition metal chromium ions reveals some shielding behavior towards irradiation. Infrared absorption spectra of the three different base phosphate glasses show characteristic vibrations due to various phosphate groups depending on the type of glass and Cr2O3 is observed to slightly affect the IR spectra. Gamma irradiation causes minor variations in some of the intensities of the IR spectra but the main characteristic bands due to phosphate groups remain in their number and position.

  11. Using Gamma-Ray and Neutron Emission to Determine Solar Flare Accelerated Particle Spectra and Composition and the Conditions Within the Flare Magnetic Loop

    DTIC Science & Technology

    2007-01-01

    computer codes we have cal- culated the yields of deexcitation lines, escaping neutron spec- tra and the neutron capture line for monoenergetic ...USING GAMMA-RAYAND NEUTRON EMISSION TO DETERMINE SOLAR FLARE ACCELERATED PARTICLE SPECTRA AND COMPOSITION AND THE CONDITIONS WITHIN THE FLARE...California, San Diego, La Jolla, CA Received 2006 May 4; accepted 2006 August 23 ABSTRACT The measurable quantities associated with -ray and neutron

  12. Simultaneous measurements of indoor radon, radon-thoron progeny and high-resolution gamma spectrometry in Greek dwellings.

    PubMed

    Clouvas, A; Xanthos, S; Antonopoulos-Domis, M

    2006-01-01

    Simultaneous indoor radon, radon-thoron progeny and high-resolution in situ gamma spectrometry measurements, with portable high-purity Ge detector were performed in 26 dwellings of Thessaloniki, the second largest town of Greece, during March 2003-January 2005. The radon gas was measured with an AlphaGUARD ionisation chamber (in each of the 26 dwellings) every 10 min, for a time period between 7 and 10 d. Most of the values of radon gas concentration are between 20 and 30 Bq m(-3), with an arithmetic mean of 34 Bq m(-3). The maximum measured value of radon gas concentration is 516 Bq m(-3). The comparison between the radon gas measurements, performed with AlphaGUARD and short-term electret ionisation chamber, shows very good agreement, taking into account the relative short time period of the measurement and the relative low radon gas concentration. Radon and thoron progeny were measured with a SILENA (model 4s) instrument. From the radon and radon progeny measurements, the equilibrium factor F could be deduced. Most of the measurements of the equilibrium factor are within the range 0.4-0.5. The mean value of the equilibrium factor F is 0.49 +/- 0.10, i.e. close to the typical value of 0.4 adopted by UNSCEAR. The mean equilibrium equivalent thoron concentration measured in the 26 dwellings is EEC(thoron) = 1.38 +/- 0.79 Bq m(-3). The mean equilibrium equivalent thoron to radon ratio concentration, measured in the 26 dwellings, is 0.1 +/- 0.06. The mean total absorbed dose rate in air, owing to gamma radiation, is 58 +/- 12 nGy h(-1). The contribution of the different radionuclides to the total indoor gamma dose rate in air is 38% due to 40K, 36% due to thorium series and 26% due to uranium series. The annual effective dose, due to the different source terms (radon, thoron and external gamma radiation), is 1.05, 0.39 and 0.28 mSv, respectively.

  13. The use of mercury as a supplementary inner shielding material for low-background gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Al-Sharkawy, A.; Sharshar, T.; Badran, H. M.

    2013-07-01

    Gamma-ray spectroscopic measurements of low-level environmental samples require the reduction of the background as low as practicable. In the present work, we investigate the advantages of adding Hg passive shielding inside a low-background Pb-shield to further reduce the background radiation. The background count rate achieved by the Pb-shield alone over the energy interval from 25 to 2700 keV, amounts to 8.4 × 10-4 counts/s.keV which is ~ 1.5% of the normal background. The introduction of Hg-shield adds another 15% reduction. On the average, the Hg-shield suppresses the net peak areas of X- and gamma-rays to < 3 and 1% of the normal background, respectively. On the other hand, the reduction in the count rate of these peaks due to the addition of Hg-shield varies according to the energy. The measurements showed no evidence of the presence of cosmogenically produced 194Hg in the measured spectra. An additional 2% reduction was achieved by using neutron moderators.

  14. In situ subterranean determination of actinides by high-resolution gamma-ray spectrometry

    SciTech Connect

    Brodzinski, R. L.

    1981-04-01

    A system utilizing high resolution germanium diode gamma-ray spectroscopy for the simple, safe, and economical in situ determination of actinides is described. Six isotopes, /sup 235/U, /sup 238/U, /sup 237/Np, /sup 239/Pu, /sup 241/Pu, and /sup 241/Am, can be simultaneously measured at the 10 nCi g/sup -1/ level in less than 7 minutes. Collimators provide for measurement of horizontal strata as thin as 1 cm or solid angles as small as 0.1 steradians. Information obtainable with the system is discussed and compared to that obtainable with neutron activation/detection systems.

  15. Statistical data evaluation in mobile gamma spectrometry: an optimization of on-line search strategies in the scenario of lost point sources.

    PubMed

    Hjerpe, T; Finck, R R; Samuelsson, C

    2001-06-01

    There is a potential risk that hazardous radioactive sources could enter the environment, e.g., via satellite debris, smuggled radioactive goods, or lost metal scrap. From a radiation protection point of view there is a need for rapid and reliable methods for locating and identifying sources. The methods could also be used to locate hot spots after radioactive fallout. Carborne and airborne gamma spectrometry systems are suitable for the task. This work focuses on a situation where the radionuclide to search for is known, which is not an unlikely scenario. The possibility that the source is located near a road can be high, and thus motivating a carborne spectrometer system. The main object is to optimize on-line statistical methods in order to achieve a high probability for locating the point source and still have reasonably few false alarms caused by variations in the natural background radiation. Data were obtained from a carborne 3-L NaI(Tl) detector and two point sources located at various distances from the road. The nuclides used were 137Cs and 131I. Spectra were measured stationary on the road. From these measurements we have reconstructed counts in spectral windows applicable to different speed and sampling times; the time 3 s and speeds 32 and 54 km h(-1) are used in this work. The maximum distance a source can be located from the road and still be detected is estimated with four different statistical analysis methods. This distance is called the critical distance, CD. The method is applied on gross counts in the full energy peak spectral window. For each method alarm levels have been calculated from background data obtained in Scania (Skåne), in the south of Sweden. The results show large differences in CD. With the best approach, the two sources could be detected from about 180 m (137Cs, 6 GBq) and 170 m (131I, 4.5 GBq).

  16. Modern aerial gamma-ray spectrometry and regional potassium map of the conterminous United States

    USGS Publications Warehouse

    Duval, Joseph S.

    1990-01-01

    The aerial gamma-ray data were obtained as part of the National Uranium Resource Evaluation (NURE) Program sponsored by the U.S. Department of Energy during the period 1975-1983. References for the Open-File Reports that describe the surveys and data collection can be found in Bendix Field Engineering Corp. (1983). The aerial surveys were flown by contractors using fixed-wing and helicopter systems with 33-50 L (liters) of thallium-activated sodium iodide (NaI (TI)) crystals. The nominal survey altitude used is 122 m. The survey lines were generally east-west with line spacings of 1.6-10 km. Tie lines were flown perpendicular to the flight lines at intervals of 16- 30 km. The data were corrected for background from aircraft contamination and cosmic rays, altitude variations, airborne 214Bi, and Compton scattering. The gamma-ray systems were calibrated using the calibrations pads at Grand Junction, Colorado (Ward, 1978 ) and the dynamic test strip at Lake Mead, Arizona (Geodata International, Inc., 1977).  

  17. Ultra low-level gamma ray spectrometry of thorium in human bone samples.

    PubMed

    Martínez Canet, M J; Hult, M; Johnston, P N; Lambrichts, I

    2001-01-01

    Following the use of in vivo measurements of 210Pb to estimate retrospectively radon exposure, interest has been expressed in the use of in vivo measurements of 208Tl to estimate thorium intake. To aid with calibration and to determine the optimum part of the body on which in vivo measurements should be made, the distribution of 208Tl and 228Ac amongst different human bones was measured in the underground laboratory HADES. The 208Tl activity was determined by the 2614.5 keV and the 583.2 keV gamma ray lines. The 225Ac activity was determined by the 911.2 keV and the 969.0 keV gamma ray lines. The background under those peaks when measured on the 106% relative efficiency coaxial HPGe detector in HADES is of the order of 1 d(-1), resulting in detection limits in the order of 1 mBq for both radionuclides for a typical 10 g bone sample and for a measuring time of I week.

  18. Evaluation of the Doppler-Broadening of Gamma-Ray Spectra from Neutron Inelastic Scattering on Light Nuclei

    SciTech Connect

    Womble, Phillip C.; Barzilov, Alexander; Novikov, Ivan; Howard, Joseph; Musser, Jason

    2009-03-10

    Neutron-induced gamma-ray reactions are extensively used in the nondestructive analysis of materials and other areas where the information about the chemical composition of a substance is crucial. The common technique to find the intensity of the gamma ray is to fit gamma-ray line shape with an analytical function, for example, a Gaussian. However, the Gaussian fitting may fail if the gamma-ray peak is Doppler-broadened since this leads to the miscalculation of the area of the peak and, therefore, to misidentification of the material. Due to momentum considerations, Doppler-broadening occurs primarily with gamma rays from neutron-induced inelastic scattering reactions with light nuclei. The recoiling nucleus of interest must have excited states whose lifetimes are much smaller than the time of flight in the material. We have examined various light nuclei bombarded by 14 MeV neutrons to predict when the peak shape of a neutron-induced gamma ray emitted from these nuclei will be Doppler-broadened. We have found that nearly all the gamma rays from neutron-induced gamma-ray reactions on light elements (A<20) are Doppler-broadened with only a few exceptions. This means that utilization of resolution curves derived from isotopic sources or thermal neutron capture reactions have little value in the analysis.

  19. Reliability of the peak-analysis results in gamma-ray spectrometry for high relative peak-area uncertainties.

    PubMed

    Korun, M; Vodenik, B; Zorko, B

    2015-11-01

    When measurement results with values near the decision threshold are being considered, a relative uncertainty of 60% is expected. Since such measurement results can be reported, the performance of the peak-analysing software for gamma-ray spectra needs to be examined for peaks that have a large relative uncertainty. The investigation was performed on a series of spectra measured with a HPGe detector under identical counting conditions. It was found that under a limit value of the relative peak area uncertainty the peak-analysis results are reliable with respect to both the peak location and the peak area evaluation. At relative uncertainties exceeding this uncertainty, the probability of type-II errors increases and a systematic influence on the peak area occurs, which originates in fluctuations of the continuous background in the vicinity of the peak. For the counting conditions used in this investigation, the limit relative uncertainty is about 35%, and whereas a systematic influence can be taken into account by a correction factor, the frequency of the type-II errors can only be reduced at the expense of increasing the frequency of the type-I errors.

  20. Quantification of gamma-aminobutyric acid in Sri Lankan tea by means of ultra performance tandem mass spectrometry.

    PubMed

    Carvalho, Elisabete; Punyasiri, P A Nimal; Somasiri, H P P Sudarshana; Abeysinghe, I Sarath B; Martens, Stefan

    2014-04-01

    Gamma-Aminobutyric acid (GABA), an important bioactive component of tea, acts as a major inhibitory neurotransmitter and is considered to influence other physiological processes in human as well as in planta. In the hereby presented study, the content of this valuable metabolite was investigated in two novel types of Ceylon Tea, explicitly "Silver Tips" and "White Tea", originating from minimally processed buds of the unique cultivar, "TRI 2043". The samples were subjected to hot water infusion, equivalent to the traditional beverage preparation procedure, and analyzed by means of hydrophilic interaction ultra performance liquid chromatography coupled to tandem mass spectrometry (HILIC LC-MS/MS). The registered GABA levels were compared with those obtained for the classic "Black Tea" and "Green Tea" samples from Sri Lanka. A high variation of GABA content was observed among the different tea types, especially in the case of "Silver Tips" and "White Tea", indicating the crucial influence of the manufacturing procedure (processing extent) on the final abundance of the bioactive component of interest. Furthermore, "White Tea" samples boasted the highest GABA concentration reported for this type of tea so far, reaching up to 50% of that characteristic of the high-priced "GABA Tea". Therefore, "White Tea" and "Silver Tips" were proved to be high quality tea with amounts of gamma-aminobutyric acid comparable with those described for similar types before. To our knowledge, this is the first report on HILIC LC-MS/MS application for the quantification of GABA and for in-depth characterization of teas from Sri Lanka.

  1. PC/FRAM: New capabilities for the gamma-ray spectrometry measurement of plutonium isotopic composition

    SciTech Connect

    Sampson, T.E.; Kelley, T.A.; Cremers, T.L.; Konkel, T.R.; Friar, R.J.

    1995-10-01

    We describe the new capability of and.present measurement results from the PC/FRAM plutonium isotopic analysis code. This new code allows data acquisition from a single coaxial germanium detector and analysis over an energy range from 120 keV to above I MeV. For the first time we demonstrate a complete isotopic analysis using only gamma rays greater than 200 keV in energy. This new capability allows the measurement of the plutonium isotopic composition of items inside shielded or heavy-walled containers without having to remove the items from the container. This greatly enhances worker safety by reducing handling and the resultant radiation exposure. Another application allows international inspectors to verify the contents of items inside sealed, long-term storage containers that may not be opened for national security or treaty compliance reasons. We present measurement results for traditional planar germanium detectors as well as coaxial detectors measuring shielded and unshielded samples.

  2. Optimized background reduction in low-level gamma-ray spectrometry at a surface laboratory.

    PubMed

    Hurtado, S; García-León, M; García-Tenorio, R

    2006-09-01

    The background of a coaxial Ge detector placed at a surface laboratory has been reduced by means of a background reduction setup consisting of a passive shield of low-activity lead, a simple radon suppression system and an active shield with a plastic scintillation plate. In particular, we have devoted our efforts to in-depth optimization of each parameter associated with different anticoincidence setups and to their subsequent intercomparison. The overall performance of the active shield was improved by using the optimum time parameters for each setup. The final objective is to decrease the cosmic-ray background and, by this way, to reduce the detection limits of gamma-ray spectrometers at conventional laboratories, and consequently make them competitive for different measurements like (210)Pb dating.

  3. Streaming of 14-MeV neutrons through an iron duct: comparison of measured neutron and gamma-ray energy spectra with results calculated using the Monte Carlo code MCNP

    SciTech Connect

    Santoro, R.T.; Barnes, J.M.; Soran, P.D.; Alsmiller, R.G. Jr.

    1982-11-01

    Neutron and gamma-ray energy spectra resulting from the streaming of 14 MeV neutrons through a 0.30-m-diameter duct (length-to-diameter ratio = 2.83) have been calculated using the Monte Carlo code MCNP. The calculated spectra are compared with measured data and data calculated previously using a combination of discrete ordinates and Monte Carlo methods. Comparisons are made at twelve detector locations on and off the duct axis for neutrons with energies above 850 keV and for gamma rays with energies above 750 keV. The neutron spectra calculated using MCNP agree with the measured data within approx. 5 to approx. 50%, depending on detector location and neutron energy. Agreement with the measured gamma-ray spectra is also within approx. 5 to approx. 50%. The spectra obtained with MCNP are also in favorable agreement with the previously calculated data and were obtained with less calculational effort.

  4. Visualization of spatial distribution of gamma-aminobutyric acid in eggplant (Solanum melongena) by matrix-assisted laser desorption/ionization imaging mass spectrometry.

    PubMed

    Goto-Inoue, Naoko; Setou, Mitsutoshi; Zaima, Nobuhiro

    2010-01-01

    We applied imaging mass spectrometry (IMS) to determine the spatial distribution of gamma-aminobutyric acid (GABA). We found that GABA had a specific localization in seeds. We also visualized various biomolecules as well as GABA with higher spatial resolution than in the previous report. Our work suggests that IMS might be a powerful tool for exploring functional food factors, investigating the specific distribution of nutrients in unused natural resources, and evaluating the quality of functional foods.

  5. In situ gamma spectrometry measurements and Monte Carlo computations for the detection of radioactive sources in scrap metal.

    PubMed

    Clouvas, A; Xanthos, S; Takoudis, G; Potiriadis, C; Silva, J

    2005-02-01

    A very limited number of field experiments have been performed to assess the relative radiation detection sensitivities of commercially available equipment used to detect radioactive sources in recycled metal scrap. Such experiments require the cooperation and commitment of considerable resources on the part of vendors of the radiation detection systems and the cooperation of a steel mill or scrap processing facility. The results will unavoidably be specific to the equipment tested at the time, the characteristics of the scrap metal involved in the tests, and to the specific configurations of the scrap containers. Given these limitations, the use of computer simulation for this purpose would be a desirable alternative. With this in mind, this study sought to determine whether Monte Carlo simulation of photon flux energy distributions resulting from a radiation source in metal scrap would be realistic. In the present work, experimental and simulated photon flux energy distributions in the outer part of a truck due to the presence of embedded radioactive sources in the scrap metal load are compared. The experimental photon fluxes are deduced by in situ gamma spectrometry measurements with portable Ge detector and the calculated ones by Monte Carlo simulations with the MCNP code. The good agreement between simulated and measured photon flux energy distributions indicate that the results obtained by the Monte Carlo simulations are realistic.

  6. Determination of 137Cs activity in soil from Qatar using high-resolution gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Al-Sulaiti, Huda; Nasir, Tabassum; Al Mugren, K. S.; Alkhomashi, N.; Al-Dahan, N.; Al-Dosari, M.; Bradley, D. A.; Bukhari, S.; Matthews, M.; Regan, P. H.; Santawamaitre, T.; Malain, D.; Habib, A.; Al-Dosari, Hanan; Al Sadig, Ibrahim; Daar, Eman

    2016-10-01

    With interest in establishing baseline concentrations of 137Cs in soil from the Qatarian peninsula, we focus on determination of the activity concentrations in 129 soil samples collected across the State of Qatar prior to the 2011 Fukushima Dai-ichi nuclear power plant accident. As such, the data provides the basis of a reference map for the detection of releases of this fission product. The activity concentrations were measured via high-resolution gamma-ray spectrometry using a hyper-pure germanium detector enclosed in a copper-lined passive lead shield that was situated in a low-background environment. The activity concentrations ranged from 0.21 to 15.41 Bq/kg, with a median value of 1 Bq/kg, the greatest activity concentration being observed in a sample obtained from northern Qatar. Although it cannot be confirmed, it is expected that this contamination is mainly due to releases from the Chernobyl accident of 26 April 1986, there being a lack of data from Qatar before the accident. The values are typically within but are sometimes lower than the range indicated by data from other countries in the region. The lower values than those of others is suggested to be due to variation in soil characteristics as well as metrological factors at the time of deposition.

  7. Development and application of Marinelli beaker standards for monitoring radioactivity in Dairy-Products by gamma-ray spectrometry.

    PubMed

    Lavi, N; Alfassi, Z B

    2004-12-01

    Marinelli (reentrant) beakers are recommended for measurement of low-activity radioactive environmental samples, in both liquid and solid phase. The preparation of Marinelli beaker standards of milk powder containing 232ThO2 at secular equilibrium with its daughter radionuclides was studied. Standards were prepared by mixing of known amounts of solid ThO2 and milk powder. The densities of the standards were 0.5-0.7 kg dm(-3). Measurements of calibrated Marinelli beaker standards with HPGe detector showed that the energy dependence of the efficiency is similar to that of a point source, i.e. an almost linear dependence of log-efficiency vs. log-energy in the 200-2000 keV range, however the parabolic correlation fits better. The validity of these standards was checked by comparison with certified standard reference material IAEA-152-Milk powder containing radiocesium and radiopotassium. The results obtained were found to be in a good agreement with the published certified data. The limit of detection for the determination of radiocesium by gamma ray spectrometry under the prevailing experimental conditions is 0.03 Bq (i.e. 0.8 pCi), for samples of dairy products having lower densities of 0.7 kg dm(-1).

  8. Martian surface heat production and crustal heat flow from Mars Odyssey Gamma-Ray spectrometry

    NASA Astrophysics Data System (ADS)

    Hahn, B. C.; McLennan, S. M.; Klein, E. C.

    2011-07-01

    Martian thermal state and evolution depend principally on the radiogenic heat-producing element (HPE) distributions in the planet's crust and mantle. The Gamma-Ray Spectrometer (GRS) on the 2001 Mars Odyssey spacecraft has mapped the surface abundances of HPEs across Mars. From these data, we produce the first models of global and regional surface heat production and crustal heat flow. As previous studies have suggested that the crust is a repository for approximately 50% of the radiogenic elements on Mars, these models provide important, directly measurable constraints on Martian heat generation. Our calculations show considerable geographic and temporal variations in crustal heat flow, and demonstrate the existence of anomalous heat flow provinces. We calculate a present day average surface heat production of 4.9 ± 0.3 × 10-11 W · kg-1. We also calculate the average crustal component of heat flow of 6.4 ± 0.4 mW · m-2. The crustal component of radiogenically produced heat flow ranges from <1 mW · m-2 in the Hellas Basin and Utopia Planitia regions to ˜13 mW · m-2 in the Sirenum Fossae region. These heat production and crustal heat flow values from geochemical measurements support previous heat flow estimates produced by different methodologies.

  9. Depleted uranium in Kosovo: results of a survey by gamma spectrometry on soil samples.

    PubMed

    Uyttenhove, J; Lemmens, M; Zizi, M

    2002-10-01

    The presence of depleted uranium in the soil of former Yugoslavia after the 1999 conflict raised great public concern all over the world. The so-called Balkan-syndrome is often linked with depleted uranium contamination. An excellent compilation of data about DU and its possible impact on health and environment can be found in the 1999 UNEP report and publications from the Swedish Radiation Protection Institute. Unfortunately, very few systematic and reliable data on the possible depleted uranium concentrations were until now available. Some of these rare data are only available on the web, without adequate information about the experimental procedure used. To clarify the situation, a systematic survey was started in the summer of 2000 as a collaborative effort between Ghent University (Physics Laboratory) and the Belgian Ministry of Defense (Medical Service). From 50 sites selected all over Kosovo, 150 soil samples were measured in the laboratory with a high-resolution gamma-spectrometer. Some sites (14) were explicitly selected based on military information on the use of depleted uranium munitions in the vicinity. After careful analysis we can conclude that there is no indication of any depleted uranium contamination on these 50 sites with a minimal detectable activity of 15 Bq; this corresponds approximately to 1 mg depleted uranium in a typical sample (100-150 g).

  10. Hydration of hyaluronan polysaccharide observed by IR spectrometry. II. Definition and quantitative analysis of elementary hydration spectra and water uptake.

    PubMed

    Haxaire, K; Maréchal, Y; Milas, M; Rinaudo, M

    2003-01-01

    We recorded a series of spectra of sodium hyaluronan (HA) films that were in equilibrium with their surrounding humid atmosphere. The hygrometry of this atmosphere extended from 0 to 0.97% relative humidity. We performed a quantitative analysis of the corresponding series of hydration spectra that are the difference spectra of the film at a defined hygrometry minus the spectrum of the dried film (hygrometry = 0). The principle of this analysis is to use this series of hydration spectra to define a limited number (four) of "elementary hydration spectra" over which we can decompose all hydration spectra with good accuracy. This decomposition, combined with the measurements of the numbers of H(2)O molecules at the origin in these elementary hydration spectra of the three characteristic vibrational bands of H(2)O, allowed us to calculate the hydration number under different relative humidity conditions. This number compares well with that determined by thermogravimetry. Furthermore, the decomposition defines for each hygrometry value which chemical mechanisms represented by elementary hydration spectra are active. This analysis is pursued by determining for the elementary hydration spectra the number of hydrogen bonds established by each of the four alcohol groups found in each disaccharide repeat unit before performing the same analysis for amide and carboxylate groups. These results are later utilized to discuss the structure of HA at various stages of hydration.

  11. Characterization by combined optical and FT infrared spectra of 3d-transition metal ions doped-bismuth silicate glasses and effects of gamma irradiation.

    PubMed

    ElBatal, F H; Abdelghany, A M; ElBatal, H A

    2014-03-25

    Optical and infrared absorption spectral measurements were carried out for binary bismuth silicate glass and other derived prepared samples with the same composition and containing additional 0.2% of one of 3d transition metal oxides. The same combined spectroscopic properties were also measured after subjecting the prepared glasses to a gamma dose of 8 Mrad. The experimental optical spectra reveal strong UV-near visible absorption bands from the base and extended to all TMs-doped samples and these specific extended and strong UV-near visible absorption bands are related to the contributions of absorption from both trace iron (Fe(3+)) ions present as contaminated impurities within the raw materials and from absorption of main constituent trivalent bismuth (Bi(3+)) ions. The strong UV-near visible absorption bands are observed to suppress any further UV bands from TM ions. The studied glasses show obvious resistant to gamma irradiation and only small changes are observed upon gamma irradiation. This observed shielding behavior is related to the presence of high Bi(3+) ions with heavy mass causing the observed stability of the optical absorption. Infrared absorption spectra of the studied glasses reveal characteristic vibrational bands due to both modes from silicate network and the sharing of Bi-O linkages and the presence of TMs in the doping level (0.2%) causes no distinct changes within the number or position of the vibrational modes. The presence of high Bi2O3 content (70 mol%) appears to cause stability of the structural building units towards gamma irradiation as revealed by FTIR measurements.

  12. Structural Characterization of Methylenedianiline Regioisomers by Ion Mobility-Mass Spectrometry, Tandem Mass Spectrometry, and Computational Strategies: I. Electrospray Spectra of 2-Ring Isomers

    PubMed Central

    2015-01-01

    Purified methylenedianiline (MDA) regioisomers were structurally characterized and differentiated using tandem mass spectrometry (MS/MS), ion mobility-mass spectrometry (IM-MS), and IM-MS/MS in conjunction with computational methods. It was determined that protonation sites on the isomers can vary depending on the position of amino groups, and the resulting protonation sites play a role in the gas-phase stability of the isomer. We also observed differences in the relative distributions of protonated conformations depending on experimental conditions and instrumentation, which is consistent with previous studies on aniline in the gas phase. This work demonstrates the utility of a multifaceted approach for the study of isobaric species and elucidates why previous MDA studies may have been unable to detect and/or differentiate certain isomers. Such analysis may prove useful in the characterization of larger MDA multimeric species, industrial MDA mixtures, and methylene diphenyl diisocyanate (MDI) mixtures used in polyurethane synthesis. PMID:24678803

  13. Gamma-ray blazar spectra with H.E.S.S. II mono analysis: The case of PKS 2155-304 and PG 1553+113

    NASA Astrophysics Data System (ADS)

    H.E.S.S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Andersson, T.; Angüner, E. O.; Arrieta, M.; Aubert, P.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Becker Tjus, J.; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Brun, F.; Brun, P.; Bryan, M.; Bulik, T.; Capasso, M.; Carr, J.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Condon, B.; Conrad, J.; Couturier, C.; Cui, Y.; Davids, I. D.; Degrange, B.; Deil, C.; Devin, J.; deWilt, P.; Dirson, L.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O.'C.; Dubus, G.; Dutson, K.; Dyks, J.; Edwards, T.; Egberts, K.; Eger, P.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Funk, S.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Goyal, A.; Grondin, M.-H.; Hadasch, D.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holler, M.; Horns, D.; Ivascenko, A.; Jacholkowska, A.; Jamrozy, M.; Janiak, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jogler, T.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kerszberg, D.; Khélifi, B.; Kieffer, M.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Kraus, M.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lees, J.-P.; Lefaucheur, J.; Lefranc, V.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morå, K.; Moulin, E.; Murach, T.; de Naurois, M.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Öttl, S.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Poon, H.; Prokhorov, D.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Settimo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Simoni, R.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tuffs, R.; Uchiyama, Y.; van der Walt, D. J.; van Eldik, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Żywucka, N.; LAT Collaboration; Ackermann, M.; Ajello, M.; Baldini, L.; Barbiellini, G.; Bellazzini, R.; Blandford, R. D.; Bonino, R.; Bregeon, J.; Bruel, P.; Buehler, R.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Cohen-Tanugi, J.; Costanza, F.; Cutini, S.; D'Ammando, F.; de Palma, F.; Desiante, R.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Donaggio, B.; Favuzzi, C.; Focke, W. B.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, F.; Giroletti, M.; Guillemot, L.; Guiriec, S.; Horan, D.; Jóhannesson, G.; Kamae, T.; Kensei, S.; Kocevski, D.; Larsson, S.; Li, J.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Maldera, S.; Manfreda, A.; Mazziotta, M. N.; Michelson, P. F.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Negro, M.; Nuss, E.; Orienti, M.; Orlando, E.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Principe, G.; Rainò, S.; Razzano, M.; Simone, D.; Siskind, E. J.; Spada, F.; Spinelli, P.; Thayer, J. B.; Torres, D. F.; Torresi, E.; Troja, E.; Vianello, G.; Wood, K. S.

    2017-04-01

    Context. The addition of a 28 m Cherenkov telescope (CT5) to the H.E.S.S. array extended the experiment's sensitivityto lower energies. The lowest energy threshold is obtained using monoscopic analysis of data taken with CT5, providing access to gamma-ray energies below 100 GeV for small zenith angle observations. Such an extension of the instrument's energy range is particularly beneficial for studies of active galactic nuclei with soft spectra, as expected for those at a redshift ≥0.5. The high-frequency peaked BL Lac objects PKS 2155-304 (z = 0.116) and PG 1553+113 (0.43 < z < 0.58) are among the brightest objects in the gamma-ray sky, both showing clear signatures of gamma-ray absorption at E > 100 GeV interpreted as being due to interactions with the extragalactic background light (EBL). Aims: The aims of this work are twofold: to demonstrate the monoscopic analysis of CT5 data with a low energy threshold, and to obtain accurate measurements of the spectral energy distributions (SED) of PKS 2155-304 and PG 1553+113 near their SED peaks at energies ≈100 GeV. Methods: Multiple observational campaigns of PKS 2155-304 and PG 1553+113 were conducted during 2013 and 2014 using the full H.E.S.S. II instrument (CT1-5). A monoscopic analysis of the data taken with the new CT5 telescope was developed along with an investigation into the systematic uncertainties on the spectral parameters which are derived from this analysis. Results: Using the data from CT5, the energy spectra of PKS 2155-304 and PG 1553+113 were reconstructed down to conservative threshold energies of 80 GeV for PKS 2155-304, which transits near zenith, and 110 GeV for the more northern PG 1553+113. The measured spectra, well fitted in both cases by a log-parabola spectral model (with a 5.0σ statistical preference for non-zero curvature for PKS 2155-304 and 4.5σ for PG 1553+113), were found consistent with spectra derived from contemporaneous Fermi-LAT data, indicating a sharp break in the

  14. 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.

  15. Improvements on Low Level Activity Gamma Measurements and X-ray Spectrometry at the CEA-MADERE Measurement Platform

    NASA Astrophysics Data System (ADS)

    Sergeyeva, Victoria; Domergue, Christophe; Destouches, Christophe; Girard, Jean Michel; Philibert, Hervé; Bonora, Jonathan; Thiollay, Nicolas; Lyoussi, Abdallah

    2016-02-01

    The CEA MADERE platform (Measurement Applied to DosimEtry in REactors) is a part of the Instrumentation Sensors and Dosimetry Laboratory (LDCI). This facility is dedicated to the specific activity measurements of solid and radioactive samples using Gamma and X-ray spectrometry. MADERE is a high-performance facility devoted to neutron dosimetry for experimental programs performed in CEA and for the irradiation surveillance programmes of PWR vessels. The MADERE platform is engaged in a continuous improvement process. Recently, two High Efficiency diodes have been integrated to the MADERE platform in order to manage the accurate low level activity measurements (few Bq per sample). This new equipment provides a good level of efficiency over the energy range from 60 keV to 2 MeV. The background continuum is reduced due to the use of a Ultra Low Background (ULB) lead shielding. Relative and absolute X-ray measurement techniques have been improved in order to facilitate absolute rhodium activity measurement (Rh103m) on solid samples. Additional efforts have been made to increase the accuracy of the relative niobium (Nb93m) activity measurement technique. The way of setting up an absolute measurement method for niobium is under investigation. After a presentation of the MADERE's measurement devices, this paper focuses on the technological options taken into account for the design of high efficiency measurement devices. Then, studies performed on X-ray measurement techniques are presented. Some details about the calculation of uncertainties and correction factors are also mentioned. Finally, future research and development axes are exposed.

  16. Absorption-mode Fourier transform mass spectrometry: the effects of apodization and phasing on modified protein spectra.

    PubMed

    Qi, Yulin; Li, Huilin; Wills, Rebecca H; Perez-Hurtado, Pilar; Yu, Xiang; Kilgour, David P A; Barrow, Mark P; Lin, Cheng; O'Connor, Peter B

    2013-06-01

    The method of phasing broadband Fourier transform ion cyclotron resonance (FT-ICR) spectra allows plotting the spectra in the absorption-mode; this new approach significantly improves the quality of the data at no extra cost. Herein, an internal calibration method for calculating the phase function has been developed and successfully applied to the top-down spectra of modified proteins, where the peak intensities vary by 100×. The result shows that the use of absorption-mode spectra allows more peaks to be discerned within the recorded data, and this can reveal much greater information about the protein and modifications under investigation. In addition, noise and harmonic peaks can be assigned immediately in the absorption-mode.

  17. Measurement of {sup 25}Mg(p, {gamma}){sup 26}Al{sup g} resonance strengths via accelerator mass spectrometry

    SciTech Connect

    Arazi, A.; Niello, J. O. Fernandez; Faestermann, T.; Knie, K.; Korschinek, G.; Poutivtsev, M.; Rugel, G.; Richter, E.; Wallner, A.

    2006-08-15

    The strengths of resonances located at center-of-mass energies of E{sub c.m.}=189, 304, 374, and 418 keV for the {sup 25}Mg(p,{gamma}) reaction have been measured for the first time with an off-line method: Mg targets were firstly activated with protons at the resonance energies and the produced {sup 26}Al{sup g} nuclei were counted by means of highly sensitive accelerator mass spectrometry (AMS). Thus, the production of {sup 26}Al in its ground state is determined independently from the {gamma}-decay branching ratio. While the 304, 374, and 418 keV resonances show fair agreement with previous measurements, the 189 keV resonance yield a significantly less strength. In addition, an experimental upper limit for the E{sub c.m.}=92 keV resonance was determined.

  18. Energetic neutron and gamma-ray spectra under the earth radiation belts according to "SALYUT-7" [correction of "SALUTE-7"]-"KOSMOS-1686" orbital complex and "CORONAS-I" satellite data.

    PubMed

    Bogomolov, A V; Dmitriev, A V; Myagkova, I N; Ryumin, S P; Smirnova, O N; Sobolevsky, I M

    1998-01-01

    The spectra of neutrons >10 MeV and gamma-rays 1.5-100 MeV under the Earth Radiation Belts, restored from the data, obtained onboard orbital complex "SALYUT-7" [correction of "SALUTE-7"]-"KOSMOS-1686", are presented. The spectra shapes are similar to those for albedo neutrons and gamma-rays, but absolute values of their fluxes (0.2 cm-2 s-1 for neutrons, 0.8 cm-2 s-1 for gamma-rays at the equator and 1.2 cm-2 s-1, 1.9 cm-2 s-1, accordingly, at L=1.9) are several times as large. It is possibly explained by the fact that most of the detected particles were produced by the cosmic ray interactions with the orbital complex matter. Neutron and gamma-ray fluxes obtained from "CORONAS-1" data are near those for albedo particles.

  19. Gamma-ray spectrometry method used for radioactive waste drums characterization for final disposal at National Repository for Low and Intermediate Radioactive Waste--Baita, Romania.

    PubMed

    Done, L; Tugulan, L C; Dragolici, F; Alexandru, C

    2014-05-01

    The Radioactive Waste Management Department from IFIN-HH, Bucharest, performs the conditioning of the institutional radioactive waste in concrete matrix, in 200 l drums with concrete shield, for final disposal at DNDR - Baita, Bihor county, in an old exhausted uranium mine. This paper presents a gamma-ray spectrometry method for the characterization of the radioactive waste drums' radionuclides content, for final disposal. In order to study the accuracy of the method, a similar concrete matrix with Portland cement in a 200 l drum was used.

  20. Measurement of the 238U neutron-capture cross section and gamma-emission spectra from 10 eV to 100 keV using the DANCE detector at LANSCE

    SciTech Connect

    Ullmann, John L; Couture, A J; Keksis, A L; Vieira, D J; O' Donnell, J M; Jandel, M; Haight, R C; Rundberg, R S; Kawano, T; Chyzh, A; Baramsai, B; Wu, C Y; Mitchell, G E; Becker, J A; Krticka, M

    2010-01-01

    A careful new measurement of the {sup 238}U(n,{gamma}) cross section from 10 eV to 100 keV has been made using the DANCE detector at LANSCE. DANCE is a 4{pi} calorimetric scintillator array consisting of 160 BaF{sub 2} crystals. Measurements were made on a 48 mg/cm{sup 2} depleted uranium target. The cross sections are in general good agreement with previous measurements. The gamma-ray emission spectra, as a function of gamma multiplicity, were also measured and compared to model calculations.

  1. Exploiting Kalman Filtering Non-linear Exponential Fitting to Promote the Energy Resolution of 137Cs and 60Co Gamma Ray Spectra.

    PubMed

    Guo, Huiping; Tian, Chenyang; Xue, Hongbin; Lv, Ning; Wei, Yingguang; Fu, Guangzhi; Lv, Wenhui; Zhao, Kuo; Hou, Yijie

    2017-03-01

    For Cs and Co gamma ray spectra, gamma ray energy is proportional to the amplitude of the pulse signal, and energy resolution can be improved by pulse signal processing with mathematical algorithms. Influenced by system measurement noise and baseline fluctuation, the pulse amplitude is difficult to calculate accurately. A method that combines the Kalman filter baseline estimation with the non-linear exponential fitting has been used. By this method, the pulse signal is divided into two parts: one is the raising edge before the pulse peak, and another is after the pulse peak. The pulse amplitude equals the difference between the pulse starting height and the pulse peak height. The pulse starting height is obtained by Kalman filter baseline estimation on the rising edge of the pulse starting point. The pulse peak height is calculated by nonlinear exponential fitting on the falling edge of the pulse highest point. When the sampling rate is 100 MHz, the pulse signals obtained from a Cd(Zn)Te detector are analyzed by this method. Results have shown that the processed pulses have a more distinguishable amplitude distribution; energy resolution for the Cs spectrum is approximately 2.97% at 662 keV (~19.66 keV FWHM), and for the Co spectrum it is 2.61% at 1,332 keV (~34.76 keV FWHM).

  2. Comparison Between the NIST and the KEBS for the Determination of Air Kerma Calibration Coefficients for Narrow X-Ray Spectra and (137)Cs Gamma-Ray Beams.

    PubMed

    O'Brien, Michelle; Minniti, Ronaldo; Masinza, Stanslaus Alwyn

    2010-01-01

    Air kerma calibration coefficients for a reference class ionization chamber from narrow x-ray spectra and cesium 137 gamma-ray beams were compared between the National Institute of Standards and Technology (NIST) and the Kenya Bureau of Standards (KEBS). A NIST reference-class transfer ionization chamber was calibrated by each laboratory in terms of the quantity air kerma in four x-ray reference radiation beams of energies between 80 kV and 150 kV and in a cesium 137 gamma-ray beam. The reference radiation qualities used for this comparison are described in detail in the ISO 4037 publication.[1] The comparison began in September 2008 and was completed in March 2009. The results reveal the degree to which the participating calibration facility can demonstrate proficiency in transferring air kerma calibrations under the conditions of the said facility at the time of the measurements. The comparison of the calibration coefficients is based on the average ratios of calibration coefficients.

  3. The use of the bulk properties of gamma-ray burst prompt emission spectra for the study of cosmology

    NASA Astrophysics Data System (ADS)

    Goldstein, Adam

    The study of bulk spectral properties of Gamma-Ray Bursts (GRBs) is important to understanding the physics behind these powerful explosions and may even be an aide in studying cosmology. The prompt emission spectral properties have long been studied by a growing community of researchers, and many theories have been developed since the discovery of GRBs. Even though the exact physics of these phenomena is not completely understood, GRBs have been proposed to give insight on other astrophysical phenomena from dark matter to the expansion of the universe. Obviously, using GRBs to study cosmology requires a large sample size to adequately constrain results and provide confident conjectures. For this reason, BATSE and GBM results are paramount to the study of the prompt emission of GRBs. Using results from both instruments, I study the bulk spectral properties of GRBs and describe analysis techniques that can be used to study cosmology.

  4. Low-resolution gamma-ray spectrometry for an information barrier based on a multi-criteria template-matching approach

    NASA Astrophysics Data System (ADS)

    Göttsche, Malte; Schirm, Janet; Glaser, Alexander

    2016-12-01

    Gamma-ray spectrometry has been successfully employed to identify unique items containing special nuclear materials. Template information barriers have been developed in the past to confirm items as warheads by comparing their gamma signature to the signature of true warheads. Their development has, however, not been fully transparent, and they may not be sensitive to some relevant evasion scenarios. We develop a fully open template information barrier concept, based on low-resolution measurements, which, by design, reduces the extent of revealed sensitive information. The concept is based on three signatures of an item to be compared to a recorded template. The similarity of the spectrum is assessed by a modification of the Kolmogorov-Smirnov test to confirm the isotopic composition. The total gamma count rate must agree with the template as a measure of the projected surface of the object. In order to detect the diversion of fissile material from the interior of an item, a polyethylene mask is placed in front of the detector. Neutrons from spontaneous and induced fission events in the item produce 2.223 MeV gamma rays from neutron capture by hydrogen-1 in the mask. This peak is detected and its intensity scales with the item's fissile mass. The analysis based on MCNP Monte Carlo simulations of various plutonium configurations suggests that this concept can distinguish a valid item from a variety of invalid ones. The concept intentionally avoids any assumptions about specific spectral features, such as looking for specific gamma peaks of specific isotopes, thereby facilitating a fully unclassified discussion. By making all aspects public and allowing interested participants to contribute to the development and benchmarking, we enable a more open and inclusive discourse on this matter.

  5. On background radiation gradients--the use of airborne surveys when searching for orphan sources using mobile gamma-ray spectrometry.

    PubMed

    Kock, Peder; Rääf, Christopher; Samuelsson, Christer

    2014-02-01

    Systematic background radiation variations can lead to both false positives and failures to detect an orphan source when searching using car-borne mobile gamma-ray spectrometry. The stochastic variation at each point is well described by Poisson statistics, but when moving in a background radiation gradient the mean count rate will continually change, leading to inaccurate background estimations. Airborne gamma spectrometry (AGS) surveys conducted on the national level, usually in connection to mineral exploration, exist in many countries. These data hold information about the background radiation gradients which could be used at the ground level. This article describes a method that aims to incorporate the systematic as well as stochastic variations of the background radiation. We introduce a weighted moving average where the weights are calculated from existing AGS data, supplied by the Geological Survey of Sweden. To test the method we chose an area with strong background gradients, especially in the thorium component. Within the area we identified two roads which pass through the high-variability locations. The proposed method is compared with an unweighted moving average. The results show that the weighting reduces the excess false positives in the positive background gradients without introducing an excess of failures to detect a source during passage in negative gradients.

  6. Calculation spreadsheet for uncertainty estimation of measurement results in gamma-ray spectrometry and its validation for quality assurance purpose.

    PubMed

    Ceccatelli, Alessia; Dybdal, Ashild; Fajgelj, Ales; Pitois, Aurelien

    2017-03-03

    An Excel calculation spreadsheet has been developed to estimate the uncertainty of measurement results in γ-ray spectrometry. It considers all relevant uncertainty components and calculates the combined standard uncertainty of the measurement result. The calculation spreadsheet has been validated using two independent open access software and is available for download free of charge at: https://nucleus.iaea.org/rpst/ReferenceProducts/Analytical_Methods/index.htm. It provides a simple and easy-to-use template for estimating the uncertainty of γ-ray spectrometry measurement results and supports the radioanalytical laboratories seeking accreditation for their measurements using γ-ray spectrometry.

  7. Mass spectrometry of analytical derivatives. 2. "Ortho" and "Para" effects in electron ionization mass spectra of derivatives of hydroxy, mercapto and amino benzoic acids.

    PubMed

    Todua, Nino G; Mikaia, Anzor I

    2016-01-01

    Derivatives requiring either anhydrous or aqueous reaction conditions were prepared for robust and reliable gas chromatography/mass spectrometry (GC/MS) characterization of hydroxyl, mercapto, and amino benzoic acids Methylation and trialkylsilytation are employed for blocking the acidic function. Alkyl, trimethylsilyl, acetyl, perfluoroacyl and alkoxycarbonyl derivatization groups are introduced to hydroxyl, mercapto and amino functions. The electron ionization induced fragmentation characteristics of corresponding derivatives are explained by comparing the MS(1) spectra of unlabeled compounds to their (2)H and (13)C labeled analogs, and analysis of collision-induced dissociation data from MS(2) spectra. Competing fragmentation alternatives are identified and specific decomposition processes are detailed that characterize (a) ortho isomers due to interaction or vicinal functional substituents and (b) para isomers prone to forming para quinoid type structures. Skeletal and hydrogen rearrangements typical for methyl benzoates and the blocking groups are considered when discussing diagnostically important ions. Characteristic ions produced as a result of rearrangements in ortho isomers are classified, and skeletal rearrangements required to produce para quinoid type ions specific for para isomers are noted. Key ions for structure elucidation and differentiation of isomers for derivatives of substituted benzoic acids by GC/MS are suggested.

  8. The average X-ray/gamma-ray spectra of Seyfert galaxies from Ginga and OSSE and the origin of the cosmic X-ray background

    NASA Technical Reports Server (NTRS)

    Zdziarski, Andrzej A.; Johnson, W. Neil; Done, Chris; Smith, David; Mcnaron-Brown, Kellie

    1995-01-01

    We have obtained the first average 2-500 keV spectra of Seyfert galaxies, using the data from Ginga and Compton Gamma-Ray Observatory's (CGRO) Oriented Scintillation Spectrometer Experiment (OSSE). Our sample contains three classes of objects with markedly different spectra: radio-quiet Seyfert 1's and 2's, and radio-loud Seyfert 1's. The average radio-quiet Seyfert 1 spectrum is well-fitted by a power law continuum with the energy spectral index alpha approximately equals 0.9, a Compton reflection component corresponding to a approximately 2 pi covering solid angle, and ionized absorption. There is a high-energy cutoff in the incident power law continuum: the e-folding energy is E(sub c) approximately equals 0.6(sup +0.8 sub -0.3) MeV. The simplest model that describes this spectrum is Comptonization in a relativistic optically-thin thermal corona above the surface of an accretion disk. Radio-quiet Seyfert 2's show strong netural absorption, and there is an indication that their X-ray power laws are intrinsically harder. Finally, the radio-loud Seyfert spectrum has alpha approximately equals 0.7, moderate neutral absorption E(sub C) = 0.4(sup +0.7 sub -0.2) MeV, and no or little Compton reflection. This is incompatible with the radio-quiet Seyfert 1 spectrum, and probably indicating that the X-rays are beamed away from the accretion disk in these objects. The average spectra of Seyferts integrated over redshift with a power-law evolution can explain the hard X-ray spectrum of the cosmic background.

  9. F-GAMMA program: Unification and physical interpretation of the radio spectra variability patterns in Fermi blazars and detection of radio jet emission from NLSY1 galaxies

    NASA Astrophysics Data System (ADS)

    Angelakis, E.

    2012-01-01

    The F-GAMMA program aims at understanding the physics at work in AGN via a multi-frequency monitoring approach. A number of roughly 65 Fermi-GST detectable blazars are being monitored monthly since January 2007 at radio wavelengths. The core program relies on the 100-m Effelsberg telescope operating at 8 frequencies between 2.6 and 43 GHz, the 30-m IRAM telescope observing at 86, 145 and 240 GHz and the APEX 12-m telescope at 345 GHz. For the targeted sources the LAT instrument onboard Fermi-GST provides gamma-ray light curves sampled daily. Here we discuss two recent findings: A). On the basis of their variability pattern, the observed quasi-simultaneous broad-band spectra can be classified to merely 5 classes. The variability for the first 4 is clearly dominated by spectral-evolution. Sources of the last class vary self-similarly with almost no apparent shift of the peak frequency. The former classes can be attributed to a two-component principal system made of a quiescent optically thin spectrum and a super-imposed flaring event. The later class must be interpreted in terms of a completely different mechanism. The apparent differences among the classes are explained in terms of a redshift modulus and an intrinsic-source/flare parameters modulus. Numerical simulations have shown that a shock-in-jet model can very well describe the observed behavior. It is concluded therefore that only two mechanisms seem to be producing variability. None of the almost 90 sources used for this study show a switch of class indicating that the variability mechanism is either (a) a finger-print of the source, or (b) remains stable on timescales far longer than the monitoring period of almost 4 years. B). Recently it has been disclosed that Narrow Line Seyfert 1 galaxies show gamma-ray emission. Within the F-GAMMA program radio jet emission has been detected from 3 such sources challenging the belief that jets are associated with elliptical galaxies. The recent findings in this area

  10. Size Effect on Nuclear Gamma-Ray Energy Spectra Acquired by Different Sized CeBr3, LaBr3:Ce, and NaI:Tl Gamma-Ray Detectors

    SciTech Connect

    Guss, Paul; Reed, Michael; Yuan, Ding; Beller, Denis; Cutler, Matthew; Contreras, Chris; Mukhopadhyay, Sanjoy; Wilde, Scott UNLV

    2014-03-01

    Gamma-ray energy spectra were acquired for different sizes of cerium tribromide (CeBr3), cerium-doped lanthanum tribromide (LaBr3:Ce), and thallium-doped sodium iodide (NaI:Tl) detectors. A comparison was conducted of the energy resolution and detection efficiency of these scintillator detectors for different sizes of detectors. The results of this study are consistent with the observation that for each size detector, LaBr3:Ce offers better resolution than either a CeBr3 or NaI:Tl detector of the same size. In addition, CeBr3 and LaBr3:Ce detectors could resolve some closely spaced peaks in the spectra of several radioisotopes that NaI:Tl could not. As the detector size increased, all three detector materials exhibited higher efficiency, albeit with slightly reduced resolution. Significantly, the very low intrinsic activity of CeBr3 is also demonstrated in this study, which, when combined with energy resolution characteristics for a range of detector sizes, could lead to an improved ability to detect special nuclear materials compared to the other detectors.

  11. Identification of differentially expressed proteins of gamma-ray irradiated rat intestinal epithelial IEC-6 cells by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionisation-time of flight mass spectrometry.

    PubMed

    Bo, Zhang; Yongping, Su; Fengchao, Wang; Guoping, Ai; Yongjiang, Wei

    2005-02-01

    To identify proteins involved in the processes of cellular and molecular response to radiation damage repair in intestinal epithelial IEC-6 cells, we comparatively analyzed the proteome of irradiated IEC-6 cells with that of normal cells. A series of methods were used, including two-dimensional gel electrophoresis (Z-DE), PDQuest software analysis of 2-DE gels, peptide mass fingerprinting based on matrix-assisted laser desorption/ionisation-time of flight-mass spectrometry (MALDI-TOF-MS), and Swiss-Prot database searching, to separate and identify differentially expressed proteins. Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) were used to validate the differentially expressed proteins. Image analysis revealed that averages of 608 +/- 39 and 595 +/- 31 protein spots were detected in normal and irradiated IEC-6 cells, respectively. Sixteen differential protein spots were isolated from gels, and measured with MALDI-TOF-MS. A total of 14 spots yielded good spectra, and 11 spots matched with known proteins after database searching. These proteins were mainly involved in anti-oxidation, metabolism, and protein post-translational processes. Western blotting confirmed that stress-70 protein was down-regulated by gamma-irradiation. Up-regulation of ERP29 was confirmed by RT-PCR, indicating that it is involved in ionizing radiation. The clues provided by the comparative proteome strategy utilized here will shed light on molecular mechanisms of radiation damage repair in intestinal epithelial cells.

  12. Reduction of metal adducts in oligonucleotide mass spectra in ion‐pair reversed‐phase chromatography/mass spectrometry analysis

    PubMed Central

    Gilar, Martin; Shion, Henry; Yu, Ying Qing; Chen, Weibin

    2016-01-01

    Rationale Electrospray ionization mass spectrometry (ESI‐MS)‐based techniques commonly used in oligonucleotide analyses are known to be sensitive to alkali metal adduct formation. Adducts directly impact the sensitivity of MS‐based analyses as the available charge is distributed across the parent peak and adduct(s). The current study systematically evaluated common liquid chromatography (LC) components in LC/ESI‐MS configurations used in oligonucleotide analysis to identify metal adduct contributions from LC instrumentation. Methods A UPLC liquid chromatography system was configured with a single quadrupole MS detector (ACQUITY QDa, Waters Corp.) to monitor adduct formation in oligonucleotide separations. An ion‐pairing mobile phase comprised of 15 mM triethylamine and 400 mM hexafluoro‐2‐propanol was used in conjunction with an oligonucleotide separation column (Waters OST BEH C18, 2.1 mm × 50 mm) for all separations. A 10‐min method was used to provide statistical figures of merit and evaluate adduct formation over time. Results Trace alkali metal salts in the mobile phase and reagents were determined to be the main source of metal salt adducts in LC/ESI‐MS‐based configurations. Non‐specific adsorption sites located throughout the fluidic path contribute to adduct formation in oligonucleotide analyses. Ion‐pairing mobile phases prepared at neutral or slightly basic pH result in up to a 57% loss of spectral abundance to adduct formation in the current study. Conclusions Implementation of a short low pH reconditioning step was observed to effectively displace trace metal salts non‐specifically adsorbed to surfaces in the fluidic path and was able to maintain an average MS spectral abundance ≥94% with a high degree of repeatability (relative standard deviation (R.S.D.) 0.8%) over an extended time study. The proposed method offers the ability to rapidly regenerate adsorption sites with minimal impact on productivity while retaining

  13. Spectral interference corrections for the measurement of (238)U in materials rich in thorium by a high resolution gamma-ray spectrometry.

    PubMed

    Yücel, H; Solmaz, A N; Köse, E; Bor, D

    2009-11-01

    In this study, the spectral interferences are investigated for the analytical peaks at 63.3 keV of (234)Th and 1001.0 keV of (234m)Pa, which are often used in the measurement of (238)U activity by the gamma-ray spectrometry. The correction methods are suggested to estimate the net peak areas of the gamma-rays overlapping the analytical peaks, due to the contribution of (232)Th that may not be negligible in materials rich in natural thorium. The activity results for the certified reference materials (CRMs) containing U and Th were measured with a well type Ge detector. The self-absorption and true coincidence-summing (TCS) effects were also taken into account in the measurements. It is found that ignoring the contributions of the interference gamma-rays of (232)Th and (235)U to the mixed peak at 63.3 keV of (234)Th ((238)U) leads to the remarkably large systematic influence of 0.8-122% in the measured (238)U activity, but in case of ignoring the contribution of (232)Th via the interference gamma-ray at 1000.7 keV of (228)Ac to the mixed peak at 1001 keV of (234m)Pa ((238)U) results in relatively smaller systematic influence of 0.05-3%, depending on thorium contents in the samples. The present results showed that the necessary correction for the spectral interferences besides self-absorption and TCS effects is also very important to obtain more accurate (238)U activity results. Additionally, if one ignores the contribution of (232)Th to both (238)U and (40)K activities in materials, the maximum systematic influence on the effective radiation dose is estimated to be ~6% and ~1% via the analytical peaks at 63.3 and 1001 keV for measurement of the (238)U activity, respectively.

  14. Comparison of optimised germanium gamma spectrometry and multicollector inductively coupled plasma mass spectrometry for the determination of 134Cs, 137Cs and 154Eu single ratios in highly burnt UO 2

    NASA Astrophysics Data System (ADS)

    Caruso, S.; Günther-Leopold, I.; Murphy, M. F.; Jatuff, F.; Chawla, R.

    2008-05-01

    Non-destructive and destructive methods have been compared to validate their corresponding assessed accuracies in the measurement of 134Cs/137Cs and 154Eu/137Cs isotopic concentration ratios in four spent UO2 fuel samples with very high (52 and 71 GWd/t) and ultra-high (91 and 126 GWd/t) burnup values, and about 10 (in the first three samples) and 4 years (in the latter sample) cooling time. The non-destructive technique tested was high-resolution gamma spectrometry using a high-purity germanium detector (HPGe) and a special tomographic station for the handling of highly radioactive 400 mm spent fuel segments that included a tungsten collimator, lead filter (to enhance the signal to Compton background ratio and reduce the dead time) and paraffin wax (to reduce neutron damage). The non-destructive determination of these isotopic concentration ratios has been particularly challenging for these segments because of the need to properly derive non-Gaussian gamma-peak areas and subtract the background from perturbing capture gammas produced by the intrinsic high-intensity neutron emissions from the spent fuel. Additionally, the activity distribution within each pin was determined tomographically to correct appropriately for self-attenuation and geometrical effects. The ratios obtained non-destructively showed a 1σ statistical error in the range 1.9-2.9%. The destructive technique used was a high-performance liquid chromatographic separation system, combined online to a multicollector inductively coupled plasma mass spectrometer (HPLC-MC-ICP-MS), for the analysis of dissolved fuel solutions. During the mass spectrometric analyses, special care was taken in the optimisation of the chromatographic separation for Eu and the interfering element Gd, as also in the mathematical correction of the 154Gd background from the 154Eu signal. The ratios obtained destructively are considerably more precise (1σ statistical error in the range 0.4-0.8% for most of the samples, but up to

  15. Reply to "Comment on `Gamma-ray spectra from low-energy positron annihilation processes in molecules' "

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoguang; Wang, Meishan; Zhu, Yinghao; Yang, Chuanlu

    2017-03-01

    In reply to the Comment of Green et al. [Phys. Rev. A 95, 036701 (2017)., 10.1103/PhysRevA.95.036701] on our paper [Phys. Rev. A 94, 052709 (2016), 10.1103/PhysRevA.94.052709], we reconfirm that all the conclusions are based on the observation and the comparisons of the theoretical and experimental data. One criticism of Green et al. [Phys. Rev. A 95, 036701 (2017)., 10.1103/PhysRevA.95.036701] concerns the positrophilic electrons and the inner valence electrons. The inner valence electrons or positrophilic electrons show most agreeable widths with the corresponding experimental measurements due to their narrowest momentum distributions for all 59 molecules. However, we agree with the criticism of Green et al. [Phys. Rev. A 95, 036701 (2017)., 10.1103/PhysRevA.95.036701] and reconfirm that this agreement does not represent the dominance of the inner valence in the annihilation process. In this Reply, we will clarify the difference between agreement and dominance and illustrate with some figures. Another criticism is about the approximation used in our paper. We emphasize that the averaged discrepancy of 34.2% for these molecules of the theoretical γ -ray spectra from the experimental measurements is due to the neglect of the positron-electron correlations, vibrational couplings, virtual-state formation, even tunneling of core electrons not the neglect of the positron wave function. In this Reply, we will show, even in this zero-order approximation, these positron-induced effects in the electron-positron annihilation process of molecules can also be analyzed with more corrections and explanations.

  16. Mass spectrometry.

    NASA Technical Reports Server (NTRS)

    Burlingame, A. L.; Johanson, G. A.

    1972-01-01

    Review of the current state of mass spectrometry, indicating its unique importance for advanced scientific research. Mass spectrometry applications in computer techniques, gas chromatography, ion cyclotron resonance, molecular fragmentation and ionization, and isotope labeling are covered. Details are given on mass spectrometry applications in bio-organic chemistry and biomedical research. As the subjects of these applications are indicated alkaloids, carbohydrates, lipids, terpenes, quinones, nucleic acid components, peptides, antibiotics, and human and animal metabolisms. Particular attention is given to the mass spectra of organo-inorganic compounds, inorganic mass spectrometry, surface phenomena such as secondary ion and electron emission, and elemental and isotope analysis. Further topics include mass spectrometry in organic geochemistry, applications in geochronology and cosmochemistry, and organic mass spectrometry.

  17. Thermal neutron fluence from ultra low-level gamma-ray spectrometry of spoons activated during the JCO criticality accident at Tokai-mura in 1999.

    PubMed

    Hult, Mikael; Martínez Canet, María Jose; Johnston, Peter N; Komura, Kazuhisa

    2002-01-01

    During the JCO-accident in Tokai-mura in 1999, the surrounding village was irradiated by an uncontrolled neutron flux. At some locations in that village, the thermal neutron flux was determined retrospectively by measurement of the very low activity of 51Cr and 60Co in stainless-steel spoons using gamma-ray spectrometry in underground laboratories. Activities determined in the HADES underground facility are presented here, together with calibrations performed using a well-defined thermal neutron flux to directly estimate the fluence of thermal neutrons independent of most assumptions. The results show measurable 51Cr in three samples and 60Co in four samples taken from locations at distances of up to 430m from the accident location despite the elapse of 4 half-lives of 51Cr before measurement. Effects of air transport of the samples were considered and shown to be negligible.

  18. Determination of thorium-232 in Canadian soils by gamma-ray spectrometry via lead-212 and actinium-228, interference from uranium

    SciTech Connect

    Zikovsky, L.; Blagoeva, R.

    1994-12-31

    Thorium-232 background levels in non-cultivated Canadian soils (southern and northern Quebec and the Northwest Territories) are presented. Gamma-ray spectrometry was used to determine the activity of {sup 232}Th by measuring the activities of {sup 228}Ac and {sup 212}Pb at 37 sites. The specific activity levels ranged from 2.7 to 95.5 Bq/kg with an overall mean of 24.0 {+-} 15.4 Bq/kg. This activity generated an annual absorbed dose equivalent in air of 0.1 mSv. The activities of {sup 228}Ac and {sup 212}Pb in the soil increased with increasing depth. IT was found that uranium, via its decay product radium, can interfere with the determination of thorium in the soil.

  19. HOTSPUR: gamma ray emission from spheres pulsed with D-T neutrons. I. Calibration of improved NE213 detector assembly. II. Comparison of TART/SANDYL electron recoil spectra to experiment; preliminary results

    SciTech Connect

    Goldberg, E.; Hansen, L.F.; Komoto, T.T.; Pohl, B.A.

    1986-09-01

    The NE213 scintillator detector was modified so that the pulse height would be linear with electron energy over the full range of interest - up to 7.1 MeV. Absolute calibration was done with four different calibrated gamma sources. An average correction factor is obtained which normalizes SANDYL calculations with respect to the calibration experiments. The procedure for calculating neutron-induced gamma-ray output and electron recoil spectra is described, and experimental data from a number of spherical assemblies are given and compared to TART/SANDYL calculations. (LEW)

  20. Radon potential mapping of the Tralee-Castleisland and Cavan areas (Ireland) based on airborne gamma-ray spectrometry and geology.

    PubMed

    Appleton, J D; Doyle, E; Fenton, D; Organo, C

    2011-06-01

    The probability of homes in Ireland having high indoor radon concentrations is estimated on the basis of known in-house radon measurements averaged over 10 km × 10 km grid squares. The scope for using airborne gamma-ray spectrometer data for the Tralee-Castleisland area of county Kerry and county Cavan to predict the radon potential (RP) in two distinct areas of Ireland is evaluated in this study. Airborne data are compared statistically with in-house radon measurements in conjunction with geological and ground permeability data to establish linear regression models and produce radon potential maps. The best agreement between the percentage of dwellings exceeding the reference level (RL) for radon concentrations in Ireland (% > RL), estimated from indoor radon data, and modelled RP in the Tralee-Castleisland area is produced using models based on airborne gamma-ray spectrometry equivalent uranium (eU) and ground permeability data. Good agreement was obtained between the % > RL from indoor radon data and RP estimated from eU data in the Cavan area using terrain specific models. In both areas, RP maps derived from eU data are spatially more detailed than the published 10 km grid map. The results show the potential for using airborne radiometric data for producing RP maps.

  1. Carbon isotopic ratio analysis by gas chromatography/combustion/isotope ratio mass spectrometry for the detection of gamma-hydroxybutyric acid (GHB) administration to humans.

    PubMed

    Saudan, Christophe; Augsburger, Marc; Mangin, Patrice; Saugy, Martial

    2007-01-01

    Since GHB (gamma-hydroxybutyric acid) is naturally produced in the human body, clinical and forensic toxicologists must be able to discriminate between endogenous levels and a concentration resulting from exposure. To suggest an alternative to the use of interpretative concentration cut-offs, the detection of exogenous GHB in urine specimens was investigated by means of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). GHB was isolated from urinary matrix by successive purification on Oasis MCX and Bond Elute SAX solid-phase extraction (SPE) cartridges prior to high-performance liquid chromatography (HPLC) fractioning using an Atlantis dC18 column eluted with a mixture of formic acid and methanol. Subsequent intramolecular esterification of GHB leading to the formation of gamma-butyrolactone (GBL) was carried out to avoid introduction of additional carbon atoms for carbon isotopic ratio analysis. A precision of 0.3 per thousand was determined using this IRMS method for samples at GHB concentrations of 10 mg/L. The (13)C/(12)C ratios of GHB in samples of subjects exposed to the drug ranged from -32.1 to -42.1 per thousand, whereas the results obtained for samples containing GHB of endogenous origin at concentration levels less than 10 mg/L were in the range -23.5 to -27.0 per thousand. Therefore, these preliminary results show that a possible discrimination between endogenous and exogenous GHB can be made using carbon isotopic ratio analyses.

  2. Use of airborne gamma-ray spectrometry for environmental assessment of the rehabilitated nabarlek uranium mine, Australia.

    PubMed

    Martin, Paul; Tims, Stephen; McGill, Anthony; Ryan, Bruce; Pfitzner, Kirrilly

    2006-04-01

    This article describes an airborne gamma survey of a 7 x 5 km region around the rehabilitated Nabarlek uranium mine in northern Australia. An unusually tight line spacing (100 m) and low aircraft height (50 m) were used, enabling the survey to distinguish man-made structures such as ponds and accommodation areas, as well as creek lines. Positive correlations between airborne data and ground-based readings enabled an estimation of the average absorbed dose rate arising from terrestrial gamma radiation over large areas of the site to be derived. For the fenced minesite area this estimate was 0.31 micro Gy hr(- 1). The airborne survey data were found to be invaluable in helping to plan further ground-level investigations and showed promise as an assessment tool for rehabilitated minesites.

  3. Interpretation of Gravity and Gamma-Ray Spectrometry Data in Low Temperature Hydrothermal Systems, Southeastern Part of Fukuoka, Japan

    NASA Astrophysics Data System (ADS)

    Nishijima, Jun; Fujimitsu, Yasuhiro

    2016-12-01

    The Hakata hot springs area is located in Fukuoka City, which is in the southwestern part of Japan. Gamma-ray and gravity surveys were conducted to understand the relationship between the low-temperature hydrothermal systems and geophysical data of the area. The depth of the reservoir basement, which was derived from gravity data, gradually deepens toward the east; it includes some steep depth gradients in the Hakata hot springs area. High intensities of gamma-rays were detected around these gradients. In addition, higher hot spring temperatures and flow rates can be observed in this area. These results indicate that some part of the level of the basement where the hot springs are concentrated is a part of the Kego Fault and is similar to the fracture zone created by past activities of the fault. Moreover, these steep depth gradients act as a path for hot spring water from the deeper side of the granitic body to the surface.

  4. Effects of Fe as a physical filter on spectra of Technitium- 99m, uniformity, system volume sensitivity and spatial resolution of Philip ADAC Forte dual-head gamma camera

    NASA Astrophysics Data System (ADS)

    Sohaimi, N.; Abdullah, N.; Shah, S. I.; Zakaria, A.

    2014-11-01

    Single photon emission computed tomography (SPECT) imaging inherits some limitations, i.e., due to scattered gamma photons which degrade spatial resolution causes poor image quality. This study attempts to reduce a fraction of scattered gamma photons before reaching gamma camera detector by using Fe sheet (0.35 mm and 0.40 mm) as a physical filter. Also investigate the effects on spectra of Tc-99m, spatial resolution, system volume sensitivity and uniformity. The thickness of Fe physical filter is selected on the basis of percentage attenuation calculations of different gamma ray energies by various thicknesses of material. Data were acquired using Philip ADAC forte dual-head gamma camera without and with physical filter with LEHR collimator installed. For spectra, uniformity and system volume sensitivity, a cylindrical source tank filled with water added with Tc-99m was scanned. Uniformity and system volume sensitivity images were reconstructed with FBP method by applying Butterworth filter of order 5, cut-off frequency 0.35 cycles/cm and Chang's attenuation correction method using 0.13 cm-1 linear attenuation coefficient. Spatial resolution study was done by scanning a line source (0.8 mm inner diameter) of Tc-99m at various source-to-collimator distances in air and in scattering medium without and with physical filter. A substantial reduction in count rate from Compton and photopeak regions of Tc-99m spectra with physical filter is recorded. Improvement in spatial resolution with physical filter up to 4 cm source-to-collimator distance is obtained. System volume sensitivity was reduced and no improvement in uniformity. These thicknesses of physical filter may be tested further by scanning different planar/SPECT phantoms in Tc-99m imaging.

  5. Determination of the natural radioactivity levels in north west of Dukhan, Qatar using high-resolution gamma-ray spectrometry.

    PubMed

    Al-Sulaiti, Huda; Nasir, Tabassum; Al Mugren, K S; Alkhomashi, N; Al-Dahan, N; Al-Dosari, M; Bradley, D A; Bukhari, S; Matthews, M; Regan, P H; Santawamaitre, T; Malain, D; Habib, A

    2012-07-01

    This study is aimed at the determination of the activity concentrations of naturally occuring and technologically enhanced levels of radiation in 34 representative soil samples that have been collected from an inshore oil field area which was found to have, in a previous study, the highest observed value of 226Ra concentration among 129 soil samples. The activity concentrations of 238U and 226Ra have been inferred from gamma-ray transitions associated with their decay progenies and measured using a hyper-pure germanium detector. Details of the sample preparation and the gamma-ray spectroscopic analysis techniques are presented, together with the values of the activity concentrations associated with the naturally occuring radionuclide chains for all the samples collected from NW Dukhan. Discrete-line, gamma-ray energy transitions from spectral lines ranging in energy from ∼100 keV up to 2.6 MeV have been associated with characteristic decays of the various decay products within the 235.8U and 232Th radioactive decay chains. These data have been analyzed, under the assumption of secular equilibrium for the U and Th decay chains. Details of the sample preparation and the gamma-ray spectroscopic analysis techniques are presented. The weighted mean value of the activity concentrations of 226Ra in one of the samples was found to be around a factor of 2 higher than the values obtained in the previous study and approximately a factor of 10 higher than the accepted worldwide average value of 35 Bq/kg. The weighted mean values of the activity concentrations of 232Th and 40K were also deduced and found to be within the worldwide average values of 30 and 400 Bq/kg, respectively. Our previous study reported a value of 201.9±1.5Stat.±13Syst.Bq/kg for 226Ra in one sample and further investigation in the current work determined a measured value for 226Ra of 342.00±1.9Stat.±25Syst.Bq/kg in a sample taken from the same locality. This is significantly higher than all the other

  6. The natural radioactivity measurements in coastal sediment samples along the East Coast of Tamilnadu using gamma spectrometry technique

    SciTech Connect

    Chandramohan, J.; Tholkappian, M.; Harikrishnan, N.; Ravisankar, R.

    2015-08-28

    The natural radioactivity concentration in beach sediment samples collected from Pattipulam to Devanampattinam of East Coast of Tamilnadu have been determined by NaI (TI) gamma ray spectrometer. The specific activity concentrations range from ≤ 2.21 (BDL) to 37.02 Bq kg{sup −1} with a mean of 3.79 Bqkg{sup −1} for {sup 238}U, ≤ 2.11 (BDL) to 643.77 Bqkg{sup −1} with a mean of 49.60 Bqkg{sup −1} for {sup 232}Th and 300.34 Bqkg{sup −1} to 449.08 Bqkg{sup −1} with a mean of 360.23 Bqkg{sup −1} for {sup 40}K. The potential radiological hazards due to natural radionuclides content such as Radium Equivalent activity (Ra{sub eq}), Representative level index (RLI), External hazard index (H{sub ex}), absorbed gamma does rate (D{sub R}), and Annual effective dose rate (AEDR) are estimated to assess the radiation hazard associated with the sediments. The obtained data are compared with the recommended safety limits and international approved values. All the values are well below the recommended safety limits indicating that radiation levels do not poses any significant health hazard to the public in the area as a result of the natural radioactivity of beach sediments. This study may help the baseline data for more extensive works in the same subjects of future studies.

  7. Rapid determination of radon daughters and of artificial radionuclides in air by online gamma-ray spectrometry.

    PubMed

    Hötzl, H; Winkler, R

    1993-01-01

    For the determination of airborne radionuclide concentrations in real time, a fixed filter device was constructed which fits directly onto a germanium detector with standard nuclear electronics and a multichannel analyzer buffer connected via a data line to a personal computer for remote control and on-line spectrum evaluation. The on-line gamma-ray spectrometer was applied to the study of radon decay product concentrations in ground-level air and to the rapid detection of any contamination of the environmental air by artificial radionuclides. At Munich-Neuherberg, depending on the meterological conditions, the measured air concentrations of 214Pb, the first gamma-ray-emitting member of the 222Rn decay series, varied from about 1 to 50 Bq m-3. For the artificial radionuclides 60Co, 131I and 137Cs the detection limits were determined as a function of the varying natural radon daughter concentrations at sampling and counting times of 1 h or 1 day. For these radionuclides minimum detectable air activity concentrations of 0.3 or 0.001 Bq m-3, respectively, were obtained at low radon daughter levels. At high radon daughter levels the respective detection limits were found to be higher by a factor of only about 2.

  8. The determination of the pulse pile-up reject (PUR) counting for X and gamma ray spectrometry

    NASA Astrophysics Data System (ADS)

    Karabıdak, S. M.; Kaya, S.

    2017-02-01

    The collection the charged particles produced by the incident radiation on a detector requires a time interval. If this time interval is not sufficiently short compared with the peaking time of the amplifier, a loss in the recovered signal amplitude occurs. Another major constraint on the throughput of modern x or gamma-ray spectrometers is the time required for the subsequent the pulse processing by the electronics. Two above-mentioned limitations are cause of counting losses resulting from the dead time and the pile-up. The pulse pile-up is a common problem in x and gamma ray radiation detection systems. The pulses pile-up in spectroscopic analysis can cause significant errors. Therefore, inhibition of these pulses is a vital step. A way to reduce errors due to the pulse pile-up is a pile-up inspection circuitry (PUR). Such a circuit rejects some of the pulse pile-up. Therefore, this circuit leads to counting losses. Determination of these counting losses is an important problem. In this work, a new method is suggested for the determination of the pulse pile-up reject.

  9. Determination of total fluorine in five coal reference materials by proton-induced gamma-ray emission spectrometry.

    PubMed

    Roelandts, I; Robaye, G; Delbrouck-Habaru, J M; Weber, G

    1996-03-01

    The direct non-destructive proton-induced gamma-ray emission (PIGE) technique with a germanium detector was applied to the determination of total fluorine concentration in five coal reference materials (BCR 40, NIST 1632b, NIST 1635, SARM 20 and USGS CLB-1). Duplicate analyses were made from five randomly selected bottles of each coal. Individual data are presented and some problems (calibration, proton stopping power, effects of sample heating by the proton beam, background estimation) which were encountered during this study are discussed. Sensitivity and reproducibility of the determinations, and homogeneity of the coal samples with respect to fluorine contents by analysis of variance were investigated. The present data are also compared with the few published values for these reference samples, including other PIGE data. The use of synthetic standards and spiked samples in the present study suggested that the PIGE method was more accurate than other techniques.

  10. Software tool for xenon gamma-ray spectrometer control

    NASA Astrophysics Data System (ADS)

    Chernysheva, I. V.; Novikov, A. S.; Shustov, A. E.; Dmitrenko, V. V.; Pyae Nyein, Sone; Petrenko, D.; Ulin, S. E.; Uteshev, Z. M.; Vlasik, K. F.

    2016-02-01

    Software tool "Acquisition and processing of gamma-ray spectra" for xenon gamma-ray spectrometers control was developed. It supports the multi-windows interface. Software tool has the possibilities for acquisition of gamma-ray spectra from xenon gamma-ray detector via USB or RS-485 interfaces, directly or via TCP-IP protocol, energy calibration of gamma-ray spectra, saving gamma-ray spectra on a disk.

  11. Determination of the activity concentration levels of the artificial radionuclide137Cs in soil samples collected from Qatar using high-resolution gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Al-Sulaiti, Huda; Nasir, Tabassum; Al Mugren, K. S.; Alkhomashi, N.; Al-Dahan, N.; Al-Dosari, M.; Bradley, D. A.; Bukhari, S.; Regan, P. H.; Santawamaitre, T.; Malain, D.; Habib, A.; Al-Dosari, Hanan; Daar, Eman

    2016-09-01

    The goal of this study was to establish the first baseline measurements for radioactivity concentration of the artificial radionuclide 137Cs in soil samples collected from the Qatarian peninsula. The work focused on the determination of the activity concentrations levels of man-made radiation in 129 soil samples collected across the landscape of the State of Qatar. All the samples were collected before the most recent accident in Japan, “the 2011 Fukushima Dai-ichi nuclear power plant accident”. The activity concentrations have been measured via high-resolution gamma-ray spectrometry using a hyper-pure germanium detector situated in a low-background environment with a copper inner-plated passive lead shield. A radiological map showing the activity concentrations of 137Cs is presented in this work. The concentration wasfound to range from 0.21 to 15.41 Bq/kg. The highest activity concentration of 137Cs was observed in sample no. 26 in North of Qatar. The mean value was found to be around 2.15 ± 0.27 Bq/kg. These values lie within the expected range relative to the countries in the region. It is expected that this contamination is mainly due to the Chernobyl accident on 26 April 1986, but this conclusion cannot be confirmed because of the lack of data before this accident.

  12. LAFARA: a new underground laboratory in the French Pyrénées for ultra low-level gamma-ray spectrometry.

    PubMed

    van Beek, P; Souhaut, M; Lansard, B; Bourquin, M; Reyss, J-L; von Ballmoos, P; Jean, P

    2013-02-01

    We describe a new underground laboratory, namely LAFARA (for "LAboratoire de mesure des FAibles RAdioactivités"), that was recently created in the French Pyrénées. This laboratory is primarily designed to analyze environmental samples that display low radioactivity levels using gamma-ray spectrometry. Two high-purity germanium detectors were placed under 85 m of rock (ca. 215 m water equivalent) in the tunnel of Ferrières (Ariège, France). The background is thus reduced by a factor of ∼20 in comparison to above-ground laboratories. Both detectors are fully equipped so that the samples can be analyzed in an automatic mode without requiring permanent presence of a technician in the laboratory. Auto-samplers (twenty positions) and systems to fill liquid nitrogen automatically provide one month of autonomy to the spectrometers. The LAFARA facility allows us to develop new applications in the field of environmental sciences based on the use of natural radionuclides present at low levels in the environment. As an illustration, we present two of these applications: i) dating of marine sediments using the decay of (226)Ra in sedimentary barite (BaSO(4)), ii) determination of (227)Ac ((231)Pa) activities in marine sediment cores.

  13. Systematic influences of gamma-ray spectrometry data near the decision threshold for radioactivity measurements in the environment.

    PubMed

    Zorko, Benjamin; Korun, Matjaž; Mora Canadas, Juan Carlos; Nicoulaud-Gouin, Valerie; Chyly, Pavol; Blixt Buhr, Anna Maria; Lager, Charlotte; Aquilonius, Karin; Krajewski, Pawel

    2016-07-01

    Several methods for reporting outcomes of gamma-ray spectrometric measurements of environmental samples for dose calculations are presented and discussed. The measurement outcomes can be reported as primary measurement results, primary measurement results modified according to the quantification limit, best estimates obtained by the Bayesian posterior (ISO 11929), best estimates obtained by the probability density distribution resembling shifting, and the procedure recommended by the European Commission (EC). The annual dose is calculated from the arithmetic average using any of these five procedures. It was shown that the primary measurement results modified according to the quantification limit could lead to an underestimation of the annual dose. On the other hand the best estimates lead to an overestimation of the annual dose. The annual doses calculated from the measurement outcomes obtained according to the EC's recommended procedure, which does not cope with the uncertainties, fluctuate between an under- and overestimation, depending on the frequency of the measurement results that are larger than the limit of detection. In the extreme case, when no measurement results above the detection limit occur, the average over primary measurement results modified according to the quantification limit underestimates the average over primary measurement results for about 80%. The average over best estimates calculated according the procedure resembling shifting overestimates the average over primary measurement results for 35%, the average obtained by the Bayesian posterior for 85% and the treatment according to the EC recommendation for 89%.

  14. Measurement of natural radioactivity in building materials of Namakkal, Tamil Nadu, India using gamma-ray spectrometry.

    PubMed

    Ravisankar, R; Vanasundari, K; Chandrasekaran, A; Rajalakshmi, A; Suganya, M; Vijayagopal, P; Meenakshisundaram, V

    2012-04-01

    The natural level of radioactivity in building materials is one of the major causes of external exposure to γ-rays. The primordial radionuclides in building materials are one of the sources of radiation hazard in dwellings made of these materials. By the determination of the radioactivity level in building materials, the indoor radiological hazard to human health can be assessed. This is an important precautionary measure whenever the dose rate is found to be above the recommended limits. The aim of this work was to measure the specific activity concentration of (226)Ra, (232)Th and (40)K in commonly used building materials from Namakkal, Tamil Nadu, India, using gamma-ray spectrometer. The radiation hazard due to the total natural radioactivity in the studied building materials was estimated by different approaches. The concentrations of the natural radionuclides and the radium equivalent activity in studied samples were compared with the corresponding results of different countries. From the analysis, it is found that these materials may be safely used as construction materials and do not pose significant radiation hazards.

  15. Bioactive compounds of fourth generation gamma-irradiated Typhoniumflagelliforme Lodd. mutants based on gas chromatography-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Sianipar, N. F.; Purnamaningsih, R.; Rosaria

    2016-08-01

    Rodent tuber (Typhonium flagelliforme Lodd.) is an Indonesian anticancer medicinal plant. The natural genetic diversity of rodent tuber is low due to vegetative propagation. Plant's genetic diversity has to be increased for obtaining clones which contain a high amount of anticancer compounds. In vitro calli were irradiated with 6 Gy of gamma ray to produce in vitro mutant plantlets. Mutant plantlets were acclimated and propagated in a greenhouse. This research was aimed to identify the chemical compounds in the leaves and tubers ofthe fourth generation of rodent tuber's vegetative mutant clones (MV4) and control plantsby using GC- MS method. Leaves and tubers of MV4 each contained 2 and 5 anticancer compounds which quantities were higher compared to control plants. MV4 leaves contained 5 new anticancer compounds while its tubers contained 3 new anticancer compounds which were not found in control. The new anticancer compounds in leaves were hexadecanoic acid, stigmast-5-en-3-ol, ergost-5-en-3-ol, farnesol isomer a, and oleic acid while the new anticancer compounds in tubers were alpha tocopherol, ergost-5-en-3-ol, and beta-elemene. Rodent tuber mutant clones are very potential to be developed into anticancer drugs.

  16. Effect of small potassium-rich dykes on regional gamma-spectrometry image of a potassium-poor volcanic complex: A case from the Doupovské hory Volcanic Complex, NW Czech Republic

    NASA Astrophysics Data System (ADS)

    Zuzana, Skácelová; Vladislav, Rapprich; Bedřich, Mlčoch

    2009-10-01

    Basaltic rocks with low K, U and Th contents dominate the entire Volcanic Complex of the Doupovské hory Mts. Significant potassium anomaly exceeding 1.5 atomic wt.% of potassium over an area of 4 × 8 km and 2 atomic wt.% of potassium over an area of 2 × 6 km was defined by airborne gamma-ray spectrometry above the central part of the Doupovské hory Volcanic Complex. The following detailed field study, supported by field and laboratory gamma-spectrometry measurements and geochemical analyses of rock samples, resulted in discovery of a swarm of potassium-rich trachytic dykes. The existence of such highly-differentiated rocks in the volcanic complex was unknown till present. These dykes are commonly less than 1 m wide, but their potassium content varies between 4 and 8 atomic wt.%. Owing to this high-K composition and relative abundance of dykes, the dyke rocks significantly modify the regional pattern of gamma-spectrometry data. The potassium anomaly cannot be explained by the presence of Flurbühl intrusive body dominated by ijolites and essexites, as all these rocks are poor in K, with potassium typically not exceeding 1.5 wt.%. On the other hand, much more extensive intermediate trachybasaltic lavas with K content varying within the range 1.8-3 wt.% cause only minor or undetectable anomalies.

  17. The use of MCNP and gamma spectrometry in supporting the evaluation of NORM in Libyan oil pipeline scale

    NASA Astrophysics Data System (ADS)

    Habib, Ahmed S.; Bradley, D. A.; Regan, P. H.; Shutt, A. L.

    2010-07-01

    The accumulation of scales in production pipes is a common problem in the oil industry, reducing fluid flow and also leading to costly remedies and disposal issues. Typical materials found in such scale are sulphates and carbonates of calcium and barium, or iron sulphide. Radium arising from the uranium/thorium present in oil-bearing rock formations may replace the barium or calcium in these salts to form radium salts. This creates what is known as technologically enhanced naturally occurring radioactive material (TENORM or simply NORM). NORM is a serious environmental and health and safety issue arising from commercial oil and gas extraction operations. Whilst a good deal has been published on the characterisation and measurement of radioactive scales from offshore oil production, little information has been published regarding NORM associated with land-based facilities such as that of the Libyan oil industry. The ongoing investigation described in this paper concerns an assessment of NORM from a number of land based Libyan oil fields. A total of 27 pipe scale samples were collected from eight oil fields, from different locations in Libya. The dose rates, measured using a handheld survey meter positioned on sample surfaces, ranged from 0.1-27.3 μSv h -1. In the initial evaluations of the sample activity, use is being made of a portable HPGe based spectrometry system. To comply with the prevailing safety regulations of the University of Surrey, the samples are being counted in their original form, creating a need for correction of non-homogeneous sample geometries. To derive a detection efficiency based on the actual sample geometries, a technique has been developed using a Monte Carlo particle transport code (MCNPX). A preliminary activity determination has been performed using an HPGe portable detector system.

  18. Quantification of DNA strand breaks and abasic sites by oxime derivatization and accelerator mass spectrometry: application to gamma-radiation and peroxynitrite.

    PubMed

    Zhou, Xinfeng; Liberman, Rosa G; Skipper, Paul L; Margolin, Yelena; Tannenbaum, Steven R; Dedon, Peter C

    2005-08-01

    We report a highly sensitive method to quantify abasic sites and deoxyribose oxidation products arising in damaged DNA. The method exploits the reaction of aldehyde- and ketone-containing deoxyribose oxidation products and abasic sites with [(14)C]methoxyamine to form stable oxime derivatives, as originally described by Talpaert-Borle and Liuzzi [Reaction of apurinic/apyrimidinic sites with [(14)C]methoxyamine. A method for the quantitative assay of AP sites in DNA, Biochim. Biophys. Acta 740 (1983) 410-416]. The sensitivity of the method was dramatically improved by the application of accelerator mass spectrometry to quantify the (14)C, with a limit of detection of 1 lesion in 10(6) nucleotides in 1 microg of DNA. The method was validated using DNA containing a defined quantity of abasic sites, with a >0.95 correlation between the quantities of abasic sites and those of methoxyamine labels. The original applications of this and similar oxyamine derivatization methods have assumed that abasic sites are the only aldehyde-containing DNA damage products. However, deoxyribose oxidation produces strand breaks and abasic sites containing a variety of degradation products with aldehyde and ketone moieties. To assess the utility of methoxyamine labeling for quantifying strand breaks and abasic sites, the method was applied to plasmid DNA treated with gamma-radiation and peroxynitrite. For gamma-radiation, there was a 0.99 correlation between the quantity of methoxyamine labels and the quantity of strand breaks and abasic sites determined by a plasmid nicking assay; the abasic sites comprised less than 10% of the radiation-induced DNA damage. Studies with peroxynitrite demonstrate that the method, in conjunction with DNA repair enzymes that remove damaged bases to produce aldehydic sugar residues or abasic sites, is also applicable to quantifying nucleobase lesions in addition to strand break products. Compared to other abasic site quantification techniques, the modified

  19. Extraction of full absorption peaks in airborne gamma-spectrometry by filtering techniques coupled with a study of the derivatives. Comparison with the window method.

    PubMed

    Guillot, L

    2001-01-01

    In this paper, an adaptation of a spectral profile analysis method, currently used in high-resolution spectrometry, to airborne gamma measurements is presented. A new algorithm has been developed for extraction of full absorption peaks by studying the variations in the spectral profile of data recorded with large-volume NaI detectors (16 l) with a short sampling time (2 s). The use of digital filters, taking into consideration the characteristics of the absorption peaks, significantly reduced the counting fluctuations, making detection possible based on study of the first and second derivatives. The absorption peaks are then obtained by modelling, followed by subtraction of the Compton continuum in the detection window. Compared to the conventional stripping ratio method, spectral profile analysis offers similar performance for the natural radioelements. The 137Cs 1SD detection limit is approximately 1200 Bq/m2 in a natural background of 200 Bq/kg 40K, 33 Bq/kg 238U and 33 Bq/kg 232Th. At low energy the very high continuum leads to detection limits similar to those obtained by the windows method, but the results obtained are more reliable. In the presence of peak overlaps, however, analysis of the spectral profile alone is not sufficient to separate the peaks, and further processing is necessary. Within the framework of environmental monitoring studies, spectral profile analysis is of great interest because it does not require any assumptions about the nature of the nuclides. The calculation of the concentrations from the results obtained is simple and reliable, since only the full absorption contributions are taken into consideration. A quantitative estimate of radioactive anomalies can thus be obtained rapidly.

  20. Evaluating airborne and ground based gamma spectrometry methods for detecting particulate radioactivity in the environment: a case study of Irish Sea beaches.

    PubMed

    Cresswell, A J; Sanderson, D C W

    2012-10-15

    In several places, programmes are in place to locate and recover radioactive particles that have the potential to cause detrimental health effects in any member of the public who may encounter them. A model has been developed to evaluate the use of mobile gamma spectrometry systems within such programmes, with particular emphasis on large volume (16l) NaI(Tl) detectors mounted in low flying helicopters. This model uses a validated Monte Carlo code with assessment of local geochemistry and natural and anthropogenic background radiation concentrations and distributions. The results of the model, applied to the example of particles recovered from beaches in the vicinity of Sellafield, clearly show the ability of rapid airborne surveys conducted at 75 m ground clearance and 120 kph speeds to demonstrate the absence of sources greater than 5 MBq (137)Cs within large areas (10-20 km(2)h(-1)), and identify areas requiring further ground based investigation. Lowering ground clearance for airborne surveys to 15m whilst maintaining speeds covering 1-2 km(2) h(-1) can detect buried (137)Cs sources of 0.5MBq or greater activity. A survey design to detect 100 kBq (137)Cs sources at 10 cm depth has also been defined, requiring surveys at <15m ground clearance and <2 ms(-1) ground speed. The response of airborne systems to the Sellafield particles recovered to date has also been simulated, and the proportion of the existing radiocaesium background in the vicinity of the nuclear site has been established. Finally the rates of area coverage and sensitivities of both airborne and ground based approaches are compared, demonstrating the ability of airborne systems to increase the rate of particle recovery in a cost effective manner. The potential for equipment and methodological developments to improve performance are discussed.

  1. A Users' Guide for the Computer Program ISDMAP: Analysis and Mapping of In-Situ Gamma-Ray Spectrometry and Soil Sample Data

    SciTech Connect

    Reginatto, Marcel; Bailey, Paul; Shebell, Peter

    2000-11-30

    The computer program ISDMAP was written to analyze data from a set of in situ gamma-ray spectrometry measurements on a grid. It can also do a combined analysis of this type of data and data from soil samples. One well-known difficulty with attempting this type of analysis is that such sets of data can never provide enough information to determine a unique solution. This can be understood intuitively since a finite number of measurements cannot be sufficient to determine a continuous distribution (this observation is not restricted to data collected with the in situ technique, but holds for any set of discrete measurements, such as a series of soil samples). One can, however, restrict to particular types of solutions by requiring that they satisfy other conditions in addition to the measurements, and this is the approach taken by ISDMAP. In ISDMAP, the data are analyzed in a different manner depending on whether the data is from a characterization survey or from a post-remediation survey. The ''characterization'' option creates a map of contamination in surface soil that is smooth and fits the data. The ''post-remediation'' option creates a map with a summary of potential hot spots over a constant background level, providing a map of hot spots that might be ''hidden'' in the data. This report describes the operation of ISDMAP in sufficient detail to allow a user to prepare the necessary input files and run the program. The program requires a PC with DOS or a DOS emulator (most Windows machines have this).

  2. Gamma II

    NASA Astrophysics Data System (ADS)

    Barker, Thurburn; Castelaz, M.; Cline, J.; Owen, L.; Boehme, J.; Rottler, L.; Whitworth, C.; Clavier, D.

    2011-05-01

    GAMMA II is the Guide Star Automatic Measuring MAchine relocated from STScI to the Astronomical Photographic Data Archive (APDA) at the Pisgah Astronomical Research Institute (PARI). GAMMA II is a multi-channel laser-scanning microdensitometer that was used to measure POSS and SERC plates to create the Guide Star Catalog and the Digital Sky Survey. The microdensitometer is designed with submicron accuracy in x and y measurements using a HP 5507 laser interferometer, 15 micron sampling, and the capability to measure plates as large as 0.5-m across. GAMMA II is a vital instrument for the success of digitizing the direct, objective prism, and spectra photographic plate collections in APDA for research. We plan several targeted projects. One is a collaboration with Drs. P.D. Hemenway and R. L. Duncombe who plan to scan 1000 plates of 34 minor planets to identify systematic errors in the Fundamental System of celestial coordinates. Another is a collaboration with Dr. R. Hudec (Astronomical Institute, Academy of Sciences of the Czech Republic) who is working within the Gaia Variability Unit CU7 to digitize objective prism spectra on the Henize plates and Burrell-Schmidt plates located in APDA. These low dispersion spectral plates provide optical counterparts of celestial high-energy sources and cataclysmic variables enabling the simulation of Gaia BP/RP outputs. The astronomical community is invited to explore the more than 140,000 plates from 20 observatories now archived in APDA, and use GAMMA II. The process of relocating GAMMA to APDA, re-commissioning, and starting up the production scan programs will be described. Also, we will present planned research and future upgrades to GAMMA II.

  3. Recent Re-Measurement of Neutron and Gamma-Ray Spectra 1080 Meters from the APRD (Army Pulse Radiation Division) Critical Facility,

    DTIC Science & Technology

    1984-01-01

    spectres d𔄀missions neutroniques et de rayons gamma. On a compar6 les risultats de ces mesures A plusieurs calculs rcents effectu~s par d’autres...les neutrons et le- rayons gamma; on observe toutefois d’importantes differences spectrales. A - faible altitude, les spectres neutroniques son i6g...measurements were performed by both groups, using a variety of tissue-equivalent ion-chambers, Geiger-M(.ller counters and sulphur activation (n,p). In 1980

  4. EML HASL-300 Method Ga-01-R: Gamma Radioassay

    EPA Pesticide Factsheets

    This method uses gamma spectrometry for measurement of gamma photons emitted from radionuclides. Samples are placed into a standard geometry for gamma counting, typically using an high purity Germanium [HP(Ge)] detector.

  5. 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.

  6. Experimental-Series Parameters for the Decay of Multigroup Beta and Gamma Spectra from 0.1 to 1000 Seconds After a Fission Burst

    DTIC Science & Technology

    1978-11-01

    applying a known neutron - flux history to multigroup cross sections taken from ENDF/B. In the present application to essentially instantaneous fission we have...AFWL-TR-78-4 AFWL-TR- (2EYEL 78-4 EXPERIMENTAL SERIES PARAMETERS FOR THE DECAY OF MULTIGROUP BETA AND GAMMA SSPECTRA FROM 0.1 TO 1000 SECONDS AFTER A...1.) November 1978 t LLJ - Final Report Approved for public release; distribution unlimited. -D DC B AIR FORCE WEAPONS LABORATORY Air Force Systems

  7. Ion Mobility Mass Spectrometry for Ion Recovery and Clean-Up of MS and MS/MS Spectra Obtained from Low Abundance Viral Samples

    NASA Astrophysics Data System (ADS)

    Harvey, David J.; Crispin, Max; Bonomelli, Camille; Scrivens, Jim H.

    2015-07-01

    Many samples of complex mixtures of N-glycans released from small amounts of material, such as glycoproteins from viruses, present problems for mass spectrometric analysis because of the presence of contaminating material that is difficult to remove by conventional methods without involving sample loss. This study describes the use of ion mobility for extraction of glycan profiles from such samples and for obtaining clean CID spectra when targeted m/z values capture additional ions from those of the target compound. N-glycans were released enzymatically from within SDS-PAGE gels, from the representative recombinant glycoprotein, gp120 of the human immunodeficiency virus, and examined by direct infusion electrospray in negative mode followed by ion mobility with a Waters Synapt G2 mass spectrometer (Waters MS-Technologies, Manchester, UK). Clean profiles of singly, doubly, and triply charged N-glycans were obtained from samples in cases where the raw electrospray spectra displayed only a few glycan ions as the result of low sample concentration or the presence of contamination. Ion mobility also enabled uncontaminated CID spectra to be obtained from glycans when their molecular ions displayed coincidence with ions from fragments or multiply charged ions with similar m/z values. This technique proved to be invaluable for removing extraneous ions from many CID spectra. The presence of such ions often produces spectra that are difficult to interpret. Most CID spectra, even those from abundant glycan constituents, benefited from such clean-up, showing that the extra dimension provided by ion mobility was invaluable for studies of this type.

  8. Progress in numerical modelling of the Cl influence on gamma-ray spectra from an n-gamma logging tool, by using the improved ENDF data for radiative capture.

    PubMed

    Cywicka-Jakiel, Teresa

    2007-06-01

    Quality of the numerical modelling (MCNP code) of the spectrometric neutron-gamma benchmark experiment, performed at the Polish Calibration Station BGW in Zielona Gora for quantification of the main rock elements: Si, Ca, Fe and H, is considered. Elemental concentrations obtained from the measurements and simulations, for the rock models with water-filled boreholes, are in good agreement. For chlorine present in the borehole, the quality of the numerical reproducibility of the measured elemental concentrations depends on the cross section library used for the Cl(n,gamma)Cl reaction. The standard evaluated nuclear data library ENDF/B-VI Release 2 supplies imperfect data for photon production from thermal neutron capture in Cl. The improved cross sections for Cl(n,gamma)Cl are included in the ENDF/B-VI Release 8 library. Superiority of this new compilation over the previous one is shown in the paper. The accuracies for the Si, Ca and Fe determination have been improved by about 36%, 19.9% and 21.4%, respectively, when the ENDF/B-VI Release 8 library has been used for Cl.

  9. 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

  10. Spectra and angular distributions of atmospheric gamma rays from 0.3 to 10 MeV at lambda = 40 deg

    NASA Technical Reports Server (NTRS)

    Ling, J. C.; Gruber, D. E.

    1977-01-01

    Measurements of the spectral and angular distributions of atmospheric gamma sq cm rays in the energy range 0.3-10 MeV over Palestine, Texas, at residual depths of 2.5 and 70 g/sq cm are reported. In confirmation of the general features of a model prediction, the measurements show at 2.5 g/sq cm upward moving fluxes greater than the downward moving fluxes, the effect increasing with energy, and approximate isotropy at 70 g/sq cm. Numerous characteristic gamma-ray lines were observed, most prominently at 0.511, 1.6, 2.3, 4.4, and 6.1 MeV. Their intensities were also compared with model predictions. Observations were made with an actively shielded scintillator counter with two detectors, one of aperture 50 deg FWHM and the other of 120 deg FWHM. Above 1 MeV, contributions to the counting rate from photons penetrating the shield annulus and from neutron interactions were large; they were studied by means of a Monte Carlo code and are extensively discussed.

  11. Radiation metabolomics. 3. Biomarker discovery in the urine of gamma-irradiated rats using a simplified metabolomics protocol of gas chromatography-mass spectrometry combined with random forests machine learning algorithm.

    PubMed

    Lanz, Christian; Patterson, Andrew D; Slavík, Josef; Krausz, Kristopher W; Ledermann, Monika; Gonzalez, Frank J; Idle, Jeffrey R

    2009-08-01

    Abstract Radiation metabolomics employing mass spectral technologies represents a plausible means of high-throughput minimally invasive radiation biodosimetry. A simplified metabolomics protocol is described that employs ubiquitous gas chromatography-mass spectrometry and open source software including random forests machine learning algorithm to uncover latent biomarkers of 3 Gy gamma radiation in rats. Urine was collected from six male Wistar rats and six sham-irradiated controls for 7 days, 4 prior to irradiation and 3 after irradiation. Water and food consumption, urine volume, body weight, and sodium, potassium, calcium, chloride, phosphate and urea excretion showed major effects from exposure to gamma radiation. The metabolomics protocol uncovered several urinary metabolites that were significantly up-regulated (glyoxylate, threonate, thymine, uracil, p-cresol) and down-regulated (citrate, 2-oxoglutarate, adipate, pimelate, suberate, azelaate) as a result of radiation exposure. Thymine and uracil were shown to derive largely from thymidine and 2'-deoxyuridine, which are known radiation biomarkers in the mouse. The radiation metabolomic phenotype in rats appeared to derive from oxidative stress and effects on kidney function. Gas chromatography-mass spectrometry is a promising platform on which to develop the field of radiation metabolomics further and to assist in the design of instrumentation for use in detecting biological consequences of environmental radiation release.

  12. Purification of pharmaceutical preparations using thin-layer chromatography to obtain mass spectra with Direct Analysis in Real Time and accurate mass spectrometry.

    PubMed

    Wood, Jessica L; Steiner, Robert R

    2011-06-01

    Forensic analysis of pharmaceutical preparations requires a comparative analysis with a standard of the suspected drug in order to identify the active ingredient. Purchasing analytical standards can be expensive or unattainable from the drug manufacturers. Direct Analysis in Real Time (DART™) is a novel, ambient ionization technique, typically coupled with a JEOL AccuTOF™ (accurate mass) mass spectrometer. While a fast and easy technique to perform, a drawback of using DART™ is the lack of component separation of mixtures prior to ionization. Various in-house pharmaceutical preparations were purified using thin-layer chromatography (TLC) and mass spectra were subsequently obtained using the AccuTOF™- DART™ technique. Utilizing TLC prior to sample introduction provides a simple, low-cost solution to acquiring mass spectra of the purified preparation. Each spectrum was compared against an in-house molecular formula list to confirm the accurate mass elemental compositions. Spectra of purified ingredients of known pharmaceuticals were added to an in-house library for use as comparators for casework samples. Resolving isomers from one another can be accomplished using collision-induced dissociation after ionization. Challenges arose when the pharmaceutical preparation required an optimized TLC solvent to achieve proper separation and purity of the standard. Purified spectra were obtained for 91 preparations and included in an in-house drug standard library. Primary standards would only need to be purchased when pharmaceutical preparations not previously encountered are submitted for comparative analysis. TLC prior to DART™ analysis demonstrates a time efficient and cost saving technique for the forensic drug analysis community. Copyright © 2011 John Wiley & Sons, Ltd.

  13. Toward prompt gamma spectrometry for monitoring boron distributions during extra corporal treatment of liver metastases by boron neutron capture therapy: a Monte Carlo simulation study.

    PubMed

    Khelifi, R; Nievaart, V A; Bode, P; Moss, R L; Krijger, G C

    2009-07-01

    A Monte Carlo calculation was carried out for boron neutron capture therapy (BNCT) of extra corporal liver phantom. The present paper describes the basis for a subsequent clinical application of the prompt gamma spectroscopy set-up aimed at in vivo monitoring of boron distribution. MCNP code was used first to validate the homogeneity in thermal neutron field in the liver phantom and simulate the gamma ray detection system (collimator and detector) in the treatment room. The gamma ray of 478 keV emitted by boron in small specific region can be detected and a mathematical formalism was used for the tomography image reconstruction.

  14. Neutron spectrometry for UF6 enrichment verification in storage cylinders

    DOE PAGES

    Mengesha, Wondwosen; Kiff, Scott D.

    2015-01-29

    Verification of declared UF6 enrichment and mass in storage cylinders is of great interest in nuclear material nonproliferation. Nondestructive assay (NDA) techniques are commonly used for safeguards inspections to ensure accountancy of declared nuclear materials. Common NDA techniques used include gamma-ray spectrometry and both passive and active neutron measurements. In the present study, neutron spectrometry was investigated for verification of UF6 enrichment in 30B storage cylinders based on an unattended and passive measurement approach. MCNP5 and Geant4 simulated neutron spectra, for selected UF6 enrichments and filling profiles, were used in the investigation. The simulated neutron spectra were analyzed using principalmore » component analysis (PCA). The PCA technique is a well-established technique and has a wide area of application including feature analysis, outlier detection, and gamma-ray spectral analysis. Results obtained demonstrate that neutron spectrometry supported by spectral feature analysis has potential for assaying UF6 enrichment in storage cylinders. The results from the present study also showed that difficulties associated with the UF6 filling profile and observed in other unattended passive neutron measurements can possibly be overcome using the approach presented.« less

  15. Anatomy and histophysiology of the periosteum: quantification of the periosteal blood supply to the adjacent bone with 85Sr and gamma spectrometry.

    PubMed

    Chanavaz, M

    1995-01-01

    The periosteum or periosteal membrane is a continuous composite fibroelastic covering membrane of the bone to which it is intimately linked. Although the bone cortex is the main beneficiary of the principal anatomical and physiological functions of the periosteal membrane, the behavior of the entire bone remains closely influenced by periosteal activity. These principal functions are related to the cortical blood supply, osteogenesis, and muscle and ligament attachments. Through its elastic and contractile nature, it participates in the maintenance of bone shape, and plays an important role in metabolic ionic exchange and physiologic distribution of electro-chemical potential differences across its membranous structure. It has also been suggested that the periosteum may have its own specific proprioceptive property. This paper presents a study of the anatomy and histophysiology of the periosteum, and discusses in detail its main functions of cortical blood supply and osteogenesis. It also presents the third intermediary report on a current study of the quantification of cortical vascularization of femoral bone via the periosteum, using an isotonic salt solution containing 85 Strontium. The afferent-efferent (arterio-venous) flows of this solution in the thigh vascular system of guinea pigs were measured by gamma spectrometry after a series of selective macro- and micro-injections of radioactive salt into the femoral arterial system was carried out. Each vascular territory was meticulously selected and the injections were made according to size, starting with the larger vessels, with or without ligatures of neighboring vessels, going progressively to smaller and smaller vessels with diameters not exceeding 100 microns. The principal technical difficulty at this stage of experimentation was related to the identifying and acquiring of appropriate microcatheters. The study also includes a series of measurements after blockage of the transmuscular blood flow and the

  16. The Visible Photodissociation Spectra of the Molecular Ions of Negative Carbonate, Negative Ozone, and Positive Ozone by Triple Quadrupole Mass Spectrometry.

    NASA Astrophysics Data System (ADS)

    Hiller, Joseph Francis, Jr.

    A modified version of the triple quadrupole photodissociation mass spectrometer utilizing a chemical ionization ion source and a nitrogen pumped tunable dye laser is described. The visible photodissociation spectra are reported for the processes. CO(,3)('-) + h(nu) (--->) O('-) + CO(,2). O(,3)('-) + h(nu) (--->) O('-) + O(,2). (--->) O(,2)('-) + O. O(,3)('+) + h(nu) (--->) O('+) + O(,2). (--->) O(,2)('+) + O. as absolute cross sections as functions of photon energy. Sequential two photon processes and excited state ion/neutral. reactions are observed directly for the visible excitation of CO(,3)('-). Rate constants and absolute cross sections are presented for these. reactions, and for the inferred fluorescent and relaxation processes. as well. Thresholds are located for three of these dissociations as. D(CO(,2)-O('-)) 2.258 (+OR-) 0.008 eV. D(O-O(,2)('-)) 2.410 (+OR-) 0.010 eV. D(O(,2)-O('+)) 1.860 (+OR-) 0.005 eV. Excited states of O(,3)('-) are identified, and vibrational analyses are included for the O(,3)('-) and O(,3)('+) spectra.

  17. Ion Mobility Mass Spectrometry for Extracting Spectra of N-Glycans Directly from Incubation Mixtures Following Glycan Release: Application to Glycans from Engineered Glycoforms of Intact, Folded HIV gp120

    NASA Astrophysics Data System (ADS)

    Harvey, David J.; Sobott, Frank; Crispin, Max; Wrobel, Antoni; Bonomelli, Camille; Vasiljevic, Snezana; Scanlan, Christopher N.; Scarff, Charlotte A.; Thalassinos, Konstantinos; Scrivens, James H.

    2011-03-01

    The analysis of glycosylation from native biological sources is often frustrated by the low abundances of available material. Here, ion mobility combined with electrospray ionization mass spectrometry have been used to extract the spectra of N-glycans released with PNGase F from a serial titration of recombinantly expressed envelope glycoprotein, gp120, from the human immunodeficiency virus (HIV). Analysis was also performed on gp120 expressed in the α-mannosidase inhibitor, and in a matched mammalian cell line deficient in GlcNAc transferase I. Without ion mobility separation, ESI spectra frequently contained no observable ions from the glycans whereas ions from other compounds such as detergents and residual buffer salts were abundant. After ion mobility separation on a Waters T-wave ion mobility mass spectrometer, the N-glycans fell into a unique region of the ion mobility/ m/z plot allowing their profiles to be extracted with good signal:noise ratios. This method allowed N-glycan profiles to be extracted from crude incubation mixtures with no clean-up even in the presence of surfactants such as NP40. Furthermore, this technique allowed clear profiles to be obtained from sub-microgram amounts of glycoprotein. Glycan profiles were similar to those generated by MALDI-TOF MS although they were more susceptible to double charging and fragmentation. Structural analysis could be accomplished by MS/MS experiments in either positive or negative ion mode but negative ion mode gave the most informative spectra and provided a reliable approach to the analysis of glycans from small amounts of glycoprotein.

  18. Formation of the 0.511.-MeV line in solar flares. [statistical mechanics of line spectra for gamma rays

    NASA Technical Reports Server (NTRS)

    Crannell, C. J.; Joyce, G.; Ramaty, R.; Werntz, C.

    1976-01-01

    The gamma-ray line produced at 0.51-MeV was studied and is shown to be the result of either of free annihilation of positrons with electrons or of the decay of positronium by 2-photon emission. Positron annihilation from the bound state of positronium may also proceed by 3-photon emission, resulting in a continuum with energies up to 0.51-MeV. Accurate calculations of the rates of free annihilation and positronium formation in a solar-flare plasma are presented. Estimates of the positronium-formulation rates by charge exchange and the rates of dissociation and quenching are also considered. The temperature and density dependence of the ratio of 3-photon to 2-photon emission was obtained. It is shown that when the ratio of free electrons to neutral atoms in the plasma is approximately unity or greater, the Doppler width of the 0.51-MeV line is a function of the temperature of the annihilation region. For the small ion densities characteristics of the photosphere, the width is predominantly a function of the density.

  19. Use of a TLD-based multisphere spectrometry system to measure the neutron spectra around a not-self-shielded PET cyclotron: Preliminary results.

    PubMed

    Guimarães, A M; Lacerda, M A S; Santos, J A L; Maletta, P G M; Rodrigues, S L M; Andrade, R S; Vilela, E C; da Silva, T A

    2012-12-01

    In the present work, we utilized the BSS system with TLD-600 and TLD-700 to measure the neutron spectra around the GE-PETtrace 8 cyclotron of the Development Centre of Nuclear Technology (CDTN/CNEN) in Belo Horizonte, Brazil. The cyclotron is capable of accelerating protons up to 16.5 MeV, to production of fluorine-18. Four points inside the bunker of the cyclotron were studied. Two points in front of the primary radiation beam and other two opposed to the primary radiation beam. The measurements were unfolded with the BUMS and the NSDUAZ computer codes. The dosimetric quantities obtained were in agreement with the other published data and were coherent with the expected from theoretical estimates obtained from source term informed by the manufacturer of the cyclotron.

  20. Background correction in separation techniques hyphenated to high-resolution mass spectrometry - Thorough correction with MS scans recorded as profile spectra.

    PubMed

    Erny, Guillaume L; Acunha, Tanize; Simó, Carolina; Cifuentes, Alejandro; Alves, Arminda

    2017-03-01

    Separation techniques hyphenated with high-resolution mass spectrometry have been a true revolution in analytical separation techniques. Such instruments not only provide unmatched resolution, but they also allow measuring the peaks accurate masses that permit identifying monoisotopic formulae. However, data files can be large, with a major contribution from background noise and background ions. Such unnecessary contribution to the overall signal can hide important features as well as decrease the accuracy of the centroid determination, especially with minor features. Thus, noise and baseline correction can be a valuable pre-processing step. The methodology that is described here, unlike any other approach, is used to correct the original dataset with the MS scans recorded as profiles spectrum. Using urine metabolic studies as examples, we demonstrate that this thorough correction reduces the data complexity by more than 90%. Such correction not only permits an improved visualisation of secondary peaks in the chromatographic domain, but it also facilitates the complete assignment of each MS scan which is invaluable to detect possible comigration/coeluting species.

  1. Development activities of a CdTe/CdZnTe pixel detector for gamma-ray spectrometry with imaging and polarimetry capability in astrophysics

    NASA Astrophysics Data System (ADS)

    Gálvez, J. L.; Hernanz, M.; Álvarez, J. M.; Álvarez, L.; La Torre, M.; Caroli, E.; Lozano, M.; Pellegrini, G.; Ullán, M.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

    2013-05-01

    In the last few years we have been working on feasibility studies of future instruments in the gamma-ray range, from several keV up to a few MeV, in collaboration with other research institutes. High sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators, e.g., Supernovae, Classical Novae, Supernova Remnants (SNRs), Gamma-Ray Bursts (GRBs), Pulsars, Active Galactic Nuclei (AGN).Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CdZnTe) are very attractive materials for gamma-ray detection, since they have already demonstrated their great performance onboard current space missions, such as IBIS/INTEGRAL and BAT/SWIFT, and future projects like ASIM onboard the ISS. However, the energy coverage of these instruments is limited up to a few hundred keV, and there has not been yet a dedicated instrument for polarimetry.Our research and development activities aim to study a gamma-ray imaging spectrometer in the MeV range based on CdTe detectors, suited either for the focal plane of a focusing mission or as a calorimeter for a Compton camera. In addition, our undergoing detector design is proposed as the baseline for the payload of a balloon-borne experiment dedicated to hard X- and soft gamma-ray polarimetry, currently under study and called CμSP (CZT μ-Spectrometer Polarimeter). Other research institutes such as INAF-IASF, DTU Space, LIP, INEM/CNR, CEA, are involved in this proposal. We will report on the main features of the prototype we are developing at the Institute of Space Sciences, a gamma-ray detector with imaging and polarimetry capabilities in order to fulfil the combined requirement of high detection efficiency with good spatial and energy resolution driven by the science.

  2. A New Method for the Reconstruction of Very-High-Energy Gamma-Ray Spectra and Application to Galactic Cosmic-Ray Accelerators

    NASA Astrophysics Data System (ADS)

    Fernandes, Milton Virgílio

    2014-06-01

    In this thesis, high-energy (HE; E > 0.1 GeV) and very-high-energy (VHE; E > 0.1 TeV) γ-ray data were investigated to probe Galactic stellar clusters (SCs) and star-forming regions (SFRs) as sites of hadronic Galactic cosmic-ray (GCR) acceleration. In principle, massive SCs and SFRs could accelerate GCRs at the shock front of the collective SC wind fed by the individual high-mass stars. The subsequently produced VHE γ rays would be measured with imaging air-Cherenkov telescopes (IACTs). A couple of the Galactic VHE γ-ray sources, including those potentially produced by SCs, fill a large fraction of the field-of-view (FoV) and require additional observations of source-free regions to determine the dominant background for a spectral reconstruction. A new method of reconstructing spectra for such extended sources without the need of further observations is developed: the Template Background Spectrum (TBS). This methods is based on a method to generate skymaps, which determines background in parameter space. The idea is the creation of a look-up of the background normalisation in energy, zenith angle, and angular separation and to account for possible systematics. The results obtained with TBS and state-of-the-art background-estimation methods on H.E.S.S. data are in good agreement. With TBS even those sources could be reconstructed that normally would need further observations. Therefore, TBS is the third method to reconstruct VHE γ-ray spectra, but the first one to not need additional observations in the analysis of extended sources. The discovery of the largest VHE γ-ray source HESS J1646-458 (2.2° in size) towards the SC Westerlund 1 (Wd 1) can be plausibly explained by the SC-wind scenario. But owing to its size, other alternative counterparts to the TeV emission (pulsar, binary system, magnetar) were found in the FoV. Therefore, an association of HESS J1646-458 with the SC is favoured, but cannot be confirmed. The SC Pismis 22 is located in the centre of

  3. Topics in gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1986-01-01

    Observations of gamma rays from solar flares, gamma ray bursts, the Galactic center, galactic nucleosynthesis, SS433, and Cygnus X-3, and their effects on astrophysical problems are discussed. It is observed that gamma ray spectra from solar flares are applicable to the study of particle acceleration and confinement and the determination of chemical abundances in the solar atmosphere. The gamma ray lines from the compact galactic object SS433 are utilized to examine the acceleration of jets, and analysis of the gamma ray lines of Cygnus X-3 reveal that particles can be accelerated in compact sources to ultrahigh energies.

  4. The GAMMA-400 gamma-ray telescope angular resolution

    NASA Astrophysics Data System (ADS)

    Kheymits, Maxim; Leonov, Alexey

    The measurements of gamma-ray fluxes and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV, which will be realized by the specially designed GAMMA-400 gamma-ray telescope, concern with the following broad range of science topics. Search for signatures of dark matter, surveying the celestial sphere in order to study point and extended sources of gamma-rays, measuring the energy spectra of Galactic and extragalactic diffuse gamma-ray emission, study of gamma-ray bursts and gamma-ray emission from the Sun. To clarify these scientific problems with the new experimental data the GAMMA-400 gamma-ray telescope possesses unique physical characteristics comparing with previous and present experiments. For gamma-ray energies more than 100 GeV GAMMA-400 provides the energy resolution nearby 1% and angular resolution better than 0.02 deg. The methods, developed to reconstruct the direction of incident gamma photon, are presented in this paper. The main point concerns with the space topology of high energy gamma photon interaction in the matter of GAMMA-400. Multiple secondary particles, generated inside gamma-ray telescope, produce significant problems to restore the direction of initial gamma photon. Also back-splash particles, i.e., charged particles and gamma photons generated in calorimeter and moved upward, mask the initial tracks of electron/positron pair from conversion of incident gamma photon. The processed methods allow us to reconstruct the direction of electromagnetic shower axis and extract the electron/positron trace. As a result, the direction of incident gamma photon with the energy of 100 GeV is calculated with an accuracy of more than 0.02 deg.

  5. Antagonistic properties of a natural product - Bicuculline with the gamma-aminobutyric acid receptor: Studied through electrostatic potential mapping, electronic and vibrational spectra using ab initio and density functional theory

    NASA Astrophysics Data System (ADS)

    Srivastava, Anubha; Tandon, Poonam; Jain, Sudha; Asthana, B. P.

    2011-12-01

    (+)-Bicuculline (hereinafter referred to as bicuculline), a phthalide isoquinoline alkaloid is of current interest as an antagonist of gamma-aminobutyric acid (GABA). Its inhibitor properties have been studied through molecular electrostatic potential (MEP) mapping of this molecule and GABA receptor. The hot site on the potential surface of bicuculline, which is also isosteric with GABA receptor, has been used to interpret the inhibitor property. A systematic quantum chemical study of the possible conformations, their relative stabilities, FT-Raman, FT-IR and UV-vis spectroscopic analysis of bicuculline has been reported. The optimized geometries, wavenumber and intensity of the vibrational bands of all the conformers of bicuculline have been calculated using ab initio Hartree-Fock (HF) and density functional theory (DFT) employing B3LYP functional and 6-311G(d,p) basis set. Mulliken atomic charges, HOMO-LUMO gap Δ E, ionization potential, dipole moments and total energy have also been obtained for the optimized geometries of both the molecules. TD-DFT method is used to calculate the electronic absorption parameters in gas phase as well as in solvent environment using integral equation formalism-polarizable continuum model (IEF-PCM) employing 6-31G basis set and the results thus obtained are compared with the UV absorption spectra. The combination of experimental and calculated results provides an insight into the structural and vibrational spectroscopic properties of bicuculline.

  6. Large-scale radon hazard evaluation in the Oslofjord region of Norway utilizing indoor radon concentrations, airborne gamma ray spectrometry and geological mapping.

    PubMed

    Smethurst, Mark Andrew; Strand, Terje; Sundal, Aud Venke; Rudjord, Anne Liv

    2008-12-15

    We test whether airborne gamma ray spectrometer measurements can be used to estimate levels of radon hazard in the Oslofjord region of Norway. We compile 43,000 line kilometres of gamma ray spectrometer data from 8 airborne surveys covering 10,000 km2 and compare them with 6326 indoor radon measurements. We find a clear spatial correlation between areas with elevated concentrations of uranium daughters in the near surface of the ground and regions with high incidence of elevated radon concentrations in dwellings. This correlation permits cautious use of the airborne data in radon hazard evaluation where direct measurements of indoor radon concentrations are few or absent. In radon hazard evaluation there is a natural synergy between the mapping of radon in indoor air, bedrock and drift geology mapping and airborne gamma ray surveying. We produce radon hazard forecast maps for the Oslofjord region based on a spatial union of hazard indicators from all four of these data sources. Indication of elevated radon hazard in any one of the data sets leads to the classification of a region as having an elevated radon hazard potential. This approach is inclusive in nature and we find that the majority of actual radon hazards lie in the assumed elevated risk regions.

  7. Gamma spectroscopy of environmental samples

    NASA Astrophysics Data System (ADS)

    Siegel, P. B.

    2013-05-01

    We describe experiments for the undergraduate laboratory that use a high-resolution gamma detector to measure radiation in environmental samples. The experiments are designed to instruct the students in the quantitative analysis of gamma spectra and secular equilibrium. Experiments include the radioactive dating of Brazil nuts, determining radioisotope concentrations in natural samples, and measurement of the 235U abundance in uranium rich rocks.

  8. Gamma-ray activity in the volcanic islands of the Southern Tyrrhenian Sea.

    PubMed

    Chiozzi, P; Pasquale, V; Verdoya, M; Minato, S

    2003-01-01

    Field gamma-ray spectrometry was used for the quantitative assessment of U, Th and K of rocks of Stromboli, Salina, Filicuidi and Panarea (Aeolian arc of the Southern Tyrrhenian, Italy). The air absorbed dose rate was calculated from radioelement concentrations. For some rocks the gamma-ray spectra were analysed with the three photo-peak methods and the response matrix method, which converts the pulse height distribution into the true incident gamma-ray energy spectrum. The higher values of U (8.2-9.8 ppm) coincide with higher Th (20.6-27.8 ppm) concentrations associated with rocks of shoshonitic composition. The spatial variation in radioelement concentration reflects the geochemical differences among the rocks. The air absorbed dose rate varies from 25 to 215 nGy h(-1). The highest values correspond to outcrops located in the eastern part of Stromboli, where the annual effective dose equivalent reaches a value of 264 microSv.

  9. Gamma ray spectroscopy in astrophysics. [conferences

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  10. Nuclear gamma rays from energetic particle interactions

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Kozlovsky, B.; Lingenfelter, R. E.

    1978-01-01

    Gamma ray line emission from nuclear deexcitation following energetic particle reactions is evaluated. The compiled nuclear data and the calculated gamma ray spectra and intensities can be used for the study of astrophysical sites which contain large fluxes of energetic protons and nuclei. A detailed evaluation of gamma ray line production in the interstellar medium is made.

  11. Compton Gamma Ray Observatory Guest Investigator Program

    NASA Technical Reports Server (NTRS)

    Lingenfelter, Richard E.

    1997-01-01

    This paper presents a final report for the Compton Gamma Ray Observatory Guest Investigator Program from 06/01/91-07/31/97. The topics include: 1) Solar Flare Neutron Spectra and Accelerated Ions; 2) Gamma Ray Lines From The Orion Complex; 3) Implications of Nuclear Line Emission From The Orion Complex; 4) Possible Sites of Nuclear Line Emission From Massive OB Associations; 5) Gamma-Ray Burst Repitition and BATSE Position Uncertainties; 6) Effects of Compton Scattering on BATSE Gamma-Ray Burst Spectra; and 7) Selection Biases on the Spectral and Temporal Distribution of Gamma Ray Bursts.

  12. Determining initial enrichment, burnup, and cooling time of pressurized-water reactor spent fuel assemblies by analyzing passive gamma spectra measured at the Clab interim-fuel storage facility in Sweden

    SciTech Connect

    Favalli, Andrea; Vo, D.; Grogan, Brandon R.; Jansson, Peter; Liljenfeldt, Henrik; Mozin, Vladimir; Schwalbach, P.; Sjoland, A.; Tobin, Stephen J.; Trellue, Holly; Vaccaro, S.

    2016-02-26

    The purpose of the Next Generation Safeguards Initiative (NGSI)–Spent Fuel (SF) project is to strengthen the technical toolkit of safeguards inspectors and/or other interested parties. The NGSI–SF team is working to achieve the following technical goals more easily and efficiently than in the past using nondestructive assay measurements of spent fuel assemblies: (1) verify the initial enrichment, burnup, and cooling time of facility declaration; (2) detect the diversion or replacement of pins; (3) estimate the plutonium mass [which is also a function of the variables in (1)]; (4) estimate the decay heat; and (5) determine the reactivity of spent fuel assemblies. Since August 2013, a set of measurement campaigns has been conducted at the Central Interim Storage Facility for Spent Nuclear Fuel (Clab), in collaboration with Swedish Nuclear Fuel and Waste Management Company (SKB). One purpose of the measurement campaigns was to acquire passive gamma spectra with high-purity germanium and lanthanum bromide scintillation detectors from Pressurized Water Reactor and Boiling Water Reactor spent fuel assemblies. The absolute 137Cs count rate and the 154Eu/137Cs, 134Cs/137Cs, 106Ru/137Cs, and 144Ce/137Cs isotopic ratios were extracted; these values were used to construct corresponding model functions (which describe each measured quantity’s behavior over various combinations of burnup, cooling time, and initial enrichment) and then were used to determine those same quantities in each measured spent fuel assembly. Furthermore, the results obtained in comparison with the operator declared values, as well as the methodology developed, are discussed in detail in the paper.

  13. Determining initial enrichment, burnup, and cooling time of pressurized-water-reactor spent fuel assemblies by analyzing passive gamma spectra measured at the Clab interim-fuel storage facility in Sweden

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    The purpose of the Next Generation Safeguards Initiative (NGSI)-Spent Fuel (SF) project is to strengthen the technical toolkit of safeguards inspectors and/or other interested parties. The NGSI-SF team is working to achieve the following technical goals more easily and efficiently than in the past using nondestructive assay measurements of spent fuel assemblies: (1) verify the initial enrichment, burnup, and cooling time of facility declaration; (2) detect the diversion or replacement of pins; (3) estimate the plutonium mass [which is also a function of the variables in (1)]; (4) estimate the decay heat; and (5) determine the reactivity of spent fuel assemblies. Since August 2013, a set of measurement campaigns has been conducted at the Central Interim Storage Facility for Spent Nuclear Fuel (Clab), in collaboration with Swedish Nuclear Fuel and Waste Management Company (SKB). One purpose of the measurement campaigns was to acquire passive gamma spectra with high-purity germanium and lanthanum bromide scintillation detectors from Pressurized Water Reactor and Boiling Water Reactor spent fuel assemblies. The absolute 137Cs count rate and the 154Eu/137Cs, 134Cs/137Cs, 106Ru/137Cs, and 144Ce/137Cs isotopic ratios were extracted; these values were used to construct corresponding model functions (which describe each measured quantity's behavior over various combinations of burnup, cooling time, and initial enrichment) and then were used to determine those same quantities in each measured spent fuel assembly. The results obtained in comparison with the operator declared values, as well as the methodology developed, are discussed in detail in the paper.

  14. Determining initial enrichment, burnup, and cooling time of pressurized-water reactor spent fuel assemblies by analyzing passive gamma spectra measured at the Clab interim-fuel storage facility in Sweden

    DOE PAGES

    Favalli, Andrea; Vo, D.; Grogan, Brandon R.; ...

    2016-02-26

    The purpose of the Next Generation Safeguards Initiative (NGSI)–Spent Fuel (SF) project is to strengthen the technical toolkit of safeguards inspectors and/or other interested parties. The NGSI–SF team is working to achieve the following technical goals more easily and efficiently than in the past using nondestructive assay measurements of spent fuel assemblies: (1) verify the initial enrichment, burnup, and cooling time of facility declaration; (2) detect the diversion or replacement of pins; (3) estimate the plutonium mass [which is also a function of the variables in (1)]; (4) estimate the decay heat; and (5) determine the reactivity of spent fuelmore » assemblies. Since August 2013, a set of measurement campaigns has been conducted at the Central Interim Storage Facility for Spent Nuclear Fuel (Clab), in collaboration with Swedish Nuclear Fuel and Waste Management Company (SKB). One purpose of the measurement campaigns was to acquire passive gamma spectra with high-purity germanium and lanthanum bromide scintillation detectors from Pressurized Water Reactor and Boiling Water Reactor spent fuel assemblies. The absolute 137Cs count rate and the 154Eu/137Cs, 134Cs/137Cs, 106Ru/137Cs, and 144Ce/137Cs isotopic ratios were extracted; these values were used to construct corresponding model functions (which describe each measured quantity’s behavior over various combinations of burnup, cooling time, and initial enrichment) and then were used to determine those same quantities in each measured spent fuel assembly. Furthermore, the results obtained in comparison with the operator declared values, as well as the methodology developed, are discussed in detail in the paper.« less

  15. Effect of different precursors on generation of reference spectra for structural molecular background correction by solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry: Determination of antimony in cosmetics.

    PubMed

    Barros, Ariane Isis; Victor de Babos, Diego; Ferreira, Edilene Cristina; Gomes Neto, José Anchieta

    2016-12-01

    Different precursors were evaluated for the generation of reference spectra and correction of the background caused by SiO molecules in the determination of Sb in facial cosmetics by high-resolution continuum source graphite furnace atomic absorption spectrometry employing direct solid sample analysis. Zeolite and mica were the most effective precursors for background correction during Sb determination using the 217.581nm and 231.147nm lines. Full 2(3) factorial design and central composite design were used to optimize the atomizer temperature program. The optimum pyrolysis and atomization temperatures were 1500 and 2100°C, respectively. A Pd(NO3)2/Mg(NO3)2 mixture was employed as the chemical modifier, and calibration was performed at 217.581nm with aqueous standards containing Sb in the range 0.5-2.25ng, resulting in a correlation coefficient of 0.9995 and a slope of 0.1548s ng(-1). The sample mass was in the range 0.15-0.25mg. The accuracy of the method was determined by analysis of Montana Soil (II) certified reference material, together with addition/recovery tests. The Sb concentration found was in agreement with the certified value, at a 95% confidence level (paired t-test). Recoveries of Sb added to the samples were in the range 82-108%. The limit of quantification was 0.9mgkg(-1) and the relative standard deviation (n=3) ranged from 0.5% to 7.1%. From thirteen analyzed samples, Sb was not detected in ten samples (blush, eye shadow and compact powder); three samples (two blush and one eye shadow) presented Sb concentration in the 9.1-14.5mgkg(-1) range.

  16. Neutron spectrometry for UF6 enrichment verification in storage cylinders

    SciTech Connect

    Mengesha, Wondwosen; Kiff, Scott D.

    2015-01-29

    Verification of declared UF6 enrichment and mass in storage cylinders is of great interest in nuclear material nonproliferation. Nondestructive assay (NDA) techniques are commonly used for safeguards inspections to ensure accountancy of declared nuclear materials. Common NDA techniques used include gamma-ray spectrometry and both passive and active neutron measurements. In the present study, neutron spectrometry was investigated for verification of UF6 enrichment in 30B storage cylinders based on an unattended and passive measurement approach. MCNP5 and Geant4 simulated neutron spectra, for selected UF6 enrichments and filling profiles, were used in the investigation. The simulated neutron spectra were analyzed using principal component analysis (PCA). The PCA technique is a well-established technique and has a wide area of application including feature analysis, outlier detection, and gamma-ray spectral analysis. Results obtained demonstrate that neutron spectrometry supported by spectral feature analysis has potential for assaying UF6 enrichment in storage cylinders. The results from the present study also showed that difficulties associated with the UF6 filling profile and observed in other unattended passive neutron measurements can possibly be overcome using the approach presented.

  17. Spatial mapping of soil and radioactivity redistribution at the hillslope scale using in-situ gamma spectrometry, terrestrial laser scanning and RFID tags after the Fukushima nuclear accident fallout.

    NASA Astrophysics Data System (ADS)

    Patin, Jeremy; Onda, Yuichi; Noguchi, Takehiro; Parsons, Anthony

    2013-04-01

    In March 2011, the Fukushima Daiichi Nuclear Power Plant disaster, triggered by the Tohoku earthquake and the consequent tsunami, released a large amount of radionuclides in the environment. To provide a rapid assessment of the soil contamination and its potential redistribution, intensive scientific monitoring has been conducted since July 2011 in our study site, located in the Yamakiya district of Kawamata town, in Fukushima prefecture, Japan, about 37 km from the power plant. In this paper, we summarize and analyze a dataset combining multiple innovative methods deployed inside a 5m x 22m bounded hillslope plot. In addition to runoff volumes and sediments radiocesium concentrations, each major rainfall event was followed by in situ gamma spectrometry measurements. In 2012, to trace the complex behavior of sediments inside the plot, about 300 RFID (Radio-Frequency IDentification) tags representing coarse sediments were scattered and their spatial position was periodically checked using a total station. Finally, several high resolutions Digital Elevation Models were acquired with a terrestrial laser scanner to assess the surface structure and changes. The observed processes at the event scale include interrill and rill erosion, as well as local deposition and remobilization phenomenon. Not only do they directly provide information on the erosion spatio-temporal variability and the associated radionuclides transfers, but combined together they can constitute a solid basis to improve and challenge process-based distributed erosion models.

  18. Investigation of (235)U, (226)Ra, (232)Th, (40)K, (137)Cs, and heavy metal concentrations in Anzali international wetland using high-resolution gamma-ray spectrometry and atomic absorption spectroscopy.

    PubMed

    Zare, Mohammad Reza; Kamali, Mahdi; Fallahi Kapourchali, Maryam; Bagheri, Hashem; Khoram Bagheri, Mahdi; Abedini, Ali; Pakzad, Hamid Reza

    2016-02-01

    Measurements of natural radioactivity levels and heavy metals in sediment and soil samples of the Anzali international wetland were carried out by two HPGe-gamma ray spectrometry and atomic absorption spectroscopy techniques. The concentrations of (235)U, (226)Ra, (232)Th, (40)K, and (137)Cs in sediment samples ranged between 1.05 ± 0.51-5.81 ± 0.61, 18.06 ± 0.63-33.36 ± .0.34, 17.57 ± 0.38-45.84 ± 6.23, 371.88 ± 6.36-652.28 ± 11.60, and 0.43 ± 0.06-63.35 ± 0.94 Bq/kg, while in the soil samples they vary between 2.36-5.97, 22.71-38.37, 29.27-42.89, 472.66-533, and 1.05-9.60 Bq/kg for (235)U, (226)Ra, (232)Th, (40)K, and (137)Cs, respectively. Present results are compared with the available literature data and also with the world average values. The radium equivalent activity was well below the defined limit of 370 Bq/kg. The external hazard indices were found to be less than 1, indicating a low dose. Heavy metal concentrations were found to decrease in order as Fe > Mn > Sr > Zn > Cu > Cr > Ni > Pb > Co > Cd. These measurements will serve as background reference levels for the Anzali wetland.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu V.; Kaplin, V. A.; Kachanov, V. A.; Kheymits, M. D.; Leonov, A. A.; Longo, F.; Mazets, E. P.; Maestro, P.; Marrocchesi, P.; Mereminskiy, I. A.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu

    2012-01-01

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

  1. Inequality spectra

    NASA Astrophysics Data System (ADS)

    Eliazar, Iddo

    2017-03-01

    Inequality indices are widely applied in economics and in the social sciences as quantitative measures of the socioeconomic inequality of human societies. The application of inequality indices extends to size-distributions at large, where these indices can be used as general gauges of statistical heterogeneity. Moreover, as inequality indices are plentiful, arrays of such indices facilitate high-detail quantification of statistical heterogeneity. In this paper we elevate from arrays of inequality indices to inequality spectra: continuums of inequality indices that are parameterized by a single control parameter. We present a general methodology of constructing Lorenz-based inequality spectra, apply the general methodology to establish four sets of inequality spectra, investigate the properties of these sets, and show how these sets generalize known inequality gauges such as: the Gini index, the extended Gini index, the Rényi index, and hill curves.

  2. Gamma Knife

    MedlinePlus

    ... equipment? How is safety ensured? What is this equipment used for? The Gamma Knife® and its associated ... in size. top of page How does the equipment work? The Gamma Knife® utilizes a technique called ...

  3. Infrared spectra of olivine polymorphs - Alpha, beta phase and spinel

    NASA Technical Reports Server (NTRS)

    Jeanloz, R.

    1980-01-01

    The infrared absorption spectra of several olivines (alpha phase) and their corresponding beta phase (modified spinel) and spinel (gamma) high-pressure polymorphs are determined. Spectra were measured for ground and pressed samples of alpha and gamma A2SiO4, where A = Fe, Ni, Co; alpha and gamma Mg2GeO4; alpha Mg2SiO4; and beta Co2SiO4. The spectra are interpreted in terms of internal, tetrahedral and octagonal, and lattice vibration modes, and the spinel results are used to predict the spectrum of gamma Mg2SiO4. Analysis of spectra obtained from samples of gamma Mg2GeO4 heated to 730 and 1000 C provides evidence that partial inversion could occur in silicate spinels at elevated temperatures and pressures.

  4. Gamma Ray Pulsars: Multiwavelength Observations

    NASA Technical Reports Server (NTRS)

    Thompson, David J.

    2004-01-01

    High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The seven or more pulsars seen by instruments on the Compton Gamma Ray Observatory (CGRO) show that: the light curves usually have double-peak structures (suggesting a broad cone of emission); gamma rays are frequently the dominant component of the radiated power; and all the spectra show evidence of a high-energy turnover. For all the known gamma-ray pulsars, multiwavelength observations and theoretical models based on such observations offer the prospect of gaining a broad understanding of these rotating neutron stars. The Gamma-ray Large Area Space Telescope (GLAST), now in planning for a launch in 2006, will provide a major advance in sensitivity, energy range, and sky coverage.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  6. Plasma Desorption Mass Spectrometry: Coming of Age.

    ERIC Educational Resources Information Center

    Cotter, Robert J.

    1988-01-01

    Discusses the history and development of Plasma Desorption Mass Spectrometry to determine molecular weights and structures of proteins and polymers. Outlines theory, instrumentation, and sample preparation commonly used. Gives several examples of resulting spectra. (ML)

  7. Photon spectra from WIMP annihilation

    SciTech Connect

    Cembranos, J. A. R.; Cruz-Dombriz, A. de la; Dobado, A.; Maroto, A. L.; Lineros, R. A.

    2011-04-15

    If the present dark matter in the Universe annihilates into standard model particles, it must contribute to the fluxes of cosmic rays that are detected on the Earth and, in particular, to the observed gamma-ray fluxes. The magnitude of such a contribution depends on the particular dark matter candidate, but certain features of the produced photon spectra may be analyzed in a rather model-independent fashion. In this work we provide the complete photon spectra coming from WIMP annihilation into standard model particle-antiparticle pairs obtained by extensive Monte Carlo simulations. We present results for each individual annihilation channel and provide analytical fitting formulas for the different spectra for a wide range of WIMP masses.

  8. Erratum: Intergalactic Photon Spectra from the Far IR to the UV Lyman Limit for 0 < z < 6 and the Optical Depth of the Universe to High Energy Gamma-Rays

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Malkan, M. A.; Scully, S. T.

    2007-01-01

    Table 1 in our paper had erroneous numbers for the coefficients fitting the parametric form for the optical depth of the universe to gamma-rays; tau. The correct values for these parameters as described in the original text are given in the table for various redshifts for the baseline model (upper row) and fast evolution (lower row) for each individual redshift.

  9. Intergalactic Photon Spectra from the Far-IR to the UV Lyman Limit for 0 < z < 6 and the Optical Depth of the Universe to High-Energy Gamma Rays

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Malkan, M. A.; Scully, S. T.

    2006-01-01

    We calculate the intergalactic photon density as a function of both energy and redshift for 0Gamma-rays in intergalactic space owing to interactions with low-energy photons and the 2.7 K cosmic microwave background radiation. We calculate the optical depth of the universe, Tau , for Gamma-rays having energies from 4 GeV to 100 TeV emitted by sources at redshifts from 0 to 5. We also give an analytic fit with numerical coefficients for approximating (E(Gamma), z). As an example of the application of our results, we calculate the absorbed spectrum of the blazar PKS 2155-304 at z=0.117 and compare it with the spectrum observed by the HESS air Cerenkov Gamma-ray telescope array.

  10. 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.

  11. 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.

  12. Precise determination of photon emission probabilities for the main X- and gamma-rays of 226Ra in equilibrium with daughters.

    PubMed

    Morel, J; Sepman, S; Rasko, M; Terechtchenko, E; Delgado, J U

    2004-01-01

    Within the context of a joint project between VNIIM (D.I. Mendeleyev Institute for Metrology) and LNHB (Laboratoire National Henri Becquerel), special 226Ra sources were prepared by VNIIM in order to determine as accurately as possible the absolute photon emission probabilities for the main X- and gamma-rays following the decay of 226Ra and daughters. The main purpose of this work was to supplement a previous joint study by Laboratorio Nacional de Metrologia das Radiaçoes Ionizantes (LNMRI) and LNHB to determine their relative values. Some specific point sources were produced for alpha-spectrometry measurements that were undertaken at VNIIM and also for gamma-ray spectrometry studies at VNIIM and LNHB. The 226Ra activity for the gamma-spectrometric sources was measured relative to the alpha-spectrometric sources by comparing the counts of the main gamma-rays. The total uncertainty of the activity for these sources was 0.2% (k = 1). Using calibrated germanium detectors, several X- and gamma-ray spectra were analyzed to determine the absolute photon emission probabilities of 226Ra in radioactive equilibrium with daughters. The results are presented and compared to other published values.

  13. 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.

  14. Gamma rays from the de-excitation of C-12 resonance 15.11 MeV and C-12 resonance 4.44 MeV as probes of energetic particle spectra

    NASA Technical Reports Server (NTRS)

    Crannell, C. J.; Crannell, H.; Ramaty, R.

    1977-01-01

    The flux of 15.11 MeV gamma rays relative to the flux 4.44 MeV gamma rays was calculated from measured cross sections for excitation of the corresponding states of C-12 and from experimental determinations of the branching ratios for direct de-excitation of these states to the ground state. Because of the difference in threshold energies for excitation of these two levels, the relative intensities in the two lines are particularly sensitive to the spectral distribution of energetic particles which excite the corresponding nuclear levels. For both solar and cosmic emission, the observability of the 15.11 MeV line is expected to be enhances by low source-background continuum in this energy range.

  15. NEAR Gamma Ray Spectrometer Characterization and Repair

    NASA Technical Reports Server (NTRS)

    Groves, Joel Lee; Vajda, Stefan

    1998-01-01

    This report covers the work completed in the third year of the contract. The principle activities during this period were (1) the characterization of the NEAR 2 Gamma Ray Spectrometer using a neutron generator to generate complex gamma ray spectra and a large Ge Detecter to identify all the major peaks in the spectra; (2) the evaluation and repair of the Engineering Model Unit of the Gamma Ray Spectrometer for the NEAR mission; (3) the investigation of polycapillary x-ray optics for x-ray detection; and (4) technology transfer from NASA to forensic science.

  16. Status of the GAMMA-400 Project

    NASA Technical Reports Server (NTRS)

    Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Gusakov, Yu. V.; Farber, M. O.; Fradkin, M. I.; Kachanov, V. A.; Kaplin, V. A.; Kheymits, M. D.; Leoniv, A. A.; Longo, F.; Maestro, P.; Marrocchesi, P.; Mazets, E. P.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I.; Naumov, P. Yu.; Papini, P.

    2013-01-01

    The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100 MeV-3 TeV is presented. The angular resolution of the instrument, 1-2 deg at E(gamma) approximately 100 MeV and approximately 0.01 at E(gamma) greater than 100 GeV, its energy resolution is approximately 1% at E(gamma) greater than 100 GeV, and the proton rejection factor is approximately 10(exp 6) are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.

  17. 2010: Status of the GAMMA-400 Project

    NASA Astrophysics Data System (ADS)

    Topchiev, Nikolay; Galper, . M.; Arkhangelskaya, I. V.; Bonvicini, V.; Boezio, M.; Dolgoshein, B. A.; Farber, M. O.; Fradkin, M. I.; Gecha, V. Ya.; Kachanov, V. A.; Kaplin, V. A.; Men'shenin, A. L.; Picozza, P.; Prilutskii, O. F.; Runtso, M. F.; Spillantini, P.; Suchkov, S. I.; Topchiev, N. P.; Vacchi, A.; Yurkin, Yu. T.; Zampa, N.; Zverev, V. G.

    An optimized version of the GAMMA-400 telescope for detecting gamma rays, electrons, and positrons in the energy range 0.1-3000 GeV and high-energy nuclei is presented. Its performance (angular resolution 0.05° , energy resolution 3%, e/p rejection factor 106 ) enables to search gamma rays, electrons, and positrons from annihilation or decay of dark matter components, to detect high-energy gamma rays from galactic and extragalactic astrophysical objects, to measure energy spectra of galactic and extragalactic diffuse gamma-ray emission, to search and investigate transient phenomena, high-energy (more than 1 GeV) gamma-ray bursts and gamma rays from solar flares, as well as galactic electron, positron, and nuclei fluxes.

  18. Online Spectral Fit Tool for Analyzing Reflectance Spectra

    NASA Astrophysics Data System (ADS)

    Penttilä, A.; Kohout, T.

    2015-11-01

    The Online Spectral Fit Tool is developed for analyzing Vis-NIR spectral behavior of asteroids and meteorites. Implementation is done using JavaScript/HTML. Fitted spectra consist of spline continuum and gamma distributions for absorption bands.

  19. Storm Spectra

    NASA Technical Reports Server (NTRS)

    2007-01-01

    portion is defined by the day/night boundary (known as the terminator).

    These two images illustrate only a small fraction of the information contained in a single LEISA scan, highlighting just one aspect of the power of infrared spectra for atmospheric studies.

  20. Perspectives of the GAMMA-400 space observatory for high-energy gamma rays and cosmic rays measurements

    NASA Astrophysics Data System (ADS)

    Topchiev, N. P.; Galper, A. M.; Bonvicini, V.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Bakaldin, A. V.; Bergstrom, L.; Berti, E.; Bigongiari, G.; Bobkov, S. G.; Boezio, M.; Bogomolov, E. A.; Bonechi, S.; Bongi, M.; Bottai, S.; Castellini, G.; Cattaneo, P. W.; Cumani, P.; Dalkarov, O. D.; Dedenko, G. L.; De Donato, C.; Dogiel, V. A.; Finetti, N.; Gorbunov, M. S.; Gusakov, Yu V.; Hnatyk, B. I.; Kadilin, V. V.; Kaplin, V. A.; Kaplun, A. A.; Kheymits, M. D.; Korepanov, V. E.; Larsson, J.; Leonov, A. A.; Loginov, V. A.; Longo, F.; Maestro, P.; Marrocchesi, P. S.; Men'shenin, A. L.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu; Papini, P.; Pearce, M.; Picozza, P.; Rappoldi, A.; Ricciarini, S.; Runtso, M. F.; Ryde, F.; Serdin, O. V.; Sparvoli, R.; Spillantini, P.; Stozhkov, Yu I.; Suchkov, S. I.; Taraskin, A. A.; Tavani, M.; Tiberio, A.; Tyurin, E. M.; Ulanov, M. V.; Vacchi, A.; Vannuccini, E.; Vasilyev, G. I.; Yurkin, Yu T.; Zampa, N.; Zirakashvili, V. N.; Zverev, V. G.

    2016-02-01

    The GAMMA-400 gamma-ray telescope is intended to measure the fluxes of gamma-rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. Such measurements concern the following scientific tasks: investigation of point sources of gamma-rays, studies of the energy spectra of Galactic and extragalactic diffuse emission, studies of gamma-ray bursts and gamma-ray emission from the Sun, as well as high precision measurements of spectra of high-energy electrons and positrons. Also the GAMMA- 400 instrument provides the possibility for protons and nuclei measurements up to knee. But the main goal for the GAMMA-400 mission is to perform a sensitive search for signatures of dark matter particles in high-energy gamma-ray emission. To fulfill these measurements the GAMMA-400 gamma-ray telescope possesses unique physical characteristics in comparison with previous and present experiments. The major advantage of the GAMMA-400 instrument is excellent angular and energy resolution for gamma-rays above 10 GeV. The GAMMA-400 experiment will be installed onboard of the Navigator space platform, manufactured by the NPO Lavochkin Association. The expected orbit will be a highly elliptical orbit (with apogee 300.000 km and perigee 500 km) with 7 days orbital period. An important profit of such an orbit is the fact that the full sky coverage will always be available for gamma ray astronomy.

  1. Existing Data Format for Two-Parameter Beta-Gamma Histograms for Radioxenon

    SciTech Connect

    TW Bowyer; TR Heimbigner; JI McIntyre; AD McKinnon; PL Reeder; E Wittinger

    1999-03-23

    There is a need to establish a commonly acceptable format for storing beta-gated coincidence data for stations in the International Monitoring System (IMS) for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The current aerosol RMS type data format is not applicable for radioxenon in that the current format contains implicit assumptions specific to conventional gamma-ray spectrometry. Some assumptions in the current RMS format are not acceptable for the beta-gated spectra expected from the U.S. Department of Energy PNNL Automated Radioxenon Sampler-Analyzer (ARSA) and other similar systems under use or development from various countries. The RMS data format is not generally applicable for radioxenon measurements in the CTBT for one or more of the following main reasons: 1) The RMS format does not currently support 2-dimensional data. That is, the RMS data format is setup for a simple l-dimensional gamma-ray energy histogram. Current data available from the ARSA system and planned for other radioxenon monitors includes spectral information from gamma-rays and betas/conversion electrons. It is worth noting that the beta/conversion electron energy information will be used to separate the contributions from the different radioxenons. 2) The RMS data format assumes that the conversion between counts and activity can be calculated based (in part) on a simple calibration curve (detector efficiency curve) that depends only on energy of the gamma-ray. In the case of beta-gated gamma-ray spectra and for 2-dimensional spectra, there are generally two detector calibration curves that must be convoluted, the lower energy cutoff for the betas must be considered, and the energy acceptance window must be taken into account to convert counts into activity. . 3) The RMS format has header information that contains aerosol-specific information that allows the activity (Bq) calculated to be converted into a concentration (Bq/SCM). This calculation is performed by dividing the

  2. Gamma ray astronomy and black hole astrophysics

    NASA Technical Reports Server (NTRS)

    Liang, Edison P.

    1990-01-01

    The study of soft gamma emissions from black-hole candidates is identified as an important element in understanding black-hole phenomena ranging from stellar-mass black holes to AGNs. The spectra of Cyg X-1 and observations of the Galactic Center are emphasized, since thermal origins and MeV gamma-ray bumps are evident and suggest a thermal-pair cloud picture. MeV gamma-ray observations are suggested for studying black hole astrophysics such as the theorized escaping pair wind, the anticorrelation between the MeV gamma bump and the soft continuum, and the relationship between source compactness and temperature.

  3. Raman Spectrometry.

    ERIC Educational Resources Information Center

    Gardiner, Derek J.

    1980-01-01

    Reviews mainly quantitative analytical applications in the field of Raman spectrometry. Includes references to other reviews, new and analytically untested techniques, and novel sampling and instrument designs. Cites 184 references. (CS)

  4. Benchmark of the non-parametric Bayesian deconvolution method implemented in the SINBAD code for X/γ rays spectra processing

    NASA Astrophysics Data System (ADS)

    Rohée, E.; Coulon, R.; Carrel, F.; Dautremer, T.; Barat, E.; Montagu, T.; Normand, S.; Jammes, C.

    2016-11-01

    Radionuclide identification and quantification are a serious concern for many applications as for in situ monitoring at nuclear facilities, laboratory analysis, special nuclear materials detection, environmental monitoring, and waste measurements. High resolution gamma-ray spectrometry based on high purity germanium diode detectors is the best solution available for isotopic identification. Over the last decades, methods have been developed to improve gamma spectra analysis. However, some difficulties remain in the analysis when full energy peaks are folded together with high ratio between their amplitudes, and when the Compton background is much larger compared to the signal of a single peak. In this context, this study deals with the comparison between a conventional analysis based on "iterative peak fitting deconvolution" method and a "nonparametric Bayesian deconvolution" approach developed by the CEA LIST and implemented into the SINBAD code. The iterative peak fit deconvolution is used in this study as a reference method largely validated by industrial standards to unfold complex spectra from HPGe detectors. Complex cases of spectra are studied from IAEA benchmark protocol tests and with measured spectra. The SINBAD code shows promising deconvolution capabilities compared to the conventional method without any expert parameter fine tuning.

  5. Characterization of carbonitrided and oxidized layers on low-carbon steel by conversion electron Moessbauer spectrometry, X-ray diffractometry, and X-ray photoelectron spectrometry

    SciTech Connect

    Kurosawa, K.; Li, H.L.; Ujihira, Y.; Nomura, K.

    1999-03-01

    The structures of low-carbon steel oxidized in an aqueous saline bath at 403 K and a fused salt bath at 673 K after carbonitriding were studied using conversion electron Moessbauer spectrometry (CEMS), x-ray diffractometry (XRD), and x-ray photoelectron spectrometry (XPS). Only a doublet peak caused by poor crystallinity of iron oxyhydroxides (FeOOH) or fine particles of iron oxides such as magnetite (Fe{sub 3}O{sub 4}) and maghemite ({gamma}-Fe{sub 2}O{sub 3}) was detected in the CEMS spectra of the surface of the carbonitrided steel oxidized in the aqueous saline bath. Corrosion resistance of the carbonitrided specimens was increased by oxidizing. The oxidized layers produced in the aqueous saline bath were superior to those produced in the fused salt bath as a result of pores in the carbonitrided zone being filled with finer particles of iron oxides and the production of tight, thick oxide layers of amorphous iron oxyhydroxides or fine iron oxides. Deformation of iron nitride ({gamma}{prime}-Fe{sub 4}N) crystals in the carbonitrided zone could not be detected by oxidizing in the aqueous saline bath but were detected in the fused salt bath at 673 K.

  6. Accuracy of field spectrometry in estimating 137Cs contamination in high altitude alpine soils.

    PubMed

    Agnesod, G; Lazzaron, R; Operti, C; Zappa, C

    2001-01-01

    In situ gamma ray spectrometry is an attractive method for providing information on the concentrations of radionuclides in the soil. This method requires separate knowledge of the soil density and of the radioactivity distribution relative to soil depth. In-field gamma spectrometry measurements were performed together with sampling of the soil at the same site for subsequent gamma spectrometry analysis in the laboratory. Results of 137Cs concentration were compared in order to: (i) verify the effectiveness of in situ gamma spectrometry in averaging local inhomogeneties in the soil; and (ii) quantify the sensitivity of the gamma ray spectrometry soil radioactivity evaluation with respect to the variability of the depth profiles obtained from a single site sampling. The site of study is a high altitude pasture, in the Alpine environment.

  7. Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.

    1992-01-01

    The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1,2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

  8. Ion mobility-mass spectrometry.

    PubMed

    Kanu, Abu B; Dwivedi, Prabha; Tam, Maggie; Matz, Laura; Hill, Herbert H

    2008-01-01

    This review article compares and contrasts various types of ion mobility-mass spectrometers available today and describes their advantages for application to a wide range of analytes. Ion mobility spectrometry (IMS), when coupled with mass spectrometry, offers value-added data not possible from mass spectra alone. Separation of isomers, isobars, and conformers; reduction of chemical noise; and measurement of ion size are possible with the addition of ion mobility cells to mass spectrometers. In addition, structurally similar ions and ions of the same charge state can be separated into families of ions which appear along a unique mass-mobility correlation line. This review describes the four methods of ion mobility separation currently used with mass spectrometry. They are (1) drift-time ion mobility spectrometry (DTIMS), (2) aspiration ion mobility spectrometry (AIMS), (3) differential-mobility spectrometry (DMS) which is also called field-asymmetric waveform ion mobility spectrometry (FAIMS) and (4) traveling-wave ion mobility spectrometry (TWIMS). DTIMS provides the highest IMS resolving power and is the only IMS method which can directly measure collision cross-sections. AIMS is a low resolution mobility separation method but can monitor ions in a continuous manner. DMS and FAIMS offer continuous-ion monitoring capability as well as orthogonal ion mobility separation in which high-separation selectivity can be achieved. TWIMS is a novel method of IMS with a low resolving power but has good sensitivity and is well intergrated into a commercial mass spectrometer. One hundred and sixty references on ion mobility-mass spectrometry (IMMS) are provided.

  9. Enhancement of energy spectra through constant fraction timing method

    NASA Astrophysics Data System (ADS)

    Ermis, Elif Ebru; Celiktas, Cuneyt

    2017-02-01

    The energy spectra of 137Cs, 60Co and 14C were achieved by using the spectrometers composed of different types of detectors. In this work, constant fraction timing method was used to enhance their energy spectra. Energy resolution values of 137Cs and 60Co gamma energy spectra were improved through this timing method. In addition, electronic noise appeared in the energy spectrum of 14C was discriminated through the timing method, leading to clear beta energy spectrum.

  10. Xgremlin: Interferograms and spectra from Fourier transform spectrometers analysis

    NASA Astrophysics Data System (ADS)

    Nave, G.; Griesmann, U.; Brault, J. W.; Abrams, M. C.

    2015-11-01

    Xgremlin is a hardware and operating system independent version of the data analysis program Gremlin used for Fourier transform spectrometry. Xgremlin runs on PCs and workstations that use the X11 window system, including cygwin in Windows. It is used to Fourier transform interferograms, plot spectra, perform phase corrections, perform intensity and wavenumber calibration, and find and fit spectral lines. It can also be used to construct synthetic spectra, subtract continua, compare several different spectra, and eliminate ringing around lines.

  11. Determination of neutron spectra within the energy of 1 keV to 1 MeV by means of reactor dosimetry

    SciTech Connect

    Sergeyeva, Victoria; Destouches, Christophe; Lyoussi, Abdallah; Thiollay, Nicolas; Vigneau, Olivier; Korschinek, Gunther; Carcreff, Hubert

    2015-07-01

    The standard procedure for neutron reactor dosimetry is based on neutron irradiation of a target and its post-irradiation analysis by Gamma and/or X-ray spectrometry. Nowadays, the neutron spectra can be easily characterized for thermal and fast energies (respectively 0.025 eV and >1 MeV). In this work we propose a new target and an innovating post-irradiation technique of analysis in order to detect the neutron spectra within the energy of 1 keV to 1 MeV. This article will present the calculations performed for the selection of a suitable nuclear reaction and isotope, the results predicted by simulations, the irradiation campaign that is proposed and the post-irradiation technique of analysis. (authors)

  12. Study of gamma-ray strength functions

    SciTech Connect

    Gardner, D.G.; Gardner, M.A.; Dietrich, F.S.

    1980-08-07

    The use of gamma-ray strength function systematics to calculate neutron capture cross sections and capture gamma-ray spectra is discussed. The ratio of the average capture width, GAMMA/sub ..gamma../-bar, to the average level spacing, D/sub obs/, both at the neutron separation energy, can be derived from such systematics with much less uncertainty than from separate systematics for values of GAMMA/sub ..gamma../-bar and D/sub obs/. In particular, the E1 gamma-ray strength function is defined in terms of the giant dipole resonance (GDR). The GDR line shape is modeled with the usual Lorentzian function and also with a new energy-dependent, Breit-Wigner (EDBW) function. This latter form is further parameterized in terms of two overlapping resonances, even for nuclei where photonuclear measurements do not resolve two peaks. In the mass ranges studied, such modeling is successful for all nuclei away from the N = 50 closed neutron shell. Near the N = 50 shell, a one-peak EDBW appears to be more appropriate. Examples of calculated neutron capture excitation functions and capture gamma-ray spectra using the EDBW form are given for target nuclei in the mass-90 region and also in the Ta-Au mass region. 20 figures.

  13. A new G(gamma) chain variant: Hb F-Bron [gamma20(B2)val-->Ala].

    PubMed

    Lacan, Philippe; Burnichon, Nelly; Becchi, Michel; Zanella-Cleon, Isabelle; Aubry, Martine; Couprie, Nicole; Francina, Alain

    2005-01-01

    A new G(gamma) hemoglobin (Hb) variant, Hb F-Bron [gamma20(B2)Val-->Ala] on the first exon of the G(gamma)-globin gene is described. The variant was characterized by DNA sequencing and mass spectrometry (MS). Hematological abnormalities included hypochromia and microcytosis and were probably caused by an interaction with an alpha-thalassemia (thal) (3.7 kb) deletion in the heterozygous state.

  14. Gamma watermarking

    SciTech Connect

    Ishikawa, Muriel Y.; Wood, Lowell L.; Lougheed, Ronald W.; Moody, Kenton J.; Wang, Tzu-Fang

    2004-05-25

    A covert, gamma-ray "signature" is used as a "watermark" for property identification. This new watermarking technology is based on a unique steganographic or "hidden writing" digital signature, implemented in tiny quantities of gamma-ray-emitting radioisotopic material combinations, generally covertly emplaced on or within an object. This digital signature may be readily recovered at distant future times, by placing a sensitive, high energy-resolution gamma-ray detecting instrument reasonably precisely over the location of the watermark, which location may be known only to the object's owner; however, the signature is concealed from all ordinary detection means because its exceedingly low level of activity is obscured by the natural radiation background (including the gamma radiation naturally emanating from the object itself, from cosmic radiation and material surroundings, from human bodies, etc.). The "watermark" is used in object-tagging for establishing object identity, history or ownership. It thus may serve as an aid to law enforcement officials in identifying stolen property and prosecuting theft thereof. Highly effective, potentially very low cost identification-on demand of items of most all types is thus made possible.

  15. Beamstrahlung spectra in next generation linear colliders

    SciTech Connect

    Barklow, T.; Chen, P. ); Kozanecki, W. )

    1992-04-01

    For the next generation of linear colliders, the energy loss due to beamstrahlung during the collision of the e{sup +}e{sup {minus}} beams is expected to substantially influence the effective center-of-mass energy distribution of the colliding particles. In this paper, we first derive analytical formulae for the electron and photon energy spectra under multiple beamstrahlung processes, and for the e{sup +}e{sup {minus}} and {gamma}{gamma} differential luminosities. We then apply our formulation to various classes of 500 GeV e{sup +}e{sup {minus}} linear collider designs currently under study.

  16. Underwater gamma surveys of Mururoa and Fangataufa lagoons.

    PubMed

    Osvath, I; Povinec, P; Huynh-Ngoc, L; Comanducci, J F

    1999-09-30

    Underwater gamma-ray spectrometry is an effective alternative or complement to traditional sampling and laboratory analyses for applications such as contamination assessment in emergency situations, long-term monitoring of radioactive releases or investigation of sunken radioactive objects. This technique was recently used in a seabed contamination study undertaken at the South Pacific nuclear weapons test sites of the Mururoa and Fangataufa atolls in order to guide and focus sediment core sampling in the areas with highest gamma-emitting radionuclide levels. 60Co inventories estimated on the basis of the underwater gamma-ray spectrometry survey were in good agreement with results previously obtained by traditional sediment sampling and laboratory analysis.

  17. Infrared spectra of U.S. automobile original finishes (post - 1989). VIII: In situ identification of bismuth vanadate using extended range FT-IR spectroscopy, Raman spectroscopy, and X-ray fluorescence spectrometry.

    PubMed

    Suzuki, Edward M

    2014-03-01

    Chrome Yellow (PbCrO4 ·xPbSO4 ) was a common pigment in U.S. automobile OEM finishes for more than three decades, but in the early 1990s its use was discontinued. One of its main replacements was Bismuth Vanadate (BiVO4 ·nBi2 MoO6 , n = 0-2), which was commercially introduced in 1985, as this inorganic pigment also produces a very bright hue and has excellent outdoor durability. This paper describes the in situ identification of Bismuth Vanadate in automotive finishes using FT-IR and dispersive Raman spectroscopy and XRF spectrometry. Some differentiation of commercial formulations of this pigment is possible based on far-infrared absorptions, Raman data, and elemental analysis. The spectral differences arise from the presence or absence of molybdenum, the use of two crystal polymorphs of BiVO4 , and differences in pigment stabilizers. Bismuth Vanadate is usually not used alone, and it is typically found with Isoindoline Yellow, hydrous ferric oxide, rutile, Isoindolinone Yellow 3R, or various combinations of these.

  18. Infrared spectra of U.S. automobile original finishes (1998-2000). IX. identification of bismuth oxychloride and silver/white mica pearlescent pigments using extended range FT-IR spectroscopy, XRF spectrometry, and SEM/EDS analysis.

    PubMed

    Suzuki, Edward M

    2014-09-01

    Bismuth oxychloride (BiOCl) was the first viable synthetic pearl pigment developed 50 years ago. It was only used for a limited time period in automotive paint (model years 1998-2000), serving to produce luster for a single Chrysler black metallic color. Identification of this pigment in an unknown automotive paint can thus facilitate determination of the vehicle of origin. Bismuth oxychloride imparts effects similar to those produced by silver/white mica pearlescent pigments, and such a pigment was used together with bismuth oxychloride in at least one original equipment manufacturer (OEM) basecoat. Silver/white micas are now used primarily in white pearl tricoat systems. This article describes the identification of bismuth oxychloride and silver/white mica pearlescent pigments in automotive finishes using FT-IR spectroscopy, X-ray fluorescence (XRF) spectrometry, and SEM/EDS analysis. Data for some cadmium pigments, which were used in automotive paint several decades ago, are also presented as they produce infrared absorptions similar to that of bismuth oxychloride.

  19. Mass spectrometry of aerospace materials

    NASA Technical Reports Server (NTRS)

    Colony, J. A.

    1976-01-01

    Mass spectrometry is used for chemical analysis of aerospace materials and contaminants. Years of analytical aerospace experience have resulted in the development of specialized techniques of sampling and analysis which are required in order to optimize results. This work has resulted in the evolution of a hybrid method of indexing mass spectra which include both the largest peaks and the structurally significant peaks in a concise format. With this system, a library of mass spectra of aerospace materials was assembled, including the materials responsible for 80 to 90 percent of the contamination problems at Goddard Space Flight Center during the past several years.

  20. Quantum synchrotron spectra from semirelativistic electrons in teragauss magnetic fields

    NASA Technical Reports Server (NTRS)

    Brainerd, J. J.

    1987-01-01

    Synchrotron spectra are calculated from quantum electrodynamic transition rates for thermal and power-law electron distributions. It is shown that quantum effects appear in thermal spectra when the photon energy is greater than the electron temperature, and in power-law spectra when the electron energy in units of the electron rest mass times the magnetic field strength in units of the critical field strength is of order unity. These spectra are compared with spectra calculated from the ultrarelativistic approximation for synchrotron emission. It is found that the approximation for the power-law spectra is good, and the approximation for thermal spectra produces the shape of the spectrum accurately but fails to give the correct normalization. Single photon pair creation masks the quantum effects for power-law distributions, so only modifications to thermal spectra are important for gamma-ray bursts.

  1. An analysis of middle ultraviolet dayglow spectra

    NASA Astrophysics Data System (ADS)

    Walden, Billie S.

    1991-12-01

    Middle ultraviolet spectra from 1800 to 3400A are analyzed. These spectra were obtained from the March 1990 rocket flight of the NPS MUSTANG instrument over the altitudes 105km to 315km. The data were compared with computer generated synthetic spectra. A least squares fitting procedure was developed for this purpose. Each data point was weighted using the standard deviation of the means. Synthetic spectra were generated for the following emissions: N2 Vegard-Kaphan; N2 Lyman-Birge-Hopfield; NO gamma, delta, and epsilon; OI 2972A, OII 2470A; and NII 2143A. Altitude profiles for the emissions were obtained. Tentative identification was made of the OIII 2853A emission. A comparison of VK and LBH profiles demonstrates the process of N2 A-state quenching by atomic oxygen.

  2. Investigation of Raman spectra of polyethylene terephthalate

    NASA Astrophysics Data System (ADS)

    Zhu, Changjun; Tong, Na; Song, Lixin; Zhang, Guoqing

    2015-08-01

    Raman spectrometry was employed to study the characteristics of Raman spectra of polyethylene terephthalate (PET), which were treated with sodium hydroxide, sulfuric acid and copper sulfate, respectively. Raman spectra under different conditions were obtained and the characteristics of the Raman spectra were analyzed. The morphology structures were observed under different conditions using Atomic Force Microscope. The results show that the spectral intensity of PET treated with sodium hydroxide is higher than that untreated between 200-1750 cm-1, while the intensity of PET treated with sodium hydroxide is lower than that untreated beyond 1750 cm-1 and the fluorescence background of Raman spectra is decreased. The spectral intensity of PET treated with sulfuric acid is remarkably reduced than that untreated, and the intensity of PET treated with copper sulphate is much higher than that untreated.

  3. Broadband Analysis of Bioagents by Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Fenselau, Catherine; Wynne, Colin; Edwards, Nathan

    Mass spectrometry was first reported to provide analysis of intact metabolite biomarkers from whole cells in 1975.1 Since then advances in ionization techniques have extended our capabilities to polar lipids and, eventually, to proteins.2, 3 Mass spectrometry provides a broadband detection system, which, however, has great specificity. Bioinformatics plays an important role in providing flexible and rapid characterization of species, based on protein and peptide mass spectra collected in the field.

  4. Gamma Processes

    DTIC Science & Technology

    1986-01-01

    E[exp{-Bn Xn 1 U-Y nU-X vi ] - EeUY )Ee (v+Bu)X1 (2.4) where, in the last step, we have dropped the indices n and n-1 because of stationarity and...1967). "Some Problems of Statistical Inference Relating to Double-Gamma Distribution," Trabajos de Estadistica , 18, 67-87. Hugus, D. K. (1982

  5. The gamma 1 and gamma 3 bands of (16)O3: Line positions and intensities

    NASA Technical Reports Server (NTRS)

    Flaud, J.-M.; Camy-Peyret, C.; Devi, V. Malathy; Rinsland, C. P.; Smith, M. A. H.

    1988-01-01

    Using 0.005/cm-resolution Fourier transform spectra of samples of ozone, the gamma 1 and gamma 3 bands of (16)O3 have been reanalyzed to obtain accurate line positions and an extended set of upper state rotational levels (J up to 69, K sub a up to 20). Combined with the available microwave data, these upper state rotational levels were satisfactorily fitted using a Hamiltonian which takes explicitly into account the strong Coriolis interaction affecting the rotational levels of these two interacting states. In addition, 350 relative line intensities were measured from which the rotational expansions of the transition moment operators for the gamma 1 and gamma 3 states have been deduced. Finally, a complete listing of line positions, intensities, and lower state energies of the gamma 1 and gamma 3 bands of (16)O3 has been generated.

  6. Detecting axionlike particles with gamma ray telescopes.

    PubMed

    Hooper, Dan; Serpico, Pasquale D

    2007-12-07

    We propose that axionlike particles (ALPs) with a two-photon vertex, consistent with all astrophysical and laboratory bounds, may lead to a detectable signature in the spectra of high-energy gamma-ray sources. This occurs as a result of gamma rays being converted into ALPs in the magnetic fields of efficient astrophysical accelerators according to the "Hillas criterion", such as jets of active galactic nuclei or hot spots of radio galaxies. The discovery of such an effect is possible by GLAST in the 1-100 GeV range and by ground-based gamma-ray telescopes in the TeV range.

  7. Report to the DOE nuclear data committee. [EV RANGE 10-100; CROSS SECTIONS; PHOTONEUTRONS; NEUTRONS; GAMMA RADIATION; COUPLED CHANNEL THEORY; DIFFERENTIAL CROSS SECTIONS; MEV RANGE 01-10; ; CAPTURE; GAMMA SPECTRA; THERMAL NEUTRONS; COMPUTER CALCULATIONS; DECAY; FISSION PRODUCTS; FISSION YIELD; SHELL MODELS; NUCLEAR DATA COLLECTIONS

    SciTech Connect

    Struble, G.L.; Haight, R.C.

    1981-03-01

    Topics covered include: studies of (n, charged particle) reactions with 14 to 15 MeV neutrons; photoneutron cross sections for /sup 15/N; neutron radiative capture; Lane-model analysis of (p,p) and (n,n) scattering on the even tin isotopes; neutron scattering cross sections for /sup 181/Ta, /sup 197/Au, /sup 209/Bi, /sup 232/Th, and /sup 238/U inferred from proton scattering and charge exchange cross sections; neutron-induced fission cross sections of /sup 245/Cm and /sup 242/Am; fission neutron multiplicities for /sup 245/Cm and /sup 242/Am; the transport of 14 MeV neutrons through heavy materials 150 < A < 208; /sup 249/Cm energy levels from measurement of thermal neutron capture gamma rays; /sup 231/Th energy levels from neutron capture gamma ray and conversion electron spectroscopy; new measurements of conversion electron binding energies in berkelium and californium; nuclear level densities; relative importance of statistical vs. valence neutron capture in the mass-90 region; determination of properties of short-lived fission products; fission yield of /sup 87/Br and /sup 137/I from 15 nuclei ranging from /sup 232/Th to /sup 249/Cf; evaluation of charged particle data for the ECPL library; evaluation of secondary charged-particle energy and angular distributions for ENDL; and evaluated nuclear structure libraries derived from the table of isotopes. (GHT)

  8. Atmospheric gamma-ray and neutron flashes

    SciTech Connect

    Babich, L. P. Kudryavtsev, A. Yu. Kudryavtseva, M. L. Kutsyk, I. M.

    2008-01-15

    Gamma-ray pulses are calculated from 2D numerical simulations of an upward atmospheric discharge in a self-consistent electric field using the multigroup approach to the kinetics of relativistic runaway electrons (REs). Computed {gamma}-ray numbers and spectra are consistent with those of terrestrial {gamma}-ray flashes (TGFs) observed aboard spacecrafts. The RE flux is concentrated mainly within the domain of the Blue Jet fluorescence. This confirms that exactly the domain adjacent to a thundercloud is the source of the observed {gamma}-ray flashes. The yield of photonuclear neutrons is calculated. One {gamma}-ray pulse generates {approx}10{sup 14}-10{sup 15} neutrons. The possibility of the direct deposition of REs to the detector readings and the origin of the lightning-advanced TGFs are discussed.

  9. 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.

  10. Laser ablation/Fourier transform mass spectrometry of polymers

    NASA Astrophysics Data System (ADS)

    Creasy, William R.; Brenna, J. T.

    1989-10-01

    Laser ablation/ionization followed by Fourier transform mass spectrometry is used to identify and characterize polymers. The mass spectra of several polymers are discussed, including polyimide, polyamic acid, Dupont Tefzel, and polyphenylene sulfide.

  11. Reactor Neutrino Spectra

    NASA Astrophysics Data System (ADS)

    Hayes, Anna C.; Vogel, Petr

    2016-10-01

    We present a review of the antineutrino spectra emitted from reactors. Knowledge of these spectra and their associated uncertainties is crucial for neutrino oscillation studies. The spectra used to date have been determined either by converting measured electron spectra to antineutrino spectra or by summing over all of the thousands of transitions that make up the spectra, using modern databases as input. The uncertainties in the subdominant corrections to β-decay plague both methods, and we provide estimates of these uncertainties. Improving on current knowledge of the antineutrino spectra from reactors will require new experiments. Such experiments would also address the so-called reactor neutrino anomaly and the possible origin of the shoulder observed in the antineutrino spectra measured in recent high-statistics reactor neutrino experiments.

  12. Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture

    SciTech Connect

    Scott Wilde, Raymond Keegan

    2008-07-01

    The countrate response of a gamma spectrometry system from a neutron radiation source behind a plane of moderating material doped with a nuclide of a large radiative neutron capture cross-section exhibits a countrate response analogous to a gamma radiation source at the same position from the detector. Using a planar, surface area of the neutron moderating material exposed to the neutron radiation produces a larger area under the prompt gamma ray peak in the detector than a smaller area of dimensions relative to the active volume of the gamma detection system.

  13. Very High Energy Gamma Ray Extension of GRO Observations

    NASA Technical Reports Server (NTRS)

    Weekes, Trevor C.

    1994-01-01

    The membership, progress, and invited talks, publications, and proceedings made by the Whipple Gamma Ray Collaboration is reported for june 1990 through May 1994. Progress was made in the following areas: the May 1994 Markarian Flare at Whipple and EGRET (Energetic Gamma Ray Experiment Telescope) energies; AGN's (Active Galactic Nuclei); bursts; supernova remnants; and simulations and energy spectra.

  14. Gamma Ray Astrophysics: New insight into the universe

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Trombka, J. I.

    1981-01-01

    Gamma ray observations of the solar system, the galaxy and extragalactic radiation are reported. Topics include: planets, comets, and asteroids; solar observations; interstellar medium and galactic structure; compact objects; cosmology; and diffuse radiation. The instrumentation used in gamma ray astronomy in covered along with techniques for the analysis of observational spectra.

  15. Implications for High Energy Blazar Spectra from Intergalactic Absorption Calculations

    NASA Technical Reports Server (NTRS)

    Stecker, F

    2008-01-01

    Given a knowledge of the density spectra intergalactic low energy photons as a function of redshift, one can derive the intrinsic gamma-ray spectra and luminosities of blazars over a range of redshifts and look for possible trends in blazar evolution. Stecker, Baring & Summerlin have found some evidence hinting that TeV blazars with harder spectra have higher intrinsic TeV gamma-ray luminosities and indicating that there may be a correlation of spectral hardness and luminosity with redshift. Further work along these lines, treating recent observations of the blazers lES02291+200 and 3C279 in the TeV and sub-TeV energy ranges, has recently been explored by Stecker & Scully. GLAST will observe and investigate many blazars in the GeV energy range and will be sensitive to blazers at higher redshifts. I examine the implications high redshift gamma-ray absorption for both theoretical and observational blazer studies.

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

    SciTech Connect

    Chyzh, A.; Dashdorj, D.; Baramsai, B.; Mitchell, G. E.; Walker, C. L.; Becker, J. A.; Parker, W.; Wu, C. Y.; Becvar, F.; Kroll, J.; Krticka, M.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.

    2011-07-15

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

  17. Gamma ray astronomy from satellites and balloons

    NASA Technical Reports Server (NTRS)

    Schoenfelder, V.

    1986-01-01

    A survey is given of gamma ray astronomy topics presented at the Cosmic Ray Conference. The major conclusions at the Cosmic Ray Conference in the field of gamma ray astronomy are given. (1) MeV-emission of gamma-ray bursts is a common feature. Variations in duration and energy spectra from burst to burst may explain the discrepancy between the measured log N - log S dependence and the observed isotropy of bursts. (2) The gamma-ray line at 1.809 MeV from Al(26) is the first detected line from a radioactive nucleosynthesis product. In order to understand its origin it will be necessary to measure its longitude distribution in the Milky Way. (3) The indications of a gamma-ray excess found from the direction of Loop I is consistent with the picture that the bulk of cosmic rays below 100 GeV is produced in galactic supernova remnants. (4) The interpretation of the large scale distribution of gamma rays in the Milky Way is controversial. At present an extragalactic origin of the cosmic ray nuclei in the GeV-range cannot be excluded from the gamma ray data. (5) The detection of MeV-emission from Cen A is a promising step towards the interesting field of extragalactic gamma ray astronomy.

  18. Physics issues of gamma ray burst emissions

    NASA Technical Reports Server (NTRS)

    Liang, Edison

    1987-01-01

    The critical physics issues in the interpretation of gamma-ray-burst spectra are reviewed. An attempt is made to define the emission-region parameter space satisfying the maximum number of observational and theoretical constraints. Also discussed are the physical mechanisms responsible for the bursts that are most consistent with the above parameter space.

  19. Mass spectrometry

    SciTech Connect

    Burlingame, A.L.; Baillie, T.A.; Derrick, P.J.

    1986-04-01

    It is the intention of the review to bring together in one source the direction of major developments in mass spectrometry and to illustrate these by citing key contributions from both fundamental and applied research. The Review is intended to provide the reader with a sense of the main currents, their breadth and depth, and probable future directions. It is also intended to provide the reader with a glimpse of the diverse discoveries and results that underpin the eventual development of new methods and instruments - the keys to obtaining new insights in all the physical, chemical, and biological sciences which depend on mass spectrometry at various levels of sophistication. Focal points for future interdisciplinary synergism might be selective quantitative derivatization of large peptides, which would convey properties that direct fragmentation providing specific sequence information, or optimization of LCMS for biooligomer sequencing and mixture analysis, or the perfect way to control or enhance the internal energy of ions of any size, or many others. 1669 references.

  20. Measurement of radionuclide activities induced in target components of an IBA CYCLONE 18/9 by gamma-ray spectrometry with HPGe and LaBr3: Ce detectors.

    PubMed

    Tomarchio, Elio

    2014-08-01

    Cyclotrons are used worldwide to produce radiopharmaceuticals by proton irradiation of a suitable target. The intense secondary neutron beam generated by proton interactions with the target induce high radionuclide activities in the target assembly parts that may result in an exposure to high dose levels of the operators during maintenance. The main goal of this work is to evaluate gamma-emitting radionuclide activities induced in Havar foils and titanium windows of a target assembly and carousel stripper forks of an IBA CYCLONE 18/9 cyclotron. The knowledge of radionuclide inventory for each component is required by many companies to assess risk for operators before waste handling and disposal. Gamma-ray spectrometric analyses were carried out with High Purity Germanium (HPGe) and Lanthanum bromide (LaBr3:Ce) scintillation detectors. HPGe is the most used detector for its high energy resolution although it is more suitable for use in a laboratory. The use of LaBr3:Ce can be considered a viable option, particularly in realizing a portable spectrometric system to perform "on-site" measurements and a fast dose rate evaluation before the disposal of activated parts. Due to a high activity of target assembly components replaced after a typical irradiation cycle (about 5000 μAh integrated beam current), gamma-ray spectrometric measurements were performed at a large distance from the detector, even more than 100 cm, or by using a purposely realized Lead-walled collimator. The identification of some key-radionuclides allows to evaluate through simple formulations the dose rate behavior for each component as function of decay time from the last irradiation. The knowledge of the dose rate behavior is a significant piece of information to health physicists for waste handling with safety at work. For an Havar™ foil, the dose rate will be reduced to about 1/1,000 of the starting value after a decay period of approximately 4 y (about 1,500 d), with a relatively safety at

  1. Electrons and protons separation in the GAMMA-400 experiment

    NASA Astrophysics Data System (ADS)

    Leonov, Alexey

    The GAMMA-400 gamma-ray telescope is intended to measure the fluxes of gamma-rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. Such measurements concern with the following scientific tasks: search for signatures of dark matter, investigation of point sources of gamma-rays, studies of the energy spectra of Galactic and extragalactic diffuse emission, studies of gamma-ray bursts and gamma-ray emission from the Sun, as well as high precision measurements of spectra of high-energy electrons and positrons, protons and nuclei up to the knee. The main components of cosmic rays are protons and helium nuclei, whereas the part of lepton component in total flux is ~10^-3 for high energies. In present paper the capability of the GAMMA-400 gamma-ray telescope to distinguish electrons and positrons from protons in cosmic rays is investigated. The separate investment in proton rejection is studied for each detector system of the GAMMA-400 gamma-ray telescope. Using combined information from all detector systems allow us to provide rejection from protons with factor of ~4×10^5 for vertical incident particles and ~3×10^5 for particles with initial inclination of 30 deg.

  2. Methods to Collect, Compile, and Analyze Observed Short-lived Fission Product Gamma Data

    SciTech Connect

    Finn, Erin C.; Metz, Lori A.; Payne, Rosara F.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Pierson, Bruce D.; Ellis, Tere A.

    2011-09-29

    A unique set of fission product gamma spectra was collected at short times (4 minutes to 1 week) on various fissionable materials. Gamma spectra were collected from the neutron-induced fission of uranium, neptunium, and plutonium isotopes at thermal, epithermal, fission spectrum, and 14-MeV neutron energies. This report describes the experimental methods used to produce and collect the gamma data, defines the experimental parameters for each method, and demonstrates the consistency of the measurements.

  3. Macromolecule Mass Spectrometry: Citation Mining of User Documents

    DTIC Science & Technology

    2006-05-31

    collision - induced dissociation in quadrupole ion trap coupled tandem mass spectrometry. Ion mass spectra analysis of the resulting fragments determines ...Factor 2 ( DISSOCIATION , FRAGMENTS , CID, COLLISIONS , PRECURSOR, TANDEM, MS/MS, ENERGY , CLEAVAGES, IONS , SPECTRA, QUADRAPOLE, TRAP, PATTERNS, PROTONATION...focuses on the use of post- electrospray ionization collision - induced dissociation of macromolecules coupled

  4. NEGATIVE-ION MASS SPECTROMETRY OF SULFONYLUREA HERBICIDES

    EPA Science Inventory

    Sulfonylurea herbicides have been studied using neg-ion desorption chem.-ionization (DCI) mass spectrometry (MS) and DCI-MS/MS techniques. Both {M-H]- and M.- ions were obsd. in the DCI mass spectra. The collisonally activated dissocn. (CAD) spectra were characteristic of the str...

  5. Crack spectra analysis

    SciTech Connect

    Tiernan, M.

    1980-09-01

    Crack spectra derived from velocity data have been shown to exhibit systematics which reflect microstructural and textural differences between samples (Warren and Tiernan, 1980). Further research into both properties and information content of crack spectra have yielded the following: Spectral features are reproducible even at low pressures; certain observed spectral features may correspond to non-in-situ crack populations created during sample retrieval; the functional form of a crack spectra may be diagnostic of the sample's grain texture; hysteresis is observed in crack spectra between up and down pressure runs - it may be due to friction between the faces of closed crack populations.

  6. Photographic spectra of fireballs

    NASA Astrophysics Data System (ADS)

    Borovička, J.

    2016-01-01

    Two methods of spectroscopy of meteors using image intensified video cameras and classical photographic film cameras are compared. Video cameras provide large number of low resolution spectra of meteors of normal brightness, which can be used for statistical studies. Large format film cameras have been used through the history and provide high resolution spectra, which can be used to derive temperature, density and absolute abundances of various elements in the radiating plasma. The sensitivity of films is, however, low and only spectra of bright meteors (fireballs) can be studied. Examples of photographic fireball spectra are provided.

  7. Solar flare gamma-ray line shapes

    NASA Technical Reports Server (NTRS)

    Werntz, C.; Kim, Y. E.; Lang, Frederick L.

    1990-01-01

    A computer code has been developed which is used to calculate ab initio the laboratory shapes and energy shifts of gamma-ray lines from (C-12)(p, gamma/4.438/)p-prime(C-12) and (O-16)(p, gamma/6.129/)p-prime(O-16) reactions and to calculate the expected shapes of these lines from solar flares. The sensitivity of observable solar flare gamma-ray line shapes to the directionality of the incident particles is investigated for several projectile angular distributions. Shapes of the carbon and oxygen lines are calculated assuming realistic proton energy spectra for particles in circular orbits at the mirror points of magnetic loops, for particle beams directed downward into the photosphere, and for isotropic particle distributions. Line shapes for flare sites near the center of the sun and on the limb are shown for both thin-target and thick-target interaction models.

  8. Gamma-Ray Pulsar Studies With GLAST

    SciTech Connect

    Thompson, D.J.; /NASA, Goddard

    2011-11-23

    Some pulsars have their maximum observable energy output in the gamma-ray band, offering the possibility of using these high-energy photons as probes of the particle acceleration and interaction processes in pulsar magnetospheres. After an extended hiatus between satellite missions, the recently-launched AGILE mission and the upcoming Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) will allow gamma-ray tests of the theoretical models developed based on past discoveries. With its greatly improved sensitivity, better angular resolution, and larger energy reach than older instruments, GLAST LAT should detect dozens to hundreds of new gamma-ray pulsars and measure luminosities, light curves, and phase-resolved spectra with unprecedented resolution. It will also have the potential to find radio-quiet pulsars like Geminga, using blind search techniques. Cooperation with radio and X-ray pulsar astronomers is an important aspect of the LAT team's planning for pulsar studies.

  9. Status of the GAMMA-400 project

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100 MeV-3 TeV is presented. The angular resolution of the instrument, 1-2° at Eγ ˜ 100 MeV and ˜0.01° at Eγ > 100 GeV, its energy resolution ˜1% at Eγ > 100 GeV, and the proton rejection factor ˜106 are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.

  10. Method of Incident Low-Energy Gamma-Ray Direction Reconstruction in GAMMA-400 Gamma-Ray Space Telescope

    NASA Astrophysics Data System (ADS)

    Kheymits, M. D.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Galper, A. M.; Zverev, V. G.; Leonov, A. A.; Suchkov, S. I.; Topchiev, N. P.; Yurkin, Y. T.

    Gamma-telescope GAMMA-400 is designed to measure fluxes of γ-rays and the electron-positron cosmic ray component possibly associated with dark matter particles annihilation or decay; and to search for and study in detail discrete γ-ray sources, to investigate the energy spectra of Galactic and extragalactic diffuse γ-rays, and to study γ-ray bursts (GRB) and γ-rays from the active Sun. GAMMA-400 gamma-ray space-based telescope scientific goals require fine angular resolution. GAMMA-400 is the pair production telescope. In the converter-tracker the incident gamma-quantum convert into electron-positron pair in the tungsten layer and then the tracks are registered by silicon-strip position-sensitive detectors. Multiple scattering processes become a significant obstacle in the incident gamma direction reconstruction for energies below several GeV. The method of utilising this process to improve the resolution is proposed in the presented work.

  11. Search for gamma ray lines from supernovae and supernova remnants

    NASA Technical Reports Server (NTRS)

    Chupp, E. L.; Forrest, D. J.; Suri, A. N.; Adams, R.; Tsai, C.

    1974-01-01

    A gamma ray monitor with a NaI crystal shielded with a cup-shaped CsI cover was contained in the rotating wheel compartment of the OSO-7 spacecraft for measuring the gamma ray spectra from 0.3 to 10 MeV in search for gamma ray lines from a possible remnant in the Gum Nebula and the apparent Type I supernovae in NGC5253. A brief analysis of data yielded no positive indications for X-rays, gamma ray lines, or continuum from these sources.

  12. Spectral feature of 31 December 1981 gamma-ray burst not confirmed

    NASA Technical Reports Server (NTRS)

    Nolan, P. L.; Share, G. H.; Chupp, E. L.; Forrest, D. J.; Matz, S. M.

    1984-01-01

    Measurements of a gamma ray burst at 01:37 UT on December 31, 1981 using the SMM gamma ray spectrometer (GRS) are compared with those made by the Konus instruments on Veneras 11-14. Burst time profiles, photon spectra, and detector energy loss spectra for three time intervals are compared for the GRS and the Konus instruments. It is concluded that the SMM spectra exhibit no evidence for the presence of emission features reported by the Konus group.

  13. System and method for resolving gamma-ray spectra

    DOEpatents

    Gentile, Charles A.; Perry, Jason; Langish, Stephen W.; Silber, Kenneth; Davis, William M.; Mastrovito, Dana

    2010-05-04

    A system for identifying radionuclide emissions is described. The system includes at least one processor for processing output signals from a radionuclide detecting device, at least one training algorithm run by the at least one processor for analyzing data derived from at least one set of known sample data from the output signals, at least one classification algorithm derived from the training algorithm for classifying unknown sample data, wherein the at least one training algorithm analyzes the at least one sample data set to derive at least one rule used by said classification algorithm for identifying at least one radionuclide emission detected by the detecting device.

  14. Induced Radioactivity in Recovered Skylab Materials. [gamma ray spectra

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.; Meegan, C. A.

    1980-01-01

    Four radioactive isotopes found in aluminum and stainless steel samples from Skylab debris were recovered in Australia. The low-level activity was induced by high-energy protons and neutrons in the space environment. Measurements of the specific activities are given.

  15. Observations of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.

    1995-01-01

    Some basic observed properties of gamma-ray bursts are reviewed. Although some properties were known 25 years ago, new and more detailed observations have been made by the Compton Observatory in the past three years. The new observation with the greatest impact has been the observed isotropic distribution of bursts along with a deficiency of weak bursts which would be expected from a homogeneous burst distribution. This is not compatible with any known Galactic population of objects. Gamma-ray bursts show an enormous variety of burst morphologies and a wide spread in burst durations. The spectra of gamma-ray bursts are characterized by rapid variations and peak power which is almost entirely in the gamma-ray energy range. Delayed gamma-ray burst photons extending to GeV energies have been detected for the first time. A time dilation effect has also been reported to be observed in gamma-ray, bursts. The observation of a gamma-ray burst counterpart in another wavelength region has yet to be made.

  16. EPR study of free radicals in non- and gamma-irradiated nutritive supplements containing anthocyanins concentrate from lyophilized red wine

    NASA Astrophysics Data System (ADS)

    Mladenova, Ralitsa B.; Firzov, Cyril; Yordanov, Nicola D.

    2010-09-01

    Nutritive supplements Enoviton, Enoviton C and Enoviton CE containing standardized anthocyanins from lyophilized red wine, vitamins (some of them) and excipients were investigated by EPR spectrometry before and after gamma-irradiation. Non-irradiated samples exhibit one singlet line with g=2.0039±0.0002, most probably due to free radicals from anthocyanins. After irradiation with 10 kGy gamma-rays, tablets of Еnoviton, Еnoviton С and Еnoviton СЕ, all exhibit complex EPR signals centered at a g-value of g=2.0034. The EPR spectrum of irradiated Enoviton is different from that of Еnoviton С or Еnoviton СЕ due to the overlap of the spectra of microcrystalline cellulose and the background singlet spectrum present in all tablets with the EPR resonance due to irradiated ascorbic acid (in Еnoviton С and Еnoviton СЕ). Gamma-induced free radicals exhibit long time stability—for a six months period the intensity of central peak decrease with 30-40%.

  17. Fast atom bombardment tandem mass spectrometry of carotenoids

    SciTech Connect

    van Breeman, R.B.; Schmitz, H.H.; Schwartz, S.J.

    1995-02-01

    Positive ion fast atom bombardment (FAB) tandem mass spectrometry (MS-MS) using a double-focusing mass spectrometer with linked scanning at constant B/E and high-energy collisionally activated dissociation (CAD) was used to differentiate 17 different cartenoids, including {beta}-apo-8{prime}- carotenal, astaxanthin, {alpha}-carotene, {beta}-carotene, {gamma}-carotene, {zeta}-carotene, canthaxanthin, {beta}-cryptoxanthin, isozeaxanthin bis (pelargonate), neoxanthin, neurosporene, nonaprene, lutein, lycopene, phytoene, phytofluene, and zeaxanthin. The carotenoids were either synthetic or isolated from plant tissues. The use of FAB ionization minimized degradation or rearrangement of the carotenoid structures due to the inherent thermal instability generally ascribed to these compounds. Instead of protonated molecules, both polar xanthophylls and nonpolar carotenes formed molecular ions, M{sup {center_dot}+}, during FAB ionization. Following collisionally activated dissociation, fragment ions of selected molecular ion precursors showed structural features indicative of the presence of hydroxyl groups, ring systems, ester groups, and aldehyde groups and the extent of aliphatic polyene conjugation. The fragmentation patterns observed in the mass spectra herein may be used as a reference for the structural determination of carotenoids isolated from plant and animal tissues. 18 refs., 4 figs.

  18. The POPOP4 library and codes for preparing secondary gamma-ray production cross sections

    NASA Technical Reports Server (NTRS)

    Ford, W. E., III

    1972-01-01

    The POPOP4 code for converting secondary gamma ray yield data to multigroup secondary gamma ray production cross sections and the POPOP4 library of secondary gamma ray yield data are described. Recent results of the testing of uranium and iron data sets from the POPOP4 library are given. The data sets were tested by comparing calculated secondary gamma ray pulse height spectra measured at the ORNL TSR-II reactor.

  19. The Self-Shielding of Fallout Gamma Rays by Terrain Roughness

    DTIC Science & Technology

    1991-02-28

    Monte C, ORNL/TM-9355, Oak Ridge National Laboratory, Oak Ridge, TN, 1985. 98 7. Emmett, M. B., General Purpose Monte Carlo Multigroup Neutron and Gamma...I 28 FEBRUARY 1991 Di~t 3; or A v o p Approved for public release; distribution unlimited .- - i. ... .. F...model the fallout gamma source distribution , it will be modelled as an infinite plane source with gamma emission rates (GER) and gamma energy spectra as

  20. Spatial distribution of gamma radiation levels in surface soils from Jaduguda uranium mineralization zone, Jharkhand, India, using γ-ray spectrometry, and determination of outdoor dose to the population

    PubMed Central

    Maharana, Mandakini; Krishnan, Narayani; Sengupta, D.

    2010-01-01

    The concentrations of natural radionuclides in surface soil samples around selected villages of Jaduguda were investigated and compared with the radioactivity level in the region. Concentrations of 238U, 232Th, and 40K were determined by a gamma ray spectrometer using the HPGe detector with 50% relative efficiency, and the radiation dose to the local population was estimated. The average estimated activity concentrations of 238U, 232Th, and 40K in the surface soil were 53.8, 44.2 and 464.2 Bq kg−1 respectively. The average absorbed dose rate in the study area was estimated to be 72.5 nGy h-1, where as the annual effective dose to the population was 0.09 mSv y-1. A correlation analysis was made between measured dose rate and individual radionuclides, in order to delineate the contribution of the respective nuclides towards dose rate. The radio-elemental concentrations of uranium, thorium and potassium estimated for the soils, in the study area, indicated the enrichment of uranium series nuclide. The results of the present study were subsequently compared with international and national recommended values. PMID:21170189

  1. Gamma ray generator

    SciTech Connect

    Firestone, Richard B; Reijonen, Jani

    2014-05-27

    An embodiment of a gamma ray generator includes a neutron generator and a moderator. The moderator is coupled to the neutron generator. The moderator includes a neutron capture material. In operation, the neutron generator produces neutrons and the neutron capture material captures at least some of the neutrons to produces gamma rays. An application of the gamma ray generator is as a source of gamma rays for calibration of gamma ray detectors.

  2. NaI detector neutron activation spectra for PGNAA applications

    PubMed

    Gardner; El; Zheng; Hayden; Mayo

    2000-10-01

    When NaI detectors are used in prompt gamma-ray neutron activation analysis devices, they are activated by neutrons that penetrate the detector. While thermal neutron filters like boron or lithium can be used to reduce this activation, it can never be completely eliminated by this approach since high energy neutrons can penetrate the detector and thermalize inside it. This activation results in the emission of prompt gamma rays from both the I and Na and the production of the radioisotopes 128I and 24Na that subsequently decay and emit their characteristic beta particles and gamma rays. The resulting three spectra represent a background for this measurement. An experimental method for obtaining these three spectra is described and results are reported for 2" x 2", 5" x 5", 6" x 6", and 1" x 6" NaI detectors using the thermal neutron beam of the NCSU PULSTAR nuclear reactor. In addition, Monte Carlo simulation programs have been developed and used for simulating these spectra. Good results have been obtained by the Monte Carlo method for the two radioisotope spectra, and it is anticipated that good results will also be obtained for the prompt gamma-ray spectrum when the I and Na coincidence schemes are known.

  3. IUE spectra of F and late A stars

    NASA Technical Reports Server (NTRS)

    Linsky, J. L.; Marstad, N. C.

    1981-01-01

    The International Ultraviolet Explorer (IUE) spectra of alpha CMi (F5 IV-V), beta Cas (F2 IV), alpha Car (F0 Ib), and gamma Boo (A7 III) in the context of the question as to whether chromospheres disappear in the early F late A portions of the Hertzsprung-Russell diagram. Both alpha CMi (Procyon) and beta Cas show bright emission line spectra indicative of chromospheres and transition regions, but neither alpha Car (Canopus) nor gamma Boo show any evidence of emission in their SWP spectra or at the Mg II lines, despite very deep exposures. Alpha CMi has emission line fluxes roughly 6 times those of the quiet Sun, but the rapidly rotating delta Scuti type variable beta Cas has surface fluxes 10 to 50 times those of the quiet Sun. Upper limits on emission line fluxes for alpha Car are 4 to 20 and for gamma Boo 15 to 80 times the quiet Sun. It is concluded that the apparent absence of emission lines in the spectra of alpha Car and gamma Boo should not be interpreted as due to the absence of nonradiatively heated outer atmospheres in stars hotter than spectral type F0, but rather to the inability to see emission lines with IUE against a background of scattered light and a bright photospheric absorption line spectrum either in low or high dispersion.

  4. Laser Ablation Molecular Isotopic Spectrometry

    NASA Astrophysics Data System (ADS)

    Russo, Richard E.; Bol'shakov, Alexander A.; Mao, Xianglei; McKay, Christopher P.; Perry, Dale L.; Sorkhabi, Osman

    2011-02-01

    A new method of performing optical isotopic analysis of condensed samples in ambient air and at ambient pressure has been developed: Laser Ablation Molecular Isotopic Spectrometry (LAMIS). The technique uses radiative transitions from molecular species either directly vaporized from a sample or formed by associative mechanisms of atoms or ions in a laser ablation plume. This method is an advanced modification of a known atomic emission technique called laser-induced breakdown spectroscopy (LIBS). The new method — LAMIS — can determine not only chemical composition but also isotopic ratios of elements in the sample. Isotopic measurements are enabled by significantly larger isotopic shifts found in molecular spectra relative to atomic spectra. Analysis can be performed from a distance and in real time. No sample preparation or pre-treatment is required. Detection of the isotopes of hydrogen, boron, carbon, and oxygen are discussed to illustrate the technique.

  5. Review of spent-fuel photon and neutron source spectra

    SciTech Connect

    Hermann, O.W.; Alexander, C.W.

    1986-01-01

    The calculations of spent-fuel photon and neutron spectra have been significantly improved over the past several years. Methods for performing these computations at ORNL have been implemented in the ORIGEN2 and ORIGEN-S codes and the SAS2 control module of the SCALE system. The codes use photon data for delayed gamma rays, x-rays, spontaneous fission gamma rays, (..cap alpha..,n) reaction gamma rays, bremsstrahlung and decay constants, taken mainly from the Evaluated Nuclear Data Structure File. The data for neutron source strengths and spectral distributions of spontaneous fission and (..cap alpha..,n) reactions were compiled from several different research projects. Brief discussions of the codes, the spectral data and the range of applicability are presented. Also, several examples of spent-fuel photon and neutron spectra are included. 29 refs.

  6. Lily Pad Spectra

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The color image on the lower left from the panoramic camera on the Mars Exploration Rover Opportunity shows the 'Lily Pad' bounce-mark area at Meridiani Planum, Mars. This image was acquired on the 3rd sol, or martian day, of Opportunity's mission (Jan.26, 2004). The upper left image is a monochrome (single filter) image from the rover's panoramic camera, showing regions from which spectra were extracted from the 'Lily Pad' area. As noted by the line graph on the right, the green spectra is from the undisturbed surface and the red spectra is from the airbag bounce mark.

  7. Equipment for the continuous measurement and identification of 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

    Presentation the Equipment for the Continuous Measurement and Identification of Gamma Radioactivity on Aerosols developed by the Nuclear Engineering Research Group (NERG) from the Technical University of Catalonia (UPC) and the Raditel Company. The device is based on a fixed filter of glass fiber (100% borosilicate), this allows determine the concentration of activity of gamma emitters on aerosols in air. A specifically developed Spectrometry Analysis System has been developed. The analysis of the spectra allows the identification of the emitters and determine the concentration of activity. Nowadays four Stations with this equipment are operating on the Environmental Radiological Surveillance Network of the Catalonian Generalitat (Spain): two near the Asco and Vandellos Nuclear Power Plants in the province of Tarragona and one in the city of Barcelona. Soon a fourth monitor will be incorporated at Roses (province of Girona) and a fifth in Puigcerda (province of Barcelona). We present measurements and analysis of the evolution of the emitters identified on different stations of the Network. (authors)

  8. Formation of an 8-hydroxyguanine moiety in deoxyribonucleic acid on gamma-irradiation in aqueous solution

    SciTech Connect

    Dizdaroglu, M.

    1985-07-30

    Isolation and characterization of a novel radiation-induced product, i.e., the 8-hydroxyguanine residue, produced in deoxyribonucleic acid (DNA), 2'-deoxyguanosine, and 2'-deoxyguanosine 5'-monophosphate by gamma-irradiation in aqueous solution, are described. For this purpose, gamma-irradiated DNA was first hydrolyzed with a mixture of four enzymes, i.e., DNase I, spleen and snake venom exonucleases, and alkaline phosphatase. Analysis of the resulting mixture by capillary gas chromatography-mass spectrometry after trimethylsilylation revealed the presence of a product, which was identified as 8-hydroxy-2'-deoxyguanosine on the basis of the typical fragment ions of its trimethylsilyl (Me3Si) derivative. This product was then isolated by using reversed-phase high-performance liquid chromatography. The UV and proton nuclear magnetic resonance spectra taken from the isolated product confirmed the structure suggested by the mass spectrum of its Me3Si derivative. The yield of 8-hydroxyguanine was also measured. Its mechanism of formation is believed to involve OH radical addition to the C-8 position of guanine followed by oxidation of the radical adduct.

  9. Gamma radiation background measurements from Spacelab 2

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.; Gregory, John C.; Fishman, Gerald J.

    1988-01-01

    A Nuclear Radiation Monitor incorporating a NaI(Tl) scintillation detector was flown as part of the verification flight instrumentation on the Spacelab 2 mission, July 29 to August 6, 1985. Gamma-ray spectra were measured with better than 20 s resolution throughout most of the mission in the energy range 0.1 to 30 MeV. Knowledge of the decay characteristics and the geomagnetic dependence of the counting rates enable measurement of the various components of the Spacelab gamma-ray background: prompt secondary radiation, Earth albedo, and delayed induced radioactivity. The status of the data analysis and present relevant examples of typical background behavior are covered.

  10. Method of incident low-energy gamma-ray direction reconstruction in the GAMMA-400 gamma-ray space telescope

    NASA Astrophysics Data System (ADS)

    Kheymits, M. D.; Leonov, A. A.; Zverev, V. G.; Galper, A. M.; Arkhangelskaya, I. V.; Arkhangelskiy, A. I.; Suchkov, S. I.; Topchiev, N. P.; Yurkin, Yu T.; Bakaldin, A. V.; Dalkarov, O. D.

    2016-02-01

    The GAMMA-400 gamma-ray space-based telescope has as its main goals to measure cosmic γ-ray fluxes and the electron-positron cosmic-ray component produced, theoretically, in dark-matter-particles decay or annihilation processes, to search for discrete γ-ray sources and study them in detail, to examine the energy spectra of diffuse γ-rays — both galactic and extragalactic — and to study gamma-ray bursts (GRBs) and γ-rays from the active Sun. Scientific goals of GAMMA-400 telescope require fine angular resolution. The telescope is of a pair-production type. In the converter-tracker, the incident gamma-ray photon converts into electron-positron pair in the tungsten layer and then the tracks are detected by silicon- strip position-sensitive detectors. Multiple scattering processes become a significant obstacle in the incident-gamma direction reconstruction for energies below several gigaelectronvolts. The method of utilising this process to improve the resolution is proposed in the presented work.

  11. Recent progress in low-level gamma imaging

    SciTech Connect

    Mahe, C.; Girones, Ph.; Lamadie, F.; Le Goaller, C.

    2007-07-01

    The CEA's Aladin gamma imaging system has been operated successfully for several years in nuclear plants and during decommissioning projects with additional tools such as gamma spectrometry detectors and dose rate probes. The radiological information supplied by these devices is becoming increasingly useful for establishing robust and optimized decommissioning scenarios. Recent technical improvements allow this gamma imaging system to be operated in low-level applications and with shorter acquisition times suitable for decommissioning projects. The compact portable system can be used in places inaccessible to operators. It is quick and easy to implement, notably for onsite component characterization. Feasibility trials and in situ measurements were recently carried out under low-level conditions, mainly on waste packages and glove boxes for decommissioning projects. This paper describes recent low-level in situ applications. These characterization campaigns mainly concerned gamma emitters with {gamma} energy < 700 keV. In many cases, the localization of hot spots by gamma camera was confirmed by additional measurements such as dose rate mapping and gamma spectrometry measurements. These complementary techniques associated with advanced calculation codes (MCNP, Mercure 6.2, Visiplan and Siren) offer a mobile and compact tool for specific assessment of waste packages and glove boxes. (authors)

  12. Nebular spectra of pair-instability supernovae

    NASA Astrophysics Data System (ADS)

    Jerkstrand, A.; Smartt, S. J.; Heger, A.

    2016-01-01

    If very massive stars (M ≳ 100 M⊙) can form and avoid too strong mass-loss during their evolution, they are predicted to explode as pair-instability supernovae (PISNe). One critical test for candidate events is whether their nucleosynthesis yields and internal ejecta structure, being revealed through nebular-phase spectra at t ≳ 1 yr, match those of model predictions. Here, we compute theoretical spectra based on model PISN ejecta at 1-3 yr post-explosion to allow quantitative comparison with observations. The high column densities of PISNe lead to complete gamma-ray trapping for t ≳ 2 yr which, combined with fulfilled conditions of steady state, leads to bolometric supernova luminosities matching the 56Co decay. Most of the gamma-rays are absorbed by the deep-lying iron and silicon/sulphur layers. The ionization balance shows a predominantly neutral gas state, which leads to emission lines of Fe I, Si I, and S I. For low-mass PISNe, the metal core expands slowly enough to produce a forest of distinct lines, whereas high-mass PISNe expand faster and produce more featureless spectra. Line blocking is complete below ˜5000 Å for several years, and the model spectra are red. The strongest line is typically [Ca II] λλ7291, 7323, one of few lines from ionized species. We compare our models with proposed PISN candidates SN 2007bi and PTF12dam, finding discrepancies for several key observables and thus no support for a PISN interpretation. We discuss distinct spectral features predicted by the models, and the possibility of detecting pair-instability explosions among non-superluminous supernovae.

  13. Application of nondestructive gamma-ray and neutron techniques for the safeguarding of irradiated fuel materials

    SciTech Connect

    Phillips, J.R.; Halbig, J.K.; Lee, D.M.; Beach, S.E.; Bement, T.R.; Dermendjiev, E.; Hatcher, C.R.; Kaieda, K.; Medina, E.G.

    1980-05-01

    Nondestructive gamma-ray and neutron techniques were used to characterize the irradiation exposures of irradiated fuel assemblies. Techniques for the rapid measurement of the axial-activity profiles of fuel assemblies have been developed using ion chambers and Be(..gamma..,n) detectors. Detailed measurements using high-resolution gamma-ray spectrometry and passive neutron techniques were correlated with operator-declared values of cooling times and burnup.

  14. Physical Performance of GAMMA-400 Telescope. Angular Resolution, Proton and Electron Separation

    NASA Astrophysics Data System (ADS)

    Leonov, A. A.; Galper, A. O. Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Gusakov, Y. V.; Kadilin, V. V.; Kheymits, M. D.; Mikhailov, V. V.; Naumov, P. Y.; Runtso, M. F.; Suchkov, S. I.; Topchiev, N. P.; Yurkin, Y. T.; Zverev, V. G.

    The specially designed GAMMA-400 gamma-ray telescope will realize the measurements of gamma-ray fluxes and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. Such measurements concern with the following broad range of scientific topics. Search for signatures of dark matter, investigation of gamma-ray point and extended sources, studies of the energy spectra of Galactic and extragalactic diffuse emission, studies of gamma-ray bursts and gamma-ray emission from the active Sun, as well as high-precision measurements of spectra of high-energy electrons and positrons, protons, and nuclei up to the knee. To clarify these scientific problems with the new experimental data the GAMMA-400 gamma-ray telescope possesses unique physical characteristics comparing with previous and present experiments. For gamma-ray energies more than 100 GeV GAMMA-400 provides the energy resolution ∼1% and angular resolution better than 0.02 deg. The methods, developed to reconstruct the direction of incident gamma photon, are presented in this paper, as well as, the capability of the GAMMA-400 gamma-ray telescope to distinguish electrons and positrons from protons in cosmic rays is discussed.

  15. Cross Sections for (gamma)-ray Production in the 191Ir (n,xn(gamma)) Reactions

    SciTech Connect

    Fotiades, N; Nelson, R O; Devlin, M; Chadwick, M B; Talou, P; Becker, J A; Garrett, P E; Younes, W

    2005-01-11

    Discrete {gamma}-ray spectra have been measured for nuclei populated in {sup 191}Ir(n{sub 4}xn{gamma}) with x{<=}11, as a function of incident neutron energy using neutrons from the 'white' neutron source at the Los Alamos Neutron Science Center's WNR facility. The energy of the neutrons was determined using the time-of-flight technique. The data were taken using the GEANIE spectrometer. The cross sections for emission of 202 {gamma} rays of {sup 181-191}Ir were determined for neutron energies 0.2 MeV < E{sub n} < 300 MeV. Comparison with model calculations, using the GNASH reaction model, and with GEANIE results from the similar {sup 193}Ir(n{sub 4}xn{gamma}) reactions is made.

  16. Gamma-ray Albedo of the Moon

    SciTech Connect

    Moskalenko, Igor V.; Porter, Troy A.

    2007-06-14

    We use the GEANT4 Monte Carlo framework to calculate the gamma-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of gamma-rays from the Moon is very steep with an effective cutoff around 3 GeV (600 MeV for the inner part of the Moon disc). Since it is the only (almost) black spot in the gamma-ray sky, it provides a unique opportunity for calibration of gamma-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). The albedo flux depends on the incident CR spectrum which changes over the solar cycle. Therefore, it is possible to monitor the CR spectrum using the albedo gamma-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo -rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the GLAST LAT to monitor the CR spectrum near the Earth beyond the lifetime of PAMELA.

  17. gamma-Hexachlorocyclohexane (gamma-HCH)

    Integrated Risk Information System (IRIS)

    gamma - Hexachlorocyclohexane ( gamma - HCH ) ; CASRN 58 - 89 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Asse

  18. The multiplicity and the spectra of secondaries correlated with the leading particle energy

    NASA Technical Reports Server (NTRS)

    Kruglov, N. A.; Proskuryakov, A. S.; Sarycheva, L. I.; Smirnova, L. N.

    1985-01-01

    The spectra of leading particles of different nature in pp-collisions at E sub 0 = 33 GeV are obtained. The multiplicities and the spectra of secondaries, mesons, gamma-quanta, lambda and lambda-hyperons and protons for different leading particle energy ranges are determined.

  19. Unthermalized positrons in gamma ray burst sources

    NASA Technical Reports Server (NTRS)

    Tkaczyk, W.; Karakula, S.

    1992-01-01

    The spectra of the broadening 0.511 MeV annihilation line produced by high temperatures was calculated in the case of unthermalized plasma; i.e., T sub e(+) is not = T sub e(-). The flattening in the spectrum of the annihilation lines for large differences of electron and positron temperatures is a strong indication that the observed features of the hard tailed spectrum of the gamma bursts can be well described by annihilation of unthermalized positrons. It is proposed that the charge separation occurring in Eddington limited accretion onto a neutron star or the one photon pair production in strong magnetic fields as a mechanism for the production of unthermalized positrons in the sources of gamma bursts. From the best fit of experimental spectra by the model, the parameters of sources for which the regions with different plasma temperatures can exist is evaluated.

  20. Gamma ray bursts: a 1983 overview

    SciTech Connect

    Cline, T.L.

    1983-10-01

    Gamma ray burst observations are reviewed with mention of new gamma-ray and optical transient measurements and with discussions of the controversial, contradictory and unresolved issues that have recently emerged: burst spectra appear to fluctuate in time as rapidly as they are measured, implying that any one spectrum may be incorrect. Energy spectra can be obligingly fitted to practically any desired shape, implying, in effect, that no objective spectral resolution exists at all. Burst fluxes and temporal quantities, including the total event energy, are characterized very differently with differing instruments, implying that even elementary knowledge of their properties is instrumentally subjective. Finally, the log N-log S determinations are deficient in the weak bursts, while there is no detection of a source direction anisotropy, implying that Ptolemy was right or that burst source distance estimates are basically guesswork. These issues may remain unsolved until vastly improved instruments are flown.

  1. Gamma Ray Bursts: a 1983 Overview

    NASA Technical Reports Server (NTRS)

    Cline, T. L.

    1983-01-01

    Gamma ray burst observations are reviewed with mention of new gamma-ray and optical transient measurements and with discussions of the controversial, contradictory and unresolved issues that have recently emerged: burst spectra appear to fluctuate in time as rapidly as they are measured, implying that any one spectrum may be incorrect; energy spectra can be obligingly fitted to practically any desired shape, implying, in effect, that no objective spectral resolution exists at all; burst fluxes and temporal quantities, including the total event energy, are characterized very differently with differing instruments, implying that even elementary knowledge of their properties is instrumentally subjective; finally, the log N-log S determinations are deficient in the weak bursts, while there is no detection of a source direction anisotropy, implying that Ptolemy was right or that burst source distance estimates are basically guesswork. These issues may remain unsolved until vastly improved instruments are flown.

  2. Separation of electrons and protons in the GAMMA-400 gamma-ray telescope

    NASA Astrophysics Data System (ADS)

    Leonov, A. A.; Galper, A. M.; Bonvicini, V.; Topchiev, N. P.; Adriaini, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Bergstrom, L.; Berti, E.; Bigongiari, G.; Bobkov, S. G.; Boezio, M.; Bogomolov, E. A.; Bonechi, S.; Bongi, M.; Bottai, S.; Castellini, G.; Cattaneo, P. W.; Cumani, P.; Dedenko, G. L.; De Donato, C.; Dogiel, V. A.; Gorbunov, M. S.; Gusakov, Yu. V.; Hnatyk, B. I.; Kadilin, V. V.; Kaplin, V. A.; Kaplun, A. A.; Kheymits, M. D.; Korepanov, V. E.; Larsson, J.; Loginov, V. A.; Longo, F.; Maestro, P.; Marrocchesi, P. S.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu.; Papini, P.; Pearce, M.; Picozza, P.; Rappoldi, A.; Ricciarini, S.; Runtso, M. F.; Ryde, F.; Serdin, O. V.; Sparvoli, R.; Spillantini, P.; Suchkov, S. I.; Taraskin, A. A.; Tavani, M.; Tiberio, A.; Tyurin, E. M.; Ulanov, M. V.; Vacchi, A.; Vannuccini, E.; Vasilyev, G. I.; Yurkin, Yu. T.; Zampa, N.; Zirakashvili, V. N.; Zverev, V. G.

    2015-10-01

    The GAMMA-400 telescope will measure the fluxes of gamma rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. These measurements will allow it to achieve the following scientific objectives: search for signatures of dark matter, investigation of gamma-ray point-like and extended sources, study of the energy spectrum of the Galactic and extragalactic diffuse emission, study of gamma-ray bursts and gamma-ray emission from the active Sun, together with high-precision measurements of the high-energy electrons and positrons spectra, protons and nuclei up to the knee. The bulk of cosmic rays are protons and helium nuclei, whereas the lepton component in the total flux is ∼10-3 at high energy. In the present paper, the simulated capability of the GAMMA-400 telescope to distinguish electrons and positrons from protons in cosmic rays is addressed. The individual contribution to the proton rejection from each detector system of GAMMA-400 is studied separately. The use of the combined information from all detectors allows us to reach a proton rejection of the order of ∼4 × 105 for vertical incident particles and ∼3 × 105 for particles with initial inclination of 30° in the electron energy range from 50 GeV to 1 TeV.

  3. Photon-photon absorption and the uniqueness of the spectra of active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Kazanas, D.

    1984-01-01

    The effects of the feedback of e(+)-e(-) pair reinjection in a plasma due to photon-photon absorption of its own radiation was examined. Under the assumption of continuous electron injection with a power law spectrum E to the minus gamma power and Compton losses only, it is shown that for gamma 2 the steady state electron distribution function has a unique form independent of the primary injection spectrum. This electron distribution function can, by synchrotron emission, reproduce the general characteristics of the observed radio to optical active galactic nuclei spectra. Inverse Compton scattering of the synchrotron photons by the same electron distribution can account for their X-ray spectra, and also implies gamma ray emission from these objects. This result is invoked to account for the similarity of these spectra, and it is consistent with observations of the diffuse gamma ray background.

  4. (n,{gamma}) Experiments on tin isotopes

    SciTech Connect

    Baramsai, B.; Mitchell, G. E.; Walker, C. L.; Rusev, G.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Mosby, S.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Becvar, F.; Krticka, M.; Kroll, J.; Agvaanluvsan, U.; Dashdorj, D.; Erdenehuluun, B.; Tsend-Ayush, T.

    2013-04-19

    Neutron capture experiments on highly enriched {sup 117,119}Sn isotopes were performed with the DANCE detector array located at the Los Alamos Neutron Science Center. The DANCE detector provides detailed information about the multi-step {gamma}-ray cascade following neutron capture. Analysis of the experimental data provides important information to improve understanding of the neutron capture reaction, including a test of the statistical model, the assignment of spins and parities of neutron resonances, and information concerning the Photon Strength Function (PSF) and Level Density (LD) below the neutron separation energy. Preliminary results for the (n,{gamma}) reaction on {sup 117,119}Sn are presented. Resonance spins of the odd-A tin isotopes were almost completely unknown. Resonance spins and parities have been assigned via analysis of the multi-step {gamma}-ray spectra and directional correlations.

  5. Spectra of Surface Waves

    DTIC Science & Technology

    1989-03-22

    with a wave follower during Marsen. J. Gophysical Res. 88, 9844-9849. 11. Hughes, B.A., 1978. The effects on internal waves on surface waves : 2...Spectra of Surface Waves K. Watson March 1989 JSR-88-130 Approved for public release; distribution unlimited. DTIC SELECTE JUN0 11989 0 JASONE The...Arlington, VA 22209 8503Z 11. TITLE (hlde Secvfty Cof.kaftn) SPECTRA OF SURFACE WAVES (U) 12. PERSONAL AUTHOfRS) K. Watson 13a. TYPE OF REPORT 13b. TIME

  6. Single-protein nanomechanical mass spectrometry in real time

    PubMed Central

    Hanay, M.S.; Kelber, S.; Naik, A.K.; Chi, D.; Hentz, S.; Bullard, E.C.; Colinet, E.; Duraffourg, L.; Roukes, M.L.

    2012-01-01

    Nanoelectromechanical systems (NEMS) resonators can detect mass with exceptional sensitivity. Previously, mass spectra from several hundred adsorption events were assembled in NEMS-based mass spectrometry using statistical analysis. Here, we report the first realization of single-molecule NEMS-based mass spectrometry in real time. As each molecule in the sample adsorbs upon the NEMS resonator, its mass and the position-of-adsorption are determined by continuously tracking two driven vibrational modes of the device. We demonstrate the potential of multimode NEMS-based mass spectrometry by analyzing IgM antibody complexes in real-time. NEMS-MS is a unique and promising new form of mass spectrometry: it can resolve neutral species, provides resolving power that increases markedly for very large masses, and allows acquisition of spectra, molecule-by-molecule, in real-time. PMID:22922541

  7. EGRET detection of high energy gamma rays from the gamma-ray burst of 3 May 1991

    NASA Technical Reports Server (NTRS)

    Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

    1992-01-01

    On May 3, 1991, the Energetic Gamma Ray Experiment Telescope on the Compton Gamma Ray Observatory detected a gamma-ray burst both in the energy measurement subsystem and independently in the spark chamber assembly. Six individual photons were detected in the spark chamber, allowing a determination of the burst arrival direction which was l(II) = 171.9 deg +/- 1.3 deg, b(II) = 5.3 deg +/- 1.1 deg. Three energy spectra were measured from 1 to 200 MeV; they were measured during the first second after the Burst and Transient Sources Experiment trigger, the next two seconds, and the subsequent four seconds. The first two spectra exhibit a similar differential spectra index of about -2.2 with no apparent high-energy cut-off. By the time of the third spectrum, an additional soft component is evident.

  8. Rehabilitation of gamma

    NASA Astrophysics Data System (ADS)

    Poynton, Charles A.

    1998-07-01

    Gamma characterizes the reproduction of tone scale in an imaging system. Gamma summarizes, in a single numerical parameter, the nonlinear relationship between code value--in an 8-bit system, from 0 through 255--and physical intensity. Nearly all image coding systems are nonlinear, and so involve values of gamma different from unity. Owing to poor understanding of tone scale reproduction, and to misconceptions about nonlinear coding, gamma has acquired a terrible reputation in computer graphics and image processing. In addition, the world-wide web suffers from poor reproduction of grayscale and color images, due to poor handling of nonlinear image coding. This paper aims to make gamma respectable again.

  9. High-Resolution Fast-Neutron Spectrometry for Arms Control and Treaty Verification

    SciTech Connect

    David L. Chichester; James T. Johnson; Edward H. Seabury

    2012-07-01

    Many nondestructive nuclear analysis techniques have been developed to support the measurement needs of arms control and treaty verification, including gross photon and neutron counting, low- and high-resolution gamma spectrometry, time-correlated neutron measurements, and photon and neutron imaging. One notable measurement technique that has not been extensively studied to date for these applications is high-resolution fast-neutron spectrometry (HRFNS). Applied for arms control and treaty verification, HRFNS has the potential to serve as a complimentary measurement approach to these other techniques by providing a means to either qualitatively or quantitatively determine the composition and thickness of non-nuclear materials surrounding neutron-emitting materials. The technique uses the normally-occurring neutrons present in arms control and treaty verification objects of interest as an internal source of neutrons for performing active-interrogation transmission measurements. Most low-Z nuclei of interest for arms control and treaty verification, including 9Be, 12C, 14N, and 16O, possess fast-neutron resonance features in their absorption cross sections in the 0.5- to 5-MeV energy range. Measuring the selective removal of source neutrons over this energy range, assuming for example a fission-spectrum starting distribution, may be used to estimate the stoichiometric composition of intervening materials between the neutron source and detector. At a simpler level, determination of the emitted fast-neutron spectrum may be used for fingerprinting 'known' assemblies for later use in template-matching tests. As with photon spectrometry, automated analysis of fast-neutron spectra may be performed to support decision making and reporting systems protected behind information barriers. This paper will report recent work at Idaho National Laboratory to explore the feasibility of using HRFNS for arms control and treaty verification applications, including simulations and

  10. Resting GABA and glutamate concentrations do not predict visual gamma frequency or amplitude

    PubMed Central

    Cousijn, Helena; Haegens, Saskia; Wallis, George; Near, Jamie; Stokes, Mark G.; Harrison, Paul J.; Nobre, Anna C.

    2014-01-01

    Gamma band oscillations arise in neuronal networks of interconnected GABAergic interneurons and excitatory pyramidal cells. A previous study found a correlation between visual gamma peak frequency, as measured with magnetoencephalography, and resting GABA levels, as measured with magnetic resonance spectroscopy (MRS), in 12 healthy volunteers. If true, this would allow studies in clinical populations testing modulation of this relationship, but this finding has not been replicated. We addressed this important question by measuring gamma oscillations and GABA, as well as glutamate, in 50 healthy volunteers. Visual gamma activity was evoked using an established gratings paradigm, and we applied a beamformer spatial filtering technique to extract source-reconstructed gamma peak frequency and amplitude from the occipital lobe. We determined gamma peak frequency and amplitude from the location with maximal activation and from the location of the MRS voxel to assess the relationship of GABA with gamma. Gamma peak frequency was estimated from the highest value of the raw spectra and by a Gaussian fit to the spectra. MRS data were acquired from occipital cortex. We did not replicate the previously found correlation between gamma peak frequency and GABA concentration. Calculation of a Bayes factor provided strong evidence in favor of the null hypothesis. We also did not find a correlation between gamma activity and glutamate or between gamma and the ratio of GABA/glutamate. Our results suggest that cortical gamma oscillations do not have a consistent, demonstrable relationship to excitatory/inhibitory network activity as proxied by MRS measurements of GABA and glutamate. PMID:24927588

  11. Beamstrahlung spectra in next generation linear colliders. Revision

    SciTech Connect

    Barklow, T.; Chen, P.; Kozanecki, W.

    1992-04-01

    For the next generation of linear colliders, the energy loss due to beamstrahlung during the collision of the e{sup +}e{sup {minus}} beams is expected to substantially influence the effective center-of-mass energy distribution of the colliding particles. In this paper, we first derive analytical formulae for the electron and photon energy spectra under multiple beamstrahlung processes, and for the e{sup +}e{sup {minus}} and {gamma}{gamma} differential luminosities. We then apply our formulation to various classes of 500 GeV e{sup +}e{sup {minus}} linear collider designs currently under study.

  12. Quantum spectra and dynamics

    NASA Astrophysics Data System (ADS)

    Arce, Julio Cesar

    This work focuses on time-dependent quantum theory and methods for the study of the spectra and dynamics of atomic and molecular systems. Specifically, we have addressed the following two problems: (1) Development of a time-dependent spectral method for the construction of spectra of simple quantum systems. This includes the calculation of eigenenergies, the construction of bound and continuum eigenfunctions, and the calculation of photo cross-sections. Computational applications include the quadrupole photoabsorption spectra and dissociation cross-sections of molecular hydrogen from various vibrational states in its ground electronic potential-energy curve. This method is seen to provide an advantageous alternative, both from the computational and conceptual point of view, to existing standard methods. (2) Explicit time-dependent formulation of photoabsorption processes -- Analytical solutions of the time-dependent Schrodinger equation are constructed and employed for the calculation of probability densities, momentum distributions, fluxes, transition rates, expectation values and correlation functions. These quantities are seen to establish the link between the dynamics and the calculated, or measured, spectra and cross-sections, and to clarify the dynamical nature of the excitation, transition and ejection processes. Numerical calculations on atomic and molecular hydrogen corroborate and complement the previous results, allowing the identification of different regimes during the photoabsorption process.

  13. Quantum Spectra and Dynamics

    NASA Astrophysics Data System (ADS)

    Arce, Julio Cesar

    1992-01-01

    This work focuses on time-dependent quantum theory and methods for the study of the spectra and dynamics of atomic and molecular systems. Specifically, we have addressed the following two problems: (i) Development of a time-dependent spectral method for the construction of spectra of simple quantum systems--This includes the calculation of eigenenergies, the construction of bound and continuum eigenfunctions, and the calculation of photo cross-sections. Computational applications include the quadrupole photoabsorption spectra and dissociation cross-sections of molecular hydrogen from various vibrational states in its ground electronic potential -energy curve. This method is seen to provide an advantageous alternative, both from the computational and conceptual point of view, to existing standard methods. (ii) Explicit time-dependent formulation of photoabsorption processes --Analytical solutions of the time-dependent Schrodinger equation are constructed and employed for the calculation of probability densities, momentum distributions, fluxes, transition rates, expectation values and correlation functions. These quantities are seen to establish the link between the dynamics and the calculated, or measured, spectra and cross-sections, and to clarify the dynamical nature of the excitation, transition and ejection processes. Numerical calculations on atomic and molecular hydrogen corroborate and complement the previous results, allowing the identification of different regimes during the photoabsorption process.

  14. Atomic Spectra Database (ASD)

    National Institute of Standards and Technology Data Gateway

    SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

  15. Resonance production in. gamma gamma. collisions

    SciTech Connect

    Renard, F.M.

    1983-04-01

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

  16. The measurement of gamma ray induced heating in a mixed neutron and gamma ray environment

    SciTech Connect

    Chiu, H.K.

    1991-10-01

    The problem of measuring the gamma heating in a mixed DT neutron and gamma ray environment was explored. A new detector technique was developed to make this measurement. Gamma heating measurements were made in a low-Z assembly irradiated with 14-Mev neutrons and (n, n{prime}) gammas produced by a Texas Nuclear Model 9400 neutron generator. Heating measurements were made in the mid-line of the lattice using a proportional counter operating in the Continuously-varied Bias-voltage Acquisition mode. The neutron-induced signal was separated from the gamma-induced signal by exploiting the signal rise-time differences inherent to radiations of different linear energy transfer coefficient, which are observable in a proportional counter. The operating limits of this measurement technique were explored by varying the counter position in the low-Z lattice, hence changing the irradiation spectrum observed. The experiment was modelled numerically to help interpret the measured results. The transport of neutrons and gamma rays in the assembly was modelled using the one- dimensional radiation transport code ANISN/PC. The cross-section set used for these calculations was derived from the ENDF/B-V library using the code MC{sup 2}-2 for the case of DT neutrons slowing down in a low-Z material. The calculated neutron and gamma spectra in the slab and the relevant mass-stopping powers were used to construct weighting factors which relate the energy deposition in the counter fill-gas to that in the counter wall and in the surrounding material. The gamma energy deposition at various positions in the lattice is estimated by applying these weighting factors to the measured gamma energy deposition in the counter at those locations.

  17. Cross sections and differential spectra for reactions of 2-20 MeV neutrons of /sup 27/Al

    SciTech Connect

    Blann, M.; Komoto, T.T.

    1988-01-01

    This report summarizes product yields, secondary n,p and ..cap alpha.. spectra, and ..gamma..-ray spectra calculated for incident neutrons of 2-20 MeV on /sup 27/Al targets. Results are all from the code ALICE, using the version ALISO which does weighting of results for targets which are a mix of isotopes. Where natural isotopic targets are involved, yields and n,p,..cap alpha.. spectra will be reported weighted over isotopic yields. Gamma-ray spectra, however, will be reported for the most abundant isotope.

  18. Formation of gamma(sup prime)-Ni3Al via the Peritectoid Reaction: gamma + beta (+ Al2O3)=gamma(sup prime)(+ Al2O3)

    NASA Technical Reports Server (NTRS)

    Copeland, Evan

    2008-01-01

    The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8-32 at.%Al and temperature range T=1400-1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma(sup prime)-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3)=gamma + Beta(+ Al2O3), at 1640 +/- 1 K and a liquid composition of 24.8 +/- 0.2 at.%al (at an unknown oxygen content). The {gamma + Beta (+Al2O3} phase field is stable over the temperature range 1633-1640 K, and gamma(sup prime)-Ni3Al forms via the peritectoid, gamma + Beta (+ Al2O3)=gamma(sup prime) (+ Al2O3), at 1633 +/- 1 K. This behavior is consistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady-state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma(sup prime)-Ni2Al phase field.

  19. Formation of gamma'-Ni3Al via the Peritectoid Reaction: gamma plus beta (+Al2O3) equals gamma'(+Al2O3)

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2008-01-01

    The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8 - 32 at.%Al and temperature range T = 1400 - 1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma'-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3) = gamma + beta (+ Al2O3), at 1640 plus or minus 1 K and a liquid composition of 24.8 plus or minus 0.2 at.%Al (at an unknown oxygen content). The {gamma + beta + Al2O3} phase field is stable over the temperature range 1633 - 1640 K, and gamma'-Ni3Al forms via the peritectiod, gamma + beta (+ Al2O3) = gamma'(+ Al2O3), at 1633 plus or minus 1 K. This behavior is inconsistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma'-Ni3Al phase field.

  20. 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.

  1. Dual Gamma Neutron Directional Elpasolite Detector

    SciTech Connect

    Guss, P. P.; Mukhopadhyay, S.

    2013-09-01

    Some applications, particularly in homeland security, require detection of both neutron and gamma radiation. Typically, this is accomplished with a combination of two detectors registering neutrons and gammas separately. We have investigated a new type of neutron/gamma (n/γ) directional detection capability. We explored a new class of scintillator, cerium (Ce)-doped Elpasolites such as Cs2LiYCl6:Ce (CLYC), Cs2LiLaCl6 (CLLC), Cs2LiLaBr6:Ce (CLLB), or Cs2LiYBr6:Ce (CLYB). These materials are capable of providing energy resolution as good as 2.9% at 662 keV (FWHM), which is better than that of NaI:Tl. Because they contain 6Li, Elpasolites can also detect thermal neutrons. In the energy spectra, the full energy thermal neutron peak appears near or above 3 GEEn MeV. Thus, very effective pulse height discrimination is possible. In addition, the core-to-valence luminescence (CVL) provides Elpasolites with different temporal responses under gamma and neutron excitation, and, therefore, may be exploited for effective pulse shape discrimination. For instance, the CLLC emission consists of two main components: (1) CVL spanning from 220 nm to 320 nm and (2) Ce emission found in the range of 350 to 500 nm. The former emission is of particular interest because it appears only under gamma excitation. It is also very fast, decaying with a 2 ns time constant. The n/γ discrimination capability of Elpasolite detectors may be optimized by tuning the cerium doping content for maximum effect on n/γ pulse shape differences. The resulting Elpasolite detectors have the ability to collect neutron and gamma data simultaneously, with excellent discrimination. Further, an array of four of these Elpasolites detectors will perform directional detection in both the neutron and gamma channels simultaneously.

  2. Elemental mapping of the moon using gamma rays : past, present, and future /

    SciTech Connect

    Reedy, R. C.

    2001-01-01

    The energies and intensities of gamma rays From a planetary surface can be used to infer the elemental composition of an object with no or a thin atmosphere. The Apollo gamma-ray spectrometers in 1972 and 1973 produced many of the results for the distribution of elements in the Moon that are now generally well accepted. Lunar Prospector in 1998 and 1999 globally mapped the Moon with gamma rays and neutrons. Both missions used spectrometers with poor energy resolution ({approx}8-10%). The Japanese plan to send a high-resolution germanium gamma-ray spectrometer to the Moon in about 2004 on their SELENE mission. However, little has been done since the 1970s on the models used to unfold planetary gamma-ray spectra. More work needs to be done on understanding what to expect in future gamma-ray spectra and how to unfold such data.

  3. Rock Outcrop Spectra

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The color image on the lower left shows a rock outcrop at Meridiani Planum, Mars. This image was taken by the panoramic camera on the Mars Exploration Rover Opportunity, looking north, and was acquired on the 4th sol, or martian day, of the rover's mission (Jan. 27, 2004). The yellow box outlines an area detailed in the top left image, which is a monochrome (single filter) image from the rover's panoramic camera. The top image uses solid colors to show several regions on or near the rock outcrop from which spectra were extracted: the dark soil above the outcrop (yellow), the distant horizon surface (aqua), a bright rock in the outcrop (green), a darker rock in the outcrop (red), and a small dark cobblestone (blue). Spectra from these regions are shown in the plot to the right.

  4. Fission Product Gamma-Ray Line Pairs Sensitive to Fissile Material and Neutron Energy

    SciTech Connect

    Marrs, R E; Norman, E B; Burke, J T; Macri, R A; Shugart, H A; Browne, E; Smith, A R

    2007-11-15

    The beta-delayed gamma-ray spectra from the fission of {sup 235}U, {sup 238}U, and {sup 239}Pu by thermal and near-14-MeV neutrons have been measured for delay times ranging from 1 minute to 14 hours. Spectra at all delay times contain sets of prominent gamma-ray lines with intensity ratios that identify the fissile material and distinguish between fission induced by low-energy or high-energy neutrons.

  5. Modifications of a method for low energy gamma-ray incident angle reconstruction in the GAMMA-400 gamma-ray telescope

    NASA Astrophysics Data System (ADS)

    Leonov, A. A.; Galper, A. M.; Topchiev, N. P.; Bonvicini, V.; Adriani, O.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Bakaldin, A. V.; Bobkov, S. G.; Boezio, M.; Dalkarov, O. D.; Egorov, A. E.; Glushkov, N. A.; Gorbunov, M. S.; Gusakov, Yu V.; Hnatyk, B. I.; Kadilin, V. V.; Kaplin, V. A.; Kheymits, M. D.; Korepanov, V. E.; Longo, F.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Moskalenko, I. V.; Naumov, P. Yu; Picozza, P.; Runtso, M. F.; Serdin, O. V.; Sparvoli, R.; Spillantini, P.; Stozhkov, Yu I.; Suchkov, S. I.; Taraskin, A. A.; Tavani, M.; Yurkin, Yu T.; Zverev, V. G.

    2017-01-01

    The GAMMA-400 gamma-ray telescope is designed to measure the gamma-ray fluxes in the energy range from ∼20 MeV to ∼1 TeV, performing a sensitive search for high-energy gamma-ray emission when annihilating or decaying dark matter particles. Such measurements will be also associated with the following scientific goals: searching for new and studying known Galactic and extragalactic discrete high-energy gamma-ray sources (supernova remnants, pulsars, accreting objects, microquasars, active galactic nuclei, blazars, quasars). It will be possible to study their structure with high angular resolution and measuring their energy spectra and luminosity with high-energy resolution; identify discrete gamma-ray sources with known sources in other energy ranges. The major advantage of the GAMMA-400 instrument is excellent angular and energy resolutions for gamma rays above 10 GeV. The gamma-ray telescope angular and energy resolutions for the main aperture at 100-GeV gamma rays are ∼0.01% and ∼1%, respectively. The motivation of presented results is to improve physical characteristics of the GAMMA-400 gamma-ray telescope in the energy range of ∼20-100 MeV, most unexplored range today. Such observations are crucial today for a number of high-priority problems faced by modern astrophysics and fundamental physics, including the origin of chemical elements and cosmic rays, the nature of dark matter, and the applicability range of the fundamental laws of physics. To improve the reconstruction accuracy of incident angle for low-energy gamma rays the special analysis of topology of pair-conversion events in thin layers of converter performed. Choosing the pair-conversion events with more precise vertical localization allows us to obtain significantly better angular resolution in comparison with previous and current space and ground-based experiments. For 50-MeV gamma rays the GAMMA-400 gamma-ray telescope angular resolution is better than 50.

  6. Barnacle Bill Spectra

    NASA Technical Reports Server (NTRS)

    1997-01-01

    These IMP spectra show the characteristics of the rock surface measured by the Alpha Proton X-Ray Spectrometer (blue), the soil trapped in pits on the rock surface (red), and the deposit of bright drift on the top of the rock. The area measured by the APXS has the properties expected for nearly unweathered igneous rock, and the soil trapped in the pits is intermediate to the unweathered rock and the highly weathered drift material.

  7. Gamma titanium aluminide alloys

    SciTech Connect

    Yamaguchi, M.; Inui, H.; Kishida, K.; Matsumuro, M.; Shirai, Y.

    1995-08-01

    Extensive progress and improvements have been made in the science and technology of gamma titanium aluminide alloys within the last decade. In particular, the understanding of their microstructural characteristics and property/microstructure relationships has been substantially deepened. Based on these achievements, various engineering two-phase gamma alloys have been developed and their mechanical and chemical properties have been assessed. Aircraft and automotive industries arc pursuing their introduction for various structural components. At the same time, recent basic studies on the mechanical properties of two-phase gamma alloys, in particular with a controlled lamellar structure have provided a considerable amount of fundamental information on the deformation and fracture mechanisms of the two-phase gamma alloys. The results of such basic studies are incorporated in the recent alloy and microstructure design of two-phase gamma alloys. In this paper, such recent advances in the research and development of the two-phase gamma alloys and industrial involvement are summarized.

  8. Gamma ray transients

    NASA Technical Reports Server (NTRS)

    Cline, Thomas L.

    1987-01-01

    The discovery of cosmic gamma ray bursts was made with systems designed at Los Alamos Laboratory for the detection of nuclear explosions beyond the atmosphere. HELIOS-2 was the first gamma ray burst instrument launched; its initial results in 1976, seemed to deepen the mystery around gamma ray transients. Interplanetary spacecraft data were reviewed in terms of explaining the behavior and source of the transients.

  9. Search for two-{gamma} sum-energy peaks in the decay out of superdeformed bands

    SciTech Connect

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

    1995-08-01

    The spectrum of {gamma}rays decaying out of the superdeformed (SD) band in {sup 192}Hg has a quasicontinuous distribution. Whereas methods to construct level schemes from discrete lines in coincidence spectra are well established, new techniques must still be developed to extract information from coincidences involving quasicontinuous {gamma}rays. From an experiment using Eurogam, we obtained impressively clean 1- and 2-dimensional {gamma} spectra from pairwise or single gates, respectively, on the transitions of the SD band in {sup 192}Hg. We investigated methods to exploit the 2-dimensional quasicontinuum spectra coincident with the SD band to determine the excitation energy of the SD band above the normal yrast line. No strong peaks were observed in the 2-{gamma} sum spectra; only candidates of peaks at a 2-3 {sigma} level were found. This suggests that 2-{gamma} decay is not the dominant decay branch out of SD bands, consistent with the observed multiplicity of 3.2. We shall next search for peaks in sum-spectra of 3 {gamma}s.

  10. Multi-Epoch Multiwavelength Spectra and Models for Blazar 3C 279

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.; Boettcher, M.; Aldering, G.; Aller, H.; Aller, M.; Backman, D. E.; Balonek, T. J.; Bertsch, D. L.; Bloom, S. D.; Bock, H.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    Of the blazars detected by EGRET in GeV gamma-rays, 3C 279 is not only the best-observed by EGRET, but also one of the best-monitored at lower frequencies. We have assembled eleven spectra, from GHz radio through GeV gamma-rays, from the time intervals of EGRET observations. Although some of the data have appeared in previous publications, most are new, including data taken during the high states in early 1999 and early 2000. All of the spectra show substantial gamma-ray contribution to the total luminosity of the object; in a high state, the gamma-ray luminosity dominates over that at all other frequencies by a factor of more than 10. There is no clear pattern of time correlation; different bands do not always rise and fall together, even in the optical, X-ray, and gamma-ray bands. The spectra are modeled using a leptonic jet, with combined synchrotron self-Compton + external Compton gamma-ray production. Spectral variability of 3C 279 is consistent with variations of the bulk Lorentz factor of the jet, accompanied by changes in the spectral shape of the electron distribution. Our modeling results are consistent with the UV spectrum of 3C 279 being dominated by accretion disk radiation during times of low gamma-ray intensity.

  11. Magnetic Microcalorimeter Gamma Detectors for High-Precision Non-Destructive Analysis, FY14 Extended Annual Report

    SciTech Connect

    Friedrich, S.

    2015-02-06

    Cryogenic gamma (γ) detectors with operating temperatures of ~0.1 K or below offer 10× better energy resolution than conventional high-purity germanium detectors that are currently used for non-destructive analysis (NDA) of nuclear materials. This can greatly increase the accuracy of NDA, especially at low-energies where gamma rays often have similar energies and cannot be resolved by Ge detectors. We are developing cryogenic γ–detectors based on metallic magnetic calorimeters (MMCs), which have the potential of higher resolution, faster count rates and better linearity than other cryogenic detector technologies. High linearity is essential to add spectra from different pixels in detector arrays that are needed for high sensitivity. Here we discuss the fabrication of a new generation of MMC γ–detectors in FY2014, and the resulting improvements in energy resolution and linearity of the new design. As an example of the type of NDA that cryogenic detectors enable, we demonstrate the direct detection of Pu-242 emissions with our MMC γ–detectors in the presence of Pu-240, and show that a quantitative NDA analysis agrees with the mass spectrometry

  12. Assessment of gamma radiolytic degradation in waste lubricating oil by GC/MS and UV/VIS

    NASA Astrophysics Data System (ADS)

    Scapin, Marcos A.; Duarte, Celina L.; Bustillos, José Oscar W. V.; Sato, Ivone M.

    2009-07-01

    The hydrocarbons degradation by gamma irradiation of the waste automotive lubricating oil at different absorbed doses has was investigated. The waste automotive oil in a Brazilian oil recycling company was collected. This sample was fractioned and 50% and 70% (v/v) Milli-Q water were added. Each sample was irradiated with 100, 200 and 500 kGy doses using a gamma source Co-60—GAMMACELL type, with 5×10 3 Ci total activity. Gas chromatography-mass spectrometry (GC/MS) was used to identify degraded organic compounds. The mass spectra were analyzed using the mass spectral library from NIST, installed in the spectrometer. The sample irradiated at 500 kGy dose with 70% (v/v) Milli-Q water addition formed eight degradation products, namely diethanolmethylamine (C 5H 13NO), diethyldiethylene glycol (C 8H 18O 3), 1-octyn-3-ol, 4-ethyl (C 10H 18O) and 1.4-pentanediamine, N1, N1-diethyl (C 9H 22N 2). The color changing of the waste lubricating oil, for different absorbed doses, was determined by UV/VIS spectrophotometer. The related sample showed the lowest absorbance value evidencing the formation of 2-ethoxyethyl ether (C 8H 18O 3) compound.

  13. Supernovae and Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Panagia, Nino; Sahu, Kailash

    2001-07-01

    Participants; Preface; Gamma-ray burst-supernova relation B. Paczynski; Observations of gamma-ray bursts G. Fishman; Fireballs T. Piran; Gamma-ray mechanisms M. Rees; Prompt optical emission from gamma-ray bursts R. Kehoe, C. Akerlof, R. Balsano, S. Barthelmy, J. Bloch, P. Butterworth, D. Casperson, T. Cline, S. Fletcher, F. Frontera, G. Gisler, J. Heise, J. Hills, K. Hurley, B. Lee, S. Marshall, T. McKay, A. Pawl, L. Piro, B. Priedhorsky, J. Szymanski and J. Wren; X-ray afterglows of gamma-ray bursts L. Piro; The first year of optical-IR observations of SN1998bw I. Danziger, T. Augusteijn, J. Brewer, E. Cappellaro, V. Doublier, T. Galama, J. Gonzalez, O. Hainaut, B. Leibundgut, C. Lidman, P. Mazzali, K. Nomoto, F. Patat, J. Spyromilio, M. Turatto, J. Van Paradijs, P. Vreeswijk and J. Walsh; X-ray emission of Supernova 1998bw in the error box of GRB980425 E. Pian; Direct analysis of spectra of type Ic supernovae D. Branch; The interaction of supernovae and gamma-ray bursts with their surroundings R. Chevalier; Magnetars, soft gamma-ray repeaters and gamma-ray bursts A. Harding; Super-luminous supernova remnants Y. -H. Chu, C. -H. Chen and S. -P. Lai; The properties of hypernovae: SNe Ic 1998bw, 1997ef, and SN IIn 1997cy K. Nomoto, P. Mazzali, T. Nakamura, K. Iwanmoto, K. Maeda, T. Suzuki, M. Turatto, I. Danziger and F. Patat; Collapsars, Gamma-Ray Bursts, and Supernovae S. Woosley, A. MacFadyen and A. Heger; Pre-supernova evolution of massive stars N. Panagia and G. Bono; Radio supernovae and GRB 980425 K. Weiler, N. Panagia, R. Sramek, S. Van Dyk, M. Montes and C. Lacey; Models for Ia supernovae and evolutionary effects P. Hoflich and I. Dominguez; Deflagration to detonation A. Khokhlov; Universality in SN Iae and the Phillips relation D. Arnett; Abundances from supernovae F. -K. Thielemann, F. Brachwitz, C. Freiburghaus, S. Rosswog, K. Iwamoto, T. Nakamura, K. Nomoto, H. Umeda, K. Langanke, G. Martinez-Pinedo, D. Dean, W. Hix and M. Strayer; Sne, GRBs, and the

  14. Density fluctuation measurements by using the Fraunhofer diffraction method in GAMMA10

    NASA Astrophysics Data System (ADS)

    Morikawa, Y.; Yoshikawa, M.; Kohagura, J.; Shima, Y.; Hasegawa, Y.; Sakamoto, M.; Imai, T.; Ichimura, M.

    2013-12-01

    We applied Fraunhofer diffraction (FD) method to GAMMA10 plasma. The FD method can measure the density fluctuation in detail and the wave number of the fluctuation. We successfully obtained the density fluctuation spectra in GAMMA 10. Analyzing the FD method signals of radial fluctuation intensity profile, we can successfully obtain the wave number and the phase velocity of the low frequency density fluctuation.

  15. Some neutron and gamma radiation characteristics of plutonium cermet fuel for isotopic power sources

    NASA Technical Reports Server (NTRS)

    Neff, R. A.; Anderson, M. E.; Campbell, A. R.; Haas, F. X.

    1972-01-01

    Gamma and neutron measurements on various types of plutonium sources are presented in order to show the effects of O-17, O-18 F-19, Pu-236, age of the fuel, and size of the source on the gamma and neutron spectra. Analysis of the radiation measurements shows that fluorine is the main contributor to the neutron yields from present plutonium-molybdenum cermet fuel, while both fluorine and Pu-236 daughters contribute significantly to the gamma ray intensities.

  16. Goddard Contributions to the La Jolla Workshop on Gamma Ray Transients

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Six articles addressing cosmic and solar gamma ray transients are presented. The topics covered include: gamma ray lines from solar flares and cosmic transients including burst spectra; a review of the 1979 March 5 transient; time variation in the 511 KeV flux observed by the ISEE spectrometer; time variations of an absorption feature in the spectrum of the burst on 1980 April 19; and the theory of gamma ray amplification through stimulated annihilation radiation.

  17. X-Ray Spectra of Young Pulsars and Their Wind Nebulae: Dependence on Spin-Down Energy Loss Rate

    NASA Technical Reports Server (NTRS)

    Gotthelf, E. V.

    2003-01-01

    An observational model is presented for the spectra of young rotation-powered pulsars and their nebulae based on a study of nine bright Crab-like pulsar systems observed with the Chandra X-ray observatory. A significant correlation is discovered between the X-ray spectra of these pulsars and that of their associated pulsar wind nebulae, both of which are observed to be a function of the spin-down energy loss rate, E. The 2-10 keV spectra of these objects are well characterized by an absorbed power-law model with photon indices, Gamma, in the range of 0.6 < Gamma (sub PSR) < 2.1 and 1.3 < Gamma(sub PWN) < 2.3, for the pulsars and their nebulae, respectively. A linear regression fit relating these two sets of indexes yields Gamma(sub PWN) = 0.91 +/- 0.18 + (0.66 +/- 0.11) Gamma (sub PSR), with a correlation coefficient of r = 0.97. The spectra of these pulsars are found to steepen as Gamma = Gamma(sub max) + alpha E (exp -1/2), with Gamma(sub max) providing an observational limit on the spectral slopes of young rotation-powered pulsars. These results reveal basic properties of young pulsar systems, allow new observational constraints on models of pulsar wind emission, and provide a means of predicting the energetics of pulsars lacking detected pulsations.

  18. Intensity of 253 keV {gamma}-rays ({sup 245}Am) from {alpha}-decay of {sup 249}Bk

    SciTech Connect

    Popov, Yu.S.; Srurov, D.Kh.; Baranov, A.A.; Chistyakov, V.M.; Timofeev, G.A.

    1995-01-01

    The intensity of 253 keV {gamma}-rays ({sup 245}Am) from {alpha}-decay of {sup 249}Bk is 3.09(9)% at the P = 0.95 confidence level. Precision semi-conducting {gamma}-spectrometry and coulometry are used.

  19. Determination of IRT-2M fuel burnup by gamma spectrometry.

    PubMed

    Koleška, Michal; Viererbl, Ladislav; Marek, Milan; Ernest, Jaroslav; Šunka, Michal; Vinš, Miroslav

    2016-01-01

    A spectrometric system was developed for evaluating spent fuel in the LVR-15 research reactor, which employs highly enriched (36%) IRT-2M-type fuel. Such system allows the measurement of detailed fission product profiles. Within these measurements, nuclides such as (137)Cs, (134)Cs, (144)Ce, (106)Ru and (154)Eu may be detected in fuel assemblies with different cooling times varying between 1.67 and 7.53 years. Burnup calculations using the MCNPX Monte Carlo code data showed good agreement with measurements, though some discrepancies were observed in certain regions. These discrepancies are attributed to the evaluation of irradiation history, reactor regulation pattern and buildup schemes.

  20. Gamma-spectrometry with Compton suppressed detectors arrays

    SciTech Connect

    Schueck, C.; Hannachi, F.; Chapman, R.; Lisle, J.C.; Mo, J.N.; Paul, E.; Love, D.J.G.; Nolan, P.J.; Nelson, A.H.; Walker, P.M.

    1985-01-01

    Recent results of experiments performed with two different Compton-suppressed detectors arrays in Daresbury and Berkeley (/sup 163,164/Yb and /sup 154/Er, respectively), are presented together with a brief description of the national French array presently under construction in Strasbourg. 25 refs., 15 figs.

  1. A new versatile underground gamma-ray spectrometry system.

    PubMed

    Lutter, Guillaume; Hult, Mikael; Marissens, Gerd; Andreotti, Erica; Rosengård, Ulf; Misiaszek, Marcin; Yüksel, Ayhan; Sahin, Namik

    2013-11-01

    The newest development in IRMM's underground analytical facility is a large lead shield lined with copper that is versatile and can host several detectors of different types. The characteristics and the background performance of the shield are described for four different detector configurations involving HPGe-detectors and NaI-detectors. The shield has been designed to swap detectors, while still maintaining a low background. This enables testing of detectors for other experiments and optimisation of detection limits for specific radionuclides in different projects.

  2. SPECTRA. September 2011

    DTIC Science & Technology

    2011-09-01

    Transportation Services program with the Dragon capsule. (Credit: SpaceX /Chris Thompson) S p a c e c r a f t e n g in e e r in g spectra NRL...secondary payloads on board a Space Exploration Technologies ( SpaceX ), Inc., Falcon 9 launch vehicle. NRL’s nanosatellites are part of the CubeSat...Maryland. The primary payload launched aboard the SpaceX Falcon 9 was the Dragon capsule. Developed by SpaceX and sponsored by NASA’s Commercial Orbital

  3. Determinations of Photon Spectra

    DTIC Science & Technology

    1989-01-01

    COVERED O14. DATE OF REPORT (Year, Month, Day) 115. PAGE COUNT THESIS/ftFROW*W FROM TO 1989 1 54 16. SUPPLEMENTARY NOTATION A ?RQVk;U kOR 3UB LIC RELEASE...IAW AFR 190- 1 ERNEST A. HAYGOOD, 1st Lt, USAF Executive Officer, Civilian Institution ProQrams 17. COSATI CODES 18. SUBJECT TERMS (Continue on...spectra from measurements obtained with a sodium iodide counting system. A response matrix is computed by combining photon cross sections with

  4. Muons in gamma showers

    NASA Technical Reports Server (NTRS)

    Stanev, T.; Vankov, C. P.; Halzen, F.

    1985-01-01

    Muon production in gamma-induced air showers, accounting for all major processes. For muon energies in the GeV region the photoproduction is by far the most important process, while the contribution of micron + micron pair creation is not negligible for TeV muons. The total rate of muons in gamma showers is, however, very low.

  5. Gamma-ray astrophysics

    NASA Technical Reports Server (NTRS)

    Stecker, F. W. (Editor); Trombka, J. I. (Editor)

    1973-01-01

    Conference papers on gamma ray astrophysics are summarized. Data cover the energy region from about 0.3 MeV to a few hundred GeV and theoretical models of production mechanisms that give rise to both galactic and extragalactic gamma rays.

  6. Gamma-Ray Pulsars

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2011-01-01

    The Fermi Gamma-Ray Space Telescope has revolutionized the study of pulsar physics with the detection of over 80 gamma-ray pulsars. Several new populations have been discovered, including 24 radio quiet pulsars found through gamma-ray pulsations alone and about 20 millisecond gamma-ray pulsars. The gamma-ray pulsations from millisecond pulsars were discovered by both folding at periods of known radio millisecond pulsars or by detecting them as gamma-ray sources that are followed up by radio pulsar searches. The second method has resulted in a phenomenally successful synergy, with -35 new radio MSPs (to date) having been discovered at Fermi unidentified source locations and the gamma-ray pulsations having then been detected in a number of these using the radio timing solutions. The higher sensitivity and larger energy range of the Fermi Large Area Telescope has produced detailed energy-dependent light curves and phase-resolved spectroscopy on brighter pulsars, that have ruled out polar cap models as the major source of the emission in favor of outer magnetosphere accelerators. The large number of gamma-ray pulsars now allows for the first time meaningful population and sub-population studies that are revealing surprising properties of these fascinating sources.

  7. Identification of Highly Pathogenic Microorganisms by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry: Results of an Interlaboratory Ring Trial.

    PubMed

    Lasch, Peter; Wahab, Tara; Weil, Sandra; Pályi, Bernadett; Tomaso, Herbert; Zange, Sabine; Kiland Granerud, Beathe; Drevinek, Michal; Kokotovic, Branko; Wittwer, Matthias; Pflüger, Valentin; Di Caro, Antonino; Stämmler, Maren; Grunow, Roland; Jacob, Daniela

    2015-08-01

    In the case of a release of highly pathogenic bacteria (HPB), there is an urgent need for rapid, accurate, and reliable diagnostics. MALDI-TOF mass spectrometry is a rapid, accurate, and relatively inexpensive technique that is becoming increasingly important in microbiological diagnostics to complement classical microbiology, PCR, and genotyping of HPB. In the present study, the results of a joint exercise with 11 partner institutions from nine European countries are presented. In this exercise, 10 distinct microbial samples, among them five HPB, Bacillus anthracis, Brucella canis, Burkholderia mallei, Burkholderia pseudomallei, and Yersinia pestis, were characterized under blinded conditions. Microbial strains were inactivated by high-dose gamma irradiation before shipment. Preparatory investigations ensured that this type of inactivation induced only subtle spectral changes with negligible influence on the quality of the diagnosis. Furthermore, pilot tests on nonpathogenic strains were systematically conducted to ensure the suitability of sample preparation and to optimize and standardize the workflow for microbial identification. The analysis of the microbial mass spectra was carried out by the individual laboratories on the basis of spectral libraries available on site. All mass spectra were also tested against an in-house HPB library at the Robert Koch Institute (RKI). The averaged identification accuracy was 77% in the first case and improved to >93% when the spectral diagnoses were obtained on the basis of the RKI library. The compilation of complete and comprehensive databases with spectra from a broad strain collection is therefore considered of paramount importance for accurate microbial identification.

  8. Control spectra for Quito

    NASA Astrophysics Data System (ADS)

    Aguiar, Roberto; Rivas-Medina, Alicia; Caiza, Pablo; Quizanga, Diego

    2017-03-01

    The Metropolitan District of Quito is located on or very close to segments of reverse blind faults, Puengasí, Ilumbisí-La Bota, Carcelen-El Inca, Bellavista-Catequilla and Tangahuilla, making it one of the most seismically dangerous cities in the world. The city is divided into five areas: south, south-central, central, north-central and north. For each of the urban areas, elastic response spectra are presented in this paper, which are determined by utilizing some of the new models of the Pacific Earthquake Engineering Research Center (PEER) NGA-West2 program. These spectra are calculated considering the maximum magnitude that could be generated by the rupture of each fault segment, and taking into account the soil type that exists at different points of the city according to the Norma Ecuatoriana de la Construcción (2015). Subsequently, the recurrence period of earthquakes of high magnitude in each fault segment is determined from the physical parameters of the fault segments (size of the fault plane and slip rate) and the pattern of recurrence of type Gutenberg-Richter earthquakes with double truncation magnitude (Mmin and Mmax) is used.

  9. Optical gamma thermometer

    DOEpatents

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

    2013-08-06

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

  10. Theoretical Studies of Molecular Spectra

    NASA Technical Reports Server (NTRS)

    McKay, Christopher (Technical Monitor); Freedman, Richard S.

    2002-01-01

    This summary describes the research activities of the principal investigator during the reporting period. The research includes spectroscopy, management of molecular databases, and generation of spectral line profiles and opacity data. The spectroscopy research includes oxygen broadening of nitric oxide (NO), analysis of CO2 spectra, analysis of HNO3 spectra, and analysis of CO spectra.

  11. Low-resolution gamma-ray measurements of uranium enrichment

    SciTech Connect

    Sprinkle, J.K. Jr.; Christiansen, A.; Cole, R.; Collins, M.L.

    1996-11-01

    Facilities that process special nuclear material perform periodic inventories. In bulk facilities that process low-enriched uranium, these inventories and their audits are based primarily on weight and enrichment measurements. Enrichment measurements determine the {sup 211}U weight fraction of the uranium compound from the passive gamma-ray emissions of the sample. Both international inspectors and facility operators rely on the capability to make in-field gamma-ray measurements of uranium enrichment. These users require rapid, portable measurement capability. Some in-field measurements have been biased, forcing the inspectors to resort to high-resolution measurements or mass spectrometry to accomplish their goals.

  12. Heavy ion recoil spectrometry of barium strontium titanate films

    NASA Astrophysics Data System (ADS)

    Stannard, W. B.; Johnston, P. N.; Walker, S. R.; Bubb, I. F.; Scott, J. F.; Cohen, D. D.; Dytlewski, N.; Martin, J. W.

    1995-05-01

    Thin films of barium strontium titanate have been analysed using heavy ion recoil spectrometry with 77 and 98 MeV 127I ions at the new heavy ion recoil facility at ANSTO, Lucas Heights. New calibration procedures have been developed for quantitative analysis. Energy spectra for each of the elements present reveal interdiffusion that was not previously known.

  13. Registration of the Atmospheric Gamma Radiation on Board the Russian Segment of the International Space Station

    NASA Astrophysics Data System (ADS)

    Andreevsky, S. E.; Kuznetsov, V. D.; Sinelnikov, V. M.

    2017-03-01

    The paper describes the complex of scientific instruments and the algorithm of the "Molniya-Gamma" experiment on measuring gamma-ray fluxes in the energy range of 32-750 keV carried out in 2011 on board the Russian Segment (RS) of the International Space Station (ISS). About 500 thousand energy spectra with a time resolution of 1 min were obtained in 512 energy channels during 232 days. One-second variations in the number of gamma quanta in four energy channels and the triggered fluxes of gamma quanta lasting less than 100 ms were recorded simultaneously. The data obtained allow us to study temporal and spatial variation of gamma-ray radiation to detect terrestrial gamma flashes (TGFs). Data on very large number of gamma-ray spikes were acquired through a trigger data mode with a low threshold.

  14. Registration of the Atmospheric Gamma Radiation on Board the Russian Segment of the International Space Station

    NASA Astrophysics Data System (ADS)

    Andreevsky, S. E.; Kuznetsov, V. D.; Sinelnikov, V. M.

    2016-11-01

    The paper describes the complex of scientific instruments and the algorithm of the "Molniya-Gamma" experiment on measuring gamma-ray fluxes in the energy range of 32-750 keV carried out in 2011 on board the Russian Segment (RS) of the International Space Station (ISS). About 500 thousand energy spectra with a time resolution of 1 min were obtained in 512 energy channels during 232 days. One-second variations in the number of gamma quanta in four energy channels and the triggered fluxes of gamma quanta lasting less than 100 ms were recorded simultaneously. The data obtained allow us to study temporal and spatial variation of gamma-ray radiation to detect terrestrial gamma flashes (TGFs). Data on very large number of gamma-ray spikes were acquired through a trigger data mode with a low threshold.

  15. X-ray Spectrometry.

    ERIC Educational Resources Information Center

    Markowicz, Andrzej A.; Van Grieken, Rene E.

    1984-01-01

    Provided is a selective literature survey of X-ray spectrometry from late 1981 to late 1983. Literature examined focuses on: excitation (photon and electron excitation and particle-induced X-ray emission; detection (wavelength-dispersive and energy-dispersive spectrometry); instrumentation and techniques; and on such quantitative analytical…

  16. Shape of the A=14 {beta} spectra

    SciTech Connect

    Garcia, A.; Brown, B.A.

    1995-10-01

    The shape of allowed {Beta} spectra have a small contribution from the interference of the vector, weak-magnetism and axial GT matrix elements. According to CVC plus charge-symmetry of nuclear interactions, in a 0{sup +}{r_arrow} 1{sup +} transition like the {Beta} and {gamma} decays of the A=14 system, the weak-magnetism and electro-magnetic-Ml matrix elements should be equal. A measurement of the shape of the {sup 14}O spectrum, however, disagrees, by a factor of two with naive calculation described above. It has been speculated that because of the high supression of GT matrix element in the A=14 system, one could understand this discrepancy based on small charge-symmetry-effects. We have used shell-model wave functions adjusted to fit {sup 14}N(e,e{sup {prime}}) inelastic scattering, the width of the M1-{gamma} transition, and the {Beta} log f t`s, and show that reasonable assumptions lead to estimates that are very close to the naive CVC estimation. We propose that the {sup 14}O discrepancy is important and that new experiments should be done to measure the shape of the spectrum.

  17. Spectral evolution of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Band, D.; Matteson, J.; Ford, L.; Schaefer, B.; Teegarden, B.; Cline, T.; Paciesas, W.; Pendleton, G.; Fishman, G.; Meegan, C.

    1992-01-01

    BATSE's Spectral Detectors provide a series of high resolution spectra over the duration of a gamma-ray burst; fits to these spectra show the evolution of the continuum as the burst progresses. The burst continuum can usually be fit by the spectral form AE sup alpha exp(-E/kT) from around 25 keV to more than 3 MeV, with varying trends in the value and evolution of the spectral parameters. As a result of limited statistics for E greater than 1 - 2 MeV in the individual spectra, a high energy power law is not required. Only long duration strong bursts can be studied by fitting a series of spectra, and therefore our conclusions concern only this class of burst. The bursts we analyzed tend to be characterized by a hard-to-soft trend both for individual intensity spikes and for the burst as a whole: the hardness leads the count rate in spectra which resolve the temporal variations, while the hardness of successive spikes decreases. We also summarize the performance of the Spectral Detectors and the development of analysis tools to date.

  18. Gamma-ray Emission from Globular Clusters

    NASA Astrophysics Data System (ADS)

    Tam, Pak-Hin T.; Hui, Chung Y.; Kong, Albert K. H.

    2016-03-01

    Over the last few years, the data obtained using the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope has provided new insights on high-energy processes in globular clusters, particularly those involving compact objects such as MilliSecond Pulsars (MSPs). Gamma-ray emission in the 100 MeV to 10 GeV range has been detected from more than a dozen globular clusters in our galaxy, including 47 Tucanae and Terzan 5. Based on a sample of known gammaray globular clusters, the empirical relations between gamma-ray luminosity and properties of globular clusters such as their stellar encounter rate, metallicity, and possible optical and infrared photon energy densities, have been derived. The measured gamma-ray spectra are generally described by a power law with a cut-off at a few gigaelectronvolts. Together with the detection of pulsed γ-rays from two MSPs in two different globular clusters, such spectral signature lends support to the hypothesis that γ-rays from globular clusters represent collective curvature emission from magnetospheres of MSPs in the clusters. Alternative models, involving Inverse-Compton (IC) emission of relativistic electrons that are accelerated close to MSPs or pulsar wind nebula shocks, have also been suggested. Observations at >100 GeV by using Fermi/LAT and atmospheric Cherenkov telescopes such as H.E.S.S.-II, MAGIC-II, VERITAS, and CTA will help to settle some questions unanswered by current data.

  19. Gamma-ray Pulsars: Models and Predictions

    NASA Technical Reports Server (NTRS)

    Harding Alice K.; White, Nicholas E. (Technical Monitor)

    2000-01-01

    Pulsed emission from gamma-ray pulsars originates inside the magnetosphere, from radiation by charged particles accelerated near the magnetic poles or in the outer gaps. In polar cap models, the high energy spectrum is cut off by magnetic pair production above an energy that is, dependent on the local magnetic field strength. While most young pulsars with surface fields in the range B = 10(exp 12) - 10(exp 13) G are expected to have high energy cutoffs around several GeV, the gamma-ray spectra of old pulsars having lower surface fields may extend to 50 GeV. Although the gamma-ray emission of older pulsars is weaker, detecting pulsed emission at high energies from nearby sources would be an important confirmation of polar cap models. Outer gap models predict more gradual high-energy turnovers of the primary curvature emission around 10 GeV, but also predict an inverse Compton component extending to TeV energies. Detection of pulsed TeV emission, which would not survive attenuation at the polar caps, is thus an important test of outer gap models. Next-generation gamma-ray telescopes sensitive to GeV-TeV emission will provide critical tests of pulsar acceleration and emission mechanisms.

  20. Continuum Fitting HST QSO Spectra

    NASA Technical Reports Server (NTRS)

    Tytler, David; Oliversen, Ronald J. (Technical Monitor)

    2002-01-01

    The Principal Component Analysis (PCA) method which we are using to fit and describe QSO spectra relies upon the fact that QSO continuum are generally very smooth and simple except for emission and absorption lines. To see this we need high signal-to-noise (S/N) spectra of QSOs at low redshift which have relatively few absorption lines in the Lyman-a forest. We need a large number of such spectra to use as the basis set for the PCA analysis which will find the set of principal component spectra which describe the QSO family as a whole. We have found that too few HST spectra have the required S/N and hence we need to supplement them with ground based spectra of QSOs at higher redshift. We have many such spectra and we have been working to make them suitable for this analysis. We have concentrated on this topic since 12/15/01.