Sample records for gamma-ray logging systems

  1. Outcrop gamma-ray logging applied to subsurface petroleum geology

    SciTech Connect (OSTI)

    Slatt, R.M.; Borer, J.M.; Horn, B.W. [Colorado School of Mines, Golden, CO (United States)] [and others

    1995-10-01T23:59:59.000Z

    Developing a gamma-ray log profile of an outcrop with a hand-held scintillometer has many applications to subsurface petroleum geology. The outcrop gamma-ray log provides a readily understandable bridge between what is observed in outcrop and what is to be interpreted on well logs and seismic records. Several examples are presented in this paper that demonstrate major applications. An outcrop from the Cretaceous Mesaverde Group in Colorado provides an excellent example of the use of outcrop gamma-ray logs to better visualize spatial variability of depositional settings for improved well log correlations. Out crops from the Cretaceous Almond Formation, Niobrara Formation, and Graneros Shale in Colorado serve as examples of outcrop gamma-ray logging used to correlate outcrops with their subsurface equivalents for improved lithologic and stratigraphic interpretation of well logs. Outcrops of the Cretaceous Sharon Springs Member of the Pierre Shale in Colorado and the Eocene Green River Formation in Wyoming provide examples of the application of outcrop-gamma ray logging to identify and characterize organic-rich shales in outcrops and on well logs. Outcrops of the Pennsylvanian Jackfork Formation in Arkansas demonstrate the use of outcrop logging to yield improved interpretation of reservoir quality on well logs and for one- and two-dimensional seismic modeling. An outcrop of Precambrian and Cambro-Ordovician rocks from Algeria provides an example of outcrop logging to recognize unconformities and other major surfaces on well logs. An outcrop of the Niobrara Formation in Colorado is used as an example for improved understanding of horizontal gamma-ray log response. The example logs presented are all drived with a hand-held scintillometer. This technique is simple, quick, and relatively inexpensive, so is recommended for any outcrop work that is intended to be applied t;o subsurface well logs or seismic interpretation.

  2. Gamma-ray tracking method for pet systems

    DOE Patents [OSTI]

    Mihailescu, Lucian; Vetter, Kai M.

    2010-06-08T23:59:59.000Z

    Gamma-ray tracking methods for use with granular, position sensitive detectors identify the sequence of the interactions taking place in the detector and, hence, the position of the first interaction. The improved position resolution in finding the first interaction in the detection system determines a better definition of the direction of the gamma-ray photon, and hence, a superior source image resolution. A PET system using such a method will have increased efficiency and position resolution.

  3. Gamma-ray Albedo of Small Solar System Bodies

    SciTech Connect (OSTI)

    Moskalenko, I.V.

    2008-03-25T23:59:59.000Z

    We calculate the {gamma}-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the {gamma}-ray albedo for the Main Belt and KBOs strongly depends on the small-body mass spectrum of each system and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). If detected, it can be used to derive the mass spectrum of small bodies in the Main Belt and Kuiper Belt and to probe the spectrum of CR nuclei at close-to-interstellar conditions. The orbits of the Main Belt asteroids and KBOs are distributed near the ecliptic, which passes through the Galactic center and high Galactic latitudes. Therefore, the {gamma}-ray emission by the Main Belt and Kuiper Belt has to be taken into account when analyzing weak {gamma}-ray sources close to the ecliptic. The asteroid albedo spectrum also exhibits a 511 keV line due to secondary positrons annihilating in the rock. This may be an important and previously unrecognized celestial foreground for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of the Galactic 511 keV line emission including the direction of the Galactic center. For details of our calculations and references see [1].

  4. SWEPP Gamma-Ray Spectrometer System software design description

    SciTech Connect (OSTI)

    Femec, D.A.; Killian, E.W.

    1994-08-01T23:59:59.000Z

    To assist in the characterization of the radiological contents of contract-handled waste containers at the Stored Waste Examination Pilot Plant (SWEPP), the SWEPP Gamma-Ray Spectrometer (SGRS) System has been developed by the Radiation Measurements and Development Unit of the Idaho National Engineering Laboratory. The SGRS system software controls turntable and detector system activities. In addition to determining the concentrations of gamma-ray-emitting radionuclides, this software also calculates attenuation-corrected isotopic mass ratios of-specific interest. This document describes the software design for the data acquisition and analysis software associated with the SGRS system.

  5. High energy gamma-rays from massive binary systems

    E-Print Network [OSTI]

    W. Bednarek

    2008-06-27T23:59:59.000Z

    During last years a few massive binary systems have been detected in the TeV gamma-rays. This gamma-ray emission is clearly modulated with the orbital periods of these binaries suggesting its origin inside the binary system. In this paper we summarize the anisotropic IC e-p pair cascade model as likely explanation of these observations. We consider scenarios in which particles are accelerated to relativistic energies, either due to the presence of an energetic pulsar inside the binary, or as a result of accretion process onto the compact object during which the jet is launched from the inner part of the accretion disk, or in collisions of stellar winds from the massive companions.

  6. A study of the performance parameters of the High Altitude Gamma Ray (HAGAR) telescope system at Ladakh in India

    E-Print Network [OSTI]

    Shyamasundar, R.K.

    results of Monte Carlo simulations for the High Altitude Gamma Ray (HAGAR) telescope array which detects High Altitude GAmma Ray (HAGAR) telescope system is designed to detect very high energy gamma rays fromA study of the performance parameters of the High Altitude Gamma Ray (HAGAR) telescope system

  7. THE EFFECT OF RADON TRANSPORT IN GROUNDWATER UPON GAMMA-RAY BOREHOLE LOGS

    E-Print Network [OSTI]

    Nelson, P.H.

    2010-01-01T23:59:59.000Z

    f o r Uranium by Gamma-Ray Spectrometry." Geophysics, 45,222 Emanation from Gamma Spectrometry on Stripa Samples B.222 Emanation from Gamma Spectrometry on Stripa Samples B.

  8. Gamma Ray Array Detector Trigger Sub-System

    E-Print Network [OSTI]

    Du Zhong-Wei; Su Hong; Qian Yi; Kong Jie

    2013-05-19T23:59:59.000Z

    Gamma Ray Array Detector (GRAD) is one of External Target Facility (ETF) subsystems at the Heavy Ion Research Facility at Lanzhou. The trigger subsystem of the GRAD has been developed based on Field Programmable Gate Array (FPGAs) and PXI interface. The GRAD trigger subsystem makes prompt L1 trigger decisions to select valid events. These decisions are made by processing the hit signals from 1024 CsI scintillators of the GRAD. According to the physical requirements, the GRAD trigger subsystem generates 12-bit trigger signals that are passed to the ETF global trigger system. In addition, the GRAD trigger subsystem generates trigger data that are packed and transmitted to the host computer via PXI bus for off-line analysis. The trigger processing is implemented in the front-end electronics and one FPGA of the trigger module. The logic of PXI transmission and reconfiguration is implemented in the other FPGA of the trigger module. The reliable and efficient performance in the Gamma-ray experiments demonstrates that the GRAD trigger subsystem is capable to satisfy the physical requirements.

  9. Neutron interrogation system using high gamma ray signature to detect contraband special nuclear materials in cargo

    DOE Patents [OSTI]

    Slaughter, Dennis R. (Oakland, CA); Pohl, Bertram A. (Berkeley, CA); Dougan, Arden D. (San Ramon, CA); Bernstein, Adam (Palo Alto, CA); Prussin, Stanley G. (Kensington, CA); Norman, Eric B. (Oakland, CA)

    2008-04-15T23:59:59.000Z

    A system for inspecting cargo for the presence of special nuclear material. The cargo is irradiated with neutrons. The neutrons produce fission products in the special nuclear material which generate gamma rays. The gamma rays are detecting indicating the presence of the special nuclear material.

  10. Short Gamma Ray Bursts as possible electromagnetic counterpart of coalescing binary systems

    E-Print Network [OSTI]

    S. Capozziello; M. De Laurentis; I. De Martino; M. Formisano

    2010-04-27T23:59:59.000Z

    Coalescing binary systems, consisting of two collapsed objects, are among the most promising sources of high frequency gravitational waves signals detectable, in principle, by ground-based interferometers. Binary systems of Neutron Star or Black Hole/Neutron Star mergers should also give rise to short Gamma Ray Bursts, a subclass of Gamma Ray Bursts. Short-hard-Gamma Ray Bursts might thus provide a powerful way to infer the merger rate of two-collapsed object binaries. Under the hypothesis that most short Gamma Ray Bursts originate from binaries of Neutron Star or Black Hole/Neutron Star mergers, we outline here the possibility to associate short Gamma Ray Bursts as electromagnetic counterpart of coalescing binary systems.

  11. Gamma-ray imaging system. Innovative technology summary report

    SciTech Connect (OSTI)

    NONE

    1998-11-01T23:59:59.000Z

    The RadScan 600 gamma-ray imaging system is designed to survey large surface areas for radiological contamination with accuracy and efficiency. The resulting survey data are clear, concise, and precise in describing how much contamination is present at exact locations. Data can be permanently stored electronically and on video tape, making storage and retrieval economical and efficient. This technology can perform accurate measurements in high radiation contamination areas while minimizing worker exposure. The RadScan 600 system is a safe and effective alternative to hand-held radiation detection devices. Performance data of the demonstrated survey area of the RadScan 600 system versus the baseline, which is the hand-held radiation detection devices (RO-2 and RO-7) for a given survey, production rate is 72% of the baseline. It should be noted that the innovative technology provides 100% coverage at a unit cost of $8.64/m{sup 2} versus a static measurement of a unit cost of $1.61/m{sup 2} for the baseline.

  12. Temperatures and Natural Gamma-Ray Logs Obtained in 1986 from...

    Open Energy Info (EERE)

    Changes in temperature logs run in July and September appear to result from fluid loss to the formation during and following drilling and possibly to ground shaking...

  13. Radiation detection system for portable gamma-ray spectroscopy

    DOE Patents [OSTI]

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

    2006-06-20T23:59:59.000Z

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

  14. System to quantify gamma-ray radial energy deposition in semiconductor detectors

    DOE Patents [OSTI]

    Kammeraad, Judith E. (San Ramon, CA); Blair, Jerome J. (Las Vegas, NV)

    2001-01-01T23:59:59.000Z

    A system for measuring gamma-ray radial energy deposition is provided for use in conjunction with a semiconductor detector. The detector comprises two electrodes and a detector material, and defines a plurality of zones within the detecting material in parallel with the two electrodes. The detector produces a charge signal E(t) when a gamma-ray interacts with the detector. Digitizing means are provided for converting the charge signal E(t) into a digitized signal. A computational means receives the digitized signal and calculates in which of the plurality of zones the gamma-ray deposited energy when interacting with the detector. The computational means produces an output indicating the amount of energy deposited by the gamma-ray in each of the plurality of zones.

  15. Multi-isotopic gamma-ray assay system for alpha-contaminated waste

    SciTech Connect (OSTI)

    Close, D.A.; Pratt, J.C.; Caldwell, J.T.; Kunz, W.E.; Schultz, F.J.; Haff, K.W.

    1983-01-01T23:59:59.000Z

    The capability of an existing segmented gamma-ray system is being expanded for the analysis of alpha-contaminated waste drums. A cursory assay of 114 transuranic waste drums of 208-l capacity has been made. Analysis of these data indicates a detection limit better than 100 nCi/g of waste for /sup 237/Np//sup 233/Pa, /sup 239/Pu, /sup 241/Am, /sup 243/Am//sup 239/Np, /sup 60/Co, /sup 125/Sb, /sup 134/ /sup 137/Cs, and /sup 154/Eu. A pending Code of Federal Regulation (10CFR61) stipulates that the nuclear industry quantify not only its transuranic waste, but also certain beta- and gamma-ray-emitting fission products. An assay system based on gamma-ray spectroscopy is the only system that can meet this requirement for the fission products.

  16. SWEPP gamma-ray spectrometer system software test plan and report

    SciTech Connect (OSTI)

    Femec, D.A.

    1994-09-01T23:59:59.000Z

    The SWEPP Gamma-Ray Spectrometer (SGRS) System has been developed by the Radiation Measurements and Development Unit of the Idaho National Engineering Laboratory to assist in the characterization of the radiological contents of contact-handled waste containers at the Stored Waste Examination Pilot Plant (SWEPP). In addition to determining the concentrations of gamma-ray-emitting radionuclides, the software also calculates attenuation-corrected isotopic mass ratios of specific interest, and provides controls for SGRS hardware as required. This document presents the test plan and report for the data acquisition and analysis software associated with the SGRS system.

  17. Real time method and computer system for identifying radioactive materials from HPGe gamma-ray spectroscopy

    DOE Patents [OSTI]

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

    2007-10-23T23:59:59.000Z

    A real-time method and computer system for identifying radioactive materials which collects gamma count rates from a HPGe gamma-radiation detector to produce a high-resolution gamma-ray energy spectrum. A library of nuclear material definitions ("library definitions") is provided, with each uniquely associated with a nuclide or isotope material and each comprising at least one logic condition associated with a spectral parameter of a gamma-ray energy spectrum. The method determines whether the spectral parameters of said high-resolution gamma-ray energy spectrum satisfy all the logic conditions of any one of the library definitions, and subsequently uniquely identifies the material type as that nuclide or isotope material associated with the satisfied library definition. The method is iteratively repeated to update the spectrum and identification in real time.

  18. DEVELOPMENT OF DEPOSIT DETECTION SYSTEM IN PIPELINES OF THE STEELWORKS USING CS-137 GAMMA-RAY

    SciTech Connect (OSTI)

    Song, Won-Joon; Lee, Seung-Hee; Jeong, Hee-Dong [Research Institute of Industrial Science and Technology, 32 Hyoja-Dong, Nam-Ku, Pohang, 790-330 (Korea, Republic of)

    2008-02-28T23:59:59.000Z

    The deposit is built up in the pipeline of the steelworks by the chemical reaction among COG (coke oven gas), BFG (blast furnace gas), moisture, and steel in the high temperature environment and obstructs the smooth gas flow. In this study a gamma-ray system is developed to detect the deposit accumulated in pipelines and calculate the accumulation rate with respect to the cross section area of pipes. Cs-137 is used as the gamma-ray source and the system is designed to apply to pipes of various diameters. This system also includes the DB for storage and display of the measurement results so that it can be used for the efficient management of the pipelines.

  19. Gadolinium-doped water cerenkov-based neutron and high energy gamma-ray detector and radiation portal monitoring system

    DOE Patents [OSTI]

    Dazeley, Steven A; Svoboda, Robert C; Bernstein, Adam; Bowden, Nathaniel

    2013-02-12T23:59:59.000Z

    A water Cerenkov-based neutron and high energy gamma ray detector and radiation portal monitoring system using water doped with a Gadolinium (Gd)-based compound as the Cerenkov radiator. An optically opaque enclosure is provided surrounding a detection chamber filled with the Cerenkov radiator, and photomultipliers are optically connected to the detect Cerenkov radiation generated by the Cerenkov radiator from incident high energy gamma rays or gamma rays induced by neutron capture on the Gd of incident neutrons from a fission source. The PMT signals are then used to determine time correlations indicative of neutron multiplicity events characteristic of a fission source.

  20. Systems for increasing the sensitivity of gamma-ray imagers

    DOE Patents [OSTI]

    Mihailescu, Lucian; Vetter, Kai M.; Chivers, Daniel H.

    2012-12-11T23:59:59.000Z

    Systems that increase the position resolution and granularity of double sided segmented semiconductor detectors are provided. These systems increase the imaging resolution capability of such detectors, either used as Compton cameras, or as position sensitive radiation detectors in imagers such as SPECT, PET, coded apertures, multi-pinhole imagers, or other spatial or temporal modulated imagers.

  1. System and method for resolving gamma-ray spectra

    DOE Patents [OSTI]

    Gentile, Charles A.; Perry, Jason; Langish, Stephen W.; Silber, Kenneth; Davis, William M.; Mastrovito, Dana

    2010-05-04T23:59:59.000Z

    A system for identifying radionuclide emissions is described. The system includes at least one processor for processing output signals from a radionuclide detecting device, at least one training algorithm run by the at least one processor for analyzing data derived from at least one set of known sample data from the output signals, at least one classification algorithm derived from the training algorithm for classifying unknown sample data, wherein the at least one training algorithm analyzes the at least one sample data set to derive at least one rule used by said classification algorithm for identifying at least one radionuclide emission detected by the detecting device.

  2. X-ray and gamma ray detector readout system

    DOE Patents [OSTI]

    Tumer, Tumay O (Riverside, CA); Clajus, Martin (Los Angeles, CA); Visser, Gerard (Bloomington, IN)

    2010-10-19T23:59:59.000Z

    A readout electronics scheme is under development for high resolution, compact PET (positron emission tomography) imagers based on LSO (lutetium ortho-oxysilicate, Lu.sub.2SiO.sub.5) scintillator and avalanche photodiode (APD) arrays. The key is to obtain sufficient timing and energy resolution at a low power level, less than about 30 mW per channel, including all required functions. To this end, a simple leading edge level crossing discriminator is used, in combination with a transimpedance preamplifier. The APD used has a gain of order 1,000, and an output noise current of several pA/ Hz, allowing bipolar technology to be used instead of CMOS, for increased speed and power efficiency. A prototype of the preamplifier and discriminator has been constructed, achieving timing resolution of 1.5 ns FWHM, 2.7 ns full width at one tenth maximum, relative to an LSO/PMT detector, and an energy resolution of 13.6% FWHM at 511 keV, while operating at a power level of 22 mW per channel. Work is in progress towards integration of this preamplifier and discriminator with appropriate coincidence logic and amplitude measurement circuits in an ASIC suitable for a high resolution compact PET instrument. The detector system and/or ASIC can also be used for many other applications for medical to industrial imaging.

  3. Gamma Ray Bursts

    E-Print Network [OSTI]

    Stahl, Bennett

    2014-01-01T23:59:59.000Z

    Olson. “Observations of gamma-ray bursts of cosmic origin. ”E. Lingenfelter. “Gamma-ray bursts. ” Annual Review of652-654. Waxman, Eli. “Gamma-ray-burst afterglow: supporting

  4. Innovative Gamma Ray Spectrometer Detection Systems for Conducting Scanning Surveys on Challenging Terrain - 13583

    SciTech Connect (OSTI)

    Palladino, Carl; Mason, Bryan; Engle, Matt; LeVangie, James [The Palladino Company, Inc., 720 Fillmore St., San Francisco, CA 94117 (United States)] [The Palladino Company, Inc., 720 Fillmore St., San Francisco, CA 94117 (United States); Dempsey, Gregg [United States Environmental Protection Agency, P.O. Box 98517, Las Vegas, NV 89193-8517 (United States)] [United States Environmental Protection Agency, P.O. Box 98517, Las Vegas, NV 89193-8517 (United States); Klemovich, Ron [HydroGeoLogic, Inc., 6340 Glenwood, Suite 200, Building No. 7, Overland Park, KS 66202 (United States)] [HydroGeoLogic, Inc., 6340 Glenwood, Suite 200, Building No. 7, Overland Park, KS 66202 (United States)

    2013-07-01T23:59:59.000Z

    The Santa Susana Field Laboratory located near Simi Valley, California was investigated to determine the nature and extent of gamma radiation anomalies. The primary objective was to conduct gamma scanning surveys over 100 percent of the approximately 1,906,000 square meters (471 acre) project site with the most sensitive detection system possible. The site had challenging topography that was not conducive to traditional gamma scanning detection systems. Terrain slope varied from horizontal to 48 degrees and the ground surface ranged from flat, grassy meadows to steep, rocky hillsides. In addition, the site was home to many protected endangered plant and animal species, and archaeologically significant sites that required minimal to no disturbance of the ground surface. Therefore, four innovative and unique gamma ray spectrometer detection systems were designed and constructed to successfully conduct gamma scanning surveys of approximately 1,076,000 square meters (266 acres) of the site. (authors)

  5. Experimental investigation of silicon photomultipliers as compact light readout systems for gamma-ray spectroscopy applications in fusion plasmas

    SciTech Connect (OSTI)

    Nocente, M., E-mail: massimo.nocente@mib.infn.it; Gorini, G. [Dipartimento di Fisica “G. Occhialini,” Università degli Studi di Milano-Bicocca, Milano (Italy); Istituto di Fisica del Plasma “P. Caldirola,” EURATOM-ENEA-CNR Association, Milano (Italy); Fazzi, A.; Lorenzoli, M.; Pirovano, C. [Dipartimento di Energia, CeSNEF, Politecnico di Milano, Milano (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Milano, Milano (Italy); Tardocchi, M. [Istituto di Fisica del Plasma “P. Caldirola,” EURATOM-ENEA-CNR Association, Milano (Italy); Cazzaniga, C.; Rebai, M. [Dipartimento di Fisica “G. Occhialini,” Università degli Studi di Milano-Bicocca, Milano (Italy); Uboldi, C.; Varoli, V. [Dipartimento di Energia, CeSNEF, Politecnico di Milano, Milano (Italy)

    2014-11-15T23:59:59.000Z

    A matrix of Silicon Photo Multipliers has been developed for light readout from a large area 1 in. × 1 in. LaBr{sub 3} crystal. The system has been characterized in the laboratory and its performance compared to that of a conventional photo multiplier tube. A pulse duration of 100 ns was achieved, which opens up to spectroscopy applications at high counting rates. The energy resolution measured using radioactive sources extrapolates to 3%–4% in the energy range E{sub ?} = 3–5 MeV, enabling gamma-ray spectroscopy measurements at good energy resolution. The results reported here are of relevance in view of the development of compact gamma-ray detectors with spectroscopy capabilities, such as an enhanced gamma-ray camera for high power fusion plasmas, where the use of photomultiplier is impeded by space limitation and sensitivity to magnetic fields.

  6. Gamma ray generator

    DOE Patents [OSTI]

    Firestone, Richard B; Reijonen, Jani

    2014-05-27T23:59:59.000Z

    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.

  7. High spatial resolution X-ray and gamma ray imaging system using diffraction crystals

    DOE Patents [OSTI]

    Smither, Robert K. (Hinsdale, IL)

    2011-05-17T23:59:59.000Z

    A method and a device for high spatial resolution imaging of a plurality of sources of x-ray and gamma-ray radiation are provided. The device comprises a plurality of arrays, with each array comprising a plurality of elements comprising a first collimator, a diffracting crystal, a second collimator, and a detector.

  8. Gamma Ray Bursts Sudden, intense flashes of gamma rays

    E-Print Network [OSTI]

    Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

    Gamma Ray Bursts #12;The Case Sudden, intense flashes of gamma rays come from nowhere and disappear with out a trace. Incredibly powerful: A single gamma ray burst is hundreds of times brighter a supernova #12;Who Vela (1960's) Looking for arms testing, found gamma ray bursts Compton Gamma Ray Observatory

  9. Gamma ray detector shield

    DOE Patents [OSTI]

    Ohlinger, R.D.; Humphrey, H.W.

    1985-08-26T23:59:59.000Z

    A gamma ray detector shield comprised of a rigid, lead, cylindrical-shaped vessel having upper and lower portions with an pneumatically driven, sliding top assembly. Disposed inside the lead shield is a gamma ray scintillation crystal detector. Access to the gamma detector is through the sliding top assembly.

  10. Gamma-ray emission states in the redback millisecond pulsar binary system PSR J1227-4853

    E-Print Network [OSTI]

    Bednarek, W

    2015-01-01T23:59:59.000Z

    Long expected transition states between the rotation powered and accretion powered non-thermal emission in the millisecond pulsar binary systems have been recently observed in the case of three objects PSR J1023+0038, PSR J1824-2452, and PSR J1227-4859. Surprisingly, the transition is related to the significant change in the $\\gamma$-ray flux being a factor of a few higher with the presence of an accretion disk. The origin of this enhanced emission seems to be related to the penetration of the inner pulsar magnetosphere by the accretion disk. We propose that the radiation processes, characteristic for the rotation powered pulsar, can co-exist with the presence of an accretion disk in the inner pulsar magnetosphere. In our scenario additional $\\gamma$-ray emission is produced by secondary leptons, originated close to the acceleration gap, which Compton up-scatter thermal radiation from the accretion disk to GeV energies. The accretion disk penetrates deep into the pulsar magnetosphere allowing the matter to fa...

  11. Gamma-Ray Signatures for State-Of-Health Analysis and Monitoring of Widely-Arrayed Radiation Portal Monitor Systems

    SciTech Connect (OSTI)

    Woodring, Mitchell L.; Ely, James H.; Angel, Linda K.; Wright, Ingrid H.; Eslinger, Melany A.; Pospical, A. Jill; Ellis, John E.

    2008-05-15T23:59:59.000Z

    Pacific Northwest National Laboratory (PNNL) has deployed a large array of radiation portal monitors for the Department of Homeland Security U.S. Customs and Border Protection. These portal monitors scan incoming vehicles crossing the U.S. border and shipping containers leaving international ports for radioactive material via gamma-ray and neutron detection. Data produced and captured by these systems are recorded for every vehicle related to radiation signature, sensor/system status, and local background, as well as a host of other variables. Within the Radiation Portal Monitor Project at PNNL, state-of-health observation and analysis for the whole RPM system using these data to determine functionality and performance is being developed. (PIET-43741-TM-492)

  12. Gamma-Ray Bursts

    E-Print Network [OSTI]

    P. Meszaros

    2006-05-30T23:59:59.000Z

    Gamma-ray bursts are the most luminous explosions in the Universe, and their origin and mechanism are the focus of intense research and debate. More than three decades after their discovery, and after pioneering breakthroughs from space and ground experiments, their study is entering a new phase with the recently launched Swift satellite. The interplay between these observations and theoretical models of the prompt gamma ray burst and its afterglow is reviewed.

  13. Report of spectral gamma-ray surveys acquired for the 200-UP-2 project

    SciTech Connect (OSTI)

    Kos, S.E.

    1995-12-01T23:59:59.000Z

    Ten boreholes were logged with the high-resolution, high-purity germanium (PHGe) passive gamma-ray tool, Radionuclide Logging System (RLS), for the 200-UP-2 project. The surveys were acquired during the period September, 1993 to March, 1994. All of the surveys identified the presence of gamma-emitting man-made radionuclides in the sediments surrounding the boreholes. In all of the wells, contamination occurred at or very near ground surface.

  14. GeV gamma-rays and TeV neutrinos from very massive compact binary systems: The case of WR 20a

    E-Print Network [OSTI]

    W. Bednarek

    2005-07-24T23:59:59.000Z

    Massive Wolf-Rayet stars in a compact binary systems are characterised by very strong winds which collide creating a shock wave. If the wind nuclei accelerated at the shock can reach large enough energies, they suffer disintegration in collisions with soft thermal radiation from the massive stars injecting relativistic protons and neutrons. Protons collide with the matter of the wind and a fraction of neutrons colide with the massive stars producing gamma-rays and neutrinos. We calculate the gamma-rays fluxes from the inverse Compton pair cascades, initiated by primary gamma-rays and leptons produced by protons, and the neutrino fluxes produced by protons and neutrons for the example compact massive binary WR 20a. From normalization of the gamma-ray spectra to the fluxes of the EGRET sources, 2EG J1021-5835 and 2EG J1049-5847, we conclude that this massive binary can be detected by the IceCube type neutrino detector with the event rate between a few up to a few tens per km^2 per yr.

  15. Gamma ray bursts in their historic context

    E-Print Network [OSTI]

    Trimble, V

    2004-01-01T23:59:59.000Z

    Gamma Ray Bursts In Their Historic Context Virginia TrimbleMD 20742 USA Abstract. Gamma ray bursts remained essentiallyalso applies to the gamma ray bursts. First, an observation

  16. Gamma Ray Bursts from Minijets

    E-Print Network [OSTI]

    Nir J. Shaviv; Arnon Dar

    1994-07-14T23:59:59.000Z

    Striking similarities exist between high energy gamma ray emission from active galactic nuclei (AGN) and gamma ray bursts (GRBs). They suggest that GRBs are generated by inverse Compton scattering from highly relativistic electrons in transient jets. Such jets may be produced along the axis of an accretion disk formed around stellar black holes (BH) or neutron stars (NS) in BH-NS and NS-NS mergers and in accretion induced collapse of magnetized white dwarfs (WD) or neutron stars in close binary systems. Such events may produce the cosmological GRBs. Transient jets formed by single old magnetized neutron stars in an extended Galactic halo may produce a local population of GRBs. Here we show that jet production of GRBs by inverse Compton scattering can explain quite simply the striking correlations that exist between various temporal features of GRBs, their duration histogram, the power spectrum of their complex multipeak light curves, their power-law high energy spectra and other features of GRBs. Some additional predictions are made including the expected polarization of gamma-rays in the bursts.

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

    SciTech Connect (OSTI)

    Thompson, Shannon; Rodriguez, Rene; Billock, Paul [HydroGeoLogic, Inc., 11107 Sunset Hills Road, Suite 400, Reston, VA 20190 (United States)] [HydroGeoLogic, Inc., 11107 Sunset Hills Road, Suite 400, Reston, VA 20190 (United States); Lit, Peter [Nomad Science Group, 7738 Nautilus Shell Street, Las Vegas, NV 89139 (United States)] [Nomad Science Group, 7738 Nautilus Shell Street, Las Vegas, NV 89139 (United States)

    2013-07-01T23:59:59.000Z

    HydroGeoLogic (HGL), Inc. completed a United States Environmental Protection Agency (USEPA) study to characterize radiological contamination at a site near Canoga Park, California. The characterized area contained 470 acres including the site of a prototype commercial nuclear reactor and other nuclear design, testing, and support operations from the 1950's until 1988 [1]. The site history included radiological releases during operation followed by D and D activities. The characterization was conducted under an accelerated schedule and the results will support the project remediation. The project has a rigorous cleanup to background agenda and does not allow for comparison to risk-based guidelines. To target soil sample locations, multiple lines of evidence were evaluated including a gamma radiation survey, geophysical surveys, historical site assessment, aerial photographs, and former worker interviews. Due to the time since production and decay, the primary gamma emitting radionuclide remaining is cesium-137 (Cs-137). The gamma ray survey covered diverse, rugged terrain using custom designed sodium iodide thallium-activated (NaI(Tl)) scintillation detection systems. The survey goals included attaining 100% ground surface coverage and detecting gamma radiation as sensitively as possible. The effectiveness of innovative gamma ray detection systems was tested by correlating field Cs-137 static count ratios to Cs-137 laboratory gamma spectrometry results. As a case study, the area encompassing the former location of the first nuclear power station in the U. S. was scanned, and second by second global positioning system (GPS)-linked gamma spectral data were evaluated by examining total count rate and nuclide-specific regions of interest. To compensate for Compton scattering from higher energy naturally occurring radionuclides (U-238, Th-232 and their progeny, and K-40), count rate ratios of anthropogenic nuclide-specific regions of interest to the total count rate were calculated. From the scanning data, locations with observed Cs-137 ratios exceeding six standard deviations above the mean ratio were mapped in high resolution [2]. Field teams returned to those locations to collect static count measurements using the same detection systems. Soil surface samples were collected at 30 locations and analyzed for Cs-137. An exponential correlation was identified between Cs-137 concentrations in surface soil and field-scanned Cs-137 ratios. The data indicate field minimum detectable concentration (MDC) of Cs-137 at 0.02 Bq/g (0.5 pCi/g) or lower depending on contaminant distribution in soil. (authors)

  18. Gamma Ray Bursts

    E-Print Network [OSTI]

    Peter Mészáros

    2012-04-12T23:59:59.000Z

    Gamma-ray bursts have been detected at photon energies up to tens of GeV. We review some recent developments in the X-ray to GeV photon phenomenology in the light of Swift and Fermi observations, and some of the theoretical models developed to explain them, with a view towards implications for C.T.A.

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

    E-Print Network [OSTI]

    Akkoyun, Serkan

    2012-01-01T23:59:59.000Z

    The gamma-ray tracking detector arrays, such as advanced gamma ray tracking array (AGATA), are quite powerful detection systems in nuclear structure physic studies. In these arrays, the sequences of the gamma-ray interaction points in the detectors can correctly be identified in order to obtain true gamma-ray energies emitted from the nuclei of interest. Together with the gamma-rays, a number of neutrons are also emitted from the nuclei and these neutrons influence gamma-ray spectra. An obvious method of separating between neutrons and gamma-rays is based on the time-of-flight (tof) technique. This work aims obtaining tof distributions of gamma-rays and neutrons by using feed-forward artificial neural network (ANN). It was shown that, ANN can correctly classify gamma-ray and neutron events. Testing of trained networks on experimental data clearly shows up tof discrimination of gamma-rays and neutrons.

  20. Nuclear Instruments and Methods in Physics Research A 476 (2002) 522526 A gamma-ray spectrometer system for fusion applications

    E-Print Network [OSTI]

    Martín-Solís, José Ramón

    Nuclear Instruments and Methods in Physics Research A 476 (2002) 522­526 A gamma-ray spectrometer electrons hitting the inconel poloidal limiter and/or the vessel; and (b) neutron capture gamma the bremsstrahlung spectra is in agreement with the runaway energy predicted by a test particle model of runaway

  1. The Universe Viewed in Gamma-Rays 1 The Control System of the MAGIC telescope

    E-Print Network [OSTI]

    Enomoto, Ryoji

    will be commissioned during this year. The control system of the telescope is distributed over a number of functional on the Central Control and Camera Control systems. 1. Introduction MAGIC[1] is a new generation Imaging Air Cherenkov Telescope (IACT) allocated at the IAC site in the Canary island of La Palma. The aim of the tele

  2. Hand-held, mechanically cooled, radiation detection system for gamma-ray spectroscopy

    DOE Patents [OSTI]

    Burks, Morgan Thomas; Eckels, Joel Del

    2010-06-08T23:59:59.000Z

    In one embodiment, a radiation detection system is provided including a radiation detector and a first enclosure encapsulating the radiation detector, the first enclosure including a low-emissivity infra-red (IR) reflective coating used to thermally isolate the radiation detector. Additionally, a second enclosure encapsulating the first enclosure is included, the first enclosure being suspension mounted to the second enclosure. Further, a cooler capable of cooling the radiation detector is included. Still yet, a first cooling interface positioned on the second enclosure is included for coupling the cooler and the first enclosure. Furthermore, a second cooling interface positioned on the second enclosure and capable of coupling the first enclosure to a cooler separate from the radiation detection system is included. Other embodiments are also presented.

  3. The EGS4 Code System: Solution of gamma-ray and electron transport problems

    SciTech Connect (OSTI)

    Nelson, W.R.; Namito, Yoshihito.

    1990-02-09T23:59:59.000Z

    In this paper we present an overview of the EGS4 Code System -- a general purpose package for the Monte Carlo simulation of the transport of electrons and photons. During the last 10-15 years EGS has been widely used to design accelerators and detectors for high-energy physics. More recently the code has been found to be of tremendous use in medical radiation physics and dosimetry. The problem-solving capabilities of EGS4 will be demonstrated by means of a variety of practical examples. To facilitate this review, we will take advantage of a new add-on package, called SHOWGRAF, to display particle trajectories in complicated geometries. These are shown as 2-D laser pictures in the written paper and as photographic slides of a 3-D high-resolution color monitor during the oral presentation. 11 refs., 15 figs.

  4. Energetics of Gamma Ray Bursts

    E-Print Network [OSTI]

    Raul Jimenez; David Band; Tsvi Piran

    2001-03-16T23:59:59.000Z

    We determine the distribution of total energy emitted by gamma-ray bursts for bursts with fluences and distance information. Our core sample consists of eight bursts with BATSE spectra and spectroscopic redshifts. We extend this sample by adding four bursts with BATSE spectra and host galaxy R magnitudes. From these R magnitudes we calculate a redshift probability distribution; this method requires a model of the host galaxy population. From a sample of ten bursts with both spectroscopic redshifts and host galaxy R magnitudes (some do not have BATSE spectra) we find that the burst rate is proportional to the galaxy luminosity at the epoch of the burst. Assuming that the total energy emitted has a log-normal distribution, we find that the average emitted energy (assumed to be radiated isotropically) is $gamma iso} > = 1.3^{+1.2}_{-1.0} \\times 10^{53}$ ergs (for H$_0$ = 65 km s$^{-1}$ Mpc$^{-1}$, $\\Omega_m=0.3$ and $\\Omega_\\Lambda=0.7$); the distribution has a logarithmic width of $\\sigma_\\gamma=1.7^{+0.7}_{-0.3}$. The corresponding distribution of X-ray afterglow energy (for seven bursts) has $ = 4.0^{+1.6}_{-1.8} \\times 10^{51}$ergs and $\\sigma_X = 1.3^{+0.4}_{-0.3}$. For completeness, we also provide spectral fits for all bursts with BATSE spectra for which there were afterglow searches.

  5. Leak checker data logging system

    DOE Patents [OSTI]

    Gannon, Jeffrey C. (Arlington, TX); Payne, John J. (Waterman, IL)

    1996-01-01T23:59:59.000Z

    A portable, high speed, computer-based data logging system for field testing systems or components located some distance apart employs a plurality of spaced mass spectrometers and is particularly adapted for monitoring the vacuum integrity of a long string of a superconducting magnets such as used in high energy particle accelerators. The system provides precise tracking of a gas such as helium through the magnet string when the helium is released into the vacuum by monitoring the spaced mass spectrometers allowing for control, display and storage of various parameters involved with leak detection and localization. A system user can observe the flow of helium through the magnet string on a real-time basis hour the exact moment of opening of the helium input valve. Graph reading can be normalized to compensate for magnet sections that deplete vacuum faster than other sections between testing to permit repetitive testing of vacuum integrity in reduced time.

  6. Leak checker data logging system

    DOE Patents [OSTI]

    Gannon, J.C.; Payne, J.J.

    1996-09-03T23:59:59.000Z

    A portable, high speed, computer-based data logging system for field testing systems or components located some distance apart employs a plurality of spaced mass spectrometers and is particularly adapted for monitoring the vacuum integrity of a long string of a superconducting magnets such as used in high energy particle accelerators. The system provides precise tracking of a gas such as helium through the magnet string when the helium is released into the vacuum by monitoring the spaced mass spectrometers allowing for control, display and storage of various parameters involved with leak detection and localization. A system user can observe the flow of helium through the magnet string on a real-time basis hour the exact moment of opening of the helium input valve. Graph reading can be normalized to compensate for magnet sections that deplete vacuum faster than other sections between testing to permit repetitive testing of vacuum integrity in reduced time. 18 figs.

  7. The Energy Spectrum of TeV $\\Gamma$-Rays from the Crab Nebula as measured by the HEGRA system of imaging air Cherenkov telescopes

    E-Print Network [OSTI]

    Aharonian, F A; Barrio, J A; Bernlöhr, K; Bojahr, H; Calle, I; Contreras, J L; Cortina, J; Denninghoff, S; Fonseca, V; González, J C; Götting, N; Heinzelmann, G; Hemberger, M; Hermann, G; Heusler, A; Hofmann, W; Horns, D; Ibarra, Alejandro; Kankanyan, R; Kestel, M; Kettler, J; Köhler, C; Kohnle, A; Konopelko, A K; Kornmayer, H; Kranich, D; Krawczynski, H; Lampeitl, H; Lindner, A; Lorenz, E; Lucarelli, F; Magnussen, N; Mang, O; Meyer, H; Mirzoian, R M; Moralejo, A; Padilla, L; Panter, M; Plaga, R; Plyasheshnikov, A V; Prahl, J; Pühlhofer, G; Rauterberg, G; Röhring, A; Sahakian, V V; Samorski, M; Schilling, M; Schmele, D; Schröder, F; Stamm, W; Tluczykont, M; Völk, H J; Wiebel-Sooth, B; Wiedner, C A; Willmer, M; Wittek, W

    2000-01-01T23:59:59.000Z

    The Crab Nebula has been observed by the HEGRA (High-Energy Gamma-Ray Astronomy) stereoscopic system of imaging air Cherenkov telescopes (IACTs) for a total of about 200 hrs during two observational campaigns: from September 1997 to March 1998 and from August 1998 to April 1999. The recent detailed studies of system performance give an energy threshold and an energy resolution for gamma-rays of 500 GeV and ~ 18, respectively. The Crab energy spectrum was measured with the HEGRA IACT system in a very broad energy range up to 20 TeV, using observations at zenith angles up to 65 degrees. The Crab data can be fitted in the energy range from 1 to 20 TeV by a simple power-law, which yields dJg/dE = (2.79+/-0.02 +/- 0.5) 10^{-7} E^{-2.59 +/- 0.03 +/- 0.05}, ph m^{-2} s^{-1} TeV^{-1} The Crab Nebula energy spectrum, as measured with the HEGRA IACT system, agrees within 15 0n the absolute scale and within 0.1 units in the power law index with the latest measurements by the Whipple, CANGAROO and CAT groups, consistent ...

  8. Report of spectral gamma-ray surveys acquired for the 200-UP-1 project

    SciTech Connect (OSTI)

    Kos, S.E.

    1995-12-01T23:59:59.000Z

    Four (4) boreholes were surveyed for the 200-UP-1 project utilizing the high-purity germanium and sodium logging systems. The surveys were acquired during the period April-September, 1994. The objectives of the surveys were to identify the presence, species, and relative activities of man-made gamma-ray emitting radionuclides, and to use log data to correlate stratigraphic features between boreholes. No man-made radionuclides were detected in the subsurface below 2 feet in depth in any of the boreholes.

  9. Gamma-Ray Burst Lines

    E-Print Network [OSTI]

    Michael S. Briggs

    1999-10-20T23:59:59.000Z

    The evidence for spectral features in gamma-ray bursts is summarized. As a guide for evaluating the evidence, the properties of gamma-ray detectors and the methods of analyzing gamma-ray spectra are reviewed. In the 1980's, observations indicated that absorption features below 100 keV were present in a large fraction of bright gamma-ray bursts. There were also reports of emission features around 400 keV. During the 1990's the situation has become much less clear. A small fraction of bursts observed with BATSE have statistically significant low-energy features, but the reality of the features is suspect because in several cases the data of the BATSE detectors appear to be inconsistent. Furthermore, most of the possible features appear in emission rather than the expected absorption. Analysis of data from other instruments has either not been finalized or has not detected lines.

  10. Gamma Ray Bursts and CETI

    E-Print Network [OSTI]

    Frank D. Smith Jr

    1993-02-10T23:59:59.000Z

    Gamma ray burst sources are isotropically distributed. They could be located at distances $\\sim 1000$ AU. (Katz \\cite{JK92}) GRB signals have many narrow peaks that are unresolved at the millisecond time resolution of existing observations. \\cite{JK87} CETI could use stars as gravitational lenses for interstellar gamma ray laser beam communication. Much better time resolution of GRB signals could rule out (or confirm?) the speculative hypothesis that GRB = CETI.

  11. VERY HIGH ENERGY GAMMA RAY Tadashi KIFUNE

    E-Print Network [OSTI]

    Enomoto, Ryoji

    elementary particles as progenitor. The particle interaction includes also absorption of gamma rays through the present time. Detection of the relics of the earlier Universe, such as gamma rays from anti­based tech­ nique to detect TeV gamma rays. The current status of gamma ray astronomy in its growing stage

  12. VERY HIGH ENERGY GAMMA RAY Tadashi KIFUNE

    E-Print Network [OSTI]

    Enomoto, Ryoji

    particles as progenitor. The particle interaction includes also absorption of gamma rays through the process to detect TeV gamma rays. The current status of gamma ray astronomy in its growing stage is demonstrated of observation 2. Ground-based detection of VHE gamma rays from SN 1006 and Markaraina 501 The review of gamma

  13. Gamma ray bursts ROBERT S MACKAY

    E-Print Network [OSTI]

    Rourke, Colin

    Gamma ray bursts ROBERT S MACKAY COLIN ROURKE We propose that a gamma ray burst is a kinematic Gamma ray bursts are intense flashes of electromagnetic radiation of cosmic origin lasting from ten accepted mechanism. We propose that a gamma ray burst is simply a kinematic effect, namely the effect

  14. Gamma ray shielding and structural properties of Bi{sub 2}O{sub 3}?PbO?B{sub 2}O{sub 3}?V{sub 2}O{sub 5} glass system

    SciTech Connect (OSTI)

    Kaur, Kulwinder, E-mail: kanwarjitsingh@yahoo.com; Singh, K. J., E-mail: kanwarjitsingh@yahoo.com; Anand, Vikas, E-mail: kanwarjitsingh@yahoo.com [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

    2014-04-24T23:59:59.000Z

    The present work has been undertaken to evaluate the applicability of Bi{sub 2}O{sub 3}?PbO?B{sub 2}O{sub 3}?V{sub 2}O{sub 5} glass system as gamma ray shielding material. Gamma ray mass attenuation coefficient has been determined theoretically using WinXcom computer software developed by National Institute of Standards and Technology. A meaningful comparison of their radiation shielding properties has been made in terms of their half value layer parameter with standard radiation shielding concrete 'barite'. Structural properties of the prepared glass system have been investigated in terms of XRD and FTIR techniques in order to check the possibility of their commercial utility as alternate to conventional concrete for gamma ray shielding applications.

  15. The Universe Viewed in Gamma-Rays 1 Concept of new gamma ray detector

    E-Print Network [OSTI]

    Enomoto, Ryoji

    a sensitivity of a detector at TeV gamma ray range. This method was used for a non-imaging detector as XrayThe Universe Viewed in Gamma-Rays 1 Concept of new gamma ray detector Satoko Osone Institute Abstract We present a concept of a new gamma ray detector in order to observe undetected TeV gamma ray

  16. Gamma-RayGamma-Ray Bursts: from SwiftBursts: from Swift

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Gamma-RayGamma-Ray Bursts: from SwiftBursts: from Swift to GLASTto GLAST Bing ZhangBing ZhangGehrels, et al), et al) #12;Gamma-ray bursts: the mostGamma-ray bursts: the most violent explosions fireball central photosphere internal external shocks engine (shocks) (reverse) (forward) gamma-ray UV

  17. Environmental measurement-while-drilling-gamma ray spectrometer (EMWD-GRS) system technology demonstration plan for use at the Savannah River Site F-Area Retention Basin

    SciTech Connect (OSTI)

    Williams, C.V.; Lockwood, G.J.; Normann, R.A. [Sandia National Labs., Albuquerque, NM (United States)] [Sandia National Labs., Albuquerque, NM (United States); Gruebel, R.D. [Tech Reps, Inc., Albuquerque, NM (United States)] [Tech Reps, Inc., Albuquerque, NM (United States)

    1996-08-01T23:59:59.000Z

    The Environmental Measurement-While-Drilling-Gamma Ray Spectrometer (EMWD-GRS) system represents an innovative blend of new and existing technology that provides the capability of producing real-time environmental and drillbit data during drilling operations. This demonstration plan presents information on the EMWD-GRS technology, demonstration design, Cs-137 contamination at the Savannah River Site F-Area Retention Basin, responsibilities of demonstration participants, and the policies and procedures for the demonstration to be conducted at the Savannah River Site F-Area Retention Basin. The EMWD-GRS technology demonstration will consist of continuously monitoring for gamma-radiation contamination while drilling two horizontal boreholes below the backfilled retention basin. These boreholes will pass near previously sampled vertical borehole locations where concentrations of contaminant levels are known. Contaminant levels continuously recorded by the EMWD-GRS system during drilling will be compared to contaminant levels previously determined through quantitative laboratory analysis of soil samples.

  18. Fissile interrogation using gamma rays from oxygen

    DOE Patents [OSTI]

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

    2004-04-20T23:59:59.000Z

    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.

  19. And the remaining 22 photons: The development of gamma ray and gamma ray burst astronomy

    E-Print Network [OSTI]

    Trimble, V

    2005-01-01T23:59:59.000Z

    goblins and cosmic gamma ray bursts. Astrophysics and Spacelinear alignments of gamma-ray burst sources. Journal of theE.E. (eds. ), 1992. Gamma Ray Bursts. Cambridge, Cambridge

  20. Real time gamma-ray signature identifier

    DOE Patents [OSTI]

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

    2012-05-15T23:59:59.000Z

    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.

  1. Neutrinos from Gamma Ray Bursts

    E-Print Network [OSTI]

    F. Halzen; G. Jaczko

    1996-02-07T23:59:59.000Z

    We show that the detection of neutrinos from a typical gamma ray burst requires a kilometer-scale detector. We argue that large bursts should be visible with the neutrino telescopes under construction. We emphasize the 3 techniques by which neutrino telescopes can perform this search: by triggering on i) bursts of muons from muon neutrinos, ii) muons from air cascades initiated by high energy gamma rays and iii) showers made by relatively low energy ($\\simeq 100\\,\\mev$) electron neutrinos. Timing of neutrino-photon coincidences may yield a measurement of the neutrino mass to order $10^{-5}$~eV, an interesting range in light of the solar neutrino anomaly.

  2. Gamma-ray emission from binaries in context

    E-Print Network [OSTI]

    Dubus, Guillaume

    2015-01-01T23:59:59.000Z

    More than a dozen binary systems are now established as sources of variable, high energy (HE, 0.1-100 GeV) gamma rays. Five are also established sources of very high energy (VHE, >100 GeV) gamma rays. The mechanisms behind gamma-ray emission in binaries are very diverse. My current understanding is that they divide up into four types of systems: gamma-ray binaries, powered by pulsar rotation; microquasars, powered by accretion onto a black hole or neutron star; novae, powered by thermonuclear runaway on a white dwarf; colliding wind binaries, powered by stellar winds from massive stars. Some of these types had long been suspected to emit gamma rays (microquasars), others have taken the community by surprise (novae). My purpose here is to provide a brief review of the current status of gamma-ray emission from binaries, in the context of related objects where similar mechanisms are at work (pulsar wind nebulae, active galactic nuclei, supernova remnants).

  3. Response transforms from comparative study of commercial pulsed-neutron-capture logging systems

    SciTech Connect (OSTI)

    Salaita, G.N. (Chevron Oil Field Research Co., La Habra, CA (United States))

    1992-09-01T23:59:59.000Z

    This paper reports that three generations of Schlumberger's Thermal Decay Time (TDT{sup SM}) logging devices - viz., TDT-K, TDT-M, and TDT-P - along with an Atlas Wireline PDK-100{sup SM} system were run in a Saudi Aramco well. The wellbore (8 1/2 in. with 7-in. casing) penetrated a sequence of clean sand, shaly sand, and shale streaks as exhibited by the openhole natural gamma ray log. The initial wellbore fluid was diesel. The fluid was then changed to brines of 42,000 and 176,000 ppm NaCl, respectively. Three repeat passes at a logging speed of 900 ft/hr were obtained by each device for each borehole liquid. As a result of this extensive comparative study, a set of departure curves and mathematical transforms was developed primarily for standardizing the various Schlumberger tools to a common reference logging system and/or borehole environment. The transforms were used beneficially to determine residual oil saturation (ROS) from time-lapse logs in a Saudi Aramco reservoir.

  4. Coal-log pipeline system development

    SciTech Connect (OSTI)

    Liu, H.

    1991-12-01T23:59:59.000Z

    Project tasks include: (1) Perform the necessary testing and development to demonstrate that the amount of binder in coal logs can be reduced to 8% or lower to produce logs with adequate strength to eliminate breakage during pipeline transportation, under conditions experienced in long distance pipeline systems. Prior to conducting any testing and demonstration, grantee shall perform an information search and make full determination of all previous attempts to extrude or briquette coal, upon which the testing and demonstration shall be based. (2) Perform the necessary development to demonstrate a small model of the most promising injection system for coal-logs, and tests the logs produced. (3) Conduct economic analysis of coal-log pipeline, based upon the work to date. Refine and complete the economic model. (VC)

  5. Light Curves of Swift Gamma Ray Bursts

    E-Print Network [OSTI]

    Paolo Cea

    2006-09-22T23:59:59.000Z

    Recent observations from the Swift gamma-ray burst mission indicate that a fraction of gamma ray bursts are characterized by a canonical behaviour of the X-ray afterglows. We present an effective theory which allows us to account for X-ray light curves of both (short - long) gamma ray bursts and X-ray rich flashes. We propose that gamma ray bursts originate from massive magnetic powered pulsars.

  6. Pulsed Gamma-Ray-Burst Afterglows

    E-Print Network [OSTI]

    J. Middleditch

    2009-01-01T23:59:59.000Z

    provides a candidate for the central engine of the gamma-ray burst (GRB) mechanism, both long and short

  7. The Universe Viewed in Gamma-Rays 1 Properties of Gamma-ray Bursts Localized by

    E-Print Network [OSTI]

    Enomoto, Ryoji

    The Universe Viewed in Gamma-Rays 1 Properties of Gamma-ray Bursts Localized by the HETE-2 and localize Gamma-ray bursts (GRBs) in wide field of view. HETE-2 have been localized about 20 GRBs per year hours after the burst. 1. The High Energy Transient Explorer 2 Gamma-ray burst (GRB) is the most

  8. The Diverse Environments of Gamma-Ray Bursts

    E-Print Network [OSTI]

    Perley, Daniel Alan

    2011-01-01T23:59:59.000Z

    Galaxies of Dark Gamma-Ray Bursts: Observational Constraintsof a Very Bright Gamma- Ray Burst in a Galactic Halo 3.11.3 Gamma-Ray Burst Classi?cation . . . . . . 1.4 Gamma-Ray

  9. Neutrinos from Gamma Ray Bursts

    E-Print Network [OSTI]

    Karl Mannheim

    2000-10-18T23:59:59.000Z

    The observed fluxes of cosmic rays and gamma rays are used to infer the maximum allowed high-energy neutrino flux allowed for Gamma Ray Bursts (GRBs), following Mannheim, Protheroe, and Rachen (2000). It is shown that if GRBs produce the ultrahigh-energy cosmic rays, they should contribute (a) at least 10% of the extragalactic gamma ray background between 3 MeV and 30 GeV, contrary to their observed energy flux which is only a minute fraction of this flux, and (b) a cumulative neutrino flux a factor of 20 below the AMANDA (Neutrino 2000) limit on isotropic neutrinos. This could have two implications, either GRBs do not produce the ultrahigh energy cosmic rays or that the GRBs are strongly beamed and emit most of their power at energies well above 100 GeV implausibly increasing the energy requirements, but consistent with the marginal detections of a few low-redshift GRBs by MILAGRITO, HEGRA-AIROBICC, and the Tibet-Array. All crucial measurements to test the models will be available in the next few years. These are measurements of (i) high-energy neutrinos with AMANDA-ICECUBE or an enlarged ANTARES/NESTOR ocean detector, (ii) GRB redshifts from HETE-2 follow-up studies, and (iii) GRB spectra above 10 GeV with low-threshold imaging air Cherenkov telescopes such as MAGIC and the space telescopes AGILE and GLAST.

  10. Gamma-Ray Bursts observed by INTEGRAL

    E-Print Network [OSTI]

    S. Mereghetti

    2003-12-12T23:59:59.000Z

    During the first six months of operations, six Gamma Ray Bursts (GRBs) have been detected in the field of view of the INTEGRAL instruments and localized by the INTEGRAL Burst Alert System (IBAS): a software for the automatic search of GRBs and the rapid distribution of their coordinates. I describe the current performances of IBAS and review the main results obtained so far. The coordinates of the latest burst localized by IBAS, GRB 031203, have been distributed within 20 s from the burst onset and with an uncertainty radius of only 2.7 arcmin.

  11. Gamma Ray Burst Central Engines

    E-Print Network [OSTI]

    Todd A. Thompson

    2008-07-04T23:59:59.000Z

    I review aspects of the theory of long-duration gamma-ray burst (GRB) central engines. I focus on the requirements of any model; these include the angular momentum of the progenitor, the power, Lorentz factor, asymmetry, and duration of the flow, and both the association and the non-association with bright supernovae. I compare and contrast the collapsar and millisecond proto-magnetar models in light of these requirements. The ability of the latter model to produce a flow with Lorentz factor ~100 while simultaneously maintaining a kinetic luminosity of ~10^50 ergs/s for a timescale of ~10-100 s is emphasized.

  12. Black Stars and Gamma Ray Bursts

    E-Print Network [OSTI]

    Tanmay Vachaspati

    2007-06-08T23:59:59.000Z

    Stars that are collapsing toward forming a black hole but are frozen near the Schwarzschild horizon are termed ``black stars''. Collisions of black stars, in contrast to black hole collisions, may be sources of gamma ray bursts, whose basic parameters are estimated quite simply and are found to be consistent with observed gamma ray bursts. Black star gamma ray bursts should be preceded by gravitational wave emission similar to that from the coalescence of black holes.

  13. High energy gamma rays from old accreting neutron stars

    E-Print Network [OSTI]

    P. Blasi

    1996-06-28T23:59:59.000Z

    We consider a magnetized neutron star with accretion from a companion star or a gas cloud around it, as a possible source of gamma rays with energy between $100$ $MeV$ and $10^{14}-10^{16}~eV$. The flow of the accreting plasma is terminated by a shock at the Alfv\\'en surface. Such a shock is the site for the acceleration of particles up to energies of $\\sim 10^{15}-10^{17}~eV$; gamma photons are produced in the inelastic $pp$ collisions between shock-accelerated particles and accreting matter. The model is applied to old neutron stars both isolated or in binary systems. The gamma ray flux above $100~MeV$ is not easily detectable, but we propose that gamma rays with very high energy could be used by Cherenkov experiments as a possible signature of isolated old neutron stars in dense clouds in our galaxy.

  14. Pulsed Photofission Delayed Gamma Ray Detection for Nuclear Material Identification

    SciTech Connect (OSTI)

    John Kavouras; Xianfei Wen; Daren R. Norman; Dante R. Nakazawa; Haori Yang

    2012-11-01T23:59:59.000Z

    Innovative systems with increased sensitivity and resolution are in great demand to detect diversion and to prevent misuse in support of nuclear materials management for the U.S. fuel cycle. Nuclear fission is the most important multiplicative process involved in non-destructive active interrogation. This process produces the most easily recognizable signature for nuclear materials. High-energy gamma rays can also excite a nucleus and cause fission through a process known as photofission. After photofission reactions, delayed signals are easily distinguishable from the interrogating radiation. Linac-based, advanced inspection techniques utilizing the fission signals after photofission have been extensively studied for homeland security applications. Previous research also showed that a unique delayed gamma ray energy spectrum exists for each fissionable isotope. Isotopic composition measurement methods based on delayed gamma ray spectroscopy will be the primary focus of this work.

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

    DOE Patents [OSTI]

    Hartwell, Jack K. (Idaho Falls, ID); Goodwin, Scott G. (Idaho Falls, ID); Johnson, Larry O. (Blackfoot, ID); Killian, E. Wayne (Idahoe Falls, ID)

    1990-01-01T23:59:59.000Z

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

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

    E-Print Network [OSTI]

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

    2014-03-28T23:59:59.000Z

    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.

  17. CONSTRAINTS ON VERY HIGH ENERGY GAMMA-RAY EMISSION FROM GAMMA-RAY BURSTS R. Atkins,1,2

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    CONSTRAINTS ON VERY HIGH ENERGY GAMMA-RAY EMISSION FROM GAMMA-RAY BURSTS R. Atkins,1,2 W. Benbow,3 emission from gamma-ray bursts (GRBs) during the prompt emission phase. Detection of >100 GeV counterparts on potential GRB models. Subject headinggs: gamma rays: bursts -- gamma rays: observations 1. INTRODUCTION

  18. Gamma-ray Bursts and their Central Engines

    E-Print Network [OSTI]

    Stephan Rosswog

    2004-01-09T23:59:59.000Z

    Gamma-ray bursts are the most luminous and probably the most relativistic events in the universe. The last few years have seen a tremendous increase in our knowledge of these events, but the source of the bursts still remains elusive. I will summarise recent progress in this field with special emphasis on our understanding of the possible progenitor systems.

  19. The HAWC Gamma-Ray Observatory: Design, Calibration, and Operation

    E-Print Network [OSTI]

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

    2013-01-01T23:59:59.000Z

    The High-Altitude Water Cherenkov Gamma Ray Observatory (HAWC) is under construction 4100 meters above sea level at Sierra Negra, Mexico. We describe the design and cabling of the detector, the characterization of the photomultipliers, and the timing calibration system. We also outline a next-generation detector based on the water Cherenkov technique.

  20. Observations of Gamma-Ray Bursts at Extreme Energies

    E-Print Network [OSTI]

    Aune, Taylor

    2012-01-01T23:59:59.000Z

    of Gamma-Ray Bursts . . . . . . . . . . . . . Redshift-CRUZ OBSERVATIONS OF GAMMA-RAY BURSTS AT EXTREME ENERGIES ADedication xix Acknowledgments xx 1 Gamma-Ray Bursts 1.1

  1. A history of gamma ray bursts and other astronomical conundrums

    E-Print Network [OSTI]

    Trimble, V

    2006-01-01T23:59:59.000Z

    V. Trimble, in “Gamma Ray Bursts: 30 Years of Discovery,”V. Trimble, in “Gamma Ray Bursts,” Ed. C. Ho et al. ,A History of Gamma Ray Bursts and Other Astronomical

  2. X- and Gamma-Ray Flashes from Type Ia Supernovae?

    E-Print Network [OSTI]

    Hoflich, Peter

    2009-01-01T23:59:59.000Z

    We investigate two potential mechanisms that will produce X-ray and gamma-ray flashes from Type Ia supernovae (SN-Ia). The mechanisms are the breakout of the thermonuclear burning front as it reaches the surface of the white dwarf and the interaction of the rapidly expanding envelope with an accretion disk. Based on the delayed-detonation scenario and detailed radiation-hydro calculation which include nuclear networks, we find that both mechanisms produce ~1 second flashes of high energy radiation with peak luminosities of 10^48 to 10^50 erg/sec with fast rises and exponential declines. The X- and gamma-ray visibility of a SN-Ia will depend strongly on self absorption within the progenitor system, specifically on the properties of the accretion disk and its orientation towards the observer. Such X-ray and gamma-ray flashes could be detected as triggered events by Gamma-Ray Burst (GRB) detectors on satellites, with events in current GRB catalogs. We have searched through the GRB catalogs (for the BATSE, HETE, ...

  3. Gamma-Ray Bursts and Particle Astrophysics

    E-Print Network [OSTI]

    B. Gendre

    2008-07-24T23:59:59.000Z

    Gamma-ray bursts are violent events occurring randomly in the sky. In this review, I will present the fireball model, proposed to explain the phenomenon of gamma-ray bursts. This model has important consequences for the production and observation at Earth of gravitational waves, high energy neutrinos, cosmic rays and high energy photons, and the second part of this review will be focused on these aspects. A last section will briefly discuss the topic of the use of gamma-ray bursts as standard candles and possible cosmological studies.

  4. Achievements in testing of the MGA and FRAM isotopic software codes under the DOE/NNSA-IRSN cooperation of gamma-ray isotopic measurement systems

    SciTech Connect (OSTI)

    Vo, Duc [Los Alamos National Laboratory; Wang, Tzu - Fang [LLNL; Funk, Pierre [IRSN; Weber, Anne - Laure [IRSN; Pepin, Nicolas [IRSN; Karcher, Anna [IRSN

    2009-01-01T23:59:59.000Z

    DOE/NNSA and IRSN collaborated on a study of gamma-ray instruments and analysis methods used to perform isotopic measurements of special nuclear materials. The two agencies agreed to collaborate on the project in response to inconsistencies that were found in the various versions of software and hardware used to determine the isotopic abundances of uranium and plutonium. IRSN used software developed internally to test the MGA and FRAM isotopic analysis codes for criteria used to stop data acquisition. The stop-criterion test revealed several unusual behaviors in both the MGA and FRAM software codes.

  5. Gamma-ray Burst Cosmology

    E-Print Network [OSTI]

    Wang, F Y; Liang, E W

    2015-01-01T23:59:59.000Z

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

  6. Gravitational waves and gamma-ray bursts

    E-Print Network [OSTI]

    Alessandra Corsi; for the LIGO Scientific Collaboration; for the Virgo Collaboration

    2012-05-11T23:59:59.000Z

    Gamma-Ray Bursts are likely associated with a catastrophic energy release in stellar mass objects. Electromagnetic observations provide important, but indirect information on the progenitor. On the other hand, gravitational waves emitted from the central source, carry direct information on its nature. In this context, I give an overview of the multi-messenger study of gamma-ray bursts that can be carried out by using electromagnetic and gravitational wave observations. I also underline the importance of joint electromagnetic and gravitational wave searches, in the absence of a gamma-ray trigger. Finally, I discuss how multi-messenger observations may probe alternative gamma-ray burst progenitor models, such as the magnetar scenario.

  7. Studying Gamma Ray Bursts from a

    E-Print Network [OSTI]

    ?umer, Slobodan

    Studying Gamma Ray Bursts from a new perspective! {... Unraveling some mysteries and adding new Radio Op0cal X-ray Short ( energy -ray photons... ... accompained by a considerable long las0ng emission

  8. Can gamma-ray bursts constrain quintessence?

    E-Print Network [OSTI]

    T. Di Girolamo; R. Catena; M. Vietri; G. Di Sciascio

    2005-04-27T23:59:59.000Z

    Using the narrow clustering of the geometrically corrected gamma-ray energies released by gamma-ray bursts, we investigate the possibility of using these sources as standard candles to probe cosmological parameters such as the matter density Omega_m and the cosmological constant energy density Omega_Lambda. By simulating different samples of gamma-ray bursts, we find that Omega_m can be determined with accuracy ~7% with data from 300 sources. We also show that, if Omega = 1 is due to a quintessence field, some of the models proposed in the literature may be discriminated from a Universe with cosmological constant, by a similar-sized sample of gamma-ray bursts.

  9. Gamma-Ray Pulsar Studies With GLAST

    SciTech Connect (OSTI)

    Thompson, D.J.; /NASA, Goddard

    2011-11-23T23:59:59.000Z

    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.

  10. Thermal neutron capture gamma-rays

    SciTech Connect (OSTI)

    Tuli, J.K.

    1983-01-01T23:59:59.000Z

    The energy and intensity of gamma rays as seen in thermal neutron capture are presented. Only those (n,..cap alpha..), 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,..gamma..) reaction given in the order of increasing energy; the Table II lists the gamma rays according to the nuclide.

  11. Mining Gamma-Ray Burst Data

    E-Print Network [OSTI]

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

    2000-11-30T23:59:59.000Z

    Gamma-ray bursts provide what is probably one of the messiest of all astrophysical data sets. Burst class properties are indistinct, as overlapping characteristics of individual bursts are convolved with effects of instrumental and sampling biases. Despite these complexities, data mining techniques have allowed new insights to be made about gamma-ray burst data. We demonstrate how data mining techniques have simultaneously allowed us to learn about gamma-ray burst detectors and data collection, cosmological effects in burst data, and properties of burst subclasses. We discuss the exciting future of this field, and the web-based tool we are developing (with support from the NASA AISR Program). We invite others to join us in AI-guided gamma-ray burst classification (http://grb.mnsu.edu/grb/).

  12. Gamma Ray Bursts from Ordinary Cosmic Strings

    E-Print Network [OSTI]

    R. H. Brandenberger; A. T. Sornborger; M. Trodden

    1993-02-12T23:59:59.000Z

    We give an upper estimate for the number of gamma ray bursts from ordinary (non-superconducting) cosmic strings expected to be observed at terrestrial detectors. Assuming that cusp annihilation is the mechanism responsible for the bursts we consider strings arising at a GUT phase transition and compare our estimate with the recent BATSE results. Further we give a lower limit for the effective area of future detectors designed to detect the cosmic string induced flux of gamma ray bursts.

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

    E-Print Network [OSTI]

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

    2013-01-01T23:59:59.000Z

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

  14. Results from the Milagro Gamma-Ray Observatory

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    V energies, and a search for transient emission above 100 GeV from gamma-ray bursts. 1 Introduction remnants and gamma-ray bursts (GRB). Gamma rays are also produced when high-energy cosmic rays interactResults from the Milagro Gamma-Ray Observatory E. Blaufuss for the Milagro Collaboration a,1 , a

  15. Gamma-ray Albedo of the Moon

    SciTech Connect (OSTI)

    Moskalenko, Igor V.; Porter, Troy A.

    2007-06-14T23:59:59.000Z

    We use the GEANT4 Monte Carlo framework to calculate the gamma-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of gamma-rays from the Moon is very steep with an effective cutoff around 3 GeV (600 MeV for the inner part of the Moon disc). Since it is the only (almost) black spot in the gamma-ray sky, it provides a unique opportunity for calibration of gamma-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). The albedo flux depends on the incident CR spectrum which changes over the solar cycle. Therefore, it is possible to monitor the CR spectrum using the albedo gamma-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo -rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the GLAST LAT to monitor the CR spectrum near the Earth beyond the lifetime of PAMELA.

  16. The Universe Viewed in Gamma-Rays 1 Toward Ultra Short Gamma Ray Burst Ground Based De-

    E-Print Network [OSTI]

    Enomoto, Ryoji

    The Universe Viewed in Gamma-Rays 1 Toward Ultra Short Gamma Ray Burst Ground Based De- tection- liminary data taking started in November 2002. 1. Introduction Gamma-ray bursts observed with space Tcherenkovlightfromoneshower Few 100MeV gamma-rays Fig. 1. In an imaging telescope, -ray bursts should appear as a Cherenkov

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

    E-Print Network [OSTI]

    Leonov, A A; Bonvicini, V; Topchiev, N P; Adriani, O; Aptekar, R L; Arkhangelskaja, I V; Arkhangelskiy, A I; Bergstrom, L; Berti, E; Bigongiari, G; Bobkov, S G; Boezio, M; Bogomolov, E A; Bonechi, S; Bongi, M; Bottai, S; Castellini, G; Cattaneo, P W; Cumani, P; Dedenko, G L; De Donato, C; Dogiel, V A; Gorbunov, M S; Gusakov, Yu V; Hnatyk, B I; Kadilin, V V; Kaplin, V A; Kaplun, A A; Kheymits, M D; Korepanov, V E; Larsson, J; Loginov, V A; Longo, F; Maestro, P; Marrocchesi, P S; Mikhailov, V V; Mocchiutti, E; Moiseev, A A; Mori, N; Moskalenko, I V; Naumov, P Yu; Papini, P; Pearce, M; Picozza, P; Popov, A V; Rappoldi, A; Ricciarini, S; Runtso, M F; Ryde, F; Serdin, O V; Sparvoli, R; Spillantini, P; Suchkov, S I; Tavani, M; Taraskin, A A; Tiberio, A; Tyurin, E M; Ulanov, M V; Vacchi, A; Vannuccini, E; Vasilyev, G I; Yurkin, Yu T; Zampa, N; Zirakashvili, V N; Zverev, V G

    2015-01-01T23:59:59.000Z

    The GAMMA-400 gamma-ray telescope is intended to measure the fluxes of gamma rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. Such measurements concern with the following scientific goals: search for signatures of dark matter, investigation of gamma-ray point and extended sources, studies of the energy spectra of Galactic and extragalactic diffuse emission, studies of gamma-ray bursts and gamma-ray emission from the active Sun, as well as high-precision measurements of spectra of high-energy electrons and positrons, protons, and nuclei up to the knee. The main components of cosmic rays are protons and helium nuclei, whereas the part of lepton component in the total flux is ~10E-3 for high energies. In present paper, the capability of the GAMMA-400 gamma-ray telescope to distinguish electrons and positrons from protons in cosmic rays is investigated. The individual contribution to the proton rejection is studied for each detector system of the GAMMA-400 gamma-ray tel...

  18. Short Gamma-Ray Bursts from Binary Neutron Star Mergers

    E-Print Network [OSTI]

    Roland Oechslin; Thomas Janka

    2006-04-27T23:59:59.000Z

    We present the results from new relativistic hydrodynamic simulations of binary neutron star mergers using realistic non-zero temperature equations of state. We vary several unknown parameters in the system such as the neutron star (NS) masses, their spins and the nuclear equation of state. The results are then investigated with special focus on the post-merger torus-remnant system. Observational implications on the Gamma-ray burst (GRB) energetics are discussed and compared with recent observations.

  19. Solar Gamma Rays Powered by Secluded Dark Matter

    E-Print Network [OSTI]

    Brian Batell; Maxim Pospelov; Adam Ritz; Yanwen Shang

    2009-10-08T23:59:59.000Z

    Secluded dark matter models, in which WIMPs annihilate first into metastable mediators, can present novel indirect detection signatures in the form of gamma rays and fluxes of charged particles arriving from directions correlated with the centers of large astrophysical bodies within the solar system, such as the Sun and larger planets. This naturally occurs if the mean free path of the mediator is in excess of the solar (or planetary) radius. We show that existing constraints from water Cerenkov detectors already provide a novel probe of the parameter space of these models, complementary to other sources, with significant scope for future improvement from high angular resolution gamma-ray telescopes such as Fermi-LAT. Fluxes of charged particles produced in mediator decays are also capable of contributing a significant solar system component to the spectrum of energetic electrons and positrons, a possibility which can be tested with the directional and timing information of PAMELA and Fermi.

  20. NEUTRON AND GAMMA RAY DETECTION FOR BORDER SECURITY APPLICATIONS

    SciTech Connect (OSTI)

    Kouzes, Richard T.

    2010-05-21T23:59:59.000Z

    Countries around the world are deploying radiation detection instrumentation to interdict the illegal shipment of radioactive material crossing international borders. These efforts include deployments in the U.S. and in a number of other countries by governments and international organizations. Most deployed radiation portal monitor systems are based on plastic scintillator for gamma-ray detection and 3He tubes for neutron detection. The approach to this homeland security application, and lessons learned, are discussed.

  1. Propagation of very high energy gamma-rays inside massive binaries LS 5039 and LSI +61 303

    E-Print Network [OSTI]

    W. Bednarek

    2006-01-28T23:59:59.000Z

    It is expected that high energy gamma-rays, if injected relatively close to the massive stars in binary systems LS 5039 and LSI 61 3003, should be strongly absorbed, initiating inverse Compton $e^\\pm$ pair cascades in the anisotropic radiation from stellar surfaces. We investigate influence of the propagation effects on the spectral and angular features of the gamma-ray spectra emerging from these two binary systems by applying the Monte Carlo method. Two different hypothesis are considered: isotropic injection of primary gamma-rays with the power law spectrum and electrons. It is concluded that propagation effects of gamma-rays can be responsible for the spectral features observed from LS 5039. The cascade processes occurring inside these binary systems significantly reduce the gamma-ray opacity obtained in other works by simple calculations of the escape of gamma-rays from the radiation fields of the massive stars. Both systems provide very similar conditions for the TeV gamma-ray production at the periastron passage. Any TeV gamma-ray flux at the apastron passage in LSI +61 303 will be relatively stronger with respect to its GeV flux than in LS 5039. If gamma-rays are produced inside these binaries not far from the massive stars, i.e. within a few stellar radii, then clear anticorrelation between the GeV and TeV emission should be observed, provided that primary gamma-rays at GeV and TeV energies are produced in the same process by the same population of relativistic particles. These gamma-ray propagation features can be tested in the near future by the multi-wavelength campaigns engaging the AGILE and GLAST telescopes and the Cherenkov telescopes (e.g. MAGIC, HESS, VERITAS and CANGAROO).

  2. Planetary Produced Axionlike Particles and Gamma-Ray Flashes

    SciTech Connect (OSTI)

    Liolios, Anastasios [Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2008-12-24T23:59:59.000Z

    Axion-like particles could be created in nuclear disintegrations and deexitations of natural radionuclides present in the interior of the planets. For the Earth and the other planets with a surrounding magnetosphere, axion production could result to gamma and X-ray emission, originating from axion to photon conversion in the planetary magnetic fields. The estimated planetary axion fluxes as well as the related gamma ray fluxes from Earth and the giant planets of our solar system are given along with the axion coupling to ordinary matter. A possible connection with the enigmatic Terrestrial Gamma-ray Flashes (TGFs) discovered in 1994 by CGRO/BATSE and also detected with the RHESSI satellite, is also discussed.

  3. Fermi Observations of Gamma-ray Bursts

    SciTech Connect (OSTI)

    Ohno, Masanori [Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)

    2010-10-15T23:59:59.000Z

    The gamma-ray emission mechanism of Gamma-ray bursts (GRBs) are still unknown. Fermi Gamma-ray Space Telescope successfully detected high-energy (> 100 MeV) emission from 17 GRBs since its launch. Fermi revealed the distinct temporal behaviors and extra spectral component from high-energy emission. These new observational results are driving many theoretical implications, such as leptonic, hadronic and afterglow origin. The highest energy photon detected by Fermi gives a constraint on the bulk Lorentz factor of the ultra-relativistic jets of GRBs. The impact of the Fermi GRB observations extends not only to the GRB-related issues but also to the outside GRB physics, such as quantum gravity and model of the extra galactic background light.

  4. A supersymmetric model of gamma ray bursts

    E-Print Network [OSTI]

    L. Clavelli; G. Karatheodoris

    2005-08-08T23:59:59.000Z

    We propose a model for gamma ray bursts in which a star subject to a high level of fermion degeneracy undergoes a phase transition to a supersymmetric state. The burst is initiated by the transition of fermion pairs to sfermion pairs which, uninhibited by the Pauli exclusion principle, can drop to the ground state of minimum momentum through photon emission. The jet structure is attributed to the Bose statistics of sfermions whereby subsequent sfermion pairs are preferentially emitted into the same state (sfermion amplification by stimulated emission). Bremsstrahlung gamma rays tend to preserve the directional information of the sfermion momenta and are themselves enhanced by stimulated emission.

  5. Redshift indicators for gamma-ray bursts

    E-Print Network [OSTI]

    J-L. Atteia

    2005-05-04T23:59:59.000Z

    The measure of the distances and luminosities of gamma-ray bursts (GRBs) led to the discovery that many GRB properties are strongly correlated with their intrinsic luminosity, leading to the construction of reliable luminosity indicators. These GRB luminosity indicators have quickly found applications, like the construction of 'pseudo-redshifts', or the measure of luminosity distances, which can be computed independently of the measure of the redshift. In this contribution I discuss various issues connected with the construction of luminosity-redshift indicators for gamma-ray bursts.

  6. Gamma-Ray Burst observations with Fermi

    E-Print Network [OSTI]

    Bissaldi, Elisabetta; Omodei, Nicola; Vianello, Giacomo; von Kienlin, Andreas

    2015-01-01T23:59:59.000Z

    After seven years of science operation, the Fermi mission has brought great advances in the study of Gamma-ray Bursts (GRBs). Over 1600 GRBs have been detected by the Gamma-ray Burst Monitor, and more than 100 of these are also detected by the Large Area Telescope above 30 MeV. We will give an overview of these observations, presenting the common properties in the GRB temporal and spectral behavior at high energies. We will also highlight the unique characteristics of some individual bursts. The main physical implications of these results will be discussed, along with open questions regarding GRB modeling in their prompt and temporally-extended emission phases.

  7. Gamma-Ray Bursts: Jets and Energetics

    E-Print Network [OSTI]

    D. A. Frail

    2003-11-12T23:59:59.000Z

    The relativistic outflows from gamma-ray bursts are now thought to be narrowly collimated into jets. After correcting for this jet geometry there is a remarkable constancy of both the energy radiated by the burst and the kinetic energy carried by the outflow. Gamma-ray bursts are still the most luminous explosions in the Universe, but they release energies that are comparable to supernovae. The diversity of cosmic explosions appears to be governed by the fraction of energy that is coupled to ultra-relativistic ejecta.

  8. Status of the Milagro $\\gamma$ Ray Observatory

    E-Print Network [OSTI]

    Atkins, R; Berley, D; Chen, M L; Coyne, D G; Delay, R S; Dingus, B L; Dorfan, D E; Ellsworth, R W; Evans, D; Falcone, A D; Fleysher, L; Fleysher, R; Gisler, G; Goodman, J A; Haines, T J; Hoffman, C M; Hugenberger, S; Kelley, L A; Leonor, I; Macri, J R; McConnell, M; McCullough, J F; McEnery, J E; Miller, R S; Mincer, A I; Morales, M F; Némethy, P; Ryan, J M; Schneider, M; Shen, B; Shoup, A L; Sinnis, G; Smith, A J; Sullivan, G W; Thompson, T N; Tümer, T O; Wang, K; Wascko, M O; Westerhoff, S; Williams, D A; Yang, T; Yodh, G B

    2001-01-01T23:59:59.000Z

    The Milagro Gamma Ray Observatory is the world's first large-area water Cherenkov detector capable of continuously monitoring the sky at TeV energies. Located in northern New Mexico, Milagro will perform an all sky survey of the Northern Hemisphere at energies between ~250 GeV and 50 TeV. With a high duty cycle, large detector area (~5000 square meters), and a wide field-of-view (~1 sr), Milagro is uniquely capable of searching for transient and DC sources of high-energy gamma-ray emission. Milagro has been operating since February, 1999. The current status of the Milagro Observatory and initial results will be discussed.

  9. Gamma Ray Bursts in the HAWC Era

    E-Print Network [OSTI]

    Mészáros, Peter; Murase, Kohta; Fox, Derek; Gao, He; Senno, Nicholas

    2015-01-01T23:59:59.000Z

    Gamma-Ray Bursts are the most energetic explosions in the Universe, and are among the most promising for detecting multiple non-electromagnetic signals, including cosmic rays, high energy neutrinos and gravitational waves. The multi-GeV to TeV gamma-ray range of GRB could have significant contributions from hadronic interactions, mixed with more conventional leptonic contributions. This energy range is important for probing the source physics, including overall energetics, the shock parameters and the Lorentz factor. We discuss some of the latest observational and theoretical developments in the field.

  10. Gamma Ray Bursts in the HAWC Era

    E-Print Network [OSTI]

    Peter Mészáros; Katsuaki Asano; Kohta Murase; Derek Fox; He Gao; Nicholas Senno

    2015-06-08T23:59:59.000Z

    Gamma-Ray Bursts are the most energetic explosions in the Universe, and are among the most promising for detecting multiple non-electromagnetic signals, including cosmic rays, high energy neutrinos and gravitational waves. The multi-GeV to TeV gamma-ray range of GRB could have significant contributions from hadronic interactions, mixed with more conventional leptonic contributions. This energy range is important for probing the source physics, including overall energetics, the shock parameters and the Lorentz factor. We discuss some of the latest observational and theoretical developments in the field.

  11. Status of the Milagro Gamma Ray Observatory

    E-Print Network [OSTI]

    R. Atkins; W. Benbow; D. Berley; M. -L. Chen; D. G. Coyne; R. S. Delay; B. L. Dingus; D. E. Dorfan; R. W. Ellsworth; D. Evans; A. Falcone; L. Fleysher; R. Fleysher; G. Gisler; J. A. Goodman; T. J. Haines; C. M. Hoffman; S. Hugenberger; L. A. Kelley; I. Leonor; J. Macri; M. McConnell; J. F. McCullough; J. E. McEnery; R. S. Miller; A. I. Mincer; M. F. Morales; P. Nemethy; J. M. Ryan; M. Schneider; B. Shen; A. Shoup; G. Sinnis; A. J. Smith; G. W. Sullivan; T. N. Thompson; O. T. Tumer; K. Wang; M. O. Wascko; S. Westerhoff; D. A. Williams; T. Yang; G. B. Yodh

    1999-06-24T23:59:59.000Z

    The Milagro Gamma Ray Observatory is the world's first large-area water Cherenkov detector capable of continuously monitoring the sky at TeV energies. Located in northern New Mexico, Milagro will perform an all sky survey of the Northern Hemisphere at energies between ~250 GeV and 50 TeV. With a high duty cycle, large detector area (~5000 square meters), and a wide field-of-view (~1 sr), Milagro is uniquely capable of searching for transient and DC sources of high-energy gamma-ray emission. Milagro has been operating since February, 1999. The current status of the Milagro Observatory and initial results will be discussed.

  12. Method for on-line evaluation of materials using prompt gamma ray analysis

    DOE Patents [OSTI]

    Akers, Douglas W. (Idaho Falls, ID)

    2009-12-08T23:59:59.000Z

    A method for evaluating a material specimen comprises: Mounting a neutron source and a detector adjacent the material specimen; bombarding the material specimen with neutrons from the neutron source to create prompt gamma rays within the material specimen, some of the prompt gamma rays being emitted from the material specimen, some of the prompt gamma rays resulting in the formation of positrons within the material specimen by pair production; collecting positron annihilation data by detecting with the detector at least one emitted annihilation gamma ray resulting from the annihilation of a positron; storing the positron annihilation data on a data storage system for later retrieval and processing; and continuing to collect and store positron annihilation data, the continued collected and stored positron annihilation data being indicative of an accumulation of lattice damage over time.

  13. Observation of the Crab Nebula in Soft Gamma Rays with the Nuclear Compton Telescope

    E-Print Network [OSTI]

    Bandstra, Mark ShenYu

    2010-01-01T23:59:59.000Z

    Gamma-ray bursts . . . . . . . . . . . . . . . . . . . 1.268] G. J. Fishman. The gamma-ray burst capabilities of BATSEOlson. Observations of Gamma- Ray Bursts of Cosmic Origin.

  14. Crystal diffraction lens telescope for focusing nuclear gamma rays

    SciTech Connect (OSTI)

    Smither, R.K.; Fernandez, P.B.; Graber, T. [Argonne National Lab., IL (United States). Advanced Photon Source; Ballmoos, P. von; Naya, J.; Albernhe, F.; Vedrenne, G. [Centre d`Etude Spatiale des Rayonnements, Toulouse (France); Faiz, M. [KFUPM, Dhahran (Saudi Arabia). Physics Dept.

    1996-08-01T23:59:59.000Z

    A crystal diffraction lens was constructed at Argonne National Laboratory for use as a telescope to focus nuclear gamma rays. It consisted of 600 single crystals of germanium arranged in 8 concentric rings. The mounted angle of each crystal was adjusted to intercept and diffract the incoming gamma rays with an accuracy of a few arc sec. The performance of the lens was tested in two ways. In one case, the gamma rays were focused on a single medium size germanium detector. In the second case, the gamma rays were focused on the central germanium detector of a 3 x 3 matrix of small germanium detectors. The efficiency, image concentration and image quality, and shape were measured. The tests performed with the 3 x 3 matrix detector system were particularly interesting. The wanted radiation was concentrated in the central detector. The 8 other detectors were used to detect the Compton scattered radiation, and their energy was summed with coincident events in the central detector. This resulted in a detector with the efficiency of a large detector (all 9 elements) and the background of a small detector (only the central element). The use of the 3 x 3 detector matrix makes it possible to tell if the source is off axis and, if so, to tell in which direction. The crystal lens acts very much like a simple convex lens for visible light. Thus if the source is off to the left then the image will focus off to the right illuminating the detector on the right side: telling one in which direction to point the telescope. Possible applications of this type of crystal lens to balloon and satellite experiments will be discussed.

  15. VERITAS OBSERVATIONS OF GAMMA-RAY BURSTS DETECTED BY SWIFT

    SciTech Connect (OSTI)

    Acciari, V. A.; Benbow, W. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Aliu, E.; Errando, M. [Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States); Arlen, T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Aune, T. [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Beilicke, M.; Buckley, J. H.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Bradbury, S. M. [School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT (United Kingdom); Byrum, K. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Cannon, A.; Collins-Hughes, E. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Cesarini, A.; Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Christiansen, J. L. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 94307 (United States); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Cui, W. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Duke, C. [Department of Physics, Grinnell College, Grinnell, IA 50112-1690 (United States); Falcone, A. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); and others

    2011-12-10T23:59:59.000Z

    We present the results of 16 Swift-triggered Gamma-ray burst (GRB) follow-up observations taken with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) telescope array from 2007 January to 2009 June. The median energy threshold and response time of these observations were 260 GeV and 320 s, respectively. Observations had an average duration of 90 minutes. Each burst is analyzed independently in two modes: over the whole duration of the observations and again over a shorter timescale determined by the maximum VERITAS sensitivity to a burst with a t{sup -1.5} time profile. This temporal model is characteristic of GRB afterglows with high-energy, long-lived emission that have been detected by the Large Area Telescope on board the Fermi satellite. No significant very high energy (VHE) gamma-ray emission was detected and upper limits above the VERITAS threshold energy are calculated. The VERITAS upper limits are corrected for gamma-ray extinction by the extragalactic background light and interpreted in the context of the keV emission detected by Swift. For some bursts the VHE emission must have less power than the keV emission, placing constraints on inverse Compton models of VHE emission.

  16. Ultrahigh Energy Cosmic Rays and Prompt TeV Gamma Rays from Gamma Ray Bursts

    E-Print Network [OSTI]

    Pijushpani Bhattacharjee; Nayantara Gupta

    2003-05-12T23:59:59.000Z

    Gamma Ray Bursts (GRBs) have been proposed as one {\\it possible} class of sources of the Ultrahigh Energy Cosmic Ray (UHECR) events observed up to energies $\\gsim10^{20}\\ev$. The synchrotron radiation of the highest energy protons accelerated within the GRB source should produce gamma rays up to TeV energies. Here we briefly discuss the implications on the energetics of the GRB from the point of view of the detectability of the prompt TeV gamma rays of proton-synchrotron origin in GRBs in the up-coming ICECUBE muon detector in the south pole.

  17. High redshift Gamma-Ray Bursts

    E-Print Network [OSTI]

    Salvaterra, R

    2015-01-01T23:59:59.000Z

    Ten years of operations of the Swift satellite have allow us to collect a small sample of long Gamma-Ray Bursts (GRBs) at redshift larger than six. I will review here the present status of this research field and discuss the possible use of GRBs as a fundamental new tool to explore the early Universe, complementary to quasar and galaxy surveys.

  18. Delayed Nickel Decay in Gamma Ray Bursts

    E-Print Network [OSTI]

    G. C. McLaughlin; R. A. M. J. Wijers

    2002-05-19T23:59:59.000Z

    Recently observed emission lines in the X-ray afterglow of gamma ray bursts suggest that iron group elements are either produced in the gamma ray burst, or are present nearby. If this material is the product of a thermonuclear burn, then such material would be expected to be rich in Nickel-56. If the nickel remains partially ionized, this prevents the electron capture reaction normally associated with the decay of Nickel-56, dramatically increasing the decay timescale. Here we examine the consequences of rapid ejection of a fraction of a solar mass of iron group material from the center of a collapsar/hypernova. The exact rate of decay then depends on the details of the ionization and therefore the ejection process. Future observations of iron, nickel and cobalt lines can be used to diagnose the origin of these elements and to better understand the astrophysical site of gamma ray bursts. In this model, the X-ray lines of these iron-group elements could be detected in suspected hypernovae that did not produce an observable gamma ray burst due to beaming.

  19. Gamma-Ray Pulsars: Models and Predictions

    E-Print Network [OSTI]

    Alice K. Harding

    2000-12-12T23:59:59.000Z

    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. Next-generation gamma-ray telescopes sensitive to GeV-TeV emission will provide critical tests of pulsar acceleration and emission mechanisms.

  20. Gamma-ray bursts: a Centauro's cry?

    E-Print Network [OSTI]

    Z. K. Silagadze

    2003-06-30T23:59:59.000Z

    A new candidate for the gamma-ray bursts central engine is proposed: if in some energetic cosmic event a macroscopic amount of bubbles of the disoriented chiral condensate can be formed, then their subsequent decays will produce a relativistic fireball without the baryon loading problem. The neutron star to strange star transition is considered as a candidate example of such cosmic event.

  1. Current segmented gamma-ray scanner technology

    SciTech Connect (OSTI)

    Bjork, C.W.

    1987-01-01T23:59:59.000Z

    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.

  2. PoGOLite -The Polarised Gamma-ray Observer

    E-Print Network [OSTI]

    Haviland, David

    PoGOLite - The Polarised Gamma-ray Observer CECILIA MARINI BETTOLO Licentiate Thesis Stockholm, Sweden 2008 #12;#12;Licentiate Thesis PoGOLite - The Polarised Gamma-ray Observer Cecilia Marini Bettolo

  3. Picture of the Week: Gamma-ray bursts, infographic

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    4 Gamma-ray bursts: infographic Gamma-ray bursts (GRBs) are the most powerful explosions in the universe. With the help of sophisticated instruments such as the ground based RAPTOR...

  4. Gamma-Ray Bursts, Ultra High Energy Cosmic Rays, and Cosmic Gamma-Ray Background

    E-Print Network [OSTI]

    Tomonori Totani

    1999-04-13T23:59:59.000Z

    We argue that gamma-ray bursts (GRBs) may be the origin of the cosmic gamma-ray background radiation observed in GeV range. It has theoretically been discussed that protons may carry a much larger amount of energy than electrons in GRBs, and this large energy can be radiated in TeV range by synchrotron radiation of ultra-high-energy protons (\\sim 10^{20} eV). The possible detection of GRBs above 10 TeV suggested by the Tibet and HEGRA groups also supports this idea. If this is the case, most of TeV gamma-rays from GRBs are absorbed in intergalactic fields and eventually form GeV gamma-ray background, whose flux is in good agreement with the recent observation.

  5. High Efficiency of Gamma-Ray Bursts Revisited

    E-Print Network [OSTI]

    Y. C. Zou A; Z. G. Dai B

    2007-01-01T23:59:59.000Z

    efficiency of gamma-ray bursts by assuming that the ejecta from the central engine are equally massive and

  6. Gamma-ray Sky Observed with Fermi Large Area Telescope

    E-Print Network [OSTI]

    Yamamoto, Hirosuke

    detection reported Flare activity reported via ATel Gamma Ray Bursts reported via GCN Giant MC imageGamma-ray Sky Observed with Fermi Large Area Telescope RESCEU Symposium on Astroparticle Physics) Measure the photon direction Identification of the gamma-ray shower 36 planes of Si strip detectors (228 m

  7. The Compton Effect--Compton Scattering and Gamma Ray Spectroscopy

    E-Print Network [OSTI]

    Dai, Pengcheng

    The Compton Effect-- Compton Scattering and Gamma Ray Spectroscopy by Dr. James E. Parks Department and procedures for measuring gamma-ray energy distributions, (7) to learn about photomultipliers the interactions of high energy, electromagnetic photon radiation with materials in general. Gamma rays are high

  8. The Biggest Bangs The Mystery of Gamma-Ray Bursts,

    E-Print Network [OSTI]

    Katz, Jonathan I.

    The Biggest Bangs The Mystery of Gamma-Ray Bursts, The Most Violent Explosions in The Universe J. I a Gamma-Ray Burst Kill the Dinosaurs? Will a Burst Kill Us? · Glossary · Sources · Index viii #12;Chapter of these four cameras recorded visible light from a gamma-ray burst as it was happening, which had been the holy

  9. Gamma-Ray Bursts Nuclear Test Ban Treaty, 1963

    E-Print Network [OSTI]

    Harrison, Thomas

    Lecture 18 Gamma-Ray Bursts #12;Nuclear Test Ban Treaty, 1963 First Vela satellite pair launched and their predecessors, Vela 4, discovered the first gamma-ray bursts. The discovery was announced by Klebesadel, Strong, and Olson (ApJ, 182, 85) in 1973. #12;First Gamma-Ray Burst The Vela 5 satellites functioned from July, 1969

  10. The Biggest Bangs The Mystery of Gamma-Ray Bursts,

    E-Print Network [OSTI]

    Katz, Jonathan I.

    The Biggest Bangs The Mystery of Gamma-Ray Bursts, The Most Violent Explosions in The Universe J. I. Did a Gamma-Ray Burst Kill the Dinosaurs? Will a Burst Kill Us? #15; Glossary #15; Sources #15; Index. On January 23, 1999, one of these four cameras recorded visible light from a gamma-ray burst

  11. GammaRay Bursts: Old and New JOCHEN GREINER

    E-Print Network [OSTI]

    Greiner, Jochen

    Gamma­Ray Bursts: Old and New JOCHEN GREINER Astrophysikalisches Institut Potsdam, 14482 Potsdam, Germany (jgreiner@aip.de) ABSTRACT. Gamma­ray bursts are sudden releases of energy that for a duration of a few seconds outshine even huge galaxies. 30 years after the first detection of a gamma­ray burst

  12. Gamma-Ray Logging Workshop (February 1981) | Department of Energy

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directed offOCHCO2: FinalOffers3.pdf0-45.pdf0 Budget Fossil EnergyFullGO 2009 AnnualDepartment

  13. JOBAID-LOGGING IN TO THE OLC LEARNING SYSTEM

    Broader source: Energy.gov [DOE]

    In this job aid you will Log In to the system, Retrieve Forgotten Password and/or User ID, and Use the LMS Help System built into the application.

  14. MilagroA TeV Observatory for Gamma Ray Bursts

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Milagro­A TeV Observatory for Gamma Ray Bursts B.L. Dingus and the Milagro Collaboration Los energy gamma-rays from gamma-ray bursts. The highest energy gamma rays supply very strong constraints on the nature of gamma-ray burst sources as well as fundamental physics. Because the highest energy gamma-rays

  15. Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture

    SciTech Connect (OSTI)

    Scott Wilde, Raymond Keegan

    2008-07-01T23:59:59.000Z

    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.

  16. Escape of VHE gamma-rays from close massive binary Cen X-3

    E-Print Network [OSTI]

    W. Bednarek

    2000-07-13T23:59:59.000Z

    We consider propagation of very high energy (VHE) gamma-rays in the radiation field of a massive star in the binary system Cen X-3, which has been reported as a source of gamma-ray photons in the GeV and TeV energies. VHE gamma-rays or electrons, injected by the compact object, should develop inverse Compton pair cascades. We predict the gamma-ray spectra and light curves for the parameters of Cen X-3 system. It is found that the gamma-ray spectra, observed at different directions, have different shape and intensity. The gamma-ray light curves, produced in the case of electron injection by the compact object in the Cen X-3 system, should have opposite tendencies for photons with energies above 100 MeV and above 300 GeV, i.e. the photon intensities increases with phase in the first case and decreases with phase in the second case. However the model with injection of primary electrons seems to be in contrary with the reported modulation of the GeV gamma-ray flux with the pulsar's period. The model with injection of primary photons allows such modulation with the pulsar's period, but predicts strong modulation of the TeV flux with the orbital period of the binary. Modulation of TeV emission with the orbital period has been reported by the early Cherenkov observations, but was not confirmed by the recent, more sensitive observations by the Durham Mark 6 telescope.

  17. EVIDENCE OF CONTRIBUTION OF INTERVENING CLOUDS TO GAMMA-RAY BURST'S X-RAY COLUMN DENSITY

    SciTech Connect (OSTI)

    Wang, J., E-mail: wj@bao.ac.cn [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2013-10-20T23:59:59.000Z

    The origin of excess of X-ray column density with respect to optical extinction in gamma-ray bursts (GRBs) is still a puzzle. A proposed explanation of the excess is the photoelectric absorption due to the intervening clouds along a GRB's line of sight. Here, we test this scenario by using the intervening Mg II absorption as a tracer of the neutral hydrogen column density of the intervening clouds. We identify a connection between the large X-ray column density (and large column density ratio of log (N{sub H,X}/N{sub H{sub I}})?0.5) and large neutral hydrogen column density probed by the Mg II doublet ratio (DR). In addition, GRBs with large X-ray column density (and large ratio of log (N{sub H,X}/N{sub H{sub I}})>0) tend to have multiple saturated intervening absorbers with DR < 1.2. These results therefore indicate an additional contribution from the intervening system to the observed X-ray column density in some GRBs, although the contribution from the host galaxy alone cannot be excluded based on this study.

  18. Neutron-driven gamma-ray laser

    DOE Patents [OSTI]

    Bowman, Charles D. (Los Alamos, NM)

    1990-01-01T23:59:59.000Z

    A lasing cylinder emits laser radiation at a gamma-ray wavelength of 0.87 .ANG. when subjected to an intense neutron flux of about 400 eV neutrons. A 250 .ANG. thick layer of Be is provided between two layers of 100 .ANG. thick layer of .sup.57 Co and these layers are supported on a foil substrate. The coated foil is coiled to form the lasing cylinder. Under the neutron flux .sup.57 Co becomes .sup.58 Co by neutron absorption. The .sup.58 Co then decays to .sup.57 Fe by 1.6 MeV proton emission. .sup.57 Fe then transitions by mesne decay to a population inversion for lasing action at 14.4 keV. Recoil from the proton emission separates the .sup.57 Fe from the .sup.57 Co and into the Be, where Mossbauer emission occurs at a gamma-ray wavelength.

  19. Are gamma-ray bursts cosmological?

    E-Print Network [OSTI]

    Horvath, I

    2015-01-01T23:59:59.000Z

    Gamma-ray burst sources are distributed with a high level of isotropy, which is compatible with either a cosmological origin or an extended Galactic halo origin. The brightness distribution is another indicator used to characterize the spatial distribution in distance. In this paper the author discusses detailed fits of the BATSE gamma-ray burst peak-flux distributions with Friedmann models taking into account possible density evolution and standard candle luminosity functions. A chi-square analysis is used to estimate the goodness of the fits and the author derives the significance level of limits on the density evolution and luminosity function parameters. Cosmological models provide a good fit over a range of parameter space which is physically reasonable

  20. Lorentz violation from gamma-ray bursts

    E-Print Network [OSTI]

    Shu Zhang; Bo-Qiang Ma

    2014-06-18T23:59:59.000Z

    The constancy of light speed is a basic assumption in Einstein's special relativity, and consequently the Lorentz invariance is a fundamental symmetry of space-time in modern physics. However, it is speculated that the speed of light becomes energy-dependent due to the Lorentz invariance violation~(LV) in various new physics theories. We analyse the data of the energetic photons from the gamma-ray bursts (GRBs) by the Fermi Gamma-Ray Space Telescope, and find more events to support the energy dependence in the light speed with both linear and quadratic form corrections. We provide two scenarios to understand all the new-released Pass~8 data of bright GRBs by the Fermi-LAT Collaboration, with predictions from such scenarios being testable by future detected GRBs.

  1. Gamma-Ray Bursts: Progress, Problems & Prospects

    E-Print Network [OSTI]

    Bing Zhang; Peter Meszaros

    2003-11-13T23:59:59.000Z

    The cosmological gamma-ray burst (GRB) phenomenon is reviewed. The broad observational facts and empirical phenomenological relations of the GRB prompt emission and afterglow are outlined. A well-tested, successful fireball shock model is introduced in a pedagogical manner. Several important uncertainties in the current understanding of the phenomenon are reviewed, and prospects of how future experiments and extensive observational and theoretical efforts may address these problems are discussed.

  2. Gamma-ray Bursts in Wavelet Space

    E-Print Network [OSTI]

    Z. Bagoly; I. Horvath; A. Meszaros; L. G. Balazs

    2005-08-31T23:59:59.000Z

    The gamma-ray burst's lightcurves have been analyzed using a special wavelet transformation. The applied wavelet base is based on a typical Fast Rise-Exponential Decay (FRED) pulse. The shape of the wavelet coefficients' total distribution is determined on the observational frequency grid. Our analysis indicates that the pulses in the long bursts' high energy channel lightcurves are more FRED-like than the lower ones, independently from the actual physical time-scale.

  3. Gamma-Ray Line Observations with RHESSI

    E-Print Network [OSTI]

    David M. Smith

    2004-04-30T23:59:59.000Z

    The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) has been observing gamma-ray lines from the Sun and the Galaxy since its launch in February 2002. Here I summarize the status of RHESSI observations of solar lines (nuclear de-excitation, neutron capture, and positron annihilation), the lines of $^{26}$Al and $^{60}$Fe from the inner Galaxy, and the search for positron annihilation in novae.

  4. Gravitational radiation from long gamma-ray bursts

    E-Print Network [OSTI]

    Maurice H. P. M. van Putten

    2001-02-11T23:59:59.000Z

    Long gamma-ray bursts (GRBs) are probably powered by high-angular momentum black hole-torus systems in suspended accretion. The torus will radiate gravitational waves as non-axisymmetric instabilities develop. The luminosity in gravitational-wave emissions is expected to compare favorably with the observed isotropic equivalent luminosity in GRB-afterglow emissions. This predicts that long GRBs are potentially the most powerful LIGO/VIRGO burst-sources in the Universe. Their frequency-dynamics is characterized by a horizontal branch in the $\\dot{f}(f)-$diagram.

  5. GAMMA RAYS FROM STAR FORMATION IN CLUSTERS OF GALAXIES

    SciTech Connect (OSTI)

    Storm, Emma M.; Jeltema, Tesla E.; Profumo, Stefano [Department of Physics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2012-08-20T23:59:59.000Z

    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 {mu}m) 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.

  6. Fiber optic thermal/fast neutron and gamma ray scintillation detector

    DOE Patents [OSTI]

    Neal, John S. (Knoxville, TN); Mihalczo, John T (Oak Ridge, TN)

    2007-10-30T23:59:59.000Z

    A system for detecting fissile and fissionable material originating external to the system includes: a .sup.6Li loaded glass fiber scintillator for detecting thermal neutrons, x-rays and gamma rays; a fast scintillator for detecting fast neutrons, x-rays and gamma rays, the fast scintillator conjoined with the glass fiber scintillator such that the fast scintillator moderates fast neutrons prior to their detection as thermal neutrons by the glass fiber scintillator; and a coincidence detection system for processing the time distributions of arriving signals from the scintillators.

  7. Gamma-Ray Bursts Observed with the Spectrometer SPI Onboard INTEGRAL

    E-Print Network [OSTI]

    A. von Kienlin; A. Rau; V. Beckmann; S. Deluit

    2004-07-07T23:59:59.000Z

    The spectrometer SPI is one of the main detectors of ESA's INTEGRAL mission. The instrument offers two interesting and valuable capabilities for the detection of the prompt emission of Gamma-ray bursts. Within a field of view of 16 degrees, SPI is able to localize Gamma-ray bursts with an accuracy of 10 arcmin. The large anticoincidence shield, ACS, consisting of 512 kg of BGO crystals, detects Gamma-ray bursts quasi omnidirectionally above ~70 keV. Burst alerts from SPI/ACS are distributed to the interested community via the INTEGRAL Burst Alert System. The ACS data have been implemented into the 3rd Interplanetary Network and have proven valuable for the localization of bursts using the triangulation method. During the first 8 months of the mission approximately one Gamma-ray burst per month was localized within the field of fiew of SPI and 145 Gamma-ray burst candidates were detected by the ACS from which 40 % have been confirmed by other instruments.

  8. Standard guide for high-resolution gamma-ray spectrometry of soil samples

    E-Print Network [OSTI]

    American Society for Testing and Materials. Philadelphia

    2004-01-01T23:59:59.000Z

    1.1 This guide covers the identification and quantitative determination of gamma-ray emitting radionuclides in soil samples by means of gamma-ray spectrometry. It is applicable to nuclides emitting gamma rays with an approximate energy range of 20 to 2000 keV. For typical gamma-ray spectrometry systems and sample types, activity levels of about 5 Bq (135 pCi) are measured easily for most nuclides, and activity levels as low as 0.1 Bq (2.7 pCi) can be measured for many nuclides. It is not applicable to radionuclides that emit no gamma rays such as the pure beta-emitting radionuclides hydrogen-3, carbon-14, strontium-90, and becquerel quantities of most transuranics. This guide does not address the in situ measurement techniques, where soil is analyzed in place without sampling. Guidance for in situ techniques can be found in Ref (1) and (2). This guide also does not discuss methods for determining lower limits of detection. Such discussions can be found in Refs (3), (4), (5), and (6). 1.2 This guide can be us...

  9. VHE gamma-rays from Westerlund 2 and implications for the inferred energetics

    E-Print Network [OSTI]

    O. Reimer; F. Aharonian; J. Hinton; W. Hofmann; S. Hoppe; M. Raue; A. Reimer

    2007-10-18T23:59:59.000Z

    The H.E.S.S. collaboration recently reported the discovery of VHE gamma-ray emission coincident with the young stellar cluster Westerlund 2. This system is known to host a population of hot, massive stars, and, most particularly, the WR binary WR20a. Particle acceleration to TeV energies in Westerlund 2 can be accomplished in several alternative scenarios, therefore we only discuss energetic constraints based on the total available kinetic energy in the system, the actual mass loss rates of respective cluster members, and implied gamma-ray production from processes such as inverse Compton scattering or neutral pion decay. From the inferred gamma-ray luminosity of the order of 10^35 erg/s, implications for the efficiency of converting available kinetic energy into non-thermal radiation associated with stellar winds in the Westerlund 2 cluster are discussed under consideration of either the presence or absence of wind clumping.

  10. Gamma-ray burst interaction with dense interstellar medium

    E-Print Network [OSTI]

    Maxim Barkov; Gennady Bisnovatyi-Kogan

    2004-10-07T23:59:59.000Z

    Interaction of cosmological gamma ray burst radiation with the dense interstellar medium of host galaxy is considered. Gas dynamical motion of interstellar medium driven by gamma ray burst is investigated in 2D approximation for different initial density distributions of host galaxy matter and different total energy of gamma ray burst. The maximum velocity of motion of interstellar medium is $1.8\\cdot10^4$ km/s. Light curves of gamma ray burst afterglow are calculated for set of non homogeneous density, distribution gamma ray burst total energy, and different viewing angles. Spectra of gamma ray burst afterglow are modeled taking into account conversion of hard photons (soft X-ray, hard UV) to soft UV and optics photons.

  11. X-Ray Observations of Gamma-Ray Burst Afterglows

    E-Print Network [OSTI]

    Filippo Frontera

    2004-06-25T23:59:59.000Z

    The discovery by the BeppoSAX satellite of X-ray afterglow emission from the gamma-ray burst which occurred on 28 February 1997 produced a revolution in our knowledge of the gamma-ray burst phenomenon. Along with the discovery of X-ray afterglows, the optical afterglows of gamma-ray bursts were discovered and the distance issue was settled, at least for long $\\gamma$-ray bursts. The 30 year mystery of the gamma-ray burst phenomenon is now on the way to solution. Here I rewiew the observational status of the X-ray afterglow emission, its mean properties (detection rate, continuum spectra, line features, and light curves), and the X-ray constraints on theoretical models of gamma-ray bursters and their progenitors. I also discuss the early onset afterglow emission, the remaining questions, and the role of future X-ray afterglow observations.

  12. Gamma Ray Burst Neutrinos Probing Quantum Gravity

    E-Print Network [OSTI]

    M. C. Gonzalez-Garcia; F. Halzen

    2006-11-28T23:59:59.000Z

    Very high energy, short wavelength, neutrinos may interact with the space-time foam predicted by theories of quantum gravity. They would propagate like light through a crystal lattice and be delayed, with the delay depending on the energy. This will appear to the observer as a violation of Lorenz invariance. Back of the envelope calculations imply that observations of neutrinos produced by gamma ray bursts may reach Planck-scale sensitivity. We revisit the problem considering two essential complications: the imprecise timing of the neutrinos associated with their poorly understood production mechanism in the source and the indirect nature of their energy measurement made by high energy neutrino telescopes.

  13. Can Naked Singularities Yield Gamma Ray Bursts?

    E-Print Network [OSTI]

    H. M. Antia

    1998-07-09T23:59:59.000Z

    Gamma-ray bursts are believed to be the most luminous objects in the Universe. There has been some suggestion that these arise from quantum processes around naked singularities. The main problem with this suggestion is that all known examples of naked singularities are massless and hence there is effectively no source of energy. It is argued that a globally naked singularity coupled with quantum processes operating within a distance of the order of Planck length of the singularity will probably yield energy burst of the order of M_pc^2\\approx2\\times 10^{16} ergs, where M_p is the Planck mass.

  14. Puzzles of Galactic continuum gamma rays

    E-Print Network [OSTI]

    I. V. Moskalenko; A. W. Strong

    1998-11-14T23:59:59.000Z

    Inverse Compton scattering appears to play a more important role in the diffuse Galactic continuum emission than previously thought, from MeV to GeV energies. We compare models having a large inverse Compton component with EGRET data, and find good agreement in the longitude and latitude distributions at low and high energies. We test an alternative explanation for the >1 GeV gamma-ray excess, the hard nucleon spectrum, using secondary antiprotons and positrons. At lower energies to fit the COMPTEL and OSSE data as diffuse emission requires either a steep upturn in the electron spectrum below 200 MeV or a population of discrete sources.

  15. Classification of Fermi Gamma-RAY Bursts

    E-Print Network [OSTI]

    Horvath, I; Hakkila, J; Bagoly, Z; Preece, R D

    2015-01-01T23:59:59.000Z

    The Fermi GBM Catalog has been recently published. Previous classification analyses of the BATSE, RHESSI, BeppoSAX, and Swift databases found three types of gamma-ray bursts. Now we analyzed the GBM catalog to classify the GRBs. PCA and Multiclustering analysis revealed three groups. Validation of these groups, in terms of the observed variables, shows that one of the groups coincides with the short GRBs. The other two groups split the long class into a bright and dim part, as defined by the peak flux. Additional analysis is needed to determine whether this splitting is only a mathematical byproduct of the analysis or has some real physical meaning.

  16. Gamma-ray Bursts as Probes of Galaxy Evolution

    E-Print Network [OSTI]

    ?umer, Slobodan

    Gamma-ray Bursts as Probes of Galaxy Evolution Daniele Malesani, Dark Cosmology Centre and the X of the "Universe") #12;What is a gamma-ray burst? Brief (ms - min) and intense (~10-7 erg cm­2 s­1 ) burst of soft to ongoing star formation "Naked-eye" GRB 080319B GRBs explode within star-forming galaxies Gamma-ray bursts

  17. Gamma Ray Bursts, Neutron Star Quakes, and the Casimir Effect

    E-Print Network [OSTI]

    C. Carlson; T. Goldman; J. Perez-Mercader

    1994-11-25T23:59:59.000Z

    We propose that the dynamic Casimir effect is a mechanism that converts the energy of neutron starquakes into $\\gamma$--rays. This mechanism efficiently produces photons from electromagnetic Casimir energy released by the rapid motion of a dielectric medium into a vacuum. Estimates based on the cutoff energy of the gamma ray bursts and the volume involved in a starquake indicate that the total gamma ray energy emission is consonant with observational requirements.

  18. Nuclear Criticality as a Contributor to Gamma Ray Burst Events

    E-Print Network [OSTI]

    Robert Bruce Hayes

    2013-01-15T23:59:59.000Z

    Most gamma ray bursts are able to be explained using supernovae related phenomenon. Some measured results still lack compelling explanations and a contributory cause from nuclear criticality is proposed. This is shown to have general properties consistent with various known gamma ray burst properties. The galactic origin of fast rise exponential decay gamma ray bursts is considered a strong candidate for these types of events.

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

    ScienceCinema (OSTI)

    Isabelle Grenier

    2010-01-08T23:59:59.000Z

    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.

  20. atmospheric gamma rays: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Cherenkov telescope for gamma-ray astronomy. STACEE uses the large mirror area of a solar heliostat facility to achieve a low energy threshold. A prototype experiment which...

  1. Probing Massive Stars Around Gamma-Ray Burst Progenitors

    E-Print Network [OSTI]

    Lu, Wenbin; Smoot, George F

    2015-01-01T23:59:59.000Z

    Long Gamma-Ray Bursts (GRBs) are produced by ultra-relativistic jets launched from core collapse of massive stars. Most massive stars form in binaries and/or in star clusters, which means that there may be a significant external photon field (EPF) around the GRB progenitor. We calculate the inverse-Compton scattering of EPF by the hot electrons in the GRB jet. Three possible cases of EPFs are considered: the progenitor is (I) in a massive binary system, (II) surrounded by a Wolf-Rayet-star wind, and (III) in a dense star cluster. Typical luminosities of 10^47 - 10^50 erg/s in the 10 - 100 GeV band are expected, depending on the stellar luminosity, binary separation (I), wind mass loss rate (II), stellar number density (III), etc. We calculate the lightcurve and spectrum in each case, taking fully into account the equal-arrival time surfaces and possible pair-production absorption with the prompt gamma-rays. Observations can put constraints on the existence of such EPFs (and hence on the nature of GRB progenit...

  2. Radio flares from gamma-ray bursts

    E-Print Network [OSTI]

    Kopac, D; Kobayashi, S; Virgili, F J; Harrison, R; Japelj, J; Guidorzi, C; Melandri, A; Gomboc, A

    2015-01-01T23:59:59.000Z

    We present predictions of centimeter and millimeter radio emission from reverse shocks in the early afterglows of gamma-ray bursts 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 parametrization 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. (2007) and Melandri et al. (2010) in which the typical frequency of the reverse shock was suggested to lie at radio, rather than optical wavelengths at early times, we show that the brightest and most distinct reverse-shock 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 opt...

  3. Gamma Ray Fresnel lenses - why not?

    E-Print Network [OSTI]

    G. K. Skinner

    2006-02-03T23:59:59.000Z

    Fresnel lenses offer the possibility of concentrating the flux of X-rays or gamma-rays flux falling on a geometric area of many square metres onto a focal point which need only be a millimetre or so in diameter (and which may even be very much smaller). They can do so with an efficiency that can approach 100%, and yet they are easily fabricated and have no special alignment requirements. Fresnel lenses can offer diffraction-limited angular resolution, even in a domain where that limit corresponds to less than a micro second of arc. Given all these highly desirable attributes, it is natural to ask why Fresnel gamma ray lenses are not already being used, or at least why there is not yet any mission that plans to use the technology. Possible reasons (apart from the obvious one that nobody thought of doing so) include the narrow bandwidth of simple Fresnel lenses, their very long focal length, and the problems of target finding. It is argued that none of these is a "show stopper" and that this technique should be seriously considered for nuclear astrophysics.

  4. The metallicity and dust content of a redshift 5 gamma-ray burst host galaxy

    SciTech Connect (OSTI)

    Sparre, M.; Krühler, T.; Fynbo, J. P. U.; Watson, D. J.; De Ugarte Postigo, A.; Hjorth, J.; Malesani, D. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen (Denmark); Hartoog, O. E.; Kaper, L. [Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam (Netherlands); Wiersema, K. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); D'Elia, V. [INAF/Rome Astronomical Observatory, via Frascati 33, I-00040 Monteporzio Catone (Roma) (Italy); Zafar, T. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Afonso, P. M. J. [Physics and Astronomy Department, American River College, 4700 College Oak Drive, Sacramento, CA 95841 (United States); Covino, S. [INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy); Flores, H. [Laboratoire GEPI, Observatoire de Paris, CNRS-UMR8111, Universite Paris Diderot 5 place Jules Janssen, F-92195 Meudon (France); Goldoni, P. [APC, Astroparticule et Cosmologie, Universite Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10, Rue Alice Domon et Léonie Duquet, F-75205 Paris, Cedex 13 (France); Greiner, J. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, D-85748 Garching (Germany); Jakobsson, P. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, IS-107 Reykjavik (Iceland); Klose, S. [Thüringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg (Germany); Levan, A. J., E-mail: sparre@dark-cosmology.dk [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); and others

    2014-04-20T23:59:59.000Z

    Observations of the afterglows of long gamma-ray bursts (GRBs) allow the study of star-forming galaxies across most of cosmic history. Here we present observations of GRB 111008A, from which we can measure metallicity, chemical abundance patterns, dust-to-metals ratio (DTM), and extinction of the GRB host galaxy at z = 5.0. The host absorption system is a damped Ly? absorber with a very large neutral hydrogen column density of log?N(H I)/cm{sup ?2}=22.30±0.06 and a metallicity of [S/H] = –1.70 ± 0.10. It is the highest-redshift GRB with such a precise metallicity measurement. The presence of fine-structure lines confirms the z = 5.0 system as the GRB host galaxy and makes this the highest redshift where Fe II fine-structure lines have been detected. The afterglow is mildly reddened with A{sub V} = 0.11 ± 0.04 mag, and the host galaxy has a DTM that is consistent with being equal to or lower than typical values in the Local Group.

  5. Fiber optic thermal/fast neutron and gamma ray scintillation detector

    DOE Patents [OSTI]

    Neal, John S.; Mihalczo, John T.

    2006-11-28T23:59:59.000Z

    A detector system that combines a .sup.6Li loaded glass fiber scintillation thermal neutron detector with a fast scintillation detector in a single layered structure. Detection of thermal and fast neutrons and ionizing electromagnetic radiation is achieved in the unified detector structure. The fast scintillator replaces the polyethelene moderator layer adjacent the .sup.6Li loaded glass fiber panel of the neutron detector and acts as the moderator for the glass fibers. Fast neutrons, x-rays and gamma rays are detected in the fast scintillator. Thermal neutrons, x-rays and gamma rays are detected in the glass fiber scintillator.

  6. An investigation of the electronic wave functions in solids by the Compton scattering of gamma rays

    E-Print Network [OSTI]

    Nha, Sang Kyun

    1968-01-01T23:59:59.000Z

    APPARATUS The instrument, which was successfully used to study the behavior of the broadening of the Compton-scattered radiation, produces monochromatic gamma rays continuously variable in energy by selective Compton scattering of gamma photons emitted... was calculated. The system was adjusted to span the energy of- interest, then a count was taken 137 by using the Cs source. The channel corresponding to the peak 137 of Cs radiation was recorded, thon the pulser setting correspond)+8 to 662 1'eV (gamma ray...

  7. A New Determination Of The Diffuse Galactic and Extragalactic Gamma-Ray Emission

    E-Print Network [OSTI]

    Moskalenko, Igor V.

    for the distribution of galactic diffuse gamma-rays. We compare different propagation models with gamma-ray spectraA New Determination Of The Diffuse Galactic and Extragalactic Gamma-Ray Emission Andrew W. Strong1 for the apparent excess emission observed at GeV gamma-rays. We find that a population of hard-spectrum gamma-ray

  8. X-RAYRICH GAMMA-RAY BURSTS, PHOTOSPHERES, AND VARIABILITY P. Meszaros,1,2

    E-Print Network [OSTI]

    Zhang, Bing

    X-RAY­RICH GAMMA-RAY BURSTS, PHOTOSPHERES, AND VARIABILITY P. Me´sza´ros,1,2 E. Ramirez-Ruiz,3 M. J of the observational gamma-ray variability-luminosity relation. Subject headings: gamma rays: bursts -- radiation mechanisms: nonthermal 1. INTRODUCTION Gamma-ray burst (GRB) light curves at gamma-ray ener- gies are often

  9. Compton scattering effects on the duration of terrestrial gamma-ray flashes

    E-Print Network [OSTI]

    Pasko, Victor

    ; published 18 January 2012. [1] Terrestrial gamma-ray flashes (TGFs) are gamma-ray bursts detected from space) recently discovered by the gamma-ray burst monitor (GBM) aboard the Fermi Gamma-Ray Space Telescope. Introduction [2] Terrestrial gamma-ray flashes (TGFs) are bursts of high-energy photons originating from

  10. OBSERVATIONS OF THE PROMPT GAMMA-RAY EMISSION OF GRB 070125 Eric C. Bellm,1

    E-Print Network [OSTI]

    California at Berkeley, University of

    2007 November 13; accepted 2008 July 25 ABSTRACT The long, bright gamma-ray burst GRB 070125: gamma rays: bursts 1. INTRODUCTION The prompt gamma-ray emission of gamma-ray bursts (GRBs) is the mostOBSERVATIONS OF THE PROMPT GAMMA-RAY EMISSION OF GRB 070125 Eric C. Bellm,1 Kevin Hurley,1 Valentin

  11. Study of Celestial Objects with Very High Energy Gamma Rays CANGAROO III

    E-Print Network [OSTI]

    Enomoto, Ryoji

    ), the doppler boosting of secondary gamma-rays is sufficient to produce TeV gamma-rays. Gamma-ray bursts: Fireballs expanding with relativistic speed explain gamma-ray bursts at cosmological distancesStudy of Celestial Objects with Very High Energy Gamma Rays CANGAROO III Project Description

  12. Search for GeV Emission from Gamma-Ray Bursts Using Milagro Scaler Data

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Search for GeV Emission from Gamma-Ray Bursts Using Milagro Scaler Data D. A. Williams to search for high energy emission from a sample of 98 gamma-ray bursts (GRB) detected from January 2000: gamma-ray sources; gamma-ray bursts; astronomical observations: gamma-ray PACS: 98.70.Rz,95.85.Pw Air

  13. Search for gamma-rays from the unusually bright GRB 130427A with the HAWC Gamma-ray Observatory

    E-Print Network [OSTI]

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

    2014-01-01T23:59:59.000Z

    The long gamma-ray burst (GRB) 130427A was the most powerful burst ever detected with a redshift $z\\lesssim0.5$, featuring the highest energy photon so far detected from a GRB and the longest lasting emission above 100 MeV. The HAWC Gamma-ray Observatory is a new extensive air shower detector currently under construction in central Mexico. It features two data acquisition (DAQ) systems - one designed to readout full air-shower events (main DAQ) and the other one counting the signals in each photomultiplier tube (scaler DAQ). The burst occurred at a zenith angle of $57^\\circ$, when HAWC was running 10% of the final detector and collecting data with the scaler DAQ only. Based on the observed light curve at MeV-GeV energies, 8 different time periods have been searched for prompt and delayed emission from this GRB. In all cases, no statistically significant excess of counts has been found and upper limits have been placed. It is shown that a similar GRB close to zenith would be easily detected by the full HAWC de...

  14. Abstract--We have recently completed a large-area, coded-aperture, gamma-ray imager for use in searching for radiation

    E-Print Network [OSTI]

    Horn, Berthold K.P.

    sufficient radiation can reach a large gamma-ray detec- tor from a small source to make detection possibleAbstract-- We have recently completed a large-area, coded- aperture, gamma-ray imager for use. Results of first measurements obtained with the system are presented. I. INTRODUCTION emote detection

  15. RAPID TeV GAMMA-RAY FLARING OF BL LACERTAE

    SciTech Connect (OSTI)

    Arlen, T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)] [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Aune, T.; Bouvier, A. [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States)] [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Beilicke, M.; Buckley, J. H.; Bugaev, V.; Dickherber, R. [Department of Physics, Washington University, St. Louis, MO 63130 (United States)] [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States)] [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Cesarini, A.; Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland)] [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States)] [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Cui, W.; Feng, Q.; Finley, J. P. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States)] [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Dumm, J.; Fortson, L. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)] [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Errando, M. [Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States)] [Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States); Falcone, A. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States)] [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); Federici, S. [DESY, Platanenallee 6, D-15738 Zeuthen (Germany)] [DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Finnegan, G., E-mail: qfeng@purdue.edu, E-mail: cui@purdue.edu [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Collaboration: VERITAS Collaboration; and others

    2013-01-10T23:59:59.000Z

    We report on the detection of a very rapid TeV gamma-ray flare from BL Lacertae on 2011 June 28 with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The flaring activity was observed during a 34.6 minute exposure, when the integral flux above 200 GeV reached (3.4 {+-} 0.6) Multiplication-Sign 10{sup -6} photons m{sup -2} s{sup -1}, roughly 125% of the Crab Nebula flux measured by VERITAS. The light curve indicates that the observations missed the rising phase of the flare but covered a significant portion of the decaying phase. The exponential decay time was determined to be 13 {+-} 4 minutes, making it one of the most rapid gamma-ray flares seen from a TeV blazar. The gamma-ray spectrum of BL Lacertae during the flare was soft, with a photon index of 3.6 {+-} 0.4, which is in agreement with the measurement made previously by MAGIC in a lower flaring state. Contemporaneous radio observations of the source with the Very Long Baseline Array revealed the emergence of a new, superluminal component from the core around the time of the TeV gamma-ray flare, accompanied by changes in the optical polarization angle. Changes in flux also appear to have occurred at optical, UV, and GeV gamma-ray wavelengths at the time of the flare, although they are difficult to quantify precisely due to sparse coverage. A strong flare was seen at radio wavelengths roughly four months later, which might be related to the gamma-ray flaring activities. We discuss the implications of these multiwavelength results.

  16. THE BRIGHT GAMMA-RAY BURST OF 2000 FEBRUARY 10: A CASE STUDY OF AN OPTICALLY DARK GAMMA-RAY BURST

    E-Print Network [OSTI]

    Fynbo, Johan

    THE BRIGHT GAMMA-RAY BURST OF 2000 FEBRUARY 10: A CASE STUDY OF AN OPTICALLY DARK GAMMA-RAY BURST L Received 2002 January 16; accepted 2002 June 8 ABSTRACT The gamma-ray burst GRB 000210 had the highest: observations -- gamma-rays: bursts 1. INTRODUCTION It is observationally well established that about half

  17. astrophysical gamma ray: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    astrophysical gamma ray First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Astrophysical Gamma Ray...

  18. aerial gamma ray: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    aerial gamma ray First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Cosmic Rays: What Gamma Rays Can Say...

  19. Polarization mesurements of gamma ray bursts and axion like particles

    E-Print Network [OSTI]

    Andre Rubbia; Alexander Sakharov

    2008-09-03T23:59:59.000Z

    A polarized gamma ray emission spread over a sufficiently wide energy band from a strongly magnetized astrophysical object like gamma ray bursts (GRBs) offers an opportunity to test the hypothesis of axion like particles (ALPs). Based on evidences of polarized gamma ray emission detected in several gamma ray bursts we estimated the level of ALPs induced dichroism, which could take place in the magnetized fireball environment of a GRB. This allows to estimate the sensitivity of polarization measurements of GRBs to the ALP-photon coupling. This sensitivity $\\gag\\le 2.2\\cdot 10^{-11} {\\rm GeV^{-1}}$ calculated for the ALP mass $m_a=10^{-3}~{\\rm eV}$ and MeV energy spread of gamma ray emission is competitive with the sensitivity of CAST and becomes even stronger for lower ALPs masses.

  20. The supernova/gamma-ray burst/jet connection

    E-Print Network [OSTI]

    Hjorth, Jens

    2013-01-01T23:59:59.000Z

    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 bi-polar jet (seen as a gamma-ray burst). The resulting hot cocoon disrupts the star while the 56Ni produced gives rise to radioactive heating of the ejecta, seen as a supernova. In this discussion paper I summarise 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 insight into supernova explosions in general.

  1. Neutrino oscillations and gamma-ray bursts

    E-Print Network [OSTI]

    W. Kluzniak

    1998-07-22T23:59:59.000Z

    If the ordinary neutrinos oscillate into a sterile flavor in a manner consistent with the Super-Kamiokande data on the zenith-angle dependence of atmospheric mu-neutrino flux, an energy sufficient to power a typical cosmic gamma-ray burst (GRB) (about 10^{52} erg) can be carried by sterile neutrinos away from the source and deposited in a region relatively free of baryons. Hence, ultra-relativistic bulk motion (required by the theory of and observations of GRBs and their afterglows) can easily be achieved in the vicinity of plausible sources of GRBs. Oscillations between sterile and ordinary neutrinos would thus provide a solution to the ``baryon-loading problem'' in the theory of GRBs.

  2. Constraining Lorentz violations with Gamma Ray Bursts

    E-Print Network [OSTI]

    Maria Rodriguez Martinez; Tsvi Piran

    2006-05-17T23:59:59.000Z

    Gamma ray bursts are excellent candidates to constrain physical models which break Lorentz symmetry. We consider deformed dispersion relations which break the boost invariance and lead to an energy-dependent speed of light. In these models, simultaneously emitted photons from cosmological sources reach Earth with a spectral time delay that depends on the symmetry breaking scale. We estimate the possible bounds which can be obtained by comparing the spectral time delays with the time resolution of available telescopes. We discuss the best strategy to reach the strongest bounds. We compute the probability of detecting bursts that improve the current bounds. The results are encouraging. Depending on the model, it is possible to build a detector that within several years will improve the present limits of 0.015 m_pl.

  3. Short Gamma-Ray Bursts Are Different

    E-Print Network [OSTI]

    J. P. Norris; J. D. Scargle; J. T. Bonnell

    2001-05-07T23:59:59.000Z

    We analyze BATSE time-tagged event (TTE) data for short gamma-ray bursts (T90 duration burst. Performing the cross-correlation between two energy bands, we measure an average lag ~ 20-40 x shorter than for long bursts, and a lag distribution close to symmetric about zero - unlike long bursts. Using a "Bayesian Block" method to identify significantly distinct pulse peaks, we find an order of magnitude fewer pulses than found in studies of long bursts. The disparity in lag magnitude is discontinuous across the ~ 2-s valley between long and short bursts. Thus, short bursts do not appear to be representable as a continuation of long bursts' temporal characteristics.

  4. Gravitational Radiation from Gamma-Ray Bursts

    E-Print Network [OSTI]

    Tsvi Piran

    2001-02-19T23:59:59.000Z

    Gamma Ray Bursts (GRBs) are the most relativistic objects known so far, involving, on one hand an ultra-relativistic motion with a Lorentz factor $\\Gamma > 100$ and on the other hand an accreting newborn black hole. The two main routes leading to this scenario: binary neutron star mergers and Collapsar - the collapse of a rotating star to a black hole, are classical sources for gravitational radiation. Additionally one expect a specific a gravitational radiation pulse associated with the acceleration of the relativistic ejecta. I consider here the implication of the observed rates of GRBs to the possibility of detection of a gravitational radiation signal associated with a GRB. Unfortunately I find that, with currently planned detectors it is impossible to detect the direct gravitational radiation associated with the GRB. It is also quite unlikely to detect gravitational radiation associated with Collapsars. However, the detection of gravitational radiation from a neutron star merger associated with a GRB is likely.

  5. Super Luminous Supernova and Gamma Ray Bursts

    E-Print Network [OSTI]

    Shlomo Dado; Arnon Dar

    2012-11-08T23:59:59.000Z

    We use a simple analytical model to derive a closed form expression for the bolometric light-curve of super-luminus supernovae (SLSNe) powered by a plastic collision between the fast ejecta from core collapse supernovae (SNe) of types Ib/c and IIn and slower massive circum-stellar shells, ejected during the late stage of the life of their progenitor stars preceding the SN explosion. We demonstrate that this expression reproduces well the bolometric luminosity of SLSNe with and without an observed gamma ray burst (GRB), and requires only a modest amount ($M < 0.1\\,M_\\odot$) of radioactive $^{56}$Ni synthesized in the SN explosion in order to explain their late-time luminosity. Long duration GRBs can be produced by ordinary SNe of type Ic rather than by 'hypernovae' - a subclass of superenergetic SNeIb/c.

  6. Search for Gamma Ray Bursts at Chacaltaya

    E-Print Network [OSTI]

    Silvia Vernetto; for the INCA Collaboration

    2000-11-13T23:59:59.000Z

    A search for Gamma Ray Bursts in the GeV-TeV energy range has been performed by INCA, an air shower array working at 5200 m of altitude at the Chacaltaya Laboratory (Bolivia). The altitude of the detector and the use of the "single particle technique" allows to lower the energy threshold up to few GeVs. No significant signals are observed during the occurrence of 125 GRBs detected by BATSE, and the obtained upper limits on the energy fluence in the interval 1-1000(100) GeV range from 3.2(8.6) 10^-5 to 2.6(7.0) 10^-2 erg/cm^2 depending on the zenith angle of the events. These limits, thanks to the extreme altitude of INCA, are the lowest ever obtained in the sub-TeV energy region by a ground based esperiment.

  7. Gravitational Radiation from Gamma-Ray Burst Progenitors

    E-Print Network [OSTI]

    Shiho Kobayashi; Peter Meszaros

    2003-02-11T23:59:59.000Z

    We study gravitational radiation from various proposed gamma-ray burst (GRB) progenitor models, in particular compact mergers and massive stellar collapses. These models have in common a high angular rotation rate, and the final stage involves a rotating black hole and accretion disk system. We consider the in-spiral, merger and ringing phases, and for massive collapses we consider the possible effects of asymmetric collapse and break-up, as well bar-mode instabilities in the disks. We calculate the strain and frequency of the gravitational waves expected from various progenitors, at distances based on occurrence rate estimates. Based on simplifying assumptions, we give estimates of the probability of detection of gravitational waves by the advanced LIGO system from the different GRB scenarios.

  8. VAMOS: a Pathfinder for the HAWC Gamma-Ray Observatory

    E-Print Network [OSTI]

    Abeysekara, A U; Alvarez, C; Álvarez, J D; Ángeles, F; Arceo, R; Arteaga-Velázquez, J C; Avila-Aroche, A; Solares, H A Ayala; Badillo, C; Barber, A S; Baughman, B M; Bautista-Elivar, N; Gonzalez, J Becerra; Belmont, E; Benítez, E; BenZvi, S Y; Berley, D; Bernal, A; Rosales, M Bonilla; Braun, J; Caballero-Lopez, R A; Caballero-Mora, K S; Cabrera, I; Carramiñana, A; Castañeda-Martínez, L; Castillo, M; Cotti, U; Cotzomi, J; de la Fuente, E; De León, C; DeYoung, T; Diaz-Azuara, A; Diaz-Cruz, L; Hernandez, R Diaz; Díaz-Vélez, J C; Dingus, B L; Dultzin, D; DuVernois, M A; Ellsworth, R W; Fernandez, A; Fiorino, D W; Fraija, N; Galindo, A; García-Torales, G; Garfias, F; González, A; González, L X; González, M M; Goodman, J A; Grabski, V; Gussert, M; Guzmán-Cerón, C; Hampel-Arias, Z; Harding, J P; Hernández-Cervantes, L; Hui, C M; Hüntemeyer, P; Imran, A; Iriarte, A; Karn, P; Kieda, D; Kunde, G J; Langarica, R; Lara, A; Lara, G; Lauer, R J; Lee, W H; Lennarz, D; Vargas, H León; Linares, E C; Linnemann, J T; Longo, M; Luna-Garcia, R; Marinelli, A; Martínez, L A; Martínez, H; Martínez, O; Martínez-Castro, J; Martos, M; Matthews, J A J; McEnery, J; Torres, E Mendoza; Miranda-Romagnoli, P; Moreno, E; Mostafá, M; Nava, J; Nellen, L; Newbold, M; Noriega-Papaqui, R; Oceguera-Becerra, T; Page, D P; Patricelli, B; Pelayo, R; Pérez-Pérez, E G; Pretz, J; Ramírez, I; Renter, A; Rivière, C; Rosa-González, D; Ruiz-Sala, F; Ruiz-Velasco, E L; Ryan, J; Sacahui, J R; Salazar, H; Salesa, F; Sandoval, A; Santos, E; Schneider, M; Silich, S; Sinnis, G; Smith, A J; Woodle, K Sparks; Springer, R W; Suarez, F; Taboada, I; Tepe, A; Toale, P A; Tollefson, K; Torres, I; Tinoco, S; Ukwatta, T N; Galicia, J F Valdés; Vanegas, P; Vázquez, A; Villaseñor, L; Wall, W; Weisgarber, T; Westerhoff, S; Wisher, I G; Wood, J; Yodh, G B; Younk, P W; Zaborov, D; Zepeda, A; Zhou, H

    2014-01-01T23:59:59.000Z

    VAMOS was a prototype detector built in 2011 at an altitude of 4100m a.s.l. in the state of Puebla, Mexico. The aim of VAMOS was to finalize the design, construction techniques and data acquisition system of the HAWC observatory. HAWC is an air-shower array currently under construction at the same site of VAMOS with the purpose to study the TeV sky. The VAMOS setup included six water Cherenkov detectors and two different data acquisition systems. It was in operation between October 2011 and May 2012 with an average live time of 30%. Besides the scientific verification purposes, the eight months of data were used to obtain the results presented in this paper: the detector response to the Forbush decrease of March 2012, and the analysis of possible emission, at energies above 30 GeV, for long gamma-ray bursts GRB111016B and GRB120328B.

  9. An expert system advisor for well log quality control

    E-Print Network [OSTI]

    Warnken, Dean Kennedy

    1988-01-01T23:59:59.000Z

    funda- mental tool in the evaluation of petroleum reservoirs. Wireline well logging involves undergrourR measurement of various rock and fluid properties. These meas~ts are usually recorded with a downhole sonde and ~tted to the surface through a... expert systems, has proven to be an effective com- puterized problem solving tool in many oilfield applications. Expert systems strive to mimic an ~'s reasoning process when performing a highly specialized task. Expert system problem solvirg combines...

  10. Compton Recoil Electron Tracking With the TIGRE Gamma-Ray Balloon Experiment

    E-Print Network [OSTI]

    Kamiya, Kaoru

    2011-01-01T23:59:59.000Z

    AGNs), pulsars, gamma-ray bursts, cosmic ray interactionssensitive to cosmic gamma-ray bursts in the energy range ofGalactic center, a single gamma-ray burst which occurred 10

  11. The Search for Muon Neutrinos from Northern Hemisphere Gamma-Ray Bursts with AMANDA

    E-Print Network [OSTI]

    Achterberg, A.; IceCube Collaboration

    2008-01-01T23:59:59.000Z

    see also the Swift Gamma-Ray Burst Mission Page: http://from Northern Hemisphere Gamma-Ray Bursts with AMANDA A.Northern Hemisphere Gamma-Ray Bursts with AMANDA The IceCube

  12. Search for muon neutrinos from Gamma-Ray Bursts with the IceCube neutrino telescope

    E-Print Network [OSTI]

    Abbasi, R.

    2010-01-01T23:59:59.000Z

    2009, GCN: The Gamma ray bursts Coordinates Network, http://for muon neutrinos from Gamma-Ray Bursts with the IceCubeMereghetti, S. 2004, in Gamma-ray Bursts: 30 Years of

  13. Long gamma-ray bursts and core-collapse supernovae have different environments

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    Progenitor Stars of Gamma-Ray Bursts. Astrophys. J. 637, 45.massive stars towards gamma-ray bursts. Astr. Astrophys.On the Lyalpha emission from gamma-ray burst host galaxies:

  14. GRB 020410: A Gamma-ray burst afterglow discovered by its supernova light

    E-Print Network [OSTI]

    2004-01-01T23:59:59.000Z

    Training Network “Gamma-Ray Bursts: An Enigma and a Tool”,Journal GRB 020410: A Gamma-Ray Burst Afterglow DiscoveredSubject headings: gamma rays: bursts – supernova: general

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

    SciTech Connect (OSTI)

    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)

    2012-10-10T23:59:59.000Z

    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. Magnetic Structures in Gamma-Ray Burst Jets Probed by Gamma-Ray Polarization

    E-Print Network [OSTI]

    Daisuke Yonetoku; Toshio Murakami; Shuichi Gunji; Tatehiro Mihara; Kenji Toma; Yoshiyuki Morihara; Takuya Takahashi; Yudai Wakashima; Hajime Yonemochi; Tomonori Sakashita; Noriyuki Toukairin; Hirofumi Fujimoto; Yoshiki Kodama

    2012-08-27T23:59:59.000Z

    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) aboard IKAROS solar sail mission. We detected linear polarization signals from each burst with polarization degree of $\\Pi = 70 \\pm 22$% with statistical significance of $3.7 \\sigma$ for GRB 110301A, and $\\Pi = 84^{+16}_{-28}$% 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. (2011). Synchrotron emission model can be consistent with all the data of the three GRBs, while photospheric quasi-thermal emission model is not favorable. We suggest that magnetic field structures in the emission region are globally-ordered fields advected from the central engine.

  17. Gravitational waves versus X-ray and gamma-ray emission in a short gamma-ray burst

    SciTech Connect (OSTI)

    Oliveira, F. G.; Rueda, Jorge A.; Ruffini, R., E-mail: fe.fisica@gmail.com, E-mail: jorge.rueda@icra.it, E-mail: ruffini@icra.it [Dipartimento di Fisica and ICRA, Sapienza Università di Roma, P.le Aldo Moro 5, I-00185 Rome (Italy)

    2014-06-01T23:59:59.000Z

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

  18. High Energy Gamma-Ray Emission from Gamma-Ray Bursts - Before GLAST

    SciTech Connect (OSTI)

    Fan, Yi-Zhong; Piran, Tsvi

    2011-11-29T23:59:59.000Z

    Gamma-ray bursts (GRBs) are short and intense emission of soft {gamma}-rays, which have fascinated astronomers and astrophysicists since their unexpected discovery in 1960s. The X-ray/optical/radio afterglow observations confirm the cosmological origin of GRBs, support the fireball model, and imply a long-activity of the central engine. The high-energy {gamma}-ray emission (> 20 MeV) from GRBs is particularly important because they shed some lights on the radiation mechanisms and can help us to constrain the physical processes giving rise to the early afterglows. In this work, we review observational and theoretical studies of the high-energy emission from GRBs. Special attention is given to the expected high-energy emission signatures accompanying the canonical early-time X-ray afterglow that was observed by the Swift X-ray Telescope. We also discuss the detection prospect of the upcoming GLAST satellite and the current ground-based Cerenkov detectors.

  19. Constraints on Very High Energy gamma-ray emission from Gamma-Ray Bursts

    E-Print Network [OSTI]

    Atkins, R; Berley, D; Blaufuss, E; Coyne, D G; De Young, T R; Dingus, B L; Dorfan, D E; Ellsworth, R W; Fleysher, L; Fleysher, R; González, M M; Goodman, J A; Hays, E; Hoffman, C M; Kelley, L A; Lansdell, C P; Linnemann, J T; McEnery, J E; Mincer, A I; Morales, M F; Némethy, P; Noyes, D; Ryan, J M; Samuelson, F W; Parkinson, P M S; Shoup, A; Sinnis, G; Smith, A J; Sullivan, G W; Williams, D A; Wilson, M E; Xu, X W; Yodh, G B

    2005-01-01T23:59:59.000Z

    The Milagro gamma-ray observatory employs a water Cherenkov detector to observe extensive air showers produced by high energy particles interacting in the Earth's atmosphere. Milagro has a wide field of view and high duty cycle, monitoring the northern sky almost continuously in the 100 GeV to 100 TeV energy range. Milagro is, thus, uniquely capable of searching for very high-energy emission from gamma-ray bursts (GRBs) during the prompt emission phase. Detection of >100 GeV counterparts would place powerful constraints on GRB mechanisms. Twenty-five satellite-triggered GRBs occurred within the field of view of Milagro between January 2000 and December 2001. We have searched for counterparts to these GRBs and found no significant emission from any of the burst positions. Due to the absorption of high-energy gamma rays by the extragalactic background light, detections are only expected to be possible for redshifts less than ~0.5. Three of the GRBs studied have measured redshifts. GRB 010921 has a redshift low ...

  20. Constraints on Very High Energy gamma-ray emission from Gamma-Ray Bursts

    E-Print Network [OSTI]

    R. Atkins; W. Benbow; D. Berley; E. Blaufuss; D. G. Coyne; T. DeYoung; B. L. Dingus; D. E. Dorfan; R. W. Ellsworth; L. Fleysher; R. Fleysher; M. M. Gonzalez; J. A. Goodman; E. Hays; C. M. Hoffman; L. A. Kelley; C. P. Lansdell; J. T. Linnemann; J. E. McEnery; A. I. Mincer; M. F. Morales; P. Nemethy; D. Noyes; J. M. Ryan; F. W. Samuelson; P. M. Saz Parkinson; A. Shoup; G. Sinnis; A. J. Smith; G. W. Sullivan; D. A. Williams; M. E. Wilson; X. W. Xu; G. B. Yodh

    2005-03-11T23:59:59.000Z

    The Milagro gamma-ray observatory employs a water Cherenkov detector to observe extensive air showers produced by high energy particles interacting in the Earth's atmosphere. Milagro has a wide field of view and high duty cycle, monitoring the northern sky almost continuously in the 100 GeV to 100 TeV energy range. Milagro is, thus, uniquely capable of searching for very high-energy emission from gamma-ray bursts (GRBs) during the prompt emission phase. Detection of >100 GeV counterparts would place powerful constraints on GRB mechanisms. Twenty-five satellite-triggered GRBs occurred within the field of view of Milagro between January 2000 and December 2001. We have searched for counterparts to these GRBs and found no significant emission from any of the burst positions. Due to the absorption of high-energy gamma rays by the extragalactic background light, detections are only expected to be possible for redshifts less than ~0.5. Three of the GRBs studied have measured redshifts. GRB 010921 has a redshift low enough (0.45) to allow an upper limit on the fluence to place an observational constraint on potential GRB models.

  1. Pile-up recovery in gamma-ray detection

    SciTech Connect (OSTI)

    Vencelj, Matjaz; Likar, Andrej; Loeher, Bastian; Miklavec, Mojca; Novak, Roman; Pietralla, Norbert; Savran, Deniz [Jozef Stefan Instute, Jamova 39, SI-1000 Ljubljana (Slovenia); Jozef Stefan Instute, Jamova 39, SI-1000 Ljubljana, Slovenia and FMF, Univ. of Ljubljana, Jadranska 19, SI-1000 Ljubljana (Slovenia); ExtreMe Matter Institute EMMI, GSI, Planckstr. 1, D-64291 Darmstadt, Germany and Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, D-60438 Frankfurt am Main (Germany); Jozef Stefan Instute, Jamova 39, SI-1000 Ljubljana (Slovenia); IKP, TU Darmstadt, Schlossgartenstrasse 9, D-64289 Darmstadt (Germany); ExtreMe Matter Institute EMMI, GSI, Planckstr. 1, D-64291 Darmstadt (Germany) and Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, D-60438 Frankfurt am Main (Germany)

    2012-07-09T23:59:59.000Z

    Count rates in gamma-ray detectors are fundamentally limited at the high end by the physics of the detection process but should not be limited further by the design of read-out. Using intense stimuli, such as the ELI, it is desirable to extract the full wealth of information flow that sensors can deliver. We discuss the photon-statistical limitations of scintillation systems and charge-collection issues of solid-state detectors. With high-speed digitizing in particular, two promising approach architectures are those of posterior list mode corrections and of time-domain adaptive filters, introducing a 'rich list mode with uncertainties' and thus a somewhat different look at experimental spectra. Real-time performance is also considered.

  2. Numerical Simulations of Gamma-Ray Burst Explosions

    E-Print Network [OSTI]

    Lazzati, Davide; López-Cámara, Diego

    2015-01-01T23:59:59.000Z

    Gamma-ray bursts are a complex, non-linear system that evolves very rapidly through stages of vastly different conditions. They evolve from scales of few hundred kilometers where they are very dense and hot to cold and tenuous on scales of parsecs. As such, our understanding of such a phenomenon can truly increase by combining theoretical and numerical studies adopting different numerical techniques to face different problems and deal with diverse conditions. In this review, we will describe the tremendous advancement in our comprehension of the bursts phenomenology through numerical modeling. Though we will discuss studies mainly based on jet dynamics across the progenitor star and the interstellar medium, we will also touch upon other problems such as the jet launching, its acceleration, and the radiation mechanisms. Finally, we will describe how combining numerical results with observations from Swift and other instruments resulted in true understanding of the bursts phenomenon and the challenges still lyi...

  3. GRAVITATIONAL WAVES OF JET PRECESSION IN GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Sun Mouyuan; Liu Tong; Gu Weimin; Lu Jufu, E-mail: tongliu@xmu.edu.cn [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005 (China)

    2012-06-10T23:59:59.000Z

    The physical nature of gamma-ray bursts (GRBs) is believed to involve an ultra-relativistic jet. The observed complex structure of light curves motivates the idea of jet precession. In this work, we study the gravitational waves of jet precession based on neutrino-dominated accretion disks around black holes, which may account for the central engine of GRBs. In our model, the jet and the inner part of the disk may precess along with the black hole, which is driven by the outer part of the disk. Gravitational waves are therefore expected to be significant from this black-hole-inner-disk precession system. By comparing our numerical results with the sensitivity of some detectors, we find that it is possible for DECIGO and BBO to detect such gravitational waves, particularly for GRBs in the Local Group.

  4. Compact Gamma-ray Source Technology Development Study

    SciTech Connect (OSTI)

    Anderson, S G; Gibson, D J; Rusnak, B

    2009-09-25T23:59:59.000Z

    This study focuses on the applicability of current accelerator and laser technologies to the construction of compact, narrow bandwidth, gamma-ray sources for DHS missions in illicit materials detection. It also identifies research and development areas in which advancement will directly benefit these light sources. In particular, we review the physics of Compton scattering based light sources and emphasize the source properties most important to Nuclear Resonance Fluorescence (NRF) applications of interest. The influences of laser and electron beam properties on the light source are examined in order to evaluate the utility of different technologies for this application. Applicable bulk and fiber-based laser systems and laser recirculation technologies are discussed and Radio Frequency (RF) Linear Accelerator (linac) technologies are examined to determine the optimal frequency and pulse formats achievable.

  5. Waves on Noncommutative Spacetime and Gamma-Ray Bursts

    E-Print Network [OSTI]

    Giovanni Amelino-Camelia; Shahn Majid

    1999-07-14T23:59:59.000Z

    Quantum group Fourier transform methods are applied to the study of processes on noncommutative Minkowski spacetime $[x^i,t]=\\imath\\lambda x^i$. A natural wave equation is derived and the associated phenomena of {\\it in vacuo} dispersion are discussed. Assuming the deformation scale $\\lambda$ is of the order of the Planck length one finds that the dispersion effects are large enough to be tested in experimental investigations of astrophysical phenomena such as gamma-ray bursts. We also outline a new approach to the construction of field theories on the noncommutative spacetime, with the noncommutativity equivalent under Fourier transform to non-Abelianness of the `addition law' for momentum in Feynman diagrams. We argue that CPT violation effects of the type testable using the sensitive neutral-kaon system are to be expected in such a theory.

  6. The Gamma-ray Albedo of the Moon

    SciTech Connect (OSTI)

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

    2007-09-28T23:59:59.000Z

    We use the GEANT4 Monte Carlo framework to calculate the {gamma}-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of {gamma}-rays from the Moon is very steep with an effective cutoff around 3-4 GeV (600 MeV for the inner part of the Moon disk) and exhibits a narrow pion-decay line at 67.5 MeV, perhaps unique in astrophysics. Apart from other astrophysical sources, the albedo spectrum of the Moon is well understood, including its absolute normalization; this makes it a useful 'standard candle' for {gamma}-ray telescopes. The steep albedo spectrum also provides a unique opportunity for energy calibration of {gamma}-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). Since the albedo flux depends on the incident CR spectrum which changes over the solar cycle, it is possible to monitor the CR spectrum using the albedo {gamma}-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter-Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo {gamma}-rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the LAT to monitor the CR spectrum near the Earth beyond the lifetime of the PAMELA.

  7. RELATIVISTIC SHOCK BREAKOUTS-A VARIETY OF GAMMA-RAY FLARES: FROM LOW-LUMINOSITY GAMMA-RAY BURSTS TO TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Nakar, Ehud [Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel); Sari, Re'em [Racah Institute for Physics, Hebrew University, Jerusalem 91904 (Israel)

    2012-03-10T23:59:59.000Z

    The light from a shock breakout of stellar explosions, which carries a wealth of information, strongly depends on the shock velocity at the time of the breakout. The emission from Newtonian breakouts, typical in regular core-collapse supernovae (SNe), has been explored extensively. However, a large variety of explosions result in mildly or ultrarelativistic breakouts, where the observed signature is unknown. Here we calculate the luminosity and spectrum produced by relativistic breakouts. In order to do so, we improve the analytic description of relativistic radiation-mediated shocks and follow the system from the breakout itself, through the planar phase and into the spherical phase. We limit our calculation to cases where the post-breakout acceleration of the gas ends during the planar phase (i.e., the final gas Lorentz factor {approx}< 30). We find that spherical relativistic breakouts produce a flash of gamma rays with energy, E{sub bo}, temperature, T{sub bo}, and duration, t{sup obs} b{sub o}, that provide the breakout radius ( Almost-Equal-To 5 R{sub Sun }(t{sup obs}{sub bo}/10 s)(T{sub bo}/50 keV){sup 2}) and the Lorentz factor ( Almost-Equal-To T{sub bo}/50 keV). They also always satisfy a relativistic breakout relation (t{sup obs}{sub bo}/20 s) {approx} (E{sub bo}/10{sup 46} erg){sup 1/2}(T{sub bo}/50 keV){sup -2.68}. The breakout flare is typically followed, on longer timescales, by X-rays that carry a comparable energy. We apply our model to a variety of explosions, including Type Ia and .Ia SNe, accretion-induced collapse, energetic SNe, and gamma-ray bursts (GRBs). We find that all these events produce detectable gamma-ray signals, some of which may have already been seen. Some particular examples are: (1) relativistic shock breakouts provide a natural explanation to the energy, temperature, and timescales of low-luminosity GRBs. Indeed, all observed low-luminosity GRBs satisfy the relativistic breakout relation. (2) Nearby broad-line Type Ib/c (like SN 2002ap) may produce a detectable {gamma}-ray signal. (3) Galactic Type Ia SNe may produce detectable {gamma}-ray flares. We conclude that relativistic shock breakouts provide a generic process for the production of gamma-ray flares.

  8. System Problem Detection by Mining Console Logs Electrical Engineering and Computer Sciences

    E-Print Network [OSTI]

    Xu, Wei

    for mining console logs using a combination of program analysis, information retrieval, data mining logs. We then extract features, such as execution traces, from logs and use data mining and machineSystem Problem Detection by Mining Console Logs Wei Xu Electrical Engineering and Computer Sciences

  9. An Analytical Expression for the Hubble diagram of supernovae and gamma-ray bursts

    E-Print Network [OSTI]

    Jean-Marie Vigoureux; Bernard Vigoureux; Michel Langlois

    2014-11-12T23:59:59.000Z

    A recent paper by Harmut Traunm\\"uller shows that the most adequate equation to interpret the observations on magnitude and redshift from 892 type 1a supernovae would be mu = 5 log[(1+z) ln(1+z)] + const. We discuss this result which is exacly the one we have obtained few years ago when postulating a relation between the speed of light and the expansion of the universe. We also compare our analytical result to the conclusion of Marosi who studied 280 supernovae and gamma-ray bursts in the range 0.1014 < z < 8.1. The difference between his results and ours is at worst of 0.3 %.

  10. Gamma Ray Burst Constraints on Ultraviolet Lorentz Invariance Violation

    E-Print Network [OSTI]

    Tina Kahniashvili; Grigol Gogoberidze; Bharat Ratra

    2006-10-20T23:59:59.000Z

    We present a unified general formalism for ultraviolet Lorentz invariance violation (LV) testing through electromagnetic wave propagation, based on both dispersion and rotation measure data. This allows for a direct comparison of the efficacy of different data to constrain LV. As an example we study the signature of LV on the rotation of the polarization plane of $\\gamma$-rays from gamma ray bursts in a LV model. Here $\\gamma$-ray polarization data can provide a strong constraint on LV, 13 orders of magnitude more restrictive than a potential constraint from the rotation of the cosmic microwave background polarization proposed by Gamboa, L\\'{o}pez-Sarri\\'{o}n, and Polychronakos (2006).

  11. A Search for Gamma-Ray Bursts and Pulsars, and the Application of Kalman Filters to Gamma-Ray Reconstruction

    E-Print Network [OSTI]

    B. B. Jones

    2002-02-04T23:59:59.000Z

    Part I describes the analysis of periodic and transient signals in EGRET data. A method to search for the transient flux from gamma-ray bursts independent of triggers from other gamma-ray instruments is developed. Several known gamma-ray bursts were independently detected, and there is evidence for a previously unknown gamma-ray burst candidate. Statistical methods using maximum likelihood and Bayesian inference are developed and implemented to extract periodic signals from gamma-ray sources in the presence of significant astrophysical background radiation. The analysis was performed on six pulsars and three pulsar candidates. The three brightest pulsars, Crab, Vela, and Geminga, were readily identified, and would have been detected independently in the EGRET data without knowledge of the pulse period. No significant pulsation was detected in the three pulsar candidates. Eighteen X-ray binaries were examined. None showed any evidence of periodicity. In addition, methods for calculating the detection threshold of periodic flux modulation were developed. The future hopes of gamma-ray astronomy lie in the development of the Gamma-ray Large Area Space Telescope, or GLAST. Part II describes the development and results of the particle track reconstruction software for a GLAST science prototype instrument beam test. The Kalman filtering method of track reconstruction is introduced and implemented. Monte Carlo simulations, very similar to those used for the full GLAST instrument, were performed to predict the instrumental response of the prototype. The prototype was tested in a gamma-ray beam at SLAC. The reconstruction software was used to determine the incident gamma-ray direction. It was found that the simulations did an excellent job of representing the actual instrument response.

  12. Gamma-ray electrification of a dielectric

    SciTech Connect (OSTI)

    Arkhipov, V.I.; Gromov, V.V.; Mamonov, M.N.; Rozno, A.G.; Rudenko, A.I.; Strikhanov, M.N.

    1987-08-01T23:59:59.000Z

    In this work the behavior of the characteristics of the volume charge induced by a ..gamma..-ray pulse in a thick plane-parallel plate, under the normal incidence of a beam of monoenergetic quanta ranging from 10 keV to 1 MeV, is examined. The theoretical results obtained are compared with experimental data obtained for a layer of polymethyl methacrylate 1.8 mm thick with the use of the spectrum of x-ray bremmstrahlung, produced by 1 MeV electrons passing through an iron target with a specific thickness of 0.796 g/cm/sup 2/. The density distribution of the volume charge was obtained taking into account in detail the angular characteristics of the photo- and Compton electrons. A simple procedure was used to take into account the effect of multiple scattering of the electrons; unlike well-known computational methods it enabled clear physical interpretation and did not require large amounts of computer time in carrying out the calculations.

  13. Diffuse Gamma-Ray Emission from Large Scale Structures

    E-Print Network [OSTI]

    Dobardzic, Aleksandra

    2012-01-01T23:59:59.000Z

    For more than a decade now the complete origin of the diffuse gamma-ray emission background (EGRB) has been unknown. Major components like unresolved star-forming galaxies (making 10GeV. Moreover, we show that, even though the gamma-ray emission arising from structure formation shocks at galaxy clusters is below previous estimates, these large scale shocks can still give an important, and even dominant at high energies, contribution to the EGRB. Future detections of cluster gamma-ray emission would make our upper limit of the extragalactic gamma-ray emission from structure-formation process, a firm prediction, and give us deeper insight in evolution of these large scale shock.

  14. INTERPLANETARY NETWORK LOCALIZATIONS OF KONUS SHORT GAMMA-RAY BURSTS

    E-Print Network [OSTI]

    Vanderspek, Roland K.

    Between the launch of the Global Geospace Science Wind spacecraft in 1994 November and the end of 2010, the Konus-Wind experiment detected 296 short-duration gamma-ray bursts (including 23 bursts which can be classified ...

  15. Redshifts of the Long Gamma-Ray Bursts

    E-Print Network [OSTI]

    Z. Bagoly; I. Csabai; A. Meszaros; P. Meszaros; I. Horvath; L. G. Balazs; R. Vavrek

    2007-04-06T23:59:59.000Z

    The low energy spectra of some gamma-ray bursts' show excess components beside the power-law dependence. The consequences of such a feature allows to estimate the gamma photometric redshift of the long gamma-ray bursts in the BATSE Catalog. There is good correlation between the measured optical and the estimated gamma photometric redshifts. The estimated redshift values for the long bright gamma-ray bursts are up to z=4, while for the the faint long bursts - which should be up to z=20 - the redshifts cannot be determined unambiguously with this method. The redshift distribution of all the gamma-ray bursts with known optical redshift agrees quite well with the BATSE based gamma photometric redshift distribution.

  16. A Gamma-Ray Burst Bibliography, 1973-1999

    E-Print Network [OSTI]

    K. Hurley

    1999-12-02T23:59:59.000Z

    On the average, one new publication on cosmic gamma-ray bursts enters the literature every day. The total number now exceeds 4100. I present here a complete bibliography which can be made available electronically to interested parties.

  17. Particle Swarm Imaging (PSIM) - Innovative Gamma-Ray Assay - 13497

    SciTech Connect (OSTI)

    Parvin, Daniel; Clarke, Sean; Humes, Sarah J. [Babcock International Group, Sellafield, Cumbria (United Kingdom)] [Babcock International Group, Sellafield, Cumbria (United Kingdom)

    2013-07-01T23:59:59.000Z

    Particle Swarm Imaging is an innovative technique used to perform quantitative gamma-ray assay. The innovation overcomes some of the difficulties associated with the accurate measurement and declaration of measurement uncertainties of radionuclide inventories within waste items when the distribution of activity is unknown. Implementation requires minimal equipment, with field measurements and results obtained using only a single electrically cooled HRGS gamma-ray detector. Examples of its application in the field are given in this paper. (authors)

  18. Hyperstars - Main Origin of Short Gamma Ray Bursts?

    E-Print Network [OSTI]

    Arnon Dar

    2005-09-09T23:59:59.000Z

    The first well-localized short-duration gamma ray bursts (GRBs), GRB 050509b, GRB 050709 and GRB 050724, could have been the narrowly beamed initial spike of a burst/hyper flare of soft gamma ray repeaters (SGRs) in host galaxies at cosmological distances. Such bursts are expected if SGRs are young hyperstars, i.e. neutron stars where a considerable fraction of their neutrons have converted to hyperons and/or strange quark matter.

  19. Gamma Ray Bursts as Probes of Quantum Gravity

    E-Print Network [OSTI]

    Tsvi Piran

    2004-07-21T23:59:59.000Z

    Gamma ray bursts (GRBs) are short and intense pulses of $\\gamma$-rays arriving from random directions in the sky. Several years ago Amelino-Camelia et al. pointed out that a comparison of time of arrival of photons at different energies from a GRB could be used to measure (or obtain a limit on) possible deviations from a constant speed of light at high photons energies. I review here our current understanding of GRBs and reconsider the possibility of performing these observations.

  20. Relativity at Action or Gamma-Ray Bursts

    E-Print Network [OSTI]

    Tsvi Piran

    1996-07-08T23:59:59.000Z

    Gamma ray Bursts (GRBs) - short bursts of few hundred keV $\\gamma$-rays - have fascinated astronomers since their accidental discovery in the sixties. GRBs were ignored by most relativists who did not expect that they are associated with any relativistic phenomenon. The recent observations of the BATSE detector on the Compton GRO satellite have revolutionized our ideas on these bursts and the picture that emerges shows that GRBs are the most relativistic objects discovered so far.

  1. Science with the new generation high energy gamma- ray experiments

    E-Print Network [OSTI]

    M. Alvarez; D. D'Armiento; G. Agnetta; A. Alberdi; A. Antonelli; A. Argan; P. Assis; E. A. Baltz; C. Bambi; G. Barbiellini; H. Bartko; M. Basset; D. Bastieri; P. Belli; G. Benford; L. Bergstrom; R. Bernabei; G. Bertone; A. Biland; B. Biondo; F. Bocchino; E. Branchini; M. Brigida; T. Bringmann; P. Brogueira; A. Bulgarelli; J. A. Caballero; G. A. Caliandro; P. Camarri; F. Cappella; P. Caraveo; R. Carbone; M. Carvajal; S. Casanova; A. J. Castro-Tirado; O. Catalano; R. Catena; F. Celi; A. Celotti; R. Cerulli; A. Chen; R. Clay; V. Cocco; J. Conrad; E. Costa; A. Cuoco; G. Cusumano; C. J. Dai; B. Dawson; B. De Lotto; G. De Paris; A. de Ugarte Postigo; E. Del Monte; C. Delgado; A. Di Ciaccio; G. Di Cocco; S. Di Falco; G. Di Persio; B. L. Dingus; A. Dominguez; F. Donato; I. Donnarumma; M. Doro; J. Edsjo; J. M. Espino Navas; M. C. Espirito Santo; Y. Evangelista; C. Evoli; D. Fargion; C. Favuzzi; M. Feroci; M. Fiorini; L. Foggetta; N. Fornengo; T. Froysland; M. Frutti; F. Fuschino; J. L. Gomez; M. Gomez; D. Gaggero; N. Galante; M. I. Gallardo; M. Galli; J. E. Garcia; M. Garczarczyk; F. Gargano; M. Gaug; F. Gianotti; S. Giarrusso; B. Giebels; N. Giglietto; P. Giommi; F. Giordano; A. Giuliani; J. Glicenstein; P. Goncalves; D. Grasso; M. Guerriero; H. L. He; A. Incicchitti; J. Kirk; H. H. Kuang; A. La Barbera; G. La Rosa; C. Labanti; G. Lamanna; I. Lapshov; F. Lazzarotto; S. Liberati; F. Liello; P. Lipari; F. Longo; F. Loparco; M. Lozano; P. G. Lucentini De Sanctis; J. M. Ma; M. C. Maccarone; L. Maccione; V. Malvezzi; A. Mangano; M. Mariotti; M. Marisaldi; I. Martel; A. Masiero; E. Massaro; M. Mastropietro; E. Mattaini; F. Mauri; M. N. Mazziotta; S. Mereghetti; T. Mineo; S. Mizobuchi; A. Moiseev; M. Moles; C. Monte; F. Montecchia; E. Morelli; A. Morselli; I. Moskalenko; F. Nozzoli; J. F. Ormes; M. A. Peres-Torres; L. Pacciani; A. Pellizzoni; F. Perez-Bernal; F. Perotti; P. Picozza; L. Pieri; M. Pietroni; M. Pimenta; A. Pina; C. Pittori; C. Pontoni; G. Porrovecchio; F. Prada; M. Prest; D. Prosperi; R. Protheroe; G. Pucella; J. M. Quesada; J. M. Quintana; J. R. Quintero; S. Raino; M. Rapisarda; M. Rissi; J. Rodriguez; E. Rossi; G. Rowell; A. Rubini; F. Russo; M. Sanchez-Conde; B. Sacco; V. Scapin; M. Schelke; A. Segreto; A. Sellerholm; X. D. Sheng; A. Smith; P. Soffitta; R. Sparvoli; P. Spinelli; V. Stamatescu; L. S. Stark; M. Tavani; G. Thornton; L. G. Titarchuk; B. Tome; A. Traci; M. Trifoglio; A. Trois; P. Vallania; E. Vallazza; S. Vercellone; S. Vernetto; V. Vitale; N. Wild; Z. P. Ye; A. Zambra; F. Zandanel; D. Zanello

    2007-12-04T23:59:59.000Z

    This Conference is the fifth of a series of Workshops on High Energy Gamma- ray Experiments, following the Conferences held in Perugia 2003, Bari 2004, Cividale del Friuli 2005, Elba Island 2006. This year the focus was on the use of gamma-ray to study the Dark Matter component of the Universe, the origin and propagation of Cosmic Rays, Extra Large Spatial Dimensions and Tests of Lorentz Invariance.

  2. Science with the new generation high energy gamma- ray experiments

    E-Print Network [OSTI]

    Alvarez, M; Agnetta, G; Alberdi, A; Antonelli, A; Argan, A; Assis, P; Baltz, E A; Bambi, C; Barbiellini, G; Bartko, H; Basset, M; Bastieri, D; Belli, P; Benford, G; Bergström, L; Bernabei, R; Bertone, G; Biland, A; Biondo, B; Bocchino, F; Branchini, E; Brigida, M; Bringmann, T; Brogueira, P; Bulgarelli, A; Caballero, J A; Caliandro, G A; Camarri, P; Cappella, F; Caraveo, P; Carbone, R; Carvajal, M; Casanova, S; Castro-Tirado, A J; Catalano, O; Catena, R; Celi, F; Celotti, A; Cerulli, R; Chen, A; Clay, R; Cocco, V; Conrad, J; Costa, E; Cuoco, A; Cusumano, G; Dai, C J; Dawson, B; De Lotto, B; De Paris, G; Postigo, A de Ugarte; Del Monte, E; Delgado, C; Di Ciaccio, A; Di Cocco, G; Di Falco, S; Di Persio, G; Dingus, B L; Dominguez, A; Donato, F; Donnarumma, I; Doro, M; Edsjö, J; Navas, J M Espino; Santo, M C Espirito; Evangelista, Y; Evoli, C; Fargion, D; Favuzzi, C; Feroci, M; Fiorini, M; Foggetta, L; Fornengo, N; Froysland, T; Frutti, M; Fuschino, F; Gómez, J L; Gómez, M; Gaggero, D; Galante, N; Gallardo, M I; Galli, M; García, J E; Garczarczyk, M; Gargano, F; Gaug, M; Gianotti, F; Giarrusso, S; Giebels, B; Giglietto, N; Giommi, P; Giordano, F; Giuliani, A; Glicenstein, J; Gonçalves, P; Grasso, D; Guerriero, M; He, H L; Incicchitti, A; Kirk, J; Kuang, H H; La Barbera, A; La Rosa, G; Labanti, C; Lamanna, G; Lapshov, I; Lazzarotto, F; Liberati, S; Liello, F; Lipari, P; Longo, F; Loparco, F; Lozano, M; De Sanctis, P G Lucentini; Ma, J M; Maccarone, M C; Maccione, L; Malvezzi, V; Mangano, A; Mariotti, M; Marisaldi, M; Martel, I; Masiero, A; Massaro, E; Mastropietro, M; Mattaini, E; Mauri, F; Mazziotta, M N; Mereghetti, S; Mineo, T; Mizobuchi, S; Moiseev, A; Moles, M; Monte, C; Montecchia, F; Morelli, E; Morselli, A; Moskalenko, I; Nozzoli, F; Ormes, J F; Peres-Torres, M A; Pacciani, L; Pellizzoni, A; Pérez-Bernal, F; Perotti, F; Picozza, P; Pieri, L; Pietroni, M; Pimenta, M; Pina, A; Pittori, C; Pontoni, C; Porrovecchio, G; Prada, F; Prest, M; Prosperi, D; Protheroe, R; Pucella, G; Quesada, J M; Quintana, J M; Quintero, J R; Rainó, S; Rapisarda, M; Rissi, M; Rodríguez, J; Rossi, E; Rowell, G; Rubini, A; Russo, F; Sanchez-Conde, M; Sacco, B; Scapin, V; Schelke, M; Segreto, A; Sellerholm, A; Sheng, X D; Smith, A; Soffitta, P; Sparvoli, R; Spinelli, P; Stamatescu, V; Stark, L S; Tavani, M; Thornton, G; Titarchuk, L G; Tomé, B; Traci, A; Trifoglio, M; Trois, A; Vallania, P; Vallazza, E; Vercellone, S; Vernetto, S; Vitale, V; Wild, N; Ye, Z P; Zambra, A; Zandanel, F; Zanello, D

    2007-01-01T23:59:59.000Z

    This Conference is the fifth of a series of Workshops on High Energy Gamma- ray Experiments, following the Conferences held in Perugia 2003, Bari 2004, Cividale del Friuli 2005, Elba Island 2006. This year the focus was on the use of gamma-ray to study the Dark Matter component of the Universe, the origin and propagation of Cosmic Rays, Extra Large Spatial Dimensions and Tests of Lorentz Invariance.

  3. MILAGRO CONSTRAINTS ON VERY HIGH ENERGY EMISSION FROM SHORT-DURATION GAMMA-RAY BURSTS

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    MILAGRO CONSTRAINTS ON VERY HIGH ENERGY EMISSION FROM SHORT-DURATION GAMMA-RAY BURSTS A. A. Abdo,1 localizations of short, hard gamma-ray bursts (GRBs) by the Swift and HETE satellites have led: bursts -- gamma rays: observations Gamma-ray bursts (GRBs) have long been classified by their durations

  4. CORRELATIONS OF PROMPT AND AFTERGLOW EMISSION IN SWIFT LONG AND SHORT GAMMA-RAY BURSTS

    E-Print Network [OSTI]

    Zhang, Bing

    CORRELATIONS OF PROMPT AND AFTERGLOW EMISSION IN SWIFT LONG AND SHORT GAMMA-RAY BURSTS N. Gehrels,1 of prompt and afterglow emission from gamma-ray bursts (GRBs) between different spectral bands have been-limited for long events. Subject headingg: gamma rays: bursts 1. INTRODUCTION One of the longest enduring gamma-ray

  5. Ivan De Mitri VHE Gamma Ray Astronomy 1 Very High Energy

    E-Print Network [OSTI]

    Harrison, Thomas

    ~ 1/day Gamma Ray Bursts The X-ray counterpart detection with better pointing accuracy instrumentsIvan De Mitri VHE Gamma Ray Astronomy 1 Very High Energy Gamma Ray Astronomy Ivan De Mitri'Aquila, 11- Jun -2002 Photo F. Arneodo #12;Ivan De Mitri VHE Gamma Ray Astronomy 2 Seminar Outline Background

  6. Radio emissions from terrestrial gamma-ray flashes Joseph R. Dwyer1

    E-Print Network [OSTI]

    Cummer, Steven A.

    . Introduction 1.1. TGF Theory Overview [2] Terrestrial gamma-ray flashes (TGFs) are bright bursts of gamma raysRadio emissions from terrestrial gamma-ray flashes Joseph R. Dwyer1 and Steven A. Cummer2 Received frequency (RF) emissions by terrestrial gamma-ray flashes (TGFs) is developed. These radio emissions, which

  7. PoGO : The Polarised Gamma-ray Observer S. Larssona

    E-Print Network [OSTI]

    Haviland, David

    . Recently, the detection of high linear polarisation, (80±20)%, in a gamma ray burst ob- served, this observation will have far reaching implications for models of gamma- ray bursts. Many of the X-ray and gamma-ray1 PoGO : The Polarised Gamma-ray Observer S. Larssona and M. Pearceb (for the PoGO Collaboration

  8. Proceedings of ICRC 2001: 1 c Copernicus Gesellschaft 2001 Status of the Milagro Gamma Ray Observatory

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    , active galactic nuclei (AGN), and gamma ray bursts (GRB). In addition, more exotic sources like Gamma Ray Observatory, located at an altitude of 8,600 feet in the Jemez Mountains of New Mexico for sources of TeV gamma rays. It is uniquely capable of search- ing for transient sources of VHE gamma rays

  9. Measurements and implications of the relationship between lightning and terrestrial gamma ray flashes

    E-Print Network [OSTI]

    Cummer, Steven A.

    the discovery of short bursts of gamma rays originating from Earth, called terrestrial gamma ray flashes (TGFsMeasurements and implications of the relationship between lightning and terrestrial gamma ray associated with 26 terrestrial gamma ray flashes (TGFs) recorded by the RHESSI satellite over the Caribbean

  10. Results from the Milagro Gamma-Ray Observatory E. Blaufuss a

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    V emission from the galactic plane, and a search for transient emission above 100 GeV from gamma ray bursts- clei (AGN), supernova remnants and gamma-ray bursts (GRB). Gamma rays are also produced when high1 Results from the Milagro Gamma-Ray Observatory E. Blaufuss a for the Milagro Collaboration

  11. Gamma Ray Bursts as seen by a Giant Air Shower Array

    E-Print Network [OSTI]

    C. O. Escobar; P. L. Da Silva; R. A. Vázquez

    1997-12-19T23:59:59.000Z

    The potentiality of a Giant Shower Array to low energy gamma rays from gamma ray bursts is discussed. Effective areas are calculated for different scenarios and the results are encouraging. If gamma ray bursts have a spectrum which continues in the high energy gamma ray region, the Pierre Auger Observatory will be able to detect it.

  12. Delayed Gamma-Ray Spectroscopy for Spent Nuclear Fuel Assay

    SciTech Connect (OSTI)

    Campbell, Luke W.; Hunt, Alan W.; Ludewigt, Bernhard A.; Mozin, Vladimir V.

    2012-04-01T23:59:59.000Z

    High-energy, beta-delayed gamma-ray spectroscopy is investigated as a non-destructive assay technique for the determination of plutonium mass in spent nuclear fuel. This approach exploits the unique isotope-specific signatures contained in the delayed gamma-ray emission spectra detected following active interrogation with an external neutron source. A high fidelity modeling approach is described that couples radiation transport, analytical decay/depletion, and a newly developed gamma-ray emission source reconstruction code. Initially simulated and analyzed was a “one-pass” delayed gamma-ray assay that focused on the long-lived signatures. Also presented are the results of an independent study that investigated “pulsed mode” measurements, to capture the more isotope-specific, short-lived signatures. Initial modeling results outlined in this paper suggest that delayed gamma-ray assay of spent nuclear fuel assemblies can be accomplished with a neutron generator of sufficient strength and currently available gamma-ray detectors.

  13. Milagro - A TeV Observatory for Gamma Ray Bursts

    SciTech Connect (OSTI)

    Dingus, B.L. [Los Alamos National Laboratory (United States)

    2004-09-28T23:59:59.000Z

    Milagro is a large field of view ({approx} 2 sr), high duty cycle ({approx}90%), ground-based observatory sensitive to gamma-rays above {approx}100 GeV. This unique detector is ideal for observing the highest energy gamma-rays from gamma-ray bursts. The highest energy gamma rays supply very strong constraints on the nature of gamma-ray burst sources as well as fundamental physics. Because the highest energy gamma-rays are attenuated by pair production with the extragalactic infrared background light, Milagro's sensitivity decreases rapidly for bursts with redshift > 0.5. While only 10 % of bursts have been measured to be within z=0.5, these bursts are very well studied at all wavelengths resulting in the most complete understanding of GRB phenomena. Milagro has sufficient sensitivity in units of E2 dN/dE to detect VHE luminosities lower than the observed luminosities at {approx} 100 keV for these nearby bursts. Therefore, the launch of SWIFT and its ability to localize and measure redshifts of many bursts points to great future possibilities.

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

    E-Print Network [OSTI]

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

    2015-01-01T23:59:59.000Z

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

  15. Cluster of Gamma-ray Bursts - Image of a Source. Catalog of Clusters (Sources) of Gamma-ray Bursts

    E-Print Network [OSTI]

    A. V. Kuznetsov

    2001-11-01T23:59:59.000Z

    The clusters of gamma-ray bursts are considered which are assumed to be images of the repeated gamma-ray burst (GRB) sources. It is shown, that localization of the cosmic gamma-ray burst sources (GBS) is determined by the clusters of GRBs. About 100 candidates in sources are presented in the form of the catalog, which is compiled relying on the base of the BATSE data up to middle of 2000. Gamma-ray bursts (from 5 to 13) of a cluster that display a source do not coincide in their position. The catalog table containing basic information about the GRB sources yields the possibility to research the GBS properties and their identification. The birth of GRBs in the clusters allows predicting the appearance of GRBs both in time and space. Most general properties of the supposed GRB sources are discussed. An attempt to compile the first GRB source catalog is made.

  16. HETEROGENEITY IN SHORT GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Norris, Jay P. [Physics and Astronomy Department, University of Denver, Denver, CO 80208 (United States); Gehrels, Neil [Astroparticle Physics Laboratory, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Scargle, Jeffrey D. [Space Science and Astrobiology Division, NASA/Ames Research Center, Moffett Field, CA 94035-1000 (United States)

    2011-07-01T23:59:59.000Z

    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 {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/X-Ray Telescope (XRT). The median flux of the initial XRT detections for EE bursts ({approx}6x10{sup -10} erg cm{sup -2} s{sup -1}) is {approx}>20x brighter than for non-EE bursts, and the median X-ray afterglow duration for EE bursts ({approx}60,000 s) is {approx}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.

  17. Fast radio burst/gamma-ray burst cosmography

    SciTech Connect (OSTI)

    Gao, He; Zhang, Bing [Department of Physics and Astronomy, University of Nevada Las Vegas, NV 89154 (United States); Li, Zhuo, E-mail: gaohe@physics.unlv.edu, E-mail: zhang@physics.unlv.edu, E-mail: zhuo.li@pku.edu.cn [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China)

    2014-06-20T23:59:59.000Z

    Recently, both theoretical arguments and observational evidence suggested that a small fraction of fast radio bursts (FRBs) could be associated with gamma-ray bursts (GRBs). If such FRB/GRB association systems are commonly detected in the future, the combination of dispersion measures (DM) derived from FRBs and redshifts derived from GRBs makes these systems a plausible tool to conduct cosmography. We quantify uncertainties in deriving the redshift-dependent DM{sub IGM} as a function of z and test how well dark energy models can be constrained with Monte Carlo simulations. We show that with several tens of FRB/GRB systems potentially detected in a decade or so, one may reach reasonable constraints on wCDM models. When combined with Type Ia supernova (SN Ia) data, unprecedented constraints on the dark energy equation of state may be achieved, thanks to the prospects of detecting FRB/GRB systems at relatively high redshifts. The ratio between the mean value and luminosity distance (D {sub L}(z)) is insensitive to dark energy models. This gives the prospect of applying SN Ia data to calibrate using a relatively small sample of FRB/GRB systems, allowing a reliable constraint on the baryon inhomogeneity distribution as a function of redshift. The methodology developed in this paper can also be applied if the FRB redshifts can be measured by other means. Some caveats of putting this method into practice are also discussed.

  18. Testing the millisecond pulsar scenario of the Galactic center gamma-ray excess with very high energy gamma-rays

    E-Print Network [OSTI]

    Qiang Yuan; Kunihito Ioka

    2015-02-09T23:59:59.000Z

    The recent analyses of the Fermi Large Area Telescope data show an extended GeV $\\gamma$-ray excess on top of the expected diffuse background in the Galactic center region, which can be explained with annihilating dark matter or a population of millisecond pulsars (MSPs). We propose to observe the very high energy $\\gamma$-rays for distinguishing the MSP scenario from the dark matter scenario. The GeV $\\gamma$-ray MSPs should release most energy to the relativistic $e^{\\pm}$ wind, which will diffuse in the Galaxy and radiate TeV $\\gamma$-rays through inverse Compton scattering and bremsstrahlung processes. By calculating the spectrum and spatial distribution, we show that such emission is detectable with the next generation very high energy $\\gamma$-ray observatory, the Cherenkov Telescope Array (CTA), under reasonable model parameters. It is essential to search for the multi-wavelength counterparts to the GeV $\\gamma$-ray excess for solving this mystery in the high energy universe.

  19. NEW FERMI-LAT EVENT RECONSTRUCTION REVEALS MORE HIGH-ENERGY GAMMA RAYS FROM GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    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)

    2013-09-01T23:59:59.000Z

    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.

  20. AN INDEPENDENT MEASUREMENT OF THE INCIDENCE OF Mg II ABSORBERS ALONG GAMMA-RAY BURST SIGHT LINES: THE END OF THE MYSTERY?

    E-Print Network [OSTI]

    Cucchiara, A.

    In 2006, Prochter et al. reported a statistically significant enhancement of very strong Mg II absorption systems intervening the sight lines to gamma-ray bursts (GRBs) relative to the incidence of such absorption along ...

  1. A Combined Neutron and Gamma-Ray Multiplicity Counter Based on Liquid Scintillation Detectors

    SciTech Connect (OSTI)

    Andreas Enqvist; Marek Flaska; Jennifer Dolan; David L. Chichester; Sara A. Pozzi

    2011-10-01T23:59:59.000Z

    Multiplicity counters for neutron assay have been extensively used in materials control and accountability for nonproliferation and nuclear safeguards. Typically, neutron coincidence counters are utilized in these fields. In this work, we present a measurement system that makes use not only of neutron (n) multiplicity counting but also of gamma-ray (g) multiplicity counting and the combined higher-order multiples containing both neutrons and gamma rays. The benefit of this approach is in using both particle types available from the sample, leading to a reduction in measurement times needed when using more measurables. We present measurement results of n, g, nn, ng, gg, nnn, nng, ngg, and ggg multiples emitted by Mixed-Oxide (MOX) samples measured at Idaho National Laboratory (INL). The MOX measurement is compared to initial validation of the detection system done using a 252Cf source. The dual radiation measuring system proposed here uses extra measurables to improve the statistics when compared to a neutron-only system and allows for extended analysis and interpretation of sample parameters. New challenges such as the effect of very high intrinsic gamma-ray sources in the case of MOX samples is discussed. Successful measurements of multiples rates can be performed also when using high-Z shielding.

  2. THE ORIGIN OF GAMMA RAYS FROM GLOBULAR CLUSTERS

    SciTech Connect (OSTI)

    Cheng, K. S. [Department of Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Chernyshov, D. O. [Moscow Institute of Physics and Technology, Institutskii lane, 141700 Moscow Region, Dolgoprudnii (Russian Federation); Dogiel, V. A. [I. E. Tamm Theoretical Physics Division of P. N. Lebedev Institute, Leninskii pr, 53, 119991 Moscow (Russian Federation); Hui, C. Y. [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of); Kong, A. K. H. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China)

    2010-11-10T23:59:59.000Z

    Fermi has detected gamma-ray emission from eight globular clusters (GCs). It is commonly believed that the energy sources of these gamma rays are millisecond pulsars (MSPs) inside GCs. Also it has been standard to explain the spectra of most Fermi Large Area Telescope pulsars including MSPs resulting from the curvature radiation (CR) of relativistic electrons/positrons inside the pulsar magnetosphere. Therefore, gamma rays from GCs are expected to be the collection of CR from all MSPs inside the clusters. However, the angular resolution is not high enough to pinpoint the nature of the emission. In this paper, we calculate the gamma rays produced by the inverse Compton (IC) scattering between relativistic electrons/positrons in the pulsar wind of MSPs in the GCs and background soft photons including cosmic microwave/relic photons, background star lights in the clusters, the galactic infrared photons, and the galactic star lights. We show that the gamma-ray spectrum from 47 Tucanae can be explained equally well by upward scattering of either the relic photons, the galactic infrared photons, or the galactic star lights, whereas the gamma-ray spectra from the other seven GCs are best fitted by the upward scattering of either the galactic infrared photons or the galactic star lights. We also find that the observed gamma-ray luminosity is correlated better with the combined factor of the encounter rate and the background soft photon energy density. Therefore, the IC scattering may also contribute to the observed gamma-ray emission from GCs detected by Fermi in addition to the standard CR process. Furthermore, we find that the emission region of high-energy photons from GCs produced by the IC scattering is substantially larger than the cores of GCs with a radius >10 pc. The diffuse radio and X-rays emitted from GCs can also be produced by the synchrotron radiation and IC scattering, respectively. We suggest that future observations including radio, X-rays, and gamma rays with energy higher than 10 GeV and better angular resolution can provide better constraints for the models.

  3. Gamma-Ray Bursts from Radio-Quiet Quasars

    E-Print Network [OSTI]

    N. Schartel; H. Andernach; J. Greiner

    1996-12-16T23:59:59.000Z

    We study positional coincidences between gamma-ray bursts in the BATSE 3B catalogue and quasars/AGN taken from the Veron-Cetty & Veron compilation. For most classes of AGN, for BL Lac objects and for radio-loud quasars, we find no excess coincidences above random expectation, and we give upper limits for their burst emission rate. However, surprising evidence is found for a positional correlation between gamma-ray bursts and radio-quiet quasars. A total of 134 selected bursts with a position error radius 99.7% to be associated with each other. An analysis of a smaller sample of well-localized interplanetary network gamma-ray burst positions supports this result. This correlation strongly favours the cosmological origin of gamma-ray bursts and enables to estimate its distance scale. The average luminosity of those gamma-ray bursts which we associate directly with radio-quiet quasars is of the order of 4*10^52 erg (assuming isotropic emission).

  4. Afterglows as Diagnostics of Gamma Ray Burst Beaming

    E-Print Network [OSTI]

    James E. Rhoads

    1997-12-03T23:59:59.000Z

    If gamma ray bursts are highly collimated, radiating into only a small fraction of the sky, the energy requirements of each event may be reduced by several (up to 4 - 6) orders of magnitude, and the event rate increased correspondingly. The large Lorentz factors (Gamma > 100) inferred from GRB spectra imply relativistic beaming of the gamma rays into an angle 1/Gamma. We are at present ignorant of whether there are ejecta outside this narrow cone. Afterglows allow empirical tests of whether GRBs are well-collimated jets or spherical fireballs. The bulk Lorentz factor decreases and radiation is beamed into an ever increasing solid angle as the burst remnant expands. It follows that if gamma ray bursts are highly collimated, many more optical and radio transients should be observed without associated gamma rays than with them. In addition, a burst whose ejecta are beamed into angle zeta undergoes a qualitative change in evolution when Gamma < 1/zeta: Before this, Gamma ~ r^{-3/2}, while afterwards, Gamma decays exponentially with r. This change results in a potentially observable break in the afterglow light curve. Successful application of either test would eliminate the largest remaining uncertainty in the energy requirements and space density of gamma ray bursters.

  5. HAND-HELD GAMMA-RAY SPECTROMETER BASED ON HIGH-EFFICIENCY FRISCH-RING CdZnTe DETECTORS.

    SciTech Connect (OSTI)

    CUI,Y.

    2007-05-01T23:59:59.000Z

    Frisch-ring CdZnTe detectors have demonstrated good energy resolution, el% FWHM at 662 keV, and good efficiency for detecting gamma rays. This technique facilitates the application of CdZnTe materials for high efficiency gamma-ray detection. A hand-held gamma-ray spectrometer based on Frisch-ring detectors is being designed at Brookhaven National Laboratory. It employs an 8x8 CdZnTe detector array to achieve a high volume of 19.2 cm3, so that detection efficiency is significantly improved. By using the front-end ASICs developed at BNL, this spectrometer has a small profile and high energy resolution. The spectrometer includes signal processing circuit, digitization and storage circuit, high-voltage module, and USB interface. In this paper, we introduce the details of the system structure and report our test results with it.

  6. The exceptionally powerful TeV gamma-ray emitters in the Large Magellanic Cloud

    E-Print Network [OSTI]

    :,; Aharonian, F; Benkhali, F Ait; Akhperjanian, A G; Angüner, E O; Backes, M; Balenderan, S; Balzer, A; Barnacka, A; Becherini, Y; Becker-Tjus, J; Berge, D; Bernhard, S; Bernlöhr, K; Birsin, E; Biteau, J; Böttcher, M; Boisson, C; Bolmont, J; Bordas, P; Bregeon, J; Brun, F; Brun, P; Bryan, M; Bulik, T; Carrigan, S; Casanova, S; Chadwick, P M; Chakraborty, N; Chalme-Calvet, R; Chaves, R C G; Chrétien, M; Colafrancesco, S; Cologna, G; Conrad, J; Couturier, C; Cui, Y; Dalton, M; Davids, I D; Degrange, B; Deil, C; de Wilt, P; Djannati-Ataï, A; Domainko, W; Donath, A; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Edwards, T; Egberts, K; Eger, P; Espigat, P; Farnier, C; Fegan, S; Feinstein, F; Fernandes, M V; Fernandez, D; Fiasson, A; Fontaine, G; Förster, A; ling, M Füß; Gabici, S; Gajdus, M; Gallant, Y A; Garrigoux, T; Giavitto, G; Giebels, B; Glicenstein, J F; Gottschall, D; Grondin, M -H; Grudzi?ska, M; Hadasch, D; Häffner, S; Hahn, J; Harris, J; Heinzelmann, G; Henri, G; Hermann, G; Hervet, O; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Ivascenko, A; Jacholkowska, A; Jahn, C; Jamrozy, M; Janiak, M; Jankowsky, F; Jung, I; Kastendieck, M A; Katarzy?ski, K; Katz, U; Kaufmann, S; Khélifi, B; Kieffer, M; Klepser, S; Klochkov, D; Klu?niak, W; Kolitzus, D; Komin, Nu; Kosack, K; Krakau, S; Krayzel, F; Krüger, P P; Laffon, H; Lamanna, G; Lefaucheur, J; Lefranc, V; Lemière, A; Lemoine-Goumard, M; Lenain, J -P; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Marx, R; Maurin, G; Maxted, N; Mayer, M; McComb, T J L; Méhault, J; Meintjes, P J; Menzler, U; Meyer, M; Mitchell, A M W; Moderski, R; Mohamed, M; Morå, K; Moulin, E; Murach, T; de Naurois, M; Niemiec, J; Nolan, S J; Oakes, L; Odaka, H; Ohm, S; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Parsons, R D; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Poon, H; Pühlhofer, G; Punch, M; Quirrenbach, A; Raab, S; Reichardt, I; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Rob, L; Romoli, C; Rosier-Lees, S; Rowell, G; Rudak, B; Sahakian, C B Rulten V; Salek, D; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schüssler, F; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sol, H; Spanier, F; Spengler, G; Spies, F; Stawarz, ?; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Tavernet, J -P; Tavernier, T; Taylor, A M; Terrier, R; Tluczykont, M; Trichard, C; Valerius, K; van Eldik, C; van Soelen, B; Vasileiadis, G; Veh, J; Venter, C; Viana, A; Vincent, P; Vink, J; Völk, H J; Volpe, F; Vorster, M; Vuillaume, T; Wagner, S J; Wagner, P; Wagner, R M; Ward, M; Weidinger, M; Weitzel, Q; White, R; Wierzcholska, A; Willmann, P; Wörnlein, A; Wouters, D; Yang, R; Zabalza, V; Zaborov, D; Zacharias, M; Zdziarski, A A; Zech, A; Zechlin, H -S

    2015-01-01T23:59:59.000Z

    The Large Magellanic Cloud, a satellite galaxy of the Milky Way, has been observed with the High Energy Stereoscopic System (H.E.S.S.) above an energy of 100 billion electron volts for a deep exposure of 210 hours. Three sources of different types were detected: the pulsar wind nebula of the most energetic pulsar known N 157B, the radio-loud supernova remnant N 132D and the largest non-thermal X-ray shell - the superbubble 30 Dor C. The unique object SN 1987A is, surprisingly, not detected, which constrains the theoretical framework of particle acceleration in very young supernova remnants. These detections reveal the most energetic tip of a gamma-ray source population in an external galaxy, and provide via 30 Dor C the unambiguous detection of gamma-ray emission from a superbubble.

  7. Gamma Ray Bursts, The Principle of Relative Locality and Connection Normal Coordinates

    E-Print Network [OSTI]

    A. E. McCoy

    2012-01-04T23:59:59.000Z

    The launch of the Fermi telescope in 2008 opened up the possibility of measuring the energy dependence of the speed of light by considering the time delay in the arrival of gamma ray bursts emitted simultaneously from very distant sources.The expected time delay between the arrival of gamma rays of significantly different energies as predicted by the framework of relative locality has already been calculated in Riemann normal coordinates. In the following, we calculate the time delay in more generality and then specialize to the connection normal coordinate system as a check that the results are coordinate independent. We also show that this result does not depend on the presence of torsion.

  8. EPISODIC JETS AS THE CENTRAL ENGINE OF GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Yuan Feng [Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Zhang Bing, E-mail: fyuan@shao.ac.cn, E-mail: zhang@physics.unlv.edu [Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, NV 89154 (United States)

    2012-09-20T23:59:59.000Z

    Most gamma-ray bursts (GRBs) have erratic light curves, which demand that the GRB central engine launches an episodic outflow. Recent Fermi observations of some GRBs indicate a lack of the thermal photosphere component as predicted by the baryonic fireball model, which suggests a magnetic origin of GRBs. Given that powerful episodic jets have been observed along with continuous jets in other astrophysical black hole systems, here we propose an intrinsically episodic, magnetically dominated jet model for the GRB central engine. Accumulation and eruption of free magnetic energy in the corona of a differentially rotating, turbulent accretion flow around a hyperaccreting black hole lead to ejections of episodic, magnetically dominated plasma blobs. These blobs are accelerated magnetically, collide with each other at large radii, trigger rapid magnetic reconnection and turbulence, efficient particle acceleration, and radiation, and power the observed episodic prompt gamma-ray emission from GRBs.

  9. Constraining the extension of a possible gamma-ray halo of 3C 279 from 2008-2014 solar occultations

    E-Print Network [OSTI]

    Kotelnikov, Egor; Troitsky, Sergey

    2014-01-01T23:59:59.000Z

    The angular extension of the gamma-ray image of 3C 279 may be constrained by studying its solar occultations as suggested by Fairbairn et al. (2010). We perform this kind of analysis for seven occultations observed by Fermi-LAT in 2008-2014, using the Fermi-LAT Solar System tools. The results are interpreted in terms of models with extended gamma-ray halo of 3C 279; first constraints on the size and the flux of the halo are reported.

  10. Delayed energy injection model for gamma-ray burst afterglows

    SciTech Connect (OSTI)

    Geng, J. J.; Huang, Y. F.; Yu, Y. B. [Department of Astronomy, Nanjing University, Nanjing 210093 (China); Wu, X. F., E-mail: hyf@nju.edu.cn, E-mail: xfwu@pmo.ac.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2013-12-10T23:59:59.000Z

    The shallow decay phase and flares in the afterglows of gamma-ray bursts (GRBs) are widely believed to be associated with the later activation of the central engine. Some models of energy injection involve a continuous energy flow since the GRB trigger time, such as the magnetic dipole radiation from a magnetar. However, in the scenario involving a black hole accretion system, the energy flow from the fall-back accretion may be delayed for a fall-back time ?t {sub fb}. Thus, we propose a delayed energy injection model. The delayed energy would cause a notable rise to the Lorentz factor of the external shock, which will 'generate' a bump in the multiple band afterglows. If the delayed time is very short, our model degenerates to the previous models. Our model can explain the significant re-brightening in the optical and infrared light curves of GRB 081029 and GRB 100621A. A considerable fall-back mass is needed to provide the later energy; this indicates that GRBs accompanied with fall-back material may be associated with a low energy supernova so that the fraction of the envelope can survive during eruption. The fall-back time can give meaningful information on the properties of GRB progenitor stars.

  11. Fermi GBM Observations of Terrestrial Gamma-ray Flashes

    SciTech Connect (OSTI)

    Briggs, Michael S. [CSPAR, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States)

    2011-09-21T23:59:59.000Z

    Terrestrial Gamma-ray Flashes are short pulses of energetic radiation associated with thunderstorms and lightning. While the Gamma-ray Burst Monitor (GBM) on Fermi was designed to observe gamma-ray bursts, its large BGO detectors are excellent for observing TGFs. Using GBM, TGF pulses are seen to either be symmetrical or have faster rise time than fall times. Some TGFs are resolved into double, partially overlapping pulses. Using ground-based radio observations of lightning from the World Wide Lightning Location Network (WWLLN), TGFs and their associated lightning are found to be simultaneous to {approx_equal}40 {mu} s. The lightning locations are typically within 300 km of the sub-spacecraft point.

  12. Gamma Ray Bursts as Possible High Energy Sources

    E-Print Network [OSTI]

    Charles D. Dermer

    2005-12-06T23:59:59.000Z

    Gamma-ray bursts are known to be sources of high-energy gamma rays, and are likely to be sources of high-energy cosmic rays and neutrinos. Following a short review of observations of GRBs at multi-MeV energies and above, the physics of leptonic and hadronic models of GRBs is summarized. Evidence for two components in BATSE and EGRET/TASC data suggest that GRBs are sources of high-energy cosmic rays. GLAST observations will reveal the high-energy gamma-ray power and energy releases from GRBs, and will provide detailed knowledge of anomalous high-energy emission components, but confirmation of cosmic ray acceleration must await 100 TeV -- PeV neutrino detection from GRBs.

  13. Gamma-Ray Bursts and Topology of the Universe

    E-Print Network [OSTI]

    Marek Biesiada

    1993-10-04T23:59:59.000Z

    In this letter we propose a physical explanation for recently reported correlations between pairs of close and antipodal gamma-ray bursts from publicly available BATSE catalogue. Our model is based on the cosmological scenario in which bursters are located at cosmological distances of order of 0.5--2~Gpc. Observed distribution of gamma-ray bursts strongly suports this assumption. If so gamma-ray bursts may provide a very good probe for investigating the topological structure of the Universe. We notice that correlation between antipodal events may in fact indicate that we live in the so called Ellis' small universe which has Friedman-Roberston-Walker metric structure and nontrivial topology.

  14. Linking Short Gamma Ray Bursts and their Host Galaxies

    E-Print Network [OSTI]

    James E. Rhoads

    2008-07-16T23:59:59.000Z

    The luminosities of short gamma ray burst host galaxies are anticorrelated with both the isotropic equivalent gamma ray energy and the gamma ray luminosity of the explosions. Observational selection effects only strengthen the significance of this correlation. The correlation may indicate that there are two physically distinct groups of SGRBs. If so, it requires that the more luminous class of explosions be associated with the younger class of progenitors. Alternatively, it could be due to a continuous distribution of burst and host properties. As one possible explanation, we find that the effect of binary neutron star masses on inspiral time and energy reservoir produces a correlation of the appropriate sign, but does not automatically reproduce the correlation slope or the full range of SGRB energy scales. Any future model of SGRB progenitors needs to reproduce this correlation.

  15. What Are Gamma-Ray Bursts -- The Unique Role of Very High Energy Gamma-Ray Observations

    E-Print Network [OSTI]

    Williams, D A; Baring, M G; Buckley, J; Connaughton, V; Coppi, P; Dermer, C; Digel, S; Dingus, B; Fryer, C; Gehrels, N; Granot, J; Horan, D; Katz, J I; Mészáros, P; Norris, J; Parkinson, P Saz; Peér, A; Razzaque, S; Sinnis, G; Wang, X Y; Weekes, T C; Zhang, B

    2009-01-01T23:59:59.000Z

    Gamma-ray bursts (GRBs) have been an enigma since their discovery forty years ago. However, considerable progress unraveling their mysteries has been made in recent years. Developments in observations, theory, and instrumentation have prepared the way so that the next decade can be the one in which we finally answer the question, "What are gamma-ray bursts?" This question encompasses not only what the progenitors are that produce the GRBs, but also how the enormous luminosity of the GRBs, concentrated in gamma rays, is achieved. Observations across the electromagnetic spectrum, from both the ground and space, will be required to fully tackle this important question. This white paper, mostly distilled from a recent study commissioned by the Division of Astrophysics of the American Physical Society, focuses on what very high energy (~100 GeV and above) gamma-ray observations can contribute. Very high energy gamma rays probe the most extreme high energy particle populations in the burst environment, testing mode...

  16. On the origin of \\gamma-ray emission in \\eta\\ Carina

    E-Print Network [OSTI]

    Ohm, S; Hinton, J A; Parkin, E R

    2015-01-01T23:59:59.000Z

    \\eta\\ Car is the only colliding-wind binary for which high-energy \\gamma\\ rays are detected. Although the physical conditions in the shock region change on timescales of hours to days, the variability seen at GeV energies is weak and on significantly longer timescales. The \\gamma-ray spectrum exhibits two features that can be interpreted as emission from the shocks on either side of the contact discontinuity. Here we report on the first time-dependent modelling of the non-thermal emission in \\eta\\ Car. We find that emission from primary electrons is likely not responsible for the \\gamma-ray emission, but accelerated protons interacting with the dense wind material can explain the observations. In our model, efficient acceleration is required at both shocks, with the primary side acting as a hadron calorimeter, whilst on the companion side acceleration is limited by the flow time out of the system, resulting in changing acceleration conditions. The system therefore represents a unique laboratory for the explor...

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

    SciTech Connect (OSTI)

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

    2007-02-01T23:59:59.000Z

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

  18. A Gamma-Ray Bursts' Fluence-Duration Correlation

    E-Print Network [OSTI]

    Istvan Horvath; Lajos G. Balazs; Peter Meszaros; Zsolt Bagoly; Attila Meszaros

    2005-08-01T23:59:59.000Z

    We present an analysis indicating that there is a correlation between the fluences and the durations of gamma-ray bursts, and provide arguments that this reflects a correlation between the total emitted energies and the intrinsic durations. For the short (long) bursts the total emitted energies are roughly proportional to the first (second) power of the intrinsic duration. This difference in the energy-duration relationship is statistically significant, and may provide an interesting constraint on models aiming to explain the short and long gamma-ray bursts.

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

    E-Print Network [OSTI]

    Axelsson, M

    2015-01-01T23:59:59.000Z

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

  20. Correlation between Gamma-Ray bursts and Gravitational Waves

    E-Print Network [OSTI]

    P. Tricarico; A. Ortolan; A. Solaroli; G. Vedovato; L. Baggio; M. Cerdonio; L. Taffarello; J. Zendri; R. Mezzena; G. A. Prodi; S. Vitale; P. Fortini; M. Bonaldi; P. Falferi

    2001-01-05T23:59:59.000Z

    The cosmological origin of $\\gamma$-ray bursts (GRBs) is now commonly accepted and, according to several models for the central engine, GRB sources should also emit at the same time gravitational waves bursts (GWBs). We have performed two correlation searches between the data of the resonant gravitational wave detector AURIGA and GRB arrival times collected in the BATSE 4B catalog. No correlation was found and an upper limit \\bbox{$h_{\\text{RMS}} \\leq 1.5 \\times 10^{-18}$} on the averaged amplitude of gravitational waves associated with $\\gamma$-ray bursts has been set for the first time.

  1. Gamma-ray Burst Models: General Requirements and Predictions

    E-Print Network [OSTI]

    P. Meszaros

    1995-02-21T23:59:59.000Z

    Whatever the ultimate energy source of gamma-ray bursts turns out to be, the resulting sequence of physical events is likely to lead to a fairly generic, almost unavoidable scenario: a relativistic fireball that dissipates its energy after it has become optically thin. This is expected both for cosmological and halo distances. Here we explore the observational motivation of this scenario, and the consequences of the resulting models for the photon production in different wavebands, the energetics and the time structure of classical gamma-ray bursters.

  2. X-ray afterglows from gamma-ray bursts

    E-Print Network [OSTI]

    M. Tavani

    1997-03-24T23:59:59.000Z

    We consider possible interpretations of the recently detected X- ray afterglow from the gamma-ray burst source GRB 970228. Cosmological and Galactic models of gamma-ray bursts predict different flux and spectral evolution of X-ray afterglows. We show that models based on adiabatic expansion of relativistic forward shocks require very efficient particle energization or post-burst re-acceleration during the expansion. Cooling neutron star models predict a very distinctive spectral and flux evolution that can be tested in current X-ray data.

  3. GAMQUEST, A computer program to identify gamma rays

    SciTech Connect (OSTI)

    Brown, E.

    1994-05-01T23:59:59.000Z

    This paper describes the application of the computer program GAMQUEST to the study of gamma-ray spectra. The program is especially suited to the analysis of samples produced by neutron activation, and of environmental samples containing radioactive pollutants. GAMQUEST searches a large database (with data for over 60,000 gamma rays) to identify the various spectral lines from samples. The program runs on the VAX/6610 computer cluster of the Lawrence Berkeley Laboratory, and can be accessed from individual accounts or through Hepnet, Internet, or World Wide Web networks.

  4. Large-Scale Anisotropy of EGRET Gamma Ray Sources

    E-Print Network [OSTI]

    Luis Anchordoqui; Thomas McCauley; Thomas Paul; Olaf Reimer; Diego F. Torres

    2005-06-24T23:59:59.000Z

    In the course of its operation, the EGRET experiment detected high-energy gamma ray sources at energies above 100 MeV over the whole sky. In this communication, we search for large-scale anisotropy patterns among the catalogued EGRET sources using an expansion in spherical harmonics, accounting for EGRET's highly non-uniform exposure. We find significant excess in the quadrupole and octopole moments. This is consistent with the hypothesis that, in addition to the galactic plane, a second mid-latitude (5^{\\circ} < |b| < 30^{\\circ}) population, perhaps associated with the Gould belt, contributes to the gamma ray flux above 100 MeV.

  5. The lowest-mass stellar black holes: catastrophic death of neutron stars in gamma-ray bursts

    E-Print Network [OSTI]

    K. Belczynski; R. O'Shaughnessy; V. Kalogera; F. Rasio; R. Taam; T. Bulik

    2008-04-16T23:59:59.000Z

    Mergers of double neutron stars are considered the most likely progenitors for short gamma-ray bursts. Indeed such a merger can produce a black hole with a transient accreting torus of nuclear matter (Lee & Ramirez-Ruiz 2007, Oechslin & Janka 2006), and the conversion of a fraction of the torus mass-energy to radiation can power a gamma-ray burst (Nakar 2006). Using available binary pulsar observations supported by our extensive evolutionary calculations of double neutron star formation, we demonstrate that the fraction of mergers that can form a black hole -- torus system depends very sensitively on the (largely unknown) maximum neutron star mass. We show that the available observations and models put a very stringent constraint on this maximum mass under the assumption that a black hole formation is required to produce a short gamma-ray burst in a double neutron star merger. Specifically, we find that the maximum neutron star mass must be within 2 - 2.5 Msun. Moreover, a single unambiguous measurement of a neutron star mass above 2.5 Msun would exclude a black hole -- torus central engine model of short gamma-ray bursts in double neutron star mergers. Such an observation would also indicate that if in fact short gamma-ray bursts are connected to neutron star mergers, the gamma-ray burst engine is best explained by the lesser known model invoking a highly magnetized massive neutron star (e.g., Usov 1992; Kluzniak & Ruderman 1998; Dai et al. 2006; Metzger, Quataert & Thompson 2007).

  6. Modeling the Production of Beta-Delayed Gamma Rays for the Detection of Special Nuclear Materials

    SciTech Connect (OSTI)

    Hall, J M; Pruet, J A; Brown, D A; Descalle, M; Hedstrom, G W; Prussin, S G

    2005-02-14T23:59:59.000Z

    The objective of this LDRD project was to develop one or more models for the production of {beta}-delayed {gamma} rays following neutron-induced fission of a special nuclear material (SNM) and to define a standardized formatting scheme which will allow them to be incorporated into some of the modern, general-purpose Monte Carlo transport codes currently being used to simulate inspection techniques proposed for detecting fissionable material hidden in sea-going cargo containers. In this report, we will describe a Monte Carlo model for {beta}-delayed {gamma}-ray emission following the fission of SNM that can accommodate arbitrary time-dependent fission rates and photon collection histories. The model involves direct sampling of the independent fission yield distributions of the system, the branching ratios for decay of individual fission products and spectral distributions representing photon emission from each fission product and for each decay mode. While computationally intensive, it will be shown that this model can provide reasonably detailed estimates of the spectra that would be recorded by an arbitrary spectrometer and may prove quite useful in assessing the quality of evaluated data libraries and identifying gaps in the libraries. The accuracy of the model will be illustrated by comparing calculated and experimental spectra from the decay of short-lived fission products following the reactions {sup 235}U(n{sub th}, f) and {sup 239}Pu(n{sub th}, f). For general-purpose transport calculations, where a detailed consideration of the large number of individual {gamma}-ray transitions in a spectrum may not be necessary, it will be shown that a simple parameterization of the {gamma}-ray source function can be defined which provides high-quality average spectral distributions that should suffice for calculations describing photons being transported through thick attenuating media. Finally, a proposal for ENDF-compatible formats that describe each of the models and allow for their straightforward use in Monte Carlo codes will be presented.

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

    SciTech Connect (OSTI)

    Levesque, Emily M.; Kewley, Lisa J. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Soderberg, Alicia M.; Berger, Edo, E-mail: emsque@ifa.hawaii.ed, E-mail: kewley@ifa.hawaii.ed, E-mail: asoderbe@cfa.harvard.ed, E-mail: eberger@cfa.harvard.ed [Smithsonian Astrophysical Observatory, 60 Garden St., MS-20, Cambridge, MA 02138 (United States)

    2010-12-10T23:59:59.000Z

    We compare the redshifts, host galaxy metallicities, and isotropic (E{sub {gamma}},iso) and beaming-corrected (E{sub {gamma}}) gamma-ray energy release of 16 long-duration gamma-ray bursts (LGRBs) at z < 1. From this comparison, we find no statistically significant correlation between host metallicity and redshift, E{sub {gamma}},iso, or E{sub {gamma}}. 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.

  8. Observations of Gamma-ray Bursts with ASTRO-H and Fermi

    E-Print Network [OSTI]

    Ohno, M; Tashiro, M S; Ueno, H; Yonetoku, D; Sameshima, H; Takahashi, T; Seta, H; Mushotzky, R; Yamaoka, K

    2015-01-01T23:59:59.000Z

    ASTRO-H, the sixth Japanese X-ray observatory, which is scheduled to be launched by the end of Japanese fiscal year 2015 has a capability to observe the prompt emission from Gamma-ray Bursts (GRBs) utilizing BGO active shields for the soft gamma-ray detector (SGD). The effective area of the SGD shield detectors is very large and its data acquisition system is optimized for short transients such as short GRBs. Thus, we expect to perform more detailed time-resolved spectral analysis with a combination of ASTRO-H and Fermi LAT/GBM to investigate the gamma-ray emission mechanism of short GRBs. In addition, the environment of the GRB progenitor should be a remarkable objective from the point of view of the chemical evolution of high-z universe. If we can maneuver the spacecraft to the GRBs, we can perform a high-resolution spectroscopy of the X-ray afterglow of GRBs utilizing the onboard micro calorimeter and X-ray CCD camera.

  9. Coincidence searches of gravitational waves and short gamma-ray bursts

    E-Print Network [OSTI]

    Andrea Maselli; Valeria Ferrari

    2014-05-28T23:59:59.000Z

    Black-hole neutron-star coalescing binaries have been invoked as one of the most suitable scenario to explain the emission of short gamma-ray bursts. Indeed, if the black-hole which forms after the merger, is surrounded by a massive disk, neutrino annihilation processes may produce high-energy and collimated electromagnetic radiation. In this paper, we devise a new procedure, to be used in the search for gravitational waves from black-hole-neutron-star binaries, to assign a probability that a detected gravitational signal is associated to the formation of an accreting disk, massive enough to power gamma-ray bursts. This method is based on two recently proposed semi-analytic fits, one reproducing the mass of the remnant disk surrounding the black hole as a function of some binary parameters, the second relating the neutron star compactness, with its tidal deformability. Our approach can be used in low-latency data analysis to restrict the parameter space searching for gravitational signals associated with short gamma-ray bursts, and to gain information on the dynamics of the coalescing system and on the neutron star equation of state.

  10. On The Gamma-Ray Emission From Reticulum II and Other Dwarf Galaxies

    E-Print Network [OSTI]

    Hooper, Dan

    2015-01-01T23:59:59.000Z

    The recent discovery of ten new dwarf galaxy candidates by the Dark Energy Survey (DES) and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) could increase the Fermi Gamma-Ray Space Telescope's sensitivity to annihilating dark matter particles, potentially enabling a definitive test of the dark matter interpretation of the long-standing Galactic Center gamma-ray excess. In this paper, we compare the previous analyses of Fermi data from the directions of the new dwarf candidates (including the relatively nearby Reticulum II) and perform our own analysis, with the goal of establishing the statistical significance of any gamma-ray signal from these sources. We confirm the presence of an excess from Reticulum II, with a spectral shape that is compatible with the Galactic Center signal. The significance of this emission is greater than that observed from 99.84% of randomly chosen high-latitude blank-sky locations, corresponding to a local detection significance of 3.2 sigma. We improve upon th...

  11. Gamma-ray momentum reconstruction from Compton electron trajectories by filtered back-projection

    SciTech Connect (OSTI)

    Haefner, A., E-mail: ahaefner@berkeley.edu; Plimley, B.; Pavlovsky, R. [Department of Nuclear Engineering, University of California Berkeley, 4155 Etcheverry Hall, MC 1730, Berkeley, California 94720-1730 (United States); Gunter, D. [Applied Nuclear Physics, Lawrence Berkeley National Laboratory, 1 Cyclotron Road Berkeley, California 94720 (United States); Vetter, K. [Department of Nuclear Engineering, University of California Berkeley, 4155 Etcheverry Hall, MC 1730, Berkeley, California 94720-1730 (United States); Applied Nuclear Physics, Lawrence Berkeley National Laboratory, 1 Cyclotron Road Berkeley, California 94720 (United States)

    2014-11-03T23:59:59.000Z

    Gamma-ray imaging utilizing Compton scattering has traditionally relied on measuring coincident gamma-ray interactions to map directional information of the source distribution. This coincidence requirement makes it an inherently inefficient process. We present an approach to gamma-ray reconstruction from Compton scattering that requires only a single electron tracking detector, thus removing the coincidence requirement. From the Compton scattered electron momentum distribution, our algorithm analytically computes the incident photon's correlated direction and energy distributions. Because this method maps the source energy and location, it is useful in applications, where prior information about the source distribution is unknown. We demonstrate this method with electron tracks measured in a scientific Si charge coupled device. While this method was demonstrated with electron tracks in a Si-based detector, it is applicable to any detector that can measure electron direction and energy, or equivalently the electron momentum. For example, it can increase the sensitivity to obtain energy and direction in gas-based systems that suffer from limited efficiency.

  12. COMPACT BINARY PROGENITORS OF SHORT GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Giacomazzo, Bruno [JILA, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309 (United States); Perna, Rosalba [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Rezzolla, Luciano [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Potsdam D-14476 (Germany); Troja, Eleonora [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Lazzati, Davide [Department of Physics, NC State University, 2401 Stinson Drive, Raleigh, NC 27695-8202 (United States)

    2013-01-10T23:59:59.000Z

    In recent years, detailed observations and accurate numerical simulations have provided support to the idea that mergers of compact binaries containing either two neutron stars (NSs) or an NS and a black hole (BH) may constitute the central engine of short gamma-ray bursts (SGRBs). The merger of such compact binaries is expected to lead to the production of a spinning BH surrounded by an accreting torus. Several mechanisms can extract energy from this system and power the SGRBs. Here we connect observations and numerical simulations of compact binary mergers, and use the current sample of SGRBs with measured energies to constrain the mass of their powering tori. By comparing the masses of the tori with the results of fully general-relativistic simulations, we are able to infer the properties of the binary progenitors that yield SGRBs. By assuming a constant efficiency in converting torus mass into jet energy, {epsilon}{sub jet} = 10%, we find that most of the tori have masses smaller than 0.01 M{sub Sun }, favoring 'high-mass' binary NSs mergers, i.e., binaries with total masses {approx}> 1.5 the maximum mass of an isolated NS. This has important consequences for the gravitational wave signals that may be detected in association with SGRBs, since 'high-mass' systems do not form a long-lived hypermassive NS after the merger. While NS-BH systems cannot be excluded to be the engine of at least some of the SGRBs, the BH would need to have an initial spin of {approx}0.9 or higher.

  13. AN EM APPROACH TO MINERAL ANALYSIS USING NATURAL GAMMA RAYS

    E-Print Network [OSTI]

    Huynh, Du

    Engineering The University of Western Australia, Australia cScantech, Camden Park SA 5038, Australia Abstract and Electronic Engineering The University of Melbourne, Australia bSchool of Computer Science and Software-channel analyzer, which sorts the measured gamma rays into a 1024 channel spectrum by energy. For a coal

  14. Constraints on relativity violations from gamma-ray bursts

    E-Print Network [OSTI]

    Alan Kostelecky; Matthew Mewes

    2013-01-23T23:59:59.000Z

    Tiny violations of the Lorentz symmetry of relativity and the associated discrete CPT symmetry could emerge in a consistent theory of quantum gravity such as string theory. Recent evidence for linear polarization in gamma-ray bursts improves existing sensitivities to Lorentz and CPT violation involving photons by factors ranging from ten to a million.

  15. Constraining axion by polarized prompt emission from gamma ray bursts

    E-Print Network [OSTI]

    A. Rubbia; A. S. Sakharov

    2007-08-21T23:59:59.000Z

    A polarized gamma ray emission spread over a sufficiently wide energy band from a strongly magnetized astrophysical object like gamma ray bursts (GRBs) offers an opportunity to test the hypothesis of invisible axion. The axionic induced dichroism of gamma rays at different energies should cause a misalignment of the polarization plane for higher energy events relative to that one for lower energies events resulting in the loss of statistics needed to form a pattern of the polarization signal to be recognized in a detector. According to this, any evidence of polarized gamma rays coming from an object with extended magnetic field could be interpreted as a constraint on the existence of the invisible axion for a certain parameter range. Based on reports of polarized MeV emission detected in several GRBs we derive a constraint on the axion-photon coupling. This constraint $\\g_{a\\gamma\\gamma}\\le 2.2\\cdot 10^{-11} {\\rm GeV^{-1}}$ calculated for the axion mass $m_a=10^{-3} {\\rm eV}$ is competitive with the sensitivity of CAST and becomes even stronger for lower masses.

  16. Current Trends in Gamma Ray Detection for Radiological Emergency Response

    SciTech Connect (OSTI)

    Mukhopadhyay, S., Guss, P., Maurer, R.

    2011-08-18T23:59:59.000Z

    Passive and active detection of gamma rays from shielded radioactive materials, including special nuclear materials, is an important task for any radiological emergency response organization. This article reports on the current trends and status of gamma radiation detection objectives and measurement techniques as applied to nonproliferation and radiological emergencies.

  17. Gamma Rays from Superheavy Relic Particles in the Halo

    E-Print Network [OSTI]

    Pasquale Blasi

    1999-05-15T23:59:59.000Z

    Superheavy (SH) quasistable particles generated in the Early Universe could be responsable for Ultra High Energy Cosmic Rays (UHECR) and be a component of Cold Dark Matter (CDM) in the universe. These particles are likely to cluster in the galactic halo, so that the main part of UHECR are gamma rays produced in the decay of neutral pions. Charged pions are also produced in the same process and result in high energy electrons. We consider here the production of gamma rays by synchrotron emission of these electrons in the galactic magnetic field. The gamma ray fluxes are in the region of interest for some current and proposed experiments (e.g. EGRET, GLAST, MILAGRO) in the energy range $0.1-10^4$ GeV. A comparison with the existing upper limits at $10^5-10^8$ GeV is also carried out. The detection of this flux of gamma rays would be an important signature of SH relic particles as sources of UHECR and would give a clue to the physics of the Early Universe.

  18. A Plasma Instability Theory of Gamma-Ray Burst Emission

    E-Print Network [OSTI]

    J. J. Brainerd

    1999-04-02T23:59:59.000Z

    A plasma instability theory is presented for the prompt radiation from gamma-ray bursts. In the theory, a highly relativistic shell interacts with the interstellar medium through the filamentation and the two-stream instabilities to convert bulk kinetic energy into electron thermal energy and magnetic field energy. The processes are not efficient enough to satisfy the Rankine-Hugoniot conditions, so a shock cannot form through this mechanism. Instead, the interstellar medium passes through the shell, with the electrons radiating during this passage. Gamma-rays are produced by synchrotron self-Compton emission. Prompt optical emission is also produced through this mechanism, while prompt radio emission is produced through synchrotron emission. The model timescales are consistent with the shortest burst timescales. To emit gamma-rays, the shell's bulk Lorentz factor must be greater than approximately 1000. For the radiative processes to be efficient, the interstellar medium density must satisfy a lower limit that is a function of the bulk Lorentz factor. Because the limits operate as selection effects, bursts that violate them constitute new classes. In particular, a class of optical and ultraviolet bursts with no gamma-ray emission should exist. The lower limit on the density of the interstellar medium is consistent with the requirements of the Compton attenuation theory, providing an explanation for why all burst spectra appear to be attenuated. Several tests of the theory are discussed, as are the next theoretical investigations that should be conducted.

  19. VERY HIGH ENERGY GAMMA RAYS FROM THE VELA PULSAR DIRECTION

    E-Print Network [OSTI]

    Enomoto, Ryoji

    VERY HIGH ENERGY GAMMA RAYS FROM THE VELA PULSAR DIRECTION T. Yoshikoshi1;2, T. Kifune2, S and Mathematical Physics, University of Adelaide, Adelaide, South Australia 5005, Australia 4Institute of SpaceDepartment of Physics, Kyoto University, Kyoto, Kyoto 606, Japan 8Solar-Terrestrial Environment Laboratory

  20. Applications of Likelihood Analysis in Gamma-Ray Astrophysics

    E-Print Network [OSTI]

    W. F. Tompkins

    2002-02-06T23:59:59.000Z

    The field of gamma ray astronomy relies heavily on the statistical analysis of data. Because of the paucity of data, and the often large errors associated with detecting gamma rays, analysis and interpretation of the data require sophisticated statistical techniques. Techniques for extending the currently used maximum likelihood technique to more complicated data sets are presented. Similarly presented are methods of calculating the distribution and behavior of the maximum likelihood statistic used to measure source significance. A new method for calculating source variability is also proposed, and used to examine the sources found by the Energetic Gamma Ray Experiment Telescope (EGRET) on board the Compton Gamma Ray Observatory (CGRO). The results show that the Active Galactic Nuclei (AGN), pulsars, and unidentified sources have markedly different variability, and that the unidentified sources fall into at least two classes, differing in variability and spatial distribution. A class composed of possible Supernova Remnant associations (SNR) is distinctly more variable than the pulsars, but has a variability consistent with that of the other low latitude unidentified sources. Finally, the results of the Fall 1997 GLAST prototype beam test are presented. The results of the beam test are compared with simulated results, and found to be in remarkably good agreement.

  1. Gamma Ray Bursts as Probes of the First Stars

    E-Print Network [OSTI]

    James E. Rhoads

    2001-11-01T23:59:59.000Z

    The redshift where the first stars formed is an important and unknown milestone in cosmological structure formation. The evidence linking gamma ray bursts (GRBs) with star formation activity implies that the first GRBs occurred shortly after the first stars formed. Gamma ray bursts and their afterglows may thus offer a unique probe of this epoch, because they are bright from gamma ray to radio wavelengths and should be observable to very high redshift. Indeed, our ongoing near-IR followup programs already have the potential to detect bursts at redshift z ~ 10. In these proceedings, we discuss two distinct ways of using GRBs to probe the earliest star formation. First, direct GRB counts may be used as a proxy for star formation rate measurements. Second, high energy cutoffs in the GeV spectra of gamma ray bursts due to pair production with high redshift optical and ultraviolet background photons contain information on early star formation history. The second method is observationally more demanding, but also more rewarding, because each observed pair creation cutoff in a high redshift GRB spectrum will tell us about the integrated star formation history prior to the GRB redshift.

  2. airborne gamma ray: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    airborne gamma ray First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Digital Logarithmic Airborne Gamma...

  3. X-ray Spectral Properties of Gamma-Ray Bursts

    E-Print Network [OSTI]

    T. E. Strohmayer; E. E. Fenimore; T. Murakami; A. Yoshida

    1997-12-18T23:59:59.000Z

    We summarize the spectral characteristics of a sample of 22 bright gamma-ray bursts detected with the gamma-ray burst sensors aboard the satellite Ginga. This instrument employed a proportional and scintillation counter to provide sensitivity to photons in the 2 - 400 keV range, providing a unique opportunity to characterize the largely unexplored X-ray properties of gamma-ray bursts. The photon spectra of the Ginga bursts are well described by a low energy slope, a bend energy, and a high energy slope. In the energy range where they can be compared, this result is consistent with burst spectral analyses obtained from the BATSE experiment aboard the Compton Observatory. However, below 20 keV we find evidence for a positive spectral number index in approximately 40% of our burst sample, with some evidence for a strong rolloff at lower energies in a few events. There is a correlation (Pearson's r = -0.62) between the low energy slope and the bend energy. We find that the distribution of spectral bend energies extends below 10 keV. The observed ratio of energy emitted in the X-rays relative to the gamma-rays can be much larger than a few percent and, in fact, is sometimes larger than unity. The average for our sample is 24%.

  4. absolute gamma ray: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    absolute gamma ray First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Absolute Branching Ratio of...

  5. advanced gamma ray: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    gamma ray First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Pixelized Gas Micro-well Detectors for...

  6. Gamma-Ray Bursts from Neutron Star Mergers

    E-Print Network [OSTI]

    T. Piran

    1994-01-17T23:59:59.000Z

    Binary neutron stars merger (NS$^2$M) at cosmological distances is probably the only $\\gamma$-ray bursts model based on an independently observed phenomenon which is known to be taking place at a comparable rate. We describe this model, its predictions and some open questions.

  7. A Gamma-Ray Burst Bibliography, 1973-2001

    E-Print Network [OSTI]

    K. Hurley

    2002-01-18T23:59:59.000Z

    On the average, 1.5 new publications on cosmic gamma-ray bursts enter the literature every day. The total number now exceeds 5300. I describe here a relatively complete bibliography which is on the web, and which can be made available electronically in various formats.

  8. Gamma-ray probes of dark matter substructure

    SciTech Connect (OSTI)

    Campbell, Sheldon [Department of Physics and Center for Cosmology and AstroParticle Physics (CCAPP), The Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210 (United States)

    2014-06-24T23:59:59.000Z

    The substructure content of dark matter halos is interesting because it can be affected by complex galaxy physics and dark matter particle physics. However, observing the small scale structure of dark matter is a challenge. The subhalo abundance (mass function, minimum mass) and morphology (density profile, subhalo shape, subsubstructure) contain information about complex astrophysics (halo formation processes) and new exotic fundamental physics (dark matter interactions). Indirect detection of dark matter annihilation radiation (DMAR) in gamma rays may be the most direct method for observing small scale structure. I outline the ways in which gamma rays may probe halo substructure. If substructure is bountiful, it may be responsible for the eventual discovery of DMAR, for instance in galaxy clusters or the diffuse gamma-ray background. Otherwise, the observation of DMAR in places without much substructure, such as the Galactic center, would lead to strict limits on the properties of small scale structure. Properties of the gamma-ray angular power spectrum will also provide information or constraints on Milky Way halo substructure.

  9. Snapshot Identification of Gamma Ray Burst Optical Afterglows

    E-Print Network [OSTI]

    James E. Rhoads

    2001-04-18T23:59:59.000Z

    Gamma ray burst afterglows can be identified in single epoch observations using three or more optical filters. This method relies on color measurements to distinguish the power law spectrum of an afterglow from the curved spectra of stars. Observations in a fourth filter will further distinguish between afterglows and most galaxies up to redshifts z ~ 1. Many afterglows can also be identified with fewer filters using ultraviolet excess, infrared excess, or Lyman break techniques. By allowing faster identification of gamma ray burst afterglows, these color methods will increase the fraction of bursts for which optical spectroscopy and other narrow-field observations can be obtained. Because quasar colors can match those of afterglows, the maximum error box size where an unambiguous identification can be expected is set by the flux limit of the afterglow search and the quasar number-flux relation. For currently typical error boxes (10 -- 100 square arcminutes), little contamination is expected at magnitudes R < 21.5 +- 0.5. Archival data demonstrates that the afterglow of GRB 000301C could have been identified using this method. In addition to finding gamma ray burst counterparts, this method will have applications in ``orphan afterglow'' searches used to constrain gamma ray burst collimation.

  10. Selected Results from Ground-Based Cosmic Ray and Gamma-Ray Experiments

    E-Print Network [OSTI]

    N. Magnussen

    1998-05-13T23:59:59.000Z

    Selected results from the HEGRA experiment on charged Cosmic Rays and on very high energy gamma-rays are presented. The MAGIC Telescope is presented as an outlook to the future of Gamma-Ray astronomy.

  11. Investigation of elemental analysis using neutron-capture gamma ray spectra

    E-Print Network [OSTI]

    Hamawi, John Nicholas

    1969-01-01T23:59:59.000Z

    This thesis evaluated the potential of neutron-capture gamma rays in elemental analysis. A large portion of the work was devoted to the development of a method for the analysis of weak peaks in gamma ray spectra. This was ...

  12. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE HETE-2 GAMMA-RAY BURST CATALOG

    E-Print Network [OSTI]

    Vanderspek, Roland K.

    Between 2000 November and 2006 May, one or more spacecraft of the interplanetary network (IPN) detected 226 cosmic gamma-ray bursts that were also detected by the French Gamma-Ray Telescope experiment on board the High ...

  13. 1 Cactus Framework: Black Holes to Gamma Ray Bursts 7 Erik Schnetter1,2

    E-Print Network [OSTI]

    Contents 1 Cactus Framework: Black Holes to Gamma Ray Bursts 7 Erik Schnetter1,2 , Christian D. Ott 94720, USA 1.1 Current challenges in relativistic astrophysics and the Gamma- Ray Burst problem

  14. Discovery of gamma-ray emission from the shell-type supernova remnant RCW 86 with H.E.S.S

    E-Print Network [OSTI]

    HESS Collaboration; F. Aharonian

    2008-10-15T23:59:59.000Z

    The shell-type supernova remnant (SNR) RCW 86, possibly associated with the historical supernova SN 185, with its relatively large size (about 40' in diameter) and the presence of non-thermal X-rays is a promising target for gamma-ray observations. The high sensitivity, good angular resolution of a few arc minutes and the large field of view of the High Energy Stereoscopic System (H.E.S.S.) make it ideally suited for the study of the gamma-ray morphology of such extended sources. H.E.S.S. observations have indeed led to the discovery of the SNR RCW 86 in very high energy (VHE; E > 100 GeV) gamma-rays. With 31 hours of observation time, the source is detected with a statistical significance of 8.5 sigma and is significantly more extended than the H.E.S.S. point spread function. Morphological studies have been performed and show that the gamma-ray flux does not correlate perfectly with the X-ray emission. The flux from the remnant is ~10% of the flux from the Crab nebula, with a similar photon index of about 2.5. Possible origins of the very high energy gamma-ray emission, via either Inverse Compton scattering by electrons or the decay of neutral pions produced by proton interactions, are discussed on the basis of spectral features obtained both in the X-ray and gamma-ray regimes.

  15. A search for GeV-TeV emission from Gamma-ray Bursts using the Milagro detector

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    A search for GeV-TeV emission from Gamma-ray Bursts using the Milagro detector p. M. Saz Parkinson of operation. Keywords: gamma-ray sources; gamma-ray bursts; astronomical observations gamma-ray; gamma-ray telescope; Milagro PACS: 95.55.Ka; 95.85.Pw; 98.70.Rz INTRODUCTION Gamma-ray bursts (GRBs) were detected up

  16. Fermi Discovery of Gamma-Ray Emission from NGC 1275

    SciTech Connect (OSTI)

    Abdo, Aous A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Ajello, M.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Asano, K.; /Tokyo Inst. Tech.; Baldini, L.; /INFN, Pisa; Ballet, J.; /DAPNIA, Saclay; Barbiellini, Guido; /INFN, Trieste /Trieste U.; Bastieri, Denis; /INFN, Padua /Padua U.; Baughman, B.M.; /Ohio State U.; Bechtol, K.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bellazzini, R.; /INFN, Pisa; Blandford, R.D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bloom, Elliott D.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bonamente, E.; /INFN, Perugia /Perugia U.; Borgland, A.W.; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Bregeon, J.; /INFN, Pisa; Brez, A.; /INFN, Pisa; Brigida, M.; /Bari U. /INFN, Bari; Bruel, P.; /Ecole Polytechnique; Burnett, Thompson H.; /Washington U., Seattle; Caliandro, G.A.; /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /IASF, Milan /IASF, Milan /DAPNIA, Saclay /ASDC, Frascati /INFN, Perugia /Perugia U. /SISSA, Trieste /George Mason U. /Naval Research Lab, Wash., D.C. /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Perugia /Perugia U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Montpellier U. /ASDC, Frascati /Sonoma State U. /Stockholm U., OKC /Royal Inst. Tech., Stockholm /Stockholm U. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Naval Research Lab, Wash., D.C. /INFN, Trieste /Bari U. /INFN, Bari /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /NASA, Goddard /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /CENBG, Gradignan /CENBG, Gradignan /Montpellier U. /Bari U. /INFN, Bari /Naval Research Lab, Wash., D.C. /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys. Dept. /INFN, Trieste /Hiroshima U.; /more authors..

    2009-05-15T23:59:59.000Z

    We report the discovery of high-energy (E > 100 MeV) {gamma}-ray emission from NGC 1275, a giant elliptical galaxy lying at the center of the Perseus cluster of galaxies, based on observations made with the Large Area Telescope (LAT) of the Fermi Gamma-ray Space Telescope. The positional center of the {gamma}-ray source is only {approx}3{prime} away from the NGC 1275 nucleus, well within the 95% LAT error circle of {approx}5{prime}. The spatial distribution of {gamma}-ray photons is consistent with a point source. The average flux and power-law photon index measured with the LAT from 2008 August 4 to 2008 December 5 are F{sub {gamma}} = (2.10 {+-} 0.23) x 10{sup -7} ph (>100 MeV) cm{sup -2} s{sup -1} and {Gamma} = 2.17 {+-} 0.05, respectively. The measurements are statistically consistent with constant flux during the four-month LAT observing period. Previous EGRET observations gave an upper limit of F{sub {gamma}} < 3.72 x 10{sup -8} ph (>100 MeV) cm{sup -2} s{sup -1} to the {gamma}-ray flux from NGC 1275. This indicates that the source is variable on timescales of years to decades, and therefore restricts the fraction of emission that can be produced in extended regions of the galaxy cluster. Contemporaneous and historical radio observations are also reported. The broadband spectrum of NGC 1275 is modeled with a simple one-zone synchrotron/synchrotron self-Compton model and a model with a decelerating jet flow.

  17. Which Massive stars are Gamma-Ray Burst Progenitors?

    E-Print Network [OSTI]

    Jelena Petrovic; Norbert Langer; Sung-Chul Yoon; Alexander Heger

    2005-04-11T23:59:59.000Z

    The collapsar model for gamma-ray bursts requires three essential ingredients: a massive core, removal of the hydrogen envelope, and enough angular momentum in the core. We study current massive star evolution models of solar metallicity to determine which massive star physics is capable of producing these ingredients. In particular, we investigate the role of hydrodynamic and magnetic internal angular momentum transport and binary mass and angular momentum transfer. We follow the evolution of rotating single stars and of binary systems that include rotational processes for both stars. Neglecting magnetic fields, we show that the cores of massive single stars can maintain a high specific angular momentum when evolved with the assumption that mean molecular weight gradients suppress rotational mixing processes. In binary systems that undergo mass transfer during core hydrogen burning the mass receiving star accretes large amounts of high angular momentum material, leading to a spin-up of the core. We find, however, that this merely compensates for the tidal angular momentum loss due to spin-orbit coupling, which leads to synchronous rotation before the mass transfer event. Therefore the resulting cores do not rotate faster than in single stars. We also present models that include magnetic fields generated by differential rotation and we consider the internal angular momentum transport by magnetic torques. We investigate the capability of magnetic torques to efficiently pump angular momentum into the cores of accreting stars. Despite our finding that this mechanism works, the magnetic coupling of core and envelope after the accreting star ends core hydrogen burning leads to slower rotation than in the non-magnetic case.

  18. Sub-TeV Gamma-Ray Astrophysics using Large Air Cerenkov Toru Tanimori3)

    E-Print Network [OSTI]

    Enomoto, Ryoji

    detection of persistent TeV gamma-ray emission from the Crab in 1989, several type of TeV gamma-ray sources the huge black holes at the center of galaxies. Recent detections of TeV gamma- ray emission from several+514, SN1006 Fig. 2. GeV gamma-ray source catalog detected by EGRET in galactic coordinates, where six Te

  19. SubTeV GammaRay Astrophysics using Large Air Toru Tanimori 3)

    E-Print Network [OSTI]

    Enomoto, Ryoji

    detection of persistent TeV gamma­ray emission from the Crab in 1989, several type of TeV gamma­ray sources the huge black holes at the center of galaxies. Recent detections of TeV gamma­ ray emission from severalES2344+514, SN1006 Fig. 2. GeV gamma­ray source catalog detected by EGRET in galactic coordinates

  20. Pulse properties of terrestrial gamma-ray flashes detected by the Fermi Gamma-Ray Burst Monitor

    E-Print Network [OSTI]

    Foley, Suzanne; Briggs, Michael S; Connaughton, Valerie; Tierney, David; McBreen, Sheila; Dwyer, Joseph; Chaplin, Vandiver L; Bhat, P Narayana; Byrne, David; Cramer, Eric; Fishman, Gerald J; Xiong, Shaolin; Greiner, Jochen; Kippen, R Marc; Meegan, Charles A; Paciesas, William S; Preece, Robert D; von Kienlin, Andreas; Wilson-Hodge, Colleen

    2015-01-01T23:59:59.000Z

    The Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope has triggered on over 300 terrestrial gamma-ray flashes (TGFs) since its launch in June 2008. With 14 detectors, GBM collects on average ~100 counts per triggered TGF, enabling unprecedented studies of the time profiles of TGFs. Here we present the first rigorous analysis of the temporal properties of a large sample of TGFs (278), including the distributions of the rise and fall times of the individual pulses and their durations. A variety of time profiles are observed with 19 of TGFs having multiple pulses separated in time and 31 clear cases of partially overlapping pulses. The effect of instrumental dead time and pulse pileup on the temporal properties are also presented. As the observed gamma ray pulse structure is representative of the electron flux at the source, TGF pulse parameters are critical to distinguish between relativistic feedback discharge and lightning leader models. We show that at least 67% of TGFs at satellite ...

  1. Relativistic Winds from Compact Gamma-Ray Sources: II. Pair Loading and Radiative Acceleration in Gamma-ray Bursts

    E-Print Network [OSTI]

    Christopher Thompson; Piero Madau

    2000-02-21T23:59:59.000Z

    We consider the effects of rapid pair creation by an intense pulse of gamma-rays propagating ahead of a relativistic shock. Side-scattered photons colliding with the main gamma-ray beam amplify the density of scattering charges. The acceleration rate of the pair-loaded medium is calculated, and its limiting bulk Lorentz factor related to the spectrum and compactness of the photon source. One obtains, as a result, a definite prediction for the relative inertia in baryons and pairs. The deceleration of a relativistic shock in the moving medium, and the resulting synchrotron emissivity, are compared with existing calculations for a static medium. The radiative efficiency is increased dramatically by pair loading. When the initial ambient density exceeds a critical value, the scattering depth traversed by the main gamma-ray pulse rises above unity, and the pulse is broadened. These considerations place significant constraints on burst progenitors: a pre-burst mass loss rate exceeding 10^{-5} M_\\odot per year is difficult to reconcile with individual pulses narrower than 10 s, unless the radiative efficiency is low. An anisotropic gamma-ray flux (on an angular scale \\Gamma^{-1} or larger) drives a large velocity shear that greatly increases the energy in the seed magnetic field forward of the propagating shock.

  2. Agile Detection of Delayed Gamma-Ray Emission from the Short Gamma-Ray Burst GRB 090510

    E-Print Network [OSTI]

    Giuliani, A; Vianello, G; Marisaldi, M; Mereghetti, S; Tavani, M; Cutini, S; Barbiellini, G; Longo, F; Moretti, E; Feroci, M; Del Monte, E; Argan, A; Bulgarelli, A; Caraveo, P; Cattaneo, P W; Chen, A W; Contessi, T; D'Ammando, F; Costa, E; De Paris, G; Di Cocco, G; Donnarumma, I; Evangelista, Y; Ferrari, A; Fiorini, M; Galli, M; Gianotti, F; Labanti, C; Lapshov, I; Lazzarotto, F; Lipari, P; Morselli, A; Pacciani, L; Pellizzoni, A; Perotti, F; Piano, G; Picozza, P; Pilia, M; Pucella, G; Prest, M; Rapisarda, M; Rappoldi, A; Rubini, A; Sabatini, S; Scalise, E; Striani, E; Soffitta, P; Trifoglio, M; Trois, A; Vallazza, E; Vercellone, S; Vittorini, V; Zambra, A; Zanello, D; Pittori, C; Verrecchia, F; Santolamazza, P; Giommi, P; Colafrancesco, S; Antonelli, L A; Salotti, L

    2009-01-01T23:59:59.000Z

    Short gamma-ray bursts (GRBs), typically lasting less than 2 s, are a special class of GRBs of great interest. We report the detection by the AGILE satellite of the short GRB 090510 which shows two clearly distinct emission phases: a prompt phase lasting ~ 200 msec and a second phase lasting tens of seconds. The burst is relatively intense in the 0.3-10 MeV range showing a spectrum of the prompt phase characterized by a large peak/cutoff energy near 3 MeV. Following the prompt phase, gamma-ray photons above 30 MeV were detected showing a power-law time decay of the flux of the type t^-1.3. The broad-band spectrum of this "delayed gamma-ray emission phase" is remarkably different from that of the prompt phase. It extends from sub-MeV to hundreds of MeV energies with a photon index alpha ~ 1.5. We present the timing and spectral data of GRB 090510 and briefly discuss its remarkable properties within the current models of gamma-ray emission of short GRBs.

  3. Characteristics of broadband lightning emissions associated with terrestrial gamma ray flashes

    E-Print Network [OSTI]

    Cummer, Steven A.

    . Introduction [2] Brief (typically bursts of gamma rays with mean energies of 2 MeV originating from the Earth's atmosphere, referred to as terrestrial gamma ray flashes (TGFs), have been observed by the Burst et al., 2010; Briggs et al., 2010]. With spectra typically harder than cosmic gamma ray bursts

  4. EFFECT OF IRRADIATION (GAMMA RAYS) ON THE BIOLOGY OF EIMERIA TENELLA OOCYSTS

    E-Print Network [OSTI]

    Boyer, Edmond

    EFFECT OF IRRADIATION (GAMMA RAYS) ON THE BIOLOGY OF EIMERIA TENELLA OOCYSTS R.S. BAJWA B.S. GILL, 1932), X-rays (Alba- nese and Smetana, 1934 ; Waxler, 1941 ; Siba- lic, 1970) and gamma rays (Baldelli. acervulina (Ali et al., 1972) to gamma rays have been reported to result in decreased infectivity. Waxler

  5. Modeling and simulation results on high sensitivity scattered gamma-ray emission imaging

    E-Print Network [OSTI]

    Nguyen-Verger, Maï K.

    Modeling and simulation results on high sensitivity scattered gamma-ray emission imaging C. Driol a simulations Numerical image reconstruction a b s t r a c t A new modality in gamma-ray emission imaging, based modality in gamma-ray emission imaging with potential applications in many fields such as bio

  6. Study of Very High Energy Gamma-ray Emission from the Pulsar Wind Nebula in

    E-Print Network [OSTI]

    Enomoto, Ryoji

    telescopes have achieved remarkably high sensitivity in the very high energy gamma-ray band. This is well-wavelength spectra were per- formed, based on both leptonic and hadronic models. In the leptonic model, gamma raysStudy of Very High Energy Gamma-ray Emission from the Pulsar Wind Nebula in MSH 15-52 with CANGAROO

  7. A EUROPEAN PROPOSAL FOR THE COMPTON GAMMA-RAY SOURCE OF ELI-NP*

    E-Print Network [OSTI]

    Boyer, Edmond

    . The predicted gamma-ray spectra have been evaluated for the case at 360 MeV. INTRODUCTION In the context of Gamma-ray photons is planned, capable to produce beams of mono-chromatic and high spectral density gammaA EUROPEAN PROPOSAL FOR THE COMPTON GAMMA-RAY SOURCE OF ELI-NP* C. Vaccarezza, O. Adriani, S

  8. Constraining the Intergalactic Magnetic Field Through its Imprint on Gamma Ray Data from Distant Sources.

    E-Print Network [OSTI]

    Arlen, Timothy

    2013-01-01T23:59:59.000Z

    Energy Emission of Gamma-Ray Bursts. ” ApJ, 682:127–134,1 GeV = 10 9 eV GRB Gamma-ray burst HE High energy, 100 MeVrays”-either from gamma-ray bursts or flares from blazars

  9. TeV GAMMA RAYS FROM PLERIONS AND RESULTS OF CAN-GAROO PROJECT

    E-Print Network [OSTI]

    @icrr.u-tokyo.ac.jp ABSTRACT Ground-based detection of very high energy gamma rays at Tev energies is discussed by using production, accel- eration and interaction of energetic particles. The point-like source of gamma raysV energies gamma rays is characterized by the interactions of energetic particles. The observation window

  10. THE NEW CANGAROO TELESCOPE AND THE PROSPECT OF VHE GAMMA RAY OBSERVATION AT

    E-Print Network [OSTI]

    Enomoto, Ryoji

    m diameter has a threshold energy of detecting gamma rays near 100 GeV. Also discussed is the next; in the region of 100 GeV to TeV energies) gamma rays are linked to energetic particles. They are produced through the non­thermal mechanism of those elementary particles as progenitor. Gamma rays are to suffer

  11. \\NEW" OBSERVATION OF TEV GAMMA RAY SOURCES: Relation to Origin of Matter and Early Universe

    E-Print Network [OSTI]

    Enomoto, Ryoji

    with matter by interactions of el- ementary particles, and gamma ray detection veri#12;es the processes of particle acceleration taking place in bright gamma ray sources, such as AGN (active galactic nuclei that utilizes the atmosphere as a calorimeter of absorbing gamma rays has a large detection area of more than

  12. The 28th International Cosmic Ray Conference 1 X-ray and Gamma-ray Measurements

    E-Print Network [OSTI]

    Enomoto, Ryoji

    The 28th International Cosmic Ray Conference 1 X-ray and Gamma-ray Measurements Masaki Mori-ray and gamma-ray measurements, of the 28th International Cosmic Ray Conference. 1. Introduction Thick atmosphere of the earth forces direct observations of X-rays and gamma-rays on satellites in space

  13. THE NEW CANGAROO TELESCOPE AND THE PROSPECT OF VHE GAMMA RAY OBSERVATION AT

    E-Print Network [OSTI]

    Enomoto, Ryoji

    a threshold energy of detecting gamma rays near 100 GeV. Also discussed is the next step we plan to take particles as progenitor. Gamma rays are to su er from the absorption through the pair creation of electron. Attempts to detect the relic phenomena have failed so far and remain as potential targets that gamma ray

  14. Stereo Matching and 3D Visualization for Gamma-Ray Cargo Inspection Zhigang Zhu*ab

    E-Print Network [OSTI]

    Zhu, Zhigang

    Stereo Matching and 3D Visualization for Gamma-Ray Cargo Inspection Zhigang Zhu*ab , Yu-Chi Hubc visualization issues are studied for a linear pushbroom stereo model built for 3D gamma-ray (or x-ray) cargo results are presented for real gamma-ray images of a 3D cargo container and the objects inside. The 3D

  15. The Interplanetary Network Supplement to the BATSE 5B Catalog of Cosmic Gamma-Ray Bursts

    E-Print Network [OSTI]

    California at Berkeley, University of

    The Interplanetary Network Supplement to the BATSE 5B Catalog of Cosmic Gamma-Ray Bursts K. Hurley Interplanetary Network (IPN) localization information for 343 gamma-ray bursts observed by the Burst Gamma-Ray Observatory (CGRO) mission, obtained by analyzing the arrival times of these bursts

  16. Evolution of massive Be and Oe stars at low metallicity towards the Long Gamma Ray bursts

    E-Print Network [OSTI]

    Evolution of massive Be and Oe stars at low metallicity towards the Long Gamma Ray bursts C and massive stars, and the theoretical predictions of the characteristics must have the long gamma-ray burst of that document deals with the long soft gamma ray bursts (here type 2 bursts) and their possible relationship

  17. Gamma-Ray Bursts in the Swift Era N. Gehrels,1

    E-Print Network [OSTI]

    Rodriguez, Luis F.

    1 Gamma-Ray Bursts in the Swift Era N. Gehrels,1 E. Ramirez-Ruiz,2 and D. B. Fox3 [1] NASA IS A GAMMA-RAY BURST? . . . . . . . . . . . . . . . . . . . . . . . . . 6 BURST AND AFTERGLOW OBSERVATIONS medium, high- redshift; gamma rays: observations, theory; stars: Wolf-Rayet; neutrinos; supernovae

  18. Studies of Gamma-Ray Burst Prompt Emission with RHESSI and NCT

    E-Print Network [OSTI]

    Bellm, Eric Christopher

    2011-01-01T23:59:59.000Z

    4 RHESSI Tests of Quasi-Thermal Gamma-Ray Burst Spectral 4.1List of Tables ix Acknowledgments 1 Gamma-Ray Bursts 1.1 GRBx 2 RHESSI Gamma-Ray Burst Analysis Methods 2.1 The RHESSI

  19. Milagro Search for Very High Energy Emission from Gamma-Ray Bursts in the Swift Era

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Milagro Search for Very High Energy Emission from Gamma-Ray Bursts in the Swift Era P. M. Saz an unprecedented number of rapid and accurate Gamma-Ray Burst (GRB) localizations, facilitating a flurry of follow as the flares. INTRODUCTION Some of the most important contributions to our understanding of gamma-ray bursts

  20. GAMMA-RAY BURSTS AND THE EARTH: EXPLORATION OF ATMOSPHERIC, BIOLOGICAL, CLIMATIC, AND BIOGEOCHEMICAL EFFECTS

    E-Print Network [OSTI]

    Jackman, Charles H.

    GAMMA-RAY BURSTS AND THE EARTH: EXPLORATION OF ATMOSPHERIC, BIOLOGICAL, CLIMATIC Received 2005 May 19; accepted 2005 August 2 ABSTRACT Gamma-ray bursts (GRBs) are likely to have made extinction may have been initiated by a GRB. Subject headinggs: astrobiology -- gamma rays: bursts Online

  1. A ground level gamma-ray burst observed in association with rocket-triggered lightning

    E-Print Network [OSTI]

    Florida, University of

    A ground level gamma-ray burst observed in association with rocket-triggered lightning J. R. Dwyer 2004; published 13 March 2004. [1] We report the observation of an intense gamma-ray burst observed lightning channel with gamma-ray energies extending up to more than 10 MeV. The burst consisted of 227

  2. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE BATSE CATALOGS OF UNTRIGGERED COSMIC GAMMA-RAY BURSTS

    E-Print Network [OSTI]

    California at Berkeley, University of

    THE INTERPLANETARY NETWORK SUPPLEMENT TO THE BATSE CATALOGS OF UNTRIGGERED COSMIC GAMMA-RAY BURSTS gamma-ray bursts (GRBs) observed as untriggered events by the Burst and Transient Source Experiment to detect BATSE un- triggered bursts. Subject headinggs: catalogs -- gamma rays: bursts Online material

  3. Did a gamma-ray burst initiate the late Ordovician mass extinction?

    E-Print Network [OSTI]

    Jackman, Charles H.

    Did a gamma-ray burst initiate the late Ordovician mass extinction? A.L. Melott1 , B.S. Lieberman2 Abstract: Gamma-ray bursts (GRBs) produce a flux of radiation detectable across the observable Universe words: Population and evolution, mass extinction, gamma-ray burst, Ordovician, ultraviolet ozone

  4. Search for Very High Energy Emission from Gamma-Ray Bursts using Milagro

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Search for Very High Energy Emission from Gamma-Ray Bursts using Milagro P. M. Saz Parkinson 95064 Abstract. Gamma-Ray Bursts (GRBs) have been detected at GeV energies by EGRET and models predict for very high energy emission from a sample of 106 gamma-ray bursts (GRB) detected since the beginning

  5. Search for gravitational waves associated with the InterPlanetary Network short gamma ray bursts

    E-Print Network [OSTI]

    California at Berkeley, University of

    Search for gravitational waves associated with the InterPlanetary Network short gamma ray bursts V with short gamma ray bursts detected by the InterPlanetary Network (IPN) during LIGO's fifth science run and Virgo's first science run. The IPN localisation of short gamma ray bursts is limited to extended error

  6. SOLAR SUBMILLIMETER AND GAMMA-RAY BURST EMISSION P. Kaufmann,1,2

    E-Print Network [OSTI]

    Giménez de Castro, Guillermo Carlos

    SOLAR SUBMILLIMETER AND GAMMA-RAY BURST EMISSION P. Kaufmann,1,2 J.-P. Raulin,1 A. M. Melo,1 E headings: gamma rays: bursts -- Sun: flares 1. INTRODUCTION The interaction of ultrarelativistic electrons observations of a burst in the submillimeter and gamma-ray ranges were obtained for the first time on 2001

  7. Search for Short Duration Bursts of TeV Gamma Rays with the Milagrito Telescope

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    OG 2.3.07 Search for Short Duration Bursts of TeV Gamma Rays with the Milagrito Telescope Gus for short duration bursts of TeV photons. Such bursts may result from "traditional" gamma-ray bursts to gamma-ray bursts, the final stages of black hole evaporation) the most compelling reason may

  8. Title of dissertation: A SEARCH FOR BURSTS OF VERY HIGH ENERGY GAMMA RAYS

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    ABSTRACT Title of dissertation: A SEARCH FOR BURSTS OF VERY HIGH ENERGY GAMMA RAYS WITH MILAGRO though the search was optimized primarily for detecting the emission from Gamma-Ray Bursts (GRBs) or to any other kind of phenomena that produce bursts of VHE gamma rays. Measurements of the GRB spectra

  9. arXiv:astro-ph/0509571v119Sep2005 Gamma-Ray Burst Early Afterglows

    E-Print Network [OSTI]

    Zhang, Bing

    arXiv:astro-ph/0509571v119Sep2005 Gamma-Ray Burst Early Afterglows Bing Zhang Department of Physics's Swift Gamma-Ray Burst Explorer open a new era for the multi-wavelength study of the very early afterglow phase of gamma-ray bursts (GRBs). GRB early afterglow information is essential to explore the unknown

  10. UNIVERSITY of CALIFORNIA A SEARCH FOR TEV GAMMA-RAY BURST EMISSION WITH

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    UNIVERSITY of CALIFORNIA SANTA CRUZ A SEARCH FOR TEV GAMMA-RAY BURST EMISSION WITH THE MILAGRO of Figures vi List of Tables viii Abstract ix Dedication x Acknowledgments xi 1 Gamma-Ray Bursts 1 1 . . . . . . . . . . . . . . . . . . . . . . . . . . 76 5.6 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 6 Gamma-Ray Burst

  11. Fermi Observations of High-Energy Gamma-Ray Emission from GRB 080916C

    E-Print Network [OSTI]

    Moskalenko, Igor V.

    Collaborations* Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory through the Gamma-ray Burst Monitor (GBM) and the Large Area Telescope (LAT) (9). The GBM consists of 12

  12. Climatic and biogeochemical effects of a galactic gamma ray burst Adrian L. Melott,1

    E-Print Network [OSTI]

    Jackman, Charles H.

    Climatic and biogeochemical effects of a galactic gamma ray burst Adrian L. Melott,1 Brian C. Jackman (2005), Climatic and biogeochemical effects of a galactic gamma ray burst, Geophys. Res. Lett., 32, L14808, doi:10.1029/2005GL023073. 1. Terrestrial Implications of Gamma Ray Bursts in Our Galaxy [2

  13. Constraints on Particle Acceleration from the Diffuse Isotropic Gamma-Ray Background

    E-Print Network [OSTI]

    Karl Mannheim

    2000-05-26T23:59:59.000Z

    Gamma rays trace accelerated particles, and the observed flux of extragalactic gamma rays therefore constrains the global efficiency for particle acceleration. Extragalactic jets in active galactic nuclei can account for the gamma ray background if their particle acceleration efficiency considerably exceeds ~ 18 per cent which would imply that particle acceleration is an essential part of the thermodynamics in these sources.

  14. Study of galactic gamma ray sources with Milagro Jordan A. Goodman for the Milagro Collaboration

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    in the Cygnus Region [3], and the possible detection of a gamma-ray burst with our prototype instrument] and the Crab Nebula [7], set stringent upper limits on the prompt TeV emission from several gamma ray bursts [8Study of galactic gamma ray sources with Milagro Jordan A. Goodman for the Milagro Collaboration

  15. UNIVERSITY OF CALIFORNIA Search for a TeV Component of GammaRay Bursts

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    UNIVERSITY OF CALIFORNIA IRVINE Search for a TeV Component of Gamma­Ray Bursts Using the Milagrito Acknowledgements xiii Curriculum Vitae xv Abstract xvi 1. Introduction 1 2. Gamma­Ray Bursts: Observations.2 The Compton Gamma­Ray Observatory . . . . . . . . . . . . . . . . . . . 6 2.3 BATSE's Contributions

  16. Source altitudes of terrestrial gamma-ray flashes produced by lightning leaders

    E-Print Network [OSTI]

    Pasko, Victor

    ; published 18 April 2012. [1] Terrestrial gamma-ray flashes (TGFs) are energetic photon bursts observed fromSource altitudes of terrestrial gamma-ray flashes produced by lightning leaders Wei Xu,1 Sebastien. Pasko (2012), Source altitudes of terres- trial gamma-ray flashes produced by lightning leaders, Geophys

  17. Gamma Ray Astronomy with Air Shower Arrays A.I. Mincer 1

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    and for searching for transient sources such as gamma ray bursts. The Milagro detector is currently operating such as gamma ray bursts or to study the time variation of ``steady'' sources, air shower arrays are usedGamma Ray Astronomy with Air Shower Arrays A.I. Mincer 1 New York University, New York, NY 10003

  18. Limits on Very High Energy Emission from Gamma-Ray Bursts with the Milagro

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Limits on Very High Energy Emission from Gamma-Ray Bursts with the Milagro Observatory Miguel F of Milagro allow it to detect very high energy (VHE) gamma-ray burst emission with much higher sensitivity gamma-ray burst satellites at keV to MeV energies. Even in the absence of a positive detection, VHE

  19. Detectors for the Gamma-Ray Resonant Absorption (GRA) Method of Explosives Detection in Cargo: A Comparative Study

    E-Print Network [OSTI]

    David Vartsky; Mark B. Goldberg; Gideon Engler; Asher Shor; Aharon Goldschmidt; Gennady Feldman; Doron Bar; Itzhak Orion; Lucian Wielopolski

    2005-06-14T23:59:59.000Z

    Gamma-Ray Resonant Absorption (GRA) is an automatic-decision radiographic screening technique that combines high radiation penetration with very good sensitivity and specificity to nitrogenous explosives. The method is particularly well-suited to inspection of large, massive objects (since the incident gamma-ray probe is at 9.17 MeV) such as aviation and marine containers, heavy vehicles and railroad cars. Two kinds of gamma-ray detectors have been employed to date in GRA systems: 1) Resonant-response nitrogen-rich liquid scintillators and 2) BGO detectors. This paper analyses and compares the response of these detector-types to the resonant radiation, in terms of single-pixel figures of merit. The latter are sensitive not only to detector response, but also to accelerator-beam quality, via the properties of the nuclear reaction that produces the resonant gamma-rays. Generally, resonant detectors give rise to much higher nitrogen-contrast sensitivity in the radiographic image than their non-resonant detector counterparts and furthermore, do not require proton beams of high energy-resolution. By comparison, the non-resonant detectors have higher gamma-detection efficiency, but their contrast sensitivity is very sensitive to the quality of the accelerator beam. Implications of these detector/accelerator characteristics for eventual GRA field systems are discussed.

  20. VAXGAP: A code for the routine analysis of gamma-ray pulse-height spectra on a VAX computer

    SciTech Connect (OSTI)

    Killian, E.W.; Hartwell, J.K.

    1988-05-01T23:59:59.000Z

    This report describes the analysis algorithms and techniques used in the VAX Gamma-Ray Analysis Program (VAXGAP) at the Idaho National Engineering Laboratory (INEL). VAXGAP is a collection of computer programs for the analysis of gamma-ray pulse-height spectra. It operates on a Digital Equipment Corporation VAX computer, using the VMS operating system. Linear and nonlinear peak fitting techniques are used to calculate photopeak areas, which in turn are used to determine the concentration of gamma-ray emitting radionuclides in many different types of samples--from /open quotes/hot/close quotes/ samples, collected from the primary coolant water of operating reactors, to very low-level environmental samples. VAXGAP is user friendly and provides laboratory technicians and spectroscopists with analysis results in a rapid and accurate manner with a minimal investment in computer hardware. On a VAX-750 computer, VAXGAP takes less than a minute to perform a typical spectrum analysis. VAXGAP programs are menu-driven and the user interface to the analysis functions is simple. Use of VAXGAP does not require a detailed knowledge of the computer operating system or gamma-ray spectroscopy. 3 refs., 5 figs., 4 tabs.

  1. Low latency search for Gravitational waves from BH-NS binaries in coincidence with Short Gamma Ray Bursts

    E-Print Network [OSTI]

    Andrea Maselli; Valeria Ferrari

    2014-02-24T23:59:59.000Z

    We propose a procedure to be used in the search for gravitational waves from black hole-neutron star coalescing binaries, in coincidence with short gamma-ray bursts. It is based on two recently proposed semi-analytic fits, one reproducing the mass of the remnant disk surrounding the black hole which forms after the merging as a function of some binary parameters, the second relating the neutron star compactness, i.e. the ratio of mass and radius, with its tidal deformability. Using a Fisher matrix analysis and the two fits, we assign a probability that the emitted gravitational signal is associated to the formation of an accreting disk massive enough to supply the energy needed to power a short gamma ray burst. This information can be used in low-latency data analysis to restrict the parameter space searching for gravitational wave signals in coincidence with short gamma-ray bursts, and to gain information on the dynamics of the coalescing system and on the internal structure of the components. In addition, when the binary parameters will be measured with high accuracy, it will be possible to use this information to trigger the search for off-axis gamma-ray bursts afterglows.

  2. Search for very high energy gamma-rays from WIMP annihilations near the Sun with the Milagro Detector

    E-Print Network [OSTI]

    Milagro Collaboration

    2004-05-14T23:59:59.000Z

    The neutralino, the lightest stable supersymmetric particle, is a strong theoretical candidate for the missing astronomical ``dark matter''. A profusion of such neutralinos can accumulate near the Sun when they lose energy upon scattering and are gravitationally captured. Pair-annihilations of those neutralinos may produce very high energy (VHE, above $100 GeV$) gamma-rays. Milagro is an air shower array which uses the water Cherenkov technique to detect extensive air showers and is capable of observing VHE gamma-rays from the direction of the Sun with an angular resolution of $0.75^{\\circ}$. Analysis of Milagro data with an exposure to the Sun of 1165 hours presents the first attempt to detect TeV gamma-rays produced by annihilating neutralinos captured by the Solar system and shows no statistically significant signal. Resulting limits that can be set on gamma-ray flux due to near-Solar neutralino annihilations and on neutralino cross-section are presented.

  3. Search for very high energy gamma-rays from WIMP annihilations near the Sun with the Milagro Detector

    E-Print Network [OSTI]

    Atkins, R; Berley, D; Blaufuss, E; Bussons, J; Coyne, D G; De Young, T R; Dingus, B L; Dorfan, D E; Ellsworth, R W; Fleysher, L; Fleysher, R; Gisler, G; González, M M; Goodman, J A; Haines, T J; Hays, E; Hoffman, C M; Kelley, L A; Lansdell, C P; Linnemann, J T; McEnery, J E; Miller, R S; Mincer, A I; Morales, M F; Némethy, P; Noyes, D; Ryan, J M; Samuelson, F W; Shoup, A; Sinnis, G; Smith, A J; Sullivan, G W; Williams, D A; Westerhoff, S; Wilson, M E; Xu, X W; Yodh, G B

    2004-01-01T23:59:59.000Z

    The neutralino, the lightest stable supersymmetric particle, is a strong theoretical candidate for the missing astronomical ``dark matter''. A profusion of such neutralinos can accumulate near the Sun when they lose energy upon scattering and are gravitationally captured. Pair-annihilations of those neutralinos may produce very high energy (VHE, above $100 GeV$) gamma-rays. Milagro is an air shower array which uses the water Cherenkov technique to detect extensive air showers and is capable of observing VHE gamma-rays from the direction of the Sun with an angular resolution of $0.75^{\\circ}$. Analysis of Milagro data with an exposure to the Sun of 1165 hours presents the first attempt to detect TeV gamma-rays produced by annihilating neutralinos captured by the Solar system and shows no statistically significant signal. Resulting limits that can be set on gamma-ray flux due to near-Solar neutralino annihilations and on neutralino cross-section are presented.

  4. A redshift - observation-time relation for gamma-ray bursts: evidence of a distinct sub-luminous population

    E-Print Network [OSTI]

    E. J. Howell; D. M. Coward

    2013-02-19T23:59:59.000Z

    We show how the redshift and peak-flux distributions of gamma-ray bursts (GRBs) have an observation time dependence that can be used to discriminate between different burst populations. We demonstrate how observation time relations can be derived from the standard integral distributions and that they can differentiate between GRB populations detected by both the BATSE and \\emph{Swift} satellites. Using \\emph{Swift} data we show that a redshift--observation-time relation (log\\,$Z$\\,--\\,log\\,$T$) is consistent with both a peak-flux\\,--\\,observation time relation (log\\,$P$\\,--\\,log\\,$T$) and a standard log\\,$N$\\,--\\,log\\,$P$ brightness distribution. As the method depends only on rarer small-$z$ events, it is invariant to high-$z$ selection effects. We use the log\\,$Z$\\,--\\,log\\,$T$ relation to show that sub-luminous GRBs are a distinct population occurring at a higher rate of order $150^{+180}_{-90} \\mathrm{Gpc}^{-3}\\mathrm{yr}^{-1}$. Our analysis suggests that GRB 060505 -- a relatively nearby GRB observed without any associated supernova -- is consistent with a sub-luminous population of bursts. Finally, we suggest that our relations can be used as a consistency test for some of the proposed GRB spectral energy correlations.

  5. Detecting special nuclear materials in containers using high-energy gamma rays emitted by fission products

    DOE Patents [OSTI]

    Norman, Eric B. (Oakland, CA); Prussin, Stanley G. (Kensington, CA)

    2007-10-02T23:59:59.000Z

    A method and a system for detecting the presence of special nuclear materials in a container. The system and its method include irradiating the container with an energetic beam, so as to induce a fission in the special nuclear materials, detecting the gamma rays that are emitted from the fission products formed by the fission, to produce a detector signal, comparing the detector signal with a threshold value to form a comparison, and detecting the presence of the special nuclear materials using the comparison.

  6. Do Gamma-Ray Bursts Come from the Oort Cloud?

    E-Print Network [OSTI]

    T. E. Clarke; O. Blaes; adn S. Tremaine

    1993-10-02T23:59:59.000Z

    We examine the possibility that gamma-ray bursts arise from sources in the Oort comet cloud, basing most of our arguments on accepted models for the formation and spatial distribution of the cloud. We identify three severe problems with such models: (1) There is no known mechanism for producing bursts that can explain the observed burst rate and energetics without violating other observational constraints. (2) The bright source counts cannot be reconciled with standard models for the phase-space distribution of objects in the Oort cloud. (3) The observed isotropy of the available burst data is inconsistent with the expected angular distribution of sources in the Oort cloud. We therefore assert that Oort cloud models of gamma-ray bursts are extremely implausible.

  7. Fiber fed x-ray/gamma ray imaging apparatus

    DOE Patents [OSTI]

    Hailey, C.J.; Ziock, K.P.

    1992-06-02T23:59:59.000Z

    X-ray/gamma ray imaging apparatus is disclosed for detecting the position, energy, and intensity of x-ray/gamma ray radiation comprising scintillation means disposed in the path of such radiation and capable of generating photons in response to such radiation; first photodetection means optically bonded to the scintillation means and capable of generating an electrical signal indicative of the intensity, and energy of the radiation detected by the scintillation means; second photodetection means capable of generating an electrical signal indicative of the position of the radiation in the radiation pattern; and means for optically coupling the scintillation means to the second photodetection means. The photodetection means are electrically connected to control and storage means which may also be used to screen out noise by rejecting a signal from one photodetection means not synchronized to a signal from the other photodetection means; and also to screen out signals from scattered radiation. 6 figs.

  8. Gamma-Ray Emission From Crushed Clouds in Supernova Remnants

    SciTech Connect (OSTI)

    Uchiyama, Yasunobu; Blandford, Roger D.; Funk, Stefan; /SLAC; Tajima, Hiroyasu; /Nagoya U., Solar-Terrestrial Environ. Lab.; Tanaka, Takaaki; /KIPAC, Menlo Park; ,

    2010-10-27T23:59:59.000Z

    It is shown that the radio and gamma-ray emission observed from newly-found 'GeV-bright' supernova remnants (SNRs) can be explained by a model, in which a shocked cloud and shock-accelerated cosmic rays (CRs) frozen in it are simultaneously compressed by the supernova blastwave as a result of formation of a radiative cloud shock. Simple reacceleration of pre-existing CRs is generally sufficient to power the observed gamma-ray emission through the decays of {pi}{sup 0}-mesons produced in hadronic interactions between high-energy protons (nuclei) and gas in the compressed-cloud layer. This model provides a natural account of the observed synchrotron radiation in SNRs W51C, W44 and IC 443 with flat radio spectral index, which can be ascribed to a combination of secondary and reaccelerated electrons and positrons.

  9. Gamma Ray Burst as Sources of Exotic Particles

    E-Print Network [OSTI]

    Morgan, Ian; De Pree, Erin; Tennyson, Kevin

    2015-01-01T23:59:59.000Z

    We consider the possible production of stable lightest first level KK particle (LKP) in baryonic gamma ray bursts (GRB) out flows. We numerically computed the energy-dependent cross-sections of Kaluza-Klein (KK) excitations for the Standard Model gauge bosons, photon and Z. Next, we determined the feasibility of producing these KK excitations in gamma-ray emitting regions of GRBs. We found that a GRB fireball that accelerates baryons to energies greater than 10^14 eV could produce KK excitations out to approximately 10^12 cm from the central engine, indicating that GRBs may be a significant source of the LKP. Finally, we explore the potential observational consequences of our results.

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

    SciTech Connect (OSTI)

    Goldstein, Adam; Preece, Robert D.; Briggs, Michael S.; Burgess, J. Michael [University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Mallozzi, Robert S.; Fishman, Gerald J.; Kouveliotou, Chryssa [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Paciesas, William S. [Universities Space Research Association, 320 Sparkman Drive, Huntsville, AL 35805 (United States)

    2013-10-01T23:59:59.000Z

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

  11. Color Superconductivity in Compact Stars and Gamma Ray Bursts

    E-Print Network [OSTI]

    A. Drago; A. Lavagno; G. Pagliara

    2003-04-08T23:59:59.000Z

    We study the effects of color superconductivity on the structure and formation of compact stars. We show that it is possible to satisfy most of recent observational boundaries on masses and radii if a diquark condensate forms in a hybrid or a quark star. Moreover, we find that a huge amount of energy, of the order of $10^{53}$ erg, can be released in the conversion from a (metastable) hadronic star into a (stable) hybrid or quark star, if the presence of a color superconducting phase is taken into account. Accordingly to the scenario proposed in Astrophys.J.586(2003)1250, the energy released in this conversion can power a Gamma Ray Burst. This mechanism can explain the recent observations indicating a delay, of the order of days or years, between a few Supernova explosions and the subsequent Gamma Ray Burst.

  12. Isotopic response with small scintillator based gamma-ray spectrometers

    DOE Patents [OSTI]

    Madden, Norman W. (Sparks, NV); Goulding, Frederick S. (Lafayette, CA); Asztalos, Stephen J. (Oakland, CA)

    2012-01-24T23:59:59.000Z

    The intrinsic background of a gamma ray spectrometer is significantly reduced by surrounding the scintillator with a second scintillator. This second (external) scintillator surrounds the first scintillator and has an opening of approximately the same diameter as the smaller central scintillator in the forward direction. The second scintillator is selected to have a higher atomic number, and thus has a larger probability for a Compton scattering interaction than within the inner region. Scattering events that are essentially simultaneous in coincidence to the first and second scintillators, from an electronics perspective, are precluded electronically from the data stream. Thus, only gamma-rays that are wholly contained in the smaller central scintillator are used for analytic purposes.

  13. Gamma-ray bursts, axion emission and string theory dilaton

    E-Print Network [OSTI]

    O. Bertolami

    1999-01-14T23:59:59.000Z

    The emission of axions from supernovae is an interesting possibility to account for the Gamma-Ray Bursts provided their energy can be effectively converted into electromagnetic energy elsewhere. The connection between supernova and gamma-ray bursts has been recently confirmed by the observed correlation between the burst of April 25, 1998 and the supernova SN1998bw. We argue that the axion convertion into photons can be more efficient if one considers the coupling between an intermediate scale axion and the string theory dilaton along with the inclusion of string loops. We also discuss the way dilaton dynamics may allow for a more effective energy exchange with electromagnetic radiation in the expansion process of fireballs.

  14. Power Density Spectra of Gamma-Ray Bursts

    E-Print Network [OSTI]

    Andrei M. Beloborodov

    1999-11-08T23:59:59.000Z

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

  15. Gravitational collapse as the source of gamma-ray bursts

    E-Print Network [OSTI]

    V. V. Sokolov

    2008-05-21T23:59:59.000Z

    If the threshold for $e^{-}e^{+}$ pair production depends on an angle between photon momenta, and if the $\\gamma$-rays are collimated right in gamma-ray burst (GRB) source then another solution of the compactness problem is possible. The list of basic assumptions of the scenario describing the GRB with energy release $< 10^{49}$ erg is adduced: the matter is about an alternative to the ultrarelativistic fireball if all long-duration GRBs are physically connected with core-collapse supernovae (SNe). The questions about radiation pressure and how the jet arises on account of even a small radiation field asymmetry in a compact GRB source of size $\\lesssim 10^8$ cm, and observational consequences of the compact model of GRBs are considered.

  16. Acceleration at Relativistic Shocks in Gamma-Ray Bursts

    E-Print Network [OSTI]

    Baring, M G

    1999-01-01T23:59:59.000Z

    Most recent extragalactic models of gamma-ray bursts consider the expansion of a relativistic blast wave, emanating from a solar-mass type progenitor, into the surrounding interstellar medium as the site for their activity. The popular perception is that the optical afterglows result from the external shock interface, while the prompt transient gamma-ray signal arises from multiple shocks internal to the expansion. This paper illustrates a number of acceleration properties of relativistic and ultrarelativistic shocks that pertain to GRB models, by way of a standard Monte Carlo simulation. Computations of the spectral shape, the range of spectral indices, and the energy gain per shock crossing are presented, as functions of the shock speed and the type of particle scattering.

  17. Neutron and Gamma Ray Pulse Shape Discrimination with Polyvinyltoluene

    SciTech Connect (OSTI)

    Lintereur, Azaree T.; Ely, James H.; Stave, Jean A.; McDonald, Benjamin S.

    2012-03-01T23:59:59.000Z

    The goal of this was research effort was to test the ability of two poly vinyltoluene research samples to produce recordable, distinguishable signals in response to gamma rays and neutrons. Pulse shape discrimination was performed to identify if the signal was generated by a gamma ray or a neutron. A standard figure of merit for pulse shape discrimination was used to quantify the gamma-neutron pulse separation. Measurements were made with gamma and neutron sources with and without shielding. The best figure of merit obtained was 1.77; this figure of merit was achieved with the first sample in response to an un-moderated 252Cf source shielded with 5.08 cm of lead.

  18. Radio and gamma-ray connection in relativistic jets

    E-Print Network [OSTI]

    Orienti, M

    2015-01-01T23:59:59.000Z

    Relativistic jets are one of the most powerful manifestations of the release of energy related to the supermassive black holes at the centre of active galactic nuclei (AGN). Their emission is observed across the entire electromagnetic spectrum, from the radio band to gamma rays. Despite decades of efforts, many aspects of the physics of relativistic jets remain elusive. In particular, the location and the mechanisms responsible for the high-energy emission and the connection of the variability at different wavelengths are among the greatest challenges in the study of AGN. Recent high resolution radio observations of flaring objects locate the high-energy emitting region downstream the jet at parsec scale distance from the central engine, posing questions on the nature of the seed photons upscattered to gamma-rays. Furthermore, monitoring campaigns of the most active blazars indicate that not all the high energy flares have the same characteristics in the various energy bands, even from the same source, making...

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

    E-Print Network [OSTI]

    Mark E. Perel'man

    2009-07-27T23:59:59.000Z

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

  20. Gamma-Ray Burst Detection with INTEGRAL/SPI

    E-Print Network [OSTI]

    Andreas von Kienlin; Nikolas Arend; Giselher Lichti; Andrew Strong; Paul Connell

    2004-07-05T23:59:59.000Z

    The spectrometer SPI, one of the two main instruments of the INTEGRAL spacecraft, has strong capabilities in the field of Gamma-Ray Burst (GRB) detections. In its 16 deg field of view (FoV) SPI is able to trigger and to localize GRBs with an accuracy for strong bursts better than 1 deg. The expected GRB detection rate is about one per month.

  1. THE ENGINES BEHIND SUPERNOVAE AND GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    FRYER, CHRISTOPHER LEE [Los Alamos National Laboratory

    2007-01-23T23:59:59.000Z

    The authors review the different engines behind supernova (SNe) and gamma-ray bursts (GRBs), focusing on those engines driving explosions in massive stars: core-collapse SNe and long-duration GRBs. Convection and rotation play important roles in the engines of both these explosions. They outline the basic physics and discuss the wide variety of ways scientists have proposed that this physics can affect the supernova explosion mechanism, concluding with a review of the current status in these fields.

  2. On the origin of Gamma Ray Burst radiation

    E-Print Network [OSTI]

    G. Ghisellini

    2001-01-17T23:59:59.000Z

    In the standard internal shock model, the observed X and gamma-ray radiation is assumed to be produced by synchrotron emission. I will show that there are serious problems with this interpretation, calling for other radiation mechanisms, such as quasi-thermal Comptonization and/or Compton drag processes, or both. These new ideas can have important consequences on the more general internal shock scenario, and can be tested by future observations.

  3. Capture Gamma-Ray Libraries for Nuclear Applications

    SciTech Connect (OSTI)

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

    2010-05-01T23:59:59.000Z

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

  4. Gamma-ray boxes from axion-mediated dark matter

    SciTech Connect (OSTI)

    Ibarra, Alejandro; Gehler, Sergio López; Pato, Miguel [Physik-Department T30d, Technische Universität München, James-Franck-Strasse, 85748 Garching (Germany); Lee, Hyun Min; Park, Wan-Il, E-mail: ibarra@tum.de, E-mail: hyun.min.lee@cern.ch, E-mail: sergio.lopez@ph.tum.de, E-mail: wipark@kias.re.kr, E-mail: miguel.pato@tum.de [School of Physics, KIAS, Seoul 130-722 (Korea, Republic of)

    2013-05-01T23:59:59.000Z

    We compute the gamma-ray output of axion-mediated dark matter and derive the corresponding constraints set by recent data. In such scenarios the dark matter candidate is a Dirac fermion that pair-annihilates into axions and/or scalars. Provided that the axion decays (at least partly) into photons, these models naturally give rise to a box-shaped gamma-ray spectrum that may present two distinct phenomenological behaviours: a narrow box, resembling a line at half the dark matter mass, or a wide box, spanning an extensive energy range up to the dark matter mass. Remarkably, we find that in both cases a sizable gamma-ray flux is predicted for a thermal relic without fine-tuning the model parameters nor invoking boost factors. This large output is in line with recent Fermi-LAT observations towards the galactic centre region and is on the verge of being excluded. We then make use of the Fermi-LAT and H.E.S.S. data to derive robust, model-independent upper limits on the dark matter annihilation cross section for the narrow and wide box scenarios. H.E.S.S. constraints, in particular, turn out to match the ones from Fermi-LAT at hundreds of GeV and extend to multi-TeV masses. Future ?erenkov telescopes will likely probe gamma-ray boxes from thermal dark matter relics in the whole multi-TeV range, a region hardly accessible to direct detection, collider searches and other indirect detection strategies.

  5. The Supernovae Associated with Gamma-Ray Bursts

    E-Print Network [OSTI]

    Thomas Matheson

    2004-10-27T23:59:59.000Z

    Supernovae (SNe) were long suspected as possible progenitors of gamma-ray bursts (GRBs). The arguments relied on circumstantial evidence. Several recent GRBs, notably GRB 030329, have provided direct, spectroscopic evidence that SNe and GRBs are related. The SNe associated with GRBs are all of Type Ic, implying a compact progenitor, which has implications for GRB models. Other peculiar Type Ic SNe may help to expand understanding of the mechanisms involved.

  6. The HAWC Gamma-Ray Observatory: Observations of Cosmic Rays

    E-Print Network [OSTI]

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

    2013-01-01T23:59:59.000Z

    We describe measurements of GeV and TeV cosmic rays with the High-Altitude Water Cherenkov Gamma-Ray Observatory, or HAWC. The measurements include the observation of the shadow of the moon; the observation of small-scale and large-scale angular clustering of the TeV cosmic rays; the prospects for measurement of transient solar events with HAWC; and the observation of Forbush decreases with the HAWC engineering array and HAWC-30.

  7. Search for neutrinos from Gamma-Ray Bursts with ANTARES

    E-Print Network [OSTI]

    Eleonora Presani

    2011-04-20T23:59:59.000Z

    A method to search for neutrino induced showers from gamma-ray bursts in the ANTARES detector is presented. ANTARES consists of a three-dimensional array of photosensitive devices that measure Cherenkov light induced by charged particles produced by high energy neutrinos interacting in the detector vicinity. The shower channel is complementary to the more commonly used upgoing muon channel. The corresponding detection volume is smaller, but has the advantage of being sensitive to neutrinos of any flavour.

  8. GAMMA-RAY OBSERVATIONS OF CYGNUS X-1 ABOVE 100 MeV IN THE HARD AND SOFT STATES

    SciTech Connect (OSTI)

    Sabatini, S.; Tavani, M.; Del Santo, M.; Campana, R.; Evangelista, Y.; Piano, G.; Del Monte, E.; Giusti, M.; Striani, E. [INAF/IAPS-Roma, I-00133 Roma (Italy)] [INAF/IAPS-Roma, I-00133 Roma (Italy); Coppi, P. [Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States)] [Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Pooley, G. [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom)] [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Chen, A.; Giuliani, A. [INAF/IASF-Milano, I-20133 Milano (Italy)] [INAF/IASF-Milano, I-20133 Milano (Italy); Bulgarelli, A. [INAF/IASF-Bologna, I-40129 Bologna (Italy)] [INAF/IASF-Bologna, I-40129 Bologna (Italy); Cattaneo, P. W. [INFN-Pavia, I-27100 Pavia (Italy)] [INFN-Pavia, I-27100 Pavia (Italy); Colafrancesco, S. [INAF-OAR, I-00040 Monteporzio Catone (Italy)] [INAF-OAR, I-00040 Monteporzio Catone (Italy); Longo, F. [Dip. Fisica and INFN Trieste, I-34127 Trieste (Italy)] [Dip. Fisica and INFN Trieste, I-34127 Trieste (Italy); Morselli, A. [INFN Roma Tor Vergata, I-00133 Roma (Italy)] [INFN Roma Tor Vergata, I-00133 Roma (Italy); Pellizzoni, A. [INAF-OAC, I-09012 Capoterra (Italy)] [INAF-OAC, I-09012 Capoterra (Italy); Pilia, M. [ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands)] [ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); and others

    2013-04-01T23:59:59.000Z

    We present the results of multi-year gamma-ray observations by the AGILE satellite of the black hole binary system Cygnus X-1. In a previous investigation we focused on gamma-ray observations of Cygnus X-1 in the hard state during the period mid-2007/2009. Here we present the results of the gamma-ray monitoring of Cygnus X-1 during the period 2010/mid-2012 which includes a remarkably prolonged 'soft state' phase (2010 June-2011 May). Previous 1-10 MeV observations of Cyg X-1 in this state hinted at a possible existence of a non-thermal particle component with substantial modifications of the Comptonized emission from the inner accretion disk. Our AGILE data, averaged over the mid-2010/mid-2011 soft state of Cygnus X-1, provide a significant upper limit for gamma-ray emission above 100 MeV of F{sub soft} < 20 Multiplication-Sign 10{sup -8} photons cm{sup -2} s{sup -1} , excluding the existence of prominent non-thermal emission above 100 MeV during the soft state of Cygnus X-1. We discuss theoretical implications of our findings in the context of high-energy emission models of black hole accretion. We also discuss possible gamma-ray flares detected by AGILE. In addition to a previously reported episode observed by AGILE in 2009 October during the hard state, we report a weak but important candidate for enhanced emission which occurred at the end of 2010 June (2010 June 30 10:00-2010 July 2 10:00 UT) exactly coinciding with a hard-to-soft state transition and before an anomalous radio flare. An appendix summarizes all previous high-energy observations and possible detections of Cygnus X-1 above 1 MeV.

  9. Unveiling the population of orphan Gamma Ray Bursts

    E-Print Network [OSTI]

    Ghirlanda, G; Campana, S; Vergani, S D; Japelj, J; Bernardini, M G; Burlon, D; D'Avanzo, P; Melandri, A; Gomboc, A; Nappo, F; Paladini, R; Pescalli, A; Salafia, O S; Tagliaferri, G

    2015-01-01T23:59:59.000Z

    Gamma Ray Bursts are detectable in the gamma-ray band if their jets are oriented towards the observer. However, for each GRB with a typical theta_jet, there should be ~2/theta_jet^2 bursts whose emission cone is oriented elsewhere in space. These off-axis bursts can be eventually detected when, due to the deceleration of their relativistic jets, the beaming angle becomes comparable to the viewing angle. Orphan Afterglows (OA) should outnumber the current population of bursts detected in the gamma-ray band even if they have not been conclusively observed so far at any frequency. We compute the expected flux of the population of orphan afterglows in the mm, optical and X-ray bands through a population synthesis code of GRBs and the standard afterglow emission model. We estimate the detection rate of OA by on-going and forthcoming surveys. The average duration of OA as transients above a given limiting flux is derived and described with analytical expressions: in general OA should appear as daily transients in o...

  10. TWO POPULATIONS OF GAMMA-RAY BURST RADIO AFTERGLOWS

    SciTech Connect (OSTI)

    Hancock, P. J.; Gaensler, B. M.; Murphy, T., E-mail: Paul.Hancock@Sydney.edu.au [Also at Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), The University of Sydney, Sydney, NSW 2006, Australia. (Australia)

    2013-10-20T23:59:59.000Z

    The detection rate of gamma-ray burst (GRB) afterglows is ?30% at radio wavelengths, much lower than in the X-ray (?95%) or optical (?70%) bands. The cause of this low radio detection rate has previously been attributed to limited observing sensitivity. We use visibility stacking to test this idea, and conclude that the low detection rate is instead due to two intrinsically different populations of GRBs: radio-bright and radio-faint. We calculate that no more than 70% of GRB afterglows are truly radio-bright, leaving a significant population of GRBs that lack a radio afterglow. These radio-bright GRBs have higher gamma-ray fluence, isotropic energies, X-ray fluxes, and optical fluxes than the radio-faint GRBs, thus confirming the existence of two physically distinct populations. We suggest that the gamma-ray efficiency of the prompt emission is responsible for the difference between the two populations. We also discuss the implications for future radio and optical surveys.

  11. Are we observing Lorentz violation in gamma ray bursts?

    E-Print Network [OSTI]

    Theodore G. Pavlopoulos

    2005-08-12T23:59:59.000Z

    From recent observations of gamma-ray bursts (GRBs), it appears that spectral time lags between higher-energy gamma rays photons and lower-energy photons vary with energy difference and time (distance) traveled. These lags appear to be smaller for the most luminous (close) bursts but larger for the fainter (farther away) bursts. From this observation, it has been suggested that it might be possible to determine the distance (L) these bursts have traveled from these time lags alone, without performing any red-shift measurements. These observed spreads (dispersion) of high-energy electromagnetic pulses of different energies with time contradict the special theory of relativity (STR). However, extended theories (ET) of the STR have been developed that contain a dispersive term, predicting the above observations. An example of such an ET is presented, allowing us to derive a relationship between time lags of gamma rays of different energies and distance L traveled from their origin. In addition, this theory predicts the origin of X-ray flashes.

  12. THE FIRST FERMI-LAT GAMMA-RAY BURST CATALOG

    SciTech Connect (OSTI)

    Ackermann, M. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Ajello, M. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States); Asano, K. [Interactive Research Center of Science, Tokyo Institute of Technology, Meguro City, Tokyo 152-8551 (Japan); Axelsson, M. [Department of Astronomy, Stockholm University, SE-106 91 Stockholm (Sweden); Baldini, L. [Università di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bechtol, K.; Bloom, E. D. [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); Bellazzini, R.; Bregeon, J. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bhat, P. N. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Bissaldi, E. [Institut für Astro- und Teilchenphysik and Institut für Theoretische Physik, Leopold-Franzens-Universität Innsbruck, A-6020 Innsbruck (Austria); Bonamente, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Bonnell, J.; Brandt, T. J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bouvier, A., E-mail: nicola.omodei@stanford.edu, E-mail: giacomov@slac.stanford.edu [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); and others

    2013-11-01T23:59:59.000Z

    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 (?> 20 MeV) ?-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected above 100 MeV and 7 GRBs above ?20 MeV. The first Fermi-LAT catalog of GRBs is a compilation of these detections and provides a systematic study of high-energy emission from GRBs for the first time. To generate the catalog, we examined 733 GRBs detected by the Gamma-Ray Burst Monitor (GBM) on Fermi and processed each of them using the same analysis sequence. Details of the methodology followed by the LAT collaboration for the GRB analysis are provided. We summarize the temporal and spectral properties of the LAT-detected GRBs. We also discuss characteristics of LAT-detected emission such as its delayed onset and longer duration compared with emission detected by the GBM, its power-law temporal decay at late times, and the fact that it is dominated by a power-law spectral component that appears in addition to the usual Band model.

  13. Gamma-ray lines from SN2014J

    E-Print Network [OSTI]

    Siegert, Thomas

    2015-01-01T23:59:59.000Z

    On 21 January 2014, SN2014J was discovered in M82 and found to be the closest type Ia supernova (SN Ia) in the last four decades. INTEGRAL observed SN2014J from the end of January until late June for a total exposure time of about 7 Ms. SNe Ia light curves are understood to be powered by the radioactive decay of iron peak elements of which $^{56}$Ni is dominantly synthesized during the thermonuclear disruption of a CO white dwarf (WD). The measurement of $\\gamma$-ray lines from the decay chain $^{56}$Ni$\\rightarrow$$^{56}$Co$\\rightarrow$$^{56}$Fe provides unique information about the explosion in supernovae. Canonical models assume $^{56}$Ni buried deeply in the supernova cloud, absorbing most of the early $\\gamma$-rays, and only the consecutive decay of $^{56}$Co should become directly observable through the overlaying material several weeks after the explosion when the supernova envelope dilutes as it expands. Surprisingly, with the spectrometer on INTEGRAL, SPI, we detected $^{56}$Ni $\\gamma$-ray lines at ...

  14. The Gamma Ray Burst Rate at High Photon Energies

    E-Print Network [OSTI]

    Karl Mannheim; Dieter Hartmann; Burkhardt Funk

    1996-05-17T23:59:59.000Z

    Some gamma-ray burst (GRB) spectra exhibit high energy tails with the highest photon energy detected at 18 GeV. The spectral slope of the high-energy tails is sufficiently flat in nu F_nu to consider the possibility of their detection at still higher energies. We calculate how many bursts can reasonably be expected above a given energy threshold for a cosmological distribution of bursts satisfying the observed apparent brightness distribution. The crucial point is that the gamma-ray absorption by pair production in the intergalactic diffuse radiation field eliminates bursts from beyond the gamma-ray horizon tau ~ 1, thus drastically reducing the number of bursts at high energies. Our results are consistent with the non-detection of bursts by current experiments in the 100 GeV to 100 TeV energy range. For the earth-bound detector array MILAGRO, we predict a maximal GRB rate of ~ 10 events per year. The Whipple Observatory can detect, under favorable conditions, ~1 event per year. The event rate for the HEGRA array is ~ 0.01 per year. Detection of significantly higher rates of bursts would severely challenge cosmological burst scenarios.

  15. Gamma-Ray Bursts Above 1 GeV

    E-Print Network [OSTI]

    Matthew G. Baring

    1997-11-21T23:59:59.000Z

    One of the principal results obtained by the Compton Gamma Ray Observatory relating to the study of gamma-ray bursts was the detection by the EGRET instrument of energetic ($>$100 MeV) photons from a handful of bright bursts. The most extreme of these was the single 18 GeV photon from the GRB940217 source. Given EGRET's sensitivity and limited field of view, the detection rate implies that such high energy emission may be ubiquitous in bursts. Hence expectations that bursts emit out to at least TeV energies are quite realistic, and the associated target-of-opportunity activity of the TeV gamma-ray community is well-founded. This review summarizes the observations and a handful of theoretical models for generating GeV--TeV emission in bursts sources, outlining possible ways that future positive detections could discriminate between different scenarios. The power of observations in the GeV--TeV range to distinguish between spectral structure intrinsic to bursts and that due to the intervening medium between source and observer is also discussed.

  16. Thermal-neutron capture gamma-rays. Volume 1

    SciTech Connect (OSTI)

    Tuli, J.K. [National Nuclear Data Center, Upton, NY (United States)

    1997-05-01T23:59:59.000Z

    The energy and photon intensity of gamma rays as seen in thermal-neutron capture are presented in ascending order of gamma energy. All those gamma-rays with intensity of {ge} 2% of the strongest transition are included. The two strongest transitions seen for the target nuclide are indicated in each case. Where the target nuclide mass number is indicated as nat the natural target was used. The gamma energies given are in keV. The gamma intensities given are relative to 100 for the strongest transition. All data for A > 44 are taken from Evaluated Nuclear Structure Data File (4/97), a computer file of evaluated nuclear structure data maintained by the National Nuclear Data Center, Brookhaven National Laboratory, on behalf of the Nuclear Structure and Decay and Decay Data network, coordinated by the International Atomic Energy Agency, Vienna. These data are published in Nuclear Data Sheets, Academic Press, San Diego, CA. The data for A {le} 44 is taken from ``Prompt Gamma Rays from Thermal-Neutron Capture,`` M.A. Lone, R.A. Leavitt, D.A. Harrison, Atomic Data and Nuclear Data Tables 26, 511 (1981).

  17. A Flexible Architecture for Statistical Learning and Data Mining from System Log Streams

    E-Print Network [OSTI]

    Xu, Wei

    A Flexible Architecture for Statistical Learning and Data Mining from System Log Streams Wei Xu. Human operators monitoring the sys- tem use the log data and their experience to detect failures information than the operators can discern. The data might be used to predict that a particular machine

  18. Mining Logs Files for Data-Driven System Management School of Computer Science

    E-Print Network [OSTI]

    Li, Tao

    Mining Logs Files for Data-Driven System Management Wei Peng School of Computer Science Florida of the log files have been less emphasized in existing methods from data mining and machine learning in data representation pose new challenges. In this paper, we will describe our research efforts on mining

  19. Invited Applications Paper Detecting Large-Scale System Problems by Mining Console Logs

    E-Print Network [OSTI]

    Xu, Wei

    . Researchers and operators have been using all kinds of mon- itoring data, from the simplest numerical metrics Problems by Mining Console Logs part operator, and charged with fixing the problem-- are usuallyInvited Applications Paper Detecting Large-Scale System Problems by Mining Console Logs Wei Xu xuw

  20. Gamma Ray Burst triggering Supernova Explosion (and other effects on neighbouring stars)

    E-Print Network [OSTI]

    C. Sivaram; Kenath Arun

    2010-09-28T23:59:59.000Z

    The initial burst of a gamma ray burst (GRB) is usually followed by a longer-lived afterglow emitted at longer wavelengths. The evidence for a physical connection between GRBs and core collapse supernovae (SN) has increased since the discovery of GRB afterglows. So far SN signatures have been found in only a few GRBs. Here we propose the possibility of a GRB triggering the collapse of a WR or RG star in a binary system producing a SN, and typical signatures. We also look at the effects of GRBs on MS and WD stars in the neighbourhood. The possibility of GRBs retarding star formation in an interstellar cloud is also discussed.

  1. The Synergy of Gamma-Ray Burst Detectors in the GLAST Era

    E-Print Network [OSTI]

    David Band; for the GLAST collaboration

    2008-01-31T23:59:59.000Z

    Simultaneous observations by the large number of gamma-ray burst detectors operating in the GLAST era will provide the spectra, lightcurves and locations necessary for studying burst physics and testing the putative relations between intrinsic burst properties. The detectors' energy band and the accumulation timescale of their trigger system affect their sensitivity to hard vs. soft and long vs. short bursts. Coordination of the Swift and GLAST observing plans consistent with Swift's other science objectives could increase the detection rate of GLAST bursts with redshifts.

  2. Investigation of delayed neutron emission through neutron and gamma- ray spectroscopy

    E-Print Network [OSTI]

    Kratz, K L; Ohm, H; Franz, H; Ristori, C; Zendel, M; Herrmann, G; Nuh, F M; Slaughter, D R; Shihab-Eldin, A A; Prussin, S G

    1976-01-01T23:59:59.000Z

    Fast radiochemical separations have permitted detailed and high resolution measurements of neutron and gamma -ray spectra from several delayed neutron emitting systems. The apparent discrete line structure in delayed neutron spectra, high intensity neutron branching to excited states in decay of intermediate levels in the emitter, and the peaking in the beta /sup -/-decay intensity to regions well above the neutron binding energy, indicate persistence of distinct nuclear structure effects at excitation energies of 5-7 MeV in the emitter nuclides.

  3. Fresnel lenses for X-ray and Gamma-ray Astronomy

    E-Print Network [OSTI]

    Gerry Skinner; Peter von Ballmoos; Neil Gehrels; John Krizmanic

    2003-08-25T23:59:59.000Z

    Phase Fresnel lenses have the same imaging properties as zone plates, but with the possibility of concentrating all of the incident power into the primary focus, increasing the maximum theoretical efficiency from 11% to close to 100%. For X-rays, and in particular for gamma-rays, large, diffraction-limited phase Fresnel lenses can be made relatively easily. The focal length is very long - for example up to a million kms. However, the correspondingly high `plate-scale' of the image means that the ultra-high (sub-micro-arc-second) angular resolution possible with a diffraction limited gamma-ray lens a few metres in diameter can be exploited with detectors having \\~mm spatial resolution. The potential of such systems for ultra-high angular resolution astronomy, and for attaining the sensitivity improvements desperately needed for certain other studies, are reviewed and the advantages and disadvantages vis-a-vis alternative approaches are discussed. We report on reduced-scale 'proof-of-principle tests' which are planned and on mission studies of the implementation of a Fresnel telescope on a space mission with lens and detector on two spacecraft separated by one million km. Such a telescope would be capable of resolving emission from super-massive black holes on the scale of their event horizons and would have the sensitivity necessary to detect gamma-ray lines from distant supernovae. We show how diffractive/refractive optics leads to a continuum of possible system designs between filled aperture lenses and wideband interferometric arrays.

  4. ON THE RECENTLY DISCOVERED CORRELATIONS BETWEEN GAMMA-RAY AND X-RAY PROPERTIES OF GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Dado, Shlomo; Dar, Arnon [Physics Department, Technion, Haifa 32000 (Israel)

    2013-09-20T23:59:59.000Z

    Recently, many correlations between the prompt {gamma}-ray emission properties and the X-ray afterglow properties of gamma-ray bursts (GRBs) have been inferred from a comprehensive analysis of the X-ray light curves of more than 650 GRBs measured with the Swift X-Ray Telescope (Swift/XRT) during the years 2004-2010. We show that these correlations are predicted by the cannonball (CB) model of GRBs. They result from the dependence of GRB observables on the bulk motion Lorentz factor and viewing angle of the jet of highly relativistic plasmoids (CBs) that produces the observed radiations by interaction with the medium through which it propagates. Moreover, despite their different physical origins, long GRBs (LGRBs) and short-hard bursts (SHBs) in the CB model share similar kinematic correlations, which can be combined into triple correlations satisfied by both LGRBs and SHBs.

  5. HIGH PURITY GE GAMMA-RAY SPECTROMETER ON JAPANESE LUNAR POLAR ORBITER , M.-N. Kobayashi1

    E-Print Network [OSTI]

    Berezhnoi, Aleksei A.

    of three parts; gamma-ray detector (GRD), compressor driver unit (CDU) and gamma- ray and particle purified Ge detector is employed as a main detector, by which gamma-rays can be detected in the energyHIGH PURITY GE GAMMA-RAY SPECTROMETER ON JAPANESE LUNAR POLAR ORBITER SELENE. N. Hasebe1 , M

  6. GRB 050117: SIMULTANEOUS GAMMA-RAY AND X-RAY OBSERVATIONS WITH THE SWIFT SATELLITE Joanne E. Hill,1, 2

    E-Print Network [OSTI]

    Zhang, Bing

    The Swift Gamma-Ray Burst Explorer performed its first autonomous, X-ray follow-up to a newly detected GRB from the XRT position. Subject headingg: gamma rays: bursts 1. INTRODUCTION The Swift Gamma-ray Burst Explorer (Gehrels et al. 2004) was launched on 2004 November 20 to study gamma-ray bursts (GRBs) over

  7. THE HIGH-ENERGY GAMMA-RAY FLUENCE AND ENERGY SPECTRUM OF GRB 970417a FROM OBSERVATIONS WITH MILAGRITO

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    of this observation are discussed. Subject headings: gamma rays: bursts -- gamma rays: observations 1. INTRODUCTION Some of the most important contributions to our under- standing of gamma-ray bursts (GRBs) have comeTHE HIGH-ENERGY GAMMA-RAY FLUENCE AND ENERGY SPECTRUM OF GRB 970417a FROM OBSERVATIONS

  8. Coal-log pipeline system development. Fifth quarterly report, August 25, 1991--November 25, 1991

    SciTech Connect (OSTI)

    Liu, H.

    1991-12-01T23:59:59.000Z

    Project tasks include: (1) Perform the necessary testing and development to demonstrate that the amount of binder in coal logs can be reduced to 8% or lower to produce logs with adequate strength to eliminate breakage during pipeline transportation, under conditions experienced in long distance pipeline systems. Prior to conducting any testing and demonstration, grantee shall perform an information search and make full determination of all previous attempts to extrude or briquette coal, upon which the testing and demonstration shall be based. (2) Perform the necessary development to demonstrate a small model of the most promising injection system for coal-logs, and tests the logs produced. (3) Conduct economic analysis of coal-log pipeline, based upon the work to date. Refine and complete the economic model. (VC)

  9. On the sensitivity of the HAWC observatory to gamma-ray bursts

    E-Print Network [OSTI]

    Abeysekara, A U; Aguilar, S; Alfaro, R; Almaraz, E; Álvarez, C; Álvarez-Romero, J de D; Álvarez, M; Arceo, R; Arteaga-Velázquez, J C; Badillo, C; Barber, A; Baughman, B M; Bautista-Elivar, N; Belmont, E; Benítez, E; BenZvi, S Y; Berley, D; Bernal, A; Bonamente, E; Braun, J; Caballero-Lopez, R; Cabrera, I; Carramiñana, A; Carrasco, L; Castillo, M; Chambers, L; Conde, R; Condreay, P; Cotti, U; Cotzomi, J; D'Olivo, J C; de la Fuente, E; De León, C; Delay, S; Delepine, D; DeYoung, T; Diaz, L; Diaz-Cruz, L; Dingus, B L; Duvernois, M A; Edmunds, D; Ellsworth, R W; Fick, B; Fiorino, D W; Flandes, A; Fraija, N I; Galindo, A; García-Luna, J L; García-Torales, G; Garfias, F; González, L X; González, M M; Goodman, J A; Grabski, V; Gussert, M; Guzmán-Ceron, C; Hampel-Arias, Z; Harris, T; Hays, E; Hernandez-Cervantes, L; Hüntemeyer, P H; Imran, A; Iriarte, A; Jimenez, J J; Karn, P; Kelley-Hoskins, N; Kieda, D; Langarica, R; Lara, A; Lauer, R; Lee, W H; Linares, E C; Linnemann, J T; Longo, M; Luna-García, R; Martínez, H; Martínez, J; Martínez, L A; Martínez, O; Martínez-Castro, J; Martos, M; Matthews, J; McEnery, J E; Medina-Tanco, G; Mendoza-Torres, J E; Miranda-Romagnoli, P A; Montaruli, T; Moreno, E; Mostafa, M; Napsuciale, M; Nava, J; Nellen, L; Newbold, M; Noriega-Papaqui, R; Oceguera-Becerra, T; Tapia, A Olmos; Orozco, V; Pérez, V; Pérez-Pérez, E G; Perkins, J S; Pretz, J; Ramirez, C; Ramírez, I; Rebello, D; Rentería, A; Reyes, J; Rosa-González, D; Rosado, A; Ryan, J M; Sacahui, J R; Salazar, H; Salesa, F; Sandoval, A; Santos, E; Schneider, M; Shoup, A; Silich, S; Sinnis, G; Smith, A J; Sparks, K; Springer, W; Suárez, F; Suarez, N; Taboada, I; Tellez, A F; Tenorio-Tagle, G; Tepe, A; Toale, P A; Tollefson, K; Torres, I; Ukwatta, T N; Valdes-Galicia, J; Vanegas, P; Vasileiou, V; Vázquez, O; Vázquez, X; Villaseñor, L; Wall, W; Walters, J S; Warner, D; Westerhoff, S; Wisher, I G; Wood, J; Yodh, G B; Zaborov, D; Zepeda, A

    2011-01-01T23:59:59.000Z

    We present the sensitivity of HAWC to Gamma Ray Bursts (GRBs). HAWC is a very high-energy gamma-ray observatory currently under construction in Mexico at an altitude of 4100 m. It will observe atmospheric air showers via the water Cherenkov method. HAWC will consist of 300 large water tanks instrumented with 4 photomultipliers each. HAWC has two data acquisition (DAQ) systems. The main DAQ system reads out coincident signals in the tanks and reconstructs the direction and energy of individual atmospheric showers. The scaler DAQ counts the hits in each photomultiplier tube (PMT) in the detector and searches for a statistical excess over the noise of all PMTs. We show that HAWC has a realistic opportunity to observe the high-energy power law components of GRBs that extend at least up to 30 GeV, as it has been observed by Fermi LAT. The two DAQ systems have an energy threshold that is low enough to observe events similar to GRB 090510 and GRB 090902b with the characteristics observed by Fermi LAT. HAWC will prov...

  10. Operator`s guide for VAXGAP, a gamma-ray spectrum analysis package

    SciTech Connect (OSTI)

    Killian, E.W.; Femec, D.A.

    1992-08-01T23:59:59.000Z

    This report describes the gamma-ray analysis program VAXGAP, which has continually evolved at the Idaho National Engineering Laboratory over a period of several years. It is an integrated suite of computer programs for performing analyses of pulse-height spectra from high-resolution gamma-ray spectrometers and assorted support functions. VAXGAP programs operate on Digital Equipment Corporation (DEC) VAX computers running the VMS operating system, and were written in VAX FORTRAN and DEC Digital Command Language (DCL). These programs make use of DEC GKS and ReGIS for graphical output on standard terminals and printers, and DEC windows for graphics on workstations and terminals that support the X Window System protocol. This report addresses the use of VAXGAP for data acquisition and control, energy scale calibration, and real-time analyses of background and sample pulse-height spectra. Also addressed are the creation and use efficiency tables and isotope libraries, manipulation of spectrum files and their contents, and graphical display of on-going acquisitions, saved spectra, and mathematical fits to spectral peaks.

  11. Operator's guide for VAXGAP, a gamma-ray spectrum analysis package

    SciTech Connect (OSTI)

    Killian, E.W.; Femec, D.A.

    1992-08-01T23:59:59.000Z

    This report describes the gamma-ray analysis program VAXGAP, which has continually evolved at the Idaho National Engineering Laboratory over a period of several years. It is an integrated suite of computer programs for performing analyses of pulse-height spectra from high-resolution gamma-ray spectrometers and assorted support functions. VAXGAP programs operate on Digital Equipment Corporation (DEC) VAX computers running the VMS operating system, and were written in VAX FORTRAN and DEC Digital Command Language (DCL). These programs make use of DEC GKS and ReGIS for graphical output on standard terminals and printers, and DEC windows for graphics on workstations and terminals that support the X Window System protocol. This report addresses the use of VAXGAP for data acquisition and control, energy scale calibration, and real-time analyses of background and sample pulse-height spectra. Also addressed are the creation and use efficiency tables and isotope libraries, manipulation of spectrum files and their contents, and graphical display of on-going acquisitions, saved spectra, and mathematical fits to spectral peaks.

  12. Elemental mapping of the moon using gamma rays : past, present, and future /

    SciTech Connect (OSTI)

    Reedy, R. C. (Robert C.)

    2001-01-01T23:59:59.000Z

    The energies and intensities of gamma rays From a planetary surface can be used to infer the elemental composition of an object with no or a thin atmosphere. The Apollo gamma-ray spectrometers in 1972 and 1973 produced many of the results for the distribution of elements in the Moon that are now generally well accepted. Lunar Prospector in 1998 and 1999 globally mapped the Moon with gamma rays and neutrons. Both missions used spectrometers with poor energy resolution ({approx}8-10%). The Japanese plan to send a high-resolution germanium gamma-ray spectrometer to the Moon in about 2004 on their SELENE mission. However, little has been done since the 1970s on the models used to unfold planetary gamma-ray spectra. More work needs to be done on understanding what to expect in future gamma-ray spectra and how to unfold such data.

  13. Are Durations of Weak Gamma-Ray Bursts Reliable?

    E-Print Network [OSTI]

    Maarten Schmidt

    2005-08-16T23:59:59.000Z

    Simulations in the GUSBAD Catalog of gamma-ray bursts suggest that the apparent duration of a burst decreases as its amplitude is decreased. We see no evidence for this effect in the BATSE catalog. We show that for a burst at the detection limit, the typical signal-to-noise ratio at the edges of the T90 duration is around 1.5, suggesting that T90 must be quite uncertain. The situation for T50 is less unfavorable. Simulations using the exact procedure to derive the durations in the BATSE catalog would be useful in quantifying the effect.

  14. INTERPLANETARY NETWORK LOCALIZATIONS OF KONUS SHORT GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Pal'shin, V. D.; Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Mazets, E. P.; Oleynik, P. P.; Ulanov, M. V. [Ioffe Physical Technical Institute, St. Petersburg, 194021 (Russian Federation); Hurley, K. [Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Cline, T.; Trombka, J.; McClanahan, T. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S.; Litvak, M. L.; Sanin, A. B. [Space Research Institute, 84/32, Profsoyuznaya, Moscow 117997 (Russian Federation); Boynton, W.; Fellows, C.; Harshman, K., E-mail: val@mail.ioffe.ru [Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721 (United States); and others

    2013-08-15T23:59:59.000Z

    Between the launch of the Global Geospace Science Wind spacecraft in 1994 November and the end of 2010, the Konus-Wind experiment detected 296 short-duration gamma-ray bursts (including 23 bursts which can be classified as short bursts with extended emission). During this period, the Interplanetary Network (IPN) consisted of up to 11 spacecraft, and using triangulation, the localizations of 271 bursts were obtained. We present the most comprehensive IPN localization data on these events. The short burst detection rate, {approx}18 yr{sup -1}, exceeds that of many individual experiments.

  15. GeV Emission from Collisional Magnetized Gamma Ray Bursts

    E-Print Network [OSTI]

    P. Mészáros; M. J. Rees

    2011-04-26T23:59:59.000Z

    Magnetic fields may play a dominant role in gamma-ray bursts, and recent observations by the Fermi satellite indicate that GeV radiation, when detected, arrives delayed by seconds from the onset of the MeV component. Motivated by this, we discuss a magnetically dominated jet model where both magnetic dissipation and nuclear collisions are important. We show that, for parameters typical of the observed bursts, such a model involving a realistic jet structure can reproduce the general features of the MeV and a separate GeV radiation component, including the time delay between the two. The model also predicts a multi-GeV neutrino component.

  16. Can Sequentially Linked Gamma-Ray Bursts Nullify Randomness?

    E-Print Network [OSTI]

    Charles Fleischer

    2012-05-02T23:59:59.000Z

    In order to nullify the property of randomness perceived in the dispersion of gamma-ray bursts (GRB's) we introduce two new procedures. 1. Create a segmented group of sequentially linked GRB's and quantify the resultant angles. 2. Create segmented groups of sequentially linked GRB's in order to identify the location of GRB's that are positioned at equidistance, by using the selected GRB as the origin for a paired point circle, where the circumference of said circle intercepts the location of other GRB's in the same group.

  17. Gamma ray burst distances and the timescape cosmology

    E-Print Network [OSTI]

    Peter R. Smale

    2011-08-22T23:59:59.000Z

    Gamma ray bursts can potentially be used as distance indicators, providing the possibility of extending the Hubble diagram to redshifts ~7. Here we follow the analysis of Schaefer (2007), with the aim of distinguishing the timescape cosmological model from the \\LambdaCDM model by means of the additional leverage provided by GRBs in the range 2 < z < 7. We find that the timescape model fits the GRB sample slightly better than the \\LambdaCDM model, but that the systematic uncertainties are still too little understood to distinguish the models.

  18. High Energy Neutrinos from Cosmological Gamma-Ray Burst Fireballs

    E-Print Network [OSTI]

    Eli Waxman; John Bahcall

    1997-01-30T23:59:59.000Z

    Observations suggest that $\\gamma$-ray bursts (GRBs) are produced by the dissipation of the kinetic energy of a relativistic fireball. We show that a large fraction, $\\ge 10%$, of the fireball energy is expected to be converted by photo-meson production to a burst of $\\sim10^{14} eV$ neutrinos. A km^2 neutrino detector would observe at least several tens of events per year correlated with GRBs, and test for neutrino properties (e.g. flavor oscillations, for which upward moving $\\tau$'s would be a unique signature, and coupling to gravity) with an accuracy many orders of magnitude better than is currently possible.

  19. Reverse Shock Emission in Gamma-ray Bursts Revisited

    E-Print Network [OSTI]

    Gao, He

    2015-01-01T23:59:59.000Z

    A generic synchrotron external shock model is the widely preferred paradigm used to interpret the broad-band afterglow data of gamma-ray bursts (GRBs), including predicted observable signatures from a reverse shock which have been confirmed by observations. Investigations of the nature of the reverse shock emission can provide valuable insights into the intrinsic properties of the GRB ejecta. Here we briefly review the standard and the extended models of the reverse shock emission, discussing the connection between the theory and observations, including the implications of the latest observational advances.

  20. Long gamma-ray bursts trace the star formation history

    SciTech Connect (OSTI)

    Dado, Shlomo; Dar, Arnon [Physics Department, Technion, Haifa 32000 (Israel)

    2014-04-10T23:59:59.000Z

    We show that if the broad-line supernova explosions of Type Ic (SNeIc) produce the bulk of the observed long duration gamma-ray bursts (LGRBs), including high- and low-luminosity LGRBs and X-ray flashes, and if the LGRBs have the geometry assumed in the cannonball model of LGRBs, then their rate, measured by Swift, and their redshift distribution are consistent with the star formation rate (SFR) over the entire range of redshifts where the SFR has been measured with sufficient accuracy.

  1. On the Power Spectrum Density of Gamma Ray Bursts

    E-Print Network [OSTI]

    Motoko Suzuki; Masahiro Morikawa; Izumi Joichi

    2001-04-13T23:59:59.000Z

    Gamma ray bursts (GRBs) are known to have short-time variability and power-law behavior with the index -1.67 in the power spectrum density. Reanalyzing the expanded data, we have found a) the power-law comes from the global profile of the burst and not from the self-similar shots nor rapid fluctuations in the luminosity profile. b) The power indices vary from burst to burst and the value -1.67 is given simply as the mean value of the distribution; there is no systematic correlation among GRBs to yield the power law.

  2. Galactic Center Gamma Ray Excess and Higgs Boson(s)

    E-Print Network [OSTI]

    Ipek, Seyda

    2015-01-01T23:59:59.000Z

    There is evidence for an excess of gamma rays with $O({\\rm GeV})$ energy coming from the Galactic Center in data from the Fermi Telescope. The spectrum of the excess is well fit by 30 GeV dark matter annihilating into a pair of $b$ quarks with a cross section expected from a thermal relic. For an explanation of this excess, we study a renormalizable model where dark matter couples to the SM via a pseudoscalar that mixes with the $CP$-odd Higgs boson of a Two HIggs Doublet Model. We report the constraints on this model from direct detection, Higgs decays, and rare $B$ meson decays.

  3. Tail Emission of Prompt Gamma-Ray Burst Jets

    E-Print Network [OSTI]

    Yamazaki, R; Ioka, K; Nakamura, T; Yamazaki, Ryo; Toma, Kenji; Ioka, Kunihito; Nakamura, Takashi

    2006-01-01T23:59:59.000Z

    Tail emission of the prompt gamma-ray burst is discussed using a multiple emitting sub-shell (inhomogeneous jet, sub-jets) model. The tail is a superposition of a number of smooth, long-duration, dim, and soft pulses emitted by segments located far from the line of sight. We find that the behavior of the tail is not so much affected by the local inhomogeneity but affected by the global sub-jet distribution. Some observed tails may disfavor the power-law jets.

  4. Gamma-ray free-electron lasers: Quantum fluid model

    E-Print Network [OSTI]

    Silva, H M

    2014-01-01T23:59:59.000Z

    A quantum fluid model is used to describe the interacion of a nondegenerate cold relativistic electron beam with an intense optical wiggler taking into account the beam space-charge potential and photon recoil effect. A nonlinear set of coupled equations are obtained and solved numerically. The numerical results shows that in the limit of plasma wave-breaking an ultra-high power radiation pulse are emitted at the$\\gamma$-ray wavelength range which can reach an output intensity near the Schwinger limit depending of the values of the FEL parameters such as detuning and input signal initial phase at the entrance of the interaction region.

  5. Gamma-ray bursts and the sociology of science

    E-Print Network [OSTI]

    A. De Rujula

    2003-06-16T23:59:59.000Z

    I discuss what we have learned about Gamma-Ray Bursts (GRBs) by studying their `afterglows', and how these are interpreted in the generally-accepted `fireball' model of GRBs, as well as in the generally-unaccepted `cannonball' model of the same phenomena. The interpretation of GRBs is a good example around which to frame a discussion of the different approaches to science found in various fields, such as high-energy physics (HEP), high-energy astrophysics, or even the deciphering of ancient languages. I use this example to draw conclusions on `post-academic' science, and on the current status of European HEP.

  6. Gamma-Ray Bursts from Primordial Quark Objects in Space

    E-Print Network [OSTI]

    B. Anoushirvani; D. Enström; S. Fredriksson; J. Hansson; P. Ökvist; A. Nicolaidis; S. Ekelin

    1997-11-28T23:59:59.000Z

    We investigate the possibility that gamma-ray bursts originate in a concentric spherical shell with a given average redshift and find that this is indeed compatible with the data from the third BATSE (3B) catalog. It is also shown that there is enough freedom in the choice of unknown burst properties to allow even for extremely large distances to the majority of bursts. Therefore, we speculate about an early, and very energetic, origin of bursts, and suggest that they come from phase transitions in massive objects of pure quark matter, left over from the Big Bang.

  7. Gamma-Ray Bursts and Dark Matter - a joint origin?

    E-Print Network [OSTI]

    Daniel Enstrom

    1998-10-14T23:59:59.000Z

    A scenario is presented where large quark-gluon plasma (QGP) objects escaping the quark-hadron transition in the early Universe account for the baryonic dark matter as well as act as the sources for gamma-ray bursts. Two basic assumptions are made. Firstly, we assume that a QGP consisting of u,d and s quarks is the absolute ground state of QCD and secondly, that the quark-hadron transition in the early Universe was of first order. Both particle physics and astrophysics constraints are discussed, mainly from an observational point of view.

  8. Gamma-ray Bursts Produced by Mirror Stars

    E-Print Network [OSTI]

    S. Blinnikov

    1999-02-21T23:59:59.000Z

    I argue that cosmic Gamma-ray Bursts (GRB) may be produced by collapses or mergers of stars made of `mirror' matter. The mirror neutrinos (which are sterile for our matter) produced at these events can oscillate into ordinary neutrinos. The annihilations or decays of the latter create an electron-positron plasma and subsequent relativistic fireball with a very low baryon load needed for GRBs. The concept of mirror matter is able to explain several key problems of modern astrophysics: neutrino anomalies, the missing mass, MACHO microlensing events and GRBs. Thus this concept becomes very appealing and should be considered quite seriously and attentively.

  9. Gamma-Ray Bursts and Quantum Cosmic Censorship

    E-Print Network [OSTI]

    T. P. Singh

    1998-05-17T23:59:59.000Z

    Gamma-ray bursts are believed to result from the coalescence of binary neutron stars. However, the standard proposals for conversion of the gravitational energy to thermal energy have difficulties. We show that if the merger of the two neutron stars results in a naked singularity, instead of a black hole, the ensuing quantum particle creation can provide the requisite thermal energy in a straightforward way. The back-reaction of the created particles can avoid the formation of the naked singularity predicted by the classical theory. Hence cosmic censorship holds in the quantum theory, even if it were to be violated in classical general relativity.

  10. High Efficiency of Gamma-Ray Bursts Revisited

    E-Print Network [OSTI]

    Y. C. Zou; Z. G. Dai

    2007-03-07T23:59:59.000Z

    Using the conservation of energy and momentum during collisions of any two shells, we consider the efficiency of gamma-ray bursts by assuming that the ejecta from the central engine are equally massive and have the same Lorentz factors. We calculate the efficiency and the final Lorentz factor of the merged whole shell for different initial diversities of Lorentz factors and for different microscopic radiative efficiency. As a result, a common high efficiency in the range of 0.1 to 0.9 is considerable, and a very high value near 100% is also reachable if the diversity of the Lorentz factors is large enough.

  11. Composite mirror facets for ground based gamma ray astronomy

    E-Print Network [OSTI]

    Brun, P; Durand, D; Glicenstein, J-F; Jeanney, C; Medina, M C; Micolon, P; Peyaud, B

    2013-01-01T23:59:59.000Z

    Composite mirrors for gamma-ray astronomy have been developed to fulfill the specifications required for the next generation of Cherenkov telescopes represented by CTA (Cherenkov Telescope Array). In addition to the basic requirements on focus and reflection efficiency, the mirrors have to be stiff, lightweight, durable and cost efficient. In this paper, the technology developed to produce such mirrors is described, as well as some tests that have been performed to validate them. It is shown that these mirrors comply with the needs of CTA, making them good candidates for use on a significant part of the array.

  12. Distance and spectrum of the Apollo gamma-ray burst

    SciTech Connect (OSTI)

    Gilman, D.; Metzger, A.E.; Parker, R.H.; Evans, L.G.; Trombka, J.I.

    1980-03-15T23:59:59.000Z

    The ..gamma..-ray spectrometer on Apollo 16 obtained spectral information with good energy resolution from more than 2500 burst photons in the energy range 0.06--5.16 MeV. The spectrum from 2 keV to 2 MeV, observed at X-ray energies by the Apollo X-ray spectrometer, is fitted by a thermal bremsstrahlung spectrum with kT=500 keV. The success of the fit implies that the source is optically thin, and it follows that it must be closer than 50 pc. Absence of spectral variability suggests that the burst results from isothermal changes in emission measure.

  13. Milagro: A TeV Gamma-Ray Monitor of the Northern Hemisphere Sky

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    transients, such as gamma-ray bursts, and all sky surveys are diÆcult. A new type of TeV -ray observatoryMilagro: A TeV Gamma-Ray Monitor of the Northern Hemisphere Sky B.L. Dingus 1 , R. Atkins 1 , W type of very high energy (> a few 100 GeV) gamma-ray observatory, Milagro, has been built with a large

  14. Are Short and Long Gamma Ray Bursts Really of Different Origin?

    E-Print Network [OSTI]

    Ernst Karl Kunst

    2000-12-06T23:59:59.000Z

    It is shown that short and long gamma ray bursts (GRBs) are of the same origin and, furthermore, correlated with their duration.

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

    SciTech Connect (OSTI)

    Dickens, J.K.

    1981-03-01T23:59:59.000Z

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

  16. Swift Pointing and the Association Between Gamma-Ray Bursts and Gravitational-Wave Bursts

    E-Print Network [OSTI]

    Lee Samuel Finn; Badri Krishnan; Patrick J. Sutton

    2003-04-11T23:59:59.000Z

    The currently accepted model for gamma-ray burst phenomena involves the violent formation of a rapidly rotating solar mass black hole. Gravitational waves should be associated with the black-hole formation, and their detection would permit this model to be tested, the black hole progenitor (e.g., coalescing binary or collapsing stellar core) identified, and the origin of the gamma rays (within the expanding relativistic fireball or at the point of impact on the interstellar medium) located. Even upper limits on the gravitational-wave strength associated with gamma-ray bursts could constrain the gamma-ray burst model. To do any of these requires joint observations of gamma-ray burst events with gravitational and gamma-ray detectors. Here we examine how the quality of an upper limit on the gravitational-wave strength associated with gamma-ray burst observations depends on the relative orientation of the gamma-ray-burst and gravitational-wave detectors, and apply our results to the particular case of the Swift Burst-Alert Telescope (BAT) and the LIGO gravitational-wave detectors. A result of this investigation is a science-based ``figure of merit'' that can be used, together with other mission constraints, to optimize the pointing of the Swift telescope for the detection of gravitational waves associated with gamma-ray bursts.

  17. Cosmic Rays, Gamma-Rays, & Neutrinos in the Starburst Nuclei of Arp 220

    E-Print Network [OSTI]

    Yoast-Hull, Tova M; Zweibel, Ellen G

    2015-01-01T23:59:59.000Z

    The cores of Arp 220, the closest ultra-luminous infrared starburst galaxy, provide an opportunity to study interactions of cosmic rays under extreme conditions. In this paper, we model the populations of cosmic rays produced by supernovae in the central molecular zones of both starburst nuclei. We find that ~65 - 100% of cosmic rays are absorbed in these regions due to their huge molecular gas contents, and thus, the nuclei of Arp 220 nearly complete proton calorimeters. As the cosmic ray protons collide with the interstellar medium, they produce secondary electrons that are also contained within the system and radiate synchrotron emission. Using results from chi-squared tests between the model and the observed radio spectral energy distribution, we predict the emergent gamma-ray and high-energy neutrino spectra and find the magnetic field to be at milligauss levels. Because of the extremely intense far-infrared radiation fields, the gamma-ray spectrum steepens significantly at TeV energies due to gamma-gamm...

  18. An Upper Bound on Neutron Star Masses from Models of Short Gamma-ray Bursts

    E-Print Network [OSTI]

    Lawrence, Scott; Bedaque, Paulo F; Miller, M Coleman

    2015-01-01T23:59:59.000Z

    The discovery of two neutron stars with gravitational masses $\\approx 2~M_\\odot$ has placed a strong lower limit on the maximum mass of a slowly rotating neutron star, and with it a strong constraint on the properties of cold matter beyond nuclear density. Current upper mass limits are much looser. Here we note that, if most short gamma-ray bursts are produced by the coalescence of two neutron stars, and if the merger remnant collapses quickly, then the upper mass limit is constrained tightly. We find that if the rotation of the merger remnant is limited only by mass-shedding (which seems plausible based on current numerical studies), then the maximum gravitational mass of a slowly rotating neutron star is between $\\approx 2~M_\\odot$ and $\\approx 2.2~M_\\odot$ if the masses of neutron stars that coalesce to produce gamma-ray bursts are in the range seen in Galactic double neutron star systems. These limits are increased by $\\sim 4$% if the rotation is slowed by $\\sim 30$%, and by $\\sim 15$% if the merger remna...

  19. THE SECOND FERMI GBM GAMMA-RAY BURST CATALOG: THE FIRST FOUR YEARS

    SciTech Connect (OSTI)

    Von Kienlin, Andreas; Greiner, Jochen; Gruber, David [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Meegan, Charles A.; Bhat, P. N.; Briggs, Michael S.; Burgess, J. Michael; Chaplin, Vandiver; Connaughton, Valerie; Goldstein, Adam [University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Paciesas, William S.; Cleveland, William [Universities Space Research Association, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Bissaldi, Elisabetta [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Byrne, David; Fitzpatrick, Gerard; Foley, Suzanne [School of Physics, University College Dublin, Belfield, Stillorgan Road, Dublin 4 (Ireland); Collazzi, Andrew C. [Astrophysics Office, ZP 12, NASA-Marshall Space Flight Center, Huntsville, AL 35812 (United States); Gibby, Melissa; Giles, Misty [Jacobs Technology, Inc., Huntsville, AL 35806 (United States); Guiriec, Sylvain [NASA-Goddard Space Flight Center, Greenbelt, MD 20771 (United States); and others

    2014-03-01T23:59:59.000Z

    This is the second of a series of catalogs of gamma-ray bursts (GRBs) observed with the Fermi Gamma-ray Burst Monitor (GBM). It extends the first two-year catalog by two more years, resulting in an overall list of 953 GBM triggered GRBs. The intention of the GBM GRB catalog is to provide information to the community on the most important observables of the GBM detected GRBs. For each GRB the location and main characteristics of the prompt emission, the duration, peak flux and fluence are derived. The latter two quantities are calculated for the 50-300 keV energy band, where the maximum energy release of GRBs in the instrument reference system is observed and also for a broader energy band from 10-1000 keV, exploiting the full energy range of GBMs low-energy detectors. Furthermore, information is given on the settings and modifications of the triggering criteria and exceptional operational conditions during years three and four in the mission. This second catalog is an official product of the Fermi GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center.

  20. Modelling the high-energy emission from gamma-ray binaries using numerical relativistic hydrodynamics

    E-Print Network [OSTI]

    Dubus, Guillaume; Fromang, Sébastien

    2015-01-01T23:59:59.000Z

    Detailed modeling of the high-energy emission from gamma-ray binaries has been propounded as a path to pulsar wind physics. Fulfilling this ambition requires a coherent model of the flow and its emission in the region where the pulsar wind interacts with the stellar wind of its companion. We developed a code that follows the evolution and emission of electrons in the shocked pulsar wind based on inputs from a relativistic hydrodynamical simulation. The code is used to model the well-documented spectral energy distribution and orbital modulations from LS 5039. The pulsar wind is fully confined by a bow shock and a back shock. The particles are distributed into a narrow Maxwellian, emitting mostly GeV photons, and a power law radiating very efficiently over a broad energy range from X-rays to TeV gamma rays. Most of the emission arises from the apex of the bow shock. Doppler boosting shapes the X-ray and VHE lightcurves, constraining the system inclination to $i\\approx 35^{\\rm o}$. There is a tension between th...

  1. Design and imaging performance of achromatic diffractive/refractive X-ray and Gamma-ray Fresnel lenses

    E-Print Network [OSTI]

    Gerald K. Skinner

    2004-07-21T23:59:59.000Z

    Achromatic combinations of a diffractive Phase Fresnel Lens and a refractive correcting element have been proposed for X-ray and gamma-ray astronomy and for microlithography, but considerations of absorption often dictate that the refractive component be given a stepped profile, resulting in a double Fresnel lens. The imaging performance of corrected Fresnel lenses, with and without `stepping' is investigated and the trade-off between resolution and useful bandwidth in different circumstances is discussed. Provided the focal ratio is large, correction lenses made of low atomic number materials can be used with X-rays in the range approximately 10--100 keV without stepping. The use of stepping extends the possibility of correction to higher aperture systems, to energies as low as a few kilo electron volts and to gamma-rays of $\\sim$ mega electron volt energy.

  2. Graphical Environment Tools for Application to Gamma-Ray Energy Tracking Arrays

    SciTech Connect (OSTI)

    Todd, Richard A. [RIS Corp.] [RIS Corp.; Radford, David C. [ORNL Physics Div.] [ORNL Physics Div.

    2013-12-30T23:59:59.000Z

    Highly segmented, position-sensitive germanium detector systems are being developed for nuclear physics research where traditional electronic signal processing with mixed analog and digital function blocks would be enormously complex and costly. Future systems will be constructed using pipelined processing of high-speed digitized signals as is done in the telecommunications industry. Techniques which provide rapid algorithm and system development for future systems are desirable. This project has used digital signal processing concepts and existing graphical system design tools to develop a set of re-usable modular functions and libraries targeted for the nuclear physics community. Researchers working with complex nuclear detector arrays such as the Gamma-Ray Energy Tracking Array (GRETA) have been able to construct advanced data processing algorithms for implementation in field programmable gate arrays (FPGAs) through application of these library functions using intuitive graphical interfaces.

  3. The SKA view of Gamma-ray Bursts

    E-Print Network [OSTI]

    Burlon, Davide; van der Horst, Alexander; Murphy, Tara; Wijers, Ralph; Gaensler, Bryan; Ghisellini, Gabriele; Prandoni, Isabella

    2015-01-01T23:59:59.000Z

    Gamma-ray bursts (GRBs) are some of the most extreme events in the Universe. As well as providing a natural laboratory for investigating fundamental physical processes, they might trace the cosmic star formation rate up to extreme redshifts and probe the composition of the intergalactic medium over most of the Universe's history. Radio observations of GRBs play a key part in determining their physical properties, but currently they are largely limited to follow-up observations of $\\gamma$-ray-detected objects. The SKA will significantly increase our ability to study GRB afterglows, following up several hundred objects in the high frequency bands already in the "early science" implementation of the telescope. SKA1-MID Bands 4 (4 GHz) and 5 (9.2 GHz) will be particularly suited to the detection of these transient phenomena. The SKA will trace the peak of the emission, sampling the thick-to-thin transition of the evolving spectrum, and follow-up the afterglow down to the time the ejecta slow down to non-relativi...

  4. Accessing the population of high redshift Gamma Ray Bursts

    E-Print Network [OSTI]

    Ghirlanda, G; Ghisellini, G; Mereghetti, S; Tagliaferri, G; Campana, S; Osborne, J P; O'Brien, P; Tanvir, N; Willingale, R; Amati, L; Basa, S; Bernardini, M G; Burlon, D; Covino, S; D'Avanzo, P; Frontera, F; Gotz, D; Melandri, A; Nava, L; Piro, L; Vergani, S D

    2015-01-01T23:59:59.000Z

    Gamma Ray Bursts (GRBs) are a powerful probe of the high redshift Universe. We present a tool to estimate the detection rate of high-z GRBs by a generic detector with defined energy band and sensitivity. We base this on a population model that reproduces the observed properties of GRBs detected by Swift, Fermi and CGRO in the hard X-ray and gamma-ray bands. We provide the expected cumulative distributions of the flux and fluence of simulated GRBs in different energy bands. We show that scintillator detectors, operating at relatively high energies (e.g. tens of keV to the MeV), can detect only the most luminous GRBs at high redshifts due to the link between the peak spectral energy and the luminosity (Ep-Liso) of GRBs. We show that the best strategy for catching the largest number of high-z bursts is to go softer (e.g. in the soft X-ray band) but with a very high sensitivity. For instance, an imaging soft X-ray detector operating in the 0.2-5 keV energy band reaching a sensitivity, corresponding to a fluence o...

  5. Uncovering the intrinsic variability of gamma-ray bursts

    SciTech Connect (OSTI)

    Golkhou, Vahid Z.; Butler, Nathaniel R., E-mail: vgolkhou@asu.edu, E-mail: natbutler@asu.edu [Cosmology Initiative, Arizona State University, Tempe, AZ 85287, USA. (United States)

    2014-05-20T23:59:59.000Z

    We develop a robust technique to determine the minimum variability timescale for gamma-ray burst (GRB) light curves, utilizing Haar wavelets. Our approach averages over the data for a given GRB, providing an aggregate measure of signal variation while also retaining sensitivity to narrow pulses within complicated time series. In contrast to previous studies using wavelets, which simply define the minimum timescale in reference to the measurement noise floor, our approach identifies the signature of temporally smooth features in the wavelet scaleogram and then additionally identifies a break in the scaleogram on longer timescales as a signature of a true, temporally unsmooth light curve feature or features. We apply our technique to the large sample of Swift GRB gamma-ray light curves and for the first time—due to the presence of a large number of GRBs with measured redshift—determine the distribution of minimum variability timescales in the source frame. We find a median minimum timescale for long-duration GRBs in the source frame of ?t {sub min} = 0.5 s, with the shortest timescale found being on the order of 10 ms. This short timescale suggests a compact central engine (3 × 10{sup 3} km). We discuss further implications for the GRB fireball model and present a tantalizing correlation between the minimum timescale and redshift, which may in part be due to cosmological time dilation.

  6. Gamma ray-induced embrittlement of pressure vessel alloys

    SciTech Connect (OSTI)

    Alexander, D.E.; Rehn, L.E. [Argonne National Lab., IL (United States); Farrell, K.; Stoller, R.E. [Oak Ridge National Lab., TN (United States)

    1994-11-01T23:59:59.000Z

    High-energy gamma rays emitted from the core of a nuclear reactor produce displacement damage in the reactor pressure vessel (RPV). The contribution of gamma damage to RPV embrittlement has in the past been largely ignored. However, in certain reactor designs the gamma flux at the RPV is sufficiently large that its contribution to displacement damage can be substantial. For example, gamma rays have been implicated in the accelerated RPV embrittlement observed in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. In the present study, mechanical property changes induced by 10-MeV electron irradiation of a model Fe alloy and an RPV alloy of interest to the HFIR were examined. Mini-tensile specimens were irradiated with high-energy electrons to reproduce damage characteristic of the Compton recoil-electrons induced by gamma bombardment. Substantial increases in yield and ultimate stress were observed in the alloys after irradiation to doses up to 5.3x10{sup {minus}3} dpa at temperatures ({approximately}50{degrees}C) characteristic of the HFIR pressure vessel. These measured increases were similar to those previously obtained following neutron irradiation, despite the highly disparate nature of the damage generated during electron and neutron irradiation.

  7. Simulated observations of gamma-ray bursts with GLAST

    SciTech Connect (OSTI)

    Bonnell, J. T.; Norris, J. P. [Code 661, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States); Dingus, B. L. [Department of Physics, University of Utah, Salt Lake City, Utah 84112 (United States); Scargle, J. D. [NASA Ames Research Center, MS 245-3, Moffett Field, California 94035 (United States)

    1998-05-16T23:59:59.000Z

    The Gamma-ray Large Area Space Telescope (GLAST) will incorporate high sensitivity, large field of view, and precision tracker technology, providing arc-minute localizations of gamma-ray bursts (GRBs) and exploring GRB physics up to {approx}100 GeV. We have simulated the response of GLAST to GRBs with power-law spectra extending to GeV energies to determine the detailed burst localization capability. The simulated properties of GRBs are based on the BATSE peak flux and duration distributions. GLAST's hodoscopic calorimeter design has sufficiently good angular resolution and discrimination power against cosmic rays that >1 GeV gammas which are only detected in the calorimeter may be utilized for bright sources such as GRBs. Our results indicate that GLAST will detect and image {approx}230 GRBs yr{sup -1} with sensitivity to {approx}100 GeV for {approx}20 bursts yr{sup -1}. Many bright burst localizations will be comparable in size to the current InterPlanetary Network error boxes thus probing the cosmological burst parameter space at nearby redshifts and enabling counterpart searches at all lower energies.

  8. Neutrino Emission from Gamma-Ray Burst Fireballs, Revised

    E-Print Network [OSTI]

    Svenja Hümmer; Philipp Baerwald; Walter Winter

    2012-05-02T23:59:59.000Z

    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 re-computation 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.

  9. GeV-TeV gamma-ray light curves expected in the IC electron-positron pair cascade model for massive binaries: Application to LS 5039

    E-Print Network [OSTI]

    W. Bednarek

    2006-11-09T23:59:59.000Z

    TeV gamma-ray emission from two massive binaries of the microquasar type, LS 5039 and LS I +61$^{\\rm o}$ 303, show clear variability with their orbital periods. Our purpose is to calculate the GeV and TeV $\\gamma$-ray light curves from the massive binary LS 5039 which are expected in the specific Inverse Compton $e^\\pm$ pair cascade model. This model successfully predicted the basic features of the high energy $\\gamma$-ray emission from LS 5039 and LS I +61 303. In the calculations we apply the Monte Carlo code which follows the IC $e^\\pm$ pair cascade in the anisotropic radiation of the massive star. The $\\gamma$-ray light curves and spectra are obtained for different parameters of the acceleration scenario and the inclination angles of the binary system. It is found that the GeV and TeV $\\gamma$-ray light curves should be anti-correlated. This feature can be tested in the near future by the simultaneous observations of LS 5039 with the AGILE and GLAST telescopes in GeV energies and the Cherenkov telescopes in the TeV energies. Considered model also predicts a broad maximum in the TeV $\\gamma$-ray light curve between the phases $\\sim 0.4-0.8$ consistently with the observations of LS 5039 by the HESS telescopes. Moreover, we predict additional dip in the TeV light curve for large inclination angles $\\sim 60^{\\rm o}$. This feature could serve as a diagnostic for independent measuring of the inclination angle of this binary system indicating also on the presence of a neutron star in LS 5039.

  10. The Status and future of ground-based TeV gamma-ray astronomy. A White Paper prepared for the Division of Astrophysics of the American Physical Society

    E-Print Network [OSTI]

    Buckley, J; Dingus, B; Falcone, A; Kaaret, Philip; Krawzcynski, H; Pohl, M; Vasilev, V; Williams, D A

    2008-01-01T23:59:59.000Z

    In recent years, ground-based TeV gamma-ray observatories have made spectacular discoveries including imaging spectroscopy observations of galactic sources of different classes, and the discovery of rapid gamma-ray flares from radio galaxies and active galactic nuclei containing supermassive black holes. These discoveries, and the fact that gamma-ray astronomy has the potential to map the radiation from dark matter annihilation in our Galaxy and in extragalactic systems, have attracted the attention of the wider scientific community. The Division of Astrophysics of the American Physical Society requested the preparation of a white paper on the status and future of ground-based gamma-ray astronomy to define the science goals of a future observatory, to determine the performance specifications, to identify the areas of necessary technology development, and to lay out a clear path for proceeding beyond the near term. The white paper was written with broad community input, including discussions on several dedicat...

  11. Klein-Nishina effects on the high-energy gamma-ray emission of gamma-ray bursts

    SciTech Connect (OSTI)

    Wang Xiangyu [Department of Astronomy, Nanjing University, Nanjing 210093 (China) and Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093 (China)

    2010-10-15T23:59:59.000Z

    Prompt and long-lived high-energy (>100 MeV) gamma-ray emission has been detected by Fermi Large Area Telescope (LAT) recently from more than ten gamma-ray bursts. It has been suggested that such emission is produced by synchrotron radiation of electrons accelerated in internal and external shocks. Here we show that, during both the prompt and early afterglow phase, inverse-Compton (IC) scattering of these electrons with synchrotron photons are typically in the Klein-Nishina (KN) regime. For the prompt emission, the KN effect may strongly suppress the IC component, which is consistent with one single spectral component seen in some strong bursts, such as in GRB080916C and GRB090217. The KN inverse-Compton cooling may also affect the low-energy electron number distribution and hence results in a low-energy synchrotron photon spectrum harder than the standard fast-cooling spectrum n({nu}){proportional_to}{nu}{sup -3/2}. During the early afterglow, KN effect leads to a low Compton-Y parameter, which is generally less than a few in the first tens of seconds for a wide range of parameter space. Furthermore, we suggest that the KN effect can explain the somewhat faster than expected decay of the early-time high-energy emission observed in some GRBs.

  12. Gamma Ray Burst Section of the White Paper on the Status and Future of Ground-based TeV Gamma-ray Astronomy

    E-Print Network [OSTI]

    Falcone, A D; Baring, M G; Blandford, R; Buckley, J; Connaughton, V; Coppi, P; Dermer, C; Dingus, B; Fryer, C; Gehrels, N; Granot, J; Horan, D; Katz, J I; Kühn, K; Mészáros, P; Norris, J; Parkinson, P Saz; Peér, A; Ramirez-Ruiz, E; Razzaque, S; Wang, X Y; Zhang, B

    2008-01-01T23:59:59.000Z

    This is a report on the findings of the gamma ray burst working group for the white paper on the status and future of TeV gamma-ray astronomy. The white paper is an APS commissioned document, and the overall version has also been released and can be found on astro-ph. This detailed section of the white paper discusses the status of past and current attempts to observe gamma ray bursts at GeV-TeV energies. We concentrate on the potential of future ground-based gamma-ray experiments to observe the highest energy emission ever recorded for GRBs, particularly for those that are nearby and have high Lorentz factors in the GRB jet. It is clear that major advances are possible and that the detection of very high energy emission would have strong implications for GRB models, as well as cosmic ray origin.

  13. Gamma Ray Burst Section of the White Paper on the Status and Future of Ground-based TeV Gamma-ray Astronomy

    E-Print Network [OSTI]

    A. D. Falcone; D. A. Williams; M. G. Baring; R. Blandford; J. Buckley; V. Connaughton; P. Coppi; C. Dermer; B. Dingus; C. Fryer; N. Gehrels; J. Granot; D. Horan; J. I. Katz; K. Kuehn; P. Meszaros; J. Norris; P. Saz Parkinson; A. Pe'er; E. Ramirez-Ruiz; S. Razzaque; X. Y. Wang; B. Zhang

    2008-10-02T23:59:59.000Z

    This is a report on the findings of the gamma ray burst working group for the white paper on the status and future of TeV gamma-ray astronomy. The white paper is an APS commissioned document, and the overall version has also been released and can be found on astro-ph. This detailed section of the white paper discusses the status of past and current attempts to observe gamma ray bursts at GeV-TeV energies. We concentrate on the potential of future ground-based gamma-ray experiments to observe the highest energy emission ever recorded for GRBs, particularly for those that are nearby and have high Lorentz factors in the GRB jet. It is clear that major advances are possible and that the detection of very high energy emission would have strong implications for GRB models, as well as cosmic ray origin.

  14. Analysis of historical gross gamma logging data from TY tank farm

    SciTech Connect (OSTI)

    MYERS, D.A.

    1999-10-19T23:59:59.000Z

    Gross gamma ray logs, recorded from January 1975 through mid-year 1994 as part of the Single-Shell Tank Farm Dry Well Surveillance Program, have been reanalyzed for the TY tank farm to locate the presence of mobile radionuclides in the subsurface. This report presents the TY tank farm gross gamma ray data in such a way as to assist others in their study of vadose zone mechanism.

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

    SciTech Connect (OSTI)

    Heath, R.L.

    1997-05-01T23:59:59.000Z

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

  16. Neutrinos from gamma-ray bursts as a tool to explore quantum-gravity-induced

    E-Print Network [OSTI]

    Loss, Daniel

    LETTERS Neutrinos from gamma-ray bursts as a tool to explore quantum-gravity-induced Lorentz energy scale. According to existing models, gamma-ray bursts (GRBs) are accompanied by very high from the same direction as a GRB, months after the burst, would be statistically significant and imply

  17. Short gamma-ray bursts from binary neutron star mergers in globular clusters

    E-Print Network [OSTI]

    Loss, Daniel

    ARTICLES Short gamma-ray bursts from binary neutron star mergers in globular clusters JONATHAN@cfa.harvard.edu Published online: 29 January 2006; doi:10.1038/nphys214 Observations by the Swift gamma-ray-burst (GRB, the so-called `long' GRBs (>2-200 s) were located by coded aperture imaging of their hard X-ray emission

  18. HETE, the High Energy Transient Explorer : unlocking the mysteries of gamma ray bursts

    E-Print Network [OSTI]

    Monnelly, Glen Pickslay, 1973-

    2002-01-01T23:59:59.000Z

    The High Energy Transient Explorer (HETE), was built primarily at MIT and launched in October 2000 with the goal of studying Gamma Ray Bursts (GRBs) at X-ray and gamma-ray energies. A suite of instruments aboard HETE provide ...

  19. Specific gamma-ray dose constants for nuclides important to dosimetry and radiological assessment

    SciTech Connect (OSTI)

    Unger, L.M.; Trubey, D.K.

    1981-09-01T23:59:59.000Z

    Tables of specific gamma-ray dose constants (the unshielded gamma-ray dose equivalent rate at 1 m from a point source) have been computed for approximately 500 nuclides important to dosimetry and radiological assessment. The half life, the mean attenuation coefficient, and thickness for a lead shield providing 95% dose equivalent attenuation are also listed.

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

    SciTech Connect (OSTI)

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

    2012-04-11T23:59:59.000Z

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

  1. accretion disk gamma-ray: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    accretion disk gamma-ray First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Nucleosynthesis in Gamma Ray...

  2. advanced gamma-ray detection: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    gamma-ray detection First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 117Fermi Detects Gamma-Rays from...

  3. agata gamma-ray tracking: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    agata gamma-ray tracking First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 AGATA: Gamma-ray tracking in...

  4. atmospheric gamma-ray flashes: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    atmospheric gamma-ray flashes First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Gamma ray flashes by...

  5. aist laser-compton gamma-ray: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    aist laser-compton gamma-ray First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 High Energy Gamma Rays...

  6. advanced gamma-ray imaging: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    advanced gamma-ray imaging First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 GRI: the gamma-ray imager...

  7. amazing gamma-ray activity: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    amazing gamma-ray activity First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Terrestrial gamma ray flash...

  8. Specific gamma-ray dose constants for nuclides important to dosimetry and radiological assessment

    SciTech Connect (OSTI)

    Unger, L.M.; Trubey, D.K.

    1982-05-01T23:59:59.000Z

    Tables of specific gamma-ray dose constants (the unshielded gamma-ray dose equivalent rate at 1 m from a point source) have been computed for approximately 500 nuclides important to dosimetry and radiological assessment. The half life, the mean attenuation coefficient, and thickness for a lead shield providing 95% dose equivalent attenuation are also listed.

  9. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE BeppoSAX GAMMA-RAY BURST CATALOGS

    E-Print Network [OSTI]

    Vanderspek, Roland K.

    Between 1996 July and 2002 April, one or more spacecraft of the interplanetary network detected 786 cosmic gamma-ray bursts that were also detected by the Gamma-Ray Burst Monitor and/or Wide-Field X-Ray Camera experiments ...

  10. absorption gamma-ray spectroscopy: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    absorption gamma-ray spectroscopy First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 gamma-Ray...

  11. Unveiling the nature of the unidentified gamma-ray sources VI: gamma-ray blazar candidates in the WISH survey and their radio properties

    E-Print Network [OSTI]

    Nori, M; Massaro, F; D'Abrusco, R; Paggi, A; Tosti, G; Funk, S

    2015-01-01T23:59:59.000Z

    According to the second Fermi LAT Catalog (2FGL), about one third of the gamma-ray sources listed have no assigned counterparts at lower energies. Many statistical methods have been developed to find proper counterparts for these sources. We explore the sky area covered at low radio frequency by Westerbork in the Southern Hemisphere (WISH) survey to search for blazar-like associations among the unidentified gamma-ray sources listed in the 2FGL (UGSs). Searching the WISH and NRAO VLA Sky Survey (NVSS) radio surveys within the positional uncertainty regions of the 2FGL UGSs, we select as gamma-ray blazar candidates the radio sources characterized by flat radio spectra between 352 MHz and 1400 MHz. We propose new gamma-ray blazar associations for eight UGSs and we also discuss their spectral properties at low radio frequencies. We compare the radio flux density distribution of the low radio frequency gamma-ray blazar candidates with that of gamma-ray blazars associated with other methods. We find significant dif...

  12. REVISITING THE LIGHT CURVES OF GAMMA-RAY BURSTS IN THE RELATIVISTIC TURBULENCE MODEL

    SciTech Connect (OSTI)

    Lin, Da-Bin; Gu, Wei-Min; Hou, Shu-Jin; Liu, Tong; Sun, Mou-Yuan; Lu, Ju-Fu, E-mail: dabinlin@xmu.edu.cn, E-mail: lujf@xmu.edu.cn [Department of Astronomy and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005 (China)

    2013-10-10T23:59:59.000Z

    Rapid temporal variability has been widely observed in the light curves of gamma-ray bursts (GRBs). One possible mechanism for such variability is related to the relativistic eddies in the jet. In this paper, we include the contribution of the inter-eddy medium together with the eddies to the gamma-ray emission. We show that the gamma-ray emission can either lead or lag behind the observed synchrotron emission, where the latter originates in the inter-eddy medium and provides most of the seed photons for producing gamma-ray emission through inverse Compton scattering. As a consequence, we argue that the lead/lag found in non-stationary short-lived light curves may not reveal the intrinsic lead/lag of different emission components. In addition, our results may explain the lead of gamma-ray emission with respect to optical emission observed in GRB 080319B.

  13. Ion-induced gamma-ray detection of fast ions escaping from fusion plasmas

    SciTech Connect (OSTI)

    Nishiura, M., E-mail: nishiura@ppl.k.u-tokyo.ac.jp; Mushiake, T. [Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8561 (Japan); Doi, K.; Wada, M. [Graduate School of Science and Engineering, Doshisha University, Kyotanabe 610-0321 (Japan); Taniike, A.; Matsuki, T. [Graduate School of Maritime Sciences, Kobe University, Kobe 658-0022 (Japan); Shimazoe, K. [Graduate School of Engineering, The University of Tokyo, Tokyo 113-8654 (Japan); Yoshino, M. [Furukawa Co. Ltd., Tsukuba, Ibaraki 305-0856 (Japan); Nagasaka, T.; Tanaka, T.; Kisaki, M. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Fujimoto, Y.; Fujioka, K. [Institute of Laser Engineering, Osaka University, Osaka 565-0871 (Japan); Yamaoka, H. [RIKEN SPring-8 center, RIKEN, Sayo, Hyogo 679-5148 (Japan); Matsumoto, Y. [Tokushima Bunri University, Tokushima 770-8514 (Japan)

    2014-11-15T23:59:59.000Z

    A 12 × 12 pixel detector has been developed and used in a laboratory experiment for lost fast-ion diagnostics. With gamma rays in the MeV range originating from nuclear reactions {sup 9}Be(?, n?){sup 12}C, {sup 9}Be(d, n?){sup 12}C, and {sup 12}C(d, p?){sup 13}C, a high purity germanium (HPGe) detector measured a fine-energy-resolved spectrum of gamma rays. The HPGe detector enables the survey of background-gamma rays and Doppler-shifted photo peak shapes. In the experiments, the pixel detector produces a gamma-ray image reconstructed from the energy spectrum obtained from total photon counts of irradiation passing through the detector's lead collimator. From gamma-ray image, diagnostics are able to produce an analysis of the fast ion loss onto the first wall in principle.

  14. Very High Energy Gamma-Ray Observations of the Galactic Centre Region

    E-Print Network [OSTI]

    Christopher van Eldik

    2008-11-06T23:59:59.000Z

    Recent progress in pushing the sensitivity of the Imaging Atmospheric Cherenkov Technique into the 10 mCrab regime has enabled first sensitive observations of the innermost few 100 pc of the Milky Way in Very High Energy (VHE; >100 GeV) gamma rays. These observations are a valuable tool to understand the acceleration and propagation of energetic particles near the Galactic Centre. Remarkably, besides two compact gamma-ray sources, faint diffuse gamma-ray emission has been discovered with high significance. The current VHE gamma-ray view of the Galactic Centre region is reviewed, and possible counterparts of the gamma-ray sources and the origin of the diffuse emission are discussed. The future prospects for VHE Galactic Centre observations are discussed based on order-of-magnitude estimates for a CTA type array of telescopes.

  15. Shallow Decay of Early X-ray Afterglows from Inhomogeneous Gamma-Ray Burst Jets

    E-Print Network [OSTI]

    Toma, K; Yamazaki, R; Nakamura, T; Toma, Kenji; Ioka, Kunihito; Yamazaki, Ryo; Nakamura, Takashi

    2006-01-01T23:59:59.000Z

    Almost all the X-ray afterglows of gamma-ray bursts (GRBs) observed by the Swift satellite have a shallow decay phase in the first thousands of seconds. We show that in an inhomogeneous jet (multiple-subjet or patchy-shell) model the superposition of the afterglows of off-axis subjets (patchy shells) can have the shallow decay phase. The necessary condition for obtaining the shallow decay phase is that gamma-ray bright subjets (patchy shells) should have gamma-ray efficiency higher than previously estimated, and should be surrounded by gamma-ray dim subjets (patchy shells) with low gamma-ray efficiency. Our model predicts that events with dim prompt emission have the conventional afterglow light curve without the shallow decay phase like GRB 050416A.

  16. Precision linac and laser technologies for nuclear photonics gamma-ray sources

    SciTech Connect (OSTI)

    Albert, F.; Hartemann, F. V.; Anderson, S. G.; Cross, R. R.; Gibson, D. J.; Hall, J.; Marsh, R. A.; Messerly, M.; Wu, S. S.; Siders, C. W.; Barty, C. P. J. [Lawrence Livermore National Laboratory, NIF and Photon Science, 7000 East Avenue, Livermore, California 94550 (United States)

    2012-05-15T23:59:59.000Z

    Tunable, high precision gamma-ray sources are under development to enable nuclear photonics, an emerging field of research. This paper focuses on the technological and theoretical challenges related to precision Compton scattering gamma-ray sources. In this scheme, incident laser photons are scattered and Doppler upshifted by a high brightness electron beam to generate tunable and highly collimated gamma-ray pulses. The electron and laser beam parameters can be optimized to achieve the spectral brightness and narrow bandwidth required by nuclear photonics applications. A description of the design of the next generation precision gamma-ray source currently under construction at Lawrence Livermore National Laboratory is presented, along with the underlying motivations. Within this context, high-gradient X-band technology, used in conjunction with fiber-based photocathode drive laser and diode pumped solid-state interaction laser technologies, will be shown to offer optimal performance for high gamma-ray spectral flux, narrow bandwidth applications.

  17. Are long gamma-ray bursts standard candles?

    E-Print Network [OSTI]

    Lin, Hai-Nan; Wang, Sai; Chang, Zhe

    2015-01-01T23:59:59.000Z

    Gamma-ray bursts (GRBs) are widely proposed as an effective probe to trace the Hubble diagram of the Universe in high redshift range. However, the calibration of GRBs is not as easy as that of type-Ia supernovae (SNe Ia). Most calibrating methods at present take use one or some of the empirical luminosity corrections, e.g., Amati relation. One of the underlying assumptions of these calibrating methods is that the empirical correlation is universal over all redshifts. In this paper, we check to what extent this assumption holds. Assuming that SNe Ia exactly trace the Hubble diagram of the Universe, we re-investigate the Amati relation for low redshift ($z1.4$) GRBs, respectively. It is found that the Amati relation of low-$z$ GRBs differs from that of high-$z$ GRBs at more than $3\\sigma$ confidence level. This result is insensitive to cosmological models.

  18. Study of Lorentz violation in INTEGRAL Gamma-Ray Bursts

    E-Print Network [OSTI]

    Raphael Lamon; Nicolas Produit; Frank Steiner

    2007-09-27T23:59:59.000Z

    We search for possible time lags caused by quantum gravitational (QG) effects using gamma-ray bursts (GRBs) detected by INTEGRAL. The advantage of this satellite is that we have at our disposal the energy and arrival time of every detected single photon, which enhances the precision of the time resolution. We present a new method for seeking time lags in unbinned data using a maximum likelihood method and support our conclusions with Monte Carlo simulations. The analysis of the data yields a mass scale well below the Planck mass whose value may however increase if better statistics of GRBs were available. Furthermore, we disagree with previous studies in which a non-monotonic function of the redshift was used to perform a linear fit.

  19. Physics of Gamma-Ray Bursts Prompt Emission

    E-Print Network [OSTI]

    Pe'er, Asaf

    2015-01-01T23:59:59.000Z

    In recent years, our understanding of gamma-ray bursts (GRB) prompt emission has been revolutionized, due to a combination of new instruments, new analysis methods and novel ideas. In this review, I describe the most recent observational results and the current theoretical interpretation. Observationally, a major development is the rise of time-resolved spectral analysis. These led to (I) identification of a distinguished high energy component, with GeV photons often seen at a delay; and (II) firm evidence for the existence of a photospheric (thermal) component in a large number of bursts. These results triggered many theoretical efforts aimed at understanding the physical conditions in the inner jet regions from which the prompt photons are emitted, as well as the spectral diversity observed. I highlight some areas of active theoretical research. These include: (I) understanding the role played by magnetic fields in shaping the dynamics of GRB outflow and spectra; (II) understanding the microphysics of kinet...

  20. Nucleosynthesis of heavy elements in gamma ray bursts

    E-Print Network [OSTI]

    ,

    2015-01-01T23:59:59.000Z

    The ultrarelativistic jets responsible for prompt and afterglow emission in gamma ray bursts are presumably driven by a central engine that consists of a dense accretion disk around a spinning black hole. We consider such engine, composed of free nucleons, electron-positron pairs, Helium nuclei, and cooled by neutrino emission. A significant number density of neutrons in the disk provide conditions for neutron rich plasma in the outflows and jets. Heavy nuclei are also formed in the accretion flow, at the distances 150-250 gravitational radii from the black hole. We study the process of nucleosynthesis in the GRB engine, depending on its physical properties. Our results may have important observational implications for the jet deceleration process and heavy elements observed in the spectra of GRB afterglows.

  1. General Relativistic Binary Merger Simulations and Short Gamma Ray Bursts

    E-Print Network [OSTI]

    Joshua A. Faber; Thomas W. Baumgarte; Stuart L. Shapiro; Keisuke Taniguchi

    2006-03-10T23:59:59.000Z

    The recent localization of some short-hard gamma ray bursts (GRBs) in galaxies with low star formation rates has lent support to the suggestion that these events result from compact object binary mergers. We discuss how new simulations in general relativity are helping to identify the central engine of short-hard GRBs. Motivated by our latest relativistic black hole-neutron star merger calculations, we discuss a scenario in which these events may trigger short-hard GRBs, and compare this model to competing relativistic models involving binary neutron star mergers and the delayed collapse of hypermassive neutron stars. Distinguishing features of these models may help guide future GRB and gravitational wave observations to identify the nature of the sources.

  2. Calorimetry of gamma-ray bursts: echos in gravitational waves

    E-Print Network [OSTI]

    Maurice H. P. M. van Putten; Amir Levinson

    2001-05-24T23:59:59.000Z

    Black holes surrounded by a disk or torus may drive the enigmatic cosmological gamma-ray bursts (GRBs). Equivalence in poloidal topology to pulsar magnetospheres shows a high incidence of the black hole-luminosity $L_H$ into the surrounding magnetized matter. We argue that this emission is re-radiated into gravitational waves at $L_{GW}\\simeq L_H/3$ in frequencies of order 1kHz, winds and, potentially, MeV neutrinos. The total energy budget and input to the GRB from baryon poor jets are expected to be standard in this scenario, consistent with recent analysis of afterglow data. Collimation of these outflows by baryon rich disk or torus winds may account for the observed spread in opening angles up to about $35^o$. This model may be tested by future LIGO/VIRGO observations.

  3. Gamma-Ray Bursts - a Primer For Relativists

    E-Print Network [OSTI]

    Tsvi Piran

    2002-05-12T23:59:59.000Z

    Gamma-Ray Bursts (GRBs) - short bursts of 100-1MeV photons arriving from random directions in the sky are probably the most relativistic objects discovered so far. Still, somehow they did not attract the attention of the relativistic community. In this short review I discuss briefly GRB observations and show that they lead us to the fireball model - GRBs involve macroscopic relativistic motion with Lorentz factors of a few hundred or more. I show that GRB sources involve, most likely, new born black holes, and their progenitors are Supernovae or neutron star mergers. I show that both GRB progenitors and the process of GRB itself produce gravitational radiation and I consider the possibility of detecting this emission. Finally I show that GRBs could serve as cosmological indicators that could teach us about the high redshift ($z \\approx 5-15$) dark ages of the universe.

  4. Polarized Gravitational Waves from Gamma-Ray Bursts

    E-Print Network [OSTI]

    Shiho Kobayashi; Peter Meszaros

    2003-01-24T23:59:59.000Z

    Significant gravitational wave emission is expected from gamma-ray bursts arising from compact stellar mergers, and possibly also from bursts associated with fast-rotating massive stellar core collapses. These models have in common a high angular rotation rate, and observations provide evidence for jet collimation of the photon emission, with properties depending on the polar angle, which may also be of relevance for X-ray flashes. Here we consider the gravitational wave emission and its polarization as a function of angle which is expected from such sources. We discuss possible correlations between the burst photon luminosity, or the delay between gravitational wave bursts and X-ray flashes, and the polarization degree of the gravitational waves.

  5. Gravitational Wave Memory of Gamma-Ray Burst Jets

    E-Print Network [OSTI]

    Norichika Sago; Kunihito Ioka; Takashi Nakamura; Ryo Yamazaki

    2004-11-16T23:59:59.000Z

    Gamma-Ray Bursts (GRBs) are now considered as relativistic jets. We analyze the gravitational waves from the acceleration stage of the GRB jets. We show that (i) the point mass approximation is not appropriate if the opening half-angle of the jet is larger than the inverse of the Lorentz factor of the jet, (ii) the gravitational waveform has many step function like jumps, and (iii) the practical DECIGO and BBO may detect such an event if the GRBs occur in Local group of galaxy. We found that the light curve of GRBs and the gravitational waveform are anti-correlated so that the detection of the gravitational wave is indispensable to determine the structure of GRB jets.

  6. Properties of Low Luminosity Afterglow Gamma-ray Bursts

    E-Print Network [OSTI]

    Dereli, H; Gendre, B; Amati, L; Dichiara, S

    2015-01-01T23:59:59.000Z

    Aims: We characterize a sample of Gamma-Ray Bursts with low luminosity X-ray afterglows (LLA GRBs), and study their properties. Method: We select a sample consisting of the 12\\% faintest X-ray afterglows from the total population of long GRBs (lGRBs) with known redshift. We study their intrinsic properties (spectral index, decay index, distance, luminosity, isotropic radiated energy and peak energy) to assess whether they belong to the same population than the brighter afterglow events. Results: We present strong evidences that these events belong to a population of nearby events, different from that of the general population of lGRBs. These events are faint during their prompt phase, and include the few possible outliers of the Amati relation. Out of 14 GRB-SN associations, 9 are in LLA GRB sample, prompting for caution when using SN templates in observational and theoretical models for the general lGRBs population.

  7. Particle Acceleration in Gamma-Ray Burst Jets

    E-Print Network [OSTI]

    Frank M. Rieger; Peter Duffy

    2005-11-02T23:59:59.000Z

    Gradual shear acceleration of energetic particles in gamma-ray burst (GRB) jets is considered. Special emphasis is given to the analysis of universal structured jets, and characteristic acceleration timescales are determined for a power-law and a Gaussian evolution of the bulk flow Lorentz factor $\\gamma_b$ with angle $\\phi$ from the jet axis. The results suggest that local power-law particle distributions may be generated and that higher energy particles are generally concentrated closer to the jet axis. Taking several constraints into account we show that efficient electron acceleration in gradual shear flows, with maximum particle energy successively decreasing with time, may be possible on scales larger than $r \\sim 10^{15}$ cm, provided the jet magnetic field becomes sufficiently weak and/or decreases rapidly enough with distance, while efficient acceleration of protons to ultra-high energies $> 10^{20}$ eV may be possible under a wide range of conditions.

  8. Radiative Transfer Models for Gamma-Ray Bursts

    E-Print Network [OSTI]

    Vurm, Indrek

    2015-01-01T23:59:59.000Z

    We present global radiative transfer models for heated relativistic jets. The simulations include all relevant radiative processes, starting deep in the opaque zone and following the evolution of radiation to and beyond the photosphere of the jet. The transfer models are compared with three gamma-ray bursts GRB 990123, GRB 090902B, and GRB 130427A, which have well-measured and different spectra. The models provide good fits to the observed spectra in all three cases. The fits give estimates for the jet magnetization parameter $\\varepsilon_{\\rm B}$ and the Lorentz factor $\\Gamma$. In the small sample of three bursts, $\\varepsilon_{\\rm B}$ varies between 0.01 and 0.1, and $\\Gamma$ varies between 340 and 1200.

  9. Evidence For and Against Collimation of Gamma Ray Bursts

    E-Print Network [OSTI]

    James E. Rhoads

    2001-03-02T23:59:59.000Z

    The degree to which gamma ray bursts are collimated is now the dominant uncertainty in their energy requirements and event rates. In this review I begin with the reasons for studying GRB collimation, then discuss existing tests for collimation and their applications to date, and finally outline some possible future tests. The most important conclusions are that (1) mean collimation angles much tighter than 1 degree appear ruled out; (2) the collimation angle appears to vary from burst to burst (like most other GRB properties). Some alternative explanations of apparent collimation signatures remain, but it should be possible to distinguish them from true collimation with future data sets and may be possible already. New satellites, improved followup observations, and new tests for collimation all promise continued rapid progress in coming years.

  10. Variable VHE gamma-ray emission from non-blazar AGNs

    E-Print Network [OSTI]

    F. M. Rieger; F. A. Aharonian

    2008-05-27T23:59:59.000Z

    The observation of rapidly variable very high energy (VHE) gamma-rays from non-aligned active galactic nuclei (AGNs), as reported from M87, proves challenging for conventional theoretical acceleration and emission models. We re-examine the centrifugal acceleration of particles by rotating jet magnetospheres in the vicinity of accreting supermassive black hole systems and analyze the energy constraints imposed for highly underluminous systems. Applications are presented for conditions expected to be present in the radio galaxy M87, assuming accretion onto the central black hole to occur in an advection-dominated (ADAF) mode. We show that for a highly underluminous source like M87, centrifugally accelerated electrons may reach Lorentz factors up to $\\gamma \\sim (10^7-10^8)$, allowing inverse Compton (Thomson) upscattering of sub-mm disk photons to the TeV regime. Upscattering of Comptonized disk photons results in a flat TeV spectrum $L_{\

  11. STATISTICAL PROPERTIES OF GAMMA-RAY BURST POLARIZATION

    SciTech Connect (OSTI)

    Toma, Kenji [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Sakamoto, Takanori; Hill, Joanne E. [CRESST and NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Zhang, Bing [Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, NV 89154 (United States); McConnell, Mark L.; Bloser, Peter F. [Space Science Center, University of New Hampshire, Durham, NH 03824 (United States); Yamazaki, Ryo [Department of Physical Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Ioka, Kunihito [Theory Division, KEK (High Energy Accelerator Research Organization), 1-1 Oho, Tsukuba 305-0801 (Japan); Nakamura, Takashi [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)], E-mail: toma@astro.psu.edu

    2009-06-20T23:59:59.000Z

    The emission mechanism and the origin and structure of magnetic fields in gamma-ray burst (GRB) jets are among the most important open questions concerning the nature of the central engine of GRBs. In spite of extensive observational efforts, these questions remain to be answered and are difficult or even impossible to infer with the spectral and light-curve information currently collected. Polarization measurements will lead to unambiguous answers to several of these questions. Recent developments in X-ray and {gamma}-ray polarimetry techniques have demonstrated a significant increase in sensitivity, enabling several new mission concepts, e.g., Polarimeters for Energetic Transients (POET), providing wide field of view and broadband polarimetry measurements. If launched, missions of this kind would finally provide definitive measurements of GRB polarizations. We perform Monte Carlo simulations to derive the distribution of GRB polarizations in three emission models; the synchrotron model with a globally ordered magnetic field (SO model), the synchrotron model with a small-scale random magnetic field (SR model), and the Compton drag model (CD model). The results show that POET, or other polarimeters with similar capabilities, can constrain the GRB emission models by using the statistical properties of GRB polarizations. In particular, the ratio of the number of GRBs for which the polarization degrees can be measured to the number of GRBs that are detected (N{sub m} /N{sub d} ) and the distributions of the polarization degrees ({pi}) can be used as the criteria. If N{sub m} /N{sub d} > 30% and {pi} is clustered between 0.2 and 0.7, the SO model will be favored. If, instead, N{sub m} /N{sub d} < 15%, then the SR or CD model will be favored. If several events with {pi}>0.8 are observed, then the CD model will be favored.

  12. Propagation of Neutrinos through Magnetized Gamma-Ray Burst Fireball

    E-Print Network [OSTI]

    Sarira Sahu; Nissim Fraija; Yong-Yeon Keum

    2009-11-10T23:59:59.000Z

    The neutrino self-energy is calculated in a weakly magnetized plasma consists of electrons, protons, neutrons and their anti-particles and using this we have calculated the neutrino effective potential up to order $M^{-4}_W$. In the absence of magnetic field it reduces to the known result. We have also calculated explicitly the effective potentials for different backgrounds which may be helpful in different environments. By considering the mixing of three active neutrinos in the medium with the magnetic field we have derived the survival and conversion probabilities of neutrinos from one flavor to another and also the resonance condition is derived. As an application of the above, we considered the dense and relativistic plasma of the Gamma-Ray Bursts fireball through which neutrinos of 5-30 MeV can propagate and depending on the fireball parameters they may oscillate resonantly or non-resonantly from one flavor to another. These MeV neutrinos are produced due to stellar collapse or merger events which trigger the Gamma-Ray Burst. The fireball itself also produces MeV neutrinos due to electron positron annihilation, inverse beta decay and nucleonic bremsstrahlung. Using the three neutrino mixing and considering the best fit values of the neutrino parameters, we found that electron neutrinos are hard to oscillate to another flavors. On the other hand, the muon neutrinos and the tau neutrinos oscillate with equal probability to one another, which depends on the neutrino energy, temperature and size of the fireball. Comparison of oscillation probabilities with and without magnetic field shows that, they depend on the neutrino energy and also on the size of the fireball. By using the resonance condition, we have also estimated the resonance length of the propagating neutrinos as well as the baryon content of the fireball.

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

    SciTech Connect (OSTI)

    Bosko, A.; Venkataraman, R.; Bronson, F.L.; Ilie, G.; Russ, W.R. [Canberra Industries, 800 Research Parkway, Meriden, CT 06450 (United States)] [Canberra Industries, 800 Research Parkway, Meriden, CT 06450 (United States)

    2013-07-01T23:59:59.000Z

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

  14. THE EFFECT OF RADON TRANSPORT IN GROUNDWATER UPON GAMMA-RAY BOREHOLE LOGS

    E-Print Network [OSTI]

    Nelson, P.H.

    2010-01-01T23:59:59.000Z

    Techniques for Uranium and Exploration and Evaluation," i nMethods i n Uranium Exploration —Application and I n t e r pray spectrometry f o r uranium exploration has advanced

  15. THE EFFECT OF RADON TRANSPORT IN GROUNDWATER UPON GAMMA-RAY BOREHOLE LOGS

    E-Print Network [OSTI]

    Nelson, P.H.

    2010-01-01T23:59:59.000Z

    Storage of Nuclear Waste in Granite by P.A. Witherspoon, P.of Discontinuities in the Stripa Granite —Time-Scale HeaterPermeability Test of the Granite in the Stripa Mine and

  16. Temperatures and Natural Gamma-Ray Logs Obtained in 1986 from Shady Rest

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to:Ezfeedflag JumpID-f <Maintained ByManagement IncDrill Hole RD08, Mammoth Lakes, Mono

  17. Development of a gamma-ray detector with iridium transition edge sensor coupled to a Pb absorber

    E-Print Network [OSTI]

    Leman, Steven W.

    We have recently started to develop a high-resolution gamma-ray spectrometer for material defect analysis. Our gamma-ray detector is a microcalorimeter consisting of an iridium/gold bilayer transition edge sensor (TES) ...

  18. Reconstruction of Distribution Functions of Fast Ions and Runaway Electrons in ITER Plasmas Using Gamma-Ray Spectrometry

    E-Print Network [OSTI]

    Reconstruction of Distribution Functions of Fast Ions and Runaway Electrons in ITER Plasmas Using Gamma-Ray Spectrometry

  19. Direct measurement of the $^{18}F(p,\\alpha)^{15}O$ reaction for application to nova gamma-ray emission

    E-Print Network [OSTI]

    De Séréville, N; Leleux, P; Coc, A; Kiener, J; Lefebvre-Schuhl, A; Tatischeff, V; Descouvemont, P; Figuera, P; Hammache, F; Achouri, L; Orr, N; Stefan, I; Casarejos, E; Davinson, T; Robertson, D; Laird, A M; Fox, S P; Mumby-Croft, P; Vaughan, K

    2006-01-01T23:59:59.000Z

    Direct measurement of the $^{18}F(p,\\alpha)^{15}O$ reaction for application to nova gamma-ray emission

  20. Results of 1999 Spectral Gamma-Ray and Neutron Moisture Monitoring of Boreholes at Specific Retention Facilities in the 200 East Area, Hanford Site

    SciTech Connect (OSTI)

    DG Horton; RR Randall

    2000-01-18T23:59:59.000Z

    Twenty-eight wells and boreholes in the 200 East Are% Hanford Site, Washington were monitored in 1999. The monitored facilities were past-practice liquid waste disposal facilities and consisted of six cribs and nineteen ''specific retention'' cribs and trenches. Monitoring consisted of spectral gamma-ray and neutron moisture logging. All data are included in Appendix B. The isotopes {sup 137}Cs, {sup 60}Co, {sup 235}U, {sup 238}U, and {sup 154}Eu were identified on spectral gamma logs from boreholes monitoring the PUREX specific retention facilities; the isotopes {sup 137}Cs, {sup 60}Co, {sup 125}Sb, and {sup 154}Eu were identified on the logs from boreholes at the BC Controlled Area cribs and trenches; and {sup 137}Cs, {sup 60}Co, and {sup 125}Sb were, identified on the logs from boreholes at the BX specific retention trenches. Three boreholes in the BC Controlled Area and one at the BX trenches had previous spectral gamma logs available for comparison with 1999 logs. Two of those logs showed that changes in the subsurface distribution of {sup 137}CS and/or {sup 60}Co had occurred since 1992. Although the changes are not great, they do point to continued movement of contaminants in the vadose zone. The logs obtained in 1999 create a larger baseline for comparison with future logs. Numerous historical gross gamma logs exist from most of the boreholes logged. Qualitative comparison of those logs with the 1999 logs show many substantial changes, most of which reflect the decay of deeper short-lived isotopes, such as {sup 106}Ru and {sup 125}Sb, and the much slower decay of shallower and longer-lived isotopes such as {sup 137}Cs. The radionuclides {sup 137}Cs and {sup 60}Co have moved in two boreholes since 1992. Given the amount of movement and the half-lives of the isotopes, it is expected that they will decay to insignificant amounts before reaching groundwater. However, gamma ray logging cannot detect many of the contaminants of interest such as {sup 99}Tc, NO{sub 3}, or {sup 129}I, all of which can be highly mobile in the vadose zone and, for the radionuclides, have long half-lives.

  1. Using Gamma-Ray Burst Prompt Emission to Probe Relativistic Shock Acceleration

    E-Print Network [OSTI]

    Baring, Matthew G

    2010-01-01T23:59:59.000Z

    It is widely accepted that the prompt transient signal in the 10 keV - 10 GeV band from gamma-ray bursts (GRBs) arises from multiple shocks internal to the ultra-relativistic expansion. The detailed understanding of the dissipation and accompanying acceleration at these shocks is a currently topical subject. This paper explores the relationship between GRB prompt emission spectra and the electron (or ion) acceleration properties at the relativistic shocks that pertain to GRB models. The focus is on the array of possible high-energy power-law indices in accelerated populations, highlighting how spectra above 1 MeV can probe the field obliquity in GRB internal shocks, and the character of hydromagnetic turbulence in their environs. It is emphasized that diffusive shock acceleration theory generates no canonical spectrum at relativistic MHD discontinuities. This diversity is commensurate with the significant range of spectral indices discerned in prompt burst emission. Such system diagnostics are now being enhan...

  2. The Performance of the Gamma-Ray Energy Tracking In-Beam Nuclear Array GRETINA

    SciTech Connect (OSTI)

    Paschalis, S. [Lawrence Berkeley National Laboratory (LBNL); Lee, I. Y. [Lawrence Berkeley National Laboratory (LBNL); Macchiavelli, A. O. [Lawrence Berkeley National Laboratory (LBNL); Campbell, C. M. [Lawrence Berkeley National Laboratory, The Scripps Research Institite and The Skaggs Institute; Cromaz, M. [Lawrence Berkeley National Laboratory (LBNL); Gros, S. [Lawrence Berkeley National Laboratory (LBNL); Pavin, J. [Lawrence Berkeley National Laboratory (LBNL); Qian, J. [Lawrence Berkeley National Laboratory (LBNL); Clark, R. M. [Lawrence Berkeley National Laboratory (LBNL); Crawford, H. L. [Lawrence Berkeley National Laboratory (LBNL); Doering, D. [Lawrence Berkeley National Laboratory (LBNL); Fallon, P. [Lawrence Berkeley National Laboratory (LBNL); Lionberger, C. [Lawrence Berkeley National Laboratory (LBNL); Loew, T. [Lawrence Berkeley National Laboratory (LBNL); Petri, M. [Lawrence Berkeley National Laboratory (LBNL); Stezelberger, T. [Lawrence Berkeley National Laboratory (LBNL); Zimmerman, S. [Lawrence Berkeley National Laboratory (LBNL); Radford, David C [ORNL; Lagergren, Karin B [ORNL; Weisshaar, D. [Michigan State University, East Lansing; Winkler, R. [Michigan State University, East Lansing; Glasmacher, T. [Michigan State University, East Lansing; Anderson, J. T, [Argonne National Laboratory (ANL); Beausang, C. W. [University of Richmond

    2013-01-01T23:59:59.000Z

    The Gamma-Ray Energy Tracking In-beam Nuclear Array (GRETINA) is a new generation high-resolution -ray spectrometer consisting of electrically segmented high-purity germanium crystals. GRETINA is capable of reconstructing the energy and position of each -ray interaction point inside the crystal with high resolution. This enables -ray energy tracking which in turn provides an array with large photopeak efficiency, high resolution and good peak-to-total ratio. GRETINA is used for nuclear structure studies with demanding -ray detection requirements and it is suitable for experiments with radioactive-ion beams with high recoil velocities. The GRETINA array has a 1 solid angle coverage and constitutes the first stage towards the full 4 array GRETA. We present in this paper the main parts and the performance of the GRETINA system.

  3. Proceedings of ICRC 2001: 1 c Copernicus Gesellschaft 2001 Background Rejection in the Milagro Gamma Ray Observatory

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    in the Milagro Gamma Ray Observatory C. Sinnis for the Milagro Collaboration Los Alamos National Laboratory Abstract. Recent advances in TeV gamma ray astronomy are a result of the ability to differentiate between extensive air showers generated by gamma rays and hadronic cosmic rays. Air Cherenkov telescopes have

  4. OBSERVATION OF TeV GAMMA RAYS FROM THE CRAB NEBULA WITH MILAGRO USING A NEW BACKGROUND REJECTION TECHNIQUE

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    electromagnetic air showers in the Milagro gamma-ray observatory, based on the ability to detect the energetic the late 1980s that the first convincing detection of a source of TeV gamma rays was made with a ground by the Whipple experiment to detect TeV gamma-ray emission from the Crab Nebula (Weekes et al. 1989). Since

  5. Nuclear Instruments and Methods in Physics Research A 486 (2002) 623638 Simulation of the AGILE gamma-ray imaging detector

    E-Print Network [OSTI]

    2002-01-01T23:59:59.000Z

    gamma-ray imaging detector performance: Part II Veronica Coccoa,d, *, Francesco Longob,d , Marco Tavanic state physics instruments for cosmic gamma-ray detection in space will sub- stantially improve Detector (GRID) is devoted to optimal detection and imaging of cosmic gamma-rays. It is *Corresponding

  6. Nuclear Instruments and Methods in Physics Research A 486 (2002) 610622 Simulation of the AGILE gamma-ray imaging detector

    E-Print Network [OSTI]

    2002-01-01T23:59:59.000Z

    gamma-ray imaging detector performance: part I Francesco Longoa,d , Veronica Coccob,d, *, Marco Tavanic-photon background. The gamma-ray photon detection efficiency by the imaging GRID is simulated to be particularly of the Gamma-Ray Imaging Detector (GRID) being developed for the AGILE space astrophysics mission. The GRID

  7. Detection of Sub-TeV gamma-rays from the Galactic Center with the CANGAROO-II

    E-Print Network [OSTI]

    Enomoto, Ryoji

    Detection of Sub-TeV gamma-rays from the Galactic Center with the CANGAROO-II telescope Ken significant excess at energies greater than 250GeV. This is the first detection of sub-TeV gamma rays from than that predicted previously give IACTs a chance of detecting a gamma-ray #12;signal in the 100 Ge

  8. 30TH INTERNATIONAL COSMIC RAY CONFERENCE PoGOLite: a balloon-borne soft gamma-ray polarimeter

    E-Print Network [OSTI]

    Haviland, David

    University of Tokyo, Japan. pearce@particle.kth.se Abstract: Polarized gamma-rays are expected from a wide30TH INTERNATIONAL COSMIC RAY CONFERENCE PoGOLite: a balloon-borne soft gamma-ray polarimeter M-dominated active galaxies. Polariza- tion measurements provide a powerful probe of the gamma-ray emission mechanism

  9. JET BREAKS IN SHORT GAMMA-RAY BURSTS. I. THE UNCOLLIMATED AFTERGLOW OF GRB 050724 Dirk Grupe,1

    E-Print Network [OSTI]

    Zhang, Bing

    JET BREAKS IN SHORT GAMMA-RAY BURSTS. I. THE UNCOLLIMATED AFTERGLOW OF GRB 050724 Dirk Grupe,1 the results of the Chandra observations of the Swift-discovered short gamma-ray burst GRB 050724. Chandra corrected energy of GRB 050724 is at least 4 ; 1049 ergs. Subject headinggs: gamma rays: bursts -- X-rays

  10. Magnetic Fields in Gamma-Ray Bursts: A Short Racah Institute for Physics, The Hebrew University, Jerusalem, 91904 Israel

    E-Print Network [OSTI]

    Jensen, Grant J.

    Magnetic Fields in Gamma-Ray Bursts: A Short Overview Tsvi Piran Racah Institute for Physics Abstract. Magnetic fields play a crucial role in the physics of Gamma-Ray Bursts (GRBs). Strong thirty years, after the discovery of Gamma-Ray bursts (GRBs) we have now a reasonable GRB model

  11. The gamma-ray burst monitor for Lobster-ISS L. Amati a,*, F. Frontera a,b

    E-Print Network [OSTI]

    Bogliolo, Alessandro

    The gamma-ray burst monitor for Lobster-ISS L. Amati a,*, F. Frontera a,b , N. Auricchio a , E telescope is flanked by a Gamma Ray Burst Monitor, with the minimum requirement of recognizing true GRBs. Published by Elsevier Ltd. All rights reserved. Keywords: Gamma-rays: bursts; X-rays: transients

  12. Title of Dissertation: A Search for Short Duration Very High Energy Emission from Gamma-Ray Bursts

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    of GRBs. #12;A Search for Short Duration Very High Energy Emission from Gamma-Ray Bursts by David NoyesABSTRACT Title of Dissertation: A Search for Short Duration Very High Energy Emission from Gamma-Ray by gamma rays with primary energies of approximately 100 GeV and higher. The wide field of view ( 2 sr

  13. ON THE KINETIC ENERGY AND RADIATIVE EFFICIENCY OF GAMMA-RAY BURSTS Nicole M. Lloyd-Ronning1

    E-Print Network [OSTI]

    Zhang, Bing

    ON THE KINETIC ENERGY AND RADIATIVE EFFICIENCY OF GAMMA-RAY BURSTS Nicole M. Lloyd-Ronning1 of 17 gamma-ray bursts (GRBs) during the afterglow phase and ac- counting for radiative losses, we the implications of these results for the GRB radiation and jet models. Subject headinggs: gamma rays: bursts

  14. SWIFT PANCHROMATIC OBSERVATIONS OF THE BRIGHT GAMMA-RAY BURST GRB 050525a A. J. Blustin,1

    E-Print Network [OSTI]

    Zhang, Bing

    SWIFT PANCHROMATIC OBSERVATIONS OF THE BRIGHT GAMMA-RAY BURST GRB 050525a A. J. Blustin,1 D. Band,2 ABSTRACT The bright gamma-ray burst GRB 050525a has been detected with the Swift observatory, providing. This jet break time combined with the total gamma-ray energy of the burst constrains the opening angle

  15. Terrestrial gamma ray flashes with energies up to 100 MeV produced by nonequilibrium acceleration of electrons

    E-Print Network [OSTI]

    Pasko, Victor

    . Introduction [2] Terrestrial gamma-ray flashes (TGFs) are bursts of high-energy photons originating fromTerrestrial gamma ray flashes with energies up to 100 MeV produced by nonequilibrium accelerationV) of terrestrial gamma-ray flashes (TGFs). This analysis provides the first direct evidence that TGFs are produced

  16. The Role of Gamma-ray Imaging in Performing Radiological Characterisation at the Magnox Storage Ponds at the Bradwell Decommissioning Site - 13628

    SciTech Connect (OSTI)

    Hughes, Karl; Shaw, Tracey [Babcock International, B14.1, Sellafield, Cumbria, CA20 1PG (United Kingdom)] [Babcock International, B14.1, Sellafield, Cumbria, CA20 1PG (United Kingdom)

    2013-07-01T23:59:59.000Z

    A gamma-ray imaging device has been used to perform radiological characterisation work at the spent fuel ponds complex at the site of the Bradwell Magnox Power Station, which is currently undergoing accelerated decommissioning. The objective of using a gamma-ray imaging system was to independently verify previous radiological survey work and to evaluate the adequacy of the random distribution of the destructive core sampling which had been performed. In performing this work the gamma-ray imager clearly identified the exact locations of the sources of radiation that gave rise to the elevated gamma dose rates measured by conventional health physics surveys of the area. In addition, the gamma-ray imager was able to characterise each hotspot as being either dominated by Cs-137 or by Co-60. The gamma imaging survey was undertaken with a RadScan gamma imaging system deployed on the walkways which run along the lengths of the ponds; this enabled the whole imaging survey to be performed with minimal dose uptake, demonstrating the ALARP principle within decommissioning. (authors)

  17. The worldwide NORM production and a fully automated gamma-ray spectrometer for their characterization

    E-Print Network [OSTI]

    G. Xhixha; GP. Bezzon; C. Broggini; GP. Buso; A. Caciolli; I. Callegari; S. De Bianchi; G. Fiorentini; E. Guastaldi; M. Kaçeli Xhixha; F. Mantovani; G. Massa; R. Menegazzo; L. Mou; A. Pasquini; C. Rossi Alvarez; M. Shyti

    2012-04-24T23:59:59.000Z

    Materials containing radionuclides of natural origin, which is modified by human made processes and being subject to regulation because of their radioactivity are known as NORM. We present a brief review of the main categories of non-nuclear industries together with the levels of activity concentration in feed raw materials, products and waste, including mechanisms of radioisotope enrichments. The global management of NORM shows a high level of complexity, mainly due to different degrees of radioactivity enhancement and the huge amount of worldwide waste production. The future tendency of guidelines concerning environmental protection will require both a systematic monitoring based on the ever-increasing sampling and high performance of gamma ray spectroscopy. On the ground of these requirements a new low background fully automated high-resolution gamma-ray spectrometer MCA_Rad has been developed. The design of Pb and Cu shielding allowed to reach a background reduction of two order of magnitude with respect to laboratory radioactivity. A severe lowering of manpower cost is obtained through a fully automation system, which enables up to 24 samples to be measured without any human attendance. Two coupled HPGe detectors increase the detection efficiency, performing accurate measurements on sample volume (180 cc) with a reduction of sample transport cost of material. Details of the instrument calibration method are presented. MCA_Rad system can measure in less than one hour a typical NORM sample enriched in U and Th with some hundreds of Bq/kg, with an overall uncertainty less than 5%. Quality control of this method has been tested. Measurements of certified reference materials RGK-1, RGU-2 and RGTh-1 containing concentrations of K, U and Th comparable to NORM have been performed, resulting an overall relative discrepancy of 5% among central values within the reported uncertainty.

  18. Inverse Compton e-p pair cascade model for the gamma-ray production in massive binary LSI +61^o 303

    E-Print Network [OSTI]

    W. Bednarek

    2006-07-13T23:59:59.000Z

    We apply an inverse Compton $e^\\pm$ pair cascade model for $\\gamma$-ray production in massive binary system LSI +61$^{\\rm o}$ 303 assuming that electrons are accelerated already inside the inner part of the jet launched by the compact object. $\\gamma$-ray spectra, affected by the cascade process, and lower energy spectra, from the synchrotron cooling of the highest energy electrons in the jet, are calculated as a function of the phase of this binary system. $\\gamma$-ray spectra expected in such model have different shape than that ones produced by electrons in the jet directly to observer. Moreover, the model predicts clear anti-correlation between $\\gamma$-ray fluxes in the GeV (1-10 GeV) and TeV ($>200$ GeV) energy ranges with the peak of the TeV emission at the phase $\\sim$0.5 (the peak half width ranges between the phases $\\sim$0.4-0.9 for the inclination of the binary system equal to $60^{\\rm o}$, and $\\sim$0.4-0.1 for $30^{\\rm o}$). The fine features of TeV $\\gamma$-ray emission (fluxes and spectral shapes) as a function of the phase of the binary system are consistent with recent observations reported by the MAGIC collaboration. Future simultaneous observations in the GeV energies (by the GLAST and AGILE telescopes) and in the TeV energies (by the MAGIC and VERITAS telescopes) should test other predictions of the considered model supporting or disproving the hypothersis of acceleration of electrons already in the inner part of the microquasar jets.

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

    SciTech Connect (OSTI)

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

    2004-12-31T23:59:59.000Z

    The increasing importance of Prompt Gamma-ray ActivationAnalysis (PGAA) in a broad range of applications is evident, and has beenemphasized at many meetings related to this topic (e.g., TechnicalConsultants' Meeting, Use of neutron beams for low- andmedium-fluxresearch reactors: radiography and materialscharacterizations, IAEA Vienna, 4-7 May 1993, IAEA-TECDOC-837, 1993).Furthermore, an Advisory Group Meeting (AGM) for the Coordination of theNuclear Structure and Decay Data Evaluators Network has stated that thereis a need for a complete and consistent library of cold- and thermalneutron capture gammaray and cross-section data (AGM held at Budapest,14-18 October 1996, INDC(NDS)-363); this AGM also recommended theorganization of an IAEA CRP on the subject. The International NuclearData Committee (INDC) is the primary advisory body to the IAEA NuclearData Section on their nuclear data programmes. At a biennial meeting in1997, the INDC strongly recommended that the Nuclear Data Section supportnew measurements andupdate the database on Neutron-induced PromptGamma-ray Activation Analysis (21st INDC meeting, INDC/P(97)-20). As aconsequence of the various recommendations, a CRP on "Development of aDatabase for Prompt Gamma-ray Neutron Activation Analysis (PGAA)" wasinitiated in 1999. Prior to this project, several consultants had definedthe scope, objectives and tasks, as approved subsequently by the IAEA.Each CRP participant assumed responsibility for the execution of specifictasks. The results of their and other research work were discussed andapproved by the participants in research co-ordination meetings (seeSummary reports: INDC(NDS)-411, 2000; INDC(NDS)-424, 2001; andINDC(NDS)-443, 200). PGAA is a non-destructive radioanalytical method,capable of rapid or simultaneous "in-situ" multi-element analyses acrossthe entire Periodic Table, from hydrogen to uranium. However, inaccurateand incomplete data were a significant hindrance in the qualitative andquantitative analysis of complicated capture-gamma spectra by means ofPGAA. Therefore, the main goal of the CRP was to improve the quality andquantity of the required data in order to make possible the reliableapplication of PGAA in fields such as materials science, chemistry,geology, mining, archaeology, environment, food analysis and medicine.This aim wasachieved thanks to the dedicated work and effort of theparticipants. The CD-ROM included with this publication contains thedatabase, the retrieval system, the three CRM reports, and otherimportant electronic documents related to the CRP. The IAEA wishes tothanks all CRP participants who contributed to the success of the CRP andthe formulation of this publication. Special thanks are due to R.B.Firestone for his leading roll in the development of this CRP and hiscomprehensive compilation, analysis and provision of the adopteddatabase, and to V. Zerkin for the software developments associatedwiththe retrieval system. An essential component of this data compilation isthe extensive sets of new measurements of capture gamma-ray energies andintensities undertaken at Budapest by Zs. Revay under the direction ofG.L. Molnar. The extensive participation and assistance of H.D. Choi isalso greatly appreciated. Other participants inthis CRP were: R.M.Lindstrom, S.M. Mughabghab, A.V.R. Reddy, V.H. Tan and C.M. Zhou. Thanksare also due to S.C. Frankle and M.A. Lone for their active participationas consultants at some of the meetings. Finally, the participants wish tothank R. Paviotti-Corcuera (Nuclear Data Section, Division of Physicaland Chemical Sciences), who was the IAEA responsible officer for the CRP,this publication and the resulting database. The participants aregrateful to D.L. Muir and A.L. Nichols, successive Heads of the NuclearData Section, for their active and enthusiastic encouragement infurthering the work of the CRP.

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

    SciTech Connect (OSTI)

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

    2014-02-01T23:59:59.000Z

    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.