WorldWideScience

Sample records for erratum gamma-ray production

  1. Terrestrial gamma ray flash production by lightning current pulses

    OpenAIRE

    İnan, Umran Savaş; Carlson, B. E.; Lehtinen, N. G.

    2017-01-01

    Terrestrial gamma ray flashes (TGFs) are brief bursts of gamma rays observed by satellites, typically in coincidence with detectable lightning. We incorporate TGF observations and the key physics behind current TGF production theories with lightning physics to produce constraints on TGF production mechanisms. The combined constraints naturally suggest a mechanism for TGF production by current pulses in lightning leader channels. The mechanism involves local field enhancements due to charge re...

  2. High energy gamma-ray production in nuclear reactions

    International Nuclear Information System (INIS)

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

    1989-01-01

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

  3. Nuclear models and data for gamma-ray production

    International Nuclear Information System (INIS)

    Young, P.G.

    1975-01-01

    The current Evaluated Nuclear Data File (ENDF/B, Version IV) contains information on prompt gamma-ray production from neutron-induced reactions for some 38 nuclides. In addition, there is a mass of fission product yield, capture, and radioactive decay data from which certain time-dependent gamma-ray results can be calculated. These data are needed in such applications as gamma-ray heating calculations for reactors, estimates of radiation levels near nuclear facilities and weapons, shielding design calculations, and materials damage estimates. The prompt results are comprised of production cross sections, multiplicities, angular distributions, and energy spectra for secondary gamma-rays from a variety of reactions up to an incident neutron energy of 20 MeV. These data are based in many instances on experimental measurements, but nuclear model calculations, generally of a statistical nature, are also frequently used to smooth data, to interpolate between measurements, and to calculate data in unmeasured regions. The techniques and data used in determining the ENDF/B evaluations are reviewed, and comparisons of model-code calculations and ENDF data with recent experimental results are given. 11 figures

  4. Terrestrial gamma ray flash production by active lightning leader channels

    OpenAIRE

    İnan, Umran Savaş; Carlson, B. E.; Lehtinen, N. G.

    2017-01-01

    The production of terrestrial gamma ray flashes (TGFs) requires a seed energetic electron source and a strong electric field. Lightning leaders naturally provide seed electrons by cold runaway and strong electric fields by charge accumulation on the channel. We model possible TGF production in such fields by simulating the charges and currents on the channel. The resulting electric fields then drive simulations of runaway relativistic electron avalanche and photon emission. Photon spectra and...

  5. Resonant production of $\\gamma$ rays in jolted cold neutron stars

    CERN Document Server

    Kusenko, A

    1998-01-01

    Acoustic shock waves passing through colliding cold neutron stars can cause repetitive superconducting phase transitions in which the proton condensate relaxes to its equilibrium value via coherent oscillations. As a result, a resonant non-thermal production of gamma rays in the MeV energy range with power up to 10^(52) erg/s can take place during the short period of time before the nuclear matter is heated by the shock waves.

  6. Terrestrial gamma-ray flash production by lightning

    Science.gov (United States)

    Carlson, Brant E.

    Terrestrial gamma-ray flashes (TGFs) are brief flashes of gamma-rays originating in the Earth's atmosphere and observed by satellites. First observed in 1994 by the Burst And Transient Source Experiment on board the Compton Gamma-Ray Observatory, TGFs consist of one or more ˜1 ms pulses of gamma-rays with a total fluence of ˜1/cm2, typically observed when the satellite is near active thunderstorms. TGFs have subsequently been observed by other satellites to have a very hard spectrum (harder than dN/d E ∝ 1/ E ) that extends from below 25 keV to above 20 MeV. When good lightning data exists, TGFs are closely associated with measurable lightning discharge. Such discharges are typically observed to occur within 300 km of the sub-satellite point and within several milliseconds of the TGF observation. The production of these intense energetic bursts of photons is the puzzle addressed herein. The presence of high-energy photons implies a source of bremsstrahlung, while bremsstrahlung implies a source of energetic electrons. As TGFs are associated with lightning, fields produced by lightning are naturally suggested to accelerate these electrons. Initial ideas about TGF production involved electric fields high above thunderstorms as suggested by upper atmospheric lightning research and the extreme energies required for lower-altitude sources. These fields, produced either quasi-statically by charges in the cloud and ionosphere or dynamically by radiation from lightning strokes, can indeed drive TGF production, but the requirements on the source lightning are too extreme and therefore not common enough to account for all existing observations. In this work, studies of satellite data, the physics of energetic electron and photon production, and consideration of lightning physics motivate a new mechanism for TGF production by lightning current pulses. This mechanism is then developed and used to make testable predictions. TGF data from satellite observations are compared

  7. Soft gamma-ray production in active galactic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, M; Zbyszewska, M

    1985-02-01

    Recent studies by Lightman (1982), Svensson (1984), an others on the pair-equilibrium states of mildly relativistic thermal plasma, including magnetic fields and optical sources are considered. Resulting constraints on luminosities and proton densities together with observational data permit the selection of an accretion scenario in which a high-energy spectrum, similar to that of NGC 4151, is produced. It is shown that soft gamma-ray production via thermal bremsstrahlung can occur in the central region of the two-temperature, geometrically thick part of the disc. On the other hand, the power-law X-ray spectrum is expected to be generated in the intermediate region due to Comptonization of optical photons coming from an outer, geometrically thin part of the disc. Implications for the relation between quasars and Seyfert galaxies are discussed. 27 references.

  8. Productive mutants in lemongrass induced by gamma rays

    International Nuclear Information System (INIS)

    Gopinathan Nair, V.

    1980-01-01

    Seeds of the lemongrass variety O.D. 19 were irradiated with gamma rays at a dose range of 5 to 30 krad. M 1 plants with one or a few tillers differing from the standard plants of O.D. 19 were selected, split into single slips and planted as clonal progenies. Mutants were isolated in M 1 V 1 and carried forward. Forty two M 1 V 2 mutant clones differing from O.D. 19 in morphological characters such as vigour, plant height, growth habit, pigmentation and number of tillers have been established. These were evaluated for tiller number, grass yield and oil content. Six clones gave higher grass yield, the highest being 556 gm per plant per cutting as against 360 gm in the standard. Five clones gave higher oil yield, the highest being 0.42% as against 0.23% in the standard. Isolation of viable mutants with high grass yield and essential oil content indicate the scope for evolving productive mutant varieties in this perennial aromatic grass. The eleven M 1 V 2 mutant clones are being critically evaluated by estimating oil yield per hectare per year. (author)

  9. Erratum

    African Journals Online (AJOL)

    Page 1. ajor flaws ion of the from the nificance. ubstantial enefit was a finding. hy' to talk ess'. He is. Erratum. In the article 'Furosemide chronopharmacology' by B. H. Meyer er al., which appeared in the SAMJ of 18 December 1982, the histograms for Figs 8 and 9 on p. 977 should ha\\'e been transposed.

  10. Gamma rays from Cygnus X-1: Modeling and nonthermal pair production

    International Nuclear Information System (INIS)

    Dermer, C.D.; Liang, E.P.

    1988-02-01

    The gamma-ray bump observed between 0.5 and 2 MeV in the spectrum of Cygnus X-1 can be interpreted as the thermal emissions from a hot (kT/approximately/400 keV) pair-dominated cloud. We argue that the X-rays and gamma rays are produced in separate emission regions, and calculate the photon-photon pair production rate from X-ray and gamma-ray interactions in the vicinity of Cyg X-1 by employing a simplified geometry for the two emitting regions

  11. Gamma-ray production cross sections for MeV neutrons

    International Nuclear Information System (INIS)

    Kitazawa, Hideo; Harima, Yoshiko; Yamakoshi, Hisao; Sano, Yuji; Kobayashi, Tsuguyuki.

    1979-01-01

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

  12. Measurement of neutron and gamma-ray production double differential cross section at KEK

    International Nuclear Information System (INIS)

    Ishibashi, Kenji

    1995-01-01

    High energy nuclear radiations were measured for 0.8-3.0 GeV proton induced reactions at KEK. The measurement was carried out to overcome the problems arising from the use of secondary beam line of a quite low incident beam intensity. Digital pulse shape discrimination method was applicable to separation between high energy neutrons and gamma-rays. By the use of a number of scintillators, cross sections were obtained for production of neutrons and gamma-rays. (author)

  13. Gamma ray NDA assay system for total plutonium and isotopics in plutonium product solutions

    International Nuclear Information System (INIS)

    Cowder, L.R.; Hsue, S.T.; Johnson, S.S.; Parker, J.L.; Russo, P.A.; Sprinkle, J.K.; Asakura, Y.; Fukuda, T.; Kondo, I.

    1979-01-01

    A LASL-designed gamma-ray NDA instrument for assay of total plutonium and isotopics of product solutions at Tokai-Mura is currently installed and operating. The instrument is, optimally, a densitometer that uses radioisotopic sources for total plutonium measurements at the K absorption edge. The measured transmissions of additional gamma-ray lines from the same radioisotopic sources are used to correct for self-attenuation of passive gamma rays from plutonium. The corrected passive data give the plutonium isotopic content of freshly separated to moderately aged solutions. This off-line instrument is fully automated under computer control, with the exception of sample positioning, and operates routinely in a mode designed for measurement control. A one-half percent precision in total plutonium concentration is achieved with a 15-minute measurement

  14. Evaluation of the total gamma-ray production cross-sections for nonelastic interaction of fast neutrons with iron nuclei

    International Nuclear Information System (INIS)

    Savin, M.V.; Nefedov, Yu.Ya; Livke, A.V.; Zvenigorodskij, A.G.

    2001-01-01

    Experimental data on the total gamma-ray production cross-sections for inelastic interaction of fast neutrons with iron nuclei were analysed. The total gamma-ray production cross-sections, grouped according to E γ , were evaluated in the neutron energy range 0.5-19 MeV. The statistical spline approximation method was used to evaluate the experimental data. Evaluated data stored in the ENDF, JENDL, BROND, and other libraries on gamma-ray production spectra and cross-sections for inelastic interaction of fast neutrons with iron nuclei, were analysed. (author)

  15. Gamma-ray spectroscopy of neutron-rich products of heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, M.P.; Janssens, R.V.F.; Ahmad, I. [and others

    1995-08-01

    Thick-target {gamma}{gamma} coincidence techniques are being used to explore the spectroscopy of otherwise hard-to-reach neutron-rich products of deep-inelastic heavy ion reactions. Extensive {gamma}{gamma} coincidence measurements were performed at ATLAS using pulsed beams of {sup 80}Se, {sup 136}Xe, and {sup 238}U on lead-backed {sup 122,124}Sn targets with energies 10-15% above the Coulomb barrier. Gamma-ray coincidence intensities were used to map out yield distributions with A and Z for even-even product nuclei around the target and around the projectile. The main features of the yield patterns are understandable in terms of N/Z equilibration. We had the most success in studying the decays of yrast isomers. Thus far, more than thirty new {mu}s isomers in the Z = 50 region were found and characterized. Making isotopic assignments for previously unknown {gamma}-ray cascades proves to be one of the biggest problems. Our assignments were based (a) on rare overlaps with radioactivity data, (b) on the relative yields with different beams, and (c) on observed cross-coincidences between {gamma} rays from light and heavy reaction partners. However, the primary products of deep inelastic collisions often are sufficiently excited for subsequent neutron evaporation, so {gamma}{gamma} cross-coincidence results require careful interpretation.

  16. The production of sulfur targets for gamma-ray spectroscopy

    CERN Document Server

    Greene, J P

    2002-01-01

    The production of thin sulfur targets for nuclear physics, either in elemental or in compound form, is problematic, due to low melting points, high vapor pressures and high dissociation rates. Many sulfur compounds have been tried in the past without great success. In this paper, we report the use of spray coating molybdenum disulfide onto a thin carbon backing. The targets were of thickness 750 mu g/cm sup 2 (approx 300 mu g/cm sup 2 of sulfur) on 15 mu g/cm sup 2 carbon backings, and withstood 4 pnA (approx 10 mW/cm sup 2) of deposited beam power for several days without apparent loss of sulfur content.

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

    International Nuclear Information System (INIS)

    Semmler, R.

    1993-01-01

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

  18. Evaluation of neutron and gamma-ray-production cross-section data for lead

    International Nuclear Information System (INIS)

    Fu, C.Y.; Perey, F.G.

    1975-01-01

    A survey was made of the available information on neutron and gamma-ray-production cross-section measurements of lead. From these and from relevant nuclear-structure information on the Pb isotopes, recommended neutron cross-section data sets for lead covering the neutron energy range from 0.00001 eV to 20.0 MeV have been prepared. The cross sections are derived from experimental results available to February 1972 and from calculations based on optical-model, DWBA, and Hauser--Feshbach theories. Comparisons which show good agreement between theoretical and experimental values are displayed in a number of graphs. Also presented graphically are smoothed total cross sections, Legendre coefficients for angular distributions, and a representative energy distribution of gamma rays from resonance capture. 15 tables, 36 figures, 104 references

  19. On the high energy gamma ray spectrum and the particle production model

    International Nuclear Information System (INIS)

    Ohta, Itaru; Tezuka, Ikuo.

    1979-01-01

    A small emulsion chamber, 25 cm x 20 cm in area and 12 radiation lengths in thick, was exposed with JAL jet-cargo at an atmospheric depth of 260 g/cm 2 during 150 hrs. The gamma ray spectrum derived by combining data from X-ray films and nuclear emulsions is well represented by I sub(r) (>=Er) = (3.65 +- 0.30) x 10 -8 [E sub(r)/TeV]sup(-1.89+0.06-0.09)/cm 2 sr sec in the energy range 200 - 3,000 GeV. This result is in good agreement with those of several other groups. We discuss our data in terms of Feynman's and Koba-Nielsen-Olesen's scaling law of high energy particle production model. Interpreted in terms of an assumption of mild violation of the scaling law as x.d delta-s / delta-s indx = AE sup(2a)exp (-BE sup(a)x), our gamma ray spectrum results suggest an existence of a violation parameter of a = 0.18, which is consistent with results from gamma ray spectrum observations at great depth such as the mountain elevations. (author)

  20. Utilization of gamma rays in the selection of Aspergillus niger for acid production

    International Nuclear Information System (INIS)

    Silva, J.C. da; Azevedo, J.L.

    1978-01-01

    Selection of Aspergillus niger for acid production was studied by the method of Foster and Davis with the use of gamma rays. Three selection cycles were carried out, and the acid production character of each population was analyzed quantitatively by the unitage acid factor. Isolates with high unitage values in relation to the paternal strain were assayed in a liquid fermentation medium. No correlation was found that would indicate unlimited use of Foster and Davis' method in the selection of more productive strains. (Author) [pt

  1. Measurement of secondary gamma-ray production cross sections of structural materials for fusion reactor. Extraction of discrete and continuum components

    International Nuclear Information System (INIS)

    Kondo, Tetsuo; Morotomi, Ryutaro; Nishio, Takashi; Murata, Isao; Takahashi, Akito

    2000-01-01

    A new method to deal with measured spectrum of secondary gamma-rays induced by D-T neutrons with Ge detector is proposed. Subtracting background components and discrete peaks from the raw secondary gamma-ray spectrum, the continuum component of secondary gamma-ray was successfully extracted. By using unfolding process, the continuum component of the secondary gamma-ray production cross section was derived. The measured cross section data obtained by this method are very useful for precise evaluation of secondary gamma-ray production cross sections. (author)

  2. Differential cross sections for gamma-ray production by 14 MeV neutrons with several elements in structural materials

    International Nuclear Information System (INIS)

    Murata, Isao; Yamamoto, Junji; Takahashi, Akito

    1988-01-01

    Energy differential cross sections for the gamma-rays produced from the (n,xγ) reactions by 14 MeV neutrons were measured in the gamma-ray energy range from 700 keV to 10 MeV using an NaI spectrometer. Results were obtained for the 8 natural elements; C, Al, Si, Cr, Fe, Ni, Cu and Mo. For prominent discrete gamma-rays in the differential cross sections, the production cross sections were determined by measuring angular distributions with a Ge detector. The gamma-ray energy covered the range between 500 and 3000 keV. The energy distributions have been compared with the differential cross sections evaluated in the nuclear data files of JENDL-3T, ENDL and ENDF/B-IV. The evaluations in JENDL-3T agreed fairly well with the measurements concerning the continuum energy spectra for secondary photons. Discrepancies appeared, however, for Si, Cr and Ni at the energies where the discrete gamma-rays were dominant. The ENDL evaluations were largely deviated from the experimental data. The production cross sections for the discrete gamma-rays in ENDL and ENDF/B-IV were available for the comparison with some of the measured cross sections. Results are presented for C, Al and Si. (author)

  3. Erratum

    OpenAIRE

    McDougall, Jason

    2011-01-01

    Schuelert N, Russell FA, McDougall JJ. Topical diclofenac in the treatment of osteoarthritis of the knee. Orthopedic Research and Reviews. 2011;3:1–8.An error in the indication for Solaraze Gel was published in this work. The sentence under the heading “The rationale for topical NSAIDs” that states “At present, four products containing diclofenac for topical application have been approved by the US Food and Drug Administration for the treatment of OA&am...

  4. High-precision gamma-ray spectroscopy for enhancing production and application of medical isotopes

    Science.gov (United States)

    McCutchan, E. A.; Sonzogni, A. A.; Smith, S. V.; Muench, L.; Nino, M.; Greene, J. P.; Carpenter, M. P.; Zhu, S.; Chillery, T.; Chowdhury, P.; Harding, R.; Lister, C. J.

    2015-10-01

    Nuclear medicine is a field which requires precise decay data for use in planning radionuclide production and in imaging and therapeutic applications. To address deficiencies in decay data, sources of medical isotopes were produced and purified at the Brookhaven Linear Isotope Producer (BLIP) then shipped to Argonne National Laboratory where high-precision, gamma-ray measurements were performed using Gammasphere. New decay schemes for a number of PET isotopes and the impact on dose calculations will be presented. To investigate the production of next-generation theranostic or radiotherapeutic isotopes, cross section measurements with high energy protons have also been explored at BLIP. The 100-200 MeV proton energy regime is relatively unexplored for isotope production, thus offering high discovery potential but at the same time a challenging analysis due to the large number of open channels at these energies. Results of cross sections deduced from Compton-suppressed, coincidence gamma-ray spectroscopy performed at Lowell will be presented, focusing on the production of platinum isotopes by irradiating natural platinum foils with 100 to 200 MeV protons. DOE Isotope Program is acknowledged for funding ST5001030. Work supported by the US DOE under Grant DE-FG02-94ER40848 and Contracts DE-AC02-98CH10946 and DE-AC02-06CH11357.

  5. Erratum.

    Science.gov (United States)

    2013-06-01

    Boiger, M., Mesquita, B., Uchida, Y., & Barrett, L. F. (2013). Condoned or Condemned: The Situational Affordance of Anger and Shame in the United States and Japan. Personality and Social Psychology Bulletin, 39(4), 540-553. doi: 10.1177/0146167213478201 This article contained the following errors that were introduced during the production process. Below is how these sentences should have appeared: On page 544, instead of "the relationship between of the actors involved," the sentence should read: "the relationship between the actors involved" On page 545, instead of "and the positive association between power and likelihood of occurrence was stronger for shame situations from Japan (b = .07, Z = 2.00, p = .04) than shame situations from Japan (b = -.02, Z = 0.71, p = .47) from the U.S., χ2(1) = 4.16, p = .04.," the sentence should read: "and the positive association between power and likelihood of occurrence was stronger for shame situations from Japan (b = .07, Z = 2.00, p = .04) than from the U.S. (b = -.02, Z = 0.71, p = .47), χ2(1) = 4.16, p = .04." On page 550, instead of "Americans perceived situations in which their personal flaws were revealed as more shameful, whereas Japanese perceived situations that implied a loss of public face as more shameful χ2(1) = 6.26, p = .01 Japanese and American students also differed substantially in terms of the source of agency eliciting shame: Americans perceived situations in which others' actions caused them to feel shame as more shameful, while Japanese perceived situations in which they themselves were responsible as more shameful χ2(1) = 51.33, p = .001.," the sentence should read: "Americans perceived situations in which their personal flaws were revealed as more shameful, whereas Japanese perceived situations that implied a loss of public face as more shameful, χ2(1) = 38.86, p personal autonomy within close relationships.," the sentence should read: "Thus, angering situations in the United States are promoted

  6. SB3. Experiment on secondary gamma-ray production cross sections averaged over a fast-neutron spectrum for each of 13 different elements plus a stainless steel

    International Nuclear Information System (INIS)

    Maerker, R.E.

    1976-01-01

    The experimental and calculational details for a CSEWG integral data testing shielding experiment are presented. This particular experiment measured the secondary gamma-ray production cross sections averaged over a fast-neutron spectrum for iron, oxygen, sodium, aluminum, copper, titanium, calcium, potassium, silicon, nickel, zinc, barium, sulfur, and a type 321 stainless steel. The gamma-ray production cross sections were binned into 0.5-MeV wide gamma-ray energy intervals. 29 tables, 1 figure

  7. A Pair Production Telescope for Medium-Energy Gamma-Ray Polarimetry

    Science.gov (United States)

    Hunter, Stanley D.; Bloser, Peter F.; Depaola, Gerardo; Dion, Michael P.; DeNolfo, Georgia A.; Hanu, Andrei; Iparraguirre, Marcos; Legere, Jason; Longo, Francesco; McConnell, Mark L.; hide

    2014-01-01

    We describe the science motivation and development of a pair production telescope for medium-energy (approximately 5-200 Mega electron Volts) gamma-ray polarimetry. Our instrument concept, the Advanced Energetic Pair Telescope (AdEPT), takes advantage of the Three-Dimensional Track Imager, a low-density gaseous time projection chamber, to achieve angular resolution within a factor of two of the pair production kinematics limit (approximately 0.6 deg at 70 Mega electron Volts), continuum sensitivity comparable with the Fermi-LAT front detector (is less than 3 x 10(exp -6) Mega electron Volts per square centimeter per second at 70 Mega electron Volts), and minimum detectable polarization less than 10% for a 10 milliCrab source in 10(exp 6) s.

  8. Kinetics Studies on citric acid production by gamma ray induced mutant of Aspergillus niger

    International Nuclear Information System (INIS)

    Begum, A.A.; Choudhury, N.; Islam, M.S.

    1991-01-01

    Effect of cultural pH and incubation temperature on citric acid yield and kinetic patterns of citric acid fermentation by a natural isolate of aspergillus niger as CA16 and one of its gamma ray induced mutants were studied using cane molasses as growth and fermentation substrate. Mutant strain, 277/30 gave maximum citric acid yield of 85 g/l at pH 3.5 and 28 degree centigrade in molasses medium adjusted to 16% sugar and 25% prescott salt in the medium. Parent strain, CA16 gave a maximum yield of 34 g/l at pH 4.0 and 26 degree centigrade in molasses medium adjusted to 16% sugar and 100% prescott salt in the medium. In kinetic studies, strains showed combination kinetics of citric acid fermentation where product formation is directly related to growth and cell mass and indirectly related to carbohydrate uptake

  9. Nuclear structure and shapes from prompt gamma ray spectroscopy of fission products

    International Nuclear Information System (INIS)

    Ahmad, I.; Morss, L.R.; Durell, J.L.

    1996-01-01

    Many nuclear shape phenomena are predicted to occur in neutron-rich nuclei. The best source for the production of these nuclides is the spontaneous fission which produces practically hundreds of nuclides with yields of greater than 0.1 % per decay. Measurements of coincident gamma rays with large Ge arrays have recently been made to obtain information on nuclear structures and shapes of these neutron- rich nuclei. Among the important results that have been obtained from such measurements are octupole correlations in Ba isotopes, triaxial shapes in Ru nuclei, two-phonon vibrations in 106 Mo and level lifetimes and quadrupole moments in Nd isotopes and A=100 nuclei. These data have been used to test theoretical models

  10. Leveraging extreme laser-driven magnetic fields for gamma-ray generation and pair production

    Science.gov (United States)

    Jansen, O.; Wang, T.; Stark, D. J.; d’Humières, E.; Toncian, T.; Arefiev, A. V.

    2018-05-01

    The ability of an intense laser pulse to propagate in a classically over-critical plasma through the phenomenon of relativistic transparency is shown to facilitate the generation of strong plasma magnetic fields. Particle-in-cell simulations demonstrate that these fields significantly enhance the radiation rates of the laser-irradiated electrons, and furthermore they collimate the emission so that a directed and dense beam of multi-MeV gamma-rays is achievable. This capability can be exploited for electron–positron pair production via the linear Breit–Wheeler process by colliding two such dense beams. Presented simulations show that more than 103 pairs can be produced in such a setup, and the directionality of the positrons can be controlled by the angle of incidence between the beams.

  11. White source gamma-ray production spectral measurement facilities in the USA

    International Nuclear Information System (INIS)

    Larson, D.C.; Dickens, J.K.; Nelson, R.O.; Wender, S.A.

    1991-01-01

    The two primary neutron sources for measuring gamma-ray production (GRP) cross sections for basic and applied work in the USA are the Oak Ridge Electron Linear Accelerator (ORELA) located at the Oak Ridge National Laboratory (ORNL) and the Weapons Neutron Research (WNR) facility located at the Los Alamos National Laboratory (LANL). ORELA is based on a 180-MeV electron linear accelerator, while the WNR facility uses the Los Alamos Meson Physics Facility 800 MeV proton beam to produce neutrons. The facilities collectively cover the neutron-energy range from thermal to over 700 MeV. The paper describes the present capabilities for GRP measurements at each facility. 18 refs

  12. The worldwide NORM production and a fully automated gamma-ray spectrometer for their characterization

    International Nuclear Information System (INIS)

    Xhixha, G.; Callegari, I.; Guastaldi, E.; De Bianchi, S.; Fiorentini, G.; Universita di Ferrara, Ferrara; Istituto Nazionale di Fisica Nucleare; Kaceli Xhixha, M.

    2013-01-01

    Materials containing radionuclides of natural origin and being subject to regulation because of their radioactivity are known as Naturally Occurring Radioactive Material (NORM). By following International Atomic Energy Agency, we include in NORM those materials with an activity concentration, which is modified by human made processes. 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 R ad has been developed. The design of lead and cooper 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 small sample volume (180 cm 3 ) with a reduction of sample transport cost of material. Details of the instrument calibration method are presented. MCA R ad system can measure in less than one hour a typical NORM sample enriched in U and Th with some hundreds of Bq kg -1 , with an overall uncertainty less than 5 %. Quality control of this method has been tested. Measurements of three certified reference materials RGK-1, RGU-2 and RGTh-1 containing concentrations of potassium, uranium and thorium comparable to NORM have

  13. Delayed Fission Product Gamma-Ray Transmission Through Low Enriched UO2 Fuel Pin Lattices in Air

    Energy Technology Data Exchange (ETDEWEB)

    Trumbull, TH [Rensselaer Polytechnic Inst., Troy, NY (United States)

    2004-10-18

    The transmission of delayed fission-product gamma rays through various arrangements of low-enriched UO2 fuel pin lattices in an air medium was studied. Experimental measurements, point-kernel and Monte Carlo photon transport calculations were performed to demonstrate the shielding effect of ordered lattices of fuel pins on the resulting gamma-ray dose to a detector outside the lattice. The variation of the gamma-ray dose on the outside of the lattice as a function of radial position, the so-called “channeling” effect, was analyzed. Techniques for performing experimental measurements and data reduction at Rensselaer Polytechnic Institute’s Reactor Critical Facility (RCF) were derived. An experimental apparatus was constructed to hold the arrangements of fuel pins for the measurements. A gamma-ray spectroscopy system consisting of a sodium-iodide scintillation detector was used to collect data. Measurements were made with and without a collimator installed. A point-kernel transport code was developed to map the radial dependence of the gamma-ray flux. Input files for the Monte Carlo code, MCNP, were also developed to accurately model the experimental measurements. The results of the calculations were compared to the experimental measurements. In order to determine the delayed fission-product gamma-ray source for the calculations, a technique was developed using a previously written code, DELBG and the reactor state-point data obtained during the experimental measurements. Calculations were performed demonstrating the effects of material homogenization on the gamma-ray transmission through the fuel pin lattice.Homogeneous and heterogeneous calculations were performed for all RCF fuel pin lattices as well as for a typical commercial pressurized water reactor fuel bundle. The results of the study demonstrated the effectiveness of the experimental measurements to isolate the channeling effect of delayed fission-product gamma-rays through lattices of RCF fuel pins

  14. Gamma ray calibration system

    International Nuclear Information System (INIS)

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

    1981-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-03-01

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

  16. Measurement of secondary gamma-ray production cross sections of vanadium induced by D-T neutrons

    International Nuclear Information System (INIS)

    Kondo, Tetsuo; Murata, Isao; Takahashi, Akito

    1999-01-01

    The secondary gamma-ray production cross sections of vanadium induced by D-T neutrons have been measured. The experimental values were compared with the theoretical calculation results by SINCROS-II and the evaluation result based on experimental data compiled by Simakov. The calculation results supported our data, while Simakov's evaluation did not agree with the present result very well. (author)

  17. Equipment for x- and gamma ray radiography

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  18. Studies of natural radioactivity in cement products using gamma ray spectroscopy

    International Nuclear Information System (INIS)

    Ibrahim, N.; Periasamy, V.

    2000-01-01

    Evidence from our earlier study on several types of building materials has shown that cement contains a substantial amount of natural occurring radioactive materials. There are many brands of cement products available in Malaysia. Although the basic ingredients of cement are similar across brand, their proportion varies. In this study we have selected twelve brands of cement products which are analysed for natural radioactivity (U,Th,K) using gamma ray spectrometry. The gamma energies of interest are 583.1 keV, 609.3 keV and 1460 keV for nuclides 208 Tl, 214 Bi and 40 K respectively. Our findings show a relatively high activity of 40 K for all cement brands, ranging from 33 Bq/kg to as high as 3010 Bq/kg. Uranium activity ranges from 9Bq/kg to 672 Bq/kg while thorium activity was found range from 6Bq/kg to 94 Bq/kg. The radium equivalent activity is calculated for all brands and the values obtained range between 24 Bq/kg to 879 Bq/kg. Eight out of twelve products possess radium equivalent greater than 370 Bq/kg, a threshold limit for radiation dose equivalent to 1.5 mSv per annum. (author)

  19. Production of 147Eu for gamma-ray emission probability measurement

    International Nuclear Information System (INIS)

    Katoh, Keiji; Marnada, Nada; Miyahara, Hiroshi

    2002-01-01

    Gamma-ray emission probability is one of the most important decay parameters of radionuclide and many researchers are paying efforts to improve the certainty of it. The certainties of γ-ray emission probabilities for neutron-rich nuclides are being improved little by little, but the improvements of those for proton-rich nuclides are still insufficient. Europium-147 that decays by electron capture or β + -particle emission is a proton-rich nuclide and the γ-ray emission probabilities evaluated by Mateosian and Peker have large uncertainties. They referred to only one report concerning with γ-ray emission probabilities. Our final purpose is to determine the precise γ-ray emission probabilities of 147 Eu from disintegration rates and γ-ray intensities by using a 4πβ-γ coincidence apparatus. Impurity nuclides affect largely to the determination of disintegration rate; therefore, a highly pure 147 Eu source is required. This short note will describe the most proper energy for 147 Eu production through 147 Sm(p, n) reaction. (author)

  20. Determination of stimulation effective dose of gamma ray on guinea pig to be used for antibody production

    International Nuclear Information System (INIS)

    Arifin, Muchson; Soewarsono, M.

    1983-01-01

    The experiment has been performed on guinea pigs which were irradiated by gamma rays with doses of 0, 150, 300 and 600 rad. Observations were carried out on peripheral blood in regard to red blood cell, white blood cell and haemoglobine, every week after irradiation. +he result obtained showed that 150 rad was the optimal stimulation effective dose for antibody production in guinea pigs. (author)

  1. Determination of stimulation effective dose of gamma ray on guinea pig to be used for antibody production

    Energy Technology Data Exchange (ETDEWEB)

    Arifin, M; Soewarsono, M [National Atomic Energy Agency, Jakarta (Indonesia). Pasar Djumat Research Centre

    1983-04-01

    The experiment has been performed on guinea pigs which were irradiated by gamma rays with doses of 0, 150, 300 and 600 rad. Observations were carried out on peripheral blood in regard to red blood cell, white blood cell and haemoglobine, every week after irradiation. The result obtained showed that 150 rad was the optimal stimulation effective dose for antibody production in guinea pigs. 10 refs.

  2. Production of low energy gamma rays by neutron interactions with fluorine for incident neutron energies between 0.1 and 20 MeV

    International Nuclear Information System (INIS)

    Morgan, G.L.; Dickens, J.K.

    1975-06-01

    Differential cross sections for the production of low-energy gamma rays (less than 240 keV) by neutron interactions in fluorine have been measured for neutron energies between 0.1 and 20 MeV. The Oak Ridge Electron Linear Accelerator was used as the neutron source. Gamma rays were detected at 92 0 using an intrinsic germanium detector. Incident neutron energies were determined by time-of-flight techniques. Tables are presented for the production cross sections of three gamma rays having energies of 96, 110, and 197 keV. (14 figures, 3 tables) (U.S.)

  3. Gamma ray generator

    Science.gov (United States)

    Firestone, Richard B; Reijonen, Jani

    2014-05-27

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

  4. Fast-neutron gamma-ray production from elemental iron: E/sub n/ approx. < 2 MeV

    International Nuclear Information System (INIS)

    Smith, D.L.

    1976-05-01

    A Ge(Li) detector and a fission detector were used to measure elemental differential cross section excitation functions for fast neutron gamma-ray production from iron relative to fast neutron fission of 235 U. Data were acquired at approximately 50 keV intervals with approximately 50 keV neutron-energy resolution from near threshold to approximately 2 MeV. Angular distributions for the 0.847 MeV gamma ray were measured at 0.93, 0.98, 1.08, 1.18, 1.28, 1.38, 1.59, 1.68, 1.79, 1.85 and 2.03 MeV. Significant fourth-order terms were required for the Legendre polynomial expansions used in fitting several of these angular distributions. This casts doubt on the accuracy of the commonly used approximation that the integrated gamma-ray production cross section is essentially equal to 4π times the 55 0 (or 125 0 ) differential cross section. The method employed in processing these data is described. Comparison is made between results from the present work and some previously reported data sets. The uncertainties associated with energy scales, neutron-energy resolution and other experimental factors for these various measurements make it difficult to draw conclusions concerning the observed differences in the values reported for these fluctuating cross sections. 6 tables, 7 figures

  5. Fast-neutron gamma-ray production from elemental iron: E/sub n/ < or approx. = 2 MeV

    International Nuclear Information System (INIS)

    Smith, D.L.

    1976-05-01

    A Ge(Li) detector and a fission detector were used to measure elemental differential cross section excitation functions for fast-neutron gamma-ray production from iron relative to fast-neutron fission of 235 U. Data were acquired at approximately 50 keV intervals with approximately 50 keV neutron-energy resolution from near threshold to approximately 2 MeV. Angular distributions for the 0.847-MeV gamma ray were measured at 0.93, 0.98, 1.08, 1.18, 1.28, 1.38, 1.59, 1.68, 1.79, 1.85 and 2.03 MeV. Significant fourth-order terms were required for the Legendre polynomial expansions used in fitting several of these angular distributions. This casts doubt on the accuracy of the commonly used approximation that the integrated gamma-ray production cross section is essentially equal to 4π times the 55-degree (or 125-degree) differential cross section. The method employed in processing these data is described. Comparison is made between results from the present work and some previously reported data sets. The uncertainties associated with energy scales, neutron-energy resolution and other experimental factors for these various measurements make it difficult to draw conclusions concerning the observed differences in the values reported for these fluctuating cross sections

  6. Beta decay of the fission product 125Sb and a new complete evaluation of absolute gamma ray transition intensities

    Science.gov (United States)

    Rajput, M. U.; Ali, N.; Hussain, S.; Mujahid, S. A.; MacMahon, D.

    2012-04-01

    The radionuclide 125Sb is a long-lived fission product, which decays to 125Te by negative beta emission with a half-life of 1008 day. The beta decay is followed by the emission of several gamma radiations, ranging from low to medium energy, that can suitably be used for high-resolution detector calibrations, decay heat calculations and in many other applications. In this work, the beta decay of 125Sb has been studied in detail. The complete published experimental data of relative gamma ray intensities in the beta decay of the radionuclide 125Sb has been compiled. The consistency analysis was performed and discrepancies found at several gamma ray energies. Evaluation of the discrepant data was carried out using Normalized Residual and RAJEVAL methods. The decay scheme balance was carried out using beta branching ratios, internal conversion coefficients, populating and depopulating gamma transitions to 125Te levels. The work has resulted in the consistent conversion factor equal to 29.59(13) %, and determined a new evaluated set of the absolute gamma ray emission probabilities. The work has also shown 22.99% of the delayed intensity fraction as outgoing from the 58 d isomeric 144 keV energy level and 77.01% of the prompt intensity fraction reaching to the ground state from the other excited states. The results are discussed and compared with previous evaluations. The present work includes additional experimental data sets which were not included in the previous evaluations. A new set of recommended relative and absolute gamma ray emission probabilities is presented.

  7. Beta decay of the fission product 125Sb and a new complete evaluation of absolute gamma ray transition intensities

    International Nuclear Information System (INIS)

    Rajput, M.U.; Ali, N.; Hussain, S.; Mujahid, S.A.; MacMahon, D.

    2012-01-01

    The radionuclide 125 Sb is a long-lived fission product, which decays to 125 Te by negative beta emission with a half-life of 1008 day. The beta decay is followed by the emission of several gamma radiations, ranging from low to medium energy, that can suitably be used for high-resolution detector calibrations, decay heat calculations and in many other applications. In this work, the beta decay of 125 Sb has been studied in detail. The complete published experimental data of relative gamma ray intensities in the beta decay of the radionuclide 125 Sb has been compiled. The consistency analysis was performed and discrepancies found at several gamma ray energies. Evaluation of the discrepant data was carried out using Normalized Residual and RAJEVAL methods. The decay scheme balance was carried out using beta branching ratios, internal conversion coefficients, populating and depopulating gamma transitions to 125 Te levels. The work has resulted in the consistent conversion factor equal to 29.59(13) %, and determined a new evaluated set of the absolute gamma ray emission probabilities. The work has also shown 22.99% of the delayed intensity fraction as outgoing from the 58 d isomeric 144 keV energy level and 77.01% of the prompt intensity fraction reaching to the ground state from the other excited states. The results are discussed and compared with previous evaluations. The present work includes additional experimental data sets which were not included in the previous evaluations. A new set of recommended relative and absolute gamma ray emission probabilities is presented.

  8. Erratum: "Low-Resolution Spectroscopy of Gamma-Ray Burst Optical Afterglows: Biases in the Swift Sample and Characterization of the Absorbers" (2009, ApJS, 185, 526)

    Science.gov (United States)

    Fynbo, J. P. U.; Jakobsson, P.; Prochaska, J. X.; Malesani, D.; Ledoux, C.; de Ugarte Postigo, A.; Nardini, M.; Vreeswijk, P. M.; Wiersema, K.; Hjorth, J.; Sollerman, J.; Chen, H.-W.; Thöne, C. C.; Björnsson, G.; Bloom, J. S.; Castro-Tirado, A.; Christensen, L.; De Cia, A.; Fruchter, A. S.; Gorosabel, J. U.; Graham, J. F.; Jaunsen, A. O.; Jensen, B. L.; Kann, D. A.; Kouveliotou, C.; Levan, A.; Maund, J.; Masetti, N.; Milvang-Jensen, B.; Palazzi, E.; Perley, D. A.; Pian, E.; Rol, E.; Schady, P.; Starling, R.; Tanvir, N.; Watson, D. J.; Xu, D.; Augusteijn, T.; Grundahl, F.; Telting, J.; Quirion, P.-O.

    2010-02-01

    In this paper, Figure 14 is incomplete due to an error during production. We here provide the missing sub-figures. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under programs 275.D-5022, 075.D-0270, 077.D-0661, 077.D-0805, 078.D-0416, 079.D-0429, 080.D-0526, 081.A-0135, 281.D-5002, and 081.A-0856. Also based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Some of the data obtained herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  9. Semi-pilot scale production of citric acid in cane molasses by gamma-ray induced mutants of Aspergillus niger

    Energy Technology Data Exchange (ETDEWEB)

    Islam, M.S.; Begum, R.; Choudhury, N.

    1986-08-01

    Utilizing cane molasses as substrate, semi-pilot scale production of citric acid was investigated in fermentation trays (40 x 35 cm) with several gamma-ray induced mutants of Aspergillus niger. Of the mutants tested, two were found to have high yield efficiency (14/20, 51.06%; 79/20, 50.35%) of sugar to citric acid. The yield of other mutants (HB3, 10/20, 164/20, 277/30 and 112/40) ranged between 30 to 42%. The prospect of utilizing the high yielding mutants for commercial production of citric acid has been discussed.

  10. Semi-pilot scale production of citric acid in cane molasses by gamma-ray induced mutants of Aspergillus niger

    International Nuclear Information System (INIS)

    Islam, M.s.; Begum, R.; Choudhury, N.

    1986-01-01

    Utilizing cane molasses as substrate, semi-pilot scale production of citric acid was investigated in fermentation trays (40 x 35 cm) with several gamma-ray induced mutants of Aspergillus niger. Of the mutants tested, two were found to have high yield efficiency (14/20, 51.06%; 79/20, 50.35%) of sugar to citric acid. The yield of other mutants (HB3, 10/20, 164/20, 277/30 and 112/40) ranged between 30 to 42%. The prospect of utilizing the high yielding mutants for commercial production of citric acid has been discussed. (author)

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

    Science.gov (United States)

    Norman, Eric B [Oakland, CA; Prussin, Stanley G [Kensington, CA

    2009-01-27

    A method and a system for detecting the presence of special nuclear materials in a suspect container. The system and its method include irradiating the suspect container with a beam of neutrons, so as to induce a thermal fission in a portion of the special nuclear materials, detecting the gamma rays that are emitted from the fission products formed by the thermal 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.

  12. Electron-positron pair production by gamma-rays in an anisotropic flux of soft photons, and application to pulsar polar caps

    Science.gov (United States)

    Voisin, Guillaume; Mottez, Fabrice; Bonazzola, Silvano

    2018-02-01

    Electron-positron pair production by collision of photons is investigated in view of application to pulsar physics. We compute the absorption rate of individual gamma-ray photons by an arbitrary anisotropic distribution of softer photons, and the energy and angular spectrum of the outgoing leptons. We work analytically within the approximation that 1 ≫ mc2/E > ɛ/E, with E and ɛ the gamma-ray and soft-photon maximum energy and mc2 the electron mass energy. We give results at leading order in these small parameters. For practical purposes, we provide expressions in the form of Laurent series which give correct reaction rates in the isotropic case within an average error of ˜ 7 per cent. We apply this formalism to gamma-rays flying downward or upward from a hot neutron star thermally radiating at a uniform temperature of 106 K. Other temperatures can be easily deduced using the relevant scaling laws. We find differences in absorption between these two extreme directions of almost two orders of magnitude, much larger than our error estimate. The magnetosphere appears completely opaque to downward gamma-rays while there are up to ˜ 10 per cent chances of absorbing an upward gamma-ray. We provide energy and angular spectra for both upward and downward gamma-rays. Energy spectra show a typical double peak, with larger separation at larger gamma-ray energies. Angular spectra are very narrow, with an opening angle ranging from 10-3 to 10-7 radians with increasing gamma-ray energies.

  13. High-energy gamma-ray and neutrino production in star-forming galaxies across cosmic time: Difficulties in explaining the IceCube data

    Science.gov (United States)

    Sudoh, Takahiro; Totani, Tomonori; Kawanaka, Norita

    2018-04-01

    We present new theoretical modeling to predict the luminosity and spectrum of gamma-ray and neutrino emission of a star-forming galaxy, from the star formation rate (ψ), gas mass (Mgas), stellar mass, and disk size, taking into account production, propagation, and interactions of cosmic rays. The model reproduces the observed gamma-ray luminosities of nearby galaxies detected by Fermi better than the simple power-law models as a function of ψ or ψMgas. This model is then used to predict the cosmic background flux of gamma-rays and neutrinos from star-forming galaxies, by using a semi-analytical model of cosmological galaxy formation that reproduces many observed quantities of local and high-redshift galaxies. Calibration of the model using gamma-ray luminosities of nearby galaxies allows us to make a more reliable prediction than previous studies. In our baseline model, star-forming galaxies produce about 20% of the isotropic gamma-ray background unresolved by Fermi, and only 0.5% of IceCube neutrinos. Even with an extreme model assuming a hard injection cosmic-ray spectral index of 2.0 for all galaxies, at most 22% of IceCube neutrinos can be accounted for. These results indicate that it is difficult to explain most of the IceCube neutrinos by star-forming galaxies, without violating the gamma-ray constraints from nearby galaxies.

  14. High-energy particle production in solar flares (SEP, gamma-ray and neutron emissions). [solar energetic particles

    Science.gov (United States)

    Chupp, E. L.

    1987-01-01

    Electrons and ions, over a wide range of energies, are produced in association with solar flares. Solar energetic particles (SEPs), observed in space and near earth, consist of electrons and ions that range in energy from 10 keV to about 100 MeV and from 1 MeV to 20 GeV, respectively. SEPs are directly recorded by charged particle detectors, while X-ray, gamma-ray, and neutron detectors indicate the properties of the accelerated particles (electrons and ions) which have interacted in the solar atmosphere. A major problem of solar physics is to understand the relationship between these two groups of charged particles; in particular whether they are accelerated by the same mechanism. The paper reviews the physics of gamma-rays and neutron production in the solar atmosphere and the method by which properties of the primary charged particles produced in the solar flare can be deduced. Recent observations of energetic photons and neutrons in space and at the earth are used to present a current picture of the properties of impulsively flare accelerated electrons and ions. Some important properties discussed are time scale of production, composition, energy spectra, accelerator geometry. Particular attention is given to energetic particle production in the large flare on June 3, 1982.

  15. Measurement of gamma-ray production cross sections in neutron-induced reactions for Al and Pb

    International Nuclear Information System (INIS)

    Pavlik, A.; Vonach, H.; Hitzenberger, H.

    1995-01-01

    The prompt gamma-radiation from the interaction of fast neutrons with aluminum and lead was measured using the white neutron beam of the WNR facility at the Los Alamos National Laboratory. The samples (Al and isotopically enriched 207 Pb and 208 Pb) were positioned at about 20 m or 41 m distance from the neutron production target. The spectra of the emitted gamma-rays were measured with a high-resolution HPGe detector. The incident neutron energy was determined by the time-of-flight method and the neutron fluence was measured with a U fission chamber. From the aluminum gamma-ray spectra excitation functions for prominent gamma-transitions in various residual nuclei (in the range from O to Al) were derived for neutron energies from 3 MeV to 400 MeV. For lead (n,xnγ) reactions were studied for neutron energies up to 200 MeV by analyzing prominent gamma-transitions in the residual nuclei 200,202,204,206,207,208 Pb. The experimental results were compared with nuclear model calculations using the code GNASH. A good overall agreement was obtained without special parameter adjustments

  16. Fission-product yields for thermal-neutron fission of 243Cm determined from measurements with a high-resolution low-energy germanium gamma-ray detector

    International Nuclear Information System (INIS)

    Merriman, L.D.

    1984-04-01

    Cumulative fission-product yields have been determined for 13 gamma rays emitted during the decay of 12 fission products created by thermal-neutron fission of 243 Cm. A high-resolution low-energy germanium detector was used to measure the pulse-height spectra of gamma rays emitted from a 77-nanogram sample of 243 Cm after the sample had been irradiated by thermal neutrons. Analysis of the data resulted in the identification and matching of gamma-ray energies and half-lives to individual radioisotopes. From these results, 12 cumulative fission product yields were deduced for radionuclides with half-lives between 4.2 min and 84.2 min. 7 references

  17. Gamma ray beam transmutation

    International Nuclear Information System (INIS)

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

    2007-01-01

    We have proposed a new approach to nuclear transmutation by a gamma ray beam of Compton scattered laser photon. We obtained 20 MeV gamma ray in this way to obtain transmutation rates with the giant resonance of 1 97Au and 1 29Iodine. The rate of the transmutation agreed with the theoretical calculation. Experiments on energy spectrum of positron, electron and neutron from targets were performed for the energy balance and design of the system scheme. The reaction rate was about 1.5∼4% for appropriate photon energies and neutron production rate was up to 4% in the measurements. We had stored laser photon more than 5000 times in a small cavity which implied for a significant improvement of system efficiency. Using these technologies, we have designed an actual transmutation system for 1 29Iodine which has a 16 million year's activity. In my presentation, I will address the properties of this scheme, experiments results and transmutation system for iodine transmutation

  18. Terrestrial gamma-ray flashes

    Science.gov (United States)

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

    2013-08-01

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

  19. Terrestrial gamma-ray flashes

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  20. Differential production of proteolytic enzymes by normal human fibroblasts and their counterparts transformed by treatment with 60Co gamma rays

    International Nuclear Information System (INIS)

    Nishitani, Koji; Namba, Masayoshi; Ohkubo, Shigeki; Kimoto, Tetsuo

    1985-01-01

    Production of proteolytic enzymes by human fibroblasts in the process of transformation was investigated. The cells used were normal human fibroblasts (KSM-6) and their in vitro counterparts transformed by treatment with 60 Co gamma rays (KMST-6). Cells seeded by treatment with EDTA were cultured in a serum free medium. Proteolytic enzymes in the culture medium of cells were assayed using a synthetic substrate, N-α-(p-tosyl)-L-arginine ( 3 H) methyl ester hydrochloride. The transformed cells (KMST-6) produced a larger amount of enzymes than normal cells (KMS-6). The enzyme production in both cell lines was high in the exponential growth stage and then decreased as the cells reached confluency. The proteolytic enzymes produced by these cells were trypsin- and thrombin-like enzymes. Cell growth of KMST-6 or KMS-6 was not inhibited by the addition of protease inhibitors to the culture medium. (author)

  1. Gamma ray astronomy

    International Nuclear Information System (INIS)

    Fichtel, C.E.

    1975-01-01

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

  2. Long gamma-ray burst as a production site of r-process elements

    International Nuclear Information System (INIS)

    Nakamrua, Ko; Harikae, Seiji; Kajino, Toshitaka; Mathews, Grant J.

    2012-01-01

    We simulated the r-process nucleosynthesis in and around a high entropy jet from a long gamma-ray burst (GRB). Our simulation is based on the collapsar scenario for long GRBs and on relativistic magnetohydrodynamic simulations (Harikae et al. 2009, 2010) including ray-tracing neutrino transport, which describe the development of the black hole accretion disk and the heating of the funnel region to produce a relativistic jet. The time evolution of the jet was then extended to later phase via axi-symmetric special relativistic hydrodynamic simulation to follow the temperature, entropy, electron fraction, and density evolution for representative test particles. The evolution of nuclear abundances from nucleons to heavy nuclei for representative test particle trajectories was solved in a large nuclear reaction network including more than 5000 isotopes. We show that a robust r-process successfully occurs within the collapsar jet outflow and that sufficient mass is ejected within the flow to account for the observed r-process abundance distribution along with the large dispersion in r-process elements observed in metal-poor halo stars.

  3. NECESSARY CONDITIONS FOR SHORT GAMMA-RAY BURST PRODUCTION IN BINARY NEUTRON STAR MERGERS

    International Nuclear Information System (INIS)

    Murguia-Berthier, Ariadna; Montes, Gabriela; Ramirez-Ruiz, Enrico; De Colle, Fabio; Lee, William H.

    2014-01-01

    The central engine of short gamma-ray bursts (sGRBs) is hidden from direct view, operating at a scale much smaller than that probed by the emitted radiation. Thus we must infer its origin not only with respect to the formation of the trigger—the actual astrophysical configuration that is capable of powering an sGRB—but also from the consequences that follow from the various evolutionary pathways that may be involved in producing it. Considering binary neutron star mergers we critically evaluate, analytically and through numerical simulations, whether the neutrino-driven wind produced by the newly formed hyper-massive neutron star can allow the collimated relativistic outflow that follows its collapse to actually produce an sGRB or not. Upon comparison with the observed sGRB duration distribution, we find that collapse cannot be significantly delayed (≤100 ms) before the outflow is choked, thus limiting the possibility that long-lived hyper-massive remnants can account for these events. In the case of successful breakthrough of the jet through the neutrino-driven wind, the energy stored in the cocoon could contribute to the precursor and extended emission observed in sGRBs

  4. ICIT contribution to JET gamma-ray diagnostics enhancement

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  5. Production cross section measurement of discrete gammas-ray at 90 degree for interactions of 14. 9 MeV neutrons with carbon and niobium

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Hongyu; Yan Yiming; Tang lin; Wen Chenlin; Zhang Shenji; Hua Ming; Han Chongzhan; Ding Xiaoji; Lan Liqiao; Fan Guoying; Yan Hua; Wang Xingfu; Wang Qi; Sun Suxu; Rong Yaning; Liu Shuzhen (Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing (CN))

    1989-05-01

    The cross sections of discrete gamma-ray produced by interactions of 14.9 MeV neutrons with carbon and niobium were investigated. A pulsed {ital T}({ital d},{ital n}){sup 4} He neutron source was used in the measurement. Neutron flux incident upon the sample was determined with the associated particle method. Technique of time-of-flight was used for reducing the background. A new method to calculate neutron flux attenuation in large cylindrical sample was proposed. The split of 4.439 MeV gamma-ray line from {sup 12}C({ital n},{ital n}{prime}{gamma}){sup 12}C reactions was confirmed. 79 discrete gamma-ray lines and their production cross sections for the interactions of 14.9 MeV neutrons with niobium were obtained for the first time.

  6. A rapid analysis of {sup 226}Ra in raw materials and by-products using gamma-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Chung Sup; Chung, Kun Ho; Kim, Chang Jong; Ji, Young Yong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-03-15

    A gamma-ray peak of {sup 226}Ra (186.2 keV) overlaps with one of {sup 235}U (185.7 keV) in a gamma-ray spectrometry system. Though reference peaks of {sup 235}U can be used to correct the peak interference of {sup 235}U in the analysis of {sup 226}Ra, this requires a complicated calculation process and a high limit of quantitation. On the other hand, evaluating {sup 226}Ra using the correction constant in the overlapped peak can make a rapid measurement of {sup 226}Ra without the complicated calculation process as well as overcome the disadvantage in the indirect measurement of {sup 214}Bi, which means the confinement of {sup 222}Rn gas in a sample container and a time period to recover the secular equilibrium. About 93 samples with 6 species for raw-materials and by-products were prepared to evaluate the activity of {sup 226}Ra using the correction constant. The results were compared with the activity of {sup 214}Bi, which means the indirect measurement of {sup 226}Ra, to validate the method of the direct measurement of {sup 226}Ra using the correction constant. The difference between the direct and indirect measurement of {sup 226}Ra was generally below about ± 20%. However, in the case of the phospho gypsum, a large error of about 50% was found in the comparison results, which indicates the disequilibrium between {sup 238}U and {sup 226}Ra in the materials. Application results of the contribution ratio of {sup 226}Ra were below about ± 10% . The direct measurement of {sup 226}Ra using the correction constant can be an effective method for its rapid measurement of raw materials and by-products because the activity of {sup 226}Ra can be produced with a simple calculation without the consideration of the integrity of a sample container and the time period to recover the secular equilibrium.

  7. Production of gamma ray bursts from asymmetric core combustion of magnetized young neutron stars

    Science.gov (United States)

    de Gouveia dal Pino, E. M.; Lugones, G.; Horvath, J. E.; Ghezzi, C. R.

    2005-09-01

    Many works in the past have explored the idea that the conversion of hadronic matter into strange quark matter in neutron stars may be an energy source for GRBs (see references in Lugones et al. 2002, Lugones and Horvath 2003). These models addressed essentially spherically symmetric conversions of the whole neutron star rendering isotropic gamma emission. Accumulating observational evidence suggests that at least ''long'' GRBs are strongly asymmetric, jet-like outflows. The ''short'' burst subclass is not obviously asymmetric, and they may actually be spherically symmetric if the sources are close enough. A new potentially important feature recently recognized (Lugones et al. 2002) is that if a conversion to strange quark matter actually begins near the center of a neutron star, the presence of a magnetic field with intensity B ˜ 1013 G (see also Ghezi, de Gouveia Dal Pino & Horvath 2004) will originate a prompt collimated gamma emission, which may be observed as a short, beamed GRB after the recovery of a fraction of the neutrino energy via ν {barν} → e+e- → γγ. The calculations show that the neutrino luminosity is ˜ 1053 erg/sec and that the e+e- luminosity is about two orders of magnitude smaller ( tet{Lugones2002grb}). We find that 90 % of the e+e- pairs are injected inside small cylinders located just above the polar caps (with radius δ and height 0.4 R) in a timescale of τi ≃ 0.2 s almost independently of the initial temperature. This provides an interesting suitable explanation for the inner engine of short gamma ray bursts.

  8. Gamma-ray sources

    International Nuclear Information System (INIS)

    Hermsen, W.

    1980-01-01

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

  9. Gamma ray astronomy

    International Nuclear Information System (INIS)

    Hillier, R.

    1984-01-01

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

  10. VELOCIRAPTOR: An X-band photoinjector and linear accelerator for the production of Mono-Energetic {gamma}-rays

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S.G., E-mail: anderson131@llnl.gov [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94551 (United States); Albert, F.; Bayramian, A.J.; Beer, G.; Bonanno, R.E.; Cross, R.R.; Deis, G.; Ebbers, C.A.; Gibson, D.J.; Hartemann, F.V.; Houck, T.L.; Marsh, R.A.; McNabb, D.P.; Messerly, M.J.; Scarpetti, R.D.; Shverdin, M.Y.; Siders, C.W.; Wu, S.S.; Barty, C.P.J. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94551 (United States); Adolphsen, C.E. [SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, CA 94025 (United States); and others

    2011-11-21

    The rf photoinjector and linear accelerator in the Mono-Energetic Gamma-ray (MEGa-ray) facility at LLNL is presented. This machine uses 11.4 GHz rf technology to accelerate a high-brightness electron beam up to 250 MeV to produce MeV {gamma}-rays through Compton scattering with a Joule-class laser pulse. Compton scattering-based generation of high flux, narrow bandwidth {gamma}-rays places stringent requirements on the performance of the accelerator. The component parts of the accelerator are presented and their requirements described. Simulations of expected electron beam parameters and the resulting light source properties are presented.

  11. SB2. Experiment on secondary gamma-ray production cross sections arising from thermal-neutron capture in each of 14 different elements plus a stainless steel

    International Nuclear Information System (INIS)

    Maerker, R.E.

    1976-01-01

    The experimental and calculational details for a CSEWG integral data testing shielding experiment are presented. This particular experiment measured the secondary gamma-ray production cross sections arising from thermal-neutron capture in iron, nitrogen, sodium, aluminum, copper, titanium, calcium, potassium, chlorine, silicon, ickel, zinc, barium, sulfur and a type 321 stainless steel. 1 figure, 30 tables

  12. Gamma ray astronomy from satellites and balloons

    International Nuclear Information System (INIS)

    Schoenfelder, V.

    1986-01-01

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

  13. Non-invasive analysis of industrial products using the simultaneous transmission of neutrons and gamma rays (Neugat) method

    International Nuclear Information System (INIS)

    Bartle, C.M.

    1998-01-01

    This research programme is designed to develop industrial measurement systems utilising simultaneous transmission of neutrons and gamma rays (Neugat method). Descriptions of these systems have been given in reports and magazine articles, and industrial site trials have been undertaken. (author)

  14. Gamma-ray production cross sections for 0.9 to 20 MeV neutron interactions with 10B

    International Nuclear Information System (INIS)

    Bywater, R.L. Jr.

    1986-09-01

    Gamma-ray spectral data previously obtained at the 20-meter station of the Oak Ridge Electron Linear Accelerator flight-path 8 were studied to determine cross sections for 0.9- to 20-MeV neutron interactions with 10 B. Data reduction techniques, including those for determination of incident neutron fluences as well as those to compensate for Doppler-broadened gamma-ray-detection responses, are given in some detail in this report. 9 refs., 4 figs., 2 tabs

  15. Basics of Gamma Ray Detection

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-09-13

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

  16. Possible existence of cosmological cosmic rays I. the framework for light-element and gamma-ray production

    International Nuclear Information System (INIS)

    Montmerle, T.

    1977-01-01

    This paper examines the possibility of the existence of cosmological cosmic rays (CCR), in the framework of big-bang cosmology. The model assumes a total energy spectrum similar to that observed at Earth at high energies, a composition of protons and α-particles only, with α/p=0.1. Following Stecker, the CCR are assumed to be born in a burst at some (high) redshift z/sub s/. Gamma-rays originate from π 0 decay resulting from interactions of the high-energy part of the CCR, and light elements are produced via (pα)+(pα) reactions by the low-energy part, both of them by collisions with the ambient matter (of density corresponding to a deceleration parameter q 0 ).The 1--100 MeV γ-ray background spectrum and the lithium abundance are considered as observational constraints on the possible CCR flux intensity. To this end, a theoretical framework is set for simultaneous γ-ray and light-element production by solving a system of coupled time-dependent transport equations, taking ionization and expansion losses into account. The absolute lithium abundance is calculated by normalizing the CCR flux to the observed γ-ray background spectrum; numerical results will be given and discussed in a separate paper, as a function of q 0 and z/sub s/

  17. Determination of yields of gaseous products of carbohydrates radiolysis by mass spectrometry method. [. gamma. rays

    Energy Technology Data Exchange (ETDEWEB)

    Ivko, A A; Gol' din, S I; Bondarenko, N T; Markevich, S V; Sharpatii, V A [AN SSSR, Moscow. Inst. Khimicheskoj Fiziki

    1977-01-01

    Possible complications are treated involved in the mass spectral study of the radiolytic products of deuterated carbohydrates. A method is proposed suitable for the evaluation of hydrogen isotopes relations and the content of deuterium in water. It has been possible to identify the major gaseous radiolytic products of glucose, polyglucan and dextran, and also to assess their radiation-chemical yields.

  18. Thick-target neutron, gamma-ray, and radionuclide production for protons below 12 MeV on nickel and carbon beam-stops

    International Nuclear Information System (INIS)

    Chadwick, M.B.; Young, P.G.; Wilson, W.B.

    1998-03-01

    Nuclear model calculations using the GNASH code are described for protons below 12 MeV incident on nickel and carbon isotopes, for beam stop design in the Los Alamos Accelerator Production of Tritium Low Energy Demonstration Accelerator (LEDA) project. The GNASH calculations apply Hauser-Feshbach and preequilibrium reaction theories and can make use of pre-calculated direct reaction cross sections to low-lying residual nucleus states. From calculated thin target cross sections, thick target 6.7 MeV and 12 MeV proton-induced production of neutrons, gamma rays, and radionuclides are determined. Emission spectra of the secondary neutrons and gamma rays are also determined. The model calculations are validated through comparisons with experimental thin- and thick-target measurements. The results of this work are being utilized as source terms in MCNP analyses for LEDA

  19. Fission product gamma-ray sources as an alternative to cobalt-60 sources for sewage sludge sterilization

    International Nuclear Information System (INIS)

    Herrnberger, V.R.D.

    1975-01-01

    The sterilization of sewage sludge is now performed successfully using 60 Co gamma-ray sources. The question arises whether more economic gamma-ray sources exist that could replace the 60 Co source. The following types of sources are considered: Spent fuel elements; mixtures of solidified fission products; and isolated solidified fission products such as 134 / 137 Cs. For a particular irradiation plant the specific source costs (S.Fr./Ci) and their contribution to the irradiation costs for 1 m 3 of sewage irradiated to a dose of 250 krad(S.Fr./m 3 ) are determined and compared with the costs of a plant using a 60 Co source. The encapsulation costs and the effect of the gamma absorption of the source are taken into account. Different encapsulation and source management techniques are reviewed to find the most economic for each source type. A spent fuel element irradiation facility is recommended for use either in combination with a sewage water purification plant or as part of a power reactor station where it replaces the storage water pool for the spent fuel elements. Additional source capsules are not envisaged, as long as double-walled source containers are used. The fission product mixtures are enclosed in double-walled capsules of two different forms: Small cylindrical rods and hollow cylinders. For caesium and cobalt cylindrical rods only are used. The main conclusions of the study are that the highest irradiation costs arise from the use of a fission product mixture source. The costs are, however, only 15% above those of a 60 Co plant. To be competitive the flow-rate has to be adapted to the decreasing activity of the source, resulting in a reduction to 20% within ten years of source utilization. The integrated irradiation plant with a spent fuel element source offers irradiation costs comparable with those of a 60 Co plant, if the flow-rate is constant during one year of source utilization. The irradiation costs are reduced to 25% of those of a 60 Co plant

  20. Evaluation of the neutron and gamma-ray production cross-sections for 55Mn

    International Nuclear Information System (INIS)

    Takahashi, H.

    1974-11-01

    The evaluation of neutron and gamma production cross sections for manganese-55 from 1.0 (10) -5 eV to 20.0 MeV for ENDF/ B-IV is summarized. Included are resonance parameters, neutron cross sections, angular and energy distribution of secondary neutrons, gamma multiplicities and transition probability array, gamma angular and energy distributions, nuclear model calculations, uncertainty estimates of cross sections, and evaluated cross sections. (U.S.)

  1. Gamma-Ray Bursts

    Science.gov (United States)

    Pellizza, L. J.

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

  2. Gamma Ray Bursts

    Science.gov (United States)

    Gehrels, Neil; Meszaros, Peter

    2012-01-01

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

  3. Lunar occultations for gamma-ray source measurements

    Science.gov (United States)

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

    1990-01-01

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

  4. Recent status on cobalt-60 gamma ray radiation sources production and its application in China

    International Nuclear Information System (INIS)

    Cao Zhijian; Song Yunjiang; Zhang Chunhua; Li Maoling

    1993-01-01

    This paper describes the status of Co-60 γ ray radiation sources and their application in China. At present, the production capacity of Co-60 γ ray radiation sources in China is about 11.1 PBq (0.3 MCi) per year. 5 years later, it is increased to 37 PBq (1 MCi) per year. The radioactivity of each source is 370 TBq - 740 TBq (1000-2000 Ci). There are over 150 Co-60 γ ray radiation facilities with total design capacity of over 370 PBq (10 MCi) and practical capacity of about 92.5 PBq (2.5 MCi) in operation. The number of Co-60 γ ray radiation facilities with practical capacity of over 3.7 PBq (0.1 MCi) is 14. The main applications of the Co-60 γ ray sources are radiation crosslinking, radiation sterilization of disposable medical supplies and food irradiation. The prospects for Co-60 γ ray radiation source application in China are good. (author)

  5. Early results utilizing high-energy fission product gamma rays to detect fissionable material in cargo

    International Nuclear Information System (INIS)

    Slaughter, D.R.; Accatino, M.R.; Alford, O.J.; Bernstein, A.; Descalle, M.; Gosnell, T.B.; Hall, J.M.; Loshak, A.; Manatt, D.R.; McDowell, M.R.; Moore, T.L.; Petersen, D.C.; Pohl, B.A.; Pruet, J.A.; Prussin, S.G.

    2004-01-01

    Full text: A concept for detecting the presence of special nuclear material ( 235 U or 239 Pu) concealed in inter modal cargo containers is described. It is based on interrogation with a pulsed beam of 6-8 MeV neutrons and fission events are identified between beam pulses by their β-delayed neutron emission or β -delayed high-energy γ-radiation. The high-energy γ-ray signature is being employed for the first time. Fission product γ-rays above 3 MeV are distinct from natural radioactivity and from nearly all of the induced activity in a normal cargo. High-energy γ-radiation is nearly 10X more abundant than the delayed neutrons and penetrates even thick cargo's readily. The concept employs two large (8x20 ft) arrays of liquid scintillation detectors that have high efficiency for the detection of both delayed neutrons and delayed γ-radiation. Detector backgrounds and potential interferences with the fission signature radiation have been identified and quantified. This information, together with predicted signature strength, has been applied to the estimation of detection probability for the nuclear material and estimation of false alarm rates. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48

  6. Investigation of the recombination losses in a three-electrode cylindrical ionization chamber developed for gamma ray dosimetry of fission product activity

    International Nuclear Information System (INIS)

    Ahmad, N.; Matiullah

    1995-01-01

    A three-electrode ionization chamber has been designed and developed for the gamma ray dosimetry of fission product activity and reported elsewhere. In this paper, the (I, V) characteristics of the chamber filled, with argon gas at 1.24 MPa (180 psi) pressure, for fission product gamma rays from spent fuel have been studied. To do so, the chamber was irradiated with gamma rays using different numbers of (i.e. up to 4) spent fuel elements. The plateau region is reached above 1200 V and the detector operating voltage is found to be 2 kV. It is observed that in the plateau region the slope increases with an increase in the exposure rate. The (1/I, 1/V) and (I, 1/V 2 ) characteristic curves reveal the presence of the initial and volume recombination losses. The volume recombination losses are found to be smaller than the initial recombination losses. Both these losses increase with the increasing exposure rate but the increase in the volume recombination losses is slightly greater than that of the initial recombination losses. (orig.)

  7. A pilot study on production of G0 potato seed minitubers derived from growth-promoted by gamma-rays in vitro materials

    International Nuclear Information System (INIS)

    Nguyen Tien Thinh; Tran Thanh Han; Hoang Hung Tien; Le Viet Thanh; Nguyen Dinh Nhan

    2007-01-01

    A procedure for production of potato G 0 minitubers from in vitro materials like test-tube plantlets (CON), artificial seeds (HNT) and microtubers (CSB), which had been treated with 100 Rad of gamma-rays, was successfully established. The procedure started with producing low cost in vitro materials by growing them in semi-aseptic/non-aseptic culture conditions; treating them next with low doses of gamma-rays; then hydroponically cultivating the materials upon the following regime: culture density of 12x12 cm, nutritive hydroponical solution of CT1, and feeding frequency of T3 (3 times/week). Nearly 50,000 G 0 minitubers were produced by such a hydroponical way, and 30,000 of them were subsequently grown in field by local farmers. Observations of the above pilot production of the G 0 minitubers and of their field growing showed that the CSB was the most suitable in vitro starting stuff for forming G 0 minitubers, and that the growth-promotion effects of gamma-rays were not carried over to the field-growing stage of the G 0 minitubers. (author)

  8. Passive amplification of a fiber laser in a Fabry-Perot cavity: application to gamma-ray production by Compton backscattering

    International Nuclear Information System (INIS)

    Labaye, F.

    2012-01-01

    One of the critical points of the International Linear Collider (ILC) is the polarized positrons source. Without going through further explanation on the physical process of polarized positrons production, we point out that they are produced when circularly polarized gamma rays interact with mater. Thus, the critical point is the circularly polarized gamma-ray source. A technical solution for this source is the Compton backscattering and in the end, this thesis takes place in the framework for the design of a high average power laser systems enslaved to Fabry-Perot cavities for polarized gamma-ray production by Compton backscattering. In the first part, we present this thesis context, the Compton backscattering principle and the choice for an optical architecture based on a fiber laser and a Fabry-Perot cavity. We finish by enumerating several possible applications for Compton backscattering which shows that the work presented here might benefits from technology transfer through others research fields. In the second part, we present the different fiber laser architecture studied as well as the results obtained. In the third part, we remind the operating principle of a Fabry-Perot cavity and present the one used for our experiment as well as its specificities. In the fourth part, we address the Compton backscattering experiment which enables us to present the joint utilization of a fiber laser and a Fabry-Perot cavity in a particles accelerator to generate gamma rays for the first time to our knowledge. This experiment took place in the Accelerator Test Facility (ATF). The experimental apparatus as well as the results obtained are thus presented. In the end, we summarize the results presented in this manuscript and propose different evolution possibilities for the system in a general conclusion. (author)

  9. Method Validation for the Gamma-ray Spectrometric Determination of Natural Radioactive Nuclides in NORM Samples - Method Validation for the Gamma-ray Spectrometric Determination of Natural Radionuclides in raw materials and by-products

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Young-Yong; Lim, Jong-Myoung; Jang, Mee; Kim, Chang-Jong; Chung, Kun Ho; Kang, Mun Ja; Choi, Geun-Sik [Environmental Radioactivity Assessment Team, Korea Atomic Energy Research Institute, 111, Daedeok-daero 989, Yuseong, Daejeon, 305-353 (Korea, Republic of)

    2014-07-01

    It has established the 'Act on safety control of radioactive rays around living environment' in Korea, since 2011, to protect the public from natural occurring radioactive materials (NORM) and their by-products. The increasing concerns regarding the radioactivity of those materials therefore dictate many demands for the radioactive analysis for them. There are several methods to determine the concentration of natural radionuclides, such as {sup 235}U, {sup 238}U, {sup 226}Ra, {sup 232}Th, and so on, through a radiochemical analysis using an alpha spectrometer, mass spectrometer and liquid scintillation counter. However, gamma-ray spectroscopy still has an effect on the assessment of radioactive concentration for these nuclides and their progenies. To adapt a gamma spectrometer to the determination of natural radionuclides, the feasibility of their analysis methods should be first verified and validated with respect to accuracy and time and cost constraints. In general, one of the well-known processes in analyzing uranium with a gamma spectrometer is an indirect measurement using the secular equilibrium state with their progenies in a sample. This method, however, demands the time elapsed about 3 weeks to reach the equilibrium state between {sup 226}Ra and {sup 222}Rn and the sufficient integrity of a sample bottle to prevent the leakage of radon isotopes which is a form of noble gas. The simple and quick method is to directly measure a full energy absorption peak of 186.2 keV from {sup 226}Ra without the secular equilibrium state between {sup 226}Ra and {sup 222}Rn in the common sample bottle. However, this direct measurement also has difficulties about the interference with a full energy absorption peak of 185.7 keV from {sup 235}U. In this study, direct measurement with the interference correction technique, which uses several reference peaks for gamma-rays from {sup 235}U and {sup 234}Th, and indirect measurement, which means the identification of {sup

  10. Effect of Culture Conditions and Gamma Rays on Chitosan Production from Shrimp Shells by Certain Isolated Fungi

    International Nuclear Information System (INIS)

    Abd EI-Aziz, A.B.; Swialam, H.M.; Abd EI -Aziz, A.H.

    2009-01-01

    The obtained chitosan from shrimp shells waste used in the present work is compared with a standard chitosan. Six strains of the isolated fungi had the ability to attack the chitin namely: Candida tropicalis, Zygosaccharomyces rouxii, Candida guilliermondii, Trichoderma viride, Penicillium chrysogenum and Aspergillus niger. Z. rouxii and A. niger were the most active strains for decomposing chitin. The best culture conditions for chitosan production by the selected strains differed from one to another. Highest yield of chitosan was obtained after 96 h of incubation by A. niger (40.00 mg/g) in the basal medium followed by P. chrysogenum (38.20 mg/g). Optimum ph for chitosan production by C. tropicalis, Z. rouxii and T. viride was found to be 5.5, while ph 6.0 was the best for A. niger and C. guilliermondii. Meanwhile ph 5.0 was preferable for P. chrysogenllm. Regarding the carbon source, fructose as a sole carbon source in the medium was the best one for A. niger (92.58 mg/g) and T. viride (85.78 mg/g). C. tropicalis and Z. rouxii showed the highest chitosan production in the presence of sucrose (66.00 and 60.00 mg/g), whereas xylose was the best carbon for P. chrysogenum (62.50 mg/g). The selected strains were also differing in their nitrogen source requiring for production of chitosan. The present work confirmed that chitosan production by microorganisms is strongly dependent on the ph of the culture medium. The present data show that exposing the selected fungal strains to very low dose levels of gamma ray enhanced their productivity of chitosan and dry weight. The best environmental conditions of temperature degree, ph value and colloidal chitin concentration on chitinase activity produced by Z. rouxii were 30 degree C, 5.5 and 2% respectively, while they were 30 degree C, 6.0 and 1.5% for chitinase produced by A. niger in the same manner respectively

  11. Gamma ray astronomy

    International Nuclear Information System (INIS)

    Broomhead, Laurent.

    1980-01-01

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

  12. Application of gamma rays for increasing the productivity of xylitol from rice straw by candida teleprocess and candida guilieliermondii

    International Nuclear Information System (INIS)

    Abouzeid, A.A.; El-zawahry, Y.A.; El-mongy, T.M.; El-Fouly, M.Z.; Abd El-aziz, A.B.

    2005-01-01

    Irradiating the rice straw with high dose level of gamma rays (100-KGy) after being treated with diluted sulphuric acid increased the xylitol yields from the hydrolysates to 43.2 and 45.0 g/l out of 63.0 g/l xylose by Candida tropical and Candida guilliermondii, respectively. Meanwhile, irradiating C. tropical is and C. guilliermondii with low dose levels (0.25 and 0.5 KGy, respectively) before being inoculated in artificial medium, containing 150 g/l xylose, increased the yields of xylitol by the irradiated species. On the contrary, the produced xylitol was decreased sharply in case of isolates irradiated with 1 KGy especially C. tropical is, which showed less resistance to gamma rays recording. D 1 0, value 1.225 compared with 1.608 for C. guilliermondii. Sub-lethal dose of gamma rays (10 and 8 KGy) shrank C. guilliermondii cells and their sh,ape became irregular while C. tropical is cells formed small cottony fibres structure on the external surface of the cell wall, respectively. Meanwhile, lethal radiation doses-(l l and 9 KGy) caused deformation of the vegetative cells of both isolates. Many cells were enlarged, the cell walls of many others were ruptured and the internal contents were released outside the cells. Complete lyses of some cells-was also observed

  13. Gamma-ray bursts

    CERN Document Server

    Wijers, Ralph A M J; Woosley, Stan

    2012-01-01

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

  14. Gamma ray camera

    International Nuclear Information System (INIS)

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

    1979-01-01

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

  15. Sensitivity of Gamma-Ray Detectors to Polarization

    OpenAIRE

    Yadigaroglu, I. -A.

    1996-01-01

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

  16. Production of acetic acid from ethanol solution by acetobactor acetigenum and effect of gamma-ray irradiation on the bacteria

    International Nuclear Information System (INIS)

    Umar, J.M.; Matsuhashi, Shinpei; Hashimoto, Shoji.

    1996-03-01

    A preliminary study on fermentation of acetic acid by S. cerevisiae and A. acetigenum was carried out to obtain information to develop the effective utilization technology of agricultural liquid wastes. Aqueous solutions of glucose and/or ethanol were used as a model of agricultural liquid waste. The effect of gamma-ray irradiation on A. acetigenum for enhancement of the fermentation was also examined. In this study, irradiated A. acetigenum had activity to produce acetic acid even after loss the activity to grow. (author)

  17. Production of acetic from ethanol solution by acetobactor acetigenum and effect of gamma-ray irradiation on the bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Umar, J.M. [National Atomic Energy Agency, Jakarta (Indonesia). Center for Application of Isotopes and Radiation; Matsuhashi, Shinpei; Hashimoto, Shoji

    1996-03-01

    A preliminary study on fermentation of acetic acid by S. cerevisiae and A. acetigenum was carried out to obtain information to develop the effective utilization technology of agricultural liquid wastes. Aqueous solutions of glucose and/or ethanol were used as a model of agricultural liquid waste. The effect of gamma-ray irradiation on A. acetigenum for enhancement of the fermentation was also examined. In this study, irradiated A. acetigenum had activity to produce acetic acid even after loss the activity to grow. (author).

  18. Highlights of GeV Gamma-Ray Astronomy

    Science.gov (United States)

    Thompson, David J.

    2010-01-01

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

  19. Benchmark test of 14-MeV neutron-induced gamma-ray production data in JENDL-3.2 and FENDL/E-1.0 through analysis of the OKTAVIAN experiments

    International Nuclear Information System (INIS)

    Maekawa, F.; Oyama, F.

    1996-01-01

    Secondary gamma rays play an important role along with neutrons in influencing nuclear design parameters, such as nuclear heating, radiation dose, and material damage on the plasma-facing components, vacuum vessel, and superconducting magnets, of fusion devices. Because evaluated nuclear data libraries are used in the designs, one must examine the accuracy of secondary gamma-ray data in these libraries through benchmark tests of existing experiments. The validity of the data should be confirmed, or problems with the data should be pointed out through these benchmark tests to ensure the quality of the design. Here, gamma-ray production data of carbon, fluorine, aluminum, silicon, titanium, chromium, manganese, cobalt, copper, niobium, molybdenum, tungsten, and lead in JENDL-3.2 and FENDL/E-1.0 induced by 14-MeV neutrons are tested through benchmark analyses of leakage gamma-ray spectrum measurements conducted at the OKTAVIAN deuterium-tritium neutron source facility. The MCNP transport code is used along with the flagging method for detailed analyses of the spectra. As a result, several moderate problems are pointed out for secondary gamma-ray data of titanium, chromium, manganese, and lead in FENDL/E-1.0. Because no fatal errors are found, however, secondary gamma-ray data for the 13 elements in both libraries are reasonably well validated through these benchmark tests as far as 14-MeV neutron incidence is concerned

  20. Gamma-ray spectroscopy on irradiated fuel rods

    International Nuclear Information System (INIS)

    Terremoto, Luis Antonio Albiac

    2009-01-01

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

  1. Gamma ray emission from pulsars

    International Nuclear Information System (INIS)

    Salvati, M.; Massaro, E.

    1978-01-01

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

  2. Gamma ray spectroscopy monitoring method and apparatus

    Science.gov (United States)

    Stagg, William R; Policke, Timothy A

    2017-05-16

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

  3. Lunar based gamma ray astronomy

    International Nuclear Information System (INIS)

    Haymes, R.C.

    1985-01-01

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

  4. Dark gamma-ray bursts

    Science.gov (United States)

    Brdar, Vedran; Kopp, Joachim; Liu, Jia

    2017-03-01

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

  5. Observation of gamma-ray bursts with GINGA

    International Nuclear Information System (INIS)

    Murakami, Toshio; Fujii, Masami; Nishimura, Jun

    1989-01-01

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

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

    International Nuclear Information System (INIS)

    Cerutti, Benoit

    2010-01-01

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

  7. Estimation of the radiation strength, dose equivalent and mean gamma-ray energy form p+ sup 2 sup 3 sup 8 U fission products

    CERN Document Server

    Kawakami, H

    2003-01-01

    On 100 isobars from 72 to 171 mass number, the radiation strength, dose equivalent and mean gamma-ray energy from p+ sup 2 sup 3 sup 8 U fission products at Tandem accelerator facility were estimated on the basis of data of proton induced fission mass yield by T. Tsukada. In order to control radiation, the decay curves of radiation of each mass after irradiation were estimated and illustrated. These calculation results showed 1) the peak of p+ sup 2 sup 3 sup 8 U fission products is 101 and 133 mass number. 2) gamma-ray strength of target ion source immediately after irradiation is 3.12x10 sup 1 sup 1 (Radiation/s) when it repeated 4 cycles of UC sub 2 (2.6 g/cm sup 2) target radiated by 30 MeV and 3 mu A proton for 5 days and then cooled for 2 days. It decreased to 3.85x10 sup 1 sup 0 and 6.7x10 sup 9 (Radiation/s) after one day and two weeks cooling, respectively. 3) Total dose equivalent is 3.8x10 sup 4 (mu S/h) at 1 m distance without shield. 4) There are no problems on control the following isobars, beca...

  8. Gamma ray-induced mutants as a tool for the production and characterisation of monoclonal antibodies against HLA-alloantigens

    International Nuclear Information System (INIS)

    Spring, B.; Pawelec, G.; Ziegler, A.

    1986-01-01

    To simplify the screening procedure for murine monoclonal antibodies specific for polymorphic HLA determinants, spleen cells from a mouse immunized with the human cell line BJAB-B95.8.6 were fused with NS1 mouse myeloma cells, and hybridoma supernatants were screened for their reactivity on BJAB-B95.8.6 and two gamma ray-induced HLA-loss mutants of this line. The use of these HLA-loss mutants allowed the rapid identification of two new allospecific MOABs designated TU160 and TU161. Serological as well as biochemical studies revealed TU160 to be specific for HLA=A2, and TU161 for HLA-B13 molecules, respectively. Bo- th MOABs were determined to be antibodies of the IgG class and were able to precipitate their antigens from lysates of radioactively labeled cells. (author)

  9. X and gamma ray backgroud observations in Antarctic

    International Nuclear Information System (INIS)

    Jayanthi, U.B.

    1988-01-01

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

  10. Gamma ray energy tracking in GRETINA

    Science.gov (United States)

    Lee, I. Y.

    2011-10-01

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

  11. Gamma Ray Bursts - Observations

    Science.gov (United States)

    Gehrels, N.; Cannizzo, J. K.

    2010-01-01

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

  12. Dual-modality and dual-energy gamma ray densitometry of petroleum products using an artificial neural network

    International Nuclear Information System (INIS)

    Roshani, G.H.; Feghhi, S.A.H.; Setayeshi, S.

    2015-01-01

    The prediction of volume fractions in order to measure the multiphase flow rate is a very important issue and is the key parameter of multi-phase flow meters (MPFMs). Currently, the gamma ray attenuation technique is known as one of the most precise methods for obtaining volume fractions. The gamma ray attenuation technique is based on the mass attenuation coefficient, which is sensitive to density changes; density is sensitive in turn to temperature and pressure fluctuations. Therefore, MPFM efficiency depends strongly on environmental conditions. The conventional solution to this problem is the periodical recalibration of MPFMs, which is a demanding task. In this study, a method based on dual-modality densitometry and artificial intelligence (AI) is presented, which offers the advantage of the measurement of the oil–gas–water volume fractions independent of density changes. For this purpose, several experiments were carried out and used to validate simulated dual modality densitometry results. The reference density point was established at a temperature of 20 °C and pressure of 1 bar. To cover the full range of likely density fluctuations, four additional density sets were defined (at changes of ±4% and ±8% from the reference point). An annular regime with different percentages of oil, gas and water at different densities was simulated. Four features were extracted from the transmission and scattered detectors and were applied to the artificial neural network (ANN) as inputs. The input parameters included the "2"4"1Am full energy peak, "1"3"7Cs Compton edge, "1"3"7Cs full energy peak and total scattered count, and the outputs were the oil and air percentages. A multi-layer perceptron (MLP) neural network was used to predict the volume fraction independent of the oil and water density changes. The obtained results show that the proposed ANN model achieved good agreement with the real data, with an estimated root mean square error (RMSE) of less than 3

  13. Cross sections for production of 70 discrete-energy gamma rays created by neutron interactions with 56Fe for En to 40 MeV: Tabulated data

    International Nuclear Information System (INIS)

    Dickens, J.K.; Todd, J.H.; Larson, D.C.

    1990-09-01

    Inelastic and nonelastic neutron interactions with 56 Fe have been studied for incident neutron energies between 0.8 and 41 MeV. An iron sample isotopically enriched in the mass 56 isotope was used. Gamma rays representing 70 transitions among levels in residual nuclei were identified, and production cross sections were deduced. The reactions studied were 56 Fe(n,n') 56 Fe, 56 Fe(n,p) 56 Mn, 56 Fe(n,2n) 55 Fe, 56 Fe(n,d + n,np) 55 Mn, 56 Fe(n,t + n,nd + n,2np) 54 Mn, 56 Fe(n,α) 53 Cr, 56 Fe(n,nα) 52 Cr, and 56 Fe(n,3n) 54 Fe. Values obtained for production cross sections as functions of incident neutron energy are presented in tabular form. 38 refs., 7 figs., 12 tabs

  14. Gamma-ray sterilization of peat carriers for the production of legume seed inoculants (better production of soya bean)

    International Nuclear Information System (INIS)

    Vojinovic, Z.; Milicic, B.; Radak, B.

    1983-01-01

    In the present work the first Yugoslav experiments on the application of gamma radiation for the sterilization of peat in the production of inoculants for soya bean production are summarised and briefly discussed. A radiation dose of 50 kGy was used. The growth and survival of the soya bean nodule bacteria, Rhizobium japonicum, in the sterilized peat is shown. (U.K.)

  15. Found: A Galaxy's Missing Gamma Rays

    Science.gov (United States)

    Kohler, Susanna

    2016-04-01

    Recent reanalysis of data from the Fermi Gamma-ray Space Telescope has resulted in the first detection of high-energy gamma rays emitted from a nearby galaxy. This discovery reveals more about how supernovae interact with their environments.Colliding Supernova RemnantAfter a stellar explosion, the supernovas ejecta expand, eventually encountering the ambient interstellar medium. According to models, this generates a strong shock, and a fraction of the kinetic energy of the ejecta is transferred into cosmic rays high-energy radiation composed primarily of protons and atomic nuclei. Much is still unknown about this process, however. One open question is: what fraction of the supernovas explosion power goes into accelerating these cosmic rays?In theory, one way to answer this is by looking for gamma rays. In a starburst galaxy, the collision of the supernova-accelerated cosmic rays with the dense interstellar medium is predicted to produce high-energy gamma rays. That radiation should then escape the galaxy and be visible to us.Pass 8 to the RescueObservational tests of this model, however, have beenstumped by Arp 220. This nearby ultraluminous infrared galaxy is the product of a galaxy merger ~700 million years ago that fueled a frenzy of starbirth. Due to its dusty interior and extreme levels of star formation, Arp 220 has long been predicted to emit the gamma rays produced by supernova-accelerated cosmic rays. But though weve looked, gamma-ray emission has never been detected from this galaxy until now.In a recent study, a team of scientists led by Fang-Kun Peng (Nanjing University) reprocessed 7.5 years of Fermi observations using the new Pass 8 analysis software. The resulting increase in resolution revealed the first detection of GeV emission from Arp 220!Acceleration EfficiencyGamma-ray luminosity vs. total infrared luminosity for LAT-detected star-forming galaxies and Seyferts. Arp 220s luminosities are consistent with the scaling relation. [Peng et al. 2016

  16. Apparatus for gamma ray radiography

    International Nuclear Information System (INIS)

    Kobayashi, Masatoshi; Enomoto, Shigemasa; Oga, Hiroshi

    1979-01-01

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

  17. Applied gamma-ray spectrometry

    CERN Document Server

    Dams, R; Crouthamel, Carl E

    1970-01-01

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

  18. Gamma rays at airplane altitudes

    International Nuclear Information System (INIS)

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

    1990-01-01

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

  19. About cosmic gamma ray lines

    Science.gov (United States)

    Diehl, Roland

    2017-06-01

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

  20. Technical Aspect on Procedure of Gamma-Ray Pipeline Inspection

    International Nuclear Information System (INIS)

    Rasif Mohd Zain; Ainul Mardhiah Terry; Norman Shah Dahing

    2015-01-01

    The main problems happen in industrial pipelines are deposit build-up, blockage, corrosion and erosion. These effects will give a constraint in transporting refined products to process or production points and cause a major problem in production. One of the techniques to inspect the problem is using gamma-ray pipe scans. The principle of the technique is gamma-ray absorption technique. In this paper describes on the technical aspect to perform the pipe inspection in laboratory work. (author)

  1. Gamma-ray bursts from black hole accretion disks

    International Nuclear Information System (INIS)

    Strong, I.B.

    1975-01-01

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

  2. Cosmic gamma-ray burst

    International Nuclear Information System (INIS)

    Yamagami, Takamasa

    1985-01-01

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

  3. Compton Gamma-Ray Observatory

    Science.gov (United States)

    1991-01-01

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

  4. Measurement of 226Ra, 232Th and 40K radioactivity contents in by-product phosphogypsum from phosphate fertilizer industry using gamma ray spectrometric method

    International Nuclear Information System (INIS)

    Demirel, H.; Parmaksiz, A.; Vural, M.; Cakir, I.T.; Demircioglu, B.; Yucel, H.

    2004-01-01

    Full text: Phosphatic fertilizers are produced from the industrial processing of rock phosphate ores which are known to contain naturally occurring radionuclides such as 238 U and its daughter products. A high volume by-product known as phosphogypsum (PG) from the production of phosphoric acid and phosphate fertilizer causes serious storage and environmental problems in phosphoric acid industries. During the phosphoric acid production process, 226 Ra (t 1/2 =1600 y) ends up in PG which has chemical analogous to calcium element. Since the stockpiles of PG near the phosphatic fertilizer plants are huge amounts, the radioactivity contained in PG has measured in view of environmental radioactivity problem. In this work, the natural radioactivity in eighty PG samples taken from a stock near Samsun phosphoric fertilizer plant was measured by a high resolution gamma ray spectrometer. The mean activity of 226 Ra in PG samples has been found to be 546 Bq.kg -1 . However, the activities of 232 Th and 40 K measured in PG samples are negligibly small. In the presented paper, the gamma spectrometric method employed for this work is discussed and the radiological risk impact of radon gas emanation from 226 Ra mainly contained in PG, has been assessed

  5. In-plant measurements of gamma-ray transmissions for precise K-edge and passive assay of plutonium concentration and isotopic abundance in product solutions at the Tokai Reprocessing Plant

    International Nuclear Information System (INIS)

    Asakura, Y.; Kondo, I.; Masui, J.; Shoji, K.; Russo, P.A.; Hsue, S.T.; Sprinkle, J.K. Jr.; Johnson, S.S.

    1982-01-01

    A field test has been carried out for more than 2 years for determination of plutonium concentration by K-edge absorption densitometry and for determination of plutonium isotopic abundance by transmission-corrected passive gamma-ray spectrometry. This system was designed and built at Los Alamos National Laboratory and installed at the Tokai reprocessing plant of the Power Reactor and Nuclear Fuel Development Corporation as a part of the Tokai Advanced Safeguards Technology Exercise (TASTEX). For K-edge measurement of plutonium concentration, the transmissions at two discrete gamma-ray energies are measured using the 121.1- and 122.1-keV gamma rays from 75 Se and 57 Co. Intensities of the plutonium passive gamma rays in the energy regions between 38 and 51 keV and between 129 and 153 keV are used for determination of the isotopic abundances. More than 200 product solution samples have been measured in a timely fashion during these 2 years. The relative precisions and accuracies of the plutonium concentration measurement are shown to be within 0.6% (1 sigma) in these applications, and those for plutonium isotopic abundances are within 3% for 238 Pu, 0.4% for 239 Pu, 1.2% for 240 Pu, 1.3% for 241 Pu, and 7% for 242 Pu. The time required is 10 min for the concentration assay, 10 min for the isotopics assay, and about 15 min for handling procedures in the laboratory

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  7. Extragalactic Gamma-Ray Astrophysics

    CERN Multimedia

    CERN. Geneva

    2016-01-01

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

  8. Fissile interrogation using gamma rays from oxygen

    Science.gov (United States)

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

    2004-04-20

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

  9. Attenuation of the gamma rays in tissues

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  10. The Gamma-ray Sky with Fermi

    Science.gov (United States)

    Thompson, David

    2012-01-01

    Gamma rays reveal extreme, nonthermal conditions in the Universe. The Fermi Gamma-ray Space Telescope has been exploring the gamma-ray sky for more than four years, enabling a search for powerful transients like gamma-ray bursts, novae, solar flares, and flaring active galactic nuclei, as well as long-term studies including pulsars, binary systems, supernova remnants, and searches for predicted sources of gamma rays such as dark matter annihilation. Some results include a stringent limit on Lorentz invariance derived from a gamma-ray burst, unexpected gamma-ray variability from the Crab Nebula, a huge gamma-ray structure associated with the center of our galaxy, surprising behavior from some gamma-ray binary systems, and a possible constraint on some WIMP models for dark matter.

  11. Gamma-ray burst spectra

    International Nuclear Information System (INIS)

    Teegarden, B.J.

    1982-01-01

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

  12. Airborne gamma-ray spectrometry

    DEFF Research Database (Denmark)

    Hovgaard, Jens

    A new method - Noise Adjusted Singular Value Decomposition, NASVD - for processing gamma-ray spectra has been developed as part of a Ph.D. project. By using this technique one is able to decompose a large set of data - for example from airborne gamma-ray surveys - into a few spectral components....... By knowing the spectral components and their amplitudes in each of the measured spectra one is able to extract more information from the data than possible with the methods used otherwise....

  13. Gamma-ray Imaging Methods

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-10-05

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

  14. Measurement of the fission yields of selected prompt and decay fission product gamma-rays of spontaneously fissioning 252Cf and 244Cm

    International Nuclear Information System (INIS)

    Reber, E.L.; Gehrke, R.J.; Aryaeinejad, R.; Hartwell, J.K.

    2005-01-01

    Gamma-ray spectrometry measurements have been made of the fission yields of selected γ -rays emitted by the spontaneously fissioning isotopes 252 Cf and 244 Cm. The measured γ-rays were selected based on their relative abundance in the spectrum and their freedom from interference or, in a few instances, ease of interference correction. From these data and the cumulative and independent yield data of England and Rider, those γ-rays that are primarily produced by radioactive decay, as opposed to direct yield, were converted into the decays per spontaneous fission expressed in percent and compared to cumulative yield values of England and Rider. For those γ-rays whose production is dominated by direct (independent) yield, the ratio of γ-rays per spontaneous fission is reported. The γ-ray yield can be compared to the independent yield values of England and Rider when 100% of the direct feeding passes through the γ-ray. In those cases where both cumulative and independent yields contribute to the observed γ-ray emission rate, a direct comparison is not possible but a method to quantify the contribution from each is proposed. (author)

  15. Gamma-Ray Pulsars Models and Predictions

    CERN Document Server

    Harding, A K

    2001-01-01

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

  16. Optical observations of Gamma-Ray Bursts

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  17. The Gamma-ray Universe through Fermi

    Science.gov (United States)

    Thompson, David J.

    2012-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-12-31

    Ion Cyclotron Resonant Heating (ICRH) that is tuned to minority fuel ions can induce an energy diffusion of the heated species and create high energy tail temperatures of {approx} 1 MeV. The most energetic of these accelerated minority ions can undergo nuclear reactions with impurity Be and C that produces {gamma}-ray emission from the decay of the excited product nuclei. This RF-induced {gamma}-ray emission has been recorded using the JET neutron emission profile diagnostic which is capable of distinguishing neutrons and {gamma}-rays. Appropriate data processing has enabled the RF-induced {gamma}-ray emission signals to be isolated from the {gamma}-ray emission signals associated with neutron interactions in the material surrounding the profile monitor. The 2-d {gamma}-ray emission profiles show that virtually all the radiation originates from the low field side of the RF resonance layer, as expected from RF-induced pitch angle diffusion. The emission profiles indicate the presence of a small population of resonant {sup 3}He ions that possess orbits lying near the passing-trapped boundary. (author) 6 refs., 4 figs.

  19. Fission rates measured using high-energy gamma-rays from short half-life fission products in fresh and spent nuclear fuel

    International Nuclear Information System (INIS)

    Kroehnert, H.

    2011-02-01

    In recent years, higher discharge burn-ups and initial fuel enrichments have led to more and more heterogeneous core configurations in light water reactors (LWRs), especially at the beginning of cycle when fresh fuel assemblies are loaded next to highly burnt ones. As this trend is expected to continue in the future, the Paul Scherrer Institute has, in collaboration with the Swiss Association of Nuclear Utilities, swissnuclear, launched the experimental programme LIFE(at)PROTEUS. The LIFE(at)PROTEUS programme aims to better characterise interfaces between burnt and fresh UO 2 fuel assemblies in modern LWRs. Thereby, a novel experimental database is to be made available for enabling the validation of neutronics calculations of strongly heterogeneous LWR core configurations. During the programme, mixed fresh and highly burnt UO 2 fuel lattices will be investigated in the zero-power research reactor PROTEUS. One of the main types of investigations will be to irradiate the fuel in PROTEUS and measure the resulting fission rate distributions across the interface between fresh and burnt fuel zones. The measurement of fission rates in burnt fuel re-irradiated in a zero-power reactor requires, however, the development of new experimental techniques which are able to discriminate against the high intrinsic activity of the fuel. The principal goal of the present research work has been to develop such a new measurement technique. The selected approach is based on the detection of high-energy gamma-ray lines above the intrinsic background (i.e. above 2200 keV), which are emitted by short-lived fission products freshly created in the fuel. The fission products 88 Kr, 142 La, 138 Cs, 84 Br, 89 Rb, 95 Y, 90m Rb and 90 Rb, with half-lives between 2.6 min and 2.8 h, have been identified as potential candidates. During the present research work, the gamma-ray activity of short-lived fission products has, for the first time, been measured and quantitatively evaluated for re

  20. Fission rates measured using high-energy gamma-rays from short half-life fission products in fresh and spent nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Kroehnert, H.

    2011-02-15

    In recent years, higher discharge burn-ups and initial fuel enrichments have led to more and more heterogeneous core configurations in light water reactors (LWRs), especially at the beginning of cycle when fresh fuel assemblies are loaded next to highly burnt ones. As this trend is expected to continue in the future, the Paul Scherrer Institute has, in collaboration with the Swiss Association of Nuclear Utilities, swissnuclear, launched the experimental programme LIFE(at)PROTEUS. The LIFE(at)PROTEUS programme aims to better characterise interfaces between burnt and fresh UO{sub 2} fuel assemblies in modern LWRs. Thereby, a novel experimental database is to be made available for enabling the validation of neutronics calculations of strongly heterogeneous LWR core configurations. During the programme, mixed fresh and highly burnt UO{sub 2} fuel lattices will be investigated in the zero-power research reactor PROTEUS. One of the main types of investigations will be to irradiate the fuel in PROTEUS and measure the resulting fission rate distributions across the interface between fresh and burnt fuel zones. The measurement of fission rates in burnt fuel re-irradiated in a zero-power reactor requires, however, the development of new experimental techniques which are able to discriminate against the high intrinsic activity of the fuel. The principal goal of the present research work has been to develop such a new measurement technique. The selected approach is based on the detection of high-energy gamma-ray lines above the intrinsic background (i.e. above 2200 keV), which are emitted by short-lived fission products freshly created in the fuel. The fission products {sup 88}Kr, {sup 142}La, {sup 138}Cs, {sup 84}Br, {sup 89}Rb, {sup 95}Y, {sup 90m}Rb and {sup 90}Rb, with half-lives between 2.6 min and 2.8 h, have been identified as potential candidates. During the present research work, the gamma-ray activity of short-lived fission products has, for the first time, been

  1. Spiked environmental matrix for use as a reference material for gamma-ray spectrometry: Production and homogeneity test

    International Nuclear Information System (INIS)

    Sobiech-Matura, K.; Máté, B.; Altzitzoglou, T.

    2016-01-01

    The application of a spiking method for reference material production and its utilisation for a food matrix is presented. The raw rice powder was tested by means of γ-ray spectrometry and spiked with a "1"3"7Cs solution. The spiked material was mixed and tested for homogeneity. The future use of the rice powder reference material after the entire characterisation cycle will be for γ-ray spectrometry method validation. - Highlights: • Spiking blank substance with a traceable radioactive solution • Spiked reference material for γ-ray emitting radionuclides in food matrix • Results of the homogeneity tests are presented

  2. Kβ/ Kα intensity ratios for X-ray production in 3d metals by gamma-rays and protons

    Science.gov (United States)

    Bhuinya, C. R.; Padhi, H. C.

    1994-04-01

    Systematic measurements of Kβ/ Kα intensity ratios for X-ray production in 3d metals have been carried out using γ-ray and fast proton ionization methods. The measured ratios from proton ionization experiments indicate production of multivacancies in the L shell giving rise to higher Kβ/ Kα ratios compared to the present γRF results and 2 MeV proton ionization results of Perujo et al. [Perujo A., Maxwell J. A., Teesdale W. J. and Cambell J. L. (1987) J. Phys. B: Atom. Molec. Phys.20, 4973]. This is consistent with the SCA model calculation which gives increased simultaneous K- and L-shell ionization at 4 MeV. The present results from γRF experiments are in close agreement with the 2 MeV proton ionization results of Perujo et al. (1987) and also with the theoretical calculation of jankowski and Polasik [Jankowski K. and Polasik M. (1989) J. Phys. B: Atom. Molec. Optic. Phys. 22, 2369] but the theoretical results of Scofield [Scofield J. H. (1974a) Atom. Data Nucl. Data Tables14, 12] are somewhat higher.

  3. Multifrequency Observations of Gamma-Ray Burst

    OpenAIRE

    Greiner, J.

    1995-01-01

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

  4. Stellar Sources of Gamma-ray Bursts

    OpenAIRE

    Luchkov, B. I.

    2011-01-01

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

  5. Gamma-rays from deep inelastic collisions

    International Nuclear Information System (INIS)

    Stephens, F.S.

    1981-01-01

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

  6. Application of gamma-ray spectroscopy to the differentiation between mobile and deposited fission products in pipes

    International Nuclear Information System (INIS)

    Packer, T.W.; Armitage, B.H.

    1990-08-01

    A method has been developed to differentiate between material flowing in pipes and deposited on the pipe walls. This has been applied to a study of fission product release from irradiated fuel under severe accident conditions. A collimation arrangement has been examined which provides good discrimination between gamma- radiation arising from flowing gases/aerosols and from stationary deposits. A systematic examination has been made of gamma- radiation obtained from gases and deposits in pipes of different diameter for a number of collimator configurations. A system of calibration has been developed based on Monte-Carlo modelling which has been found to be in broad agreement with measured values. This knowledge has been applied to the data obtained in a real-time measurement undertaken on the FALCON reactor safety facility at AEA Technology, Winfrith

  7. Determination of gamma-ray exposure rate from short-lived fission products under criticality accident conditions

    International Nuclear Information System (INIS)

    Yanagisawa, Hiroshi; Ohno, Akio; Aizawa, Eijyu

    2002-01-01

    For the assessment of γ-ray doses from short-lived fission products (FPs) under criticality accident conditions, γ-ray exposure rates varying with time were experimentally determined in the Transient Experiment Critical Facility (TRACY). The data were obtained by reactivity insertion in the range of 1.50 to 2.93$. It was clarified from the experiments that the contribution of γ-ray from short-lived FPs to total exposure during the experiments was evaluated to be 15 to 17%. Hence, the contribution cannot be neglected for the assessment of γ-ray doses under criticality accident conditions. Computational analyses also indicated that γ-ray exposure rates from short-lived FPs calculated with the Monte Carlo code, MCNP4B, and photon sources based on the latest FP decay data, the JENDL FP Decay Data File 2000, well agreed with the experimental results. The exposure rates were, however, extremely underestimated when the photon sources were obtained by the ORIGEN2 code. The underestimation is due to lack of energy-dependent photon emission data for major short-lived FP nuclides in the photon database attached to the ORIGEN2 code. It was also confirmed that the underestimation arose in 1,000 or less of time lapse after an initial power burst. (author)

  8. Airborne gamma ray spectrometer surveying

    International Nuclear Information System (INIS)

    1991-01-01

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

  9. Compton suppression gamma ray spectrometry

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  10. Inverse Compton gamma-rays from pulsars

    International Nuclear Information System (INIS)

    Morini, M.

    1983-01-01

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

  11. CAMAC gamma ray scanning system

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  12. THE NEUTRAL INTERSTELLAR GAS TOWARD SNR W44: CANDIDATES FOR TARGET PROTONS IN HADRONIC {gamma}-RAY PRODUCTION IN A MIDDLE-AGED SUPERNOVA REMNANT

    Energy Technology Data Exchange (ETDEWEB)

    Yoshiike, S.; Fukuda, T.; Sano, H.; Ohama, A.; Moribe, N.; Torii, K.; Hayakawa, T.; Okuda, T.; Yamamoto, H.; Mizuno, N.; Onishi, T.; Fukui, Y. [Department of Physics and Astrophysics, Nagoya University, Nagoya, Aichi 464-8602 (Japan); Tajima, H.; Maezawa, H.; Mizuno, A. [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Aichi 464-8601 (Japan); Nishimura, A.; Kimura, K.; Ogawa, H. [Department of Astrophysics, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Giuliani, A. [INAF-IASF Milano, via E. Bassini 15, I-20133 Milano (Italy); Koo, B.-C., E-mail: yoshiike@a.phys.nagoya-u.ac.jp [Seoul National University, Seoul 151-742 (Korea, Republic of)

    2013-05-10

    We present an analysis of the interstellar medium (ISM) toward the {gamma}-ray supernova remnant (SNR) W44. We used NANTEN2 {sup 12}CO(J = 2-1) and {sup 12}CO(J = 1-0) data and Arecibo H I data in order to identify the molecular and atomic gas in the SNR. We confirmed that the molecular gas is located in the SNR shell with a primary peak toward the eastern edge of the shell. We newly identified high-excitation molecular gas along the eastern shell of the SNR in addition to the high-excitation broad gas previously observed inside the shell; the line intensity ratio between the {sup 12}CO(J = 2-1) and {sup 12}CO(J = 1-0) transitions in these regions is greater than {approx}1.0, suggesting a kinetic temperature of 30 K or higher, which is most likely due to heating by shock interaction. By comparing the ISM with {gamma}-rays, we find that target protons of hadronic origin are dominated by molecular protons of average density around 200 cm{sup -3}, where the possible contribution of atomic protons is 10% or less. This average density is consistent with the recent discovery of the low-energy {gamma}-rays suppressed in 50 MeV-10 GeV as observed with AGILE and Fermi. The {gamma}-ray spectrum differs from place to place in the SNR, suggesting that the cosmic-ray (CR) proton spectrum significantly changes within the middle-aged SNR perhaps due to the energy-dependent escape of CR protons from the acceleration site. We finally derive a total CR proton energy of {approx}10{sup 49} erg, consistent with the SN origin of the majority of the CRs in the Galaxy.

  13. Gamma-ray production cross-sections for the interactions of 14.9 MeV neutrons with Si, Cu, Nb and Pb

    International Nuclear Information System (INIS)

    Fan Guoying

    1991-12-01

    Gamma rays produced in the interactions of 14.9 MeV neutrons with Si, Cu, Nb and Pb targets were studied. The neutron beam was produced with the T(d,n)He reaction using 300 KeV Cockroft-Walton accelerator. Absolute neutron flux was determined by the associated particle technique. The time-of-flight technique was used to reduce the background. The FWHM of neutron pulses was 1.5 ns. A Ge(Li) detector was used for gamma-ray detection. 39 gamma lines for Si, 39 gamma lines for Cu, 79 for Nb and 39 for Pb were detected. Most of these gamma rays were emitted in (n,γ), (n,n') and (n,2n) reactions. The measurements were made at 40 deg. C, 55 deg. C, 125 deg. C and 140 deg. C relative to the incident neutron beam. The results are presented in the form of the data tables. 9 refs, 11 figs, 19 tabs

  14. Space instrumentation for gamma-ray astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Teegarden, B.J

    1999-02-11

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

  15. Space instrumentation for gamma-ray astronomy

    International Nuclear Information System (INIS)

    Teegarden, B.J.

    1999-01-01

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

  16. Gamma rays from pulsar outer gaps

    International Nuclear Information System (INIS)

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

    1993-01-01

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

  17. Study of a high finesse four mirrors Fabry Perot cavity for X-rays and Gamma rays production by laser-electron Compton scattering

    International Nuclear Information System (INIS)

    Fedala, Y.

    2008-10-01

    The main goal of this thesis is the study and design of a high finesse Fabry Perot cavity to amplify a laser beam in order to achieve power gains ranging from 10 4 to 10 5 . This cavity is dedicated to the production of intense and monochromatic X-ray for medical applications (medical RADIOTHOMX ring) and gamma rays for a Compton based polarized positron source by Compton scattering of a high power laser beam and electron beam. To increase the brightness of the Compton interaction at the collision points, it is essential to have not only a high power laser beam but also very small laser beam radii at the interaction points. To achieve such performances, 2 scenarios are possible: a concentric 2 mirrors cavity which is mechanically unstable or a 4 mirrors cavity more complex but more stable. We tested numerically mechanical stability and stability of Eigen modes polarization of various planar and non-planar geometries of 4 mirrors cavities. Experimentally, we have developed a four mirrors tetrahedral 'bow-tie' cavity; radii of the order of 20 microns were made. The Eigen modes of such a cavity, in both planar and non planar geometries, were measured and compared with the numerical results. A good agreement was observed. In a second time, the impact of Compton interaction on the transverse dynamics, in the case of the polarized positrons source, and the longitudinal dynamic, in the case of the medical ring of the electron beam was studied. Compton scattering causes energy loss and induces an additional dispersion of energy in electron beam. For the polarized positrons source, 10 collision points are planned. The transport line has been determined and the modelling of the Compton interaction effect with a simple matrix calculation was made. For the medical ring, Compton scattering causes bunch lengthening and the increase of energy dispersion which are to influence the produced X-ray flux. A study of the longitudinal dynamics of the electron beam in the ring was

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

    Science.gov (United States)

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

    2018-01-01

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

  19. Gamma-ray pulsars: Emission zones and viewing geometries

    Science.gov (United States)

    Romani, Roger W.; Yadigaroglu, I.-A.

    1995-01-01

    There are now a half-dozen young pulsars detected in high-energy photons by the Compton Gamma-Ray Observatory (CGRO), showing a variety of emission efficiencies and pulse profiles. We present here a calculation of the pattern of high-energy emission on the sky in a model which posits gamma-ray production by charge-depleted gaps in the outer magnetosphere. This model accounts for the radio to gamma-ray pulse offsets of the known pulsars, as well as the shape of the high-energy pulse profiles. We also show that about one-third of emitting young radio pulsars will not be detected due to beaming effects, while approximately 2.5 times the number of radio-selected gamma-ray pulsars will be viewed only high energies. Finally we compute the polarization angle variation and find that the previously misunderstood optical polarization sweep of the Crab pulsar arises naturally in this picture. These results strongly support an outer magnetosphere location for the gamma-ray emission.

  20. Coincidence gamma-ray spectrometry

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  1. Cosmic gamma-ray bursts

    International Nuclear Information System (INIS)

    Hurley, K.

    1989-01-01

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

  2. Gamma-ray burst polarimeter (GAP)

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  3. Gamma-Ray Astronomy Technology Needs

    Science.gov (United States)

    Gehrels, N.; Cannizzo, J. K.

    2012-01-01

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

  4. Gamma-ray burst models.

    Science.gov (United States)

    King, Andrew

    2007-05-15

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

  5. Laser Compton Scattering Gamma Ray Induced Photo-Trasmutation

    CERN Document Server

    Li, Dazhi

    2004-01-01

    High brightness beams of gamma rays produced with laser Compton scattering have the potential to realize photo-transmutation through (γ,n) reaction, implying an efficient method to dispose long-lived fission products. Preliminary investigations have been carried out in understanding the feasibility of development of a transmutation facility to repose nuclear waste. A laser Compton scattering experimental setup based on a storage ring started to generate gamma-ray beams for studying the coupling of gamma photons and nuclear giant resonance. This paper demonstrates the dependency of nuclear transmutation efficiency on target dimensions and gamma ray features. 197Au sample was adopted in our experiment, and experimental results correspond to the theoretical estimations.

  6. Relativistic motion in gamma-ray bursts

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  7. Radio Observations of Gamma-ray Novae

    Science.gov (United States)

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

    2014-01-01

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

  8. $\\gamma$-Ray Pulsars: Emission Zones and Viewing Geometries

    OpenAIRE

    Romani, Roger W.; Yadigaroglu, I. -A.

    1994-01-01

    There are now a half dozen young pulsars detected in high energy photons by the Compton GRO, showing a variety of emission efficiencies and pulse profiles. We present here a calculation of the pattern of high energy emission on the sky in a model which posits $\\gamma$-ray production by charge depleted gaps in the outer magnetosphere. This model accounts for the radio to $\\gamma$-ray pulse offsets of the known pulsars, as well as the shape of the high energy pulse profiles. We also show that $...

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

    OpenAIRE

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

    2012-01-01

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

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

    Science.gov (United States)

    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

    2008-04-15

    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.

  11. New lithology compensated capture gamma ray system

    International Nuclear Information System (INIS)

    Peatross, R.F.

    1976-01-01

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

  12. Feasibility study of gamma-ray medical radiography

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  13. Polarised and tagged gamma-ray Ladon beams

    Energy Technology Data Exchange (ETDEWEB)

    Babusci, D [Istituto Nazionale di Fisica Nucleare, Frascati (Italy). Lab. Nazionale di Frascati

    1995-11-01

    The production of polarized and tagged gamma-ray beams by the backscattering of Laser light on the relativistic electrons circulating in storage rings is discussed. the main characteristic and the experimental results of the Ladon and LEGS beams are presented. The Graal beam is introduced.

  14. Polarised and tagged gamma-ray Ladon beams

    International Nuclear Information System (INIS)

    Babusci, D.

    1995-11-01

    The production of polarized and tagged gamma-ray beams by the backscattering of Laser light on the relativistic electrons circulating in storage rings is discussed. the main characteristic and the experimental results of the Ladon and LEGS beams are presented. The Graal beam is introduced

  15. Egg weight and gamma-rays effects. Pt. 3

    International Nuclear Information System (INIS)

    Shebaita, M.K.; Kamar, G.A.R.; Salem, M.A.I.; Ezzat, I.E.

    1979-01-01

    A total of 180 roosters at 36 weeks old were used to find out the effects of egg weight and gamma-rays on blood, carcass and meat analysis. The data revealed that radiation induced anemia and increased meat production. The different parameters under study were discussed in details. (orig.) [de

  16. Handbook on Mobile Gamma-ray Spectrometry

    DEFF Research Database (Denmark)

    Aage, Helle Karina; Korsbech, Uffe C C

    2003-01-01

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

  17. Gamma-Ray Interactions for Reachback Analysts

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-02

    This presentation is a part of the DHS LSS spectroscopy training course and presents an overview of the following concepts: identification and measurement of gamma rays; use of gamma counts and energies in research. Understanding the basic physics of how gamma rays interact with matter can clarify how certain features in a spectrum were produced.

  18. Prompt gamma-ray activation analysis (PGAA)

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-11-01

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

  19. Prompt gamma-ray activation analysis (PGAA)

    International Nuclear Information System (INIS)

    Kern, J.

    1996-01-01

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

  20. A high energy gamma ray astronomy experiment

    International Nuclear Information System (INIS)

    Hofstadter, R.

    1988-01-01

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

  1. Intercomparison of gamma ray analysis software packages

    International Nuclear Information System (INIS)

    1998-04-01

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

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

    Science.gov (United States)

    Chadwick, Paula M

    2007-05-15

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

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

    International Nuclear Information System (INIS)

    Dingus, Brenda L.

    2001-01-01

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

  4. High dose gamma-ray standard

    International Nuclear Information System (INIS)

    Macrin, R.; Moraru, R.

    1999-01-01

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

  5. Operating experience with gamma ray irradiators

    International Nuclear Information System (INIS)

    Fraser, F.M.; Ouwerkerk, T.

    1980-01-01

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

  6. Gamma-Rays from Galactic Compact Sources

    Science.gov (United States)

    Kaaret, Philip

    2007-04-01

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

  7. Gamma-ray measurements at the WNR white neutron source

    International Nuclear Information System (INIS)

    Nelson, R.O.; Wender, S.A.; Mayo, D.R.

    1994-01-01

    Photon production data have been acquired in the incident neutron energy range, 1 n γ 56 Fe, and 207,208 Pb. These data are useful both for testing nuclear reaction models at intermediate energies and for numerous applied purposes. BGO detectors do not have the good energy resolution of Ge detectors, but have much greater detection efficiency for gamma rays with energies greater than a few MeV. We have used an array of 5 BGO detectors to measure cross sections and angular distributions for photon production from C and N. A large, well-shielded BGO detector has been used to measure fast neutron capture in the giant resonance region with a maximum gamma-ray energy of 52 MeV. We present results of our study of the isovector giant quadrupole resonance in 41 Ca via these capture measurements. Recent measurements of inclusive photon spectra from our neutron proton Bremsstrahlung experiment have been made using a gamma-ray telescope to detect gamma-rays in the energy range, 40 γ < 300 MeV. This detector is briefly described. The advantages and disadvantages of these detector systems are discussed using examples from our measurements. The status of current measurements is presented

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

    International Nuclear Information System (INIS)

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

    2001-01-01

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

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

    Science.gov (United States)

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

    1990-01-01

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

  10. Future prospects for. gamma. -ray astronomy

    Energy Technology Data Exchange (ETDEWEB)

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

    1981-06-30

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

  11. Characterizing the source properties of terrestrial gamma ray flashes

    Science.gov (United States)

    Dwyer, Joseph R.; Liu, Ningyu; Eric Grove, J.; Rassoul, Hamid; Smith, David M.

    2017-08-01

    Monte Carlo simulations are used to determine source properties of terrestrial gamma ray flashes (TGFs) as a function of atmospheric column depth and beaming geometry. The total mass per unit area traversed by all the runaway electrons (i.e., the total grammage) during a TGF, Ξ, is introduced, defined to be the total distance traveled by all the runaway electrons along the electric field lines multiplied by the local air mass density along their paths. It is shown that key properties of TGFs may be directly calculated from Ξ and its time derivative, including the gamma ray emission rate, the current moment, and the optical power of the TGF. For the calculations presented in this paper, a standard TGF gamma ray fluence, F0 = 0.1 cm-2 above 100 keV for a spacecraft altitude of 500 km, and a standard total grammage, Ξ0 = 1018 g/cm2, are introduced, and results are presented in terms of these values. In particular, the current moments caused by the runaway electrons and their accompanying ionization are found for a standard TGF fluence, as a function of source altitude and beaming geometry, allowing a direct comparison between the gamma rays measured in low-Earth orbit and the VLF-LF radio frequency emissions recorded on the ground. Such comparisons should help test and constrain TGF models and help identify the roles of lightning leaders and streamers in the production of TGFs.

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

    International Nuclear Information System (INIS)

    Gabici, Stefano

    2011-01-01

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

  13. On Gamma-Ray Bursts

    CERN Document Server

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

    2008-01-01

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

  14. Gamma ray shielding: a web based interactive program

    International Nuclear Information System (INIS)

    Subbaiah, K.V.; Senthi Kumar, C.; Sarangapani, R.

    2005-01-01

    A web based interactive computing program is developed using java for quick assessment of Gamma Ray shielding problems. The program addresses usually encountered source geometries like POINT, LINE, CYLINDRICAL, ANNULAR, SPHERICAL, BOX, followed by 'SLAB' shield configurations. The calculation is based on point kernel technique. The source points are randomly sampled within the source volume. From each source point, optical path traversed in the source and shield media up to the detector location is estimated to calculate geometrical and material attenuations, and then corresponding buildup factor is obtained, which accounts for scattered contribution. Finally, the dose rate for entire source is obtained by summing over all sampled points. The application allows the user to select one of the seven regular geometrical bodies and provision exist to give source details such as emission energies, intensities, physical dimensions and material composition. Similar provision is provided to specify shield slab details. To aid the user, atomic numbers, densities, standard build factor materials and isotope list with respective emission energies and intensity for ready reference are given in dropdown combo boxes. Typical results obtained from this program are validated against existing point kernel gamma ray shielding codes. Additional facility is provided to compute fission product gamma ray source strengths based on the fuel type, burn up and cooling time. Plots of Fission product gamma ray source strengths, Gamma ray cross-sections and buildup factors can be optionally obtained, which enable the user to draw inference on the computed results. It is expected that this tool will be handy to all health physicists and radiological safety officers as it will be available on the internet. (author)

  15. Spectra of gamma-ray bursts at high energies

    International Nuclear Information System (INIS)

    Matz, S.M.

    1986-01-01

    Between 1980 February and 1983 August the Gamma-Ray Spectrometer (GRS) on the Solar Maximum Mission satellite (SMM) observed 71 gamma-ray bursts. These events form a representative subset of the class of classical gamma-ray bursts. Since their discovery more than 15 years ago, hundreds of gamma-ray bursts have been detected; however, most observations have been limited to an energy range of roughly 30 keV-1 MeV. The large sensitive area and spectral range of the GRS allow, for the first time, an investigation of the high energy (>1 MeV) behavior of a substantial number of gamma-ray bursts. It is found that high-energy emission is seen in a large fraction of all events and that the data are consistent with all bursts emitting to at least 5 MeV with no cut-offs. Further, no burst spectrum measured by GRS has a clear high-energy cut-off. The high-energy emission can be a significant part of the total burst energy on the average about 30% of the observed energy above 30 keV is contained in the >1 MeV photons. The fact that the observations are consistent with the presence of high-energy emission in all events implies a limit on the preferential beaming of high-energy photons, from any mechanism. Single-photon pair-production in a strong magnetic field produces such beaming; assuming that the low-energy emission is isotropic, the data imply an upper limit of 1 x 10 12 G on the typical magnetic field at burst radiation sites

  16. Neutron detection gamma ray sensitivity criteria

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  17. Gamma-Ray Pulsar Studies With GLAST

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, D.J.; /NASA, Goddard

    2011-11-23

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

  18. Processing of gamma-ray spectrometric logs

    International Nuclear Information System (INIS)

    Umiastowski, K.; Dumesnil, P.

    1984-10-01

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

  19. Gamma ray astronomy with COS-B

    International Nuclear Information System (INIS)

    Swanenburg, B.N.

    1981-01-01

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

  20. Thermal neutron capture gamma-rays

    International Nuclear Information System (INIS)

    Tuli, J.K.

    1983-01-01

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

  1. Gamma ray auto absorption correction evaluation methodology

    International Nuclear Information System (INIS)

    Gugiu, Daniela; Roth, Csaba; Ghinescu, Alecse

    2010-01-01

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

  2. Observations of gamma-ray bursts

    International Nuclear Information System (INIS)

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

    1975-01-01

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

  3. Gamma-rays from decaying dark matter

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-10-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1977-03-31

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

  5. Magic gamma rays, extra-atmospheric source

    International Nuclear Information System (INIS)

    Bolufer, P.

    2010-01-01

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

  6. Studies on the influences of. gamma. -ray irradiation upon food additives, (6). Radiolysis of monosodium glutamate due to. gamma. -ray irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, M [Shimonoseki Univ. of Fisheries, Yamaguchi (Japan); Gohya, Y; Ishio, S

    1981-08-01

    The effect of ..gamma..-ray irradiation on monosodium glutamate (MSG) in aqueous solution and in ''kamaboko'' was investigated to evaluate the rate of decomposition of MSG and to elucidate the safety of the decomposed products, under the concentration of 106.9 mmol/l aqueous solution and 1% content of MSG in ''kamaboko''. In aqueous solution, MSG was decomposed by ..gamma..-ray irradiation, and G value was estimated to be 1.24. The decomposition of MSG resulted from deamination reaction was estimated to be 40% of the total decomposition. Glutamic acid content decreased as the dose of ..gamma..-ray increased in MSG-enriched ''kamaboko'', while it increased as the dose of ..gamma..-ray increased in MSG-free ''kamaboko''. Glutamic acid was liberated from the protein in ''kamaboko'', therefore the apparent decomposition rate of MSG in ''kamaboko'' was regarded as lower than actual.

  7. Gamma Ray Bursts-Afterglows and Counterparts

    Science.gov (United States)

    Fishman, Gerald J

    1998-01-01

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

  8. High energy particles from {gamma}-ray bursts

    Energy Technology Data Exchange (ETDEWEB)

    Waxman, E [Weizmann Institute of Science, Rehovot (Israel)

    2001-11-15

    A review is presented of the fireball model of {gamma}-ray bursts (GRBs), and of the production in GRB fireballs of high energy protons and neutrinos. Constraints imposed on the model by recent afterglow observations, which support the association of GRB and ultra-high energy cosmic-ray (UHECR) sources, are discussed. Predictions of the GRB model for UHECR production, which can be tested with planned large area UHECR detectors and with planned high energy neutrino telescopes, are reviewed. (author)

  9. MESSENGER E/V/H GRNS 3 GAMMA RAY SPECTROMETER CALIBDATA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract ======== This data set consists of the MESSENGER GRS calibrated observations (CDRs) and the reduced data product (RDR). The GRS experiment is a gamma ray...

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

    International Nuclear Information System (INIS)

    Carbonari, A.W.

    1983-01-01

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

  11. Decaying vs. annihilating dark matter in light of a tentative gamma-ray line

    International Nuclear Information System (INIS)

    Buchmüller, Wilfried; Garny, Mathias

    2012-01-01

    Recently reported tentative evidence for a gamma-ray line in the Fermi-LAT data is of great potential interest for identifying the nature of dark matter. We compare the implications for decaying and annihilating dark matter taking the constraints from continuum gamma-rays, antiproton flux and morphology of the excess into account. We find that higgsino and wino dark matter are excluded, also for nonthermal production. Generically, the continuum gamma-ray flux severely constrains annihilating dark matter. Consistency of decaying dark matter with the spatial distribution of the Fermi-LAT excess would require an enhancement of the dark matter density near the Galactic center

  12. Computer-controlled gamma-ray scanner for irradiated reactor fuel

    International Nuclear Information System (INIS)

    Mandler, J.W.; Coates, R.A.; Killian, E.W.

    1979-01-01

    Gamma-ray scanning of irradiated fuel is an important nondestructive technique used in the thermal fuels behavior program currently under way at the Idaho National Engineering Laboratory. This paper is concerned with the computer-controlled isotopic gamma-ray-scanning system developed for postirradiation examination of fuel and includes a brief discussion of some scan results obtained from fuel rods irradiated in the Power-Burst Facility to illustrate gamma-ray spectrometry for this application. Both burnup profiles and information concerning fission-product migration in irradiated fuel are routinely obtained with the computer-controlled system

  13. Decaying vs annihilating dark matter in light of a tentative gamma-ray line

    Energy Technology Data Exchange (ETDEWEB)

    Buchmueller, Wilfried; Garny, Mathias

    2012-06-15

    Recently reported tentative evidence for a gamma-ray line in the Fermi-LAT data is of great potential interest for identifying the nature of dark matter. We compare the implications for decaying and annihilating dark matter taking the constraints from continuum gamma-rays, antiproton flux and morphology of the excess into account. We find that higgsino and wino dark matter are excluded, also for nonthermal production. Generically, the continuum gamma-ray ux severely constrains annihilating dark matter. Consistency of decaying dark matter with the spatial distribution of the Fermi-LAT excess would require an enhancement of the dark matter density near the Galactic center.

  14. Simulating Terrestrial Gamma-ray Flashes using SWORD (Invited)

    Science.gov (United States)

    Gwon, C.; Grove, J.; Dwyer, J. R.; Mattson, K.; Polaski, D.; Jackson, L.

    2013-12-01

    We report on simulations of the relativistic feedback discharges involved with the production of terrestrial gamma-ray flashes (TGFs). The simulations were conducted using Geant4 using the SoftWare for the Optimization of Radiation Detectors (SWORD) framework. SWORD provides a graphical interface for setting up simulations in select high-energy radiation transport engines. Using Geant4, we determine avalanche length, the energy spectrum of the electrons and gamma-rays as they leave the field region, and the feedback factor describing the degree to which the production of energetic particles is self-sustaining. We validate our simulations against previous work in order to determine the reliability of our results. This work is funded by the Office of Naval Research.

  15. The Gamma-Ray Imager GRI

    Science.gov (United States)

    Wunderer, Cornelia B.; GRI Collaboration

    2008-03-01

    Observations of the gamma-ray sky reveal the most powerful sources and the most violent events in the Universe. While at lower wavebands the observed emission is generally dominated by thermal processes, the gamma-ray sky provides us with a view on the non-thermal Universe. Here particles are accelerated to extreme relativistic energies by mechanisms which are still poorly understood, and nuclear reactions are synthesizing the basic constituents of our world. Cosmic accelerators and cosmic explosions are major science themes that are addressed in the gamma-ray regime. ESA's INTEGRAL observatory currently provides the astronomical community with a unique tool to investigate the sky up to MeV energies and hundreds of sources, new classes of objects, extraordinary views of antimatter annihilation in our Galaxy, and fingerprints of recent nucleosynthesis processes have been discovered. NASA's GLAST mission will similarly take the next step in surveying the high-energy ( GeV) sky, and NuSTAR will pioneer focusing observations at hard X-ray energies (to 80 keV). There will be clearly a growing need to perform deeper, more focused investigations of gamma-ray sources in the 100-keV to MeV regime. Recent technological advances in the domain of gamma-ray focusing using Laue diffraction and multilayer-coated mirror techniques have paved the way towards a gamma-ray mission, providing major improvements compared to past missions regarding sensitivity and angular resolution. Such a future Gamma-Ray Imager will allow the study of particle acceleration processes and explosion physics in unprecedented detail, providing essential clues on the innermost nature of the most violent and most energetic processes in the Universe.

  16. Study of cerenkov radiation. Production of {gamma} rays by electron accelerators; Etude du rayonnement de freinage. Production de rayons {gamma} par des accelerateurs d'electrons

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    This study is a critical comparison of the theories of Bremsstrahlung. Experimental results obtained by the production of {gamma} radiation with electron accelerators are compared to the theoretical results in order to estimate the extent to which the various theories are valid. (author) [French] Cette etude est une synthese des theories du rayonnement de freinage. Des resultats experimentaux, obtenus par la production de rayonnements {gamma} avec des accelerateurs d'electrons, sont compares aux resultats theoriques afin d'evaluer les domaines de validite des diverses theories. (auteur)

  17. Uses Of Gamma Rays In Peas Breeding

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  18. Lightning leader models of terrestrial gamma-ray flashes

    Science.gov (United States)

    Dwyer, J. R.; Liu, N.; Ihaddadene, K. M. A.

    2017-12-01

    Terrestrial gamma-ray flashes (TGFs) are bright sub-millisecond bursts of gamma rays that originate from thunderstorms. Because lightning leaders near the ground have been observed to emit x-rays, presumably due to runaway electron production in the high-field regions near the leader tips, models of TGFs have been developed by several groups that assume a similar production mechanism of runaway electrons from lightning leaders propagating through thunderclouds. However, it remains unclear exactly how and where these runaway electrons are produced, since lightning propagation at thunderstorm altitudes remains poorly understood. In addition, it is not obvious how to connect the observed behavior of the x-ray production from lightning near the ground with the properties of TGFs. For example, it is not clear how to relate the time structure of the x-ray emission near the ground to that of TGFs, since x-rays from stepped leaders near the ground are usually produced in a series of sub-microsecond bursts, but TGFs are usually observed as much longer pulses without clear substructures, at sub-microsecond timescales or otherwise. In this presentation, spacecraft observations of TGFs, ground-based observations of x-rays from lightning and laboratory sparks, and Monte Carlo and PIC simulations of runaway electron and gamma ray production and propagation will be used to constrain the lightning leader models of TGFs.

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

    Science.gov (United States)

    Dwyer, Joseph R.

    2012-02-01

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

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

    International Nuclear Information System (INIS)

    Prantzos, N.

    1986-07-01

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

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

    NARCIS (Netherlands)

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

    2015-01-01

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

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    Observations of the gamma-ray sky reveal the most powerful sources and the most violent events in the Universe. While at lower wavebands the observed emission is generally dominated by thermal processes, the gamma-ray sky provides us with a view on the non-thermal Universe. Here particles are acc...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1983-01-01

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

  4. Planetary Produced Axionlike Particles and Gamma-Ray Flashes

    International Nuclear Information System (INIS)

    Liolios, Anastasios

    2008-01-01

    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.

  5. Gamma ray irradiation to semi-purified diet

    International Nuclear Information System (INIS)

    Takigawa, Akihiro; Danbara, Hiroshi; Ohyama, Yoshinobu

    1976-01-01

    Semi-purified diet containing 10% soybean oil was irradiated with gamma rays at levels of 0.6, 3 and 6 Mrad and was fed to chicks. Crude fat contents of the diets decreased and a considerable amount of peroxide was formed with high doses of irradiation. Feed consumption and feed efficiency of the highly irradiated diets were less than those of control. Metabolizable energy and digestibility of the diets, especially of fat, were decreased with the irradiation. The chicks fed with irradiated diets showed marked dilatation of the small intestine and the liver, and their erythrocytes were more fragile than those of control. The same phenomena were found with the chicks fed the diet containing the oil highly oxidized by autoxidation. Irradiation of the diet excluding oil showed little effect on the growth of chicks. It was considered that these phenomena were caused by the peroxide or other oxidation products of fat which were formed with gamma ray irradiation. (auth.)

  6. Study on effects of gamma-ray irradiation on TlBr semiconductor detectors

    International Nuclear Information System (INIS)

    Matsumura, Motohiro; Watanabe, Kenichi; Yamazaki, Atsushi; Uritani, Akira; Kimura, Norihisa; Nagano, Nobumichi; Hitomi, Keitaro

    2016-01-01

    Radiation hardness of thallium bromide (TlBr) semiconductor detectors to 60 Co gamma-ray irradiation was evaluated. The energy spectra and μτ products of electrons were measured to evaluate the irradiation effects. No significant degradation of spectroscopic performance of the TlBr detector for 137 Cs gamma-rays was observed up to 45 kGy irradiation. Although the μτ products of electrons in the TlBr detector slightly decreased, position of the photo-peak was stable without significant degradation after the gamma-ray irradiation. We confirmed that the TlBr semiconductor detector has a high tolerance for gamma-ray irradiation at least up to 45 kGy. (author)

  7. Recent improvements in plutonium gamma-ray analysis using MGA

    International Nuclear Information System (INIS)

    Ruhter, W.D.; Gunnink, R.

    1992-06-01

    MGA is a gamma-ray spectrum analysis program for determining relative plutonium isotopic abundances. It can determine plutonium isotopic abundances better than 1% using a high-resolution, low-energy, planar germanium detector and measurement times ten minutes or less. We have modified MGA to allow determination of absolute plutonium isotopic abundances in solutions. With calibration of a detector using a known solution concentration in a well-defined sample geometry, plutonium solution concentrations can be determined. MGA can include analysis of a second spectrum of the high-energy spectrum to include determination of fission product abundances relative to total plutonium. For the high-energy gamma-ray measurements we have devised a new hardware configuration, so that both the low- and high-energy gamma-ray detectors are mounted in a single cryostat thereby reducing weight and volume of the detector systems. We describe the detector configuration, and the performance of the MGA program for determining plutonium concentrations in solutions and fission product abundances

  8. Fuzzy correlations of gamma-ray bursts

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  9. Prompt Gamma Ray Spectroscopy for process monitoring

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  10. Librarian driven analysis of gamma ray spectra

    International Nuclear Information System (INIS)

    Kondrashov, V.; Petersone, I.

    2002-01-01

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

  11. Technology Needs for Gamma Ray Astronomy

    Science.gov (United States)

    Gehrels, Neil

    2011-01-01

    Gamma ray astronomy is currently in an exciting period of multiple missions and a wealth of data. Results from INTEGRAL, Fermi, AGILE, Suzaku and Swift are making large contributions to our knowledge of high energy processes in the universe. The advances are due to new detector and imaging technologies. The steps to date have been from scintillators to solid state detectors for sensors and from light buckets to coded aperture masks and pair telescopes for imagers. A key direction for the future is toward focusing telescopes pushing into the hard X-ray regime and Compton telescopes and pair telescopes with fine spatial resolution for medium and high energy gamma rays. These technologies will provide finer imaging of gamma-ray sources. Importantly, they will also enable large steps forward in sensitivity by reducing background.

  12. Very high energy gamma-ray astronomy

    International Nuclear Information System (INIS)

    Weekes, T.C.

    1988-01-01

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

  13. Evaluation of gamma-ray intensities

    International Nuclear Information System (INIS)

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

    1980-04-01

    Relative intensities and intensities per decay of gamma rays were evaluated for 16 nuclides, 22 Na, 24 Na, 46 Sc, 54 Mn, 60 Co, 85 Sr, 88 Y, 95 Nb, sup(108m)Ag, 134 Cs, 133 Ba, 139 Ce, sup(180m)Hf, 198 Au, 203 Hg and 207 Bi. For most of these nuclides disintegration rates can be determined by means of β-γ or X-γ coincidence method. Since decay schemes of these nuclides are established, intensities per decay of strong gamma rays were accurately evaluated by using weak beta-ray branching ratios, relative gamma-ray intensities and internal conversion coefficients. Half-lives of the nuclides were also evaluated. Use of the nuclides, therefore, are recommended for precision intensity calibration of the detectors. (author)

  14. gamma. -ray. Present status and problems

    Energy Technology Data Exchange (ETDEWEB)

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

    1975-01-01

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

  15. High-energy gamma-ray astronomy and the COS-B mission

    International Nuclear Information System (INIS)

    Wills, R.D.

    1977-01-01

    The most significant results in gamma-ray astronomy have been produced by satellite- and balloon-borne instruments sensitive in the range 30 MeV to approximately 10 GeV. The COS-B instrument which is described is typical of this type of detector. For this reason the review of gamma-ray production mechanisms gives greater attention to those processes which are specifically important in that energy range. (orig.) [de

  16. Gamma-ray standards for detector calibration

    International Nuclear Information System (INIS)

    Lorenz, A.

    1985-10-01

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

  17. Very high energy gamma ray astrophysics

    International Nuclear Information System (INIS)

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

    1991-01-01

    The Whipple Observatory High Resolution Camera will be used in a vigorous program of observations to search for new sources of very-high-energy gamma rays. In addition, a search for antimatter using the moon-earth system as an ion spectrometer will be begun. The first phase of GRANITE, the new 37-element 11-m camera, will be concluded with first light scheduled for September, 1991. The two cameras will operate in support of the Gamma Ray Observatory mission in the winter of 1991/2

  18. VHE Gamma-ray Supernova Remnants

    Energy Technology Data Exchange (ETDEWEB)

    Funk, Stefan; /KIPAC, Menlo Park

    2007-01-22

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

  19. Gamma-ray lasers or grasers

    International Nuclear Information System (INIS)

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

    1976-01-01

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

  20. Nuclear Forensics using Gamma-ray Spectroscopy

    Directory of Open Access Journals (Sweden)

    Norman E. B.

    2016-01-01

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

  1. Gamma-ray surveys in uranium exploration

    International Nuclear Information System (INIS)

    1979-01-01

    This report is intended to provide newcomers to uranium exploration with an up-to-date statement of the principal factors to be considered in planning and using gamma-ray surveys. Since the report incorporates the results of recent research, and since its preparation was influenced by the cumulative experience of its contributors, it should also be useful to those who already have some knowledge of radioactivity surveys and methods. The intention is that the information and explanations given in the report will make it possible for gamma-ray surveys to be used in the most efficient way for a given exploration task

  2. Neutron Capture Gamma-Ray Libraries for Nuclear Applications

    International Nuclear Information System (INIS)

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

    2011-01-01

    The neutron capture reaction is useful in identifying and analyzing the gamma-ray spectrum from an unknown assembly as it gives unambiguous information on its composition. This can be done passively or actively where an external neutron source is used to probe an unknown assembly. There are known capture gamma-ray data gaps in the ENDF libraries used by transport codes for various nuclear applications. The Evaluated Gamma-ray Activation file (EGAF) is a new thermal neutron capture database of discrete line spectra and cross sections for over 260 isotopes that was developed as part of an IAEA Coordinated Research Project. EGAF is being 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 90% of all the decay energy and 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 are investigating the capture spectra from higher energy neutrons experimentally using surrogate reactions and modeling this with Hauser-Feshbach codes. This can then be used to benchmark CASINO, a version of DICEBOX modified for neutron capture at higher energy. This can be used to simulate spectra from neutron capture at incident neutron energies up to 20 MeV to improve the gamma-ray spectrum in neutron data libraries used for transport modeling of unknown assemblies.

  3. Neutron Capture Gamma-Ray Libraries for Nuclear Applications

    International Nuclear Information System (INIS)

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

    2010-01-01

    The neutron capture reaction is useful in identifying and analyzing the gamma-ray spectrum from an unknown assembly as it gives unambiguous information on its composition. this can be done passively or actively where an external neutron source is used to probe an unknown assembly. There are known capture gamma-ray data gaps in the ENDF libraries used by transport codes for various nuclear applications. The Evaluated Gamma-ray Activation file (EGAF) is a new thermal neutron capture database of discrete line spectra and cross sections for over 260 isotopes that was developed as part of an IAEA Coordinated Research project. EGAF is being 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 90% of all the decay energy and 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. They are investigating the capture spectra from higher energy neutrons experimentally using surrogate reactions and modeling this with Hauser-Feshbach codes. This can then be used to benchmark CASINO, a version of DICEBOX modified for neutron capture at higher energy. This can be used to simulate spectra from neutron capture at incident neutron energies up to 20 MeV to improve the gamma-ray spectrum in neutron data libraries used for transport modeling of unknown assemblies.

  4. Modeling of Pulses in Terrestrial Gamma-ray Flashes

    Science.gov (United States)

    Xu, Wei; Celestin, Sebastien; Pasko, Victor

    2015-04-01

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

  5. Capture Gamma-Ray Libraries for Nuclear Applications

    International Nuclear Information System (INIS)

    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.

    2010-01-01

    The neutron capture reaction is useful in identifying and analyzing the gamma-ray spectrum from an unknown assembly as it gives unambiguous information on its composition. This can be done passively or actively where an external neutron source is used to probe an unknown assembly. There are known capture gamma-ray data gaps in the ENDF libraries used by transport codes for various nuclear applications. The Evaluated Gamma-ray Activation file (EGAF) is a new thermal neutron capture database of discrete line spectra and cross sections for over 260 isotopes that was developed as part of an IAEA Coordinated Research Project. EGAF has been used to improve the capture gamma production in ENDF libraries. For medium to heavy nuclei the quasi continuum contribution to the gamma cascades is not experimentally resolved. The continuum contains up to 90% 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.

  6. Computer programs for data reduction and interpretation in plutonium and uranium analysis by gamma ray spectrometry

    International Nuclear Information System (INIS)

    Singh, R.K.; Moorthy, A.D.; Babbar, R.K.; Udagatti, S.V.

    1989-01-01

    Non destructive gamma ray have been developed for analysis of isotopic abundances and concentrations of plutonium and uranium in the respective product solutions of a reprocessing plant. The method involves analysis of gamma rays emitted from the sample and uses a multichannel analyser system. Data reduction and interpretation of these techniques are tedious and time consuming. In order to make it possible to use them in routine analysis, computer programs have been developed in HP-BASIC language which can be used in HP-9845B desktop computer. A set of programs, for plutonium estimation by high resolution gamma ray spectrometry and for on-line measurement of uranium by gamma ray spectrometry are described in this report. (author) 4 refs., 3 tabs., 6 figs

  7. SPATIAL AND SPECTRAL MODELING OF THE GAMMA-RAY DISTRIBUTION IN THE LARGE MAGELLANIC CLOUD

    Energy Technology Data Exchange (ETDEWEB)

    Foreman, Gary; Chu, You-Hua; Gruendl, Robert; Fields, Brian; Ricker, Paul [Department of Astronomy, University of Illinois, 1002 W. Green St., Urbana, IL 61801 (United States); Hughes, Annie, E-mail: gforema2@illinois.edu [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)

    2015-07-20

    We perform spatial and spectral analyses of the LMC gamma-ray emission collected over 66 months by the Fermi Gamma-ray Space Telescope. In our spatial analysis, we model the LMC cosmic-ray distribution and gamma-ray production using observed maps of the LMC interstellar medium, star formation history, interstellar radiation field, and synchrotron emission. We use bootstrapping of the data to quantify the robustness of spatial model performance. We model the LMC gamma-ray spectrum using fitting functions derived from the physics of π{sup 0} decay, Bremsstrahlung, and inverse Compton scattering. We find the integrated gamma-ray flux of the LMC from 200 MeV to 20 GeV to be 1.37 ± 0.02 × 10{sup −7} ph cm{sup −2} s{sup −1}, of which we attribute about 6% to inverse Compton scattering and 44% to Bremsstrahlung. From our work, we conclude that the spectral index of the LMC cosmic-ray proton population is 2.4 ± 0.2, and we find that cosmic-ray energy loss through gamma-ray production is concentrated within a few 100 pc of acceleration sites. Assuming cosmic-ray energy equipartition with magnetic fields, we estimate LMC cosmic rays encounter an average magnetic field strength ∼3 μG.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    The GAMMA-400 gamma-ray space-based telescope has as its main goals to measure cosmic γ-ray fluxes and the electron-positron cosmic-ray component produced, theoretically, in dark-matter-particles decay or annihilation processes, to search for discrete γ-ray sources and study them in detail, to examine the energy spectra of diffuse γ-rays — both galactic and extragalactic — and to study gamma-ray bursts (GRBs) and γ-rays from the active Sun. Scientific goals of GAMMA-400 telescope require fine angular resolution. The telescope is of a pair-production type. In the converter-tracker, the incident gamma-ray photon converts into electron-positron pair in the tungsten layer and then the tracks are detected by silicon- strip position-sensitive detectors. Multiple scattering processes become a significant obstacle in the incident-gamma direction reconstruction for energies below several gigaelectronvolts. The method of utilising this process to improve the resolution is proposed in the presented work. (paper)

  9. Light Dawns on Dark Gamma-ray Bursts

    Science.gov (United States)

    2010-12-01

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

  10. Gamma ray observations of the solar system

    International Nuclear Information System (INIS)

    1981-01-01

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

  11. Gamma ray observations of the solar system

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

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

  12. Gamma ray observations of the solar system

    Science.gov (United States)

    1981-01-01

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

  13. Black Hole Accretion in Gamma Ray Bursts

    Directory of Open Access Journals (Sweden)

    Agnieszka Janiuk

    2017-02-01

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

  14. Swift: A gamma ray burst MIDEX

    International Nuclear Information System (INIS)

    Barthelmy, Scott

    2001-01-01

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

  15. Gamma-ray bursts at high redshift

    NARCIS (Netherlands)

    Wijers, R.A.M.J.

    1999-01-01

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

  16. Coakial gamma ray detector and method therefor

    International Nuclear Information System (INIS)

    Harchol, M.

    1977-01-01

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

  17. Effects of Shielding on Gamma Rays

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-03-13

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

  18. Developments in mercuric iodide gamma ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Patt, B E; Beyerle, A G; Dolin, R C; Ortale, C [EG and G Energy Measurements, Inc., Goleta, CA (USA). Santa Barbara Operations

    1989-11-01

    A mercuric iodide (HgI{sub 2}) gamma ray imaging array and camera system previously described have been characterized for spatial and energy resolution. Based on these data a new camera is being developed to more fully exploit the potential of the array. Characterization results and design criteria for the new camera will be presented. (orig.).

  19. Current segmented gamma-ray scanner technology

    International Nuclear Information System (INIS)

    Bjork, C.W.

    1987-01-01

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

  20. Gamma-Ray Telescope and Uncertainty Principle

    Science.gov (United States)

    Shivalingaswamy, T.; Kagali, B. A.

    2012-01-01

    Heisenberg's Uncertainty Principle is one of the important basic principles of quantum mechanics. In most of the books on quantum mechanics, this uncertainty principle is generally illustrated with the help of a gamma ray microscope, wherein neither the image formation criterion nor the lens properties are taken into account. Thus a better…

  1. Gamma-ray astronomy: A historical perspective

    International Nuclear Information System (INIS)

    Lingenfelter, R.E.

    1988-01-01

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

  2. Gamma-ray Emission from Globular Clusters

    Directory of Open Access Journals (Sweden)

    Pak-Hin T. Tam

    2016-03-01

    Full Text Available Over the last few years, the data obtained using the Large Area Telescope (LAT aboard the Fermi Gamma-ray Space Telescope has provided new insights on high-energy processes in globular clusters, particularly those involving compact objects such as MilliSecond Pulsars (MSPs. Gamma-ray emission in the 100 MeV to 10 GeV range has been detected from more than a dozen globular clusters in our galaxy, including 47 Tucanae and Terzan 5. Based on a sample of known gammaray globular clusters, the empirical relations between gamma-ray luminosity and properties of globular clusters such as their stellar encounter rate, metallicity, and possible optical and infrared photon energy densities, have been derived. The measured gamma-ray spectra are generally described by a power law with a cut-off at a few gigaelectronvolts. Together with the detection of pulsed γ-rays from two MSPs in two different globular clusters, such spectral signature lends support to the hypothesis that γ-rays from globular clusters represent collective curvature emission from magnetospheres of MSPs in the clusters. Alternative models, involving Inverse-Compton (IC emission of relativistic electrons that are accelerated close to MSPs or pulsar wind nebula shocks, have also been suggested. Observations at >100 GeV by using Fermi/LAT and atmospheric Cherenkov telescopes such as H.E.S.S.-II, MAGIC-II, VERITAS, and CTA will help to settle some questions unanswered by current data.

  3. Gamma ray bursts of black hole universe

    Science.gov (United States)

    Zhang, T. X.

    2015-07-01

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

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

    International Nuclear Information System (INIS)

    Inoue, Yoshiyuki

    2015-01-01

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

  6. Study of radio-restoration by various mineral salts and silice wich products (Tuf and Pouzzolane) of rice embryos (oryza-sativa L, Cigalon variety) exposed to cobalt 60 gamma rays

    International Nuclear Information System (INIS)

    Mouthia-Khadija.

    1981-12-01

    Mutagenic treatments produce a large number of mutants per unit time and are used for plant improvement. However these treatments cause damage to cells. To counteract this radio-induced damage 2 methods are being tried: - Protection, which consists in the supply of an active product before application of mutagenic agents; - Restoration, which tries to repair the damage after mutagenic treatment. This work is devoted to restoration processes. Technique for the isolation and culture on a suitable nutrient of rice embryos (oryza sativa L, Cigalon variety) separated from non-irradiated caryopses were developed first. By separating out the embryo in this way it is possible to study in vitro the interactions between the embryo and the rest of the caryopsis (albumin + pericarp). The effects of radiations on embryos from caryopses exposed to cobalt 60 gamma rays were measured next, then the action of certain inorganic elements contained in the caryopsis tissues was analysed. On the basis of the first results obtained the differences in response between plantlets from embryos irradiated or otherwise treated or not either by zinc sulphate or by very silice-rich volcanic products (Tuf and Pouzzolane), were examined by chemical analysis techniques. These tests have allowed the detection of ionic changes induced by irradiation during the different stages of plant development and led to a better estimate of the radio-restoration mechanisms brought about by the various chemical compounds used [fr

  7. Neutron-induced gamma-ray spectroscopy: simulations for chemical mapping of planetary surfaces

    International Nuclear Information System (INIS)

    Brueckner, J.; Waenke, H.; Reedy, R.C.

    1986-01-01

    Cosmic rays interact with the surface of a planetary body and produce a cascade of secondary particles, such as neutrons. Neutron-induced scattering and capture reactions play an important role in the production of discrete gamma-ray lines that can be measured by a gamma-ray spectrometer on board of an orbiting spacecraft. These data can be used to determine the concentration of many elements in the surface of a planetary body, which provides clues to its bulk composition and in turn to its origin and evolution. To investigate the gamma rays made by neutron interactions, thin targets were irradiated with neutrons having energies from 14 MeV to 0.025 eV. By means of foil activation technique the ratio of epithermal to thermal neutrons was determined to be similar to that in the Moon. Gamma rays emitted by the targets and the surrounding material were detected by a high-resolution germanium detector in the energy range of 0.1 to 8 MeV. Most of the gamma-ray lines that are expected to be used for planetary gamma-ray spectroscopy were found in the recorded spectra and the principal lines in these spectra are presented. 58 refs., 7 figs., 9 tabs

  8. Radon emanation and soil moisture effects on airborne gamma-ray measurements

    International Nuclear Information System (INIS)

    Grasty, R.L.

    1997-01-01

    A theoretical model is developed to explain variations in airborne gamma-ray measurements over a calibration range near Ottawa, Ontario. The gamma-ray flux from potassium and the thorium decay series showed an expected decrease with increasing soil moisture. However, the gamma-ray flux from the uranium decay series was highest in the spring when the ground was water-saturated and even covered with snow. These results are explained through the build-up of radon and its associated gamma-ray-emitting decay products in the clay soil of the calibration range with increasing soil moisture. Similar results were found from airborne measurements over other clay soils. However, measurements over sandy soils showed that the count rates from all three radio elements increased with decreasing soil moisture. This difference between soil types was attributed to the lower radon emanation of the more coarse-grained sandy soils compared to finer-grained clay soils. The theoretical and experimental results demonstrate that any estimate of the natural gamma-ray field caused by radium in the ground must take into consideration the radon emanation coefficient of the soil. The radon diffusion coefficient of the soil must also be considered since it depends strongly on soil moisture. This has significant implications for the assessment of outdoor radiation doses using laboratory analyses of soil samples and the use of ground and airborne gamma-ray measurements for radon potential mapping

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

    International Nuclear Information System (INIS)

    Clark, D.D.

    1995-01-01

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

  10. Interstellar medium structure and content and gamma ray astronomy

    International Nuclear Information System (INIS)

    Lebrun, F.

    1982-05-01

    A general description of gamma-ray astronomy is presented with special emphasis on the study of diffuse gamma-ray emission. This is followed by a collection of reflections and observations on the structure and the gas and dust content of the local interstellar medium. Results of gamma-ray observations on the local interstellar medium are given. The last part is devoted to the whole of the galactic gamma-ray emission and its interpretation [fr

  11. Gamma-ray burst observations: the present situation

    International Nuclear Information System (INIS)

    Vedrenne, G.

    1984-01-01

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

  12. Egret observations of the extragalactic gamma-ray emission

    DEFF Research Database (Denmark)

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

    1998-01-01

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

  13. High-energy neutrinos from gamma ray bursts

    International Nuclear Information System (INIS)

    Dermer, Charles D.; Atoyan, Armen

    2003-01-01

    We treat high-energy neutrino production in gamma ray bursts (GRBs). Detailed calculations of photomeson neutrino production are presented for the collapsar model, where internal nonthermal synchrotron radiation is the primary target photon field, and the supranova model, where external pulsar-wind synchrotron radiation provides important additional target photons. Detection of > or approx. 10 TeV neutrinos from GRBs with Doppler factors > or approx. 200, inferred from γ-ray observations, would support the supranova model. Detection of or approx. 3x10 -4 erg cm -2 offer a realistic prospect for detection of ν μ

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-03-01

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

  15. Study of neutrino production in the Cannonball model of Gamma ray bursts: possibility of observation of these neutrinos with the Antares neutrinos telescope, and study of the optical background recorded with the prototype sector line

    International Nuclear Information System (INIS)

    Ferry, S.

    2004-09-01

    ANTARES is a future neutrino telescope which will be build at 40 km off the french coast (Toulon), at a 2500 m depth. The interaction of a neutrino with matter produces a muon which emits Cerenkov light while propagating in water. This light is detected with 900 photomultipliers distributed over 12 lines. Gamma ray bursts (GRB) are violent cosmological phenomenon observed once per day. In the Cannonball Model, bursts are produced by the interaction of a jet made of cannonballs (CB) with a supernova remnant (SNR). Forward shocks propagate in the SNR, reverse ones in the CB and neutrinos are produced at the shock fronts. An estimation of the neutrino production is given and is studied over a large parameter range. For a typical GRB, 0.002 to 0.3 v μ , cm -2 can be produced. Depending on the viewing angle, ANTARES could detect 1 to 10 v μ per year in correlation with GRBs. The ambient optical background has been recorded by the ANTARES prototype sector line. The analysis is about the background influence on the detector performance and about the organisms activity which produces it. For example, it appears a 17.6 to 20.4 h periodicity which is compatible with the liquid masses movement imposed by the Coriolis force at the ANTARES latitude. (author)

  16. Relativistic effects in gamma-ray bursts

    International Nuclear Information System (INIS)

    Eriksen, Erik; Groen, Oeyvind

    1999-01-01

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

  17. Environmental Effects of Gamma Ray Bursts

    International Nuclear Information System (INIS)

    Martin, Osmel; Zarauza, Dario; Cardenas, Rolando

    2007-01-01

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

  18. TeV gamma-ray astronomy

    International Nuclear Information System (INIS)

    Cui Wei

    2009-01-01

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

  19. Real time gamma-ray signature identifier

    Science.gov (United States)

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

    2012-05-15

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

  20. The Future of Gamma Ray Astrophysics

    CERN Multimedia

    CERN. Geneva

    2016-01-01

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

  1. Advances in gamma-ray burst astronomy

    International Nuclear Information System (INIS)

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

    1976-01-01

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

  2. Nature of gamma-ray burst sources

    International Nuclear Information System (INIS)

    Ventura, J.

    1983-01-01

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

  3. Evaluation of gamma-ray intensities

    International Nuclear Information System (INIS)

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

    1978-03-01

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

  4. Gamma-ray standards for detector calibration

    International Nuclear Information System (INIS)

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

    1987-09-01

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

  5. Gamma-ray bursts - a critical review

    International Nuclear Information System (INIS)

    Tudose, Valeriu; Biermann, Peter

    2003-01-01

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

  6. Balloon observation of gamma-ray burst

    International Nuclear Information System (INIS)

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

    1978-01-01

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

  7. Prompt Gamma Ray Analysis of Soil Samples

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-01

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

  8. AGILE: A gamma-ray mission

    International Nuclear Information System (INIS)

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

    2000-01-01

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

  9. Gamma ray irradiation characteristics of SM fibers

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  10. A gamma-ray discriminating neutron scintillator

    International Nuclear Information System (INIS)

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

    1994-01-01

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

  11. Radio Flares from Gamma-ray Bursts

    Science.gov (United States)

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

    2015-06-01

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

  12. RADIO FLARES FROM GAMMA-RAY BURSTS

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  13. Gamma rays from the interstellar medium

    International Nuclear Information System (INIS)

    Bloemen, J.B.G.M.

    1985-01-01

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

  14. Gamma-ray Output Spectra from 239 Pu Fission

    International Nuclear Information System (INIS)

    Ullmann, John

    2015-01-01

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

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

    International Nuclear Information System (INIS)

    Narita, Tsutomu; Kitao, Kensuke.

    1991-03-01

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

  16. Physical constraints on models of gamma-ray bursters

    International Nuclear Information System (INIS)

    Epstein, R.I.

    1985-01-01

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

  17. Gamma-ray mirror technology for NDA of spent fuel

    Energy Technology Data Exchange (ETDEWEB)

    Descalle, M. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ruz-Armendariz, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Decker, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Alameda, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brejnholt, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Soufli, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Robinson, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dreyer, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pivovaroff, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ziock, K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chichester, D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Watson, S. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Trellue, H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-28

    Direct measurements of gamma rays emitted by fissile material have been proposed as an alternative to measurements of the gamma rays from fission products. From a safeguards applications perspective, direct detection of uranium (U) and plutonium (Pu) K-shell fluorescence emission lines and specific lines from some of their isotopes could lead to improved shipper-receiver difference or input accountability at the start of Pu reprocessing. However, these measurements are difficult to implement when the spent fuel is in the line-of-sight of the detector, as the detector is exposed to high rates dominated by fission product emissions. To overcome the combination of high rates and high background, grazing incidence multilayer mirrors have been proposed as a solution to selectively reflect U and Pu hard X-ray and soft gamma rays in the 90 to 420 keV energy into a high-purity germanium (HPGe) detector shielded from the direct line-of-sight of spent fuel. Several groups demonstrated that K-shell fluorescence lines of U and Pu in spent fuel could be detected with Ge detectors. In the field of hard X-ray optics the performance of reflective multilayer coated reflective optics was demonstrated up to 645 keV at the European Synchrotron Radiation Facility. Initial measurements conducted at Oak Ridge National Laboratory with sealed sources and scoping experiments conducted at the ORNL Irradiated Fuels Examination Laboratory (IFEL) with spent nuclear fuel further demonstrated the pass-band properties of multilayer mirrors for reflecting specific emission lines into 1D and 2D HPGe detectors, respectively.

  18. Continuum gamma-ray spectroscopy

    International Nuclear Information System (INIS)

    Diamond, R.M.

    1981-06-01

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

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

    Science.gov (United States)

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

    2005-05-12

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

  20. Observations on transverse moments of pions neutral and gamma rays of intermediate mass state ∼3GeW/c2 (MIRIM) in meson multiple production

    International Nuclear Information System (INIS)

    Fauth, A.C.

    1986-01-01

    The transverse moment distribution of pions neutral of 32 mirin c-jets with ΣΕγ>20 TeV by tw methods of 2γ->Π 0 coupling. This results independ of any particle production model. A simulation of pion production by Monte Carlo method is carried out and it is shown that, the two methods provide to obtain approximately 50% of correct couplings. The form of pions neutral distribution depends weakly of the percentage of correct couplings. The pions neutral transverse moment distribution of Mirins events is obtained by a third model which is completely independent from the two first, which consists in a composition between an analytical solution and the Monte Carlo method. The results of the three methods are consistents among themselves. (M.C.K.) [pt

  1. Gamma ray production cross sections for the interactions of 14.9 MeV neutrons with C, Al, V, Fe and Nb at 90 deg

    International Nuclear Information System (INIS)

    Zhou Hongyu; Tang Lin; Yan Yiming

    1986-11-01

    Discrete γ-ray spectra and production cross sections for the interactions of 14.9 MeV neutrons with C, Al, V, Fe and Nb targets have been measured at 90 deg. using a 110.7cm 3 Ge(Li) detector. A single γ-ray peak was measured for C. For Al 34 γ lines, for Fe 41 γ lines, for V 61 γ lines and for Nb 79 γ lines were measured

  2. Decomposition of water and production of H{sub 2} using semiconductor-photocatalytic effect induced by gamma ray from high radioactive waste

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Y; Kawaguchi, K; Myouchin, M [Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan). Tokai Works

    1996-12-31

    The technology of the radiolytic decomposition of water leading to hydrogen production was demonstrated to explore a new field in the utilization of radiation and radioactive elements. The technology used consisted of a photoassisted catalytic method which has been generally investigated for photocatalysis using a semiconductor and light in an electrochemical study. In our study, gamma radiation from Co-60 was used instead of light, and a significant amount of evolved hydrogen was detected. Our preliminary experiments proved the possibility of converting the energy ionizing radiation (gamma radiation) into chemical energy (hydrogen) using a semiconductor-photocatalytic effect. (author).

  3. The study of 90 deg. gamma ray production cross sections for interactions of 14.9 Mev neutrons with C, Al, V, Fe, Co, Nb samples

    International Nuclear Information System (INIS)

    Tang Lin; Yan Yiming; Zhou Hongyu; Wen Shenlin; Wang Qi; Sun Shuxu; Ding Xiaoji; Wang Wanhong

    1987-04-01

    The (n,xr) reactions have been studied for incident neutron energy 14.9 Mev and for the samples C, Al, V, Fe, Co and Nb. The pulsed beam Time-of-Flight technique was adopted to discriminate neutrons and de-excitation r-rays and to improve the background conditions of the experiment. 90 deg. differential gamma production cross sections as the results of experiments are presented. Due to very low background many new r-rays peaks have been obtained. (author). 14 refs, 12 figs, 1 tab

  4. Effects of glucose irradiated by high doses of 60cobalt gamma rays, and of some products of glucose radiolysis on the growth of Jerusalem Artichoke tissue and potato shoots culture in vitro

    International Nuclear Information System (INIS)

    Manant, Pierre

    1975-01-01

    Glucose, irradiated in dry conditions by gamma rays from 5.10 5 to 10 7 rad, and incorporated into culture medium, inhibits growth and, simultaneously, increases rhizogenesis of Jerusalem Artichoke tissue in culture. Tuberisation of potato shoots grown in vitro is delayed and partially inhibited. Some substances which result from radiolysis of sugars give the same results, but only at higher concentrations [fr

  5. Colorado School of Mines Fusion Gamma Ray Project

    International Nuclear Information System (INIS)

    Cecil, F.E.

    1990-01-01

    This report summarizes the activities and accomplishments of the CSM Fusion Gamma Ray Project for the calendar year 1989. As reported in last year's Technical Progress Report, the initial objective of the project was the design and bench testing of an eight channel, very high count rate gamma ray spectrometer. The next objective of the project was the installation and field testing of a comparable fifteen channel spectrometer on TFTR. This objective has been accomplished over the past year and the system has been operated successfully at count rates approaching 10 MHz during neutral beam injected (NBI) deuterium plasmas with injected beam powers in excess of 20 MW. The MFE computer network link between CSM and TFTR has been most valuable in the accomplishment of the year's objectives and should serve as a model for future collaborations of outside researchers with experiments on TFTR and CIT. The coming year's work includes the spectrometry of high energy fusion gamma rays during 3 He minority ICRH heating of deuterium plasmas and hydrogen minority ICRH heating during Lithium pellet injection as diagnostics of energetic alpha particle production. We include in this report selected results from our parallel grant from the DOE Office of High Energy and Nuclear Physics as they pertain to the present APP grant. These results include experimentally derived thermonuclear reactivities of various light ion fusion plasmas for temperatures up to 40 keV. We would emphasize that our APP project is highly collaborative in nature and that Sid Medley and other members of the TFTR staff deserve much of the credit and bore much of the cost for many of the important accomplishments summarized in this report

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

    International Nuclear Information System (INIS)

    Sofia, S.; Wilson, R.E.

    1976-01-01

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

  7. Radiolysis of titanium potassium oxalate in aqueous solution. [. gamma. rays

    Energy Technology Data Exchange (ETDEWEB)

    Bundo, Y; Ono, I [Industrial Research Inst. of Kanagawa Prefecture, Yokohama (Japan); Ogawa, T

    1975-01-01

    The dissolution state of titanium potassium oxalate in aqueous solution is different according to the pH. The yellowish brown titanium complex produced by the reaction of titanium potassium oxalate and hydrogen peroxide seems to be different in its structure according to the pH. Considering these points, gamma-ray irradiation was carried out on the sample by dissolving titanium potassium oxalate in purified water under the conditions of oxygen saturation and nitrogen saturation, and the relation between irradiation dose and the production of titanium complex was determined. On the basis of the experimental result, the mechanism of forming hydrogen peroxide was presumed. The radiation source used was 2,000 Ci of /sup 60/Co. For photometric analysis, a 139 type photoelectric spectrophotometer of Hitachi Ltd. was used. From the experimental results, in neutral water, titanium potassium oxalate exists in the state that two oxalic acid ions are coordinated to titanyl ion, while in case of the pH lowered by the addition of sulfuric acid, it can exist in the state that one oxalic acid ion is coordinated to titanyl ion. The yield of hydrogen peroxide produced by irradiating titanium potassium oxalate aqueous solution with gamma-ray is the sum of the molecular product from water and the radiolysis product from titanium potassium oxalate.

  8. Influence of gamma-rays and some cultural conditions on the enhancement of cellulase production by some fungal strains isolated from cellulosic wastes

    International Nuclear Information System (INIS)

    Aziz, N.H.; Abo-State, M.A.; Girigs, A.M.P.; Youssef, Kh.A.; El-Mahalawy, A.A.

    2010-01-01

    In the present study, out of 51 fungal strains isolated from the cellulosic wastes, only 19 were CMCase-producers. Aspergillus, Fusarium and Penicillium were the most common fungal genera isolated from the cellulosic wastes. Fusarium neoceras, Aspergillus fumigatus and Fusarium oxysporium produced CMCase activity than Trichoderma viride. Out of 23 gamma-irradiated survivors from A.fumigatus and F. neoceras showing CMCase production, only two mutant strains A.fumigatus 8G-2 and F. neoceras 4G-2 produced the highest levels of CMCase than the parent strains. The results indicated that the maximum level of of CMCase activity was produced by A.fumigatus and F. neoceras strains under optiminizing conditions.

  9. Gamma-Ray Background Variability in Mobile Detectors

    Science.gov (United States)

    Aucott, Timothy John

    Gamma-ray background radiation significantly reduces detection sensitivity when searching for radioactive sources in the field, such as in wide-area searches for homeland security applications. Mobile detector systems in particular must contend with a variable background that is not necessarily known or even measurable a priori. This work will present measurements of the spatial and temporal variability of the background, with the goal of merging gamma-ray detection, spectroscopy, and imaging with contextual information--a "nuclear street view" of the ubiquitous background radiation. The gamma-ray background originates from a variety of sources, both natural and anthropogenic. The dominant sources in the field are the primordial isotopes potassium-40, uranium-238, and thorium-232, as well as their decay daughters. In addition to the natural background, many artificially-created isotopes are used for industrial or medical purposes, and contamination from fission products can be found in many environments. Regardless of origin, these backgrounds will reduce detection sensitivity by adding both statistical as well as systematic uncertainty. In particular, large detector arrays will be limited by the systematic uncertainty in the background and will suffer from a high rate of false alarms. The goal of this work is to provide a comprehensive characterization of the gamma-ray background and its variability in order to improve detection sensitivity and evaluate the performance of mobile detectors in the field. Large quantities of data are measured in order to study their performance at very low false alarm rates. Two different approaches, spectroscopy and imaging, are compared in a controlled study in the presence of this measured background. Furthermore, there is additional information that can be gained by correlating the gamma-ray data with contextual data streams (such as cameras and global positioning systems) in order to reduce the variability in the background

  10. Potency of Gamma ray, Electric Current and Elicitor Application, as a Novel Practical Technique, to Improve Biomass Production and Glycoside Quality for Digitalis purpurea L. Grown in Sandy Soil Irrigated with Brackish Water

    International Nuclear Information System (INIS)

    Bosila, H.A.; Afifi, L.M.A.; Ahmed, T.E.S.

    2012-01-01

    Digitalis purpurea L seeds were treated before sowing with gamma ray (G:0, 2.5, 5, 7.5 KR, and electric current (E:O, 100, 150, 200 mA) then grown in sandy soil irrigated with brackish water (900 ppm) , in splite-splite plot design for 3 replicat (R) at two subsequent seasons , through surface drip irrigation system. Plants at 4- month old and monthly until before flowering were foliar sprayed with MnSO 4 as abiotic elicitor (M :O, 3 ppm). Biomass/ Feddan, percentage of total glycosides and percentage of bioactive glycosides, digitoxin and gitoxin were quantitated. Statistical analysis for the obtained data revealed that G, E and M achieved significant in biomass yield and its quality traits. Moreover, interactions ; GE, GM, EM and GEM achieved synergistic and significant increment for this traits. At such G dose the trait was increased by increasing E dose and M concentration. Hence, G 2.5, 5,7.5 KR E200 mA M3 ppm achieved significant increment, as percent over that of control, in biomass production / Feddan by 22, 29, 32%, total glycoside by 27, 40, 30%, digitoxin 27, 40, 30% for both first and second seasons, respectively. Whereas, increment for gitoxin were 27, 41, 30% at first season and 26, 38, 30% at second season, respectively. Overall, these finding strongly confirm the reliability of GEM as a novel practical technique for overproduction biomass/Fed. and quality improvement bioactive cardiac glycosides, digitoxin and gitoxin in Digitalis purpurea L.

  11. Phenomenology of Dark Matter from radio to gamma ray frequencies

    International Nuclear Information System (INIS)

    Vollmann, Martin

    2015-07-01

    Multiwavelength astronomical observations have been proven to be of crucial relevance in understanding the most fundamental questions in physics. One of the biggest mysteries of nature is the existence of a (still) unidentified type of matter that makes up most of the material universe. Although little is known about its nature, it is very likely that this exotic Dark Matter (DM) is made of so-called Weakly Interacting Massive Particles (WIMPs). In this thesis we investigate which strategies can best address the fundamental question: What is Dark Matter? Specifically, by following the ''WIMP'' paradigm as our guiding principle, we comprehensively discuss the phenomenology of prospective ''indirect'' detection scenarios of such WIMPs. Special consideration is given to extraterrestrial gamma rays and radio waves produced around the center of the Milky Way. In light of two recently highly debated claims of WIMP Dark Matter discovery, namely the 130 GeV gamma-ray line and the GeV gamma-ray excess, we invoke our methods to confront those hypotheses. In addition our study contains antiparticle cosmic-ray (antiproton and positron) data analyses. The phenomenology for indirect DM detection with these ''messengers'' is briefly discussed as well. By exploiting the high degree of symmetry of typical annihilating 2-WIMP initial states, we are able to employ a very powerful tool in theoretical particle physics: the generalized optical theorem. This theorem relates the amplitude of loop-suppressed processes, such as the 130 GeV line if interpreted as product of WIMP annihilations, with tree-level process which are constrained in the same way as with the GeV excess. Unprecedentedly reported analytical computations of partial-wave (and helicity) cross sections with general applicability are calculated and applied. The possibility that a non-trivial effect in the particle model for DM might enhance the strength of a gamma-ray

  12. GAMMA RAYS FROM STAR FORMATION IN CLUSTERS OF GALAXIES

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  13. U and Pu Gamma-Ray Measurements of Spent Fuel Using a Gamma-Ray Mirror Band-Pass Filter

    International Nuclear Information System (INIS)

    Ziock, K.-P.; Kisner, R.; Melin, A.; Patton, B.; Alameda, J.; Brejnhold, N.; Decker, T.; Descalle, M.-A.; Fernandez-Perea, M.; Hill, R.; Ruz Armendariz, J.; Soufli, R.

    2015-01-01

    We report the use of grazing incidence gamma-ray mirrors as narrow band-pass filters for advanced non-destructive analysis of spent nuclear fuel. The mirrors limit radiation reaching an HPGe detector to narrow spectral bands around characteristic emission lines from fissile isotopes in the fuel. Ideally, these emissions could be used to determine the fuel's fissile content, but they are normally masked by the overwhelming radiation emitted by short-lived fission by-products. These latter emissions raise the overall background, making direct observation of the fuel with HPGe detectors virtually impossible. Such observations can only be performed using precise collimators that restrict the detector's field of view to very small solid angles. This results in impracticably long dwell times for safeguards measurements targeting the weak isotopic lines of interest. In a proof-ofconcept experiment, a set of simple flat gamma-ray mirrors was used to observe the atomic florescence lines from U and Pu from a spent nuclear fuel pin. For the measurements, the mirrors were placed at the egress of an access port in a hot cell wall. A coarse collimator in the port restricted radiation from a fuel pin placed in front of the port to fully illuminate the front surface of the mirror assembly (0:5 x 3:8 cm2). The mirrors, consisting of highly polished silicon substrates deposited with WC/SiC multilayer coatings, were successfully used to deflect the lines of interest onto an HPGe detector while the intense primary radiation from the spent fuel was blocked by a lead beam stop. The gamma-ray mirror multilayer coatings used here at ∼100 keV, have been experimentally tested at energies as high as 645 keV, indicating that direct observation of nuclear emission lines from 239Pu should be possible with an appropriately designed optic. (author)

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

    International Nuclear Information System (INIS)

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

    1983-01-01

    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 237 Np/ 233 Pa, 239 Pu, 241 Am, 243 Am/ 239 Np, 60 Co, 125 Sb, 134 137 Cs, and 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

  15. Role of NADP+-dependent isocitrate dehydrogenase (NADP+-ICDH) on cellular defence against oxidative injury by gamma-rays.

    Science.gov (United States)

    Lee, S H; Jo, S H; Lee, S M; Koh, H J; Song, H; Park, J W; Lee, W H; Huh, T L

    2004-09-01

    To investigate the regulation of NADPH-producing isocitrate dehydrogenase (ICDH) in cytosol (IDPc) and mitochondria (IDPm) upon gamma-ray irradiation, and the roles of IDPc and IDPm in the protection against cellular damage induced by gamma-ray irradiation. Changes of IDPc and IDPm proteins upon gamma-ray irradiation to NIH3T3 cells were analysed by immunoblotting. To increase or decrease the expression of IDPc or IDPm, NIH3T3 cells were stably transfected with mouse IDPc or IDPm cDNA in either the sense or the antisense direction. The transfected cells with either increased or decreased IDPc or IDPm were exposed to gamma-rays, and the levels of reactive oxygen species generation, protein oxidation and lipid peroxidation were measured. Both IDPc and IDPm activities were induced by gamma-ray in NIH3T3 cells. Cells with decreased expression of IDPc or IDPm had elevated reactive oxygen species generation, lipid peroxidation and protein oxidation. Conversely, overproduction of IDPc or IDPm protein partially protected the cells from oxidative damage induced by gamma-ray irradiation. The protective role of IDPc and IDPm against gamma-ray-induced cellular damage can be attributed to elevated NADPH, reducing equivalents needed for recycling reduced glutathione in the cytosol and mitochondria. Thus, a primary biological function of the ICDHs may be production of NADPH, which is a prerequisite for some cellular defence systems against oxidative damage.

  16. Constraints on the galactic distribution of cosmic rays from the COS-B gamma-ray data

    International Nuclear Information System (INIS)

    1985-08-01

    The velocity information of the HI and CO observations is used as a distance indicator to ascertain the spatial distribution of the interstellar gas. Using this distance information, the galacto-centric distribution of the gamma-ray emissivity (the production rate per H atom) is determined for three gamma-ray energy ranges from a correlation study of the gamma-ray intensity maps and the gas-tracer maps for selected galacto-centric distance intervals, taking into account the expected IC contribution and pointlike gamma-ray sources. On the assumption that unresolved gamma-ray point sources do not contribute significantly to the observed gamma-ray emission, the gamma-ray emissivity is proportional to the Cosmic ray density and, more specifically, the energy dependence can be used to study separately the distribution of Cosmic ray electrons and nuclei: whereas the emission for the 300 MeV - 5 GeV range is dominated by π 0 -decay, the 70 MeV - 150 MeV range has a large electron bremsstrahlung contribution

  17. Common Gamma-ray Glows above Thunderclouds

    Science.gov (United States)

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

    2013-04-01

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

  18. Studies on the influences of. gamma. -ray irradiation upon food additives, (8). Influences of. gamma. -ray irradiation on polyphosphates in aqueous solution and in 'kamaboko'

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, M; Ishio, S [Kyushu Univ., Fukuoka (Japan). Faculty of Agriculture

    1981-08-01

    The effect of ..gamma..-ray irradiation on polyphosphates in aqueous solution and in ''kamaboko'' was investigated to evaluate the rate of decomposition and to examine the safety of the decomposed products. Tripolyphosphate, pyrophosphate and o-phosphate in aqueous solution were very stable against ..gamma..-ray irradiation, respectively. Tripolyphosphate added to ''surimi'' (minced and washed flesh of Alaska Pollack) completely changed to o-phosphate during the period of processing ''kamaboko'', but pyrophosphate was retained. Pyrophosphate content in ''kamaboko'' decreased in proportion to the dose of ..gamma..-ray. Decreased pyrophosphate was presumed to change into such products as insolubles which can not be extracted with 6% per chloric acid solution. Both tripolyphosphate and pyrophosphate changed enzymatically to o-phosphate. The activity of exopolyphosphatase in ''surimi'' was still retained. Polyphosphates added to ''surimi'' changed completely to o-phosphate during the frozen storage of ''surimi'', therefore, the application of ..gamma..-ray irradiation on ''kamaboko'' was considered not to induce any injurious substances from polyphosphates.

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

    Science.gov (United States)

    Puget, J. L.

    1973-01-01

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

  20. Variable code gamma ray imaging system

    International Nuclear Information System (INIS)

    Macovski, A.; Rosenfeld, D.

    1979-01-01

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

  1. Detection circuit for gamma-ray burst

    International Nuclear Information System (INIS)

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

    1982-01-01

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

  2. Very high energy gamma ray astrophysics

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  3. Gamma ray induced decomposition of lanthanide nitrates

    International Nuclear Information System (INIS)

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

    1992-01-01

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

  4. Very high energy gamma-ray astronomy

    International Nuclear Information System (INIS)

    Weekes, T.C.

    1989-01-01

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

  5. Gamma-Ray Spectrum Analysis Software GDA

    International Nuclear Information System (INIS)

    Wanabongse, P.

    1998-01-01

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

  6. Gamma ray bursts from extragalactic sources

    Science.gov (United States)

    Hoyle, Fred; Burbidge, Geoffrey

    1992-01-01

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

  7. Gamma ray thermometrical facility for nuclear reactor

    International Nuclear Information System (INIS)

    Smith, R.D.; Regazzoni, Pierre.

    1981-01-01

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

  8. Principles and techniques of gamma ray tracers

    International Nuclear Information System (INIS)

    Claxton, K.T.

    1978-01-01

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

  9. Gamma ray constraints on decaying dark matter

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  10. Gamma ray spectroscopy with Arduino UNO

    Science.gov (United States)

    Lavelle, C. M.

    2018-05-01

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

  11. Comptonization of gamma rays by cold electrons

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  12. Recent developments in airborne gamma ray surveying

    International Nuclear Information System (INIS)

    Grasty, Robert L.

    1999-01-01

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

  13. Contribution to gamma ray transport calculation in heterogeneous media

    International Nuclear Information System (INIS)

    Bourdet, L.

    1985-04-01

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

  14. Review of GRANAT observations of gamma-ray bursts

    DEFF Research Database (Denmark)

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

    1995-01-01

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

  15. Microwave-gamma ray water in crude monitor

    International Nuclear Information System (INIS)

    Paap, H.J.

    1984-01-01

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

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

    International Nuclear Information System (INIS)

    Grenier, Isabelle

    2009-01-01

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

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

    CERN Document Server

    Marel, J V D

    2001-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-10

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

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

    Science.gov (United States)

    Hümmer, Svenja; Baerwald, Philipp; Winter, Walter

    2012-06-08

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

  20. Fundamentals of gamma-ray measurements and radiometric analyses

    International Nuclear Information System (INIS)

    Hochel, R.C.

    1990-01-01

    There are four primary modes of radioactive decay. All can be measured using various types of detectors and are the basis of many analytical techniques and much of what we know about the nucleus and its structure. Alpha particle emission occurs mostly in heavy nuclei of atomic number, Z, greater than 82 like Po, Ra, Th, and U, etc. Beta particles are simply electrons. They are emitted from the nucleus with a distribution of energies ranging from 0--3 MeV. Gamma-rays are photons with energies ranging from a few keV to 10 MeV or more. They usually follow alpha or beta decay, and depending on their energy, can have considerable range in matter. Neutrons are emitted in fission processes and also from a few of the highly excited fission product nuclei. Fission neutrons typically have energies of 1--2 MeV. Like gamma-rays, they have long ranges. The energies involved in nuclear decay processes are much higher than anything encountered in, say, chemical reactions. They are at the very top of the electromagnetic spectrum -- about a million times more energetic than visible light. As a result, these particles always produce ionization, either directly or indirectly, as they pass through matter. It is this ionization which is the basis of all radiation detectors

  1. Using Gamma Rays to Improve Nutritional Value of Legumes

    International Nuclear Information System (INIS)

    Sajet, A.S.

    2009-01-01

    World is suffering from food shortages and rising prices of animal food, in particular. Therefore, attention turned to fill the shortfall by increasing the production and consumption of pulses. Beans are the most important types of legumes consumed in the countries of the Middle East. But there are some factors that reduce the expansion in the consumption of beans and some factors discourage feeding the trypsin inhibitor,phytic acid, causes of gases and allergens in some people, which negatively affect the bioavailability to absorb the vital minerals and proteins in addition to the length of time needed for cooking beans. There have been attempts to use gamma rays to improve strength and Leakage and cooking recipes for legumes, and reached results in other studies to reduce the efficiency of trypsin inhibitor in beans treated at a dose of 10 kGy as well as achieving the highest percentage reduction in phytic acid content of the same seed above. Also it was found that gamma rays affect negatively on the causes of gases in the beans, radiation works to break down some of the Oligosaccharides and turn it into simple sugars, as well as to break down some of the compounds which are responsible of disease in beans.

  2. High Energy Gamma-rays from FR I Jets

    CERN Document Server

    Sikora, M

    2003-01-01

    Thanks to Hubble and Chandra telescopes, some of the large scale jets in extragalactic radio sources are now being observed at optical and X-ray frequencies. For the FR I objects the synchrotron nature of this emission is surely established, although a lot of uncertainties--connected for example with the particle acceleration processes involved--remain. In this paper we study production of high energy gamma-rays in FR I kiloparsec-scale jets by inverse-Compton emission of the synchrotron-emitting electrons. We consider different origin of seed photons contributing to the inverse-Compton scattering, including nuclear jet radiation as well as ambient, stellar and circumstellar emission of the host galaxies. We discuss how future detections or non-detections of the evaluated gamma-ray fluxes can provide constraints on the unknown large scale jet parameters, i.e. the magnetic field intensity and the jet Doppler factor. For the nearby sources Centaurus A and M 87, we find measurable fluxes of TeV photons resulting...

  3. Near stellar sources of gamma-ray bursts

    OpenAIRE

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

    2012-01-01

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

  4. Fermi GBM Observations of Terrestrial Gamma-Ray Flashes

    Science.gov (United States)

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

    2010-01-01

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

  5. Gamma-ray transients and related astrophysical phenomena

    International Nuclear Information System (INIS)

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

    1982-01-01

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

  6. Multiphase Venturi Dual Energy Gamma Ray combination performance in NUEX flow loop; Desempenho no flowloop do NUEX da medicao multifasica Venturi Dual Energy Gamma Ray

    Energy Technology Data Exchange (ETDEWEB)

    Barreiros, Claudio; Taranto, Cleber; Costa, Alcemir [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Pinguet, Bruno; Heluey, Vitor; Bessa, Fabiano; Loicq, Olivier [Schlumberger Servicos de Petroleo Ltda., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The Multiphase Venturi Dual Energy Gamma Ray Combination, Vx* technology, arrived in Brazil in 2000. PETROBRAS, Brazilian Oil Company, has been putting big efforts in its production business and also has demonstrated a large interest in having a multiphase meter approved by ANP for back allocation purposes. The oil industry was looking for ways to improve the back allocation process using an approved on line multiphase flow measurement device, thus replacing punctual test done today by a permanent monitoring device. Considering this scenario, a partnership project between PETROBRAS and Schlumberger was created in Brazil. The main objective of this project, which was held in NUEX flow loop, was to demonstrate to INMETRO (Brazilian Metrology Institute) that the Multiphase Venturi Dual Energy Gamma Ray Combination meter is able to be used for back allocation purpose. PETROBRAS and Schlumberger elaborated a complete methodology in the NUEX flow loop to demonstrate the results and benefits of the Multiphase Venturi Dual Energy Gamma Ray Combination meter. The test was witnessed by INMETRO and had a very good performance at the end. The results were within what was expected by Schlumberger, PETROBRAS and INMETRO. These results has been very useful to PETROBRAS in order to start using the Venturi Dual Energy Gamma Ray technology for well allocation purposes. (author)

  7. Very high energy gamma ray astrophysics

    International Nuclear Information System (INIS)

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

    1990-02-01

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

  8. Spectra of {gamma} rays feeding superdeformed bands

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-08-01

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

  9. Determination of protein content in seeds by prompt gamma-ray spectrometry

    International Nuclear Information System (INIS)

    Carbonari, A.W.; Pecequilo, B.R.S.

    1984-01-01

    The protein level in seeds can be directly calculated through the determination of the nitrogen content in grains. The authors show here that the radioactive thermal neutron capture prompt gamma-rays technique can be used to determine the nitrogen content in grains without chemical destruction, with good precision and relative rapidity, by detecting the prompt gamma rays emitted by the 14 N(n,γ) 15 N reaction product. The samples were irradiated in the tangential tube of the IEA-R1 research reactor, in Sao Paulo, and a pair spectrometer was used for the detection of the prompt gamma-rays. The nitrogen content was determined in several samples of soybean, common bean, peas and rice and the results compared with typical nitrogen content values for each grain. 33 references, 1 figure, 1 table

  10. Disentangling the gamma-ray emission towards Cygnus X: Sh2-104

    Science.gov (United States)

    Gotthelf, Eric

    2015-09-01

    We have just discovered distinct X-ray emission coincident with VER J2018+363, a TeV source recently resolved from the giant gamma-ray complex MGRO J2019+37 in the Cygnus region. NuSTAR reveals a hard point source and a diffuse nebula adjacent to and possibly part of Sh2-104, a compact HII region containing several young massive stellar clusters. There is reasonable evidence that these X-rays probe the origin of the gamma-ray flux, however, unrelated extragalactic sources need to be excluded. We propose a short Chandra observation to localize the X-ray emission to identify a putative pulsar or stellar counterpart(s). This is an important step to fully understand the energetics of the MGRO J2019+37 complex and the production of gamma-rays in star formation regions, in general.

  11. GRAP, Gamma-Ray Level-Scheme Assignment

    International Nuclear Information System (INIS)

    Franklyn, C.B.

    2002-01-01

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

  12. X-ray echoes from gamma-ray bursts

    International Nuclear Information System (INIS)

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

    1991-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-05-15

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

  14. Gamma-Ray Pulsars: Beaming Evolution, Stats and Unident. EGRET Sources

    OpenAIRE

    Yadigaroglu, I. -A.; Romani, Roger W.

    1994-01-01

    We compute the variation of the beaming fraction with the efficiency of high energy gamma-ray production in the outer gap pulsar model of Romani and Yadigaroglu. This allows us to correct the fluxes observed for pulsars in the EGRET band and to derive a simple estimate of the variation of efficiency with age. Integration of this model over the population of young neutron stars gives the expected number of gamma-ray pulsars along with their distributions in age and distance. This model also sh...

  15. Gamma rays and the case for baryon symmetric big-bang cosmology

    Science.gov (United States)

    Stecker, F. W.

    1977-01-01

    The baryon symmetric big-bang cosmologies offer an explanation of the present photon-baryon ratio in the universe, the best present explanation of the diffuse gamma-ray background spectrum in the 1 to 200 MeV range, and a mechanism for galaxy formation. In the context of an open universe model, the value of omega which best fits the present gamma-ray data is omega equals approx. 0.1 which does not conflict with upper limits on Comptonization distortion of the 3K background radiation. In regard to He production, evidence is discussed that nucleosynthesis of He may have taken place after the galaxies were formed.

  16. Observation of solar gamma-ray by Hinotori

    International Nuclear Information System (INIS)

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

    1982-01-01

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

  17. GROSS- GAMMA RAY OBSERVATORY ATTITUDE DYNAMICS SIMULATOR

    Science.gov (United States)

    Garrick, J.

    1994-01-01

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

  18. Delayed Fission Gamma-ray Characteristics of Th-232 U-233 U-235 U-238 and Pu-239

    Energy Technology Data Exchange (ETDEWEB)

    Lane, Taylor [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Parma, Edward J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-08-01

    Delayed fission gamma-rays play an important role in determining the time dependent ioniz- ing dose for experiments in the central irradiation cavity of the Annular Core Research Reactor (ACRR). Delayed gamma-rays are produced from both fission product decay and from acti- vation of materials in the core, such as cladding and support structures. Knowing both the delayed gamma-ray emission rate and the time-dependent gamma-ray energy spectrum is nec- essary in order to properly determine the dose contributions from delayed fission gamma-rays. This information is especially important when attempting to deconvolute the time-dependent neutron, prompt gamma-ray, and delayed gamma-ray contribution to the response of a diamond photo-conducting diode (PCD) or fission chamber in time frames of milliseconds to seconds following a reactor pulse. This work focused on investigating delayed gamma-ray character- istics produced from fission products from thermal, fast, and high energy fission of Th-232, U-233, U-235, U-238, and Pu-239. This work uses a modified version of CINDER2008, a transmutation code developed at Los Alamos National Laboratory, to model time and energy dependent photon characteristics due to fission. This modified code adds the capability to track photon-induced transmutations, photo-fission, and the subsequent radiation caused by fission products due to photo-fission. The data is compared against previous work done with SNL- modified CINDER2008 [ 1 ] and experimental data [ 2 , 3 ] and other published literature, includ- ing ENDF/B-VII.1 [ 4 ]. The ability to produce a high-fidelity (7,428 group) energy-dependent photon fluence at various times post-fission can improve the delayed photon characterization for radiation effects tests at research reactors, as well as other applications.

  19. Practice for dosimetry for a self-contained dry-storage gamma-ray irradiator

    International Nuclear Information System (INIS)

    2002-01-01

    This practice outlines dosimetric procedures to be followed with self-contained dry-storage gamma-ray irradiators. If followed, these procedures will help to ensure that calibration and testing will be carried out with acceptable precision and accuracy and that the samples processed with ionizing radiation from gamma rays in a self-contained dry-storage irradiator receive absorbed doses within a predetermined range. This practice covers dosimetry in the use of dry-storage gamma-ray irradiators, namely self-contained dry storage 137 Cs or 60 Co irradiators (shielded free-standing irradiators). It does not cover underwater pool sources, panoramic gamma-ray sources such as those raised mechanically or pneumatically to irradiate isotropically into a room or through a collimator, nor does it cover self-contained bremsstrahlung x-ray units. The absorbed dose range for the use of the dry-storage self-contained gamma-ray irradiators covered by this practice is typically 1 to 10 5 Gy, depending on the application. The absorbed-dose rate range typically is from 10 -2 to 10 3 Gy/min. This practice describes general procedures applicable to all self-contained dry-storage gamma-ray irradiators. For procedures specific to dosimetry in blood irradiation, see ISO/ ASTM Practice 51939. For procedures specific to dosimetry in radiation research on food and agricultural products, see ISO/ASTM Practice 51900. For procedures specific to radiation hardness testing, see ASTM Practice E 1249. For procedures specific to the dosimetry in the irradiation of insects for sterile release programs, see ISO/ASTM Guide 51940. In those cases covered by ISO/ASTM Practices 51939, 51900, 51940, or ASTM E 1249, those standards take precedence. In addition, this practice does not cover absorbed-dose rate calibrations of radiation protection instrumentation

  20. Evaluation and improvement of gamma-ray stability of chelating resins containing oxy-acid groups of phosphorus

    International Nuclear Information System (INIS)

    Jyo, Akinori; Yamabe, Kazunori; Shuto, Taketomi

    1998-01-01

    Chelating resins containing oxy-acid groups of phosphorus, such as phosphonic and phosphoric acid groups have been studied from the point of view of solvent extraction processes for the separation of nuclear fuel elements as well as of fission product ones. The present work was planned to evaluate the effect of gamma-ray on properties of the resins and to obtain directional information for design of the resins having high stability to gamma-ray. It was clarified that gamma-ray stability of the resins is not high; tolerance limit is ca. 2.3x10 3 C/kg. The present work also clarified that polymers crosslinked with divinylbenzene have much higher gamma-ray stability than ones crosslinked with dimetacrylate esters of oligo (ethylene glycol)s. (J.P.N.)

  1. Application of the self-powered detector concept in the design of a threshold gamma-ray detector

    International Nuclear Information System (INIS)

    LeVert, F.E.

    1979-01-01

    The self-powered detector concept has been utilized to develop an energy threshold gamma-ray detector. Gamma-ray energy discrimination is achieved by using a thick annular lead shield around the outer wall (emitter) of the detector in conjunction with a self-shielding central electrode (collector). Measurements conducted in the graphite pit of the Argonne Thermal Source Reactor have confirmed its ability to detect high-energy prompt fission gamma rays while discriminating against a significant flux of low-energy gamma rays from the decay of fission products. Also, auto-power spectral densities obtained with the detector were used to estimate the kinetic parameter, β/l, of the reactor

  2. Erratum (astro-ph/0510172) Robust Limits on Lorentz Violation from Gamma-Ray Bursts

    CERN Document Server

    AUTHOR|(CDS)2108556; Nanopoulos, D V; Sakharov, Alexander S; Sarkisyan-Grinbaum, E

    2008-01-01

    We correct the fitting formula used in refs. [1,2] to obtain a robust limit on a violation of Lorentz invariance that depends linearly on the photon energy. The correction leads to a slight increase of the limit on the scale of the violation, to M > 1.4 x 10^{16} GeV.

  3. Cosmological Gamma-Ray Bursts and Hypernovae Conclusively Linked

    Science.gov (United States)

    2003-06-01

    . Thousands of years prior to this explosion, a very massive star, running out of hydrogen fuel, let loose much of its outer envelope, transforming itself into a bluish Wolf-Rayet star [3]. The remains of the star contained about 10 solar masses worth of helium, oxygen and heavier elements. In the years before the explosion, the Wolf-Rayet star rapidly depleted its remaining fuel. At some moment, this suddenly triggered the hypernova/gamma-ray burst event. The core collapsed, without the outer part of the star knowing. A black hole formed inside, surrounded by a disk of accreting matter. Within a few seconds, a jet of matter was launched away from that black hole. The jet passed through the outer shell of the star and, in conjunction with vigorous winds of newly formed radioactive nickel-56 blowing off the disk inside, shattered the star. This shattering, the hypernova, shines brightly because of the presence of nickel. Meanwhile, the jet plowed into material in the vicinity of the star, and created the gamma-ray burst which was recorded some 2,650 million years later by the astronomers on Earth. The detailed mechanism for the production of gamma rays is still a matter of debate but it is either linked to interactions between the jet and matter previously ejected from the star, or to internal collisions inside the jet itself. This scenario represents the "collapsar" model, introduced by American astronomer Stan Woosley (University of California, Santa Cruz) in 1993 and a member of the current team, and best explains the observations of GRB 030329. " This does not mean that the gamma-ray burst mystery is now solved ", says Woosley . " We are confident now that long bursts involve a core collapse and a hypernova, likely creating a black hole. We have convinced most skeptics. We cannot reach any conclusion yet, however, on what causes the short gamma-ray bursts, those under two seconds long ."

  4. Gravitational wave: gamma-ray burst connections.

    Science.gov (United States)

    Hough, Jim

    2007-05-15

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

  5. Gamma-ray burst theory after Swift.

    Science.gov (United States)

    Piran, Tsvi; Fan, Yi-Zhong

    2007-05-15

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

  6. New possibilities in prompt gamma ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

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

    1977-01-01

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

  7. Dosimetry for terrestrial gamma-ray sources

    International Nuclear Information System (INIS)

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

    1975-01-01

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

  8. A review of gamma ray bursts

    CERN Document Server

    Rees, Martin J

    2000-01-01

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

  9. Gamma-ray induced doppler broadening

    International Nuclear Information System (INIS)

    Robinson, S.J.

    1992-01-01

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

  10. Gamma-Ray Bursts: A Radio Perspective

    Directory of Open Access Journals (Sweden)

    Poonam Chandra

    2016-01-01

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

  11. Gamma-Ray Burst Prompt Correlations

    Directory of Open Access Journals (Sweden)

    M. G. Dainotti

    2018-01-01

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

  12. Nuclear gamma ray lines from supernovae

    International Nuclear Information System (INIS)

    Jardim, J.O.D.

    1980-01-01

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

  13. Theoretical Study of Gamma-ray Pulsars

    Directory of Open Access Journals (Sweden)

    Kwong Sang Cheng

    2016-06-01

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

  14. On the transparency of the metagalaxy to ultrahigh-energy gamma rays

    International Nuclear Information System (INIS)

    Aharonyan, F.A.; Vardanyan, V.V.

    1987-01-01

    The electron-photon shower production in the field of the microwave background radiation (MBR) is considered. The absolute flux of ultrahigh-energy cascade gamma-rays (E>or approx.5X10 19 eV), resulting from the Π-meson photoproduction in the field of the MBR is obtained

  15. Gamma-ray scintillation counter hodoscope for the experiment S140

    CERN Multimedia

    CERN PhotoLab

    1975-01-01

    The experiment S140 was set-up in the East Hall (beam p14) by the CERN-Munich-Cracow Collaboration to study the production by negative kaons of a neutral meson associated to a Lambda. Here, the liquid hydrogen target (inside the horizontal black tube) is withdrawn from the surrounding cylindrical gamma-ray-measuring scintillation counter hodoscope.

  16. Gamma ray induced somatic mutations in rose

    International Nuclear Information System (INIS)

    Datta, S.K.

    1989-01-01

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

  17. Activation of wine bentonite with gamma rays

    International Nuclear Information System (INIS)

    Goranov, N.; Antonov, M.

    1997-01-01

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

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

    DEFF Research Database (Denmark)

    Hovgaard, Jens

    1997-01-01

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

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

    International Nuclear Information System (INIS)

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

    1990-01-01

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

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

    African Journals Online (AJOL)

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

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

    NARCIS (Netherlands)

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

    2010-01-01

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

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  3. Gamma ray bursts observed with WATCH‐EURECA

    DEFF Research Database (Denmark)

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

    1994-01-01

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

  4. The many phases of gamma-ray burst afterglows

    NARCIS (Netherlands)

    Leventis, K.

    2013-01-01

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

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

    International Nuclear Information System (INIS)

    Meegan, C.A.

    1990-04-01

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

  6. Supernova sheds light on gamma-ray bursts

    CERN Multimedia

    2003-01-01

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

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

    NARCIS (Netherlands)

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

    2011-01-01

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

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

    NARCIS (Netherlands)

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

    2010-01-01

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

  9. Observational techniques of gamma rays astronomy in low energy

    International Nuclear Information System (INIS)

    Costa, J.M. da.

    1982-02-01

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

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  11. Bulk density calculations from prompt gamma ray yield

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  12. Discoveries by the Fermi Gamma Ray Space Telescope

    Science.gov (United States)

    Gehrels, Neil

    2011-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-10-10

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

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

    Science.gov (United States)

    Hjorth, Jens

    2013-06-13

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

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

    International Nuclear Information System (INIS)

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

    1998-01-01

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

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

    International Nuclear Information System (INIS)

    Lu Tan; Dai Zigao

    2001-01-01

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

  17. Multiwavelength Study of Gamma-Ray Bright Blazars

    Science.gov (United States)

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

    2011-01-01

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

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

    Science.gov (United States)

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

    1980-01-01

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

  19. gamma-ray spectra measurements for long cooled MOX spent fuels

    International Nuclear Information System (INIS)

    Murakami, Kiyonobu; Kobayashi, Iwao

    1993-09-01

    Gamma-ray spectra of spent fuels have important informations in the estimation of burnup rate, concentration of fission products, cooling time and etc. which are required in the fuel loading control of reactors and special nuclear materials accountancy from the view point of safe guard. Although, some available data are given about uranium dioxide fuels, few data are given about uranium and plutonium dioxide mixtures (MOX fuels). Especially, there is few data about MOX fuels which are irradiated in thermal reactors and cooled more than ten years. Gamma-ray spectra are measured for PuO 2 -UO 2 fuel rods (IFA-159, IFA-160) which are irradiated at HBWR in Norway up to 9,420 and 5,340MWd/t respectively. Gamma-ray spectra had been measured about the two fuels ten years ago at the spent fuel pond of Japan Demonstration Reactor (JPDR). The objectives of this measurement is to know how decayed the gamma-ray spectra in these ten years and some fission products are there which are effective to estimate burnup rate of spent MOX fuels. (author)

  20. Gamma ray sensitivity of superheated liquid

    International Nuclear Information System (INIS)

    Sawamura, Teruko; Sugiyama, Noriyuki; Narita, Masakuni

    2000-01-01

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

  1. Effect of {gamma}-ray irradiation on the magnetic properties of NdFeB and Fe-Cr-Co permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Gao, R.S. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhen, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)]. E-mail: zhenl@hit.edu.cn; Li, G.A. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xu, C.Y. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Shao, W.Z. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2006-07-15

    The effect of {gamma}-ray irradiation on the magnetic properties of NdFeB and Fe-Cr-Co permanent magnets has been investigated. The magnetic flux loss of two kinds of magnets before and after irradiation was measured. Results show that the effect of {gamma}-ray irradiation on the magnetic properties of sintered NdFeB is not so obvious as that on Fe-Cr-Co magnet. Irradiation-induced damage from {gamma}-ray for the Fe-Cr-Co magnets was characterized for the first time. The decline of permanent magnetic properties of Fe-Cr-Co magnet induced by {gamma}-ray irradiation is reversible except for the maximum energy product (BH){sub max}. The difference of coercivity mechanism between these two kinds of permanent magnets is responsible for the different dependence of magnetic properties loss induced by {gamma}-ray irradiation.

  2. ICF gamma-ray reaction history diagnostics

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  3. ICF gamma-ray reaction history diagnostics

    Science.gov (United States)

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

    2010-08-01

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

  4. The Extragalactic Background Light and the Gamma-ray Opacity of the Universe

    Science.gov (United States)

    Dwek, Eli; Krennrich, Frank

    2012-01-01

    The extragalactic background light (EBL) is one of the fundamental observational quantities in cosmology. All energy releases from resolved and unresolved extragalactic sources, and the light from any truly diffuse background, excluding the cosmic microwave background (CMB), contribute to its intensity and spectral energy distribution. It therefore plays a crucial role in cosmological tests for the formation and evolution of stellar objects and galaxies, and for setting limits on exotic energy releases in the universe. The EBL also plays an important role in the propagation of very high energy gamma-rays which are attenuated en route to Earth by pair producing gamma-gamma interactions with the EBL and CMB. The EBL affects the spectrum of the sources, predominantly blazars, in the approx 10 GeV to 10 TeV energy regime. Knowledge of the EBL intensity and spectrum will allow the determination of the intrinsic blazar spectrum in a crucial energy regime that can be used to test particle acceleration mechanisms and VHE gamma-ray production models. Conversely, knowledge of the intrinsic gamma-ray spectrum and the detection of blazars at increasingly higher redshifts will set strong limits on the EBL and its evolution. This paper reviews the latest developments in the determination of the EBL and its impact on the current understanding of the origin and production mechanisms of gamma-rays in blazars, and on energy releases in the universe. The review concludes with a summary and future directions in Cherenkov Telescope Array techniques and in infrared ground-based and space observatories that will greatly improve our knowledge of the EBL and the origin and production of very high energy gamma-rays.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  6. Guidelines for radioelement mapping using gamma ray spectrometry data

    International Nuclear Information System (INIS)

    2003-07-01

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

  7. Design Study for Direction Variable Compton Scattering Gamma Ray

    Science.gov (United States)

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

    2013-03-01

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

  8. GAMMA-RAYS FROM THE QUASAR PKS 1441+25: STORY OF AN ESCAPE

    Energy Technology Data Exchange (ETDEWEB)

    Abeysekara, A. U. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Archambault, S. [Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada); Archer, A.; Buckley, J. H.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Aune, T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Barnacka, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Benbow, W.; Cerruti, M. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Bird, R. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Biteau, J. [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Cardenzana, J. V. [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Chen, X. [Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam-Golm (Germany); 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); Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Coppi, P. [Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States); Cui, W. [Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907 (United States); Dickinson, H. J.; Dumm, J., E-mail: matteo.cerruti@cfa.harvard.edu, E-mail: caajohns@ucsc.edu, E-mail: jbiteau@ucsc.edu, E-mail: biteau@ipno.in2p3.fr, E-mail: mcerruti@lpnhe.in2p3.fr, E-mail: mark.lang@nuigalway.ie [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Collaboration: VERITAS; SPOL; ASAS-SN; OVRO; NuSTAR; CRTS; and others

    2015-12-20

    Outbursts from gamma-ray quasars provide insights on the relativistic jets of active galactic nuclei and constraints on the diffuse radiation fields that fill the universe. The detection of significant emission above 100 GeV from a distant quasar would show that some of the radiated gamma-rays escape pair-production interactions with low-energy photons, be it the extragalactic background light (EBL), or the radiation near the supermassive black hole lying at the jet’s base. VERITAS detected gamma-ray emission up to ∼200 GeV from PKS 1441+25 (z = 0.939) during 2015 April, a period of high activity across all wavelengths. This observation of PKS 1441+25 suggests that the emission region is located thousands of Schwarzschild radii away from the black hole. The gamma-ray detection also sets a stringent upper limit on the near-ultraviolet to near-infrared EBL intensity, suggesting that galaxy surveys have resolved most, if not all, of the sources of the EBL at these wavelengths.

  9. Multi-messenger Light Curves from Gamma-Ray Bursts in the Internal Shock Model

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, Mauricio [Center for Cosmology and AstroParticle Physics (CCAPP), The Ohio State University, Columbus, OH 43210 (United States); Heinze, Jonas; Winter, Walter [Deutsches Elektronen-Synchrotron (DESY), Platanenallee 6, D-15738 Zeuthen (Germany); Murase, Kohta, E-mail: bustamanteramirez.1@osu.edu, E-mail: walter.winter@desy.de, E-mail: jonas.heinze@desy.de, E-mail: murase@psu.edu [Center for Particle and Gravitational Astrophysics, The Pennsylvania State University, University Park, PA16802 (United States)

    2017-03-01

    Gamma-ray bursts (GRBs) are promising as sources of neutrinos and cosmic rays. In the internal shock scenario, blobs of plasma emitted from a central engine collide within a relativistic jet and form shocks, leading to particle acceleration and emission. Motivated by present experimental constraints and sensitivities, we improve the predictions of particle emission by investigating time-dependent effects from multiple shocks. We produce synthetic light curves with different variability timescales that stem from properties of the central engine. For individual GRBs, qualitative conclusions about model parameters, neutrino production efficiency, and delays in high-energy gamma-rays can be deduced from inspection of the gamma-ray light curves. GRBs with fast time variability without additional prominent pulse structure tend to be efficient neutrino emitters, whereas GRBs with fast variability modulated by a broad pulse structure can be inefficient neutrino emitters and produce delayed high-energy gamma-ray signals. Our results can be applied to quantitative tests of the GRB origin of ultra-high-energy cosmic rays, and have the potential to impact current and future multi-messenger searches.

  10. Effect of gamma-ray on olive fruits quality, enzyme activities and issued oil

    International Nuclear Information System (INIS)

    Mejri, Sonia

    2007-01-01

    The results described in the present work concern the study of changes in gamma ray irradiated olive fruit (Tunisian variety: C hemlali ) quality along the storage time processing and the quality of olive oil issued. The study focused on the changes related to the microbiological, physico-chemical properties, as well as pectinase activities in olive after irradiation. We also have been interested in the final product quality after oil extraction. The results of non irradiated olives were presented for comparative purposes. Mature olive fruits were treated with 0.5, 1 and 1.5 kGy gamma ray radiation. Olive fruits were then stored for one month. Irradiation at 1.5 kGy allows the almost total destruction of the total aerobic germs, yeasts and moulds. Concerning physico-chemical parameters, the increase of the dose level generated an improvement in water retention capacity and decreased the rate of polysaccharides hydrolyzes olives. Moreover, the irradiation dose of 0.5 kGy induced the increase in pectinase activities thanks to the improvement of the protein extraction yield. The gamma ray irradiation of olive fruit seems to not decrease olive oil oxidative stability in the studied samples. Finally, gamma ray radiation was able to improve the yield of extraction of the oil and insaponifiable fraction as polyphenols and beta carotenes. (Author)

  11. Multi-messenger light curves from gamma-ray bursts in the internal shock model

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, Mauricio [Ohio State Univ., Columbus, OH (United States). Center for Cosmology and AstroParticle Physics (CCAPP); Ohio State Univ., Columbus, OH (United States). Dept. of Physics; Murase, Kohta [Pennsylvania State Univ., University Park, PA (United States). Center for Particle and Gravitational Astrophysics; Pennsylvania State Univ., University Park, PA (United States). Dept. of Astronomy and Astrophysics; Winter, Walter [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2016-06-15

    Gamma-ray bursts (GRBs) are promising as sources of neutrinos and cosmic rays. In the internal shock scenario, blobs of plasma emitted from a central engine collide within a relativistic jet and form shocks, leading to particle acceleration and emission. Motivated by present experimental constraints and sensitivities, we improve the predictions of particle emission by investigating time-dependent effects from multiple shocks. We produce synthetic light curves with different variability timescales that stem from properties of the central engine. For individual GRBs, qualitative conclusions about model parameters, neutrino production efficiency, and delays in high-energy gamma rays can be deduced from inspection of the gamma-ray light curves. GRBs with fast time variability without additional prominent pulse structure tend to be efficient neutrino emitters, whereas GRBs with fast variability modulated by a broad pulse structure tend to be inefficient neutrino emitters and produce delayed high-energy gamma-ray signals. Our results can be applied to quantitative tests of the GRB origin of ultra-high-energy cosmic rays, and have the potential to impact current and future multi-messenger searches.

  12. Limits on the space density of gamma-ray burst sources

    International Nuclear Information System (INIS)

    Epstein, R.I.

    1985-01-01

    Gamma-ray burst spectra which extend to several MeV without significant steepening indicate that there is negligible degradation due to two-photon pair production. The inferred low rate of photon-photon reactions is used to give upper limits to the distances to the sources and to the intensity of the radiation from the sources. These limits are calculated under the assumptions that the bursters are neutron stars which emit uncollimated gamma rays. The principal results are that the space density of the gamma-ray burst sources exceeds approx.10 -6 pc -3 if the entire surface of the neutron star radiates and exceeds approx.10 -3 pc -3 if only a small cap or thin strip in the stellar surface radiates. In the former case the density of gamma-ray bursters is approx.1% of the inferred density of extinct pulsars, and in the latter case the mean mass density of burster sources is a few percent of the density of unidentified dark matter in the solar neighborhood. In both cases the X-ray intensity of the sources is far below the Rayleigh-Jeans limit, and the total flux is at most comparable to the Eddington limit. This implies that low-energy self-absorption near 10 keV is entirely negligible and that radiation-driven explosions are just barely possible

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

    Energy Technology Data Exchange (ETDEWEB)

    Abramowski, A. [Institut fuer Experimentalphysik, Universitaet Hamburg, Luruper Chaussee 149, D-22761 Hamburg (Germany); Acero, F. [Laboratoire Univers et Particules de Montpellier, Universite Montpellier 2, CNRS/IN2P3, CC 72, Place Eugene Bataillon, F-34095 Montpellier Cedex 5 (France); Aharonian, F.; Bernloehr, K.; Bochow, A. [Max-Planck-Institut fuer Kernphysik, P.O. Box 103980, D-69029 Heidelberg (Germany); Akhperjanian, A. G. [National Academy of Sciences of the Republic of Armenia, Yerevan (Armenia); Anton, G.; Balzer, A.; Brucker, J. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Str. 1, D-91058 Erlangen (Germany); Barnacka, A. [Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw (Poland); Becherini, Y. [APC, AstroParticule et Cosmologie, Universite Paris Diderot, CNRS/IN2P3, CEA/lrfu, Observatoire de Paris, Sorbonne Paris Cite, 10, rue Alice Domon et Leonie Duquet, F-75205 Paris Cedex 13 (France); Becker, J. [Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum und Astrophysik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Birsin, E. [Institut fuer Physik, Humboldt-Universitaet zu Berlin, Newtonstr. 15, D-12489 Berlin (Germany); Biteau, J.; Brun, F. [Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS/IN2P3, F-91128 Palaiseau (France); Boisson, C. [LUTH, Observatoire de Paris, CNRS, Universite Paris Diderot, 5 Place Jules Janssen, F-92190 Meudon (France); Bolmont, J. [LPNHE, Universite Pierre et Marie Curie Paris 6, Universite Denis Diderot Paris 7, CNRS/IN2P3, 4 Place Jussieu, F-75252, Paris Cedex 5 (France); Bordas, P. [Institut fuer Astronomie und Astrophysik, Universitaet Tuebingen, Sand 1, D-72076 Tuebingen (Germany); Brun, P. [CEA Saclay, DSM/IRFU, F-91191 Gif-Sur-Yvette Cedex (France); Bulik, T., E-mail: stefan.ohm@le.ac.uk [Astronomical Observatory, The University of Warsaw, Al. Ujazdowskie 4, 00-478 Warsaw (Poland); Collaboration: H.E.S.S. Collaboration; and others

    2012-10-01

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

  14. The LASL gamma-ray burst astronomy program

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  15. Evaluation of effective dose equivalent from environmental gamma rays

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  16. Cellular response to low Gamma-ray doses

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-07-01

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

  17. High energy photons and neutrinos from gamma ray bursts

    International Nuclear Information System (INIS)

    Dar, A.

    1998-01-01

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

  18. Analytical applications of neutron capture gamma-rays

    International Nuclear Information System (INIS)

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

    1997-01-01

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

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

    DEFF Research Database (Denmark)

    Content, Robert; Content, Robert; Sharples, Ray

    2012-01-01

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

  20. Cellular response to low Gamma-ray doses

    International Nuclear Information System (INIS)

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

    2002-01-01

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

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

    International Nuclear Information System (INIS)

    Schoenfelder, V.

    1989-01-01

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

  2. Gamma ray induced mutants in Coleus

    International Nuclear Information System (INIS)

    Vasudevan, K.; Jos, J.S.

    1988-01-01

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

  3. Observations of short gamma-ray bursts.

    Science.gov (United States)

    Fox, Derek B; Roming, Peter W A

    2007-05-15

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

  4. Gamma ray induced mutants in Coleus

    Energy Technology Data Exchange (ETDEWEB)

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

    1988-07-01

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

  5. Portable high energy gamma ray imagers

    International Nuclear Information System (INIS)

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

    1996-01-01

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

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

    International Nuclear Information System (INIS)

    Lapides, J.R.

    1981-01-01

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

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

    International Nuclear Information System (INIS)

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

    1985-01-01

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

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

    National Research Council Canada - National Science Library

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

    1996-01-01

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

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

    Science.gov (United States)

    Krennrich, Frank

    2009-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-07-01

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

  11. Gamma-ray flares from the Crab Nebula.

    Science.gov (United States)

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

    2011-02-11

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

  12. Some deficiencies and solutions in gamma ray spectrometry

    International Nuclear Information System (INIS)

    Westmeier, W.

    1998-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1992-08-15

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

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

    International Nuclear Information System (INIS)

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

    1985-01-01

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

  15. Saccharification of gamma-ray and alkali pretreated lignocellulosics

    International Nuclear Information System (INIS)

    Begum, A.; Choudhury, N.

    1988-01-01

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

  16. Very high energy gamma ray astronomy from Hanle

    International Nuclear Information System (INIS)

    Chitnis, Varsha R.

    2015-01-01

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

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

    International Nuclear Information System (INIS)

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

    1984-01-01

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

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

    Indian Academy of Sciences (India)

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

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  20. Secondary gamma-ray data for shielding calculation

    International Nuclear Information System (INIS)

    Miyasaka, Sunichi

    1979-01-01

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

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

    Data.gov (United States)

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

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  3. Gamma-ray flares from the Crab nebula

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  4. Exploring the extreme gamma-ray sky with HESS

    International Nuclear Information System (INIS)

    Sol, Helene

    2006-01-01

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

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

    International Nuclear Information System (INIS)

    Ginzburg, V.L.

    1973-01-01

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

  6. Upgrade of the JET gamma-ray cameras

    International Nuclear Information System (INIS)

    Soare, S.; Curuia, M.; Anghel, M.; Constantin, M.; David, E.; Craciunescu, T.; Falie, D.; Pantea, A.; Tiseanu, I.; Kiptily, V.; Prior, P.; Edlington, T.; Griph, S.; Krivchenkov, Y.; Loughlin, M.; Popovichev, S.; Riccardo, V; Syme, B.; Thompson, V.; Lengar, I.; Murari, A.; Bonheure, G.; Le Guern, F.

    2007-01-01

    Full text: The JET gamma-ray camera diagnostics have already provided valuable information on the gamma-ray imaging of fast ion in JET plasmas. The applicability of gamma-ray imaging to high performance deuterium and deuterium-tritium JET discharges is strongly dependent on the fulfilment of rather strict requirements for the characterisation of the neutron and gamma-ray radiation fields. These requirements have to be satisfied within very stringent boundary conditions for the design, such as the requirement of minimum impact on the co-existing neutron camera diagnostics. The JET Gamma-Ray Cameras (GRC) upgrade project deals with these issues with particular emphasis on the design of appropriate neutron/gamma-ray filters ('neutron attenuators'). Several design versions have been developed and evaluated for the JET GRC neutron attenuators at the conceptual design level. The main design parameter was the neutron attenuation factor. The two design solutions, that have been finally chosen and developed at the level of scheme design, consist of: a) one quasi-crescent shaped neutron attenuator (for the horizontal camera) and b) two quasi-trapezoid shaped neutron attenuators (for the vertical one). The second design solution has different attenuation lengths: a short version, to be used together with the horizontal attenuator for deuterium discharges, and a long version to be used for high performance deuterium and DT discharges. Various neutron-attenuating materials have been considered (lithium hydride with natural isotopic composition and 6 Li enriched, light and heavy water, polyethylene). Pure light water was finally chosen as the attenuating material for the JET gamma-ray cameras. The neutron attenuators will be steered in and out of the detector line-of-sight by means of an electro-pneumatic steering and control system. The MCNP code was used for neutron and gamma ray transport in order to evaluate the effect of the neutron attenuators on the neutron field of the

  7. Evaluation of components of X-ray irradiated 7-valent pneumococcal conjugate vaccine and pneumococcal vaccine polyvalent and X-ray and gamma-ray irradiated acellular pertussis component of DTaP vaccine products

    International Nuclear Information System (INIS)

    May, J.C.; Rey, L.; Lee, C.-J.; Arciniega, Juan

    2004-01-01

    Samples of pneumococcal vaccine polyvalent, 7-valent pneumococcal conjugate vaccine, and two different diphtheria and tetanus toxoids and acellular pertussis vaccines adsorbed were irradiated with X-rays and/or gamma-rays (Co-60). Mouse IgG and IgM antibody responses (ELISA) for types 9V, 14, 18C, and 19F pneumococcal polysaccharides and conjugates indicated that the polysaccharides were more tolerant of the radiation than the conjugates. The mouse antibody response for the detoxified pertussis toxin (PT) antigen, filamentous hemagglutinin antigen (FHA), pertactin (PRN), and fimbriae types 2 and 3 (FIM) antigens for the appropriate vaccine type indicated that the antibody response was not significantly changed in the 25 kGy X-ray irradiated vaccines frozen in liquid nitrogen compared to the control vaccine

  8. Evaluation of components of X-ray irradiated 7-valent pneumococcal conjugate vaccine and pneumococcal vaccine polyvalent and X-ray and gamma-ray irradiated acellular pertussis component of DTaP vaccine products

    Energy Technology Data Exchange (ETDEWEB)

    May, J.C. E-mail: may@cber.fda.gov; Rey, L. E-mail: louis.rey@bluewin.ch; Lee, C.-J.; Arciniega, Juan

    2004-10-01

    Samples of pneumococcal vaccine polyvalent, 7-valent pneumococcal conjugate vaccine, and two different diphtheria and tetanus toxoids and acellular pertussis vaccines adsorbed were irradiated with X-rays and/or gamma-rays (Co-60). Mouse IgG and IgM antibody responses (ELISA) for types 9V, 14, 18C, and 19F pneumococcal polysaccharides and conjugates indicated that the polysaccharides were more tolerant of the radiation than the conjugates. The mouse antibody response for the detoxified pertussis toxin (PT) antigen, filamentous hemagglutinin antigen (FHA), pertactin (PRN), and fimbriae types 2 and 3 (FIM) antigens for the appropriate vaccine type indicated that the antibody response was not significantly changed in the 25 kGy X-ray irradiated vaccines frozen in liquid nitrogen compared to the control vaccine.

  9. The Advanced Gamma-ray Imaging System (AGIS): Simulation Studies

    Science.gov (United States)

    Fegan, Stephen; Buckley, J. H.; Bugaev, S.; Funk, S.; Konopelko, A.; Maier, G.; Vassiliev, V. V.; Simulation Studies Working Group; AGIS Collaboration

    2008-03-01

    The Advanced Gamma-ray Imaging System (AGIS) is a concept for the next generation instrument in ground-based very high energy gamma-ray astronomy. It has the goal of achieving significant improvement in sensitivity over current experiments. We present the results of simulation studies of various possible designs for AGIS. The primary characteristics of the array performance, collecting area, angular resolution, background rejection, and sensitivity are discussed.

  10. The Advanced Gamma-ray Imaging System (AGIS): Simulation Studies

    OpenAIRE

    Maier, G.; Collaboration, for the AGIS

    2009-01-01

    The Advanced Gamma-ray Imaging System (AGIS) is a next-generation ground-based gamma-ray observatory being planned in the U.S. The anticipated sensitivity of AGIS is about one order of magnitude better than the sensitivity of current observatories, allowing it to measure gammaray emmission from a large number of Galactic and extra-galactic sources. We present here results of simulation studies of various possible designs for AGIS. The primary characteristics of the array performance - collect...

  11. Significant gamma-ray lines from dark matter annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Duerr, Michael [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Fileviez Perez, Pavel; Smirnov, Juri [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany)

    2016-07-01

    Gamma-ray lines from dark matter annihilation are commonly seen as a ''smoking gun'' for the particle nature of dark matter. However, in many dark matter models the continuum background from tree-level annihilations makes such a line invisible. I present two simple extensions of the Standard Model where the continuum contributions are suppressed and the gamma-ray lines are easily visible over the continuum background.

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

    International Nuclear Information System (INIS)

    Hudec, R.

    1998-01-01

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

  13. Extragalactic Gamma Ray Excess from Coma Supercluster Direction

    Indian Academy of Sciences (India)

    More precise analysis of EGRET data however, makes it possible to estimate the diffuse gamma ray in Coma supercluster (i.e., Coma\\A1367 supercluster) direction with a value of ( > 30MeV) ≃ 1.9 × 10-6 cm-2 s-1, which is considered to be an upper limit for the diffuse gamma ray due to Coma supercluster. The related ...

  14. Population Studies of Radio and Gamma-Ray Pulsars

    Science.gov (United States)

    Harding, Alice K; Gonthier, Peter; Coltisor, Stefan

    2004-01-01

    Rotation-powered pulsars are one of the most promising candidates for at least some of the 40-50 EGRET unidentified gamma-ray sources that lie near the Galactic plane. Since the end of the EGRO mission, the more sensitive Parkes Multibeam radio survey has detected mere than two dozen new radio pulsars in or near unidentified EGRET sources, many of which are young and energetic. These results raise an important question about the nature of radio quiescence in gamma-ray pulsars: is the non-detection of radio emission a matter of beaming or of sensitivity? The answer is very dependent on the geometry of the radio and gamma-ray beams. We present results of a population synthesis of pulsars in the Galaxy, including for the first time the full geometry of the radio and gamma-ray beams. We use a recent empirically derived model of the radio emission and luminosity, and a gamma-ray emission geometry and luminosity derived theoretically from pair cascades in the polar slot gap. The simulation includes characteristics of eight radio surveys of the Princeton catalog plus the Parkes MB survey. Our results indicate that EGRET was capable of detecting several dozen pulsars as point sources, with the ratio of radio-loud to radio-quiet gamma-ray pulsars increasing significantly to about ten to one when the Parkes Survey is included. Polar cap models thus predict that many of the unidentified EGRET sources could be radio-loud gamma- ray pulsars, previously undetected as radio pulsars due to distance, large dispersion and lack of sensitivity. If true, this would make gamma-ray telescopes a potentially more sensitive tool for detecting distant young neutron stars in the Galactic plane.

  15. GLAST, the Gamma-ray Large Area Space Telescope

    CERN Document Server

    De Angelis, A

    2001-01-01

    GLAST, a detector for cosmic gamma rays in the range from 20 MeV to 300 GeV, will be launched in space in 2005. Breakthroughs are expected in particular in the study of particle acceleration mechanisms in space and of gamma ray bursts, and maybe on the search for cold dark matter; but of course the most exciting discoveries could come from the unexpected.

  16. Measuring The Variability Of Gamma-Ray Sources With AGILE

    International Nuclear Information System (INIS)

    Chen, Andrew W.; Vercellone, Stefano; Pellizzoni, Alberto; Tavani, Marco

    2005-01-01

    Variability in the gamma-ray flux above 100 MeV at various time scales is one of the primary characteristics of the sources detected by EGRET, both allowing the identification of individual sources and constraining the unidentified source classes. We present a detailed simulation of the capacity of AGILE to characterize the variability of gamma-ray sources, discussing the implications for source population studies

  17. Physics and astrophysics with gamma-ray telescopes

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-15

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

  18. The MAGIC gamma-ray telescope: status and first results

    International Nuclear Information System (INIS)

    Fernandez, Enrique

    2006-01-01

    MAGIC, a 17 m diameter Cherenkov telescope for gamma ray astronomy, has recently been commissioned at the Roque de los Muchachos site in the Island of La Palma, of the Canary Islands. The telescope was proposed in 1998 with the goal of lowering the threshold of observation of gamma rays by ground detectors to 20-30 GeV energies. This paper describes its main design features, its physics objectives and its first operations

  19. Catalogue of gamma rays from radionuclides ordered by nuclide

    International Nuclear Information System (INIS)

    Ekstroem, L.P.; Andersson, P.; Sheppard, H.M.

    1984-01-01

    A catalogue of about 28500 gamma-ray energies from 2338 radionuclides is presented. The nuclides are listed in order of increasing (A,Z) of the daughter nuclide. In addition the gamma-ray intensity per 100 decays of the parent (if known) and the decay half-life are given. All data are from a computer processing of a recent ENSDF (Evaluated Nuclear Structure Data File) file. (authors)

  20. Computers in activation analysis and gamma-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

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

    1979-01-01

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

  1. Gamma-Ray Imager With High Spatial And Spectral Resolution

    Science.gov (United States)

    Callas, John L.; Varnell, Larry S.; Wheaton, William A.; Mahoney, William A.

    1996-01-01

    Gamma-ray instrument developed to enable both two-dimensional imaging at relatively high spatial resolution and spectroscopy at fractional-photon-energy resolution of about 10 to the negative 3rd power in photon-energy range from 10 keV to greater than 10 MeV. In its spectroscopic aspect, instrument enables identification of both narrow and weak gamma-ray spectral peaks.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-11

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

  3. Neutron and gamma-ray emission double differential cross sections for the nuclear reaction by 1.5 GeV {pi}{sup +} incidence

    Energy Technology Data Exchange (ETDEWEB)

    Iga, Kiminori; Ishibashi, Kenji; Shigyo, Nobuhiro [Kyushu Univ., Fukuoka (Japan)] [and others

    1998-03-01

    Neutron and gamma-ray production double differential cross sections were measured for iron by the use of 1.5 GeV {pi}{sup +} mesons. The measured cross sections were compared with the calculated values by HETC-KFA2. For the neutrons, the calculated results deviate from the experimental data in the neutron energy region below 30 MeV. The calculated values of gamma-ray production agree with the experimental data at gamma-ray energies from 1 to 7 MeV within a factor of three. (author)

  4. Heterogeneity in Short Gamma-Ray Bursts

    Science.gov (United States)

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

    2011-01-01

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

  5. Gamma-ray effect on sweet potato

    International Nuclear Information System (INIS)

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

    1994-01-01

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

  6. HETEROGENEITY IN SHORT GAMMA-RAY BURSTS

    International Nuclear Information System (INIS)

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

    2011-01-01

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

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

    International Nuclear Information System (INIS)

    Carter, J.N.

    1979-09-01

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

  8. The Fermi Gamma-ray Burst Monitor (GBM) Terrestrial Gamma-ray Flash (TGF) Catalog

    Science.gov (United States)

    Briggs, M. S.; Roberts, O.; Fitzpatrick, G.; Stanbro, M.; Cramer, E.; Mailyan, B. G.; McBreen, S.; Connaughton, V.; Grove, J. E.; Chekhtman, A.; Holzworth, R.

    2017-12-01

    The revised Second Fermi GBM TGF catalog includes data on 4144 TGFs detected by the Fermi Gamma-ray Burst Monitor through 2016 July 31. The catalog includes 686 bright TGFs there were detected in orbit and 4135 TGFs that were discovered by ground analysis of GBM data (the two samples overlap). Thirty of the events may have been detected as electrons and positrons rather than gamma-rays: Terrestrial Electron Beams (TEBs). We also provide results from correlating the GBM TGFs with VLF radio detections of the World Wide Lightning Location Network (WWLLN). TGFs with WWLLN associations have their localization uncertainties improved from 800 to 10 km, making it possible to identify specific thunderstorms responsible for the TGFs and opening up new types of scientific investigations. There are 1544 TGFs with WWLLN associations; maps are provided for these and the other TGFs of the catalog. The data tables of the catalog are available for use by the scientific community at the Fermi Science Support Center, at https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/tgf/.

  9. LOCALIZATION OF GAMMA-RAY BURSTS USING THE FERMI GAMMA-RAY BURST MONITOR

    Energy Technology Data Exchange (ETDEWEB)

    Connaughton, V.; Briggs, M. S.; Burgess, J. M. [CSPAR and Physics Department, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Goldstein, A.; Wilson-Hodge, C. A. [Astrophysics Office, ZP12, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Meegan, C. A.; Jenke, P.; Pelassa, V.; Xiong, S.; Bhat, P. N. [CSPAR, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Paciesas, W. S. [Universities Space Research Association, Huntsville, AL (United States); Preece, R. D. [Department of Space Science, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Gibby, M. H. [Jacobs Technology, Inc., Huntsville, AL (United States); Greiner, J.; Yu, H.-F. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Gruber, D. [Planetarium Südtirol, Gummer 5, I-39053 Karneid (Italy); Kippen, R. M. [Los Alamos National Laboratory, NM 87545 (United States); Byrne, D.; Fitzpatrick, G.; Foley, S., E-mail: valerie@nasa.gov [School of Physics, University College Dublin, Belfield, Stillorgan Road, Dublin 4 (Ireland); and others

    2015-02-01

    The Fermi Gamma-ray Burst Monitor (GBM) has detected over 1400 gamma-ray bursts (GRBs) since it began science operations in 2008 July. We use a subset of over 300 GRBs localized by instruments such as Swift, the Fermi Large Area Telescope, INTEGRAL, and MAXI, or through triangulations from the InterPlanetary Network, to analyze the accuracy of GBM GRB localizations. We find that the reported statistical uncertainties on GBM localizations, which can be as small as 1°, underestimate the distance of the GBM positions to the true GRB locations and we attribute this to systematic uncertainties. The distribution of systematic uncertainties is well represented (68% confidence level) by a 3.°7 Gaussian with a non-Gaussian tail that contains about 10% of GBM-detected GRBs and extends to approximately 14°. A more complex model suggests that there is a dependence of the systematic uncertainty on the position of the GRB in spacecraft coordinates, with GRBs in the quadrants on the Y axis better localized than those on the X axis.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  12. Self-powered neutron and gamma-ray flux detector

    International Nuclear Information System (INIS)

    Allan, C.J.; Shields, R.B.; Lynch, G.F.; Cuttler, J.M.

    1980-01-01

    A new type of self-powered neutron detector was developed which is sensitive to both the neutron and gamma-ray fluxes. The emitter comprises two parts. The central emitter core is made of materials that generate high-energy electrons on exposure to neutrons. The outer layer acts as a gamma-ray/electron converter, and since it has a higher atomic number and higher back-scattering coefficient than the collector, increases the net outflow or emmission of electrons. The collector, which is around the emitter outer layer, is insulated from the outer layer electrically with dielectric insulation formed from compressed metal-oxide powder. The fraction of electrons given off by the emitter that is reflected back by the collector is less than the fraction of electrons emitted by the collector that is reflected back by the emitter. The thickness of the outer layer needed to achieve this result is very small. A detector of this design responds to external reactor gamma-rays as well as to neutron capture gamma-rays from the collector. The emitter core is either nickel, iron or titanium, or alloys based on these metals. The outer layer is made of platinum, tantalum, osmium, molybdenum or cerium. The detector is particularly useful for monitoring neutron and gamma ray flux intensities in nuclear reactor cores in which the neutron and gamma ray flux intensities are closely proportional, are unltimately related to the fission rate, and are used as measurements of nuclear reactor power. (DN)

  13. A study on gamma rays from electrochemical cells

    International Nuclear Information System (INIS)

    Shin, Seung Ai

    1993-01-01

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

  14. RADHEAT-V3, a code system for generating coupled neutron and gamma-ray group constants and analyzing radiation transport

    International Nuclear Information System (INIS)

    Koyama, Kinji; Taji, Yukichi; Miyasaka, Shun-ichi; Minami, Kazuyoshi.

    1977-07-01

    The modular code system RADHEAT is for producing coupled multigroup neutron and gamma-ray cross section sets, analyzing the neutron and gamma-ray transport, and calculating the energy deposition and atomic displacements due to these radiations in a nuclear reactor or shield. The basic neutron cross sections and secondary gamma-ray production data are taken from ENDF/B and POPOP4 libraries respectively. The system (1) generates multigroup neutron cross sections, energy deposition coefficients and atomic displacement factors due to neutron reactions, (2) generates multigroup gamma-ray cross sections and energy transfer coefficients, (3) generates secondary gamma-ray production cross sections, (4) combines these cross sections into the coupled set, (5) outputs and updates the multigroup cross section libraries in convenient formats for other transport codes, (6) analyzes the neutron and gamma-ray transport and calculates the energy deposition and the number density of atomic displacements in a medium, (7) collapses the cross sections to a broad-group structure, by option, using the weighting functions obtained by one-dimensional transport calculation, and (8) plots, by option, multigroup cross sections, and neutron and gamma-ray distributions. Definitions of the input data required in various options of the code system are also given. (auth.)

  15. Gamma-ray emission from internal shocks in novae

    Science.gov (United States)

    Martin, P.; Dubus, G.; Jean, P.; Tatischeff, V.; Dosne, C.

    2018-04-01

    Context. Gamma-ray emission at energies ≥100 MeV has been detected from nine novae using the Fermi Large Area Telescope (LAT), and can be explained by particle acceleration at shocks in these systems. Eight out of these nine objects are classical novae in which interaction of the ejecta with a tenuous circumbinary material is not expected to generate detectable gamma-ray emission. Aim. We examine whether particle acceleration at internal shocks can account for the gamma-ray emission from these novae. The shocks result from the interaction of a fast wind radiatively-driven by nuclear burning on the white dwarf with material ejected in the initial runaway stage of the nova outburst. Methods: We present a one-dimensional model for the dynamics of a forward and reverse shock system in a nova ejecta, and for the associated time-dependent particle acceleration and high-energy gamma-ray emission. Non-thermal proton and electron spectra are calculated by solving a time-dependent transport equation for particle injection, acceleration, losses, and escape from the shock region. The predicted emission is compared to LAT observations of V407 Cyg, V1324 Sco, V959 Mon, V339 Del, V1369 Cen, and V5668 Sgr. Results: The ≥100 MeV gamma-ray emission arises predominantly from particles accelerated up to 100 GeV at the reverse shock and undergoing hadronic interactions in the dense cooling layer downstream of the shock. The emission rises within days after the onset of the wind, quickly reaches a maximum, and its subsequent decrease reflects mostly the time evolution of the wind properties. Comparison to gamma-ray data points to a typical scenario where an ejecta of mass 10-5-10-4 M⊙ expands in a homologous way with a maximum velocity of 1000-2000 km s-1, followed within a day by a wind with a velocity values of which result in the majority of best-fit models having gamma-ray spectra with a high-energy turnover below 10 GeV. Our typical model is able to account for the main

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

    Energy Technology Data Exchange (ETDEWEB)

    Atwood, W. B. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Baldini, L. [Universita di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bregeon, J.; Pesce-Rollins, M.; Sgro, C.; Tinivella, M. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bruel, P. [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France); Chekhtman, A. [Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030 (United States); Cohen-Tanugi, J. [Laboratoire Univers et Particules de Montpellier, Universite Montpellier 2, CNRS/IN2P3, F-34095 Montpellier (France); Drlica-Wagner, A.; Omodei, N.; Rochester, L. S.; Usher, T. L. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Granot, J. [Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Ra' anana 43537 (Israel); Longo, F. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Razzaque, S. [Department of Physics, University of Johannesburg, Auckland Park 2006 (South Africa); Zimmer, S., E-mail: melissa.pesce.rollins@pi.infn.it, E-mail: nicola.omodei@stanford.edu, E-mail: granot@openu.ac.il [Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm (Sweden)

    2013-09-01

    Based on the experience gained during the four and a half years of the mission, the Fermi-LAT Collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet finalized, we can test the improvements in the new event reconstruction with the special case of the prompt phase of bright gamma-ray bursts (GRBs), where the signal-to-noise ratio is large enough that loose selection cuts are sufficient to identify gamma rays associated with the source. Using the new event reconstruction, we have re-analyzed 10 GRBs previously detected by the Large Area Telescope (LAT) for which an X-ray/optical follow-up was possible and found four new gamma rays with energies greater than 10 GeV in addition to the seven previously known. Among these four is a 27.4 GeV gamma ray from GRB 080916C, which has a redshift of 4.35, thus making it the gamma ray with the highest intrinsic energy ({approx}147 GeV) detected from a GRB. We present here the salient aspects of the new event reconstruction and discuss the scientific implications of these new high-energy gamma rays, such as constraining extragalactic background light models, Lorentz invariance violation tests, the prompt emission mechanism, and the bulk Lorentz factor of the emitting region.

  17. Factors influencing in situ gamma-ray measurements

    Science.gov (United States)

    Loonstra, E. H.; van Egmond, F. M.

    2009-04-01

    Introduction In situ passive gamma-ray sensors are very well suitable for mapping physical soil properties. In order to make a qualitative sound soil map, high quality input parameters for calibration are required. This paper will focus on the factors that affect the output of in situ passive gamma-ray sensors, the primary source, soil, not taken into account. Factors The gamma-ray spectrum contains information of naturally occurring nuclides 40K, 238U and 232Th and man-made nuclides like 137Cs, as well as the total count rate. Factors that influence the concentration of these nuclides and the count rate can be classified in 3 categories. These are sensor design, environmental conditions and operational circumstances. Sensor design The main elements of an in situ gamma-ray sensor that influence the outcome and quality of the output are the crystal and the spectrum analysis method. Material and size of the crystal determine the energy resolution. Though widely used, NaI crystals are not the most efficient capturer of gamma radiation. Alternatives are BGO and CsI. BGO has a low peak resolution, which prohibits use in cases where man-made nuclides are subject of interest. The material is expensive and prone to temperature instability. CsI is robust compared to NaI and BGO. The density of CsI is higher than NaI, yielding better efficiency, especially for smaller crystal sizes. More volume results in higher energy efficiency. The reduction of the measured spectral information into concentration of radionuclides is mostly done using the Windows analysis method. In Windows, the activities of the nuclides are found by summing the intensities of the spectrum found in a certain interval surrounding a peak. A major flaw of the Windows method is the limited amount of spectral information that is incorporated into the analysis. Another weakness is the inherent use of ‘stripping factors' to account for contributions of radiation from nuclide A into the peak of nuclide B. This

  18. Gamma rays application in veterinary immunology

    International Nuclear Information System (INIS)

    Bulkhanov, R.U.; Butaev, M.K.; Mirzaev, B.Sh.; Ryasnyanskiy, I.V.; Yuldashev, R.Yu.

    2005-01-01

    Full text: The process based on stimulated action of ionized radiation, change of quality of agricultural goods and row materials, biocides including bactericide action of ionized radiation are among the methods of radiation biotechnology, which can be applied in agriculture. We used the bactericide action of ionized radiation in technological process for creation of fundamentally new preparation possessed by by immunogenic properties and named as 'radio vaccine'. This term is well known and frequently used in scientific papers in the field of applied radiobiology. It is well known that physical (thermal) and chemical actions are used for preparation of vaccine for veterinary. It was noted that this process resulted in destruction of antigenic structure of bacteria cells, with are responsible for immunity creation. The possibility of virulence reduction at constant immunogenic properties of microorganism and keeping its antigenic structure can be achieved by using ionized radiation as one of the factor, which influences on bacteria. Taking into account the necessity of vaccine improvement and increase of quantity of associated vaccine one of the most important problems of veterinary science and particle is creation of vaccines of new generation which are characterized by the ability to form immunity against several diseases of agricultural animals. As a result of many-years investigations using gamma rays radiations in UzSRIV (laboratory of radiobiology) the radiation biotechnology of vaccine preparation was developed. These vaccines are necessary for practical application. Radiation biotechnology allows to prepare high-effective mono-, associated and polyvalent radio vaccines against widespread infection diseases of agricultural animals especially cubs (calves, lambs, young pigs). On the basis of developed radiation biotechnology there were prepared the following vaccines: 'Associated radio vaccine against colibacteriosis and salmonellosis of small horned cattle

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

    Science.gov (United States)

    Bussard, R. W.

    1978-01-01

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

  20. The possibility of gamma ray sterilization by using ITU TRIGA Mark II reactor

    International Nuclear Information System (INIS)

    Bilge, A.N.; Tugrul, B.; Yavuz, H.

    1988-01-01

    Gamma rays are one of the effective method for sterilization which is preferred for a long time. Generally Co-60 radioisotope sources betatrons or accelerators are used for the sterilization. In this work, it was aimed to find the possibilities of the sterilization by gamma rays obtained in ITU TRIGA Mark-II radial tube. Radiation dosages are measured in the radial tube and several medical products are irradiated. Irradiation is arranged according to the desired dosages. Irradiated sterilized goods (mainly medical products) tested and checked at the Governmental Medical Health Center and results compared with literature. It can be seen that this kind of irradiation is a good tool for sterilization. Unfortunately, because of the stability of the radial tube and impracticality of the system it is rather difficult to compete with industrial system using Co-60 and accelerators. Nevertheless, this type of irradiation is also applicable for the purpose of the sterilization by using ITU TRIGA Mark II. (author)

  1. Using airborne GAMMA-ray spectrometry (uranium, thorium, potassium) to quantify weathering and erosion processes

    International Nuclear Information System (INIS)

    Carrier, F.

    2005-01-01

    The airborne gamma-ray spectrometry survey carried out on the Armorican Massif provided soil contents in U, Th and K in ppm. Chemical and mechanical erosion processes within a homogeneous geological unit have been estimated using their variations and those of the 137 Cs. Our new approach, based on a multivariate analysis (hierarchic ascending classification), integrates the airborne gamma-ray spectrometry data, with their broad spatial distribution, together with precisely located station data (major elements, traces and isotopic geochemistry) resulting from a soil and river water erosion products survey. The total export of potassium was estimated in any point of an area catchment (50-m resolution) until 17+2 t/km 2 /a for a 50-m thick weathering profile. Erosion study by river sampling provide important biases, for the perennial river does not integrate the whole range of erosion products: the geochemical signature of the valleys is currently more represented than plateau areas. (author)

  2. The generation, validation and testing of a coupled 219-group neutron 36-group gamma ray AMPX-II library

    International Nuclear Information System (INIS)

    Panini, G.C.; Siciliano, F.; Lioi, A.

    1987-01-01

    The main characteristics of a P 3 coupled 219-group neutron 36-group gamma-ray library in the AMPX-II Master Interface Format obtained processing ENDF/B-IV data by means of various AMPX-II System modules are presented in this note both for the more reprocessing aspects and features of the generated component files-neutrons, photon and secondary gamma-ray production cross sections. As far as the neutron data are concerned there is the avaibility of 186 data sets regarding most significant fission products. Results of the additional validation of the neutron data pertaining to eighteen benchmark experiments are also given. Some calculational tests on both neutron and coupled data emphasize the important role of the secondary gamma-ray data in nuclear criticality safety calculations

  3. A commercial gamma-ray irradiation plant in Japan

    International Nuclear Information System (INIS)

    Tomita, K.; Sugimoto, S.

    1977-01-01

    In 1973, a commercial gamma-ray irradiation plant was constructed in Takasaki, about 100 km north of Tokyo. The plant has been used for both production of irradiated commercial products and irradiation services. The irradiation services are being made available for sterilization of both medical appliances such as disposable medical syringes, catheters, surgical sutures, and sterilization of feed stuffs for animals. Treatment of plastic materials and colouring of both crystals and glass wares are also undertaken. This facility can accommodate 600 kCi of 60 Co and has a monthly treating capacity of 12,000 packages ( a standard carton of 340 mm x 400 mm x 500 mm) at an irradiation dose of 1 Mrad/hr. A receiving port for packages is on the second floor and the outlet of the irradiated packages on the first floor, with three lines of connecting loop conveyors between them, and the irradiation compartment in the center section. The space arrangement of the facility is well designed and gravity can be utilized for the transportation of the packages. Polymer impregnated coral is put on the market for ornamental building material on an order contract basis. (author)

  4. Gamma-ray emission from 80-86As isotopes

    International Nuclear Information System (INIS)

    Kratz, J.V.; Franz, H.; Kaffrell, N.; Hermann, G.

    1975-01-01

    Activities of 80-86 As were produced in (n,p) reactions on stable selenium nuclei as fission products, and via β - decay from their precursors. To separate arsenic and germanium from fission product mixtures, rapid chemical separations were applied. Gamma-ray emission from arsenic isotopes was studied in γ-singles and γγ coincidence experiments. Partial decay schemes are proposed for 34sec 81 As, 14.0sec and 19.1sec 82 As, 13.3sec 83 As and 5.3sec 84 As. The delayed-neutron branch in the decay of 2.05sec 85 As was shown to preferentially populate several excited levels in 84 Se while the ground state of 84 Se is fed to 29% only. The systematics of low-lying levels in doubly even selenium isotopes is extended up to mass number 86. Discontinuities in the systematics at N=48 are interpreted as an indication of a soft character of the nucleus 82 Se. (Auth.)

  5. Commercial gamma-ray irradiation plant in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Tomita, K; Sugimoto, S [Radia Industry Co. Ltd., Gunma (Japan)

    1977-01-01

    In 1973, a commercial gamma-ray irradiation plant was constructed in Takasaki, about 100 km north of Tokyo. The plant has been used for both production of irradiated commercial products and irradiation services. The irradiation services are being made available for sterilization of both medical appliances such as disposable medical syringes, catheters, surgical sutures, and sterilization of feed stuffs for animals. Treatment of plastic materials and colouring of both crystals and glass wares are also undertaken. This facility can accommodate 600 kCi of /sup 60/Co and has a monthly treating capacity of 12,000 packages ( a standard carton of 340 mm x 400 mm x 500 mm) at an irradiation dose of 1 Mrad/hr. A receiving port for packages is on the second floor and the outlet of the irradiated packages on the first floor, with three lines of connecting loop conveyors between them, and the irradiation compartment in the center section. The space arrangement of the facility is well designed and gravity can be utilized for the transportation of the packages. Polymer impregnated coral is put on the market for ornamental building material on an order contract basis.

  6. Developments in gamma-ray spectrometry: systems, software, and methods-II. 3. Low-Energy Gamma-Ray Spectrometry Using a Compton-Suppressed Telescope Detector

    International Nuclear Information System (INIS)

    Sigg, R.A.; DiPrete, D.P.

    2001-01-01

    The Savannah River Technology Center (SRTC) utilizes gamma-ray spectrometry in studying numerous areas of applied interest to the Savannah River Site (SRS). For example, analyses of long-lived gamma-ray-emitting fission products and actinides are required to meet waste characterization, process holdup, environmental restoration, and decontamination and decommissioning efforts. A significant portion of the overall effort centers on measurements of gamma rays having energies below several hundred kilo-electron-volts. To assist these efforts, the SRTC recently acquired a spectrometer system that provides lower natural and Compton scattered background levels while achieving relatively high counting efficiencies for low-energy gamma rays. The combination of high efficiency and low background provides factor-of- 2-to-4 improvements in minimum detectable activities and allows meeting programmatic objectives with shorter measurement times. Numerous Compton-suppression spectrometers have been reported since the concept was first advanced. The spectrometer consists of two high-purity germanium detectors in a telescope configuration surrounded by a background /Compton-suppression sodium iodide detector. The front germanium detector is a 20-mm-thick x 60-mm-diam broad energy spectrometer, and the rear detector is a 40% efficient 61- mm-diam x 60-cm-thick closed-end coaxial spectrometer. The cryostat housing the germanium detectors (a) includes a carbon composite window for transmitting low-energy gamma rays, (b) is in a J-type configuration to mask the germanium detectors from natural activities in the cryo-pumping media, and (c) is fabricated from materials selected for low background. The telescope detector is in the 8.6-cm-inside-diameter annulus of a 22.9- x 22.9-cm sodium iodide detector encased in a 10-cm-thick lead shield. The counting system is located in a basement counting room having ∼60-cm-thick concrete walls. Initial tests show that the low-energy segment of

  7. LFlGRB: Luminosity function of long gamma-ray bursts

    Science.gov (United States)

    Paul, Debdutta

    2018-04-01

    LFlGRB models the luminosity function (LF) of long Gamma Ray Bursts (lGRBs) by using a sample of Swift and Fermi lGRBs to re-derive the parameters of the Yonetoku correlation and self-consistently estimate pseudo-redshifts of all the bursts with unknown redshifts. The GRB formation rate is modeled as the product of the cosmic star formation rate and a GRB formation efficiency for a given stellar mass.

  8. Deficiency of gamma-ray excision repair in skin fibroblasts from patients with Fanconi's anemia

    International Nuclear Information System (INIS)

    Remsen, J.F.; Cerutti, P.A.

    1976-01-01

    The capacity of preparations of skin fibroblasts from normal individuals and patients with Fanconi's anemia to excise gamma-ray products of the 5,6-dihydroxydihydrothymine type from exogenous DNA was investigated. The excision capacity of whole-cell homogenates of fibroblasts from two of four patients with Fanconi's anemia was substantially below normal. This repair deficiency was further pronounced in nuclear preparations from cells of the same two patients

  9. Radiosensitivity of California Wonder pepper variety to Co-60 gamma rays

    International Nuclear Information System (INIS)

    Puertas Arias, Ana Leonor; Gonzalez Nunez, Luis Manuel; Ramirez Fernandez, Ramiro

    1998-01-01

    Seeds of California wonder pepper variety were irradiated with dosages among 100-800 Gy, to intervals of 100 Gy, in a source of Co 60 gamma rays, with the objective of determining its radiosensitivity and to establish the adequate interval of dosage for the mutation breeding. A decrease of the growing indicators, productivity and plant fertility was observed with the increasing of irradiation dosages and the interval among 130-460 Gy was established as the most adequate

  10. Effects of gamma-ray irradiation on cellulase secretion of Trichoderma reesei

    International Nuclear Information System (INIS)

    Tamada, M.; Kasai, N.; Kaetsu, I.

    1987-01-01

    Trichoderma reesei was irradiated with gamma rays to investigate the effects of different dosages on cellulase production. Doses above 0.7 kGy induced cell lysis. Cell growth began to be obstructed at 2.0 kGy. As a result, the cells irradiated at 2.0 kGy secreted 1.8 times as much cellulase as the untreated cells

  11. Gamma-rays and the case for baryon symmetric big-bang cosmology

    Science.gov (United States)

    Stecker, F. W.

    1977-01-01

    The baryon symmetric big-bang cosmologies offer an explanation of the present photon-baryon ratio in the universe, the best present explanation of the diffuse gamma-ray background spectrum in the 1-200 MeV range, and a mechanism for galaxy formation. In regard to He production, evidence is discussed that nucleosynthesis of He may have taken place after the galaxies were formed.

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

    OpenAIRE

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

    2017-01-01

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

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

    International Nuclear Information System (INIS)

    Chiu, H.K.

    1991-10-01

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

  14. Protective Role of Emodin in Reducing The Gamma Rays Induced Hazardous Effects On The Tongue of Diabetic or Normoglycaemic Mice

    International Nuclear Information System (INIS)

    Haggag, M.G.; Kazem, H.H.

    2013-01-01

    Ionizing radiation leads to damage at various cellular and sub-cellular levels and can be prevented by radio protectors. There is a need for natural prospective radio protectors that protect normal tissues from ionizing radiation in patients receiving high doses of radiation for treating malignant neoplasms. The study aimed to evaluate the potential protective role of emodin in reducing the severity of gamma rays-induced hazardous damage in the tongue of normoglycaemic and diabetic mice. Sixty-four male mice were randomly divided into 8 experimental groups: control group received vehicle, emodin group received daily emodin dose of 4g/kg orally for a week, diabetes mellitus (DM) group in which DM was induced by streptozotocin (STZ) treatment, emodin + DM received emodin for a week + STZ treatment, irradiated group submitted to 4 Gy of gamma rays and received vehicle for a week, gamma rays + DM group received gamma rays + STZ treatment, gamma rays + emodin group received gamma rays + emodin for a week, and gamma rays + DM + emodin group received gamma rays + STZ treatment + emodin for a week. Tongue and serum of mice were biochemically examined for screening gamma radiation and diabetic damages and the efficacy of emodin in ameliorating these damaging effects. The levels of cellular thiols such as reduced glutathione (GSH), oxidized glutathione (GSSG), total thiols (TT) and lipid peroxidation products; malondialdehyde (MDA) and conjugated dienes (CD), were assessed in tongue tissues. Tongue antioxidant enzymes; gamma glutamyl transferase (GGT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glucose-6-phosphatase (G-6-P), were measured and serum glucose level was estimated. The results revealed alterations of the levels of cellular thiols and antioxidant enzymes in tongue and the level of glucose in serum of gamma irradiated diabetic mice were ameliorated in mice groups received emodin treatment. The results suggest that emodin treatment (4 g

  15. THE ORIGIN OF GAMMA RAYS FROM GLOBULAR CLUSTERS

    International Nuclear Information System (INIS)

    Cheng, K. S.; Chernyshov, D. O.; Dogiel, V. A.; Hui, C. Y.; Kong, A. K. H.

    2010-01-01

    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

  16. Continued Development of a Soft Gamma-Ray Concentrator

    Science.gov (United States)

    Bloser, Peter

    We propose to continue our development of a concept for a soft gamma-ray (E > 100 keV) concentrator using thin-film multilayer structures. Alternating layers of low- and high-density materials will channel soft gamma-ray photons via total external reflection. A suitable arrangement of bent structures will then concentrate the incident radiation to a point. Gamma-ray optics made in this way offer the potential for soft gamma-ray telescopes with focal lengths of less than 10 m, removing the need for formation flying spacecraft and opening the field up to balloon-borne instruments. Under previous APRA funding we have been investigating methods for efficiently producing such multilayer structures and modeling their performance. We now propose to pursue magnetron sputtering (MS) techniques to quickly produce structures with the required smoothness and thickness, to measure their channeling efficiency and compare with calculations, and to design a "lens" with optimized bandpass and throughput and predict its scientific performance. If successful, this work will confirm that this innovative optics concept is suitable for a balloon-born soft gamma-ray telescope with unprecedented sensitivity.

  17. TL detectors for gamma ray dose measurements in criticality accidents

    International Nuclear Information System (INIS)

    Miljanic, S.; Zorko, B.; Gregori, B.; Knezevic, Z.

    2007-01-01

    Determination of gamma ray dose in mixed neutron + gamma ray fields is still a demanding task. Dosemeters used for gamma ray dosimetry are usually in some extent sensitive to neutrons and their response variations depend on neutron energy i.e., on neutron spectra. Besides, it is necessary to take into account the energy dependence of dosemeter responses to gamma rays. In this work, several types of thermoluminescent detectors (TLD) placed in different holders used for gamma ray dose determination in the mixed fields were examined. Dosemeters were from three different institutions: Ruder Boskovic Inst. (RBI), Croatia, Jozef Stefan Inst. (JSI), Slovenia and Autoridad Regulatoria Nuclear (ARN), Argentina. All dosemeters were irradiated during the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002. Three accidental scenarios were reproduced and in each irradiation the dosemeters were exposed placed on the front of phantom and 'free in air'. Following types of TLDs were used: 7 LiF (TLD-700), CaF 2 :Mn and Al2 O3 :Mg,Y - all from RBI; CaF 2 :Mn from JSI and 7 LiF (TLD-700) from ARN. Reported doses were compared with the reference values as well as with the values obtained from the results of all participants. The results show satisfactory agreement with other dosimetry systems used in the Intercomparison. The influence of different types of holders and applied corrections of dosemeters' readings are discussed. (authors)

  18. TL detectors for gamma ray dose measurements in criticality accidents.

    Science.gov (United States)

    Miljanić, Saveta; Zorko, Benjamin; Gregori, Beatriz; Knezević, Zeljka

    2007-01-01

    Determination of gamma ray dose in mixed neutron+gamma ray fields is still a demanding task. Dosemeters used for gamma ray dosimetry are usually in some extent sensitive to neutrons and their response variations depend on neutron energy i.e., on neutron spectra. Besides, it is necessary to take into account the energy dependence of dosemeter responses to gamma rays. In this work, several types of thermoluminescent detectors (TLD) placed in different holders used for gamma ray dose determination in the mixed fields were examined. Dosemeters were from three different institutions: Ruder Bosković Institute (RBI), Croatia, JoZef Stefan Institute (JSI), Slovenia and Autoridad Regulatoria Nuclear (ARN), Argentina. All dosemeters were irradiated during the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002. Three accidental scenarios were reproduced and in each irradiation the dosemeters were exposed placed on the front of phantom and 'free in air'. Following types of TLDs were used: 7LiF (TLD-700), CaF2:Mn and Al2O3:Mg,Y-all from RBI; CaF2:Mn from JSI and 7LiF (TLD-700) from ARN. Reported doses were compared with the reference values as well as with the values obtained from the results of all participants. The results show satisfactory agreement with other dosimetry systems used in the Intercomparison. The influence of different types of holders and applied corrections of dosemeters' readings are discussed.

  19. Bacteriostatic activity of various antibiotics after gamma-ray irradiation

    International Nuclear Information System (INIS)

    Fleurette, J.; Madier, S.; Transy, M.J.

    1975-01-01

    The purpose of the work described was to discover whether the antibiotics used in medicine can be sterilized by gamma rays; in this preliminary study, only the antimicrobic activity - the principal criterion for this type of medicament - was evaluated. Thirty-three products belonging to the various families of antibacterial and antifungic antibiotics were studied. The substances were irradiated in the dry state and in an aqueous solution, using a caesium-137 irradiator. The antibacterial and antifungic activity before and after irradiation was investigated by the method of diffusion in gelose. When irradiated in the dry state, 14 antibiotics preserve normal activity up to a dose of 10 Mrad; at doses between 5 and 10 Mrad, 15 other antibiotics are subject to a variable, but moderate, loss activity; and four register a slight loss of activity at a dose of 2.5 Mrad. In an aqueous solution all but two of the antibiotics suffer total loss of activity at a dose of 2.5 Mrad. As most commercial antibiotics are supplied in the dry state, gamma irradiation may be a useful sterilization process. However, preparations such as eye lotions, suspensions, ointments, etc. should be excepted

  20. Proton current measurements using the prompt gamma ray diagnostic technique

    International Nuclear Information System (INIS)

    Leeper, R.J.; Burns, E.J.T.; Johnson, D.J.; McMurtry, W.M.

    1981-01-01

    Prompt gamma ray signals from the nuclear reaction 7 Li(p,γ) 8 Be have been used to make time resolved proton current measurements. In these measurements, the proton beam was allowed to strike cylindrical thick lithium metal targets. The time integrated proton current was measured using gamma activation of copper via the reaction 63 Cu(γ,n) 62 Cu(β+). The positron activity of the copper sample was easily measured using coincidence counting techniques. The number of 62 Cu atoms produced per proton incident on a thick Li metal target was determined with separate calibration runs performed on the Sandia 2.5 MeV Van de Graaff accelerator. The time history of the prompt gamma production was measured using six EGG NPM-54 scintillator photomultiplier combinations shielded by 96.5 cm of concrete and 5.1 cm of Pb. The use of six scintillator photomultiplier combinations was necessary to increase the statistical precision of the data. The normalization of the prompt gamma time history data with the total time integrated proton-current measurement yielded the absolute time resolved proton current on target. Data from runs performed on the Sandia Proto I accelerator will be presented