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Sample records for capture gamma-ray spectra

  1. Study of gamma ray multiplicity spectra for radiative capture of neutrons in 113,115In

    International Nuclear Information System (INIS)

    Neutron radiative capture measurements were performed for the enriched isotopes 113In and 115In on the neutron spectrometer at the Neutron Physics Laboratory of the Joint Institute for Nuclear Research employing the gamma ray multiplicity technique and using a ''Romashka'' multi-sectional 4p detector on the 500 m time base of the IBR-30 booster. The gamma multiplicity spectra of resolved resonances were obtained for the 20-500 eV energy range. The mean gamma ray multiplicity was determined for each resonance. The dependence of the ratio S of the low-energy coincidence multiplicity spectrum to the high-energy coincidence multiplicity spectrum on resonance energy exhibits a non-statistical structure. This structure was found to correlate with the local neutron strength function. (author). 10 refs, 6 figs, 2 tabs

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

    Science.gov (United States)

    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).

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

    Energy Technology Data Exchange (ETDEWEB)

    Ullmann, John Leonard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kawano, Toshihiko [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bredeweg, Todd Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Baramsai, Bayarbadrakh [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Couture, Aaron Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Haight, Robert Cameron [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jandel, Marian [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mosby, Shea Morgan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); O' Donnell, John M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rundberg, Robert S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vieira, David J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wilhelmy, Jerry B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Becker, John A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wu, Ching-Yen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Krticka, Milan [Charles Univ., Prague (Czech Republic)

    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.

  4. Analytical applications of neutron capture gamma-ray spectroscopy

    International Nuclear Information System (INIS)

    Prompt gamma-rays from thermal induced nuclear reactions have been used to estimate the boron, chlorine and phosphorus contents in industrial and reference materials. A neutron capture gamma-ray spectroscopy facility for analytical purposes using 252-Cf sources has been designed and calibrated. The facility is principally designed for the measurement of the prompt gamma-ray spectra obtained due to thermal neutron capture by means of the internal target geometry. The capture spectra were recorded using a high resolution Ge(Li) system. The designed facility and the system used in this work are described in detail. A weight of 50 to 100 gm of each sample in a power or liquid form encapsulated in a polyethene container was used. Sensitivity curves using different standard concentration values of B, Cl and P, were constructed. The concentration range was from 0.005 to 30%. (orig.)

  5. Skyshine spectra of gamma rays

    International Nuclear Information System (INIS)

    A study of the spectra of gamma photons back-scattered in vertical direction by infinite air above ground (skyshine) is presented. The source for these measurements is a 650 Ci Cobalt-60 point-source and the skyshine spectra are reported for distances from 150 m to 325 m from the source, measured with a 5 cm x 5 cm NaI(Tl) detector collimated with collimators of 12 mm and 20 mm diameter and 5 cm length. These continuous spectra are unfolded with Gold's iterative technique. The photon-spectra so obtained have a distinct line at 72 keV due to multiply-scattered photons. This is an energy where photoelectric and Compton cross-sections for multiply-scattered photons balance each other. The intensity of the line(I) decreases exponentially with distance (d) from the source obeying a relation of the type I = Isub(o)esup(-μd) where μ is called as ''Multiply-Scatter Coefficient'', a constant of the medium which is air in these measurements. This relationship is explained in terms of a halo around the source comprising of multiply-scattered gamma photons, Isub(0) being the intensity of these scattered photons at the location of cobalt-source. A fraction called as ''Back-scattered Fraction'', the ratio of Isub(0) to the number of original photons from the cobalt-source entering the infinite air, is also calculated. It is shown that with a properly calibrated detector system, this fraction can be used to determine the strength of a large gamma source, viz. a nuclear explosion in air, and for mineral prospecting. These conclusions are general and can be applied to any other infinite medium. Some forward-scatter (transmission) spectra of cobalt-60 source through 10 cm of Pb and 2.5 cm of Al are also reported. (auth.)

  6. Capture Gamma-Ray Libraries for Nuclear Applications

    Energy Technology Data Exchange (ETDEWEB)

    Sleaford, B.W.; Firestone, Richard B.; Summers, N.; Escher, J.; Hurst, A.; Krticka, M.; Basunia, S.; Molnar, G.; Belgya, T.; Revay, Z.; Choi, H.D.

    2010-05-01

    The neutron capture reaction is useful in identifying and analyzing the gamma-ray spectrum from an unknown assembly as it gives unambiguous information on its composition. This can be done passively or actively where an external neutron source is used to probe an unknown assembly. There are known capture gamma-ray data gaps in the ENDF libraries used by transport codes for various nuclear applications. The Evaluated Gamma-ray Activation file (EGAF) is a new thermal neutron capture database of discrete line spectra and cross sections for over 260 isotopes that was developed as part of an IAEA Coordinated Research Project. EGAF has been used to improve the capture gamma production in ENDF libraries. For medium to heavy nuclei the quasi continuum contribution to the gamma cascades is not experimentally resolved. The continuum contains up to 90percent of all the decay energy an is modeled here with the statistical nuclear structure code DICEBOX. This code also provides a consistency check of the level scheme nuclear structure evaluation. The calculated continuum is of sufficient accuracy to include in the ENDF libraries. This analysis also determines new total thermal capture cross sections and provides an improved RIPL database. For higher energy neutron capture there is less experimental data available making benchmarking of the modeling codes more difficult. We use CASINO, a version of DICEBOX that is modified for this purpose. This can be used to simulate the neutron capture at incident neutron energies up to 20 MeV to improve the gamma-ray spectrum in neutron data libraries used for transport modelling of unknown assemblies.

  7. Spectra of {gamma} rays feeding superdeformed bands

    Energy Technology Data Exchange (ETDEWEB)

    Lauritsen, T.; Khoo, T.L.; Henry, R.G. [and others

    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.

  8. Neutron capture cross section and capture gamma-ray spectra of 138Ba in the keV-neutron energy region

    Directory of Open Access Journals (Sweden)

    Katabuchi T.

    2015-01-01

    Full Text Available The neutron capture cross sections and the capture γ-ray spectra of 138Ba were measured in the astrophysically important energy region. Measurements were made at neutron energies from 15 to 80 keV. The neutron energy was determined by the time-of-flight method. The γ-ray spectra showed that the primary transition pattern strongly depended on the incident neutron energy. The neutron capture cross sections were derived by the pulse height weighting technique. The present cross section values were compared with evaluated cross section data and previous measurements.

  9. Neutron Capture Gamma-Ray Spectroscopy. Proceedings of the International Symposium on Neutron Capture Gamma-Ray Spectroscopy

    International Nuclear Information System (INIS)

    Experimental capabilities in the field of neutron capture gamma-ray spectroscopy have expanded greatly in the last few years; this has been due in large part to the advent of high-quality Ge(Li) detectors, improvements in electronic data processing, and improvements in bent-crystal spectrometers. Previously unsuspected phenomena, such as the '5. 5-MeV1 anomaly, have appeared and new research tools, such as neutron guide tubes, have been brought into use. Equally exciting developments have occurred in the theory of neutron capture. Complex spectra have yielded to analysis after account had been taken of such effects as vibration, rotation and Coriolis forces, and the theoretical prediction of capture spectra seems to be a future possibility. In view of the International Atomic Energy Agency's close interest in this subject and the need for an international exchange of ideas to analyse and study the latest developments, the organizers of the Symposium felt that work on neutron capture gamma-ray spectroscopy had achieved such valuable and significant results that the time had come for this information to be presented, examined and discussed internationally

  10. Gamma-rays from Muon Capture in $^{14}$N

    CERN Document Server

    Stocki, T J; Gete, E; Saliba, M A; Moftah, B A; Gorringe, T P

    2001-01-01

    Many new $\\gamma$-rays have been observed, following muon capture on $^{14}$N. One had been reported before, and the low yield is confirmed, indicating that the nuclear structure of $^{14}$N is still not understood. Gamma-rays from $^{13}$C resulting from the reaction $^{14}$N($\\mu^{-}$,$\

  11. The uses of neutron capture {gamma}-rays in environmental pollution measurements

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Haleem, A.S.; Abdel-Samad, M.A. [Atomic Energy Authority, Cairo (Egypt). Hot Lab. Centre; Zaghloul, R.A. [Ministry of Scientific Research, Cairo (Egypt). Mubarak City for Scientific Research and Technology; Hassan, A.M. [Nuclear Research Centre, Cairo (Egypt). Reactor and Neutron Physics Dept.

    1996-05-01

    A neutron capture {gamma}-ray spectroscopy facility using an isotopic neutron source, {sup 252}Cf, has been installed and used for investigation of some environmental samples. The facility is designed and calibrated for measurement of the prompt {gamma}-ray spectra due to thermal neutron capture. Qualitative analysis studies of some local environmental samples have been carried out using some developed analytical programs. The experimental results of the environmental pollutant analysis are discussed. (author).

  12. Measurements of keV-neutron capture {gamma} rays of fission products. 3

    Energy Technology Data Exchange (ETDEWEB)

    Igashira, Masayuki [Tokyo Inst. of Tech. (Japan). Research Lab. for Nuclear Reactors

    1997-03-01

    {gamma} rays from the keV-neutron capture reactions by {sup 143,145}Nd and {sup 153}Eu have been measured in a neutron energy region of 10 to 80 keV, using a large anti-Compton NaI(Tl) {gamma}-ray spectrometer and the {sup 7}Li(p,n){sup 7}Be pulsed neutron source with a 3-MV Pelletron accelerator. The preliminary results for the capture cross sections and {gamma}-ray spectra of those nuclei are presented and discussed. (author)

  13. Librarian driven analysis of gamma ray spectra

    International Nuclear Information System (INIS)

    For a set of a priori given radionuclides extracted from a general nuclide data library, the authors use median estimates of the gamma-peak areas and estimates of their errors to produce a list of possible radionuclides matching gamma ray line(s). The identification of a given radionuclide is obtained by searching for a match with the energy information of a database. This procedure is performed in an interactive graphic mode by markers that superimpose, on the spectral data, the energy information and yields provided by a general gamma ray data library. This library of experimental data includes approximately 17,000 gamma ray energy lines related to 756 known gamma emitter radionuclides listed by the ICRP. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Prettyman, T. H. (Thomas H.); Feldman, W. C. (William C.); Lawrence, David J. (David Jeffery),; Elphic, R. C. (Richard C.); Gasnault, O. M. (Olivier M.); Maurice, S. (Sylvestre); Moore, K. R. (Kurt 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.

  15. New capture gamma-ray data for PGAA database

    International Nuclear Information System (INIS)

    A new catalogue of prompt gamma rays has been created on the basis of experiments at the Budapest PGAA facility. It contains elemental spectra and a table with nearly 7000 gamma rays with relative intensity over 1 percent of the strongest line. The average accuracy is about 0.08 keV for energies and about 5 percent for cross-sections in the whole energy range, from about 40 keV to 11 MeV. (author)

  16. Linear combination reading program for capture gamma rays

    Science.gov (United States)

    Tanner, Allan B.

    1971-01-01

    This program computes a weighting function, Qj, which gives a scalar output value of unity when applied to the spectrum of a desired element and a minimum value (considering statistics) when applied to spectra of materials not containing the desired element. Intermediate values are obtained for materials containing the desired element, in proportion to the amount of the element they contain. The program is written in the BASIC language in a format specific to the Hewlett-Packard 2000A Time-Sharing System, and is an adaptation of an earlier program for linear combination reading for X-ray fluorescence analysis (Tanner and Brinkerhoff, 1971). Following the program is a sample run from a study of the application of the linear combination technique to capture-gamma-ray analysis for calcium (report in preparation).

  17. Neutron-capture gamma-ray analysis of coal for sulfur, iron, silicon and moisture

    International Nuclear Information System (INIS)

    Samples of coal weighing approximately 200 grams placed in a collimated beam of neutrons from the thermal column of the Ames Laboratory Research Reactor produced capture gamma-rays which could be used for the simultaneous determination of sulfur and iron. Spectra from NaI(Tl) and Ge(Li) detectors were used and interferences were located by examining spectra of the major elemental components of coal. In determining sulfur, iron is a potential source of interference when gamma-ray spectra are collected with a NaI(Tl) detector. Corrections for iron interference were made by use of a higher energy iron peak. The possibility of determining silicon in coal was investigated but this element determination was unsuccessful since capture gamma-ray spectrometry lacked the necessary sensitivity for silicon. A linear relation was found between the area of the hydrogen capture peak at 2.23 MeV and the amount of water added to coal

  18. Monte Carlo simulations of plutonium gamma-ray spectra

    International Nuclear Information System (INIS)

    Monte Carlo calculations were investigated as a means of simulating the gamma-ray spectra of Pu. These simulated spectra will be used to develop and evaluate gamma-ray analysis techniques for various nondestructive measurements. Simulated spectra of calculational standards can be used for code intercomparisons, to understand systematic biases and to estimate minimum detection levels of existing and proposed nondestructive analysis instruments. The capability to simulate gamma-ray spectra from HPGe detectors could significantly reduce the costs of preparing large numbers of real reference materials. MCNP was used for the Monte Carlo transport of the photons. Results from the MCNP calculations were folded in with a detector response function for a realistic spectrum. Plutonium spectrum peaks were produced with Lorentzian shapes, for the x-rays, and Gaussian distributions. The MGA code determined the Pu isotopes and specific power of this calculated spectrum and compared it to a similar analysis on a measured spectrum

  19. Program DEIMOS32 for gamma-ray spectra evalution

    Czech Academy of Sciences Publication Activity Database

    Frána, Jaroslav

    2003-01-01

    Roč. 257, č. 3 (2003), s. 583-587. ISSN 0236-5731. [International Conference Ko-users Workshop /3./. Bruges, 23.09.2001-28.09.2001] Institutional research plan: CEZ:AV0Z1048901 Keywords : gamma-ray spectra * software Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.472, year: 2003

  20. User controlled analysis of gamma ray spectra

    International Nuclear Information System (INIS)

    The program 'ANGES' was designed as a general purpose high-resolution γ ray spectrometry program. It offers all main features as commercial software packages except control of acquisition process. The program is able to perform automatic analysis of spectra but it is announced as 'user controlled' because it supplies all intermediate results and gives the opportunity these results to be analyzed and corrected by the user. ANGES offers: multi document Windows interface; detailed visualization of spectra; nuclide library based on another contribution to CRP; energy and FWHM calibrations calculated by means of orthonormal polynomial fitting; peak processing engine based on a non-linear LSQ method for fitting peaks; peak location engine, based on first derivative method is provided to ease the preparation of a spectrum for processing; two methods for efficiency calibration (an efficiency calibration curve and reference table); peak identification and activity calculation procedure; a number of corrections (true coincidence summing, background correction, pile up rejection and so on); an option for processing series of similar spectra. The fitting procedure can be applied to the whole spectrum or to a single Region-of-Interest (ROI). The assumed peak shape is pure Gaussian. All peaks in single ROI are assumed to have the same FWHM. The maximum number of peaks in a single ROI is restricted to 25, the maximum ROI length is 512 channels, and the baseline is described with a polynomial of a degree up to 4. As a result of the identification procedure a report file is issued containing spectrum processing results, list of identified and not identified peaks, list of identified nuclides and background nuclides. (author)

  1. Gamma-ray spectra of 241Am

    International Nuclear Information System (INIS)

    The γ-spectrum of 241Am was reinvestigated by using intense sources (100 and 25 mCi) for the energy range of Eγ>60 keV, and purified solution source of about 10 μCi for the low energy and to make sure that the γ-lines present in the spectrum come from the α-decay of 241Am. The study was divided into three parts. The γ-spectrometers consists of 40 and 10% relative efficiency Hp Ge detectors and 8192 channel ADC for normal spectra, and Si-Li for low energy. Outs of 169 γ-lines that are presented in the spectrum 47 are new. The major part of the new gamma lines was observed in the energy range of Eγ≥200 keV. (author)

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

    Institute of Scientific and Technical Information of China (English)

    Wei Chen; Wei-Qun Gan

    2012-01-01

    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.

  3. Power Density Spectra of $\\gamma$-Ray Bursts

    CERN Document Server

    Beloborodov, A M

    1999-01-01

    Power density spectra (PDSs) of long gamma-ray bursts provide useful information on GRBs, indicating their self-similar temporal structure. The best power-law PDSs are displayed by the longest bursts (T_90 > 100 s) in which the range of self-similar time scales covers more than 2 decades. Shorter bursts have apparent PDS slopes more strongly affected by statistical fluctuations. The underlying power law can then be reproduced with high accuracy by averaging the PDSs for a large sample of bursts. This power-law has a slope alpha\\approx -5/3 and a sharp break at 1 Hz. The power-law PDS provides a new sensitive tool for studies of gamma-ray bursts. In particular, we calculate the PDSs of bright bursts in separate energy channels. The PDS flattens in the hard channel (h\

  4. Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Capture cross section and gamma-ray spectrum calculations for medium-weight nuclei

    International Nuclear Information System (INIS)

    A double-peak, energy-dependent Breit-Wigner model of the E1 gamma-ray strength function was applied to nuclei from As to Rh, to predict their neutron capture cross sections and capture gamma-ray spectra. A consistent set of model parameters was obtained in this mass region to describe the step in the low-energy tail of the E1 strength function. This step allows agreement with photonuclear data at high energies, the correct GAMMA/sub gamma/ to be obtained for agreement with neutron capture cross-section data, and the calculation of the observed hardness in the capture gamma-ray spectra. For nuclei at or near the closed, N = 50 shell, however, the double-peak assumption breaks down. In these cases, good results are still obtained if the same set of model parameters is applied, except that the E1 strength function is formulated in terms of the first, narrower peak. 8 figures

  6. The sharpness of gamma-ray burst prompt emission spectra

    Science.gov (United States)

    Yu, Hoi-Fung; van Eerten, Hendrik J.; Greiner, Jochen; Sari, Re'em; Narayana Bhat, P.; von Kienlin, Andreas; Paciesas, William S.; Preece, Robert D.

    2015-11-01

    Context. We study the sharpness of the time-resolved prompt emission spectra of gamma-ray bursts (GRBs) observed by the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope. Aims: We aim to obtain a measure of the curvature of time-resolved spectra that can be compared directly to theory. This tests the ability of models such as synchrotron emission to explain the peaks or breaks of GBM prompt emission spectra. Methods: We take the burst sample from the official Fermi GBM GRB time-resolved spectral catalog. We re-fit all spectra with a measured peak or break energy in the catalog best-fit models in various energy ranges, which cover the curvature around the spectral peak or break, resulting in a total of 1113 spectra being analyzed. We compute the sharpness angles under the peak or break of the triangle constructed under the model fit curves and compare them to the values obtained from various representative emission models: blackbody, single-electron synchrotron, synchrotron emission from a Maxwellian or power-law electron distribution. Results: We find that 35% of the time-resolved spectra are inconsistent with the single-electron synchrotron function, and 91% are inconsistent with the Maxwellian synchrotron function. The single temperature, single emission time, and location blackbody function is found to be sharper than all the spectra. No general evolutionary trend of the sharpness angle is observed, neither per burst nor for the whole population. It is found that the limiting case, a single temperature Maxwellian synchrotron function, can only contribute up to % of the peak flux. Conclusions: Our results show that even the sharpest but non-realistic case, the single-electron synchrotron function, cannot explain a large fraction of the observed GRB prompt spectra. Because any combination of physically possible synchrotron spectra added together will always further broaden the spectrum, emission mechanisms other than optically thin

  7. The width of gamma-ray burst spectra

    CERN Document Server

    Axelsson, Magnus

    2014-01-01

    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 $EF_E$ 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/GBM and CGRO/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% of long GRBs and 85% of short GRBs are incompatible wi...

  8. Database of prompt gamma rays from slow neutron capture for elemental analysis

    International Nuclear Information System (INIS)

    The increasing importance of prompt gamma ray activation analysis (PGAA) in a broad range of applications is evident, and has been emphasized at many meetings related to this topic. Furthermore, an Advisory Group Meeting (AGM) for the Coordination of the International Network of Nuclear Structure and Decay Data Evaluators concluded that there is a need for a complete library of gamma ray and cross-section data from cold and thermal neutron capture (the AGM was held in Budapest, 14-18 October 1996); this AGM also recommended the organization of an IAEA Coordinated Research Project (CRP) on this subject. The nuclear data programmes of the IAEA arose as a consequence of the advisory reviews of the International Nuclear Data Committee (INDC). At a biennial meeting in 1997, the INDC strongly recommended that the IAEA support new measurements and update the database on the analysis of prompt gamma ray activation induced by neutrons. As a consequence of the various recommendations, a CRP, entitled Development of a Database for Prompt Gamma Ray Neutron Activation Analysis (PGAA), was initiated in 1999. Prior to this project, several consultants had defined the scope, objectives and tasks of this CRP, as approved subsequently by the IAEA. Each CRP participant assumed responsibility for the execution of specific tasks. The results of their work and of other research were discussed and approved by the participants in Research Coordination Meetings (RCMs) held in 2000, 2001 and 2003. Prompt gamma ray activation analysis is a non-destructive radioanalytical method capable of rapid or simultaneous in situ multielement analyses across the entire periodic table, from hydrogen to uranium. However, inaccurate and incomplete data have been a significant hindrance in the qualitative and quantitative analyses of complicated neutron capture gamma spectra by means of PGAA. Therefore, the main goal of the CRP was to improve the quality and quantity of the required data in order to make

  9. Pulse Summing in the gamma-Ray Spectra

    CERN Document Server

    Gromov, K Ya; Samatov, Zh K; Chumin, V G

    2004-01-01

    It was shown that the peaks formed at the summing of the cascade gamma-rays pulses can be used for the determination of gamma-ray source activity and gamma-ray registration efficency. Possible sources of the determined quantities errors have been investigated. Such a method can be useful at the nuclear reaction cross section measurements, at background analysis in looking for rare decays and so on.

  10. The holistic analysis of gamma-ray spectra in instrumental neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Blaauw, M.

    1993-11-15

    The subject is the computerized analysis of the gamma-ray spectra in INAA. This analysis can be separated in three parts: The conversion of the spectra to information on {gamma}-ray energies and their relative intensities (spectrum reduction), the determination of the relation between the intensity of a {gamma}-ray and the amount of the corresponding element present in the sample (standardization) and the attribution of the {gamma}-ray energies to the elements, including the subsequent computation of the amounts of the elements (interpretation). A {gamma}-ray spectrum can be considered to be the linear sum of the {gamma}-ray spectra of the individual radionuclides present in the sample. Knowing the relative activities of the different radionuclides that may be produced by activation of a single element, a {gamma}-ray spectrum in INAA can also be considered to be the linear sum of the spectra of the elements. This principle has hitherto not been used in INAA to analyze the spectra by linear least squares methods, using all {gamma}-ray energies observed in the spectrum. The implementation of this `holistic` approach required that attention be paid to both spectrum reduction, standardization and interpretation. The thesis describes the methods developed for the holistic analysis of {gamma}-ray spectra in INAA, and present results of experimental comparisons between the holistic and other approaches. (orig./HP).

  11. Prompt gamma-ray detectors for the measurement of neutron capture cross-sections

    International Nuclear Information System (INIS)

    A review is given of current techniques for detecting prompt gamma-radiation as a means of measuring total capture cross-sections. The discussion is generally restricted to systems with low or moderate gamma-ray energy resolution. Three classes of detector are considered: (1) the total absorption type; (2) detectors with efficiency proportional to gamma-ray energy; and (3) detectors of low efficiency and known gamma-ray response. Particular attention is given to the problems of background from reactions which compete with neutron capture, and the sensitivity of capture detectors to scattered neutrons. The extraction of capture yields from observed data is briefly considered

  12. Augmentation of ENDF/B fission product gamma-ray spectra by calculated spectra

    International Nuclear Information System (INIS)

    Gamma-ray spectral data of the ENDF/B-V fission product decay data file have been augmented by calculated spectra. The calculations were performed with a model using beta strength functions and cascade gamma-ray transitions. The calculated spectra were applied to individual fission product nuclides. Comparisons with several hundred measured aggregate gamma spectra after fission were performed to confirm the applicability of the calculated spectra. The augmentation was extended to a preliminary ENDF/B-VI file, and to beta spectra. Appendix C provides information on the total decay energies for individual products and some comparisons of measured and aggregate values based on the preliminary ENDF/B-VI files. 15 refs., 411 figs

  13. Experimental simulation of A-bomb gamma ray spectra: Revisited

    International Nuclear Information System (INIS)

    It has been reported recently that the A-bomb gamma ray spectra received by the colon of the average Japanese survivor of Hiroshima and Nagasaki may be experimentally simulated using a hospital-based Philips SL15 linear accelerator. The simulated A-bomb gamma radiation may be used in radiobiology experiments to determine, amongst other things, the biological effectiveness of the A-bomb gamma radiation. However, in that study, the electron beams from the linear accelerator were poorly defined and photon contamination was ignored. In the study reported here, a Varian Clinac 2100C linear accelerator has been used for the same purpose but with photon contamination included in better defined output electron beams. It is found that the A-bomb gamma radiation can still be matched to an acceptable degree (<10%). The cause of the slightly poorer fit was due mainly to the different ranges of energies available from the linear accelerators used. The absorbed dose received by model breasts was also estimated in this study for the same situations as in the previous study. The ratio of the breast to colon doses was found to be only (3.9 ± 4.0)% low compared with the expected values of 1.17 and 1.16 for Hiroshima and Nagasaki, respectively. These results provide further confirmation of the acceptability of the simple cylindrically symmetrical body models employed in these studies to represent the average Japanese survivor. (authors)

  14. Landmine detection method combined with backscattering neutrons and capture {gamma}-rays from hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Yoshiyuki, E-mail: ytaka@rri.kyoto-u.ac.j [Graduate School of Energy Science, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501 (Japan); Misawa, Tsuyoshi; Pyeon, Cheol Ho; Shiroya, Seiji [Research Reactor Institute, Kyoto University, Asashiro-nishi, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Yoshikawa, Kiyoshi [Institute of Advanced Energy, Kyoto University, Gokashou, Uji-shi, Kyoto 611-0011 (Japan)

    2011-07-15

    The usefulness of the measurements of the backscattering neutron and 2.22 MeV capture {gamma}-ray from hydrogen in the landmine detection method is described in this paper. When the soil moisture content is increased, the reaction rates of both the neutron scattering reaction and capture reaction are increased. However, the backscattering neutrons are more influenced than the capture {gamma}-rays by the soil moisture before the reaction with the detector. The facts that the backscattering neutron method is useful in the dry soil case and that the capture {gamma}-ray method is effective in well-wet soil case are confirmed by the experiments and the calculations. The landmine detection efficiency is improved in various soil moisture conditions by combining the backscattering neutron method together with the capture {gamma}-ray method. The effectiveness of the pulse mode operation was confirmed numerically.

  15. MCNP modelling of scintillation-detector gamma-ray spectra from natural radionuclides

    NARCIS (Netherlands)

    Hendriks, Peter; Maucec, M; de Meijer, RJ

    2002-01-01

    gamma-ray spectra of natural radionuclides are simulated for a BGO detector in a borehole geometry using the Monte Carlo code MCNP. All gamma-ray emissions of the decay of K-40 and the series of Th-232 and U-238 are used to describe the source. A procedure is proposed which excludes the time-consumi

  16. The use of resonance scattering of capture gamma rays as an analytical tool

    International Nuclear Information System (INIS)

    The sensitivity for the resonance scattering of capture gamma rays as a tool to measure comparatively small concentrations of certain elements in bulk materials is investigated. Looking at the resonance for lead excited by iron capture gamma rays it is possible to measure concentrations down to less than 100 ppm. The advantages of the new technique are compared with other existing methods. The application of nuclear resonance scattering in prospecting for zirconium ores is emphasized

  17. Time-Integrated Gamma-Ray Burst Synchrotron Spectra from Blast Wave/Cloud Interactions

    OpenAIRE

    Chiang, James

    1998-01-01

    We show that the spectral shape of the low energy tails found for the time-integrated spectra of gamma-ray bursts, even in the absence of strong synchrotron cooling, can be significantly softer than the $\

  18. Determination of protein content in grains by radioactive thermal neutron capture prompt gamma rays analysis

    International Nuclear Information System (INIS)

    The radioactive thermal neutron capture prompt gamma rays technique can be used to determinate the nitrogen content in grains without chemical destruction, with good precision and relative rapidity. This determination is based on the detection of prompt gamma rays emitted by the 14N(n,γ) 15N reaction product. The samples has been irradiated the tanGencial tube of the IEA-R1 research reator and a pair spectrometer has been used for the detection of the prompt gamma rays. The nitrogen content is determinated in several samples of soybean, commonbean, peas and rice, and the results is compared with typical nitrogen content for each grain. (Autor)

  19. Database of prompt gamma rays from slow neutron capture for elemental analysis

    International Nuclear Information System (INIS)

    The increasing importance of Prompt Gamma-ray Activation Analysis (PGAA) in a broad range of applications is evident, and has been emphasized at many meetings related to this topic (e.g., Technical Consultants' Meeting, Use of neutron beams for low- and medium-flux research reactors: radiography and materials characterizations, IAEA Vienna, 4-7 May 1993, IAEA-TECDOC-837, 1993). Furthermore, an Advisory Group Meeting (AGM) for the Coordination of the Nuclear Structure and Decay Data Evaluators Network has stated that there is a need for a complete and consistent library of cold- and thermal neutron capture gamma ray and cross-section data (AGM held at Budapest,14-18 October 1996, INDC(NDS)-363); this AGM also recommended the organization of an IAEA CRP on the subject. The International Nuclear Data Committee (INDC) is the primary advisory body to the IAEA Nuclear Data Section on their nuclear data programs. At a biennial meeting in 1997, the INDC strongly recommended that the Nuclear Data Section support new measurements and update the database on Neutron-induced Prompt Gamma-ray Activation Analysis (21st INDC meeting, INDC/P(97)-20). As a consequence of the various recommendations, a CRP on ''Development of a Database for Prompt Gamma-ray Neutron Activation Analysis (PGAA)'' was initiated in 1999. Prior to this project, several consultants had defined the scope, objectives and tasks, as approved subsequently by the IAEA. Each CRP participant assumed responsibility for the execution of specific tasks. The results of their and other research work were discussed and approved by the participants in research co-ordination meetings (see Summary reports: INDC(NDS)-411, 2000; INDC(NDS)-424, 2001; and INDC(NDS)-443, 200). PGAA is a non-destructive radioanalytical method, capable of rapid or simultaneous ''in-situ'' multi-element analyses across the entire Periodic Table, from hydrogen to uranium. However, inaccurate and incomplete data were a significant hindrance in the

  20. Individual power density spectra of Swift gamma-ray bursts

    Science.gov (United States)

    Guidorzi, C.; Dichiara, S.; Amati, L.

    2016-05-01

    Context. Timing analysis can be a powerful tool with which to shed light on the still obscure emission physics and geometry of the prompt emission of gamma-ray bursts (GRBs). Fourier power density spectra (PDS) characterise time series as stochastic processes and can be used to search for coherent pulsations and, more in general, to investigate the dominant variability timescales in astrophysical sources. Because of the limited duration and of the statistical properties involved, modelling the PDS of individual GRBs is challenging, and only average PDS of large samples have been discussed in the literature thus far. Aims: We aim at characterising the individual PDS of GRBs to describe their variability in terms of a stochastic process, to explore their variety, and to carry out for the first time a systematic search for periodic signals and for a link between PDS properties and other GRB observables. Methods: We present a Bayesian procedure that uses a Markov chain Monte Carlo technique and apply it to study the individual PDS of 215 bright long GRBs detected with the Swift Burst Alert Telescope in the 15-150 keV band from January 2005 to May 2015. The PDS are modelled with a power-law either with or without a break. Results: Two classes of GRBs emerge: with or without a unique dominant timescale. A comparison with active galactic nuclei (AGNs) reveals similar distributions of PDS slopes. Unexpectedly, GRBs with subsecond-dominant timescales and duration longer than a few tens of seconds in the source frame appear to be either very rare or altogether absent. Three GRBs are found with possible evidence for a periodic signal at 3.0-3.2σ (Gaussian) significance, corresponding to a multi-trial chance probability of ~1%. Thus, we found no compelling evidence for periodic signal in GRBs. Conclusions: The analogy between the PDS of GRBs and of AGNs could tentatively indicate similar stochastic processes that rule BH accretion across different BH mass scales and objects

  1. Photoneutron cross sections measurements in {sup 13}C with thermal neutron capture gamma-rays

    Energy Technology Data Exchange (ETDEWEB)

    Semmler, Renato; Carbonari, Artur W.; Terremoto, Luis A.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: rsemmler@ipen.br; carbonar@ipen.br; laaterre@ipen.br; Goncalez, Odair L. [Centro Tecnico Aeroespacial (CTA-IEAv), Sao Jose dos Campos, SP (Brazil). Inst. de Estudos Avancados]. E-mail: odairl@ieav.cta.br

    2007-07-01

    Photoneutrons cross sections measurements of {sup 13}C have been obtained in energy interval between 5,3 and 10,8 MeV, using neutron capture gamma-rays with high resolution in energy (3 - 21 eV), produced by 21 target materials, placed inside a tangential beam port, near the core of the IPEN/CNEN-SP IEA-R1 (2MW) research reactor. The sample have been irradiated inside a 4p geometry neutron detector system 'Long Counter', 520,5 cm away from the capture target. The capture gamma-ray flux was determined by means of the analysis of the gamma spectrum obtained by using a Ge(Li) solid-state detector (EG and G ORTEC, 25 cm{sup 3}, 5%), previously calibrated with capture gamma-rays from a standard target of Nitrogen (Melamine). The neutron photoproduction cross section has been measured for each target capture gamma-ray spectrum (compound cross section). A methodology for unfolding the set of experimental compound cross sections, have been used in order to obtain the cross sections at specific excitation energy values (principal gamma lines energies of the capture targets). The cross sections were compared with experimental data, reported by other authors, using different gamma-ray sources. A good agreement was observed between in this work and reported in the literature. (author)

  2. Photoneutron cross sections measurements in 13C with thermal neutron capture gamma-rays

    International Nuclear Information System (INIS)

    Photoneutrons cross sections measurements of 13C have been obtained in energy interval between 5,3 and 10,8 MeV, using neutron capture gamma-rays with high resolution in energy (3 - 21 eV), produced by 21 target materials, placed inside a tangential beam port, near the core of the IPEN/CNEN-SP IEA-R1 (2MW) research reactor. The sample have been irradiated inside a 4p geometry neutron detector system 'Long Counter', 520,5 cm away from the capture target. The capture gamma-ray flux was determined by means of the analysis of the gamma spectrum obtained by using a Ge(Li) solid-state detector (EG and G ORTEC, 25 cm3, 5%), previously calibrated with capture gamma-rays from a standard target of Nitrogen (Melamine). The neutron photoproduction cross section has been measured for each target capture gamma-ray spectrum (compound cross section). A methodology for unfolding the set of experimental compound cross sections, have been used in order to obtain the cross sections at specific excitation energy values (principal gamma lines energies of the capture targets). The cross sections were compared with experimental data, reported by other authors, using different gamma-ray sources. A good agreement was observed between in this work and reported in the literature. (author)

  3. Analysis of Phobos mission gamma ray spectra from Mars

    Science.gov (United States)

    Trombka, J. I.; Evans, L. G.; Starr, R.; Floyd, S. R.; Squyres, S. W.; Whelan, J. T.; Bamford, G. J.; Coldwell, R. L.; Rester, A. C.; Surkov, Iu. A.

    1992-01-01

    The determination of the elemental composition of the surface of a planetary body can be achieved, in many cases, by remote-sensing gamma ray spectroscopy. A gamma ray spectrometer was carried on the Soviet spacecraft Phobos-2, and obtained data while in an elliptical orbit around Mars. Results of two independent approaches to data analysis, one by the Soviet group and one by an American group are reported. The results for five elements are given for two different orbits of Mars. Major geologic units that contribute to the signal for each orbit have been identified. The results from the two techniques are in general agreement and there appear to be no geologically significant differences between the results for each orbit.

  4. Processing of gamma-ray spectra employing a Fourier deconvolver for the analysis of complex spectra

    International Nuclear Information System (INIS)

    Processing of a nuclear spectrum e.g. gamma ray spectrum is concerned with the estimation of energies and intensities of radiation. The processing involves filtering, peak detection and its significance, baseline delineation, the qualitative and the quantitative analysis of singlets and multiplets present in the spectrum. The methodology for the analysis of singlets is well established. However, the analysis of multiplets provides a challenge and is a extremely difficult problem. This report incorporates a Fourier deconvolver for the quantitative analysis of doublets separated by more than a full width at half maximum. The method is easy to implement. The report discusses the methodology, mathematical analysis, and the results obtained by analyzing both synthetic and observed spectra. A computer program, developed for the analysis of a nuclear spectrum, was verified by analyzing a 152Eu gamma ray spectrum. The proposed technique compared favourably with SAMPO and MDFT method. (author). 16 refs., 3 tabs

  5. VISPECT program evaluation in gamma-ray spectra analysis of neutron-activated geological samples

    International Nuclear Information System (INIS)

    A comparative evaluation of gamma-ray analysis software VISPECT in relation to two commercial gamma-ray analysis software packages OMNIGAM (EG and GORTEC) and SAMPO 90 (CANBERRA) was performed. For this evaluation, artificial gamma-ray spectra were created, presenting peaks of different intensities and located at different regions of the spectrum. Multiplet peaks with equal and different intensities, but with different channel separations were also created. Neutron activation analysis of the reference material GS-N (IWG-GIT) was also performed, aiming the evaluation of the program VISPECT in the analysis of a geological sample. (author)

  6. Experimental Measurements and Computer Simulation of Fission Product Gamma-Ray Spectra

    OpenAIRE

    Sanderson, D.C.W; Cresswell, A.; Allyson, J.D.; McConville, P.

    1997-01-01

    Airborne gamma ray spectrometry using high volume scintillation detectors, optionally in conjunction with Ge detectors, has potential for making rapid environmental measurements in response to nuclear accidents. An experimental investigation and computer simulation have been used to characterise the response of such detectors to short lived fission products. Small samples of 235U were irradiated in a research reactor for short periods, to generate fission product sources. Gamma ray spectra w...

  7. Review of Past Nuclear Accidents: Source Terms and Recorded Gamma-Ray Spectra

    OpenAIRE

    Sanderson, D.C.W.; Cresswell, A.; Allyson, J.D.; McConville, P.

    1997-01-01

    Airborne gamma ray spectrometry using high volume scintillation detectors, optionally in conjunction with Ge detectors, has potential for making rapid environmental measurements in response to nuclear accidents. A literature search on past nuclear accidents has been conducted to define the source terms which have been experienced so far. Selected gamma ray spectra recorded after past accidents have also been collated to examine the complexity of observed behaviour.

  8. Anomalies in low-energy Gamma-Ray Burst spectra with the Fermi Gamma-Ray Burst Monitor

    CERN Document Server

    Tierney, Dave; Preece, Robert D; Fitzpatrick, Gerard; Foley, Suzanne; Guiriec, Sylvain; Bissaldi, Elisabetta; Briggs, Michael S; Burgess, J Michael; Connaughton, Valerie; Goldstein, Adam; Greiner, Jochen; Gruber, David; Kouveliotou, Chryssa; McGlynn, Sinead; Paciesas, William S; Pelassa, Veronique; von Kienlin, Andreas

    2013-01-01

    A Band function has become the standard spectral function used to describe the prompt emission spectra of gamma-ray bursts (GRBs). However, deviations from this function have previously been observed in GRBs detected by BATSE and in individual GRBs from the \\textit{Fermi} era. We present a systematic and rigorous search for spectral deviations from a Band function at low energies in a sample of the first two years of high fluence, long bursts detected by the \\textit{Fermi} Gamma-Ray Burst Monitor (GBM). The sample contains 45 bursts with a fluence greater than 2$\\times10^{-5}$ erg / cm$^{2}$ (10 - 1000 keV). An extrapolated fit method is used to search for low-energy spectral anomalies, whereby a Band function is fit above a variable low-energy threshold and then the best fit function is extrapolated to lower energy data. Deviations are quantified by examining residuals derived from the extrapolated function and the data and their significance is determined via comprehensive simulations which account for the ...

  9. Dose Rate Determination from Airborne Gamma-ray Spectra

    DEFF Research Database (Denmark)

    Bargholz, Kim

    1996-01-01

    The standard method for determination of ground level dose rates from airborne gamma-ray is the integral count rate which for a constant flying altitude is assumed proportional to the dose rate. The method gives reasonably results for natural radioactivity which almost always has the same energy...... distribution. When manmade radioactivity is present, this is no longer the case. Another method based on giving the counts of different channels a different weighting has been examined. The new method is more robust against varying energy distribution, and for energies above 200 keV it gives excellent results....

  10. PEPIN, Methodology for Computing Concentrations, Activities, Gamma-Ray Spectra, and Residual Heat from Fission Products

    International Nuclear Information System (INIS)

    1 - Description of program or function: The concentrations, activities, gamma-ray spectra and residual heat from fission products can be calculated as a function of time for instantaneous fission or for one or more irradiation steps. 2 - Methods: Using the basic data in the libraries, the PEPIN code solves the differential equations satisfied by the fission product concentrations. Data Libraries: Independent Yields Library: 8 independent yields for 235U, 238U, 239U, 232U, 233U. Chain library: Precursor chain file for 635 nuclides. Gamma-Ray Energies Library: Average beta and gamma-ray energies in increasing order. 3 - Restrictions on the complexity of the problem: The number of nuclides must not exceed 650. The number of Gamma-Rays must not exceed 8500. The number of decay times must not exceed 59. The number of irradiation steps must not exceed 40

  11. Portable microcomputer unit for the analysis of plutonium gamma-ray spectra

    International Nuclear Information System (INIS)

    A portable microcomputer has been developed for the IAEA to perform in-field analysis of plutonium gamma-ray spectra. The unit includes a 16-bit LSI-11/2 microprocessor, 32K words of memory, a 20-character display for user prompting, and a 20-character thermal printer for hardcopy output. Only the positions of the 148-keV Pu-241 and 208-keV U-237 peaks are required for spectral analysis. The unit was tested against gamma-ray spectra taken of NBS plutonium standards and IAEA spectra. Results obtained are presented

  12. The gamma-ray spectra of halocarbons in positron–electron annihilation process

    International Nuclear Information System (INIS)

    The gamma-ray spectra of the positron annihilation process in methane CH4 and its fully substituent halocarbons CF4, CCl4, and CBr4 have been studied. The theoretical predictions of the inner valence electrons agree well with the experimental measurements for all these molecules. That the outermost s electrons in carbon or halogen atoms dominate the gamma-ray spectra has been confirmed for the first time. The positrophilic site has also been found in these molecules and understanding of annihilation processes in molecules has been enhanced. - Highlights: • The inner valence electrons in molecules dominate the Doppler shift. • The outermost atomic s electrons in molecules show dominance in the gamma-ray spectra. • The positron can penetrate deeper inside molecules in positrophilic sites to annihilate with inner valence electrons

  13. gamma ray spectra measurement in WWER-1000 reactor pressure vessel simulator

    International Nuclear Information System (INIS)

    The gamma spectra are to be measured in order to evaluate the possible contribution of the gamma rays to the radiation damage of the reactor pressure vessel (RPV) steel. The results should be used for benchmarking of the calculation of the gamma-ray RPV exposure. The measurements are carried out in the WWER-1000 simulator assembled in the LR-O experimental reactor in NRI Rez. The gamma-ray spectra are measured with the stilbene scintilator spectrometer in the energy range 0.8-10 MeV. The same spectrometer (with smaller stilbene detector) could be used for the measurement of the neutron spectra measurement in the energy range 0.8-10 MeV (Authors)

  14. The gamma-ray spectra of halocarbons in positron–electron annihilation process

    Energy Technology Data Exchange (ETDEWEB)

    Ma, X.G., E-mail: hsiaoguangma@188.com; Zhu, Y.H.; Liu, Y.

    2015-10-09

    The gamma-ray spectra of the positron annihilation process in methane CH{sub 4} and its fully substituent halocarbons CF{sub 4}, CCl{sub 4}, and CBr{sub 4} have been studied. The theoretical predictions of the inner valence electrons agree well with the experimental measurements for all these molecules. That the outermost s electrons in carbon or halogen atoms dominate the gamma-ray spectra has been confirmed for the first time. The positrophilic site has also been found in these molecules and understanding of annihilation processes in molecules has been enhanced. - Highlights: • The inner valence electrons in molecules dominate the Doppler shift. • The outermost atomic s electrons in molecules show dominance in the gamma-ray spectra. • The positron can penetrate deeper inside molecules in positrophilic sites to annihilate with inner valence electrons.

  15. Concept of capture credit based on neutron-induced gamma ray spectroscopy

    International Nuclear Information System (INIS)

    Capture credit (CapC) based on neutron-induced gamma ray spectroscopy (NIGS) is proposed to confirm the subcriticality of fuel debris in which nuclear fuel and structural materials are co-melted or mixed. By NIGS, rates of some capture reactions can be measured in relation to fission reactions. By the ratio, we can credit the negative reactivity inserted by the capture reactions. The theory of CapC is described. In order to demonstrate the benefit to take CapC for storage of the fuel debris, numerical simulations are performed for a hypothetical array of canisters in which the fuel debris is stored. A procedure of CapC based on NIGS is also proposed, which consists of several technologies: (1) NIGS, (2) simulations of a response and an efficiency of the γ ray detection, and (3) unfolding of the γ ray pulse height spectrum to obtain reaction rates. Experimental studies of NIGS have been launched in Kyoto university critical assembly facility. NIGS is firstly studied for simulated fuel debris of a few kinds of mixture of stainless steel and uranium in subcritical systems. The measured γ ray pulse height spectra and preliminary analyses indicate that CapC based on NIGS is worth to be investigated further for the efficient storage of fuel debris. (author)

  16. Database of prompt gamma rays from slow neutron capture forelemental analysis

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, R.B.; Choi, H.D.; Lindstrom, R.M.; Molnar, G.L.; Mughabghab, S.F.; Paviotti-Corcuera, R.; Revay, Zs; Trkov, A.; Zhou,C.M.; Zerkin, V.

    2004-12-31

    analysis of complicated capture-gamma spectra by means ofPGAA. Therefore, the main goal of the CRP was to improve the quality andquantity of the required data in order to make possible the reliableapplication of PGAA in fields such as materials science, chemistry,geology, mining, archaeology, environment, food analysis and medicine.This aim wasachieved thanks to the dedicated work and effort of theparticipants. The CD-ROM included with this publication contains thedatabase, the retrieval system, the three CRM reports, and otherimportant electronic documents related to the CRP. The IAEA wishes tothanks all CRP participants who contributed to the success of the CRP andthe formulation of this publication. Special thanks are due to R.B.Firestone for his leading roll in the development of this CRP and hiscomprehensive compilation, analysis and provision of the adopteddatabase, and to V. Zerkin for the software developments associatedwiththe retrieval system. An essential component of this data compilation isthe extensive sets of new measurements of capture gamma-ray energies andintensities undertaken at Budapest by Zs. Revay under the direction ofG.L. Molnar. The extensive participation and assistance of H.D. Choi isalso greatly appreciated. Other participants inthis CRP were: R.M.Lindstrom, S.M. Mughabghab, A.V.R. Reddy, V.H. Tan and C.M. Zhou. Thanksare also due to S.C. Frankle and M.A. Lone for their active participationas consultants at some of the meetings. Finally, the participants wish tothank R. Paviotti-Corcuera (Nuclear Data Section, Division of Physicaland Chemical Sciences), who was the IAEA responsible officer for the CRP,this publication and the resulting database. The participants aregrateful to D.L. Muir and A.L. Nichols, successive Heads of the NuclearData Section, for their active and enthusiastic encouragement infurthering the work of the CRP.

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

    International Nuclear Information System (INIS)

    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: (1) a data-transfer application for transferring spectral data from a CICERO multichannel analyzer to a binary data file, (2) a data-analysis application to analyze plutonium gamma-ray spectra for plutonium isotopic ratios and weight percents of total plutonium, (3) and a data-quality assurance application to check spectral data for proper data-acquisition setup and performance. Volume 2 describes the operations of these applications and the installation and maintenance of the software

  18. Irregularity in gamma ray source spectra as a signature of axionlike particles

    CERN Document Server

    Wouters, Denis

    2012-01-01

    Oscillations from high energy photons into light pseudoscalar particles in an external magnetic field is expected to happen in some extensions of the Standard Model. It is usually assumed that those axionlike particles (ALPs) could produce a drop in the energy spectra of gamma ray sources and possibly decrease the opacity of the Universe for TeV gamma rays. We show here that these assumptions are in fact based on an average behavior that cannot happen in real observations of single sources. We propose a new method to search for photon-ALP oscillations, taking advantage of the fact that a single observation would deviate from the average expectation. Our method is based on the search for irregularities in the energy spectra of gamma ray sources. We predict features that are unlikely to be produced by known astrophysical processes and a new signature of ALPs that is easily falsifiable.

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

    International Nuclear Information System (INIS)

    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

  20. Gamma rays from muon capture in sup 1 sup 4 N

    CERN Document Server

    Stocki, T J; Gete, E; Saliba, M A; Moftah, B A; Gorringe, T P

    2002-01-01

    Many new gamma-rays have been observed, following muon capture on sup 1 sup 4 N. One had been reported before, and the low yield is confirmed, indicating that the nuclear structure of sup 1 sup 4 N is still not understood. Gamma rays from sup 1 sup 3 C resulting from the reaction sup 1 sup 4 N(mu sup - ,nu n) sup 1 sup 3 C compare favourably with states observed in the reaction sup 1 sup 4 N(gamma, p) sup 1 sup 3 C. More precise energies are also given for the 7017 and 6730 keV gamma-rays in sup 1 sup 4 C.

  1. Nuclear resonant scattering of capture gamma rays on Sb

    International Nuclear Information System (INIS)

    Monochromatic photons obtained from thermal neutron capture in titanium were used for exciting nuclear levels in antimony. Angular distribution of the elastic scattered radiation was carried-out for the determination of the spins of the resonance levels. Total and ground state radiation widths of resonance levels were measured using self absorption and temperature variation measurements

  2. Conversion of Airborne Gamma ray Spectra to Ground Level Air Kerma Rates

    DEFF Research Database (Denmark)

    Bargholz, Kim; Korsbech, Uffe C C

    A new method for relating airborne gamma-ray spectra to dose rates and kerma rates at ground level is presented. Dependent on flying altitude 50 m to 125 m the method gives correct results for gamma energies above 250 keV respective 350 keV. At lower energies the method underestimate the dose or ...

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

    Science.gov (United States)

    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.

  4. Gamma ray spectra recorded from the fallout collected in May 1986

    International Nuclear Information System (INIS)

    An analysis of the gamma ray spectra recorded from the fallout collective in Bucharest and Brasov in May, 1986 was carried out. Relative activities of the assigned radionuclides were computed and the duration of the 235U fuel irradiation has been deduced. (author)

  5. Catalogue of response spectra for unfolding in situ gamma-ray pulse-height distributions

    International Nuclear Information System (INIS)

    To unfold in situ gamma-ray pulse-height distributions by means of a response matrix technique, the matrix must be in keeping with the measurement geometry, detector size, and energy range to be covered by the measurements. A methodology has been described for determination of standard gamma-ray spectra needed in deriving response matrices and a spectrum catalogue compiled containing graphs and data for the 0-3 MeV (4 x 4 in. NaI(Tl)) and 0-8 MeV (1.5 x 1.5 in. NaI(Tl)) ranges. (author)

  6. Automatic processing of gamma ray spectra employing classical and modified Fourier transform approach

    International Nuclear Information System (INIS)

    This report describes methods for automatic processing of gamma ray spectra acquired with HPGe detectors. The processing incorporated both classical and signal processing approach. The classical method was used for smoothing, detecting significant peaks, finding peak envelope limits and a proposed method of finding peak limits, peak significance index, full width at half maximum, detecting doublets for further analysis. To facilitate application of signal processing to nuclear spectra, Madan et al. gave a new classification of signals and identified nuclear spectra as Type II signals, mathematically formalized modified Fourier transform and pioneered its application to process doublet envelopes acquired with modern spectrometers. It was extended to facilitate routine analysis of the spectra. A facility for energy and efficiency calibration was also included. The results obtained by analyzing observed gamma-ray spectra using the above approach compared favourably with those obtained with SAMPO and also those derived from table of radioisotopes. (author). 15 refs., 3 figs., 3 tabs

  7. Simulations to neutron-induced gamma ray spectra of light nuclides in TNT

    International Nuclear Information System (INIS)

    There are several factors affecting the detection of explosive or landmine using neutron-induced reactions, such as the neutron source, detector, object and surroundings. In this paper,using a system of NaI(Tl) or BGO detectors and an Am-Be neutron source, prompt gamma ray spectra from nuclides in TNT of landmine in soil are simulated by MCNP. The counts of full energy characteristic peaks of gamma rays from hydrogen, carbon, nitrogen and oxygen in TNT are related to the explosive mass. Effects of the soil moisture on the gamma-ray spectrum are studied. The ratio of full energy peak counts from nitrogen to full energy peak counts from carbon is defined. A method to use the ratio to identify explosives under water environment is proposed. (authors)

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

    International Nuclear Information System (INIS)

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

  9. A distribution-free test for anomalous gamma-ray spectra

    International Nuclear Information System (INIS)

    Gamma-ray spectra are increasingly acquired in monitoring cross-border traffic, or in an area search for lost or orphan special nuclear material (SNM). The signal in such data is generally weak, resulting in poorly resolved spectra, thereby making it hard to detect the presence of SNM. We develop a new test for detecting anomalous spectra by characterizing the complete shape change in a spectrum from background radiation; the proposed method may serve as a tripwire for routine screening for SNM. We show that, with increasing detection time, the limiting distribution of the test is given by some functional of the Brownian bridge. The efficacy of the proposed method is illustrated by simulations. - Highlights: • We develop a new non-parametric test for detecting anomalous gamma-ray spectra. • The proposed test has good empirical power for detecting weak signals. • It can serve as an effective tripwire for invoking more thorough scrutiny of the source

  10. Decomposition Of Continuum GAMMA Ray Spectra For Point Sources By Using Gold Algorithm

    International Nuclear Information System (INIS)

    In this work, we try for decomposition of continuum gamma ray spectra using Gold algorithm. The problem is applied for the gamma spectra of Co-60, Cs-137 and Eu-152 point source for HPGe GC2018 gamma spectroscopy. The results show that the convergence speed is faster than results for using MLEM algorithm and the largest difference of the peak area ratios before and after unfolding from P/T values decreases 15%. (author)

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

    Science.gov (United States)

    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. PMID:19864704

  12. Assembly and calibration of a new experimental apparatus for production and utilization of capture gamma rays

    International Nuclear Information System (INIS)

    A new experimental apparatus has been mounted at the tangential beam tube B H 4/12 of the IPEN IEA-R1 (2 MW) reactor, for production and utilization of capture gamma rays. In this type of experiment, monochromatic gamma radiation, with energy resolution of about 10 eV, is produced by thermal neutron capture in several materials placed near the reactor core. By changing the target material it was possible to obtain up to 30 gamma lines in the 5 to 11 MeV energy range and so, the present experimental arrangement may be considered as an excellent gamma ray source for photonuclear reactions studies in low excitation energies. (author)

  13. Investigation of photoneutron and capture gamma-ray production in Pb and W under irradiation from 16N decay radiation

    International Nuclear Information System (INIS)

    Highlights: • MCNP used to investigate (γ,n) and (n,γ) in Pb and W due to interaction with 16N decay γ-rays and β. • Evidence of photoneutrons and capture gamma rays observed. • Bremsstrahlung from 16N beta spectrum insufficient to generate photoneutrons. - Abstract: Lead and tungsten are potential alternative materials for shielding reactor ex-core components with high 16N activity when available space limits application of concrete. Since the two materials are vulnerable to photonuclear reactions, the nature and intensity of the secondary radiation resulting from (γ,n) and (n,γ) reactions when 16N decay radiation interact with these materials need to be well known for effective shielding design. In this study the MCNP code was used to calculate the photoneutron and capture gamma-ray spectra in the two materials when irradiated by 16N decay radiation. It was observed that some of the photoneutrons generated in the two materials lie in the low-energy range which is considered optimum for (n,γ) reactions. Lead is more transparent to the photoneutrons when compared to tungsten. The calculations also revealed that the bremsstrahlung generated by the beta spectrum was not sufficient to trigger any additional photoneutrons. Both energetic and less energetic capture gamma-rays are observed when photoneutrons interact with nuclei of the two materials. Depending on the strength of the 16N source term, the secondary radiation could affect the effectiveness of the shield and need to be considered during design

  14. Individual power density spectra of Swift gamma-ray bursts

    CERN Document Server

    Guidorzi, C; Amati, L

    2016-01-01

    Timing analysis is a powerful tool with which to shed light on the still obscure emission physics and geometry of the prompt emission of GRBs. Fourier power density spectra (PDS) characterise time series as stochastic processes and can be used to search for coherent pulsations and to investigate the dominant variability timescales. Because of the limited duration and of the statistical properties, modelling the PDS of individual GRBs is challenging, and only average PDS of large samples have been discussed in the literature. We characterise the individual PDS of GRBs in terms of a stochastic process, and carry out for the first time a systematic search for periodic signals and for a link between the PDS and other observables. We present a Bayesian procedure that uses a Markov chain Monte Carlo technique and apply it to study 215 bright long GRBs detected with the Swift Burst Alert Telescope from January 2005 to May 2015. The PDS are modelled with a power-law either with or without a break. Two classes of GRBs...

  15. Calculation of neutron and gamma ray energy spectra for fusion reactor shield design: comparison with experiment

    International Nuclear Information System (INIS)

    Integral experiments that measure the transport of approx. 14 MeV D-T neutrons through laminated slabs of proposed fusion reactor shield materials have been carried out. Measured and calculated neutron and gamma ray energy spectra are compared as a function of the thickness and composition of stainless steel type 304, borated polyethylene, and Hevimet (a tungsten alloy), and as a function of detector position behind these materials. The measured data were obtained using a NE-213 liquid scintillator using pulse-shape discrimination methods to resolve neutron and gamma ray pulse height data and spectral unfolding methods to convert these data to energy spectra. The calculated data were obtained using two-dimensional discrete ordinates radiation transport methods in a complex calculational network that takes into account the energy-angle dependence of the D-T neutrons and the nonphysical anomalies of the S/sub n/ method

  16. Resonance Spin Memory in Low-Energy Gamma-Ray Spectra from Sb, Tb, Ho and Ta Odd-Odd Compound Nuclei

    CERN Document Server

    Olejniczak, U; Pikelner, L B; Przytula, M; Serov, D G

    2002-01-01

    The low-energy gamma-ray spectra from neutron resonance capture with natural samples of Sb, Tb, Ho and Ta were measured using HPGe detector at IBR-30 pulsed reactor (JINR, Dubna). The resonance spin memory effect in the spectra from the odd-odd compound nuclei of ^{122}Tb, ^{160}Tb and ^[166}Ho was found to be quite distinct. For the ^{182}Ta compound nucleus it proved to be rather weak.

  17. Resonance spin memory in low-energy gamma-ray spectra from Sb, Tb, Ho and Ta odd-odd compound nuclei

    International Nuclear Information System (INIS)

    The low-energy gamma-ray spectra from neutron resonance capture with natural samples of Sb, Tb, Ho and Ta were measured using a HPGe detector at the IBR-30 pulsed reactor (JINR, Dubna). The resonance spin memory effect in the spectra from the odd-odd compound nuclei of 122Sb, 160Tb and 166Ho was found to be quite distinct. For the 182Ta compound nucleus it proved to be rather weak

  18. The rapid reduction of gamma-ray spectra with a desk-top calculator

    International Nuclear Information System (INIS)

    A programme has been written for a desk-top programmable calculator, so that gamma-ray spectra can be processed immediately after the counting of active samples. The programme has some unusual features, among them automatic boundary selection and rejection of insignificant peaks. Operation is quick and simple, and the results agree well with those obtained from an I.B.M. computer, Model 370/158

  19. Detection efficiency for radionuclides decaying by electron capture and gamma-Ray

    International Nuclear Information System (INIS)

    In this paper, the electron capture partial counting efficiency vs the figure of merit for electron-capture and gamma-ray emitters has been computed. The radionuclides tabulated are 48cr, 54Mn, 57Co 56Ni, 72Se, 73As, 85Sr, 88Zr, 92Nb, 103Pd, 111ln, 119Sb, 125I, 139Ce and 152Dy. It has been assumed that the liquid is a toluene based scintillator solution in standard glass vials containing 15 cm3. (Author) 17 refs

  20. Strong MgII systems in quasar and gamma-ray burst spectra

    OpenAIRE

    Porciani, Cristiano; Viel, Matteo; Lilly, Simon J.

    2007-01-01

    The incidence of strong MgII systems in gamma-ray burst (GRB) spectra is a few times higher than in quasar (QSO) spectra. We investigate several possible explanations for this effect, including: dust obscuration bias, clustering of the absorbers, different beam sizes of the sources, multiband magnification bias of GRBs, association of the absorbers with the GRB event or the circumburst environment. We find that: i) the incidence rate of MgII systems in QSO spectra could be underestimated by a...

  1. Investigation of photoneutron and capture gamma-ray production in Pb and W under irradiation from 16N decay radiation

    Science.gov (United States)

    Kebwaro, Jeremiah Monari; Zhao, Yaolin; He, Chaohui

    2015-09-01

    Lead and tungsten are potential alternative materials for shielding reactor ex-core components with high 16N activity when available space limits application of concrete. Since the two materials are vulnerable to photonuclear reactions, the nature and intensity of the secondary radiation resulting from (γ,n) and (n,γ) reactions when 16N decay radiation interact with these materials need to be well known for effective shielding design. In this study the MCNP code was used to calculate the photoneutron and capture gamma-ray spectra in the two materials when irradiated by 16N decay radiation. It was observed that some of the photoneutrons generated in the two materials lie in the low-energy range which is considered optimum for (n,γ) reactions. Lead is more transparent to the photoneutrons when compared to tungsten. The calculations also revealed that the bremsstrahlung generated by the beta spectrum was not sufficient to trigger any additional photoneutrons. Both energetic and less energetic capture gamma-rays are observed when photoneutrons interact with nuclei of the two materials. Depending on the strength of the 16N source term, the secondary radiation could affect the effectiveness of the shield and need to be considered during design.

  2. Delin and Delog codes for graphic representation of gamma ray spectra

    International Nuclear Information System (INIS)

    Two FORTRAN IV Codes have been developed for graphic representation of the gamma-ray spectra obtained with GeLi detectors and multichannel analyzers. The graphic plotting is carried out with the H.P. Graphic Plotter Mod HP-7221 A, using the graphic package software GRAPHICS-1000 from Hewlett-Packard. The codes have a great versatility and the representation of gamma spectra can be done in a lineal, semilog, or log-log scale, as desired. The gamma ray spectra data are fed into the computer through magnetic tape or perforated paper tape. The different output options and complementary data are given in a conversational way through a terminal with TV display. Among the options that can be selected by the user are the following: 1) smoothing the spectra; 2) drawing the spectra point by point or continuous; 3) output drawing in 1, 2 or 4 sheets with automatic division of the energy scale; 4) overlapping of selected spectra regions in γ-scale ampliation with automatic printout of the region limits and ampliation factor; 5) printing spectra data and identifications of selected photopeaks. The codes can be employed with any computer using printing devices, HP-GRAPHICS 1000 software compatible, but are easily modified for another printing software since their modular structure with FORTRAN IV written subroutines. (author)

  3. DELIN and DELOG codes for graphic representation of gamma ray spectra

    International Nuclear Information System (INIS)

    Two Fortran IV Codes has been developed for graphic representation of the gamma-ray spectra obtained with Ge Li detectors and multichannel analyzers. The grafic plotting es carried out with the H.P. Graphic Plotter Mod HP-7221 A, using the graphic package software GRAPHICS-1000 from Hewlett-Packard. The codes have a great versatility and the representation of gamma spectra can ba done in a lineal, semi log, or log-log scale, as desired. The gamma ray spectra data are feed into the computer through magnetic tape or perfored paper tape. The different out-put options and complementary data are given in a conversational way through a terminal with T.V. displays. Among the options that can be selected by the user are the following: - smoothing the spectra - drawing the spectra point by point or continuous - out-put drawing an 1, 2, or 4 sheet with automatic division of the energy scale. - overlapping of selected spectra regions in Y scale ampliation with automatic print-out of the region limits and ampliation factor. - Printing spectra data and identifications of selected photo peaks. The codes can be employed with any computer using printing devices, HP-Graphics 1000 software compatible, but are easily modified for another printing software since their modular structure with Fortran IV written

  4. GPU-based prompt gamma ray imaging from boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Do-Kun; Jung, Joo-Young; Suk Suh, Tae, E-mail: suhsanta@catholic.ac.kr [Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul 505 137-701 (Korea, Republic of); Jo Hong, Key [Molecular Imaging Program at Stanford (MIPS), Department of Radiology, Stanford University, 300 Pasteur Drive, Stanford, California 94305 (United States); Sil Lee, Keum [Department of Radiation Oncology, Stanford University School of Medicine, 875 Blake Wilbur Drive, Stanford, California 94305-5847 (United States)

    2015-01-15

    Purpose: The purpose of this research is to perform the fast reconstruction of a prompt gamma ray image using a graphics processing unit (GPU) computation from boron neutron capture therapy (BNCT) simulations. Methods: To evaluate the accuracy of the reconstructed image, a phantom including four boron uptake regions (BURs) was used in the simulation. After the Monte Carlo simulation of the BNCT, the modified ordered subset expectation maximization reconstruction algorithm using the GPU computation was used to reconstruct the images with fewer projections. The computation times for image reconstruction were compared between the GPU and the central processing unit (CPU). Also, the accuracy of the reconstructed image was evaluated by a receiver operating characteristic (ROC) curve analysis. Results: The image reconstruction time using the GPU was 196 times faster than the conventional reconstruction time using the CPU. For the four BURs, the area under curve values from the ROC curve were 0.6726 (A-region), 0.6890 (B-region), 0.7384 (C-region), and 0.8009 (D-region). Conclusions: The tomographic image using the prompt gamma ray event from the BNCT simulation was acquired using the GPU computation in order to perform a fast reconstruction during treatment. The authors verified the feasibility of the prompt gamma ray image reconstruction using the GPU computation for BNCT simulations.

  5. GPU-based prompt gamma ray imaging from boron neutron capture therapy

    International Nuclear Information System (INIS)

    Purpose: The purpose of this research is to perform the fast reconstruction of a prompt gamma ray image using a graphics processing unit (GPU) computation from boron neutron capture therapy (BNCT) simulations. Methods: To evaluate the accuracy of the reconstructed image, a phantom including four boron uptake regions (BURs) was used in the simulation. After the Monte Carlo simulation of the BNCT, the modified ordered subset expectation maximization reconstruction algorithm using the GPU computation was used to reconstruct the images with fewer projections. The computation times for image reconstruction were compared between the GPU and the central processing unit (CPU). Also, the accuracy of the reconstructed image was evaluated by a receiver operating characteristic (ROC) curve analysis. Results: The image reconstruction time using the GPU was 196 times faster than the conventional reconstruction time using the CPU. For the four BURs, the area under curve values from the ROC curve were 0.6726 (A-region), 0.6890 (B-region), 0.7384 (C-region), and 0.8009 (D-region). Conclusions: The tomographic image using the prompt gamma ray event from the BNCT simulation was acquired using the GPU computation in order to perform a fast reconstruction during treatment. The authors verified the feasibility of the prompt gamma ray image reconstruction using the GPU computation for BNCT simulations

  6. Which Epeak? The Characteristic Energy of Gamma-ray Burst Spectra

    Science.gov (United States)

    Preece, Robert; Goldstein, Adam; Bhat, Narayana; Stanbro, Matthew; Hakkila, Jon; Blalock, Dylan

    2016-04-01

    A characteristic energy of individual gamma-ray burst (GRB) spectra can in most cases be determined from the peak energy of the energy density spectra (ν {{ F }}ν ), called “{E}{{peak}}.” Distributions of {E}{{peak}} have been compiled for time-resolved spectra from bright GRBs, as well as time-averaged spectra and peak flux spectra for nearly every burst observed by the Compton Gamma Ray Observatory Burst And Transient Source Experiment and the Fermi Gamma-ray Burst Monitor (GBM). Even when determined by an instrument with a broad energy band, such as GBM (8 keV to 40 MeV), the distributions themselves peak at around 240 keV in the observer’s frame, with a spread of roughly a decade in energy. {E}{{peak}} can have considerable evolution (sometimes greater than one decade) within any given burst, as amply demonstrated by single pulses in GRB 110721A and GRB 130427A. Meanwhile, several luminosity or energy relations have been proposed to correlate with either the time-integrated or peak flux {E}{{peak}}. Thus, when discussing correlations with {E}{{peak}}, the question arises, “Which {E}{{peak}}?” A single burst may be characterized by any of a number of values for {E}{{peak}} that are associated with it. Using a single-pulse simulation model with spectral evolution as a proxy for the type of spectral evolution observed in many bursts, we investigate how the time-averaged {E}{{peak}} emerges from the spectral evolution within a single pulse, how this average naturally correlates with the peak flux derived {E}{{peak}} in a burst, and how the distribution in {E}{{peak}} values from many bursts derives its surprisingly narrow width.

  7. A study of boron determination in high purity aluminium by capture gamma-ray measurement

    International Nuclear Information System (INIS)

    The boron content in reactor grade aluminium has been determined by means of a capture gamma-ray counting method. The experimental detection limit is found to be 5.7 ppm with 10% uncertainty. In order to improve the sensitivity, the boron is preconcentrated from aluminium by cation exchange resin system. The accuracies of both methods, i.e., one by the direct measurement and the other by the measurement after preconcentration, are checked by an additive method. The results show good agreements with less than 5% deviation. (author)

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

    International Nuclear Information System (INIS)

    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

  9. Tomographic image of prompt gamma ray from boron neutron capture therapy: A Monte Carlo simulation study

    International Nuclear Information System (INIS)

    The resulting neutron captures in 10B are used for radiation therapy. The occurrence point of the characteristic 478 keV prompt gamma rays agrees with the neutron capture point. If these prompt gamma rays are detected by external instruments such as a gamma camera or single photon emission computed tomography (SPECT), the therapy region can be monitored during the treatment using images. A feasibility study and analysis of a reconstructed image using many projections (128) were conducted. The optimization of the detection system and a detailed neutron generator simulation were beyond the scope of this study. The possibility of extracting a 3D BNCT-SPECT image was confirmed using the Monte Carlo simulation and OSEM algorithm. The quality of the prompt gamma ray SPECT image obtained from BNCT was evaluated quantitatively using three different boron uptake regions and was shown to depend on the location and size relations. The prospects for obtaining an actual BNCT-SPECT image were also estimated from the quality of the simulated image and the simulation conditions. When multi tumor regions should be treated using the BNCT method, a reasonable model to determine how many useful images can be obtained from SPECT can be provided to the BNCT facilities based on the preceding imaging research. However, because the scope of this research was limited to checking the feasibility of 3D BNCT-SPECT image reconstruction using multiple projections, along with an evaluation of the image, some simulation conditions were taken from previous studies. In the future, a simulation will be conducted that includes optimized conditions for an actual BNCT facility, along with an imaging process for motion correction in BNCT. Although an excessively long simulation time was required to obtain enough events for image reconstruction, the feasibility of acquiring a 3D BNCT-SPECT image using multiple projections was confirmed using a Monte Carlo simulation, and a quantitative image analysis was

  10. Self-absorption of neutron capture gamma-rays in gold samples

    International Nuclear Information System (INIS)

    The self absorption of neutron capture gamma rays in gold samples has been determined experimentally for two standard setups used in measurements of neutron capture cross sections. One makes use of an artificially collimated neutron beam and two C6D6 detectors, the other of kinematically collimated neutrons and three Moxon-Rae detectors. Correction factors for an actual measurement of a neutron capture cross section using a gold standard of 1 mm thickness up to 12% were found for the first setup while they are only 4% for the second setup. The present data allow to determine the correction in an actual measurement with an accuracy of 0.5-1%. (orig.)

  11. Capture cross section and gamma-ray spectrum calculations for medium-weight nuclei. [Double-peak, energy-dependent Breit-Wigner model

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, M.A.; Gardner, D.G.

    1979-11-14

    A double-peak, energy-dependent Breit-Wigner model of the E1 gamma-ray strength function was applied to nuclei from As to Rh, to predict their neutron capture cross sections and capture gamma-ray spectra. A consistent set of model parameters was obtained in this mass region to describe the step in the low-energy tail of the E1 strength function. This step allows agreement with photonuclear data at high energies, the correct GAMMA/sub gamma/ to be obtained for agreement with neutron capture cross-section data, and the calculation of the observed hardness in the capture gamma-ray spectra. For nuclei at or near the closed, N = 50 shell, however, the double-peak assumption breaks down. In these cases, good results are still obtained if the same set of model parameters is applied, except that the E1 strength function is formulated in terms of the first, narrower peak. 8 figures.

  12. Photoneutron cross sections measurements in 9Be, 13C e 17O with thermal neutron capture gamma-rays

    International Nuclear Information System (INIS)

    Photoneutron cross sections measurements of 9Be, 13C and 17O have been obtained in the energy interval between 1,6 and 10,8 MeV, using neutron capture gamma-rays with high resolution in energy (3 a 21 eV), produced by 21 target materials, placed inside a tangential beam port, near the core of the IPEN/CNEN-SP IEA-R1 (5 MW) research reactor. The samples have been irradiated inside a 4π geometry neutron detector system 'Long Counter', 520,5 cm away from the capture target. The capture gamma-ray flux was determined by means of the analysis of the gamma spectrum obtained by using a Ge(Li) solid-state detector (EG and G ORTEC, 25 cm3, 5%), previously calibrated with capture gamma-rays from a standard target of Nitrogen (Melamine). The neutron photoproduction cross section has been measured for each target capture gamma-ray spectrum (compound cross section). A inversion matrix methodology to solve inversion problems for unfolding the set of experimental compound cross sections, was used in order to obtain the cross sections at specific excitation energy values (principal gamma line energies of the capture targets). The cross sections obtained at the energy values of the principal gamma lines were compared with experimental data reported by other authors, with have employed different gamma-ray sources. A good agreement was observed among the experimental data in this work with reported in the literature. (author)

  13. Gamma-ray spectra of hexane (C6H14) in positron–electron annihilation process

    International Nuclear Information System (INIS)

    Theoretical gamma-ray spectra of molecule hexane have been calculated and compared with the experimental results in both gas (Iwata et al., 1997a) and liquid (Kerr et al., 1965) phases. The present study reveals that in gas phase not all valence electrons of hexane contribute the same degree in the electron–positron annihilation of hexane. The electrons which dominate the positron–electron annihilation of molecules are called positrophilic electrons. The positrophilic electrons are predominately found to involve the electrons on the lowest occupied valence orbital (LOVO) of a free molecule in gas phase. When hexane is confined in liquid phase, however, the intermolecular interactions ultimately eliminate the free molecular orientation and selectivity for the positrophilic electrons in the gas phase. As a result, the gamma-ray spectra of hexane become an “averaged” contribution from all valence electrons, which is again in agreement with liquid phase measurement. The roles of valence electrons in annihilation process for gas and liquid phases of hexane have been recognized for the first time in the present study. - Highlights: • The role of the positrophilic electrons in annihilation process of hexane has been evidenced by excellent agreement with gas phase experiment. • The study suggested that the electrons in the inner most valence orbital—the lowest occupied valence orbital (LOVO)—dominate the positron–electron annihilation of gamma-ray spectra in molecules. • The study suggests that intermolecular interactions of liquid hexane may contribute to eliminate certain individuality of electrons in free molecules to averaged electron behaviors in liquid

  14. Deconvolution of gamma-ray spectra obtained with NAI(Tl) detector in a water tank.

    Science.gov (United States)

    Rahman, M Sohelur; Cho, Gyuseong; Kang, Bo-Sun

    2009-07-01

    Maximum-likelihood fitting by the expectation maximization deconvolution method is presented to analyse gamma-ray spectra recorded using an NaI(Tl) detector for a water monitoring system. The applicability of the method was tested by deconvolving measured spectra taken using an industry standard 3'' x 3'' cylindrical NaI(Tl) detector in a model water tank with several calibration sources. The results show significant removal of the Compton continuum counts and efficient transfer of the counts into the corresponding photo-peaks. The peak-to-total count ratio and the number of counts in the photo-peaks in the deconvolved spectra increased approximately 4.67 and 5.29 times, respectively, compared with those of measured spectra taken using an NaI(Tl) scintillation detector in the case of (137)Cs. PMID:19502359

  15. Gamma ray energy loss spectra simulation in NaI detectors with the Monte Carlo method

    International Nuclear Information System (INIS)

    With the aim of studying and applying the Monte Carlo method, a computer code was developed to calculate the pulse height spectra and detector efficiencies for gamma rays incident on NaI (Tl) crystals. The basic detector processes in NaI (Tl) detectors are given together with an outline of Monte Carlo methods and a general review of relevant published works. A detailed description of the application of Monte Carlo methods to ν-ray detection in NaI (Tl) detectors is given. Comparisons are made with published, calculated and experimental, data. (Author)

  16. Doppler-broadening of gamma rays following muon capture search for scalar coupling

    CERN Document Server

    Shitov, Y; Briançon, C; Brudanin, V; Deutsch, J; Filipova, T; Petitjean, C; Prieels, R; Siiskonen, T; Suhonen, J; Vylov, T D; Wiaux, V; Yutlandov, I A; Zaparov, S

    2002-01-01

    A precision measurement of the 277 keV gamma ray produced by capturing muons in gaseous oxygen was performed using high-resolution HPGe detectors. The Doppler-broadened shape of this line is sensitive to the possible admixture into muon capture of genuine scalar interaction. This experiment complements, in the muon sector, in principle, similar ones undertaken recently in nuclear beta decay. Using a procedure discussed in earlier papers, a fit to the experimental line-shape allowed us to obtain for the recoil-gamma correlation coefficient the value of a sup 1 sub 2 =0.096+-0.041 (95% CL). The available evaluations of the contributing nuclear matrix elements, performed in the impulse approximation in the absence of scalar interaction, produce correlation coefficients in disagreement with our result. These evaluations are independent of the induced pseudoscalar coupling and so of the validity of the PCAC hypothesis, but their reliability and model dependence remain to be investigated.

  17. Apparatus for parity-violation study via capture gamma-ray measurements

    CERN Document Server

    Seestrom, S J; Bowman, J D; Crawford, B C; Haseyama, T; Masaike, A; Matsuda, A; Penttilae, S I; Roberson, R N; Sharapov, E I; Stephenson, S L

    1999-01-01

    The Time Reversal and Parity at Low Energy (TRIPLE) Collaboration uses a short-pulsed longitudinally polarized epithermal neutron beam at the Los Alamos Neutron Science Center to study spatial parity violation (PV) in the compound nucleus. The typical PV experiment measures the longitudinal cross-section asymmetry by the neutron transmission method through thick samples. Neutron capture gamma-ray measurement provides an alternative method for the study of PV, which enables the use of smaller amounts of isotopically pure target material. In 1995 TRIPLE commissioned a new neutron-capture detector consisting of 24 pure CsI scintillators arranged in a cylindrical geometry around the neutron beam. The characteristics and the performance of the detector and spin transport are described.

  18. Monte Carlo calculations of neutron and gamma-ray energy spectra for fusion reactor shield design: comparison with experiment

    International Nuclear Information System (INIS)

    Neutron and gamma-ray energy spectra resulting from the interactions of approx. 14 MeV neutrons in laminated slabs of stainless steel type-304 and borated polyethylene have been calculated using the Monte Carlo code MCNP. The calculated spectra are compared with measured data as a function of slab thickness and material composition and as a function of detector location behind the slabs. Comparisons of the differential energy spectra are made for neutrons with energies above 850 keV and for gamma rays with energies above 750 keV. The measured neutron spectra and those calculated using Monte Carlo methods agree witin 5% to 50% depending on the slab thickness and composition and neutron energy. The agreement between the measured and calculated gamma-ray energy spectra are also within this range. The MCNP data are also in favorable agreement with attenuated data calculated previously by discrete ordinates transport methods and the Monte Carlo code SAM-CE

  19. Gamma-ray spectra of methane in the positron-electron annihilation process

    CERN Document Server

    Ma, Xiaoguang

    2012-01-01

    Bound electron contribution to the Doppler-shift of gamma-ray spectra in the positron-electron annihilation process of molecular methane has been studied in gas phase. Two accurate ab initio quantum mechanical schemes, i.e. the delocalized molecular orbital (MO) and the localized natural bond orbital (NBO) schemes, are applied to study the multi-centred methane molecule. The present ab initio calculations of methane indicate that the C-H bonds are polarized with the partial negative charge of -0.36 a.u. on the carbon atom and the partial positive charge of +0.09 a.u. on each of the hydrogen atoms. The positively charged hydrogen atoms produce repulsive Coulomb potentials to a positron. Both the MO and NBO schemes further reveal that the 2a1 electrons of methane, that is, the 2a1 electron component of the C-H bonds rather than the whole C-H bonds of methane, predominates the positron-electron annihilation gamma-ray spectra of the molecule. Electrons of a molecule which are dominant the positron-electron annihi...

  20. The holistic analysis of gamma-ray spectra in instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    The subject is the computerized analysis of the gamma-ray spectra in INAA. This analysis can be separated in three parts: The conversion of the spectra to information on γ-ray energies and their relative intensities (spectrum reduction), the determination of the relation between the intensity of a γ-ray and the amount of the corresponding element present in the sample (standardization) and the attribution of the γ-ray energies to the elements, including the subsequent computation of the amounts of the elements (interpretation). A γ-ray spectrum can be considered to be the linear sum of the γ-ray spectra of the individual radionuclides present in the sample. Knowing the relative activities of the different radionuclides that may be produced by activation of a single element, a γ-ray spectrum in INAA can also be considered to be the linear sum of the spectra of the elements. This principle has hitherto not been used in INAA to analyze the spectra by linear least squares methods, using all γ-ray energies observed in the spectrum. The implementation of this 'holistic' approach required that attention be paid to both spectrum reduction, standardization and interpretation. The thesis describes the methods developed for the holistic analysis of γ-ray spectra in INAA, and present results of experimental comparisons between the holistic and other approaches. (orig./HP)

  1. Spectra characteristics of airborne gamma-ray spectrometer based on data fusion

    International Nuclear Information System (INIS)

    Background: Airborne gamma-ray spectrometry is made up of multiple NaI (Tl) detector, but the detectors have the different level of noise. Purpose: Aimed at reducing the affection of noise, a weighted least square fusion estimation algorithm is presented to extract the Spectra Characteristics. Methods: The method doesn't need any prior knowledge on the detector, but carries on the variance estimated on-line these data and timely adjust weights of various fusion sensors in order to make the mean-square error of fusion results least all the time. Results: It is used to process the date come from the standard model, the results show that measurement error range of 40K decreased from 17% to 12%. Conclusions: The result has shown that the method can dramatically decrease the error and improve the accuracy. (authors)

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

    CERN Document Server

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

    2014-01-01

    We investigate the scaling relation between the observed amount of absorption in the X-ray spectra of Gamma Ray Burst (GRB) 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 10^5-10^6 counts in the 0.3-10 keV band are needed to constrain the redshift with 10% 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.

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

    Science.gov (United States)

    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.

  4. Fifteenth international symposium on capture gamma-ray spectroscopy and related topics. CGS15. Book of abstracts

    International Nuclear Information System (INIS)

    The proceedings of the fifteenth international symposium on capture gamma-ray spectroscopy and related topics - CGS15 - includes abstract concerning the following topics: nuclear structure, nuclear reactions, nuclear astrophysics, techniques/reactions, nuclear data/reactions, statistical properties, fundamental properties, nuclear reactions/data.

  5. APPLE-2: an improved version of APPLE code for plotting neutron and gamma ray spectra and reaction rates

    International Nuclear Information System (INIS)

    A computer code APPLE-2 which plots the spatial distribution of energy spectra of multi-group neutron and/or gamma ray fluxes, and reaction rates has been developed. This code is an improved version of the previously developed APPLE code and has the following features: (1) It plots energy spectra of neutron and/or gamma ray fluxes calculated by ANISN, DOT and MORSE. (2) It calculates and plots the spatial distribution of neutron and gamma ray fluxes and various types of reaction rates such as nuclear heating rates, operational dose rates, displacement damage rates. (3) Input data specification is greatly simplified by the use of standard, response libraries and by close coupling with radiation transport calculation codes. (4) Plotting outputs are given in camera ready form. (author)

  6. 1012 - 1015 eV interaction deduced from energy spectra of gamma-ray and hadrons at airplane altitude

    International Nuclear Information System (INIS)

    The present paper deals with the latest results of the spectral measurements of high energy cosmic ray performed on an airplane with an emulsion chamber. The hadronic component together with the gamma-ray component were observed in the region of gamma energy not smaller than 30 GeV and gamma energy sum not larger than 40 TeV. It was observed that the integral spectra of hadronic showers showed less steep power than those obtained at mountain stations. On the other hand, the integral spectra of gamma-ray in the energy region from 40 GeV to 40 TeV showed steeper power than those of hadronic component. The zenith angle distributions of hadrons and gamma-ray were inspected, and it was confirmed that the observed distributions were well reproduced by the theoretical curves with the appropriate attenuation length. (Yoshimori, M.)

  7. Strong MgII systems in quasar and gamma-ray burst spectra

    CERN Document Server

    Porciani, C; Lilly, S J; Porciani, Cristiano; Viel, Matteo; Lilly, Simon J.

    2007-01-01

    The incidence of strong MgII systems in gamma-ray burst (GRB) spectra is a few times higher than in quasar (QSO) spectra. We investigate several possible explanations for this effect, including: dust obscuration bias, clustering of the absorbers, different beam sizes of the sources, multiband magnification bias of GRBs, association of the absorbers with the GRB event or the circumburst environment. We find that: i) the incidence rate of MgII systems in QSO spectra could be underestimated by a factor 1.3-2 due to dust obscuration; ii) the equivalent-width distribution of the MgII absorbers along GRBs is consistent with that observed along QSOs thus suggesting that the absorbers are more extended than the beam sizes of the sources; iii) on average, GRB afterglows showing more than one MgII system are a factor of 1.7 brighter than the others, suggesting a lensing origin of the observed discrepancy; iv) gravitational lensing (in different forms, from galaxy lensing to microlensing) can bias high the counts of MgI...

  8. ACCURACY OF MEASUREMENT OF NATURAL GAMMA RAY SPECTRA BY HD—8004 NaI(T1) GAMMA SPECTROMETER

    Institute of Scientific and Technical Information of China (English)

    朱国钦; 郑仁淑

    1995-01-01

    The measurement principle and analysis method of natural gammaray spectra using NaI(T1) scintillation spectrometer are briefly described first,then block diagrams of the HD-8004 NaI(T1) gamma-ray spectrometer,Finally,sample measurements are listed and discussed.The results are quite promising.Based on the analysis of these measurements,measures to improve the accuracy of spectrum measurement are proposed.It is well hoped that these measures can contribute to the development and application of gamma-ray spectrum measurement.

  9. A new technique for the determination of impurities in uranium-and thorium compounds, by the analysis of capture gamma rays

    International Nuclear Information System (INIS)

    A new technique is presented for the determination of impurities in uranium-and thorium compounds, based on the analysis of capture gamma rays emitted by the impurities and by the matrix element, without previous matrix isolation. The experimental system utilized is described and calibration curves are given. Several measurements are made for uranium oxide and thorium oxide samples to which known impurities were added in a controlled way: Through the analysis of spectra, the possibility is shown of utilizing the new technique for the determination of impurities found in uranium-and thorium compounds used as nuclear fuel materials. (Author)

  10. Study of p-wave gamma-ray strength functions

    International Nuclear Information System (INIS)

    Gamma-ray strength functions are important for description of the gamma emission channel in nuclear reactions. The impact of different models- Weisskopf's single particle model, Brink's standard Lorentzian and Kopecky's generalized Lorentzian for gamma ray strength functions on the calculation of neutron capture related experimental quantities such as total radiation widths Γγ cross sections and gamma-ray spectra has been studied

  11. Investigation of possibilities of application of neutron capture gamma-ray spectrometry for cement manufactures control

    International Nuclear Information System (INIS)

    Full text: Creation of system of Automatic Management of Technological Processes in cement industry still remains an actual problem, solution of which leads to increase in volume and improvement in the quality of the ready product, and also gives opportunity to effective use of electro energy and raw material resources. In preparation of cement acute stands the question of realization of operative control of the content of main technologically important elements: like Ca, Mg, Fe, Si and Al in the initial raw material and different content must be determined on the technological stream. Among existing analytical methods, nuclear physics method based on prompt gamma radiation of neutron capture spectrometry is one of the better possibilities/1,2/. In this work, results of investigation of possibilities of express determination of technological important elements: Ca, Mg, Fe, Si and Al in the initial raw material by the method of neutron capture prompt gamma - ray spectrometry. Laboratory model of low power radionuclide (252Cf) - source of neutrons with the yield of 5x106 neutron/sec. Measuring equipment consists of semiconductor Ge (Li) - detector with volume of sensitive crystal, 40 sm3 and energy resolution of 4 keV on the line of 60Co with the energy of 1333 keV and multichannel pulse analyzers AI-1024-95. Possibility of express determination of concentration of technologically important elements in the initial raw material of Kyzylkum by means of using neutron capture gamma radiation spectrometry with parameters meeting production requirements of cement industry of Uzbekistan

  12. Neutron capture prompt gamma-ray activation analysis of meat homogenates

    International Nuclear Information System (INIS)

    Thermal neutron capture prompt gamma-ray activation analysis (PGAA) was used to determine mass fractions of H, B, C, N, Na, Cl, K, and S in 2 meat homogenates. Twelve units of candidate Standard Reference Material (SRM) 1546 Meat Homogenate produced by the National Institute of Standards and Technology (NIST) were analyzed to provide NIST with certification data. This SRM is a realistic processed food matrix, ideal for food analysis programs such as the Food and Drug Administration's Total Diet Study. Another meat homogenate, Certified Reference Material LGC 7002 Pork/Chicken (along with NIST SRMs 1549 Non-fat Milk Powder and 1571 Orchard Leaves) was analyzed for quality control. Candidate SRM 1546 unit-to-unit heterogeneity was <2% for H, Na, Cl, and K, and 3.5% for N and within-unit heterogeneity was <2% for H, N, Cl, and K, and 2.9% for Na, similar to LGC 7002 homogeneity results. Control material mass fractions agreed well with certificate and consensus values. Protein mass fractions, calculated from N results, were 15.2% and 11.9% for candidate SRM 1546 and LGC 7002, respectively. Protein content calculated for SRM 1549 (36.0%) agreed well with known values for dried non-fat milk powder. (author)

  13. Exploitation of gamma ray spectra by non parametric probabilistic methods and without operator's intervention

    International Nuclear Information System (INIS)

    Gamma ray spectrometry is a passive non-destructive assay most commonly used for the quantification of radionuclides in nuclear waste. The thesis aims to improve the exploitation of the spectra (which takes place after the step of acquiring the spectrum). The exploitation of the spectra was done in two parts (extract energy and net areas of the peaks contained in the spectrum and determine the efficiency of the assay), the work is divided into two parts. First, we set up a validation process that quantifies the uncertainties caused by the extraction of energy and net areas and that is applicable to any deconvolution software. With this process, we studied the performance of the deconvolution performed by the software SINBAD. The work has allowed to have an automated tool for extracting energy and net areas of full absorption peaks whose uncertainties are quantified. Finally, the second part of the thesis has allowed to develop an automated method for calculating the efficiency of the assay, that is applicable to any objects being measured. The feasibility of the method to simple cases was proved by the thesis. The extrapolation to more complex cases will be subject of further studies. (author)

  14. Upper Limits on the Extragalactic Background Light from the Gamma-Ray Spectra of Blazars

    CERN Document Server

    Schroedter, M

    2005-01-01

    The direct measurement of the extragalactic background light (EBL) is difficult at optical to infrared wavelengths because of the strong foreground radiation originating in the Solar System. Very high energy (VHE, E$>$100 GeV) gamma rays interact with EBL photons of these wavelengths through pair production. In this work, the available VHE spectra from six blazars are used to place upper limits on the EBL. These blazars have been detected over a range of redshifts and a steepening of the spectral index is observed with increasing source distance. This can be interpreted as absorption by the EBL. In general, knowledge of the intrinsic source spectrum is necessary to determine the density of the intervening EBL. Motivated by the observed spectral steepening with redshift, upper limits on the EBL are derived by assuming that the intrinsic spectra of the six blazars are $\\propto E^{-1.8}$. Upper limits are then placed on the EBL flux at discrete energies without assuming a specific spectral shape for the EBL. Thi...

  15. Secondary Standardizations with Digital Computer Techniques to Normalize Multiple Gamma-Ray Spectra for Direct Efficiency Determinations

    International Nuclear Information System (INIS)

    A new standardization technique for gamma-ray emitting nuclides has been developed. The method is based on the use of gamma-ray spectral data in digital format from absolutely standardized samples of radionuclides. A system for collecting a library of gamma-ray spectra from such absolutely standardized samples was perfected in conjunction with a least-squares gamma-spectral resolution programme. A pooling programme was devised to combine six gamma-ray spectra from multiple sample mounts from the single master solution. The programme was written in FORTRAN-FAP for the IBM 1090 computer; it corrects for background, decay, and gain shift, and then converts the spectral data from counts/second/channel to counts/disintegration/channel using the disintegration rate of the standard sample as an input parameter. The spectral data are treated statistically with an analysis of variance to get a high degree of accuracy in the library of spectra. Since the gamma-ray spectra from the pooling programme consist of channel-by-channel data in units of counts per disintegration, these response curves comprise a channel-by-channel measure of the efficiency of detection for the given gamma-ray spectrometer system. By combining these individual channel efficiencies for some region of the gamma-ray spectrum that is not affected greatly by external processes (e.g. a prominent photopeak), it is possible to assign directly an efficiency factor for the detection of each of the library nuclides. An assay system has been developed with the digital data in the form of punched paper tape. The paper-tape standard may be read into the memory of a multichannel analyser where a direct comparison may be made with the unknown sample. The system has been found to be independent of detector resolution as long as the region chosen for the comparison of standard and unknown encompasses an entire photopeak. A library of standard spectra in the described format has been collected for 42 radionuclides using

  16. Calculation of the delayed fission gamma-ray spectra from U-235, -238, Pu-239, -240 and Pu-241, tabular data

    International Nuclear Information System (INIS)

    The delayed fission-gamma-ray, which is emitted aggregatively from the unstable nuclides produced by fission, must be taken into account properly in calculation of the gamma-ray source in nuclear reactors. Despite its importance, the delayed gamma-ray data is not well organized nor prepared even in major nuclear data libraries such as JENDL and ENDF/B. Here we prepare the delayed gamma-ray spectra for five major fissioning nuclides. In calculating these spectra, theoretical estimation of the unknown spectra was carried out widely for a lot of no-data nuclides, which had been a major source of ambiguity in calculating the delayed gamma-ray spectra. (author)

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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 MATLABTM 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.

  19. Calculation of neutron and gamma-ray emission spectra produced by p + 27Al reactions

    International Nuclear Information System (INIS)

    Preliminary calculations of neutron and gamma-ray spectra induced by proton reactions on aluminum have been made to provide data required for shielding design for a proposed proton linear accelerator. The nuclear models used in this study were the preequilibrium and Hauser-Feshbach models as embodied in the GNASH program. This nuclear model code has been used in the past to successfully investigate higher energy (E less than or equal to 50 MeV) neutron and proton interactions with nuclei in the structural materials region. Because this study was of an exploratory nature, we did not attempt to optimize input parameters but instead relied upon global sets, especially for optical parameters. In particular, for neutrons we chose the Wilmore-Hodgson parameter set after confirmation of its suitability through comparison to n+27Al total cross-section data between 0.5 and 60 MeV. Agreement with the data on the level of 5-10% occurred. Comparisons were also made to measured nonelastic data for incident energies between 10 and 60 MeV. Again, there was generally good agreement although there was some tendency to overpredict such data for incident neutron energies below several MeV. For protons we found the Becchetti-Greenlees parameter set reproduced nonelastic data recently measured by McGill et al

  20. Constraining Lorentz invariance violation from the continuous spectra of short gamma-ray bursts

    Science.gov (United States)

    Chang, Zhe; Li, Xin; Lin, Hai-Nan; Sang, Yu; Wang, Ping; Wang, Sai

    2016-04-01

    In some quantum gravity theories, a foamy structure of space-time may lead to Lorentz invariance violation (LIV). As the most energetic explosions in the Universe, gamma-ray bursts (GRBs) provide an effect way to probe quantum gravity effects. In this paper, we use the continuous spectra of 20 short GRBs detected by the Swift satellite to give a conservative lower limit of quantum gravity energy scale M QG. Due to the LIV effect, photons with different energy have different velocities. This will lead to the delayed arrival of high energy photons relative to low energy ones. Based on the fact that the LIV-induced time delay cannot be longer than the duration of a GRB, we present the most conservative estimate of the quantum gravity energy scales from 20 short GRBs. The strictest constraint, M QG > 5.05 × 1014 GeV in the linearly corrected case, is from GRB 140622A. Our constraint on M QG, although not as tight as previous results, is the safest and most reliable so far. Supported by National Natural Science Foundation of China (11375203, 11305181, 11322545, 11335012) and Knowledge Innovation Program of The Chinese Academy of Sciences

  1. Modification of the gamma-ray spectra by internal absorption in OVV blazars: The example cases of 3C 273 and 3C 279

    OpenAIRE

    Sitarek, J.; Bednarek, W.

    2008-01-01

    Recent observations with the low threshold Cherenkov telescopes proved that sub-TeV gamma-rays are able to arrive from active galaxies at relatively large distances in spite of expected severe absorption in the extragalactic background light (EBL). We calculate the gamma-ray spectra at TeV energies from two example OVV quasars, 3C 273 and 3C 279, assuming that gamma-rays are injected in the inner parts of the jets launched by the accretion disks. It is assumed that gamma-rays in the broad ene...

  2. Experimental determination of nuclear reaction rates (n,γ) by the gamma-rays capture spectrometry technique

    International Nuclear Information System (INIS)

    The technique of the gamma-rays capture spectrometry was used in the experimental determination of nuclear reaction rates of the type (n,γ). This technique consists in the incidence of a thermal neutrons collimated beam upon a sample, detecting the capture spectrum of gamma rays emitted at a solid fixed angle. In the determination of the efficiency curve intrinsic to the detection electronic system the reactions 199Hg(n,γ)200Hg, 56Fe(n,γ)57Fe and 63Cu(n,γ)64Cu were used with the energy of the gamma rays capture of 5.976, 7.635 and 7.915 Mev respectively, through the irradiation of standard samples of Hg(175.3g), Fe(110.4g) and Cu(108.5g) of cylindrical geometry the two former and parallelepiped the latter. The problem concerning the corrections due to the thermal neutrons flux depression, the gammas auto-attenuation, and the geometric factor due to the cylindrical and parallelepiped geometry are involved in the data process. The experimental determination of the reaction 35Cl(n,γ)36Cl rate was made through the observation of the gamma caputre of 6.111 Mev when a sample of CaCl2 of cylindrical geometry was irradiated. This rate can be favorably compared with the reaction rate determined theoretically. (author)

  3. Calculation of the decision thresholds for radionuclides identified in gamma-ray spectra by post-processing peak analysis results

    Science.gov (United States)

    Korun, Matjaž; Vodenik, Branko; Zorko, Benjamin

    2016-03-01

    A method for calculating the decision thresholds for gamma-ray emitters, identified in gamma-ray spectrometric analyses, is described. The method is suitable for application in computerized spectra-analyzing procedures. In the calculation, the number of counts and the uncertainty in the number of counts for the peaks associated with the emitter are used. The method makes possible to calculate decision thresholds from peaks on a curved background and overlapping peaks. The uncertainty in the number of counts used in the calculation was computed using Canberra's Standard Peak Search Program (Canberra, 1986, Peak Search Algorithm Manual 07-0064). For isolated peaks, the decision threshold exceeds the value calculated from the channel contents in an energy region that is 2.5 FWHM wide, covering the background in the immediate vicinity of the peak. The decision thresholds vary by approximately 20% over a dynamic range of peak areas of about 1000. In the case of overlapping peaks, the decision threshold increases considerably. For multi-gamma-ray emitters, a common decision threshold is calculated from the decision thresholds obtained from individual gamma-ray emissions, being smaller than the smallest of the individual decision thresholds.

  4. Calculation of neutron and gamma-ray energy spectra for fusion reactor shield design: comparison with Experiment II

    International Nuclear Information System (INIS)

    Measured and calculated neutron and gamma-ray energy spectra resulting from the transport of approx. 14 MeV neutrons through a 0.30-m-thick lithium hydride slab and through a 0.05-m-thick lead slab followed by 0.30 m of lithium hydride are compared. Also reported are comparisons of the measured and calculated neutron energy spectra behind an 0.80-m-thick assembly comprised of stainless steel type 304 and borated polyethylene. The spatial dependence of the gamma-ray energy deposition rate measured using thermoluminescent detectors is compared with calculated data. The calculated data obtained using two-dimensional radiation transport methods and ENDF/B-IV cross section data are in good agreement for all of the experimental configurations

  5. Design, construction, and characterization of a facility for neutron capture gamma ray analysis of sulfur in coal using californium-252

    International Nuclear Information System (INIS)

    A study of neutron capture gamma ray analysis of sulfur in coal using californium-252 as a neutron source is reported. Both internal and external target geometries are investigated. The facility designed for and used in this study is described. The external target geometry is found to be inappropriate because of the low thermal neutron flux at the sample location, which must be outside the biological shielding. The internal target geometry is found to have a sufficient thermal neutron flux, but an excessive gamma ray background. A water filled plastic facility, rather than the paraffin filled steel one used in this study, is suggested as a means of increasing flexibility and decreasing the beackground in the internal target geometry

  6. Elemental analysis of water and soil environmental samples in Tabuk area by neutron capture gamma-ray spectroscopy techniques

    International Nuclear Information System (INIS)

    The prompt and delayed gamma-rays due to neutron capture in the nuclei of the constituent elements of three soil samples and one drinking water sample have been measured. The 252Cf and 226Ra/Be isotopic neutron sources are used for neutron irradiation. Also, the hyper pure germanium detection system is used. The soil samples were from Astra, Tadco and El-Gammaz farms, while the water sample was taken from Tabuk city. In case of prompt gamma-ray analysis, a total of 16 elements were identified and the concentration percentage values by weight were calculated for: C, Na, Mg, Al, Si, S, Cl,, Ca, Ti, Cr, Mn, Fe, Co, Zn, Sr ad Pb elements. A comparative study between the results obtained in this work and the results obtained by ICP-MS and EDX-Ray techniques for the same samples is given

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

    Science.gov (United States)

    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.

  8. Responses of C6D6 and C6F6 gamma-ray detectors and the capture in the 1.15-keV resonance of 56Fe

    International Nuclear Information System (INIS)

    We have used the electron gamma-ray transport code EGS to calculate responses of C6D6 and C6F6 gamma-ray detectors, where the geometry of the capture experiments was carefully modelled. Very good agreement was obtained with spectra from selected resonances in the capture of neutrons by 207Pb. Weighting functions based upon the calculated responses were used in measuring the capture in the 1.15-keV resonance of 56Fe relative to the capture in the Au 4.9-eV resonance. The neutron width was measured to be 64.5+-3. MeV with C6F6 detectors, and 63.0+-2.5 meV with C6D6 detectors. These valuues are in good agreement with the value of 61.7+-0.9 MeV found from transmission measurements. 16 refs., 6 figs

  9. PC/FRAM plutonium isotopic analysis of CdTe gamma-ray spectra

    CERN Document Server

    Vo, D T

    2002-01-01

    This paper reports the results of isotopics measurements of plutonium with the new CdTe gamma-ray spectrometer. These are the first wide-range plutonium gamma-ray isotopics analysis results obtained with other than germanium spectrometers. The CdTe spectrometer measured small plutonium reference samples in reasonable count times, covering the range from low to high burnup. The complete experimental hardware included the new, commercial, portable CdTe detector and two commercial portable multichannel analyzers. Version 4 of FRAM is the software that performed the isotopics analysis.

  10. PC/FRAM plutonium isotopic analysis of CdTe gamma-ray spectra

    Science.gov (United States)

    Vo, D. T.; Russo, P. A.

    2002-07-01

    This paper reports the results of isotopics measurements of plutonium with the new CdTe gamma-ray spectrometer. These are the first wide-range plutonium gamma-ray isotopics analysis results obtained with other than germanium spectrometers. The CdTe spectrometer measured small plutonium reference samples in reasonable count times, covering the range from low to high burnup. The complete experimental hardware included the new, commercial, portable CdTe detector and two commercial portable multichannel analyzers. Version 4 of FRAM is the software that performed the isotopics analysis.

  11. Detailed parametrization of neutrino and gamma-ray energy spectra from high energy proton-proton interactions

    Science.gov (United States)

    Supanitsky, A. D.

    2016-02-01

    Gamma rays and neutrinos are produced as a result of proton-proton interactions that occur in different astrophysical contexts. The detection of these two types of messengers is of great importance for the study of different physical phenomena, related to nonthermal processes, taking place in different astrophysical scenarios. Therefore, the knowledge of the energy spectrum of these two types of particles, as a function of the incident proton energy, is essential for the interpretation of the observational data. In this paper, parametrizations of the energy spectra of gamma rays and neutrinos, originated in proton-proton collisions, are presented. The energy range of the incident protons considered extends from 102 to 108 GeV . The parametrizations are based on Monte Carlo simulations of proton-proton interactions performed with the hadronic interaction models QGSJET-II-04 and EPOS-LHC, which have recently been updated with the data taken by the Large Hadron Collider.

  12. GPU-based prompt gamma ray imaging from boron neutron capture therapy

    International Nuclear Information System (INIS)

    This reaction can be applied to the therapy and diagnosis about the tumor simultaneously. After the compound labeled with the boron is accumulated at the tumor site, the alpha particle induced by the reaction between the thermal neutron and the boron induces tumor cell death. Also, the 478 keV prompt gamma ray is emitted from the same reaction point. If this single prompt photon is detected by single photon emission computed tomography (SPECT), the tomographic image of the therapy region can be monitored during the radiation treatment. However, in order to confirm the therapy region using the image during the treatment, the image needs to be provided promptly. Due to a relatively long acquisition time required to get SPECT images, both reduced number of projections and the fast image reconstruction schemes are needed to provide the images during radiation treatment. The computation time for image reconstruction using the GPU with the modified OSEM algorithm was measured and compared with the computation time using CPU. Through the results, we confirmed the feasibility of the image reconstruction for prompt gamma ray image using GPU for the BNCT. In the further study, the development of the algorithm for faster reconstruction of the prompt gamma ray image during the BNCT using the GPU computation will be conducted. Also, the analysis of the target to background level about the reconstructed image will be performed using the extracted image profile

  13. Order statistics and energy-ordered histograms: an analytical approach to continuum gamma-ray spectra

    International Nuclear Information System (INIS)

    Full text: Fusion-evaporation heavy ion collisions have enable us to explore new regions of phase space E - I, particularly high spin and excitation energy regions, where level densities are so high that modern detectors are unable to resolve individual gamma-ray transitions and consequently the resulting spectrum is continuous and undoubtedly contains a lot of new physics. In spite of that, very few experiments have been designed to extract conclusions about behavior of nuclei in continuum, thus in order to obtain a continuum spectroscopy it is necessary to apply to numerical simulations. In this sense GAMBLE a Monte Carlo based code- is a powerful tool that with some modifications allows us to test a new method to analyze the outcome of experiments focused on the properties of phase space regions in nuclear continuum: The use of Energy-Ordered Spectra (EOS) . Let's suppose that in a experiment is collected all gamma radiation emitted by a specific nucleus in a fixed intrinsic excitation energy range and that the different EOS are constructed. Although it has been shown that comparisons between such EOS and Monte Carlo simulations give information about the level density and the strength function their interpretation is not too clear because the large number of input values needed in a code like GAMBLE. On the other hand, if we could have an analytical description of EOS, the understanding of the underlying physics would be more simple because one could control exactly the involved variables and eventually simulation would be unnecessary. Promissory advances in that direction come from mathematical theory of Order Statistics (OS) In this work it is described the modified code GAMBLE and some simulated EOS for 170 Hf are shown. The simulations are made with different formulations for both level density (Fermi Gas at constant and variable temperature) and gamma strength function (GDR, single particle). Further it is described in detail how OS are employed in the

  14. Impact of a low-energy enhancement in the gamma-ray strength function on the radiative neutron-capture

    OpenAIRE

    Larsen, A.C.; Goriely, S.

    2012-01-01

    A low-energy enhancement of the gamma-ray strength function in several light and medium-mass nuclei has been observed recently in 3He-induced reactions. The effect of this enhancement on (n,gamma) cross-sections is investigated for stable and unstable neutron-rich Fe, Mo and Cd isotopes. Our results indicate that the radiative neutron capture cross sections may increase considerably due to the low-energy enhancement when approaching the neutron drip line. This could have non-negligible conseq...

  15. In-vivo measurement of kidney and liver cadmium by neutron capture prompt gamma-ray analysis

    International Nuclear Information System (INIS)

    A method for the determination of Cd in-vivo in human kidney and liver has been developed. The technique employs the detection of prompt gamma-rays emitted under slow neutron capture in Cd. The method allows measurement of absolute quantities of Cd in the left kidney and Cd concentration in the liver, in normal population. The limit of detection of cadmium is 2.5 mg for the left kidney and 1.5 μg/g (wet weight) for the liver, for a localized dose of 670 mrem

  16. Investigation of the P-odd asymmetry in the resonance scattering of neutron capture gamma-rays

    International Nuclear Information System (INIS)

    The PCN-Asymmetry of the resonance scattering of circularly polarized neutron capture gamma-rays was investigated for the following nuclei as scatterers: 112Cd, 118Sn, 139La, 141Pr, 142Nd, 205Tl and 208Pb. The experiments were carried out on the polarized neutron beam of the Institut Laue Langevin's High Flux Reactor. For six nuclei-scatterer combinations limits on the value of the PNC-asymmetry of the order 10-4 to 10-3 were obtained. For 205Tl a PNC-asymmetry of a=(+ 4.8 ± 1.5).10-5 was observed

  17. Stabilization of prompt gamma-ray neutron activation analysis (PGNAA) spectra from NaI detectors

    Energy Technology Data Exchange (ETDEWEB)

    Metwally, W.A.; Gardner, R.P. E-mail: gardner@ncsu.edu

    2004-06-11

    NaI detectors are still used frequently in industrial Prompt Gamma-Ray Neutron Activation Analysis applications such as in bulk material analysis. They have the advantages of being efficient for high-energy gamma rays, being relatively rugged, and being able to be used without cooling. When using NaI detectors, and consequently photomultiplier tubes, the quality of the data can drastically deteriorate through gain and zero shifts that result in spectral smearing due to temperature and/or counting rate changes. A new offline approach is presented to stabilize the NaI spectral drift. The approach is not sensitive to the cause of the drift and takes into account the NaI and ADC non-linearities. Peak resolution is improved substantially when this approach is used in the presence of spectral drift.

  18. Stabilization of prompt gamma-ray neutron activation analysis (PGNAA) spectra from NaI detectors

    Science.gov (United States)

    Metwally, W. A.; Gardner, R. P.

    2004-06-01

    NaI detectors are still used frequently in industrial Prompt Gamma-Ray Neutron Activation Analysis applications such as in bulk material analysis. They have the advantages of being efficient for high-energy gamma rays, being relatively rugged, and being able to be used without cooling. When using NaI detectors, and consequently photomultiplier tubes, the quality of the data can drastically deteriorate through gain and zero shifts that result in spectral smearing due to temperature and/or counting rate changes. A new offline approach is presented to stabilize the NaI spectral drift. The approach is not sensitive to the cause of the drift and takes into account the NaI and ADC non-linearities. Peak resolution is improved substantially when this approach is used in the presence of spectral drift.

  19. Gamma-ray spectra of fast-breeder spent nuclear fuel from the BN-350 reactor

    International Nuclear Information System (INIS)

    Gamma-ray measurements of spent nuclear fuel (SNF) from a fast breeder reactor have been obtained with a High-Purity Germanium (HPGe) Detector. The HPGe measurements were performed inside a hot cell using an adjustable collimator to restrict the viewing angle of the HPGe to a small region of the SNF assembly. In addition Ion Chamber (IC) measurements were performed underwater using a lead shielded IC 15-cm in active length. We are going to present HPGe measurement results of the distribution of fission product and activation products along the assembly. We will also compare the gamma-ray profiles of the HPGe and IC measurements to those of the neutron profiles measured with a 3 He tube based neutron counter

  20. A search for double-electron capture in 74Se using coincidence/anticoincidence gamma-ray spectrometry

    CERN Document Server

    Jeskovsky, M; Kovacik, A; Povinec, P P; Puppe, P; Stanicek, J; Sykora, I; Simkovic, F; Thies, J H

    2015-01-01

    Evaluation of single, coincidence and anticoincidence gamma-ray spectrometry methods has been carried out with the aim to search for double-electron capture in 74Se. This process is unique, because there is probability for transition to the 2+ excited state in 74Ge (1204 keV), and de-excitation through two gamma-quanta cascade with energies of 595.9 keV and 608.4 keV. Long-term measurements with anticosmic shielded HPGe spectrometer and the coincidence HPGe-NaI(Tl) spectrometer did not show any evidence for the double-electron capture in 74Se. The best limit for the half-life of the double electron capture in 74Se (both for the neutrinoless and two neutrino processes) was estimated to be >1.5x10E19 years.

  1. Modeling of the $\\gamma$-ray pulsed spectra of Geminga, Crab, and Vela with synchro-curvature radiation

    CERN Document Server

    Viganò, Daniele

    2015-01-01

    $\\gamma$-ray spectra of pulsars have been mostly studied in a phenomenological way, by fitting them to a cut-off power-law function. Here, we analyze a model where pulsed emission comes from synchro-curvature processes in a gap. We calculate the variation of kinetic energy of magnetospheric particles along the gap and the associated radiated spectra, considering an effective particle distribution. We fit the phase-averaged and phase-resolved {\\em Fermi}-LAT spectra of the three brightest $\\gamma$-ray pulsars: Geminga, Crab, and Vela, and constrain the three free parameters we leave free in the model. Our best-fit models well reproduce the observed data, apart from residuals above a few GeV in some cases, range for which the inverse Compton scattering likely becomes the dominant mechanism. In any case, the flat slope at low-energy ($\\lesssim$ GeV) seen by {\\it Fermi}-LAT both in the phase-averaged and phase-resolved spectra of most pulsars, including the ones we studied, requires that most of the detected radi...

  2. A user guide to GASP - a general purpose program for analysis and manipulation of gamma ray spectra

    International Nuclear Information System (INIS)

    The application of a very flexible computer program for the analysis of gamma-ray spectra at Harwell is described at a level suitable for users with practical experience of spectrometry but with limited knowledge of computer methods. Details of running a job are provided in this guide together with a description of the GASP language. The program is designed to allow free format input of data and instructions with the minimum requirements for running a task on the computer. A procedure called GASP can be invoked together with essential parameters which are described. The program itself is centred around the linear regression analysis of spectra produced from either sodium iodide crystals or solid state detectors with anything from 128 to 2048 channels. Various factors which are required for interpreting results (such as decay times, half lives, cross-section, chemical yield) can be entered and applied automatically, thus removing much tedious arithmetical labour. Many facilities have been added which include storage space (either internally to the program or on disk) which may be required for standard spectra and data to describe them. Various other processes which may be applied in gamma-ray spectrometry which include energy calibration, analysis of peaks, and searching for peaks in spectra from solid state detectors are described. A comprehensive list of the 'GASP' vocabulary which is used to present data and instructions to the program is included, together with examples of a number of specific applications. (author)

  3. Monitoring the distribution of prompt gamma rays in boron neutron capture therapy using a multiple-scattering Compton camera: A Monte Carlo simulation study

    International Nuclear Information System (INIS)

    This study evaluated the use of Compton imaging technology to monitor prompt gamma rays emitted by 10B in boron neutron capture therapy (BNCT) applied to a computerized human phantom. The Monte Carlo method, including particle-tracking techniques, was used for simulation. The distribution of prompt gamma rays emitted by the phantom during irradiation with neutron beams is closely associated with the distribution of the boron in the phantom. Maximum likelihood expectation maximization (MLEM) method was applied to the information obtained from the detected prompt gamma rays to reconstruct the distribution of the tumor including the boron uptake regions (BURs). The reconstructed Compton images of the prompt gamma rays were combined with the cross-sectional images of the human phantom. Quantitative analysis of the intensity curves showed that all combined images matched the predetermined conditions of the simulation. The tumors including the BURs were distinguishable if they were more than 2 cm apart

  4. Monitoring the distribution of prompt gamma rays in boron neutron capture therapy using a multiple-scattering Compton camera: A Monte Carlo simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Taewoong; Lee, Hyounggun; Lee, Wonho, E-mail: wonhol@korea.ac.kr

    2015-10-21

    This study evaluated the use of Compton imaging technology to monitor prompt gamma rays emitted by {sup 10}B in boron neutron capture therapy (BNCT) applied to a computerized human phantom. The Monte Carlo method, including particle-tracking techniques, was used for simulation. The distribution of prompt gamma rays emitted by the phantom during irradiation with neutron beams is closely associated with the distribution of the boron in the phantom. Maximum likelihood expectation maximization (MLEM) method was applied to the information obtained from the detected prompt gamma rays to reconstruct the distribution of the tumor including the boron uptake regions (BURs). The reconstructed Compton images of the prompt gamma rays were combined with the cross-sectional images of the human phantom. Quantitative analysis of the intensity curves showed that all combined images matched the predetermined conditions of the simulation. The tumors including the BURs were distinguishable if they were more than 2 cm apart.

  5. Use of an iterative convolution approach for qualitative and quantitative peak analysis in low resolution gamma-ray spectra

    International Nuclear Information System (INIS)

    In many applications, low resolution gamma-ray spectrometers, such as sodium iodide scintillation detectors, are widely used primarily due to their relatively low cost and high detection efficiency. There is widespread interest in improved methods for analyzing spectral data acquired with such devices, using inverse analysis. Peak means and peak areas in gamma- and X-ray spectra are needed for both qualitative and quantitative analysis. This paper introduces the PEAKSI code package that was developed at the Center for Engineering Applications of Radioisotopes (CEAR). The basic approach described here is to use accurate forward models and iterative convolution instead of direct deconvolution. Rather than smoothing and differentiation a combination of linear regression and non-linear searching is used to minimize the reduced chi-square, since this approach retains the capability of establishing uncertainties in the estimated peak parameters. The PEAKSI package uses a Levenberg-Marquardt (LM) non-linear search method combined with multiple linear regression (MLR) to minimize the reduced chi-square value for fitting single or multiple overlapping peaks to determine peak parameters, including peak means, peak standard deviations or full width at half maximum (FWHM), net peak counts, and background counts of peaks in experimental gamma-ray spectra. This approach maintains the natural error structure so that parameter uncertainties can be estimated. The plan is to release this code to the public in the near future.

  6. Detection of low levels of plutonium in natural environments from gamma-ray spectra with advanced methods in robust fitting

    Energy Technology Data Exchange (ETDEWEB)

    Lasche, G.P.; Coldwell, R.L.; Nobel, J.A

    1999-02-11

    A newly developed spectral analysis methodology, RobWin, is experimentally tested for its ability to identify plutonium in highly background-dominated gamma-ray spectra. The method, which builds upon nonlinear robust fitting techniques from RobFit spectral analysis software, emphasizes gradually adding structure to the entire spectrum background shape function after accounting for re-optimized combinations of entire-spectrum photopeak response functions from a user-defined set of nuclides at each iteration. This new feature makes it uniquely suited to the identification of weak-strength nuclides in high-background environments. The method is briefly described and applied to a series of background-dominated laboratory gamma-ray spectra from a 98 nCi {sup 239}Pu source with logarithmically varying collection times taken with a 100% n-type HPGe detector. The laboratory experiment, the data, and the analysis results are presented. As a measure of confidence in the effectiveness of the several entire-spectrum features of the new approach, comparisons of confidence levels, and detectable total isotopic counts are made with analysis of the same data by fitting only peaks with these new features disabled. It is concluded that for similar applications the new method can improve detectable strength and confidence of detection significantly.

  7. Detection of low levels of plutonium in natural environments from gamma-ray spectra with advanced methods in robust fitting

    International Nuclear Information System (INIS)

    A newly developed spectral analysis methodology, RobWin, is experimentally tested for its ability to identify plutonium in highly background-dominated gamma-ray spectra. The method, which builds upon nonlinear robust fitting techniques from RobFit spectral analysis software, emphasizes gradually adding structure to the entire spectrum background shape function after accounting for re-optimized combinations of entire-spectrum photopeak response functions from a user-defined set of nuclides at each iteration. This new feature makes it uniquely suited to the identification of weak-strength nuclides in high-background environments. The method is briefly described and applied to a series of background-dominated laboratory gamma-ray spectra from a 98 nCi 239Pu source with logarithmically varying collection times taken with a 100% n-type HPGe detector. The laboratory experiment, the data, and the analysis results are presented. As a measure of confidence in the effectiveness of the several entire-spectrum features of the new approach, comparisons of confidence levels, and detectable total isotopic counts are made with analysis of the same data by fitting only peaks with these new features disabled. It is concluded that for similar applications the new method can improve detectable strength and confidence of detection significantly

  8. Uses of neutron capture gamma-rays in environmental pollution applications

    International Nuclear Information System (INIS)

    As a sensitive and accurate technique, the prompt gamma-rays neutron activation is used with success for elemental analysis. The advantages of this method over the other techniques are rapidity, usage of relatively large sample size and high reliability, beside the detection of the elements which have no gamma activity during the delayed neutron activation analysis or very short lived isotopes. Actually different techniques could be used for estimating the trace, minor and major elements of these environmental samples which are considered as complex samples. In the mean time the neutron activation analysis techniques have been improved and have become an excellent tool for elemental analysis of complex samples (Duffey et al., 1970; Senftle et al., 1971; Henkelmm and Born, 1973 ; Hassan et al., .; 1981, 1982, 1983; Clyton et al., 1983; Zaghloul et al., 1993) and the advantages of the prompt γ- ray neutron activation analysis over the other techniques put this technique in the fore front

  9. Light curves and spectra from off-axis gamma-ray burst single pulses

    CERN Document Server

    Salafia, Om S; Pescalli, Alessio; Ghirlanda, Giancarlo; Nappo, Francesco

    2016-01-01

    We set up a simple model to compute the bolometric light curve and time dependent spectrum of a single pulse of a Gamma-Ray Burst under the assumption that the pulse rise and decay are dominated by the shell curvature effect. For the first time, our model includes the effect of an arbitrary off-axis viewing angle. We show that a pulse observed off-axis is (i) longer, (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 many observed properties found in time-resolved spectral analysis of Gamma-Ray Burst light curves are reproduced in curves with a slightly off-axis viewing angle. Such properties include the fact that the spectral peak energy evolution tracks the variations in flux, leading them slightly. Based on these results, we argue that low lum...

  10. Measurements of gamma rays from keV-neutron resonance capture by odd-Z nuclei in the 2s-1d shell region

    Energy Technology Data Exchange (ETDEWEB)

    Igashira, Masayuki; Lee, Sam Yol; Mizuno, Satoshi; Hori, Jun-ichi [Tokyo Inst. of Tech. (Japan). Research Lab. for Nuclear Reactors; Kitazawa, Hideo

    1998-03-01

    Measurements of gamma rays from keV-neutron resonance capture by {sup 19}F, {sup 23}Na, and {sup 27}Al, which are odd-Z nuclei in the 2s-1d shell region, were performed, using an anti-Compton HPGe spectrometer and a pulsed neutron source by the {sup 7}Li(p,n){sup 7}Be reaction. Capture gamma rays from the 27-, 49-, and 97-keV resonances of {sup 19}F, the 35- and 53-keV resonances of {sup 23}Na, and the 35-keV resonance of {sup 27}Al were observed. Some results are presented. (author)

  11. Analyzing global distribution of thorium on the lunar surface using Chang' E-1 Gamma-Ray spectrometer spectra data

    International Nuclear Information System (INIS)

    In order to acquire the global elemental distributions on the lunar surface, a method to process level 2C spectra data measured by Chang' E-1 gamma-ray spectrometer (CE1-GRS) was proposed and implemented. After data processing made by this method to level 2C spectra measured from 27 Nov, 2007 to 6 Feb, 2008, preliminary global counting rate map of thorium is derived. Compared with the global map of thorium measured by the Lunar Prospector (LP) GRS, the result shows that major features of the global thorium distribution appeared in CE1 map is consistent with the map of thorium from the LP GRS, but there are still some differences in detail between these two maps. (authors)

  12. Software tool for xenon gamma-ray spectrometer control

    Science.gov (United States)

    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.

  13. On thermalization in gamma-ray burst jets and the peak energies of photospheric spectra

    CERN Document Server

    Vurm, Indrek; Piran, Tsvi

    2012-01-01

    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 Thompson 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 termalization 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 i...

  14. PCGAP. Application to analyze gamma-ray pulse-height spectra on a personal computer under Windows NTR

    International Nuclear Information System (INIS)

    PCGAP is a software code, which was written to provide gamma-ray pulse height spectrum analysis on a personal computer platform. The code was specifically developed for Windows NT for either an IntelR or DEC AlphaR based processor. PCGAP includes programs which can be used to control data collection using a Canberra INSPECTORR multichannel pulse-height analyzer. With suitable spectrum conversion routines PCGAP can be used to analyze data from almost any multi-channel analyzer. Besides the normal functions associated with a robust spectrum analysis package, PCGAP can be used for radionuclide analysis for actinides via L-X and gamma-ray spectrometry. It can be used to control and analyze data from an INEEL developed pulse injection system for individual spectrum validation. The package includes programs for the manual analysis of spectra using displays which permit the spectroscopist to interactively define the spectral continuum and peak fitting limits, and display the resulting function fitting forms. (author)

  15. High-Quality Medium-Resolution Gamma-Ray Spectra from Certified Reference Uranium and Plutonium Materials

    International Nuclear Information System (INIS)

    The Institute of Transuranium Elements (ITU) has made an effort to record a collection of medium resolution gamma-ray spectra from well-characterized U and Pu certified reference materials CRM-171 (also known as SRM-969), CBNM-271, and Harwell PIDIE standards. The goal of this exercise was twofold: (i) to complement the international database of reference gamma-ray spectra with high-quality data for medium resolution spectrometers, and (ii) to feed Phase I of the U/Pu isotopic inter-comparison exercise that is being jointly organized by the ESARDA NDA Working Group and IAEA. Phase II of the exercise will be fed by similar spectra recorded by Institute for Radiological Protection and Nuclear Safety (IRSN). These activities are supported through a joint Member State Support Programmes (MSSP) task and aimed at delivering reliable methodologies for the determination of U/Pu isotopic composition using medium resolution gamma-spectrometers. The latter have obvious benefits for in-field applications, amongst which are better usability, portability and maintainability. As the spectra will be made available online for software developers and end users, ultimately this will also contribute to sustainability as well as the improved and validated performance of existing U/Pu isotopic codes. The spectra were recorded using the IAEA's standard Lanthanum Bromide (LaBr3(Ce)) (2.0'' x 0.5'') and Cadmium Zink Telluride (CdZnTe) (500 mm''3) detectors and acquisition electronics. Aiming to acquire the highest quality reference data, the spectra were measured for long acquisition times, ensuring very good counting statistics across potentially useful spectral intervals — up to 1 MeV for the CdZnTe and up to 2.6 MeV for the LaBr3(Ce) detectors. Great attention was also paid to ensure that the measurement geometry was stable and reproducible, and the spectra had minimum influence from background radiation and pile-up effects. The paper will briefly

  16. A reevaluation of commercial IBM PC software for the analysis of low-level environmental gamma-ray spectra

    International Nuclear Information System (INIS)

    In 1988, a comparative evaluation of seven commercially available software packages for the analysis of low-level environmental gamma-ray spectra was performed. At that time it was determined that many of the packages did not contain all the features that were necessary for the accurate analysis of complex, low-level environmental samples. The evaluation concentrated on peak detection, noise and phantom-peak rejection, resolution of peak doublets, and nuclide identification. A new evaluation was conducted on updated versions of four of the previously evaluated programs and two additional programs from Canada and Germany. The evaluation involved the analysis of synthetic and actual spectral data, including an air filter containing debris from the Chernobyl accident. System requirements, accurate nuclide quantification and ease of operation are also reported. (author)

  17. Literature survey of chemical analysis by thermal neutron induced capture gamma ray spectrometry

    International Nuclear Information System (INIS)

    A brief discussion of the principles and techniques of chemical analysis by neutron capture gamma radiation is presented, and the widely scattered literature is collected into a single table arranged by element measured

  18. Soft X-ray absorption excess in gamma-ray burst afterglow spectra: Absorption by turbulent ISM

    CERN Document Server

    Tanga, M; Gatto, A; Greiner, J; Krause, M G H; Diehl, R; Savaglio, S; Walch, S

    2016-01-01

    Two-thirds of long duration gamma-ray bursts (GRBs) show soft X-ray absorption in excess of the Milky Way. The column densities of metals inferred from UV and optical spectra differ from those derived from soft X-ray spectra, at times by an order of magnitude, with the latter being higher. The origin of the soft X-ray absorption excess observed in GRB X-ray afterglow spectra remains a heavily debated issue, which has resulted in numerous investigations on the effect of hot material both internal and external to the GRB host galaxy on our X-ray afterglow observations. Nevertheless, all models proposed so far have either only been able to account for a subset of our observations (i.e. at z > 2), or they have required fairly extreme conditions to be present within the absorbing material. In this paper, we investigate the absorption of the GRB afterglow by a collisionally ionised and turbulent interstellar medium (ISM). We find that a dense (3 per cubic centimeters) collisionally ionised ISM could produce UV/opti...

  19. Relation among gamma-ray energy spectra, exposure rates and effective dose equivalents rates in the working places of the KUR reactor room

    International Nuclear Information System (INIS)

    Exposure rates and Effective dose equivalents are estimated on the basis of gamma-ray energy spectra in some places of the KUR reactor room. A relation among those radiation protection quantities are investigated to know the most appropriate way for estimation of radiation risks to radiation worekers. (author)

  20. An approach of a systematical description of gamma-ray spectra from (n,xγ). Reactions induced by fast neutron

    International Nuclear Information System (INIS)

    Based on the semi-empirical method which used to calculate the gamma-ray production data from neutron induced reactions, within the target mass number of 20n<20 MeV, the systematics for parameter R was obtained. And the sensitivity of the parameter R to the total spectra was studied. (1 tab., 8 figs.)

  1. Airborne gamma-ray spectrometry

    DEFF Research Database (Denmark)

    Hovgaard, Jens

    A new method - Noise Adjusted Singular Value Decomposition, NASVD - for processing gamma-ray spectra has been developed as part of a Ph.D. project. By using this technique one is able to decompose a large set of data - for example from airborne gamma-ray surveys - into a few spectral components. ...

  2. Gamma ray internal conversion lines shift resulting from atom ionization after electron capture

    International Nuclear Information System (INIS)

    Energy differencies of four couples of transitions in γ- and conversion spectra of 152Eu and 184Re isomers are measured with high precision. γ-spectra are measured using the HGe detectors. The spectra of conversion electrons are measured using the magnetic high-resolution beta-spectrometer of the π√2 type. The comparison of energy differences of γ-rays of 963 and 970 keV transitions with the energy difference of their K-lines has revealed the effect of K-line internal conversion shift which is 20±7eV for K963 transition resolving the level from T1/2=3x10-14s 152Sm. The comparison of energy differences of 963 and 964 keV transitions has produced the shift value for K963 20±9eV. The average weighted value of these two independent measurements is 20±6eV. For conversion transitions resolving more long-lived levels (T1/2≥9x10-13s) the effect is not found. The lifetime of atoms in the ionized state is estimated

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

    CERN Document Server

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

    2016-01-01

    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 <3.0 sigma. 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 (N_H) testing different models for the Galactic absorption confirms this origin because we found an indication of an...

  4. Stabilization of spectra provided by a gamma-ray spectrometer. Application to the construction of a stabilizer

    International Nuclear Information System (INIS)

    This research is concerned with the stabilization of spectra provided by a gamma-ray spectrometer. It is required to hold the calibration straight line of the spectrometer in a position which is fixed initially to better than 5x10-5 channel. A prototype numerical stabilizer has been constructed : the SPECTROSTAB; it is made up of two independent control loops; one of these makes the spectrometer gain depend on the derivatives of a reference peak at high energies; the other makes the origin of the energy scale depend on the derivatives of a second reference peak at low energies A theoretical study of the behaviour of a control loop shows that a direct action stabilizer gives the most accurate stabilization; the loss in resolving power on the theoretical peaks of the spectra attains about 1 % with a scintillation detector, and 10 % with a semi-conductor detector. Various tests show that the expected results are obtained and that the displacement of the spectral peaks produced by the derivatives are hidden by errors in the calculation of the peak abscissae. (author)

  5. Comparisons of peak-search and photopeak-integration methods in the computer analysis of gamma-ray spectra

    International Nuclear Information System (INIS)

    Myriad methods have been devised for extracting quantitative information from gamma-ray spectra by means of a computer, and a critical evaluation of the relative merits of the various programs that have been written would represent a Herculean, if not an impossible, task. The results from the International Atomic Energy Agency (IAEA) intercomparison, which may represent the most straightforward approach to making such an evaluation, showed a wide range in the quality of the results - even among laboratories where similar methods were used. The most clear-cut way of differentiating between programs is by the method used to evaluate peak areas: by the iterative fitting of the spectral features to an often complex model, or by a simple summation procedure. Previous comparisons have shown that relatively simple algorithms can compete favorably with fitting procedures, although fitting holds the greatest promise for the detection and measurement of complex peaks. However, fitting algorithms, which are generally complex and time consuming, are often ruled out by practical limitations based on the type of computing equipment available, cost limitations, the number of spectra to be processed in a given time period, and the ultimate goal of the analysis. Comparisons of methods can be useful, however, in helping to illustrate the limitations of the various algorithms that have been devised. This paper presents a limited review of some of the more common peak-search and peak-integration methods, along with Peak-search procedures

  6. On the sharpness of gamma-ray burst prompt emission spectra

    CERN Document Server

    Yu, Hoi-Fung; Greiner, Jochen; Sari, Re'em; Bhat, P Narayana; von Kienlin, Andreas; Paciesas, William S; Preece, Robert D

    2015-01-01

    We aim to obtain a measure of the curvature of time-resolved spectra that can be compared directly to theory. This tests the ability of models such as synchrotron emission to explain the peaks or breaks of GBM prompt emission spectra. We take the burst sample from the official Fermi GBM GRB time-resolved spectral catalog. We re-fit all spectra with a measured peak or break energy in the catalog best-fit models in various energy ranges, which cover the curvature around the spectral peak or break, resulting in a total of 1,113 spectra being analysed. We compute the sharpness angles under the peak or break of the triangle constructed under the model fit curves and compare to the values obtained from various representative emission models: blackbody, single-electron synchrotron, synchrotron emission from a Maxwellian or power-law electron distribution. We find that 35% of the time-resolved spectra are inconsistent with the single-electron synchrotron function, and 91% are inconsistent with the Maxwellian synchrot...

  7. Feasibility of using prompt neutron capture gamma rays to detect mercury

    International Nuclear Information System (INIS)

    This report describes a study to determine the feasibility to use neutrons to probe hidden spaces within buildings for the presence of mercury. The study was performed in four phases: First a search of the scientific literature was performed to ascertain the behavior of mercury subsequent to the capture of a thermal or near-thermal neutron. Second, a Monte Carlo investigation (using the code MCNP) of the effects of neutrons on materials expected to be found near and/or surrounding the mercury was undertaken. Third, a Monte Carlo study of the shielding and beam forming properties of various configurations of moderator material was started. Lastly, a Monte Carlo analysis of a likely field situation involving mercury behind 1 inch and 2 inch thicknesses of concrete was performed

  8. Evaluation of gamma ray production cross sections and spectra for neutron induced reactions on Chromium

    International Nuclear Information System (INIS)

    An evaluation of photon production cross sections and relevant spectra is described, referring to neutron induced reactions on *H5*H0CR, *H5*H2CR, *H5*H4CR and sup(nat)CR in the energy range 100 KEV-8MEV

  9. On-line bulk analysis of raw material in a cement plant using the neutron irradiation and capture gamma ray technique

    International Nuclear Information System (INIS)

    In collaboration with Ciments Lafarge, the Laboratoire central des ponts et chaussees (LCPC) has developed a technique, involving neutron irradiation, for on-line bulk analysis of raw material quality, along the input line to a cement plant, by determining the quantities of the following elements: calcium, silicon, aluminium and iron. A system was constructed and tested in a cement plant under actual service conditions. The system consists of a sampler placed on the on-stream line supplying the plant at a rate of 1000 t/h. An analysing hopper incorporating a neutron irradiation system, consisting of a 14 MeV neutron generator tube, and a gamma ray detection system, comprising a NaI(Tl) scintillator associated with a photomultiplier, are coupled to this sampler. The system is fed continuously with the raw material to be analysed. Gamma radiation spectra supplied by the detector are analysed on two distinct measurement channels. One of these channels processes the nuclear radiation generated by neutron capture phenomena, while the other channel processes the nuclear radiation resulting from neutron activation phenomena. The data collected under the operating conditions mentioned above (i.e. in real time) allows readings to be obtained every 2 min for silicon, calcium, aluminium and iron as a result of the processing method applied to gamma capture and activation spectra. A comparison was made between these measurements and the results of an analysis of the same piles, conducted simultaneously through a sampling tower delivering at an hourly rate a sample analysed in accord with the X ray fluorescence process. Comparison of the results obtained from both analysis methods highlights the advantages of the neutron irradiation process. (author). 4 figs, 2 tabs

  10. Study of 237Np photonuclear reactions near threshold, induced by gamma rays from thermal neutron capture

    International Nuclear Information System (INIS)

    The photodisintegration of 237Np has been studied using monochromatic photons produced by thermal neutron capture in several materials. The partial cross sections σ gamma, sub(f) and σ gamma, sub(n) were measured in the energy interval from 5.43 MeV to 10.83 MeV. Analysing the photofission data according to the liquid drop model, the height (E sub(f)) and the curvature ((h/2π)ω) of the simple fission barrier were determined: E sub(f) = (5.9 +- 0.2) MeV and (h/2π)ω = (0.8 +- 0.4) MeV. For the competition between photoneutron emission and fission (GAMMA sub(n) / GAMMA sub(f) a constant value was found (1.28+- 0.15) in the energy range 6.73 - 10.83 MeV. From this result the following nuclear temperatures for 237Np were extracted on bases of some models of levels density: T = 0.84 +- 0.06 MeV (Fujimoto-Yamaguchi model) and T = 0.60 +- 0.04 MeV (Constant Nuclear temperature model). (Author)

  11. Resolving the Extragalactic Background Light with gamma-ray spectra from distant blazars

    CERN Document Server

    Aharonian, F; Bazer-Bachi, A R; Beilicke, M; Benbow, W; Berge, D; Bernlöhr, K; Boisson, C; Bolz, O; Borrel, V; Braun, I; Breitling, F; Brown, A M; Chadwick, P M; Chounet, L M; Cornils, R; Costamante, L; Degrange, B; Dickinson, H J; Djannati-Ata, A; O'Connor-Drury, L; Dubus, G; Emmanoulopoulos, D; Espigat, P; Feinstein, F; Fontaine, G; Fuchs, Y; Funk, S; Gallant, Y A; Giebels, B; Gillessen, S; Glicenstein, J F; Goret, P; Hadjichristidis, C; Hauser, D; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hofmann, W; Holleran, M; Horns, D; Jacholkowska, A; De Jager, O C; Khelifi, B; Klages, S; Komin, Nu; Konopelko, A; Latham, I J; Le Gallou, R; Lemiere, A; Lemoine-Goumard, M; Leroy, N; Lohse, T; Martin, J M; Martineau--, O; Huynh; Marcowith, A; Masterson, C; McComb, T J L; De Naurois, Mathieu; Nolan, S J; Noutsos, A; Orford, K J; Osborne, J L; Ouchrif, M; Panter, M; Pelletier, G; Pita, S; Pühlhofer, G; Punch, M; Raubenheimer, B C; Raue, M; Raux, J; Rayner, S M; Reimer, A; Reimer, O; Ripken, J; Rob, L; Rolland, L; Rowell, G; Sahakian, V V; Sauge, L; Schlenker, S; Schlickeiser, R; Schuster, C; Schwanke, U; Siewert, M; Sol, H; Spangler, D; Steenkamp, R; Stegmann, C; Tavernet, J P; Terrier, R; Theoret, C G; Tluczykont, M; Van Eldik, C; Vasileiadis, G; Venter, C; Vincent, P; Völk, H J; Wagner, S J

    2006-01-01

    The diffuse Extragalactic Background Light (EBL) contains unique information about the epochs of formation and the history of evolution of galaxies. Unfortunately, direct measurements are subject to large systematic uncertainties due to the difficulties in the accurate model-based subtraction of the bright foregrounds. An alternative approach is based on the detection and identification of EBL absorption features in high-energy spectra of objects of known redshift. Here we exploit this method on the blazars H 2356-309 (z=0.165) and 1ES 1101-232 (z=0.186), newly discovered at TeV energies by the H.E.S.S. Collaboration. They are the most distant sources with measured spectra known so far at these energies. Their hard spectra provide the most stringent upper limit to date on the EBL in the Opt--NIR band, which appears significantly lower than expected from the current "direct" estimates and very close to the absolute lower limit represented by the integrated light of resolved galaxies. In addition to important c...

  12. Transmitted photon spectra of low-energy gamma rays through water

    International Nuclear Information System (INIS)

    From the transmitted spectra of point sources it is concluded that in a medium of low effective atomic number, a multiple-scatter peak is observed at an energy below 100 keV where Compton collisions are not very effective in energy-degradation and photoelectric cross-section is negligible. The energy of the peak does not depend on the thickness and physical state of the medium, or on the primary photon energy. The intensity of the peak decreases exponentially with the thickness of the medium. Measured build-up factors are compared with the calculated ones available in the literature. (author)

  13. Portable microcomputer for the analysis of plutonium gamma-ray spectra. Volume I. Data analysis methodology and hardware description

    International Nuclear Information System (INIS)

    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 had 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 241Pu and 208-keV 237U 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

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

    International Nuclear Information System (INIS)

    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 241Pu and 208-keV 237U 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. Broad band turbulent spectra in gamma-ray burst light curves

    CERN Document Server

    van Putten, Maurice H P M; Frontera, Filippo

    2014-01-01

    Broad band 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 GRBs. We describe a chirp search method which steps aside Fourier analysis for signal detection in the Poisson noise-dominated 2 kHz sampled BeppoSAX light curves. An efficient numerical implementation is described in $O(Nn\\log n)$ 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 detection of individual chirps of duration $\\tau=1$ s, the method is one order of magnitude more sensitive in SNR than Fourier analysis. The Fourier-chirp spectra of GRB 010408 and GRB 970816 show a continuation of the spectral slope up to 1 kHz of turbulence identified in low frequency Fourier analysis. The same continuation is observed in an ensemble averaged spectrum of 40 bright long GRBs. An outlook on a similar analysis of upcoming gra...

  16. First tests of the applicability of $\\gamma$-ray imaging for background discrimination in time-of-flight neutron capture measurements

    OpenAIRE

    Magán, D. L. Pérez; Caballero-Ontanaya, L.; Domingo-Pardo, C.; Agramunt-Ros, J.; Albiol, F.; Casanovas, A.; González, A; Guerrero, C.; Lerendegui-Marco, J.; Tarifeño-Saldivia, A.; Collaboration, the n_TOF

    2015-01-01

    In this work we explore for the first time the applicability of using $\\gamma$-ray imaging in neutron capture measurements to identify and suppress spatially localized background. For this aim, a pinhole gamma camera is assembled, tested and characterized in terms of energy and spatial performance. It consists of a monolithic CeBr$_3$ scintillating crystal coupled to a position-sensitive photomultiplier and readout through an integrated circuit AMIC2GR. The pinhole collimator is a massive car...

  17. PC based analysis of gamma ray spectra generated by semiconductor detectors

    International Nuclear Information System (INIS)

    This report describes a spectrum analysis method and computer program for analysis of gamma spectra obtained by using semiconductor detectors and multichannel analysers. The analysis steps incorporated are smoothing, peak location using signal processing method of convolution, selectable background subtraction viz linear, polynomial and step like, peak fitting both for singlets and doublets using Mukoyama's method for evaluation of full width at half maximum and area evaluation including errors in its evaluation. The program also provides a facility for energy calibration. Typical results of analysis for singlets and doublets are included. This report is based on Wilson's report which has been modified and extended. The program is written in BASIC and its listing is included in the appendices. (author). 20 refs., 2 figs., 2 tabs

  18. Monte Carlo assessment of soil moisture effect on high-energy thermal neutron capture gamma-ray by {sup 14}N

    Energy Technology Data Exchange (ETDEWEB)

    Pazirandeh, Ali [Physics Department, University of Tehran, Tehran (Iran, Islamic Republic of) and Institute for Theoretical and Applied Physics, Tabriz (Iran, Islamic Republic of)]. E-mail: paziran@ut.ac.ir; Azizi, Maryam [Physics Department, University of Tehran, Tehran (Iran, Islamic Republic of); Institute for Theoretical and Applied Physics, Tabriz (Iran, Islamic Republic of); Farhad Masoudi, S. [Physics Department, University of Tehran, Tehran (Iran, Islamic Republic of); Institute for Theoretical and Applied Physics, Tabriz (Iran, Islamic Republic of)

    2006-01-01

    Among many conventional techniques, nuclear techniques have shown to be faster, more reliable, and more effective in detecting explosives. In the present work, neutrons from a 5 Ci Am-Be neutron source being in water tank are captured by elements of soil and landmine (TNT), namely {sup 14}N, H, C, and O. The prompt capture gamma-ray spectrum taken by a NaI (Tl) scintillation detector indicates the characteristic photo peaks of the elements in soil and landmine. In the high-energy region of the gamma-ray spectrum, besides 10.829 MeV of {sup 15}N, single escape (SE) and double escape (DE) peaks are unmistakable photo peaks, which make the detection of concealed explosive possible. The soil has the property of moderating neutrons as well as diffusing the thermal neutron flux. Among many elements in soil, silicon is more abundant and {sup 29}Si emits 10.607 MeV prompt capture gamma-ray, which makes 10.829 MeV detection difficult. The Monte Carlo simulation was used to adjust source-target-detector distances and soil moisture content to yield the best result. Therefore, we applied MCNP4C for configuration very close to reality of a hidden landmine in soil.

  19. EMISSION FROM HOT DUST IN THE INFRARED SPECTRA OF GAMMA-RAY BRIGHT BLAZARS

    International Nuclear Information System (INIS)

    A possible source of γ-ray photons observed from the jets of blazars is inverse Compton scattering by relativistic electrons of infrared seed photons from a hot, dusty torus in the nucleus. We use observations from the Spitzer Space Telescope to search for signatures of such dust in the infrared spectra of four γ-ray bright blazars, the quasars 4C 21.35, CTA102, and PKS 1510-089, and the BL Lacertae object ON231. The spectral energy distribution (SED) of 4C 21.35 contains a prominent infrared excess indicative of dust emission. After subtracting a non-thermal component with a power-law spectrum, we fit a dust model to the residual SED. The model consists of a blackbody with temperature ∼1200 K, plus a much weaker optically thin component at ∼660 K. The total luminosity of the thermal dust emission is 7.9 ± 0.2 x 1045 erg s-1. If the dust lies in an equatorial torus, the density of infrared photons from the torus is sufficient to explain the γ-ray flux from 4C 21.35 as long as the scattering occurs within a few parsecs of the central engine. We also report a tentative detection of dust in the quasar CTA102, in which the luminosity of the infrared excess is 7 ± 2 x 1045 erg s-1. However, in CTA102 the far-infrared spectra are too noisy to detect the 10 μm silicate feature. Upper limits to the luminosity from thermal emission from dust in PKS 1510-089, and ON231, are 2.3 x 1045, and 6.6 x 1043 erg s-1, respectively. These upper limits do not rule out the possibility of inverse Compton upscattering of infrared photons to γ-ray energies in these two sources. The estimated covering factor of the hot dust in 4C 21.35, 22%, is similar to that of non-blazar quasars; however, 4C 21.35 is deficient in cooler dust.

  20. Planetary gamma-ray spectroscopy

    International Nuclear Information System (INIS)

    The chemical composition of a planet can be inferred from the gamma rays escaping from its surface and can be used to study its origin and evolution. The measured intensities of certain gamma rays of specific energies can be used to determine the abundances of a number of elements. The major sources of these gamma-ray lines are the decay of natural radionuclides, reactions induced by energetic galactic-cosmic-ray particles, capture of low energy neutrons, and solar-proton-induced radioactivities. The fluxes of the more intense gamma-ray lines emitted from 30 elements were calculated using current nuclear data and existing models. The source strengths for neutron-capture reactions were modified from those previously used. The fluxes emitted from a surface of average lunar composition are reported for 288 gamma-ray lines. These theoretical fluxes have been used elsewhere to convert the data from the Apollo gamma-ray spectrometers to elemental abundances and can be used with results from future missions to map the concentrations of a number of elements over a planet's surface. Detection sensitivities for these elements are examined and applications of gamma-ray spectroscopy for future orbiters to Mars and other solar-system objects are discussed

  1. Planetary gamma-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Reedy, R.C.

    1978-01-01

    The chemical composition of a planet can be inferred from the gamma rays escaping from its surface and can be used to study its origin and evolution. The measured intensities of certain gamma rays of specific energies can be used to determine the abundances of a number of elements. The major sources of these gamma-ray lines are the decay of natural radionuclides, reactions induced by energetic galactic-cosmic-ray particles, capture of low energy neutrons, and solar-proton-induced radioactivities. The fluxes of the more intense gamma-ray lines emitted from 30 elements were calculated using current nuclear data and existing models. The source strengths for neutron-capture reactions were modified from those previously used. The fluxes emitted from a surface of average lunar composition are reported for 288 gamma-ray lines. These theoretical fluxes have been used elsewhere to convert the data from the Apollo gamma-ray spectrometers to elemental abundances and can be used with results from future missions to map the concentrations of a number of elements over a planet's surface. Detection sensitivities for these elements are examined and applications of gamma-ray spectroscopy for future orbiters to Mars and other solar-system objects are discussed.

  2. Gamma-ray irradiation effect on the absorption and luminescence spectra of Nd:GGG and Nd:GSGG laser crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sun Dunlu [Crystal Lab, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shushanhu Road 350, PO Box 1125, Hefei, Anhui 230031 (China); Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, Aveiro 3810-193 (Portugal)], E-mail: dlsun@aiofm.ac.cn; Luo Jianqiao; Zhang Qingli [Crystal Lab, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shushanhu Road 350, PO Box 1125, Hefei, Anhui 230031 (China); Xiao Jingzhong [Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, Aveiro 3810-193 (Portugal); Xu Jiayue [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Jiang Haihe; Yin Shaotang [Crystal Lab, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shushanhu Road 350, PO Box 1125, Hefei, Anhui 230031 (China)

    2008-12-15

    Laser crystals Nd{sup 3+}:Gd{sub 3}Ga{sub 5}O{sub 12} (Nd:GGG) and Nd{sup 3+}:Gd{sub 3}Sc{sub 2}Ga{sub 3}O{sub 12} (Nd:GSGG) were grown by Czochralski method. The influence of gamma-ray irradiation on their absorption and luminescence spectra has been investigated. Two additional absorption (AA) bands induced by gamma-ray irradiation appear in the spectra of Nd:GGG crystal while only a very weak AA band appears for the Nd:GSGG crystal. This indicated that Nd:GSGG crystal has stronger ability to resist the color center formation by irradiation. The intensity of the excitation and emission spectra of Nd:GGG crystal decrease after the irradiation of 100 Mrad gamma-ray. In contrast, a luminescence strengthening effect was observed in Nd:GSGG crystal after exposure to the same irradiation dose. The results showed that the Nd:GSGG crystal is a promising candidate used under radiation environments such as in outer space.

  3. Gamma-ray irradiation effect on the absorption and luminescence spectra of Nd:GGG and Nd:GSGG laser crystals

    International Nuclear Information System (INIS)

    Laser crystals Nd3+:Gd3Ga5O12 (Nd:GGG) and Nd3+:Gd3Sc2Ga3O12 (Nd:GSGG) were grown by Czochralski method. The influence of gamma-ray irradiation on their absorption and luminescence spectra has been investigated. Two additional absorption (AA) bands induced by gamma-ray irradiation appear in the spectra of Nd:GGG crystal while only a very weak AA band appears for the Nd:GSGG crystal. This indicated that Nd:GSGG crystal has stronger ability to resist the color center formation by irradiation. The intensity of the excitation and emission spectra of Nd:GGG crystal decrease after the irradiation of 100 Mrad gamma-ray. In contrast, a luminescence strengthening effect was observed in Nd:GSGG crystal after exposure to the same irradiation dose. The results showed that the Nd:GSGG crystal is a promising candidate used under radiation environments such as in outer space

  4. A comparative study on experimental and theoretical ESR spectra of lactic acid polymers irradiated by gamma rays

    International Nuclear Information System (INIS)

    Homo polymers of L-Lactic acid (LLA) and D,L-Lactic acid (DLLA), being biocompatible and absorbable in body iluids have recently found wide applications in the preparation of surgical sutures, controlled drug delivery systems, burn wound coverings etc. For sometime these polymers have also been prepared in the form of plates and screws for mandibular fracture fixation, tissue implants. Their chemical sensitivities against relatively high temperatures and hydrolysis with water make them unsuitable for conventional sterilization techniques like hot water vapor and ethylene oxide. Sterilization of the devices made of these polymers is therefore possible by gamma ray irradiation. This has initiated a number of research works in order to better understand the effects of ionizing radiation on this polymer. The aim of this study is to determine the possible radical types, their location on macromolecular structure and the reasons for peak shifts in the experimental and theoretical ESR spectra. Polymer samples were irradiated in air and in vacuum (10□□ torr) to 25 kGy sterilization dose at the dose rate 0.59 kGy/h and at room temperature by 60Co γ-irradiator. Despite being chemically the same radical type, some differences were observed in the splitting of peaks of PLLA and PDLLA samples. These differences were determined and compared by means of fitting studies. Firstly, PLLA was characterized and its g and hyperfine splitting values were found as 2.0032±0.0002 and 20.37±0.2. In the characterization study of PDLLA, it was found that one of the nearest two radicals was on the upper and the other one was on the lower plane of PDLLA chain. (author)

  5. Boron concentrations in brain during boron neutron capture therapy: in vivo measurements from the Phase I trial EORTC 11961 using a gamma-ray telescope

    International Nuclear Information System (INIS)

    Purpose: Gamma-ray spectroscopic scans to measure boron concentrations in the irradiated volume were performed during treatment of 5 patients suffering from brain tumors with boron neutron capture therapy (BNCT). In BNCT, the dose that is meant to be targeted primarily to the tumor is the dose coming from the reaction 10B(n,α)7Li, which is determined by the boron concentration in tissue and the thermal neutron fluence rate. The boron distribution throughout the head of the patient during the treatment is therefore of major interest. The detection of the boron distribution during the irradiation was until now not possible. Methods and Materials: Five patients suffering from glioblastoma multiforme and treated with BNCT in a dose escalation study were administered the boron compound, boron sulfhydryl (BSH; Na2B12H11SH). Boron concentrations were reconstructed from measurements performed with the gamma-ray telescope which detects locally the specific gamma rays produced by neutron capture in 10B and 1H. Results: For all patients, at a 10B concentration in blood of 30 ppm, the boron concentration in nonoperated areas of the brain was very low, between 1 and 2.5 ppm. In the target volume, which included the area where the tumor had been removed and where remaining tumor cells have to be assumed, much higher boron concentrations were measured with large variations from one patient to another. Superficial tissue contained a higher concentration of 10B than the nonoperated areas of the brain, ranging between 8 and 15 ppm. Conclusions: The measured results correspond with previous tissue uptake studies, confirming that normal brain tissue hardly absorbs the boron compound BSH. Gamma-ray telescope measurements seem to be a promising method to provide information on the biodistribution of boron during therapy. Furthermore, it also opens the possibility of in vivo dosimetry

  6. DELIN and DELOG codes for graphic representation of gamma ray spectra; Programas DELIN y DELOG para la representacion grafica de espectros gamma

    Energy Technology Data Exchange (ETDEWEB)

    Romero, L.; Travesi, A.

    1983-07-01

    Two Fortran IV Codes has been developed for graphic representation of the gamma-ray spectra obtained with Ge Li detectors and multichannel analyzers. The grafic plotting es carried out with the H.P. Graphic Plotter Mod HP-7221 A, using the graphic package software GRAPHICS-1000 from Hewlett-Packard. The codes have a great versatility and the representation of gamma spectra can ba done in a lineal, semi log, or log-log scale, as desired. The gamma ray spectra data are feed into the computer through magnetic tape or perfored paper tape. The different out-put options and complementary data are given in a conversational way through a terminal with T.V. displays. Among the options that can be selected by the user are the following: - smoothing the spectra - drawing the spectra point by point or continuous - out-put drawing an 1, 2, or 4 sheet with automatic division of the energy scale. - overlapping of selected spectra regions in Y scale ampliation with automatic print-out of the region limits and ampliation factor. - Printing spectra data and identifications of selected photo peaks. The codes can be employed with any computer using printing devices, HP-Graphics 1000 software compatible, but are easily modified for another printing software since their modular structure with Fortran IV written.

  7. Influence of Gamma-Ray Irradiation on Absorption and Fluorescent Spectra of Nd:YAG and Yb:YAG Laser Crystals

    International Nuclear Information System (INIS)

    We investigate the influence of gamma-ray irradiation on the absorption and fluorescent spectra of Nd3+:Y3A15O12 (Nd:YAG) and Yb3+:Y3A15O12 (Yb:YAG) crystals grown by the Czochralski method. Two additional absorption (AA) bands induced by gamma-ray irradiation appear at 255nm and 340 nm. The former is contributed due to Fe3+ impurity, the latter is due to Fe2+ ions and F-type colour centres. The intensity of the excitation and emission spectra as well as the fluorescent lifetime of Nd:YAG crystal decrease after the irradiation of 100Mrad gamma-ray In contrast, the same dose irradiation does not impair the fluorescent properties of Yb:YAG crystal. These results indicate that Yb:YAG crystal possesses the advantage over Nd:YAG crystal that has better reliability for applications in harsh radiant environment. (fundamental areas of phenomenology (including applications))

  8. Photoluminescence spectra of thin films containing CdSe/ZnS quantum dots irradiated by 532-nm laser radiation and gamma-rays

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Suresh C. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)], E-mail: sharma@uta.edu; Murphree, Jay; Chakraborty, Tonmoy [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)

    2008-11-15

    We have investigated temporal behavior of the photoluminescence (PL) spectra of thin films containing CdSe/ZnS quantum dots irradiated by 532 nm laser radiation and gamma-rays. Under {approx}100 W/cm{sup 2} laser radiation, the PL intensity (I{sub PL}) increases with irradiation time upto about 500 s and thereafter declines linearly. The wavelength of the PL emission ({lambda}{sub peak}) exhibits a blue-shift with exposure time. Upon simultaneous irradiation by 100 W/cm{sup 2} 532-nm laser, as well as 0.57 and 1.06 MeV gamma-rays, the temporal behaviors of both I{sub PL} and {lambda}{sub peak} are significantly different; I{sub PL} increases to a saturation level, and the magnitude of the blue-shift in {lambda}{sub peak} is reduced. We discuss possible mechanisms underlying these results.

  9. Development of a neural network approach to characterise 226Ra contamination at legacy sites using gamma-ray spectra taken from boreholes

    International Nuclear Information System (INIS)

    There are a large number of sites across the UK and the rest of the world that are known to be contaminated with 226Ra owing to historical industrial and military activities. At some sites, where there is a realistic risk of contact with the general public there is a demand for proficient risk assessments to be undertaken. One of the governing factors that influence such assessments is the geometric nature of contamination particularly if hazardous high activity point sources are present. Often this type of radioactive particle is encountered at depths beyond the capabilities of surface gamma-ray techniques and so intrusive borehole methods provide a more suitable approach. However, reliable spectral processing methods to investigate the properties of the waste for this type of measurement have yet to be developed since a number of issues must first be confronted including: representative calibration spectra, variations in background activity and counting uncertainty. Here a novel method is proposed to tackle this issue based upon the interrogation of characteristic Monte Carlo calibration spectra using a combination of Principal Component Analysis and Artificial Neural Networks. The technique demonstrated that it could reliably distinguish spectra that contained contributions from point sources from those of background or dissociated contamination (homogenously distributed). The potential of the method was demonstrated by interpretation of borehole spectra collected at the Dalgety Bay headland, Fife, Scotland. Predictions concurred with intrusive surveys despite the realisation of relatively large uncertainties on activity and depth estimates. To reduce this uncertainty, a larger background sample and better spatial coverage of cores were required, alongside a higher volume better resolution detector. - Highlights: • Land contaminated with radium is hazardous to human health. • Borehole gamma-ray spectra provide means of characterising contamination at depth

  10. The Prompt Gamma-Ray, Prompt Electron and Prompt X-Ray Spectra Associated with Fission Fragments of Specific Mass

    International Nuclear Information System (INIS)

    Well-defined prompt gamma-rays, prompt-conversion elections and prompt K-X-rays have been observed in coincidence with moving fission fragments of Cf252. In a few cases, the masses and charges of the nuclei emitting the gamma-rays and conversion electrons have been identified. The gamma-ray, prompt-electron and prompt X-ray energies as well as the two fission fragments energies were measured with high-resolution solid-state detectors. The masses of the fragments were deduced from their energies, and the nuclear charges were determined by measuring the K-X - ray energies associated with different masses. The magnitude and sign of the Doppler shift in gamma-ray energy allowed assignment of the gamma-ray lines to single members of fragment pairs. The Doppler shift also provides an independent measure of the fragment velocity and hence the fragment mass after neutron emission. The results of the X-ray measurements are consistent with the view that the majority of the prompt X-rays emitted during the spontaneous fission of Cf252 are the result of internal conversion during the de-excitation of low-energy collective states of the primary fission fragments. Apart from the specific results discussed above, the most important consequence of these experiments has been the demonstration that it is possible to study the properties of individual fission fragments, as identified by their characteristic radiations, rather than studying the properties of an average fission fragment with an average mass and charge. The consequences of this advance in the technique of studying fission fragments ate being explored. (author)

  11. Formation of very hard electron and gamma-ray spectra of flat spectrum radio quasar in fast-cooling regime

    Science.gov (United States)

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

    2016-04-01

    In external Compton scenario, we investigate the formation of the 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 the spectral index p ˜ 1.3 is formed below the minimum energy of injection electron 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 reasonably explain the very hard Fermi-LAT spectrum of the flat spectrum radio quasar 3C 279 during the extreme gamma-ray flare in 2013 December.

  12. Measurement of the Multi-T{bold e}V Gamma-Ray Flare Spectra of Markarian 421 and Markarian 501

    Energy Technology Data Exchange (ETDEWEB)

    Krennrich, F. [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011-3160 (United States); Biller, S.D. [Department of Physics, Oxford University, Oxford, England (United Kingdom); Bond, I.H. [Department of Physics, University of Leeds, Leeds, LS2 9JT, England (United Kingdom); Boyle, P.J. [Experimental Physics Department, University College, Belfield, Dublin 4 (Ireland); Bradbury, S.M. [Department of Physics, University of Leeds, Leeds, LS2 9JT, England (United Kingdom); Breslin, A.C. [Experimental Physics Department, University College, Belfield, Dublin 4 (Ireland); Buckley, J.H. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Burdett, A.M. [Department of Physics, University of Leeds, Leeds, LS2 9JT, England (United Kingdom); Gordo, J.B. [Experimental Physics Department, University College, Belfield, Dublin 4 (Ireland); Carter-Lewis, D.A.; Catanese, M. [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011-3160 (United States); Cawley, M.F. [Physics Department, National University of Ireland, Maynooth (Ireland); Fegan, D.J. [Experimental Physics Department, University College, Belfield, Dublin 4 (Ireland); Finley, J.P.; Gaidos, J.A.; Hall, T. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Hillas, A.M. [Department of Physics, University of Leeds, Leeds, LS2 9JT, England (United Kingdom); Lamb, R.C. [Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States); Lessard, R.W. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Masterson, C. [Experimental Physics Department, University College, Belfield, Dublin 4 (Ireland); McEnery, J.E. [Department of Physics, University of Utah, Salt Lake City, UT 84112 (United States); Mohanty, G. [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011-3160 (United States); Moriarty, P. and others.

    1999-01-01

    The energy spectrum of Markarian 421 in flaring states has been measured from 0.3 to 10 TeV using both small and large zenith angle observations with the Whipple Observatory 10 m imaging telescope. The large zenith angle technique is useful for extending spectra to high energies, and the extraction of spectra with this technique is discussed. The resulting spectrum of Markarian 421 is fitted reasonably well by a simple power law: J(E)=E{sup {minus}2.54{plus_minus}0.03{plus_minus}0.10} photons m{sup {minus}1} s{sup {minus}1} TeV{sup {minus}1}, where the first set of errors is statistical and the second set is systematic. This is in contrast to our recently reported spectrum of Markarian 501, which over a similar energy range has substantial curvature. The differences in TeV energy spectra of gamma-ray blazars reflect both the physics of the gamma-ray production mechanism and possibly differential absorption effects at the source or in the intergalactic medium. Since Markarian 421 and Markarian 501 have almost the same redshift (0.031 and 0.033, respectively), the difference in their energy spectra must be intrinsic to the sources and not due to intergalactic absorption, assuming the intergalactic infrared background is uniform. {copyright} {ital {copyright} 1999.} {ital The American Astronomical Society}

  13. A search for double-electron capture of {sup 74}Se to excited levels using coincidence/anticoincidence gamma-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ješkovský, M. [Comenius University, Faculty of Mathematics, Physics and Informatics, Department of Nuclear Physics and Biophysics, 84248 Bratislava (Slovakia); Frekers, D. [Institut für Kernphysik, Westfälische Wilhelms Universität, Münster (Germany); Kováčik, A. [Comenius University, Faculty of Mathematics, Physics and Informatics, Department of Nuclear Physics and Biophysics, 84248 Bratislava (Slovakia); Povinec, P.P., E-mail: povinec@fmph.uniba.sk [Comenius University, Faculty of Mathematics, Physics and Informatics, Department of Nuclear Physics and Biophysics, 84248 Bratislava (Slovakia); Puppe, P. [Institut für Kernphysik, Westfälische Wilhelms Universität, Münster (Germany); Staníček, J.; Sýkora, I. [Comenius University, Faculty of Mathematics, Physics and Informatics, Department of Nuclear Physics and Biophysics, 84248 Bratislava (Slovakia); Šimkovic, F. [Comenius University, Faculty of Mathematics, Physics and Informatics, Department of Nuclear Physics and Biophysics, 84248 Bratislava (Slovakia); Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation); Thies, J.H. [Institut für Kernphysik, Westfälische Wilhelms Universität, Münster (Germany)

    2015-09-21

    Evaluation of single, coincidence and anticoincidence gamma-ray spectrometry methods has been carried out with the aim to search for double-electron capture of {sup 74}Se to excited states. This process is unique, because there is probability for transition to the 2{sup +} excited state in {sup 74}Ge (1204 keV), and de-excitation through two gamma-quanta cascade with energies of 595.9 keV and 608.4 keV. Long-term measurements with an anticosmic shielded HPGe (high purity Ge) spectrometer and a coincidence HPGe–NaI(Tl) spectrometer did not show any evidence for the double-electron capture in {sup 74}Se. The best limit for the half-life of the double electron capture in {sup 74}Se (both for the neutrinoless and two neutrino processes) was estimated to be >1.5×10{sup 19} yr.

  14. A search for double-electron capture of 74Se to excited levels using coincidence/anticoincidence gamma-ray spectrometry

    International Nuclear Information System (INIS)

    Evaluation of single, coincidence and anticoincidence gamma-ray spectrometry methods has been carried out with the aim to search for double-electron capture of 74Se to excited states. This process is unique, because there is probability for transition to the 2+ excited state in 74Ge (1204 keV), and de-excitation through two gamma-quanta cascade with energies of 595.9 keV and 608.4 keV. Long-term measurements with an anticosmic shielded HPGe (high purity Ge) spectrometer and a coincidence HPGe–NaI(Tl) spectrometer did not show any evidence for the double-electron capture in 74Se. The best limit for the half-life of the double electron capture in 74Se (both for the neutrinoless and two neutrino processes) was estimated to be >1.5×1019 yr

  15. Intercomparison of gamma ray analysis software packages

    International Nuclear Information System (INIS)

    The IAEA undertook an intercomparison exercise to review available software for gamma ray spectra analysis. This document describes the methods used in the intercomparison exercise, characterizes the software packages reviewed and presents the results obtained. Only direct results are given without any recommendation for a particular software or method for gamma ray spectra analysis

  16. Monte Carlo simulation of prompt gamma-ray spectra from depleted uranium under D-T neutron irradiation and electron recoil spectra in a liquid scintillator detector

    CERN Document Server

    Qin, Jianguo; Liu, Rong; Zhu, Tonghua; Zhang, Xinwei; Ye, Bangjiao

    2015-01-01

    To overcome the problem of inefficient computing time and unreliable results in MCNP5 calculation, a two-step method is adopted to calculate the energy deposition of prompt gamma-rays in detectors for depleted uranium spherical shells under D-T neutrons irradiation. In the first step, the gamma-ray spectrum for energy below 7 MeV is calculated by MCNP5 code; secondly, the electron recoil spectrum in a BC501A liquid scintillator detector is simulated based on EGSnrc Monte Carlo Code with the gamma-ray spectrum from the first step as input. The comparison of calculated results with experimental ones shows that the simulations agree well with experiment in the energy region 0.4-3 MeV for the prompt gamma-ray spectrum and below 4 MeVee for the electron recoil spectrum. The reliability of the two-step method in this work is validated.

  17. Prompt and Delayed Gamma-Rays from Fission

    International Nuclear Information System (INIS)

    The following data about gamma-rays from fission are reported and discussed; Total prompt gamma-ray spectrum, and average number and energy of gamma-rays; X-rays in prompt fission, and excitation of X-rays in matter; gamma-ray spectra as a function of the mass ratio in fission, gamma-lines in those spectra, and Doppler effect-, anisotropy in gamma-emission relative to the direction of fragments; average gamma-energy and gamma-spectra as a function of mass of the fission products; delayed gamma-rays; delayed gamma-rays as a function of fission product mass. (author)

  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.

    Science.gov (United States)

    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. PMID:11542904

  19. Lunar Elemental Abundances from Gamma-Ray and Neutron Measurements

    Science.gov (United States)

    Reedy, R. C.; Vaniman, D. T.

    1999-01-01

    thermal energies at similar rates. The main exception is when neutrons scatter from H, in which case neutrons can be rapidly thermalized. The cross sections for the absorption of thermal neutrons can vary widely among elements, with major elements like Ti and Fe having high-capture cross sections. Some trace elements, such as Sm and Gd, have such large neutron-absorption cross sections that, despite their low abundances, can absorb significant amounts of thermal neutrons in the Moon. Because the processes affecting neutrons are complicated, good modeling is needed to properly extract elemental information from measured neutron fluxes. The LAHET Code System (LCS) can be use to calculate neutron fluxes from GCR interactions in the Moon. Lunar Gamma-Ray Spectroscopy: The main sources of planetary gamma-rays are the decay of the naturally occurring radioactive isotopes of K, Th, and U and the interactions of GCRs with atomic nuclei in the planet's surface. Most "cosmogenic" gamma-rays are produced by fast and thermal neutrons made in the planet's surface by GCRs, and their production rates can vary with time. Over 300 gamma-ray lines have been identified that can be emitted from planetary surfaces by a variety of production mechanisms. There exist nuclear databases that can be used to identify and quantify other gamma-ray lines. Use will be made of gamma-rays from major elements, particularly those from Si and O, that have not been routinely used in the past. The fluxes of gamma-rays from a given element can vary depending on many factors besides the concentration of that element. For example, the fluxes of neutron-capture gamma-rays in the planetary region of interest depend on (1) the total cross section for elements to absorb thermalized neutrons and (2) the H content of the top meter of the surface. The fluxes of the fast neutrons that induce inelastic-scattering and other nonelastic-scattering reactions can vary with the composition of the surface There are several key

  20. An evaluation of commercial IBM PC software for the analysis of low-level environmental gamma-ray spectra

    International Nuclear Information System (INIS)

    A comparative evaluation of seven commercial gamma-ray analysis software packages, written for the IBM PC, was performed. Four software packages were supplied by US nuclear instrument manufacturers. A fifth package was supplied by a French nuclear instrument manufacturer. Two additional packages were supplied by software companies in the United States and Finland. For this evaluation emphasis was given to accuracy, peak detection, noise and phantom peak rejection for low level environmental sample analysis. System requirements, nuclide identification, ease of operation and other optional utilities were also considered. Of the seven software packages evaluated, two contained the most desirable features required for environmental applications. 9 tabs

  1. Monte Carlo based method for conversion of in-situ gamma ray spectra obtained with a portable Ge detector to an incident photon flux energy distribution.

    Science.gov (United States)

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

    1998-02-01

    A Monte Carlo based method for the conversion of an in-situ gamma-ray spectrum obtained with a portable Ge detector to photon flux energy distribution is proposed. The spectrum is first stripped of the partial absorption and cosmic-ray events leaving only the events corresponding to the full absorption of a gamma ray. Applying to the resulting spectrum the full absorption efficiency curve of the detector determined by calibrated point sources and Monte Carlo simulations, the photon flux energy distribution is deduced. The events corresponding to partial absorption in the detector are determined by Monte Carlo simulations for different incident photon energies and angles using the CERN's GEANT library. Using the detector's characteristics given by the manufacturer as input it is impossible to reproduce experimental spectra obtained with point sources. A transition zone of increasing charge collection efficiency has to be introduced in the simulation geometry, after the inactive Ge layer, in order to obtain good agreement between the simulated and experimental spectra. The functional form of the charge collection efficiency is deduced from a diffusion model. PMID:9450590

  2. Measurement and Analysis of the Neutron and Gamma-Ray Flux Spectra in a Neutronics Mock-Up of the HCPB Test Blanket Module

    International Nuclear Information System (INIS)

    The nuclear parameters of a breeding blanket, such as tritium production rate, nuclear heating, activation and dose rate, are calculated by integral folding of an energy dependent cross section (or coefficient) with the neutron (or gamma-ray) flux energy spectra. The uncertainties of the designed parameters are determined by the uncertainties of both the cross section data and the flux spectra obtained by transport calculations. Also the analysis of possible discrepancies between measured and calculated integral nuclear parameter represents a two-step procedure. First, the energy region and the amount of flux discrepancies has to be found out and second, the cross section data have to be checked. To this end, neutron and gamma-ray flux spectra in a mock-up of the EU Helium-Cooled Pebble Bed (HCPB) breeder Test Blanket Module (TBM), irradiated with 14 MeV neutrons, were measured and analysed by means of Monte Carlo transport calculations. The flux spectra were determined for the energy ranges that are relevant for the most important nuclear parameters of the TBM, which are the tritium production rate and the shielding capability. The fast neutron flux which determines the tritium production on 7Li and dominates the shield design was measured by the pulse-height distribution obtained from an organic liquid scintillation detector. Simultaneously, the gamma-ray flux spectra were measured. The neutron flux at lower energies, down to thermal, which determines the tritium production on 6Li, was measured with time-of-arrival spectroscopy. For this purpose, the TUD neutron generator was operated in pulsed mode (pulse width 10 μs, frequency 1 kHz) and the neutrons arriving at a 3He proportional counter in the mock-up were recorded as a function of time after the source neutron pulse. The spectral distributions for the two positions in the mock-up, where measurements were carried out, were calculated with the Monte Carlo code MCNP, version 5, and nuclear data from the

  3. Monte Carlo simulation of prompt gamma-ray spectra from depleted uranium under D-T neutron irradiation and electron recoil spectra in a liquid scintillator detector

    OpenAIRE

    Qin, Jianguo; Lai, Caifeng; Liu, Rong; Zhu, Tonghua; Zhang, Xinwei; Ye, Bangjiao

    2015-01-01

    To overcome the problem of inefficient computing time and unreliable results in MCNP5 calculation, a two-step method is adopted to calculate the energy deposition of prompt gamma-rays in detectors for depleted uranium spherical shells under D-T neutrons irradiation. In the first step, the gamma-ray spectrum for energy below 7 MeV is calculated by MCNP5 code; secondly, the electron recoil spectrum in a BC501A liquid scintillator detector is simulated based on EGSnrc Monte Carlo Code with the g...

  4. DS02 fluence spectra for neutrons and gamma rays at Hiroshima and Nagasaki with fluence-to-kerma coefficients and transmission factors for sample measurements.

    Science.gov (United States)

    Egbert, Stephen D; Kerr, George D; Cullings, Harry M

    2007-11-01

    Fluence spectra at several ground distances in Hiroshima and Nagasaki are provided along with associated fluence-to-kerma coefficients from the Dosimetry System 2002 (DS02). Also included are transmission factors for calculating expected responses of in situ sample measurements of neutron activation products such as (32)P,(36)Cl,(39)Ar,(41)Ca, (60)Co,(63)Ni,(152)Eu, and (154)Eu. The free-in-air (FIA) fluences calculated in 2002 are available for 240 angles, 69 energy groups, 101 ground distances, 5 heights, 4 radiation source components, 2 cities. The DS02 code uses these fluences partitioned to a prompt and delayed portion, collapsed to 58 energy groups and restricted to 97 ground distances. This is because the fluence spectra were required to be in the same format that was used in the older Dosimetry System 1986 (DS86) computer code, of which the DS02 computer code is a modification. The 2002 calculation fluences and the collapsed DS02 code fluences are presented and briefly discussed. A report on DS02, which is available on the website at the Radiation Effects Research Foundation, provides tables and figures of the A-bomb neutron and gamma-ray output used as the sources in the 2002 radiation transport calculations. While figures illustrating the fluence spectra at several ground ranges are presented in the DS02 Report, it does not include any tables of the calculated fluence spectra in the DS02 report. This paper provides, at several standard distances from the hypocenter, the numerical information which is required to translate the FIA neutron fluences given in DS02 to a neutron activation measurement or neutron and gamma-ray soft-tissue dose. PMID:17643260

  5. $\\gamma$-ray energy spectra and multiplicities from the neutron-induced fission of $^{235}$U using STEFF

    CERN Multimedia

    An experiment is proposed to use the STEFF spectrometer at n_TOF to study fragment $\\gamma$-correlations following the neutron-induced fission of $^{235}$U. The STEFF array of 12 NaI detectors will allow measurements of the single $\\gamma$-energy, the $\\gamma$ multiplicity, and the summed $\\gamma$energy distributions as a function of the mass and charge split, and deduced excitation energy in the fission event. These data will be used to study the origin of fission-fragment angular momenta, examining angular distribution eects as a function of incident neutron energy. The principal application of this work is in meeting the NEA high-priority request for improved $\\gamma$ray data from $^{235}$U(n; F). To improve the detection rate and expand the range of detection angles, STEFF will be modied to include two new ssion-fragment detectors each at 45 to the beam direction.

  6. Gamma-ray methods

    International Nuclear Information System (INIS)

    Bulk analysis techniques using gamma radiation are described. The methods include gamma-ray induced reactions, selective gamma-ray scattering and methods which rely on natural radioactivity. The gamma-ray resonance scattering technique can be used for the determination of copper and nickel in bulk samples and drill cores. The application of gamma-gamma methods to iron ore analysis is outlined

  7. Presentation of a semiempirical method for the calculation of doses due to neutrons and capture gamma rays inside high energy accelerators rooms

    International Nuclear Information System (INIS)

    Full text: Medical electron accelerators operating above 10 MeV produce radiation beams that are contaminated with neutrons. Therefore, shielding design for high energy accelerator rooms must consider the neutron component of the radiation field. In this paper a semiempirical method is presented to calculate doses due to neutrons and capture gamma rays inside the room and the maze. The calculation method is based on the knowledge of the neutron yield Q (neutrons/Gy of photons at isocenter) and the average energy of the primary beam of neutrons Eo (MeV). The method constitutes an appropriate tool for shielding facilities evaluation. The accuracy of the method has been contrasted with data obtained from the literature and an excellent correlation among the calculations and the measured values was achieved. In addition, the method has been used in the verification of experimental data corresponding to a 15 MeV linear accelerator installed in the country with similar results. (author)

  8. First tests of the applicability of $\\gamma$-ray imaging for background discrimination in time-of-flight neutron capture measurements

    CERN Document Server

    Magán, D L Pérez; Domingo-Pardo, C; Agramunt-Ros, J; Albiol, F; Casanovas, A; González, A; Guerrero, C; Lerendegui-Marco, J; Tarifeño-Saldivia, A

    2015-01-01

    In this work we explore for the first time the applicability of using $\\gamma$-ray imaging in neutron capture measurements to identify and suppress spatially localized background. For this aim, a pinhole gamma camera is assembled, tested and characterized in terms of energy and spatial performance. It consists of a monolithic CeBr$_3$ scintillating crystal coupled to a position-sensitive photomultiplier and readout through an integrated circuit AMIC2GR. The pinhole collimator is a massive carven block of lead. A series of dedicated measurements with calibrated sources and with a neutron beam incident on a $^{197}$Au sample have been carried out at n\\_TOF, achieving an enhancement of a factor of 2 in the signal-to-background ratio when selecting only those events coming from the direction of the sample.

  9. Measurements of neutron-induced capture and fission reactions on $^{235}$ U: cross sections and ${\\alpha}$ ratios, photon strength functions and prompt ${\\gamma}$-ray from fission

    CERN Multimedia

    We propose to measure the neutron-induced capture cross section of the fissile isotope $^{235}$U using a fission tagging set-up. This new set-up has been tested successfully in 2010 and combines the n_TOF 4${\\pi}$ Total Absorption Calorimeter (TAC) with MicroMegas (MGAS) fission detectors. It has been proven that such a combination of detectors allows distinguishing with very good reliability the electromagnetic cascades from the capture reactions from dominant ${\\gamma}$-ray background coming from the fission reactions. The accurate discrimination of the fission background is the main challenge in the neutron capture cross section measurements of fissile isotopes. The main results from the measurement will be the associated capture cross section and ${\\alpha}$ ratio in the resolved (0.3-2250 eV) and unresolved (2.25-30 keV) resonance regions. According to the international benchmarks and as it is mentioned in the NEA High Priority Request List (HPRL), the 235U(n,${\\gamma}$) cross section is of utmost impo...

  10. Gamma-ray astronomy

    OpenAIRE

    Pohl, Martin

    2001-01-01

    This paper summarizes recents results in gamma-ray astronomy, most of which were derived with data from ground-based gamma-ray detectors. Many of the contributions presented at this conference involve multiwavelength studies which combine ground-based gamma-ray measurements with optical data or space-based X-ray and gamma-ray measurements. Besides measurements of the diffuse emission from the Galaxy, observations of blazars, gamma-ray bursts, and supernova remnants this paper also covers theo...

  11. Neutron photoproduction in sup 2 sup 3 sup 2 Th and sup 2 sup 3 sup 8 U using thermal neutron capture gamma-rays in the energy range 5.61 to 10.83 MeV

    CERN Document Server

    Goncalez, O L

    1998-01-01

    Neutron photoproduction studies for sup 2 sup 3 sup 2 Th and sup 2 sup 3 sup 8 U were carried out from 5.6 to 10.8 MeV, using neutron capture gamma-rays with high resolution in energy (3 to 21 eV), produced by 30 target materials, placed inside a tangential beam port, near the core of the IPEN/CNEN-SP IEA-R1 2 MW research reactor. The samples (17.76 g of U sub 3 sub O sub 8 depleted to 0.349% in sup 2 sup 3 sup 5 U and 19.93 g of natural Th O sub 2) have been irradiated inside a 4 pi geometry neutron detector system sup L ong Counter sup , 520.5 cm away from the capture target. The capture gamma-ray flux was determined by means of the analysis of the gamma spectrum obtained by using a Ge(Li) solid-state detector (E G and G Ortec, 25 cm sup 3 , 5%), previously calibrated with capture gamma-rays from a standard target of Nitrogen (Melamine). The neutron photoproduction cross section has been measured for each target capture gamma-ray spectrum (compound cross section). A methodology for unfolding the set of expe...

  12. Natural background gamma-ray spectrum. List of gamma-rays ordered in energy from natural radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Ichimiya, Tsutomu [Japan Radioisotope Association, Tokyo (Japan); Narita, Tsutomu; Kitao, Kensuke

    1998-03-01

    A quick index to {gamma}-rays and X-rays from natural radionuclides is presented. In the list, {gamma}-rays are arranged in order of increasing energy. The list also contains {gamma}-rays from radioactive nuclides produced in a germanium detector and its surrounding materials by interaction with cosmic neutrons, as well as direct {gamma}-rays from interaction with the neutrons. Artificial radioactive nuclides emitting {gamma}-rays with same or near energy value as that of the natural {gamma}-rays and X-rays are also listed. In appendix, {gamma}-ray spectra from a rock, uranium ore, thorium, monazite and uraninite and also background spectra obtained with germanium detectors placed in iron or lead shield have been given. The list is designed for use in {gamma}-ray spectroscopy under the conditions of highly natural background, such as in-situ environmental radiation monitoring or low-level activity measurements, with a germanium detector. (author)

  13. Gamma ray interaction, crystallization and infrared absorption spectra of some glasses and glass-ceramics from the system Li2O.B2O3.Al2O3

    International Nuclear Information System (INIS)

    The infrared absorption spectra of some selected ternary glasses and their glass-ceramic derivatives from the system Li2OB2O3Al2O3 have been measured in the spectral range 200-4000 cm-1 before and after successive gamma rays irradiation. Vibrational and crystallization techniques are employed to investigate the structure and phases which are found in this system by controlled crystallization. The role of Al2O3 in the structure and the crystallization behaviour of the system has been discussed. The effect of gamma rays on the surface of the glasses and glass-ceramics as revealed from infrared spectroscopy is discussed. (author)

  14. Neutrino and gamma-ray signatures of supernova explosions

    Science.gov (United States)

    Lu, Yu

    2007-08-01

    A supernova occurs when the core of a massive star collapses into a compact neutron star. Nearly all the gravitational binding energy of the neutron star is emitted in neutrinos. This is approximately 100 times larger than the explosion energy as measured by the total energy of the ejecta. A prevalent paradigm is that a fraction of the neutrino energy is absorbed by the material above the neutron star, thereby delivering the explosion. We test this neutrino driven supernova mechanism by analyzing the signal induced by supernova electron antineutrinos in terrestrial detectors such as SuperKamiokande. We perform detailed Monte Carlo simulations of such signals and identify the potential signatures of this mechanism by comparing the event rates and energy spectra before and after explosion. Before the neutrinos reach terrestrial detectors, a fraction of them interact with protons and nuclei in the supernova envelope. Some of these interactions result in gamma-ray emission. The gamma-rays produced in the outmost layer escape and may be detected. We calculate the time evolution for the fluxes of gamma-rays produced by neutron capture on protons and positron annihilation following the absorption of electron antineutrinos on protons. Because these gamma-rays are produced before the supernova shock arrives at the envelope, their detection can help identify the supernova before it is seen optically. In addition, they may provide a useful probe of the conditions in the surface layer of the supernova progenitor.

  15. On the gamma-ray spectra radiated by protons accelerated in SNR shocks near molecular clouds: The case of SNR RX J1713.7-3946

    CERN Document Server

    Malkov, M A; Sagdeev, R Z

    2005-01-01

    Cosmic rays (CRs) are thought to be accelerated in SNRs. The most favorable situation for proving that the main, hadronic CR component is accelerated there is when CRs interact with dense gases, such as molecular clouds (MC) which surround the SN shock. Here, a new mechanism of spectrum formation in partially ionized gases near SNRs is proposed. Using an analytic model of nonlinear diffusive shock acceleration, we calculate the spectra of protons and estimate the resulting $\\gamma$-ray emission occurring when the SNR shock approaches a MC. We show that the spectrum develops a break in the TeV range and that its GeV component is suppressed. These modifications to the standard theory occur because of the proximity of the partially ionized MC-gas and because of the physics of particle and Alfven wave propagation inside the gas. Possible applications of the new spectra to the recent CANGAROO and HESS observations of the SNR RX J1713.7-3946 are discussed.

  16. Gamma-ray sources

    International Nuclear Information System (INIS)

    Results are presented from an analysis of the celestial gamma-ray fine-scale structure based on over half of the data which may ultimately be available from the COS-B satellite. A catalogue consisting of 25 gamma-ray sources measured at energies above 100 MeV is presented. (Auth.)

  17. Development of a neural network approach to characterise (226)Ra contamination at legacy sites using gamma-ray spectra taken from boreholes.

    Science.gov (United States)

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

    2015-02-01

    There are a large number of sites across the UK and the rest of the world that are known to be contaminated with (226)Ra owing to historical industrial and military activities. At some sites, where there is a realistic risk of contact with the general public there is a demand for proficient risk assessments to be undertaken. One of the governing factors that influence such assessments is the geometric nature of contamination particularly if hazardous high activity point sources are present. Often this type of radioactive particle is encountered at depths beyond the capabilities of surface gamma-ray techniques and so intrusive borehole methods provide a more suitable approach. However, reliable spectral processing methods to investigate the properties of the waste for this type of measurement have yet to be developed since a number of issues must first be confronted including: representative calibration spectra, variations in background activity and counting uncertainty. Here a novel method is proposed to tackle this issue based upon the interrogation of characteristic Monte Carlo calibration spectra using a combination of Principal Component Analysis and Artificial Neural Networks. The technique demonstrated that it could reliably distinguish spectra that contained contributions from point sources from those of background or dissociated contamination (homogenously distributed). The potential of the method was demonstrated by interpretation of borehole spectra collected at the Dalgety Bay headland, Fife, Scotland. Predictions concurred with intrusive surveys despite the realisation of relatively large uncertainties on activity and depth estimates. To reduce this uncertainty, a larger background sample and better spatial coverage of cores were required, alongside a higher volume better resolution detector. PMID:25461525

  18. Cascaded Gamma Rays as a Probe of Cosmic Rays

    Science.gov (United States)

    Murase, Kohta

    2014-06-01

    Very-high-energy (VHE) and ultra-high-energy (UHE) gamma rays from extragalactic sources experience electromagnetic cascades during their propagation in intergalactic space. Recent gamma-ray data on TeV blazars and the diffuse gamma-ray background may have hints of the cascade emission, which are especially interesting if it comes from UHE cosmic rays. I show that cosmic-ray-induced cascades can be discriminated from gamma-ray-induced cascades with detailed gamma-ray spectra. I also discuss roles of structured magnetic fields, which suppress inverse-Compton pair halos/echoes but lead to guaranteed signals - synchrotron pair halos/echoes.

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

    Science.gov (United States)

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

    2016-04-01

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

  20. Photofission cross sections of U-233 and Pu-239 near threshold induced by gamma-rays from thermal neutron capture

    International Nuclear Information System (INIS)

    The photofission cross sections of U-233 and PU-239 have been studied using monochromatic photons produced by thermal neutron capture in several materials placed in a radial beam hole of the IEA-R1, 2 MW pool type research reactor, in the energy interval from 5.43 MeV to 9.72 MeV. The gamma flux incident on the samples were measured using a (3X3) inch. NaI(Tl) crystal. The photofission fragments were detected in MAKROFOL-KG (solid state nuclear track detector) etched 30 min. in a KOH (35%wt) solution at 600C. The efficiency of the detector was obtained using a Californium-252 calibrated source and its value was (0.4323 ± 3%). The tracks were counted by means of an automatic spark counting. Analyzing the photofission data we have observed similarities between the cross sections obtained for the two samples in comparison with other authors. A structure was also observed in the U-233 cross section near the energy of 7.23 MeW. Acoording to the liquid drop model the height of the simple fission barrier were determined: (5.6 ± 0.2) MeV and (5.7 ± 0.2) MeV for U-233 and Pu-239 respectively. The relative fissionability of the samples to U-238 were also determined in each excitation energy and showed to be energy independent: (2.12 +-0.25) for U-233, and (3.32+-0.41) for Pu-239. (author)

  1. Gamma-ray emission from globular clusters

    CERN Document Server

    Tam, P H Thomas; Hui, C Y

    2012-01-01

    Over the last few years, the fruitful data provided by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope has revolutionized our understanding of high-energy processes in globular clusters, particularly those involving compact objects like millisecond pulsars (MSPs). Gamma-ray emission between 100 MeV to 10 GeV has been detected from more than a dozen globular clusters in our Galaxy, most notably 47 Tucanae and Terzan 5. Based on a sample of known gamma-ray globular clusters, empirical relations between the gamma-ray luminosity and properties of globular clusters such as stellar encounter rate, metallicity, as well as optical and infrared photon energy density in the cluster, have been derived. The gamma-ray spectra are generally described by a power law with a cut-off at a few GeV. Together with the detection of pulsed gamma-rays from a millisecond pulsar in a globular cluster, such spectral signature gives support that gamma-rays from globular clusters are collective curvature emission from...

  2. Gamma-ray production cross sections for MeV neutrons

    International Nuclear Information System (INIS)

    Gamma-ray production cross section and spectra for 1- to 20-MeV neutrons were theoretically obtained, which were requested for heating calculations, for shielding design calculations, and for material damage estimates. Calculations were carried out for Al, Si, Ca, Fe, Ni, Cu, Nb, Ta, Au, and Pb, using a spin-dependent evaporation model without the parity conservation and including the dipole and quardupole gamma-ray transitions. The results were compared with the experimental data measured in ORNL to confirm the availability of this model in applications. In addition, the effects on the gamma-ray production cross section of the optical potential, level density, yrast level, and radiation width were investigated in detail. The conclusions are: 1) the use of the optical potential which gives the correct total reaction cross section is essential to gamma-ray production calculations, 2) the gamma-ray production cross section is not so sensitive to the choice of level density parameters, 3) the inclusion of yrast levels is necessary in dealing with the competition of the neutron and gamma-ray emissions from highly excited states, and 4) the Brink-Axel type's radiation width is unsuitable to be applied to radiative capture processes. (author)

  3. Photonuclear reactions of U-233 and Pu-239 near threshold induced by thermal neutron capture gamma rays

    International Nuclear Information System (INIS)

    The photonuclear cross sections of U-293 and Pu-239 have been studied by using monochromatic and discrete photons, in the energy interval from 5.49 to 9.72 MeV, produced by thermal neutron capture. The gamma fluxes incident on the samples were measured using a ( 3 x 3 )'' NaI (TI) crystal. The photofission fragments were detected in Makrofol-Kg (SSNTD). A possible structure was observed in the U-233 cross sections, near 7.23 MeV. The relative fissionability of the nuclides was determined at each excitation energy and shown to be energy independent: ( 2.12 ± 0.25) for U-233 and ( 3.32 ± 0.41 ) for Pu-239. The angular distribution of photofission fragments of Pu-239 were measured at two mean excitation energies of 5.43 and 7.35 MeV. An anisotropic distribution of ( 12.2 ± 3.6 ) % was observed at 5.43 MeV. The total neutron cross sections were measured by using a long counter detector. The photoneutron cross sections were calculated by using energy dependent neutron multiplicities values, γ(E), obtained in the literature. The competition Γn/γf was also determined at each excitation energy, and shown to be energy independent: ( 0.54 ± 0.05 ) for U-233 and ( 0.44 ± 0.05 ) for Pu-239, and were correlated to the parameters Z sup(2)/A, ( Ef'-Bn'), A. According to the FUJIMOTO-YAMAGUCHI and CONSTANT NUCLEAR TEMPERATURE models, the nuclear temperatures were calculated. The total photoabsorption cross sections were also calculated as a sum of the photofission and photoneutron cross sections at each energy excitation. From these results the competition Γf/ΓA, called fission probability Pf, were obtained: ( 0.66 ± 0.02) for U-233 and ( 0.70 ± 0.02 ) for Pu-239. (author)

  4. Gamma-ray Astronomy

    CERN Document Server

    Hinton, Jim

    2007-01-01

    The relevance of gamma-ray astronomy to the search for the origin of the galactic and, to a lesser extent, the ultra-high-energy cosmic rays has long been recognised. The current renaissance in the TeV gamma-ray field has resulted in a wealth of new data on galactic and extragalactic particle accelerators, and almost all the new results in this field were presented at the recent International Cosmic Ray Conference (ICRC). Here I summarise the 175 papers submitted on the topic of gamma-ray astronomy to the 30th ICRC in Merida, Mexico in July 2007.

  5. Gamma-ray astronomy

    Science.gov (United States)

    Ramaty, R.; Lingenfelter, R. E.

    1982-01-01

    Cosmic gamma rays, the physical processes responsible for their production and the astrophysical sites from which they were seen are reported. The bulk of the observed gamma ray emission is in the photon energy range from about 0.1 MeV to 1 GeV, where observations are carried out above the atmosphere. There are also, however, gamma ray observations at higher energies obtained by detecting the Cerenkov light produced by the high energy photons in the atmosphere. Gamma ray emission was observed from sources as close as the Sun and the Moon and as distant as the quasar 3C273, as well as from various other galactic and extragalactic sites. The radiation processes also range from the well understood, e.g. energetic particle interactions with matter, to the still incompletely researched, such as radiation transfer in optically thick electron positron plasmas in intense neutron star magnetic fields.

  6. Gamma ray camera

    International Nuclear Information System (INIS)

    An improved Anger-type gamma ray camera utilizes a proximity-type image intensifier tube. It has a greater capability for distinguishing between incident and scattered radiation, and greater spatial resolution capabilities

  7. Precision measurements of gamma-ray intensities

    International Nuclear Information System (INIS)

    To determine relative intensities of gamma rays in the region of 280 to 2750 keV, Ge(Li) detectors were calibrated with standard sources and cascade gamma-ray sources. Decay rates of the standard sources were determined by means of the 4πβ-γ or 4πX-γ coincidence method. Experimental conditions were improved and spectra were carefully analyzed. Relative gamma-ray intensities of 56Co, 88Y, sup(110m)Ag, 133Ba, 134Cs, 152Eu, 154Eu, 192Ir and 207Bi were determined within the accuracy of about 0.5% for strong gamma rays. Intensities per decays were obtained from the relative intensities for most of the nuclides. (author)

  8. New parameterization of the E1 gamma-ray strength function

    International Nuclear Information System (INIS)

    The giant dipole (GD) parameters of peak energy, width, and cross section were satisfactorily correlated for elements from V to Bi, assuming two overlapping peaks with a separation dependent on deformation. The energy dependence of the GD resonance is assumed to have a Breit-Wigner form, but with an energy-dependent width. The resulting gamma-ray strength function model is used to predict neutron capture cross sections and gamma-ray spectra for isotopes of Ta, Os, and Au. 23 references

  9. Gamma ray optics

    Energy Technology Data Exchange (ETDEWEB)

    Jentschel, M.; Guenther, M. M.; Habs, D.; Thirolf, P. G. [Institut Laue-Langevin, F38042 Grenoble (France); Max-Planck-Institut fuer Quantenoptik, D-85748 Garching (Germany); Max-Planck-Institut fuer Quantenoptik, D-85748 Garching, Germany and Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany); Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany)

    2012-07-09

    Via refractive or diffractive scattering one can shape {gamma} ray beams in terms of beam divergence, spot size and monochromaticity. These concepts might be particular important in combination with future highly brilliant gamma ray sources and might push the sensibility of planned experiments by several orders of magnitude. We will demonstrate the experimental feasibility of gamma ray monochromatization on a ppm level and the creation of a gamma ray beam with nanoradian divergence. The results are obtained using the inpile target position of the High Flux Reactor of the ILL Grenoble and the crystal spectrometer GAMS. Since the refractive index is believed to vanish to zero with 1/E{sup 2}, the concept of refractive optics has never been considered for gamma rays. The combination of refractive optics with monochromator crystals is proposed to be a promising design. Using the crystal spectrometer GAMS, we have measured for the first time the refractive index at energies in the energy range of 180 - 2000 keV. The results indicate a deviation from simple 1/E{sup 2} extrapolation of X-ray results towards higher energies. A first interpretation of these new results will be presented. We will discuss the consequences of these results on the construction of refractive optics such as lenses or refracting prisms for gamma rays and their combination with single crystal monochromators.

  10. Gamma-ray spectrum measurement in Japan research reactor no. 3 using a portable Ge(Li) spectrometer

    International Nuclear Information System (INIS)

    A portable Ge(Li) gamma-ray spectrometer having 2.6% peak detection efficiency and 3.5 keV energy resolution was made using a 7.5 liter liquid nitrogen dewar. The total weight of the spectrometer including the detector, cryostat, preamplifier, high voltage filter, and 7.5 liter liquid nitrogen was 11 kg. Gamma-ray spectra were measured at various places in Japan Research Reactor No. 3 using the spectrometer. Gamma-rays from natural radioactive nuclides such as 40K, 208Tl, 214Bi, and from 60Co, which was an induced radioactive nuclide of the reactor constructing components, were observed at all the places. During the reactor in operation, gamma-rays from 41Ar, the induced radioactive nuclide of argon in air, were observed also at all the places. High-energy gamma-rays from the neutron capture reaction in iron and from 16N induced by 16O(n,p)16N reaction in the oxygen in heavy-water coolant were found in the first floor of the reactor room; the former seemed to originate from the monochromator crystals of the neutron diffractometers. Noble gas fission product gamma-rays were observed in helium cover gas in the FFD system. Pulse height distributions and counting rates of these gamma-rays were shown. (author)

  11. Gamma-ray Albedo of the Moon

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. Specific activities and the relevant gamma ray dose rates at 1 meter from radioisotopes and isomers following thermal neutron capture reaction

    International Nuclear Information System (INIS)

    Calculations were performed for the specific activity of 245 gamma-ray emitting radioisotopes and isomers produced in 48, 72 and 96 hour irradiation periods of the natural isotopic mixture of their 77 elements with thermal neutron flux 1.0 E + 13 n/cm2 .5, at the core of the (ET-R R-1) reactor. The relevant gamma-ray dose rate at a point 1 meter apart from each radioisotope or isomer was evaluated whenever the specific gamma-ray dose rate constant is available. The irradiation time factor (ITF) for the irradiation periods 24, 48, 72 and 96 hours are reported for each of the 248 gamma-ray emitters. The average of (ITF) over these 248 radionuclides for each irradiation period is taken as a measure of the feasibility of the irradiation time. The results favour the increase of the irradiation period from the conventional 48 to 72 hours but not to 96 hours. A programme was established in the VAX computer to carry out the above mentioned calculations. Tables of the present work are very useful for isotope production and reactor safety. 1 fig., 2 tabs

  13. Statistical analysis for discrimination of prompt gamma ray peak induced by high energy neutron: Monte Carlo simulation study

    International Nuclear Information System (INIS)

    The purpose of this research is a statistical analysis for discrimination of prompt gamma ray peak induced by the 14.1 MeV neutron particles from spectra using Monte Carlo simulation. For the simulation, the information of 18 detector materials was used to simulate spectra by the neutron capture reaction. The discrimination of nine prompt gamma ray peaks from the simulation of each detector material was performed. We presented the several comparison indexes of energy resolution performance depending on the detector material using the simulation and statistics for the prompt gamma activation analysis. (author)

  14. Gamma Ray Bursts

    Science.gov (United States)

    Gehrels, Neil; Meszaros, Peter

    2012-01-01

    Gamma-ray bursts (GRBs) are bright flashes of gamma-rays coming from the cosmos. They occur roughly once per day ,last typically lOs of seconds and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.

  15. Gamma-Ray Bursts

    Science.gov (United States)

    Gehrels, Neil; Mészáros, Péter

    2012-08-01

    Gamma-ray bursts (GRBs) are bright flashes of gamma rays coming from the cosmos. They occur roughly once per day, typically last for tens of seconds, and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this Review, we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglow.

  16. Gamma Ray Bursts

    CERN Document Server

    Gehrels, Neil; 10.1126/science.1216793

    2012-01-01

    Gamma-ray bursts (GRBs) are bright flashes of gamma-rays coming from the cosmos. They occur roughly once per day, last typically 10s of seconds and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.

  17. SVOM gamma ray monitor

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The space-based multi-band astronomical Variable Object Monitor(SVOM) mission is dedicated to the detection,localization and broad-band study of gamma-ray bursts(GRBs) and other high-energy transient phenomena.The gamma ray monitor(GRM) onboard is designed to observe GRBs up to 5 MeV.With this instrument,one of the key GRB parameters,Epeak,can be easily measured in the hard X-ray band.It can achieve a detection rate of 100 GRBs per year which ensures the scientific output of SVOM.

  18. Evaluation on radiation features of the KUR deuterium neutron irradiation equipment. Neutron energy spectra and neutron- and gamma-ray absorption dose rate

    International Nuclear Information System (INIS)

    The deuterium irradiation equipment at reactor for research in Kyoto University (KUR) was reformed at main aim of upgrading of neutron capture therapy (NCT) from November, 1995 to March, 1996. Neutron energy spectra at reference radiation position evaluated on a partial radiation mode by multiple activated foil method, was introduced. As a result of carrying out a simulation calculation using two dimensional transmission calculation supposing medical radiation using the obtained spectra, experimental results could be followed satisfactorily in total. And, comparison with differential absorption dose rate measured by using twin-type ionization box and semiconductor detector for medical probe was also carried out. (G.K.)

  19. Transuranic isotopic analysis using gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D; Decman, D

    1998-10-15

    Transuranic waste typically emits gamma rays that are characteristic of the isotopic composition of the materials. If the area of the gamma ray photopeaks in a High Purity Ge (HPGe) spectrum can be accurately determined and if the gamma ray/x-ray branching ratios and half-lives for the radionuclides in the sample are known the relative concentration of each isotope in the waste can be determined using tomographic techniques. Methods used to accurately determine these photopeaks usually requires a computer code that does multi-peak analysis and unfolding of a given part of the gamma-ray spectrum. Computer techniques allow an accurate determination of the photopeaks and hence the isotopic composition of the waste material. These computer techniques can be automated for different spectra within a wide range of possible isotopic compositions. To improve photopeak statistics all of the spectra taken in a tomographic survey of the sample are summed and are used in the isotopic analysis. The method, accuracy, and limitations of this type of isotopic analysis system will be discussed. The gamma ray acquisition system is currently being upgraded with multiple HPGe detectors to improve the counting statistics obtainable in a given amount of time. The results of the DOE performance evaluations and the progress of the multiple detector upgrade will be discussed.

  20. Gamma-ray spectroscopy on irradiated fuel rods

    International Nuclear Information System (INIS)

    The recording of gamma-ray spectra along an irradiated fuel rod allows the fission products to be qualitatively and quantitatively examined. Among all nondestructive examinations performed on irradiated fuel rods by gamma-ray spectroscopy, the most comprehensive one is the average burnup measurement, which is quantitative. Moreover, burnup measurements by means of gamma-ray spectroscopy are less time-consuming and waste-generating than burnup measurements by radiochemical, destructive methods. This work presents the theoretical foundations and experimental techniques necessary to measure, using nondestructive gamma-ray spectroscopy, the average burnup of irradiated fuel rods in a laboratory equipped with hot cells. (author)

  1. Chemist's gamma-ray table

    International Nuclear Information System (INIS)

    An edited listing of gamma-ray information has been prepared. Prominent gamma rays originating from nuclides with half lives long enough to be seen in radiochemical experiments are included. Information is ordered by nuclide in one section and by energy in a second section. This shorter listing facilitates identification of nuclides responsible for gamma rays observed in experiments

  2. A synchrotron self-Compton emission model compared with the VHE spectrum of Crab Nebula, Geminga energy spectra and hadronic gamma-rays in the Tycho SNR

    Energy Technology Data Exchange (ETDEWEB)

    Sinitsyna, V.G.; Borisov, S.S.; Musin, F.I.; Nikolsky, S.I.; Sinitsyna, V.Y.; Platonov, G.F. [P.N.Lebedev Physical Institute, Leninsky prospect 53, Moscow, 119991 (Russian Federation)

    2009-12-15

    The Crab Nebula has an extraordinary broad spectrum, attributed to synchrotron radiation of electrons with energies from GeV to PeV. This continuous spectrum appears to terminate near 10{sup 8} eV and photons, produced by relativistic electrons and positrons (approx10{sup 15} eV) via the Inverse Compton effect, form a new component of the spectrum in the GeV - TeV energy range. The spectrum of gamma-rays from the Crab Nebula has been measured in the energy range 0.8 TeV to 11 TeV at the SHALON Alatoo Observatory by the atmospheric Cerenkov technique. The VHE spectral energy distribution of the Crab Nebula is compared with the predictions of a synchrotron self-Compton emission model in the energy range 0.8 TeV to 11 TeV (Hillas et al. 1998). Tycho's SNR has been observed by SHALON imaging Cherenkov telescope at Tien-Shan. This object, Ia SNR, has long been considered as a candidate for a CR hadron source in the Northern Hemisphere. The expected pion decay gamma-flux, F{sub g}ammaapproxE{sub g}amma{sup -1}, extends up to >30 TeV, whereas the IC gamma-ray flux has a cutoff above a few TeV. So, the detection of gamma-rays at energies of 10 - 40 TeV by SHALON is evidence for a hadron origin of the gamma-rays.

  3. Heliospheric Origin of $\\gamma$-Ray Bursts

    CERN Document Server

    Li Ti Pei

    1997-01-01

    Systematic variations of average observational characteristics and correlation properties between different parameters of gamma-ray bursts (GRBs) with time from 1991 April to 1994 September are revealed. It is hard to explain the observed long-term variability by variations of experimental conditions. The variability of GRB properties with the time scale of months to years, together with the similarity between GRBs, solar hard X-ray flares and terrestrial gamma-ray flashes, may indicate an origin of GRBs, at least partly, within the heliosphere. Large-voltage and high-temperature pinch plasma columns produced by disruptive electrical discharges in the outer heliosphere can generate hard X-ray and gamma-ray flashes with energy spectra and spectral evolution characters consistent with that observed in GRBs.

  4. Gamma Ray Astronomy with Magnetized Zevatrons

    CERN Document Server

    Armengaud, E; Miniati, F; Armengaud, Eric; Sigl, Guenter; Miniati, Francesco

    2005-01-01

    Nearby sources of cosmic rays up to a ZeV(=10^21 eV) could be observed with a multi-messenger approach including secondary gamma-rays and neutrinos. If cosmic rays above ~10^18 eV are produced in magnetized environments such as galaxy clusters, the flux of secondary gamma-rays below ~1 TeV can be enhanced up to several orders of magnitudes compared to unmagnetized sources. A particular source of enhancement are synchrotron and cascade photons from e^+e^- pairs produced by protons from sources with relatively steep injection spectra proportional to E^-2.6. Such sources should be visible at the same time in ultra-high energy cosmic ray experiments and gamma-ray telescopes.

  5. Gamma-ray bursters at cosmological distances

    Science.gov (United States)

    Paczynski, B.

    1986-01-01

    It is proposed that some, perhaps most, gamma-ray bursters are at cosmological distances, like quasars, with a redshift of about 1 or 2. This proposition requires a release of supernova-like energy of about 10 to the 51st ergs within less than 1 s, making gamma-ray bursters the brightest objects known in the universe, many orders of magnitude brighter than any quasars. This power must drive a highly relativistic outflow of electron-positron plasma and radiation from the source. It is proposed that three gamma-ray bursts, all with identical spectra, detected from B1900 + 14 by Mazets, Golenetskii, and Gur'yan and reported in 1979, were all due to a single event multiply imaged by a gravitational lens. The time intervals between the successive bursts, 10 hr to 3 days, were due to differences in the light travel time for different images.

  6. Statistical analysis for discrimination of prompt gamma ray peak induced by high energy neutron: Monte Carlo simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Moo-Sub; Jung, Joo-Young; Suh, Tae Suk [College of Medicine, Catholic University of Korea, Seoul (Korea, Republic of)

    2015-05-15

    The purpose of this research was the statistical analysis for discrimination of the prompt gamma ray peak induced by the 14.1 MeV neutron particles from spectra using Monte Carlo simulation. For the simulation, the information of the eighteen detector materials was used to simulate spectra by the neutron capture reaction. To the best of our knowledge, the results in this study are the first reported data regarding the peak discrimination of high energy prompt gamma ray using the many cases (the eighteen detector materials and the nine prompt gamma ray peaks). The reliable data based on the Monte Carlo method and statistical method with the identical conditions was deducted. Our results are important data in the PGAA study for the peak detection within actual experiments.

  7. Statistical analysis for discrimination of prompt gamma ray peak induced by high energy neutron: Monte Carlo simulation study

    International Nuclear Information System (INIS)

    The purpose of this research was the statistical analysis for discrimination of the prompt gamma ray peak induced by the 14.1 MeV neutron particles from spectra using Monte Carlo simulation. For the simulation, the information of the eighteen detector materials was used to simulate spectra by the neutron capture reaction. To the best of our knowledge, the results in this study are the first reported data regarding the peak discrimination of high energy prompt gamma ray using the many cases (the eighteen detector materials and the nine prompt gamma ray peaks). The reliable data based on the Monte Carlo method and statistical method with the identical conditions was deducted. Our results are important data in the PGAA study for the peak detection within actual experiments

  8. Gamma ray beam transmutation

    International Nuclear Information System (INIS)

    We have proposed a new approach to nuclear transmutation by a gamma ray beam of Compton scattered laser photon. We obtained 20 MeV gamma ray in this way to obtain transmutation rates with the giant resonance of 197Au and 129Iodine. The rate of the transmutation agreed with the theoretical calculation. Experiments on energy spectrum of positron, electron and neutron from targets were performed for the energy balance and design of the system scheme. The reaction rate was about 1.5∼4% for appropriate photon energies and neutron production rate was up to 4% in the measurements. We had stored laser photon more than 5000 times in a small cavity which implied for a significant improvement of system efficiency. Using these technologies, we have designed an actual transmutation system for 129Iodine which has a 16 million year's activity. In my presentation, I will address the properties of this scheme, experiments results and transmutation system for iodine transmutation

  9. Gamma ray camera

    International Nuclear Information System (INIS)

    An Anger gamma ray camera is improved by the substitution of a gamma ray sensitive, proximity type image intensifier tube for the scintillator screen in the Anger camera. The image intensifier tube has a negatively charged flat scintillator screen, a flat photocathode layer, and a grounded, flat output phosphor display screen, all of which have the same dimension to maintain unit image magnification; all components are contained within a grounded metallic tube, with a metallic, inwardly curved input window between the scintillator screen and a collimator. The display screen can be viewed by an array of photomultipliers or solid state detectors. There are two photocathodes and two phosphor screens to give a two stage intensification, the two stages being optically coupled by a light guide. (author)

  10. Time-of-flight discrimination between gamma-rays and neutrons by neural networks

    OpenAIRE

    Akkoyun, Serkan

    2012-01-01

    In gamma-ray spectroscopy, a number of neutrons are emitted from the nuclei together with the gamma-rays and these neutrons influence gamma-ray spectra. An obvious method of separating between neutrons and gamma-rays is based on the time-of-flight (tof) technique. This work aims obtaining tof distributions of gamma-rays and neutrons by using feed-forward artificial neural network (ANN). It was shown that, ANN can correctly classify gamma-ray and neutron events. Testing of trained networks on ...

  11. Some deficiencies and solutions in gamma ray spectrometry

    International Nuclear Information System (INIS)

    A number of problems in high-resolution gamma ray spectrometry as well as some deficiencies of existing computer programs for the quantitative evaluation of spectra are discussed and some practical solutions are proposed. (author)

  12. Computers in activation analysis and gamma-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, B. S.; D' Agostino, M. D.; Yule, H. P. [eds.

    1979-01-01

    Seventy-three papers are included under the following session headings: analytical and mathematical methods for data analysis; software systems for ..gamma..-ray and x-ray spectrometry; ..gamma..-ray spectra treatment, peak evaluation; least squares; IAEA intercomparison of methods for processing spectra; computer and calculator utilization in spectrometer systems; and applications in safeguards, fuel scanning, and environmental monitoring. Separate abstracts were prepared for 72 of those papers. (DLC)

  13. Observational techniques of gamma rays astronomy in low energy

    International Nuclear Information System (INIS)

    Due to the absorption of great part of the gamma-ray spectrum of cosmic origin, by the earth's atmosphere at heights above 20Km, gamma-ray astronomy achieved its full development only after the advent of the space age. Ballons and satellites are the space vehicles which have been used to transport gamma-ray telescopes to observational heights in the atmosphere, or out of it. The results of these experiments can determine the sources, the energy spectra and the intensities of the cosmic gamma-rays, and provide other important information of astrophysical interest. The detection of gamma-rays of cosmic origin is very difficult. The observational techniques used in gamma-ray astronomy are dependent on the energy range of the gamma-rays which one desires to detect. The most common telescopes of low energy gamma-ray astronomy (50KeV - 20MeV) use NaI(Tl) scintillators, or germanium diodes, as principal detectors, surrounded by an active shield (anticoincidence) of organic or inorganic scintillators. (Author)

  14. Automation system for measurement of gamma-ray spectra of induced activity for multi-element high-volume neutron activation analysis at the IBR-2 reactor of FLNP at JINR

    International Nuclear Information System (INIS)

    The automation system for measurement of induced activity of gamma-ray spectra for multi-element high-volume neutron activation analysis (NAA) was designed, developed and implemented at the IBR-2 reactor at the Frank Laboratory of Neutron Physics. The system consists of three devices of automatic sample changers for three Canberra HPGe detector-based gamma spectrometry systems. Each sample changer consists of two-axis linear positioning module M202A by DriveSet company and disk with 45 slots for containers with samples. Control of automatic sample changer is performed by the Xemo S360U controller by Systec company. Positioning accuracy can reach 0.1 mm. Special software performs automatic changing of samples and measurement of gamma-spectra at constant interaction with the NAA database.

  15. Automation system for measurement of gamma-ray spectra of induced activity for multi-element high volume neutron activation analysis at the reactor IBR-2 of Frank Laboratory of Neutron Physics at the joint institute for nuclear research

    Science.gov (United States)

    Pavlov, S. S.; Dmitriev, A. Yu.; Chepurchenko, I. A.; Frontasyeva, M. V.

    2014-11-01

    The automation system for measurement of induced activity of gamma-ray spectra for multi-element high volume neutron activation analysis (NAA) was designed, developed and implemented at the reactor IBR-2 at the Frank Laboratory of Neutron Physics. The system consists of three devices of automatic sample changers for three Canberra HPGe detector-based gamma spectrometry systems. Each sample changer consists of two-axis of linear positioning module M202A by DriveSet company and disk with 45 slots for containers with samples. Control of automatic sample changer is performed by the Xemo S360U controller by Systec company. Positioning accuracy can reach 0.1 mm. Special software performs automatic changing of samples and measurement of gamma spectra at constant interaction with the NAA database.

  16. Can we probe the Lorentz factor of gamma-ray bursts from GeV-TeV spectra integrated over internal shocks?

    CERN Document Server

    Aoi, Junichi; Takahashi, Keitaro; Ioka, Kunihito; Nagataki, Shigehiro

    2009-01-01

    We revisit the high-energy spectral cutoff originating from the electron-positron pair creation in the prompt phase of gamma-ray bursts (GRBs) with numerical and analytical calculations. We show that the conventional exponential cutoff should be drastically modified to a steepened power-law in practical observations that integrate emissions from different internal shocks. Since the steepening is tiny for observations, this "smearing" effect can generally reduce the previous estimates of the Lorentz factor of the GRB outflows. We apply our formulation to GRB 080916C, recently detected by the LAT detector on the Fermi satellite, and find that the minimum Lorentz factor can be ~600 (or even smaller values), which is below but consistent with the previous result of ~900. Observing the steepening energy (so-called "pair-break energy") is crucial to diagnose the Lorentz factor and/or the emission site in the future observations.

  17. Gamma-ray Emission from Globular Clusters

    Science.gov (United States)

    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.

  18. The solar gamma ray and neutron capabilities of COMPTEL on the Gamma Ray Observatory

    Science.gov (United States)

    Ryan, James M.; Lockwood, John A.

    1989-01-01

    The imaging Compton telescope COMPTEL on the Gamma Ray Observatory (GRO) has unusual spectroscopic capabilities for measuring solar gamma-ray and neutron emission. The launch of the GRO is scheduled for June 1990 near the peak of the sunspot cycle. With a 30 to 40 percent probability for the Sun being in the COMPTEL field-of-view during the sunlit part of an orbit, a large number of flares will be observed above the 800 keV gamma-ray threshold of the telescope. The telescope energy range extends to 30 MeV with high time resolution burst spectra available from 0.1 to 10 MeV. Strong Compton tail suppression of instrumental gamma-ray interactions will facilitate improved spectral analysis of solar flare emissions. In addition, the high signal to noise ratio for neutron detection and measurement will provide new neutron spectroscopic capabilities. Specifically, a flare similar to that of 3 June 1982 will provide spectroscopic data on greater than 1500 individual neutrons, enough to construct an unambiguous spectrum in the energy range of 20 to 200 MeV. Details of the instrument and its response to solar gamma-rays and neutrons will be presented.

  19. Requirements on gamma ray spectrum analysis programs

    International Nuclear Information System (INIS)

    Many programs intended for the evaluation of gamma ray spectra have been written. Most of them cover the basic needs but there are several options a user might want to have which are not incorporated. This paper attempts to list all general and some special requirements on such programs. Recommendations on details of the physical and technical methods to match the requirements and the citation of any existing program are avoided. (author)

  20. Cosmic gamma rays from quasars

    International Nuclear Information System (INIS)

    The diffuse gamma radiation consists of the galactic and extragalactic components. The latter component is of special interest on account of its cosmological significance. Following the method recently proposed to estimate the gamma ray flux from galaxy clusters, and the detection of gamma rays from the quasars 3C273, the data base of the SAS II satellite was used to estimate the contribution from quasars to the extragalactic gamma ray flux. It is shown that quasars as a whole are significant gamma ray contributors, the average gamma ray flux per quasar in the energy range 35 MeV to 100 Mev being (1.3 + or - 0.9) x .00001 cm(-2)s(-1)sr(-1)

  1. Cosmic gamma rays from quasars

    Science.gov (United States)

    Lau, M. M.; Young, E. C. M.

    1985-01-01

    The diffuse gamma radiation consists of the galactic and extragalactic components. The latter component is of special interest on account of its cosmological significance. Following the method recently proposed to estimate the gamma ray flux from galaxy clusters, and the detection of gamma rays from the quasars 3C273, the data base of the SAS II satellite was used to estimate the contribution from quasars to the extragalactic gamma ray flux. It is shown that quasars as a whole are significant gamma ray contributors, the average gamma ray flux per quasar in the energy range 35 MeV to 100 Mev being (1.3 + or - 0.9) x .00001 cm(-2)s(-1)sr(-1).

  2. Gamma ray bursts of black hole universe

    Science.gov (United States)

    Zhang, T. X.

    2015-07-01

    Slightly modifying the standard big bang theory, Zhang recently developed a new cosmological model called black hole universe, which has only a single postulate but is consistent with Mach's principle, governed by Einstein's general theory of relativity, and able to explain existing observations of the universe. In the previous studies, we have explained the origin, structure, evolution, expansion, cosmic microwave background radiation, quasar, and acceleration of black hole universe, which grew from a star-like black hole with several solar masses through a supermassive black hole with billions of solar masses to the present state with hundred billion-trillions of solar masses by accreting ambient matter and merging with other black holes. This study investigates gamma ray bursts of black hole universe and provides an alternative explanation for the energy and spectrum measurements of gamma ray bursts according to the black hole universe model. The results indicate that gamma ray bursts can be understood as emissions of dynamic star-like black holes. A black hole, when it accretes its star or merges with another black hole, becomes dynamic. A dynamic black hole has a broken event horizon and thus cannot hold the inside hot (or high-frequency) blackbody radiation, which flows or leaks out and produces a GRB. A star when it collapses into its core black hole produces a long GRB and releases the gravitational potential energy of the star as gamma rays. A black hole that merges with another black hole produces a short GRB and releases a part of their blackbody radiation as gamma rays. The amount of energy obtained from the emissions of dynamic star-like black holes are consistent with the measurements of energy from GRBs. The GRB energy spectra derived from this new emission mechanism are also consistent with the measurements.

  3. Method for converting in-situ gamma ray spectra of a portable Ge detector to an incident photon flux energy distribution based on Monte Carlo simulation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A matrix stripping method for the conversion of in-situ gamma ray spectrum, obtained with portable Ge detector, to photon flux energy distribution is proposed. The detector response is fully described by its stripping matrix and full absorption efficiency curve. A charge collection efficiency function is introduced in the simulation to take into account the existence of a transition zone of increasing charge collection after the inactive Ge layer. Good agreement is obtained between simulated and experimental full absorption efficiencies. The characteristic stripping matrix is determined by Monte Carlo simulation for different incident photon energies using the Geant4 toolkit system. The photon flux energy distribution is deduced by stripping the measured spectrum of the partial absorption and cosmic ray events and then applying the full absorption efficiency curve. The stripping method is applied to a measured in-situ spectrum. The value of the absorbed dose rate in air deduced from the corresponding flux energy distribution agrees well with the value measured directly in-situ.

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

    Science.gov (United States)

    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.

  5. Application of multiple gamma-ray spectrum for analytical chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Hatsukawa, Yuichi; Hayakawa, Takehito; Shinohara, Noboru; Oshima, Masumi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2000-01-01

    Feasibility of application of the multi-gamma ray spectrum for analytical chemistry was examined. A specimen in which some minor fission products are included was measured at an array of ten germanium detectors with BGO Compton suppressors, GEMINI, and multiple gamma-ray spectra are measured. Even in very strong radiation fields from {sup 137}Cs isotope, some miner contents, {sup 106}Ru, {sup 125}Sb, {sup 144}Pr, {sup 207}Bi were detected by this method. (author)

  6. Gamma-Rays and Neutrinos from Dark Matter

    OpenAIRE

    Stecker, F. W.

    1996-01-01

    High energy gamma-rays and neutrinos can be produced both by the annihilation and by the possible slow decay of dark matter particles. We discuss the fluxes and spectra of such secondaries produced by dark matter particles in the universe and their observability in competition with other astrophysical gamma-ray signals and with atmospheric neutrinos. To do this, we work within the assumption that the dark matter particles are neutralinos which are the lightest supersymmetric particles (LSPs) ...

  7. Photoneutron cross sections measurements in {sup 9}Be, {sup 13}C e {sup 17}O with thermal neutron capture gamma-rays; Medidas das secoes de choque de fotoneutrons do {sup 9}Be, {sup 13}C e {sup 17}O com radiacao gama de captura de neutrons termicos

    Energy Technology Data Exchange (ETDEWEB)

    Semmler, Renato

    2006-07-01

    Photoneutron cross sections measurements of {sup 9}Be, {sup 13}C and {sup 17}O have been obtained in the energy interval between 1,6 and 10,8 MeV, using neutron capture gamma-rays with high resolution in energy (3 a 21 eV), produced by 21 target materials, placed inside a tangential beam port, near the core of the IPEN/CNEN-SP IEA-R1 (5 MW) research reactor. The samples have been irradiated inside a 4{pi} geometry neutron detector system 'Long Counter', 520,5 cm away from the capture target. The capture gamma-ray flux was determined by means of the analysis of the gamma spectrum obtained by using a Ge(Li) solid-state detector (EG and G ORTEC, 25 cm{sup 3}, 5%), previously calibrated with capture gamma-rays from a standard target of Nitrogen (Melamine). The neutron photoproduction cross section has been measured for each target capture gamma-ray spectrum (compound cross section). A inversion matrix methodology to solve inversion problems for unfolding the set of experimental compound cross sections, was used in order to obtain the cross sections at specific excitation energy values (principal gamma line energies of the capture targets). The cross sections obtained at the energy values of the principal gamma lines were compared with experimental data reported by other authors, with have employed different gamma-ray sources. A good agreement was observed among the experimental data in this work with reported in the literature. (author)

  8. The Gamma-ray Albedo of the Moon

    Energy Technology Data Exchange (ETDEWEB)

    Moskalenko, Igor V.; /Stanford U., HEPL; Porter, Troy A.; /UC, Santa Cruz

    2007-09-28

    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 3-4 GeV (600 MeV for the inner part of the Moon disk) and exhibits a narrow pion-decay line at 67.5 MeV, perhaps unique in astrophysics. Apart from other astrophysical sources, the albedo spectrum of the Moon is well understood, including its absolute normalization; this makes it a useful 'standard candle' for {gamma}-ray telescopes. The steep albedo spectrum also provides a unique opportunity for energy calibration of {gamma}-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). Since the albedo flux depends on the incident CR spectrum which changes over the solar cycle, 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 {gamma}-rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the LAT to monitor the CR spectrum near the Earth beyond the lifetime of the PAMELA.

  9. Effect of gamma ray irradiation on sodium borate single crystals

    Science.gov (United States)

    Kalidasan, M.; Asokan, K.; Baskar, K.; Dhanasekaran, R.

    2015-12-01

    In this work, the effects of 5 kGy, 10 kGy and 20 kGy doses of gamma ray irradiation on sodium borate, Na2[B4O5(OH)4]·(H2O)8 single crystals have been studied. Initially these crystals were grown by solution growth technique and identified as monoclinic using X-ray diffraction analysis. X-ray rocking curves confirm the formation of crystalline defects due to gamma rays in sodium borate single crystals. The electron paramagnetic resonance spectra have been recorded to identify the radicals created due to gamma ray irradiation in sodium borate single crystals. The thermoluminescence glow curves due to the defects created by gamma rays in this crystal have been observed and their kinetic parameters were calculated using Chen's peak shape method. The optical absorption increases and photoluminescence spectral intensity decreases for 5 kGy and 20 kGy doses gamma ray irradiated crystals compared to pristine and 10 kGy dose irradiated one. The effect of various doses of gamma rays on vibrational modes of the sodium borate single crystals was studied using FT-Raman and ATR-FTIR spectral analysis. The dielectric permittivity, conductance and dielectric loss versus frequency graphs of these crystals have been analyzed to know the effect of gamma ray irradiation on these parameters.

  10. Spatial distribution of reflected gamma rays by Monte Carlo simulation

    International Nuclear Information System (INIS)

    In nuclear facilities, the reflection of gamma rays of the walls and metals constitutes an unknown origin of radiation. These reflected gamma rays must be estimated and determined. This study concerns reflected gamma rays on metal slabs. We evaluated the spatial distribution of the reflected gamma rays spectra by using the Monte Carlo method. An appropriate estimator for the double differential albedo is used to determine the energy spectra and the angular distribution of reflected gamma rays by slabs of iron and aluminium. We took into the account the principal interactions of gamma rays with matter: photoelectric, coherent scattering (Rayleigh), incoherent scattering (Compton) and pair creation. The Klein-Nishina differential cross section was used to select direction and energy of scattered photons after each Compton scattering. The obtained spectra show peaks at 0.511* MeV for higher source energy. The Results are in good agreement with those obtained by the TRIPOLI code [J.C. Nimal et al., TRIPOLI02: Programme de Monte Carlo Polycinsetique a Trois dimensions, CEA Rapport, Commissariat a l'Energie Atomique.

  11. Spatial distribution of reflected gamma rays by Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Jehouani, A. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, B.P. 2390, 40000 Marrakech (Morocco)], E-mail: jehouani@ucam.ac.ma; Merzouki, A. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, B.P. 2390, 40000 Marrakech (Morocco); Remote Sensing and Geomatics of the Environment Laboratory, Ottawa-Carleton Geoscience Centre, Marion Hall, 140 Louis Pasteur, Ottawa, ON, KIN 6N5 (Canada); Boutadghart, F.; Ghassoun, J. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, B.P. 2390, 40000 Marrakech (Morocco)

    2007-10-15

    In nuclear facilities, the reflection of gamma rays of the walls and metals constitutes an unknown origin of radiation. These reflected gamma rays must be estimated and determined. This study concerns reflected gamma rays on metal slabs. We evaluated the spatial distribution of the reflected gamma rays spectra by using the Monte Carlo method. An appropriate estimator for the double differential albedo is used to determine the energy spectra and the angular distribution of reflected gamma rays by slabs of iron and aluminium. We took into the account the principal interactions of gamma rays with matter: photoelectric, coherent scattering (Rayleigh), incoherent scattering (Compton) and pair creation. The Klein-Nishina differential cross section was used to select direction and energy of scattered photons after each Compton scattering. The obtained spectra show peaks at 0.511{sup *} MeV for higher source energy. The Results are in good agreement with those obtained by the TRIPOLI code [J.C. Nimal et al., TRIPOLI02: Programme de Monte Carlo Polycinsetique a Trois dimensions, CEA Rapport, Commissariat a l'Energie Atomique. ].

  12. Spatial distribution of reflected gamma rays by Monte Carlo simulation

    Science.gov (United States)

    Jehouani, A.; Merzouki, A.; Boutadghart, F.; Ghassoun, J.

    2007-10-01

    In nuclear facilities, the reflection of gamma rays of the walls and metals constitutes an unknown origin of radiation. These reflected gamma rays must be estimated and determined. This study concerns reflected gamma rays on metal slabs. We evaluated the spatial distribution of the reflected gamma rays spectra by using the Monte Carlo method. An appropriate estimator for the double differential albedo is used to determine the energy spectra and the angular distribution of reflected gamma rays by slabs of iron and aluminium. We took into the account the principal interactions of gamma rays with matter: photoelectric, coherent scattering (Rayleigh), incoherent scattering (Compton) and pair creation. The Klein-Nishina differential cross section was used to select direction and energy of scattered photons after each Compton scattering. The obtained spectra show peaks at 0.511∗ MeV for higher source energy. The Results are in good agreement with those obtained by the TRIPOLI code [J.C. Nimal et al., TRIPOLI02: Programme de Monte Carlo Polycinśetique à Trois dimensions, CEA Rapport, Commissariat à l'Energie Atomique. [1

  13. Gamma-ray Pulsar Revolution

    OpenAIRE

    Caraveo, Patrizia A.

    2013-01-01

    Isolated Neutron Stars (INSs) were the first sources identified in the field of high-energy gamma-ray astronomy. At first, in the 70s, there were only two identified sources, the Crab and Vela pulsars. However, although few in number, these objects were crucial in establishing the very concept of a gamma-ray source. Moreover, they opened up significant discovery space both in the theoretical and phenomenological fronts. The need to explain the copious gamma-ray emission of these pulsars led t...

  14. High energy irradiations simulating cosmic-ray-induced planetary gamma ray production. I - Fe target

    Science.gov (United States)

    Metzger, A. E.; Parker, R. H.; Yellin, J.

    1986-01-01

    Two thick Fe targets were bombarded by a series of 6 GeV proton irradiations for the purpose of simulating the cosmic ray bombardment of planetary objects in space. Gamma ray energy spectra were obtained with a germanium solid state detector during the bombardment, and 46 of the gamma ray lines were ascribed to the Fe targets. A comparison between observed and predicted values showed good agreement for Fe lines from neutron inelastic scattering and spallation reactions, and less satisfactory agreement for neutron capture reactions, the latter attributed to the difference in composition between the Fe target and the mean lunar abundance used in the modeling. Through an analysis of the irradiation results together with continuum data obtained in lunar orbit, it was found that 100 hours of measurement with a current instrument should generate a spectrum containing approximately 20 lines due to Fe alone, with a 2-sigma sensitivity for detection of about 0.2 percent.

  15. Gamma-ray Burst Cosmology

    CERN Document Server

    Wang, F Y; Liang, E W

    2015-01-01

    Gamma-ray bursts (GRBs) are the most luminous electromagnetic explosions in the Universe, which emit up to $8.8\\times10^{54}$ erg isotropic equivalent energy in the hard X-ray band. The high luminosity makes them detectable out to the largest distances yet explored in the Universe. GRBs, as bright beacons in the deep Universe, would be the ideal tool to probe the properties of high-redshift universe: including the cosmic expansion and dark energy, star formation rate, the reionization epoch and the metal enrichment history of the Universe. In this article, we review the luminosity correlations of GRBs, and implications for constraining the cosmological parameters and dark energy. Observations show that the progenitors of long GRBs are massive stars. So it is expected that long GRBs are tracers of star formation rate. We also review the high-redshift star formation rate derived from GRBs, and implications for the cosmic reionization history. The afterglows of GRBs generally have broken power-law spectra, so it...

  16. Gamma rays at airplane altitudes

    International Nuclear Information System (INIS)

    An examination of the gamma ray flux above 1 TeV in the atmosphere is needed to better understand the anomalous showers from point sources. Suggestions are made for future experiments on board airplanes

  17. The Extragalactic Gamma-ray Sky in the Fermi era

    CERN Document Server

    Massaro, F; Ferrara, E C

    2015-01-01

    The Universe is largely transparent to $\\gamma$ rays in the GeV energy range, making these high-energy photons valuable for exploring energetic processes in the cosmos. After seven years of operation, the Fermi {\\it Gamma-ray Space Telescope} has produced a wealth of information about the high-energy sky. This review focuses on extragalactic $\\gamma$-ray sources: what has been learned about the sources themselves and about how they can be used as cosmological probes. Active galactic nuclei (blazars, radio galaxies, Seyfert galaxies) and star-forming galaxies populate the extragalactic high-energy sky. Fermi observations have demonstrated that these powerful non-thermal sources display substantial diversity in energy spectra and temporal behavior. Coupled with contemporaneous multifrequency observations, the Fermi results are enabling detailed, time-dependent modeling of the energetic particle acceleration and interaction processes that produce the $\\gamma$ rays, as well as providing indirect measurements of t...

  18. Emission probabilities of gamma rays from the decay of 233Pa and 238Np, and the thermal neutron capture cross section of 237Np

    International Nuclear Information System (INIS)

    In order to determine the thermal neutron capture cross section of 237Np, the relevant γ emission probabilities of the 312-keV γ-ray from the decay of 233Pa and the 984-keV γ-ray from the decay of 238Np are deduced from the ratio of the emission rate to the activity. The emission rate and activity are measured with a Ge detector and a Si detector, respectively. The measured emission probability for 312-keV γ-ray is 41.6±0.9% and that for 984-keV γ-ray is 25.2±0.5%. The emission probabilities are used to correct the thermal neutron capture cross section of 237Np reported previously, and gives 168±6b. The neutron capture cross section is also determined as 169±6b by α-ray spectroscopic method. The measured emission probabilities and capture cross section are compared with others from references. By averaging these values deduced by different methods, the value of 169±4b is recommended as the thermal neutron capture cross section of 237Np for 2,200 m/s neutrons. (author)

  19. Varying Faces of Photospheric Emission in Gamma-Ray Bursts

    CERN Document Server

    Axelsson, M

    2015-01-01

    Among the more than 1000 gamma-ray bursts observed by the Fermi Gamma-ray Space Telescope, a large fraction show narrow and hard spectra inconsistent with non-thermal emission, signifying optically thick emission from the photosphere. However, only a few of these bursts have spectra consistent with a pure Planck function. We will discuss the observational features of photospheric emission in these GRBs as well as in the ones showing multi-component spectra. We interpret the observations in light of models of subphotospheric dissipation, geometrical broadening and multi-zone emission, and show what we can learn about the dissipation mechanism and properties of GRB jets.

  20. Compton scattering in terrestrial gamma-ray flashes detected with the Fermi gamma-ray burst monitor

    CERN Document Server

    Fitzpatrick, Gerard; McBreen, Sheila; Briggs, Michael S; Foley, Suzanne; Tierney, David; Chaplin, Vandiver L; Connaughton, Valerie; Stanbro, Matthew; Xiong, Shaolin; Dwyer, Joseph; Fishman, Gerald J; Roberts, Oliver J; von Kienlin, Andreas

    2015-01-01

    Terrestrial gamma-ray flashes (TGFs) are short intense flashes of gamma rays associated with lightning activity in thunderstorms. Using Monte Carlo simulations of the relativistic runaway electron avalanche (RREA) process, theoretical predictions for the temporal and spectral evolution of TGFs are compared to observations made with the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope. Assuming a single source altitude of 15 km, a comparison of simulations to data is performed for a range of empirically chosen source electron variation time scales. The data exhibit a clear softening with increased source distance, in qualitative agreement with theoretical predictions. The simulated spectra follow this trend in the data, but tend to underestimate the observed hardness. Such a discrepancy may imply that the basic RREA model is not sufficient. Alternatively, a TGF beam that is tilted with respect to the zenith could produce an evolution with source distance that is compatible with the da...

  1. The Animated Gamma-ray Sky Revealed by the Fermi Gamma-ray Space Telescope

    International Nuclear Information System (INIS)

    The Fermi Gamma-ray Space Telescope has been observing the sky in gamma-rays since August 2008. In addition to breakthrough capabilities in energy coverage (20 MeV-300 GeV) and angular resolution, the wide field of view of the Large Area Telescope enables observations of 20% of the sky at any instant, and of the whole sky every three hours. It has revealed a very animated sky with bright gamma-ray bursts flashing and vanishing in minutes, powerful active galactic nuclei flaring over hours and days, many pulsars twinkling in the Milky Way, and X-ray binaries shimmering along their orbit. Most of these variable sources had not been seen by the Fermi predecessor, EGRET, and the wealth of new data already brings important clues to the origin of the high-energy emission and particles powered by the compact objects. The telescope also brings crisp images of the bright gamma-ray emission produced by cosmic-ray interactions in the interstellar medium, thus allowing to measure the cosmic nuclei and electron spectra across the Galaxy, to weigh interstellar clouds, in particular in the dark-gas phase. The telescope sensitivity at high energy will soon provide useful constraints on dark-matter annihilations in a variety of environments. I will review the current results and future prospects of the Fermi mission.

  2. Magnetic angle for gamma rays

    International Nuclear Information System (INIS)

    In December 2002 astronomers at the University of California in Berkeley got a lucky break. A bright gamma-ray burst appeared in the sky within 18 degrees of the Sun, which was close enough to be picked up by the RHESSI solar satellite. Analysing data from the satellite, Wayne Coburn and Steven Boggs made the stunning discovery that the gamma rays from the burst - named GRB021206 - were linearly polarized. And not just by any amount, but by 80% - the maximum polarization theoretically possible. The discovery represents a major breakthrough in gamma-ray astronomy (Nature 423 415).Gamma-ray bursts are the most energetic events in the universe, typically corresponding to the conversion of 1% of the mass of the Sun into energy. Every day an average of about one of these brief flashes of gamma rays - which come from any direction in the sky and last a few tens of seconds - are detected. Observations of the optical afterglow of the bursts reveal that they originate in galaxies that are several billions of light-years away. But what causes the bursts, and how the gamma rays are actually produced, have, until recently, remained a mystery. It has been suggested that gamma-ray bursts result from supernovae - the explosions of massive stars that have used up all their fuel - and that the bursts might be the 'birth cries' of black holes. Some of this evidence is circumstantial. It is known, for example, that the host galaxies of the bursts are regions where massive stars are copiously forming. However, observations of the afterglow of GRB980425 in 1998 revealed a spectral signature that would be expected for a supernova. This provided the first compelling, but inconclusive, direct evidence for the link between gamma-ray bursts and supernovae. In March this year, however, this link was dramatically confirmed. The HETE-2 satellite detected a spectacular gamma-ray burst that was among the closest and brightest ever observed. GRB030329 was just two billion light-years away, which

  3. Pulsed Gamma-Ray Emission From Short-Period Pulsars: Predicted Gamma-Ray Pulsar PSR1951+32

    Science.gov (United States)

    Cheng, K. S.; Ding, K. Y. Winnis

    1995-03-01

    We studied the gamma-ray emission mechanisms from pulsars with period, P, between 4.6 times 10(-2) B12(2/5) s and 0.17 B12(5/12) sin (1/6) theta alpha (-5/4) s in terms of outermagnetospheric gap model. We found that the spectra of all known gamma -ray pulsars can be fitted by two free parameters, namely, alpha r_L, the mean distance to the outergap, and sin theta , the mean pitch angle of the secondary e(+/-) pairs. Gamma-rays from those pulsars with P B12(5/12) sin (1/6) alpha (-5/4) s are mainly emitted by secondary e(+/-) pairs, which are created beyond the outergap, via synchrotron radiation and the gamma-ray emission efficiency is ~ 10(-2) . For pulsars with period approaching ~ 0.17 B12(5/12) sin (1/6) alpha (-5/4) s, their gamma-ray emission efficiency is approaching unity. We used our model to fit the observed spectra of gamma -ray pulsars (Vela, PSR1706-44, PSR1055-52, PSR1509-58, Geminga). All the best fit curves satisfy the constraints of alpha and sin theta . The pulse separation and relative intensity of pulses are function of alpha . In our model, the first three strongest theoretical gamma -ray sources have been detected. PSR1951+32 is predicted to be the fourth strongest gamma -ray pulsar (Cheng and Ding, 1994, ApJ, 432, 724) which is confirmed by the recent GRO result.

  4. The theoretical description of thermal neutron capture γ-spectra

    International Nuclear Information System (INIS)

    In the framework of statistical approach with phenomenological parametrization the energy dependence of the excited level density the thermal neutron capture γ-ray spectra for a number of spherical nuclei with 77<=A<=200 are calculated. Taking into account satisfactory agreement between theoretical and experimental intensities of the γ-ray spectra it is concluded that the photon E1- and M1-strength functions can serve as a reliable basis for the analysis of radiative decay of these nuclei

  5. Reducing Statistical Noise in Airborne Gamma-Ray Data

    DEFF Research Database (Denmark)

    Hovgaard, Jens; Grasty, R. L.

    1997-01-01

    By using the Noise Adjusted Singular Value Decomposition (NASVD) technique it is possible to reconstruct the measured airborne gamma-ray spectra with a noise content that is significant smaller than the noise contained in the original measured spectra. The method can be used for improving the out...

  6. Late Time Emission of Prompt Fission Gamma Rays

    CERN Document Server

    Talou, P; Stetcu, I; Lestone, J P; McKigney, E; Chadwick, M B

    2016-01-01

    The emission of prompt fission $\\gamma$ rays within a few nanoseconds to a few microseconds following the scission point is studied in the Hauser-Feshbach formalism applied to the deexcitation of primary excited fission fragments. Neutron and $\\gamma$-ray evaporations from fully accelerated fission fragments are calculated in competition at each stage of the decay, and the role of isomers in the fission products, before $\\beta$-decay, is analyzed. The time evolution of the average total $\\gamma$-ray energy, average total $\\gamma$-ray multiplicity, and fragment-specific $\\gamma$-ray spectra, is presented in the case of neutron-induced fission reactions of $^{235}$U and $^{239}$Pu, as well as spontaneous fission of $^{252}$Cf. The production of specific isomeric states is calculated and compared to available experimental data. About 7% of all prompt fission $\\gamma$ rays are predicted to be emitted between 10 nsec and 5 $\\mu$sec following fission, in the case of $^{235}$U and $^{239}$Pu $(n_{\\rm th},f)$ reactio...

  7. The Gamma-Ray View of the Extragalactic Background Light

    CERN Document Server

    Finke, Justin D

    2010-01-01

    The Extragalactic Background Light (EBL) from the infrared (IR) through the ultraviolet (UV) is dominated by emission from stars, either directly or through absorption and reradiation by dust. It can thus give information on the star formation history of the universe. However, it is difficult to measure directly due to foreground radiation fields from the Galaxy and solar system. Gamma-rays from extragalactic sources at cosmological distances (blazars and gamma-ray bursts) interact with EBL photons creating electron-positron pairs, absorbing the gamma-rays. Given the intrinsic gamma-ray spectrum of a source and its redshift, the EBL can in principle be measured. However, the intrinsic gamma-ray spectra of blazars and GRBs can vary considerably from source to source and the from the same source over short timescales. A maximum intrinsic spectrum can be assumed from theoretical grounds, to give upper limits on the EBL absorption from blazars at low redshift with very high energy (VHE) gamma-ray observations wit...

  8. Dark Gamma Ray Bursts

    OpenAIRE

    Brdar, Vedran; Kopp, Joachim; Liu, Jia

    2016-01-01

    Many theories of dark matter (DM) predict that DM particles can be captured by stars via scattering on ordinary matter. They subsequently condense into a DM core close to the center of the star and eventually annihilate. In this work, we trace DM capture and annihilation rates throughout the life of a massive star and show that this evolution culminates in an intense annihilation burst coincident with the death of the star in a core collapse supernova. The reason is that, along with the stell...

  9. Are Gamma-ray Bursts Universal?

    OpenAIRE

    Eichler, David; Levinson, Amir

    2006-01-01

    It is noted that the Liang-Zhang correlation can be accounted for with the viewing angle interpretation proposed earlier. The Ghirlanda correlation, recently generalized by Nava et al (2006) to a wind profile, can be accounted for by the viewing angle interpretation accordingly generalized to a wind profile. Most of the scatter in the spectra and time-integrated brightness in $\\gamma$-ray bursts (GRB) can thus be accounted for by variation in two parameters, 1) the viewing angle and 2) the je...

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

    International Nuclear Information System (INIS)

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

  11. Study of X-Ray and $\\gamma$-Ray Spectra from Antiprotonic Atoms at the Slowly Extracted Antiproton Beam of LEAR

    CERN Multimedia

    2002-01-01

    This experiment will study the X-ray spectra of antiprotonic atoms and the $\\gamma$ spectra of residual nuclei after the antiproton absorption. We intend to begin with measurements on selected isotopically pure targets. Strong interaction effects, the antiproton absorption and the atomic cascade are analysed through the measurement of energies, lineshapes, relative and absolute intensities of all observable lines. The experiments are continued to determine st in resolved fine structure levels and in different isotopes of the same element. Coincidence techniques may be applied. All components of the experimental set-up are already existing from previous experiments and we could begin the measurements with any slowly extracted beam of low energy at LEAR.

  12. Gamma-ray Imaging Methods

    Energy Technology Data Exchange (ETDEWEB)

    Vetter, K; Mihailescu, L; Nelson, K; Valentine, J; Wright, D

    2006-10-05

    In this document we discuss specific implementations for gamma-ray imaging instruments including the principle of operation and describe systems which have been built and demonstrated as well as systems currently under development. There are several fundamentally different technologies each with specific operational requirements and performance trade offs. We provide an overview of the different gamma-ray imaging techniques and briefly discuss challenges and limitations associated with each modality (in the appendix we give detailed descriptions of specific implementations for many of these technologies). In Section 3 we summarize the performance and operational aspects in tabular form as an aid for comparing technologies and mapping technologies to potential applications.

  13. Neutron capture prompt gamma-ray analysis of stratospheric and groundfall ash following the Mt. St. Helens eruption of May 18, 1980

    International Nuclear Information System (INIS)

    Neutron-capture prompt γ-ray activation analysis (PGAA) is an exceptionally good method for the determination of the major and minor elements Na, Mg, Al, Si, K, Ca, Ti, Mn and Fe in most geological matrices. The trace elements H, B, S, Cl, Cd, Sm and Gd can often be readily measured in most geological materials. This technique was applied to volcanic ash samples collected in Washington and Montana by various groups following the May 18 eruption of the Mt. St. Helens volcano, as well as to several particulate samples collected at altitudes between 13 and 18 km by a NASA U-2 research aircraft. Groundfall ash samples show distinct elemental variations versus distance from the volcano. Samples collected sequentially at a given location also exhibit variations in the elemental ratios. These sequential samples were also subjected to leaching studies to determine soluble B, Cl and S. On the average, PGAA is able to account for 99.4+-1.7% of the mass of each sample. The PGAA results indicate that the sample from the greatest altitude resembles ashfall near the volcano, while those at lower altitudes somewhat resemble more distant ashfall. (author)

  14. Measurement and analysis of neutron and gamma-ray flux spectra in a neutronics mock-up of the HCPB Test Blanket Module

    International Nuclear Information System (INIS)

    Neutron and γ-ray flux spectra were measured with a NE 213 spectrometer in the rear block of a mock-up of the HCPB Test Blanket Module. The flux of the slow neutrons was investigated by time-of-arrival spectroscopy with a pulsed D-T neutron source. The experimental results were compared versus calculations performed with the Monte Carlo code MCNP and the data libraries EFF-3, FENDL-2.0 and FENDL-2.1, and are discussed with respect to the shielding capability of the TBM and to tritium breeding

  15. SU-E-J-100: Reconstruction of Prompt Gamma Ray Three Dimensional SPECT Image From Boron Neutron Capture Therapy(BNCT)

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, D; Jung, J; Suh, T [The Catholic University of Korea, College of medicine, Department of biomedical engineering (Korea, Republic of)

    2014-06-01

    Purpose: Purpose of paper is to confirm the feasibility of acquisition of three dimensional single photon emission computed tomography (SPECT) image from boron neutron capture therapy (BNCT) using Monte Carlo simulation. Methods: In case of simulation, the pixelated SPECT detector, collimator and phantom were simulated using Monte Carlo n particle extended (MCNPX) simulation tool. A thermal neutron source (<1 eV) was used to react with the boron uptake region (BUR) in the phantom. Each geometry had a spherical pattern, and three different BURs (A, B and C region, density: 2.08 g/cm3) were located in the middle of the brain phantom. The data from 128 projections for each sorting process were used to achieve image reconstruction. The ordered subset expectation maximization (OSEM) reconstruction algorithm was used to obtain a tomographic image with eight subsets and five iterations. The receiver operating characteristic (ROC) curve analysis was used to evaluate the geometric accuracy of reconstructed image. Results: The OSEM image was compared with the original phantom pattern image. The area under the curve (AUC) was calculated as the gross area under each ROC curve. The three calculated AUC values were 0.738 (A region), 0.623 (B region), and 0.817 (C region). The differences between length of centers of two boron regions and distance of maximum count points were 0.3 cm, 1.6 cm and 1.4 cm. Conclusion: The possibility of extracting a 3D BNCT SPECT image was confirmed using the Monte Carlo simulation and OSEM algorithm. The prospects for obtaining an actual BNCT SPECT image were estimated from the quality of the simulated image and the simulation conditions. When multiple tumor region should be treated using the BNCT, a reasonable model to determine how many useful images can be obtained from the SPECT could be provided to the BNCT facilities. This research was supported by the Leading Foreign Research Institute Recruitment Program through the National Research

  16. SU-E-J-100: Reconstruction of Prompt Gamma Ray Three Dimensional SPECT Image From Boron Neutron Capture Therapy(BNCT)

    International Nuclear Information System (INIS)

    Purpose: Purpose of paper is to confirm the feasibility of acquisition of three dimensional single photon emission computed tomography (SPECT) image from boron neutron capture therapy (BNCT) using Monte Carlo simulation. Methods: In case of simulation, the pixelated SPECT detector, collimator and phantom were simulated using Monte Carlo n particle extended (MCNPX) simulation tool. A thermal neutron source (<1 eV) was used to react with the boron uptake region (BUR) in the phantom. Each geometry had a spherical pattern, and three different BURs (A, B and C region, density: 2.08 g/cm3) were located in the middle of the brain phantom. The data from 128 projections for each sorting process were used to achieve image reconstruction. The ordered subset expectation maximization (OSEM) reconstruction algorithm was used to obtain a tomographic image with eight subsets and five iterations. The receiver operating characteristic (ROC) curve analysis was used to evaluate the geometric accuracy of reconstructed image. Results: The OSEM image was compared with the original phantom pattern image. The area under the curve (AUC) was calculated as the gross area under each ROC curve. The three calculated AUC values were 0.738 (A region), 0.623 (B region), and 0.817 (C region). The differences between length of centers of two boron regions and distance of maximum count points were 0.3 cm, 1.6 cm and 1.4 cm. Conclusion: The possibility of extracting a 3D BNCT SPECT image was confirmed using the Monte Carlo simulation and OSEM algorithm. The prospects for obtaining an actual BNCT SPECT image were estimated from the quality of the simulated image and the simulation conditions. When multiple tumor region should be treated using the BNCT, a reasonable model to determine how many useful images can be obtained from the SPECT could be provided to the BNCT facilities. This research was supported by the Leading Foreign Research Institute Recruitment Program through the National Research

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

    International Nuclear Information System (INIS)

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

  18. Dark Gamma Ray Bursts

    CERN Document Server

    Brdar, Vedran; Liu, Jia

    2016-01-01

    Many theories of dark matter (DM) predict that DM particles can be captured by stars via scattering on ordinary matter. They subsequently condense into a DM core close to the center of the star and eventually annihilate. In this work, we trace DM capture and annihilation rates throughout the life of a massive star and show that this evolution culminates in an intense annihilation burst coincident with the death of the star in a core collapse supernova. The reason is that, along with the stellar interior, also its DM core heats up and contracts, so that the DM density increases rapidly during the final stages of stellar evolution. We argue that, counterintuitively, the annihilation burst is more intense if DM annihilation is a p-wave process than for s-wave annihilation because in the former case, more DM particles survive until the supernova. If among the DM annihilation products are particles like dark photons that can escape the exploding star and decay to Standard Model particles later, the annihilation bu...

  19. The GRAD gamma ray spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Rester, A.C.; Piercey, R.B.; Eichhorn, G.; Coldwell, R.L.; McKisson, J.M.; Ely, D.W.; Mann, H.M.; Jenkins, D.A.

    1986-02-01

    A gamma-ray spectrometer for an upcoming space shuttle mission is described. Consisting of a 150 cm/sup 3/ n-type germanium detector set inside active shielding of bismuth germanate and plastic scintillator, the instrument will be used in studies of the Orbiter background and the galactic center.

  20. The GRAD gamma ray spectrometer

    International Nuclear Information System (INIS)

    A gamma-ray spectrometer for an upcoming space shuttle mission is described. Consisting of a 150 cm3 n-type germanium detector set inside active shielding of bismuth germanate and plastic scintillator, the instrument will be used in studies of the Orbiter background and the galactic center

  1. Short duration gamma ray bursts

    Indian Academy of Sciences (India)

    Patrick Das Gupta

    2004-10-01

    After a short review of gamma ray bursts (GRBs), we discuss the physical implications of strong statistical correlations seen among some of the parameters of short duration bursts (90 < 2 s). Finally, we conclude with a brief sketch of a new unified model for long and short GRBs.

  2. Gamma ray slush hydrogen monitor

    Science.gov (United States)

    Singh, Jag J.; Shen, Chih-Peng; Sprinkle, Danny R.

    1992-01-01

    Mass attenuation for 109Cd radiation have been measured in mixtures of phases and in single phases of five chemical compounds. As anticipated, the mass attenuation coefficients are independent of the phases of the test chemicals. It is recommended that a slush hydrogen monitoring system based on low energy gamma ray attenuation be developed for utilization aboard the NASP.

  3. Periodicities in gamma ray bursts

    International Nuclear Information System (INIS)

    Gamma ray burst models based on magnetic neutron stars face a problem of account for the scarcity of observed periods. Both this scarcity and the typical period found when any is detected are explained if the neutron stars are accreting in binary systems

  4. Remote planetary geochemical exploration with the NEAR X-ray/gamma-ray spectrometer

    International Nuclear Information System (INIS)

    The X-ray/gamma-ray spectrometer (XGRS) instrument onboard the Near Earth Asteroid Rendezvous (NEAR) spacecraft will map asteroid 433 Eros in the 0.2 keV to 10 MeV energy region. Measurements of the discrete line X-ray and gamma-ray emissions in this energy domain can be used to obtain both qualitative and quantitative elemental composition maps of the asteroid surface. The NEAR X-ray/gamma-ray spectrometer (XGRS) was turned on for the first time during the week of 7 April 1996. Rendezvous with Eros 433 is expected during December 1998. Observations of solar X-ray spectra during both quiescent and active periods have been made. A gamma-ray transient detection system has been implemented and about three gamma-ray transient events a week have been observed which are associated with either gamma-ray bursts or solar flares

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

    Science.gov (United States)

    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.

  6. The very high energy gamma ray spectra of IES 1959+650 and Mrk 421 as measured with the Whipple 10 m telescope

    International Nuclear Information System (INIS)

    In observations made with the Whipple 10 m telescope, 1ES 1959+650 (z 0.048) was caught in a high flaring state in May 2002, concurrent with a high X-ray state, and in June 2002, for which there was no corresponding X-ray flare. The spectra for both of those occasions are well fitted by a power law of differential spectral index ∼ -2.8. The relative stability of the spectral index for those flares argues strongly in favour of a two-component model as to the emission zones for the two radiation regimes.Markarian 421 (z = 0.031) was observed to be in a high flaring state, at levels of ≥ 3 Crab, during March and April 2004. The average spectrum over this time period shows evidence for a cut-off in the spectrum at ∼ 5 TeV, similar to a cut-off seen during an equivalently strong episode of flaring activity in 2001. The continued appearance of this feature indicates a long term stability, either in the physical conditions at the source, or in the intervening medium (such as attenuation on the extra-galactic infra-red background radiation)

  7. The Gamma-ray Sky with Fermi

    CERN Document Server

    Thompson, D J

    2013-01-01

    Gamma rays reveal extreme, nonthermal conditions in the Universe. The Fermi Gamma-ray Space Telescope has been exploring the gamma-ray sky for more than four years, enabling a search for powerful transients like gamma-ray bursts, solar flares, and flaring active galactic nuclei, as well as long-term studies including pulsars, binary systems, supernova remnants, and searches for predicted sources of gamma rays such as clusters of galaxies. Some results include a stringent limit on Lorentz invariance violation derived from a gamma-ray burst, unexpected gamma-ray variability from the Crab Nebula, a huge gamma-ray structure in the direction of the center of our Galaxy, and strong constraints on some Weakly Interacting Massive Particle (WIMP) models for dark matter.

  8. A new method for the reconstruction of very-high-energy gamma-ray spectra and application to galatic cosmic-ray accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Milton Virgilio

    2014-09-15

    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 HESSJ1646-458 (2.2 in size) towards the SC Westerlund 1 (Wd1) 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 HESSJ1646-458 with the SC is favoured, but cannot be confirmed. The SC Pismis 22 is located in the centre of the

  9. A new method for the reconstruction of very-high-energy gamma-ray spectra and application to galatic cosmic-ray accelerators

    International Nuclear Information System (INIS)

    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 HESSJ1646-458 (2.2 in size) towards the SC Westerlund 1 (Wd1) 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 HESSJ1646-458 with the SC is favoured, but cannot be confirmed. The SC Pismis 22 is located in the centre of the

  10. Gravitational microlensing of gamma-ray blazars

    DEFF Research Database (Denmark)

    F. Torres, Diego; E. Romero, Gustavo; F. Eiroa, Ernesto;

    2003-01-01

    We present a detailed study of the effects of gravitational microlensing on compact and distant $\\gamma$-ray blazars. These objects have $\\gamma$-ray emitting regions which are small enough as to be affected by microlensing effects produced by stars lying in intermediate galaxies. We analyze the...... galactic latitude whose gamma-ray statistical properties are very similar to detected $\\gamma$-ray blazars) are indeed the result of gravitational lensing magnification of background undetected Active Galactic Nuclei (AGNs)....

  11. Influence of gamma rays colimation on Mosbauer lines

    International Nuclear Information System (INIS)

    The effect of gamma rays collimation in Mossbauer absorption spectra was investigated when thin absorbers are used. A simple model is proposed to study shift and broadening of spectral lines. This model along with some approximations, makes the calculations easily done. The results are in good agreement with those in the literature. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Heath, R.L. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    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.

  13. Gammapy - A Python package for {\\gamma}-ray astronomy

    OpenAIRE

    Donath, Axel; Deil, Christoph; Arribas, Manuel Paz; King, Johannes; Owen, Ellis; Terrier, Régis; Reichardt, Ignasi; Harris, Jon; Bühler, Rolf; Klepser, Stefan

    2015-01-01

    In the past decade imaging atmospheric Cherenkov telescope arrays such as H.E.S.S., MAGIC, VERITAS, as well as the Fermi-LAT space telescope have provided us with detailed images and spectra of the gamma-ray universe for the first time. Currently the gamma-ray community is preparing to build the next-generation Cherenkov Telecope Array (CTA), which will be operated as an open observatory. Gammapy (available at https://github.com/gammapy/gammapy under the open-source BSD license) is a new in-d...

  14. Gammapy - A Python package for {\\gamma}-ray astronomy

    CERN Document Server

    Donath, Axel; Arribas, Manuel P; King, Johannes; Owen, Ellis; Terrier, Régis; Reichardt, Ignasi; Harris, Jon; Bühler, Rolf; Klepser, Stefan

    2015-01-01

    In the past decade imaging atmospheric Cherenkov telescope arrays such as H.E.S.S., MAGIC, VERITAS, as well as the Fermi-LAT space telescope have provided us with detailed images and spectra of the {\\gamma}-ray universe for the first time. Currently the {\\gamma}-ray community is preparing to build the next-generation Cherenkov Telecope Array (CTA), which will be operated as an open observatory. Gammapy (available at https://github.com/gammapy/gammapy under the open-source BSD li- cense) is a new in-development Astropy affiliated package for high-level analysis and simulation of astronomical {\\gamma}-ray data. It is built on the scientific Python stack (Numpy, Scipy, matplotlib and scikit-image) and makes use of other open-source astronomy packages such as Astropy, Sherpa and Naima to provide a flexible set of tools for {\\gamma}-ray astronomers. We present an overview of the current Gammapy features and example analyses on real as well as simulated {\\gamma}-ray datasets. We would like Gammapy to become a commu...

  15. The Fermi view of gamma-ray bursts

    Science.gov (United States)

    Axelsson, Magnus; Fermi/LAT Collaboration

    2015-08-01

    The Fermi mission has brought great advances in the study of GRBs. Over 1500 gamma-ray bursts (GRBs) have been detected by the Gamma-ray Burst Monitor (GBM), and more than 100 of these are also detected by the Fermi Large Area Telescope (LAT) above 30 MeV. These high-energy detections have revealed previously unknown features in GRB spectra, including additional components and spectral cut-offs, as well as delayed and long-lived GeV emission. Interpretation of these new features has proven to be a source of vigorous debate within the GRB community. I will review recent Fermi-LAT observations of GRBs, ranging from the detection of the long-lived GRB 130427A to the broad-band fits of simultaneous X-ray and gamma-ray data, and what they reveal about the origin of the high-energy emission from GRBs.

  16. Low-resolution gamma-ray measurements of process holdup

    International Nuclear Information System (INIS)

    Nuclear facilities worldwide have deposits of nuclear material remaining in processing equipment. Nuclear facilities need portable, automated tools based on gamma-ray spectroscopy to perform plant wide in situ assays of special nuclear materials (SNM) deposited in processing equipment. These tools have requirements to (1) acquire and manage several hundred spectra in an hour; (2) produce prompt and reliable quantitative analyses; (3) be self-powered, easily carried, and operated by one use; (4) accommodate varying degrees of user expertise; (5) correct for the effects of equipment variables; (6) tolerate facility variables such as temperature and equipment accessibility; and (7) accommodate the geometry of each measurement. this paper describes a new system for in-situ measurements consisting of a compact gamma-ray detector, a self-contained portable gamma-ray spectroscopy instrument, and a palm-size programmable control and data storage unit

  17. Multi - element determination by neutron - induced prompt gamma - ray analysis

    International Nuclear Information System (INIS)

    Prompt gamma neutron activation analysis ( PGNAA ) is an elemental and isotopic analytical technique in which prompt gamma - rays emitted within 10-14s after neutron capture reaction are measured. Although this analytical methodology is similar to instrumental neutron activation analysis (INAA), PGNAA is characterized by its capability for nondestructive multi - elemental analysis and by its ability to analyze elements that cannot be determined by INAA. In addition, due to the negligibly low residual radioactivity after being analyzed by PGNAA, the same sample can be used for other analytical methods. According to calculation, the analytical sensitivity of PGNAA is higher than that of INAA under the same neutron and gamma-ray measurement conditions. PGNAA technique is based on the interaction of the neutrons with the nuclei contained in a sample. Upon capturing a thermal neutron, a target nucleus gains energy which produces a compound nucleus in an excited state. This process may be represented as follows: AX + n → A+1 X * → A+1 X + γ, were A X is target and a+1 X are the target and compound nuclei, respectively. The compound nucleus is produced in excited state. The prompt gamma ray is emitted in the instantaneous decay of the compound nuclide. The neutron capture prompt gamma ray is usually emitted in less than 10-13 s. (author)

  18. Programs for the automatic gamma-ray measurement with CANBERRA 8100/QUANTA system

    International Nuclear Information System (INIS)

    Some programs have been prepared for the automatic operation of the CANBERRA 8100/QUANTA System for the gamma-ray spectrum measurement. The main parts of these programs are: (1) to collect and record on magnetic disks the data of gamma-ray spectra automatically, while the recorded data are analyzed to estimate the nuclides which generate photopeaks of spectra and to calculate those concentrations; (2) to draw plotted diagrams of pulse height distributions of gamma-ray spectra data and other data by the additional digital plotter; and etc. (author)

  19. Airborne gamma ray spectrometer surveying

    International Nuclear Information System (INIS)

    The International Atomic Energy Agency (IAEA) in its role as collector and disseminator of information on nuclear techniques has long had an interest in gamma ray spectrometer methods and has published a number of Technical Reports on various aspects of the subject. At an Advisory Group Meeting held in Vienna in November 1986 to review appropriate activities the IAEA could take following the Chernobyl accident, it was recommended that preparation begin on a new Technical Report on airborne gamma ray spectrometer surveying, taking into account the use of the technique for environmental monitoring as well as for nuclear emergency response requirements. Shortly thereafter the IAEA became the lead organization in the Radioelement Geochemical Mapping section of the International Geological Correlation Programme/United Nations Educational, Scientific and Cultural Organization (UNESCO) Project on International Geochemical Mapping. These two factors led to the preparation of the present Technical Report. 18 figs, 4 tabs

  20. Compton suppression gamma ray spectrometry

    International Nuclear Information System (INIS)

    In the past decade there have been many studies to use Compton suppression methods in routine neutron activation analysis as well as in the traditional role of low level gamma ray counting of environmental samples. On a separate path there have been many new PC based software packages that have been developed to enhance photopeak fitting. Although the newer PC based algorithms have had significant improvements, they still suffer from being effectively used in weak gamma ray lines in natural samples or in neutron activated samples that have very high Compton backgrounds. We have completed a series of experiments to show the usefulness of Compton suppression. As well we have shown the pitfalls when using Compton suppression methods for high counting deadtimes as in the case of neutron activated samples. We have also investigated if counting statistics are the same both suppressed and normal modes. Results are presented in four separate experiments. (author)

  1. Detector system for gamma-ray production cross section measurements and data analysis

    International Nuclear Information System (INIS)

    A detector system for double-differential gamma-ray production cross section measurements has been installed in the JAERI Tandem Accelerator and data analysis computer codes have been developed. Gamma-ray pulse-height spectra have been measured by a 3'' dia. x 6'' anti-Compton NaI(Tl) detector. Response matrix of the detector has been obtained and evaluated by some pulse-height spectra using standard gamma-ray sources and reaction gamma-rays such as 12C(n, n'γ), 16O(n, n'γ), 27Al(p, γ), and 19F(p, αγ). Gamma-ray production cross sections have been deduced by means of the unfolding and normalization of neutron flux and number of sample atoms. In this report, outline of the detector system and process of data analysis have been presented. (author)

  2. Neutrinos from Gamma Ray Bursts

    CERN Document Server

    Mannheim, K

    2000-01-01

    The observed fluxes of cosmic rays and gamma rays are used to infer the maximum allowed high-energy neutrino flux allowed for Gamma Ray Bursts (GRBs), following Mannheim, Protheroe, and Rachen (2000). It is shown that if GRBs produce the ultrahigh-energy cosmic rays, they should contribute (a) at least 10% of the extragalactic gamma ray background between 3 MeV and 30 GeV, contrary to their observed energy flux which is only a minute fraction of this flux, and (b) a cumulative neutrino flux a factor of 20 below the AMANDA (Neutrino 2000) limit on isotropic neutrinos. This could have two implications, either GRBs do not produce the ultrahigh energy cosmic rays or that the GRBs are strongly beamed and emit most of their power at energies well above 100 GeV implausibly increasing the energy requirements, but consistent with the marginal detections of a few low-redshift GRBs by MILAGRITO, HEGRA-AIROBICC, and the Tibet-Array. All crucial measurements to test the models will be available in the next few years. Thes...

  3. A transportable source of gamma rays with discrete energies and wide range for calibration and on-site testing of gamma-ray detectors

    International Nuclear Information System (INIS)

    We describe a compact and transportable wide energy range, gamma-ray station for the calibration of gamma-ray sensitive devices. The station was specifically designed for the on-site testing and calibration of gamma-ray sensitive spacecraft payloads, intended for space flight on the BepiColombo and SoIar Orbiter missions of the European Space Agency. The source is intended to serve as a calibrated reference for post test center qualification of integrated payload instruments and for preflight evaluation of scientific radiation sensors. Discrete gamma rays in the energy range 100 keV–9 MeV are produced in the station with reasonable intensity using a radionuclide neutron source and 100 l of distilled water with 22 kg salt dissolved. The gamma-rays generated contain many discrete lines conveniently evenly distributed over the entire energy range. The neutron and gamma-ray fields have been simulated by Monte Carlo calculations. Results of the numerical calculations are given in the form of neutron and gamma-ray spectra as well as dose equivalent rate. The dose rate was also determined directly by dedicated dosemetric measurements. The gamma-ray field produced in the station was characterized using a conventional HPGe detector. The application of the station is demonstrated by measurements taken with a flight-qualified LaBr3:Ce scintillation detector. Gamma-ray spectra acquired by both detectors are presented. The minimum measuring times for calibration of the flight-version detector, was between 2 and 10 min (up to 6.2 MeV) and 20–30 min (up to 8 MeV), when the detector was placed at a distance 2–5 m from the station. - Highlights: • Transportable station of mono-energetic gamma rays has been built. • Produced neutron and gamma ray field simulated by Monte Carlo calculations. • Discrete gamma rays produced in wide energy range up to 9 MeV. • Produced gamma ray spectra measured by HPGe and scintillating LaBr3Ce detectors. • Demonstration of application

  4. The BATSE 5B Gamma-Ray Burst Spectral Catalog

    OpenAIRE

    Goldstein, A.; Preece, R.D.; Mallozzi, R. S.; Briggs, M S; Fishman, G. J.; C. Kouveliotou(NASA/Marshall Space Flight Center, United States); Pacieses, W. S.; Burgess, J. M.

    2013-01-01

    We present systematic spectral analyses of GRBs detected with the Burst and Transient Source Experiment (BATSE) onboard the Compton Gamma-Ray Observatory (CGRO) during its entire nine years of operation. This catalog contains two types of spectra extracted from 2145 GRBs and fitted with five different spectral models resulting in a compendium of over 19000 spectra. The models were selected based on their empirical importance to the spectral shape of many GRBs, and the analysis performed was d...

  5. Discuss the information of gamma-ray spectrum about uranium metallogenesis

    International Nuclear Information System (INIS)

    Information of gamma-ray spectrum indicates the Uranium deposits directly, information of gamma-ray spectrum is radioactive nuclides which calculated by the gamma-ray spectrum, also including ratios of nuclides, combinations of nuclides and so on. For the analysis of the spectra, in practice two methods are used: peak or window analysis and full spectrum analysis. Precondition of spectra processing is how to reduce the statistic noise, base of spectrum anomaly analysis is how to distinguish anomaly lower limit of gamma-ray spectrum. Extracted the gamma-ray spectrum anomaly information of nuclides ratios, activated uranium, residual uranium, uranium enrichment coefficient, gamma-ray spectrum coefficient, using average add twice standard deviation, by comprehensive analysis gamma-ray spectrum information, geology, aeromagnetic, geochemistry and remote sensing information, selected 30 information layers as evidence weight factors, the uranium potential is calculated by evidence weight model and 7 levels targets care selected, the result has shown that the gamma-ray spectrum information is helpful to predicate uranium resources. (authors)

  6. The GAMMA-400 gamma-ray telescope characteristics. Angular resolution and electrons/protons separation

    CERN Document Server

    Leonov, A A; Bonvicini, V; Topchiev, N P; Adriani, 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; Boyarchuk, K A; 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; Popov, A V; Rappoldi, A; Ricciarini, S; Runtso, M F; Ryde, F; Serdin, O V; Sparvoli, R; Spillantini, P; Suchkov, S I; Tavani, M; Taraskin, A A; 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

    2014-01-01

    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 implemented by the specially designed GAMMA-400 gamma-ray telescope, concern with the following broad range of science topics. Searching for signatures of dark matter, surveying the celestial sphere in order to study gamma-ray point and extended sources, measuring the energy spectra of Galactic and extragalactic diffuse gamma-ray emission, studying gamma-ray bursts and gamma-ray emission from the Sun, as well as high precision measuring 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 of ~1% and angular resolution better than 0.02 deg. The methods developed to reconstru...

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

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, A.A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; Ajello, M.; /SLAC; Anderson, B.; Atwood, W.B.; /UC, Santa Cruz; Axelsson, M.; /Stockholm U. /Stockholm U., OKC; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, G.; /INFN, Trieste /Trieste U.; Bastieri, D.; /INFN, Padua /Padua U.; Baughman, B.M.; /Taiwan, Natl. Taiwan U. /Ohio State U.; Bechtol, K.; /SLAC; Bellazzini, R.; /INFN, Pisa; Berenji, B.; Blandford, R.D.; Bloom, E.D.; /SLAC; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /SLAC; Bregeon, J.; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari /Ecole Polytechnique /Washington U., Seattle /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /IASF, Milan /DAPNIA, Saclay /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /Naval Research Lab, Wash., D.C. /George Mason U. /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /Montpellier U. /Stockholm U. /Stockholm U., OKC /Royal Inst. Tech., Stockholm /Padua U. /Naval Research Lab, Wash., D.C. /Udine U. /INFN, Trieste /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /INFN, Pisa /UC, Santa Cruz /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /CENBG, Gradignan /CENBG, Gradignan /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /Montpellier U. /Bari U. /INFN, Bari /Ecole Polytechnique /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /Udine U. /INFN, Trieste /Hiroshima U. /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /Bari U. /INFN, Bari /INFN, Pisa /INFN, Bari /NASA, Goddard /Maryland U.; /more authors..

    2012-04-11

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

  8. CONTRIBUTION OF GAMMA-RAY-LOUD RADIO GALAXIES' CORE EMISSIONS TO THE COSMIC MeV AND GeV GAMMA-RAY BACKGROUND RADIATION

    International Nuclear Information System (INIS)

    The Fermi gamma-ray satellite has recently detected gamma-ray emissions from radio galaxy cores. From these samples, we first examine the correlation between the luminosities at 5 GHz, L5GHz, and at 0.1-10 GeV, Lγ, of gamma-ray-loud radio galaxies. We find that the correlation is significant with Lγ∝L1.165GHz based on a partial correlation analysis. Using this correlation and the radio luminosity function (RLF) of radio galaxies, we explore the contribution of gamma-ray-loud radio galaxies to the unresolved extragalactic gamma-ray background (EGRB). The gamma-ray luminosity function is obtained by normalizing the RLF to reproduce the source-count distribution of the Fermi gamma-ray-loud radio galaxies. We find that gamma-ray-loud radio galaxies can explain ∼25% of the unresolved Fermi EGRB flux above 100 MeV and will also make a significant contribution to the EGRB in the 1-30 MeV energy band. Since blazars explain 22% of the EGRB above 100 MeV, radio-loud active galactic nucleus populations explain ∼47% of the unresolved EGRB. We further make an interpretation on the origin of the EGRB. The observed EGRB spectrum at 0.2-100 GeV does not show an absorption signature by the extragalactic background light. Thus, the dominant population of the origin of EGRB at very high energy (>30 GeV) might be either nearby gamma-ray-emitting sources or sources with very hard gamma-ray spectra.

  9. Neutron Capture Experiments Using the DANCE Array at Los Alamos

    International Nuclear Information System (INIS)

    The Detector for Advanced Neutron Capture Experiments (DANCE) is designed for neutron capture measurements on very small and/or radioactive targets. The DANCE array of 160 BaF2 scintillation detectors is located at the Lujan Center at the Los Alamos Neutron Science Center (LANSCE). Accurate measurements of neutron capture data are important for many current applications as well as for basic understanding of neutron capture. The gamma rays following neutron capture reactions have been studied by the time-of-flight technique using the DANCE array. The high granularity of the array allows measurements of the gamma-ray multiplicity. The gamma-ray multiplicities and energy spectra for different multiplicities can be measured and analyzed for spin and parity determination of the resolved resonances.

  10. Gamma ray source studies using muon tracking

    International Nuclear Information System (INIS)

    A large area (128 m2) streamer tube detector, located within the KASCADE-Grande experiment has been built. We discuss the possibility of observing gamma-ray sources by means of photo-pion produced single isolated muon tracks above the background of cosmic-ray muons using a muon tracking detector (MTD). Properties of the photo-production process in the atmosphere and of the MTD which support the identification of gammas are discussed. The sensitivity of the technique of observing the Crab energy spectrum in the tens of GeV range is discussed. Gamma spectra accumulated from Crab and a Mrk 421 flux correlation with X-ray (RXTE/PCA) are presented.

  11. Measurement and calculation of gamma ray transport in concrete

    International Nuclear Information System (INIS)

    A gamma-ray spectroscopy system using a 5-cm by 5-cm NE-213 organic scintillator was used for the measurement of gamma-ray pulse-height spectra behind four concrete slabs of different thickness. The pulse-height data was fed to the Tsing-Hua gamma-ray response matrix coupled with FORIST code to evaluate the experimental spectra. The experimental results were compared to ANISN discrete ordinates calculations. The ANISN calculations used DLC-23E data library with 22 neutron and 18 gamma-ray groups. The experimental and numerical results were in good agreement for 30 cm and 40 cm concrete slabs in the energy ranging from 0.1 MeV to 0.7 MeV, and large disagreement was evident for 10 cm and 20 cm slabs. The calculated fluxes overpredicted the measurements. At upper energies namely between 0.4 - 0.7 MeV, very good agreement was obtained for the four concrete slabs. The main source of disagreement was due to Tsing-Hua response matrix and poor modeling of one dimensional code. 36 Ref

  12. 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

    Science.gov (United States)

    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.

  13. Search of a prompt gamma ray for chlorine analysis in a Portland cement sample

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A. [Center for Applied Physical Sciences, King Fahd University of Petroleum and Minerals, Box 1815, Dhahran-31261 (Saudi Arabia)]. E-mail: annaqvi@kfupm.edu.sa; Nagadi, M.M. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia); Kidwai, S. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia); Khateeb-ur-Rehman [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia); Maslehuddin, M. [Center for Engineering Sciences, King Fahd University of Petroleum and Minerals, Dhahran-31261 (Saudi Arabia)

    2004-11-11

    Prompt Gamma Ray analysis of chlorine contaminated Portland cement samples have been carried out using an accelerator-based Prompt Gamma ray Neutron Activation Analysis setup. The chlorine concentration was measured over a range of 0.25-4 wt% using 1.165 MeV capture {gamma}-rays from chlorine. The experimental results were compared with the results of Monte Carlo simulations and an excellent agreement was observed between the two results. Further theoretical study has shown that yield of the 1.165 MeV prompt {gamma}-rays from chlorine is not very sensitive to variation in moisture contents of the Portland sample. An order of magnitude increase in sample moisture content resulted in only 16-20% increase in yield of 1.165 MeV prompt {gamma}-rays.

  14. A transportable source of gamma rays with discrete energies and wide range for calibration and on-site testing of gamma-ray detectors

    Science.gov (United States)

    Granja, Carlos; Slavicek, Tomas; Kroupa, Martin; Owens, Alan; Pospisil, Stanislav; Janout, Zdenek; Kralik, Miloslav; Solc, Jaroslav; Valach, Ondrej

    2015-01-01

    We describe a compact and transportable wide energy range, gamma-ray station for the calibration of gamma-ray sensitive devices. The station was specifically designed for the on-site testing and calibration of gamma-ray sensitive spacecraft payloads, intended for space flight on the BepiColombo and SoIar Orbiter missions of the European Space Agency. The source is intended to serve as a calibrated reference for post test center qualification of integrated payload instruments and for preflight evaluation of scientific radiation sensors. Discrete gamma rays in the energy range 100 keV-9 MeV are produced in the station with reasonable intensity using a radionuclide neutron source and 100 l of distilled water with 22 kg salt dissolved. The gamma-rays generated contain many discrete lines conveniently evenly distributed over the entire energy range. The neutron and gamma-ray fields have been simulated by Monte Carlo calculations. Results of the numerical calculations are given in the form of neutron and gamma-ray spectra as well as dose equivalent rate. The dose rate was also determined directly by dedicated dosemetric measurements. The gamma-ray field produced in the station was characterized using a conventional HPGe detector. The application of the station is demonstrated by measurements taken with a flight-qualified LaBr3:Ce scintillation detector. Gamma-ray spectra acquired by both detectors are presented. The minimum measuring times for calibration of the flight-version detector, was between 2 and 10 min (up to 6.2 MeV) and 20-30 min (up to 8 MeV), when the detector was placed at a distance 2-5 m from the station.

  15. Gamma-ray observations of supernova SN1987A by the balloonborne gamma-ray advanced detector

    International Nuclear Information System (INIS)

    On 8 January 1988, gamma-ray advanced detector (GRAD) supernova observer was launched on a 3.3 x 105 cubic meter helium balloon from Williams Field. The instrument maintained a float altitude of 36 kilometers as it drifted eastward along the 78 degrees S parallel until it was brought down 320 kilometers east of Vostak Station on 10 January and recovered on 13 January. High-energy resolution gamma-ray spectra of the supernova SN1987A were taken; it is hoped that these spectra will provide evidence of explosive nucleosynthesis of the heavy elements in the supernova. Results. The earliest results of the analysis, showed evidence of gamma rays from the radioactive decay of the isotope cobalt-56, the longer-lived daughter of short-lived nickel-56, which was expected to be produced in great abundance in the supernova explosion, but the cobalt-56 line appearing most clearly in the supernova spectrum-the 1,238-kiloelectronvolt gamma-ray--was apparently split into two doppler-shifted and broadened components. This astonishing result appeared to suggest that the mantle of the supernova had expanded asymmetrically with a velocity in excess of 3,000 kilometers per second

  16. Gamma-ray observations of supernova SN1987A by the balloonborne gamma-ray advanced detector

    Energy Technology Data Exchange (ETDEWEB)

    Coldwell, R.L.; Rester, A.C. (Univ. of Florida, Alachua (USA)); Eichhorn, G. (Univ. of Florida, Gainesville (USA)); Starr, R.; Trombka, J.I. (Goddard Space Flight Center, Greenbelt, MD (USA)); Lasche, G.P. (Defense Advanced Research Projects Agency, Arlington, VA (USA))

    1988-01-01

    On 8 January 1988, gamma-ray advanced detector (GRAD) supernova observer was launched on a 3.3 x 10{sup 5} cubic meter helium balloon from Williams Field. The instrument maintained a float altitude of 36 kilometers as it drifted eastward along the 78{degrees}S parallel until it was brought down 320 kilometers east of Vostak Station on 10 January and recovered on 13 January. High-energy resolution gamma-ray spectra of the supernova SN1987A were taken; it is hoped that these spectra will provide evidence of explosive nucleosynthesis of the heavy elements in the supernova. Results. The earliest results of the analysis, showed evidence of gamma rays from the radioactive decay of the isotope cobalt-56, the longer-lived daughter of short-lived nickel-56, which was expected to be produced in great abundance in the supernova explosion, but the cobalt-56 line appearing most clearly in the supernova spectrum-the 1,238-kiloelectronvolt gamma-ray--was apparently split into two doppler-shifted and broadened components. This astonishing result appeared to suggest that the mantle of the supernova had expanded asymmetrically with a velocity in excess of 3,000 kilometers per second.

  17. Monitoring the Low-Energy Gamma-Ray Sky Using Earth Occultation with GLAST GBM

    Science.gov (United States)

    Case, G.; Wilson-Hodge, C.; Cherry, M.; Kippen, M.; Ling, J.; Radocinski, R.; Wheaton, W.

    2007-01-01

    Long term all-sky monitoring of the 20 keV - 2 MeV gamma-ray sky using the Earth occultation technique was demonstrated by the BATSE instrument on the Compton Gamma Ray Observatory. The principles and techniques used for the development of an end-to-end earth occultation data analysis system for BATSE can be extended to the GLAST Gamma-ray Burst Monitor (GBM), resulting in multiband light curves and time-resolved spectra in the energy range 8 keV to above 1 MeV for known gamma-ray sources and transient outbursts, as well as the discovery of new sources of gamma-ray emission. In this paper we describe the application of the technique to the GBM. We also present the expected sensitivity for the GBM.

  18. The Redshift Dependence of Gamma-Ray Absorption in the Environments of Strong-Line AGNs

    Energy Technology Data Exchange (ETDEWEB)

    Reimer, A.; /Stanford U., HEPL /KIPAC, Menlo Park

    2007-11-12

    The case of {gamma}-ray absorption due to photon-photon pair production of jet photons in the external photon environments, such as the accretion disk and the broad-line region radiation fields, of {gamma}-ray--loud active galactic nuclei (AGNs) that exhibit strong emission lines is considered. I demonstrate that this 'local opacity,' if detected, will almost unavoidably be redshift-dependent in the sub-TeV range. This introduces nonnegligible biases and complicates approaches for studying the evolution of the extragalactic background light with contemporary GeV instruments such as the Gamma-Ray Large Area Space Telescope (GLAST ), where the {gamma}-ray horizon is probed by means of statistical analysis of absorption features (e.g., the Fazio-Stecker relation) in AGN spectra at various redshifts. It particularly applies to strong-line quasars, where external photon fields are potentially involved in {gamma}-ray production.

  19. Recommended standards for gamma ray intensities

    Energy Technology Data Exchange (ETDEWEB)

    Bé, Marie-Martine, E-mail: mmbe@cea.fr [LNHB, CEA LIST Saclay, 91191 Gif-sur-Yvette Cedex (France); Chechev, Valery P. [KRI, V.G. Khlopin Radium Institute, St. Petersburg 194021 (Russian Federation)

    2013-11-11

    Gamma ray data are used in more and more areas of application, and so over the years the demand for recommended gamma ray energies and intensities has increased. This paper proposes a list of gamma rays whose intensity is sufficiently well-known and they can be used for the calibration of gamma ray spectrometers and other applications; it is based on studies carried out by an international group of evaluators: the Decay Data Evaluation Project. One goal of this paper is to gather this set of data together in order to facilitate and generalize their use. In the first part, a brief description of the methodology followed throughout the evaluations is given, different methods of gamma ray intensity evaluation are presented, some typical examples of evaluations are shown; in the second part, the list of chosen nuclides is given along with their applications, and finally a list of recommended gamma ray intensities is presented.

  20. Gamma-ray burst polarimeter (GAP)

    International Nuclear Information System (INIS)

    The gamma-ray burst polarimeter (GAP: GAmma-ray burst Polarimeter), which had been almost handcrafted by scientists, has succeeded in working normally in interplanetary space, and in detecting the polarization of the gamma-ray from a mysterious astronomical object 'gamma-ray burst'. It is the first result of the detectors in the world exclusively aiming at detecting gamma-ray polarization. We mainly describe the hardware of our GAP equipment and show the method of preparing equipment to work in the cosmic space with a tight budget. The mechanical structure, the electronic circuits, the software on the equipment, the data analysis on the earth, and the scientific results gained by the observation just over one year, are presented after explaining the principle of gamma-ray polarization detection. Our design to protect equipment against mechanical shock and cosmic radiation may provide useful information for future preparation of compact satellite. (J.P.N.)

  1. Mining Gamma-Ray Burst Data

    OpenAIRE

    Hakkila, Jon; Roiger, Richard J.; Haglin, David J.; Mallozzi, Robert S.; Pendleton, Geoffrey N.; Meegan, Charles A.

    2000-01-01

    Gamma-ray bursts provide what is probably one of the messiest of all astrophysical data sets. Burst class properties are indistinct, as overlapping characteristics of individual bursts are convolved with effects of instrumental and sampling biases. Despite these complexities, data mining techniques have allowed new insights to be made about gamma-ray burst data. We demonstrate how data mining techniques have simultaneously allowed us to learn about gamma-ray burst detectors and data collectio...

  2. Gamma-Ray Astronomy Technology Needs

    Science.gov (United States)

    Gehrels, N.; Cannizzo, J. K.

    2012-01-01

    In recent decades gamma-ray observations have become a valuable tool for studying the universe. Progress made in diverse 8re1lS such as gamma-ray bursts (GRBs), nucleosynthesis, and active galactic nuclei (AGNs) has complimented and enriched our astrophysical understanding in many ways. We present an overview of current and future planned space y-ray missions and discussion technology needs for- the next generation of space gamma-ray instruments.

  3. New possibilities for improving the accuracy of parameter calculations for cascade gamma-ray decay of heavy nuclei

    CERN Document Server

    Sukhovoj, A M; Khitrov, V A

    2001-01-01

    The level density and radiative strength functions which accurately reproduce the experimental intensity of two- step cascades after thermal neutron capture and the total radiative widths of the compound states were applied to calculate the total gamma-ray spectra from the (n,gamma) reaction. In some cases, analysis showed far better agreement with experiment and gave insight into possible ways in which these parameters need to be corrected for further improvement of calculation accuracy for the cascade gamma-decay of heavy nuclei.

  4. Experiment Signal for Gamma-Ray Research of the Sun

    Science.gov (United States)

    Galper, Arkady; Arkhangelskaja, Irene; Arkhangelsky, Andrey; Shustov, Alexander; Ulin, Sergey; Novikov, Alexander; Grachev, Viktor; Uteshev, Ziyaetdin; Petrenko, Denis; Vlasik, Konstantin; Krivova, Kira; Dmitrenko, Valery; Chernysheva, Irina

    Description as well as physical and technical characteristics of Scientific Instrument (SI) “Signal” are presented. This equipment will be installed onboard the spacecraft (SC) “Interhelioprobe” for researching the Sun and Heliosphere at close distance. “Signal” will be developed for study cosmic gamma-rays. It consists of Xenon Gamma-Spectrometer (XeGS), the anticoincidence scintillation system and the digital electronic module. XeGS is based on cylindrical pulse ionization chamber with Frisch grid filled with high pressure xenon. Anticoincidence system will be made of polystyrene organic scintillator and silicon photomultipliers. Digital electronic module provides analyzing and data processing, collecting measured gamma-ray spectra and communication with onboard systems of SC “Interhelioprobe”. Main “Signal” scientific tasks are: begin{itemize} Research of X-ray and gamma emission in lines and continuum in energy range 30 keV - 5 MeV; begin{itemize} Study of gamma-ray bursts with Galactic and Metagalactic origin; begin{itemize} Analysis of gamma-ray lines near the Earth and Venus; begin{itemize} Charged particle fluxes registration along the spacecraft trajectory.

  5. An optimum analysis sequence for environmental gamma-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    De la Torre, F.; Rios M, C.; Ruvalcaba A, M. G.; Mireles G, F.; Saucedo A, S.; Davila R, I.; Pinedo, J. L., E-mail: fta777@hotmail.co [Universidad Autonoma de Zacatecas, Centro Regional de Estudis Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2010-10-15

    This work aims to obtain an optimum analysis sequence for environmental gamma-ray spectroscopy by means of Genie 2000 (Canberra). Twenty different analysis sequences were customized using different peak area percentages and different algorithms for: 1) peak finding, and 2) peak area determination, and with or without the use of a library -based on evaluated nuclear data- of common gamma-ray emitters in environmental samples. The use of an optimum analysis sequence with certified nuclear information avoids the problems originated by the significant variations in out-of-date nuclear parameters of commercial software libraries. Interference-free gamma ray energies with absolute emission probabilities greater than 3.75% were included in the customized library. The gamma-ray spectroscopy system (based on a Ge Re-3522 Canberra detector) was calibrated both in energy and shape by means of the IAEA-2002 reference spectra for software intercomparison. To test the performance of the analysis sequences, the IAEA-2002 reference spectrum was used. The z-score and the reduced {chi}{sup 2} criteria were used to determine the optimum analysis sequence. The results show an appreciable variation in the peak area determinations and their corresponding uncertainties. Particularly, the combination of second derivative peak locate with simple peak area integration algorithms provides the greater accuracy. Lower accuracy comes from the combination of library directed peak locate algorithm and Genie's Gamma-M peak area determination. (Author)

  6. An optimum analysis sequence for environmental gamma-ray spectrometry

    International Nuclear Information System (INIS)

    This work aims to obtain an optimum analysis sequence for environmental gamma-ray spectroscopy by means of Genie 2000 (Canberra). Twenty different analysis sequences were customized using different peak area percentages and different algorithms for: 1) peak finding, and 2) peak area determination, and with or without the use of a library -based on evaluated nuclear data- of common gamma-ray emitters in environmental samples. The use of an optimum analysis sequence with certified nuclear information avoids the problems originated by the significant variations in out-of-date nuclear parameters of commercial software libraries. Interference-free gamma ray energies with absolute emission probabilities greater than 3.75% were included in the customized library. The gamma-ray spectroscopy system (based on a Ge Re-3522 Canberra detector) was calibrated both in energy and shape by means of the IAEA-2002 reference spectra for software intercomparison. To test the performance of the analysis sequences, the IAEA-2002 reference spectrum was used. The z-score and the reduced χ2 criteria were used to determine the optimum analysis sequence. The results show an appreciable variation in the peak area determinations and their corresponding uncertainties. Particularly, the combination of second derivative peak locate with simple peak area integration algorithms provides the greater accuracy. Lower accuracy comes from the combination of library directed peak locate algorithm and Genie's Gamma-M peak area determination. (Author)

  7. A gamma-ray spectrometer system for fusion applications

    CERN Document Server

    Esposito, B; Kaschuck, Y A; Martin-Solis, J R; Portnov, D V

    2002-01-01

    A NaI scintillator spectrometer system for the measurement of gamma-ray spectra in tokamak discharges has been developed and installed on the Frascati Tokamak Upgrade. Two NaI scintillators are viewing the plasma at two different angles with respect to the equatorial plane. The main features of the spectrometer system (energy range: 0.3-23 MeV) and of the unfolding technique used to restore physical spectra from the pulse-height distributions are described: a method of solution with regularisation for matrix equations of large size, allowing to process count distributions with significant statistical noise, has been developed. A dedicated software, portable to any platform, has been written both for the acquisition and the analysis of the spectra. The typical gamma-ray spectra recorded in hydrogen and deuterium discharges, also with additional heating, are presented and discussed; two components have been observed: (a) thick-target Bremsstrahlung gamma-rays produced by runaway electrons hitting the Inconel po...

  8. The Most Remote Gamma-Ray Burst

    Science.gov (United States)

    2000-10-01

    years, the look-back time indicates that the explosion took place around the time our own galaxy, the Milky Way, was formed and at least 6,000 million years before the solar system was born. GRB 000131 and other gamma-ray bursts are believed to have taken place in remote galaxies. However, due to the huge distance, it has not yet been possible to see the galaxy in which the GRB 000131 event took place (the "host" galaxy). From the observed fading of the afterglow it is possible to estimate that the maximum brightness of this explosion was at least 10,000 times brighter than the host galaxy. Future studies of gamma-ray bursts The present team of astronomers has now embarked upon a detailed study of the surroundings of GRB 000131 with the VLT. A main goal is to observe the properties of the host galaxy. From the observations of about twenty optical counterparts of gamma-ray bursts identified until now, it is becoming increasingly clear that these very rare events are somehow related to the death of massive, short-lived stars . But despite the accumulating amount of excellent data, the details of the mechanism that leads to such dramatic explosions still remain a puzzle to astrophysicists. The detection and present follow-up observations of GRB 000131 highlight the new possibilities for studies of the extremely distant (and very early) Universe, now possible by means of gamma-ray bursts. When observed with the powerful instruments at a large ground-based telescope like the VLT, this incredibly bright class of cosmological objects may throw light on the fundamental processes of star formation in the infant universe. Of no less interest is the opportunity to analyse the chemical composition of the gas clouds at the epoch galaxies formed, by means of the imprints of the corresponding absorption lines on the afterglow spectrum. Waiting for the opportunity In this context, it would be extremely desirable to obtain very detailed (high-dispersion) spectra of the afterglow of a

  9. Gravitational Waves versus X and Gamma Ray Emission in a Short Gamma-Ray Burst

    OpenAIRE

    Oliveira, F. G.; Rueda, Jorge A.; Ruffini, Remo

    2012-01-01

    The recent progress in the understanding the physical nature of neutron star equilibrium configurations and the first observational evidence of a genuinely short gamma-ray burst, GRB 090227B, allows to give an estimate of the gravitational waves versus the X and Gamma-ray emission in a short gamma-ray burst.

  10. Calculations of gamma-ray spectral profiles of linear alkanes in the positron annihilation process

    CERN Document Server

    Ma, X G

    2014-01-01

    The positron-electron annihilation gamma-ray spectra of linear alkanes CnH2n+2 (n=1-12) have been studied systematically. A profile quality (PQ) parameter, is introduced to assess the agreement between the obtained theoretical profiles and the experimental measurements in the entire region of energy shift of the spectra. Together with the Doppler shift of the gamma-ray spectra, the two parameters,PQ and Doppler shift, are able to provide a more comprehensive assessment of the calculated gamma-ray spectra with respect to available experiment. Applying the recently developed docking model, the present study determines the positrophilic electrons for individual alkanes from which the gamma-ray spectral profiles are calculated. The results achieve an excellent agreement with experiment, not only with respect to the Doppler shift, but also with respect to the gamma-ray profiles in the photon energy region up to 5 keV. The study further calculates the gamma-ray spectra of other linear alkanes in the series without ...

  11. THE BATSE 5B GAMMA-RAY BURST SPECTRAL CATALOG

    International Nuclear Information System (INIS)

    We present systematic spectral analyses of gamma-ray bursts (GRBs) detected with the Burst and Transient Source Experiment (BATSE) on board the Compton Gamma-Ray Observatory during its entire nine years of operation. This catalog contains two types of spectra extracted from 2145 GRBs, and fitted with five different spectral models resulting in a compendium of over 19,000 spectra. The models were selected based on their empirical importance to the spectral shape of many GRBs, and the analysis performed was devised to be as thorough and objective as possible. We describe in detail our procedures and criteria for the analyses, and present the bulk results in the form of parameter distributions. This catalog should be considered an official product from the BATSE Science Team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center (HEASARC)

  12. Understanding hadronic gamma-ray emission from supernova remnants

    International Nuclear Information System (INIS)

    We aim to test the plausibility of a theoretical framework in which the gamma-ray emission detected from supernova remnants may be of hadronic origin, i.e., due to the decay of neutral pions produced in nuclear collisions involving relativistic nuclei. In particular, we investigate the effects induced by magnetic field amplification on the expected particle spectra, outlining a phenomenological scenario consistent with both the underlying Physics and the larger and larger amount of observational data provided by the present generation of gamma experiments, which seem to indicate rather steep spectra for the accelerated particles. In addition, in order to study to study how pre-supernova winds might affect the expected emission in this class of sources, the time-dependent gamma-ray luminosity of a remnant with a massive progenitor is worked out. Solid points and limitations of the proposed scenario are finally discussed in a critical way

  13. High-energy gamma rays in Hiroshima and Nagasaki: Implications for risk and WR

    International Nuclear Information System (INIS)

    Based on the DS86 dosimetry system, nearly all of the dose to survivors of the atomic bombings of Hiroshima and Nagasaki was due to unusually high-energy gamma rays, predominantly in the 2- to 5-MeV range. These high energies resulted in part from neutron capture gamma rays as the bomb neutrons penetrated large distances of air. Because of the inverse relationship between energy and biological effectiveness, these high-energy gamma rays are expected to be substantially less effective in producing biological damage than the radiations commonly used in radiobiology and risk assessment. This observation has implications for radiation protection and risk assessment

  14. About gamma-ray intensity measurement in manganese

    International Nuclear Information System (INIS)

    Full text: Thermal neutron capture gamma-ray spectroscopy setup at Pakistan Research Reactor (PARR-1) is being used for the various properties like re-estimation of capture cross-sections, absolute intensity measurements, etc in different isotopes. The facility comprises a collimated thermal neutron beam having a flux of ∼2·l06 n/cm2/s at the target position about two meters away from the reactor wall. The measurement system consists of well-shielded anti-Compton/pair spectrometer assembly containing high-resolution HPGe detector surrounded by two large Nal crystals. The spectrometer was calibrated using standard radioactive sources up to 1.5 MeV. In the higher energy region (up to 10 MeV), the energy calibration was performed with prompt gamma rays from thermal neutron capture in chlorine. Spec pure powder and 5N pure Mn metal pieces were used for this study. Chlorine was used a comparator for calculation of Ko factor. The results have been tabulate for all interference free gamma-rays from manganese

  15. Photodisintegrated gamma rays and neutrinos from heavy nuclei in the gamma-ray burst jet of GRB 130427A

    CERN Document Server

    Joshi, Jagdish C; Moharana, Reetanjali

    2015-01-01

    Detection of $\\sim$ 0.1-70 GeV prompt $\\gamma$-ray emission from the exceptionally bright gamma-ray burst (GRB) 130427A by the ${\\it Fermi}$-Large Area Telescope provides an opportunity to explore the physical processes of GeV $\\gamma$-ray emission from the GRB jets. In this work we discuss interactions of Iron and Oxygen nuclei with observed keV-MeV photons in the jet of GRB 130427A in order to explain an additional, hard spectral component observed during 11.5-33 second after trigger. The photodisintegration time scale for Iron nuclei is comparable to or shorter than this duration. We find that $\\gamma$ rays resulting from the Iron nuclei disintegration can account for the hard power-law component of the spectra in the $\\sim$ 1-70 GeV range, before the $\\gamma\\gamma \\to e^\\pm$ pair production with low-energy photons severely attenuates emission of higher energy photons. Electron antineutrinos from the secondary neutron decay, on the other hand, can be emitted with energies up to $\\sim$ 2 TeV. The flux of th...

  16. A separation of electrons and protons in the GAMMA-400 gamma-ray telescope

    CERN Document Server

    Leonov, A A; Bonvicini, V; Topchiev, N P; Adriani, 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; Popov, A V; Rappoldi, A; Ricciarini, S; Runtso, M F; Ryde, F; Serdin, O V; Sparvoli, R; Spillantini, P; Suchkov, S I; Tavani, M; Taraskin, A A; 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

    2015-01-01

    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 with the following scientific goals: 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. The main components of cosmic rays are protons and helium nuclei, whereas the part of lepton component in the total flux is ~10E-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 individual contribution to the proton rejection is studied for each detector system of the GAMMA-400 gamma-ray tel...

  17. Modulated gamma ray beam absorptiometer

    International Nuclear Information System (INIS)

    The purpose of this paper is to describe the study and operating of a heavy elements content measuring instrument. This apparatus (French patent n0 2184533, December 16, 1974) uses the absorption of a modulated gamma ray beam to measure the concentration of 5 to 500 g per litre uranium of plutonium solutions with an over 1% accuracy. The activity of the fission products present in the solution may rise to 60 Ci/l. An automatic device suppresses all daily checkings and adjustements. The tension obtained is proportional to the content of the heavy element being measured. The influence of the nitric acid content is twenty times as weak as in the case of a conventional densimeter. This apparatus is particularly adapted to fuel reprocessing plants

  18. Dark gamma-ray bursts: possible role of multiphoton processes

    CERN Document Server

    Perel'man, Mark E

    2009-01-01

    The absence of optical afterglow at some gamma-ray bursts (so called dark bursts) requires analyses of physical features of this phenomenon. It is shown that such singularity can be connected with multiphoton processes of frequencies summation in the Rayleigh- Jeans part of spectra, their pumping into higher frequencies. It can be registered most probably on young objects with still thin plasma coating, without further thermalization, i.e. soon after a prompt beginning of the explosive activity.

  19. ATCA monitoring of gamma-ray loud AGN

    OpenAIRE

    J.Stevens; Edwards, P. G.; Ojha, R.; Kadler, M.(University Würzburg, Würzburg, Germany); Hungwe, F.; Dutka, M.; Tingay, S.; Macquart, J.P.; Moin, A.; Lovell, J.; Blanchard, J.

    2012-01-01

    As a critical part of the Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry (TANAMI) program, in November 2007 the Australia Telescope Compact Array (ATCA) started monitoring the radio spectra of a sample of southern hemisphere active galactic nuclei (AGN) that were selected as likely candidates for detection (as well as a control sample) by the Large Area Telescope (LAT) aboard the Fermi Gamma Ray Space Observatory. The initial sample was chosen based on properties d...

  20. A 16N gamma-ray facility

    Science.gov (United States)

    Hull, Ethan L.; Pehl, Richard H.; Stanley, Michelle R.; Foster, Charles C.; Komisarcik, Kevin; East, Gary W.; Vanderwerp, John D.; Friesel, Dennis L.

    1997-02-01

    A practical 16N gamma-ray source is created in a medium-energy cyclotron environment. A 16N source emits 6129 and 7115 keV gamma rays. The viability of this several μCi source for detector calibration and studying detector physics is established.

  1. A 16N gamma-ray facility

    International Nuclear Information System (INIS)

    A practical 16N gamma-ray source is created in a medium-energy cyclotron environment. A 16N source emits 6129 and 7115 keV gamma rays. The viability of this several μCi source for detector calibration and studying detector physics is established. (orig.)

  2. Handbook on Mobile Gamma-ray Spectrometry

    DEFF Research Database (Denmark)

    Aage, Helle Karina; Korsbech, Uffe C C

    2003-01-01

    Basic physics and mathematics for Airborne and Car-borne Gamma-ray Spectrometry supplemented with practical examples and methods for advanced data processing......Basic physics and mathematics for Airborne and Car-borne Gamma-ray Spectrometry supplemented with practical examples and methods for advanced data processing...

  3. Sterilization of pharmaceuticals by gamma ray

    International Nuclear Information System (INIS)

    This paper shows the possibility of sterilization of certain pharmaceuticals and materials involved by gamma radiation from cobalt-60 and cesium-137 sources, and illustrates the importance of gamma ray sterilization compared with other sterilization methods. The paper also reviews some pharmaceuticals and materials involved, which proved the possibility of gamma ray sterilization. (author)

  4. Prompt gamma-ray activation analysis (PGAA)

    Energy Technology Data Exchange (ETDEWEB)

    Kern, J. [Fribourg Univ. (Switzerland). Inst. de Physique

    1996-11-01

    The paper deals with a brief description of the principles of prompt gamma-ray activation analysis (PGAA), with the detection of gamma-rays, the PGAA project at SINQ and with the expected performances. 8 figs., 3 tabs., 10 refs.

  5. Physics-based generation of gamma-ray response functions for CDZNTE detectors

    International Nuclear Information System (INIS)

    A physics-based approach to gamma-ray response-function generation is presented in which the response of CdZnTe detectors is modeled from first principles. Computer modeling is used to generate response functions needed for spectrum analysis for general detector configurations (e.g., electrode design, detector materials and geometry, and operating conditions). With computer modeling, requirements for calibration and characterization are significantly reduced. Elements of the physics-based model, including gamma-ray transport, charge drift-diffusion, and circuit response, are presented. Calculated and experimental gamma-ray spectra are compared for a coplanar-grid CdZnTe detector

  6. Fermi LAT Gamma-ray Detections of Classical Novae V1369 Centauri 2013 and V5668 Sagittarii 2015

    CERN Document Server

    Cheung, C C; Shore, S N; Stawarz, L; Corbet, R H D; Knodlseder, J; Starrfield, S; Wood, D L; Desiante, R; Longo, F; Pivato, G; Wood, K S

    2016-01-01

    We report the Fermi Large Area Telescope (LAT) detections of high-energy (>100 MeV) gamma-ray emission from two recent optically bright classical novae, V1369 Centauri 2013 and V5668 Sagittarii 2015. At early times, Fermi target-of-opportunity observations prompted by their optical discoveries provided enhanced LAT exposure that enabled the detections of gamma-ray onsets beginning ~2 days after their first optical peaks. Significant gamma-ray emission was found extending to 39-55 days after their initial LAT detections, with systematically fainter and longer duration emission compared to previous gamma-ray detected classical novae. These novae were distinguished by multiple bright optical peaks that encompassed the timespans of the observed gamma rays. The gamma-ray light curves and spectra of the two novae are presented along with representative hadronic and leptonic models, and comparisons to other novae detected by the LAT are discussed.

  7. Evidence for Gamma-Ray Flares in 3C 279 and PKS 1622-297 at ~10 MeV

    CERN Document Server

    Collmar, W; Blömen, H; Blom, J J; Hermsen, W; McConnell, M; Stacy, J G; Bennett, K; Williams, O R

    1997-01-01

    The EGRET experiment aboard the Compton Gamma-Ray Observatory (CGRO) has observed at energies above 100 MeV strong gamma-ray flares with short-term time variability from the gamma-ray blazars 3C 279 and PKS 1622-297. During these flaring periods both blazars have been detected by the COMPTEL experiment aboard CGRO at photon energies of about 10 MeV, revealing simultaneous gamma-ray activity down to these energies. For both cases the derived fluxes exceed those measured in previous observations, and 3C 279 shows an indication for time variability within the observational period. Both sources show evidence for `hard' MeV spectra. In general the behaviour of both sources at gamma-ray energies is found to be quite similar supporting the conclusion that the underlying physical mechanism for both gamma-ray flares might be the same.

  8. Gamma-ray pulsars: a gold mine

    CERN Document Server

    Grenier, Isabelle A

    2015-01-01

    The most energetic neutron stars, powered by their rotation, are capable of producing pulsed radiation from the radio up to gamma rays with nearly TeV energies. These pulsars are part of the universe of energetic and powerful particle accelerators, using their uniquely fast rotation and formidable magnetic fields to accelerate particles to ultra-relativistic speed. The extreme properties of these stars provide an excellent testing ground, beyond Earth experience, for nuclear, gravitational, and quantum-electrodynamical physics. A wealth of gamma-ray pulsars has recently been discovered with the Fermi Gamma-Ray Space Telescope. The energetic gamma rays enable us to probe the magnetospheres of neutron stars and particle acceleration in this exotic environment. We review the latest developments in this field, beginning with a brief overview of the properties and mysteries of rotation-powered pulsars, and then discussing gamma-ray observations and magnetospheric models in more detail.

  9. Unveiling the Secrets of Gamma Ray Bursts

    CERN Document Server

    Gomboc, A

    2012-01-01

    Gamma Ray Bursts (GRBs) are unpredictable and brief flashes of gamma rays that occur about once a day in random locations in the sky. Since gamma rays do not penetrate the Earth's atmosphere, they are detected by satellites, which automatically trigger ground-based telescopes for follow-up observations at longer wavelengths. In this introduction to Gamma Ray Bursts we review how building a multi-wavelength picture of these events has revealed that they are the most energetic explosions since the Big Bang and are connected with stellar deaths in other galaxies. However, in spite of exceptional observational and theoretical progress in the last 15 years, recent observations raise many questions which challenge our understanding of these elusive phenomena. Gamma Ray Bursts therefore remain one of the hottest topics in modern astrophysics.

  10. Perspectives of the GAMMA-400 space observatory for high-energy gamma rays and cosmic rays measurements

    Science.gov (United States)

    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.

  11. Sensitivity of HAWC to gamma ray bursts

    Science.gov (United States)

    Taboada, Ignacio; HAWC Collaboration

    2012-12-01

    HAWC is a ground based very high-energy gamma ray detector under construction in Mexico at an altitude of 4100 m a.s.l. Higher altitude, improved design and a larger physical size used to reject CR background, make HAWC 10-20 times more sensitive than its predecessor Milagro. HAWC's large field of view, ~2sr, and over 90% duty cycle make it ideal to search for GRBs. We review the sensitivity of HAWC to GRBs with two independent data acquisition systems. We show that some of the brightest GRBs observed by Fermi LAT (e.g. GRB 090510) could result in >5 σ observation by HAWC. The observations (or limits) of GRBs by HAWC will provide information on the high-energy spectra of GRBs. The high-energy spectra will teach us about extra galactic background light, the Lorentz boost factor of the jets tha power GRBs and/or particle acceleration models of GRBs. Finally we present limits on > 10 GeV emission from GRB 111016B, recently studied with HAWC's engineering array VAMOS.

  12. Modeling gamma-ray bursts

    Science.gov (United States)

    Maxham, Amanda

    Discovered serendipitously in the late 1960s, gamma-ray bursts (GRBs) are huge explosions of energy that happen at cosmological distances. They provide a grand physical playground to those who study them, from relativistic effects such as beaming, jets, shocks and blastwaves to radiation mechanisms such as synchrotron radiation to galatic and stellar populations and history. Through the Swift and Fermi space telescopes dedicated to observing GRBs over a wide range of energies (from keV to GeV), combined with accurate pinpointing that allows ground based follow-up observations in the optical, infrared and radio, a rich tapestry of GRB observations has emerged. The general picture is of a mysterious central engine (CE) probably composed of a black hole or neutron star that ejects relativistic shells of matter into intense magnetic fields. These shells collide and combine, releasing energy in "internal shocks" accounting for the prompt emission and flaring we see and the "external shock" or plowing of the first blastwave into the ambient surrounding medium has well-explained the afterglow radiation. We have developed a shell model code to address the question of how X-ray flares are produced within the framework of the internal shock model. The shell model creates randomized GRB explosions from a central engine with multiple shells and follows those shells as they collide, merge and spread, producing prompt emission and X-ray flares. We have also included a blastwave model, which can constrain X-ray flares and explain the origin of high energy (GeV) emission seen by the Fermi telescope. Evidence suggests that gamma-ray prompt emission and X-ray flares share a common origin and that at least some flares can only be explained by long-lasting central engine activity. We pay special attention to the time history of central engine activity, internal shocks, and observed flares. We calculate the gamma-ray (Swift/BAT band) and X-ray (Swift/XRT band) lightcurves for arbitrary

  13. Gamma-rays from nebulae around binary systems containing energetic rotation powered pulsars

    CERN Document Server

    Bednarek, W

    2013-01-01

    We consider nebulae which are created around binary systems containing rotation powered pulsars and companion stars with strong stellar winds. It is proposed that the stellar and pulsar winds have to mix at some distance from the binary system, defined by the orbital period of the companion stars and the velocity of the stellar wind. The mixed pulsar-stellar wind expands with a specific velocity determined by the pulsar power and the mass loss rate of the companion star. Relativistic particles, either from the inner pulsar magnetosphere and/or accelerated at the shocks between stellar and pulsar winds, are expected to be captured and isotropized in the reference frame of the mixed wind. Therefore, they can efficiently comptonize stellar radiation producing GeV-TeV $\\gamma$-rays in the inverse Compton process. We calculate the $\\gamma$-ray spectra expected in such scenario for the two example binary systems: J1816+4510 which is the redback type millisecond binary and LS 5039 which is supposed to contain energe...

  14. Colorado School of Mines fusion gamma ray project: Annual progress report

    International Nuclear Information System (INIS)

    A multifaceted study was made at PPPL of the gamma ray energy spectra and count rates on TFTR during Ohmic and neutral beam heated deuterium and 3He plasmas. These measurements were made at neutron source strengths up to about 6 x 1015 neutrons per second during some of the record setting ''super shots'' achieved on TFTR during early July. During the course of a series of deuterium neutral beam heated 3He plasmas, we observed the 16.6 MeV gamma ray from the d(3He,γ)5Li direct capture reaction using a large volume NE226 liquid scintillator detector. Preliminary measurements were made on TFTR of the flux of 14 MeV neutrons during deuterium discharges resulting from the burn-up of the 1 MeV tritons from the d-d reactions. The measured yield of the 14 MeV neutrons was found to be generally low when compared to the predicted yield. The use of alpha particle induced nuclear reactions as the basis of a diagnostic of fast confined and escaping alpha particles is described

  15. GEANT4 Simulations of Gamma-Ray Emission from Accelerated Particles in Solar Flares

    OpenAIRE

    Tang, Shichao; Smith, David M

    2010-01-01

    Gamma-ray spectroscopy provides diagnostics of particle acceleration in solar flares, but care must be taken when interpreting the spectra due to effects of the angular distribution of the accelerated particles (such as relativistic beaming) and Compton reprocessing of the radiation in the solar atmosphere. In this paper, we use the GEANT4 Monte Carlo package to simulate the interactions of accelerated electrons and protons and study these effects on the gamma-rays resulting from electron bre...

  16. The evaluated gamma-ray activation file (EGAF)

    International Nuclear Information System (INIS)

    The Evaluated Gamma-ray Activation File (EGAF), a new database of prompt and delayed neutron capture g-ray cross sections, has been prepared as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project to develop a ''Database of Prompt Gamma-rays from Slow Neutron Capture for Elemental Analysis.'' Recent elemental g-ray cross-section measurements performed with the guided neutron beam at the Budapest Reactor have been combined with data from the literature to produce the EGAF database. EGAF contains thermal cross sections for ∼ 35,000 prompt and delayed g-rays from 262 isotopes. New precise total thermal radiative cross sections have been derived for many isotopes from the primary and secondary gamma-ray cross sections and additional level scheme data. An IAEA TECDOC describing the EGAF evaluation and tabulating the most prominent g-rays will be published in 2004. The TECDOC will include a CD-ROM containing the EGAF database in both ENSDF and tabular formats with an interactive viewer for searching and displaying the data. The Isotopes Project, Lawrence Berkeley National Laboratory continues to maintain and update the EGAF file. These data are available on the Internet from both the IAEA and Isotopes Project websites

  17. On the f' spectrum of high-energy gamma-ray families

    International Nuclear Information System (INIS)

    The f' spectra of high-energy gamma-ray families are constructed from the data obtained with the Mount Fuji emulsion chambers. The shape of the spectra is almost independent of the energy of the families and is apparently contradictory to the result of the Pamir collaboration, which shows a shrinkage of the spectra as energy increases. (author)

  18. Gamma-ray Astronomy and GLAST

    Science.gov (United States)

    McEnery, Julie

    2007-01-01

    The high energy gamma-ray (30 MeV to 100 GeV) sky has been relatively poorly studied. Most of our current knowledge comes from observations made by the Energetic Gamma Ray Experiment Telescope (EGRET) detector on the Compton Gamma Ray Observatory (CGRO), which revealed that the GeV gamma-ray sky is rich and vibrant. Studies of astrophysical objects at GeV energies are interesting for several reasons: The high energy gamma-rays are often produced by a different physical process than the better studied X-ray and optical emission, thus providing a unique information for understanding these sources. Production of such high-energy photons requires that charged particles are accelerated to equally high energies, or much greater. Thus gamma-ray astronomy is the study of extreme environments, with natural and fundamental connections to cosmic-ray and neutrino astrophysics. The launch of GLAST in 2008 will herald a watershed in our understanding of the high energy gamma-ray sky, providing dramatic improvements in sensitivity, angular resolution and energy range. GLAST will open a new avenue to study our Universe as well as to answer scientific questions EGRET observations have raised. In this talk, I will describe the GLAST instruments and capabilities and highlight some of the science we expect to address.

  19. Gamma-Ray Burst Physics with GLAST

    Energy Technology Data Exchange (ETDEWEB)

    Omodei, N.; /INFN, Pisa

    2006-10-06

    The Gamma-ray Large Area Space Telescope (GLAST) is an international space mission that will study the cosmos in the energy range 10 keV-300 GeV, the upper end of which is one of the last poorly observed region of the celestial electromagnetic spectrum. The ancestor of the GLAST/LAT was the Energetic Gamma Ray Experiment Telescope (EGRET) detector, which flew onboard the Compton Gamma Ray Observatory (CGRO). The amount of information and the step forward that the high energy astrophysics made thanks to its 9 years of observations are impressive. Nevertheless, EGRET uncovered the tip of the iceberg, raising many questions, and it is in the light of EGRET's results that the great potential of the next generation gamma-ray telescope can be appreciated. GLAST will have an imaging gamma-ray telescope, the Large Area Telescope (LAT) vastly more capable than instruments own previously, as well as a secondary instrument, the GLAST Bursts Monitor, or GBM, to augment the study of gamma-ray bursts. Gamma-Ray Bursts (GRBs) science is one of the most exciting challenges for the GLAST mission, exploring the high energy emission of one of the most intense phenomena in the sky, shading light on various problems: from the acceleration of particles to the emission processes, to more exotic physics like Quantum Gravity effect. In this paper we report the work done so far in the simulation development as well as the study of the LAT sensitivity to GRB.

  20. Time-of-flight discrimination between gamma-rays and neutrons by using artificial neural networks

    International Nuclear Information System (INIS)

    Highlights: ► Time-of-flight (tof) is an obvious method for separation between gamma and neutron particles. ► tof distributions are obtained by neural networks. ► Neural network method is consistent with the experimental results. ► Neural networks can classify different events for discrimination. - Abstract: In gamma-ray spectroscopy, a number of neutrons are emitted from the nuclei together with the gamma-rays. These neutrons influence gamma-ray spectra. An obvious method for discrimination between neutrons and gamma-rays is based on the time-of-flight (tof) technique. In this work, the tof distributions of gamma-rays and neutrons were obtained both experimentally and by using artificial neural networks (ANNs). It was shown that, ANN can correctly classify gamma-ray and neutron events. Also, for highly nonlinear detector response for tof, we have constructed consistent empirical physical formulas (EPFs) by appropriate ANNs. These ANN–EPFs can be used to derive further physical functions which could be relevant to discrimination between gamma-rays and neutrons

  1. Observing Gamma Ray Bursts with the RHESSI satellite

    International Nuclear Information System (INIS)

    The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) was launched successfully on the 5th of February 2002 into a low Earth orbit. It is a NASA Small Explorer satellite designed to study hard X-rays and gamma-rays from solar flares. In addition, its lightly shielded array of 9 germanium detectors can see photons from high-energy sources throughout the Universe, in particular also from Gamma Ray Bursts (GRBs). With its wide field of view, RHESSI observes about one GRB per week, the sensitive energy band ranging from about 30 keV to 15 MeV. By presenting preliminary lightcurves and raw spectra from three very strong GRBs observed with RHESSI we demonstrate its high time and energy resolution. Since the arrival time and energy of each photon is recorded, combined time/energy studies, e.g. time dependent hardness ratios, can be studied

  2. A mobile gamma ray spectrometer system for nuclear hazard mapping

    CERN Document Server

    Smethurst, M A

    2000-01-01

    The Geological Survey of Norway has developed a system for mobile gamma ray spectrometer surveying suitable for use in nuclear emergencies where potentially dangerous radioactive materials have been released into the environment. The measuring system has been designed for use with different kinds of transportation platforms. These include fixed-wing aircraft, helicopters and vans. The choice of transportation platform depends on the nature of the nuclear emergency. Widespread fallout from a distant source can be mapped quickly from the air while local sources of radiation can be delineated by a car-borne system. The measuring system processes gamma ray spectra in real time. The operator of the system is therefore able to guide surveying in accordance with meaningful data values and immediately report these values to decision making The operator is presented with a number of different displays suited to different kinds of nuclear emergencies that lead to more efficient surveying. Real time processing of data m...

  3. Estimation of uranium from multichannel spectra in airborne gamma ray spectrometry using 1.12 MeV and 1.76 MeV photopeaks of 214Bi - an application to Cuddapah basin

    International Nuclear Information System (INIS)

    Present study examines the utility of gamma rays of energies 1.12 MeV and 1.76 MeV of uranium in estimation of uranium in airborne gamma ray spectrometric survey (AGRS) in comparison to the conventional 1.76 MeV alone used world wide. As a case study, the AGRS data of northern part of Cuddapah Basin is considered. Multi-channel processing is applied on this dataset to reduce the spectral noise and use of combined 1.12 MeV and 1.76 MeV has reduced the Poisson's related statistical error. Uranium is estimated using above two energies individually and in combination, using multi-channel processing followed by standard corrections procedure. Result indicates that a combination of both energies has given best estimation due to a reduction in overall noise which helped in demarcating geological entities and litho-contacts. This indicates the efficacy of this technique which improved the radio-geochemistry of study area in understanding the radio-elemental variation. (author)

  4. Photospheric Emission in Gamma-Ray Bursts

    CERN Document Server

    Pe'er, Asaf

    2016-01-01

    A major breakthrough in our understanding of gamma-ray bursts (GRB) prompt emission physics occurred in the last few years, with the realization that a thermal component accompanies the over-all non-thermal prompt spectra. This thermal part is important by itself, as it provides direct probe of the physics in the innermost outflow regions. It further has an indirect importance, as a source of seed photons for inverse-Compton scattering, thereby it contributes to the non-thermal part as well. In this short review, we highlight some key recent developments. Observationally, although so far it was clearly identified only in a minority of bursts, there are indirect evidence that thermal component exists in a very large fraction of GRBs, possibly close to 100%. Theoretically, the existence of thermal component have a large number of implications as a probe of underlying GRB physics. Some surprising implications include its use as a probe of the jet dynamics, geometry and magnetization.

  5. Effects of Cosmic Infrared Background on High Energy Delayed Gamma-Rays From Gamma-Ray Bursts

    Energy Technology Data Exchange (ETDEWEB)

    Murase, Kohta; /Kyoto U., Yukawa Inst., Kyoto; Asano, Katsuaki; /Natl. Astron. Observ. of Japan; Nagataki, Shigehiro; /Kyoto U., Yukawa Inst., Kyoto /KIPAC, Menlo Park

    2007-04-06

    Regenerated high energy emissions from gamma-ray bursts (GRBs) are studied in detail. If the primary emission spectrum extends to TeV range, these very high energy photons will be absorbed by the cosmic infrared background (CIB). The created high energy electron-positron pairs up-scatter not only cosmic microwave background (CMB) photons but also CIB photons, and secondary photons are generated in the GeV-TeV range. These secondary delayed photons may be observed in the near future, and useful for a consistency check for the primary spectra and GRB physical parameters. The up-scattered CIB photons cannot be neglected for low redshift bursts and/or GRBs with a relatively low maximum photon energy. The secondary gamma-rays also give us additional information on the CIB, which is uncertain in observations so far.

  6. GAMMA-RAY AND X-RAY EMISSION FROM GAMMA-RAY-LOUD BLAZARS

    Institute of Scientific and Technical Information of China (English)

    ZHANG XIONG; ZHAO GANG; XIE GUANG-ZHONG; ZHENG GUANG-SHENG; ZHANG LI

    2001-01-01

    We present a strong correlation of the gamma-ray (above 100 MeV) mean spectral indices aγ and X-ray (1 keV)mean spectral indices cX for 34 gamma-ray-loud blazars (16 BL Lac objects and 18 flat spectrum radio quasars). Astrong correlation is also found between the gamma-ray flux densities F-γ and X-ray flux densities Fx in the low state for 47 blazars (17 BL Lac and 30 flat spectrum radio quasars). Possible correlation on the gamma-ray emission mechanism is discussed. We suggest that the main gamma-ray radiation mechanism is probably the synchrotron process. The gamma-ray emission may be somewhat different from that of BL Lac objects and flat spectrum radio quasars.

  7. Gamma-Ray Astrophysics NSSTC Fermi GBM

    Data.gov (United States)

    National Aeronautics and Space Administration — The Fermi Gamma-Ray Burst Monitor (GBM) is not a pointed or imaging instrument. To determine fluxes for known sources, we measure the change in the count rate...

  8. Gamma rays from clusters of galaxies

    CERN Document Server

    Blasi, P; Brunetti, G; Blasi, Pasquale; Gabici, Stefano; Brunetti, Gianfranco

    2007-01-01

    Clusters of galaxies and the large scale filaments that connect neighboring clusters are expected to be sites of acceleration of charged particles and sources of non-thermal radiation from radio frequencies to gamma rays. Gamma rays are particularly interesting targets of investigation, since they may provide precious information on the nature and efficiency of the processes of acceleration and magnetic confinement of hadrons within clusters of galaxies. Here we review the status of viable scenarios that lead to the production of gamma rays from large scale structures and are compatible with the multifrequency observations that are already available. We also discuss the possibility of detection of gamma rays with space-borne telescopes such as GLAST and ground based Cherenkov telescopes, and the physical information that may be gathered from such observations.

  9. Gamma-Ray Interactions for Reachback Analysts

    Energy Technology Data Exchange (ETDEWEB)

    Karpius, Peter Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Myers, Steven Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-02

    This presentation is a part of the DHS LSS spectroscopy training course and presents an overview of the following concepts: identification and measurement of gamma rays; use of gamma counts and energies in research.

  10. Gamma ray auto absorption correction evaluation methodology

    International Nuclear Information System (INIS)

    Neutron activation analysis (NAA) is a well established nuclear technique, suited to investigate the microstructural or elemental composition and can be applied to studies of a large variety of samples. The work with large samples involves, beside the development of large irradiation devices with well know neutron field characteristics, the knowledge of perturbing phenomena and adequate evaluation of correction factors like: neutron self shielding, extended source correction, gamma ray auto absorption. The objective of the works presented in this paper is to validate an appropriate methodology for gamma ray auto absorption correction evaluation for large inhomogeneous samples. For this purpose a benchmark experiment has been defined - a simple gamma ray transmission experiment, easy to be reproduced. The gamma ray attenuation in pottery samples has been measured and computed using MCNP5 code. The results show a good agreement between the computed and measured values, proving that the proposed methodology is able to evaluate the correction factors. (authors)

  11. Gamma-ray detected radio galaxies

    Science.gov (United States)

    Beckmann, Volker; Soldi, Simona; De Jong, Sandra; Kretschmer, Karsten; Savchenko, Volodymyr

    2016-07-01

    So far 15 radio galaxies have been detected in the gamma-ray domain by CGRO/EGRET and Fermi/LAT, with a few detections also in the VHE range. We search for distinguishing parameters and estimate the total number of gamma-ray emitting radio galaxies that are potentially detectable by Fermi/LAT. We use Fermi/LAT data in comparison with X-ray and hard X-ray data in order to constrain basic parameters such as the total power of the inverse Compton branch and the position of its peak. We search for possible correlations between the radio, UV, X-ray, and gamma-ray domain and derive the number counts distribution. We then compare their properties with those of the radio galaxies in the 3CRR and SMS4 catalogues. The data show no correlation between the peak of the inverse Compton emission and its luminosity. For the gamma-ray detected radio galaxies the luminosities in the various bands are correlated, except for the UV band, but there is no indication of a correlation of peak frequency or luminosity with the spectral slopes in the X-ray or gamma-ray band. The comparison with other bright radio galaxies shows that the gamma-ray detected objects are among those that have the largest X-ray but rather moderate radio fluxes. Their UV and X-ray luminosities are similar, but gamma-ray detected radio galaxies are predominantly of type FR-I, while the 3CRR sample contains mainly FR-II objects. The number counts of the so far gamma-ray detected radio galaxies shows a very shallow slope, indicating that potentially a fraction of radio galaxies has been missed so far or has not been identified as such, although the predicted number of 22 ± 7 is consistent with the observed 15 objects.

  12. Supernovae and gamma-ray bursts connection

    Energy Technology Data Exchange (ETDEWEB)

    Valle, Massimo Della [INAF-Napoli, Capodimonte Observatory, Salita Moiariello, 16, I-80131 Napoli (Italy); International Center for Relativistic Astrophysics Network, Piazzale della Repubblica 10, I-65122, Pescara (Italy)

    2015-12-17

    I’ll review the status of the Supernova/Gamma-Ray Burst connection. Several pieces of evidence suggest that long duration Gamma-ray Bursts are associated with bright SNe-Ic. However recent works suggest that GRBs might be produced in tight binary systems composed of a massive carbon-oxygen cores and a neutron star companion. Current estimates of the SN and GRB rates yield a ratio GRB/SNe-Ibc in the range ∼ 0.4% − 3%.

  13. Supernovae and gamma-ray bursts connection

    Science.gov (United States)

    Valle, Massimo Della

    2015-12-01

    I'll review the status of the Supernova/Gamma-Ray Burst connection. Several pieces of evidence suggest that long duration Gamma-ray Bursts are associated with bright SNe-Ic. However recent works suggest that GRBs might be produced in tight binary systems composed of a massive carbon-oxygen cores and a neutron star companion. Current estimates of the SN and GRB rates yield a ratio GRB/SNe-Ibc in the range ˜ 0.4% - 3%.

  14. Gamma-ray upper limits on magnetars with 6 years of Fermi-LAT observations

    CERN Document Server

    Li, Jian; Torres, Diego F; de Ona-Wilhelmi, Emma

    2016-01-01

    We report on the search for gamma-ray emission from 20 magnetars using 6 years of Fermi, Large Area Telescope (LAT) observations. No significant evidence for gamma-ray emission from any of the currently-known magnetars is found. We derived the most stringent upper limits to date on the 0.1--10 GeV emission of Galactic magnetars, which are estimated between $\\sim10^{-12}-10^{-11}$ erg s$^{-1}$ cm$^{-2}$. Gamma-ray pulsations were searched for the four magnetars having reliable ephemerides over the observing period, but none were detected. On the other hand, we also studied the gamma-ray morphology and spectra of seven Supernova Remnants associated or adjacent to the magnetars.

  15. Monitoring the Low-Energy Gamma-Ray Sky Using Earth Occultation with GLAST GBM

    International Nuclear Information System (INIS)

    Long term all-sky monitoring of the 20 keV - 2 MeV gamma-ray sky using the Earth occultation technique was demonstrated by the BATSE instrument on the Compton Gamma Ray Observatory. The principles and techniques used for the development of an end-to-end earth occultation data analysis system for BATSE can be extended to the GLAST Burst Monitor (GBM), resulting in multiband light curves and time-resolved spectra in the energy range 8 keV to above 1 MeV for known gamma-ray sources and transient outbursts, as well as the discovery of new sources of gamma-ray emission. In this paper we describe the application of the technique to the GBM. We also present the expected sensitivity for the GBM

  16. Study of gamma ray analysis software's. Application to activation analysis of geological samples

    International Nuclear Information System (INIS)

    A comparative evaluation of the gamma-ray analysis software VISPECT, in relation to two commercial gamma-ray analysis software packages, OMNIGAM (EG and G Ortec) and SAMPO 90 (Canberra) was performed. For this evaluation, artificial gamma ray spectra were created, presenting peaks of different intensities and located at four different regions of the spectrum. Multiplet peaks with equal and different intensities, but with different channel separations, were also created. The results obtained showed a good performance of VISPECT in detecting and analysing single and multiplet peaks of different intensities in the gamma-ray spectrum. Neutron activation analysis of the geological reference material GS-N (IWG-GIT) and of the granite G-94, used in a Proficiency Testing Trial of Analytical Geochemistry Laboratories, was also performed , in order to evaluate the VISEPCT software in the analysis of real samples. The results obtained by using VISPECT were as good or better than the ones obtained using the other programs. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Younes, W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-11-13

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

  18. The Diffuse Galactic Gamma-Ray Emission Model for GLAST LAT

    Energy Technology Data Exchange (ETDEWEB)

    Porter, T.A.; /UC, Santa Cruz; Digel, S.W.; /SLAC /KIPAC, Menlo Park; Grenier, I.A.; /Saclay; Moskalenko, I.V.; /Stanford U., HEPL /KIPAC, Menlo Park; Strong, A.W.; /Garching, Max Planck Inst., MPE

    2007-06-13

    Diffuse emission from the Milky Way dominates the gamma-ray sky. About 80% of the high-energy luminosity of the Milky Way comes from processes in the interstellar medium. The Galactic diffuse emission traces interactions of energetic particles, primarily protons and electrons, with the interstellar gas and radiation field, thus delivering information about cosmic-ray spectra and interstellar mass in distant locations. Additionally, the Galactic diffuse emission is the celestial foreground for the study of gamma-ray point sources and the extragalactic diffuse gamma-ray emission. We will report on the latest developments in the modeling of the Galactic diffuse emission, which will be used for the Gamma Ray Large Area Space Telescope (GLAST) investigations.

  19. Removal cross sections and total mass attenuation coefficients of fast neutrons and gamma rays for steel

    CERN Document Server

    Elsayed, A A

    2003-01-01

    The present work deals with the study of the attenuation properties and determination of the cross sections of fast neutrons and gamma rays for structure steel used in different applications in nuclear power plants, particle accelerators, research reactors and different radiation attenuation fields. Investigation has been performed by measuring the transmitted fast neutron and gamma ray spectra behind cylindrical samples of steel (rho=7.87 gem sup - sup 3) of different thicknesses. A reactor collimated beam and neutron - gamma spectrometer with stiblbene scintillator were used for measurements. The pluse shape disriminate technique based on zero cross over method was used to discriminate between neutron and gamma ray pulses. Effective removal cross-section (sigma sub R) and total mass attenuation coefficient (mu) of neureons and gamma rays have been achieved using the attenuation relations. Microscopic removal cross sections sigma sup 9 sup 8 and mass removal cross sections sigma sub R sub / subrho of fast ne...

  20. The HAWC Gamma-Ray Observatory: Sensitivity to Steady and Transient Sources of Gamma Rays

    CERN Document Server

    Abeysekara, A U; Alvarez, C; Álvarez, J D; Arceo, R; Arteaga-Velázquez, J C; Solares, H A Ayala; Barber, A S; Baughman, B M; Bautista-Elivar, N; Belmont, E; BenZvi, S Y; Berley, D; Rosales, M Bonilla; Braun, J; Caballero-Lopez, R A; Caballero-Mora, K S; Carramiñana, A; Castillo, M; Cotti, U; Cotzomi, J; de la Fuente, E; De León, C; DeYoung, T; Hernandez, R Diaz; Díaz-Vélez, J C; Dingus, B L; DuVernois, M A; Ellsworth, R W; Fernandez, A; Fiorino, D W; Fraija, N; Galindo, A; Garfias, F; González, L X; González, M M; Goodman, J A; Grabski, V; Gussert, M; Hampel-Arias, Z; Hui, C M; Hüntemeyer, P; Imran, A; Iriarte, A; Karn, P; Kieda, D; Kunde, G J; Lara, A; Lauer, R J; Lee, W H; Lennarz, D; Vargas, H León; Linares, E C; Linnemann, J T; Longo, M; Luna-GarcIa, R; Marinelli, A; Martinez, H; Martinez, O; Martínez-Castro, J; Matthews, J A J; Miranda-Romagnoli, P; Moreno, E; Mostafá, M; Nava, J; Nellen, L; Newbold, M; Noriega-Papaqui, R; Oceguera-Becerra, T; Patricelli, B; Pelayo, R; Pérez-Pérez, E G; Pretz, J; Rivière, C; Rosa-González, D; Salazar, H; Salesa, F; Sanchez, F E; Sandoval, A; Santos, E; Schneider, M; Silich, S; Sinnis, G; Smith, A J; Sparks, K; Springer, R W; Taboada, I; Toale, P A; Tollefson, K; Torres, I; Ukwatta, T N; Villaseñor, L; Weisgarber, T; Westerhoff, S; Wisher, I G; Wood, J; Yodh, G B; Younk, P W; Zaborov, D; Zepeda, A; Zhou, H

    2013-01-01

    The High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory is designed to record air showers produced by cosmic rays and gamma rays between 100 GeV and 100 TeV. Because of its large field of view and high livetime, HAWC is well-suited to measure gamma rays from extended sources, diffuse emission, and transient sources. We describe the sensitivity of HAWC to emission from the extended Cygnus region as well as other types of galactic diffuse emission; searches for flares from gamma-ray bursts and active galactic nuclei; and the first measurement of the Crab Nebula with HAWC-30.

  1. Cosmic gamma-ray studies at Srinagar

    International Nuclear Information System (INIS)

    Cosmic gamma ray studies being carried out at the Nuclear Research Laboratory at Srinagar and Gulmarg are described and some of the results of observation and possible conclusions are mentioned. These studies use ground base techniques which can detect short-time scale gamma ray bursts from supernovae and primordial black hole (PBH) and also high energy gamma rays from various point sources. A large area photomultiplier system is employed to detect pulses of visible fluorescence radiation which is caused by a gamma ray burst of supernovae of PBH origin. However, any signal out a large number of signals recorded at Gulmarg could not be identified as coinciding with any such event observed elsewhere. It shows that the size of the burst source cannot exceed 30 km., which is in agreement with neutron-star source models. An array using plastic scintillator detectors at the corner of a 10 metre square has been set up at Gulmarg to detect air-shower due to high energy gamma rays. Cerenkov light pulses recorded at Gulmarg have been projected on the sidereal map. A significant excess observed in the right ascension range 20 +- 3 h suggests the possible presence of a quasic-periodic source of gamma rays of energy greater than 1014 eV in the general direction of Cygnus X-3. Future programme of studies is mentioned. (K.M.)

  2. Gamma rays from extragalactic astrophysical sources

    CERN Document Server

    Bosch-Ramon, V

    2011-01-01

    Presently there are several classes of detected gamma-ray extragalatic sources. They are mostly associated to active galactic nuclei (AGN) and (at soft gamma rays) to gamma-ray bursts (GRB), but not only. Active galactic nuclei consist of accreting supermassive black holes hosted by a galaxy that present in some cases powerful relativistic jet activity. These sources, which have been studied in gamma rays for several decades, are probably the most energetic astrophysical objects, and their appearance depends much on whether their jets point to us. Gamma-ray bursts, thought to be associated to collapsing or merging stellar-mass objects at cosmological distances, are also accreting highly relativistic jet sources that shine strongly at high energies. These are very short-duration events, but they are also the most luminous. Recently, star formation galaxies have turned out to be also gamma-ray emitters. On the other hand, clusters of galaxies have not been detected beyond X-rays yet. These are the largest known...

  3. Gamma-Ray Bursts: The End Game

    Science.gov (United States)

    Lamb, Don

    1997-11-01

    The nature of gamma-ray bursts has been one of the greatest unsolved mysteries in astrophysics for more than a quarter century. A major reason for this is that no definite counterparts to the bursts could be found at other wavelengths, despite intense efforts spanning more than two decades. Consequently, the study of gamma-ray bursts has been isolated from the rest of astronomy. Scientists studying them have had only the laws of physics and the bursts themselves to guide them in attempting to solve the burst mystery. All of this changed dramatically with the discovery earlier this year of fading X-ray and optical sources in the arcminute-sized positional error boxes of several gamma-ray bursts. For the first time, temporal, as well as spatial, coincidence could be used to associate these X-ray and optical sources with the gamma-ray bursts. As a result, the odds are great that the fading X-ray and optical sources are counterparts of the bursts, and that the study of gamma-ray bursts has finally been connected with the rest of astronomy. In this talk, we describe the dramatic new information about the nature of gamma-ray bursts that the X-ray, optical, and radio observations of the fading sources have provided, and emphasize the implications that this information has for the distance scale to the bursts.

  4. Gamma-ray pulsar studies with COMPTEL

    Science.gov (United States)

    Hermsen, W.; Kuiper, L.; Diehl, R.; Lichti, G.; Schoenfelder, V.; Strong, A. W.; Connors, A.; Ryan, J.; Bennett, K.; Busetta, M.; Carraminana, A.; Buccheri, R.; Grenier, I. A.

    1994-06-01

    Since the launch of the Compton Gamma-Ray Observatory (CGRO) the number of detected gamma-ray pulsars increased from two to six. COMPTEL, on-board CGRO and sensitive to gamma-rays with energies between approximately 0.7 and 30 MeV, detected three of these unambiguously. The classical Crab and Vela pulsars have been observed on several occasions and detailed pulse patterns and spectral parameters have been derived. The new CGRO gamma-ray pulsar PSR B1509-58 has been detected by COMPTEL at a significance level above 4 sigma, consistently in a timing and spatial analysis. A likely detection of Geminga has been obtained at an approximately 3 sigma level. This indication is found in a phase interval in which COS B data showed the presence of a new variable component, Interpeak 2, exhibiting a very soft spectrum above 50 MeV. The diversities in light-curve sphapes and spectral distributions, the apparent time variabilities, and the significant differences in the fractions of the spin-down power radiated at gamma-ray energies in this small sample of gamma-ray pulsars pose important constraints to pulsar modeling.

  5. Neutron fluence rate measurement using prompt gamma rays

    International Nuclear Information System (INIS)

    A gamma ray spectrometer, with a 3'' X 3'' NaI(Tl) detector, with a moderator sphere has been utilised to measure the neutron fluence rate, with this value the H*(10) was estimated. When a neutron is captured by the hydrogen-based moderator, a 2.22 MeV prompt gamma ray is produced. In a multichannel analyser the net area under the 2.22 MeV photopeak is proportional to the total neutron fluence rate. The features of this system were determined by a Monte Carlo study that includes 3-, 5- and 10-inches diameter, water and polyethylene moderators and a 239Pu-Be source. The prompt gamma response was extended to monoenergetic neutron sources. To verify the response, a 239Pu-Be source in combination with a 10'' polyethylene sphere having a gamma-ray spectrometer with NaI(Tl) was utilised to estimate the neutron fluence rate and the H*(10). These results were compared with neutron fluence rate and H*(10) obtained using a Bonner sphere spectrometer and with the H*(10) measured using a neutron rem-meter. (authors)

  6. Active galactic nuclei at gamma-ray energies

    CERN Document Server

    Dermer, Charles Dennison

    2016-01-01

    Active Galactic Nuclei can be copious extragalactic emitters of MeV-GeV-TeV gamma rays, a phenomenon linked to the presence of relativistic jets powered by a super-massive black hole in the center of the host galaxy. Most of gamma-ray emitting active galactic nuclei, with more than 1500 known at GeV energies, and more than 60 at TeV energies, are called "blazars". The standard blazar paradigm features a jet of relativistic magnetized plasma ejected from the neighborhood of a spinning and accreting super-massive black hole, close to the observer direction. Two classes of blazars are distinguished from observations: the flat-spectrum radio-quasar class (FSRQ) is characterized by strong external radiation fields, emission of broad optical lines, and dust tori. The BL Lac class (from the name of one of its members, BL Lacertae) corresponds to weaker advection-dominated flows with gamma-ray spectra dominated by the inverse Compton effect on synchrotron photons. This paradigm has been very successful for modeling t...

  7. Contribution of External Gamma Rays to SPND at HANARO

    Energy Technology Data Exchange (ETDEWEB)

    Park, B. G.; Cho, D. K.; Kim, M. S.; Kang, G. D. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Self-Powered Neutron Detectors (SPNDs) have been widely used for monitoring the neutron flux in reactors as well as in irradiation facilities. In its simplest form, the detector operates on the basis of directly measuring the beta decay current following neutron capture. The neutron capture cross-section of {sup 103}Rh, which is used for an emitter of the SPND, is 142.13 barns for thermal neutron (0.0253 eV). After neuron capture of {sup 103}Rh, the compound nuclei of {sup 104}Rh (92.6%) and {sup 104}mRh (7.4%) are produced. The sensitivity of SPND is generally defined as. The influence of water in the irradiation basket on the external gamma rays is determined by calculations of neutron capture reaction and photon interaction rates at various irradiation positions in HANARO. Since it is not easy to correct the contribution of the external gamma rays to the current signal by measurements at the research reactor, it is advantageous to reduce materials such as water at the irradiation position.

  8. The half-lives of 151Tb and 151Gd and the absolute gamma ray intensities of 151Gd

    International Nuclear Information System (INIS)

    The gamma rays accompanying the electron capture/positron decay of 151Tb and the electron capture decay of its 151Gd daughter have been studied. The half life of 151Tb has been found to be 17.609+-.014 hours. The half life of 151Gd has been found to be 123.9+-1.0 days and the absolute intensities of the 151Gd gamma rays have been determined. (orig.)

  9. Modeling of Pulses in Terrestrial Gamma-ray Flashes

    Science.gov (United States)

    Xu, Wei; Celestin, Sebastien; Pasko, Victor

    2015-04-01

    Terrestrial Gamma-ray Flashes (TGFs) are high-energy photon bursts originating from the Earth's atmosphere that are associated with lightning activities. After their discovery in 1994 by the Burst and Transient Source Experiment (BATSE) detector aboard the Compton Gamma-Ray Observatory [Fishman et al., Science, 264, 1313, 1994], this phenomenon has been further observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) [Smith et al., Science, 307, 1085, 2005], the Fermi Gamma-ray Space Telescope [Briggs et al., JGR, 115, A07323, 2010] and the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite [Marisaldi et al., JGR, 115, A00E13, 2010]. Photon spectra corresponding to the mechanism of relativistic runaway electron avalanches (RREAs) usually provide a very good agreement with satellite observations [Dwyer and Smith, GRL, 32, L22804, 2005]. On the other hand, Celestin and Pasko [JGR, 116, A03315, 2011] have shown theoretically that the large flux of thermal runaway electrons generated by streamers during the negative corona flash stage of stepping lightning leaders in intracloud lightning flashes could be responsible for TGFs. Recently, based on analysis of the temporal profiles of 278 TGF events observed by the Fermi Gamma-Ray Burst Monitor, Foley et al. [JGR, 119, 5931, 2014] have suggested that 67% of TGF pulses detected are asymmetric and these asymmetric pulses are consistent with the production mechanism of TGFs by relativistic feedback discharges. In the present work, we employ a Monte Carlo model to study the temporal distribution of photons at low-orbit satellite altitudes during TGF events. Using the pulse fitting method described in [Foley et al., 2014], we further investigate the characteristics of TGF pulses. We mainly focus on the effects of Compton scattering on the symmetry properties and the rise and fall times of TGF pulses.

  10. The relativistic feedback discharge model of terrestrial gamma ray flashes

    Science.gov (United States)

    Dwyer, Joseph R.

    2012-02-01

    As thunderclouds charge, the large-scale fields may approach the relativistic feedback threshold, above which the production of relativistic runaway electron avalanches becomes self-sustaining through the generation of backward propagating runaway positrons and backscattered X-rays. Positive intracloud (IC) lightning may force the large-scale electric fields inside thunderclouds above the relativistic feedback threshold, causing the number of runaway electrons, and the resulting X-ray and gamma ray emission, to grow exponentially, producing very large fluxes of energetic radiation. As the flux of runaway electrons increases, ionization eventually causes the electric field to discharge, bringing the field below the relativistic feedback threshold again and reducing the flux of runaway electrons. These processes are investigated with a new model that includes the production, propagation, diffusion, and avalanche multiplication of runaway electrons; the production and propagation of X-rays and gamma rays; and the production, propagation, and annihilation of runaway positrons. In this model, referred to as the relativistic feedback discharge model, the large-scale electric fields are calculated self-consistently from the charge motion of the drifting low-energy electrons and ions, produced from the ionization of air by the runaway electrons, including two- and three-body attachment and recombination. Simulation results show that when relativistic feedback is considered, bright gamma ray flashes are a natural consequence of upward +IC lightning propagating in large-scale thundercloud fields. Furthermore, these flashes have the same time structures, including both single and multiple pulses, intensities, angular distributions, current moments, and energy spectra as terrestrial gamma ray flashes, and produce large current moments that should be observable in radio waves.

  11. Application of neutron-induced and natural gamma-ray spectrometry for evaluation of coal parameters in the laboratory and in-situ

    International Nuclear Information System (INIS)

    Experimental investigations of the three laboratory nuclear techniques (natural gamma-ray, neutron capture gamma-ray and neutron activation analysis) have been applied for quantitative determination of coal parameters. Natural gamma-ray measurements of carboniferous rocks of the Upper Silesian Coal Basin have shown that the specific activity of shale and mudstone is higher than that of bituminous coal. The determination of ash content, calorific value and carbon content by natural gamma-ray spectrometry was feasible. An elemental analysis of principal elements in coal was performed by neutron capture gamma-ray measurements. The major constituents of mineral components of coal were determined by means of neutron activation analysis. Fields experiments of the two neutron induced gamma-ray spectrometric logging methods (neutron-gamma and neutron activation) have been used for quantitative determination of coal quality parameters. 74 refs, 40 figs, 15 tabs

  12. Method of incident low-energy gamma-ray direction reconstruction in the GAMMA-400 gamma-ray space telescope

    Science.gov (United States)

    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.

  13. New insights from cosmic gamma rays

    Science.gov (United States)

    Roland, Diehl

    2016-04-01

    The measurement of gamma rays from cosmic sources at ~MeV energies is one of the key tools for nuclear astrophysics, in its study of nuclear reactions and their impacts on objects and phenomena throughout the universe. Gamma rays trace nuclear processes most directly, as they originate from nuclear transitions following radioactive decays or high-energy collisions with excitation of nuclei. Additionally, the unique gamma-ray signature from the annihilation of positrons falls into this astronomical window and is discussed here: Cosmic positrons are often produced from β-decays, thus also of nuclear physics origins. The nuclear reactions leading to radioactive isotopes occur inside stars and stellar explosions, which therefore constitute the main objects of such studies. In recent years, both thermonuclear and core-collapse supernova radioactivities have been measured though 56Ni, 56Co, and 44Ti lines, and a beginning has thus been made to complement conventional supernova observations with such measurements of the prime energy sources of supernova light created in their deep interiors. The diffuse radioactive afterglow of massive-star nucleosynthesis in gamma rays is now being exploited towards astrophysical studies on how massive stars feed back their energy and ejecta into interstellar gas, as part of the cosmic cycle of matter through generations of stars enriching the interstellar gas and stars with metals. Large interstellar cavities and superbubbles have been recognised to be the dominating structures where new massive-star ejecta are injected, from 26Al gamma-ray spectroscopy. Also, constraints on the complex interiors of stars derive from the ratio of 60Fe/26Al gamma rays. Finally, the puzzling bulge-dominated intensity distribution of positron annihilation gamma rays is measured in greater detail, but still not understood; a recent microquasar flare provided evidence that such objects may be prime sources for positrons in interstellar space, rather than

  14. Gamma-Ray Peak Integration: Accuracy and Precision

    International Nuclear Information System (INIS)

    The accuracy of singlet gamma-ray peak areas obtained by a peak analysis program is immaterial. If the same algorithm is used for sample measurement as for calibration and if the peak shapes are similar, then biases in the integration method cancel. Reproducibility is the only important issue. Even the uncertainty of the areas computed by the program is trivial because the true standard uncertainty can be experimentally assessed by repeated measurements of the same source. Reproducible peak integration was important in a recent standard reference material certification task. The primary tool used for spectrum analysis was SUM, a National Institute of Standards and Technology interactive program to sum peaks and subtract a linear background, using the same channels to integrate all 20 spectra. For comparison, this work examines other peak integration programs. Unlike some published comparisons of peak performance in which synthetic spectra were used, this experiment used spectra collected for a real (though exacting) analytical project, analyzed by conventional software used in routine ways. Because both components of the 559- to 564-keV doublet are from 76As, they were integrated together with SUM. The other programs, however, deconvoluted the peaks. A sensitive test of the fitting algorithm is the ratio of reported peak areas. In almost all the cases, this ratio was much more variable than expected from the reported uncertainties reported by the program. Other comparisons to be reported indicate that peak integration is still an imperfect tool in the analysis of gamma-ray spectra

  15. Design of a Multi-Channel Ultra-High Resolution Superconducting Gamma-Ray Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, S; Terracol, S F; Miyazaki, T; Drury, O B; Ali, Z A; Cunningham, M F; Niedermayr, T R; Barbee Jr., T W; Batteux, J D; Labov, S E

    2004-11-29

    Superconducting Gamma-ray microcalorimeters operated at temperatures around {approx}0.1 K offer an order of magnitude improvement in energy resolution over conventional high-purity Germanium spectrometers. The calorimeters consist of a {approx}1 mm{sup 3} superconducting or insulating absorber and a sensitive thermistor, which are weakly coupled to a cold bath. Gamma-ray capture increases the absorber temperature in proportion to the Gamma-ray energy, this is measured by the thermistor, and both subsequently cool back down to the base temperature through the weak link. We are developing ultra-high-resolution Gamma-ray spectrometers based on Sn absorbers and superconducting Mo/Cu multilayer thermistors for nuclear non-proliferation applications. They have achieved an energy resolution between 60 and 90 eV for Gamma-rays up to 100 keV. We also build two-stage adiabatic demagnetization refrigerators for user-friendly detector operation at 0.1 K. We present recent results on the performance of single pixel Gamma-ray spectrometers, and discuss the design of a large detector array for increased sensitivity.

  16. Gamma-Ray Lenses for Astrophysics-and the Gamma-Ray Imager Mission GRI

    DEFF Research Database (Denmark)

    Wunderer, C. B.; Ballmoos, P. V.; Barriere, N.;

    2009-01-01

    , albeit at much more modest sensitivities. There will be clearly a growing need to perform deeper, more focused investigations of gamma-ray sources in the 100-keV to MeV regime. Recent technological advances in the domain of gamma-ray focusing using Lane diffraction and multilayer-coated mirror techniques......Observations of the gamma-ray sky reveal the most powerful sources and the most violent events in the Universe. While at lower wavebands the observed emission is generally dominated by thermal processes, the gamma-ray sky provides us with a view on the non-thermal Universe. Here particles are...... accelerated to extreme relativistic energies by mechanisms which are still poorly understood, and nuclear reactions are synthesizing the basic constituents of our world. Cosmic accelerators and cosmic explosions are major science themes that are addressed in the gamma-ray regime. While Fermi will take the...

  17. Constraining the location of rapid gamma-ray flares in the FSRQ 3C 273

    CERN Document Server

    Rani, B; Krichbaum, T P; Fuhrmann, L; Zensus, J A

    2013-01-01

    We present a \\gamma-ray photon flux and spectral variability study of the flat-spectrum radio quasar 3C 273 over a rapid flaring activity period between September 2009 to April 2010. Five major flares are observed in the source during this period. The most rapid flare observed in the source has a flux doubling time of 1.1 hr. The rapid \\gamma-ray flares allow us to constrain the location and size of the \\gamma-ray emission region in the source. The \\gamma \\gamma-opacity constrains the Doppler factor, $\\delta_{\\gamma} \\geq$ 10 for the highest energy (15 GeV) photon observed by the {\\it Fermi}-Large Area Telescope (LAT). Causality arguments constrain the size of the emission region to 1.6$\\times 10^{15}$ cm. The \\gamma-ray spectra measured over this period show clear deviations from a simple power law with a break in 1-2 GeV energy range. We discuss possible explanations for the origin of the \\gamma-ray spectral breaks. Our study suggests that the \\gamma-ray emission region in 3C 273 is located within the broad...

  18. Stellar Photon Archaeology with Gamma-Rays

    Science.gov (United States)

    Stecker, Floyd W.

    2009-01-01

    Ongoing deep surveys of galaxy luminosity distribution functions, spectral energy distributions and backwards evolution models of star formation rates can be used to calculate the past history of intergalactic photon densities and, from them, the present and past optical depth of the Universe to gamma-rays from pair production interactions with these photons. The energy-redshift dependence of the optical depth of the Universe to gamma-rays has become known as the Fazio-Stecker relation (Fazio & Stecker 1970). Stecker, Malkan & Scully have calculated the densities of intergalactic background light (IBL) photons of energies from 0.03 eV to the Lyman limit at 13.6 eV and for 0$ < z < $6, using deep survey galaxy observations from Spitzer, Hubble and GALEX and have consequently predicted spectral absorption features for extragalactic gamma-ray sources. This procedure can also be reversed. Determining the cutoff energies of gamma-ray sources with known redshifts using the recently launched Fermi gamma-ray space telescope may enable a more precise determination of the IBL photon densities in the past, i.e., the "archaeo-IBL.", and therefore allow a better measure of the past history of the total star formation rate, including that from galaxies too faint to be observed.

  19. GRI: the gamma-ray imager mission

    CERN Document Server

    Knödlseder, J

    2006-01-01

    Observations of the gamma-ray sky reveal the most powerful sources and the most violent events in the Universe. While at lower wavebands the observed emission is generally dominated by thermal processes, the gamma-ray sky provides us with a view on the non-thermal Universe. Here particles are accelerated to extreme relativistic energies by mechanisms which are still poorly understood, and nuclear reactions are synthesizing the basic constituents of our world. Cosmic accelerators and cosmic explosions are the major science themes that are addressed in the gamma-ray regime. With the INTEGRAL observatory, ESA has provided a unique tool to the astronomical community revealing hundreds of sources, new classes of objects, extraordinary views of antimatter annihilation in our Galaxy, and fingerprints of recent nucleosynthesis processes. While INTEGRAL provides the global overview over the soft gamma-ray sky, there is a growing need to perform deeper, more focused investigations of gamma-ray sources. In soft X-rays a...

  20. Gamma-ray binaries and related systems

    CERN Document Server

    Dubus, Guillaume

    2013-01-01

    After initial claims and a long hiatus, it is now established that several binary stars emit high (0.1-100 GeV) and very high energy (>100 GeV) gamma rays. A new class has emerged called 'gamma-ray binaries', since most of their radiated power is emitted beyond 1 MeV. Accreting X-ray binaries, novae and a colliding wind binary (eta Car) have also been detected - 'related systems' that confirm the ubiquity of particle acceleration in astrophysical sources. Do these systems have anything in common ? What drives their high-energy emission ? How do the processes involved compare to those in other sources of gamma rays: pulsars, active galactic nuclei, supernova remnants ? I review the wealth of observational and theoretical work that have followed these detections, with an emphasis on gamma-ray binaries. I present the current evidence that gamma-ray binaries are driven by rotation-powered pulsars. Binaries are laboratories giving access to different vantage points or physical conditions on a regular timescale as ...

  1. Status of the Milagro Gamma Ray Observatory

    CERN Document Server

    Maryland Univ. College Park

    2001-01-01

    The Milagro Gamma Ray Observatory, located at an altitude of 8,600 feet in the Jemez Mountains of New Mexico, is the world's first large-area water Cherenkov detector capable of continuously monitoring the entire sky for sources of TeV gamma rays. It is uniquely capable of searching for transient sources of VHE gamma rays. The core of the detector is a 60m x 80m x 8m pond instrumented with 723 PMTs deployed in two layers. This part of the detector is complete and has operated continuously since Jan. 2000. Initial studies including searches for gamma-ray sources are ongoing, and preliminary results are available. The final stage of construction is under way. We are deploying 170 auxiliary "outrigger" water Cherenkov detectors in an area of 40,000 square-meters surrounding the pond, which will significantly enhance our ability to reject background and more accurately reconstruct the gamma-ray direction and energy. In addition, we are lowering the energy threshold of the detector by using custom processing to en...

  2. Gamma-Ray Astronomy from the Ground

    CERN Document Server

    Horns, D

    2016-01-01

    The observation of cosmic gamma-rays from the ground is based upon the detection of gamma-ray initiated air showers. At energies between approximately $10^{11}$ eV and $10^{13}$ eV, the imaging air Cherenkov technique is a particularly successful approach to observe gamma-ray sources with energy fluxes as low as $\\approx 10^{-13}$ erg\\,cm$^{-2}\\,$s$^{-1}$. The observations of gamma-rays in this energy band probe particle acceleration in astrophysical plasma conditions and are sensitive to high energy phenomena beyond the standard model of particle physics (e.g., self-annihilating or decaying dark matter, violation of Lorentz invariance, mixing of photons with light pseudo-scalars). The current standing of the field and its major instruments are summarised briefly by presenting selected highlights. A new generation of ground based gamma-ray instruments is currently under development. The perspectives and opportunities of these future facilities will be discussed.

  3. A Search for Gamma-Ray Bursts and Pulsars, and the Application of Kalman Filters to Gamma-Ray Reconstruction

    OpenAIRE

    Jones, B B

    2002-01-01

    Part I describes the analysis of periodic and transient signals in EGRET data. A method to search for the transient flux from gamma-ray bursts independent of triggers from other gamma-ray instruments is developed. Several known gamma-ray bursts were independently detected, and there is evidence for a previously unknown gamma-ray burst candidate. Statistical methods using maximum likelihood and Bayesian inference are developed and implemented to extract periodic signals from gamma-ray sources ...

  4. The Spectral Sharpness Angle of Gamma-ray Bursts

    CERN Document Server

    Yu, Hoi-Fung; Greiner, Jochen; Sari, Re'em; Bhat, P Narayana; von Kienlin, Andreas; Paciesas, William S; Preece, Robert D

    2016-01-01

    We explain the results of Yu et al. (2015b) of the novel sharpness angle measurement to a large number of spectra obtained from the Fermi gamma-ray burst monitor. The sharpness angle is compared to the values obtained from various representative emission models: blackbody, single-electron synchrotron, synchrotron emission from a Maxwellian or power-law electron distribution. It is found that more than 91% of the high temporally and spectrally resolved spectra are inconsistent with any kind of optically thin synchrotron emission model alone. It is also found that the limiting case, a single temperature Maxwellian synchrotron function, can only contribute up to 58+23 -18% of the peak flux. These results show that even the sharpest but non-realistic case, the single-electron synchrotron function, cannot explain a large fraction of the observed spectra. Since any combination of physically possible synchrotron spectra added together will always further broaden the spectrum, emission mechanisms other than optically...

  5. MIRAX sensitivity for Gamma Ray Bursts

    Science.gov (United States)

    Sacahui, J. R.; Penacchioni, A. V.; Braga, J.; Castro, M. A.; D'Amico, F.

    2016-03-01

    In this work we present the detection capability of the MIRAX (Monitor e Imageador de RAios-X) experiment for Gamma-Ray Bursts (GRBs). MIRAX is an X-ray astronomy mission designed to perform a wide band hard X-ray (10-200 keV) survey of the sky, especially in the Galactic plane. With a total detection area of 169 cm2, large field of view (FoV, 20 ° × 20 °), angular resolution of 1°45‧ and good spectral and time resolution (∼8% at 60 keV, 10 μs), MIRAX will be optimized for the detection and study of transient sources, such as accreting neutron stars (NS), black holes (BH), Active Galactic Nuclei (AGNs), and both short and long GRBs. This is especially important because MIRAX is expected to operate in an epoch when probably no other hard X-ray wide-field imager will be active. We have performed detailed simulations of MIRAX GRB observations using the GEANT4 package, including the background spectrum and images of GRB sources in order to provide accurate predictions of the sensitivity for the expected GRB rate to be observed. MIRAX will be capable of detecting ∼44 GRBs per year up to redshifts of ∼4.5. The MIRAX mission will be able to contribute significantly to GRB science by detecting a large number of GRBs per year with wide band spectral response. The observations will contribute mainly to the part of GRB spectra where a thermal emission is predicted by the Fireball model. We also discuss the possibility of detecting GRB afterglows in the X-ray band with MIRAX.

  6. Specialized software utilities for gamma ray spectrometry. Final report of a co-ordinated research project 1996-2000

    International Nuclear Information System (INIS)

    A Co-ordinated Research Project (CRP) on Software Utilities for Gamma Ray Spectrometry was initiated by the International Atomic Energy Agency in 1996 for a three year period. In the CRP several basic applications of nuclear data handling were assayed which also dealt with the development of PC computer codes for various spectrometric purposes. The CRP produced several software packages: for the analysis of low level NaI spectra; user controlled analysis of gamma ray spectra from HPGe detectors; a set of routines for the definition of the detector resolution function and for the unfolding of experimental annihilation spectra; a program for the generation of gamma ray libraries for specific applications; a program to calculate true coincidence corrections; a program to calculate full-energy peak efficiency calibration curve for homogenous cylindrical sample geometries including self-attenuation correction; and a program for the library driven analysis of gamma ray spectra and for the quantification of radionuclide content in samples. In addition, the CRP addressed problems of the analysis of naturally occurring radioactive soil material gamma ray spectra, questions of quality assurance and quality control in gamma ray spectrometry, and verification of the expert system SHAMAN for the analysis of air filter spectra obtained within the framework of the Comprehensive Nuclear Test Ban Treaty. This TECDOC contains 10 presentations delivered at the meeting with the description of the software developed. Each of the papers has been indexed separately

  7. Preliminary results of a gamma-ray burst study in the Konus experiment on the Venera-11 and Venera-12 space probes

    Science.gov (United States)

    Mazets, Y. P.; Golentskiy, S. V.; Ilinskiy, V. N.; Panov, V. N.; Aptekar, R. L.; Guryan, Y. A.; Sokolov, I. A.; Sokolova, Z. Y.; Kharitonova, T. V.

    1979-01-01

    Twenty-one gamma-ray bursts and 68 solar flares in the hard X-ray range were detected on Venera-11 and Venera-12 space probes during the initial 50-day observation period. Major characteristics of the equipment used and preliminary data on the temporal structure and energy spectra of the gamma-ray bursts are considered. The pattern of gamma-ray burst frequency distribution vs. intensity, N(S), is established.

  8. JIGSAW; A gamma ray data acquisition, display and analysis program

    Energy Technology Data Exchange (ETDEWEB)

    Haywood, S.E.; Bamford, G.J.; Rester, A.C.; Coldwell, R.L. (Inst. for Astrophysics and Planetary Exploration, Univ. of Florida, Alachua, FL (United States))

    1992-08-01

    In this paper, the authors report on work performed to date on JIGSAW - a self contained data acquisition, display and analysis system designed to collect data form multiple gamma-ray detectors. The data acquisition system utilizes commercially available VMEbus and NIM hardware modules and the VME exec real time operating system. A Unix based software package, written in ANSI standard C and with the XII graphics routines, allows the user to view the acquired spectra. Analysis of the histograms can be performed in background during the run with the ROBFIT suite of curve fitting routines.

  9. Gamma-rays in the 146Eu→146Sm decay

    International Nuclear Information System (INIS)

    Gamma-rays of 146Eu→146Sm decay were measured on the anti Compton spectrometer. 293 γ-transitions were attributed to 146Eu decay, 134 of them having been observed for the first time. For other transitions the accuracy of determination of Iγ, Eγ was improved several fold. Conversion electron spectra were measured with Si(Li) detector. IK were determined for 105 transitions, for four of them - for the first time. Relative intensities of differential-integral coincidences were measured for 130 transitions. 20 refs.; 2 tabs

  10. Young Pulsars and the Galactic Center GeV Gamma-ray Excess

    CERN Document Server

    O'Leary, Ryan M; Kerr, Matthew; Dexter, Jason

    2015-01-01

    Studies of Fermi data indicate an excess of GeV gamma rays around the Galactic center (GC), possibly due to dark matter. We show that young gamma-ray pulsars can yield a similar signal. First, a high concentration of GC supernovae naturally leads to a population of kicked pulsars symmetric about the GC. Second, while very-young pulsars with soft spectra reside near the Galactic plane, pulsars with spectra that have hardened with age accumulate at larger angles. This combination, including unresolved foreground pulsars, traces the morphology and spectrum of the Excess.

  11. Measurement of the activity of a remote source by in-situ gamma-ray spectrometry

    International Nuclear Information System (INIS)

    A method for calculation of the attenuation factor for gamma rays passing through a layer of material is presented. The method is based on the measurement of the amount of radiation scattered in the material at small angles and registered in the spectra of a high resolution gamma-ray detector. The method is applied to the calculation of the activity of a remote source. The attenuation factor, the distance between the source and detector as well as the activity of the source were calculated from the spectra and compared to their reference values. (author)

  12. Technology Needs for Gamma Ray Astronomy

    Science.gov (United States)

    Gehrels, Neil

    2011-01-01

    Gamma ray astronomy is currently in an exciting period of multiple missions and a wealth of data. Results from INTEGRAL, Fermi, AGILE, Suzaku and Swift are making large contributions to our knowledge of high energy processes in the universe. The advances are due to new detector and imaging technologies. The steps to date have been from scintillators to solid state detectors for sensors and from light buckets to coded aperture masks and pair telescopes for imagers. A key direction for the future is toward focusing telescopes pushing into the hard X-ray regime and Compton telescopes and pair telescopes with fine spatial resolution for medium and high energy gamma rays. These technologies will provide finer imaging of gamma-ray sources. Importantly, they will also enable large steps forward in sensitivity by reducing background.

  13. New insights from cosmic gamma rays

    CERN Document Server

    Diehl, Roland

    2016-01-01

    The measurement of gamma rays from cosmic sources at MeV energies is one of the key tools for nuclear astrophysics, in its study of nuclear reactions and their impacts on objects and phenomena throughout the universe. Gamma rays trace nuclear processes most directly, as they originate from nuclear transitions following radioactive decays or high-energy collisions with excitation of nuclei. Additionally, the unique gamma-ray signature from the annihilation of positrons falls into this astronomical window and is discussed here: Cosmic positrons are often produced from beta-decays, thus also of nuclear physics origins. The nuclear reactions leading to radioactive isotopes occur inside stars and stellar explosions, which therefore constitute the main objects of such studies. In recent years, both thermonuclear and core-collapse supernova radioactivities have been measured, and complement conventional supernova observations with measurements of their prime energy sources. The diffuse radioactive afterglow of massi...

  14. High Energy Radiation from $\\gamma$ Ray Bursts

    CERN Document Server

    Dermer, C D; Dermer, Charles D.; Chiang, James

    1999-01-01

    Gamma-ray burst (GRB) engines are probed most intimately during the prompt gamma-ray luminous phase when the expanding blast wave is closest to the explosion center. Using GRBs 990123 and 940217 as guides, we briefly review observations of high-energy emission from GRBs and summarize some problems in GRB physics. \\gamma\\gamma transparency arguments imply relativistic beaming. The parameters that go into the external shock model are stated, and we show numerical simulation results of gamma-ray light curves from relativistic blast waves with different amounts of baryon loading. A distinct component due to the synchrotron self-Compton process produces significant emission at GeV and TeV energies. Predictions for spectral and temporal evolution at these energies are presented for a blast wave expanding into uniform surroundings. Observations of the slow decay of GeV-TeV radiation provide evidence for ultra-high energy cosmic ray acceleration in GRBs.

  15. Evaluation of gamma-ray intensities

    International Nuclear Information System (INIS)

    Relative intensities and intensities per decay of gamma rays were evaluated for 16 nuclides, 22Na, 24Na, 46Sc, 54Mn, 60Co, 85Sr, 88Y, 95Nb, sup(108m)Ag, 134Cs, 133Ba, 139Ce, sup(180m)Hf, 198Au, 203Hg and 207Bi. For most of these nuclides disintegration rates can be determined by means of β-γ or X-γ coincidence method. Since decay schemes of these nuclides are established, intensities per decay of strong gamma rays were accurately evaluated by using weak beta-ray branching ratios, relative gamma-ray intensities and internal conversion coefficients. Half-lives of the nuclides were also evaluated. Use of the nuclides, therefore, are recommended for precision intensity calibration of the detectors. (author)

  16. Solution To The Gamma Ray Burst Mystery?

    CERN Document Server

    Dar, Arnon

    1996-01-01

    Photoexcitation and ionization of partially ionized heavy atoms in highly relativistic flows by interstellar photons, followed by their reemission in radiative recombination and decay, boost star-light into beamed $\\gamma$ rays along the flow direction. Repeated excitation/decay of highly relativistic baryonic ejecta from merger or accretion induced collapse of neutron stars in dense stellar regions (DSRs), like galactic cores, globular clusters and super star-clusters, can convert enough kinetic energy in such events in distant galaxies into cosmological gamma ray bursts (GRBs). The model predicts remarkably well all the main observed temporal and spectral properties of GRBs. Its success strongly suggests that GRBs are $\\gamma$ ray tomography pictures of DSRs in galaxies at cosmological distances with unprecedented resolution: A time resolution of $dt\\sim 1~ms$ in a GRB can resolve stars at a Hubble distance which are separated by only $D\\sim 10^{10}cm$. This is equivalent to the resolving power of an optica...

  17. Thermoluminescence of Simulated Interstellar Matter after Gamma-ray Irradiation

    CERN Document Server

    Koike, K; Koike, C; Okada, M; Chihara, H

    2002-01-01

    Interstellar matter is known to be strongly irradiated by radiation and several types of cosmic ray particles. Simulated interstellar matter, such as forsterite $\\rm Mg_{2}SiO_{4}$, enstatite $\\rm MgSiO_{3}$ and magnesite $\\rm MgCO_{3}$ has been irradiated with the $\\rm ^{60}Co$ gamma-rays in liquid nitrogen, and also irradiated with fast neutrons at 10 K and 70 K by making use of the low-temperature irradiation facility of Kyoto University Reactor (KUR-LTL. Maximum fast neutron dose is $10^{17}n_f{\\rm /cm^{2}}$). After irradiation, samples are stored in liquid nitrogen for several months to allow the decay of induced radioactivity. We measured the luminescence spectra of the gamma ray irradiated samples during warming to 370K using a spectrophotometer. For the forsterite and magnesite, the spectra exhibit a rather intense peak at about 645 -- 655 nm and 660 nm respectively, whereas luminescence scarcely appeared in olivine sample. The spectra of forsterite is very similar to the ERE of the Red Rectangle.

  18. Gamma Ray Bursts in the HAWC Era

    CERN Document Server

    Mészáros, Peter; Murase, Kohta; Fox, Derek; Gao, He; Senno, Nicholas

    2015-01-01

    Gamma-Ray Bursts are the most energetic explosions in the Universe, and are among the most promising for detecting multiple non-electromagnetic signals, including cosmic rays, high energy neutrinos and gravitational waves. The multi-GeV to TeV gamma-ray range of GRB could have significant contributions from hadronic interactions, mixed with more conventional leptonic contributions. This energy range is important for probing the source physics, including overall energetics, the shock parameters and the Lorentz factor. We discuss some of the latest observational and theoretical developments in the field.

  19. Gamma-Ray Bursts: Jets and Energetics

    CERN Document Server

    Frail, D A

    2003-01-01

    The relativistic outflows from gamma-ray bursts are now thought to be narrowly collimated into jets. After correcting for this jet geometry there is a remarkable constancy of both the energy radiated by the burst and the kinetic energy carried by the outflow. Gamma-ray bursts are still the most luminous explosions in the Universe, but they release energies that are comparable to supernovae. The diversity of cosmic explosions appears to be governed by the fraction of energy that is coupled to ultra-relativistic ejecta.

  20. Gamma Ray Astronomy with Magnetized Zevatrons

    OpenAIRE

    Armengaud, Eric; Sigl, Guenter; Miniati, Francesco

    2005-01-01

    Nearby sources of cosmic rays up to a ZeV(=10^21 eV) could be observed with a multi-messenger approach including secondary gamma-rays and neutrinos. If cosmic rays above ~10^18 eV are produced in magnetized environments such as galaxy clusters, the flux of secondary gamma-rays below ~1 TeV can be enhanced up to several orders of magnitudes compared to unmagnetized sources. A particular source of enhancement are synchrotron and cascade photons from e^+e^- pairs produced by protons from sources...

  1. Very high energy gamma ray astrophysics

    International Nuclear Information System (INIS)

    The Whipple Observatory High Resolution Camera will be used in a vigorous program of observations to search for new sources of very-high-energy gamma rays. In addition, a search for antimatter using the moon-earth system as an ion spectrometer will be begun. The first phase of GRANITE, the new 37-element 11-m camera, will be concluded with first light scheduled for September, 1991. The two cameras will operate in support of the Gamma Ray Observatory mission in the winter of 1991/2

  2. Gamma ray spectrometer for Lunar Scout 2

    Science.gov (United States)

    Moss, C. E.; Burt, W. W.; Edwards, B. C.; Martin, R. A.; Nakano, George H.; Reedy, R. C.

    1993-01-01

    We review the current status of the Los Alamos program to develop a high-resolution gamma-ray spectrometer for the Lunar Scout-II mission, which is the second of two Space Exploration Initiative robotic precursor missions to study the Moon. This instrument will measure gamma rays in the energy range of approximately 0.1 - 10 MeV to determine the composition of the lunar surface. The instrument is a high-purity germanium crystal surrounded by an CsI anticoincidence shield and cooled by a split Stirling cycle cryocooler. It will provide the abundance of many elements over the entire lunar surface.

  3. A Shotgun Model for $\\gamma$ Ray Bursts

    CERN Document Server

    Heinz, S

    1999-01-01

    We propose that gamma ray bursts (GRBs) are produced by a shower of heavy blobs running into circumstellar material at highly relativistic speeds. The gamma ray emission is produced in the shocks these bullets drive into the surrounding medium. The short term variability seen in GRBs is set by the slowing-down time of the bullets while the overall duration of the burst is set by the lifetime of the central engine. A requirement of this model is that the ambient medium be dense, consistent with a strong stellar wind. In contrast to other external shock scenarios, the efficiency of the shock can be close to unity.

  4. Gamma rays induced variation in Plantago ovata

    International Nuclear Information System (INIS)

    Plantago ovata Fork., a medicinal herb, requires improvement in seed yield to meet would demand for its seed husk. Mutation breeding has been attempted on account of narrow genetic base of the crop. The mutagen, gamma rays from 60Co sources was tried for its effect on various phenotypic traits, including those related to seed yield. Studies indicate that P. ovata is radio-resistant. Gamma rays also induce alteration in mean and variance of yield related characters which can be exploited to select superior genotypes in this conservative crop

  5. Nuclear forensics using gamma-ray spectroscopy

    CERN Document Server

    Norman, Eric B

    2016-01-01

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

  6. Gamma-ray surveys in uranium exploration

    International Nuclear Information System (INIS)

    This report is intended to provide newcomers to uranium exploration with an up-to-date statement of the principal factors to be considered in planning and using gamma-ray surveys. Since the report incorporates the results of recent research, and since its preparation was influenced by the cumulative experience of its contributors, it should also be useful to those who already have some knowledge of radioactivity surveys and methods. The intention is that the information and explanations given in the report will make it possible for gamma-ray surveys to be used in the most efficient way for a given exploration task

  7. Status of the Milagro $\\gamma$ Ray Observatory

    CERN Document Server

    Atkins, R; Berley, D; Chen, M L; Coyne, D G; Delay, R S; Dingus, B L; Dorfan, D E; Ellsworth, R W; Evans, D; Falcone, A D; Fleysher, L; Fleysher, R; Gisler, G; Goodman, J A; Haines, T J; Hoffman, C M; Hugenberger, S; Kelley, L A; Leonor, I; Macri, J R; McConnell, M; McCullough, J F; McEnery, J E; Miller, R S; Mincer, A I; Morales, M F; Némethy, P; Ryan, J M; Schneider, M; Shen, B; Shoup, A L; Sinnis, G; Smith, A J; Sullivan, G W; Thompson, T N; Tümer, T O; Wang, K; Wascko, M O; Westerhoff, S; Williams, D A; Yang, T; Yodh, G B

    2001-01-01

    The Milagro Gamma Ray Observatory is the world's first large-area water Cherenkov detector capable of continuously monitoring the sky at TeV energies. Located in northern New Mexico, Milagro will perform an all sky survey of the Northern Hemisphere at energies between ~250 GeV and 50 TeV. With a high duty cycle, large detector area (~5000 square meters), and a wide field-of-view (~1 sr), Milagro is uniquely capable of searching for transient and DC sources of high-energy gamma-ray emission. Milagro has been operating since February, 1999. The current status of the Milagro Observatory and initial results will be discussed.

  8. Capture in the 1.15-keV iron resonance

    International Nuclear Information System (INIS)

    The 1.15-keV resonance in iron is important to reactors in that a major part of the iron capture integral is due to this one resonance. This resonance is also a good test case for capture gamma-ray detectors, which are meant to have an efficiency independent of gamma-ray energy spectra, because this resonance has an unusually hard spectrum and other iron resonances do not. There have been severe discrepancies among different groups who have measured the capture area and transmission of this resonance. A new measurement, employing C6F6 liquid scintillators and pulse-height weighting to effect total energy detection, has been made of the ratio of the capture area of the 22.8-keV resonance relative to that of the 1.15-keV resonance. The 22.8-keV resonance has a relatively soft gamma-ray spectrum and there is agreement on the capture area. The results (2.91 +- 0.17) agree well with transmission measurements and confirm the applicability of total energy detectors for use on capture resonances with very hard capture gamma-ray spectra

  9. Gamma Rays, Electrons, Hard X-Rays, and the Central Parsec of the Milky Way

    CERN Document Server

    Kistler, Matthew D

    2015-01-01

    The complex interplay of processes at the Galactic Center is at the heart of numerous past, present, and (likely) future mysteries. We aim at a more complete understanding of how spectra extending to >10 TeV result. We first construct a simplified model to account for the peculiar energy and angular dependence of the intense central parsec photon field. This allows for calculating anisotropic inverse Compton scattering and mapping gamma-ray extinction due to gamma gamma -> e^+ e^- attenuation. Coupling these with a method for evolving electron spectra, we examine several clear and present excesses, including the diffuse hard X-rays seen by NuSTAR and GeV gamma rays by Fermi. We address further applications to cosmic rays, dark matter, neutrinos, and gamma rays from the Center and beyond.

  10. INTEGRAL & RXTE View of Gamma-ray Binaries

    OpenAIRE

    Jian LI; Torres, Diego F.; Zhang, Shu; WANG, JIANMIN

    2013-01-01

    Gamma-ray binaries are X-ray binaries with gamma-ray emissions. Their multi-wavelength emissions range from radio, optical, X-ray and to very high energy (TeV). X-ray emissions are crucial to understand the nature of gamma-ray binaries. INTEGRAL and RXTE have covered and monitored most of the gamma-ray binaries in hard and soft X-rays. Here we report the results of several gamma-ray binaries and possible gamma-ray binaries from INTEGRAL and RXTE.

  11. Found: A Galaxy's Missing Gamma Rays

    Science.gov (United States)

    Kohler, Susanna

    2016-04-01

    Recent reanalysis of data from the Fermi Gamma-ray Space Telescope has resulted in the first detection of high-energy gamma rays emitted from a nearby galaxy. This discovery reveals more about how supernovae interact with their environments.Colliding Supernova RemnantAfter a stellar explosion, the supernovas ejecta expand, eventually encountering the ambient interstellar medium. According to models, this generates a strong shock, and a fraction of the kinetic energy of the ejecta is transferred into cosmic rays high-energy radiation composed primarily of protons and atomic nuclei. Much is still unknown about this process, however. One open question is: what fraction of the supernovas explosion power goes into accelerating these cosmic rays?In theory, one way to answer this is by looking for gamma rays. In a starburst galaxy, the collision of the supernova-accelerated cosmic rays with the dense interstellar medium is predicted to produce high-energy gamma rays. That radiation should then escape the galaxy and be visible to us.Pass 8 to the RescueObservational tests of this model, however, have beenstumped by Arp 220. This nearby ultraluminous infrared galaxy is the product of a galaxy merger ~700 million years ago that fueled a frenzy of starbirth. Due to its dusty interior and extreme levels of star formation, Arp 220 has long been predicted to emit the gamma rays produced by supernova-accelerated cosmic rays. But though weve looked, gamma-ray emission has never been detected from this galaxy until now.In a recent study, a team of scientists led by Fang-Kun Peng (Nanjing University) reprocessed 7.5 years of Fermi observations using the new Pass 8 analysis software. The resulting increase in resolution revealed the first detection of GeV emission from Arp 220!Acceleration EfficiencyGamma-ray luminosity vs. total infrared luminosity for LAT-detected star-forming galaxies and Seyferts. Arp 220s luminosities are consistent with the scaling relation. [Peng et al. 2016

  12. Gadolinium-doped water cerenkov-based neutron and high energy gamma-ray detector and radiation portal monitoring system

    Science.gov (United States)

    Dazeley, Steven A; Svoboda, Robert C; Bernstein, Adam; Bowden, Nathaniel

    2013-02-12

    A water Cerenkov-based neutron and high energy gamma ray detector and radiation portal monitoring system using water doped with a Gadolinium (Gd)-based compound as the Cerenkov radiator. An optically opaque enclosure is provided surrounding a detection chamber filled with the Cerenkov radiator, and photomultipliers are optically connected to the detect Cerenkov radiation generated by the Cerenkov radiator from incident high energy gamma rays or gamma rays induced by neutron capture on the Gd of incident neutrons from a fission source. The PMT signals are then used to determine time correlations indicative of neutron multiplicity events characteristic of a fission source.

  13. Gamma-ray spectrometry with thick mercuric iodide detectors

    International Nuclear Information System (INIS)

    Gamma-ray spectra with energies up to 1.3 MeV have been detected for the first time with 1-cm-thick HgI2 semiconductor detectors at room temperature. The spectra can be taken using a long, 10 μs, or a short, 0.5 μs, charge collection time. The latter has produced better results with better peak efficiency, higher peak-to-valley ratio, and fewer low energy counts with little sacrifice in resolution. Spectra for energies between 100 keV and 1.3 MeV and descriptions of the techniques for their acquisition are presented. The thick detectors need a conditioning treatment, which is described, prior to showing spectral response

  14. A simple method for the analysis of neutron resonance capture spectra

    OpenAIRE

    Clarijs, M.C.; Bom, V.R.; Van Eijk, C.W.E.

    2009-01-01

    Neutron resonance capture analysis (NRCA) is a method used to determine the bulk composition of various kinds of objects and materials. It is based on analyzing direct capture resonance peaks. However, the analysis is complicated by scattering followed by capture effects in the object itself. These effects depend on the object’s shape and size. In this paper the new Delft elemental analysis program (DEAP) is presented which can automatically and quickly analyze multiple NRCA spectra in a prac...

  15. Estimation method of planetary fast neutron flux by a Ge gamma-ray spectrometer

    Science.gov (United States)

    Hareyama, M.; Fujibayashi, Y.; Yamashita, Y.; Karouji, Y.; Nagaoka, H.; Kobayashi, S.; Reedy, R. C.; Gasnault, O.; Forni, O.; d'Uston, C.; Kim, K. J.; Hasebe, N.

    2016-08-01

    An intensity map of lunar fast neutrons (LFNs) and their temporal variation has been estimated by fitting "sawtooth" peaks in the energy spectra of lunar gamma rays observed by the Kaguya (SELENE) Gamma Ray Spectrometer (GRS) consisting of a high-purity germanium (HPGe) detector with a BGO scintillator. While an ordinary peak in the spectrum is produced by only gamma ray lines, the sawtooth peak is produced by gamma ray lines and recoil nuclei in the detector by Ge(n ,n‧ γ) reaction. We develop a model for the shape of the sawtooth peak and apply it to fit sawtooth peaks together with ordinary peaks in actual observed spectra on the Moon. The temporal variation of LFNs is synchronous with that of galactic cosmic rays (GCRs), and the global distribution of fast neutrons on the lunar surface agrees well with the past observation reported by the Neutron Spectrometer aboard Lunar Prospector. Based on these results, a new method is established to estimate the flux of fast neutrons by fitting sawtooth peaks on the gamma ray spectrum observed by the HPGe detector.

  16. Calculations of gamma-ray spectral profiles of linear alkanes in the positron annihilation process

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xiaoguang [Molecular Model Discovery Laboratory, Department of Chemistry and Biotechnology, School of Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria, 3122 (Australia); School of Physics and Optoelectronic Engineering, Ludong University, Shandong, Yantai, 264025 (China); Wang, Feng, E-mail: fwang@swin.edu.au [Molecular Model Discovery Laboratory, Department of Chemistry and Biotechnology, School of Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria, 3122 (Australia)

    2014-10-15

    Highlights: • The study calculates gamma-ray profiles for linear alkanes (n up to 12) quantum mechanically;. • “Profile quality” has been defined as the root-mean square deviation (RMSD) between the theoretical and the experimental results in the entire region of the profile. • Excellent agreement with measurements suggests that the theory model is applicable to predict other alkanes such as heptane (C{sub 7}H{sub 16}) etc. • The study suggested that gamma-ray spectra may be more sensitive to study smaller alkanes (and their isomers), rather than larger alkanes (i.e., n > 12). - Abstract: The positron–electron annihilation gamma-ray spectra of linear alkanes C{sub n}H{sub 2n+2} (n = 1–12) have been studied systematically. A profile quality (PQ) parameter, χ, is introduced to assess the agreement between the obtained theoretical profiles and the experimental measurements in the entire region of energy shift of the spectra. Together with the Doppler shift (Δε) of the gamma-ray spectra, the two parameters, χ and Δε, are able to provide a more comprehensive assessment of the calculated gamma-ray spectra with respect to available experiment. Applying the recently developed docking model, the present study determines the positrophilic electrons for individual alkanes from which the gamma-ray spectral profiles are calculated. The results achieve an excellent agreement with experiment, not only with respect to the Doppler shift, but also with respect to the gamma-ray profiles in the photon energy region up to 5 keV. The study further calculates the gamma-ray spectra of other linear alkanes in the series without available experimental measurements, such as heptane (C{sub 7}H{sub 16}), octane (C{sub 8}H{sub 18}), decane (C{sub 10}H{sub 22}) and undecane (C{sub 11}H{sub 24}). The results obtained show a dominance of the positrophilic electrons in the lowest occupied valence orbital (LOVO) in the positron–electron annihilation process, in agreement with

  17. Emission mechanism of GeV-quiet soft gamma-ray pulsars; A case for peculiar geometry?

    CERN Document Server

    Wang, Y; Takata, J; Leung, Gene C K; Cheng, K S

    2014-01-01

    There is a growing new class of young spin-down powered pulsars called GeV-quiet soft gamma-ray pulsar; (1) spectral turnover appears around~10MeV, (2) the X-ray spectra of below 20 keV can be described by power law with photon index around 1.2 and (3) the light curve in X-ray/soft gamma-ray bands shows single broad pulse. Their emission properties are distinct from the normal gamma-ray pulsars, for which the spectral peak in $\

  18. Gamma ray irradiated silicon nanowires: An effective model to investigate defects at the interface of Si/SiOx

    International Nuclear Information System (INIS)

    The effect of gamma ray irradiation on silicon nanowires was investigated. Here, an additional defect emerged in the gamma-ray-irradiated silicon nanowires and was confirmed with electron spin resonance spectra. 29Si nuclear magnetic resonance spectroscopy showed that irradiation doses had influence on the Q4 unit structure. This phenomenon indicated that the unique core/shell structure of silicon nanowires might contribute to induce metastable defects under gamma ray irradiation, which served as a satisfactory model to investigate defects at the interface of Si/SiOx

  19. Gamma ray irradiated silicon nanowires: An effective model to investigate defects at the interface of Si/SiOx

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Kui; Zhao, Yi; Liu, Liangbin; Lee, Shuit-Tong; Shao, Mingwang, E-mail: wxlthefirst@gmail.com, E-mail: xuegi@nju.edu.cn, E-mail: mwshao@suda.edu.cn [Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices and Collaborative Innovation, Center of Suzhou Nano Science and Technology, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou 215123 (China); Wang, Xiaoliang, E-mail: wxlthefirst@gmail.com, E-mail: xuegi@nju.edu.cn, E-mail: mwshao@suda.edu.cn; Xue, Gi, E-mail: wxlthefirst@gmail.com, E-mail: xuegi@nju.edu.cn, E-mail: mwshao@suda.edu.cn [State Key Laboratory of Co-ordination Chemistry, Department of Polymer Science and Engineering, Nanjing University, No. 20, Hankou Road, Nanjing 210093 (China)

    2014-01-20

    The effect of gamma ray irradiation on silicon nanowires was investigated. Here, an additional defect emerged in the gamma-ray-irradiated silicon nanowires and was confirmed with electron spin resonance spectra. {sup 29}Si nuclear magnetic resonance spectroscopy showed that irradiation doses had influence on the Q{sup 4} unit structure. This phenomenon indicated that the unique core/shell structure of silicon nanowires might contribute to induce metastable defects under gamma ray irradiation, which served as a satisfactory model to investigate defects at the interface of Si/SiOx.

  20. Developments in mercuric iodide gamma ray imaging

    International Nuclear Information System (INIS)

    A mercuric iodide (HgI2) gamma ray imaging array and camera system previously described have been characterized for spatial and energy resolution. Based on these data a new camera is being developed to more fully exploit the potential of the array. Characterization results and design criteria for the new camera will be presented. (orig.)

  1. Developments in mercuric iodide gamma ray imaging

    Science.gov (United States)

    Patt, B. E.; Beyerle, A. G.; Dolin, R. C.; Ortale, C.

    1989-11-01

    A mercuric iodide (HgI2) gamma ray imaging array and camera system previously described have been characterized for spatial and energy resolution. Based on these data a new camera is being developed to more fully exploit the potential of the array. Characterization results and design criteria for the new camera will be presented.

  2. Developments in mercuric iodide gamma ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Patt, B.E.; Beyerle, A.G.; Dolin, R.C.; Ortale, C.

    1987-01-01

    A mercuric iodide gamma-ray imaging array and camera system previously described has been characterized for spatial and energy resolution. Based on this data a new camera is being developed to more fully exploit the potential of the array. Characterization results and design criterion for the new camera will be presented. 2 refs., 7 figs.

  3. Developments in mercuric iodide gamma ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Patt, B.E.; Beyerle, A.G.; Dolin, R.C.; Ortale, C. (EG and G Energy Measurements, Inc., Goleta, CA (USA). Santa Barbara Operations)

    1989-11-01

    A mercuric iodide (HgI{sub 2}) gamma ray imaging array and camera system previously described have been characterized for spatial and energy resolution. Based on these data a new camera is being developed to more fully exploit the potential of the array. Characterization results and design criteria for the new camera will be presented. (orig.).

  4. Gamma-Ray Telescope and Uncertainty Principle

    Science.gov (United States)

    Shivalingaswamy, T.; Kagali, B. A.

    2012-01-01

    Heisenberg's Uncertainty Principle is one of the important basic principles of quantum mechanics. In most of the books on quantum mechanics, this uncertainty principle is generally illustrated with the help of a gamma ray microscope, wherein neither the image formation criterion nor the lens properties are taken into account. Thus a better…

  5. Gamma-ray emission from thunderstorm discharges

    International Nuclear Information System (INIS)

    Fine features of gamma-ray radiation registered during a thunderstorm at Tien-Shan Mountain Cosmic Ray Station are presented. Long duration (100-600 ms) gamma-ray bursts are found. They are for the first time identified with atmospheric discharges (lighting). Gamma-ray emission lasts all the time of the discharge and is extremely non-uniform consisting of numerous flashes. Its peak intensity in the flashes exceeds the gamma-ray background up to two orders of magnitude. Exclusively strong altitude dependence of gamma radiation is found. The observation of gamma radiation at the height 4-8 km could serve as a new important method of atmospheric discharge processes investigation. - Highlights: → Gamma-radiation bursts always accompany the electric discharges in atmosphere. → The gamma burst fill up the time of an atmospheric discharge completely. → The higher is the discharge electric field change - the higher is gamma intensity. → The temporal distribution of gamma intensity during the burst is non-uniform. → The altitude dependence of the burst gamma intensity is dramatic.

  6. Gamma ray induced female mutation in castor

    International Nuclear Information System (INIS)

    Three female mutants in castor (Ricinus communis L.) were obtained from 100 to 125 kR gamma-rays treated M2 population. The racemes of these mutants bore only pistillate flowers. This character is monogenic, recessive and these mutants can be used for large scale hybrid seed production

  7. Gamma-ray emission from thunderstorm discharges

    Energy Technology Data Exchange (ETDEWEB)

    Gurevich, A.V., E-mail: alex@lpi.r [P. N. Lebedev Physical Institute, Moscow (Russian Federation); Chubenko, A.P. [P. N. Lebedev Physical Institute, Moscow (Russian Federation); Karashtin, A.N. [Radiophysical Research Institute, Nizhny Novgorod (Russian Federation); Mitko, G.G.; Naumov, A.S.; Ptitsyn, M.O.; Ryabov, V.A.; Shepetov, A.L. [P. N. Lebedev Physical Institute, Moscow (Russian Federation); Shlyugaev, Yu.V. [Radiophysical Research Institute, Nizhny Novgorod (Russian Federation); Vildanova, L.I. [Tien-Shan Mountain Cosmic Ray Station, Almaty (Kazakhstan); Zybin, K.P. [P. N. Lebedev Physical Institute, Moscow (Russian Federation)

    2011-04-11

    Fine features of gamma-ray radiation registered during a thunderstorm at Tien-Shan Mountain Cosmic Ray Station are presented. Long duration (100-600 ms) gamma-ray bursts are found. They are for the first time identified with atmospheric discharges (lighting). Gamma-ray emission lasts all the time of the discharge and is extremely non-uniform consisting of numerous flashes. Its peak intensity in the flashes exceeds the gamma-ray background up to two orders of magnitude. Exclusively strong altitude dependence of gamma radiation is found. The observation of gamma radiation at the height 4-8 km could serve as a new important method of atmospheric discharge processes investigation. - Highlights: Gamma-radiation bursts always accompany the electric discharges in atmosphere. The gamma burst fill up the time of an atmospheric discharge completely. The higher is the discharge electric field change - the higher is gamma intensity. The temporal distribution of gamma intensity during the burst is non-uniform. The altitude dependence of the burst gamma intensity is dramatic.

  8. The single backscattering of gamma rays

    International Nuclear Information System (INIS)

    The paper presents the results of the single backscattering investigations of gamma rays in various materials. A simplified mathematical model is given for determining the probability that a photon scattered back by a single Compton scattering is incident on the detector. The probability is calculated as a function of the primary photon energy and the atomic number Z of the scatterer. (Auth.)

  9. Neutrino Balls and Gamma-Ray Bursts

    CERN Document Server

    Holdom, B

    1994-01-01

    We propose a mechanism by which the neutrino emission from a supernova-type explosion can be converted into a gamma-ray burst of total energy $\\sim 10^{50}$ ergs. This occurs naturally if the explosion is situated inside a ball of trapped neutrinos, which in turn may lie at a galactic core. There are possible unique signatures of this scenario.

  10. Primary shutter and gamma ray trap

    International Nuclear Information System (INIS)

    This paper reports on the main radiation shutter and gamma ray trap, which will be used at LNLS front-ends that has been designed. The components external to the UHV chamber have been assembled and are undergoing tests. Vacuum requirements for the chamber have been estimated

  11. The new gamma-ray observatory: CTA

    Science.gov (United States)

    Carr, John

    2016-07-01

    CTA is the next generation gamma-ray observatory and will have a factor 10 better sensitivity compared to existing facilities, as well as many other superior parameters. Aspects of array layout, performance and sites are presented. The broad range of forefront science which will be studied is described.

  12. Gamma-rays from Type Ia supernova SN2014J

    CERN Document Server

    Churazov, E; Isern, J; Bikmaev, I; Bravo, E; Chugai, N; Grebenev, S; Jean, P; Knödlseder, J; Lebrun, F; Kuulkers, E

    2015-01-01

    The whole set of INTEGRAL observations of type Ia supernova SN2014J, covering the period 16-162 days after the explosion has being analyzed. For spectral fitting the data are split into early and late periods covering days 16-35 and 50-162, respectively, optimized for Ni-56 and Co-56 lines. As expected for the early period much of the gamma-ray signal is confined to energies below $\\sim$200 keV, while for the late period it is most strong above 400 keV. In particular, in the late period Co-56 lines at 847 and 1248 keV are detected at 4.7 and 4.3 sigma respectively. The lightcurves in several representative energy bands are calculated for the entire period. The resulting spectra and lightcurves are compared with a subset of models. We confirm our previous finding that the gamma-ray data are broadly consistent with the expectations for canonical 1D models, such as delayed detonation or deflagration models for a near-Chandrasekhar mass WD. Late optical spectra (day 136 after the explosion) show rather symmetric ...

  13. Neutron-induced gamma-ray measurements on soft landers

    International Nuclear Information System (INIS)

    Gamma-ray spectra provide useful data in the study of the development of planets. Measurements made on landers overcome many of the limitations of orbital measurements, especially for solar-system bodies where atmospheres interfere with obtaining orbital data. Elemental compositions can be inferred from the spectra, produced by neutron interactions with nuclei of the planetary body. The cosmic ray flux yields a relatively low neutron flux requiring long integration times (sometimes as long as a year) to obtain a statistical accuracy allowing elemental compositions to be inferred to determine different mineral compositions and to characterize the nature of the area studied. A recent advance is the combination of a gamma-ray spectrometer with a compact, pulsed neutron generator, which increases the neutron flux by orders of magnitude. Such a device is used on Earth and its capability is being extended to operate within the low weight and power requirements of typical lander missions. A pulsed source permits data accumulation by type of reaction, increasing the sensitivity for detecting many elements. The enhanced speed of measurement makes many new studies possible, such as time-dependent measurements to detect seasonal or diurnal changes from active processes. Where motion is provided, either around the lander or on a rover, data can be obtained at different positions to evaluate heterogeneities. The use of a pulsed neutron generator provides increased quality of elemental data and provides many additional options for system design to provide more useful information for understanding the creation and evolution of our solar system

  14. ATCA monitoring of gamma-ray loud AGN

    CERN Document Server

    Stevens, J; Ojha, R; Kadler, M; Hungwe, F; Dutka, M; Tingay, S; Macquart, J P; Moin, A; Lovell, J; Blanchard, J

    2012-01-01

    As a critical part of the Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry (TANAMI) program, in November 2007 the Australia Telescope Compact Array (ATCA) started monitoring the radio spectra of a sample of southern hemisphere active galactic nuclei (AGN) that were selected as likely candidates for detection (as well as a control sample) by the Large Area Telescope (LAT) aboard the Fermi Gamma Ray Space Observatory. The initial sample was chosen based on properties determined from AGN detections by the Energetic Gamma Ray Experiment Telescope (EGRET). Most of the initial sample has been detected by Fermi/LAT and with the addition of new detections the sample has grown to include 226 AGN, 133 of which have data for more than one epoch. For the majority of these AGN, our monitoring program provides the only dynamic radio spectra available. The ATCA receiver suite makes it possible to observe several sources at frequencies between 4.5 and 41 GHz in a few hours, resulting in an excellent...

  15. Slow neutrons and secondary gamma ray distributions in concrete shields followed by reflecting layers

    International Nuclear Information System (INIS)

    Slow neutrons and secondary gamma ray distributions in concrete shields with and without a reflecting layer behind layer behind the concrete shield have been investigated first in case of using a bare reactor beam and then on using a B-4 C filtered beam. The total and capture secondary gamma ray coefficient (B gamma and B gammaC), the ratio of the reflected thermal neutron (gamma) the ratio of the secondary gamma rays caused by reflected neutrons to those caused transmitted neutrons (ThI gamma/FI gamma) and the effect of inserting a blocking layer (a B-4 C layer) between the concrete shield and the reflector on the suppression of the produced secondary gamma rays have been investigated. It was found that the presence of the reflector layer behind the concrete shield reflects some thermal neutrons back to the concrete shields and so it increases the number of thermal neutrons at the interface between the concrete shield and the reflector. Also the capture secondary gamma rays was increased at the interface between the two medii due to the capture of the reflected thermal neutrons in the concrete shields. It was shown that B-gamma is higher than and that Bgamma B gammaC and I gammaTh/ I gammaif for the different concrete types is higher in case of using the graphite reflector than that in using either water or paraffin reflectors. Putting a blocking layer (B4C layer) between the concrete shield and the reflector decreases the produced secondary gamma rays due to the absorption of the reflected thermal neutrons. 17 figs

  16. Study of the fluctuations of the partial and total radiative widths by neutron capture resonance method

    International Nuclear Information System (INIS)

    Radiative capture experiments by neutron time-of-flight methods have been made for following studies: distribution of partial radiative widths, effects of correlation between different radiative transitions, fluctuations of total radiative widths Γγ from resonance to resonance, variation of Γγ with number of mass and the search for the existence of potential capture. Also, some other experiments with the use of neutron capture gamma-rays spectra have been investigated. (author)

  17. Interstellar medium structure and content and gamma ray astronomy

    International Nuclear Information System (INIS)

    A general description of gamma-ray astronomy is presented with special emphasis on the study of diffuse gamma-ray emission. This is followed by a collection of reflections and observations on the structure and the gas and dust content of the local interstellar medium. Results of gamma-ray observations on the local interstellar medium are given. The last part is devoted to the whole of the galactic gamma-ray emission and its interpretation

  18. Zinc oxide nanowire gamma ray detector with high spatiotemporal resolution

    Science.gov (United States)

    Mayo, Daniel C.; Nolen, J. Ryan; Cook, Andrew; Mu, Richard R.; Haglund, Richard F.

    2016-03-01

    Conventional scintillation detectors are typically single crystals of heavy-metal oxides or halides doped with rare-earth ions that record the recombination of electron-hole pairs by photon emission in the visible to ultraviolet. However, the light yields are typically low enough to require photomultiplier detection with the attendant instrumental complications. Here we report initial studies of gamma ray detection by zinc oxide (ZnO) nanowires, grown by vapor-solid deposition. The nanowires grow along the c-axis in a wurtzite structure; they are typically 80 nm in diameter and have lengths of 1- 2 μm. The nanowires are single crystals of high quality, with a photoluminescence (PL) yield from band-edge exciton emission in the ultraviolet that is typically one hundred times larger than the PL yield from defect centers in the visible. Nanowire ensembles were irradiated by 662 keV gamma rays from a Cs-137 source for periods of up to ten hours; gamma rays in this energy range interact by Compton scattering, which in ZnO creates F+ centers that relax to form singly-charged positive oxygen vacancies. Following irradiation, we fit the PL spectra of the visible emission with a sum of Gaussians at the energies of the known defects. We find highly efficient PL from the irradiated area, with a figure of merit approaching 106 photons/s/MeV of deposited energy. Over a period of days, the singly charged O+ vacancies relax to the more stable doubly charged O++ vacancies. However, the overall defect PL returns to pre-irradiation values after about a week, as the vacancies diffuse to the surface of these very thin nanowires, indicating that a self-healing process restores the nanowires to their original state.

  19. Method and apparatus for nuclear logging making use of lithium detectors and equipment for gamma ray stripping

    International Nuclear Information System (INIS)

    The patent deals with a borehole logging tool where a pair of spaced-apart lithium detectors is lowered into a borehole traversing a sursurface formation. The formation is irradiated with bursts of neutrons, and the neutrons returning to the borehole are detected by thermal neutron detectors. The dieaway gamma ray spectra provide information on the formation porosity. A MWD system includes a programmable gain amplifier and gamma ray stripping means. 30 figs

  20. Electron acceleration in supernova remnants and diffuse gamma rays above 1 GeV

    DEFF Research Database (Denmark)

    Pohl, M.; Esposito, J.A.

    1998-01-01

    radio synchrotron spectrum of individual SNRs. We use a three-dimensional propagation code to calculate the spectra of electrons throughout the Galaxy and show that the longitude and latitude distribution of the leptonic gamma-ray production above 1 GeV is in accord with the respective distributions for...

  1. Balloon-borne gamma-ray telescope with nuclear emulsion

    OpenAIRE

    Takahashi, Satoru; Group, for the Emulsion Gamma-ray Telescope

    2010-01-01

    By detecting the beginning of electron pairs with nuclear emulsion, precise gamma-ray direction and gamma-ray polarization can be detected. With recent advancement in emulsion scanning system, emulsion analyzing capability is becoming powerful. Now we are developing the balloon-borne gamma-ray telescope with nuclear emulsion. Overview and status of our telescope is described.

  2. Determination of protein content in seeds by prompt gamma-ray spectrometry

    International Nuclear Information System (INIS)

    The protein level in seeds can be directly calculated through the determination of the nitrogen content in grains. The authors show here that the radioactive thermal neutron capture prompt gamma-rays technique can be used to determine the nitrogen content in grains without chemical destruction, with good precision and relative rapidity, by detecting the prompt gamma rays emitted by the 14N(n,γ)15N reaction product. The samples were irradiated in the tangential tube of the IEA-R1 research reactor, in Sao Paulo, and a pair spectrometer was used for the detection of the prompt gamma-rays. The nitrogen content was determined in several samples of soybean, common bean, peas and rice and the results compared with typical nitrogen content values for each grain. 33 references, 1 figure, 1 table

  3. A gamma-ray transient at the position of DG CVn

    Science.gov (United States)

    Loh, A.; Corbel, S.; Dubus, G.

    2015-12-01

    Solar flares are regularly detected by the Large Area Telescope (LAT) on board the Fermi satellite, however no gamma-ray emission from other stellar eruptions has ever been captured. A recent Swift detection of a powerful outburst originating from the nearby binary star DG CVn, with optical and radio counterparts, gave us an opportunity to measure the 0.1--100 GeV emission from this kind of objects for the first time. We performed a deep LAT study over the past six years of the Fermi mission and we report a significant gamma-ray excess in November 2012, at a position consistent with this binary at a 2σ confidence level. Since no multi-wavelength coverage was available in 2012 and because no high-energy emission was detected during the recent X-ray superflare, we discuss the possible origin of this gamma-ray transient.

  4. Study of X-rays and nuclear gamma -rays in muonic thallium

    CERN Document Server

    Backe, H; Jahnke, U; Kankeleit, E; Pearce, R M; Petitjean, C; Schellenberg, L; Schneuwly, H; Schröder, W U; Walter, H K; Zehnder, A

    1972-01-01

    Energies and intensities of muonic X-rays, nuclear gamma -rays and mu -capture gamma -rays were measured in natural muonic thallium with Ge (Li) detectors. The absolute intensities of higher mu X-rays were reproduced by a cascade calculation starting with a statistical population at n=20 including K-, L- and M-conversion. The electron screening effect was deduced from energies of higher mu X-rays. Eight prompt nuclear gamma -rays were found. This excitation explains the anomalous intensity ratios of the 2p-1s and 3d-2p fine structure components. From the nuclear gamma -rays of the first excited states were deduced: the magnetic h.f. splittings, muonic isomer shifts E2/M1 mixing ratios and the half-life in the presence of the muon in /sup 205/Tl. Evidence for a magnetic nuclear polarization was found. An isotope shift of Delta E=10.35+or-0.25 keV was measured for the 1s/sub 1/2/ state which is compared with data from optical spectroscopy. From an analysis of the time distribution of delayed gamma -rays from mu...

  5. Fermi/GBM and BATSE Gamma-Ray Bursts: comparison of the spectral properties

    OpenAIRE

    Nava, Lara; Ghirlanda, Giancarlo; Ghisellini, Gabriele; Celotti, Annalisa

    2010-01-01

    The Gamma-ray Burst Monitor (GBM) on board Fermi allows to study the spectra of Gamma Ray Bursts (GRBs) over an unprecedented wide energy range (8 keV - 35 MeV). We compare the spectral properties of short and long GRBs detected by the GBM (up to March 2010) with those of GRBs detected by the BATSE instrument on board the CGRO. GBM and BATSE long bursts have similar distributions of fluence (F), Epeak and peak flux (P) but GBM bursts have a slightly harder low-energy spectral index \\alpha wit...

  6. Fermi-LAT Detection of Gamma-ray Pulsars above 10 GeV

    CERN Document Server

    Parkinson, Pablo M Saz

    2012-01-01

    The Large Area Telescope (LAT) on board the Fermi satellite has detected ~120 pulsars above 100 MeV. While most gamma-ray pulsars have spectra that are well modeled by a power law with an exponential cut-off at around a few GeV, some show significant pulsed high-energy (HE, >10 GeV) emission. I present a study of HE emission from LAT gamma-ray pulsars and discuss prospects for the detection of pulsations at very high energies (VHE, >100 GeV) with ground-based instruments.

  7. TRUEE: Regularized unfolding for gamma-ray astronomy

    International Nuclear Information System (INIS)

    The reconstruction of energy spectra from the observables of air-showers is one of the main tasks during the data analysis of many astroparticle experiments. The new unfolding program TRUEE, which is based on V. Blobel's RUN, offers the possibility to perform a regularized unfolding of energy spectra. It uses up to 3 observables, treats the background of the measurement and takes into account the correction for the limited acceptance of the detector. After a successful application to IceCube measurements, this method is now being used for gamma-ray data. The program has been integrated into the analysis chain of the MAGIC experiment. This includes the development of an interface between the MAGIC and TRUEE data formats, the optimal choice of observed parameters to be used in the unfolding, and subsequent functionalities like fits to the obtained spectrum. The functionality of the present implementation and an example application is presented, and an outlook for further enhancements is given.

  8. Impact of Secondary Acceleration in Gamma-Ray Bursts

    CERN Document Server

    Winter, Walter; Klein, Spencer R

    2014-01-01

    We discuss the acceleration of secondary muons, pions, and kaons in gamma-ray bursts within the internal shock scenario, and their impact on the neutrino fluxes. We introduce a two-zone model consisting of an acceleration zone (the shocks) and a radiation zone (the plasma downstream the shocks). The acceleration in the shocks, which is an unavoidable consequence of the efficient proton acceleration, requires efficient transport from the radiation back to the acceleration zone. On the other hand, stochastic acceleration in the radiation zone can enhance the secondary spectra of muons and kaons significantly if there is a sufficiently large turbulent region. Overall, it is plausible that neutrino spectra can be enhanced by up to a factor of two at the peak by stochastic acceleration, that an additional spectral peaks appears from shock acceleration of the secondary muons and pions, and that the neutrino production from kaon decays is enhanced. Depending on the GRB parameters, the general conclusions concerning ...

  9. The BATSE 5B Gamma-Ray Burst Spectral Catalog

    CERN Document Server

    Goldstein, A; Mallozzi, R S; Briggs, M S; Fishman, G J; Kouveliotou, C; Pacieses, W S; Burgess, J M

    2013-01-01

    We present systematic spectral analyses of GRBs detected with the Burst and Transient Source Experiment (BATSE) onboard the Compton Gamma-Ray Observatory (CGRO) during its entire nine years of operation. This catalog contains two types of spectra extracted from 2145 GRBs and fitted with five different spectral models resulting in a compendium of over 19000 spectra. The models were selected based on their empirical importance to the spectral shape of many GRBs, and the analysis performed was devised to be as thorough and objective as possible. We describe in detail our procedures and criteria for the analyses, and present the bulk results in the form of parameter distributions. This catalog should be considered an official product from the BATSE Science Team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center (HEASARC).

  10. Determination of the (He-3)/H ratio in the solar photosphere from flare gamma-ray line observations

    International Nuclear Information System (INIS)

    The time dependence of the 2.223 MeV gamma-ray line emission from the capture of flare-produced neutrons in the solar photosphere provides a sensitive measure of the He-3 abundance there. Monte Carlo calculations have been made of this time dependence as a function of both He-3 abundance and observing angle for neutrons produced by thick-target interactions of flare-accelerated ions with a range of incident energy spectra and angular distributions. Assuming a mirroring distribution, suggested by other observations, it is found that the Solar Maximum Mission measurements of the time dependence of the 2.223 MeV line emission from the solar flare of June 3, 1982, imply a solar photospheric (He-3)/H ratio of (2.3 + or - 1.2) x 10 to the -5th at the 90 percent confidence level. 44 references

  11. U-238 neutron-capture gamma-cascade generation and transport simulation for capture-tank response (final report). Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Rosener, T.J.

    1992-05-07

    A computer analysis has been performed to evaluate the energy dependent response of a capture tank to the gamma rays emitted in the cascades of the excited U-239 nucleus. This model determines the energies of the gamma-ray cascades, the order of emission of the gamma rays in a cascade, and the gamma-ray multiplicity of the cascades using Monte Carlo techniques. A capture tank responds to the combined effect of the various gamma rays emitted in the cascade. Examined is the energy deposition in a capture tank by the cascades generated in resonant (surface) capture and off-resonant (volumetric) capture, with and without internal conversion. Off-resonant capture deposits, on the average, less energy than resonant capture, due to self-shielding of the gamma-rays in the capture sample. Internal conversion has negligible effect on the average cascade energy deposited in the capture tank. Gamma-ray cascade, Capture tank, U-238 neutron capture.

  12. Energy dependent gamma-ray morphology in the Pulsar wind nebula HESSJ1825-137

    CERN Document Server

    Aharonian, F

    2006-01-01

    Detailed morphological and spatially resolved spectral studies reveal the very high-energy (VHE) gamma-ray aspects of this object with unprecedented precision. We confirm previous results obtained in a survey of the Galactic Plane in 2004. The gamma-ray emission extends asymmetrically to the south and south-west of the energetic pulsar PSR J1826-1334, that is thought to power the pulsar wind nebula. The differential gamma-ray spectrum of the whole emission region is measured over more than two orders of magnitude, from 270 GeV to 35 TeV, and shows indications for a deviation from a pure power law. Spectra have also been determined for spatially separated regions of HESS J1825-137. The photon indices from a power-law fit in the different regions show a softening of the spectrum with increasing distance from the pulsar and therefore an energy dependent morphology. This is the first time that an energy dependent morphology has been detected in the VHE gamma-ray regime. The VHE gamma-ray emission of HESS J1825-13...

  13. Neutrino, $\\gamma$-ray and cosmic ray fluxes from the core of the closest radio galaxies

    CERN Document Server

    Fraija, Nissim

    2016-01-01

    The closest radio galaxies; Centaurus A, M87 and NGC 1275, have been detected from radio wavelengths to TeV $\\gamma$-rays, and also studied as high-energy neutrino and ultra-high-energy cosmic ray potential emitters. Their spectral energy distributions show a double-peak feature, which is explained by synchrotron self-Compton model. However, TeV $\\gamma$-ray measured spectra could suggest that very-high-energy $\\gamma$-rays might have a hadronic origin. We introduce a lepto-hadronic model to describe the broadband spectral energy distribution; from radio to sub GeV photons as synchrotron self-Compton emission and TeV $\\gamma$-ray photons as neutral pion decay resulting from p$\\gamma$ interactions occurring close to the core. These photo-hadronic interactions take place when Fermi-accelerated protons interact with the seed photons around synchrotron self-Compton peaks. Obtaining a good description of the TeV $\\gamma$-ray fluxes, firstly, we compute neutrino fluxes and events expected in IceCube detector and se...

  14. Statistical Measurement of the Gamma-Ray Source-count Distribution as a Function of Energy

    Science.gov (United States)

    Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza; Fornengo, Nicolao; Regis, Marco

    2016-08-01

    Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. We employ the 1-point probability distribution function of six years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy. To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 and 171 GeV. It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of ˜50 GeV. The index below the break is between 1.95 and 2.0. For higher energies, a simple power-law fits the data, with an index of {2.2}-0.3+0.7 in the energy band between 50 and 171 GeV. Upper limits on further possible breaks as well as the angular power of unresolved sources are derived. We find that point-source populations probed by this method can explain {83}-13+7% ({81}-19+52%) of the extragalactic gamma-ray background between 1.04 and 1.99 GeV (50 and 171 GeV). The method has excellent capabilities for constraining the gamma-ray luminosity function and the spectra of unresolved blazars.

  15. Long-duration gamma-ray emissions from 2007 and 2008 winter thunderstorms

    CERN Document Server

    Tsuchiya, H; Yamada, S; Yuasa, T; Nakazawa, K; Kitaguchi, T; Kawaharada, M; Kokubun, M; Kato, H; Okano, M; Makishima, K

    2011-01-01

    The Gamma-Ray Observation of Winter THunderclouds (GROWTH) experiment, consisting of two radiation-detection subsystems, has been operating since 2006 on the premises of Kashiwazaki-Kariwa nuclear power plant located at the coastal area of Japan Sea. By 2010 February, GROWTH detected 7 long-duration $\\gamma$-rays emissions associated with winter thunderstorms. Of them, two events, obtained on 2007 December 13 and 2008 December 25, are reported.On both occasions, all inorganic scintillators (NaI, CsI, and BGO) of the two subsystems detected significant gamma-ray signals lasting for >1 minute. Neither of these two events were associated with any lightning. In both cases, the gamma-ray energy spectra extend to 10 MeV, suggesting that the detected gamma-rays are produced by relativistic electrons via bremsstrahlung. Assuming that the initial photon spectrum at the source is expressed by a power-law function,the observed photons can be interpreted as being radiated from a source located at a distance of 290-560 m ...

  16. Development of underwater gamma ray measurement system for spent fuel verification

    International Nuclear Information System (INIS)

    A gamma ray measurement system (GAMESY) was designed and developed to measure the gamma rays of spent nuclear fuel nondestructively in pool, and the performance test on the system was carried out in the spent fuel storage pool of KAERI's post irradiation examination facility. As the results of the mechanical performance test, the GAMESY showed a good position reproducibility and precision within ±1 mm along full scanning length and a perfect watertightness of the detection chamber immersed in 9m deep water. The preliminary experiment for energy resolution and radiation shielding in detection part were performed both in air by using standard gamma ray source and in pool water by using PWR rods with the average burnup of 36GWD/tU. The results showed that the 10 extension cable between detector preamplifier and amplifier did not cause any deterioration of signal in its energy resolution, and the detector shielding thickness of about 15cm Pb equivalent seemed to be sufficient for minimizing the unwanted gamma rays coming from the off slit region. From these results, it is believed that the newly developed prototype GAMESY can be used for the verification and accounting for spent nuclear fuel material for the purpose of nuclear material safeguards by determining several characteristics such as burnup profile and cooling time that are obtainable from the measured gamma ray spectra

  17. The Second Fermi Large Area Telescope Catalog of Gamma-ray Pulsars

    CERN Document Server

    ,

    2013-01-01

    This catalog summarizes 117 high-confidence > 0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data, through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars. We compare the gamma-ray properties with those in the radio, optical, and X-ray bands. We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sam...

  18. A Deep Observation of Gamma-ray Emission from Cassiopeia A using VERITAS

    CERN Document Server

    Ghiotto, Augusto

    2015-01-01

    Supernova remnants (SNRs) have long been considered the leading candidates for the accelerators of cosmic rays within the Galaxy through the process of diffusive shock acceleration. The connection between SNRs and cosmic rays is supported by the detection of high energy (HE; 100 MeV to 100 GeV) and very high energy (VHE; 100 GeV to 100 TeV) gamma rays from young and middle-aged SNRs. However, the interpretation of the gamma-ray observations is not unique. This is because gamma rays can be produced both by electrons through non-thermal Bremsstrahlung and inverse Compton scattering, and by protons through proton-proton collisions and subsequent neutral-pion decay. To disentangle and quantify the contributions of electrons and protons to the gamma-ray flux, it is necessary to measure precisely the spectra and morphology of SNRs over a broad range of gamma-ray energies. Cassiopeia A (Cas A) is one such young SNR (~ 350 years) which is bright in radio and X-rays. It has been detected as a bright point source in HE...

  19. Observation of Gamma Rays from the Galactic Center with the MAGIC Telescope

    CERN Document Server

    Albert, J; Anderhub, H; Antoranz, P; Armada, A; Asensio, M; Baixeras, C; Barrio, J A; Bartelt, M; Bartko, H; Bastieri, D; Bavikadi, R; Bednarek, W; Berger, K; Bigongiari, C; Biland, A; Bisesi, E; Bretz, T; Britvitch, I; Böck, R K; Camara, M; Chilingarian, A A; Ciprini, S; Coarasa, J A; Commichau, S C; Contreras, J l; Cortina, J; Curtef, V; Danielyan, V; Dazzi, F; Deangelis, A; Delosreyes, R; Delotto, B; Domingo-Santamaria, E; Dorner, D; Doro, M; Errando, M; Fagiolini, M; Ferenc, D; Fernández, E; Firpo, R; Flix, J; Fonseca, M V; Font, L; Galante, N; Garczarczyk, M; Gaug, M; Giller, M; Göbel, F; Hakobyan, D; Hayashida, M; Hengstebeck, T; Hose, J; Höhne, D; Jacon, P; Kalekin, o; Kranich, D; Laille, A; Liebing, P; Lindfors, E; Longo, F; Lorenz, E; Lucarelli, F; López, J; López, M; Majumdar, P; Maneva, g; Mannheim, K; Mariotti, M; Martínez, M; Mase, K; Mazin, D; Merck, M; Meucci, M; Meyer, M; Miranda, J m; Mirzoyan, R; Mizobuchi, S; Moralejo, A; Nilsson, K; Oña-Wilhelmi, E; Orduna, R; Otte, N; Oya, I; Paneque, D; Paoletti, R; Pasanen, M; Pascoli, D; Pauss, F; Pavel, N; Pegna, R; Peruzzo, L; Piccioli, A; Prandini, E; Rhode, W; Rico, J; Riegel, B; Rissi, M; Robert, A; Rugamer, S; Saggion, A; Sartori, P; Scalzotto, V; Schmitt, R; Schweizer, T; Shayduk, M; Shinozaki, K; Shore, S N; Sidro, N; Sillanp, A; Sobczynska, D; Stamerra, A; Stark, L S; Stepanian, A; Sánchez, A; Takalo, L; Temnikov, P; Tescaro, D; Teshima, M; Tonello, N; Torres, A; Torres, D F; Turini, N; Vankov, H; Vardanyan, A; Vitale, V; Wagner, R M; Wibig, T; Wittek, W; Zapatero, J

    2006-01-01

    Recently, the Galactic Center has been reported to be a source of very high energy (VHE) gamma-rays by the VERITAS, CANGAROO and HESS experiments. The energy spectra as measured by these experiments show substantial differences. In this Letter we present MAGIC observations of the Galactic Center, resulting in the detection of a differential gamma-ray flux consistent with a steady, hard-slope power law, described as dN/(dA dt dE) = (2.9+/-0.6)*10^{-12} (E/TeV)^{-2.2+/-0.2} cm^{-2}s^{-1}TeV^{-1}. The gamma-ray source is centered at (Ra, Dec)=(17h 45m 20s, -29deg 2'. This result confirms the previous measurements by the HESS experiment and indicates a steady source of TeV gamma-rays. We briefly describe the observational technique used, the procedure implemented for the data analysis, and discuss the results in the perspective of different models proposed for the acceleration of the VHE gamma-rays.

  20. Removal cross sections and total mass attenuation coefficients of fast neutrons and gamma rays for steel

    International Nuclear Information System (INIS)

    The present work deals with the study of the attenuation properties and determination of the cross sections of fast neutrons and gamma rays for structure steel used in different applications in nuclear power plants, particle accelerators, research reactors and different radiation attenuation fields. Investigation has been performed by measuring the transmitted fast neutron and gamma ray spectra behind cylindrical samples of steel (ρ=7.87 gem-3) of different thicknesses. A reactor collimated beam and neutron - gamma spectrometer with stiblbene scintillator were used for measurements. The pluse shape disriminate technique based on zero cross over method was used to discriminate between neutron and gamma ray pulses. Effective removal cross-section (σR) and total mass attenuation coefficient (μ) of neureons and gamma rays have been achieved using the attenuation relations. Microscopic removal cross sections σ98 and mass removal cross sections σR/ρ of fast neutrons have been evaluated based on measured results and definite energies. Also, total mass attenuation coefficients (μ/σ) of gamma rays have been evalusted and calculated using measured results and XCOM code respectively. Comparison between measured and calculated results shows a resonable agreement between the two