WorldWideScience

Sample records for astrophysical gamma ray

  1. Gamma-ray astrophysics

    International Nuclear Information System (INIS)

    Fichtel, C.E.

    1977-01-01

    The most striking feature of the celestial sphere when viewed in the frequency range of γ-rays is the emission from the galactic plane, which is particularly intense in the galactic longitudinal region from 300 0 to 50 0 . The longitudinal and latitudinal distributions are generally correlated with galactic structural features and when studied in detail suggest a non-uniform distribution of cosmic rays in the galaxy. Several point γ-ray sources have now been observed, including four radio pulsars. This last result is particularly striking since only one radio pulsar has been seen at either optical or X-ray frequencies. Nuclear γ-ray lines have been seen from the Sun during a large solar flare and future satellite experiments are planned to search for γ-ray lines from supernovae and their remnants. A general apparently diffuse flux of γ-rays has also been seen whose energy spectrum has interesting implications; however, in view of the possible contribution of point sources and the observation of galactic features such as Gould's belt, its interpretation must await γ-ray experiments with finer spatial and energy resolution, as well as greater sensitivity. (Auth.)

  2. Extragalactic Gamma-Ray Astrophysics

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    During the last decades, various classes of radio-loud active galactic nuclei have been established as sources of high-energy radiation extending over a very broad range from soft gamma-rays (photon energies E~MeV) up to very-high-energy gamma-rays (E>100 GeV). These include blazars of different types, as well as young and evolved radio galaxies. The observed gamma-ray emission from such implies efficient particle acceleration processes taking place in highly magnetized and relativistic jets produced by supermassive black holes, processes that have yet to be identified and properly understood. In addition, nearby starforming and starburst galaxies, some of which host radio-quiet Seyfert-type nuclei, have been detected in the gamma-ray range as well. In their cases, the observed gamma-ray emission is due to non-thermal activity in the interstellar medium, possibly including also a contribution from accretion disks and nuclear outflows. Finally, the high-energy emission from clusters of galaxies remains elusive...

  3. The Future of Gamma Ray Astrophysics

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Over the past decade, gamma ray astrophysics has entered the astrophysical mainstream. Extremely successful space-borne (GeV) and ground-based (TeV) detectors, combined with a multitude of partner telescopes, have revealed a fascinating “astroscape" of active galactic nuclei, pulsars, gamma ray bursts, supernova remnants, binary stars, star-forming galaxies, novae much more, exhibiting major pathways along which large energy releases can flow. From  a basic physics perspective, exquisitely sensitive measurements have constrained the nature of dark matter, the cosmological origin of magnetic field and the properties of black holes. These advances have motivated the development of new facilities, including HAWC, DAMPE, CTA and SVOM, which will further our understanding of the high energy universe. Topics that will receive special attention include merging neutron star binaries, clusters of galaxies, galactic cosmic rays and putative, TeV dark matter.

  4. Gamma-ray bursts: astrophysical puzzle of the century

    International Nuclear Information System (INIS)

    Hudec, R.

    1998-01-01

    An overview is given of the problems of gamma-ray bursts /GRB/. As GRB became one of the greatest mysteries in modern astrophysics, this field of astrophysics is a subject of intensive research. The article covers some topical aspects of experiments related to the indentification of gamma-ray bursts. The preparation and results of experiments in the Astronomical Institute of the Academy of Sciences of the Czech Republic are described. (Z.J.)

  5. Very high energy gamma ray astrophysics

    International Nuclear Information System (INIS)

    Lamb, R.C.; Lewis, D.A.

    1991-01-01

    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

  6. Very high energy gamma ray astrophysics

    International Nuclear Information System (INIS)

    Lamb, R.C.; Lewis, D.A.

    1986-01-01

    The Whipple Observatory's atmospheric Cerenkov camera has detected TeV radiation from four galactic sources: the Crab Nebula, Cygnus X-3, Hercules X-1, and 4U0115+63. Recent simulations encourage the view that unwanted cosmic-ray background showers may be suppressed by a large factor. Emphasis in the coming year will be on determining optimum selection criteria for enhancing gamma-ray signals and in developing a prototype camera with finer angular resolution as a first step towards implementation of the HERCULES concept

  7. Very high energy gamma ray astrophysics

    International Nuclear Information System (INIS)

    Lamb, R.C.; Lewis, D.A.

    1990-02-01

    Our scientific goal is to discover and study by means of gamma-ray astronomy those regions of the universe where particles are accelerated to extreme energies. The atmospheric Cherenkov technique provides a unique and potentially sensitive window in the region of 10 11 to approximately 10 14 eV for this purpose. The Whipple Observatory Collaboration is currently engaged in the development of a Cherenkov camera which has the ultimate capability of distinguishing gamma-ray showers from the numerous cosmic-ray background showers by imaging the Cherenkov light from each shower. We have recently demonstrated the potential of the imaging technique with our 18 sigma detection of TeV photons from the Crab Nebula using a camera of 10 elements, pixel spacing 0.25 degrees. This detection represents a factor of 10 improvement in sensitivity compared to a non-imaging detector. The next step in the development of the detector is to obtain a second large reflector, similar to the present 10 meter instrument, for stereoscopic viewing of showers. This project, named GRANITE, is now approved by DOE. With GRANITE it should be possible to probe more deeply in space by a factor of 7, and to fully investigate the possibility of new physics which has been suggested by reports of anomalous radiation from Hercules X-1. 18 refs

  8. High energy astrophysics with ground-based gamma ray detectors

    International Nuclear Information System (INIS)

    Aharonian, F; Buckley, J; Kifune, T; Sinnis, G

    2008-01-01

    Recent advances in ground-based gamma ray astronomy have led to the discovery of more than 70 sources of very high energy (E γ ≥ 100 GeV) gamma rays, falling into a number of source populations including pulsar wind nebulae, shell type supernova remnants, Wolf-Rayet stars, giant molecular clouds, binary systems, the Galactic Center, active galactic nuclei and 'dark' (yet unidentified) galactic objects. We summarize the history of TeV gamma ray astronomy up to the current status of the field including a description of experimental techniques and highlight recent astrophysical results. We also discuss the potential of ground-based gamma ray astronomy for future discoveries and describe possible directions for future instrumental developments

  9. Physics and astrophysics with gamma-ray telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Vandenbroucke, J. [Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)

    2012-08-15

    In the past few years gamma-ray astronomy has entered a golden age. A modern suite of telescopes is now scanning the sky over both hemispheres and over six orders of magnitude in energy. At {approx}TeV energies, only a handful of sources were known a decade ago, but the current generation of ground-based imaging atmospheric Cherenkov telescopes (H.E.S.S., MAGIC, and VERITAS) has increased this number to nearly one hundred. With a large field of view and duty cycle, the Tibet and Milagro air shower detectors have demonstrated the promise of the direct particle detection technique for TeV gamma rays. At {approx}GeV energies, the Fermi Gamma-ray Space Telescope has increased the number of known sources by nearly an order of magnitude in its first year of operation. New classes of sources that were previously theorized to be gamma-ray emitters have now been confirmed observationally. Moreover, there have been surprise discoveries of GeV gamma-ray emission from source classes for which no theory predicted it was possible. In addition to elucidating the processes of high-energy astrophysics, gamma-ray telescopes are making essential contributions to fundamental physics topics including quantum gravity, gravitational waves, and dark matter. I summarize the current census of astrophysical gamma-ray sources, highlight some recent discoveries relevant to fundamental physics, and describe the synergetic connections between gamma-ray and neutrino astronomy. This is a brief overview intended in particular for particle physicists and neutrino astronomers, based on a presentation at the Neutrino 2010 conference in Athens, Greece. I focus in particular on results from Fermi (which was launched soon after Neutrino 2008), and conclude with a description of the next generation of instruments, namely HAWC and the Cherenkov Telescope Array.

  10. Astrophysical applications of Delbrück scattering: Dust scattered gamma radiation from gamma ray bursts

    International Nuclear Information System (INIS)

    Kunwar, B.; Bhadra, A.; Gupta, S.K. Sen

    2014-01-01

    A preliminary, and perhaps the first, study of astrophysical applications of Delbrück scattering in a gamma-ray emitting celestial object like a gamma-ray burst (GRB) has been made. At energies≥100 MeV the elastic scattering of gamma-ray photons off the molecular dust surrounding the GRB site is dominated by Delbrück scattering. Expressions for Delbrück-scattered gamma-ray flux as a function of time has been obtained for a few selected energies by assuming a simple model of GRB. These are compared with Compton-scattered flux. At certain situations, interestingly, the former is found to exceed the latter for the first few milliseconds of the burst. The issue of detectability of Delbrück-scattered gamma-ray echo from the cloud of a GRB is discussed. Although it is observed that the detection of such an echo is not within the capability of the presently operating gamma-ray missions such as Fermi LAT, a rough estimate shows that one can be optimistic that future generation gamma-ray telescopes might be able to see such photons' contribution to the total flux. - Highlights: ► Astrophysical application of Delbrück scattering in a GRB has been made. ► Initially, the Delbrück scattering may dominate the scattering of GeV γ-rays. ► The issue of detectability of such radiations is discussed

  11. Gamma-ray transients and related astrophysical phenomena

    International Nuclear Information System (INIS)

    Lingenfelter, R.E.; Hudson, H.S.; Worrall, D.M.

    1982-01-01

    The workshop covered the study of the explosive phenomena responsible for the various gamma ray transients. X-ray burster observations and theories were also reviewed with emphasis on their relationship to gamma ray bursts. Recent observational data, particularly from the SMM, HEAO, and VENERA satellites made the workshop especially timely. Major headings include: gamma-ray transients, x-ray bursts, solar transients, and instrumental concepts. Individual items from the workshop were prepared separately for the data base

  12. Computational Astrophysics Consortium 3 - Supernovae, Gamma-Ray Bursts and Nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Woosley, Stan [Univ. of California, Santa Cruz, CA (United States)

    2014-08-29

    Final project report for UCSC's participation in the Computational Astrophysics Consortium - Supernovae, Gamma-Ray Bursts and Nucleosynthesis. As an appendix, the report of the entire Consortium is also appended.

  13. Cosmic ray and gamma astrophysics with the AMS-02 experiment

    International Nuclear Information System (INIS)

    Natale, Sonia

    2006-01-01

    The Alpha Magnetic Spectrometer (AMS) is a particle physics detector designed to operate on the International Space Station (ISS) for a minimum period of three years. The aim of AMS is the direct detection of charged particles in the rigidity range from 0.5 GV to few TV to perform high statistics studies of cosmic rays in space and a search for antimatter and dark matter. AMS will provide precise gamma measurements in the GeV range. In addition, the good angular resolution and identification capabilities of the detector will allow clean studies of galactic and extra-galactic sources, the diffuse gamma background and gamma ray bursts

  14. 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

    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 acc...

  15. Topics in Astrophysical X-Ray and Gamma Ray Spectroscopy. Ph.D. Thesis - Maryland Univ.

    Science.gov (United States)

    Bussard, R. W.

    1978-01-01

    A number of topics relating to astrophysical observations that have already been made or are currently planned of spectral features, mostly emission lines, in the X-ray and gamma ray region of the electromagnetic spectrum are investigated. These topics include: the production of characteristic X-ray and gamma ray lines by nonthermal ions, spectral features induced by processes occurring in strong magnetic fields, and the positron annihilation line at 0.5 MeV. The rate of X-ray production at 6.8 keV by the 2p to 1s transition in fast hydrogen- and helium-like iron ions, following both electron capture to excited levels and collisional excitation is calculated. The cross section for electron-ion Coulomb collisions in strong fields is also calculated.

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

    Science.gov (United States)

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

    1990-01-01

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

  17. The Advanced Gamma-ray Imaging System (AGIS): Galactic Astrophysics

    Science.gov (United States)

    Digel, Seth William; Funk, S.; Kaaret, P. E.; Tajima, H.; AGIS Collaboration

    2010-03-01

    The Advanced Gamma-ray Imaging System (AGIS), a concept for a next-generation atmospheric Cherenkov telescope array, would provide unprecedented sensitivity and resolution in the energy range >50 GeV, allowing great advances in the understanding of the populations and physics of sources of high-energy gamma rays in the Milky Way. Extrapolation based on the known source classes and the performance parameters for AGIS indicates that a survey of the Galactic plane with AGIS will reveal hundreds of TeV sources in exquisite detail, for population studies of a variety of source classes, and detailed studies of individual sources. AGIS will be able to study propagation effects on the cosmic rays produced by Galactic sources by detecting the diffuse glow from their interactions in dense interstellar gas. AGIS will complement and extend results now being obtained in the GeV range with the Fermi mission, by providing superior angular resolution and sensitivity to variability on short time scales, and of course by probing energies that Fermi cannot reach.

  18. Multi-TeV gamma ray and cosmic ray astrophysics with TAIGA

    Energy Technology Data Exchange (ETDEWEB)

    Tluczykont, Martin [Hamburg Univ. (Germany). Institut fuer Experimentalphysik; Collaboration: TAIGA Kollaboration

    2016-07-01

    The very high energy gamma-ray regime is the key to several questions in high energy astrophysics, the most prominent being the search for the origin of cosmic rays. Observations of gamma rays up to several 100 TeV are particularly important to spectrally resolve the cutoff regime of the long-sought Pevatrons, the accelerators of PeV cosmic rays. TAIGA is an international collaboration that has, in the past 3 years, installed the air Cherenkov timing array HiSCORE on an area of 0.25 square-km, and are currently installing a first 4m diameter imaging air Cherenkov telescope (IACT), to be operated in parallel with the timing array. Our aim is to combine the timing and imaging techniques on a large scale in order to optimize the air Cherenkov detection technique for energies above 10 TeV and up to several 100 TeV. Simulations show a clear potential of the planned hybrid event reconstruction, especially in the energy regime from 10 TeV to 100 TeV. The TAIGA experiment will be complemented by scintillator based particle detectors for a measurement of the muon content of the air shower at higher energies. The status of our experiment and the planned 1 square-km stage of TAIGA are discussed.

  19. The INTErnational Gamma Ray Astrophysics Laboratory: INTEGRAL Highlights

    Energy Technology Data Exchange (ETDEWEB)

    Ubertini, Pietro, E-mail: pietro.ubertini@iaps.inaf.it; Bazzano, Angela

    2014-04-01

    The INTEGRAL Space Observatory was selected as the second Medium size mission (M2) of the ESAs Horizon 2000 vision programme. INTEGRAL is the first high angular and spectral resolution hard X-ray and soft γ-ray observatory with a wide band spectral response ranging from 3 keV up to 10 MeV energy band. This capability is supplemented by an unprecedented sensitivity enhanced by the 3 days orbit allowing long and uninterrupted observations over very wide field of view (up to ∼1000 squared degrees to zero response) and sub-ms time resolution. Part of the observatory success is due to its capability to link the high energy sky with the lower energy band. The complementarity and synergy with pointing soft X-ray missions such as XMM-Newton and CHANDRA and more recently with NuSTAR is a strategic feature to link the “thermal” and the “non-thermal” Universe observed at higher energies by space missions such as Fermi and AGILE and ground based TeV observatories sensitive to extremely high energies. INTEGRAL was launched on 17 October 2002 from the Baikonur Cosmodrome (Kazakistan) aboard a Proton rocket as part of the Russian contribution to the mission, and has successfully spent almost 11 years in orbit. In view of its successful science outcome the ESA Space Programme Committee haw recently approved its scientific operation till the end of 2016. To date the spacecraft, ground segment and scientific payload are in excellent state-of-health, and INTEGRAL is continuing its scientific operations, originally planned for a 5-year technical design and scientific nominal operation plan. This paper summarizes the current INTEGRAL scientific achievements and future prospects, with particular regard to the high energy domain.

  20. Hard X-ray/soft gamma-ray telescope designs for future astrophysics missions

    DEFF Research Database (Denmark)

    Ferreira, Desiree Della Monica; Christensen, Finn Erland; Pivovaroff, Michael J.

    2013-01-01

    We present several concept designs of hard X-ray/soft λ-ray focusing telescopes for future astrophysics missions. The designs are based on depth graded multilayer coatings. These have been successfully employed on the NuSTAR mission for energies up to 80 keV. Recent advances in demonstrating...

  1. Very high energy gamma ray astrophysics: Progress report, May 1, 1987-February 1, 1988

    International Nuclear Information System (INIS)

    Lamb, R.G.; Lewis, D.A.

    1988-02-01

    The Whipple observatory Gamma Ray Collaboration has continued to make steady progress in its development of a highly sensitive stereoscopic imaging gamma-ray telescope (known as the HERCULES project). The milestones in this year's development include: the demonstration of the success of the imaging concept with a single camera by the detection of a very weak flux of gamma rays from the Crab Nebula at a high level of statistical significance (7 sigma), the confirmation of our detection of an anomalous pulsed flux from Hercules X-1 in the summer of 1986 by two other groups; this result has serious implications for the mechanism for gamma-ray emission in this binary source. The construction and installation of the new high resolution camera on the 10 m reflector; the realistic simulation of the sensitivity of this camera as well as that of the full HERCULES system was also undertaken. These, and other highlights of this year's program at the Iowa State University and the Smithsonian Astrophysical Observatory, are discussed in this paper. 6 figs

  2. Developing a Laue Lens for Nuclear Astrophysics: The Challenge of Focusing Soft Gamma-rays

    Science.gov (United States)

    Barriere, Nicolas

    Soft gamma rays provide a unique window on the high-energy Universe, especially for studying nuclear astrophysics through nuclear line emission. However, the sensitivity of state-of-the-art gamma-ray telescopes is severely limited by the intense instrumental background when flown in space. A solution is to decouple the photon collection area from the photon detection area. Focusing source photons from a large collection area onto a small detector volume would dramatically improve the signal-to-noise ratio, and hence provide the long awaited sensitivity leap in this challenging energy band. Laue crystal diffraction can be utilized to focus soft gamma rays when configured in a Laue lens. While this technology has been demonstrated on balloon flights, the type of crystals used and the process of assembling many crystals into a lens have not been optimized yet. We propose to address all the technical aspects of the construction of a scientifically exploitable Laue lens in order to bring this technology to TRL-6. To this end, two small prototypes representative of the diversity of Laue lenses will be built and tested in relevant environments, leveraging the work accomplished under a previous APRA grant. This project will establish the real performances, the cost, and the construction duration of a full-scale lens, allowing us to propose a Laue lens telescope for suborbital or satellite missions.

  3. Laue optics for nuclear astrophysics: New detector requirements for focused gamma-ray beams

    Energy Technology Data Exchange (ETDEWEB)

    Barriere, N. [INAF - IASF Roma, via Fosso del Cavaliere 100, 00133 Roma (Italy)], E-mail: nicolas.barriere@iasf-roma.inaf.it; Ballmoos, P. von [CESR - UMR 5187, 9 Av. du Colonel Roche, 31028 Toulouse (France); Abrosimov, N.V. [IKZ, Max Born-Str. 2, D-12489 Berlin (Germany); Bastie, P. [LSP UMR 5588, 140 Av. de la physique, 38402 Saint Martin d' Heres (France); Camus, T. [CESR - UMR 5187, 9 Av. du Colonel Roche, 31028 Toulouse (France); Courtois, P.; Jentschel, M. [ILL, 6 rue Jules Horowitz, 38042 Grenoble (France); Knoedlseder, J. [CESR - UMR 5187, 9 Av. du Colonel Roche, 31028 Toulouse (France); Natalucci, L. [INAF - IASF Roma, via Fosso del Cavaliere 100, 00133 Roma (Italy); Roudil, G.; Rousselle, J. [CESR - UMR 5187, 9 Av. du Colonel Roche, 31028 Toulouse (France); Wunderer, C.B. [SSL, University of California at Berkeley, CA 94708 (United States); Kurlov, V.N. [Institute of Solid State Physics of Russian Academy of Sciences, 142432 Chernogolovka (Russian Federation)

    2009-10-21

    Nuclear astrophysics presents an extraordinary scientific potential for the study of the most powerful sources and the most violent events in the Universe. But in order to take full advantage of this potential, telescopes should be at least an order of magnitude more sensitive than present technologies. Today, Laue lenses have demonstrated their capability of focusing gamma-rays in the 100 keV-1 MeV domain, enabling the possibility of building a new generation of instruments for which sensitive area is decoupled from collecting area. Thus we have now the opportunity of dramatically increase the signal/background ratio and hence improve significantly the sensitivity. With a lens, the best detector is no longer the largest possible within a mission envelope. The point spread function of a Laue lens measures a few centimeters in diameter, but the field of view is limited by the detector size. Requirements for a focal plane instrument are presented in the context of the Gamma-Ray Imager mission (proposed to European Space Agency, ESA in the framework of the first Cosmic Vision AO): a 15-20 cm a side finely pixellated detector capable of Compton events reconstruction seems to be optimal, giving polarization and background rejection capabilities and 30 arcsec of angular resolution within a field of view of 5 arc min.

  4. Topics in High-Energy Astrophysics: X-ray Time Lags and Gamma-ray Flares

    Science.gov (United States)

    Kroon, John J.

    2016-03-01

    The Universe is host to a wide variety of high-energy processes that convert gravitational potential energy or rest-mass energy into non-thermal radiation such as bremsstrahlung and synchrotron. Prevailing models of X-ray emission from accreting Black Hole Binaries (BHBs) struggle to simultaneously fit the quiescent X-ray spectrum and the transients which result in the phenomenon known as X-ray time lags. And similarly, classical models of diffusive shock acceleration in pulsar wind nebulae fail to explain the extreme particle acceleration in very short timescales as is inferred from recent gamma-ray flares from the Crab nebula. In this dissertation, I develop new exact analytic models to shed light on these intriguing processes. I take a fresh look at the formation of X-ray time lags in compact sources using a new mathematical approach in which I obtain the exact Green's function solution. The resulting Green's function allows one to explore a variety of injection scenarios, including both monochromatic and broadband (bremsstrahlung) seed photon injection. I obtain the exact solution for the dependence of the time lags on the Fourier frequency, for both homogeneous and inhomogeneous clouds. The model can successfully reproduce both the observed time lags and the quiescent X-ray spectrum using a single set of coronal parameters. I show that the implied coronal radii in the new model are significantly smaller than those obtained in the Monte Carlo simulations, hence greatly reducing the coronal heating problem. Recent bright gamma-ray flares from the Crab nebula observed by AGILE and Fermi reaching GeV energies and lasting several days challenge the contemporary model for particle acceleration in pulsar wind nebulae, specifically the diffusive shock acceleration model. Simulations indicate electron/positron pairs in the Crab nebula pulsar wind must be accelerated up to PeV energies in the presence of ambient magnetic fields with strength B ~100 microG. No

  5. The future of high energy gamma ray astronomy and its potential astrophysical implications

    Science.gov (United States)

    Fichtel, C. E.

    1982-01-01

    Future satellites should carry instruments having over an order of magnitude greater sensitivity than those flown thus far as well as improved energy and angular resolution. The information to be obtained from these experiments should greatly enhance knowledge of: the very energetic and nuclear processes associated with compact objects; the structure of our galaxy; the origin and dynamic pressure effects of the cosmic rays; the high energy particles and energetic processes in other galaxies; and the degree of matter-antimatter symmetry of the universe. The relevant aspects of extragalactic gamma ray phenomena are emphasized along with the instruments planned. The high energy gamma ray results of forthcoming programs such as GAMMA-1 and the Gamma Ray Observatory should justify even more sophisticated telescopes. These advanced instruments might be placed on the space station currently being considered by NASA.

  6. Status of the GILDA project for the 30 MeV-100 GeV high energy gamma ray astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Casolino, M.; Sparvoli, R.; Morselli, A.; Picozza, P. [Rome Univ. `Tor Vergata` (Italy)]|[INFN, Rome (Italy); Barbiellini, G. [Trieste Univ. (Italy)]|[INFN, Trieste (Italy); Fuglesang, C. [ESA-EAC, Cologne (Germany); Ozerov, Yu.V.; Zemskov, V.M.; Zverev, V.G.; Galper, A.M. [Moscow Engineering Physics Institute, Moscow (Russian Federation)

    1995-09-01

    High energy gamma-ray astrophysics has greatly developed in the last few years because of the results of EGRET, on the Compton gamma ray observatory. The satellite observations have shown the importance of continuing the investigation of high energy gamma radiation but the emerging of new astrophysical and cosmological problems require for future experiments the realization of telescopes with parameters significatively improved with respect to the previous missions. In a traditional point of view, this is achieved with the increase of the length L of the device and, consequently, the mass of the telescope and satellite (growing as L{sup 3}). Such kinds of experiments are becoming rather expensive and are approaching the maximum value in cost, satellite mass and consuming resources. The telescope project GILDA presented in this paper is based on the use of silicon strip detectors. The silicon technique consents to obtain a much wider solid angle aperture; in this way there is more sensitivity without a growing in the size of the

  7. Status of the GILDA project for the 30 MeV-100 GeV high energy gamma ray astrophysics

    International Nuclear Information System (INIS)

    Casolino, M.; Sparvoli, R.; Morselli, A.; Picozza, P.; Barbiellini, G.; Fuglesang, C.; Ozerov, Yu.V.; Zemskov, V.M.; Zverev, V.G.; Galper, A.M.

    1995-01-01

    High energy gamma-ray astrophysics has greatly developed in the last few years because of the results of EGRET, on the Compton gamma ray observatory. The satellite observations have shown the importance of continuing the investigation of high energy gamma radiation but the emerging of new astrophysical and cosmological problems require for future experiments the realization of telescopes with parameters significatively improved with respect to the previous missions. In a traditional point of view, this is achieved with the increase of the length L of the device and, consequently, the mass of the telescope and satellite (growing as L 3 ). Such kinds of experiments are becoming rather expensive and are approaching the maximum value in cost, satellite mass and consuming resources. The telescope project GILDA presented in this paper is based on the use of silicon strip detectors. The silicon technique consents to obtain a much wider solid angle aperture; in this way there is more sensitivity without a growing in the size of the

  8. Astrophysical interpretation of the anisotropies in the unresolved gamma-ray background

    Science.gov (United States)

    Ando, Shin'ichiro; Fornasa, Mattia; Fornengo, Nicolao; Regis, Marco; Zechlin, Hannes-S.

    2017-06-01

    Recently, a new measurement of the auto- and cross-correlation angular power spectrum (APS) of the isotropic gamma-ray background was performed, based on 81 months of data of the Fermi Large-Area Telescope (LAT). Here, we fit, for the first time, the new APS data with a model describing the emission of unresolved blazars. These sources are expected to dominate the anisotropy signal. The model we employ in our analysis reproduces well the blazars resolved by Fermi LAT. When considering the APS obtained by masking the sources listed in the 3FGL catalog, we find that unresolved blazars underproduce the measured APS below ˜1 GeV . Contrary to past results, this suggests the presence of a new contribution to the low-energy APS, with a significance of, at least, 5 σ . The excess can be ascribed to a new class of faint gamma-ray emitters. If we consider the APS obtained by masking the sources in the 2FGL catalog, there is no underproduction of the APS below 1 GeV, but the new source class is still preferred over the blazars-only scenario (with a significance larger than 10 σ ). The properties of the new source class and the level of anisotropies induced in the isotropic gamma-ray background are the same, independent of the APS data used. In particular, the new gamma-ray emitters must have a soft energy spectrum, with a spectral index ranging, approximately, from 2.7 to 3.2. This complicates their interpretation in terms of known sources, since, normally, star-forming and radio galaxies are observed with a harder spectrum. The new source class identified here is also expected to contribute significantly to the intensity of the isotropic gamma-ray background.

  9. Very high energy gamma ray astrophysics. Progress report, August 1, 1980-July 31, 1981

    International Nuclear Information System (INIS)

    Lamb, R.C.

    1981-04-01

    Very high energy (VHE) gamma ray astronomy gives insight into fundamental questions regarding the origins of cosmic rays and the types of particle acceleration mechanisms which operate in nature. VHE photons are detected by means of the Cerenkov light their secondaries produce in the atmosphere. During June - September 1981 the solar collectors at Edwards Air Force Base will be used to detect the Cerenkov light from the photons from Cygnus X-3 thus extending its observation into a previously unexplored region. The time of each detector event will be recorded to the nearest 0.5 ms. If Cygnus X-3 is the neutron star remnant of a recent (unseen) supernova, then the VHE gamma rays may be pulsed at its rotation rate, and the data obtained will allow a sensitive test of this possibility. The equipment for the summer observations is nearly ready and will be tested in May prior to any early run in June

  10. Design and expected performance of a novel hybrid detector for very-high-energy gamma-ray astrophysics

    Science.gov (United States)

    Assis, P.; Barres de Almeida, U.; Blanco, A.; Conceição, R.; D'Ettorre Piazzoli, B.; De Angelis, A.; Doro, M.; Fonte, P.; Lopes, L.; Matthiae, G.; Pimenta, M.; Shellard, R.; Tomé, B.

    2018-05-01

    Current detectors for Very-High-Energy γ-ray astrophysics are either pointing instruments with a small field of view (Cherenkov telescopes), or large field-of-view instruments with relatively large energy thresholds (extensive air shower detectors). In this article, we propose a new hybrid extensive air shower detector sensitive in an energy region starting from about 100 GeV. The detector combines a small water-Cherenkov detector, able to provide a calorimetric measurement of shower particles at ground, with resistive plate chambers which contribute significantly to the accurate shower geometry reconstruction. A full simulation of this detector concept shows that it is able to reach better sensitivity than any previous gamma-ray wide field-of-view experiment in the sub-TeV energy region. It is expected to detect with a 5σ significance a source fainter than the Crab Nebula in one year at 100 GeV and, above 1 TeV a source as faint as 10% of it. As such, this instrument is suited to detect transient phenomena making it a very powerful tool to trigger observations of variable sources and to detect transients coupled to gravitational waves and gamma-ray bursts.

  11. Gamma-Ray Bursts

    Science.gov (United States)

    Pellizza, L. J.

    Gamma-ray bursts are the brightest transient sources in the gamma-ray sky. Since their discovery in the late 1960s, the investigation of the astrophysical sys- tems in which these phenomena take place, and the physical mechanisms that drive them, has become a vast and prolific area of modern astrophysics. In this work I will briefly describe the most relevant observations of these sources, and the models that describe their nature, emphasizing on the in- vestigations about the progenitor astrophysical systems. FULL TEXT IN SPANISH

  12. Studying explosive phenomena in astrophysics by the example of gamma-ray bursts and supernovae

    International Nuclear Information System (INIS)

    Filina, Anastasia

    2015-01-01

    The formation of the first stars hundreds of millions of years after the Big-Bang marks the end of the Dark Ages. Currently, we have no direct observations on how the primordial stars formed, but according to modern theory of stellar evolution these stars should be very massive (about 100 Msun) Population III stars have a potential to produce probably most energetic flashes in the Universe - gamma-ray bursts. GRBs may provide one of the most promising methods to probe directly final stage of life of primordial stars. Today's telescopes cannot look far enough into the cosmic past to observe the formation of the first stars, but the new generation of telescopes will test theoretical ideas about the formation of the first stars.Thanks to many years of observations we have good GRB's data -statistics of occurrence, spectrum, light curves. But there are still a lot of questions in the theory of GRBs. We know that GRBs are related to the death of stars and that they are connected with supernovae. So gamma-ray bursts are one of the classes of explosive processes in stellar physics that should have a lot of common with supernovae explosions. In that case GRBs should follow the same physical laws of explosion as supernovae. This work tries to approach the problem of GRBs as a problem of stellar explosion.Necessary instruments of studying stellar explosion were developed as a part of doctoral research: code for solving systems of nuclear reaction equations was incorporated into hydrodynamical code. These tools were applied for supernovae simulations in order to find possible connection with GRBs. Basing on analysis of supernovae simulations spectral analysis of GRBs was performed. (author)

  13. Statistical gamma-ray emission of gold and its astrophysical implications

    Directory of Open Access Journals (Sweden)

    Giacoppo F.

    2014-03-01

    Full Text Available The properties of the excited states of gold isotopes were investigated at the Oslo Cyclotron Laboratory. This study is important for the understanding of neutron capture rates in astrophysical plasmas relevant for heavy element nucleosynthesys.

  14. FAST TIMING ANALYSIS OF CYGNUS X-1 USING THE SPECTROMETER ON THE INTERNATIONAL GAMMA-RAY ASTROPHYSICS LABORATORY

    International Nuclear Information System (INIS)

    Cabanac, Clement; Roques, Jean-Pierre; Jourdain, Elisabeth

    2011-01-01

    We report for the first time the high-frequency analysis of Cyg X-1 up to hard X-ray using the spectrometer on International Gamma-Ray Astrophysics Laboratory (INTEGRAL). After analyzing the possible contribution from the background, and using the INTEGRAL archive from 2005 March to 2008 May, power density spectra were obtained up to 130 keV. First, we show that their overall shape is very similar to that observed at lower energies as they are well described by sets of Lorentzians. The strength of this fast variability (up to 40 Hz) does not drop at high energy since we show that it remains at ∼25% rms, even in the highest energy bands. Second, the hard X-ray variability patterns of Cyg X-1 are state dependent: the softer the spectrum (or the lower the hardness ratio), the lower the total fractional variability and the higher the typical frequencies observed. The strength of the total variability as a function of energy and state is then investigated. By comparison with simultaneous and published RXTE/Proportional Counter Array data, we show that in the hard state it remains quite constant in the 2-130 keV energy range. In the softer state it is also flat up to 50 keV and may increase at higher energy. The implications of this behavior on the models are then discussed.

  15. ASTROPHYSICAL PARAMETERS OF LS 2883 AND IMPLICATIONS FOR THE PSR B1259-63 GAMMA-RAY BINARY

    International Nuclear Information System (INIS)

    Negueruela, Ignacio; Lorenzo, Javier; Ribo, Marc; Herrero, Artemio; Khangulyan, Dmitry; Aharonian, Felix A.

    2011-01-01

    Only a few binary systems with compact objects display TeV emission. The physical properties of the companion stars represent basic input for understanding the physical mechanisms behind the particle acceleration, emission, and absorption processes in these so-called gamma-ray binaries. Here we present high-resolution and high signal-to-noise optical spectra of LS 2883, the Be star forming a gamma-ray binary with the young non-accreting pulsar PSR B1259-63, showing it to rotate faster and be significantly earlier and more luminous than previously thought. Analysis of the interstellar lines suggests that the system is located at the same distance as (and thus is likely a member of) Cen OB1. Taking the distance to the association, d = 2.3 kpc, and a color excess of E(B - V) = 0.85 for LS 2883 results in M V ∼ -4.4. Because of fast rotation, LS 2883 is oblate (R eq ≅ 9.7 R sun and R pole ≅ 8.1 R sun ) and presents a temperature gradient (T eq ∼ 27,500 K, log g eq = 3.7; T pole ∼ 34,000 K, log g pole = 4.1). If the star did not rotate, it would have parameters corresponding to a late O-type star. We estimate its luminosity at log(L * /L sun ) ≅ 4.79 and its mass at M * ∼ 30 M sun . The mass function then implies an inclination of the binary system i orb ∼ 23 0 , slightly smaller than previous estimates. We discuss the implications of these new astrophysical parameters of LS 2883 for the production of high-energy and very high-energy gamma rays in the PSR B1259-63/LS 2883 gamma-ray binary system. In particular, the stellar properties are very important for prediction of the line-like bulk Comptonization component from the unshocked ultrarelativistic pulsar wind.

  16. The History of Ground-Based Very High Energy Gamma-Ray Astrophysics with the Atmospheric Air Cherenkov Telescope Technique

    Energy Technology Data Exchange (ETDEWEB)

    Mirzoyan, Razmik

    2013-06-15

    In the recent two decades the ground-based technique of imaging atmosphericescopes has established itself as a powerful new discipline in science. As of today some ∼ 150 sources of gamma rays of very different types, of both galactic and extragalactic origin, have been discovered due to this technique. The study of these sources is providing clues to many basic questions in astrophysics, astro-particle physics, physics of cosmic rays and cosmology. The current generation of telescopes, despite the young age of the technique, offers a solid performance. The technique is still maturing, leading to the next generation large instrument known under the name Cherenkov Telescope Array. The latter's sensitivity will be an order of magnitude higher than that of the currently best instruments VERITAS, H.E.S.S. and MAGIC. This article is devoted to outlining the milestones in a long history that step-by-step have given shape to this technique and have brought about today's successful source marathon.

  17. Very high energy gamma ray astrophysics: Progress report for period May 1, 1986-February 15, 1987

    International Nuclear Information System (INIS)

    Lamb, R.C.; Lewis, D.A.

    1987-02-01

    Highlights of research are noted. These include new electronics, noise and gain analysis, tests of imaging, new sources of gamma radiation observed, development of a 37-element mini camera, computer capabilities, and new detector capabilities

  18. A search for gamma-ray imprints of annihilating dark matter in the galaxy, and the astrophysical implications of ultra-light fundamental vector bosons

    International Nuclear Information System (INIS)

    Zechlin, Hannes-Sebastian

    2013-12-01

    Standard Model extensions imply new elementary particles that can lead to specific astrophysical signatures. In particular, weakly interacting massive particles (WIMPs) can constitute the unknown non-luminous cold dark matter, which contributes approximately 84% to the matter content of the Universe. Annihilation or decay of WIMPs may lead to high-energy gamma-rays. In this thesis, new methods of searching for gamma-ray signals from annihilating dark matter are developed and applied. Moreover, astrophysical imprints of new ultra-light hidden U(1) gauge bosons in radio data are investigated. Hierarchical structure formation predicts a variety of smaller bound dark matter sub-halos in Milky-Way-like galactic hosts. It is shown that the Fermi-LAT is sufficiently sensitive for detecting up to a few nearby dark matter subhalos in terms of faint gamma-ray sources with a moderate angular extent. Searches in the first and second Fermi-LAT source catalogs reveal about ten candidate sources each. To discriminate the source candidates from conventional astrophysical objects, an analysis for spectral, spatial, positional, and temporal gamma-ray properties using 3.5 years of Fermi-LAT data is carried out. In addition, a multi-wavelength analysis of archival data or follow-up observations in the radio, infrared, optical, UV, X-ray, high-energy, and very-high energy gamma-ray bands is carried out. The broad-band spectra of all promising candidates are compatible with AGN, in particular high-energy peaked BL-Lac type objects (HBLs). Dark matter annihilation can contribute to the small-scale angular anisotropy spectrum of the diffuse gamma-ray background (DGB). The detection capabilities of currently operating imaging atmospheric Cherenkov telescopes and the planned Cherenkov Telescope Array (CTA) are studied. With CTA, a relative gamma-ray contribution from annihilating dark matter of 10% to the extragalactic DGB can be resolved via angular anisotropies. In terms of the dark

  19. Investigations in γ-Ray Astrophysics and Astroparticle Physics

    Energy Technology Data Exchange (ETDEWEB)

    Krennrich, Frank [Iowa State Univ., Ames, IA (United States). Dept. of Physics and Astronomy

    2016-06-28

    This report describes the status of data analysis efforts, results and publications of research grant DE-SC0009917. The research is focused on TeV gamma-ray studies of astrophysical sources and related particle physics questions.

  20. Gamma-ray bursts

    CERN Document Server

    Wijers, Ralph A M J; Woosley, Stan

    2012-01-01

    Cosmic gamma ray bursts (GRBs) have fascinated scientists and the public alike since their discovery in the late 1960s. Their story is told here by some of the scientists who participated in their discovery and, after many decades of false starts, solved the problem of their origin. Fourteen chapters by active researchers in the field present a detailed history of the discovery, a comprehensive theoretical description of GRB central engine and emission models, a discussion of GRB host galaxies and a guide to how GRBs can be used as cosmological tools. Observations are grouped into three sets from the satellites CGRO, BeppoSAX and Swift, and followed by a discussion of multi-wavelength observations. This is the first edited volume on GRB astrophysics that presents a fully comprehensive review of the subject. Utilizing the latest research, Gamma-ray Bursts is an essential desktop companion for graduate students and researchers in astrophysics.

  1. A search for gamma-ray imprints of annihilating dark matter in the galaxy, and the astrophysical implications of ultra-light fundamental vector bosons

    Energy Technology Data Exchange (ETDEWEB)

    Zechlin, Hannes-Sebastian

    2013-12-15

    Standard Model extensions imply new elementary particles that can lead to specific astrophysical signatures. In particular, weakly interacting massive particles (WIMPs) can constitute the unknown non-luminous cold dark matter, which contributes approximately 84% to the matter content of the Universe. Annihilation or decay of WIMPs may lead to high-energy gamma-rays. In this thesis, new methods of searching for gamma-ray signals from annihilating dark matter are developed and applied. Moreover, astrophysical imprints of new ultra-light hidden U(1) gauge bosons in radio data are investigated. Hierarchical structure formation predicts a variety of smaller bound dark matter sub-halos in Milky-Way-like galactic hosts. It is shown that the Fermi-LAT is sufficiently sensitive for detecting up to a few nearby dark matter subhalos in terms of faint gamma-ray sources with a moderate angular extent. Searches in the first and second Fermi-LAT source catalogs reveal about ten candidate sources each. To discriminate the source candidates from conventional astrophysical objects, an analysis for spectral, spatial, positional, and temporal gamma-ray properties using 3.5 years of Fermi-LAT data is carried out. In addition, a multi-wavelength analysis of archival data or follow-up observations in the radio, infrared, optical, UV, X-ray, high-energy, and very-high energy gamma-ray bands is carried out. The broad-band spectra of all promising candidates are compatible with AGN, in particular high-energy peaked BL-Lac type objects (HBLs). Dark matter annihilation can contribute to the small-scale angular anisotropy spectrum of the diffuse gamma-ray background (DGB). The detection capabilities of currently operating imaging atmospheric Cherenkov telescopes and the planned Cherenkov Telescope Array (CTA) are studied. With CTA, a relative gamma-ray contribution from annihilating dark matter of 10% to the extragalactic DGB can be resolved via angular anisotropies. In terms of the dark

  2. The digital ASIC for the digital front end electronics of the SPI astrophysics gamma-ray experiment

    International Nuclear Information System (INIS)

    Lafond, E.; Mur, M.; Schanne, S.

    1998-01-01

    The SPI spectrometer is one of the gamma-ray astronomy instruments that will be installed on the ESA INTEGRAL satellite, intended to be launched in 2001 by the European Space Agency. The Digital Front-End Electronics sub-system (DFEE) is in charge of the real time data processing of the various measurements produced by the Germanium (Ge) detectors and the Bismuth Germanate (BGO) anti-coincidence shield. The central processing unit of the DFEE is implemented in a digital ASIC circuit, which provides the real time association of the various time signals, acquires the associated energy measurements, and classifies the various types of physics events. The paper gives the system constraints of the DFEE, the architecture of the ASIC circuit, the technology requirements, and the strategy for test and integration. Emphasis is given to the high level language development and simulation, the automatic circuit synthesis approach, and the performance estimation

  3. VI School on Cosmic Rays and Astrophysics

    International Nuclear Information System (INIS)

    2017-01-01

    VI School on Cosmic Rays and Astrophysics 17-25 November 2015, Chiapas, Mexico The VI School on Cosmic Rays and Astrophysics was held at the MCTP, at the Autonomous University of Chiapas (UNACH), Tuxtla Gutiérrez, Chiapas, Mexico thanks to the Science for Development ICTP-UNACH-UNESCO Regional Seminar, 17-25 November 2015 (http://mctp.mx/e-VI-School-on-Cosmic-Rays-and-Astrophysics.html). The School series started in La Paz, Bolivia in 2004 and it has been, since then, hosted by several Latin American countires: 1.- La Paz, Bolivia (August, 2004), 2.- Puebla, Mexico (September, 2006), 3.- Arequipa, Peru (September, 2008), 4.- Santo André, Brazil (September, 2010), 5.- La Paz, Bolivia (August, 2012). It aims to promote Cosmic Ray (CR) Physics and Astrophysics in the Latin American community and to provide a general overview of theoretical and experimental issues on these topics. It is directed to undergraduates, postgraduates and active researchers in the field. The lectures introduce fundamental Cosmic Ray Physics and Astrophysics with a review of standards of the field. It is expected the school continues happening during the next years following a tradition. In this edition, the list of seminars included topics such as experimental techniques of CR detection, development of CR showers and hadronic interactions, composition and energy spectrum of primary CR, Gamma-Ray Bursts (GRBs), neutrino Astrophysics, spacecraft detectors, simulations, solar modulation, and the current state of development and results of several astroparticle physics experiments such as The Pierre Auger Observatory in Argentina, HAWC in Mexico, KASCADE and KASCADE Grande, HESS, IceCube, JEM-EUSO, Fermi-LAT, and others. This time the school has been complemented with the ICTP-UNACH-UNESCO Seminar of theory on Particle and Astroparticle Physics. The organization was done by MCTP, the Mesoamerican Centre for Theoretical Physics. The school had 46 participants, 30 students from Honduras, Brazil

  4. 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.

  5. Gamma ray generator

    Science.gov (United States)

    Firestone, Richard B; Reijonen, Jani

    2014-05-27

    An embodiment of a gamma ray generator includes a neutron generator and a moderator. The moderator is coupled to the neutron generator. The moderator includes a neutron capture material. In operation, the neutron generator produces neutrons and the neutron capture material captures at least some of the neutrons to produces gamma rays. An application of the gamma ray generator is as a source of gamma rays for calibration of gamma ray detectors.

  6. 14th International School of Cosmic Ray Astrophysics

    CERN Document Server

    Stanev, Todor; Wefel, John P; Neutrinos and explosive events in the universe

    2005-01-01

    This volume contains the Lectures and selected participant contributions to the 14th Course of the International School of Cosmic Rays Astrophysics, a NATO Advanced Study Institute. Well known astrophysicists and astronomers discuss different aspects of the generation of high energy signals in powerful astrophysical objects concentrating on the production of neutrinos and gamma rays from high energy particle interactions. Recent results from new experiments and observatories are presented. Topics cover a wide range including the Spitzer infrared observatory, TeV gamma ray observations, dark matter, and neutrino telescopes. The combination of basic knowledge about the production of high energy signals with information about the data analysis of ongoing observations places the book between the usual levels of a textbook and a conference proceedings. It will give the reader a good introduction to the current field of astroparticle physics, and some of the fascinating astrophysics being addressed.

  7. Future prospects for. gamma. -ray astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Fichtel, C [National Aeronautics and Space Administration, Greenbelt, MD (USA). Goddard Space Flight Center

    1981-06-30

    As ..gamma..-ray astronomy moves from the discovery to the exploratory phase, the promise of ..gamma..-ray astrophysics noted by theorists in the late 1940s and 1950s is beginning to be realized. In the future, satellites should carry instruments that will have over an order of magnitude greater sensitivity than those flown thus far, and, for at least some portions of the ..gamma..-ray energy range, these detectors will also have substantially improved energy and angular resolution. The information to be obtained from these experiments should greatly enhance our knowledge of several astrophysical phenomena including the very energetic and nuclear processes associated with compact objects, astrophysical nucleosynthesis, solar particle acceleration, the chemical composition of the planets and other bodies of the Solar System, the structure of our Galaxy, the origin and dynamic pressure effects of the cosmic rays, high energy particles and energetic processes in other galaxies especially active ones, and the degree of matter-antimatter symmetry of the Universe. The ..gamma..-ray results of the forthcoming programs such as Gamma-I, the Gamma Ray Observatory, the ..gamma..-ray burst network, Solar Polar, and very high energy ..gamma..-ray telescopes on the ground will almost certainly provide justification for more sophisticated telescopes. These advanced instruments might be placed on the Space Platform currently under study by N.A.S.A.

  8. About cosmic gamma ray lines

    Science.gov (United States)

    Diehl, Roland

    2017-06-01

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

  9. Gamma ray astronomy

    International Nuclear Information System (INIS)

    Fichtel, C.E.

    1975-01-01

    The first certain detection of celestial high energy gamma rays came from a satellite experiment flown on the third Orbiting Solar Observatory (OSO-111). A Gamma ray spark chamber telescope with substantively greater sensitivity and angular resolution (a few degrees) flown on the second Small Astronomy Satellite (SAS-II) has now provided a better picture of the gamma ray sky, and particularly the galactic plane and pulsars. This paper will summarize the present picture of gamma ray astronomy as it has developed at this conference from measurements made with experiments carried out on balloons, those remaining on the ground, and ones flown on satellites. (orig.) [de

  10. Gamma-rays from decaying dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Bertone, G. [Paris-6 Univ., 75 (France). Inst. d' Astrophysique; Buchmueller, W.; Covi, L.; Ibarra, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2007-10-15

    We study the prospects for detecting gamma-rays from decaying Dark Matter (DM), focusing in particular on gravitino DM in R-parity breaking vacua. Given the substantially different angular distribution of the predicted gamma-ray signal with respect to the case of annihilating DM, and the relatively poor (of order 0.1 ) angular resolution of gamma-ray detectors, the best strategy for detection is in this case to look for an exotic contribution to the gamma-ray flux at high galactic latitudes, where the decaying DM contribution would resemble an astrophysical extragalactic component, similar to the one inferred by EGRET observations. Upcoming experiments such as GLAST and AMS-02 may identify this exotic contribution and discriminate it from astrophysical sources, or place significant constraints on the mass and lifetime of DM particles. (orig.)

  11. Particle and astrophysics aspects of ultrahigh energy cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Sigl, G [Institut d' Astrophysique de Paris, Paris (France)

    2001-11-15

    The origin of cosmic rays is one of the major unresolved astrophysical questions. In particular, the highest energy cosmic rays observed possess macroscopic energies and their origin is likely to be associated with the most energetic processes in the Universe. Their existence triggered a flurry of theoretical explanations ranging from conventional shock acceleration to particle physics beyond the Standard Model and processes taking place at the earliest moments of our Universe. Furthermore, many new experimental activities promise a strong increase of statistics at the highest energies and a combination with {gamma}-ray and neutrino astrophysics will put strong constraints on these theoretical models. Detailed Monte Carlo simulations indicate that charged ultra-high energy cosmic rays can also be used as probes of large scale magnetic fields whose origin may open another window into the very early Universe. We give an overview over this quickly evolving research field. (author)

  12. Space instrumentation for gamma-ray astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Teegarden, B.J

    1999-02-11

    The decade of the 1990s has witnessed a renaissance in the field of gamma-ray astronomy. The seminal event was the launch of the Compton Gamma-Ray Observatory (CGRO) in April 1991. There have been a flood of major discoveries from CGRO including breakthroughs in gamma-ray bursts, annihilation radiation, and blazars. The Italian SAX satellite was launched in April 1996. Although not primarily a gamma-ray mission, it has added a new dimension to our understanding of gamma-ray bursts. Along with these new discoveries a firm groundwork has been laid for missions and new technology development that should maintain a healthy and vigorous field throughout most of the next decade. These include the ESA INTEGRAL mission (INTErnational Gamma-Ray Astrophysics Laboratory, to be launched in mid-2001) and the NASA GLAST mission (Gamma-Ray Large Area Space Telescope) with a likely launch in the middle of the next decade. These two missions will extend the observational capabilities well beyond those of CGRO. New technologies (to gamma-ray astronomy), such as cooled germanium detectors, silicon strip detectors, and CdTe detectors are planned for these new missions. Additional promising new technologies such as CdZnTe strip detectors, scintillator fibers, and a gamma-ray lens for future gamma-ray astronomy missions are under development in laboratories around the world.

  13. Space instrumentation for gamma-ray astronomy

    International Nuclear Information System (INIS)

    Teegarden, B.J.

    1999-01-01

    The decade of the 1990s has witnessed a renaissance in the field of gamma-ray astronomy. The seminal event was the launch of the Compton Gamma-Ray Observatory (CGRO) in April 1991. There have been a flood of major discoveries from CGRO including breakthroughs in gamma-ray bursts, annihilation radiation, and blazars. The Italian SAX satellite was launched in April 1996. Although not primarily a gamma-ray mission, it has added a new dimension to our understanding of gamma-ray bursts. Along with these new discoveries a firm groundwork has been laid for missions and new technology development that should maintain a healthy and vigorous field throughout most of the next decade. These include the ESA INTEGRAL mission (INTErnational Gamma-Ray Astrophysics Laboratory, to be launched in mid-2001) and the NASA GLAST mission (Gamma-Ray Large Area Space Telescope) with a likely launch in the middle of the next decade. These two missions will extend the observational capabilities well beyond those of CGRO. New technologies (to gamma-ray astronomy), such as cooled germanium detectors, silicon strip detectors, and CdTe detectors are planned for these new missions. Additional promising new technologies such as CdZnTe strip detectors, scintillator fibers, and a gamma-ray lens for future gamma-ray astronomy missions are under development in laboratories around the world

  14. Gamma ray astronomy

    International Nuclear Information System (INIS)

    Broomhead, Laurent.

    1980-01-01

    The nuclear gamma astronomy is presented, in particular the Gamma Ray Observatory, an enormous eight tonnes machine fitted with gamma telescopes, scheduled for launching around 1985. It is thereby hoped to study the natural nuclear reactions which occur when stars explode [fr

  15. Monopole, astrophysics and cosmic ray observatory at Gran Sasso

    International Nuclear Information System (INIS)

    Demarzo, C.; Enriquez, O.; Giglietto, N.

    1985-01-01

    A new large area detector, MACRO was approved for installation at the Gran Sasso Laboratory in Italy. The detector will be dedicated to the study of naturally penetrating radiation deep underground. It is designed with the general philosophy of covering the largest possible area with a detector having both sufficient built-in redundancy and use of complementary techniques to study very rare phenomena. The detector capabilities will include monopole investigations significantly below the Parker bound; astrophysics studies of very high energy gamma ray and neutrino point sources; cosmic ray measurements of single and multimuons; and the general observation of rare new forms of matter in the cosmic rays

  16. Monopole, astrophysics and cosmic ray observatory at Gran Sasso

    Science.gov (United States)

    Demarzo, C.; Enriquez, O.; Giglietto, N.; Posa, F.; Attolini, M.; Baldetti, F.; Giacomelli, G.; Grianti, F.; Margiotta, A.; Serra, P.

    1985-01-01

    A new large area detector, MACRO was approved for installation at the Gran Sasso Laboratory in Italy. The detector will be dedicated to the study of naturally penetrating radiation deep underground. It is designed with the general philosophy of covering the largest possible area with a detector having both sufficient built-in redundancy and use of complementary techniques to study very rare phenomena. The detector capabilities will include monopole investigations significantly below the Parker bound; astrophysics studies of very high energy gamma ray and neutrino point sources; cosmic ray measurements of single and multimuons; and the general observation of rare new forms of matter in the cosmic rays.

  17. Gamma-ray sources

    International Nuclear Information System (INIS)

    Hermsen, W.

    1980-01-01

    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.)

  18. Gamma ray astronomy

    International Nuclear Information System (INIS)

    Hillier, R.

    1984-01-01

    The book reviews the development of gamma ray astronomy over the past twenty five years. A large section of the book is devoted to the problems of background radiation and the design of detectors. Gamma rays from the sun, the galactic disc, the galaxy, and extra galactic sources; are also discussed. (U.K.)

  19. Results of search for the point superhigh-energy gamma ray sources carried out in the Crimean Astrophysical Observatory in the years 1969-1973

    International Nuclear Information System (INIS)

    Stepanyan, A.A.; Vladimirskij, B.M.; Neshpor, Yu.I.; Fomin, V.P.

    1975-01-01

    Astrophysical objects possessing high density of ultrahigh energy γ-particles are observed. The observations have been carried out in the Crimean astrophysical observatory of the AN SSSR for the period of 1969-1973. 43 celestial objects have been chosen for observation, among them are both the supposed and well-known sources of hard electromaanetic radiation (x-ray or γ-radiation with the energy of quanta up to 10 -8 eV). Regular observations of celestial bodies are followed by recording Cherenkov bursts by method of scanning with two groups of detectors, each consisting of two parallel-directed light detectors switched on to coincidences. Criteria for selecting the material are described. Paricular attention is paid to stability of the equipment parameters, permanent atmospheric transparency, presence of such atmospheric phenomena as meteors, summer lightings, and so on. As the objects under observation the authors involve x-ray sources, pulsars, supernovae, novae, supernovae remnants, radiogalaxies, point γ-sources. The data obtained and also those of other authors are summarized in a catalog including 72 objects from the Northern part of the celestial sphere

  20. Basics of Gamma Ray Detection

    Energy Technology Data Exchange (ETDEWEB)

    Stinnett, Jacob [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Venkataraman, Ram [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-09-13

    The objective of this training is to explain the origin of x-rays and gamma rays, gamma ray interactions with matter, detectors and electronics used in gamma ray-spectrometry, and features of a gamma-ray spectrum for nuclear material that is safeguarded.

  1. High energy astrophysics

    International Nuclear Information System (INIS)

    Engel, A.R.

    1979-01-01

    High energy astrophysical research carried out at the Blackett Laboratory, Imperial College, London is reviewed. Work considered includes cosmic ray particle detection, x-ray astronomy, gamma-ray astronomy, gamma and x-ray bursts. (U.K.)

  2. Gamma-Ray Instrument for Polarimetry, Spectroscopy and Imaging (GIPSI)

    National Research Council Canada - National Science Library

    Kroeger, R. A; Johnson, W. N; Kinzer, R. L; Kurfess, J. D; Inderhees, S. E; Phlips, B. F; Graham, B. L

    1996-01-01

    .... Gamma-ray polarimetry in the energy band around 60-300 keV is an interesting area of high energy astrophysics where observations have not been possible with the technologies employed in current and past space missions...

  3. Measurements of Cyclotron Features and Pulse Periods in the High-Mass X-Ray Binaries 4U 1538-522 and 4U 1907+09 with the International Gamma-Ray Astrophysics Laboratory

    Science.gov (United States)

    Hemphill, Paul B.; Rothschild, Richard E.; Caballero, Isabel; Pottschmidt, Katja; Kuhnel, Matthias; Furst, Felix; Wilms, Jorn

    2013-01-01

    We present a spectral and timing analysis of International Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of two high-mass X-ray binaries, 4U 1538-522 and 4U 1907+09. Our timing measurements for 4U 1538-522 find the pulse period to have exhibited a spin-up trend until approximately 2009, after which there is evidence for a torque reversal, with the source beginning to spin down to the most recently measured period of 525.407 plus or minus 0.001 seconds. The most recent INTEGRAL observations of 4U 1907+09 are not found to yield statistically significant pulse periods due to the significantly lower flux from the source compared with 4U 1538-522. A spectral model consisting of a power-law continuum with an exponential cutoff and modified by two cyclotron resonance scattering features is found to fit both sources well, with the cyclotron scattering features detected at approximately 22 and approximately 49 kiloelectronvolts for 4U 1538-522 and at approximately 18 and approximately 36 kiloelectronvolts for 4U 1907+09. The spectral parameters of 4U 1538-522 are generally not found to vary significantly with flux and there is little to no variation across the torque reversal. Examining our results in conjunction with previous work, we find no evidence for a correlation between cyclotron line energy and luminosity for 4U 1538-522. 4U 1907+09 shows evidence for a positive correlation between cyclotron line energy and luminosity, which would make it the fourth, and lowest luminosity, cyclotron line source to exhibit this relationship.

  4. 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.

  5. Gamma Ray Bursts-Afterglows and Counterparts

    Science.gov (United States)

    Fishman, Gerald J

    1998-01-01

    Several breakthrough discoveries were made last year of x-ray, optical and radio afterglows and counterparts to gamma-ray bursts, and a redshift has been associated with at least one of these. These discoveries were made possible by the fast, accurate gamma-ray burst locations of the BeppoSAX satellite. It is now generally believed that the burst sources are at cosmological distances and that they represent the most powerful explosions in the Universe. These observations also open new possibilities for the study of early star formation, the physics of extreme conditions and perhaps even cosmology. This session will concentrate on recent x-ray, optical and radio afterglow observations of gamma-ray bursts, associated redshift measurements, and counterpart observations. Several review and theory talks will also be presented, along with a summary of the astrophysical implications of the observations. There will be additional poster contributions on observations of gamma-ray burst source locations at wavelengths other than gamma rays. Posters are also solicited that describe new observational capabilities for rapid follow-up observations of gamma-ray bursts.

  6. The high intensity {gamma}-ray source (HI{gamma}S) and recent results

    Energy Technology Data Exchange (ETDEWEB)

    Tonchev, A.P. [Duke University and TUNL, Triangle University Nuclear Laboratory, P.O. Box 90308, Durham, NC 27708 0308 (United States)]. E-mail: tonchev@tunl.duke.edu; Boswell, M. [University of North Carolina at Chapel Hill and TUNL, Chapel Hill, NC 27599 (United States); Howell, C.R. [Duke University and TUNL, Triangle University Nuclear Laboratory, P.O. Box 90308, Durham, NC 27708 0308 (United States); Karwowski, H.J. [University of North Carolina at Chapel Hill and TUNL, Chapel Hill, NC 27599 (United States); Kelley, J.H. [North Carolina State University and TUNL, Raleigh, NC 27695 (United States); Tornow, W. [Duke University and TUNL, Triangle University Nuclear Laboratory, P.O. Box 90308, Durham, NC 27708 0308 (United States); Wu, Y.K. [Duke University and Duke Free Electron Laser Laboratory, Durham, NC 27708-0319 (United States)

    2005-12-15

    The high intensity {gamma}-ray source (HI{gamma}S) utilizes intra-cavity backscattering of free electron laser photons from the Duke electron storage ring to produce a unique monoenergetic beam of high-flux {gamma}-rays with high polarization and selectable energy resolution. At present, {gamma}-ray beams with energies from 2 to 58 MeV are available with intensities as high as 10{sup 5}-5 x 10{sup 6} {gamma}/s, energy spreads of 3% or better, and nearly 100% linear polarization. The quality and intensity of the {gamma}-ray beams at HI{gamma}S are responsible for the unprecedented performance of this facility in a broad range of research programs in nuclear structure, nuclear astrophysics and nuclear applications. Recent results from excitation of isomeric states in ({gamma}, n) reactions and parity assignments of dipole states determined via the ({gamma}, {gamma}') reaction are presented.

  7. Gamma ray calibration system

    International Nuclear Information System (INIS)

    Rosauer, P.J.; Flaherty, J.J.

    1981-01-01

    This invention is in the field of gamma ray inspection devices for tubular products and the like employing an improved calibrating block which prevents the sensing system from being overloaded when no tubular product is present, and also provides the operator with a means for visually detecting the presence of wall thicknesses which are less than a required minimum. (author)

  8. INTEGRAL and XMM-Newton observations of the weak gamma-ray burst GRB 030227

    DEFF Research Database (Denmark)

    Mereghetti, S.; Gotz, D.; Tiengo, A.

    2003-01-01

    We present International Gamma-Ray Astrophysical Laboratory ( INTEGRAL) and XMM-Newton observations of the prompt gamma-ray emission and the X-ray afterglow of GRB 030227, the first gamma-ray burst for which the quick localization obtained with the INTEGRAL Burst Alert System has led...

  9. A directional gamma-ray detector based on scintillator plates

    Energy Technology Data Exchange (ETDEWEB)

    Hanna, D., E-mail: hanna@physics.mcgill.ca; Sagnières, L.; Boyle, P.J.; MacLeod, A.M.L.

    2015-10-11

    A simple device for determining the azimuthal location of a source of gamma radiation, using ideas from astrophysical gamma-ray burst detection, is described. A compact and robust detector built from eight identical modules, each comprising a plate of CsI(Tl) scintillator coupled to a photomultiplier tube, can locate a point source of gamma rays with degree-scale precision by comparing the count rates in the different modules. Sensitivity to uniform environmental background is minimal.

  10. Gamma ray camera

    International Nuclear Information System (INIS)

    Wang, S.-H.; Robbins, C.D.

    1979-01-01

    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)

  11. Applications for X-ray detectors in astrophysics

    International Nuclear Information System (INIS)

    Remillard, R.A.

    2003-01-01

    Full text: Position-sensitive X-Ray detectors continue to playa central role in high-energy astrophysics. The current science goals are reviewed with emphasis on requirements in terms of camera performance. Wide-field imaging techniques, including coded mask cameras, are an essential part of space programs because of the transient nature of high-priority targets, e.g. eruptions from black-hole binaries and cosmic explosions such as gamma ray bursts. Pointing X-ray telescopes are being planned with a wide range of photon energies and with collection designs that include both mirrors and coded masks. Requirements for high spectral resolution and high time resolution are driven by diverse types of X-ray sources such as msec pulsars, quasars with emission-line profiles shaped by general relativity, and X-ray binaries that exhibit quasi-periodic oscillations in the range of 40-1300 Hz. Many laboratories and universities are involved in space-qualification of new detector technologies, e.g. CZT cameras, X-ray calorimeters, new types of CCDs, and GEM detectors. Even X-ray interferometry is on the horizon of NASA's science roadmap. The difficulties in advancing new technologies for space science applications require careful coordinations between industry and science groups in order to solve science problems while minimizing risk

  12. X-Ray Calorimeter Arrays for Astrophysics

    Science.gov (United States)

    Kilbourne, Caroline A.

    2009-01-01

    High-resolution x-ray spectroscopy is a powerful tool for studying the evolving universe. The grating spectrometers on the XMM and Chandra satellites started a new era in x-ray astronomy, but there remains a need for instrumentation that can provide higher spectral resolution with high throughput in the Fe-K band (around 6 keV) and can enable imaging spectroscopy of extended sources, such as supernova remnants and galaxy clusters. The instrumentation needed is a broad-band imaging spectrometer - basically an x-ray camera that can distinguish tens of thousands of x-ray colors. The potential benefits to astrophysics of using a low-temperature calorimeter to determine the energy of an incident x-ray photon via measurement of a small change in temperature was first articulated by S. H. Moseley over two decades ago. In the time since, technological progress has been steady, though full realization in an orbiting x-ray telescope is still awaited. A low-temperature calorimeter can be characterized by the type of thermometer it uses, and three types presently dominate the field. The first two types are temperature-sensitive resistors - semiconductors in the metal-insulator transition and superconductors operated in the superconducting-normal transition. The third type uses a paramagnetic thermometer. These types can be considered the three generations of x-ray calorimeters; by now each has demonstrated a resolving power of 2000 at 6 keV, but only a semiconductor calorimeter system has been developed to spaceflight readiness. The Soft X-ray Spectrometer on Astro-H, expected to launch in 2013, will use an array of silicon thermistors with I-IgTe x-ray absorbers that will operate at 50 mK. Both the semiconductor and superconductor calorimeters have been implemented in small arrays, kilo-pixel arrays of the superconducting calorimeters are just now being produced, and it is anticipated that much larger arrays will require the non-dissipative advantage of magnetic thermometers.

  13. Lunar based gamma ray astronomy

    International Nuclear Information System (INIS)

    Haymes, R.C.

    1985-01-01

    Gamma ray astronomy represents the study of the universe on the basis of the electromagnetic radiation with the highest energy. Gamma ray astronomy provides a crucial tool for the understanding of astronomical phenomena, taking into account nucleosynthesis in supernovae, black holes, active galaxies, quasars, the sources of cosmic rays, neutron stars, and matter-antimatter annihilation. Difficulties concerning the conduction of studies by gamma ray astronomy are related to the necessity to perform such studies far from earth because the atmosphere is a source of gamma rays. Studies involving the use of gamma ray instruments in earth orbit have been conducted, and more gamma ray astronomy observations are planned for the future. Imperfections of studies conducted in low earth orbit could be overcome by estalishing an observatory on the moon which represents a satellite orbiting at 60 earth radii. Details concerning such an observatory are discussed. 5 references

  14. Applied gamma-ray spectrometry

    CERN Document Server

    Dams, R; Crouthamel, Carl E

    1970-01-01

    Applied Gamma-Ray Spectrometry covers real life application of the gamma-ray and the devices used in their experimental studies. This book is organized into 9 chapters, and starts with discussions of the various decay processes, the possible interaction mechanisms of gamma radiation with matter, and the intrinsic and extrinsic variables, which affect the observed gamma-ray and X-ray spectra. The subsequent chapters deal with the properties and fabrication of scintillation detectors, semiconductor detectors, and proportional gas counters. These chapters present some of the most widely utilized

  15. Gamma ray beam transmutation

    International Nuclear Information System (INIS)

    Imasaki, K.; Li, D.; Miyamoto, S.; Amano, S.; Motizuki, T.

    2007-01-01

    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 1 97Au and 1 29Iodine. 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 1 29Iodine 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

  16. AGIS -- the Advanced Gamma-ray Imaging System

    Science.gov (United States)

    Krennrich, Frank

    2009-05-01

    The Advanced Gamma-ray Imaging System, AGIS, is envisioned to become the follow-up mission of the current generation of very high energy gamma-ray telescopes, namely, H.E.S.S., MAGIC and VERITAS. These instruments have provided a glimpse of the TeV gamma-ray sky, showing more than 70 sources while their detailed studies constrain a wealth of physics and astrophysics. The particle acceleration, emission and absorption processes in these sources permit the study of extreme physical conditions found in galactic and extragalactic TeV sources. AGIS will dramatically improve the sensitivity and angular resolution of TeV gamma-ray observations and therefore provide unique prospects for particle physics, astrophysics and cosmology. This talk will provide an overview of the science drivers, scientific capabilities and the novel technical approaches that are pursued to maximize the performance of the large array concept of AGIS.

  17. On Gamma-Ray Bursts

    CERN Document Server

    Ruffini, Remo; Bianco, Carlo Luciano; Caito, Letizia; Chardonnet, Pascal; Cherubini, Christian; Dainotti, Maria Giovanna; Fraschetti, Federico; Geralico, Andrea; Guida, Roberto; Patricelli, Barbara; Rotondo, Michael; Hernandez, Jorge Armando Rueda; Vereshchagin, Gregory; Xue, She-Sheng

    2008-01-01

    (Shortened) We show by example how the uncoding of Gamma-Ray Bursts (GRBs) offers unprecedented possibilities to foster new knowledge in fundamental physics and in astrophysics. After recalling some of the classic work on vacuum polarization in uniform electric fields by Klein, Sauter, Heisenberg, Euler and Schwinger, we summarize some of the efforts to observe these effects in heavy ions and high energy ion collisions. We then turn to the theory of vacuum polarization around a Kerr-Newman black hole, leading to the extraction of the blackholic energy, to the concept of dyadosphere and dyadotorus, and to the creation of an electron-positron-photon plasma. We then present a new theoretical approach encompassing the physics of neutron stars and heavy nuclei. It is shown that configurations of nuclear matter in bulk with global charge neutrality can exist on macroscopic scales and with electric fields close to the critical value near their surfaces. These configurations may represent an initial condition for the...

  18. Gamma Ray Bursts - Observations

    Science.gov (United States)

    Gehrels, N.; Cannizzo, J. K.

    2010-01-01

    We are in an exciting period of discovery for gamma-ray bursts. The Swift observatory is detecting 100 bursts per year, providing arcsecond localizations and sensitive observations of the prompt and afterglow emission. The Fermi observatory is observing 250 bursts per year with its medium-energy GRB instrument and about 10 bursts per year with its high-energy LAT instrument. In addition, rapid-response telescopes on the ground are providing new capabilities to study optical emission during the prompt phase and spectral signatures of the host galaxies. The combined data set is enabling great advances in our understanding of GRBs including afterglow physics, short burst origin, and high energy emission.

  19. Gamma-Ray Imaging Spectrometer (GRIS): a new balloon-borne experiment for gamma-ray line astronomy

    International Nuclear Information System (INIS)

    Teegarden, B.J.; Cline, T.L.; Gehrels, N.; Porreca, G.; Tueller, J.; Leventhal, M.; Huters, A.F.; Maccallum, C.J.; Stang, P.D.; Sandia Labs., Albuquerque, NM)

    1985-01-01

    High resolution gamma-ray spectroscopy is a relatively new field that holds great promise for further understanding of high energy astrophysical processes. When the high resolution gamma-ray spectrometer (GRSE) was removed from the GRO payload, a balloon program was initiated to permit continued development and improvement of instrumentation in this field, as well as continued scientific observations. The Gamma-Ray Imaging Spectrometer (GRIS) is one of the experiments selected as part of this program. The instrument contains a number of new and innovative features that are expected to produce a significant improvement in source location accuracy and sensitivity over previous balloon and satellite experiments

  20. Equipment for x- and gamma ray radiography

    International Nuclear Information System (INIS)

    Abd Nasir Ibrahim; Azali Muhammad; Ab Razak Hamzah; Abd Aziz Mohamed; Mohammad Pauzi Ismail

    2004-01-01

    The following topics related to the equipment for x - and gamma ray radiography are discussed in this chapter. The topics are x-ray source for Industrial Radiography: properties of x-ray, generation of x-ray, mechanism of x-ray production, x-ray equipment, power supply, distribution of x-ray intensity along the tube: gamma ray source for Industrial Radiography: properties of gamma rays, gamma ray sources, gamma ray projectors on cameras, source changing. Care of Radiographic Equipments: Merits and Demerits of x and Gamma Rays

  1. Cosmic Rays Astrophysics: The Discipline, Its Scope, and Its Applications

    Science.gov (United States)

    Barghouty, A. F.

    2009-01-01

    This slide presentation gives an overview of the discipline surrounding cosmic ray astrophysics. It includes information on recent assertions surrounding cosmic rays, exposure levels, and a short history with specific information on the origin, acceleration, transport, and modulation of cosmic rays.

  2. Apparatus for gamma ray radiography

    International Nuclear Information System (INIS)

    Kobayashi, Masatoshi; Enomoto, Shigemasa; Oga, Hiroshi

    1979-01-01

    This is the standard of Japan Non-Destructive Inspection Society, NDIS 1101-79, which stipulates on the design, construction and testing method of the apparatuses for gamma ray radiography used for taking industrial radiograms. The gamma ray apparatuses stipulated in this standard are those containing sealed radioactive isotopes exceeding 100 μCi, which emit gamma ray. The gamma ray apparatuses are classified into three groups according to their movability. The general design conditions, the irradiation dose rate and the sealed radiation sources for the gamma ray apparatuses are stipulated. The construction of the gamma ray apparatuses must be in accordance with the notification No. 52 of the Ministry of Labor, and safety devices and collimators must be equipped. The main bodies of the gamma ray apparatuses must pass the vibration test, penetration test, impact test and shielding efficiency test. The method of each test is described. The attached equipments must be also tested. The tests according to this standard are carried out by the makers of the apparatuses. The test records must be made when the apparatuses have passed the tests, and the test certificates are attached. The limit of guarantee by the endurance test must be clearly shown. The items to be shown on the apparatuses are stipulated. (Kako, I.)

  3. GRIPS - Gamma-Ray Imaging, Polarimetry and Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Greiner, J.; Mannheim, K.; Hudec, René; Mészáros, A.

    2012-01-01

    Roč. 34, č. 2 (2012), s. 551-582 ISSN 0922-6435 Institutional research plan: CEZ:AV0Z10030501 Keywords : compton and pair creation telescope * gamma-ray bursts * nucleosynthesis Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.969, year: 2012

  4. Balloon observation of gamma-ray burst

    International Nuclear Information System (INIS)

    Nishimura, Jun; Fujii, Masami; Yamagami, Takamasa; Oda, Minoru; Ogawara, Yoshiaki

    1978-01-01

    Cosmic gamma-ray burst is an interesting high energy astrophysical phenomenon, but the burst mechanism has not been well understood. Since 1975, long duration balloon flight has been conducted to search for gamma-ray bursts and to determine the source locations. A rotating cross-modulation collimator was employed to determine the locations of sources, and four NaI(Tl) scintillation counters were employed to detect hard X-ray with energy from 20 to 200 keV. The balloon light was performed at altitude of 8.3 mb from September 28, 1977, and the observation time of 79 hours was achieved. In this experiment, the monitor counter was not mounted. The count increase was observed at 16 h 22 m 31 s JST on October 1, 1977. The event disappeared after 1 sec. The total flux is estimated to be 1.6 x 10 -6 erg/cm 2 sec at the top of the atmosphere. When this event was observed, the solar-terrestrial environment was also quiet. Thus, this event was attributed to a small gamma-ray burst. Unfortunately, the duration of the burst was so short that the position of the burst source was not able to be determined. (Yoshimori, M.)

  5. AGILE: A gamma-ray mission

    International Nuclear Information System (INIS)

    Tavani, M.; Caraveo, P.; Mereghetti, S.; Perotti, F.; Vercellone, S.; Barbiellini, G.; Budini, G.; Longo, F.; Prest, M.; Vallazza, E.; Cocco, V.; Morselli, A.; Picozza, P.; Pittori, C.; Costa, E.; Feroci, M.; Lapshov, I.; Morelli, E.; Rubini, A.; Soffitta, P.

    2000-01-01

    AGILE is an innovative, cost-effective gamma-ray mission selected by the Italian Space Agency for a Program of Small Scientific Missions. The AGILE gamma-ray imaging detector (GRID, made of a Silicon tracker and CsI Mini-Calorimeter) is designed to detect and image photons in the 30 MeV-50 GeV energy band with good sensitivity and very large field of view (FOV ∼3 sr). The X-ray detector, Super-AGILE, sensitive in the 10-40 keV band and integrated on top of the GRID gamma-ray tracker will provide imaging (1-3 arcmin) and moderate spectroscopy. For selected sky areas, AGILE might achieve a flux sensitivity (above 100 MeV) better than 5x10 -8 ph cm 2 s -1 at the completion of its scientific program. AGILE will operate as an Observatory open to the international community and is planned to be operational during the year 2002 for a nominal 2-year mission. It will be an ideal 'bridge' between EGRET and GLAST, and the only mission entirely dedicated to high-energy astrophysics above 30 MeV during that period

  6. Gamma rays at airplane altitudes

    International Nuclear Information System (INIS)

    Iwai, J.; Koss, T.; Lord, J.; Strausz, S.; Wilkes, J.; Woosley, J.

    1990-01-01

    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

  7. Observational techniques of gamma rays astronomy in low energy

    International Nuclear Information System (INIS)

    Costa, J.M. da.

    1982-02-01

    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) [pt

  8. CELESTE: an atmospheric Cherenkov telescope for high energy gamma astrophysics

    Czech Academy of Sciences Publication Activity Database

    Paré, E.; Balauge, B.; Bazer-Bachi, R.; Bergeret, H.; Berny, F.; Briand, N.; Bruel, P.; Cerutti, M.; Collon, J.; Cordier, A.; Cornbise, P.; Debiais, G.; Dezalay, J. P.; Dumora, D.; Durand, E.; Eschstruth, P.; Espigat, P.; Fabre, B.; Fleury, P.; Gilly, J.; Gouillaud, J. C.; Gregory, C.; Hérault, N.; Holder, J.; Hrabovský, Miroslav; Incerti, S.; Jouenne, A.; Kalt, L.; LeGallou, R.; Lott, B.; Manigot, P.; Neveu, J.; Olive, J. F.; Palatka, Miroslav; Perez, A.; Rebii, A.; Rob, L.; Sans, J. L.; Schovánek, Petr; Villard, G.

    2002-01-01

    Roč. 490, - (2002), s. 71-89 ISSN 0168-9002 R&D Projects: GA MŠk LN00A006 Institutional research plan: CEZ:AV0Z1010920 Keywords : gamma-ray astronopy * atmospheric Cherenkov detector Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 1.167, year: 2002

  9. Compton Gamma-Ray Observatory

    Science.gov (United States)

    1991-01-01

    This photograph shows the Compton Gamma-Ray Observatory (GRO) being deployed by the Remote Manipulator System (RMS) arm aboard the Space Shuttle Atlantis during the STS-37 mission in April 1991. The GRO reentered Earth atmosphere and ended its successful mission in June 2000. For nearly 9 years, the GRO Burst and Transient Source Experiment (BATSE), designed and built by the Marshall Space Flight Center (MSFC), kept an unblinking watch on the universe to alert scientists to the invisible, mysterious gamma-ray bursts that had puzzled them for decades. By studying gamma-rays from objects like black holes, pulsars, quasars, neutron stars, and other exotic objects, scientists could discover clues to the birth, evolution, and death of stars, galaxies, and the universe. The gamma-ray instrument was one of four major science instruments aboard the Compton. It consisted of eight detectors, or modules, located at each corner of the rectangular satellite to simultaneously scan the entire universe for bursts of gamma-rays ranging in duration from fractions of a second to minutes. In January 1999, the instrument, via the Internet, cued a computer-controlled telescope at Las Alamos National Laboratory in Los Alamos, New Mexico, within 20 seconds of registering a burst. With this capability, the gamma-ray experiment came to serve as a gamma-ray burst alert for the Hubble Space Telescope, the Chandra X-Ray Observatory, and major gound-based observatories around the world. Thirty-seven universities, observatories, and NASA centers in 19 states, and 11 more institutions in Europe and Russia, participated in the BATSE science program.

  10. Cosmic gamma-ray burst

    International Nuclear Information System (INIS)

    Yamagami, Takamasa

    1985-01-01

    Ballon experiments for searching gamma-ray burst were carried out by employing rotating-cross modulation collimators. From a very long observation of total 315 hours during 1975 to 1979, three gamma-ray intensity anomalies were observed which were speculated as a gamma-ray burst. As for the first gamma-ray intensity anomaly observed in 1975, the burst source could be located precisely but the source, heavenly body, could not be specified. Gamma-ray burst source estimation was made by analyzing distribution of burst source in the celestial sphere, burst size distribution, and burst peak. Using the above-mentioned data together with previously published ones, apparent inconsistency was found between the observed results and the adopted theory that the source was in the Galaxy, and this inconsistency was found due to the different time profiles of the burst observed with instruments of different efficiency. It was concluded by these analysis results that employment of logN - logP (relation between burst frequency and burst count) was better than that of logN - logS (burst size) in the examination of gamma-ray burst because the former was less uncertain than the latter. Analyzing the author's observed gamma-ray burst data and the related published data, it was clarified that the burst distribution was almost P -312 for the burst peak value larger than 10 -6 erg/cm 2 .sec. The author could indicate that the calculated celestial distribution of burst source was consistent with the observed results by the derivation using the logN - logP relationship and that the burst larger than 10 -6 erg/cm 2 .sec happens about one thousand times a year, about ten times of the previous value. (Takagi, S.)

  11. Exploring the extreme gamma-ray sky with HESS

    International Nuclear Information System (INIS)

    Sol, Helene

    2006-01-01

    The international HESS experiment. High Energy Stereoscopic System, fully operational since January 2004, is opening a new era for extreme gamma-ray astronomy. Located in Namibia, it is now the most sensitive detector for cosmic sources of very high energy (VHE) gamma-rays, in the tera-electron-volt (TeV) range. In July 2005, it had already more than double the number of sources detected at such energies, with the discovery of several active galactic nuclei (AGN), supernova remnants and plerions, a binary pulsar system, a microquasar candidate, and a sample of yet unidentified sources. HESS has also provide for the first time gamma-ray images of extended sources with the first astrophysical jet resolved in gamma-rays, and the first mapping of a shell supernova remnant, which proves the efficiency of in situ acceleration of particles up to 100 TeV and beyond

  12. Dissecting the Gamma-Ray Background in Search of Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Cholis, Ilias; Hooper, Dan; McDermott, Samuel D.

    2014-02-01

    Several classes of astrophysical sources contribute to the approximately isotropic gamma-ray background measured by the Fermi Gamma-Ray Space Telescope. In this paper, we use Fermi's catalog of gamma-ray sources (along with corresponding source catalogs at infrared and radio wavelengths) to build and constrain a model for the contributions to the extragalactic gamma-ray background from astrophysical sources, including radio galaxies, star-forming galaxies, and blazars. We then combine our model with Fermi's measurement of the gamma-ray background to derive constraints on the dark matter annihilation cross section, including contributions from both extragalactic and galactic halos and subhalos. The resulting constraints are competitive with the strongest current constraints from the Galactic Center and dwarf spheroidal galaxies. As Fermi continues to measure the gamma-ray emission from a greater number of astrophysical sources, it will become possible to more tightly constrain the astrophysical contributions to the extragalactic gamma-ray background. We project that with 10 years of data, Fermi's measurement of this background combined with the improved constraints on the astrophysical source contributions will yield a sensitivity to dark matter annihilations that exceeds the strongest current constraints by a factor of ~ 5 - 10.

  13. Fermi-LAT Observations of the Gamma-Ray Burst GRB 130427A

    NARCIS (Netherlands)

    Ackermann, M.; et al., [Unknown; van der Horst, A.J.

    2014-01-01

    The observations of the exceptionally bright gamma-ray burst (GRB) 130427A by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope provide constraints on the nature of these unique astrophysical sources. GRB 130427A had the largest fluence, highest-energy photon (95 GeV), longest

  14. Optical observations of Gamma-Ray Bursts

    International Nuclear Information System (INIS)

    Hjorth, J.; Pian, E.; Fynbo, J.P.U.

    2004-01-01

    We briefly review the status and recent progress in the field of optical observations of gamma-ray burst afterglows. We will focus on the fundamental observational evidence for the relationship between gamma-ray bursts and the final evolutionary phases of massive stars. In particular, we will address (i) gamma-ray burst host galaxies, (ii) optically dark gamma-ray burst afterglows, (iii) the gamma-ray burst-supernova connection, and (iv) the relation between X-ray flashes, gamma-ray bursts, and supernovae

  15. Multiwavelength Study of Gamma-Ray Bright Blazars

    Science.gov (United States)

    Morozova, Daria; Larionov, V. M.; Hagen-Thorn, V. A.; Jorstad, S. G.; Marscher, A. P.; Troitskii, I. S.

    2011-01-01

    We investigate total intensity radio images of 6 gamma-ray bright blazars (BL Lac, 3C 279, 3C 273, W Com, PKS 1510-089, and 3C 66A) and their optical and gamma-ray light curves to study connections between gamma-ray and optical brightness variations and changes in the parsec-scale radio structure. We use high-resolution maps obtained by the BU group at 43 GHz with the VLBA, optical light curves constructed by the St.Petersburg State U. (Russia) team using measurements with the 0.4 m telescope of St.Petersburg State U. (LX200) and the 0.7 m telescope of the Crimean Astrophysical Observatory (AZT-8), and gamma-ray light curves, which we have constructed with data provided by the Fermi Large Area Telescope. Over the period from August 2008 to November 2009, superluminal motion is found in all 6 objects with apparent speed ranging from 2c to 40c. The blazars with faster apparent speeds, 3C 273, 3C 279, PKS 1510-089, and 3C 66A, exhibit stronger variability of the gamma-ray emission. There is a tendency for sources with sharply peaked gamma-ray flares to have faster jet speed than sources with gamma-ray light curves with no sharp peaks. Gamma-ray light curves with sharply peaked gamma-ray flares possess a stronger gamma-ray/optical correlations. The research at St.Petersburg State U. was funded by the Minister of Education and Science of the Russian Federation (state contract N#P123). The research at BU was funded in part by NASA Fermi Guest Investigator grant NNX08AV65G and by NSF grant AST-0907893. The VLBA is an instrument of the National Radio Astronomy Observatory, a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  16. The Gamma-ray Sky with Fermi

    Science.gov (United States)

    Thompson, David

    2012-01-01

    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, novae, 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 dark matter annihilation. Some results include a stringent limit on Lorentz invariance derived from a gamma-ray burst, unexpected gamma-ray variability from the Crab Nebula, a huge gamma-ray structure associated with the center of our galaxy, surprising behavior from some gamma-ray binary systems, and a possible constraint on some WIMP models for dark matter.

  17. Terrestrial gamma-ray flashes

    Science.gov (United States)

    Marisaldi, Martino; Fuschino, Fabio; Labanti, Claudio; Tavani, Marco; Argan, Andrea; Del Monte, Ettore; Longo, Francesco; Barbiellini, Guido; Giuliani, Andrea; Trois, Alessio; Bulgarelli, Andrea; Gianotti, Fulvio; Trifoglio, Massimo

    2013-08-01

    Lightning and thunderstorm systems in general have been recently recognized as powerful particle accelerators, capable of producing electrons, positrons, gamma-rays and neutrons with energies as high as several tens of MeV. In fact, these natural systems turn out to be the highest energy and most efficient natural particle accelerators on Earth. Terrestrial Gamma-ray Flashes (TGFs) are millisecond long, very intense bursts of gamma-rays and are one of the most intriguing manifestation of these natural accelerators. Only three currently operative missions are capable of detecting TGFs from space: the RHESSI, Fermi and AGILE satellites. In this paper we review the characteristics of TGFs, including energy spectrum, timing structure, beam geometry and correlation with lightning, and the basic principles of the associated production models. Then we focus on the recent AGILE discoveries concerning the high energy extension of the TGF spectrum up to 100 MeV, which is difficult to reconcile with current theoretical models.

  18. Terrestrial gamma-ray flashes

    International Nuclear Information System (INIS)

    Marisaldi, Martino; Fuschino, Fabio; Labanti, Claudio; Tavani, Marco; Argan, Andrea; Del Monte, Ettore; Longo, Francesco; Barbiellini, Guido; Giuliani, Andrea; Trois, Alessio; Bulgarelli, Andrea; Gianotti, Fulvio; Trifoglio, Massimo

    2013-01-01

    Lightning and thunderstorm systems in general have been recently recognized as powerful particle accelerators, capable of producing electrons, positrons, gamma-rays and neutrons with energies as high as several tens of MeV. In fact, these natural systems turn out to be the highest energy and most efficient natural particle accelerators on Earth. Terrestrial Gamma-ray Flashes (TGFs) are millisecond long, very intense bursts of gamma-rays and are one of the most intriguing manifestation of these natural accelerators. Only three currently operative missions are capable of detecting TGFs from space: the RHESSI, Fermi and AGILE satellites. In this paper we review the characteristics of TGFs, including energy spectrum, timing structure, beam geometry and correlation with lightning, and the basic principles of the associated production models. Then we focus on the recent AGILE discoveries concerning the high energy extension of the TGF spectrum up to 100 MeV, which is difficult to reconcile with current theoretical models

  19. Gamma-ray burst spectra

    International Nuclear Information System (INIS)

    Teegarden, B.J.

    1982-01-01

    A review of recent results in gamma-ray burst spectroscopy is given. Particular attention is paid to the recent discovery of emission and absorption features in the burst spectra. These lines represent the strongest evidence to date that gamma-ray bursts originate on or near neutron stars. Line parameters give information on the temperature, magnetic field and possibly the gravitational potential of the neutron star. The behavior of the continuum spectrum is also discussed. A remarkably good fit to nearly all bursts is obtained with a thermal-bremsstrahlung-like continuum. Significant evolution is observed of both the continuum and line features within most events

  20. 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....... By knowing the spectral components and their amplitudes in each of the measured spectra one is able to extract more information from the data than possible with the methods used otherwise....

  1. 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.

  2. Minicourses in Astrophysics, Modular Approach, Vol. I.

    Science.gov (United States)

    Illinois Univ., Chicago.

    This is the first volume of a two-volume minicourse in astrophysics. It contains chapters on the following topics: planetary atmospheres; X-ray astronomy; radio astrophysics; molecular astrophysics; and gamma-ray astrophysics. Each chapter gives much technical discussion, mathematical treatment, diagrams, and examples. References are included with…

  3. Particle and astrophysics aspects of ultrahigh energy cosmic rays

    International Nuclear Information System (INIS)

    Sigl, G.

    2001-01-01

    The origin of cosmic rays is one of the major unresolved astrophysical questions. In particular, the highest energy cosmic rays observed possess macroscopic energies and their origin is likely to be associated with the most energetic processes in the Universe. Their existence triggered a flurry of theoretical explanations ranging from conventional shock acceleration to particle physics beyond the Standard Model and processes taking place at the earliest moments of our Universe. Furthermore, many new experimental activities promise a strong increase of statistics at the highest energies and a combination with γ-ray and neutrino astrophysics will put strong constraints on these theoretical models. Detailed Monte Carlo simulations indicate that charged ultra-high energy cosmic rays can also be used as probes of large scale magnetic fields whose origin may open another window into the very early Universe. We give an overview over this quickly evolving research field. (author)

  4. Gamma-ray imaging. Applications in nuclear non-proliferation and homeland security

    International Nuclear Information System (INIS)

    Vetter, Kai; Mihailescu, Lucian

    2010-01-01

    This paper provides the motivation and describes implementations of gamma-ray imaging for homeland security applications and more general for national and international nuclear security. As in nuclear medicine and astrophysics, the goal of gamma-ray imaging is the detection and localization of nuclear materials, however, here in a terrestrial environment with distances between nuclear medicine and astrophysics, i.e. in the range of 1-100 meters. Due to the recently increased threat of nuclear terrorism, the detection of illicit nuclear materials and the prevention of nuclear proliferation through the development of advanced gamma-ray imaging concepts and technologies has become and active research field. (author)

  5. The Gamma-ray Universe through Fermi

    Science.gov (United States)

    Thompson, David J.

    2012-01-01

    Gamma rays, the most powerful form of light, reveal extreme conditions in the Universe. The Fermi Gamma-ray Space Telescope and its smaller cousin AGILE have been exploring the gamma-ray sky for several years, enabling a search for powerful transients like gamma-ray bursts, novae, 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 dark matter annihilation. Some results include a stringent limit on Lorentz invariance derived from a gamma-ray burst, unexpected gamma-ray variability from the Crab Nebula, a huge ga.nuna-ray structure associated with the center of our galaxy, surprising behavior from some gamma-ray binary systems, and a possible constraint on some WIMP models for dark matter.

  6. Gamma rays for pedestrians

    International Nuclear Information System (INIS)

    Lipkin, H.J.

    1987-01-01

    Nuclear gamma radiation does not have many of the properties taken for granted in atomic or molecular radiation and necessary for lasers. The basic science and technology underlying these differences and the proposed methods of overcoming difficulties resulting from them are not properly understood. Considerable illumination in this interdisciplinary problem could be provided by some back-of-the-envelope calculations and simple experimental surveys by small groups of students and postdocs with an elementary knowledge of the nuclear and solid state physics which is evidently not familiar these days to laser physicists. 3 refs

  7. Current Status of Astrophysics of Cosmic Rays

    Science.gov (United States)

    Moskalenko, Igor

    2016-03-01

    I will review the current instrumentation and recent results. I will discuss which measurements have to be done in the near future to significantly advance our knowledge about the phenomenon of cosmic rays, their sources, and their interactions with the interstellar medium. A support from NASA APRA Grant No. NNX13AC47G is greatly acknowledged.

  8. Gravitational wave: gamma-ray burst connections.

    Science.gov (United States)

    Hough, Jim

    2007-05-15

    After 35 years of experimental research, we are rapidly approaching the point at which gravitational waves (GWs) from astrophysical sources may be directly detected by the long-baseline detectors LIGO (USA), GEO 600 (Germany/UK), VIRGO (Italy/France) and TAMA 300 (Japan), which are now in or coming into operation.A promising source of GWs is the coalescence of compact binary systems, events which are now believed to be the origin of short gamma-ray bursts (GRBs). In this paper, a brief review of the state of the art in detector development and exploitation will be given, with particular relevance to a search for signals associated with GRBs, and plans for the future will be discussed.

  9. Gamma-Rays from Galactic Compact Sources

    Science.gov (United States)

    Kaaret, Philip

    2007-04-01

    Recent discoveries have revealed many sources of TeV photons in our Mikly Way galaxy powered by compact objects, either neutron stars or black holes. These objects must be powerful particle accelerators, some with peak energies of at least 100 TeV, and may be neutrino, as well as photon, sources. Future TeV observations will enable us to address key questions concerning particle acceleration by compact objects including the fraction of energy which accreting black holes channel into relativstic jet production, whether the compact object jets are leptonic or hadronic, and the mechanism by which pulsar winds accelerate relativistic particles. We report on work done related to compact Galactic objects in preparation of a White Paper on the status and future of ground-based gamma-ray astronomy requested by the Division of Astrophysics of the American Physical Society.

  10. New Worlds / New Horizons Science with an X-ray Astrophysics Probe

    Science.gov (United States)

    Smith, Randall K.; Bookbinder, Jay A.; Hornschemeier, Ann E.; Bandler, Simon; Brandt, W. N.; Hughes, John P.; McCammon, Dan; Matsumoto, Hironori; Mushotzky, Richard; Osten, Rachel A.; hide

    2014-01-01

    In 2013 NASA commenced a design study for an X-ray Astrophysics Probe to address the X-ray science goals and program prioritizations of the Decadal Survey New World New Horizons (NWNH) with a cost cap of approximately $1B. Both the NWNH report and 2011 NASA X-ray mission concept study found that high-resolution X-ray spectroscopy performed with an X-ray microcalorimeter would enable the most highly rated NWNH X-ray science. Here we highlight some potential science topics, namely: 1) a direct, strong-field test of General Relativity via the study of accretion onto black holes through relativistic broadened Fe lines and their reverberation in response to changing hard X-ray continuum, 2) understanding the evolution of galaxies and clusters by mapping temperatures, abundances and dynamics in hot gas, 3) revealing the physics of accretion onto stellar-mass black holes from companion stars and the equation of state of neutron stars through timing studies and time-resolved spectroscopy of X-ray binaries and 4) feedback from AGN and star formation shown in galaxy-scale winds and jets. In addition to these high-priority goals, an X-ray astrophysics probe would be a general-purpose observatory that will result in invaluable data for other NWNH topics such as stellar astrophysics, protostars and their impact on protoplanetary systems, X-ray spectroscopy of transient phenomena such as high-z gamma-ray bursts and tidal capture of stars by massive black holes, and searches for dark matter decay.

  11. An X-ray perspective on a gamma-ray mission

    DEFF Research Database (Denmark)

    Lund, Niels

    2003-01-01

    The most recent astrophysics mission of ESA is INTEGRAL, a mission dedicated to gamma-ray astronomy (Winkler et al. 2003). INTEGRAL carries two gamma-ray instruments: the imager, IBIS, and the spectrometer, SPI, and in addition an optical monitor, OMC, and an X-ray monitor, JEM-X. INTEGRAL is an ...... is an observatory mission with 70% of the observation time available to the general astronomical community through a peer-reviewed selection process. This paper describes the INTEGRAL mission primarily as seen from the JEM-X perspective....

  12. CELESTE an atmospheric Cherenkov telescope for high energy gamma astrophysics

    CERN Document Server

    Paré, E; Bazer-Bachi, R; Bergeret, H; Berny, F; Briand, N; Bruel, P; Cerutti, M; Collon, J; Cordier, A; Cornebise, P; Debiais, G; Dezalay, J P; Dumora, D; Durand, E; Eschstruth, P T; Espigat, P; Fabre, B; Fleury, P; Gilly, J; Gouillaud, J C; Gregory, C; Herault, N; Holder, J; Hrabovsky, M; Incerti, S; Jouenne, A; Kalt, L; Legallou, R; Lott, B; Lodygensky, O; Manigot, P; Manseri, H; Manitaz, H; Martin, M; Morano, R; Morineaud, G; Muenz, F; Musquere, A; Naurois, M D; Neveu, J; Noppe, J M; Olive, J F; Palatka, M; Pérez, A; Quebert, J; Rebii, A; Reposeur, T; Rob, L; Roy, P; Sans, J L; Sako, T; Schovanek, P; Smith, D A; Snabre, P; Villard, G

    2002-01-01

    CELESTE is an atmospheric Cherenkov telescope based on the sampling method which makes use of the de-commissioned THEMIS solar electrical plant in the French Pyrenees. A large (2000 m sup 2) mirror surface area from 40 independent heliostats followed by a secondary optic, a trigger system using analog summing techniques and signal digitization with 1 GHz flash ADCs make possible the detection of cosmic gamma-rays down to 30 GeV. This paper provides a detailed technical description of the CELESTE installation.

  13. Cosmic Ray Astrophysics using The High Altitude Water Cherenkov (HAWC Observatory in México

    Directory of Open Access Journals (Sweden)

    de la Fuente Eduardo

    2017-01-01

    Full Text Available The High-Altitude Water Cherenkov (HAWC TeV gamma–ray Observatory in México is ready to search and study gamma-ray emission regions, extremely high-energy cosmic-ray sources, and to identify transient phenomena. With a better Gamma/Hadron rejection method than other similar experiments, it will play a key role in triggering multi–wavelength and multi–messenger studies of active galaxies (AGN, gamma-ray bursts (GRB, supernova remnants (SNR, pulsar wind nebulae (PWN, Galactic Plane Sources, and Cosmic Ray Anisotropies. It has an instantaneous field-of-view of ∼2 str, equivalent to 15% of the whole sky and continuous operation (24 hours per day. The results obtained by HAWC–111 (111 detectors in operation were presented on the proceedings of the International Cosmic Ray Conference 2015 and in [1]. The results obtained by HAWC–300 (full operation are now under analysis and will be published in forthcoming papers starting in 2017 (see preliminary results on http://www.hawc-observatory.org/news/. Here we present the HAWC contributions on cosmic ray astrophysics via anisotropies studies, summarizing the HAWC detector and its upgrading by the installation of “outriggers”.

  14. Multifrequency Observations of Gamma-Ray Burst

    OpenAIRE

    Greiner, J.

    1995-01-01

    Neither a flaring nor a quiescent counterpart to a gamma-ray burst has yet been convincingly identified at any wavelength region. The present status of the search for counterparts of classical gamma-ray bursts is given. Particular emphasis is put on the search for flaring counterparts, i.e. emission during or shortly after the gamma-ray emission.

  15. Stellar Sources of Gamma-ray Bursts

    OpenAIRE

    Luchkov, B. I.

    2011-01-01

    Correlation analysis of Swift gamma-ray burst coordinates and nearby star locations (catalog Gliese) reveals 4 coincidences with good angular accuracy. The random probability is 4\\times 10^{-5}, so evidencing that coincident stars are indeed gamma-ray burst sources. Some additional search of stellar gamma-ray bursts is discussed.

  16. Gamma-rays from deep inelastic collisions

    International Nuclear Information System (INIS)

    Stephens, F.S.

    1981-01-01

    My objective in this talk is to consider the question: 'What can be learned about deep inelastic collisions (DIC) from studying the associated gamma-rays'. First, I discuss the origin and nature of the gamma-rays from DIC, then the kinds of information gamma-ray spectra contain, and finally come to the combination of these two subjects. (orig./HSI)

  17. Coincidence gamma-ray spectrometry

    DEFF Research Database (Denmark)

    Markovic, Nikola; Roos, Per; Nielsen, Sven Poul

    2017-01-01

    Gamma-ray spectrometry with high-purity germanium (HPGe) detectors is often the technique of choice in an environmental radioactivity laboratory. When measuring environmental samples associated activities are usually low so an important parameter that describes the performance of the spectrometer...... for a nuclide of interest is the minimum detectable activity (MDA). There are many ways for lowering the MDAs in gamma spectrometry. Recently, developments of fast and compact digital acquisition systems have led to growing number of multiple HPGe detector spectrometers. In these applications all detected...

  18. Cosmic gamma-ray bursts

    International Nuclear Information System (INIS)

    Hurley, K.

    1989-01-01

    This paper reviews the essential aspects of the gamma-ray burst (GRB) phenomenon, with emphasis on the more recent results. GRBs are introduced by their time histories, which provide some evidence for a compact object origin. The energy spectra of bursts are presented and they are seen to demonstrate practically unambiguously that the origin of some GRBs involves neutron stars. Counterpart searches are reviewed briefly and the statistical properties of bursters treated. This paper presents a review of the three known repeating bursters (the Soft Gamma Repeaters). Extragalactic and galactic models are discussed and future prospects are assessed

  19. International spring school observing the X-and gamma-ray sky

    Energy Technology Data Exchange (ETDEWEB)

    Paul, J; Longair, M; Von Ballmoos, P; Daigne, F; Baring, M; Gudel, M; King, A; Dotani, T; Arnaud, M; Gudel, M; Malzac, J; Servillat, M; Soldi, S; Corbel, S; Beckmann, V; Rodriguez, J; Erlund, M; Bodaghee, A; Graham, J; Ruiz, A; Corbel, S; Fabian, A; Tagger, M; Grenier, I; Bernard, R; Jackson, N; Eckart, A; Grenier, I; Belloni, T; Stella, L; Vink, J; KnodLseder, J; Hermsen, W; Ferrando, Ph; Ibragimov, A

    2006-07-01

    This school, dedicated to young researchers, will clarify our present knowledge of the X-ray sky and give the opportunity to learn about the observatories and tools which are available. The contributions have been organized into 3 issues: -) fundamental physics, -) X-ray and Gamma-ray instruments and analysis techniques, and -) astrophysical objects. This document gathers only the slides of the presentations.

  20. International spring school observing the X-and gamma-ray sky

    International Nuclear Information System (INIS)

    Paul, J.; Longair, M.; Von Ballmoos, P.; Daigne, F.; Baring, M.; Gudel, M.; King, A.; Dotani, T.; Arnaud, M.; Gudel, M.; Malzac, J.; Servillat, M.; Soldi, S.; Corbel, S.; Beckmann, V.; Rodriguez, J.; Erlund, M.; Bodaghee, A.; Graham, J.; Ruiz, A.; Corbel, S.; Fabian, A.; Tagger, M.; Grenier, I.; Bernard, R.; Jackson, N.; Eckart, A.; Grenier, I.; Belloni, T.; Stella, L.; Vink, J.; KnodLseder, J.; Hermsen, W.; Ferrando, Ph.; Ibragimov, A.

    2006-01-01

    This school, dedicated to young researchers, will clarify our present knowledge of the X-ray sky and give the opportunity to learn about the observatories and tools which are available. The contributions have been organized into 3 issues: -) fundamental physics, -) X-ray and Gamma-ray instruments and analysis techniques, and -) astrophysical objects. This document gathers only the slides of the presentations

  1. Gamma-Ray Bursts The Brightest Explosions in the Universe

    CERN Document Server

    Vedrenne, Gilbert

    2009-01-01

    Since their discovery was first announced in 1973, gamma-ray bursts (GRBs) have been among the most fascination objects in the universe. While the initial mystery has gone, the fascination continues, sustained by the close connection linking GRBs with some of the most fundamental topics in modern astrophysics and cosmology. Both authors have been active in GRB observations for over two decades and have produced an outstanding account on both the history and the perspectives of GRB research.

  2. Gamma-ray-line astronomy: the case of 26Al

    International Nuclear Information System (INIS)

    Prantzos, N.

    1986-07-01

    The recent detection of the 1.8 MeV line in the galactic plane, attributed to the decay of ∼ 3 Solar mass of radioactive 26 Al, brought closer together the disciplines of gamma-ray Astronomy and Nuclear Astrophysics. A review is presented here of the possible production mechanisms and sites of 26 Al in the Galaxy, with an emphasis on the role of massive, mass losing stars

  3. Relativistic motion in gamma-ray bursts

    International Nuclear Information System (INIS)

    Krolik, J.H.; Pier, E.A.

    1991-01-01

    Three fundamental problems affect models of gamma-ray bursts, i.e., the energy source, the ability of high-energy photons to escape the radiation region, and the comparative weakness of X-ray emission. It is indicated that relativistic bulk motion of the gamma-ray-emitting plasma generically provides a solution to all three of these problems. Results show that, if the plasma that produces gamma-ray bursts has a bulk relativistic velocity with Lorentz factor gamma of about 10, several of the most troubling problems having to do with gamma-ray bursts are solved. 42 refs

  4. Inverse Compton gamma-rays from pulsars

    International Nuclear Information System (INIS)

    Morini, M.

    1983-01-01

    A model is proposed for pulsar optical and gamma-ray emission where relativistic electrons beams: (i) scatter the blackbody photons from the polar cap surface giving inverse Compton gamma-rays and (ii) produce synchrotron optical photons in the light cylinder region which are then inverse Compton scattered giving other gamma-rays. The model is applied to the Vela pulsar, explaining the first gamma-ray pulse by inverse Compton scattering of synchrotron photons near the light cylinder and the second gamma-ray pulse partly by inverse Compton scattering of synchrotron photons and partly by inverse Compton scattering of the thermal blackbody photons near the star surface. (author)

  5. Airborne gamma ray spectrometer surveying

    International Nuclear Information System (INIS)

    1991-01-01

    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

  6. Compton suppression gamma ray spectrometry

    International Nuclear Information System (INIS)

    Landsberger, S.; Iskander, F.Y.; Niset, M.; Heydorn, K.

    2002-01-01

    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)

  7. Cosmic gamma-ray background from dark matter annihilation

    International Nuclear Information System (INIS)

    Ando, Shin'ichiro

    2007-01-01

    High-energy photons from pair annihilation of dark matter particles contribute to the cosmic gamma-ray background (CGB) observed in a wide energy range. The precise shape of the energy spectrum of CGB depends on the nature of dark matter particles. In order to discriminate between the signals from dark matter annihilation and other astrophysical sources, however, the information from the energy spectrum of CGB may not be sufficient. We show that dark matter annihilation not only contributes to the mean CGB intensity, but also produces a characteristic anisotropy, which provides a powerful tool for testing the origins of the observed CGB. We show that the expected sensitivity of future gamma-ray detectors such as GLAST should allow us to measure the angular power spectrum of CGB anisotropy, if dark matter particles are supersymmetric neutralinos and they account for most of the observed mean intensity. As the intensity of photons from annihilation is proportional to the density squared, we show that the predicted shape of the angular power spectrum of gamma rays from dark matter annihilation is different from that due to other astrophysical sources such as blazars, whose intensity is linearly proportional to density. Therefore, the angular power spectrum of the CGB provides a 'smoking-gun' signature of gamma rays from dark matter annihilation

  8. CAMAC gamma ray scanning system

    International Nuclear Information System (INIS)

    Moss, C.E.; Pratt, J.C.; Shunk, E.R.

    1981-01-01

    A flexible gamma-ray scanning system, based on a LeCroy 3500 multichannel analyzer and CAMAC modules, is described. The system is designed for making simultaneous passive and active scans of objects of interest to nuclear safeguards. The scanner is a stepping-motor-driven carriage; the detectors, a bismuth-germanate scintillator and a high-purity germanium detector. A total of sixteen peaks in the two detector-produced spectra can be integrated simultaneously, and any scan can be viewed during data acquisition. For active scanning, the 2615-keV gamma-ray line from a 232 U source and the 4439-keV gamma-ray line from 9 Be(α,n) 12 C were selected. The system can be easily reconfigured to accommodate up to seven detectors because it is based on CAMAC modules and FORTRAN. The system is designed for field use and is easily transported. Examples of passive and active scans are presented

  9. Gamma-ray imaging spectrometer (GRIS): a new balloon-borne experiment for gamma-ray line astronomy

    International Nuclear Information System (INIS)

    Teegarden, B.J.; Cline, T.L.; Gehrels, N.; Porreca, G.; Tueller, J.; Leventhal, M.; Huters, A.F.; MacCallum, C.J.; Stang, P.D.

    1985-01-01

    High resolution gamma-ray spectroscopy is a relatively new field that holds great promise for further understanding of high energy astrophysical processes. Preliminary results such as the annihilation radiation from the galactic center, the 26 Al line from the galactic plane and cyclotron lines from neutron stars may well be just the initial discoveries of a rich and as yet undeveloped field. When the high resolution gamma-ray spectrometer (GRSE) was removed from the GRO payload NASA decided to initiate a balloon program to permit continued development and improvement of instrumentation in this field, as well as continued scientific observations. The Gamma-Ray Imaging Spectrometer (GRIS) is one of the experiments selected as part of this program. The instrument contains a number of new and innovative features that are expected to produce a significant improvement in source location accuracy and sensitivity over previous balloon and satellite experiments. 6 refs., 2 figs

  10. Observing with a space-borne gamma-ray telescope: selected results from INTEGRAL

    International Nuclear Information System (INIS)

    Schanne, Stephane

    2006-01-01

    The International Gamma-Ray Astrophysics Laboratory, i.e. the INTEGRAL satellite of ESA, in orbit since about 3 years, performs gamma-ray observations of the sky in the 15 keV to 8 MeV energy range. Thanks to its imager IBIS, and in particular the ISGRI detection plane based on 16384 CdTe pixels, it achieves an excellent angular resolution (12 arcmin) for point source studies with good continuum spectrum sensitivity. Thanks to its spectrometer SPI, based on 19 germanium detectors maintained at 85 K by a cryogenic system, located inside an active BGO veto shield, it achieves excellent spectral resolution of about 2 keV for 1 MeV photons, which permits astrophysical gamma-ray line studies with good narrow-line sensitivity. In this paper we review some goals of gamma-ray astronomy from space and present the INTEGRAL satellite, in particular its instruments ISGRI and SPI. Ground and in-flight calibration results from SPI are presented, before presenting some selected astrophysical results from INTEGRAL. In particular results on point source searches are presented, followed by results on nuclear astrophysics, exemplified by the study of the 1809 keV gamma-ray line from radioactive 26 Al nuclei produced by the ongoing stellar nucleosynthesis in the Galaxy. Finally a review on the study of the positron-electron annihilation in the Galactic center region, producing 511 keV gamma-rays, is presented

  11. 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. Understanding the basic physics of how gamma rays interact with matter can clarify how certain features in a spectrum were produced.

  12. Nuclear transfer reaction measurements at the ESR-for the investigation of the astrophysical O-15(alpha,gamma)Ne-19 reaction

    NARCIS (Netherlands)

    Doherty, D. T.; Woods, P. J.; Litvinov, Yu A.; Najafi, M. Ali; Bagchi, S.; Bishop, S.; Bo, M.; Brandau, C.; Davinson, T.; Dillmann, I.; Estrade, A.; Egelhof, P.; Evdokimov, A.; Gumberidze, A.; Heil, M.; Lederer, C.; Litvinov, S. A.; Lotay, G.; Kalantar-Nayestanaki, N.; Kiselev, O.; Kozhuharov, C.; Kroell, T.; Mahjour-Shafei, M.; Mutterer, M.; Nolden, F.; Petridis, N.; Popp, U.; Reifarth, R.; Rigollet, C.; Roy, S.; Steck, M.; Stoehlker, Th; Streicher, B.; Trotsenko, S.; von Schmid, M.; Yan, X. L.; Zamora, J. C.

    Astrophysical x-ray bursts are thought to be a result of thermonuclear explosions on the atmosphere of an accreting neutron star. Between these bursts, energy is thought to be generated by the hot CNO cycles. The O-15(alpha,gamma)Ne-19 reaction is one reaction that allows breakout from these CNO

  13. Nuclear transfer reaction measurements at the ESR-for the investigation of the astrophysical O-15(alpha,gamma)Ne-19 reaction

    NARCIS (Netherlands)

    Doherty, D. T.; Woods, P. J.; Litvinov, Yu A.; Najafi, M. Ali; Bagchi, S.; Bishop, S.; Bo, M.; Brandau, C.; Davinson, T.; Dillmann, I.; Estrade, A.; Egelhof, P.; Evdokimov, A.; Gumberidze, A.; Heil, M.; Lederer, C.; Litvinov, S. A.; Lotay, G.; Kalantar-Nayestanaki, N.; Kiselev, O.; Kozhuharov, C.; Kroell, T.; Mahjour-Shafei, M.; Mutterer, M.; Nolden, F.; Petridis, N.; Popp, U.; Reifarth, R.; Rigollet, C.; Roy, S.; Steck, M.; Stoehlker, Th; Streicher, B.; Trotsenko, S.; von Schmid, M.; Yan, X. L.; Zamora, J. C.

    2015-01-01

    Astrophysical x-ray bursts are thought to be a result of thermonuclear explosions on the atmosphere of an accreting neutron star. Between these bursts, energy is thought to be generated by the hot CNO cycles. The O-15(alpha,gamma)Ne-19 reaction is one reaction that allows breakout from these CNO

  14. Gamma ray astronomy from satellites and balloons

    International Nuclear Information System (INIS)

    Schoenfelder, V.

    1986-01-01

    A survey is given of gamma ray astronomy topics presented at the Cosmic Ray Conference. The major conclusions at the Cosmic Ray Conference in the field of gamma ray astronomy are given. (1) MeV-emission of gamma-ray bursts is a common feature. Variations in duration and energy spectra from burst to burst may explain the discrepancy between the measured log N - log S dependence and the observed isotropy of bursts. (2) The gamma-ray line at 1.809 MeV from Al(26) is the first detected line from a radioactive nucleosynthesis product. In order to understand its origin it will be necessary to measure its longitude distribution in the Milky Way. (3) The indications of a gamma-ray excess found from the direction of Loop I is consistent with the picture that the bulk of cosmic rays below 100 GeV is produced in galactic supernova remnants. (4) The interpretation of the large scale distribution of gamma rays in the Milky Way is controversial. At present an extragalactic origin of the cosmic ray nuclei in the GeV-range cannot be excluded from the gamma ray data. (5) The detection of MeV-emission from Cen A is a promising step towards the interesting field of extragalactic gamma ray astronomy

  15. Astrophysical extended X-ray absorption fine-structure analysis

    International Nuclear Information System (INIS)

    Woo, J.W.; Forrey, R.C.; Cho, K.; Department of Physics and Division of Applied Sciences, Harvard University)

    1997-01-01

    We present an astrophysical extended X-ray absorption fine-structure (EXAFS) analysis (AEA) tool. The AEA tool is designed to generate a numerical model of the modification to the X-ray absorption coefficient due to the EXAFS phenomenon. We have constructed a complete database (elements up to the atomic number 92) of EXAFS parameters: central atom phase shift (2δ 1 ), backscattering phase shift (φ b ), and backscattering amplitude (F). Using the EXAFS parameter data base, the AEA tool can generate a numerical model of any compound when the atomic numbers of neighboring atoms and their distances to the central X-ray-absorbing atom are given. copyright 1997 The American Astronomical Society

  16. Gamma-ray burst polarimeter (GAP)

    International Nuclear Information System (INIS)

    Mihara, Tatehiro; Murakami, Toshio; Yonetoku, Daisuke; Gunji, Shuichi; Kubo, Shin

    2013-01-01

    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.)

  17. Studies of weak capture-gamma-ray resonances via coincidence techniques

    CERN Document Server

    Rowland, C; Champagne, A E; Dummer, A K; Fitzgerald, R; Harley, E C T; Mosher, J; Runkle, R

    2002-01-01

    A method for measuring weak capture-gamma-ray resonances via gamma gamma-coincidence counting techniques is described. The coincidence apparatus consisted of a large-volume germanium detector and an annular NaI(Tl) crystal. The setup was tested by measuring the weak E sub R =227 keV resonance in sup 2 sup 6 Mg(p,gamma) sup 2 sup 7 Al. Absolute germanium and NaI(Tl) counting efficiencies for a range of gamma-ray energies and for different detector-target geometries are presented. Studies of the gamma-ray background in our spectra are described. Compared to previous work, our method improves the detection sensitivity for weak capture-gamma-ray resonances by a factor of approx 100. The usefulness of the present technique for investigations of interest to nuclear astrophysics is discussed.

  18. INTEGRAL Upper Limits on Gamma-Ray Emission Associated with the Gravitational Wave Event GW150914

    DEFF Research Database (Denmark)

    Savchenko, V.; Ferrigno, C.; Mereghetti, S.

    2016-01-01

    Using observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), we place upper limits on the gamma-ray and hard X-ray prompt emission associated with the gravitational wave event GW150914, which was discovered by the LIGO/Virgo Collaboration. The omnidirectional view...... in the 75 keV-2 MeV energy range for typical spectral models. Our results constrain the ratio of the energy promptly released in gamma-rays in the direction of the observer to the gravitational wave energy Eγ/EGW ... of the gravitational wave source, based on the available predictions for prompt electromagnetic emission....

  19. INTEGRAL Upper Limits on Gamma-Ray Emission Associated with the Gravitational Wave Event GW150914

    DEFF Research Database (Denmark)

    Savchenko, V.; Ferrigno, C.; Natalucci, L.

    Using observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), we place upper limits on the gamma-ray and hard X-ray prompt emission associated with the gravitational wave event GW150914, discovered by the LIGO/Virgo Collaboration. The omnidirectional view of the INTEGRAL...... MeV energy range for typical spectral models. Our results constrain the ratio of the energy promptly released in gamma-rays in the direction of the observer to the gravitational wave energy Eγ/EGW gravitational wave...

  20. Radio Observations of Gamma-ray Novae

    Science.gov (United States)

    Linford, Justin D.; Chomiuk, L.; Ribeiro, V.; project, E.-Nova

    2014-01-01

    Recent detection of gamma-ray emission from classical novae by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope surprised many in the astronomical community. We present results from radio observations, obtained using the Karl G. Jansky Very Large Array (VLA), of three gamma-ray novae: Mon2012, Sco2012, and Del2013. Radio observations allow for the calculation of ejecta masses, place limits on the distances, and provide information about the gamma-ray emission mechanism for these sources.

  1. X-ray and gamma radiography devices

    International Nuclear Information System (INIS)

    Abdul Nassir Ibrahim; Azali Muhammad; Ab. Razak Hamzah; Abd. Aziz Mohamed; Mohamad Pauzi Ismail

    2008-01-01

    When we are using this technique, we also must familiar with the device and instrument that used such as gamma projector, crawler, x-ray tubes and others. So this chapter discussed detailed on device used for radiography work. For the x-ray and gamma, their characteristics are same but the source to produce is a big different. X-ray produced from the machine meanwhile, gamma produce from the source such as Co-60 and IR-192. Both are electromagnetic waves. So, the reader can have some knowledge on what is x-ray tube, discrete x-ray and characteristic x-ray, how the machine works and how to control a machine, what is source for gamma emitter, how to handle the projector and lastly difference between x-ray and gamma. Of course this cannot be with the theory only, so detailed must be learned practically.

  2. Gamma-ray burst models.

    Science.gov (United States)

    King, Andrew

    2007-05-15

    I consider various possibilities for making gamma-ray bursts, particularly from close binaries. In addition to the much-studied neutron star+neutron star and black hole+neutron star cases usually considered good candidates for short-duration bursts, there are also other possibilities. In particular, neutron star+massive white dwarf has several desirable features. These systems are likely to produce long-duration gamma-ray bursts (GRBs), in some cases definitely without an accompanying supernova, as observed recently. This class of burst would have a strong correlation with star formation and occur close to the host galaxy. However, rare members of the class need not be near star-forming regions and could have any type of host galaxy. Thus, a long-duration burst far from any star-forming region would also be a signature of this class. Estimates based on the existence of a known progenitor suggest that this type of GRB may be quite common, in agreement with the fact that the absence of a supernova can only be established in nearby bursts.

  3. Gamma ray emission from pulsars

    International Nuclear Information System (INIS)

    Salvati, M.; Massaro, E.

    1978-01-01

    A model for the production of gamma rays in a pulsar environment is presented, together with numerical computations fitted to the observations of PSR 0833-45. It is assumed that the primary particles are accelerated close to the star surface and then injected along the open field lines, which cause them to emit curvature radiation. The equation describing the particles' braking is integrated exactly up to the first order in the pulsar rotational frequency, and the transfer problem for the curvature photons is solved with the aberration, the Doppler shif, and the pair production absorption being taken into account. The latter effect is due not only to the transverse component of the magnetic field, but also to the electric field induced by the rotation. The synchrotron radiation emitted by the secondary particles is also included, subject to the 'on-the-spot' approximation. It is found that the observed gamma rays originate in the innermost regions of the magnetosphere, where the open lines' bundle is narrow and the geometrical beaming is effective. As shown by the computed pulse profiles, the duty cycle turns out to be equal to a few percent, comparable to the one of PSR 0833-45. The averaged spectra indicate that a substantial fraction of the primary photons do outlive the interaction with the magnetisphere; furthermore, the agreement in shape with the observational curves suggests that the acceleration output is fiarly close to a monoenergetic beam of particles. (orig.) [de

  4. Dark gamma-ray bursts

    Science.gov (United States)

    Brdar, Vedran; Kopp, Joachim; Liu, Jia

    2017-03-01

    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 burst results in a flash of gamma rays accompanying the supernova. For a galactic supernova, this "dark gamma-ray burst" may be observable in the Čerenkov Telescope Array.

  5. The Fermi Gamma-Ray Space Telescope, Exploding Stars, Neutron Stars, and Black Holes

    Science.gov (United States)

    Thompson, David J.

    2010-01-01

    Since August, 2008, the Fermi Gamma-ray Space Telescope has been scanning the sky, producing a full-sky image every three hours. These cosmic gamma-rays come from extreme astrophysical phenomena, many related to exploding stars (supernovae) or what these explosions leave behind: supernova remnants, neutron stars, and black holes. This talk uses sample Fermi results, plus simple demonstrations, to illustrate the exotic properties of these endpoints of stellar evolution.

  6. 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.

  7. X-ray echoes from gamma-ray bursts

    International Nuclear Information System (INIS)

    Dermer, C.D.; Hurley, K.C.; Hartmann, D.H.

    1991-01-01

    The identification of an echo of reflected radiation in time histories of gamma-ray burst spectra can provide important information about the existence of binary companions or accretion disks in gamma-ray burst systems. Because of the nature of Compton scattering, the spectrum of the echo will be attenuated at gamma-ray energies compared with the spectrum of the primary burst emission. The expected temporal and spectral signatures of the echo and a search for such echoes are described, and implications for gamma-ray burst models are discussed. 35 refs

  8. Processing of gamma-ray spectrometric logs

    International Nuclear Information System (INIS)

    Umiastowski, K.; Dumesnil, P.

    1984-10-01

    CEA (Commissariat a l'Energie Atomique) has developped a gamma-ray spectrometric tool, containing an analog-to-digital converter. This new tool permits to perform very precise uranium logs (natural gamma-ray spectrometry), neutron activation logs and litho-density logs (gamma-gamma spectrometric logs). Specific processing methods were developped to treate the particular problems of down-hole gamma-ray spectrometry. Extraction of the characteristic gamma-ray peak, even if they are superposed on the background radiation of very high intensity, is possible. This processing methode enables also to obtain geological informations contained in the continuous background of the spectrum. Computer programs are written in high level language for SIRIUS (VICTOR) and APOLLO computers. Exemples of uranium and neutron activation logs treatment are presented [fr

  9. 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...

  10. 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.

  11. Prompt gamma-ray activation analysis (PGAA)

    International Nuclear Information System (INIS)

    Kern, J.

    1996-01-01

    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

  12. A high energy gamma ray astronomy experiment

    International Nuclear Information System (INIS)

    Hofstadter, R.

    1988-01-01

    The author describes work involving NASA's Gamma Ray Observatory (GRO). GRO exemplifies the near zero principle because it investigates new gamma ray phenomena by relying on the space program to take us into the region of zero interference above the earth's atmosphere. In its present form GRO has four experiments

  13. Intercomparison of gamma ray analysis software packages

    International Nuclear Information System (INIS)

    1998-04-01

    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

  14. Very high-energy gamma rays from gamma-ray bursts.

    Science.gov (United States)

    Chadwick, Paula M

    2007-05-15

    Very high-energy (VHE) gamma-ray astronomy has undergone a transformation in the last few years, with telescopes of unprecedented sensitivity having greatly expanded the source catalogue. Such progress makes the detection of a gamma-ray burst at the highest energies much more likely than previously. This paper describes the facilities currently operating and their chances for detecting gamma-ray bursts, and reviews predictions for VHE gamma-ray emission from gamma-ray bursts. Results to date are summarized.

  15. Observations of the highest energy gamma-rays from gamma-ray bursts

    International Nuclear Information System (INIS)

    Dingus, Brenda L.

    2001-01-01

    EGRET has extended the highest energy observations of gamma-ray bursts to GeV gamma rays. Such high energies imply the fireball that is radiating the gamma-rays has a bulk Lorentz factor of several hundred. However, EGRET only detected a few gamma-ray bursts. GLAST will likely detect several hundred bursts and may extend the maximum energy to a few 100 GeV. Meanwhile new ground based detectors with sensitivity to gamma-ray bursts are beginning operation, and one recently reported evidence for TeV emission from a burst

  16. Gamma ray astronomy with COS-B

    International Nuclear Information System (INIS)

    Swanenburg, B.N.

    1981-01-01

    Observational results in the field of gamma-ray astronomy that have been obtained to date with the COS-B satellite are discussed and questions raised by these observations are summarized. Following a brief review of the instrumental characteristics of COS-B and the extent of COS-B gamma-ray coverage of the sky, particular attention is given to the questions raised by the discovery of many unidentified gamma-ray sources with no apparent optical, X-ray or radio counterparts and the detection of high-energy gamma radiation from the quasar 3C 273, which suggests the role of gamma-ray emission in the creation of other radiation

  17. Gamma-ray astronomy and cosmic-ray origin theory

    International Nuclear Information System (INIS)

    Ginzburg, V.L.

    1973-01-01

    A theory of the origin of cosmic radiation is discussed in light of the advances made in gamma-ray astronomy. Arguments against metagalactic models for the origin of cosmic rays are emphasized. (U.S.)

  18. Fermi-LAT Observations of the Gamma-Ray Burst GRB 130427A

    Science.gov (United States)

    Ackermann, M.; Ajello, M.; Asano, K.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; hide

    2013-01-01

    The observations of the exceptionally bright gamma-ray burst (GRB) 130427A by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope provide constraints on the nature of these unique astrophysical sources. GRB 130427A had the largest fluence, highest-energy photon (95 GeV), longest gamma-ray duration (20 hours), and one of the largest isotropic energy releases ever observed from a GRB. Temporal and spectral analyses of GRB 130427A challenge the widely accepted model that the nonthermal high-energy emission in the afterglow phase of GRBs is synchrotron emission radiated by electrons accelerated at an external shock.

  19. Science with the Advanced Gamma Ray Imaging System (AGIS)

    Science.gov (United States)

    Coppi, Paolo

    2009-05-01

    We present the scientific drivers for the Advanced Gamma Ray Imaging System (AGIS), a concept for the next-generation ground- based gamma-ray experiment, comprised of an array of ˜100 imaging atmospheric Cherenkov telescopes. Design requirements for AGIS include achieving a sensitivity an order of magnitude better than the current generation of space or ground-based instruments in the energy range of 40 GeV to ˜100 TeV. We present here an overview of the scientific goals of AGIS, including the prospects for understanding VHE phenomena in the vicinity of accreting black holes, particle acceleration in a variety of astrophysical environments, indirect detection of dark matter, study of cosmological background radiation fields, and particle physics beyond the standard model.

  20. Light speed variation from gamma ray burst GRB 160509A

    Directory of Open Access Journals (Sweden)

    Haowei Xu

    2016-09-01

    Full Text Available It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers. However, the effect of quantum gravity could bring an energy dependence of light speed. Even a tiny speed variation, when amplified by the cosmological distance, may be revealed by the observed time lags between photons with different energies from astrophysical sources. From the newly detected long gamma ray burst GRB 160509A, we find evidence to support the prediction for a linear form modification of light speed in cosmological space.

  1. Light speed variation from gamma ray burst GRB 160509A

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Haowei [School of Physics, State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Ma, Bo-Qiang, E-mail: mabq@pku.edu.cn [School of Physics, State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Center for High Energy Physics, Peking University, Beijing 100871 (China); Center for History and Philosophy of Science, Peking University, Beijing 100871 (China)

    2016-09-10

    It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers. However, the effect of quantum gravity could bring an energy dependence of light speed. Even a tiny speed variation, when amplified by the cosmological distance, may be revealed by the observed time lags between photons with different energies from astrophysical sources. From the newly detected long gamma ray burst GRB 160509A, we find evidence to support the prediction for a linear form modification of light speed in cosmological space.

  2. Gamma-ray lines from radiative dark matter decay

    International Nuclear Information System (INIS)

    Garny, Mathias; Ibarra, Alejandro; Tran, David; Weniger, Christoph

    2011-01-01

    The decay of dark matter particles which are coupled predominantly to charged leptons has been proposed as a possible origin of excess high-energy positrons and electrons observed by cosmic-ray telescopes PAMELA and Fermi LAT. Even though the dark matter itself is electrically neutral, the tree-level decay of dark matter into charged lepton pairs will generically induce radiative two-body decays of dark matter at the quantum level. Using an effective theory of leptophilic dark matter decay, we calculate the rates of radiative two-body decays for scalar and fermionic dark matter particles. Due to the absence of astrophysical sources of monochromatic gamma rays, the observation of a line in the diffuse gamma-ray spectrum would constitute a strong indication of a particle physics origin of these photons. We estimate the intensity of the gamma-ray line that may be present in the energy range of a few TeV if the dark matter decay interpretation of the leptonic cosmic-ray anomalies is correct and comment on observational prospects of present and future Imaging Cherenkov Telescopes, in particular the CTA

  3. Neutron detection gamma ray sensitivity criteria

    International Nuclear Information System (INIS)

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Mace, Emily K.; Stephens, Daniel L.; Woodring, Mitchell L.

    2011-01-01

    The shortage of 3 He has triggered the search for effective alternative neutron detection technologies for national security and safeguards applications. Any new detection technology must satisfy two basic criteria: (1) it must meet a neutron detection efficiency requirement, and (2) it must be insensitive to gamma-ray interference at a prescribed level, while still meeting the neutron detection requirement. It is the purpose of this paper to define measureable gamma ray sensitivity criteria for neutron detectors. Quantitative requirements are specified for: intrinsic gamma ray detection efficiency and gamma ray absolute rejection. The gamma absolute rejection ratio for neutrons (GARRn) is defined, and it is proposed that the requirement for neutron detection be 0.9 3 He based neutron detector is provided showing that this technology can meet the stated requirements. Results from tests of some alternative technologies are also reported.

  4. The Polarimeter for Relativistic Astrophysical X-ray Sources

    Science.gov (United States)

    Jahoda, Keith; Kallman, Timothy R.; Kouveliotou, Chryssa; Angelini, Lorella; Black, J. Kevin; Hill, Joanne E.; Jaeger, Theodore; Kaaret, Philip E.; Markwardt, Craig B.; Okajima, Takashi; Petre, Robert; Schnittman, Jeremy; Soong, Yang; Strohmayer, Tod E.; Tamagawa, Toru; Tawara, Yuzuru

    2016-07-01

    The Polarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) is one of three Small Explorer (SMEX) missions selected by NASA for Phase A study, with a launch date in 2020. The PRAXyS Observatory exploits grazing incidence X-ray mirrors and Time Projection Chamber Polarimeters capable of measuring the linear polarization of cosmic X-ray sources in the 2-10 keV band. PRAXyS combines well-characterized instruments with spacecraft rotation to ensure low systematic errors. The PRAXyS payload is developed at the Goddard Space Flight Center with the Johns Hopkins University Applied Physics Laboratory, University of Iowa, and RIKEN (JAXA) collaborating on the Polarimeter Assembly. The LEOStar-2 spacecraft bus is developed by Orbital ATK, which also supplies the extendable optical bench that enables the Observatory to be compatible with a Pegasus class launch vehicle. A nine month primary mission will provide sensitive observations of multiple black hole and neutron star sources, where theory predicts polarization is a strong diagnostic, as well as exploratory observations of other high energy sources. The primary mission data will be released to the community rapidly and a Guest Observer extended mission will be vigorously proposed.

  5. Gamma-Ray Pulsar Studies With GLAST

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, D.J.; /NASA, Goddard

    2011-11-23

    Some pulsars have their maximum observable energy output in the gamma-ray band, offering the possibility of using these high-energy photons as probes of the particle acceleration and interaction processes in pulsar magnetospheres. After an extended hiatus between satellite missions, the recently-launched AGILE mission and the upcoming Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) will allow gamma-ray tests of the theoretical models developed based on past discoveries. With its greatly improved sensitivity, better angular resolution, and larger energy reach than older instruments, GLAST LAT should detect dozens to hundreds of new gamma-ray pulsars and measure luminosities, light curves, and phase-resolved spectra with unprecedented resolution. It will also have the potential to find radio-quiet pulsars like Geminga, using blind search techniques. Cooperation with radio and X-ray pulsar astronomers is an important aspect of the LAT team's planning for pulsar studies.

  6. Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth

    OpenAIRE

    Abeysekara, A. U.; Albert, A.; Alfaro, R.; Alvarez, C.; Álvarez, J. D.; Arceo, R.; Arteaga-Velázquez, J. C.; Rojas, D. Avila; Solares, H. A. Ayala; Barber, A. S.; Bautista-Elivar, N.; Becerril, A.; Belmont-Moreno, E.; BenZvi, S. Y.; Berley, D.

    2017-01-01

    The unexpectedly high flux of cosmic ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the HighAltitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of ac...

  7. Gamma-Ray, Cosmic Ray and Neutrino Tests of Lorentz Invariance and Quantum Gravity Models

    Science.gov (United States)

    Stecker, Floyd

    2011-01-01

    High-energy astrophysics observations provide the best possibilities to detect a very small violation of Lorentz invariance such as may be related to the structure of space-time near the Planck scale of approximately 10(exp -35) m. I will discuss here the possible signatures of Lorentz invariance violation (LIV) from observations of the spectra, polarization, and timing of gamma-rays from active galactic nuclei and gamma-ray bursts. Other sensitive tests are provided by observations of the spectra of ultrahigh energy cosmic rays and neutrinos. Using the latest data from the Pierre Auger Observatory one can already derive an upper limit of 4.5 x 10(exp -23) to the amount of LIV of at a proton Lorentz factor of approximately 2 x 10(exp 11). This result has fundamental implications for quantum gravity models. I will also discuss the possibilities of using more sensitive space based detection techniques to improve searches for LIV in the future.

  8. Development of a low-level setup for gamma spectroscopy: Application for nuclear astrophysics using reverse kinematics

    International Nuclear Information System (INIS)

    Genard, G.; Nuttens, V.E.; Bouchat, V.; Terwagne, G.

    2010-01-01

    It is more and more necessary to improve the sensitivity of gamma-ray spectroscopy systems, especially in nuclear astrophysics. In the case of radiative proton capture reactions, one means is to avoid the reactions on the target impurities by using reverse kinematics. This technique is possible with the LARN accelerator and can provide very clean cross-section measurements. For that purpose, a hydrogen standard has been carried out by means of ion implantation in silicon. In addition, a low-level setup has been put in place on a new beam line of the accelerator. A high efficiency and high resolution germanium detector is used conjointly with a double shielding. A passive lead castle shielding system is used to reduce the natural radioactivity and an active shielding consisting of an anti-cosmic veto is provided by an anticoincidence between the plastic scintillator and the gamma-ray detector. The setup allows a reduction of 70% of the background interference and provides an approximately 200 fold sensitivity gain of between 600 and 3000 keV. Some other developments have also been carried out to optimize the setup. The entire setup and the reverse kinematics have been validated by measuring the cross-section of the 13 C(p,γ) 14 N and 15 N(p,γ) 16 O reactions that present some astrophysical interest.

  9. X-Ray-Driven Gamma Emission

    International Nuclear Information System (INIS)

    Carroll, J. J.; Karamian, S. A.; Rivlin, L. A.; Zadernovsky, A. A.

    2001-01-01

    X-ray-driven gamma emission describes processes that may release nuclear energy in a 'clean' way, as bursts of incoherent or coherent gamma rays without the production of radioactive by-products. Over the past decade, studies in this area, as a part of the larger field of quantum nucleonics, have gained tremendous momentum. Since 1987 it has been established that photons could trigger gamma emission from a long-lived metastable nuclear excited state of one nuclide and it appears likely that triggering in other isotopes will be demonstrated conclusively in the near future. With these experimental results have come new proposals for the creation of collective and avalanche-like incoherent gamma-ray bursts and even for the ultimate light source, a gamma-ray laser. Obviously, many applications would benefit from controlled bursts of gamma radiation, whether coherent or not. This paper reviews the experimental results and concepts for the production of gamma rays, driven by externally produced X-rays

  10. EDGE: explorer of diffuse emission and gamma-ray burst explosions

    NARCIS (Netherlands)

    den Herder, J.W.; Piro, L.; Ohashi, T.; Amati, L.; Atteia, J.; Barthelmy, S.D.; Barbera, M.; Barret, D.; Basso, S.; de Boer, M.; Borgani, S.; Boyarskiy, O.; Branchini, E.; Branduardi-Raymont, G.; Briggs, M.; Brunetti, G.; Budtz-Jorgensenf, C.; Burrows, D.N.; Campana, S.; Caroli, E.; Chincarini, G.; Christensen, F.; Cocchi, M.; Comastri, A.; Corsi, A.; Cotroneo, V.; Conconi, P.; Colasanti, L.; Cusamano, G.; Rosa, A.; Del Santo, M.; Ettori, S.; Ezoe, Y.; Ferrari, L.; Feroci, M.; Finger, M.; Fishman, G.; Fujimoto, R.; Galeazzi, M.; Galli, A.; Gatti, F.; Gehrels, N.; Gendre, B.; Ghirlanda, G.; Ghisellini, G.; Giommi, P.; Girardi, M.; Guzzo, L.; Haardt, F.; Hepburn, I.; Hermsen, W.; Hoevers, H.; Holland, A.; in 't Zand, J.J.M.; Ishisaki, Y.; Kawahara, H.; Kawai, N.; Kaastra, J.; Kippen, M.; de Korte, P.A.J.; Kouveliotou, C.; Kusenko, A.; Labanti, C.; Lieu, R.; Macculi, C.; Makishima, K.; Matt, G.; Mazotta, P.; McCammon, D.; Méndez, M.; Mineo, T.; Mitchell, S.; Mitsuda, K.; Molendi, S.; Moscardini, L.; Mushotzky, R.; Natalucci, L.; Nicastro, F.; O'Brien, P.; Osborne, J.; Paerels, F.; Page, M.; Paltani, S.; Pareschi, G.; Perinati, E.; Perola, C.; Ponman, T.; Rasmussen, A.; Roncarelli, M.; Rosati, P.; Ruchayskiy, O.; Quadrini, E.; Sakurai, I.; Salvaterra, R.; Sasaki, S.; Wijers, R.; et al., [Unknown

    2007-01-01

    How structures of various scales formed and evolved from the early Universe up to present time is a fundamental question of astrophysics. EDGE will trace the cosmic history of the baryons from the early generations of massive stars by Gamma-Ray Burst (GRB) explosions, through the period of galaxy

  11. Librarian driven analysis of gamma ray spectra

    International Nuclear Information System (INIS)

    Kondrashov, V.; Petersone, I.

    2002-01-01

    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)

  12. The agile alert system for gamma-ray transients

    International Nuclear Information System (INIS)

    Bulgarelli, A.; Trifoglio, M.; Gianotti, F.; Fioretti, V.; Tavani, M.; Argan, A.; Trois, A.; Scalise, E.; Parmiggiani, N.; Beneventano, D.; Chen, A. W.; Vercellone, S.; Pittori, C.; Verrecchia, F.; Lucarelli, F.; Santolamazza, P.; Fanari, G.; Giommi, P.; Longo, F.; Pellizzoni, A.

    2014-01-01

    In recent years, a new generation of space missions has offered great opportunities for discovery in high-energy astrophysics. In this article we focus on the scientific operations of the Gamma-Ray Imaging Detector (GRID) on board the AGILE space mission. AGILE-GRID, sensitive in the energy range of 30 MeV-30 GeV, has detected many γ-ray transients of both galactic and extragalactic origin. This work presents the AGILE innovative approach to fast γ-ray transient detection, which is a challenging task and a crucial part of the AGILE scientific program. The goals are to describe (1) the AGILE Gamma-Ray Alert System, (2) a new algorithm for blind search identification of transients within a short processing time, (3) the AGILE procedure for γ-ray transient alert management, and (4) the likelihood of ratio tests that are necessary to evaluate the post-trial statistical significance of the results. Special algorithms and an optimized sequence of tasks are necessary to reach our goal. Data are automatically analyzed at every orbital downlink by an alert pipeline operating on different timescales. As proper flux thresholds are exceeded, alerts are automatically generated and sent as SMS messages to cellular telephones, via e-mail, and via push notifications from an application for smartphones and tablets. These alerts are crosschecked with the results of two pipelines, and a manual analysis is performed. Being a small scientific-class mission, AGILE is characterized by optimization of both scientific analysis and ground-segment resources. The system is capable of generating alerts within two to three hours of a data downlink, an unprecedented reaction time in γ-ray astrophysics.

  13. The agile alert system for gamma-ray transients

    Energy Technology Data Exchange (ETDEWEB)

    Bulgarelli, A.; Trifoglio, M.; Gianotti, F.; Fioretti, V. [INAF/IASF-Bologna, Via Gobetti 101, I-40129 Bologna (Italy); Tavani, M.; Argan, A.; Trois, A.; Scalise, E. [INAF/IASF-Roma, Via del Fosso del Cavaliere 100, I-00133 Roma (Italy); Parmiggiani, N.; Beneventano, D. [University of Modena and Reggio Emilia, Dipartimento di Science e Metodi dell' Ingegneria (Italy); Chen, A. W. [INAF/IASF-Milano, Via E. Bassini 15, I-20133 Milano (Italy); Vercellone, S. [School of Physics, University of the Witwatersrand, Johannesburg Wits 2050 (South Africa); Pittori, C.; Verrecchia, F.; Lucarelli, F.; Santolamazza, P.; Fanari, G.; Giommi, P. [INAF/IASF-Palermo, Via U. La Malfa 153, I-90146 Palermo (Italy); Longo, F. [ASI-ASDC, Via G. Galilei, I-00044 Frascati (Roma) (Italy); Pellizzoni, A. [INFN Trieste, I-34127 Trieste (Italy); and others

    2014-01-20

    In recent years, a new generation of space missions has offered great opportunities for discovery in high-energy astrophysics. In this article we focus on the scientific operations of the Gamma-Ray Imaging Detector (GRID) on board the AGILE space mission. AGILE-GRID, sensitive in the energy range of 30 MeV-30 GeV, has detected many γ-ray transients of both galactic and extragalactic origin. This work presents the AGILE innovative approach to fast γ-ray transient detection, which is a challenging task and a crucial part of the AGILE scientific program. The goals are to describe (1) the AGILE Gamma-Ray Alert System, (2) a new algorithm for blind search identification of transients within a short processing time, (3) the AGILE procedure for γ-ray transient alert management, and (4) the likelihood of ratio tests that are necessary to evaluate the post-trial statistical significance of the results. Special algorithms and an optimized sequence of tasks are necessary to reach our goal. Data are automatically analyzed at every orbital downlink by an alert pipeline operating on different timescales. As proper flux thresholds are exceeded, alerts are automatically generated and sent as SMS messages to cellular telephones, via e-mail, and via push notifications from an application for smartphones and tablets. These alerts are crosschecked with the results of two pipelines, and a manual analysis is performed. Being a small scientific-class mission, AGILE is characterized by optimization of both scientific analysis and ground-segment resources. The system is capable of generating alerts within two to three hours of a data downlink, an unprecedented reaction time in γ-ray astrophysics.

  14. The AGILE Alert System for Gamma-Ray Transients

    Science.gov (United States)

    Bulgarelli, A.; Trifoglio, M.; Gianotti, F.; Tavani, M.; Parmiggiani, N.; Fioretti, V.; Chen, A. W.; Vercellone, S.; Pittori, C.; Verrecchia, F.; Lucarelli, F.; Santolamazza, P.; Fanari, G.; Giommi, P.; Beneventano, D.; Argan, A.; Trois, A.; Scalise, E.; Longo, F.; Pellizzoni, A.; Pucella, G.; Colafrancesco, S.; Conforti, V.; Tempesta, P.; Cerone, M.; Sabatini, P.; Annoni, G.; Valentini, G.; Salotti, L.

    2014-01-01

    In recent years, a new generation of space missions has offered great opportunities for discovery in high-energy astrophysics. In this article we focus on the scientific operations of the Gamma-Ray Imaging Detector (GRID) on board the AGILE space mission. AGILE-GRID, sensitive in the energy range of 30 MeV-30 GeV, has detected many γ-ray transients of both galactic and extragalactic origin. This work presents the AGILE innovative approach to fast γ-ray transient detection, which is a challenging task and a crucial part of the AGILE scientific program. The goals are to describe (1) the AGILE Gamma-Ray Alert System, (2) a new algorithm for blind search identification of transients within a short processing time, (3) the AGILE procedure for γ-ray transient alert management, and (4) the likelihood of ratio tests that are necessary to evaluate the post-trial statistical significance of the results. Special algorithms and an optimized sequence of tasks are necessary to reach our goal. Data are automatically analyzed at every orbital downlink by an alert pipeline operating on different timescales. As proper flux thresholds are exceeded, alerts are automatically generated and sent as SMS messages to cellular telephones, via e-mail, and via push notifications from an application for smartphones and tablets. These alerts are crosschecked with the results of two pipelines, and a manual analysis is performed. Being a small scientific-class mission, AGILE is characterized by optimization of both scientific analysis and ground-segment resources. The system is capable of generating alerts within two to three hours of a data downlink, an unprecedented reaction time in γ-ray astrophysics.

  15. Thermal neutron capture gamma-rays

    International Nuclear Information System (INIS)

    Tuli, J.K.

    1983-01-01

    The energy and intensity of gamma rays as seen in thermal neutron capture are presented. Only those (n,α), E = thermal, reactions for which the residual nucleus mass number is greater than or equal to 45 are included. These correspond to evaluations published in Nuclear Data Sheets. The publication source data are contained in the Evaluated Nuclear Structure Data File (ENSDF). The data presented here do not involve any additional evaluation. Appendix I lists all the residual nuclides for which the data are included here. Appendix II gives a cumulated index to A-chain evaluations including the year of publication. The capture gamma ray data are given in two tables - the Table 1 is the list of all gamma rays seen in (n,#betta#) reaction given in the order of increasing energy; the Table II lists the gamma rays according to the nuclide

  16. Gamma ray auto absorption correction evaluation methodology

    International Nuclear Information System (INIS)

    Gugiu, Daniela; Roth, Csaba; Ghinescu, Alecse

    2010-01-01

    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)

  17. Observations of gamma-ray bursts

    International Nuclear Information System (INIS)

    Strong, I.B.; Klebesadel, R.W.; Evans, W.D.

    1975-01-01

    Observational data on gamma-ray bursts are reviewed. Information is grouped into temporal properties, energy fluxes and spectral properties, and directions and distributions of the sources in space. (BJG)

  18. Possible galactic origin of. gamma. -ray bursts

    Energy Technology Data Exchange (ETDEWEB)

    Manchanda, R K; Ramsden, D [Southampton Univ. (UK). Dept. of Physics

    1977-03-31

    It is stated that extragalactic models for the origin of non-solar ..gamma..-ray bursts include supernova bursts in remote galaxies, and the collapse of the cores of active stars, whilst galactic models are based on flare stars, thermonuclear explosions in neutron stars and the sudden accretion of cometary gas on to neutron stars. The acceptability of any of these models may be tested by the observed size spectrum of the ..gamma..-ray bursts. The extragalactic models predict a power law spectrum with number index -1.5, whilst for the galactic models the number index will be -1. Experimental data on ..gamma..-ray bursts is, however, still meagre, and so far only 44 confirmed events have been recorded by satellite-borne instruments. The number spectrum of the observed ..gamma..-ray bursts indicates that the observed distribution for events with an energy < 10/sup -4/ erg/cm/sup 2/ is flat; this makes the choice of any model completely arbitrary. An analysis of the observed ..gamma..-ray events is here presented that suggests very interesting possibilities for their origin. There appears to be a preferred mean energy for ..gamma..-ray bursts; some 90% of the recorded events show a mean energy between 5 x 10/sup -5/ and 5 x 10/sup -4/ erg/cm/sup 2/, contrary to the predicted characteristics of the number spectrum of various models. A remarkable similarity is found between the distribution of ..gamma..-ray bursts and that of supernova remnants, suggesting a genetic relationship between the two and the galactic origin of the ..gamma..-ray bursts, and the burst source could be identified with completely run down neutron stars, formed during supernova explosions.

  19. Magic gamma rays, extra-atmospheric source

    International Nuclear Information System (INIS)

    Bolufer, P.

    2010-01-01

    Without the atmospheric layer, the cosmos radiation would kill every living, our planet would be like the moon. The cosmic gamma ray to collide with gases in land cover, as it is disintegrated. They are harmless, they form a cone of light that points to the cosmic source comes from. On April 25, 2009 was born on the island of Palma Magic II and Magic I the best observer of atmospheric gamma rays of low intensity. (Author)

  20. VHE Gamma-ray Supernova Remnants

    Energy Technology Data Exchange (ETDEWEB)

    Funk, Stefan; /KIPAC, Menlo Park

    2007-01-22

    Increasing observational evidence gathered especially in X-rays and {gamma}-rays during the course of the last few years support the notion that Supernova remnants (SNRs) are Galactic particle accelerators up to energies close to the ''knee'' in the energy spectrum of Cosmic rays. This review summarizes the current status of {gamma}-ray observations of SNRs. Shell-type as well as plerionic type SNRs are addressed and prospect for observations of these two source classes with the upcoming GLAST satellite in the energy regime above 100 MeV are given.

  1. Gamma-ray lasers or grasers

    International Nuclear Information System (INIS)

    Wilson, G.V.H.; George, E.P.; Hora, H.

    1976-01-01

    A method is described for controlling the emission and direction of gamma rays from excited nuclei contained in a sample source of suitable geometry having its major axis parallel to the proposed direction of gamma ray emission, comprising subjecting said sample source to thermal or dynamic polarization at temperatures approaching absolute zero in the presence of a strong magnetic field, and when a pulse of coherent gamma radiation is required along said major axis rotating the active nuclei through 90 0 by employing a short pulse of radio frequency oscillations in an auxilliary coil around the sample source

  2. Constraining decaying dark matter with Fermi LAT gamma-rays

    International Nuclear Information System (INIS)

    Zhang, Le; Sigl, Günter; Weniger, Christoph; Maccione, Luca; Redondo, Javier

    2010-01-01

    High energy electrons and positrons from decaying dark matter can produce a significant flux of gamma rays by inverse Compton off low energy photons in the interstellar radiation field. This possibility is inevitably related with the dark matter interpretation of the observed PAMELA and FERMI excesses. The aim of this paper is providing a simple and universal method to constrain dark matter models which produce electrons and positrons in their decay by using the Fermi LAT gamma-ray observations in the energy range between 0.5 GeV and 300 GeV. We provide a set of universal response functions that, once convolved with a specific dark matter model produce the desired constraints. Our response functions contain all the astrophysical inputs such as the electron propagation in the galaxy, the dark matter profile, the gamma-ray fluxes of known origin, and the Fermi LAT data. We study the uncertainties in the determination of the response functions and apply them to place constraints on some specific dark matter decay models that can well fit the positron and electron fluxes observed by PAMELA and Fermi LAT. To this end we also take into account prompt radiation from the dark matter decay. We find that with the available data decaying dark matter cannot be excluded as source of the PAMELA positron excess

  3. The Gamma-Ray Imager GRI

    Science.gov (United States)

    Wunderer, Cornelia B.; GRI Collaboration

    2008-03-01

    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 major science themes that are addressed in the gamma-ray regime. ESA's INTEGRAL observatory currently provides the astronomical community with a unique tool to investigate the sky up to MeV energies and hundreds of sources, new classes of objects, extraordinary views of antimatter annihilation in our Galaxy, and fingerprints of recent nucleosynthesis processes have been discovered. NASA's GLAST mission will similarly take the next step in surveying the high-energy ( GeV) sky, and NuSTAR will pioneer focusing observations at hard X-ray energies (to 80 keV). 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 Laue diffraction and multilayer-coated mirror techniques have paved the way towards a gamma-ray mission, providing major improvements compared to past missions regarding sensitivity and angular resolution. Such a future Gamma-Ray Imager will allow the study of particle acceleration processes and explosion physics in unprecedented detail, providing essential clues on the innermost nature of the most violent and most energetic processes in the Universe.

  4. Prompt Gamma Ray Spectroscopy for process monitoring

    International Nuclear Information System (INIS)

    Zoller, W.H.; Holmes, J.L.

    1991-01-01

    Prompt Gamma Ray Spectroscopy (PGRS) is a very powerful analytical technique able to measure many metallic, contamination problem elements. The technique involves measurement of gamma rays that are emitted by nuclei upon capturing a neutron. This method is sensitive not only to the target element but also to the particular isotope of that element. PGRS is capable of measuring dissolved metal ions in a flowing system. In the field, isotopic neutron sources are used to produce the desired neutron flux ( 252 Cf can produce neutron flux of the order of 10 8 neutrons/cm 2 --sec.). Due to high penetrating power of gamma radiation, high efficiency gamma ray detectors can be placed in an appropriate geometry to maximize sensitivity, providing real-time monitoring with low detection level capabilities

  5. Hot topics of X-ray Astrophysics from past and future missions

    International Nuclear Information System (INIS)

    Costa, Enrico

    2013-01-01

    50 years after the first discovery, X-ray Astrophysics is a well-established discipline, with a continuous development of detection/observation techniques. These can find application on both large observatories and thematic space missions. I will recall the main milestones of X-ray Astrophysics and review some of the hottest topics of High Energy Astrophysics, included some open problems of Fundamental Physics, that can be addressed with measurements in the X-ray band. I will show which proposed missions and which concepts of new missions could be more attractive for a future development of this discipline

  6. 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

  7. Gamma ray astronomy and the origin of galactic cosmic rays

    International Nuclear Information System (INIS)

    Gabici, Stefano

    2011-01-01

    Diffusive shock acceleration operating at expanding supernova remnant shells is by far the most popular model for the origin of galactic cosmic rays. Despite the general consensus received by the model, an unambiguous and conclusive proof of the supernova remnant hypothesis is still missing. In this context, the recent developments in gamma ray astronomy provide us with precious insights into the problem of the origin of galactic cosmic rays, since production of gamma rays is expected both during the acceleration of cosmic rays at supernova remnant shocks and during their subsequent propagation in the interstellar medium. In particular, the recent detection of a number of supernova remnants at TeV energies nicely fits with the model, but it still does not constitute a conclusive proof of it, mainly due to the difficulty of disentangling the hadronic and leptonic contributions to the observed gamma ray emission. The main goal of my research is to search for an unambiguous and conclusive observational test for proving (or disproving) the idea that supernova remnants are the sources of galactic cosmic rays with energies up to (at least) the cosmic ray knee. Our present comprehension of the mechanisms of particle acceleration at shocks and of the propagation of cosmic rays in turbulent magnetic fields encourages beliefs that such a conclusive test might come from future observations of supernova remnants and of the Galaxy in the almost unexplored domain of multi-TeV gamma rays. (author)

  8. Effects of Shielding on Gamma Rays

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-03-13

    The interaction of gamma rays with matter results in an effect we call attenuation (i.e. ‘shielding’). Attenuation can dramatically alter the appearance of a spectrum. Attenuating materials may actually create features in a spectrum via x-ray fluorescence

  9. Gamma rays from the interstellar medium

    International Nuclear Information System (INIS)

    Bloemen, J.B.G.M.

    1985-01-01

    This thesis describes new gamma-ray views on cosmic rays and the interstellar medium. The author describes the COS-B data base and the pre-launch and in-flight calibration data used for all analyses. Diffuse galactic gamma radiation (> 50 MeV) may be either a result of cosmic-ray-matter interactions, or of the cosmic-ray electrons with the interstellar radiation field (mainly at optical and infrared wavelengths), through the inverse-Compton process. A detailed comparison between the gamma-ray observations of the large complex of interstellar clouds in Orion and Monoceros and the CO and HI surveys of this region is given. It gives insight into the cloud penetration of cosmic rays and in the relation between CO detections and molecular hydrogen column densities. Next, the radial distribution of gamma rays in the Galaxy is studied, as well as the galactic centre (more precisely, the central 400 pc), which contains a large concentration of CO molecules. The H 2 /CO abundance and the cosmic-ray density in the galactic centre are discussed and compared to the findings for the galactic disk. In various analyses in this thesis a likelihood-ratio method is applied for parameter estimation and hypothesis testing. A general description of this method is added as an appendix. (Auth.)

  10. Magnetically-coupled microcalorimeter arrays for x-ray astrophysics

    Science.gov (United States)

    Bandler, Simon

    The "X-ray Surveyor" has been listed by NASA as one of the four major large mission concepts to be studied in the next Astrophysics Decadal Review in its preliminary list of large concepts. One of the key instruments on such a mission would be a very large format X-ray microcalorimeter array, with an array size of greater than 100 thousand pixels. Magnetically-coupled microcalorimeters (MCC) are one of the technologies with the greatest potential to meet the requirements of this mission, and this proposal is one to carry out research specifically to reach the goals of this vision. The "X-ray Surveyor" is a concept for a future mission that will make X-ray observations that are instrumental to understanding the quickly emerging population of galaxies and supermassive black holes at z ~10. The observations will trace the formation of galaxies and their assembly into large-scale structures starting from the earliest possible epochs. This mission would be observing baryons and large-scale physical processes outside of the very densest regions in the local Universe. This can be achieved with an X-ray observatory with similar angular resolution as Chandra but with significantly improved optic area and detector sensitivity. Chandra-scale angular resolution (1" or better) is essential in building more powerful, higher throughput observatories to avoid source confusion and remain photon-limited rather than background-limited. A prime consideration for the microcalorimeter camera on this type of mission is maintaining ~ 1 arcsec spatial resolution over the largest possible field of view, even if this means a slight trade-off against the spectral resolution. A uniform array of 1" pixels covering at least 5'x5' field of view is desired. To reduce the number of sensors read out, in geometries where extremely fine pitch (~50 microns) is desired, the most promising technologies are those in which a thermal sensor such an MCC can read out a sub-array of 20-25 individual 1'

  11. 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.

  12. Very high energy gamma-ray astronomy

    International Nuclear Information System (INIS)

    Weekes, T.C.

    1988-01-01

    Current interest in gamma-ray astronomy at energies above 100 GeV comes from the identification of Cygnus X-3 and other X-ray binaries as sources. In addition there are reports of emission from radio pulsars and a variety of other objects. The statistical significance of many of the observations is not high and many reported effects await confirmation, but there are a sufficient number of independent reports that very high energy gamma-ray astronomy must now be considered to have an observational basis. The observations are summarized with particular emphasis on those reported since 1980. The techniques used - the detection of small air showers using the secondary photons and particles at ground level - are unusual and are described. Future prospects for the field are discussed in relation to new ground-based experiments, satellite gamma-ray studies and proposed neutrino astronomy experiments. (orig.) With 296 refs

  13. Evaluation of gamma-ray intensities

    International Nuclear Information System (INIS)

    Yoshizawa, Yasukazu; Inoue, Hikaru; Hoshi, Masaharu; Shizuma, Kiyoshi; Iwata, Yosei.

    1980-04-01

    Relative intensities and intensities per decay of gamma rays were evaluated for 16 nuclides, 22 Na, 24 Na, 46 Sc, 54 Mn, 60 Co, 85 Sr, 88 Y, 95 Nb, sup(108m)Ag, 134 Cs, 133 Ba, 139 Ce, sup(180m)Hf, 198 Au, 203 Hg and 207 Bi. 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)

  14. Summary for astrophysics and non-accelerator physics

    International Nuclear Information System (INIS)

    Kahana, S.H.

    1988-01-01

    This paper summarizes the presentations at the astrophysics and non-accelerator physics conference. Discussed in this paper are: supernovae, neutrinos, x-rays, gamma rays, cosmic rays, monopoles and primordial nucleosynthesis. 15 refs

  15. Localization of Gamma-Ray Bursts Using the Fermi Gamma-Ray Burst Monitor

    NARCIS (Netherlands)

    Connaughton, V.; Briggs, M.S.; Goldstein, A.; Meegan, C.A.; Paciesas, W.S.; Preece, R.D.; Wilson-Hodge, C.A.; Gibby, M.H.; Greiner, J.; Gruber, D.; Jenke, P.; Kippen, R.M.; Pelassa, V.; Xiong, S.; Yu, H-F.; Bhat, P.N.; Burgess, J.M.; Byrne, D.; Fitzpatrick, G.; Foley, S.; Giles, M.M.; Guiriec, S.; van der Horst, A.J.; von Kienlin, A.; McBreen, S.; McGlynn, S.; Tierney, D.; Zhang, B..B.

    2015-01-01

    The Fermi Gamma-ray Burst Monitor (GBM) has detected over 1400 gamma-ray bursts (GRBs) since it began science operations in 2008 July. We use a subset of over 300 GRBs localized by instruments such as Swift, the Fermi Large Area Telescope, INTEGRAL, and MAXI, or through triangulations from the

  16. ESA's Integral detects closest cosmic gamma-ray burst

    Science.gov (United States)

    2004-08-01

    should emit similar amounts of gamma-ray energy. The fraction of it detected at Earth should then depend on the 'width' (opening angle) and orientation of the beam as well as on the distance. The energy received should be larger when the beam is narrow or points towards us and smaller when the beam is broad or points away from us. New data collected with ESA's high energy observatories, Integral and XMM-Newton, now show that this picture is not so clear-cut and that the amount of energy emitted by GRBs can vary significantly. "The idea that all GRBs spit out the same amount of gamma rays, or that they are 'standard candles' as we call them, is simply ruled out by the new data," said Dr Sergey Sazonov, from the Space Research Institute of the Russian Academy of Sciences, Moscow (Russia) and the Max-Planck Institute for Astrophysics, Garching near Munich (Germany). Sazonov and an international team of researchers studied the GRB detected by Integral on 3 December 2003 and given the code-name of GRB 031203. Within a record 18 seconds of the burst, the Integral Burst Alert System had pinpointed the approximate position of GRB 031203 in the sky and sent the information to a network of observatories around the world. A few hours later one of them, ESA's XMM-Newton, determined a much more precise position for GRB 031203 and detected a rapidly fading X-ray source, which was subsequently seen by radio and optical telescopes on the ground. This wealth of data allowed astronomers to determine that GRB 031203 went off in a galaxy less than 1300 million light years away, making it the closest GRB ever observed. Even so, the way in which GRB 031203 dimmed with time and the distribution of its energy were not different from those of distant GRBs. Then, scientists started to realise that the concept of the 'standard candle' may not hold. "Being so close should make GRB 031203 appear very bright, but the amount of gamma-rays measured by Integral is about one thousand times less than what

  17. Point source search techniques in ultra high energy gamma ray astronomy

    International Nuclear Information System (INIS)

    Alexandreas, D.E.; Biller, S.; Dion, G.M.; Lu, X.Q.; Yodh, G.B.; Berley, D.; Goodman, J.A.; Haines, T.J.; Hoffman, C.M.; Horch, E.; Sinnis, C.; Zhang, W.

    1993-01-01

    Searches for point astrophysical sources of ultra high energy (UHE) gamma rays are plagued by large numbers of background events from isotropic cosmic rays. Some of the methods that have been used to estimate the expected number of background events coming from the direction of a possible source are found to contain biases. Search techniques that avoid this problem are described. There is also a discussion of how to optimize the sensitivity of a search to emission from a point source. (orig.)

  18. High energy neutrinos from astrophysical accelerators of cosmic ray nuclei

    Science.gov (United States)

    Anchordoqui, Luis A.; Hooper, Dan; Sarkar, Subir; Taylor, Andrew M.

    2008-02-01

    Ongoing experimental efforts to detect cosmic sources of high energy neutrinos are guided by the expectation that astrophysical accelerators of cosmic ray protons would also generate neutrinos through interactions with ambient matter and/or photons. However, there will be a reduction in the predicted neutrino flux if cosmic ray sources accelerate not only protons but also significant numbers of heavier nuclei, as is indicated by recent air shower data. We consider plausible extragalactic sources such as active galactic nuclei, gamma ray bursts and starburst galaxies and demand consistency with the observed cosmic ray composition and energy spectrum at Earth after allowing for propagation through intergalactic radiation fields. This allows us to calculate the expected neutrino fluxes from the sources, normalized to the observed cosmic ray spectrum. We find that the likely signals are still within reach of next generation neutrino telescopes such as IceCube.PACS95.85.Ry98.70.Rz98.54.Cm98.54.EpReferencesFor a review, see:F.HalzenD.HooperRep. Prog. Phys.6520021025A.AchterbergIceCube CollaborationPhys. Rev. Lett.972006221101A.AchterbergIceCube CollaborationAstropart. Phys.262006282arXiv:astro-ph/0611063arXiv:astro-ph/0702265V.NiessANTARES CollaborationAIP Conf. Proc.8672006217I.KravchenkoPhys. Rev. D732006082002S.W.BarwickANITA CollaborationPhys. Rev. Lett.962006171101V.Van ElewyckPierre Auger CollaborationAIP Conf. Proc.8092006187For a survey of possible sources and event rates in km3 detectors see e.g.,W.BednarekG.F.BurgioT.MontaruliNew Astron. Rev.4920051M.D.KistlerJ.F.BeacomPhys. Rev. D742006063007A. Kappes, J. Hinton, C. Stegmann, F.A. Aharonian, arXiv:astro-ph/0607286.A.LevinsonE.WaxmanPhys. Rev. Lett.872001171101C.DistefanoD.GuettaE.WaxmanA.LevinsonAstrophys. J.5752002378F.A.AharonianL.A.AnchordoquiD.KhangulyanT.MontaruliJ. Phys. Conf. Ser.392006408J.Alvarez-MunizF.HalzenAstrophys. J.5762002L33F.VissaniAstropart. Phys.262006310F.W

  19. Swift: A gamma ray burst MIDEX

    International Nuclear Information System (INIS)

    Barthelmy, Scott

    2001-01-01

    Swift is a first of its kind multiwavelength transient observatory for gamma-ray burst astronomy. It has the optimum capabilities for the next breakthroughs in determining the origin of gamma-ray bursts and their afterglows as well as using bursts to probe the early Universe. Swift will also perform the first sensitive hard X-ray survey of the sky. The mission is being developed by an international collaboration and consists of three instruments, the Burst Alert Telescope (BAT), the X-ray Telescope (XRT), and the Ultraviolet and Optical Telescope (UVOT). The BAT, a wide-field gamma-ray detector, will detect ∼1 gamma-ray burst per day with a sensitivity 5 times that of BATSE. The sensitive narrow-field XRT and UVOT will be autonomously slewed to the burst location in 20 to 70 seconds to determine 0.3-5.0 arcsec positions and perform optical, UV, and X-ray spectrophotometry. On-board measurements of redshift will also be done for hundreds of bursts. Swift will incorporate superb, low-cost instruments using existing flight-spare hardware and designs. Strong education/public outreach and follow-up programs will help to engage the public and astronomical community. Swift has been selected by NASA for development and launch in late 2003

  20. gamma. -ray. Present status and problems

    Energy Technology Data Exchange (ETDEWEB)

    Okudaira, K [Rikkyo Univ., Tokyo (Japan). Faculty of Science

    1975-01-01

    As ..gamma..-ray advances straightly through space, the study on cosmic ..gamma..-ray will give the information concerning the origin directly. However, the intensity is weak, and the avoidance of background is a serious problem. The wide-spread components were studied by OSO-3. The intensity of the galactic disc component around 100 MeV was reported as (3.4+-1.0)x10/sup -5/ photons (cm/sup 2/, radian, sec)/sup -1/ by OSO-3 and 0.2x10/sup -4/ photons (cm/sup 2/, radian sec)/sup -1/ by SAS-2, and corresponds to the calculated ..gamma.. yield from ..pi../sup 0/. The strong disc component, so-called galactic center region, has been observed, and is due to the mixture of ..gamma..-ray from ..pi../sup 0/ and inverse Compton ..gamma..-ray. A peak at 476+-24 KeV was found as well as the continuous component. Special care must be taken for the observation of isotropic component, since it is hardly distinguished from the background. It is considered that the isotropic component is due to the inverse Compton scattering of 3/sup 0/K radiation in super-galactic space and the contribution from outer galaxy. The nearest point source of ..gamma..-ray is the sun. Among the other point sources, the crab nebula is the most reliable one. The energy flux of pulse component showed the spectrum of E/sup -1/. ..gamma..-ray bursts were observed by man-made satellites Vela-5 and 6. Theoretical explanation is still incomplete regarding the bursts. (Kato, T.).

  1. Nature of gamma-ray burst sources

    International Nuclear Information System (INIS)

    Ventura, J.

    1983-01-01

    Observational evidence suggests that gamma ray bursts have a local galactic origin involving neutron stars. In this light we make a critical review of physics of the thermonuclear runaway model placing emphasis on self-consistency. We further show that some of the proposed models can be observationally excluded in the light of existing data from the Einstein Observatory. The possibility of gamma bursts arising in low mass binaries is finally discussed in the light of evolutionary scenarios leading to low luminosity systems

  2. Gamma-ray Emission from Globular Clusters

    Directory of Open Access Journals (Sweden)

    Pak-Hin T. Tam

    2016-03-01

    Full Text Available 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.

  3. Fuzzy correlations of gamma-ray bursts

    International Nuclear Information System (INIS)

    Hartmann, D.H.; Linder, E.V.; Blumenthal, G.R.

    1991-01-01

    The origin of gamma-ray bursts is not known, both in the sense of the nature of the source emitting the radiation and literally, the position of the burst on the sky. Lacking unambiguously identified counterparts in any wavelength band studied to date, statistical approaches are required to determine the burster distance scale. Angular correlation analysis is one of the most powerful tools in this regard. However, poor detector resolution gives large localization errors, effectively beam smearing the positions. The resulting fuzzy angular correlation function is investigated and the generic isotropization that smearing induces on any intrinsic clustering is discussed. In particular, the extent to which gamma-ray burst observations by the BATSE detector aboard the Gamma-Ray Observatory might recover an intrinsic source correlation is investigated. 16 refs

  4. Gamma ray thermometrical facility for nuclear reactor

    International Nuclear Information System (INIS)

    Smith, R.D.; Regazzoni, Pierre.

    1981-01-01

    This invention concerns a gamma ray thermometer for nuclear reactors, fitted with a thermal bridge for use as a centring device. In accordance with the invention, an elastic device fills all the annular space between the gamma thermometer and the orifice through which the thermometer is introduced. This elastic device has the two-fold role of providing a thermal bridge at the gamma thermometer location suitable as a heat well, and of acting as a device for centring the thermometer in the orifice into which it has been introduced [fr

  5. A novel background reduction strategy for high level triggers and processing in gamma-ray Cherenkov detectors

    OpenAIRE

    Cabras, G.; De Angelis, A.; De Lotto, B.; De Maria, M. M.; De Sabata, F.; Mansutti, O.; Frailis, M.; Persic, M.; Bigongiari, C.; Doro, M.; Mariotti, M.; Peruzzo, L.; Saggion, A.; Scalzotto, V.; Paoletti, R.

    2008-01-01

    Gamma ray astronomy is now at the leading edge for studies related both to fundamental physics and astrophysics. The sensitivity of gamma detectors is limited by the huge amount of background, constituted by hadronic cosmic rays (typically two to three orders of magnitude more than the signal) and by the accidental background in the detectors. By using the information on the temporal evolution of the Cherenkov light, the background can be reduced. We will present here the results obtained wit...

  6. The Multi-Messenger Approach to High-Energy Gamma-Ray Sources

    CERN Document Server

    Paredes, Josep M; Torres, Diego F

    2008-01-01

    This book provides a theoretical and observational overview of the state of the art of gamma-ray astrophysics, and their impact and connection with the physics of cosmic rays and neutrinos. With the aim of shedding new and fresh light on the problem of the nature of the gamma-ray sources, particularly those yet unidentified, this book summarizes contributions to a workshop that continues with the series initiated by the meeting held at Tonantzintla in October 2000, and Hong-Kong in May 2004. This books will be of interest for all active researchers in the field of high energy astrophysics and astroparticle physics, as well as for graduate students entering into the subject.

  7. Claire: first light of a gamma-ray lens

    International Nuclear Information System (INIS)

    Halloin, H.

    2003-12-01

    At the high energy boundary of the observed electromagnetic spectrum, γ-ray astrophysics provides a unique probe to study the most energetic phenomena in the Universe. New γ-rays instruments have to be developed in order to reach the sensitivity and the angular resolution needed to compare theoretical predictions with observational data. γ-rays focusing appears now to be a promising way to overcome the actual issue. The CLAIRE project is dedicated to demonstrating the interest of a γ-ray lens for nuclear astrophysics, as well as measuring the performance of such an instrument and compare them to the theoretical predictions. According to the laws of γ-rays diffraction in crystal, the first lens for nuclear astrophysics has been developed. Due to mechanical and observational constraints, the energy bandwidth is a few keV broad and centered at 170 keV. The lens itself is made of about 560 germanium crystals, mounted on 8 concentric rings. The tuning of this lens in the laboratory has required the development of specific system and procedures. Besides, the data collected during this tuning has allowed the determination of various crystal characteristics, which have been used for numerical simulations of the γ-ray lens. Then, the gamma ray lens principle has also been tested by ground based measurements and by an observation of the Crab Nebula during a stratospheric flight. Ground based measurements, in the laboratory and with a source at a long distance, has allowed the determination of the diffraction efficiency as well as the angular response. These results, in agreement with the numerical expectations, demonstrate the validity of the γ-ray lens principles. Moreover, the CLAIRE gondola was launched in June 2001 and was recovered after about 5 hours and a half at an altitude of 41 km. Data analysis has led to a 3σ detection of the diffracted signal, corresponding to about 33 collected photons during an effective observation time of 1 h and 12 mn. The results

  8. Gamma-ray standards for detector calibration

    International Nuclear Information System (INIS)

    Lorenz, A.

    1985-10-01

    The proceeedings are reported of a Consultants' Meeting on Gamma-ray Standards for Detector Calibration, held at the CEN, Grenoble in France, from 30-31 May 1985. The meeting provided a forum to assess the requirements for a suitable file to be used internationally for the calibration of X- and gamma-ray detectors. A provisional list of nuclides was drawn up, and an initial assessment of the status of the required data was agreed to be performed by the participants before the end of 1985. (author)

  9. Gamma ray spectroscopy monitoring method and apparatus

    Science.gov (United States)

    Stagg, William R; Policke, Timothy A

    2017-05-16

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

  10. Gamma ray energy tracking in GRETINA

    Science.gov (United States)

    Lee, I. Y.

    2011-10-01

    The next generation of stable and exotic beam accelerators will provide physics opportunities to study nuclei farther away from the line of stability. However, these experiments will be more demanding on instrumentation performance. These come from the lower production rate for more exotic beams, worse beam impurities, and large beam velocity from the fragmentation and inverse reactions. Gamma-ray spectroscopy will be one of the most effective tools to study exotic nuclei. However, to fully exploit the physics reach provided by these new facilities, better gamma-ray detector will be needed. In the last 10 years, a new concept, gamma-ray energy tracking array, was developed. Tracking arrays will increase the detection sensitivity by factors of several hundred compared to current arrays used in nuclear physics research. Particularly, the capability of reconstructing the position of the interaction with millimeters resolution is needed to correct the Doppler broadening of gamma rays emitted from high velocity nuclei. GRETINA is a gamma-ray tracking array which uses 28 Ge crystals, each with 36 segments, to cover ¼ of the 4 π of the 4 π solid angle. The gamma ray tracking technique requires detailed pulse shape information from each of the segments. These pulses are digitized using 14-bit 100 MHz flash ADCs, and digital signal analysis algorithms implemented in the on-board FPGAs provides energy, time and selection of pulse traces. A digital trigger system, provided flexible trigger functions including a fast trigger output, and also allows complicated trigger decisions to be made up to 20 microseconds. Further analyzed, carried out in a computer cluster, determine the energy, time, and three-dimensional positions of all gamma-ray interactions in the array. This information is then utilized, together with the characteristics of Compton scattering and pair-production processes, to track the scattering sequences of the gamma rays. GRETINA construction is completed in

  11. Nuclear Forensics using Gamma-ray Spectroscopy

    Directory of Open Access Journals (Sweden)

    Norman E. B.

    2016-01-01

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

  12. Gamma-ray surveys in uranium exploration

    International Nuclear Information System (INIS)

    1979-01-01

    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

  13. 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.; hide

    2012-01-01

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

  14. Gamma-ray burst observations: the present situation

    International Nuclear Information System (INIS)

    Vedrenne, G.

    1984-01-01

    Recent results in gamma ray burst investigations concerning the spectral variability on a short time scale, precise locations, and the discovery of optical flashes in gamma ray burst positions on archival plates are presented. The implications of optical and X-ray observations of gamma ray burst error boxes are also discussed. 72 references

  15. Egret observations of the extragalactic gamma-ray emission

    DEFF Research Database (Denmark)

    Sreekumar, P.; Bertsch, D.L.; Dingus, B.L.

    1998-01-01

    The all-sky survey in high-energy gamma rays (E > 30 MeV) carried out by EGRET aboard the Compton Gamma Ray Observatory provides a unique opportunity to examine in detail the diffuse gamma-ray emission. The observed diffuse emission has a Galactic component arising from cosmic-ray interactions wi...

  16. Neutrino emission from gamma-ray burst fireballs, revised.

    Science.gov (United States)

    Hümmer, Svenja; Baerwald, Philipp; Winter, Walter

    2012-06-08

    We review the neutrino flux from gamma-ray bursts, which is estimated from gamma-ray observations and used for the interpretation of recent IceCube data, from a particle physics perspective. We numerically calculate the neutrino flux for the same astrophysical assumptions as the analytical fireball neutrino model, including the dominant pion and kaon production modes, flavor mixing, and magnetic field effects on the secondary muons, pions, and kaons. We demonstrate that taking into account the full energy dependencies of all spectra, the normalization of the expected neutrino flux reduces by about one order of magnitude and the spectrum shifts to higher energies, where we can pin down the exact origin of the discrepancies by the recomputation of the analytical models. We also reproduce the IceCube-40 analysis for exactly the same bursts and same assumptions and illustrate the impact of uncertainties. We conclude that the baryonic loading of the fireballs, which is an important control parameter for the emission of cosmic rays, can be constrained significantly with the full-scale experiment after about ten years.

  17. ICIT contribution to JET gamma-ray diagnostics enhancement

    International Nuclear Information System (INIS)

    Soare, S.; Curuia, M.; Zoita, V.

    2010-01-01

    Full text: Gamma-ray emission of tokamak plasmas is the result of the interaction of fast ions (fusion reaction products, including alpha particles, NBI ions, ICRH-accelerated ions) with main plasma impurities (e.g., carbon, beryllium). Gamma-ray diagnostics involve both gamma-ray imaging (cameras) and gamma-ray spectrometry (spectrometers). For the JET tokamak, gamma-ray diagnostics have been used to provide information on the characteristics of the fast ion population in plasmas. Two gamma-ray diagnostics enhancements project have been launched by JET and the MEdC/EURATOM Association has agreed to lead both of them with ICIT as projects leader. (authors)

  18. GammaModeler 3-D gamma-ray imaging technology

    International Nuclear Information System (INIS)

    2000-01-01

    The 3-D GammaModelertrademark system was used to survey a portion of the facility and provide 3-D visual and radiation representation of contaminated equipment located within the facility. The 3-D GammaModelertrademark system software was used to deconvolve extended sources into a series of point sources, locate the positions of these sources in space and calculate the 30 cm. dose rates for each of these sources. Localization of the sources in three dimensions provides information on source locations interior to the visual objects and provides a better estimate of the source intensities. The three dimensional representation of the objects can be made transparent in order to visualize sources located within the objects. Positional knowledge of all the sources can be used to calculate a map of the radiation in the canyon. The use of 3-D visual and gamma ray information supports improved planning decision-making, and aids in communications with regulators and stakeholders

  19. 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)

  20. Skyshine spectra of gamma rays

    International Nuclear Information System (INIS)

    Swarup, Janardan

    1980-01-01

    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.)

  1. The beginning of gamma-ray astronomy with Fermi

    International Nuclear Information System (INIS)

    Paneque, D.

    2008-01-01

    The Fermi observatory is designed to perform gamma-ray astronomy in the energy range 20 MeV to 300 GeV, with supporting measurements for gamma-ray bursts from 10 keV to 30 MeV. Fermi was successfully launched on June 11 (2008) from the Kennedy Space Center at Cape Canaveral. The main instrument of Fermi is the Large Area Telescope (LAT), which provides break-through high-energy measurements using techniques typically used in particle detectors for collider experiments. The LAT consists of 16 identical towers in a four-by-four grid, each one containing a pair conversion tracker and a hodoscopic crystal calorimeter, all covered by a segmented plastic scintillator anti-coincidence shield. The LAT is currently monitoring the GeV gamma-ray sky with rather uniform exposure (covering 20% of the sky at any instant and the entire sky on a timescale of a few hours) and a sensitivity ∼ 30 times better than its predecessor, EGRET. The large performance improvement of LAT opens a new and important window on a wide variety of high-energy astrophysical phenomena, as well as potential to discover/study non-conventional physics. In the talk I will report the instrument performance, the mission status and science opportunities and will present some results derived from the first months of operation, which includes astronomical telegrams on AGN flares, 2 GCN circulars on LAT-detected GRBs and the monitoring of some selected sources (22 blazars and 1 high mass X-ray Binary). (author)

  2. Gamma ray observations of the solar system

    International Nuclear Information System (INIS)

    1981-01-01

    Two general categories are discussed concerning the evolution of the solar system: the dualistic view, the planetesimal approach and the monistic view, the nebular hypothesis. The major points of each view are given and the models that are developed from these views are described. Possible applications of gamma ray astronomical observations to the question of the dynamic evolution of the solar system are discussed

  3. Gamma ray observations of the solar system

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

    Two general categories are discussed concerning the evolution of the solar system: the dualistic view, the planetesimal approach and the monistic view, the nebular hypothesis. The major points of each view are given and the models that are developed from these views are described. Possible applications of gamma ray astronomical observations to the question of the dynamic evolution of the solar system are discussed.

  4. Gamma ray observations of the solar system

    Science.gov (United States)

    1981-01-01

    Two general categories are discussed concerning the evolution of the solar system: the dualistic view, the planetesimal approach; and the monistic view, the nebular hypothesis. The major points of each view are given and the models that are developed from these views are described. Possible applications of gamma ray astronomical observations to the question of the dynamic evolution of the solar system are discussed.

  5. Black Hole Accretion in Gamma Ray Bursts

    Directory of Open Access Journals (Sweden)

    Agnieszka Janiuk

    2017-02-01

    Full Text Available We study the structure and evolution of the hyperaccreting disks and outflows in the gamma ray bursts central engines. The torus around a stellar mass black hole is composed of free nucleons, Helium, electron-positron pairs, and is cooled by neutrino emission. Accretion of matter powers the relativistic jets, responsible for the gamma ray prompt emission. The significant number density of neutrons in the disk and outflowing material will cause subsequent formation of heavier nuclei. We study the process of nucleosynthesis and its possible observational consequences. We also apply our scenario to the recent observation of the gravitational wave signal, detected on 14 September 2015 by the two Advanced LIGO detectors, and related to an inspiral and merger of a binary black hole system. A gamma ray burst that could possibly be related with the GW150914 event was observed by the Fermi satellite. It had a duration of about 1 s and appeared about 0.4 s after the gravitational-wave signal. We propose that a collapsing massive star and a black hole in a close binary could lead to the event. The gamma ray burst was powered by a weak neutrino flux produced in the star remnant’s matter. Low spin and kick velocity of the merged black hole are reproduced in our simulations. Coincident gravitational-wave emission originates from the merger of the collapsed core and the companion black hole.

  6. Gamma-ray bursts at high redshift

    NARCIS (Netherlands)

    Wijers, R.A.M.J.

    1999-01-01

    Gamma-ray bursts are much brighter than supernovae, and could therefore possibly probe the Universe to high redshift. The presently established GRB redshifts range from 0.83 to 5, and quite possibly even beyond that. Since most proposed mechanisms for GRB link them closely to deaths of massive

  7. Coakial gamma ray detector and method therefor

    International Nuclear Information System (INIS)

    Harchol, M.

    1977-01-01

    A coaxial gamma ray detector is fabricated using intrinsic Ge semiconductor material in a geometry whereby full depletion of electrical carriers is prevented within a small region proximate the point of electrical contact thereby allowing greater biasing potentials across the detector and, consequently, providing reduced electronic noise and increased energy resolution

  8. 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.).

  9. Current segmented gamma-ray scanner technology

    International Nuclear Information System (INIS)

    Bjork, C.W.

    1987-01-01

    A new generation of segmented gamma-ray scanners has been developed at Los Alamos for scrap and waste measurements at the Savannah River Plant and the Los Alamos Plutonium Facility. The new designs are highly automated and exhibit special features such as good segmentation and thorough shielding to improve performance

  10. 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…

  11. Gamma-ray astronomy: A historical perspective

    International Nuclear Information System (INIS)

    Lingenfelter, R.E.

    1988-01-01

    This is a brief review of the course theoretical gamma-ray astronomy has taken over the past thirty years. An examination is given of what the theoretical expectations were; to what extent they were realized; how well they anticipated new directions of research; and alternatively, how often were new directions unexpected

  12. Gamma-Ray Bursts Shower the Universe with Metals

    International Nuclear Information System (INIS)

    Hazi, A

    2006-01-01

    According to the results from a Livermore computer model, some of the small change jingling in your pocket contains zinc and copper created in massive gamma-ray bursts (GRBs) that rank as the most impressive light shows in the universe. Livermore astrophysicist Jason Pruet and his colleagues Rebecca Surman and Gail McLaughlin from North Carolina State University (NCSU) reported on their calculations in the February 20, 2004, issue of ''Astrophysical Journal Letters''. They found that GRBs from black holes surrounded by a disk of dense, hot plasma may have contributed heavily to the galactic inventory of elements such as calcium, scandium, titanium, zinc, and copper. ''A typical GRB of this kind briefly outshines all the stars in millions of galaxies combined'', says Pruet. ''Plus it makes about 100 times as much of some common elements as an ordinary supernova''

  13. Gamma-ray Output Spectra from 239 Pu Fission

    International Nuclear Information System (INIS)

    Ullmann, John

    2015-01-01

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

  14. Gamma-ray imaging probes

    International Nuclear Information System (INIS)

    Wild, W.J.

    1988-01-01

    External nuclear medicine diagnostic imaging of early primary and metastatic lung cancer tumors is difficult due to the poor sensitivity and resolution of existing gamma cameras. Nonimaging counting detectors used for internal tumor detection give ambiguous results because distant background variations are difficult to discriminate from neighboring tumor sites. This suggests that an internal imaging nuclear medicine probe, particularly an esophageal probe, may be advantageously used to detect small tumors because of the ability to discriminate against background variations and the capability to get close to sites neighboring the esophagus. The design, theory of operation, preliminary bench tests, characterization of noise behavior and optimization of such an imaging probe is the central theme of this work

  15. 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.

  16. Matrix of response functions for xenon gamma-ray detector

    International Nuclear Information System (INIS)

    Shustov, A.E.; Vlasik, K.F.; Grachev, V.M.; Dmitrenko, V.V.; Novikov, A.S.; P'ya, S.N.; Ulin, S.E.; Uteshev, Z.M.; Chernysheva, I.V.

    2014-01-01

    An approach of creation of response matrix using simulation GEANT4 gamma-ray Monte-Carlo method has been described for gamma-ray spectrometer based on high pressure xenon impulse ionization chamber with a shielding grid [ru

  17. Cosmic gamma-ray background radiation. Current understandings and problems

    International Nuclear Information System (INIS)

    Inoue, Yoshiyuki

    2015-01-01

    The cosmic gamma-ray background radiation is one of the most fundamental observables in the gamma-ray band. Although the origin of the cosmic gamma-ray background radiation has been a mystery for a long time, the Fermi gamma-ray space telescope has recently measured it at 0.1-820 GeV and revealed that the cosmic GeV gamma-ray background is composed of blazars, radio galaxies, and star-forming galaxies. However, Fermi still leaves the following questions. Those are dark matter contribution, origins of the cosmic MeV gamma-ray background, and the connection to the IceCube TeV-PeV neutrino events. In this proceeding, I will review the current understandings of the cosmic gamma-ray background and discuss future prospects of cosmic gamma-ray background radiation studies. (author)

  18. Searching for gravitational waves associated with gamma-ray bursts int 2009-2010 LIGO-Virgo data

    International Nuclear Information System (INIS)

    Was, M.

    2011-01-01

    In this thesis we present the results of the search for gravitational wave bursts associated with gamma-ray bursts in the 2009-2010 data from the LIGO-Virgo gravitational wave interferometer network. The study of gamma-ray bursts progenitors, both from the gamma-ray emission and the gravitational wave emission point of view, yields the characteristic of the sought signal: polarization, time delays, etc... This knowledge allows the construction of a data analysis method which includes the astrophysical priors on joint gravitational wave and gamma-ray emission, and moreover which is robust to non-stationary transient noises, which are present in the data. The lack of detection in the analyzed data yields novel observational limits on the gamma-ray burst population. (author)

  19. The new astrophysics

    International Nuclear Information System (INIS)

    Longair, M.

    1993-01-01

    The various themes developed are: radioastronomy, X-ray and gamma-ray astronomy, cosmic ray, ultraviolet, neutral hydrogen and molecular line astronomy, optical and theoretical astronomy; the large scale distribution of matter and radiation in the universe, the galaxies, stars and stellar evolution, the interstellar medium (gas, dust) and star formation, galaxies and clusters of galaxies, active galaxies and quasars, astrophysical cosmology, the astronomy of the future. 86 figs., 60 refs

  20. High-energy Emission from Nonrelativistic Radiative Shocks: Application to Gamma-Ray Novae

    Science.gov (United States)

    Vurm, Indrek; Metzger, Brian D.

    2018-01-01

    The observation of GeV gamma-rays from novae by Fermi/LAT demonstrates that the nonrelativistic radiative shocks in these systems can accelerate particles to energies of at least ∼10 GeV. The low-energy extension of the same nonthermal particle distribution inevitably gives rise to emission in the hard X-ray band. Above ≳ 10 {keV}, this radiation can escape the system without significant absorption/attenuation, and can potentially be detected by NuSTAR. We present theoretical models for hard X-ray and gamma-ray emission from radiative shocks in both leptonic and hadronic scenarios, accounting for the rapid evolution of the downstream properties due to the fast cooling of thermal plasma. We find that due to strong Coulomb losses, only a fraction of {10}-4{--}{10}-3 of the gamma-ray luminosity is radiated in the NuSTAR band; nevertheless, this emission could be detectable simultaneously with the LAT emission in bright gamma-ray novae with a ∼50 ks exposure. The spectral slope in hard X-rays is α ≈ 0 for typical nova parameters, thus serving as a testable prediction of the model. Our work demonstrates how combined hard X-ray and gamma-ray observations can be used to constrain properties of the nova outflow (velocity, density, and mass outflow rate) and particle acceleration at the shock. A very low X-ray to gamma-ray luminosity ratio ({L}{{X}}/{L}γ ≲ 5× {10}-4) would disfavor leptonic models for the gamma-ray emission. Our model can also be applied to other astrophysical environments with radiative shocks, including SNe IIn and colliding winds in massive star binaries.

  1. X-ray and gamma ray waveguide, cavity and method

    International Nuclear Information System (INIS)

    Vali, V.; Krogstad, R.S.; Willard, H.R.

    1978-01-01

    An x-ray and gamma ray waveguide, cavity, and method for directing electromagnetic radiation of the x-ray, gamma ray, and extreme ultraviolet wavelengths are described. A hollow fiber is used as the waveguide and is manufactured from a material having an index of refraction less than unity for these wavelengths. The internal diameter of the hollow fiber waveguide and the radius of curvature for the waveguide are selectively predetermined in light of the wavelength of the transmitted radiation to minimize losses. The electromagnetic radiation is obtained from any suitable source ad upon introduction into the waveguide is transmitted along a curvilinear path. The waveguide may be formed as a closed loop to create a cavity or may be used to direct the electromagnetic radiation to a utilization site

  2. X-Ray and Gamma-Ray Radiation Detector

    DEFF Research Database (Denmark)

    2015-01-01

    Disclosed is a semiconductor radiation detector for detecting X-ray and / or gamma-ray radiation. The detector comprises a converter element for converting incident X-ray and gamma-ray photons into electron-hole pairs, at least one cathode, a plurality of detector electrodes arranged with a pitch...... (P) along a first axis, a plurality of drift electrodes, a readout circuitry being configured to read out signals from the plurality of detector electrodes and a processing unit connected to the readout circuitry and being configured to detect an event in the converter element. The readout circuitry...... is further configured to read out signals from the plurality of drift electrodes, and the processing unit is further configured to estimate a location of the event along the first axis by processing signals obtained from both the detector electrodes and the drift electrodes, the location of the event along...

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

    International Nuclear Information System (INIS)

    Kheymits, M D; Leonov, A A; Zverev, V G; Galper, A M; Arkhangelskaya, I V; Arkhangelskiy, A I; Yurkin, Yu T; Bakaldin, A V; Suchkov, S I; Topchiev, N P; Dalkarov, O D

    2016-01-01

    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. (paper)

  4. Applications of Monte Carlo simulations of gamma-ray spectra

    International Nuclear Information System (INIS)

    Clark, D.D.

    1995-01-01

    A short, convenient computer program based on the Monte Carlo method that was developed to generate simulated gamma-ray spectra has been found to have useful applications in research and teaching. In research, we use it to predict spectra in neutron activation analysis (NAA), particularly in prompt gamma-ray NAA (PGNAA). In teaching, it is used to illustrate the dependence of detector response functions on the nature of gamma-ray interactions, the incident gamma-ray energy, and detector geometry

  5. Interstellar medium structure and content and gamma ray astronomy

    International Nuclear Information System (INIS)

    Lebrun, F.

    1982-05-01

    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 [fr

  6. Some aspects of ultra high energy gamma ray astronomy

    International Nuclear Information System (INIS)

    De Jager, O.C.

    1983-11-01

    A short review of ultra high energy (UHE) gamma ray astronomy (10 11 14 eV) as well as a description of a planned experiment to be erected at Potchefstroom is given in the introduction. This experiment will be the first and only one in the Southern Hemisphere and as such may play an important role in this new field of astronomy and astrophysics. In the first part the necessary infrastructure for astronomical observations of known celestial objects is developed. This embodies the special physical, mechanical and astronomical constraints in this type of astronomy, such as the definition of the various astronomical coordinate systems and transformations between them, the effect of precession and nutation on the source position etc. This leads to automatic observation schedules for the various applicable techniques of observation. In the second part the various effects which may influence the arrival time of a gamma ray at the telescope is investigated. It is found that dispersion and relativistic effects are negligible, given the special type of analysis used in this low counting rate system. The classic Doppler effect due to the motion of Earth as well as the configuration of the telescope does have a major effect and must be taken into consideration when analysing the data. A simple method, depending only on the movement of Earth around the sun, is developed to simplify the identification of pulsars at the planned observatory where computing facilities are limited

  7. Constraining decaying dark matter with FERMI-LAT gamma rays

    International Nuclear Information System (INIS)

    Maccione, L.

    2011-01-01

    High energy electron sand positrons from decaying dark matter can produce a significant flux of gamma rays by inverse Compton of low energy photons in the interstellar radiation field. This possibility is inevitably related with the dark matter interpretation of the observed PAMELA and FERMI excesses. We will describe a simple and universal method to constrain dark matter models which produce electrons and positrons in their decay by using the FERMI-LAT gamma-ray observations in the energy range between 0.5 GeV and 300 GeV, by exploiting universal response functions that, once convolved with a specific dark matter model, produce the desired constraint. The response functions contain all the astrophysical inputs. Here is discussed the uncertainties in the determination of the response functions and apply them to place constraints on some specific dark matter decay models that can well fit the positron and electron fluxes observed by PAMELA and FERMI LAT, also taking into account prompt radiation from the dark matter decay. With the available data decaying dark matter can not be excluded as source of the PAMELA positron excess.

  8. Physical constraints on models of gamma-ray bursters

    International Nuclear Information System (INIS)

    Epstein, R.I.

    1985-01-01

    This report deals with the constraints that can be placed on models of gamma-ray burst sources based on only the well-established observational facts and physical principles. The premise is developed that the very hard x-ray and gamma-ray continua spectra are well-established aspects of gamma-ray bursts. Recent theoretical work on gamma-ray bursts are summarized with emphasis on the geometrical properties of the models. Constraints on the source models which are implied by the x-ray and gamma-ray spectra are described. The allowed ranges for the luminosity and characteristic dimension for gamma-ray burst sources are shown. Some of the deductions and inferences about the nature of the gamma-ray burst sources are summarized. 67 refs., 3 figs

  9. Gamma-Ray Spectrum Analysis Software GDA

    International Nuclear Information System (INIS)

    Wanabongse, P.

    1998-01-01

    The developmental work on computer software for gamma-ray spectrum analysis has been completed as a software package version 1.02 named GDA, which is an acronym for Gamma-spectrum Deconvolution and Analysis. The software package consists of three 3.5-inch diskettes for setup and a user's manual. GDA software can be installed for using on a personal computer with Windows 95 or Windows NT 4.0 operating system. A computer maybe the type of 80486 CPU with 8 megabytes of memory

  10. Principles and techniques of gamma ray tracers

    International Nuclear Information System (INIS)

    Claxton, K.T.

    1978-01-01

    Radioactive tracer techniques provide a very sensitive means of studying physical and chemical processes in a whole variety of different media. Some of the techniques and principles of radioactive tracers and their application to practical engineering systems are discussed. Information which has been found useful in the design of high temperature liquid sodium facilities employing radio-tracers, is presented. The report deals solely with the use of gamma-emitting species as the tracer. These find particular application for in-situ studies on engineering systems where the highly penetrating properties of gamma rays are needed for detection through strongly absorbent media such as stainless steel pepe walls. (author)

  11. Gamma ray spectroscopy with Arduino UNO

    Science.gov (United States)

    Lavelle, C. M.

    2018-05-01

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

  12. Observational astrophysics

    CERN Document Server

    Smith, Robert C

    1995-01-01

    Combining a critical account of observational methods (telescopes and instrumentation) with a lucid description of the Universe, including stars, galaxies and cosmology, Smith provides a comprehensive introduction to the whole of modern astrophysics beyond the solar system. The first half describes the techniques used by astronomers to observe the Universe: optical telescopes and instruments are discussed in detail, but observations at all wavelengths are covered, from radio to gamma-rays. After a short interlude describing the appearance of the sky at all wavelengths, the role of positional astronomy is highlighted. In the second half, a clear description is given of the contents of the Universe, including accounts of stellar evolution and cosmological models. Fully illustrated throughout, with exercises given in each chapter, this textbook provides a thorough introduction to astrophysics for all physics undergraduates, and a valuable background for physics graduates turning to research in astronomy.

  13. Colors and luminosities of the optical afterglows of the gamma-ray bursts

    Czech Academy of Sciences Publication Activity Database

    Šimon, Vojtěch; Hudec, René; Pizzichini, G.; Masetti, N.

    2001-01-01

    Roč. 377, č. 2 (2001), s. 450-461 ISSN 0004-6361 R&D Projects: GA AV ČR KSK1048102; GA MŠk ME 137; GA MŠk ME 002; GA ČR GA205/99/0145 Institutional research plan: CEZ:AV0Z1003909 Keywords : gamma rays * bursts * radiation mechanisms Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.790, year: 2000

  14. Gamma-Ray Imaging Probes.

    Science.gov (United States)

    Wild, Walter James

    1988-12-01

    External nuclear medicine diagnostic imaging of early primary and metastatic lung cancer tumors is difficult due to the poor sensitivity and resolution of existing gamma cameras. Nonimaging counting detectors used for internal tumor detection give ambiguous results because distant background variations are difficult to discriminate from neighboring tumor sites. This suggests that an internal imaging nuclear medicine probe, particularly an esophageal probe, may be advantageously used to detect small tumors because of the ability to discriminate against background variations and the capability to get close to sites neighboring the esophagus. The design, theory of operation, preliminary bench tests, characterization of noise behavior and optimization of such an imaging probe is the central theme of this work. The central concept lies in the representation of the aperture shell by a sequence of binary digits. This, coupled with the mode of operation which is data encoding within an axial slice of space, leads to the fundamental imaging equation in which the coding operation is conveniently described by a circulant matrix operator. The coding/decoding process is a classic coded-aperture problem, and various estimators to achieve decoding are discussed. Some estimators require a priori information about the object (or object class) being imaged; the only unbiased estimator that does not impose this requirement is the simple inverse-matrix operator. The effects of noise on the estimate (or reconstruction) is discussed for general noise models and various codes/decoding operators. The choice of an optimal aperture for detector count times of clinical relevance is examined using a statistical class-separability formalism.

  15. Operating experience with gamma ray irradiators

    International Nuclear Information System (INIS)

    Fraser, F.M.; Ouwerkerk, T.

    1980-01-01

    The experience of Atomic Energy of Canada, Limited (AECL) with radioisotopes dates back to the mid-1940s when radium was marketed for medical purposes. Cobalt-60 came on the scene in 1949 and within a few years a thriving business in cancer teletherapy machines and research irradiators was developed. AECL's first full-scale cobalt-60 gamma ray sterilizer for medical products was installed in 1964. AECL now has over 50 plants and 30 million curies in service around the world. Sixteen years of design experience in cobalt-60 sources, radiation shielding, safety interlock systems, and source pass mechanisms have made gamma irradiators safe, reliable, and easy to operate. This proven technology is being applied in promising new fields such as sludge treatment and food preservation. Cesium-137 is expected to be extensively utilized as the gamma radiation source for these applications

  16. Dosimetry for terrestrial gamma-ray sources

    International Nuclear Information System (INIS)

    Abdullah, S.A.; Dickson, H.W.; Kerr, G.D.; Miah, M.F.K.; Perdue, P.T.

    1975-01-01

    Dose rates from natural radionuclides and 137 Cs in soils of the Oak Ridge area have been determined from in situ and core sample measurements. Information on soil composition, density, and moisture content and on the distribution of cesium in the soil was obtained from the core samples. Measurements of radionuclide concentrations in the samples were made with a 4 x 4 in. NaI detector. Gamma-ray spectroscopy using a lithium-drifted germanium (GeLi) detector has been applied to the determination of radionuclide concentrations in soil and the associated gamma dose rates above the earth plane. An unshielded GeLi detector placed about 1 m above the earth detects gamma radiation from an area of about 100 m 2 . The equipment and data processing procedure are briefly described

  17. The emission of Gamma Ray Bursts as a test-bed for modified gravity

    Directory of Open Access Journals (Sweden)

    S. Capozziello

    2015-11-01

    Full Text Available The extreme physical conditions of Gamma Ray Bursts can constitute a useful observational laboratory to test theories of gravity where very high curvature regimes are involved. Here we propose a sort of curvature engine capable, in principle, of explaining the huge energy emission of Gamma Ray Bursts. Specifically, we investigate the emission of radiation by charged particles non-minimally coupled to the gravitational background where higher order curvature invariants are present. The coupling gives rise to an additional force inducing a non-geodesic motion of particles. This fact allows a strong emission of radiation by gravitationally accelerated particles. As we will show with some specific model, the energy emission is of the same order of magnitude of that characterizing the Gamma Ray Burst physics. Alternatively, strong curvature regimes can be considered as a natural mechanism for the generation of highly energetic astrophysical events. Possible applications to cosmology are discussed.

  18. An Overview of the Current Understanding of Gamma-Ray Bursts in the Fermi Era

    Science.gov (United States)

    Bhat, P. N.; Guiriec, Sylvain

    2011-01-01

    Gamma-ray bursts are the most luminous explosions in the Universe, and their origin as well as mechanism are the focus of intense research and debate. More than three decades since their serendipitous discovery, followed by several breakthroughs from space-borne and ground-based observations, they remain one of the most interesting astrophysical phenomena yet to be completely understood. Since the launch of Fermi with its unprecedented energy band width spanning seven decades, the study of gamma-ray burst research has entered a new phase. Here we review the current theoretical understanding and observational highlights of gamma-ray burst astronomy and point out some of the potential promises of multi-wavelength observations in view of the upcoming ground based observational facilities .

  19. Continuum gamma-ray spectroscopy

    International Nuclear Information System (INIS)

    Diamond, R.M.

    1981-06-01

    When angular momentum is added to a nucleus, it is, of course, carried by the individual nucleons, but two limiting types of behavior may be distinguished: (1) a small number of high-j particles align with the rotation axis and (2) the nucleus is deformed and rotates as a whole. At high spin all nuclei seem to show a compromise utilizing both motions. The excited nuclei left as products of (HI,xn) reactions have so many pathways down that none of the γ-ray transitions have enough intensity to be seen individually until the population gathers near the yrast line. This occurs usually between spin 20 to 40 h-bar. All our information on the higher states comes from their continuum spectra. With the new techniques that are developing, including the use of multiplicity filters, total-energy spectrometers, energy correlation studies, crystal balls, and observation of giant dipole resonances in the continuum spectra, there is hope to learn much about the nature of the high-spin states

  20. Gamma-ray spectrometry applied to down-hole logging

    International Nuclear Information System (INIS)

    Dumesnil, P.; Umiastowsky, K.

    1983-11-01

    Gamma-ray spectrometry permits to improve the accuracy of natural gamma, gamma-gamma and neutron-gamma geophysical measurements. The probe developed at Centre d'Etudes Nucleaires de Saclay allows down-hole gamma-ray spectrometry. Among others, this probe can be applied to the uranium content determination by selective natural gamma method, down-hole determination of the ash content in the coal by gamma-gamma selective method and elemental analysis by neutron-gamma method. For the calibration and an exact interpretation of the measurements it is important to know the gamma-ray and neutron characteristics of the different kinds of rocks considered as probabilistic variables

  1. Relativistic effects in gamma-ray bursts

    International Nuclear Information System (INIS)

    Eriksen, Erik; Groen, Oeyvind

    1999-01-01

    According to recent models of the sources of gamma-ray bursts the extremely energetic emission is caused by shells expanding with ultrarelativistic velocity. With the recent identification of optical sources at the positions of some gamma-ray bursts these ''fireball'' models have acquired an actuality that invites to use them as a motivating application when teaching special relativity. We demonstrate several relativistic effects associated with these models which are very pronounced due to the great velocity of the shell. For example a burst lasting for a month in the rest frame of an element of the shell lasts for a few seconds only, in the rest frame of our detector. It is shown how the observed properties of a burst are modified by aberration and the Doppler effect. The apparent luminosity as a function of time is calculated. Modifications due to the motion of the star away from the observer are calculated. (Author)

  2. Fissile interrogation using gamma rays from oxygen

    Science.gov (United States)

    Smith, Donald; Micklich, Bradley J.; Fessler, Andreas

    2004-04-20

    The subject apparatus provides a means to identify the presence of fissionable material or other nuclear material contained within an item to be tested. The system employs a portable accelerator to accelerate and direct protons to a fluorine-compound target. The interaction of the protons with the fluorine-compound target produces gamma rays which are directed at the item to be tested. If the item to be tested contains either a fissionable material or other nuclear material the interaction of the gamma rays with the material contained within the test item with result in the production of neutrons. A system of neutron detectors is positioned to intercept any neutrons generated by the test item. The results from the neutron detectors are analyzed to determine the presence of a fissionable material or other nuclear material.

  3. Environmental Effects of Gamma Ray Bursts

    International Nuclear Information System (INIS)

    Martin, Osmel; Zarauza, Dario; Cardenas, Rolando

    2007-01-01

    Gamma rays bursts, coming from very massive stars, are the most powerful explosions in our Universe. Some authors have linked them to some of the climatic changes and consequent biological mass extinctions of the Phanerozoic eon. However, the consequences of their direct impact on primitive Earth, is today a hot topic of debate. On the other hand, it is usually assumed that they were more common in earlier stages of our galaxy. So it is important to evaluate its potential effects on terrestrial paleoenvironments. We outline some simple models to estimate their influence mainly on the primordial atmospheric chemistry of Earth and on the climate in general. To do that, we consider different scenarios where the atmospheric composition diverges substantially from the atmosphere today, and compute the evolution of principal chemical species under the intense radiational stress of a gamma ray burst. Furthermore, the possible impact on the isotopic composition, geochemistry and the biosphere are mentioned in general way

  4. TeV gamma-ray astronomy

    International Nuclear Information System (INIS)

    Cui Wei

    2009-01-01

    The field of ground-based gamma-ray astronomy has enjoyed rapid growth in recent years. As an increasing number of sources are detected at TeV energies, the field has matured and become a viable branch of modern astronomy. Lying at the uppermost end of the electromagnetic rainbow, TeV photons are always preciously few in number but carry essential information about the particle acceleration and radiative processes involved in extreme astronomical settings. Together with observations at longer wavelengths, TeV gamma-ray observations have drastically improved our view of the universe. In this review, we briefly describe recent progress in the field. We will conclude by providing a personal perspective on the future of the field, in particular, on the significant roles that China could play in advancing this young but exciting field. (invited reviews)

  5. Real time gamma-ray signature identifier

    Science.gov (United States)

    Rowland, Mark [Alamo, CA; Gosnell, Tom B [Moraga, CA; Ham, Cheryl [Livermore, CA; Perkins, Dwight [Livermore, CA; Wong, James [Dublin, CA

    2012-05-15

    A real time gamma-ray signature/source identification method and system using principal components analysis (PCA) for transforming and substantially reducing one or more comprehensive spectral libraries of nuclear materials types and configurations into a corresponding concise representation/signature(s) representing and indexing each individual predetermined spectrum in principal component (PC) space, wherein an unknown gamma-ray signature may be compared against the representative signature to find a match or at least characterize the unknown signature from among all the entries in the library with a single regression or simple projection into the PC space, so as to substantially reduce processing time and computing resources and enable real-time characterization and/or identification.

  6. Attenuation of the gamma rays in tissues

    International Nuclear Information System (INIS)

    Arcos P, A.; Rodriguez N, S.; Pinedo S, A.; Amador V, P.; Chacon R, A.; Vega C, H.R.

    2005-01-01

    The mass and lineal attenuation coefficient and of hepatic tissue, muscular, osseous and of brain before gamma rays of 10 -3 to 10 5 MeV were calculated. For the case of the osseous tissue the calculation was made for the cartilage, the cortical tissue and the bone marrow. During the calculations the elementary composition of the tissues of human origin was used. The calculations include by separate the Photoelectric effect, the Compton scattering and the Pair production, as well as the total. For to establish a comparison with the attenuation capacities, the coefficients of the water, the aluminum and the lead also were calculated. The study was complemented measuring the attenuation coefficient of hepatic tissue of bovine before gamma rays of 0.662 MeV of a source of 137 Cs. The measurement was made through of an experiment of photons transmission through samples frozen of hepatic tissue and with a Geiger-Mueller detector. (Author)

  7. Advances in gamma-ray burst astronomy

    International Nuclear Information System (INIS)

    Cline, T.L.; Desai, U.D.

    1976-01-01

    Work at Goddard is presently being carried out in three major areas of gamma-ray burst research: (1) A pair of simultaneously operating 0.8-m 2 burst detectors were successfully balloon-borne at locations 800 miles apart on 9 May, 1975, each to atmospheric depths of 3 to 4 g cm -2 , for a 20-h period of coincident data coverage. This experiment investigates the size spectrum of bursts in the 10 -7 to 10 -6 erg cm -2 size region where dozens of events per day are expected on a -1.5 index integral power-law extrapolation. Considerable separation in latitude was used to avoid possible atmospheric and auroral secondary effects. Its results are not yet available. (2) A deep-space burst detector, the first spacecraft instrument built specifically for gamma-ray burst studies, was recently successfully integrated into the Helios-B space probe. Its use at distances of up to 2 AU will make possible the first high-resolution directional study of gamma-ray burst source locations. Similar modifications to several other space vehicles are also being prepared. (3) The gamma-ray instrument on the IMP-7 satellite is presently the most sensitive burst detector still operating in orbit. Its results have shown that all measured event-average energy spectra are consistent with being alike. Using this characteristic spectrum to select IMP-7 candidate events of smaller size than those detected using other spacecraft in coincidence, a size spectrum is constructed which fits the -1.5 index power law down to 2.5 x 10 -5 erg cm -2 per event, at an occurrence rate of about once per month. (Auth.)

  8. Evaluation of gamma-ray intensities

    International Nuclear Information System (INIS)

    Yoshizawa, Yasukazu; Inoue, Hikaru; Hoshi, Masaharu; Shizuma, Kiyoshi; Iwata, Yosei.

    1978-03-01

    Results of literature survey and evaluation of relative intensities and intensities per decay of gamma rays are presented. Evaluations were made for 22 Na, 24 Na, 46 Sc, 48 Sc, 48 V, 54 Mn, 57 Co, 60 Co, 85 Sr, 88 Y, 95 Nb, 95 Zr, sup(108m)Ag, 134 Cs, 137 Cs, 144 Ce, 144 Pr, 203 Hg, and 207 Bi. For eight of the nuclides, the half-lives were also evaluated. (auth.)

  9. Common Gamma-ray Glows above Thunderclouds

    Science.gov (United States)

    Kelley, Nicole; Smith, David; Dwyer, Joseph; Hazelton, Bryna; Grefenstette, Brian; Lowell, Alex; Splitt, Michael; Lazarus, Steven; Rassoul, Hamid

    2013-04-01

    Gamma-ray glows are continuous, long duration gamma- and x-ray emission seen coming from thunderclouds. The Airborne for Energetic Lightning Emissions (ADELE) observed 12 gamma-ray glows during its summer 2009 flight campaign over the areas of Colorado and Florida in the United States. For these glows we shall present their spectra, relationship to lightning activity and how their duration and size changes as a function of distance. Gamma-ray glows follow the relativistic runaway electron avalanche (RREA) spectrum and have been previously measured from the ground and inside the cloud. ADELE measured most glows as it flew above the screening layer of the cloud. During the brightest glow on August 21, 2009, we can show that we are flying directly into a downward facing relativistic runaway avalanche, indicative of flying between the upper positive and negative screening layer of the cloud. In order to explain the brightness of this glow, RREA with an electric field approaching the limit for relativistic feedback must be occurring. Using all 12 glows, we show that lightning activity diminishes during the onset of the glow. Using this along with the fact that glows occur as the field approaches the level necessary for feedback, we attempt to distinguish between two possibilities: that glows are evidence that RREA with feedback, rather than lightning, is sometimes the primary channel for discharging the cloud, or else that the overall discharging is still controlled by lightning, with glows simply appearing during times when a subsidence of lightning allows the field to rise above the threshold for RREA.

  10. Gamma-ray standards for detector calibration

    International Nuclear Information System (INIS)

    Christmas, P.; Nichols, A.L.; Lorenz, A.

    1987-09-01

    The first official meeting of the IAEA Coordinated Research Programme on the Measurement and Evaluation of X- and Gamma-ray Standards for Detector Calibration was held in Rome from 11 to 13 June 1987. Work undertaken by the CRP members was reviewed in detail: specific problems in the evaluations were identified and actions placed on the participants to resolve these issues. (author). 3 tabs

  11. Gamma-ray bursts - a critical review

    International Nuclear Information System (INIS)

    Tudose, Valeriu; Biermann, Peter

    2003-01-01

    We present a short general introduction into the field of gamma-ray bursts (GRBs) research, summarizing the past and the present status. We give an general view of the GRBs observations to date, both in the prompt emission phase as well as in the afterglow phase, and a brief primer into the theory, mainly in the frame-work of the fireball model. (authors)

  12. Comptonization of gamma rays by cold electrons

    International Nuclear Information System (INIS)

    Xu, Yueming; Ross, R.R.; Mccray, R.

    1991-01-01

    An analytic method is developed for calculating the emergent spectrum of gamma-rays and X-rays scattered in a homogeneous medium with low-temperature electrons. The Klein-Nishina corrections of the scattering cross section and absorption processes are taken in account. The wavelength relaxation and the spatial diffusion problems are solved separately, and the emergent spectrum is calculated by convolving the evolution function of the spectrum in an infinite medium with the photon luminosity resulting from the spatial diffusion in a finite sphere. The analytic results are compared with that of Monte Carlo calculations and it is concluded that the analytic result is quite accurate. 9 refs

  13. Prompt Gamma Ray Analysis of Soil Samples

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A.; Khiari, F.Z.; Haseeb, S.M.A.; Hussein, Tanvir; Khateeb-ur-Rehman [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Isab, A.H. [Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

    2015-07-01

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

  14. Gamma ray irradiation characteristics of SM fibers

    International Nuclear Information System (INIS)

    Ito, Ryuichi; Okano, Hiroaki; Hashiba, Keichi; Nakai, Hisanori

    1987-01-01

    1.3 μm range single mode (SM) optical fibers have been used for wide application of mainly long distance communication. At present, in order to realize the larger capacity and longer distance between relay points, the development of 1.5 μm range SM fibers of low dispersion and small loss has been actively promoted. As for the radiation withstanding property of SM fibers, report is scarce. The authors reported on the gamma ray irradiation characteristics of 1.3 μm range SM fibers, but since 1.5 μm range SM fibers are designed with the different structure from that of 1.3 μm fibers, it is necessary to evaluate from new viewpoint. In this report, mainly on the structure having triangular distribution, the effect that the manufacturing condition and the structural defects of glass exert on the gamma ray irradiation characteristics is described. The specimens were mainly dispersion shift type fibers (DSF), and for comparison, single window, double window and 1.3 μm SM fibers were examined. Co-60 gamma ray was irradiated, and the optical loss and electron spin resonance were measured. By low temperature and low speed drawing, the good result in the optical loss was obtained. The presence of oxygen at the time of sintering materials had no effect. The dependence of the ESR on the drawing condition was not very remarkable. (Kako, I.)

  15. A gamma-ray discriminating neutron scintillator

    International Nuclear Information System (INIS)

    Eschbach, P.A.; Miller, S.D.; Cole, M.C.

    1994-01-01

    A neutron scintillator has been developed at Pacific Northwest Laboratory which responds directly to as little as 10 mrem/hour dose equivalent rate fast neutron fields. The scintillator is composed of CaF 2 :Eu or of NaI grains within a silicone rubber or polystyrene matrix, respectively. Neutrons colliding with the plastic matrix provide knockon protons, which in turn deposit energy within the grains of phosphor to produce pulses of light. Neutron interactions are discriminated from gamma-ray events on the basis of pulse height. Unlike NE-213 liquid scintillators, this solid scintillator requires no pulseshape discrimination and therefore requires less hardware. Neutron events are anywhere from two to three times larger than the gamma-ray exposures are compared to 0.7 MeV gamma-ray exposures. The CaF 2 :Eu/silicone rubber scintillator is nearly optically transparent, and can be made into a very sizable detector (4 cm x 1.5 cm) without degrading pulse height. This CaF 2 :Eu scintillator has been observed to have an absolute efficiency of 0.1% when exposed to 5-MeV accelerator-generated neutrons (where the absolute efficiency is the ratio of observed neutron events divided by the number of fast neutrons striking the detector)

  16. Gamma-Ray Pulsars Models and Predictions

    CERN Document Server

    Harding, A K

    2001-01-01

    Pulsed emission from gamma-ray pulsars originates inside the magnetosphere, from radiation by charged particles accelerated near the magnetic poles or in the outer gaps. In polar cap models, the high energy spectrum is cut off by magnetic pair production above an energy that is dependent on the local magnetic field strength. While most young pulsars with surface fields in the range B = 10^{12} - 10^{13} G are expected to have high energy cutoffs around several GeV, the gamma-ray spectra of old pulsars having lower surface fields may extend to 50 GeV. Although the gamma-ray emission of older pulsars is weaker, detecting pulsed emission at high energies from nearby sources would be an important confirmation of polar cap models. Outer gap models predict more gradual high-energy turnovers at around 10 GeV, but also predict an inverse Compton component extending to TeV energies. Detection of pulsed TeV emission, which would not survive attenuation at the polar caps, is thus an important test of outer gap models. N...

  17. Radio Flares from Gamma-ray Bursts

    Science.gov (United States)

    Kopač, D.; Mundell, C. G.; Kobayashi, S.; Virgili, F. J.; Harrison, R.; Japelj, J.; Guidorzi, C.; Melandri, A.; Gomboc, A.

    2015-06-01

    We present predictions of centimeter and millimeter radio emission from reverse shocks (RSs) in the early afterglows of gamma-ray bursts (GRBs) with the goal of determining their detectability with current and future radio facilities. Using a range of GRB properties, such as peak optical brightness and time, isotropic equivalent gamma-ray energy, and redshift, we simulate radio light curves in a framework generalized for any circumburst medium structure and including a parameterization of the shell thickness regime that is more realistic than the simple assumption of thick- or thin-shell approximations. Building on earlier work by Mundell et al. and Melandri et al. in which the typical frequency of the RS was suggested to lie at radio rather than optical wavelengths at early times, we show that the brightest and most distinct RS radio signatures are detectable up to 0.1-1 day after the burst, emphasizing the need for rapid radio follow-up. Detection is easier for bursts with later optical peaks, high isotropic energies, lower circumburst medium densities, and at observing frequencies that are less prone to synchrotron self-absorption effects—typically above a few GHz. Given recent detections of polarized prompt gamma-ray and optical RS emission, we suggest that detection of polarized radio/millimeter emission will unambiguously confirm the presence of low-frequency RSs at early time.

  18. RADIO FLARES FROM GAMMA-RAY BURSTS

    International Nuclear Information System (INIS)

    Kopač, D.; Mundell, C. G.; Kobayashi, S.; Virgili, F. J.; Harrison, R.; Japelj, J.; Gomboc, A.; Guidorzi, C.; Melandri, A.

    2015-01-01

    We present predictions of centimeter and millimeter radio emission from reverse shocks (RSs) in the early afterglows of gamma-ray bursts (GRBs) with the goal of determining their detectability with current and future radio facilities. Using a range of GRB properties, such as peak optical brightness and time, isotropic equivalent gamma-ray energy, and redshift, we simulate radio light curves in a framework generalized for any circumburst medium structure and including a parameterization of the shell thickness regime that is more realistic than the simple assumption of thick- or thin-shell approximations. Building on earlier work by Mundell et al. and Melandri et al. in which the typical frequency of the RS was suggested to lie at radio rather than optical wavelengths at early times, we show that the brightest and most distinct RS radio signatures are detectable up to 0.1–1 day after the burst, emphasizing the need for rapid radio follow-up. Detection is easier for bursts with later optical peaks, high isotropic energies, lower circumburst medium densities, and at observing frequencies that are less prone to synchrotron self-absorption effects—typically above a few GHz. Given recent detections of polarized prompt gamma-ray and optical RS emission, we suggest that detection of polarized radio/millimeter emission will unambiguously confirm the presence of low-frequency RSs at early time

  19. Catalog of gamma-rays unplaced in radioactive decay schemes

    International Nuclear Information System (INIS)

    Narita, Tsutomu; Kitao, Kensuke.

    1991-03-01

    A catalog is made for gamma-rays emitted in decay of radioactive nuclides but not placed in their decay schemes. It consists of two tables. In Table 1, the number of these unplaced gamma-ray components by a nuclide is given together with the fraction of total intensity of these gamma-rays to that of all observed gamma-rays. In Table 2, the unplaced gamma-rays are arranged in order of increasing energy. Each line of this table contains the gamma-ray energy, intensity, nuclide identification, and energies and intensities of the most prominent gamma-rays from the decay of the radionuclides. This catalog is a compilation from Evaluated Nuclear Structure Data File (ENSDF) maintained by National Nuclear Data Center at Brookhaven National Laboratory, of at February 1990. (author)

  20. Highlights of GeV Gamma-Ray Astronomy

    Science.gov (United States)

    Thompson, David J.

    2010-01-01

    Because high-energy gamma rays are primarily produced by high-energy particle interactions, the gamma-ray survey of the sky by the Fermi Gamma-ray Space Telescope offers a view of sites of cosmic ray production and interactions. Gamma-ray bursts, pulsars, pulsar wind nebulae, binary sources, and Active Galactic Nuclei are all phenomena that reveal particle acceleration through their gamma-ray emission. Diffuse Galactic gamma radiation, Solar System gamma-ray sources, and energetic radiation from supernova remnants are likely tracers of high-energy particle interactions with matter and photon fields. This paper will present a broad overview of the constantly changing sky seen with the Large Area Telescope (LAT) on the Fermi spacecraft.

  1. Lunar occultations for gamma-ray source measurements

    Science.gov (United States)

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

    1990-01-01

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

  2. Gamma Ray Tomographic Scan Method for Large Scale Industrial Plants

    International Nuclear Information System (INIS)

    Moon, Jin Ho; Jung, Sung Hee; Kim, Jong Bum; Park, Jang Geun

    2011-01-01

    The gamma ray tomography systems have been used to investigate a chemical process for last decade. There have been many cases of gamma ray tomography for laboratory scale work but not many cases for industrial scale work. Non-tomographic equipment with gamma-ray sources is often used in process diagnosis. Gamma radiography, gamma column scanning and the radioisotope tracer technique are examples of gamma ray application in industries. In spite of many outdoor non-gamma ray tomographic equipment, the most of gamma ray tomographic systems still remained as indoor equipment. But, as the gamma tomography has developed, the demand on gamma tomography for real scale plants also increased. To develop the industrial scale system, we introduced the gamma-ray tomographic system with fixed detectors and rotating source. The general system configuration is similar to 4 th generation geometry. But the main effort has been made to actualize the instant installation of the system for real scale industrial plant. This work would be a first attempt to apply the 4th generation industrial gamma tomographic scanning by experimental method. The individual 0.5-inch NaI detector was used for gamma ray detection by configuring circular shape around industrial plant. This tomographic scan method can reduce mechanical complexity and require a much smaller space than a conventional CT. Those properties make it easy to get measurement data for a real scale plant

  3. Light Dawns on Dark Gamma-ray Bursts

    Science.gov (United States)

    2010-12-01

    Gamma-ray bursts are among the most energetic events in the Universe, but some appear curiously faint in visible light. The biggest study to date of these so-called dark gamma-ray bursts, using the GROND instrument on the 2.2-metre MPG/ESO telescope at La Silla in Chile, has found that these gigantic explosions don't require exotic explanations. Their faintness is now fully explained by a combination of causes, the most important of which is the presence of dust between the Earth and the explosion. Gamma-ray bursts (GRBs), fleeting events that last from less than a second to several minutes, are detected by orbiting observatories that can pick up their high energy radiation. Thirteen years ago, however, astronomers discovered a longer-lasting stream of less energetic radiation coming from these violent outbursts, which can last for weeks or even years after the initial explosion. Astronomers call this the burst's afterglow. While all gamma-ray bursts [1] have afterglows that give off X-rays, only about half of them were found to give off visible light, with the rest remaining mysteriously dark. Some astronomers suspected that these dark afterglows could be examples of a whole new class of gamma-ray bursts, while others thought that they might all be at very great distances. Previous studies had suggested that obscuring dust between the burst and us might also explain why they were so dim. "Studying afterglows is vital to further our understanding of the objects that become gamma-ray bursts and what they tell us about star formation in the early Universe," says the study's lead author Jochen Greiner from the Max-Planck Institute for Extraterrestrial Physics in Garching bei München, Germany. NASA launched the Swift satellite at the end of 2004. From its orbit above the Earth's atmosphere it can detect gamma-ray bursts and immediately relay their positions to other observatories so that the afterglows could be studied. In the new study, astronomers combined Swift

  4. A link between prompt optical and prompt gamma-ray emission in gamma-ray bursts.

    Science.gov (United States)

    Vestrand, W T; Wozniak, P R; Wren, J A; Fenimore, E E; Sakamoto, T; White, R R; Casperson, D; Davis, H; Evans, S; Galassi, M; McGowan, K E; Schier, J A; Asa, J W; Barthelmy, S D; Cummings, J R; Gehrels, N; Hullinger, D; Krimm, H A; Markwardt, C B; McLean, K; Palmer, D; Parsons, A; Tueller, J

    2005-05-12

    The prompt optical emission that arrives with the gamma-rays from a cosmic gamma-ray burst (GRB) is a signature of the engine powering the burst, the properties of the ultra-relativistic ejecta of the explosion, and the ejecta's interactions with the surroundings. Until now, only GRB 990123 had been detected at optical wavelengths during the burst phase. Its prompt optical emission was variable and uncorrelated with the prompt gamma-ray emission, suggesting that the optical emission was generated by a reverse shock arising from the ejecta's collision with surrounding material. Here we report prompt optical emission from GRB 041219a. It is variable and correlated with the prompt gamma-rays, indicating a common origin for the optical light and the gamma-rays. Within the context of the standard fireball model of GRBs, we attribute this new optical component to internal shocks driven into the burst ejecta by variations of the inner engine. The correlated optical emission is a direct probe of the jet isolated from the medium. The timing of the uncorrelated optical emission is strongly dependent on the nature of the medium.

  5. Instrument for observing transient cosmic gamma-ray sources for the ISEE-C Heliocentric spacecraft

    International Nuclear Information System (INIS)

    Evans, W.D.; Aiello, W.P.; Klebesadel, R.W.

    1977-12-01

    Satellite instrumentation that would serve as one element of a three-satellite network to provide precise directional information for the recently discovered cosmic gamma-ray bursts is described. The proposed network would be capable of determining source locations with uncertainties of less than one arc minute, sufficient for a meaningful optical and radio search. The association of the gamma bursts with a known type of astrophysical object provides the most direct method for establishing source distances and thus defining the overall energetics of the emission process

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

    International Nuclear Information System (INIS)

    Grenier, Isabelle

    2009-01-01

    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.

  7. Contribution to gamma ray transport calculation in heterogeneous media

    International Nuclear Information System (INIS)

    Bourdet, L.

    1985-04-01

    This thesis presents the development of gamma transport calculation codes in three dimension heterogeneous geometries. These codes allow us to define the protection against gamma-rays or verify their efficiency. The laws that govern the interactions of gamma-rays with matters are briefly revised. A library with the all necessary constants for these codes is created. TRIPOLI-2, a code that treats in exact way the neutron transport in matters using Monte-Carlo method, has been adapted to deal with the transport of gamma-rays in matters as well. TRINISHI, a code which considers only one collision, has been realized to treat heterogeneous geometries containing voids. Elaborating a formula that calculates the albedo for gamma-ray reflection (the code ALBANE) allows us to solve the problem of gamma-ray reflection on plane surfaces. NARCISSE-2 deals with gamma-rays that suffer only one reflection on the inner walls of any closed volume (rooms, halls...) [fr

  8. Local gamma ray events as tests of the antimatter theory of gamma ray bursts

    International Nuclear Information System (INIS)

    Sofia, S.; Wilson, R.E.

    1976-01-01

    Nearby examples of the antimatter 'chunks' postulated by Sofia and Van Horn to explain the cosmic gamma ray bursts may produce detectable gamma ray events when struck by solar system meteoroids. These events would have a much shorter time scale and higher energy spectrum than the bursts already observed. In order to have a reasonably high event rate, the local meteoroid population must extend to a distance from the Sun of the order of 0.1 pc, but the required distance could become much lower if the instrumental threshold is improved. The expected gamma ray flux for interaction of the antimatter bodies with the solar wind is also examined, and found to be far below present instrumental capabilities. (Auth.)

  9. GAMMA RAYS FROM STAR FORMATION IN CLUSTERS OF GALAXIES

    International Nuclear Information System (INIS)

    Storm, Emma M.; Jeltema, Tesla E.; Profumo, Stefano

    2012-01-01

    Star formation in galaxies is observed to be associated with gamma-ray emission, presumably from non-thermal processes connected to the acceleration of cosmic-ray nuclei and electrons. The detection of gamma rays from starburst galaxies by the Fermi Large Area Telescope (LAT) has allowed the determination of a functional relationship between star formation rate and gamma-ray luminosity. Since star formation is known to scale with total infrared (8-1000 μm) and radio (1.4 GHz) luminosity, the observed infrared and radio emission from a star-forming galaxy can be used to quantitatively infer the galaxy's gamma-ray luminosity. Similarly, star-forming galaxies within galaxy clusters allow us to derive lower limits on the gamma-ray emission from clusters, which have not yet been conclusively detected in gamma rays. In this study, we apply the functional relationships between gamma-ray luminosity and radio and IR luminosities of galaxies derived by the Fermi Collaboration to a sample of the best candidate galaxy clusters for detection in gamma rays in order to place lower limits on the gamma-ray emission associated with star formation in galaxy clusters. We find that several clusters have predicted gamma-ray emission from star formation that are within an order of magnitude of the upper limits derived in Ackermann et al. based on non-detection by Fermi-LAT. Given the current gamma-ray limits, star formation likely plays a significant role in the gamma-ray emission in some clusters, especially those with cool cores. We predict that both Fermi-LAT over the course of its lifetime and the future Cerenkov Telescope Array will be able to detect gamma-ray emission from star-forming galaxies in clusters.

  10. Gamma-ray burst theory after Swift.

    Science.gov (United States)

    Piran, Tsvi; Fan, Yi-Zhong

    2007-05-15

    Afterglow observations in the pre-Swift era confirmed to a large extend the relativistic blast wave model for gamma-ray bursts (GRBs). Together with the observations of properties of host galaxies and the association with (type Ic) SNe, this has led to the generally accepted collapsar origin of long GRBs. However, most of the afterglow data was collected hours after the burst. The X-ray telescope and the UV/optical telescope onboard Swift are able to slew to the direction of a burst in real time and record the early broadband afterglow light curves. These observations, and in particular the X-ray observations, resulted in many surprises. While we have anticipated a smooth transition from the prompt emission to the afterglow, many observed that early light curves are drastically different. We review here how these observations are changing our understanding of GRBs.

  11. Gamma-ray detectors for breast imaging

    Science.gov (United States)

    Williams, Mark B.; Goode, Allen R.; Majewski, Stan; Steinbach, Daniela; Weisenberger, Andrew G.; Wojcik, Randolph F.; Farzanpay, Farzin

    1997-07-01

    Breast cancer is the most common cancer of American women and is the leading cause of cancer-related death among women aged 15 - 54; however recent years have shown that early detection using x-ray mammography can lead to a high probability of cure. However, because of mammography's low positive predictive value, surgical or core biopsy is typically required for diagnosis. In addition, the low radiographic contrast of many nonpalpable breast masses, particularly among women with radiographically dense breasts, results in an overall rate of 10% to 25% for missed tumors. Nuclear imaging of the breast using single gamma emitters (scintimammography) such as (superscript 99m)Tc, or positron emitters such as F-18- fluorodeoxyglucose (FDG) for positron emission tomography (PET), can provide information on functional or metabolic tumor activity that is complementary to the structural information of x-ray mammography, thereby potentially reducing the number of unnecessary biopsies and missed cancers. This paper summarizes recent data on the efficacy of scintimammography using conventional gamma cameras, and describes the development of dedicated detectors for gamma emission breast imaging. The detectors use new, high density crystal scintillators and large area position sensitive photomultiplier tubes (PSPMTs). Detector design, imaging requirements, and preliminary measured imaging performance are discussed.

  12. 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.

  13. Collimatorless imaging of gamma rays with help of gamma-ray tracking

    CERN Document Server

    Marel, J V D

    2001-01-01

    In many gamma-ray detector systems that are built for imaging purposes Compton scattered photons are suppressed as much as possible. However, the information from photons that scattered inside a detector system can be used to reconstruct the tracks of the photons with help of gamma-ray tracking. Estimates of the incident directions of the photons can be made and an image can be created. Examples of potential applications for this technique are the use as a gamma-camera in medical imaging (e.g. SPECT) or as a detector for PET. Due to the omission of collimators, much higher detection efficiencies can be achieved, reducing the doses required for an image. A gamma-ray tracking method, called backtracking, has been developed for nuclear spectroscopy. The method tracks gamma-rays originating from a point source in the center of a spherical detector system consisting of position-sensitive germanium detectors. This method can also be used as a tracking technique for imaging of an unknown source distribution. With he...

  14. Cosmic-ray and neutrino emission from Gamma-Ray Bursts with a nuclear cascade

    Energy Technology Data Exchange (ETDEWEB)

    Biehl, Daniel; Boncioli, Denise; Fedynitch, Anatoli; Winter, Walter

    2017-05-24

    We discuss neutrino and cosmic-ray emission from Gamma-Ray Bursts (GRBs) with the injection of nuclei, where we take into account that a nuclear cascade from photo-disintegration can fully develop in the source. One of our main objectives is to test if recent results from the IceCube and the Pierre Auger Observatory can be accommodated with the paradigm that GRBs are the sources of Ultra-High Energy Cosmic Rays (UHECRs). While our key results are obtained using an internal shock model, we discuss how the secondary emission from a GRB shell can be interpreted in terms of other astrophysical models. It is demonstrated that the expected neutrino flux from GRBs weakly depends on the injection composition, which implies that prompt neutrinos from GRBs can efficiently test the GRB-UHECR paradigm even if the UHECRs are nuclei. We show that the UHECR spectrum and composition, as measured by the Pierre Auger Observatory, can be self-consistently reproduced in a combined source-propagation model. In an attempt to describe the energy range including the ankle, we find tension with the IceCube bounds from the GRB stacking analyses. In an alternative scenario, where only the UHECRs beyond the ankle originate from GRBs, the requirement for a joint description of cosmic-ray and neutrino observations favors lower luminosities, which does not correspond to the typical expectation from γ-ray observations.

  15. Cosmic-ray and neutrino emission from Gamma-Ray Bursts with a nuclear cascade

    International Nuclear Information System (INIS)

    Biehl, Daniel; Boncioli, Denise; Fedynitch, Anatoli; Winter, Walter

    2017-01-01

    We discuss neutrino and cosmic-ray emission from Gamma-Ray Bursts (GRBs) with the injection of nuclei, where we take into account that a nuclear cascade from photo-disintegration can fully develop in the source. One of our main objectives is to test if recent results from the IceCube and the Pierre Auger Observatory can be accommodated with the paradigm that GRBs are the sources of Ultra-High Energy Cosmic Rays (UHECRs). While our key results are obtained using an internal shock model, we discuss how the secondary emission from a GRB shell can be interpreted in terms of other astrophysical models. It is demonstrated that the expected neutrino flux from GRBs weakly depends on the injection composition, which implies that prompt neutrinos from GRBs can efficiently test the GRB-UHECR paradigm even if the UHECRs are nuclei. We show that the UHECR spectrum and composition, as measured by the Pierre Auger Observatory, can be self-consistently reproduced in a combined source-propagation model. In an attempt to describe the energy range including the ankle, we find tension with the IceCube bounds from the GRB stacking analyses. In an alternative scenario, where only the UHECRs beyond the ankle originate from GRBs, the requirement for a joint description of cosmic-ray and neutrino observations favors lower luminosities, which does not correspond to the typical expectation from γ-ray observations.

  16. Cosmic ray and neutrino emission from gamma-ray bursts with a nuclear cascade

    Science.gov (United States)

    Biehl, D.; Boncioli, D.; Fedynitch, A.; Winter, W.

    2018-04-01

    Aim. We discuss neutrino and cosmic ray emission from gamma-ray bursts (GRBs) with the injection of nuclei, where we take into account that a nuclear cascade from photodisintegration can fully develop in the source. Our main objective is to test whether recent results from the IceCube and the Pierre Auger Observatory can be accommodated within the paradigm that GRBs are the sources of ultra-high-energy cosmic rays (UHECRs). Methods: We simulate this scenario in a combined source-propagation model. While our key results are obtained using an internal shock model of the source, we discuss how the secondary emission from a GRB shell can be interpreted in terms of other astrophysical models. Results: We demonstrate that the expected neutrino flux from GRBs weakly depends on the injection composition for the same injection spectra and luminosities, which implies that prompt neutrinos from GRBs can efficiently test the GRB-UHECR paradigm even if the UHECRs are nuclei. We show that the UHECR spectrum and composition, as measured by the Pierre Auger Observatory, can be self-consistently reproduced. In an attempt to describe the energy range including the ankle, we find tension with the IceCube bounds from the GRB stacking analyses. In an alternative scenario, where only the UHECRs beyond the ankle originate from GRBs, the requirement for a joint description of cosmic ray and neutrino observations favors lower luminosities, which does not correspond to the typical expectation from γ-ray observations.

  17. Cosmic-ray world with gamma-ray astronomy: a wealth on information, an even more open issue

    Directory of Open Access Journals (Sweden)

    Cardillo Martina

    2015-01-01

    Full Text Available Since from their discovery in 1912, Cosmic-Rays (CRs are one of the most debated issues of the high energy astrophysics. Their origin is still a fundamental problem and is the subject of very intense research. Until now, the best candidate sources of Galactic CR component are Supernova Remnants (SNRs but final proof for the origin of CRs up to the knee can only be obtained through two fundamental signatures, the detection of a clear gamma-ray signature of π0 decay in Galactic sources and the identification of sources emitting a photon spectrum up to PeV energies. Both indications are quite difficult to obtain. The two gamma-ray satellites, AGILE and Fermi, together with ground telescopes operating in the TeV energy range (HESS, VERITAS and MAGIC, collected a great amount of data from SNRs. In spite of the recent discovery of the neutral pion spectral signature in the SNR W44 spectrum by AGILE (and confirmed by Fermi-LAT, all gamma-ray data collected at GeV and TeV energies for several young and middle-aged SNRs provide interesting challenges to current theoretical models. The emerging view from gamma-ray and particle detection is intriguing and lead to revisit the CR-SNR paradigm, considering also the contribution of other kind of sources.

  18. New lithology compensated capture gamma ray system

    International Nuclear Information System (INIS)

    Peatross, R.F.

    1976-01-01

    The results of the HYDROCARBON* log after a series of field tests in which gamma rays resulting from thermal neutron capture were measured utilizing an energy analyzer and a scintillation counter of unique construction are reported. A brief discussion covers the nuclear physics required for an understanding of gamma spectral logging. Included in the explanation will be the effects of different atoms on neutrons and photons. The HYDROCARBON log utilizes these nuclear principles to record cased hole measurements and quantitatively distinguish possible productive zones from non-productive zones. Different field examples are illustrated showing the response to shaly sands, porosity and water salinity. Interpretation techniques are discussed both qualitatively and quantitatively. The HYDROCARBON log has proven to be a reliable device in the determination of water saturation in sands behind casing even when shale content and porosity are not well known. This technique is also valuable in the location of the present position of gas--oil contacts and water levels

  19. Gamma-ray induced doppler broadening

    International Nuclear Information System (INIS)

    Robinson, S.J.

    1992-01-01

    The ultra high resolving power of the GAMS4 double-flat crystal spectrometer (M.S. Dewey et al Nucl. Instrum. Methods A 284 (1989) 151.) has been used to observe the Doppler broadening of gamma-rays emitted by nuclei recoiling at speeds as low as 10 -6 c. Such recoils may be induced by the previous emission of gamma-radiation following thermal neutron capture. If the population mechanism of an excited state is known (or can be approximated) and the slowing down mechanism can be modeled, then this technique can be used to extract the lifetime of excited nuclear states. The combination of this technique and the neutron capture reaction allows the study of states which cannot necessarily be accessed by other means. This has allowed the resolution of a number of long standing questions in low-spin nuclear structure. The basis of the technique is discussed and a number of examples given

  20. The High-Energy Astrophysics Learning Center, Version 1. [CD-ROM].

    Science.gov (United States)

    Whitlock, Laura A.; Allen, Jesse S.; Lochner, James C.

    The High-Energy Astrophysics (HEA) Learning Center gives students, teachers, and the general public a window into the world of high-energy astrophysics. The universe is revealed through x-rays and gamma rays where matter exists under extreme conditions. Information is available on astrophysics at a variety of reading levels, and is illustrated…

  1. The new astrophysics

    International Nuclear Information System (INIS)

    Longair, M.

    1989-01-01

    The author offers a review of advances in astrophysics since 1945 when astronomers started to explore the universe beyond the bounds of the optical wavelength of the electromagnetic spectrum, especially in the fields of radio, x ray and gamma ray, cosmic ray, ultraviolet and infrared astronomies, as well as neutral hydrogen and molecular line studies. Theoretical and technological advances have also kept pace. An overview of the new astrophysics is offered focusing on the large-scale distribution of matter and the background microwave radiation, galaxies, stellar evolution and the interstellar media (dust, gas and high energy particles). Nucleosynthesis in stars is mentioned in a broader discussion of stellar evolution, and dead stars including supernovae. Active galaxies and quasars are discussed. After considering what should be included in astrophysical cosmology, the author looks to the future of the science. (U.K.)

  2. The measurement of gamma ray induced heating in a mixed neutron and gamma ray environment

    International Nuclear Information System (INIS)

    Chiu, H.K.

    1991-10-01

    The problem of measuring the gamma heating in a mixed DT neutron and gamma ray environment was explored. A new detector technique was developed to make this measurement. Gamma heating measurements were made in a low-Z assembly irradiated with 14-Mev neutrons and (n, n') gammas produced by a Texas Nuclear Model 9400 neutron generator. Heating measurements were made in the mid-line of the lattice using a proportional counter operating in the Continuously-varied Bias-voltage Acquisition mode. The neutron-induced signal was separated from the gamma-induced signal by exploiting the signal rise-time differences inherent to radiations of different linear energy transfer coefficient, which are observable in a proportional counter. The operating limits of this measurement technique were explored by varying the counter position in the low-Z lattice, hence changing the irradiation spectrum observed. The experiment was modelled numerically to help interpret the measured results. The transport of neutrons and gamma rays in the assembly was modelled using the one- dimensional radiation transport code ANISN/PC. The cross-section set used for these calculations was derived from the ENDF/B-V library using the code MC 2 -2 for the case of DT neutrons slowing down in a low-Z material. The calculated neutron and gamma spectra in the slab and the relevant mass-stopping powers were used to construct weighting factors which relate the energy deposition in the counter fill-gas to that in the counter wall and in the surrounding material. The gamma energy deposition at various positions in the lattice is estimated by applying these weighting factors to the measured gamma energy deposition in the counter at those locations

  3. Nuclear astrophysics lessons from INTEGRAL.

    Science.gov (United States)

    Diehl, Roland

    2013-02-01

    Measurements of high-energy photons from cosmic sources of nuclear radiation through ESA's INTEGRAL mission have advanced our knowledge: new data with high spectral resolution showed that characteristic gamma-ray lines from radioactive decays occur throughout the Galaxy in its interstellar medium. Although the number of detected sources and often the significance of the astrophysical results remain modest, conclusions derived from this unique astronomical window of radiation originating from nuclear processes are important, complementing the widely-employed atomic-line based spectroscopy. We review the results and insights obtained in the past decade from gamma-ray line measurements of cosmic sources in the context of their astrophysical questions.

  4. NRAO Teams With NASA Gamma-Ray Satellite

    Science.gov (United States)

    2007-06-01

    The National Radio Astronomy Observatory (NRAO) is teaming with NASA's upcoming Gamma-ray Large Area Space Telescope (GLAST) to allow astronomers to use both the orbiting facility and ground-based radio telescopes to maximize their scientific payoff. Under the new, streamlined process, astronomers can compete for coordinated observing time and support from both GLAST and NRAO's radio telescopes. GLAST satellite Artist's rendering of the GLAST spacecraft in orbit above the Earth. CREDIT: General Dynamics C4 Systems Click on Image for Larger File Images of NRAO Telescopes Robert C. Byrd Green Bank Telescope Very Long Baseline Array Very Large Array Atacama Large Millimeter/submillimeter Array GLAST is scheduled for launch no earlier than December 14. It will perform a survey of the entire sky at gamma-ray wavelengths every 3 hours using its primary instrument, the Large Area Telescope (LAT). NRAO operates the Very Large Array (VLA) in New Mexico, the continent-wide Very Long Baseline Array (VLBA), and the Robert C. Byrd Green Bank Telescope (GBT) in West Virginia. The NRAO is a research facility of the National Science Foundation (NSF). "Coordinated gamma-ray and radio observations of celestial objects will greatly enhance the ability to fully understand those objects. Astronomy today requires such multiwavelength studies, and this agreement paves the way for exciting, cutting-edge research," said Fred K.Y. Lo, NRAO Director. GLAST will be vastly more capable than previous gamma-ray satellites, and will carry an instrument, the GLAST Burst Monitor, specifically designed to detect gamma-ray bursts. GLAST observers will study objects such as active galaxies, pulsars, and supernova remnants, which are also readily studied with radio telescopes. By working together, NASA's GLAST mission and NSF's NRAO facilities can study flares from blazars over the widest possible range of energies, which is crucial to understanding how black holes, notorious for drawing matter in, can

  5. Exploring the Extreme Universe with the Fermi Gamma-Ray Space Telescope

    Science.gov (United States)

    Thompson, David J.; Digel, Seth W.; Racusin, Judith L.

    2012-01-01

    In ways similar to experiments in nuclear and particle physics, high-energy astrophysics usesgamma rays and energetic charged particles toprobe processes that involve large energy transfers.Since its launch in 2008, the international Fermi Gamma-Ray Space Telescope has been exploringnatural particle accelerators and the interactionsof high-energy particles in the universe. Withsources ranging from thunderstorms on Earth to galaxies and exploding stars in distant parts of the cosmos, the telescopes subjects of study are almostas diverse as were those of the scientist whose name it bears.

  6. Variable code gamma ray imaging system

    International Nuclear Information System (INIS)

    Macovski, A.; Rosenfeld, D.

    1979-01-01

    A gamma-ray source distribution in the body is imaged onto a detector using an array of apertures. The transmission of each aperture is modulated using a code such that the individual views of the source through each aperture can be decoded and separated. The codes are chosen to maximize the signal to noise ratio for each source distribution. These codes determine the photon collection efficiency of the aperture array. Planar arrays are used for volumetric reconstructions and circular arrays for cross-sectional reconstructions. 14 claims

  7. Detection circuit for gamma-ray burst

    International Nuclear Information System (INIS)

    Murakami, Hiroyuki; Yamagami, Takamasa; Mori, Kunishiro; Uchiyama, Sadayuki.

    1982-01-01

    A new gamma-ray burst detection system is described. The system was developed as an environmental monitor of an accelerator, and can be used as the burst detection system. The system detects the arrival time of burst. The difference between the arrival times detected at different places will give information on the burst source. The frequency of detecting false burst was estimated, and the detection limit under the estimated frequency of false burst was also calculated. Decision whether the signal is false or true burst was made by the statistical treatment. (Kato, T.)

  8. Gamma ray induced decomposition of lanthanide nitrates

    International Nuclear Information System (INIS)

    Joshi, N.G.; Garg, A.N.

    1992-01-01

    Gamma ray induced decomposition of the lanthanide nitrates, Ln(NO 3 ) 3 .xH 2 O where Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Tm and Yb has been studied at different absorbed doses up to 600 kGy. G(NO 2 - ) values depend on the absorbed dose and the nature of the outer cation. It has been observed that those lanthanides which exhibit variable valency (Ce and Eu) show lower G-values. An attempt has been made to correlate thermal and radiolytic decomposition processes. (author). 20 refs., 3 figs., 1 tab

  9. Very high energy gamma-ray astronomy

    International Nuclear Information System (INIS)

    Weekes, T.C.

    1989-01-01

    It is apparent that very high gamma-ray astronomy, at the very end of the electromagnetic spectrum, is just at the threshold of becoming an important channel of astronomical information. The author discusses how, to fully develop, it requires telescopes with improved minimum flux sensitivity; development of techniques that characterize the nature of the primary; more overlapping observations to remove any question of the reality of the detected phenomenon; more consistency in the application of statistics among experimenters and more openness about methods used; development of models that will predict the phenomenon to be expected rather than explain what has been observed; and more accurate calibrations to determine absolute fluxes and energies

  10. Gamma ray bursts from extragalactic sources

    Science.gov (United States)

    Hoyle, Fred; Burbidge, Geoffrey

    1992-01-01

    The properties of gamma ray bursts of classical type are found to be explicable in terms of high speed collisions between stars. A model is proposed in which the frequency of such collisions can be calculated. The model is then applied to the nuclei of galaxies in general on the basis that galaxies, or at least some fraction of them, originate in the expulsion of stars from creation centers. Evidence that low level activity of this kind is also taking place at the center of our own Galaxy is discussed. The implications for galactic evolution are discussed and a negative view of black holes is taken.

  11. Gamma ray constraints on decaying dark matter

    DEFF Research Database (Denmark)

    Cirelli, M.; Moulin, E.; Panci, P.

    2012-01-01

    We derive new bounds on decaying dark matter from the gamma ray measurements of (i) the isotropic residual (extragalactic) background by Fermi and (ii) the Fornax galaxy cluster by H.E.S.S. We find that those from (i) are among the most stringent constraints currently available, for a large range...... of dark matter masses and a variety of decay modes, excluding half-lives up to similar to 10(26) to few 10(27) seconds. In particular, they rule out the interpretation in terms of decaying dark matter of the e(+/-) spectral features in PAMELA, Fermi and H.E.S.S., unless very conservative choices...

  12. Recent developments in airborne gamma ray surveying

    International Nuclear Information System (INIS)

    Grasty, Robert L.

    1999-01-01

    Standardized procedures have been developed for converting airborne gamma ray measurements to ground concentrations of potassium, uranium and thorium. These procedures make use of an airborne calibration range whose ground concentrations should be measured with a calibrated portable spectrometer rather than by taking geochemical samples. Airborne sensitivities and height attenuation coefficients are normally determined from flights over the calibration range but may not be applicable in mountainous areas. Mathematical techniques have been now developed to reduce statistical noise in the airborne measurements by utilizing up to 256 channels of spectral information. (author)

  13. Stacked search for time shifted high energy neutrinos from gamma ray bursts with the Antares neutrino telescope

    International Nuclear Information System (INIS)

    Adrian-Martinez, S.; Ardid, M.; Felis, I.; Martinez-Mora, J.A.; Saldana, M.; Albert, A.; Drouhin, D.; Racca, C.; Andre, M.; Anghinolfi, M.; Anton, G.; Eberl, T.; Enzenhoefer, A.; Fehn, K.; Folger, F.; Geisselsoeder, S.; Geyer, K.; Gleixner, A.; Graf, K.; Hallmann, S.; Hoessl, J.; Hofestaedt, J.; James, C.W.; Kalekin, O.; Katz, U.; Kiessling, D.; Lahmann, R.; Richter, R.; Roensch, K.; Schmid, J.; Schnabel, J.; Seitz, T.; Sieger, C.; Tselengidou, M.; Wagner, S.; Aubert, J.J.; Bertin, V.; Brunner, J.; Busto, J.; Carr, J.; Costantini, H.; Coyle, P.; Dornic, D.; Mathieu, A.; Vallee, C.; Baret, B.; Barrios-Marti, J.; Hernandez-Rey, J.J.; Sanchez-Losa, A.; Toennis, C.; Zornoza, J.D.; Zuniga, J.; Basa, S.; Marcelin, M.; Nezri, E.; Biagi, S.; Coniglione, R.; Distefano, C.; Piattelli, P.; Riccobene, G.; Sapienza, P.; Trovato, A.; Bormuth, R.; Jong, M. de; Samtleben, D.F.E.; Bouwhuis, M.C.; Heijboer, A.J.; Michael, T.; Steijger, J.J.M.; Visser, E.; Bruijn, R.; Capone, A.; De Bonis, G.; Fermani, P.; Perrina, C.; Caramete, L.; Pavalas, G.E.; Popa, V.; Chiarusi, T.; Circella, M.; Creusot, A.; Galata, S.; Gracia-Ruiz, R.; Van Elewyck, V.; Dekeyser, I.; Lefevre, D.; Tamburini, C.; Deschamps, A.; Hello, Y.; Donzaud, C.; Dumas, A.; Gay, P.; Elsaesser, D.; Kadler, M.; Kreter, M.; Mueller, C.; Fusco, L.A.; Margiotta, A.; Pellegrino, C.; Spurio, M.; Giordano, V.; Haren, H. van; Hugon, C.; Taiuti, M.; Kooijman, P.; Kouchner, A.; Kreykenbohm, I.; Wilms, J.; Kulikovskiy, V.; Leonora, E.; Loucatos, S.; Marinelli, A.; Migliozzi, P.; Moussa, A.; Pradier, T.; Sanguineti, M.; Schuessler, F.; Stolarczyk, T.; Vallage, B.; Vivolo, D.

    2017-01-01

    A search for high-energy neutrino emission correlated with gamma-ray bursts outside the electromagnetic prompt-emission time window is presented. Using a stacking approach of the time delays between reported gamma-ray burst alerts and spatially coincident muon-neutrino signatures, data from the Antares neutrino telescope recorded between 2007 and 2012 are analysed. One year of public data from the IceCube detector between 2008 and 2009 have been also investigated. The respective timing profiles are scanned for statistically significant accumulations within 40 days of the Gamma Ray Burst, as expected from Lorentz Invariance Violation effects and some astrophysical models. No significant excess over the expected accidental coincidence rate could be found in either of the two data sets. The average strength of the neutrino signal is found to be fainter than one detectable neutrino signal per hundred gamma-ray bursts in the Antares data at 90% confidence level. (orig.)

  14. Stacked search for time shifted high energy neutrinos from gamma ray bursts with the Antares neutrino telescope

    Energy Technology Data Exchange (ETDEWEB)

    Adrian-Martinez, S.; Ardid, M.; Felis, I.; Martinez-Mora, J.A.; Saldana, M. [Universitat Politecnica de Valencia, Institut d' Investigacio per a la Gestio Integrada de les Zones Costaneres (IGIC), Gandia (Spain); Albert, A.; Drouhin, D.; Racca, C. [GRPHE-Institut Universitaire de Technologie de Colmar, 34 rue du Grillenbreit, BP 50568, Colmar (France); Andre, M. [Technical University of Catalonia, Laboratory of Applied Bioacoustics, Vilanova i la Geltru, Barcelona (Spain); Anghinolfi, M. [INFN-Sezione di Genova, Genoa (Italy); Anton, G.; Eberl, T.; Enzenhoefer, A.; Fehn, K.; Folger, F.; Geisselsoeder, S.; Geyer, K.; Gleixner, A.; Graf, K.; Hallmann, S.; Hoessl, J.; Hofestaedt, J.; James, C.W.; Kalekin, O.; Katz, U.; Kiessling, D.; Lahmann, R.; Richter, R.; Roensch, K.; Schmid, J.; Schnabel, J.; Seitz, T.; Sieger, C.; Tselengidou, M.; Wagner, S. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Erlangen Centre for Astroparticle Physics, Erlangen (Germany); Aubert, J.J.; Bertin, V.; Brunner, J.; Busto, J.; Carr, J.; Costantini, H.; Coyle, P.; Dornic, D.; Mathieu, A.; Vallee, C. [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Baret, B.; Barrios-Marti, J.; Hernandez-Rey, J.J.; Sanchez-Losa, A.; Toennis, C.; Zornoza, J.D.; Zuniga, J. [CSIC-Universitat de Valencia, IFIC-Instituto de Fisica Corpuscular, Edificios Investigacion de Paterna, Paterna, Valencia (Spain); Basa, S.; Marcelin, M.; Nezri, E. [Pole de l' Etoile Site de Chateau-Gombert, LAM-Laboratoire d' Astrophysique de Marseille, Marseille Cedex 13 (France); Biagi, S.; Coniglione, R.; Distefano, C.; Piattelli, P.; Riccobene, G.; Sapienza, P.; Trovato, A. [INFN-Laboratori Nazionali del Sud (LNS), Catania (Italy); Bormuth, R.; Jong, M. de; Samtleben, D.F.E. [Nikhef, Science Park, Amsterdam (Netherlands); Universiteit Leiden, Leids Instituut voor Onderzoek in Natuurkunde, Leiden (Netherlands); Bouwhuis, M.C.; Heijboer, A.J.; Michael, T.; Steijger, J.J.M.; Visser, E. [Nikhef, Science Park, Amsterdam (Netherlands); Bruijn, R. [Nikhef, Science Park, Amsterdam (Netherlands); Universiteit van Amsterdam, Instituut voor Hoge-Energie Fysica, Amsterdam (Netherlands); Capone, A.; De Bonis, G.; Fermani, P.; Perrina, C. [INFN-Sezione di Roma, Rome (Italy); Dipartimento di Fisica dell' Universita La Sapienza, Rome (Italy); Caramete, L.; Pavalas, G.E.; Popa, V. [Institute for Space Sciences, Bucharest, Magurele (Romania); Chiarusi, T. [INFN-Sezione di Bologna, Bologna (Italy); Circella, M. [INFN-Sezione di Bari, Bari (Italy); Creusot, A.; Galata, S.; Gracia-Ruiz, R.; Van Elewyck, V. [APC, Universite Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cite, Paris (France); Dekeyser, I.; Lefevre, D.; Tamburini, C. [Aix-Marseille University, Mediterranean Institute of Oceanography (MIO), Marseille Cedex 9 (France); Universite du Sud Toulon-Var, CNRS-INSU/IRD UM 110, La Garde Cedex (France); Deschamps, A.; Hello, Y. [Geoazur, Universite Nice Sophia-Antipolis, CNRS/INSU, IRD, Observatoire de la Cote d' Azur, Sophia Antipolis (France); Donzaud, C. [APC, Universite Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cite, Paris (France); Universite Paris-Sud, Orsay Cedex (France); Dumas, A.; Gay, P. [Clermont Universite, Universite Blaise Pascal, CNRS/IN2P3, Laboratoire de Physique Corpusculaire, BP 10448, Clermont-Ferrand (France); Elsaesser, D.; Kadler, M.; Kreter, M.; Mueller, C. [Universitaet Wuerzburg, Institut fuer Theoretische Physik und Astrophysik, Wuerzburg (Germany); Fusco, L.A.; Margiotta, A.; Pellegrino, C.; Spurio, M. [INFN-Sezione di Bologna, Bologna (Italy); Dipartimento di Fisica dell' Universita, Bologna (Italy); Giordano, V. [INFN-Sezione di Catania, Catania (Italy); Haren, H. van [Royal Netherlands Institute for Sea Research (NIOZ), ' t Horntje, Texel (Netherlands); Hugon, C.; Taiuti, M. [INFN-Sezione di Genova, Genoa (Italy); Dipartimento di Fisica dell' Universita, Genoa (Italy); Kooijman, P. [Nikhef, Science Park, Amsterdam (Netherlands); Universiteit Utrecht, Faculteit Betawetenschappen, Utrecht (Netherlands); Universiteit van Amsterdam, Instituut voor Hoge-Energie Fysica, Amsterdam (Netherlands); Kouchner, A. [APC, Universite Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cite, Paris (France); Institut Universitaire de France, Paris (France); Kreykenbohm, I.; Wilms, J. [Universitaet Erlangen-Nuernberg, Dr. Remeis-Sternwarte and ECAP, Bamberg (Germany); Kulikovskiy, V. [INFN-Laboratori Nazionali del Sud (LNS), Catania (Italy); Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation); Leonora, E. [INFN-Sezione di Catania, Catania (Italy); Dipartimento di Fisica ed Astronomia dell' Universita, Catania (Italy); Loucatos, S. [APC, Universite Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cite, Paris (France); CEA Saclay, Direction des Sciences de la Matiere, Institut de recherche sur les lois fondamentales de l' Univers, Service de Physique des Particules, Gif-sur-Yvette Cedex (France); Marinelli, A. [INFN-Sezione di Pisa, Pisa (Italy); Dipartimento di Fisica dell' Universita, Pisa (Italy); Migliozzi, P. [INFN-Sezione di Napoli, Naples (IT); Moussa, A. [University Mohammed I, Laboratory of Physics of Matter and Radiations, Oujda (MA); Pradier, T. [Universite de Strasbourg et CNRS/IN2P3, IPHC-Institut Pluridisciplinaire Hubert Curien, 23 rue du Loess, BP 28, Strasbourg Cedex 2 (FR); Sanguineti, M. [Dipartimento di Fisica dell' Universita, Genoa (IT); Schuessler, F.; Stolarczyk, T.; Vallage, B. [CEA Saclay, Direction des Sciences de la Matiere, Institut de recherche sur les lois fondamentales de l' Univers, Service de Physique des Particules, Gif-sur-Yvette Cedex (FR); Vivolo, D. [INFN-Sezione di Napoli, Naples (IT); Dipartimento di Fisica dell' Universita Federico II di Napoli, Naples (IT)

    2017-01-15

    A search for high-energy neutrino emission correlated with gamma-ray bursts outside the electromagnetic prompt-emission time window is presented. Using a stacking approach of the time delays between reported gamma-ray burst alerts and spatially coincident muon-neutrino signatures, data from the Antares neutrino telescope recorded between 2007 and 2012 are analysed. One year of public data from the IceCube detector between 2008 and 2009 have been also investigated. The respective timing profiles are scanned for statistically significant accumulations within 40 days of the Gamma Ray Burst, as expected from Lorentz Invariance Violation effects and some astrophysical models. No significant excess over the expected accidental coincidence rate could be found in either of the two data sets. The average strength of the neutrino signal is found to be fainter than one detectable neutrino signal per hundred gamma-ray bursts in the Antares data at 90% confidence level. (orig.)

  15. The First Fermi-LAT Gamma-Ray Burst Catalog

    NARCIS (Netherlands)

    Ackermann, M.; et al., [Unknown; van der Horst, A.J.

    2013-01-01

    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy (gsim 20 MeV) γ-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected

  16. Gamma ray bursts observed with WATCH‐EURECA

    DEFF Research Database (Denmark)

    Brandt, Søren; Lund, Niels; Castro-Tirado, A. J.

    1994-01-01

    The WATCH wide field x‐ray monitor has the capability of independently locating bright Gamma Ray Bursts to 1° accuracy. We report the preliminary positions of 12 Gamma Ray Bursts observed with the WATCH monitor flown on the ES spacecraft EURECA during its 11 month mission. Also the recurrence...

  17. X and gamma ray backgroud observations in Antarctic

    International Nuclear Information System (INIS)

    Jayanthi, U.B.

    1988-01-01

    Atmospheric X amd gamma rays are products of complex electromagnetic interation between charged particles and atmospheric constituents. The latitudinal dependence of the cosmic rays secondaries, auroral and South Atlantic Anomaly phenomena produce flux variations, especially the later temporal flux variations. We propose to discuss these variations in relevance to balloon flight observations of X and gamma ray atmospheric background at polar latitudes. (author) [pt

  18. Observation of solar gamma-ray by Hinotori

    International Nuclear Information System (INIS)

    Yoshimori, Masato; Okudaira, Kiyoaki; Hirashima, Yo; Kondo, Ichiro.

    1982-01-01

    The solar gamma-ray emitted by solar flare was observed. The gamma-ray is the electromagnetic radiation with the energy more than 300 keV. The line gamma-ray intensity and the time profile were observed. The gamma-ray detector CsI (Tl) was loaded on Hinotori, and the observed gamma-ray was analyzed by a multi-channel analyzer. The observed line gamma-ray was the radiation from Fe-56 and Ne-20. The line gamma-ray from C-12 and O-16 was also seen. These gamma-ray is the direct evidence of the nuclear reaction on the sun. The observed spectrum suggested the existence of the lines from Mg-24 and Si-28. The intensity of the 2.22 MeV gamma-line was small. This fact showed that the origin of this line was different from other nuclear gamma-ray. Two kinds of hard X-ray bursts were detected. The one was impulsive burst, and the other was gradual burst. There was no time difference between the hard X-ray and the gamma-ray of the impulsive burst. The impulsive burst may be explained by the beam model. The delay of time profile in the high energy gamma-ray of the gradual burst was observed. This means that the time when accelerated electrons cause bremsstrahlung depends on the electron energy. The long trapping of electrons at the top of magnetic loop is suggested. (Kato, T.)

  19. Nebulae of young pulsars: emitters of TeV neutrinos and gamma-rays

    International Nuclear Information System (INIS)

    Das, Manabindu; Dey, Rajat K.

    2015-01-01

    High-energy neutrinos are expected to be produced in astrophysical objects by the decays of charged pions made in cosmic-ray interactions with surrounding photons and/or matter. As these pions decay, they produce neutrinos with typical energies of 5% compared to those of the cosmic-ray nucleons. These neutrinos can travel long distances undisturbed by either the absorption experienced by high-energy photons or the magnetic deflection experienced by charged particles, making them a unique tracer of cosmic-ray acceleration. Hence neutrinos are considered to be important probes for exploring the high energy Universe, and they may fill the missing link between the TeV gamma-rays and the PeV - EeV cosmic-rays. At the same time, neutrinos produced in cosmic-ray air showers provide information about hadronic physics in kinematic regions that are difficult to probe with terrestrial accelerators

  20. Observation of gamma-ray bursts with GINGA

    International Nuclear Information System (INIS)

    Murakami, Toshio; Fujii, Masami; Nishimura, Jun

    1989-01-01

    Gamma-ray Burst Detector System (GBD) on board the scientific satellite 'GINGA' which was launched on Feb. 5, 1987, was realized as an international cooperation between ISAS and LANL. It has recorded more than 40 Gamma-Ray Burst candidates during 20 months observation. Although many observational evidences were accumulated in past 20 years after the discovery of gamma-ray burst by LANL scientists, there are not enough evidence to determine the origin and the production mechanism of the gamma-ray burst. GBD consists of a proportional counter and a NaI scintillation counter so that it became possible to observe energy spectrum of the gamma-ray burst with high energy resolution over wide range of energy (1.5-380 keV) together with high time resolution. As the result of observation, the following facts are obtained: (1) A large fraction of observed gamma-ray bursts has a long X-ray tail after the harder part of gamma-ray emission has terminated. (2) Clear spectral absorption features with harmonic in energy was observed in some of the energy spectrum of gamma-ray bursts. These evidences support the hypothesis that the strongly magnetized neutron star is the origin of gamma-ray burst. (author)

  1. Review of GRANAT observations of gamma-ray bursts

    DEFF Research Database (Denmark)

    Terekhov, O.; Denissenko, D.; Sunyaev, R.

    1995-01-01

    The GRANAT observatory was launched into a high apogee orbit on 1 December, 1989. Three instruments onboard GRANAT - PHEBUS, WATCH and SIGMA are able to detect gamma-ray bursts in a very broad energy range from 6 keV up to 100 MeV. Over 250 gamma-ray bursts were detected. We discuss the results...... of the observations of the time histories and spectral evolution of the detected events provided by the different instruments in different energy ranges. Short Gamma-Ray Bursts ( 2 s) events. Evidence of the existence...... of four differently behaving componenents in gamma-ray burst spectra is discussed. Statistical properties of the gamma-ray burst sources based on the 5 years of observations with (∼ 10−6 erg/cm2) sensitivity as well as the results of high sensitivity (∼ 10−8 erg/cm2) search for Gamma-Ray Bursts within...

  2. Microwave-gamma ray water in crude monitor

    International Nuclear Information System (INIS)

    Paap, H.J.

    1984-01-01

    A microwave-gamma ray water-in-crude monitoring system measures the percent quantity of fresh water or salt water in crude oil flowing in a pipe line. The system includes a measuring cell arranged with the pipe line so that the crude oil flows through the measuring cell. A microwave transmitter subsystem and a gamma ray source are arranged with the measuring cell so that microwave energy and gamma rays are transmitted through the measuring cell. A microwave receiving subsystem and a gamma ray detector provide signals corresponding to received microwave energy and to the received gamma rays, respectively. Apparatus connected to the microwave receiver and to the gamma ray detector provides an indication of the percentage of water in the crude oil

  3. Gamma ray sensitivity of superheated liquid

    International Nuclear Information System (INIS)

    Sawamura, Teruko; Sugiyama, Noriyuki; Narita, Masakuni

    2000-01-01

    The superheated drop detector (SDD) is composed of droplets of sensitive liquid with a low-boiling point and a medium supporting the dispersed droplets throughout the medium. The SDD has been mainly used for neutron dosimetry and recently also for gamma-rays. While for neutrons the conditions for bubble formation have been discussed, there has been little work for gamma-rays. We investigated the conditions for low LET radiation, such as protons and gamma-rays, and showed octafluoropropane (C 3 F 8 , boiling point -36.7degC) as advantageous liquid. The bubble formation condition is given by the energy density imparted from the charged particle to the sensitive liquid. The energy density requirement means that the energy must be deposited over a definite region length, effective to produce the vapor nucleus that becomes the visible bubble. Recently for γ-rays, Evans and Wang proposed the model that the vaporization was triggered by the energy deposition in a 'cluster' including many events in proximity in a superheated liquid. Measurements of the γ-ray sensitivity have not been sufficiently carried out and therefore the effective length or the cluster model has not been well-established. In this study the detection sensitivity was evaluated by measuring the life time of a liquid drop exposed to γ-rays. We developed a device trapping a superheated drop, where a single drop of test liquid was trapped and decompressed by an acoustic standing wave field. When a liquid drop with volume V[cm 3 ] is exposed to a γ-ray flux φ γ [cm -2 s -1 ], the average evaporation rate λ(T, P) [s -1 ] (T: temperature, P: decompressed pressure) is expressed as λ(T, P)=K γ Vφ γ (1), K γ [cm -1 ] is the γ-ray detection sensitivity per unit volume of the sensitive liquid and unit fluence. If the average rate of spontaneous evaporation is λ 0 (T, P), then the probability distribution of the life time t, the probability that t > τ, is expressed by X(τ)=exp{-(λ+λ 0 )

  4. SYSTEMATIC STUDY OF GAMMA-RAY-BRIGHT BLAZARS WITH OPTICAL POLARIZATION AND GAMMA-RAY VARIABILITY

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Ryosuke; Fukazawa, Yasushi; Kanda, Yuka; Shiki, Kensei; Kawabata, Miho; Nakaoka, Tatsuya; Takaki, Katsutoshi; Takata, Koji; Ui, Takahiro [Department of Physical Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Nalewajko, Krzysztof; Madejski, Greg M. [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road M/S 29, Menlo Park, CA 94025 (United States); Uemura, Makoto; Tanaka, Yasuyuki T.; Kawabata, Koji S.; Akitaya, Hiroshi; Ohsugi, Takashi [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Schinzel, Frank K. [Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131 (United States); Moritani, Yuki [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Sasada, Mahito [Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Yamanaka, Masayuki, E-mail: itoh@hep01.hepl.hiroshima-u.ac.jp, E-mail: itoh@hp.phys.titech.ac.jp [Department of Physics, Faculty of Science and Engineering, Konan University, Okamoto, Kobe, Hyogo 658-8501 (Japan); and others

    2016-12-10

    Blazars are highly variable active galactic nuclei that emit radiation at all wavelengths from radio to gamma rays. Polarized radiation from blazars is one key piece of evidence for synchrotron radiation at low energies, and it also varies dramatically. The polarization of blazars is of interest for understanding the origin, confinement, and propagation of jets. However, even though numerous measurements have been performed, the mechanisms behind jet creation, composition, and variability are still debated. We performed simultaneous gamma-ray and optical photopolarimetry observations of 45 blazars between 2008 July and 2014 December to investigate the mechanisms of variability and search for a basic relation between the several subclasses of blazars. We identify a correlation between the maximum degree of optical linear polarization and the gamma-ray luminosity or the ratio of gamma-ray to optical fluxes. Since the maximum polarization degree depends on the condition of the magnetic field (chaotic or ordered), this result implies a systematic difference in the intrinsic alignment of magnetic fields in parsec-scale relativistic jets between different types of blazars (flat-spectrum radio quasars vs. BL Lacs) and consequently between different types of radio galaxies (FR I versus FR II).

  5. Near stellar sources of gamma-ray bursts

    OpenAIRE

    Luchkov, B. I.; Markin, P. D.

    2012-01-01

    Correlation analysis of gamma-ray burst coordinates and nearby stars, registered on 2008-2011, revealed 5 coincidences with angular accuracy better than 0.1 degree. The random probability is $7\\times 10^{-7}$, so evidencing that coincident stars are indeed gamma-ray burst sources. The proposed method should be continued in order to provide their share in common balance of cosmic gamma-ray bursts.

  6. Fermi GBM Observations of Terrestrial Gamma-Ray Flashes

    Science.gov (United States)

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

    2010-01-01

    This slide presentation explores the relationship between Terrestrial Gamma-Ray Flashes (TGF) and lightning. Using data from the World-Wide Lightning Location Network (WWLLN), and the gamma ray observations from Fermi's Gamma-ray Burst Monitor (GBM), the study reviews any causal relationship between TGFs and lightning. The conclusion of the study is that the TGF and lightning are simultaneous with out a causal relationship.

  7. Sensitivity of Gamma-Ray Detectors to Polarization

    OpenAIRE

    Yadigaroglu, I. -A.

    1996-01-01

    Previous studies have shown that the largest gamma-ray detector to date, EGRET, does not have useful polarization sensitivity. We have explored here some improved approaches to analyzing gamma-ray pair production events, leading to important gains in sensitivity to polarization. The performance of the next generation gamma-ray instrument GLAST is investigated using a detailed Monte Carlo simulation of the complete detector.

  8. Portable high energy gamma ray imagers

    International Nuclear Information System (INIS)

    Guru, S.V.; Squillante, M.R.

    1996-01-01

    To satisfy the needs of high energy gamma ray imagers for industrial nuclear imaging applications, three high energy gamma cameras are presented. The RMD-Pinhole camera uses a lead pinhole collimator and a segmented BGO detector viewed by a 3 in. square position sensitive photomultiplier tube (PSPMT). This pinhole gamma camera displayed an energy resolution of 25.0% FWHM at the center of the camera at 662 keV and an angular resolution of 6.2 FWHM at 412 keV. The fixed multiple hole collimated camera (FMCC), used a multiple hole collimator and a continuous slab of NaI(Tl) detector viewed by the same PSPMT. The FMCC displayed an energy resolution of 12.4% FWHM at 662 keV at the center of the camera and an angular resolution of 6.0 FWHM at 412 keV. The rotating multiple hole collimated camera (RMCC) used a 180 antisymmetric rotation modulation collimator and CsI(Tl) detectors coupled to PIN silicon photodiodes. The RMCC displayed an energy resolution of 7.1% FWHM at 662 keV and an angular resolution of 4.0 FWHM at 810 keV. The performance of these imagers is discussed in this paper. (orig.)

  9. Line and continuum spectroscopy as diagnostic tools for gamma ray bursts

    International Nuclear Information System (INIS)

    Liang, E.P.

    1990-12-01

    We review the theoretical framework of both line and continuum spectra formation in gamma ray bursts. These include the cyclotron features at 10's of keV, redshifted annihilation features at ∼400 keV, as well as other potentially detectable nuclear transition lines, atomic x-ray lines, proton cyclotron lines and plasma oscillation lines. By combining the parameters derived from line and continuum modeling we can try to reconstruct the location, geometry and physical conditions of the burst emission region, thereby constraining and discriminating the astrophysical models. Hence spectroscopy with current and future generations of detectors should provide powerful diagnostic tools for gamma ray bursters. 48 refs., 10 figs., 4 tabs

  10. ICF gamma-ray reaction history diagnostics

    International Nuclear Information System (INIS)

    Herrmann, H W; Young, C S; Mack, J M; Kim, Y H; McEvoy, A; Evans, S; Sedillo, T; Batha, S; Schmitt, M; Wilson, D C; Langenbrunner, J R; Malone, R; Kaufman, M I; Cox, B C; Frogget, B; Tunnell, T W; Miller, E K; Ali, Z A; Stoeffl, W; Horsfield, C J

    2010-01-01

    Reaction history measurements, such as nuclear bang time and burn width, are fundamental components of diagnosing ICF implosions and will be employed to help steer the National Ignition Facility (NIF) towards ignition. Fusion gammas provide a direct measure of nuclear interaction rate (unlike x-rays) without being compromised by Doppler spreading (unlike neutrons). Gas Cherenkov Detectors that convert fusion gamma rays to UV/visible Cherenkov photons for collection by fast optical recording systems have established their usefulness in illuminating ICF physics in several experimental campaigns at OMEGA. In particular, bang time precision better than 25 ps has been demonstrated, well below the 50 ps accuracy requirement defined by the NIF. NIF Gamma Reaction History (GRH) diagnostics are being developed based on optimization of sensitivity, bandwidth, dynamic range, cost, and NIF-specific logistics, requirements and extreme radiation environment. Implementation will occur in two phases. The first phase consists of four channels mounted to the outside of the target chamber at ∼6 m from target chamber center (GRH-6m) coupled to ultra-fast photo-multiplier tubes (PMT). This system is intended to operate in the 10 13 -10 17 neutron yield range expected during the early THD campaign. It will have high enough bandwidth to provide accurate bang times and burn widths for the expected THD reaction histories (> 80 ps fwhm). Successful operation of the first GRH-6m channel has been demonstrated at OMEGA, allowing a verification of instrument sensitivity, timing and EMI/background suppression. The second phase will consist of several channels located just inside the target bay shield wall at 15 m from target chamber center (GRH-15m) with optical paths leading through the cement shield wall to well-shielded streak cameras and PMTs. This system is intended to operate in the 10 16 -10 20 yield range expected during the DT ignition campaign, providing higher temporal resolution

  11. ICF gamma-ray reaction history diagnostics

    Science.gov (United States)

    Herrmann, H. W.; Young, C. S.; Mack, J. M.; Kim, Y. H.; McEvoy, A.; Evans, S.; Sedillo, T.; Batha, S.; Schmitt, M.; Wilson, D. C.; Langenbrunner, J. R.; Malone, R.; Kaufman, M. I.; Cox, B. C.; Frogget, B.; Miller, E. K.; Ali, Z. A.; Tunnell, T. W.; Stoeffl, W.; Horsfield, C. J.; Rubery, M.

    2010-08-01

    Reaction history measurements, such as nuclear bang time and burn width, are fundamental components of diagnosing ICF implosions and will be employed to help steer the National Ignition Facility (NIF) towards ignition. Fusion gammas provide a direct measure of nuclear interaction rate (unlike x-rays) without being compromised by Doppler spreading (unlike neutrons). Gas Cherenkov Detectors that convert fusion gamma rays to UV/visible Cherenkov photons for collection by fast optical recording systems have established their usefulness in illuminating ICF physics in several experimental campaigns at OMEGA. In particular, bang time precision better than 25 ps has been demonstrated, well below the 50 ps accuracy requirement defined by the NIF. NIF Gamma Reaction History (GRH) diagnostics are being developed based on optimization of sensitivity, bandwidth, dynamic range, cost, and NIF-specific logistics, requirements and extreme radiation environment. Implementation will occur in two phases. The first phase consists of four channels mounted to the outside of the target chamber at ~6 m from target chamber center (GRH-6m) coupled to ultra-fast photo-multiplier tubes (PMT). This system is intended to operate in the 1013-1017 neutron yield range expected during the early THD campaign. It will have high enough bandwidth to provide accurate bang times and burn widths for the expected THD reaction histories (> 80 ps fwhm). Successful operation of the first GRH-6m channel has been demonstrated at OMEGA, allowing a verification of instrument sensitivity, timing and EMI/background suppression. The second phase will consist of several channels located just inside the target bay shield wall at 15 m from target chamber center (GRH-15m) with optical paths leading through the cement shield wall to well-shielded streak cameras and PMTs. This system is intended to operate in the 1016-1020 yield range expected during the DT ignition campaign, providing higher temporal resolution for the

  12. GRAP, Gamma-Ray Level-Scheme Assignment

    International Nuclear Information System (INIS)

    Franklyn, C.B.

    2002-01-01

    1 - Description of program or function: An interactive program for allocating gamma-rays to an energy level scheme. Procedure allows for searching for new candidate levels of the form: 1) L1 + G(A) + G(B) = L2; 2) G(A) + G(B) = G(C); 3) G(A) + G(B) = C (C is a user defined number); 4) L1 + G(A) + G(B) + G(C) = L2. Procedure indicates intensity balance of feed and decay of each energy level. Provides for optimization of a level energy (and associated error). Overall procedure allows for pre-defining of certain gamma-rays as belonging to particular regions of the level scheme, for example, high energy transition levels, or due to beta- decay. 2 - Method of solution: Search for cases in which the energy difference between two energy levels is equal to a gamma-ray energy within user-defined limits. 3 - Restrictions on the complexity of the problem: Maximum number of gamma-rays: 999; Maximum gamma ray energy: 32000 units; Minimum gamma ray energy: 10 units; Maximum gamma-ray intensity: 32000 units; Minimum gamma-ray intensity: 0.001 units; Maximum number of levels: 255; Maximum level energy: 32000 units; Minimum level energy: 10 units; Maximum error on energy, intensity: 32 units; Minimum error on energy, intensity: 0.001 units; Maximum number of combinations: 6400 (ca); Maximum number of gamma-ray types : 127

  13. High-energy gamma-ray emission in compact binaries

    International Nuclear Information System (INIS)

    Cerutti, Benoit

    2010-01-01

    Four gamma-ray sources have been associated with binary systems in our Galaxy: the micro-quasar Cygnus X-3 and the gamma-ray binaries LS I +61 degrees 303, LS 5039 and PSR B1259-63. These systems are composed of a massive companion star and a compact object of unknown nature, except in PSR B1259-63 where there is a young pulsar. I propose a comprehensive theoretical model for the high-energy gamma-ray emission and variability in gamma-ray emitting binaries. In this model, the high-energy radiation is produced by inverse Compton scattering of stellar photons on ultra-relativistic electron-positron pairs injected by a young pulsar in gamma-ray binaries and in a relativistic jet in micro-quasars. Considering anisotropic inverse Compton scattering, pair production and pair cascade emission, the TeV gamma-ray emission is well explained in LS 5039. Nevertheless, this model cannot account for the gamma-ray emission in LS I +61 degrees 303 and PSR B1259-63. Other processes should dominate in these complex systems. In Cygnus X-3, the gamma-ray radiation is convincingly reproduced by Doppler-boosted Compton emission of pairs in a relativistic jet. Gamma-ray binaries and micro-quasars provide a novel environment for the study of pulsar winds and relativistic jets at very small spatial scales. (author)

  14. Gamma-ray spectroscopy on irradiated fuel rods

    International Nuclear Information System (INIS)

    Terremoto, Luis Antonio Albiac

    2009-01-01

    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)

  15. Fermi Large Area Telescope Bright Gamma-ray Source List

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /KIPAC, Menlo Park /SLAC; Ajello, M.; /KIPAC, Menlo Park /SLAC; Atwood, W.B.; /UC, Santa Cruz; Axelsson, M.; /Stockholm U., OKC /Stockholm U.; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Band, D.L.; /NASA, Goddard /NASA, Goddard; Barbiellini, Guido; /INFN, Trieste /Trieste U.; Bastieri, Denis; /INFN, Padua /Padua U.; Bechtol, K.; /KIPAC, Menlo Park /SLAC; Bellazzini, R.; /INFN, Pisa; Berenji, B.; /KIPAC, Menlo Park /SLAC; Bignami, G.F.; /Pavia U.; Bloom, Elliott D.; /KIPAC, Menlo Park /SLAC; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /KIPAC, Menlo Park /SLAC; Bregeon, J.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Burnett, Thompson H.; /Washington U., Seattle /Bari U. /INFN, Bari /KIPAC, Menlo Park /SLAC /IASF, Milan /IASF, Milan /DAPNIA, Saclay /ASDC, Frascati /INFN, Perugia /Perugia U. /KIPAC, Menlo Park /SLAC /George Mason U. /Naval Research Lab, Wash., D.C. /NASA, Goddard /KIPAC, Menlo Park /SLAC /INFN, Perugia /Perugia U. /KIPAC, Menlo Park /SLAC /Montpellier U. /Sonoma State U. /Stockholm U., OKC /Royal Inst. Tech., Stockholm /Stockholm U. /KIPAC, Menlo Park /SLAC /ASDC, Frascati /NASA, Goddard /Maryland U. /Naval Research Lab, Wash., D.C. /INFN, Trieste /Pavia U. /Bari U. /INFN, Bari /KIPAC, Menlo Park /SLAC /UC, Santa Cruz /KIPAC, Menlo Park /SLAC /KIPAC, Menlo Park /SLAC /KIPAC, Menlo Park /SLAC /Montpellier U. /Bari U. /INFN, Bari /Ecole Polytechnique /NASA, Goddard; /more authors..

    2009-05-15

    Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the {gamma}-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than {approx}10{sigma}) {gamma}-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) {gamma}-ray sources in the early mission data.

  16. Gamma rays from pulsar outer gaps

    International Nuclear Information System (INIS)

    Chiang, J.; Romani, R.W.; Cheng Ho

    1993-01-01

    We describe a gamma ray pulsar code which computes the high energy photon emissivities from vacuum gaps in the outer magnetosphere, after the model outlined by Cheng, Ho and Ruderman (1986) and Ho (1989). Pair-production due to photon-photon interactions and radiation processes including curvature, synchrotron and inverse Compton processes are computed with an iterative scheme which converges to self-consistent photon and particle distributions for a sampling of locations in the outer magnetosphere. We follow the photons from these distributions as they propagate through the pulsar magnetosphere toward a distant observer. We include the effects of relativistic aberration, time-of-flight delays and reabsorption by photon-photon pair-production to determine an intensity map of the high energy pulsar emission on the sky. Using data from radio and optical observations to constrain the geometry of the magnetosphere as well as the possible observer viewing angles, we derive light curves and phase dependent spectra which can be directly compared to data from the Compton Observatory. Observations for Crab, Vela and the recently identified gamma ray pulsars Geminga, PSR1706-44 aNd PSR 1509-58 will provide important tests of our model calculations, help us to improve our picture of the relevant physics at work in pulsar magnetospheres and allow us to comment on the implications for future pulsar discoveries

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

    International Nuclear Information System (INIS)

    Trombka, J.I.; Boynton, W.V.; Brueckner, J.; Squyres, S.; Clark, P.E.; Starr, R.; Evans, L.G.; Floyd, S.R.; McClanahan, T.P.; Goldsten, J.; Mcnutt, R.; Schweitzer, J.S.

    1999-01-01

    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

  18. High dose gamma-ray standard

    International Nuclear Information System (INIS)

    Macrin, R.; Moraru, R.

    1999-01-01

    The high gamma-ray doses produced in a gamma irradiator are used, mainly, for radiation processing, i.e. sterilization of medical products, processing of food, modifications of polymers, irradiation of electronic devices, a.s.o. The used absorbed doses depend on the application and cover the range 10 Gy to 100 MGy. The regulations in our country require that the response of the dosimetry systems, used for the irradiation of food and medical products, be calibrated and traceable to the national standards. In order to be sure that the products receive the desired absorbed dose, appropriate dosimetric measurements must be performed, including the calibration of the dosemeters and their traceability to the national standards. The high dose gamma-ray measurements are predominantly based on the use of reference radiochemical dosemeters. Among them the ferrous sulfate can be used as reference dosemeter for low doses (up to 400 Gy) but due to its characteristics it deserves to be considered a standard dosemeter and to be used for transferring the conventional absorbed dose to other chemical dosemeters used for absorbed doses up to 100 MGy. The study of the ferrous sulfate dosemeter consisted in preparing many batches of solution by different operators in quality assurance conditions and in determining for all batches the linearity, the relative intrinsic error, the repeatability and the reproducibility. The principal results are the following: the linear regression coefficient: 0.999, the relative intrinsic error: max.6 %, the repeatability (for P* = 95 %): max.3 %, the reproducibility (P* = 95%): max.5 %. (authors)

  19. Activation of wine bentonite with gamma rays

    International Nuclear Information System (INIS)

    Goranov, N.; Antonov, M.

    1997-01-01

    The action of gamma rays on wine bentonite as well as influence of its adsorption and technologic qualities on the composition and stability of wines against protein darkening and precipitation has been studied. The experiments were carried out with wine bentonite produced in the firm Bentonite and irradiated with doses of 0.4, 0.6, 0.8 and 1.0 MR. White and red wines have been treated with irradiated bentonite under laboratory conditions at 1.0 g/dm 3 . All samples are treated at the same conditions. The flocculation rate of the sediment was determined visually. Samples have been taken 24 h later from the cleared wine layers. The following parameters have been determined: clarification, filtration rate, phenolic compounds, calcium, colour intensity, total extracted substances, etc. The volume of the sediment has been determined also. The control samples have been taken from the same unirradiated wines. The results showed better and faster clarification in on the third, the 20th and the 24th hours with using of gamma-irradiated at doses 0.8 and 1.0 MR. The sediment was the most compact and its volume - the smallest compared to the samples treated with bentonite irradiated with doses of 0.6 and 0.4 MR. This ensures a faster clarification and better filtration of treated wines. The bentonite activated with doses of 0.8 and 1.0 MR adsorbs the phenolic compounds and the complex protein-phenolic molecules better. In the same time it adsorbs less extracted substances compared to untreated bentonite and so preserves all organoleptic properties of wine. The irradiated bentonite adsorbs less the monomers of anthocyan compounds which ensures brighter natural colour of wine. The gamma-rays activation consolidates calcium in the crystal lattice of bentonite particles and in this way eliminates the formation of crystal precipitates

  20. Very high-frequency gravitational waves from magnetars and gamma-ray bursts

    Science.gov (United States)

    Wen, Hao; Li, Fang-Yu; Li, Jin; Fang, Zhen-Yun; Beckwith, Andrew

    2017-12-01

    Extremely powerful astrophysical electromagnetic (EM) systems could be possible sources of high-frequency gravitational waves (HFGWs). Here, based on properties of magnetars and gamma-ray bursts (GRBs), we address “Gamma-HFGWs” (with very high-frequency around 1020 Hz) caused by ultra-strong EM radiation (in the radiation-dominated phase of GRB fireballs) interacting with super-high magnetar surface magnetic fields (˜1011 T). By certain parameters of distance and power, the Gamma-HFGWs would have far field energy density Ω gw around 10-6, and they would cause perturbed signal EM waves of ˜10-20 W/m2 in a proposed HFGW detection system based on the EM response to GWs. Specially, Gamma-HFGWs would possess distinctive envelopes with characteristic shapes depending on the particular structures of surface magnetic fields of magnetars, which could be exclusive features helpful to distinguish them from background noise. Results obtained suggest that magnetars could be involved in possible astrophysical EM sources of GWs in the very high-frequency band, and Gamma-HFGWs could be potential targets for observations in the future. Supported by National Natural Science Foundation of China (11605015, 11375279, 11205254, 11647307) and the Fundamental Research Funds for the Central Universities (106112017CDJXY300003, 106112017CDJXFLX0014)

  1. HETEROGENEITY IN SHORT GAMMA-RAY BURSTS

    International Nuclear Information System (INIS)

    Norris, Jay P.; Gehrels, Neil; Scargle, Jeffrey D.

    2011-01-01

    We analyze the Swift/BAT sample of short gamma-ray bursts, using an objective Bayesian Block procedure to extract temporal descriptors of the bursts' initial pulse complexes (IPCs). The sample is comprised of 12 and 41 bursts with and without extended emission (EE) components, respectively. IPCs of non-EE bursts are dominated by single pulse structures, while EE bursts tend to have two or more pulse structures. The medians of characteristic timescales-durations, pulse structure widths, and peak intervals-for EE bursts are factors of ∼2-3 longer than for non-EE bursts. A trend previously reported by Hakkila and colleagues unifying long and short bursts-the anti-correlation of pulse intensity and width-continues in the two short burst groups, with non-EE bursts extending to more intense, narrower pulses. In addition, we find that preceding and succeeding pulse intensities are anti-correlated with pulse interval. We also examine the short burst X-ray afterglows as observed by the Swift/X-Ray Telescope (XRT). The median flux of the initial XRT detections for EE bursts (∼6x10 -10 erg cm -2 s -1 ) is ∼>20x brighter than for non-EE bursts, and the median X-ray afterglow duration for EE bursts (∼60,000 s) is ∼30x longer than for non-EE bursts. The tendency for EE bursts toward longer prompt-emission timescales and higher initial X-ray afterglow fluxes implies larger energy injections powering the afterglows. The longer-lasting X-ray afterglows of EE bursts may suggest that a significant fraction explode into denser environments than non-EE bursts, or that the sometimes-dominant EE component efficiently powers the afterglow. Combined, these results favor different progenitors for EE and non-EE short bursts.

  2. European team gauges a gamma-ray star

    Science.gov (United States)

    1996-03-01

    Italian astrophysicists have pushed the Hubble Space Telescope to the limit of its powers in finding the distance of Geminga, a pointlike object 500 light-years from the Earth. It is the prototype of a novel kind of star, a radio-silent neutron star, which may be much more common in the Universe than previously supposed. Geminga is so weak in visible light that Hubble had to stare at the spot for more than an hour to register it adequately. The object is nevertheless one of the brightest sources of gamma-rays in the sky, and its output of this very energetic form of radiation can now be accurately ganged. Neutron stars, first discovered as radio pulsars in 1967, are fantastic creations of exploding stars, just one step short of a black hole. They are heavier than the Sun yet only about twenty kilometres wide. Made of compressed nuclear matter, they have gravity and magnetic fields many billions of times stronger than on the Earth. With the first direct measurement of the distance of a radio-silent neutron star, astrophysicists can assess Geminga's power and speed of motion. The astronomical task was like judging the width of a one- franc piece in Paris, seen from the distance of Sicily. Geminga's low brightness greatly aggravated the difficulties. Patrizia Caraveo and her colleagues at the Istituto di Fisica Cosmica in Milan arranged for Hubble's wide-field camera (WFPC2) to make its prolonged observations of Geminga three times. Their findings will be published in Astrophysical Journal Letters on 20 April 1996. Caraveo's co-authors are Giovanni Bignami and Roberto Mignani of Milan, and Laurence Taff of Johns Hopkins University, Maryland. The Italians took advantage of the European Space Agency's collaboration with NASA in the Hubble mission, which gives European astronomers privileged access to the Space Telescope. Shifts of millionths of a degree The three sightings of Geminga, made at intervals of six months, revealed small shifts in the position of the faint

  3. The Astrophysics Science Division Annual Report 2008

    Science.gov (United States)

    Oegerle, William; Reddy, Francis; Tyler, Pat

    2009-01-01

    The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radio wavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. This report includes the Division's activities during 2008.

  4. Gamma-Ray Bursts: 4th Huntsville Symposium. Proceedings

    International Nuclear Information System (INIS)

    Meegan, C.A.; Preece, R.D.; Koshut, T.M.

    1998-01-01

    These proceedings represent papers presented at the Fourth Huntsville Gamma-Ray Bursts Symposium held in September, 1997 in Huntsville, Alabama, USA. This conference occurred at a crucial time in the history of the gamma-ray burst research. In early 1997, 30 years after the detection of the first gamma-ray burst by the Vela satellites, counterparts to bursts were finally detected at optical and radio wavelengths. The symposium attracted about 200 scientists from 16 countries. Some of the topics discussed include gamma-ray burst spectra, x-ray observations, optical observations, radio observations, host galaxies, shocks and afterglows and models of gamma-ray bursts. There were 183 papers presented, out of these, 16 have been abstracted for the Energy Science and Technology database

  5. Discoveries by the Fermi Gamma Ray Space Telescope

    Science.gov (United States)

    Gehrels, Neil

    2011-01-01

    Fermi is a large space gamma-ray mission developed by NASA and the DOE with major contributions from France, Germany, Italy, Japan and Sweden. It was launched in June 2008 and has been performing flawlessly since then. The main instrument is the Large Area Telescope (LAT) operating in the 20 MeV to 300 GeV range and a smaller monitor instrument is the Gamma-ray Burst Monitor (GBM) operating in the 8 keV to 40 MeV range. New findings are occurring every week. Some of the key discoveries are: 1) Discovery of many new gamma-ray pulsars, including gamma-ray only and millisecond pulsars. 2) Detection of high energy gamma-ray emission from globular clusters, most likely due to summed emission from msec pulsars. 3) Discovery of delayed and extended high energy gamma-ray emission from short and long gamma-ray busts. 4) Detection of approximately 250 gamma-ray bursts per year with the GBM instrument. 5) Most accurate measurement of the cosmic ray electron spectrum between 30 GeV and 1 TeV, showing some excess above the conventional diffusion model. The talk will present the new discoveries and their implications.

  6. Cosmological Gamma-Ray Bursts and Hypernovae Conclusively Linked

    Science.gov (United States)

    2003-06-01

    radiation. The team concludes that it is likely to be due to the nearly instantaneous, non-symmetrical collapse of the inner region of a highly developed star (known as the "collapsar" model) . The March 29 gamma-ray burst will pass into the annals of astrophysics as a rare "type-defining event", providing conclusive evidence of a direct link between cosmological gamma-ray bursts and explosions of very massive stars . PR Photo 17a/03 : Image of the optical afterglow of GRB 030329 (VLT FORS1+2). PR Photo 17b/03 : A series of VLT spectra of the optical afterglow of GRB 030329. What are Gamma-Ray Bursts? One of the currently most active fields of astrophysics is the study of the dramatic events known as "gamma-ray bursts (GRBs)" . They were first detected in the late 1960's by sensitive instruments on-board orbiting military satellites, launched for the surveillance and detection of nuclear tests. Originating, not on the Earth, but far out in space, these short flashes of energetic gamma-rays last from less than a second to several minutes. Despite major observational efforts, it is only within the last six years that it has become possible to pinpoint with some accuracy the sites of some of these events. With the invaluable help of comparatively accurate positional observations of the associated X-ray emission by various X-ray satellite observatories since early 1997, astronomers have until now identified about fifty short-lived sources of optical light associated with GRBs (the "optical afterglows"). Most GRBs have been found to be situated at extremely large ("cosmological") distances. This implies that the energy released in a few seconds during such an event is larger than that of the Sun during its entire lifetime of more than 10,000 million years. The GRBs are indeed the most powerful events since the Big Bang known in the Universe, cf. ESO PR 08/99 and ESO PR 20/00 . During the past years circumstantial evidence has mounted that GRBs signal the collapse of massive

  7. Heterogeneity in Short Gamma-Ray Bursts

    Science.gov (United States)

    Norris, Jay P.; Gehrels Neil; Scargle, Jeffrey D.

    2011-01-01

    We analyze the Swift/BAT sample of short gamma-ray bursts, using an objective Bayesian Block procedure to extract temporal descriptors of the bursts' initial pulse complexes (IPCs). The sample comprises 12 and 41 bursts with and without extended emission (EE) components, respectively. IPCs of non-EE bursts are dominated by single pulse structures, while EE bursts tend to have two or more pulse structures. The medians of characteristic timescales - durations, pulse structure widths, and peak intervals - for EE bursts are factors of approx 2-3 longer than for non-EE bursts. A trend previously reported by Hakkila and colleagues unifying long and short bursts - the anti-correlation of pulse intensity and width - continues in the two short burst groups, with non-EE bursts extending to more intense, narrower pulses. In addition we find that preceding and succeeding pulse intensities are anti-correlated with pulse interval. We also examine the short burst X-ray afterglows as observed by the Swift/XRT. The median flux of the initial XRT detections for EE bursts (approx 6 X 10(exp -10) erg / sq cm/ s) is approx > 20 x brighter than for non-EE bursts, and the median X-ray afterglow duration for EE bursts (approx 60,000 s) is approx 30 x longer than for non-EE bursts. The tendency for EE bursts toward longer prompt-emission timescales and higher initial X-ray afterglow fluxes implies larger energy injections powering the afterglows. The longer-lasting X-ray afterglows of EE bursts may suggest that a significant fraction explode into more dense environments than non-EE bursts, or that the sometimes-dominant EE component efficiently p()wers the afterglow. Combined, these results favor different progenitors for EE and non-EE short bursts.

  8. GROSS- GAMMA RAY OBSERVATORY ATTITUDE DYNAMICS SIMULATOR

    Science.gov (United States)

    Garrick, J.

    1994-01-01

    The Gamma Ray Observatory (GRO) spacecraft will constitute a major advance in gamma ray astronomy by offering the first opportunity for comprehensive observations in the range of 0.1 to 30,000 megaelectronvolts (MeV). The Gamma Ray Observatory Attitude Dynamics Simulator, GROSS, is designed to simulate this mission. The GRO Dynamics Simulator consists of three separate programs: the Standalone Profile Program; the Simulator Program, which contains the Simulation Control Input/Output (SCIO) Subsystem, the Truth Model (TM) Subsystem, and the Onboard Computer (OBC) Subsystem; and the Postprocessor Program. The Standalone Profile Program models the environment of the spacecraft and generates a profile data set for use by the simulator. This data set contains items such as individual external torques; GRO spacecraft, Tracking and Data Relay Satellite (TDRS), and solar and lunar ephemerides; and star data. The Standalone Profile Program is run before a simulation. The SCIO subsystem is the executive driver for the simulator. It accepts user input, initializes parameters, controls simulation, and generates output data files and simulation status display. The TM subsystem models the spacecraft dynamics, sensors, and actuators. It accepts ephemerides, star data, and environmental torques from the Standalone Profile Program. With these and actuator commands from the OBC subsystem, the TM subsystem propagates the current state of the spacecraft and generates sensor data for use by the OBC and SCIO subsystems. The OBC subsystem uses sensor data from the TM subsystem, a Kalman filter (for attitude determination), and control laws to compute actuator commands to the TM subsystem. The OBC subsystem also provides output data to the SCIO subsystem for output to the analysts. The Postprocessor Program is run after simulation is completed. It generates printer and CRT plots and tabular reports of the simulated data at the direction of the user. GROSS is written in FORTRAN 77 and

  9. Ultra-high energy cosmic rays and prompt TeV gamma rays from ...

    Indian Academy of Sciences (India)

    physics pp. 789-792. Ultra-high energy cosmic rays and prompt. TeV gamma rays from gamma ray bursts ... The origin of the observed ultra-high energy cosmic ray (UHECR) events with ... are proton and electron rest mass, respectively.

  10. A study of gamma-ray bursts and a new detector for gamma-ray astronomy

    International Nuclear Information System (INIS)

    Carter, J.N.

    1979-09-01

    Three gamma-ray experiments flown on balloons between August 1975 and August 1976 are described in detail. The successful Transatlantic balloon flight enabled a rate of 3 bursts year -1 with energies > 7 x 10 -7 ergs cm -2 to be established. This result is discussed in the light of other work. The choice of γ-ray detector for optimum sensitivity is presented. In addition various techniques for determining the arrival direction of gamma-ray bursts are compared. A new balloon borne γ-ray burst telescope is proposed. The design, testing and results of the beam calibration of a new drift chamber detector system for high energy (> 50 MeV) γ-rays are presented. A projected angular resolution of 0.8 0 was obtained at 300 MeV. Techniques for the measurement of γ-ray energies are discussed in relation to this instrument. Finally the use of drift chambers in an integrated free flying satellite is illustrated, and the expected performance is presented. (author)

  11. Large Imaging X-ray MKID Arrays for Astrophysics

    Science.gov (United States)

    Mazin, Benjamin

    Microwave Kinetic Inductance Detectors, or MKIDs, are a relatively new type of superconducting detector with built-in frequency domain multiplexing. Like Transition Edge Sensors (TESs) microbolometers, MKIDs can count single X-ray photons over a wide energy range and determine their energy and arrival time. MKIDs allow very large pixel counts with a simple room temperature microwave readout. In this investigation we will develop a new type of detector based on a MKID called the Thermal Kinetic Inductance Detector, or TKID. A TKID changes the basic MKID architecture by placing the inductor of the MKID on a suspended SiN membrane. The capacitor will remain on the bulk Si to reduce noise. Much like a TES, the TKID will sense changes in temperature of the isolated SiN island caused by photon absorption. The advantages of a TKID include lack of positional/geometry dependence, a more tunable pulse decay time, a relaxation of the MKID resonator material requirements, and more. We have already fabricated a TKID with the best energy resolution seen to date in any KID. Here we propose to improve the energy resolution below 10 eV, develop mushroom absorbers compatible with our TKIDs, and integrate these detectors into small arrays.

  12. X-ray polarimetry and new prospects in high-energy astrophysics

    International Nuclear Information System (INIS)

    Sgrò, C.

    2016-01-01

    Polarimetry is universally recognized as one of the new frontiers in X-ray astrophysics. It is a powerful tool to investigate a variety of astrophysical processes, as well as a mean to study fundamental physics in space. A renewed interest is testified by dedicated missions approved for phase A by ESA and NASA. The main advance is the availability of a gas pixel detector that is able to add polarization measurement to imaging and spectroscopy, and can be used at the focus of a conventional X-ray optics. The detector exploits the photoelectric effect in gas and a finely segmented ASIC as a collecting anode. In this work I will describe in detail the experimental technique and the detector concept, and illustrate the scientific prospects of these new missions.

  13. Gamma-ray effect on sweet potato

    International Nuclear Information System (INIS)

    Ferdes, O.; Ciofu, R.; Stroia, L.; Ghering, A.; Ferdes, M.

    1994-01-01

    The paper presents the results on modification occurred in biochemical properties of sweet potato (Ipomea batatus L.) after gamma irradiation. Two varieties, named Victoria Ianb (a white variety) and Portocaliu (a red variety), were selected and acclimatized for the agrometeorological conditions of Romania. The samples consist of roots from both usual and experimental crops. They were irradiated in batch, one week after harvesting, with a ICPR Co-60 gamma-ray source by approx. 370 TBq, dose range 100-500 Gy, dose rate 100±5 Gy/hour, dose uniformity ±5%, temperature 10 o C, 80±5% relative humidity (rh). The irradiation doses received were checked using the Fricke ferrous sulphate dosimeter procedure. The roots were kept two months at relative darkness, 6-11 o C, 60-75% rh and analyzed from time to time (initial, 5, 7, 14, 30 and 60 days). The following parameters are analyzed by conventional methods: total and reducing sugars (in De equivalent, %, on dry weight basis), starch content and the activities of sugar metabolizing enzymes. The red variety had a better behaviour towards irradiation that the white one. The sugar contents (both total and reducing), as well as starch, varied more in the white variety. The sugar metabolizing enzyme activities were influenced by both irradiation and storage conditions. Their activities were maximal at 200 and 300 Gy, and decreased significantly at higher doses. The activities also decreased in time, their variations being higher at lower doses (100 and 200 Gy). The results showed no significant influence of gamma irradiation on storage life. The modifications induced in sugar contents and enzyme activities had maximal effects at 200-300 Gy. (author)

  14. New possibilities in prompt gamma ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Borderie, B; Barrandon, J N [Centre National de la Recherche Scientifique, 45 - Orleans-la-Source (France). Lab. du cyclotron; Pinault, J L [Bureau de Recherches Geologiques et Minieres (BRGM), 45 - Orleans (France)

    1977-01-01

    Prompt gamma ray spectrometry has been used as an analytical tool for many years. The high level of background noise does, however, remain a major problem with this technique. From simple theoretical consideration, conditions (particle, energy) were determined to reduce significantly the background noise under irradiation. Alpha particles of 3.5 MeV were chosen. Some fifty elements were studied, of which 24 gave interesting results. The detection limits obtained for a sample of niobium were as follows: approximately 1 ppm (10/sup -6/g/g) for the light elements Li, B, F and Na, and between 50 ppm and 1% for the others. Numerous applications may be envisaged in the geo- and cosmo-sciences.

  15. A review of gamma ray bursts

    CERN Document Server

    Rees, Martin J

    2000-01-01

    Gamma-ray bursts, an enigma for more than 25 years, are now coming into focus. They involve extraordinary power outputs, and highly relativistic dynamics. The 'trigger' involves stellar-mass compact objects. The most plausible progenitors, ranging from neutron star binary mergers to collapsars (sometimes called 'hypernovae') eventually lead to the formation of a black hole with a torus of hot neutron-density material around it, the extractable energy being up to 10 sup 5 sup 4 ergs. Magnetic fields may exceed 10 sup 1 sup 5 G and particles may be accelerated up to > or approx. 10 sup 2 sup 0 eV. Details of the afterglow may be easier to understand than the initial trigger. Bursts at very high redshift can be astronomically-important as probes of the distant universe.

  16. Gamma-Ray Bursts: A Radio Perspective

    Directory of Open Access Journals (Sweden)

    Poonam Chandra

    2016-01-01

    Full Text Available Gamma-ray bursts (GRBs are extremely energetic events at cosmological distances. They provide unique laboratory to investigate fundamental physical processes under extreme conditions. Due to extreme luminosities, GRBs are detectable at very high redshifts and potential tracers of cosmic star formation rate at early epoch. While the launch of Swift and Fermi has increased our understanding of GRBs tremendously, many new questions have opened up. Radio observations of GRBs uniquely probe the energetics and environments of the explosion. However, currently only 30% of the bursts are detected in radio bands. Radio observations with upcoming sensitive telescopes will potentially increase the sample size significantly and allow one to follow the individual bursts for a much longer duration and be able to answer some of the important issues related to true calorimetry, reverse shock emission, and environments around the massive stars exploding as GRBs in the early Universe.

  17. Gamma-Ray Burst Prompt Correlations

    Directory of Open Access Journals (Sweden)

    M. G. Dainotti

    2018-01-01

    Full Text Available The mechanism responsible for the prompt emission of gamma-ray bursts (GRBs is still a debated issue. The prompt phase-related GRB correlations can allow discriminating among the most plausible theoretical models explaining this emission. We present an overview of the observational two-parameter correlations, their physical interpretations, and their use as redshift estimators and possibly as cosmological tools. The nowadays challenge is to make GRBs, the farthest stellar-scaled objects observed (up to redshift z=9.4, standard candles through well established and robust correlations. However, GRBs spanning several orders of magnitude in their energetics are far from being standard candles. We describe the advances in the prompt correlation research in the past decades, with particular focus paid to the discoveries in the last 20 years.

  18. Nuclear gamma ray lines from supernovae

    International Nuclear Information System (INIS)

    Jardim, J.O.D.

    1980-01-01

    From theoretical considerations of the behaviour of gamma ray line fluxes occurring after a supernova explosion, the 1.156 and 0.847 MeV lines are seen to be the most likely to be observed. The 1.156 MeV line has been previously observed by other investigators. Observations of the 0.847 MeV line, and 1.332, 1.173 and 0.059 MeV lines using a Ge(Li) telescope aboard a stratospheric balloon which was flown in Brazil in 1977 are reported. The observation using a NaI(Tl) detector of a line in the energy interval 1.5 - 1.6 MeV, which may be due to 0 18 (p,p') 0 18 sup (*) reaction is also reported. (Author) [pt

  19. Theoretical Study of Gamma-ray Pulsars

    Directory of Open Access Journals (Sweden)

    Kwong Sang Cheng

    2016-06-01

    Full Text Available We use the non-stationary three dimensional two-layer outer gap model to explain gamma-ray emissions from a pulsar magnetosphere. We found out that for some pulsars like the Geminga pulsar, it was hard to explain emissions above a level of around 1 GeV. We then developed the model into a non-stationary model. In this model we assigned a power-law distribution to one or more of the spectral parameters proposed in the previous model and calculated the weighted phaseaveraged spectrum. Though this model is suitable for some pulsars, it still cannot explain the high energy emission of the Geminga pulsar. An Inverse-Compton Scattering component between the primary particles and the radio photons in the outer magnetosphere was introduced into the model, and this component produced a sufficient number of GeV photons in the spectrum of the Geminga pulsar.

  20. Prototyping a Global Soft X-Ray Imaging Instrument for Heliophysics, Planetary Science, and Astrophysics Science

    Science.gov (United States)

    Collier, M. R.; Porter, F. S.; Sibeck, D. G.; Carter, J. A.; Chiao, M. P.; Chornay, D. J.; Cravens, T.; Galeazzi, M.; Keller, J. W.; Koutroumpa, D.; hide

    2012-01-01

    We describe current progress in the development of a prototype wide field-of-view soft X-ray imager that employs Lobstereye optics and targets heliophysics, planetary, and astrophysics science. The prototype will provide proof-of-concept for a future flight instrument capable of imaging the entire dayside magnetosheath from outside the magnetosphere. Such an instrument was proposed for the ESA AXIOM mission.

  1. Prototyping a Global Soft X-ray Imaging Instrument for Heliophysics, Planetary Science, and Astrophysics Science

    Science.gov (United States)

    Collier, Michael R.; Porter, F. Scott; Sibeck, David G.; Carter, Jenny A.; Chiao, Meng P.; Chornay, Dennis J.; Cravens, Thomas; Galeazzi, Massimiliano; Keller, John W.; Koutroumpa, Dimitra; hide

    2012-01-01

    We describe current progress in the development of a prototype wide field-of-view soft X-ray imager that employs Lobster-eye optics and targets heliophysics, planetary, and astrophysics science. The prototype will provide proof-of-concept for a future flight instrument capable of imaging the entire dayside magnetosheath from outside the magnetosphere. Such an instrument was proposed for the FSA AXIOM mission

  2. A new processing technique for airborne gamma-ray data

    DEFF Research Database (Denmark)

    Hovgaard, Jens

    1997-01-01

    The mathematical-statistical background for at new technique for processing gamma-ray spectra is presented. The technique - Noise Adjusted Singular Value Decomposition - decomposes at set of gamma-ray spectra into a few basic spectra - the spectral components. The spectral components can be proce...

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

    International Nuclear Information System (INIS)

    Hartwell, J.K.; Goodwin, S.G.; Johnson, L.O.; Killian, E.W.

    1990-01-01

    This patent describes a module for use with a gamma-ray spectroscopy system. The system includes a gamma-ray detector for detecting gamma-ray events and producing a signal representing the gamma-ray events, a converter responsive to the detector and capable of converting the signal to a spectrum, a storage memory responsive to the converter and capable of storing the spectrum at address locations in memory, and a pulser capable of injecting pulses into the signal produced by the detector. The module comprises: means for generating a logic pulse for controlling the pulser, the controlling means adapted for coupling to the pulser; means for generating separation of events logic to isolate the components of a combined gamma-ray---pulse spectrum, the separation of events logic means adapted for coupling to the converter and the storage memory with the capability of storing pulses at address locations in the storage memory separate from the gamma-ray events; means for receiving an imitating signal from the converter to generate a plurality of operations by the module; means for tracking variations in a gamma-ray---pulse spectrum brought on by external parameter changes; and means for interfacing with commercially developed gamma-ray spectrometry equipment

  4. Effectiveness of gamma ray irradiation and ethyl methane ...

    African Journals Online (AJOL)

    Survival rate and plantlet performance of DNKW001 in gamma ray + EMS 7uM treatment declined profoundly with increasing doses and LD50 was lower (104 Gy) than LD50 in gamma ray irradiation (177 Gy) alone. Variants of plantlets were detected in pre (white streaked leaf and bigger petiole with distorted leaf) and post ...

  5. Wolf-Rayet stars as gamma-ray burst progenitors

    NARCIS (Netherlands)

    Langer, N.; van Marle, A. -J; Yoon, S.C.

    2010-01-01

    It became clear in the last few years that long gamma-ray bursts are associated with the endpoints of massive star evolution. They occur in star forming regions at cosmological distances (Jakobsson et al., 2005), and are associated with supernova-type energies. The collapsar model explains gamma-ray

  6. The many phases of gamma-ray burst afterglows

    NARCIS (Netherlands)

    Leventis, K.

    2013-01-01

    Gamma-ray bursts are the brightest sources in the universe. Their afterglows have been observed for about 15 years now, and their study has greatly advanced our understanding of these, mysterious until recently, events. In a way, gamma-ray bursts can be seen as huge cosmic bombs which convert

  7. Gamma ray bursts: Current status of observations and theory

    International Nuclear Information System (INIS)

    Meegan, C.A.

    1990-04-01

    Gamma ray bursts display a wide range of temporal and spectral characteristics, but typically last several seconds and emit most of their energy in a low energy, gamma ray region. The burst sources appear to be isotropically distributed on the sky. Several lines of evidence suggest magnetic neutron stars as sources for bursts. A variety of energy sources and emission mechanisms are proposed

  8. Supernova sheds light on gamma-ray bursts

    CERN Multimedia

    2003-01-01

    On 29 March the HETE-II satellite detected the most violent explosion in the universe to date - an enormous burst of gamma rays. Observers across the world recorded and studied the event. It appears to prove that gamma ray bursts originate in supernovae (1 page)

  9. Jet simulations and gamma-ray burst afterglow jet breaks

    NARCIS (Netherlands)

    van Eerten, H.J.; Meliani, Z.; Wijers, R.A.M.J.; Keppens, R.

    2011-01-01

    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on

  10. Jet simulations and gamma-ray burst afterglow jet breaks

    NARCIS (Netherlands)

    van Eerten, H. J.; Meliani, Z.; Wijers, R.A.M.J.; Keppens, R.

    2010-01-01

    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on

  11. Bulk density calculations from prompt gamma ray yield

    International Nuclear Information System (INIS)

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

    2006-01-01

    Full text: The gamma ray yield from a Prompt Gamma ray Neutron Activation Analysis (PGNAA) setup is a linear function of element concentration and neutron flux in a the sample with constant bulk density. If the sample bulk density varies as well, then the element concentration and the neutron flux has a nonlinear correlation with the gamma ray yield [1]. The measurement of gamma ray yield non-linearity from samples and a standard can be used to estimate the bulk density of the samples. In this study the prompt gamma ray yield from Blast Furnace Slag, Fly Ash, Silica Fumes and Superpozz cements samples have been measured as a function of their calcium and silicon concentration using KFUPM accelerator-based PGNAA setup [2]. Due to different bulk densities of the blended cement samples, the measured gamma ray yields have nonlinear correlation with calcium and silicon concentration of the samples. The non-linearity in the yield was observed to increase with gamma rays energy and element concentration. The bulk densities of the cement samples were calculated from ratio of gamma ray yield from blended cement and that from a Portland cement standard. The calculated bulk densities have good agreement with the published data. The result of this study will be presented

  12. Gamma ray induced somatic mutations in rose

    International Nuclear Information System (INIS)

    Datta, S.K.

    1989-01-01

    Budwood of 32 rose cultivars (Rosa spp.) was exposed to 3-4 krad of gamma rays and eyes were grafted on Rosa indica var. odorata root stock. Radiosensitivity with respect to sprouting, survival and plant height, and mutation frequency varied with the cultivar and dose of gamma rays. Somatic mutations in flower colour/shape were detected as chimera in 21 cultivars. The size of the mutant sector varied from a narrow streak on a petal to a whole flower and from a portion of a branch to an entire branch. 14 mutants were detected in M 1 V 1 , four in M 1 V 2 and three in M 1 V 3 . Maximum number of mutations was detected following 3 krad treatment. Eyes from mutant branches were grafted again on root stock and non-chimeric mutants were aimed at by vegetative propagation. Mutants from 11 cultivars only could be isolated in pure form. Isolation of non-chimeric mutants sometimes is difficult due to weak growth of a mutant branch. In such a case, all normal looking branches are removed to force a better growth of the mutant branch. It is advisable to maintain irradiated plants at least for four years with drastic pruning in each year. Nine mutants viz. 'Sharada', 'Sukumari', 'Tangerine Contempo', 'Yellow Contempo', 'Pink Contempo', 'Striped Contempo', 'Twinkle', 'Curio' and 'Light Pink Prize' have already been released as new cultivars for commercialization [ref. MBNL No. 23 and 31] and others are being multiplied and assessed. The mutation spectrum appears to be wider for the cultivars 'Contempo' and 'Imperator'. Pigment composition of the original variety is relevant for the kind of flower colour mutations that can be induced

  13. A simulation package for soft X-ray and EUV spectroscopy of astrophysical and laboratory plasmas in different environments

    International Nuclear Information System (INIS)

    Liang, G Y; Li, F; Wang, F L; Zhong, J Y; Zhao, G; Wu, Y

    2014-01-01

    Spectroscopic researches in astronomy are significantly dependent on theoretical modelling methods, such as Chianti, Xstar, Cloudy etc. Recently, a different research community - Laboratory Astrophysics tries to benchmark these theoretical models or simulate the astrophysical phenomenon directly in conditions accessed in ground laboratory. Those unavoidable differences between the astrophysical objects and laboratory provide a need for a self-consistent model to make a bridge for the two cases. So we setup a visualized simulation package for soft X-ray and EUV spectroscopy in astrophysical and laboratory plasmas.

  14. Gamma-ray angular distribution and correlation measurement. II

    International Nuclear Information System (INIS)

    Twin, P.J.

    1975-01-01

    Angular correlations of γ-rays following nuclear reactions depend, in general, on some alignment of the γ-emitting initial state. The methods of alignment are briefly discussed and then the techniques and experimental methods associated with direct angular distributions, particle-gamma correlations, gamma-gamma correlations and linear polarization correlations are dealt with. Finally the inherent ambiguities which arise when different spin and delta values give identical correlations are discussed for the simple direct and particle-gamma correlations together with the question whether the larger information content of gamma-gamma and linear polarization correlations can resolve these ambiguities. (Auth.)

  15. MAGNETIC STRUCTURES IN GAMMA-RAY BURST JETS PROBED BY GAMMA-RAY POLARIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Yonetoku, Daisuke; Murakami, Toshio; Morihara, Yoshiyuki; Takahashi, Takuya; Wakashima, Yudai; Yonemochi, Hajime; Sakashita, Tomonori; Fujimoto, Hirofumi; Kodama, Yoshiki [College of Science and Engineering, School of Mathematics and Physics, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192 (Japan); Gunji, Shuichi; Toukairin, Noriyuki [Department of Physics, Faculty of Science, Yamagata University, 1-4-12, Koshirakawa, Yamagata, Yamagata 990-8560 (Japan); Mihara, Tatehiro [Cosmic Radiation Laboratory, RIKEN, 2-1, Hirosawa, Wako City, Saitama 351-0198 (Japan); Toma, Kenji, E-mail: yonetoku@astro.s.kanazawa-u.ac.jp [Department of Earth and Space Science, Osaka University, Toyonaka 560-0043 (Japan)

    2012-10-10

    We report polarization measurements in two prompt emissions of gamma-ray bursts, GRB 110301A and GRB 110721A, observed with the gamma-ray burst polarimeter (GAP) on borad the IKAROS solar sail mission. We detected linear polarization signals from each burst with polarization degree of {Pi} = 70 {+-} 22% with statistical significance of 3.7{sigma} for GRB 110301A, and {Pi} = 84{sup +16}{sub -28}% with 3.3{sigma} confidence level for GRB 110721A. We did not detect any significant change of polarization angle. These two events had shorter durations and dimmer brightness compared with GRB 100826A, which showed a significant change of polarization angle, as reported in Yonetoku et al. Synchrotron emission model can be consistent with the data of the three GRBs, while the photospheric quasi-thermal emission model is not favored. We suggest that magnetic field structures in the emission region are globally ordered fields advected from the central engine.

  16. The supernova-gamma-ray burst-jet connection.

    Science.gov (United States)

    Hjorth, Jens

    2013-06-13

    The observed association between supernovae and gamma-ray bursts represents a cornerstone in our understanding of the nature of gamma-ray bursts. The collapsar model provides a theoretical framework for this connection. A key element is the launch of a bipolar jet (seen as a gamma-ray burst). The resulting hot cocoon disrupts the star, whereas the (56)Ni produced gives rise to radioactive heating of the ejecta, seen as a supernova. In this discussion paper, I summarize the observational status of the supernova-gamma-ray burst connection in the context of the 'engine' picture of jet-driven supernovae and highlight SN 2012bz/GRB 120422A--with its luminous supernova but intermediate high-energy luminosity--as a possible transition object between low-luminosity and jet gamma-ray bursts. The jet channel for supernova explosions may provide new insights into supernova explosions in general.

  17. Recent achievements in the field of gamma-ray bursts

    International Nuclear Information System (INIS)

    Lu Tan; Dai Zigao

    2001-01-01

    Recent progresses in the field of gamma-ray bursts is briefly introduced. Gamma-ray bursts are the most energetic explosion since the Big Bang of the universe. Within a few tens of seconds, the energy released in gamma-ray bursts could be several hundred times larger than that released form the sun in its whole life (about 10 billion years). The authors will first briefly discuss the observational facts, based on which the authors will discuss the standard fireball model, the dynamical behavior and evolution of gamma-ray bursts and their afterglows. Then, various observational phenomena that contradict the standard model are given and the importance of these post-standard effects are pointed out. The questions related to the energy source of gamma-ray bursts are still unanswered, and other important questions also remain to be solved

  18. Cross-correlation of weak lensing and gamma rays: implications for the nature of dark matter

    Science.gov (United States)

    Tröster, Tilman; Camera, Stefano; Fornasa, Mattia; Regis, Marco; van Waerbeke, Ludovic; Harnois-Déraps, Joachim; Ando, Shin'ichiro; Bilicki, Maciej; Erben, Thomas; Fornengo, Nicolao; Heymans, Catherine; Hildebrandt, Hendrik; Hoekstra, Henk; Kuijken, Konrad; Viola, Massimo

    2017-05-01

    We measure the cross-correlation between Fermi gamma-ray photons and over 1000 deg2 of weak lensing data from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), the Red Cluster Sequence Lensing Survey (RCSLenS), and the Kilo Degree Survey (KiDS). We present the first measurement of tomographic weak lensing cross-correlations and the first application of spectral binning to cross-correlations between gamma rays and weak lensing. The measurements are performed using an angular power spectrum estimator while the covariance is estimated using an analytical prescription. We verify the accuracy of our covariance estimate by comparing it to two internal covariance estimators. Based on the non-detection of a cross-correlation signal, we derive constraints on weakly interacting massive particle (WIMP) dark matter. We compute exclusion limits on the dark matter annihilation cross-section , decay rate Γdec and particle mass mDM. We find that in the absence of a cross-correlation signal, tomography does not significantly improve the constraining power of the analysis. Assuming a strong contribution to the gamma-ray flux due to small-scale clustering of dark matter and accounting for known astrophysical sources of gamma rays, we exclude the thermal relic cross-section for particle masses of mDM ≲ 20 GeV.

  19. The gamma-ray arc-minute imaging system (GRATIS) - Mechanical design and expected performance

    International Nuclear Information System (INIS)

    Seiffert, M.; Lubin, P.; Hailey, C.J.; Ziock, K.P.; Harrison, F.A.

    1989-01-01

    A balloon experiment, GRATIS, is being constructed which will perform the first arcmin imaging of cosmic sources in the 30 - 200 keV energy band. Observations conducted with GRATIS can provide data relevant to several key problems in high energy astrophysics, including the physical processes responsible for the high energy tail observed in the soft gamma-ray spectra of clusters of galaxies and the origin of both the diffuse and point-source components of the gamma-ray emission from the Galactic Center. This paper discusses the scientific motivations in detail, outlines the experiment, discusses several aspects of the design and construction of hardware components, gives an overview of the stabilized platform, and shows the expected performance and sensitivity. 16 refs

  20. The MAGIC telescope for gamma-ray astronomy above 30 GeV

    Science.gov (United States)

    Moralejo, A.; MAGIC Collaboration

    The MAGIC telescope is presently at its commissioning phase at the Roque de los Muchachos Observatory (ORM) on the island of La Palma. MAGIC will become the largest ground-based gamma ray telescope in the world, being sensitive to photons of energies as low as 30 GeV. The spectral range between 10 and 300 GeV remains to date mostly unexplored. Observations in this region of the spectrum are expected to provide key data for the understanding of a wide variety of astrophysical phenomena belonging to the so-called ``non thermal Universe'', like the processes in the nuclei of active galaxies, the radiation mechanisms of pulsars and supernova remnants, and the enigmatic gamma-ray bursts. And overview of the telescope and its Physics goals is presented.

  1. Gamma-Ray imaging for nuclear security and safety: Towards 3-D gamma-ray vision

    Science.gov (United States)

    Vetter, Kai; Barnowksi, Ross; Haefner, Andrew; Joshi, Tenzing H. Y.; Pavlovsky, Ryan; Quiter, Brian J.

    2018-01-01

    The development of portable gamma-ray imaging instruments in combination with the recent advances in sensor and related computer vision technologies enable unprecedented capabilities in the detection, localization, and mapping of radiological and nuclear materials in complex environments relevant for nuclear security and safety. Though multi-modal imaging has been established in medicine and biomedical imaging for some time, the potential of multi-modal data fusion for radiological localization and mapping problems in complex indoor and outdoor environments remains to be explored in detail. In contrast to the well-defined settings in medical or biological imaging associated with small field-of-view and well-constrained extension of the radiation field, in many radiological search and mapping scenarios, the radiation fields are not constrained and objects and sources are not necessarily known prior to the measurement. The ability to fuse radiological with contextual or scene data in three dimensions, in analog to radiological and functional imaging with anatomical fusion in medicine, provides new capabilities enhancing image clarity, context, quantitative estimates, and visualization of the data products. We have developed new means to register and fuse gamma-ray imaging with contextual data from portable or moving platforms. These developments enhance detection and mapping capabilities as well as provide unprecedented visualization of complex radiation fields, moving us one step closer to the realization of gamma-ray vision in three dimensions.

  2. Astrophysics at very high energies

    International Nuclear Information System (INIS)

    Aharonian, Felix; Bergstroem, Lars; Dermer, Charles

    2013-01-01

    Presents three complementary lectures on very-high-energy astrophysics given by worldwide leaders in the field. Reviews the recent advances in and prospects of gamma-ray astrophysics and of multi-messenger astronomy. Prepares readers for using space and ground-based gamma-ray observatories, as well as neutrino and other multi-messenger detectors. With the success of Cherenkov Astronomy and more recently with the launch of NASA's Fermi mission, very-high-energy astrophysics has undergone a revolution in the last years. This book provides three comprehensive and up-to-date reviews of the recent advances in gamma-ray astrophysics and of multi-messenger astronomy. Felix Aharonian and Charles Dermer address our current knowledge on the sources of GeV and TeV photons, gleaned from the precise measurements made by the new instrumentation. Lars Bergstroem presents the challenges and prospects of astro-particle physics with a particular emphasis on the detection of dark matter candidates. The topics covered by the 40th Saas-Fee Course present the capabilities of current instrumentation and the physics at play in sources of very-high-energy radiation to students and researchers alike. This book will encourage and prepare readers for using space and ground-based gamma-ray observatories, as well as neutrino and other multi-messenger detectors.

  3. An Artificial Intelligence Classification Tool and Its Application to Gamma-Ray Bursts

    Science.gov (United States)

    Hakkila, Jon; Haglin, David J.; Roiger, Richard J.; Giblin, Timothy; Paciesas, William S.; Pendleton, Geoffrey N.; Mallozzi, Robert S.

    2004-01-01

    Despite being the most energetic phenomenon in the known universe, the astrophysics of gamma-ray bursts (GRBs) has still proven difficult to understand. It has only been within the past five years that the GRB distance scale has been firmly established, on the basis of a few dozen bursts with x-ray, optical, and radio afterglows. The afterglows indicate source redshifts of z=1 to z=5, total energy outputs of roughly 10(exp 52) ergs, and energy confined to the far x-ray to near gamma-ray regime of the electromagnetic spectrum. The multi-wavelength afterglow observations have thus far provided more insight on the nature of the GRB mechanism than the GRB observations; far more papers have been written about the few observed gamma-ray burst afterglows in the past few years than about the thousands of detected gamma-ray bursts. One reason the GRB central engine is still so poorly understood is that GRBs have complex, overlapping characteristics that do not appear to be produced by one homogeneous process. At least two subclasses have been found on the basis of duration, spectral hardness, and fluence (time integrated flux); Class 1 bursts are softer, longer, and brighter than Class 2 bursts (with two second durations indicating a rough division). A third GRB subclass, overlapping the other two, has been identified using statistical clustering techniques; Class 3 bursts are intermediate between Class 1 and Class 2 bursts in brightness and duration, but are softer than Class 1 bursts. We are developing a tool to aid scientists in the study of GRB properties. In the process of developing this tool, we are building a large gamma-ray burst classification database. We are also scientifically analyzing some GRB data as we develop the tool. Tool development thus proceeds in tandem with the dataset for which it is being designed. The tool invokes a modified KDD (Knowledge Discovery in Databases) process, which is described as follows.

  4. Optical telescope BIRT in ORIGIN for gamma ray burst observing

    DEFF Research Database (Denmark)

    Content, Robert; Content, Robert; Sharples, Ray

    2012-01-01

    The ORIGIN concept is a space mission with a gamma ray, an X-ray and an optical telescope to observe the gamma ray bursts at large Z to determine the composition and density of the intergalactic matter in the line of sight. It was an answer to the ESA M3 call for proposal. The optical telescope i...... length. All 3 instruments use the same 2k x 2k detector simultaneously so that telescope pointing and tip-tilt control of a fold mirror permit to place the gamma ray burst on the desired instrument without any other mechanism. © 2012 SPIE....

  5. Design Study for Direction Variable Compton Scattering Gamma Ray

    Science.gov (United States)

    Kii, T.; Omer, M.; Negm, H.; Choi, Y. W.; Kinjo, R.; Yoshida, K.; Konstantin, T.; Kimura, N.; Ishida, K.; Imon, H.; Shibata, M.; Shimahashi, K.; Komai, T.; Okumura, K.; Zen, H.; Masuda, K.; Hori, T.; Ohgaki, H.

    2013-03-01

    A monochromatic gamma ray beam is attractive for isotope-specific material/medical imaging or non-destructive inspection. A laser Compton scattering (LCS) gamma ray source which is based on the backward Compton scattering of laser light on high-energy electrons can generate energy variable quasi-monochromatic gamma ray. Due to the principle of the LCS gamma ray, the direction of the gamma beam is limited to the direction of the high-energy electrons. Then the target object is placed on the beam axis, and is usually moved if spatial scanning is required. In this work, we proposed an electron beam transport system consisting of four bending magnets which can stick the collision point and control the electron beam direction, and a laser system consisting of a spheroidal mirror and a parabolic mirror which can also stick the collision point. Then the collision point can be placed on one focus of the spheroid. Thus gamma ray direction and collision angle between the electron beam and the laser beam can be easily controlled. As the results, travelling direction of the LCS gamma ray can be controlled under the limitation of the beam transport system, energy of the gamma ray can be controlled by controlling incident angle of the colliding beams, and energy spread can be controlled by changing the divergence of the laser beam.

  6. Deep Space Thermal Cycle Testing of Advanced X-Ray Astrophysics Facility - Imaging (AXAF-I) Solar Array Panels Test

    National Research Council Canada - National Science Library

    Sisco, Jimmy

    1997-01-01

    The NASA Advanced X-ray Astrophysics Facility - Imaging (AXAF-I) satellite will be exposed to thermal conditions beyond normal experience flight temperatures due to the satellite's high elliptical orbital flight...

  7. A broad band X-ray imaging spectrophotometer for astrophysical studies

    Science.gov (United States)

    Lum, Kenneth S. K.; Lee, Dong Hwan; Ku, William H.-M.

    1988-01-01

    A broadband X-ray imaging spectrophotometer (BBXRIS) has been built for astrophysical studies. The BBXRIS is based on a large-imaging gas scintillation proportional counter (LIGSPC), a combination of a gas scintillation proportional counter and a multiwire proportional counter, which achieves 8 percent (FWHM) energy resolution and 1.5-mm (FWHM) spatial resolution at 5.9 keV. The LIGSPC can be integrated with a grazing incidence mirror and a coded aperture mask to provide imaging over a broad range of X-ray energies. The results of tests involving the LIGSPC and a coded aperture mask are presented, and possible applications of the BBXRIS are discussed.

  8. Europe's space camera unmasks a cosmic gamma-ray machine

    Science.gov (United States)

    1996-11-01

    The new-found neutron star is the visible counterpart of a pulsating radio source, Pulsar 1055-52. It is a mere 20 kilometres wide. Although the neutron star is very hot, at about a million degrees C, very little of its radiant energy takes the form of visible light. It emits mainly gamma-rays, an extremely energetic form of radiation. By examining it at visible wavelengths, astronomers hope to figure out why Pulsar 1055-52 is the most efficient generator of gamma-rays known so far, anywhere the Universe. The Faint Object Camera found Pulsar 1055-52 in near ultraviolet light at 3400 angstroms, a little shorter in wavelength than the violet light at the extremity of the human visual range. Roberto Mignani, Patrizia Caraveo and Giovanni Bignami of the Istituto di Fisica Cosmica in Milan, Italy, report its optical identification in a forthcoming issue of Astrophysical Journal Letters (1 January 1997). The formal name of the object is PSR 1055-52. Evading the glare of an adjacent star The Italian team had tried since 1988 to spot Pulsar 1055-52 with two of the most powerful ground-based optical telescopes in the Southern Hemisphere. These were the 3.6-metre Telescope and the 3.5-metre New Technology Telescope of the European Southern Observatory at La Silla, Chile. Unfortunately an ordinary star 100,000 times brighter lay in almost the same direction in the sky, separated from the neutron star by only a thousandth of a degree. The Earth's atmosphere defocused the star's light sufficiently to mask the glimmer from Pulsar 1055-52. The astronomers therefore needed an instrument in space. The Faint Object Camera offered the best precision and sensitivity to continue the hunt. Devised by European astronomers to complement the American wide field camera in the Hubble Space Telescope, the Faint Object Camera has a relatively narrow field of view. It intensifies the image of a faint object by repeatedly accelerating electrons from photo-electric films, so as to produce

  9. Characteristics of the telescope for high energy gamma-ray astronomy selected for definition studies on the Gamma Ray Observatory

    Science.gov (United States)

    Hughes, E. B.; Hofstadter, R.; Rolfe, J.; Johansson, A.; Bertsch, D. L.; Cruickshank, W. J.; Ehrmann, C. H.; Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.

    1980-01-01

    The high energy gamma-ray telescope selected for definition studies on the Gamma Ray Observatory provides a substantial improvement in observational capability over earlier instruments. It will have about 20 times more sensitivity, cover a much broader energy range, have considerably better energy resolution and provide a significantly improved angular resolution. The design and performance are described.

  10. Planetary gamma-ray spectroscopy: the effects of hydrogen absorption cross-section of the gamma-ray spectrum

    International Nuclear Information System (INIS)

    Lapides, J.R.

    1981-01-01

    The gamma-ray spectroscopy of planet surfaces is one of several possible methods that are useful in determining the elemental composition of planet surfaces from orbiting spacecraft. This has been demonstrated on the Apollos 15 and 16 missions as well as the Soviet Mars-5 mission. Planetary gamma-ray emission is primarily the result of natural radioactive decay and cosmic-ray and solar-flare-induced nuclear reactions. Secondary neutron reactions play a large role in the more intense gamma-ray emission. The technique provides information on the elemental composition of the top few tens of centimeters of the planet surface. Varying concentrations of hydrogen and compositional variations that alter the macroscopic thermal-neutron absorption cross section have a significant effect on the neutron flux in the planet surface and therefore also on the gamma-ray emission from the surface. These effects have been systematically studied for a wide range of possible planetary compositions that include Mercury, the moon, Mars, the comets, and the asteroids. The problem of the Martian atmosphere was also investigated. The results of these calculations, in which both surface neutron fluxes and gamma-ray emission fluxes were determined, were used to develop general procedures for obtaining planet compositions from the gamma-ray spectrum. Several changes have been suggested for reanalyzing the Apollos 15 and 16 gamma-ray results. In addition, procedures have been suggested that can be applied to neutron-gamma techniques in mineral and oil exploration

  11. Ultra high energy gamma rays and observations with CYGNUS/MILAGRO

    International Nuclear Information System (INIS)

    Weeks, D.D.; Yodh, G.B.

    1992-01-01

    This talk discusses high-energy observations of the Crab pulsar/nebula and the pulsar in the X-ray binary, Hercules X-1, and makes the case for continued observations with ground-based γ-ray detectors. The CYGNUS Air Shower Array has a wide field of view on monitors several astrophysical γ-ray sources at the same time, many of which are prime objects observed by the Compton Gamma Ray Observatory (GRO) and air Cerenkov telescopes. This array and the future MILAGRO Water Cerenkov Detector can perform observations that are simultaneous with similar experiments to provide confirmation of emission, and can measure source spectra at a range of high energies previously unexplored

  12. Development of a Telescope for Medium-Energy Gamma-ray Astronomy

    Science.gov (United States)

    Sunter, Stan

    2012-01-01

    Since the launch of AGILE and FERMI, the scientific progress in high-energy (Eg greater than approximately 200 MeV) gamma-ray science has been, and will continue to be dramatic. Both of these telescopes cover a broad energy range from approximately 20 MeV to greater than 10 GeV. However, neither instrument is optimized for observations below approximately 200 MeV where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. Hence, while significant progress from current observations is expected, there will nonetheless remain a significant sensitivity gap in the medium-energy (approximately 0.1-200 MeV) regime; the lower end of this range remains largely unexplored whereas the upper end will allow comparison with FERMI data. Tapping into this unexplored regime requires significant improvements in sensitivity. A major emphasis of modern detector development, with the goal of providing significant improvements in sensitivity in the medium-energy regime, focuses on high-resolution electron tracking. The Three-Dimensional Track Imager (3-DTI) technology being developed at GSFC provides high resolution tracking of the electron-positron pair from gamma-ray interactions from 5 to 200 MeV. The 3-DTI consists of a time projection chamber (TPC) and 2-D cross-strip microwell detector (MWD). The low-density and homogeneous design of the 3-DTI, offers unprecedented sensitivity by providing angular resolution near the kinematic limit. Electron tracking also enables measurement of gamma-ray polarization, a new tool to study astrophysical phenomenon. We describe the design, fabrication, and performance of a 30x30x30 cm3 3-DTI detector prototype of a medium-energy gamma-ray telescope.

  13. Astrophysical Sources of Cosmic Rays and Related Measurements with the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, : J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Ahn, E.J.; Allard, D.; Allekotte, I.; Allen, J.; Alvarez-Muniz, J.; Ambrosio, M.; Anchordoqui, L.

    2009-06-01

    These are presentations to be presented at the 31st International Cosmic Ray Conference, in Lodz, Poland during July 2009. It consists of the following presentations: (1) Correlation of the highest energy cosmic rays with nearby extragalactic objects in Pierre Auger Observatory data; (2) Discriminating potential astrophysical sources of the highest energy cosmic rays with the Pierre Auger Observatory; (3) Intrinsic anisotropy of the UHECR from the Pierre Auger Observatory; (4) Ultra-high energy photon studies with the Pierre Auger Observatory; (5) Limits on the flux of diffuse ultra high energy neutrinos set using the Pierre Auger Observatory; (6) Search for sidereal modulation of the arrival directions of events recorded at the Pierre Auger Observatory; (7) Cosmic Ray Solar Modulation Studies in the Pierre Auger Observatory; (8) Investigation of the Displacement Angle of the Highest Energy Cosmic Rays Caused by the Galactic Magnetic Field; (9) Search for coincidences with astrophysical transients in Pierre Auger Observatory data; and (10) An alternative method for determining the energy of hybrid events at the Pierre Auger Observatory.

  14. EDGE: Explorer of diffuse emission and gamma-ray burst explosions

    DEFF Research Database (Denmark)

    Den Herder, J.W.; Hermsen, W.; Hoevers, H.

    2007-01-01

    cluster formation, down to the very low redshift Universe, when between a third and one half of the baryons are expected to reside in cosmic filaments undergoing gravitational collapse by dark matter (the so-called warm hot intragalactic medium). In addition EDGE, with its unprecedented capabilities......How structures of various scales formed and evolved from the early Universe up to present time is a fundamental question of astrophysics. EDGE1 will trace the cosmic history of the baryons from the early generations of massive stars by Gamma-Ray Burst (GRB) explosions, through the period of galaxy...

  15. EDGE: Explorer of diffuse emission and gamma-ray burst explosions

    DEFF Research Database (Denmark)

    Piro, L; den Herder, J W; Ohashi, T

    2009-01-01

    , through the period of galaxy cluster formation, down to the very low redshift Universe, when between a third and one half of the baryons are expected to reside in cosmic filaments undergoing gravitational collapse by dark matter (the so-called warm hot intragalactic medium). In addition EDGE, with its......How structures of various scales formed and evolved from the early Universe up to present time is a fundamental question of astrophysical cosmology. EDGE (Piro et al., 2007) will trace the cosmic history of the baryons from the early generations of massive stars by Gamma-Ray Burst (GRB) explosions...

  16. Search for neutrino emission from gamma-ray flaring blazars with the ANTARES telescope

    OpenAIRE

    Adrián-Martínez, S.; Al Samarai, Imen; Albert, A.; André, Michel; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M.; Astraatmadja, T.; Aubert, J.-J.; Baret, B.; Basa, S.; Bertin, V.; Biagi, S.; Bigongiari, C.

    2011-01-01

    The ANTARES telescope is well-suited to detect neutrinos produced in astrophysical transient sources as it can observe a full hemisphere of the sky at all times with a high duty cycle. Radio-loud active galactic nuclei with jets pointing almost directly towards the observer, the so-called blazars, are particularly attractive potential neutrino point sources. The all-sky monitor LAT on board the Fermi satellite probes the variability of any given gamma-ray bright blazar in the sky on time scal...

  17. Hard X-ray irradiation of cosmic silicate analogs: structural evolution and astrophysical implications

    Science.gov (United States)

    Gavilan, L.; Jäger, C.; Simionovici, A.; Lemaire, J. L.; Sabri, T.; Foy, E.; Yagoubi, S.; Henning, T.; Salomon, D.; Martinez-Criado, G.

    2016-03-01

    Context. Protoplanetary disks, interstellar clouds, and active galactic nuclei contain X-ray-dominated regions. X-rays interact with the dust and gas present in such environments. While a few laboratory X-ray irradiation experiments have been performed on ices, X-ray irradiation experiments on bare cosmic dust analogs have been scarce up to now. Aims: Our goal is to study the effects of hard X-rays on cosmic dust analogs via in situ X-ray diffraction. By using a hard X-ray synchrotron nanobeam, we seek to simulate cumulative X-ray exposure on dust grains during their lifetime in these astrophysical environments and provide an upper limit on the effect of hard X-rays on dust grain structure. Methods: We prepared enstatite (MgSiO3) nanograins, which are analogs to cosmic silicates, via the melting-quenching technique. These amorphous grains were then annealed to obtain polycrystalline grains. These were characterized via scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) before irradiation. Powder samples were prepared in X-ray transparent substrates and were irradiated with hard X-rays nanobeams (29.4 keV) provided by beamline ID16B of the European Synchrotron Radiation Facility (Grenoble). X-ray diffraction images were recorded in transmission mode, and the ensuing diffractograms were analyzed as a function of the total X-ray exposure time. Results: We detected the amorphization of polycrystalline silicates embedded in an organic matrix after an accumulated X-ray exposure of 6.4 × 1027 eV cm-2. Pure crystalline silicate grains (without resin) do not exhibit amorphization. None of the amorphous silicate samples (pure and embedded in resin) underwent crystallization. We analyze the evolution of the polycrystalline sample embedded in an organic matrix as a function of X-ray exposure. Conclusions: Loss of diffraction peak intensity, peak broadening, and the disappearance of discrete spots and arcs reveal the amorphization

  18. 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)

  19. Focusing Telescopes in Nuclear Astrophysics

    CERN Document Server

    Ballmoos, Peter von

    2007-01-01

    This volume is the first of its kind on focusing gamma-ray telescopes. Forty-eight refereed papers provide a comprehensive overview of the scientific potential and technical challenges of this nascent tool for nuclear astrophysics. The book features articles dealing with pivotal technologies such as grazing incident mirrors, multilayer coatings, Laue- and Fresnel-lenses - and even an optic using the curvature of space-time. The volume also presents an overview of detectors matching the ambitious objectives of gamma ray optics, and facilities for operating such systems on the ground and in space. The extraordinary scientific potential of focusing gamma-ray telescopes for the study of the most powerful sources and the most violent events in the Universe is emphasized in a series of introductory articles. Practicing professionals, and students interested in experimental high-energy astrophysics, will find this book a useful reference

  20. Gamma ray lines from a universal extra dimension

    Energy Technology Data Exchange (ETDEWEB)

    Bertone, Gianfranco; Jackson, C. B.; Shaughnessy, Gabe; Tait, Tim M.P.; Vallinotto, Alberto

    2012-03-01

    Indirect Dark Matter searches are based on the observation of secondary particles produced by the annihilation or decay of Dark Matter. Among them, gamma-rays are perhaps the most promising messengers, as they do not suffer deflection or absorption on Galactic scales, so their observation would directly reveal the position and the energy spectrum of the emitting source. Here, we study the detailed gamma-ray energy spectrum of Kaluza--Klein Dark Matter in a theory with 5 Universal Extra Dimensions. We focus in particular on the two body annihilation of Dark Matter particles into a photon and another particle, which produces monochromatic photons, resulting in a line in the energy spectrum of gamma rays. Previous calculations in the context of the five dimensional UED model have computed the line signal from annihilations into \\gamma \\gamma, but we extend these results to include \\gamma Z and \\gamma H final states. We find that these spectral lines are subdominant compared to the predicted \\gamma \\gamma signal, but they would be important as follow-up signals in the event of the observation of the \\gamma \\gamma line, in order to distinguish the 5d UED model from other theoretical scenarios.

  1. CENTRAL ENGINE MEMORY OF GAMMA-RAY BURSTS AND SOFT GAMMA-RAY REPEATERS

    International Nuclear Information System (INIS)

    Zhang, Bin-Bin; Castro-Tirado, Alberto J.; Zhang, Bing

    2016-01-01

    Gamma-ray bursts (GRBs) are bursts of γ-rays generated from relativistic jets launched from catastrophic events such as massive star core collapse or binary compact star coalescence. Previous studies suggested that GRB emission is erratic, with no noticeable memory in the central engine. Here we report a discovery that similar light curve patterns exist within individual bursts for at least some GRBs. Applying the Dynamic Time Warping method, we show that similarity of light curve patterns between pulses of a single burst or between the light curves of a GRB and its X-ray flare can be identified. This suggests that the central engine of at least some GRBs carries “memory” of its activities. We also show that the same technique can identify memory-like emission episodes in the flaring emission in soft gamma-ray repeaters (SGRs), which are believed to be Galactic, highly magnetized neutron stars named magnetars. Such a phenomenon challenges the standard black hole central engine models for GRBs, and suggest a common physical mechanism behind GRBs and SGRs, which points toward a magnetar central engine of GRBs

  2. Neural network consistent empirical physical formula construction for neutron–gamma discrimination in gamma ray tracking

    International Nuclear Information System (INIS)

    Yildiz, Nihat; Akkoyun, Serkan

    2013-01-01

    Highlights: ► Detector responses in neutron–gamma discrimination were estimated by neural networks. ► Novel consistent neural network empirical physical formulas (EPFs) were constructed for detector responses. ► The EPFs are of explicit mathematical functional form. ► The EPFs can be used to derive various physical functions relevant to neutron–gamma discrimination in gamma ray tracking. -- Abstract: Gamma ray tracking is an efficient detection technique in studying exotic nuclei which lies far from beta stability line. To achieve very powerful and extraordinary resolution ability, new detectors based on gamma ray tracking are currently being developed. To reach this achievement, the neutron–gamma discrimination in these detectors is also an important task. In this paper, by suitable layered feedforward neural networks (LFNNs), we have constructed novel and consistent empirical physical formulas (EPFs) for some highly nonlinear detector counts measured in neutron–gamma discrimination. The detector counts data used in the discrimination was actually borrowed from our previous paper. The counts used here had been originally measured versus the following parameters: energy deposited in the first interaction points, difference in the incoming direction of initial gamma rays, and finally figure of merit values of the clusters determined by tracking. The LFNN–EPFs are of explicit mathematical functional form. Therefore, by various suitable operations of mathematical analysis, these LFNN–EPFs can be used to derivate further physical functions which might be potentially relevant to neutron–gamma discrimination performance of gamma ray tracking.

  3. High energy gamma-ray production in nuclear reactions

    International Nuclear Information System (INIS)

    Pinston, J.A.; Nifenecker, H.; Nifenecker, H.

    1989-01-01

    Experimental techniques used to study high energy gamma-ray production in nuclear reactions are reviewed. High energy photon production in nucleus-nucleus collisions is discussed. Semi-classical descriptions of the nucleus-nucleus gamma reactions are introduced. Nucleon-nucleon gamma cross sections are considered, including theoretical aspects and experimental data. High energy gamma ray production in proton-nucleus reactions is explained. Theoretical explanations of photon emission in nucleus-nucleus collisions are treated. The contribution of charged pion currents to photon production is mentioned

  4. Prompt gamma-ray analysis of steel slag in concrete

    International Nuclear Information System (INIS)

    Naqvi, Akhtar Abbas; Garwan, Muhammad Ahmad; Nagadi, Mahmoud Mohammad; Rehman, Khateeb-ur; Raashid, Mohammad; Masalehuddin Mohiuddin, Mohammad; Al-Amoudi, Omar Saeed Baghabra

    2009-01-01

    Blast furnace slag (BFS) is added to Portland cement concrete to increase its durability, particularly its corrosion resistance. Monitoring the concentration of BFS in concrete for quality control purposes is desired. In this study, the concentration of BFS in concrete was measured by utilizing an accelerator-based prompt gamma-ray neutron activation analysis (PGNAA) setup. The optimum size of the BFS cement concrete specimen that produces the maximum intensity of gamma rays at the detector location was calculated through Monte Carlo simulations. The simulation results were experimentally validated through the gamma-ray yield measurement from BFS cement concrete specimens having different radii. The concentration of BFS in the cement concrete specimens was assessed through calcium and silicon gamma-ray yield measurement from cement concrete specimens containing 5 to 80 wt% BFS. The yield of calcium gamma rays decreases with increasing BFS concentration in concrete while the yield of silicon gamma rays increases with increasing BFS concentration in concrete. The calcium-to-silicon gamma-ray yield ratio has an inverse relation with BFS concentration in concrete. (author)

  5. Guidelines for radioelement mapping using gamma ray spectrometry data

    International Nuclear Information System (INIS)

    2003-07-01

    The purpose of the report is to provide an up-to-date review on the use of gamma ray spectrometry for radioelement mapping and, where appropriate, provide guidelines on the correct application of the method. It is a useful training guide for those new to the method. It gives a broad coverage of all aspects of the gamma ray method and provides a comprehensive list of references. The report gives an overview of the theoretical background to radioactivity and the gamma ray spectrometric method followed by a review of the application of the method to mapping the radiation environment. A brief outline is presented of the principles of radioactivity, the interaction of gamma rays with matter, instrumentation applied to the measurement of gamma rays, and the quantities and units in contemporary use in gamma ray spectrometry. This is followed by a review of the fundamentals of gamma ray spectrometry, and its application to ground and airborne mapping. Covered are also all aspects of the calibration and data processing procedures required for estimating the ground concentrations of the radioelements. The procedures required for the recovery of older survey data are also presented as well as an overview of data presentation and integration for mapping applications

  6. Multiple Gamma-Ray Detection Capability of a CeBr3 Detector for Gamma Spectroscopy

    Directory of Open Access Journals (Sweden)

    A. A. Naqvi

    2017-01-01

    Full Text Available The newly developed cerium tribromide (CeBr3 detector has reduced intrinsic gamma-ray activity with gamma energy restricted to 1400–2200 keV energy range. This narrower region of background gamma rays allows the CeBr3 detector to detect more than one gamma ray to analyze the gamma-ray spectrum. Use of multiple gamma-ray intensities in elemental analysis instead of a single one improves the accuracy of the estimated results. Multigamma-ray detection capability of a cylindrical 75 mm × 75 mm (diameter × height CeBr3 detector has been tested by analyzing the chlorine concentration in water samples using eight chlorine prompt gamma rays over 517 to 8578 keV energies utilizing a D-D portable neutron generator-based PGNAA setup and measuring the corresponding minimum detection limit (MDC of chlorine. The measured MDC of chlorine for gamma rays with 517–8578 keV energies varies from 0.07 ± 0.02 wt% to 0.80 ± 0.24. The best value of MDC was measured to be 0.07 ± 0.02 wt% for 788 keV gamma rays. The experimental results are in good agreement with Monte Carlo calculations. The study has shown excellent detection capabilities of the CeBr3 detector for eight prompt gamma rays over 517–8578 keV energy range without significant background interference.

  7. Modeling X-ray Spectra of Astrophysical Plasmas: Current Status and Future Needs

    Science.gov (United States)

    Smith, Randall

    Existing high-resolution astrophysical X-ray spectra has exposed the need for high-quality atomic data of all stripes: wavelengths, collisional and absorption cross sections, and radiative rates. The Astro-H soft X-ray spectrometer (2015 launch) will vastly increase the number and type of high-resolution X-ray spectra available and likely expose a number of shortcomings in our models. I will describe recent advances in theoretical calculations and laboratory measurements, as well as a number of existing needs in the field. These include accurate soft X-ray wavelengths for L-shell ions, diagnostic emission line ratios with estimated error bars, and high-resolution absorption cross sections for abundant ions and molecules. Finally, new models of emission from non-equilibrium ionization plasmas and astrophysical charge exchange will be discussed. This latter emission arises due to the interaction of highly charged ions with neutral atoms, forming a diffuse background in the case of solar wind ions and possibly also arising in more distant environments.

  8. The B-10((p)over-right-arrow, gamma)C-11 reaction at astrophysically relevant energies

    NARCIS (Netherlands)

    Tonchev, AP; Nelson, SO; Sabourov, K; Crowley, BT; Joshi, K; Weller, HR; Kelley, JH; Prior, RM; Spraker, M; Kalantar-Nayestanaki, N

    2003-01-01

    The B-10(, gamma)C-11 reaction was studied by detecting the gamma-rays produced when 100, 130-, and 160-keV polarized protons were stopped in a thick B-10 target. Polarized and unpolarized incident beams were used to measure the cross section and vector analyzing power as a function of angle and

  9. Generation of laser Compton gamma-rays using Compact ERL

    International Nuclear Information System (INIS)

    Shizuma, Toshiyuki; Hajima, Ryoichi; Nagai, Ryoji; Hayakawa, Takehito; Mori, Michiaki; Seya, Michio

    2015-01-01

    Nondestructive isotope-specific assay system using nuclear resonance fluorescence has been developed at JAEA. In this system, intense, mono-energetic laser Compton scattering (LCS) gamma-rays are generated by combining an energy recovery linac (ERL) and laser enhancement cavity. As technical development for such an intense gamma-ray source, we demonstrated generation of LCS gamma-rays using Compact ERL (supported by the Ministry of Education, Culture, Sports, Science and Technology) developed in collaboration with KEK. We also measured X-ray fluorescence for elements near iron region by using mono-energetic LCS gamma-rays. In this presentation, we will show results of the experiment and future plan. (author)

  10. Summary of existing information on gamma-ray and X-ray attenuation coefficients of solutions

    DEFF Research Database (Denmark)

    Singh, K.; Gerward, Leif

    2002-01-01

    Accurate values of X-ray and gamma-ray attenuation coefficients of different chemicals are required in spectrometry as well as in many other scientific, engineering and medical disciplines involving photon radiation. The current state of knowledge of experimental and theoretical gamma-ray and X-r......-ray attenuation coefficients in aqueous solutions of salts is presented and exemplified by recent work. The results presented provide a basis for studying X-ray and gamma-ray photon interactions with ions in solution (hydrated ions) rather than ion compounds in solid form....

  11. Effect of /sup 60/Co. gamma. -rays on polyphenyl methacrylate obtained by. gamma. -ray irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Raghunath, S.; Rao, M.H.; Rao, K.N. (Bhabha Atomic Research Centre, Bombay (India). Chemistry Div.)

    1983-01-01

    Polyphenyl methacrylate of different molecular weights Msub(n) 13000, 34500 and crosslinked polymer prepared by /sup 60/Co ..gamma..-irradiation has been irradiated with /sup 60/Co ..gamma..-rays at 300 K. G(scission) of the 13000 molecular weight polymer was 15. The crosslinked polymer undergoes both degradation and crosslinking. G(x) value determined for that polymer is approx. 9. The gaseous product consists largely of CO with some CO/sub 2/ and H/sub 2/. Hydrocarbon gases were not detected. The yield of H/sub 2/ is only to the extent of 2 to 5% of the total gas and it is assumed that majority of scission takes place at the ester linkage. On the basis of the estimation of phenol and benzene, a mechanism for degradation and crosslinking is proposed.

  12. The LASL gamma-ray burst astronomy program

    International Nuclear Information System (INIS)

    Klebesadel, R.W.; Evans, W.D.; Laros, J.G.

    1981-01-01

    Gamma-ray burst observations performed by LASL began with the identification and initial report of the phenomenon from data acquired by the Vela satellites. The Vela instruments have recorded responses to 73 gamma-ray bursts over a ten-year interval, and are continuing to contribute toward these observations. Similar instrumentation was included aboard the NRL SOLRAD 11 spacecraft. These performed well but suffered an early demise. Recently, the LASL gamma-ray burst astronomy program has been enhanced through the implementation of experiments aboard the Pioneer Venus Orbiter and ISEF-C spacecraft. Both of these experiments are continuing to contribute data vital to trigonometric directional analyses. (orig.)

  13. Evaluation of effective dose equivalent from environmental gamma rays

    International Nuclear Information System (INIS)

    Saito, K.; Tsutsumi, M.; Moriuchi, S.; Petoussi, N.; Zankl, M.; Veit, R.; Jacob, P.; Drexler, G.

    1991-01-01

    Organ doses and effective dose equivalents for environmental gamma rays were calculated using human phantoms and Monte Carlo methods accounting rigorously the environmental gamma ray fields. It was suggested that body weight is the dominant factor to determine organ doses. The weight function expressing organ doses was introduced. Using this function, the variation in organ doses due to several physical factors were investigated. A detector having gamma-ray response similar to that of human bodies has been developed using a NaI(Tl) scintillator. (author)

  14. Gamma-ray bursts from black hole accretion disks

    International Nuclear Information System (INIS)

    Strong, I.B.

    1975-01-01

    The suggestion was first made more than a year ago that gamma-ray bursts might originate in the neighborhood of black holes, based on some rather circumstantial evidence linking Cygnus X-1, the prime black-hole candidate, with two of the then-known gamma-ray bursts. Since then additional evidence makes the idea still more plausible. The evidence is summarized briefly, a physical model for production of gamma-ray bursts is given, and several of the more interesting consequences of such an origin are pointed out. (orig.) [de

  15. Cellular response to low Gamma-ray doses

    Energy Technology Data Exchange (ETDEWEB)

    Manzanares A, E; Vega C, H R; Leon, L.C. de . [Unidades Academicas de Estudios Nucleares, Universidad Autonoma de Zacatecas, A.P. 336, 98000 Zacatecas (Mexico); Rebolledo D, O; Radillo J, F [Facultad de Ciencias Biologicas y Agropecuarias de la Universidad de Colima, Colima (Mexico)

    2002-07-01

    Lymphocytes, obtained from healthy donors, were exposed to a low strength gamma-ray field to determine heat shock protein expression in function of radiation dose. Protein identification was carried out using mAb raised against Hsp70 and Hsc70.Hsp70 protein was detected after lymphocyte irradiation. In all cases, an increasing trend of relative amounts of Hsp70 in function to irradiation time was observed. After 1.25 c Gy gamma-ray dose, lymphocytes expressed Hsp70 protein, indicating a threshold response to gamma rays. (Author)

  16. High energy photons and neutrinos from gamma ray bursts

    International Nuclear Information System (INIS)

    Dar, A.

    1998-01-01

    The Hubble space telescope has recently discovered thousands of gigantic comet-like objects in a ring around the central star in the nearest planetary nebula. It is suggested that such circumstellar rings exist around most of stars. Collisions of the relativistic debris from gamma ray bursts in dense stellar regions with such gigantic comet-like objects, which have been stripped off from the circumstellar rings by gravitational perturbations, produce detectable fluxes of high energy gamma-rays and neutrinos from gamma ray bursts

  17. Analytical applications of neutron capture gamma-rays

    International Nuclear Information System (INIS)

    Lindstrom, R.M.; Paul, R.L.; Anderson, D.L.; Paul, R.L.

    1997-01-01

    Field and industrial applications of neutron capture gamma-ray spectrometry with isotopic sources or neutron generators are economically important. Geochemical exploration in boreholes is done routinely with neutron probes. Coal and ores are assayed with analyzers adjacent to a conveyor belt in dozens of industrial facilities. The use of capture gamma rays for explosives detection has been described in the literature, both for scanning airline baggage and for characterizing obsolete munitions; a packaged system for the latter is available commercially. Generalizations are drawn from the history of the field, and predictions are made about the future usefulness of capture gamma rays. (author)

  18. Cellular response to low Gamma-ray doses

    International Nuclear Information System (INIS)

    Manzanares A, E.; Vega C, H.R.; Leon, L.C. de; Rebolledo D, O.; Radillo J, F.

    2002-01-01

    Lymphocytes, obtained from healthy donors, were exposed to a low strength gamma-ray field to determine heat shock protein expression in function of radiation dose. Protein identification was carried out using mAb raised against Hsp70 and Hsc70.Hsp70 protein was detected after lymphocyte irradiation. In all cases, an increasing trend of relative amounts of Hsp70 in function to irradiation time was observed. After 1.25 c Gy gamma-ray dose, lymphocytes expressed Hsp70 protein, indicating a threshold response to gamma rays. (Author)

  19. Gamma ray astronomy and search for antimatter in the universe

    International Nuclear Information System (INIS)

    Schoenfelder, V.

    1989-01-01

    Gamma ray astronomy provides a powerful tool for searching antimatter in the universe; it probably provides the only means to determine, if the universe has baryon symmetry. Presently existing gamma-ray observations can be interpreted without postulating the existence of antimatter. However, the measurements are not precise enough to definitely exclude the possibility of its existence. The search for antimatter belongs to one of the main scientific objectives of the Gamma Ray Observatory GRO of NASA, which will be launched in 1990 by the Space Shuttle. (orig.)

  20. Tenth International Colloquium on UV and X-Ray Spectroscopy of Astrophysical and Laboratory Plasmas

    Science.gov (United States)

    Silver, Eric H.; Kahn, Steven M.

    UV and X-ray spectroscopy of astrophysical and laboratory plasmas draws interest from many disciplines. Contributions from international specialists are collected together in this book from a timely recent conference. In astrophysics, the Hubble Space Telescope, Astro 1 and ROSAT observatories are now providing UV and X-ray spectra and images of cosmic sources in unprecedented detail, while the Yohkoh mission recently collected superb data on the solar corona. In the laboratory, the development of ion-trap facilities and novel laser experiments are providing vital new data on high temperature plasmas. Recent innovations in the technology of spectroscopic instrumentation are discussed. These papers constitute an excellent up-to-date review of developments in short-wavelength spectroscopy and offer a solid introduction to its theoretical and experimental foundations. These proceedings give an up-to-date review of developments in short-wavelength spectroscopy and offer a solid introduction to its theoretical and experimental foundations. Various speakers presented some of the first results from the high resolution spectrograph on the Hubble Space Telescope, the high sensitivity far ultraviolet and X-ray spectrometers of the ASTRO 1 Observatory, the imaging X-ray spectrometer on the ROSAT Observatory, and the high resolution solar X-ray spectrometer on Yohkoh. The development of ion trap devices had brought about a revolution in laboratory investigations of atomic processes in highly charged atoms. X-ray laser experiments had not only yielded considerable insight into electron ion interactions in hot dense plasmas, but also demonstrated the versatility of laser plasmas as laboratory X-ray sources. Such measurements also motivated and led to refinements in the development of large-scale atomic and molecular codes. On the instrumental side, the design and development of the next series of very powerful short wavelength observatories had generated a large number of

  1. X-ray Fluorescence Spectroscopy: the Potential of Astrophysics-developed Techniques

    Science.gov (United States)

    Elvis, M.; Allen, B.; Hong, J.; Grindlay, J.; Kraft, R.; Binzel, R. P.; Masterton, R.

    2012-12-01

    X-ray fluorescence from the surface of airless bodies has been studied since the Apollo X-ray fluorescence experiment mapped parts of the lunar surface in 1971-1972. That experiment used a collimated proportional counter with a resolving power of ~1 and a beam size of ~1degree. Filters separated only Mg, Al and SI lines. We review progress in X-ray detectors and imaging for astrophysics and show how these advances enable much more powerful use of X-ray fluorescence for the study of airless bodies. Astrophysics X-ray instrumentation has developed enormously since 1972. Low noise, high quantum efficiency, X-ray CCDs have flown on ASCA, XMM-Newton, the Chandra X-ray Observatory, Swift and Suzaku, and are the workhorses of X-ray astronomy. They normally span 0.5 to ~8 keV with an energy resolution of ~100 eV. New developments in silicon based detectors, especially individual pixel addressable devices, such as CMOS detectors, can withstand many orders of magnitude more radiation than conventional CCDs before degradation. The capability of high read rates provides dynamic range and temporal resolution. Additionally, the rapid read rates minimize shot noise from thermal dark current and optical light. CMOS detectors can therefore run at warmer temperatures and with ultra-thin optical blocking filters. Thin OBFs mean near unity quantum efficiency below 1 keV, thus maximizing response at the C and O lines.such as CMOS detectors, promise advances. X-ray imaging has advanced similarly far. Two types of imager are now available: specular reflection and coded apertures. X-ray mirrors have been flown on the Einstein Observatory, XMM-Newton, Chandra and others. However, as X-ray reflection only occurs at small (~1degree) incidence angles, which then requires long focal lengths (meters), mirrors are not usually practical for planetary missions. Moreover the field of view of X-ray mirrors is comparable to the incident angle, so can only image relatively small regions. More useful

  2. Gamma ray induced mutants in Coleus

    International Nuclear Information System (INIS)

    Vasudevan, K.; Jos, J.S.

    1988-01-01

    The germplasm collection of Chinese potato (Coleus parviflorus Benth) contains almost no variation for yield contributing traits. The crop does not produce seeds. Treatment of underground tubers with 1 kR, 2 kR, 3 kR and 4 kR gamma rays resulted in 50 morphologically different mutants which are maintained as mutant clones. In the M 1 V 1 generation, suspected mutant sprouts, were carefully removed and grown separately. The most interesting mutant types are the following: (i) erect mutant with spoon shaped light green leaves, 30 cm long inflorescences against 20 cm in the control, cylindrical tubers measuring ca. 7.0 cm long and 3 cm girth against 4 cm and 2.5 cm in the control (ii) early mutants 1 and 2, one having less leaf serration, the other having light green small leaves and dwarf type (iii) fleshy leaf mutant, dark green, thick and smooth leaves. Control plants spread almost in 1 m 2 area and bear tubers from the nodes of branches. In the early mutants tuber formation is mainly restricted to the base of the plant, which makes harvest easier. The crop usually matures within 150 - 160 days, the early mutants are ready for harvest 100 days after planting. As the mutants are less spreading, the yield could be increased by closer spacing

  3. Observations of short gamma-ray bursts.

    Science.gov (United States)

    Fox, Derek B; Roming, Peter W A

    2007-05-15

    We review recent observations of short-hard gamma-ray bursts and their afterglows. The launch and successful ongoing operations of the Swift satellite, along with several localizations from the High-Energy Transient Explorer mission, have provoked a revolution in short-burst studies: first, by quickly providing high-quality positions to observers; and second, via rapid and sustained observations from the Swift satellite itself. We make a complete accounting of Swift-era short-burst localizations and proposed host galaxies, and discuss the implications of these observations for the distances, energetics and environments of short bursts, and the nature of their progenitors. We then review the physical modelling of short-burst afterglows: while the simplest afterglow models are inadequate to explain the observations, there have been several notable successes. Finally, we address the case of an unusual burst that threatens to upset the simple picture in which long bursts are due to the deaths of massive stars, and short bursts to compact-object merger events.

  4. Gamma ray induced mutants in Coleus

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, K; Jos, J S [Central Tuber Crops Research Institute, Trivandrum, Kerala (India)

    1988-07-01

    The germplasm collection of Chinese potato (Coleus parviflorus Benth) contains almost no variation for yield contributing traits. The crop does not produce seeds. Treatment of underground tubers with 1 kR, 2 kR, 3 kR and 4 kR gamma rays resulted in 50 morphologically different mutants which are maintained as mutant clones. In the M{sub 1}V{sub 1} generation, suspected mutant sprouts, were carefully removed and grown separately. The most interesting mutant types are the following: (i) erect mutant with spoon shaped light green leaves, 30 cm long inflorescences against 20 cm in the control, cylindrical tubers measuring ca. 7.0 cm long and 3 cm girth against 4 cm and 2.5 cm in the control (ii) early mutants 1 and 2, one having less leaf serration, the other having light green small leaves and dwarf type (iii) fleshy leaf mutant, dark green, thick and smooth leaves. Control plants spread almost in 1 m{sup 2} area and bear tubers from the nodes of branches. In the early mutants tuber formation is mainly restricted to the base of the plant, which makes harvest easier. The crop usually matures within 150 - 160 days, the early mutants are ready for harvest 100 days after planting. As the mutants are less spreading, the yield could be increased by closer spacing.

  5. Uses Of Gamma Rays In Peas Breeding

    International Nuclear Information System (INIS)

    Ghunim, A.; Mobakher, H.; Salman, S.

    2004-01-01

    Most of peas varieties grown in Syria are introduced and they have variable characteristics and unstable in the productivity. Therefore this study aims to utilize physical mutagens as the developed technology in plant breeding to obtain high, stable productivity and suitable for human consumption and processing. Two green peas vars (onward, local homsi) were used in this study, and their dry seeds were subjected to different doses of Gamma rays (5.0,7.5,10.0) KR and planted conventional used methods at AL Taibba searching station (20 Km from Damascus) in 1985/1986 season. Individual selection from M2 was practiced based on yield traits. Starting from 1991/1992 season the best selected mutants were used in yield trials to be compared with the best common cultivars. After/3/years of yield trials, the advanced lines were incorporated into field test trials. Some morphological and phonological scores, i.e. green pods yield, dry seeds yield per area were achieved in addition to lab tests. Some strains have advanced in yield of green pods and dry seeds per area compared with the local check. Some other strains. Showed an increase in earliness, length of pods, number of seeds per pod, and number of pods per plant than the local check. Therefore these can be called promising strains and as nucleus for new vars. will be used into verifiable fields, and in large-scale cultivation in order to be released. (Authors)

  6. Observations of cosmic gamma ray bursts with WATCH on EURECA

    DEFF Research Database (Denmark)

    Brandt, Søren; Lund, N.; Castro-Tirado, A. J.

    1995-01-01

    19 Cosmic Gamma-Ray Bursts were detected by the WATCH wide field X-ray monitor during the 11 months flight of EURECA. The identification of the bursts were complicated by a high frequency of background of events caused by high energy cosmic ray interactions in the detector and by low energy, trap...

  7. INTEGRAL Detection of the First Prompt Gamma-Ray Signal Coincident with the Gravitational-wave Event GW170817

    DEFF Research Database (Denmark)

    Savchenko, V.; Ferrigno, C.; Kuulkers, E.

    2017-01-01

    We report the INTernational Gamma-ray Astrophysics Laboratory (INTEGRAL) detection of the short gamma-ray burst GRB 170817A (discovered by Fermi-GBM) with a signal-to-noise ratio of 4.6, and, for the first time, its association with the gravitational waves (GWs) from binary neutron star (BNS......) merging event GW170817 detected by the LIGO and Virgo observatories. The significance of association between the gamma-ray burst observed by INTEGRAL and GW170817 is 3.2σ, while the association between the Fermi-GBM and INTEGRAL detections is 4.2σ. GRB 170817A was detected by the SPI-ACS instrument about...

  8. A novel background reduction strategy for high level triggers and processing in gamma-ray Cherenkov detectors

    International Nuclear Information System (INIS)

    Cabras, G.; De Angelis, A.; De Lotto, B.; De Maria, M. M.; De Sabata, F.; Mansutti, O.; Frailis, M.; Persic, M.; Bigongiari, C.; Doro, M.; Mariotti, M.; Peruzzo, L.; Saggion, A.; Scalzotto, V.; Paoletti, R.; Scribano, A.; Turini, N.; Moralejo, A.; Tescaro, D.

    2008-01-01

    Gamma ray astronomy is now at the leading edge for studies related both to fundamental physics and astrophysics. The sensitivity of gamma detectors is limited by the huge amount of background, constituted by hadronic cosmic rays (typically two to three orders of magnitude more than the signal) and by the accidental background in the detectors. By using the information on the temporal evolution of the Cherenkov light, the background can be reduced. We will present here the results obtained within the MAGIC experiment using a new technique for the reduction of the background. Particle showers produced by gamma rays show a different temporal distribution with respect to showers produced by hadrons; the background due to accidental counts shows no dependence on time. Such novel strategy can increase the sensitivity of present instruments

  9. The early X-ray afterglows of optically bright and dark Gamma-Ray Bursts

    OpenAIRE

    Lin, Yi-Qing

    2006-01-01

    A systematical study on the early X-ray afterglows of both optically bright and dark gamma-ray bursts (B-GRBs and D-GRBs) observed by Swift has been presented. Our sample includes 25 GRBs. Among them 13 are B-GRBs and 12 are D-GRBs. Our results show that the distributions of the X-ray afterglow fluxes ($F_{X}$), the gamma-ray fluxes ($S_{\\gamma}$), and the ratio ($R_{\\gamma, X}$) for both the D-GRBs and B-GRBs are similar. The differences of these distributions for the two kinds of GRBs shoul...

  10. A study on gamma rays from electrochemical cells

    International Nuclear Information System (INIS)

    Shin, Seung Ai

    1993-01-01

    The energies and intensities of gamma rays emitted from 3 cells with Pd-cathodes of φ 1mm x 10mm, φ 2mm x 20mm, φ 1mm x 10mm were determined using HPGe-detector system and compared with Pd-neutron capture model. Very strong gamma rays of 512keC, 622keC, 1051keC and 8 more important ones were found to be identical with characteristic gamma rays of 106 Pd and 109 Pd. It is likely that the neutron capture reaction, A PD(n, γ) A+1 Pd, occurred in the cell and the neutrons came from the fusion reaction of two deutrons. It is necessary, however, to retest the model since another strong 84keV-gamma rays do not belong to any A+1 Pd-gamma spectra and two important 106 Pd-gamma rays 717keV, 1046KeV were not detected. Total amount of emitted gamma rays was large when the size of the Pd-cathod was large. Its depedence on the time of measurement and the preheating period did not have any regularities. Thus the replication is not an easy thing. (Author)

  11. Gamma ray astronomy above 30 TeV and the IceCube results

    Directory of Open Access Journals (Sweden)

    Vernetto Silvia

    2017-01-01

    Full Text Available The study of the diffuse Galactic gamma ray emission is of fundamental importance to understand the properties of cosmic ray propagation in the Milky Way, and extending the measurements to E ≳ 30 TeV is of great interest. In the same energy range the IceCube detector has also recently observed a flux of astrophysical neutrinos, and it is important to test experimentally if the neutrino production is accompanied by a comparable emission of high energy photons. For E ≳ 30 TeV, the absorption effects due to e+e− pair production when the high energy photons interact with radiation fields present in space are not negligible and must be taken into account. Gamma rays, in good approximation, are completely absorbed if they have an extragalactic origin, but the absorption is significant also for Galactic photons. In this case the size and angular dependence of the absorption depends on the space distribution of the emission. In this work we estimate the absorption for different models of the space distribution of the gamma ray emission, and discuss the potential of future detectors.

  12. Operations manual for the megachannel gamma-ray coincidence system

    International Nuclear Information System (INIS)

    Ruhter, W.

    1977-01-01

    To aid in the study of nuclear structures, a megachannel pulse-height coincidence analysis system on a PDP-8 computer was constructed. The system digitizes the energies of coincident gamma-rays and stores the resultant information on a moving-head disk. The system uses a minicomputer to sort and store gamma-gamma coincident information on line. The megachannel system and how to use it are described

  13. NO CORRELATION BETWEEN HOST GALAXY METALLICITY AND GAMMA-RAY ENERGY RELEASE FOR LONG-DURATION GAMMA-RAY BURSTS

    International Nuclear Information System (INIS)

    Levesque, Emily M.; Kewley, Lisa J.; Soderberg, Alicia M.; Berger, Edo

    2010-01-01

    We compare the redshifts, host galaxy metallicities, and isotropic (E γ,iso ) and beaming-corrected (E γ ) gamma-ray energy release of 16 long-duration gamma-ray bursts (LGRBs) at z γ,iso , or E γ . These results are at odds with previous theoretical and observational predictions of an inverse correlation between gamma-ray energy release and host metallicity, as well as the standard predictions of metallicity-driven wind effects in stellar evolutionary models. We consider the implications that these results have for LGRB progenitor scenarios, and discuss our current understanding of the role that metallicity plays in the production of LGRBs.

  14. Feasibility study of gamma-ray medical radiography

    International Nuclear Information System (INIS)

    Alyassin, Abdalmajeid M.; Maqsoud, Hamza A.; Mashat, Ahmad M.; Al-Mohr, Al-Sayed; Abdulwajid, Subhan

    2013-01-01

    This research explores the feasibility of using gamma-ray radiography in medical imaging. We will show that gamma-ray medical radiography has the potential to provide alternative diagnostic medical information to X-ray radiography. Approximately one Ci Am-241 radioactive source which emits mono-energetic 59.5 keV gamma rays was used. Several factors that influence the feasibility of this study were tested. They were the radiation source uniformity, image uniformity, and image quality parameters such as contrast, noise, and spatial resolution. In addition, several gamma-ray and X-ray images were acquired using humanoid phantoms. These images were recorded on computed radiography image receptors and displayed on a standard monitor. Visual assessments of these images were then conducted. The Am-241 radioactive source provided relatively uniform radiation exposure and images. Image noise and image contrast were mainly dependent on the exposure time and source size, whereas spatial resolution was dependent on source size and magnification factor. The gamma-ray humanoid phantom images were of lower quality than the X-ray images mainly due to the low radioactivity used and not enough exposure time. Nevertheless, the gamma-ray images displayed most of the main structures contained in the humanoid phantoms. Higher exposure rates and thus lower exposure times were estimated for different pure Am-241 source sizes that are hypothesized to provide high quality images similar to X-ray images. For instance, a 10 mm source size of pure Am-241 with 7 s exposure time should produce images similar in contrast and noise to X-ray images. This research paves the way for the production and usage of a highly radioactive Am-241 source with the potential to lead to the feasibility of acceptable quality medical gamma-ray radiography. - Highlights: ► Characterized the performance of gamma-ray radiography. ► Displayed medical images of humanoid phantoms using gamma radiography. ► Am-241

  15. Gamma-ray emission profile measurements during JET ICRH discharges

    Energy Technology Data Exchange (ETDEWEB)

    Jarvis, O N; Marcus, F B; Sadler, G; Van Belle, P [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Howarth, P J.A. [Birmingham Univ. (United Kingdom); Adams, J M; Bond, D S [UKAEA Harwell Lab. (United Kingdom). Energy Technology Div.

    1994-07-01

    Gamma-ray emission from plasma-impurity reactions caused by minority ICRH accelerating fuel ions to MeV energies has been measured using the JET neutron profile monitor. A successful data analysis technique has been used to isolate the RF-induced gamma-ray emission that was detected, enabling profiles of gamma-ray emission to be obtained. The 2-d gamma-ray emission profiles show that virtually all the radiation originates from the low field side of the RF resonance layer, as expected from RF-induced pitch angle diffusion. The emission profiles indicate the presence of a small population of resonant {sup 3}He ions that possess orbits lying near the passing-trapped boundary. 6 refs., 4 figs.

  16. Gamma-ray flares from the Crab Nebula.

    Science.gov (United States)

    Abdo, A A; Ackermann, M; Ajello, M; Allafort, A; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bouvier, A; Brandt, T J; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Cannon, A; Caraveo, P A; Casandjian, J M; Çelik, Ö; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Costamante, L; Cutini, S; D'Ammando, F; Dermer, C D; de Angelis, A; de Luca, A; de Palma, F; Digel, S W; do Couto e Silva, E; Drell, P S; Drlica-Wagner, A; Dubois, R; Dumora, D; Favuzzi, C; Fegan, S J; Ferrara, E C; Focke, W B; Fortin, P; Frailis, M; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M-H; Grove, J E; Guiriec, S; Hadasch, D; Hanabata, Y; Harding, A K; Hayashi, K; Hayashida, M; Hays, E; Horan, D; Itoh, R; Jóhannesson, G; Johnson, A S; Johnson, T J; Khangulyan, D; Kamae, T; Katagiri, H; Kataoka, J; Kerr, M; Knödlseder, J; Kuss, M; Lande, J; Latronico, L; Lee, S-H; Lemoine-Goumard, M; Longo, F; Loparco, F; Lubrano, P; Madejski, G M; Makeev, A; Marelli, M; Mazziotta, M N; McEnery, J E; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Naumann-Godo, M; Nolan, P L; Norris, J P; Nuss, E; Ohsugi, T; Okumura, A; Omodei, N; Ormes, J F; Ozaki, M; Paneque, D; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Pierbattista, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Ray, P S; Razzano, M; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Romani, R W; Sadrozinski, H F-W; Sanchez, D; Saz Parkinson, P M; Scargle, J D; Schalk, T L; Sgrò, C; Siskind, E J; Smith, P D; Spandre, G; Spinelli, P; Strickman, M S; Suson, D J; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J B; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Troja, E; Uchiyama, Y; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Wang, P; Wood, K S; Yang, Z; Ziegler, M

    2011-02-11

    A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10(15) electron volts) electrons in a region smaller than 1.4 × 10(-2) parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory.

  17. Some deficiencies and solutions in gamma ray spectrometry

    International Nuclear Information System (INIS)

    Westmeier, W.

    1998-01-01

    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)

  18. Multidimensional analysis of high resolution. gamma. -ray data

    Energy Technology Data Exchange (ETDEWEB)

    Flibotte, S.; Huettmeier, U.J.; France, G. de; Haas, B.; Romain, P.; Theisen, C.; Vivien, J.P.; Zen, J. (Centre de Recherches Nucleaires, 67 - Strasbourg (France)); Bednarczyk, P. (Inst. of Nuclear Physics, Krakow (Poland))

    1992-08-15

    Algorithms are developed to analyze high-fold {gamma}-ray coincidences. Performances of the programs have been tested in 3, 4 and 5 dimensions using events generated with a Monte Carlo simulation. (orig.).

  19. A new measurement-while-drilling gamma ray log calibrator

    International Nuclear Information System (INIS)

    Meisner, J.; Brooks, A.; Wisniewski, W.

    1985-01-01

    Many of the present methods of calibration for both wireline and MWD gamma ray detectors use a point source at a fixed distance from the detector. MWD calibration errors are introduced from scattering effects, from spectral differences, from position sensitivity and form lack of cylindrical geometry. A new method has been developed at Exploration Logging INc. (EXLOG) that eliminates these errors. The method uses a wrap-around or annular calibrator, referenced to the University of Houston gamma ray API pit. The new calibrator is designed to simulate the API pit's gamma ray emission spectrum with a finite amount of natural source material in the annular shape. Because of the thickness of steel between the MWD gamma ray detector and the formation, there is theoretical necessity for spectral matching. A simple theoretical approach was used to calibrate the new calibrator. Spectral matching allows a closer approximation to wireline logs and makes it possible to estimate the relative spectral content of a formation

  20. Saccharification of gamma-ray and alkali pretreated lignocellulosics

    International Nuclear Information System (INIS)

    Begum, A.; Choudhury, N.

    1988-01-01

    Enzymic saccharification of gamma ray and alkali pretreated sawdust, rice straw, and sugar cane bagasse showed higher release of reducing sugar from pretreated substrates. By gamma ray treatment alone (500 kGy) reducing sugar release of 2.8, 9.2, and 10 g/l was obtained from 7.5% (w/v) sawdust, rice straw, and bagasse and the same substrates showed reducing sugar release of 4.2, 30, and 20 g/l respectively when treated with alkali (0.1 g/g). Combination of gamma ray with alkali treatment further increased the reducing sugar release to 10.2, 33, and 36 g/l from sawdust, rice straw, and bagasse respectively. The effects of gamma ray and alkali treatment on saccharification varied with the nature of the substrate

  1. Very high energy gamma ray astronomy from Hanle

    International Nuclear Information System (INIS)

    Chitnis, Varsha R.

    2015-01-01

    Over a past decade very high energy (VHE) gamma ray astronomy has emerged as a major astronomical discipline. In India, we have a long tradition of experiments in this field. Few years ago, multi-institutional Himalayan Gamma Ray Observatory (HiGRO) collaboration was formed to set up VHE gamma rays experiments at Hanle, a high altitude location in Himalayas. HAGAR, the first phase of this collaboration is operational since 2008. HAGAR has successfully detected VHE gamma ray emission from some of the extragalactic objects like Mrk 421, Mrk 501 as well as galactic sources including Crab nebula/pulsar. Details of HAGAR telescope system and results obtained will be discussed. HiGRO is now gearing up for the next phase, i.e. 21 m diameter MACE telescope, which is being installed at Hanle at present. Details of MACE telescope system and future plans will be discussed. (author)

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

    International Nuclear Information System (INIS)

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

    1984-01-01

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

  3. Gamma-ray spectroscopy with relativistic exotic heavy-ions

    Indian Academy of Sciences (India)

    Abstract. Feasibility of gamma-ray spectroscopy at relativistic energies with exotic heavy-ions and new generation of germanium detectors (segmented Clover) is discussed. An experiment with such detector array and radioactive is discussed.

  4. Secondary gamma-ray data for shielding calculation

    International Nuclear Information System (INIS)

    Miyasaka, Sunichi

    1979-01-01

    In deep penetration transport calculations, the integral design parameters is determined mainly by secondary particles which are produced by interactions of the primary radiation with materials. The shield thickness and the biological dose rate at a given point of a bulk shield are determined from the contribution from secondary gamma rays. The heat generation and the radiation damage in the structural and shield materials depend strongly on the secondary gamma rays. In this paper, the status of the secondary gamma ray data and its further problems are described from the viewpoint of shield design. The secondary gamma-ray data in ENDF/B-IV and POPOP4 are also discussed based on the test calculations made for several shield assemblies. (author)

  5. Public List of LAT-Detected Gamma-Ray Pulsars

    Data.gov (United States)

    National Aeronautics and Space Administration — The following is a compilation of all publicly-announced gamma-ray pulsars detected using the Fermi LAT. Each of the detections has been vetted by the LAT team,...

  6. Gamma-ray flares from the Crab nebula

    International Nuclear Information System (INIS)

    Abdo, A.A.; Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Casandjian, J.M.; Grenier, I.A.; Naumann-Godo, M.; Pierbattista, M.; Tibaldo, L.

    2011-01-01

    A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10 15 electron volts) electrons in a region smaller than 1.4 * 10 -2 parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory. (authors)

  7. Influence of gamma rays on the yield of Linum usitatissimum

    International Nuclear Information System (INIS)

    Ghouse, A.K.M.; Abidi, S.H.

    1979-01-01

    The impact of various acute doses of gamma-rays has been studied in an oil yielding Indian variety, Neelum of Linum usitatissimum. It has been found that gamma irradiation brings about an increase in the yield of the crop at lower doses upto 75 krads, while the higher ones like 125 and 150 krads reduce the yield to half. (auth.)

  8. Airborne Gamma-ray Measurements in the Chernobyl Plume

    DEFF Research Database (Denmark)

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

    1997-01-01

    On 29 April 1986, the Geological Survey of Finland (GSF) survey aircraft with a gamma ray spectrometer flew through a radioactive plume from the Chernobyl nuclear accident. The aircraft became contaminated and the gamma spectrometer measured radioactivity in the plume as well as radioactivity...

  9. Structure and content of the galaxy and galactic gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    1976-01-01

    The conference included papers on ..gamma..-ray pulsars, galactic diffuse flux and surveys, radio surveys of external galaxies, galactic distribution of pulsars, and galactic gamma emission. Galactic structure drawing on all branches of galactic astronomy is discussed. New and unpublished material is included. (JFP)

  10. Upgrade of the JET gamma-ray cameras

    International Nuclear Information System (INIS)

    Soare, S.; Curuia, M.; Anghel, M.; Constantin, M.; David, E.; Craciunescu, T.; Falie, D.; Pantea, A.; Tiseanu, I.; Kiptily, V.; Prior, P.; Edlington, T.; Griph, S.; Krivchenkov, Y.; Loughlin, M.; Popovichev, S.; Riccardo, V; Syme, B.; Thompson, V.; Lengar, I.; Murari, A.; Bonheure, G.; Le Guern, F.

    2007-01-01

    Full text: The JET gamma-ray camera diagnostics have already provided valuable information on the gamma-ray imaging of fast ion in JET plasmas. The applicability of gamma-ray imaging to high performance deuterium and deuterium-tritium JET discharges is strongly dependent on the fulfilment of rather strict requirements for the characterisation of the neutron and gamma-ray radiation fields. These requirements have to be satisfied within very stringent boundary conditions for the design, such as the requirement of minimum impact on the co-existing neutron camera diagnostics. The JET Gamma-Ray Cameras (GRC) upgrade project deals with these issues with particular emphasis on the design of appropriate neutron/gamma-ray filters ('neutron attenuators'). Several design versions have been developed and evaluated for the JET GRC neutron attenuators at the conceptual design level. The main design parameter was the neutron attenuation factor. The two design solutions, that have been finally chosen and developed at the level of scheme design, consist of: a) one quasi-crescent shaped neutron attenuator (for the horizontal camera) and b) two quasi-trapezoid shaped neutron attenuators (for the vertical one). The second design solution has different attenuation lengths: a short version, to be used together with the horizontal attenuator for deuterium discharges, and a long version to be used for high performance deuterium and DT discharges. Various neutron-attenuating materials have been considered (lithium hydride with natural isotopic composition and 6 Li enriched, light and heavy water, polyethylene). Pure light water was finally chosen as the attenuating material for the JET gamma-ray cameras. The neutron attenuators will be steered in and out of the detector line-of-sight by means of an electro-pneumatic steering and control system. The MCNP code was used for neutron and gamma ray transport in order to evaluate the effect of the neutron attenuators on the neutron field of the

  11. Journal of Astrophysics and Astronomy | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy. Pantea Davoudifar. Articles written in Journal of Astrophysics and Astronomy. Volume 32 Issue 3 September 2011 pp 359-370. Extragalactic Gamma Ray Excess from Coma Supercluster Direction · Pantea Davoudifar S. Jalil Fatemi · More Details Abstract Fulltext ...

  12. System for Gamma an X rays fluorescence spectrometric

    International Nuclear Information System (INIS)

    Alonso Abad, D.; Arista Romeu, E.; Bolanos Perez, L. and others

    1997-01-01

    A system for spectrometry of gamma or fluorescence X rays is presented. It sis composed by a Si(Li) semiconductors detector, a charge sensitive preamplifier, a high voltage power supply, a spectrometric amplifier and a monolithic 1024 channels multichannel analyzers or an IBM compatible 4096 channels add - on- card multichannel analyzer. The system can be configured as a 1024 or 4096 channels gamma or fluorescent X rays spectrometer

  13. The Advanced Gamma-ray Imaging System (AGIS): Simulation Studies

    Science.gov (United States)

    Fegan, Stephen; Buckley, J. H.; Bugaev, S.; Funk, S.; Konopelko, A.; Maier, G.; Vassiliev, V. V.; Simulation Studies Working Group; AGIS Collaboration

    2008-03-01

    The Advanced Gamma-ray Imaging System (AGIS) is a concept for the next generation instrument in ground-based very high energy gamma-ray astronomy. It has the goal of achieving significant improvement in sensitivity over current experiments. We present the results of simulation studies of various possible designs for AGIS. The primary characteristics of the array performance, collecting area, angular resolution, background rejection, and sensitivity are discussed.

  14. The Advanced Gamma-ray Imaging System (AGIS): Simulation Studies

    OpenAIRE

    Maier, G.; Collaboration, for the AGIS

    2009-01-01

    The Advanced Gamma-ray Imaging System (AGIS) is a next-generation ground-based gamma-ray observatory being planned in the U.S. The anticipated sensitivity of AGIS is about one order of magnitude better than the sensitivity of current observatories, allowing it to measure gammaray emmission from a large number of Galactic and extra-galactic sources. We present here results of simulation studies of various possible designs for AGIS. The primary characteristics of the array performance - collect...

  15. Significant gamma-ray lines from dark matter annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Duerr, Michael [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Fileviez Perez, Pavel; Smirnov, Juri [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany)

    2016-07-01

    Gamma-ray lines from dark matter annihilation are commonly seen as a ''smoking gun'' for the particle nature of dark matter. However, in many dark matter models the continuum background from tree-level annihilations makes such a line invisible. I present two simple extensions of the Standard Model where the continuum contributions are suppressed and the gamma-ray lines are easily visible over the continuum background.

  16. Extragalactic Gamma Ray Excess from Coma Supercluster Direction

    Indian Academy of Sciences (India)

    More precise analysis of EGRET data however, makes it possible to estimate the diffuse gamma ray in Coma supercluster (i.e., Coma\\A1367 supercluster) direction with a value of ( > 30MeV) ≃ 1.9 × 10-6 cm-2 s-1, which is considered to be an upper limit for the diffuse gamma ray due to Coma supercluster. The related ...

  17. Population Studies of Radio and Gamma-Ray Pulsars

    Science.gov (United States)

    Harding, Alice K; Gonthier, Peter; Coltisor, Stefan

    2004-01-01

    Rotation-powered pulsars are one of the most promising candidates for at least some of the 40-50 EGRET unidentified gamma-ray sources that lie near the Galactic plane. Since the end of the EGRO mission, the more sensitive Parkes Multibeam radio survey has detected mere than two dozen new radio pulsars in or near unidentified EGRET sources, many of which are young and energetic. These results raise an important question about the nature of radio quiescence in gamma-ray pulsars: is the non-detection of radio emission a matter of beaming or of sensitivity? The answer is very dependent on the geometry of the radio and gamma-ray beams. We present results of a population synthesis of pulsars in the Galaxy, including for the first time the full geometry of the radio and gamma-ray beams. We use a recent empirically derived model of the radio emission and luminosity, and a gamma-ray emission geometry and luminosity derived theoretically from pair cascades in the polar slot gap. The simulation includes characteristics of eight radio surveys of the Princeton catalog plus the Parkes MB survey. Our results indicate that EGRET was capable of detecting several dozen pulsars as point sources, with the ratio of radio-loud to radio-quiet gamma-ray pulsars increasing significantly to about ten to one when the Parkes Survey is included. Polar cap models thus predict that many of the unidentified EGRET sources could be radio-loud gamma- ray pulsars, previously undetected as radio pulsars due to distance, large dispersion and lack of sensitivity. If true, this would make gamma-ray telescopes a potentially more sensitive tool for detecting distant young neutron stars in the Galactic plane.

  18. Cosmic very high-energy {gamma}-rays

    Energy Technology Data Exchange (ETDEWEB)

    Plaga, R. [Max-Planck-Institut fur Physik, Muenchen (Germany)

    1998-12-31

    The article gives a brief overview, aimed at nonspecialists, about the goals and selected recent results of the detection of very-high energy {gamma}-rays (energies above 100 GeV) with ground based detectors. The stress is on the physics questions, specially the origin of Galactic Cosmic Rays and the emission of TeV {gamma}-radiation from active galaxies. Moreover some particle-physics questions which are addressed in this area are discussed.

  19. GLAST, the Gamma-ray Large Area Space Telescope

    CERN Document Server

    De Angelis, A

    2001-01-01

    GLAST, a detector for cosmic gamma rays in the range from 20 MeV to 300 GeV, will be launched in space in 2005. Breakthroughs are expected in particular in the study of particle acceleration mechanisms in space and of gamma ray bursts, and maybe on the search for cold dark matter; but of course the most exciting discoveries could come from the unexpected.

  20. Measuring The Variability Of Gamma-Ray Sources With AGILE

    International Nuclear Information System (INIS)

    Chen, Andrew W.; Vercellone, Stefano; Pellizzoni, Alberto; Tavani, Marco

    2005-01-01

    Variability in the gamma-ray flux above 100 MeV at various time scales is one of the primary characteristics of the sources detected by EGRET, both allowing the identification of individual sources and constraining the unidentified source classes. We present a detailed simulation of the capacity of AGILE to characterize the variability of gamma-ray sources, discussing the implications for source population studies

  1. The MAGIC gamma-ray telescope: status and first results

    International Nuclear Information System (INIS)

    Fernandez, Enrique

    2006-01-01

    MAGIC, a 17 m diameter Cherenkov telescope for gamma ray astronomy, has recently been commissioned at the Roque de los Muchachos site in the Island of La Palma, of the Canary Islands. The telescope was proposed in 1998 with the goal of lowering the threshold of observation of gamma rays by ground detectors to 20-30 GeV energies. This paper describes its main design features, its physics objectives and its first operations

  2. Catalogue of gamma rays from radionuclides ordered by nuclide

    International Nuclear Information System (INIS)

    Ekstroem, L.P.; Andersson, P.; Sheppard, H.M.

    1984-01-01

    A catalogue of about 28500 gamma-ray energies from 2338 radionuclides is presented. The nuclides are listed in order of increasing (A,Z) of the daughter nuclide. In addition the gamma-ray intensity per 100 decays of the parent (if known) and the decay half-life are given. All data are from a computer processing of a recent ENSDF (Evaluated Nuclear Structure Data File) file. (authors)

  3. Terrestrial gamma ray flash production by lightning current pulses

    OpenAIRE

    İnan, Umran Savaş; Carlson, B. E.; Lehtinen, N. G.

    2017-01-01

    Terrestrial gamma ray flashes (TGFs) are brief bursts of gamma rays observed by satellites, typically in coincidence with detectable lightning. We incorporate TGF observations and the key physics behind current TGF production theories with lightning physics to produce constraints on TGF production mechanisms. The combined constraints naturally suggest a mechanism for TGF production by current pulses in lightning leader channels. The mechanism involves local field enhancements due to charge re...

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

    Science.gov (United States)

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

    1996-01-01

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

  5. Technical Aspect on Procedure of Gamma-Ray Pipeline Inspection

    International Nuclear Information System (INIS)

    Rasif Mohd Zain; Ainul Mardhiah Terry; Norman Shah Dahing

    2015-01-01

    The main problems happen in industrial pipelines are deposit build-up, blockage, corrosion and erosion. These effects will give a constraint in transporting refined products to process or production points and cause a major problem in production. One of the techniques to inspect the problem is using gamma-ray pipe scans. The principle of the technique is gamma-ray absorption technique. In this paper describes on the technical aspect to perform the pipe inspection in laboratory work. (author)

  6. Gamma-ray astronomy in the medium energy (10-50 MeV) range

    International Nuclear Information System (INIS)

    Kniffen, D.A.; Bertsch, D.L.; Palmeira, R.A.R.; Rao, K.R.

    1977-01-01

    Gamma-ray astronomy in the medium energy (10-50 MeV) range can provide unique information with which to study many astrophysical problems. Observations in the 10-50 MeV range provide the cleanest window with which to view the isotropic diffuse component of the radiation and to study the possible cosmological implications of the spectrum. For the study of compact sources, this is the important region between the X-ray sky and the vastly different γ-ray sky seen by SAS-2 and COS-B. To understand the implications of medium energy γ-ray astronomy to the study of the galactic diffuse γ-radiation, the model developed to explain the high energy γ-ray observations of SAS-2 is extended to the medium energy range. This work illustrates the importance of medium energy γ-ray astronomy for studying the electromagnetic component of the galactic cosmic rays. To observe the medium energy component of the intense galactic center γ-ray emission, two balloon flights of a medium energy γ-ray spark chamber telescope were flown in Brazil in 1975. These results indicate the emission is higher than previously thought and above the predictions of the theoretical model

  7. Gamma Ray Burst Discoveries with the Swift Mission

    Science.gov (United States)

    Gehrels, Neil; Tueller, Jack

    2007-01-01

    There is a great synergy between the Swift and INTEGRAL missions. Swift provides wide-field hard x-ray monitoring and sensitive x-ray and UV/optical observations. INTEGRAL provides optical through gamma-ray coverage with emphasis on hard xray imaging and gamma-ray spectroscopy. For hard x-ray survey studies, the BAT and IBIS instruments are complementary with BAT covering the full sky every day and IBIS scanning the galactic plane. For GRBs, Swift follows up bursts detected by INTEGRAL. X-ray and optical observations give arcsecond positions and afterglow lightcurves. For IGR sources, X-ray observations identify counterparts. The joint BAT and IBIS survey data are giving the most complete picture of the hard x-ray sky ever obtained. This talk will review Swift capabilities and discuss joint observations that are taking place and planned

  8. The Fermi Gamma-ray Burst Monitor (GBM) Terrestrial Gamma-ray Flash (TGF) Catalog

    Science.gov (United States)

    Briggs, M. S.; Roberts, O.; Fitzpatrick, G.; Stanbro, M.; Cramer, E.; Mailyan, B. G.; McBreen, S.; Connaughton, V.; Grove, J. E.; Chekhtman, A.; Holzworth, R.

    2017-12-01

    The revised Second Fermi GBM TGF catalog includes data on 4144 TGFs detected by the Fermi Gamma-ray Burst Monitor through 2016 July 31. The catalog includes 686 bright TGFs there were detected in orbit and 4135 TGFs that were discovered by ground analysis of GBM data (the two samples overlap). Thirty of the events may have been detected as electrons and positrons rather than gamma-rays: Terrestrial Electron Beams (TEBs). We also provide results from correlating the GBM TGFs with VLF radio detections of the World Wide Lightning Location Network (WWLLN). TGFs with WWLLN associations have their localization uncertainties improved from 800 to 10 km, making it possible to identify specific thunderstorms responsible for the TGFs and opening up new types of scientific investigations. There are 1544 TGFs with WWLLN associations; maps are provided for these and the other TGFs of the catalog. The data tables of the catalog are available for use by the scientific community at the Fermi Science Support Center, at https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/tgf/.

  9. LOCALIZATION OF GAMMA-RAY BURSTS USING THE FERMI GAMMA-RAY BURST MONITOR

    Energy Technology Data Exchange (ETDEWEB)

    Connaughton, V.; Briggs, M. S.; Burgess, J. M. [CSPAR and Physics Department, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Goldstein, A.; Wilson-Hodge, C. A. [Astrophysics Office, ZP12, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Meegan, C. A.; Jenke, P.; Pelassa, V.; Xiong, S.; Bhat, P. N. [CSPAR, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Paciesas, W. S. [Universities Space Research Association, Huntsville, AL (United States); Preece, R. D. [Department of Space Science, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Gibby, M. H. [Jacobs Technology, Inc., Huntsville, AL (United States); Greiner, J.; Yu, H.-F. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Gruber, D. [Planetarium Südtirol, Gummer 5, I-39053 Karneid (Italy); Kippen, R. M. [Los Alamos National Laboratory, NM 87545 (United States); Byrne, D.; Fitzpatrick, G.; Foley, S., E-mail: valerie@nasa.gov [School of Physics, University College Dublin, Belfield, Stillorgan Road, Dublin 4 (Ireland); and others

    2015-02-01

    The Fermi Gamma-ray Burst Monitor (GBM) has detected over 1400 gamma-ray bursts (GRBs) since it began science operations in 2008 July. We use a subset of over 300 GRBs localized by instruments such as Swift, the Fermi Large Area Telescope, INTEGRAL, and MAXI, or through triangulations from the InterPlanetary Network, to analyze the accuracy of GBM GRB localizations. We find that the reported statistical uncertainties on GBM localizations, which can be as small as 1°, underestimate the distance of the GBM positions to the true GRB locations and we attribute this to systematic uncertainties. The distribution of systematic uncertainties is well represented (68% confidence level) by a 3.°7 Gaussian with a non-Gaussian tail that contains about 10% of GBM-detected GRBs and extends to approximately 14°. A more complex model suggests that there is a dependence of the systematic uncertainty on the position of the GRB in spacecraft coordinates, with GRBs in the quadrants on the Y axis better localized than those on the X axis.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

    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 Polycinsetique a Trois dimensions, CEA Rapport, Commissariat a l'Energie Atomique.

  11. Self-powered neutron and gamma-ray flux detector

    International Nuclear Information System (INIS)

    Allan, C.J.; Shields, R.B.; Lynch, G.F.; Cuttler, J.M.

    1980-01-01

    A new type of self-powered neutron detector was developed which is sensitive to both the neutron and gamma-ray fluxes. The emitter comprises two parts. The central emitter core is made of materials that generate high-energy electrons on exposure to neutrons. The outer layer acts as a gamma-ray/electron converter, and since it has a higher atomic number and higher back-scattering coefficient than the collector, increases the net outflow or emmission of electrons. The collector, which is around the emitter outer layer, is insulated from the outer layer electrically with dielectric insulation formed from compressed metal-oxide powder. The fraction of electrons given off by the emitter that is reflected back by the collector is less than the fraction of electrons emitted by the collector that is reflected back by the emitter. The thickness of the outer layer needed to achieve this result is very small. A detector of this design responds to external reactor gamma-rays as well as to neutron capture gamma-rays from the collector. The emitter core is either nickel, iron or titanium, or alloys based on these metals. The outer layer is made of platinum, tantalum, osmium, molybdenum or cerium. The detector is particularly useful for monitoring neutron and gamma ray flux intensities in nuclear reactor cores in which the neutron and gamma ray flux intensities are closely proportional, are unltimately related to the fission rate, and are used as measurements of nuclear reactor power. (DN)

  12. Gamma-ray emission profile measurements during JET ICRH discharges

    Energy Technology Data Exchange (ETDEWEB)

    Howarth, P.J.A. [Birmingham Univ. (United Kingdom); Adams, J.M.; Bond, D.S.; Watkins, N. [AEA Technology, Harwell (United Kingdom); Jarvis, O.N.; Marcus, F.B.; Sadler, G.; Belle, P. van [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1994-12-31

    Ion Cyclotron Resonant Heating (ICRH) that is tuned to minority fuel ions can induce an energy diffusion of the heated species and create high energy tail temperatures of {approx} 1 MeV. The most energetic of these accelerated minority ions can undergo nuclear reactions with impurity Be and C that produces {gamma}-ray emission from the decay of the excited product nuclei. This RF-induced {gamma}-ray emission has been recorded using the JET neutron emission profile diagnostic which is capable of distinguishing neutrons and {gamma}-rays. Appropriate data processing has enabled the RF-induced {gamma}-ray emission signals to be isolated from the {gamma}-ray emission signals associated with neutron interactions in the material surrounding the profile monitor. The 2-d {gamma}-ray emission profiles show that virtually all the radiation originates from the low field side of the RF resonance layer, as expected from RF-induced pitch angle diffusion. The emission profiles indicate the presence of a small population of resonant {sup 3}He ions that possess orbits lying near the passing-trapped boundary. (author) 6 refs., 4 figs.

  13. NEW FERMI-LAT EVENT RECONSTRUCTION REVEALS MORE HIGH-ENERGY GAMMA RAYS FROM GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Atwood, W. B. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Baldini, L. [Universita di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bregeon, J.; Pesce-Rollins, M.; Sgro, C.; Tinivella, M. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bruel, P. [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France); Chekhtman, A. [Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030 (United States); Cohen-Tanugi, J. [Laboratoire Univers et Particules de Montpellier, Universite Montpellier 2, CNRS/IN2P3, F-34095 Montpellier (France); Drlica-Wagner, A.; Omodei, N.; Rochester, L. S.; Usher, T. L. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Granot, J. [Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Ra' anana 43537 (Israel); Longo, F. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Razzaque, S. [Department of Physics, University of Johannesburg, Auckland Park 2006 (South Africa); Zimmer, S., E-mail: melissa.pesce.rollins@pi.infn.it, E-mail: nicola.omodei@stanford.edu, E-mail: granot@openu.ac.il [Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm (Sweden)

    2013-09-01

    Based on the experience gained during the four and a half years of the mission, the Fermi-LAT Collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet finalized, we can test the improvements in the new event reconstruction with the special case of the prompt phase of bright gamma-ray bursts (GRBs), where the signal-to-noise ratio is large enough that loose selection cuts are sufficient to identify gamma rays associated with the source. Using the new event reconstruction, we have re-analyzed 10 GRBs previously detected by the Large Area Telescope (LAT) for which an X-ray/optical follow-up was possible and found four new gamma rays with energies greater than 10 GeV in addition to the seven previously known. Among these four is a 27.4 GeV gamma ray from GRB 080916C, which has a redshift of 4.35, thus making it the gamma ray with the highest intrinsic energy ({approx}147 GeV) detected from a GRB. We present here the salient aspects of the new event reconstruction and discuss the scientific implications of these new high-energy gamma rays, such as constraining extragalactic background light models, Lorentz invariance violation tests, the prompt emission mechanism, and the bulk Lorentz factor of the emitting region.

  14. A NOVEL APPROACH IN THE WEAKLY INTERACTING MASSIVE PARTICLE QUEST: CROSS-CORRELATION OF GAMMA-RAY ANISOTROPIES AND COSMIC SHEAR

    International Nuclear Information System (INIS)

    Camera, Stefano; Fornasa, Mattia; Fornengo, Nicolao; Regis, Marco

    2013-01-01

    Both cosmic shear and cosmological gamma-ray emission stem from the presence of dark matter (DM) in the universe: DM structures are responsible for the bending of light in the weak-lensing regime and those same objects can emit gamma rays, either because they host astrophysical sources (active galactic nuclei or star-forming galaxies) or directly by DM annihilations (or decays, depending on the properties of the DM particle). Such gamma rays should therefore exhibit strong correlation with the cosmic shear signal. In this Letter, we compute the cross-correlation angular power spectrum of cosmic shear and gamma rays produced by the annihilation/decay of weakly interacting massive particle DM, as well as by astrophysical sources. We show that this observable provides novel information on the composition of the extragalactic gamma-ray background (EGB), since the amplitude and shape of the cross-correlation signal strongly depend on which class of sources is responsible for the gamma-ray emission. If the DM contribution to the EGB is significant (at least in a definite energy range), although compatible with current observational bounds, its strong correlation with the cosmic shear makes such signal potentially detectable by combining Fermi Large Area Telescope data with forthcoming galaxy surveys, like the Dark Energy Survey and Euclid. At the same time, the same signal would demonstrate that the weak-lensing observables are indeed due to particle DM matter and not to possible modifications of general relativity.

  15. A Novel Approach in the Weakly Interacting Massive Particle Quest: Cross-correlation of Gamma-Ray Anisotropies and Cosmic Shear

    Science.gov (United States)

    Camera, Stefano; Fornasa, Mattia; Fornengo, Nicolao; Regis, Marco

    2013-07-01

    Both cosmic shear and cosmological gamma-ray emission stem from the presence of dark matter (DM) in the universe: DM structures are responsible for the bending of light in the weak-lensing regime and those same objects can emit gamma rays, either because they host astrophysical sources (active galactic nuclei or star-forming galaxies) or directly by DM annihilations (or decays, depending on the properties of the DM particle). Such gamma rays should therefore exhibit strong correlation with the cosmic shear signal. In this Letter, we compute the cross-correlation angular power spectrum of cosmic shear and gamma rays produced by the annihilation/decay of weakly interacting massive particle DM, as well as by astrophysical sources. We show that this observable provides novel information on the composition of the extragalactic gamma-ray background (EGB), since the amplitude and shape of the cross-correlation signal strongly depend on which class of sources is responsible for the gamma-ray emission. If the DM contribution to the EGB is significant (at least in a definite energy range), although compatible with current observational bounds, its strong correlation with the cosmic shear makes such signal potentially detectable by combining Fermi Large Area Telescope data with forthcoming galaxy surveys, like the Dark Energy Survey and Euclid. At the same time, the same signal would demonstrate that the weak-lensing observables are indeed due to particle DM matter and not to possible modifications of general relativity.

  16. A NOVEL APPROACH IN THE WEAKLY INTERACTING MASSIVE PARTICLE QUEST: CROSS-CORRELATION OF GAMMA-RAY ANISOTROPIES AND COSMIC SHEAR

    Energy Technology Data Exchange (ETDEWEB)

    Camera, Stefano [CENTRA, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Lisboa (Portugal); Fornasa, Mattia [School of Physics and Astronomy, University of Nottingham, Nottingham (United Kingdom); Fornengo, Nicolao; Regis, Marco [Dipartimento di Fisica, Universita di Torino and INFN, Torino (Italy)

    2013-07-01

    Both cosmic shear and cosmological gamma-ray emission stem from the presence of dark matter (DM) in the universe: DM structures are responsible for the bending of light in the weak-lensing regime and those same objects can emit gamma rays, either because they host astrophysical sources (active galactic nuclei or star-forming galaxies) or directly by DM annihilations (or decays, depending on the properties of the DM particle). Such gamma rays should therefore exhibit strong correlation with the cosmic shear signal. In this Letter, we compute the cross-correlation angular power spectrum of cosmic shear and gamma rays produced by the annihilation/decay of weakly interacting massive particle DM, as well as by astrophysical sources. We show that this observable provides novel information on the composition of the extragalactic gamma-ray background (EGB), since the amplitude and shape of the cross-correlation signal strongly depend on which class of sources is responsible for the gamma-ray emission. If the DM contribution to the EGB is significant (at least in a definite energy range), although compatible with current observational bounds, its strong correlation with the cosmic shear makes such signal potentially detectable by combining Fermi Large Area Telescope data with forthcoming galaxy surveys, like the Dark Energy Survey and Euclid. At the same time, the same signal would demonstrate that the weak-lensing observables are indeed due to particle DM matter and not to possible modifications of general relativity.

  17. THERMAL X-RAY EMISSION FROM THE SHOCKED STELLAR WIND OF PULSAR GAMMA-RAY BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Zabalza, V.; Paredes, J. M. [Departament d' Astronomia i Meteorologia, Institut de Ciencies del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E08028 Barcelona (Spain); Bosch-Ramon, V., E-mail: vzabalza@am.ub.es [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland)

    2011-12-10

    Gamma-ray-loud X-ray binaries are binary systems that show non-thermal broadband emission from radio to gamma rays. If the system comprises a massive star and a young non-accreting pulsar, their winds will collide producing broadband non-thermal emission, most likely originated in the shocked pulsar wind. Thermal X-ray emission is expected from the shocked stellar wind, but until now it has neither been detected nor studied in the context of gamma-ray binaries. We present a semi-analytic model of the thermal X-ray emission from the shocked stellar wind in pulsar gamma-ray binaries, and find that the thermal X-ray emission increases monotonically with the pulsar spin-down luminosity, reaching luminosities of the order of 10{sup 33} erg s{sup -1}. The lack of thermal features in the X-ray spectrum of gamma-ray binaries can then be used to constrain the properties of the pulsar and stellar winds. By fitting the observed X-ray spectra of gamma-ray binaries with a source model composed of an absorbed non-thermal power law and the computed thermal X-ray emission, we are able to derive upper limits on the spin-down luminosity of the putative pulsar. We applied this method to LS 5039, the only gamma-ray binary with a radial, powerful wind, and obtain an upper limit on the pulsar spin-down luminosity of {approx}6 Multiplication-Sign 10{sup 36} erg s{sup -1}. Given the energetic constraints from its high-energy gamma-ray emission, a non-thermal to spin-down luminosity ratio very close to unity may be required.

  18. Detection of pseudo gamma-ray bursts of long duration

    International Nuclear Information System (INIS)

    Frontera, F.; Fuligni, F.; Morelli, E.; Pizzichini, G.; Ventura, G.

    1981-01-01

    It is known that the counting rate of both Na I and Cs I hard X-ray detectors can have intense enhancements of brief (< 1 s) duration, which appear like very short cosmic gamma-ray bursts but probably are due to phosphorescence in the detector itself. Unfortunately, this problem is not limited to short bursts. We present here three much longer (up to 80 s) pseudo-gamma-ray bursts observed during a transatlantic balloon flight. We conclude that detections of gamma-ray bursts (and probably also of hard X-ray source flares) based only on a rate increase by a single scintillator should always be confirmed by at least one other instrument. (orig.)

  19. In situ measurements of dose rates from terrestrial gamma rays

    International Nuclear Information System (INIS)

    Horng, M.C.; Jiang, S.H.

    2002-01-01

    A portable, high purity germanium (HPGe) detector was employed for the performance of in situ measurements of radionuclide activity concentrations in the ground in Taiwan, at altitudes ranging from sea level to 3900 m. The absolute peak efficiency of the HPGe detector for a gamma-ray source uniformly distributed in the semi-infinite ground was determined using a semi-empirical method. The gamma-ray dose rates from terrestrial radionuclides were calculated from the measured activity levels using recently published dose rate conversion factors. The absorbed dose rate in air due to cosmic rays was derived by subtracting the terrestrial gamma-ray dose rate from the overall absorbed dose rate in air measured using a high-pressure ionization chamber. The cosmic-ray dose rate calculated as a function of altitude, was found to be in good agreement with the data reported by UNSCEAR. (orig.)

  20. A new type gamma-ray spectrum monitoring system

    CERN Document Server

    Cheng Bo; Zhou Jian Bin; Zhang Zhi Ming; Tong Yun Fu

    2002-01-01

    This new radiation monitoring system can be used to monitor the radiation of building materials and the radiation of atmosphere, to explore and evaluate rock for building in the field, and this system can be used to monitor the gamma irradiation near the nuclear establishments in the average situation and in the serious situation of the radiation incident have happened. The control core of this monitoring system is SCM-AT89C52, and gamma-ray sensing head consists of scintillator phi 50 mm x 50 mm NaI(Tl) and PMT GDB44. This system can be used to measure the whole gamma-ray spectrum of 256 channels

  1. 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.

  2. Recent results in nuclear astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Coc, Alain; Kiener, Juergen [CNRS/IN2P3 et Universite Paris Sud 11, UMR 8609, Centre de Sciences Nucleaires et de Sciences de la Matiere (CSNSM), Orsay Campus (France); Hammache, Fairouz [CNRS/IN2P3 et Universite Paris Sud 11, UMR 8608, Institut de Physique Nucleaire d' Orsay (IPNO), Orsay Campus (France)

    2015-03-01

    In this review, we emphasize the interplay between astrophysical observations, modeling, and nuclear physics laboratory experiments. Several important nuclear cross sections for astrophysics have long been identified, e.g., {sup 12}C(α, γ){sup 16}O for stellar evolution, or {sup 13}C(α, n){sup 16}O and {sup 22}Ne(α, n){sup 25}Mg as neutron sources for the s-process. More recently, observations of lithium abundances in the oldest stars, or of nuclear gamma-ray lines from space, have required new laboratory experiments. New evaluation of thermonuclear reaction rates now includes the associated rate uncertainties that are used in astrophysical models to i) estimate final uncertainties on nucleosynthesis yields and ii) identify those reactions that require further experimental investigation. Sometimes direct cross section measurements are possible, but more generally the use of indirect methods is compulsory in view of the very low cross sections. Non-thermal processes are often overlooked but are also important for nuclear astrophysics, e.g., in gamma-ray emission from solar flares or in the interaction of cosmic rays with matter, and also motivate laboratory experiments. Finally, we show that beyond the historical motivations of nuclear astrophysics, understanding i) the energy sources that drive stellar evolution and ii) the origin of the elements can also be used to give new insights into physics beyond the standard model. (orig.)

  3. Recent results in nuclear astrophysics

    International Nuclear Information System (INIS)

    Coc, Alain; Kiener, Juergen; Hammache, Fairouz

    2015-01-01

    In this review, we emphasize the interplay between astrophysical observations, modeling, and nuclear physics laboratory experiments. Several important nuclear cross sections for astrophysics have long been identified, e.g., 12 C(α, γ) 16 O for stellar evolution, or 13 C(α, n) 16 O and 22 Ne(α, n) 25 Mg as neutron sources for the s-process. More recently, observations of lithium abundances in the oldest stars, or of nuclear gamma-ray lines from space, have required new laboratory experiments. New evaluation of thermonuclear reaction rates now includes the associated rate uncertainties that are used in astrophysical models to i) estimate final uncertainties on nucleosynthesis yields and ii) identify those reactions that require further experimental investigation. Sometimes direct cross section measurements are possible, but more generally the use of indirect methods is compulsory in view of the very low cross sections. Non-thermal processes are often overlooked but are also important for nuclear astrophysics, e.g., in gamma-ray emission from solar flares or in the interaction of cosmic rays with matter, and also motivate laboratory experiments. Finally, we show that beyond the historical motivations of nuclear astrophysics, understanding i) the energy sources that drive stellar evolution and ii) the origin of the elements can also be used to give new insights into physics beyond the standard model. (orig.)

  4. Gamma-ray and neutrino diffuse emissions of the Galaxy above the TeV

    CERN Document Server

    Gaggero, Daniele; Marinelli, Antonio; Urbano, Alfredo; Valli, Mauro

    2016-01-01

    As recently shown, Fermi-LAT measurements of the diffuse gamma-ray emission from the Galaxy favor the presence of a smooth softening in the primary cosmic-ray spectrum with increasing Galactocentric distance. This result can be interpreted in terms of a spatial-dependent rigidity scaling of the diffusion coefficient. The DRAGON code was used to build a model based on such feature. That scenario correctly reproduces the latest Fermi-LAT results as well as local cosmic-ray measurements from PAMELA, AMS-02 and CREAM. Here we show that the model, if extrapolated at larger energies, grasps both the gamma-ray flux measured by MILAGRO at 15 TeV and the H.E.S.S. data from the Galactic ridge, assuming that the cosmic-ray spectral hardening found by those experiments at about 250 GeV/n is present in the whole inner Galactic plane region. Moreover, we show as that model also predicts a neutrino emission which may account for a significant fraction, as well as for the correct spectral shape, of the astrophysical flux mea...

  5. Gamma-ray shielding design and performance test of WASTEF

    International Nuclear Information System (INIS)

    Matsumoto, Seiichiro; Aoyama, Saburo; Tashiro, Shingo; Nagai, Shiro

    1984-06-01

    The Waste Safety Testing Facility (WASTEF) was planned in 1978 to test the safety performance of HLW vitrified forms under the simulated conditions of long term storage and disposal, and completed in August 1981. The designed feature of the facility is to treat the vitrified forms contain actual high-level wastes of 5 x 10 4 Ci in maximum with 5 units of concrete shilded hot cells (3 units : Bate-Gamma cells, 2 units : Alpha-Gamma cells) and one units of Alpha-Gamma lead shielded cell, and to store radioactivity of 10 6 Ci in maximum. The safety performance of this facility is fundamentally maintained with confinement of radioactivity and shielding of the radiation. This report describes the method of gamma-ray shielding design, evaluation of the shielding test performed by using sealded gamma-ray sources(Co-60). (author)

  6. Anisotropy of the cosmic gamma-ray background from dark matter annihilation

    International Nuclear Information System (INIS)

    Ando, Shin'ichiro; Komatsu, Eiichiro

    2006-01-01

    High-energy photons from pair annihilation of dark matter particles contribute to the cosmic gamma-ray background (CGB) observed in a wide energy range. Since dark matter particles are weakly interacting, annihilation can happen only in high density regions such as dark matter halos. The precise shape of the energy spectrum of CGB depends on the nature of dark matter particles--their mass and annihilation cross section, as well as the cosmological evolution of dark matter halos. In order to discriminate between the signals from dark matter annihilation and other astrophysical sources, however, the information from the energy spectrum of CGB may not be sufficient. We show that dark matter annihilation not only contributes to the mean CGB intensity, but also produces a characteristic anisotropy, which provides a powerful tool for testing the origins of the observed CGB. We develop the formalism based on a halo model approach to analytically calculate the three-dimensional power spectrum of dark matter clumping, which determines the power spectrum of annihilation signals. We show that the expected sensitivity of future gamma-ray detectors such as the Gamma Ray Large Area Space Telescope (GLAST) should allow us to measure the angular power spectrum of CGB anisotropy, if dark matter particles are supersymmetric neutralinos and they account for most of the observed mean intensity of CGB in GeV region. On the other hand, if dark matter has a relatively small mass, on the order of 20 MeV, and accounts for most of the CGB in MeV region, then the future Advanced Compton Telescope (ACT) should be able to measure the angular power spectrum in MeV region. As the intensity of photons from annihilation is proportional to the density squared, we show that the predicted shape of the angular power spectrum of gamma rays from dark matter annihilation is different from that due to other astrophysical sources such as blazars and supernovae, whose intensity is linearly proportional to

  7. Experimental techniques for the detection of the high energy gamma rays of cosmic origin

    International Nuclear Information System (INIS)

    Dumitrescu, Gh.; Angelescu, T.; Radu, A.A.

    2002-01-01

    The observation of high energy gamma rays of cosmic origin in the early 90 by Volcano Ranch experiment opened a new direction of study in astrophysics. The very high energy and the very low flux of these gamma rays, posed numerous detection problems which in turn were the object of a very intense research activity. The present article tries to review the detection techniques for the high energy gamma rays of cosmic origin. In the 'Introduction' we summarize the specific problems involved in the detection of this type of radiation. 'Chapter 1' presents the classic technique based on the use of scintillation detectors. 'Chapter 2' includes the imaging atmospheric Cherenkov technique (IACT) and the sampling wavefront technique. 'Chapter 3' is dedicated to the detection of the atmospheric nitrogen. 'Chapter 4' describes issues related to the calibration of the detectors, the cross checking of the experimental data, the use of the Monte Carlo simulations and the use of the density observed at a distance of 600 m S(600), in order to estimate the primary energy. The characteristics of some future developments of the above presented techniques are included in the last chapter. (authors)

  8. Population synthesis of radio and gamma-ray millisecond pulsars using Markov Chain Monte Carlo techniques

    Science.gov (United States)

    Gonthier, Peter L.; Koh, Yew-Meng; Kust Harding, Alice

    2016-04-01

    We present preliminary results of a new population synthesis of millisecond pulsars (MSP) from the Galactic disk using Markov Chain Monte Carlo techniques to better understand the model parameter space. We include empirical radio and gamma-ray luminosity models that are dependent on the pulsar period and period derivative with freely varying exponents. The magnitudes of the model luminosities are adjusted to reproduce the number of MSPs detected by a group of thirteen radio surveys as well as the MSP birth rate in the Galaxy and the number of MSPs detected by Fermi. We explore various high-energy emission geometries like the slot gap, outer gap, two pole caustic and pair starved polar cap models. The parameters associated with the birth distributions for the mass accretion rate, magnetic field, and period distributions are well constrained. With the set of four free parameters, we employ Markov Chain Monte Carlo simulations to explore the model parameter space. We present preliminary comparisons of the simulated and detected distributions of radio and gamma-ray pulsar characteristics. We estimate the contribution of MSPs to the diffuse gamma-ray background with a special focus on the Galactic Center.We express our gratitude for the generous support of the National Science Foundation (RUI: AST-1009731), Fermi Guest Investigator Program and the NASA Astrophysics Theory and Fundamental Program (NNX09AQ71G).

  9. Disrupted globular clusters and the gamma-ray excess in the Galactic Centre

    Science.gov (United States)

    Fragione, Giacomo; Antonini, Fabio; Gnedin, Oleg Y.

    2018-04-01

    The Fermi Large Area Telescope has provided the most detailed view towards the Galactic Centre (GC) in high-energy gamma-rays. Besides the interstellar emission and point source contributions, the data suggest a residual diffuse gamma-ray excess. The similarity of its spatial distribution with the expected profile of dark matter has led to claims that this may be evidence for dark matter particle annihilation. Here, we investigate an alternative explanation that the signal originates from millisecond pulsars (MSPs) formed in dense globular clusters and deposited at the GC as a consequence of cluster inspiral and tidal disruption. We use a semi-analytical model to calculate the formation, migration, and disruption of globular clusters in the Galaxy. Our model reproduces the mass of the nuclear star cluster and the present-day radial and mass distribution of globular clusters. For the first time, we calculate the evolution of MSPs from disrupted globular clusters throughout the age of the Galaxy and consistently include the effect of the MSP spin-down due to magnetic-dipole braking. The final gamma-ray amplitude and spatial distribution are in good agreement with the Fermi observations and provide a natural astrophysical explanation for the GC excess.

  10. Gamma Ray Large Area Space Telescope (GLAST) Balloon Flight Engineering Model: Overview

    Science.gov (United States)

    Thompson, D. J.; Godfrey, G.; Williams, S. M.; Grove, J. E.; Mizuno, T.; Sadrozinski, H. F.-W.; Kamae, T.; Ampe, J.; Briber, Stuart; Dann, James; hide

    2001-01-01

    The Gamma Ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) is a pair-production high-energy (greater than 20 MeV) gamma-ray telescope being built by an international partnership of astrophysicists and particle physicists for a satellite launch in 2006, designed to study a wide variety of high-energy astrophysical phenomena. As part of the development effort, the collaboration has built a Balloon Flight Engineering Model (BFEM) for flight on a high-altitude scientific balloon. The BFEM is approximately the size of one of the 16 GLAST-LAT towers and contains all the components of the full instrument: plastic scintillator anticoincidence system (ACD), high-Z foil/Si strip pair-conversion tracker (TKR), CsI hodoscopic calorimeter (CAL), triggering and data acquisition electronics (DAQ), commanding system, power distribution, telemetry, real-time data display, and ground data processing system. The principal goal of the balloon flight was to demonstrate the performance of this instrument configuration under conditions similar to those expected in orbit. Results from a balloon flight from Palestine, Texas, on August 4, 2001, show that the BFEM successfully obtained gamma-ray data in this high-background environment.

  11. Spectroscopic CZT detectors development for x- and gamma-ray imaging instruments

    Science.gov (United States)

    Quadrini, Egidio M.; Uslenghi, Michela; Alderighi, Monica; Casini, Fabio; D'Angelo, Sergio; Fiorini, Mauro; La Palombara, Nicola; Mancini, Marcello; Monti, Serena; Bazzano, Angela; Di Cosimo, Sergio; Frutti, Massimo; Natalucci, Lorenzo; Ubertini, Pietro; Guadalupi, Giuseppe M.; Sassi, Matteo; Negri, Barbara

    2007-09-01

    In the context of R&D studies financed by the Italian Space Agency (ASI), a feasibility study to evaluate the Italian Industry interest in medium-large scale production of enhanced CZT detectors has been performed by an Italian Consortium. The R&D investment aims at providing in-house source of high quality solid state spectrometers for Space Astrophysics applications. As a possible spin-off industrial applications to Gamma-ray devices for non-destructive inspections in medical, commercial and security fields have been considered by ASI. The short term programme mainly consists of developing proprietary procedures for 2-3" CZT crystals growth, including bonding and contact philosophy, and a newly designed low-power electronics readout chain. The prototype design and breadboarding is based on a fast signal AD conversion with the target in order to perform a new run for an already existing low-power (digital photon energy reconstruction with particular care for multiple events and polarimetry evaluations. Scientific requirement evaluations for Space Astrophysics Satellite applications have been carried out in parallel, targeted to contribute to the ESA Cosmic Vision 2015-2025 Announcement of Opportunity. Detailed accommodation studies are undergoing, as part of this programme, to size a "Large area arcsecond angular resolution Imager" for the Gamma Ray Imager satellite (Knödlseder et al., this conference).and a new Gamma-ray Wide Field Camera for the "EDGE" proposal (Piro et al., this conference). Finally, an extended market study for cost analysis evaluation in view of the foreseen massive detector production has been performed.

  12. Kondrashov Gammas. PC database for gamma-rays from radionuclides. Summary documentation

    International Nuclear Information System (INIS)

    Lemmel, H.D.

    1996-01-01

    A PC database by V. Kondrashov containing energies and yields of gamma-rays from radionuclides is described. The PC diskette is available from the IAEA Nuclear Data Section, cost free upon request. (author)

  13. Gamma-ray emission from internal shocks in novae

    Science.gov (United States)

    Martin, P.; Dubus, G.; Jean, P.; Tatischeff, V.; Dosne, C.

    2018-04-01

    Context. Gamma-ray emission at energies ≥100 MeV has been detected from nine novae using the Fermi Large Area Telescope (LAT), and can be explained by particle acceleration at shocks in these systems. Eight out of these nine objects are classical novae in which interaction of the ejecta with a tenuous circumbinary material is not expected to generate detectable gamma-ray emission. Aim. We examine whether particle acceleration at internal shocks can account for the gamma-ray emission from these novae. The shocks result from the interaction of a fast wind radiatively-driven by nuclear burning on the white dwarf with material ejected in the initial runaway stage of the nova outburst. Methods: We present a one-dimensional model for the dynamics of a forward and reverse shock system in a nova ejecta, and for the associated time-dependent particle acceleration and high-energy gamma-ray emission. Non-thermal proton and electron spectra are calculated by solving a time-dependent transport equation for particle injection, acceleration, losses, and escape from the shock region. The predicted emission is compared to LAT observations of V407 Cyg, V1324 Sco, V959 Mon, V339 Del, V1369 Cen, and V5668 Sgr. Results: The ≥100 MeV gamma-ray emission arises predominantly from particles accelerated up to 100 GeV at the reverse shock and undergoing hadronic interactions in the dense cooling layer downstream of the shock. The emission rises within days after the onset of the wind, quickly reaches a maximum, and its subsequent decrease reflects mostly the time evolution of the wind properties. Comparison to gamma-ray data points to a typical scenario where an ejecta of mass 10-5-10-4 M⊙ expands in a homologous way with a maximum velocity of 1000-2000 km s-1, followed within a day by a wind with a velocity values of which result in the majority of best-fit models having gamma-ray spectra with a high-energy turnover below 10 GeV. Our typical model is able to account for the main

  14. Ultra high energy gamma-ray astronomy

    International Nuclear Information System (INIS)

    Wdowczyk, J.

    1986-01-01

    The experimental data on ultra high energy γ-rays are reviewed and a comparison of the properties of photon and proton initiated shower is made. The consequences of the existence of the strong ultra high energy γ-ray sources for other observations is analysed and possible mechanisms for the production of ultra high energy γ-rays in the sources are discussed. It is demonstrated that if the γ-rays are produced via cosmic ray interactions the sources have to produce very high fluxes of cosmic ray particles. In fact it is possible that a small number of such sources can supply the whole Galactic cosmic ray flux

  15. Calibration and control modules for gamma-ray borehole loggers

    International Nuclear Information System (INIS)

    1983-01-01

    A calibration pad for quantitative evaluation of gamma-ray logs, developed and constructed by CNEA is described. The facility is composed of a set of mineralized modules with which it is intended to reproduce the natural variable conditions found in boreholes drilled for uranium mineral exploration, such as the ore concentration, rock's density and porosity, water content, etc. The facility is able to operate under different radiometric models, as follow: 1) gross-count gamma-ray models; 2) gamma-spectrometer models; 3) neutronic-fission models, and 4) models for determination of magnetic susceptibility, density, neutron-neutron, etc. The gathered information allows the adequate quantitative radiometric evaluation of the ore bodies crossed by exploration holes, and also allows the correlation of gamma-ray logs obtained by different logger-equipments. The paper includes the description of the project development and the standards established for the facility's operation. (M.E.L.) [es

  16. Laser Compton Scattering Gamma Ray Induced Photo-Trasmutation

    CERN Document Server

    Li, Dazhi

    2004-01-01

    High brightness beams of gamma rays produced with laser Compton scattering have the potential to realize photo-transmutation through (γ,n) reaction, implying an efficient method to dispose long-lived fission products. Preliminary investigations have been carried out in understanding the feasibility of development of a transmutation facility to repose nuclear waste. A laser Compton scattering experimental setup based on a storage ring started to generate gamma-ray beams for studying the coupling of gamma photons and nuclear giant resonance. This paper demonstrates the dependency of nuclear transmutation efficiency on target dimensions and gamma ray features. 197Au sample was adopted in our experiment, and experimental results correspond to the theoretical estimations.

  17. Response of human lymphocytes to low gamma ray doses

    International Nuclear Information System (INIS)

    Vega Carrillo, HR; Banuelos Valenzuela, R; Manzanares Acuna, E; Sanchez-Rodriguez, S.H

    2001-01-01

    Radiation and non-radiation workers lymphocytes were exposed to a low strength gamma-ray field to determine heat shock protein expression in function of radiation dose. Protein identification was carried out using mAb raised against Hsp25, Hsp60, Hsp70 and Hsp90; from these, only Hsp70 protein was detected before and after lymphocyte irradiation. In all cases, an increasing trend of relative amounts of Hsp70 in function to irradiation time was observed. After 70.5 mGy gamma-ray dose, radiation worker's lymphocytes expressed more Hsp70 protein, than non-radiation workers' lymphocytes, indicating a larger tolerance to gamma rays (gamma tolerance), due to an adaptation process developed by their labor condition (Au)

  18. Gamma ray induced chromophore modification of softwood thermomechanical pulp

    International Nuclear Information System (INIS)

    Robert, S.; Daneault, C.; Viel, C.; Lepine, F.

    1992-01-01

    This study focuses on bleaching a softwood (black spruce, balsam fur) thermomechanical pulp with gamma rays. Gamma rays are known for their enormous penetrating power, along with their ionizing properties. They can generate highly energetic radicals capable of oxidizing lignin chromophores. The authors studied the influence of isopropyl alcohol, sodium borohydride, oxygen, hydrogen peroxide, nitrogen dioxide and water along with gamma ray irradiation of the pulps. The authors measured the optimal dose and dose rate, along with the influence of the radical scavengers like oxygen on the bleaching effect of gamma irradiated pulps. They observe various degrees of bleaching of these pulps. Evidence relates this bleaching to the generation of perhydroxyl anions upon irradiation of water. Also, they were able to pinpoint the influence of the dose rate on the rate of formation and disappearance of these perhydroxyl anions and their influence on bleaching kinetics. Stability toward photoyellowing, and photoyellowing's kinetic of papers from these pulps was also studied

  19. On response operator in semiconductor gamma ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Krnac, S [Slovak Technical Univ., Bratislava (Slovakia); Povinec, P [International Atomic Energy Agency, Monaco (Monaco). MEL; Ragan, R [Inst. of Preventive and Clinical Medicine, Bratislava (Slovakia)

    1996-12-31

    Some results of the scaling confirmation factor analysis (SCFA) application in semiconductor gamma-ray spectrometry presented in this contribution points out to a new ground for evaluation the gamma-ray spectra. This whole-spectrum processing approach considerably increases detection sensitivity, especially, if significant interferences being present in the measured spectrum. Precision of the SCFA method is determined by choice of a sufficient number of suitable calibration gamma-ray sources in the energy region of interest, by setting up an acceptable latent hypothesis and by chosen experimental quantification of spectra. The SCFA method is very advantageous to use, for instance, in ultra low-level gamma-spectrometry where counting rates in full energy peaks are extremely low as compared with background interferences. It enables to increase of the sensitivity by the 5-10 times in comparison with the traditional full energy peak net area method (J.K.). 1 fig., 2 tabs., 6 refs.

  20. On response operator in semiconductor gamma ray spectrometry

    International Nuclear Information System (INIS)

    Krnac, S.; Povinec, P.

    1995-01-01

    Some results of the scaling confirmation factor analysis (SCFA) application in semiconductor gamma-ray spectrometry presented in this contribution points out to a new ground for evaluation the gamma-ray spectra. This whole-spectrum processing approach considerably increases detection sensitivity, especially, if significant interferences being present in the measured spectrum. Precision of the SCFA method is determined by choice of a sufficient number of suitable calibration gamma-ray sources in the energy region of interest, by setting up an acceptable latent hypothesis and by chosen experimental quantification of spectra. The SCFA method is very advantageous to use, for instance, in ultra low-level gamma-spectrometry where counting rates in full energy peaks are extremely low as compared with background interferences. It enables to increase of the sensitivity by the 5-10 times in comparison with the traditional full energy peak net area method (J.K.). 1 fig., 2 tabs., 6 refs