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Sample records for gamma-ray induced mutation

  1. Did gamma ray burst induce Cambrian explosion?

    NASA Astrophysics Data System (ADS)

    Chen, Pisin; Ruffini, R.

    2015-06-01

    One longstanding mystery in bio-evolution since Darwin's time is the origin of the Cambrian explosion that happened around 540 million years ago (Mya), where an extremely rapid increase of species occurred. Here we suggest that a nearby GRB event 500 parsecs away, which should occur about once per 5 Gy, might have triggered the Cambrian explosion. Due to a relatively lower cross section and the conservation of photon number in Compton scattering, a substantial fraction of the GRB photons can reach the sea level and would induce DNA mutations in organisms protected by a shallow layer of water or soil, thus expediting the bio-diversification. This possibility of inducing genetic mutations is unique among all candidate sources for major incidents in the history of bio-evolution. A possible evidence would be the anomalous abundance of certain nuclear isotopes with long half-lives transmuted by the GRB photons in geological records from the Cambrian period. Our notion also imposes constraints on the evolution of exoplanet organisms and the migration of panspermia.

  2. Induced Background in the Mars Observer Gamma-Ray Spectrometer

    NASA Technical Reports Server (NTRS)

    Boynton, William V.; Evans, Larry G.; Starr, Richard; Bruekner, Johnnes; Bailey, S. H.; Trombka, Jacob I.

    1997-01-01

    Gamma-Ray Spectrometers in space must necessarily work in an environment of a background of lines due to natural and cosmic-ray induced radioactivity and lines due to prompt emission following nuclear reactions caused by primary and secondary cosmic rays. The Gamma-Ray Spectrometer (GRS) on the Mar Observer mission has provided important data allowing one to estimate for future missions the extent of the background due to cosmic rays. These data will help in the design of instruments and in calculation of realistic background intensities that may effect the sensitivity of determining the intensity of lines of interest.

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

    NASA Astrophysics Data System (ADS)

    Chiu, H. K.

    1991-10-01

    The problem of measuring the gamma heating in a mixed DT neutron and gamma ray environment was explored. A new detector technique was developed to make this measurement. Gamma heating measurements were made in a low-Z assembly irradiated with 14-Mev neutrons and (n, n(prime)) gammas produced by a Texas Nuclear Model 9400 neutron generator. Heating measurements were made in the mid-line of the lattice using a proportional counter operating in the Continuously-varied Bias-voltage Acquisition mode. The neutron-induced signal was separated from the gamma-induced signal by exploiting the signal rise-time differences inherent to radiations of different linear energy transfer coefficient, which are observable in a proportional counter. The operating limits of this measurement technique were explored by varying the counter position in the low-Z lattice, hence changing the irradiation spectrum observed. The experiment was modelled numerically to help interpret the measured results. The transport of neutrons and gamma rays in the assembly was modelled using the one-dimensional radiation transport code ANISN/PC. The cross-section set used for these calculations was derived from the ENDF/B-V library using the code MC(exp 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.

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

    SciTech Connect

    Chiu, H.K.

    1991-10-01

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

  5. Identification of Selected Gamma-Ray Induced Deficiencies in Zebrafish Using Multiplex Polymerase Chain Reaction

    PubMed Central

    Fritz, A.; Rozowski, M.; Walker, C.; Westerfield, M.

    1996-01-01

    The ease with which mutations can be generated in zebrafish makes this vertebrate an important resource for developmental genetics and genome studies. We have developed a PCR-based screening method that allows the efficient identification of gamma-ray induced deficiencies targeted to selected sequences. We describe three mutants characteristic of our findings and show that these mutations include deletions and translocations that can affect as much as 1% of the genome. These deficiencies provide a basis for analyzing the functions of cloned zebrafish genes using noncomplementation screens for point mutations induced by high-efficiency chemical mutagenesis. PMID:8978059

  6. Explosive Material Identification via Neutron-Induced Gamma Rays

    NASA Astrophysics Data System (ADS)

    Freiberg, David; Litz, Marc

    2014-09-01

    With the increase in the usage of improvised explosive devices, both vehicle-borne and buried, it has become increasingly important to quickly identify potentially explosive materials before they can be detonated. In a field test performed in January of 2014, 14 MeV neutrons generated in a deuterium-tritium reaction induced gamma emissions in explosive material targets. The resulting gamma rays were counted in LaBr3 detectors in both a time-binned associated particle imaging (API) mode and a repetitively pulsed mode. The details of the resulting data sets were analyzed, and gamma lines for carbon, oxygen, and nitrogen were identified in the spectra produced by both modes. Post-test noise reduction techniques included empty hole background subtraction, Compton background subtraction, peak area integration, and time-of-flight gating. The induced C, O, and N gamma line intensities and ratios were compared to the elemental weight ratios expected for each type of material. The composition results are indicative of the known elemental weights in the target materials. The statistics are limited because of the short, 20 second data collection periods, and would improve greatly with longer exposure times in the future.

  7. Lymphocytes from wasted mice express enhanced spontaneous and {gamma}-ray-induced apoptosis

    SciTech Connect

    Woloschak, G.E. |; Chang-Liu, Chin-Mei; Chung, Jen; Libertin, C.R.

    1993-09-01

    Mice bearing the autosomal recessive mutation wasted (wst/wst) display a disease pattern including faulty repair of DNA damage in lymphocytes after radiation exposure, neurologic abnormalities, and immunodeficiency. Many of the features of this mouse model have suggested a premature or increased spontaneous frequency of apoptosis in thymocytes; past work has shown an inability to establish cultured T cell lines, an abnormally high death rate of stimulated T cells in culture, and an increased sensitivity of T cells to the killing effects of ionizing radiations in wst/wst mice relative to controls. The experiments reported here were designed to examine splenic and thymic lymphocytes from wasted and control mice for signs of early apoptosis. Our results revealed enhanced expression of Rp-8 mRNA (associated with apoptosis) in thymic lymphocytes and reduced expression in splenic lymphocytes of wst/wst mice relative to controls; expression of Rp-2 and Td-30 mRNA (induced during apoptosis) were not detectable in spleen or thymus. Higher spontaneous DNA fragmentation was observed in wasted mice than in controls; however, {gamma}-ray-induced DNA fragmentation peaked at a lower dose and occurred to a greater extent in wasted mice relative to controls. These results provide evidence for high spontaneous and {gamma}-ray-induced apoptosis in T cells of wasted mice as a mechanism underlying the observed lymphocyte and DNA repair abnormalities.

  8. Changes in DNA base sequence induced by gamma-ray mutagenesis of lambda phage and prophage

    SciTech Connect

    Tindall, K.R.; Stein, J.; Hutchinson, F.

    1988-04-01

    Mutations in the cI (repressor) gene were induced by gamma-ray irradiation of lambda phage and of prophage, and 121 mutations were sequenced. Two-thirds of the mutations in irradiated phage assayed in recA host cells (no induction of the SOS response) were G:C to A:T transitions; it is hypothesized that these may arise during DNA replication from adenine mispairing with a cytosine product deaminated by irradiation. For irradiated phage assayed in host cells in which the SOS response had been induced, 85% of the mutations were base substitutions, and in 40 of the 41 base changes, a preexisting base pair had been replaced by an A:T pair; these might come from damaged bases acting as AP (apurinic or apyrimidinic) sites. The remaining mutations were 1 and 2 base deletions. In irradiated prophage, base change mutations involved the substitution of both A:T and of G:C pairs for the preexisting pairs; the substitution of G:C pairs shows that some base substitution mechanism acts on the cell genome but not on the phage. In the irradiated prophage, frameshifts and a significant number of gross rearrangements were also found.

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

    SciTech Connect

    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.

  10. Method and System for Gamma-Ray Localization Induced Spacecraft Navigation Using Celestial Gamma-Ray Sources

    NASA Technical Reports Server (NTRS)

    Sheikh, Suneel I. (Inventor); Hisamoto, Chuck (Inventor); Arzoumanian, Zaven (Inventor)

    2015-01-01

    A method and system for spacecraft navigation using distant celestial gamma-ray bursts which offer detectable, bright, high-energy events that provide well-defined characteristics conducive to accurate time-alignment among spatially separated spacecraft. Utilizing assemblages of photons from distant gamma-ray bursts, relative range between two spacecraft can be accurately computed along the direction to each burst's source based upon the difference in arrival time of the burst emission at each spacecraft's location. Correlation methods used to time-align the high-energy burst profiles are provided. The spacecraft navigation may be carried out autonomously or in a central control mode of operation.

  11. Change in Ion Beam Induced Current from Si Metal-Oxide-Semiconductor Capacitors after Gamma-Ray Irradiation

    SciTech Connect

    Ohshima, T.; Onoda, S.; Hirao, T.; Takahashi, Y.; Vizkelethy, G.; Doyle, B. L.

    2009-03-10

    To investigate the effects of gamma-ray irradiation on transient current induced in MOS capacitors by heavy ion incidence, Si MOS capacitors were irradiated with gamma-rays up to 60.9 kGy(SiO2). The change in Transient Ion Beam Induced Current (TIBIC) signals due to gamma-ray irradiation was investigated using 15 MeV-oxygen ion microbeams. After gamma-ray irradiation, the peak current of the TIBIC signal vs. bias voltage curve shifted toward negative voltages. This shift can be interpreted in terms of the charge trapped in the oxide. In this dose range, no significant effects of the interface traps induced by gamma-ray irradiation on the TIBIC signals were observed.

  12. Hepatocyte growth factor protects endothelial cells against gamma ray irradiation-induced damage

    PubMed Central

    Hu, Shun-ying; Duan, Hai-feng; Li, Qing-fang; Yang, Yue-feng; Chen, Jin-long; Wang, Li-sheng; Wang, Hua

    2009-01-01

    Aim: To investigate the effect of HGF on proliferation, apoptosis and migratory ability of human vascular endothelial cells against gamma ray irradiation. Methods: ECV304 cells derived from adult human umbilical vein endothelial cells (HUVEC) were irradiated with a single gamma ray dose of 20 Gy. Immunocytochemistry and Western blot analysis were used to detect c-Met protein expression and HGF/c-Met signal pathway. In the HGF-treated groups, ECV304 cells were incubated with HGF (20 or 40 ng/mL) 3 h prior to irradiation. At 48 h post-irradiation, the proliferation of ECV304 cells was measured by MTT assay, the apoptosis was assessed by flow cytometry, and the migratory ability of ECV304 cells was measured by transwell chamber assay. Results: c-Met protein is expressed in ECV304 cells and can be activated by HGF. Gamma ray irradiation inhibits proliferation and migration of ECV304 cells in a dose-dependent manner. HGF significantly promoted the proliferation of ECV304 cells, and flow cytometry revealed that HGF can inhibit apoptosis of ECV304 cells. Transwell chamber assay also showed that HGF increases migration activity of endothelial cells. Conclusion: HGF may afford protection to vascular endothelial cells against gamma ray irradiation-induced damage. PMID:19749787

  13. Detection of pulsed bremsstrahlung-induced prompt neutron capture gamma rays with a HPGe detector

    NASA Astrophysics Data System (ADS)

    Jones, James L.

    1997-02-01

    The Idaho National Engineering Laboratory (INEL) is developing a novel photoneutron-based nondestructive evaluation technique which uses a pulsed, high-energy electron accelerator and gamma-ray spectrometry. Highly penetrating pulses of bremsstrahlung photons are produced by each pulse of electrons. Interrogating neutrons are generated by the bremsstrahlung photons interacting within a photoneutron source material. The interactions of the neutrons within a target result in the emission of elemental characteristic gamma-rays. Spectrometry is performed by analyzing the photoneutron-induced, prompt gama-rays acquired between accelerator pulses with a unique, high- purity germanium gamma-ray detection system using a modified transistor reset preamplifier. The detection system, the experimental configuration, and the accelerator operation used to characterize the detection systems performance are described. Using a 6.5-MeV electron accelerator and a beryllium metal photoneutron source, gamma-ray spectra were successfully acquired for Al, Cu, polyethylene, NaCl, and depleted uranium targets as soon as 30 microsecond(s) after each bremsstrahlung flash.

  14. Analysis of spontaneous, gamma ray- and ethylnitrosourea-induced hprt mutants in HL-60 cells with multiplex PCR

    PubMed Central

    Liu, Sheng-Xue; Cao, Jia; An, Hui; Shun, Hua-Min; Yang, Lu-Jun; Liu, Yong

    2003-01-01

    AIM: To explore the molecular spectra and mechanism of human hypoxanthine guanine phosphoribosyl transferase (hprt) gene mutation induced by ethyluitrosourea (ENU) and 60Co γ-rays. METHODS: Independent human promyelocytic leukemia cells (HL-60) mutants at the hprt locus were isolated from untreated, ethyluitrosourea (ENU) and 60Co γ-ray-exposed cells, respectively, and verified by two-way screening. The genetic changes underlying the mutation were determined by multiplex polymerase chain reaction (PCR) amplification and electrophoresis technique. RESULTS: With dosage increased, survival rate of plated cell reduced (in the group with dosage of ENU with 100-200 μg/mL, P < 0.01; in the group with dosage of 60Co γ-ray with 2-4 Gy, P < 0.05) and mutational frequency increased (in the group of ENU 12.5-200.0 μg/mL, P < 0.05; in the group of 60Co γ-ray with 1-4 Gy, P < 0.05) significantly. In the 13 spontaneous mutants analyzed, 92.3% of mutant clones did not show any change in number or size of exon, a single exon was lost in 7.7%, and no evidence indicated total gene deletion occurred in nine hprt exons. However, deletions were found in 79.7% of ENU-induced mutations (62.5%-89.4%, P < 0.01) and in 61.7% of gamma-ray-induced mutations (28.6%-76.5%, P < 0.01). There were deletion mutations in all 9 exons of hprt gene and the most of induced mutations were chain deletion with multiplex exons (97.9% in gamma-ray-induced mutants, 88.1% in ENU-induced mutants). CONCLUSION: The spectra of spontaneous mutations differs completely from that induced by EUN or 60Co γ-ray. Although both ENU and γ-ray can cause destruction of genetic structure, mechanism of mutagenesis between them may be different. PMID:12632522

  15. Lignocellulolytic mutants of Pleurotus ostreatus induced by gamma-ray radiation and their genetic similarities

    NASA Astrophysics Data System (ADS)

    Lee, Y.-K.; Chang, H.-H.; Kim, J.-S.; Kim, J. K.; Lee, K.-S.

    2000-02-01

    To induce the lignocellulolytic mutants of Pleurotus ostreatus, the mycelia were irradiated by gamma-ray radiation to doses of 1-2 kGy. Five strains were isolated by the criteria of clamp connection, fruiting body formation, growth rate and activities of extracellular enzymes. All isolated strains were able to form the fruiting bodies and grew similarly to the control. The extracellular enzymes activities in liquid media of isolated strains were up to 10 times higher than the control. Genetic similarities of the isolated strains ranged from 64.4% to 93.3% of the control. From these results, it seems that the genetic diversity of P. ostreatus could be changed and useful strains be induced by gamma-ray radiation to recycle or reuse biowastes.

  16. Monte Carlo simulation of induced radioactive background in gamma-ray detector materials

    SciTech Connect

    Truscott, P.R.; Evans, H.E.; Dyer, C.S.; Cosby, M.; Knight, P.R.; Moss, C.E.

    1998-06-01

    Induced activation in detector materials constitutes a major source of background for space-borne {gamma}-ray instruments. Future detector systems will utilize a variety of background reduction techniques and novel detector materials to maximize signal-to-noise and resolution of the measurements taken, and assessment of the merits of different designs will require detailed attention to a wide range of physical processes. The Integrated Radiation Transport Suite (IRTS) has been applied to simulate the effects of spacecraft shielding against Van Allen and galactic cosmic-ray protons, the production of secondary hadrons, and induced radioactivity in and the response of {gamma}-ray detector materials. This paper discusses the physics requirements for these simulations, and the degree of success of the models through comparisons with experimental data obtained from Space Shuttle flights and proton-beam irradiation of detector materials.

  17. Induced Radioactivity in Recovered Skylab Materials. [gamma ray spectra

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.; Meegan, C. A.

    1980-01-01

    Four radioactive isotopes found in aluminum and stainless steel samples from Skylab debris were recovered in Australia. The low-level activity was induced by high-energy protons and neutrons in the space environment. Measurements of the specific activities are given.

  18. Gamma-ray irradiation induced bulk photochromism in WO3-P2O5 glass

    NASA Astrophysics Data System (ADS)

    Shen, Wei; Baccaro, Stefania; Cemmi, Alessia; Xu, Xiaoqing; Chen, Guorong

    2015-11-01

    In the present work, photochromism of WO3-P2O5 glass under gamma-ray irradiation was reported. As-prepared glass samples with different WO3 content are all optically transparent in the visible wavelength range thanks to the addition of a small amount of oxidizing couple Sb2O3-NaNO3. The photochromic properties are identified by transmission spectra of the glasses before and after irradiation. The results show that the irradiation induced darkening results from the reduction of W6+ to W5+ or W4+. The existence of WO6 clusters in glasses of high WO3 content is proved by XPS, which is the main reason for the obvious photochromic effects. The WO3-P2O5 glass is a promising candidate in gamma-ray sensitive detector.

  19. The {alpha}-induced thick-target {gamma}-ray yield from light elements

    SciTech Connect

    Heaton, R.K. |

    1994-10-01

    The {alpha}-induced thick-target {gamma}-ray yield from light elements has been measured in the energy range 5.6 MeV {le} E{sub {alpha}} {le} 10 MeV. The {gamma}-ray yield for > 2.1 MeV from thick targets of beryllium, boron nitride, sodium fluoride, magnesium, aluminum and silicon were measured using the {alpha}-particle beam from the Lawrence Berkeley Laboratories 88 in. cyclotron. The elemental yields from this experiment were used to construct the {alpha}-induced direct production {gamma}-ray spectrum from materials in the SNO detector, a large volume ultra-low background neutrino detector located in the Creighton mine near Sudbury, Canada. This background source was an order of magnitude lower than predicted by previous calculations. These measurements are in good agreement with theoretical calculations of this spectrum based on a statistical nuclear model of the reaction, with the gross high energy spectrum structure being reproduced to within a factor of two. Detailed comparison of experimental and theoretical excitation population distribution of several residual nuclei indicate the same level of agreement within experimental uncertainties.

  20. Photon-induced positron annihilation lifetime spectroscopy using ultrashort laser-Compton-scattered gamma-ray pulses

    SciTech Connect

    Taira, Y.; Toyokawa, H.; Kuroda, R.; Yamamoto, N.; Adachi, M.; Tanaka, S.; Katoh, M.

    2013-05-15

    High-energy ultrashort gamma-ray pulses can be generated via laser Compton scattering with 90 Degree-Sign collisions at the UVSOR-II electron storage ring. As an applied study of ultrashort gamma-ray pulses, a new photon-induced positron annihilation lifetime spectroscopy approach has been developed. Ultrashort gamma-ray pulses with a maximum energy of 6.6 MeV and pulse width of 2.2 ps created positrons throughout bulk lead via pair production. Annihilation gamma rays were detected by a BaF{sub 2} scintillator mounted on a photomultiplier tube. A positron lifetime spectrum was obtained by measuring the time difference between the RF frequency of the electron storage ring and the detection time of the annihilation gamma rays. We calculated the response of the BaF{sub 2} scintillator and the time jitter caused by the variation in the total path length of the ultrashort gamma-ray pulses, annihilation gamma rays, and scintillation light using a Monte Carlo simulation code. The positron lifetime for bulk lead was successfully measured.

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

    SciTech Connect

    Masarik, J.; Reedy, R.C.

    1994-07-01

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

  2. Chromosomal mutations and chromosome loss measured in a new human-hamster hybrid cell line, ALC: studies with colcemid, ultraviolet irradiation, and 137Cs gamma-rays

    NASA Technical Reports Server (NTRS)

    Kraemer, S. M.; Waldren, C. A.; Chatterjee, A. (Principal Investigator)

    1997-01-01

    Small mutations, megabase deletions, and aneuploidy are involved in carcinogenesis and genetic defects, so it is important to be able to quantify these mutations and understand mechanisms of their creation. We have previously quantified a spectrum of mutations, including megabase deletions, in human chromosome 11, the sole human chromosome in a hamster-human hybrid cell line AL. S1- mutants have lost expression of a human cell surface antigen, S1, which is encoded by the M1C1 gene at 11p13 so that mutants can be detected via a complement-mediated cytotoxicity assay in which S1+ cells are killed and S1- cells survive. But loss of genes located on the tip of the short arm of 11 (11p15.5) is lethal to the AL hybrid, so that mutants that have lost the entire chromosome 11 die and escape detection. To circumvent this, we fused AL with Chinese hamster ovary (CHO) cells to produce a new hybrid, ALC, in which the requirement for maintaining 11p15.5 is relieved, allowing us to detect mutations events involving loss of 11p15.5. We evaluated the usefulness of this hybrid by conducting mutagenesis studies with colcemid, 137Cs gamma-radiation and UV 254 nm light. Colcemid induced 1000 more S1- mutants per unit dose in ALC than in AL; the increase for UV 254 nm light was only two-fold; and the increase for 137Cs gamma-rays was 12-fold. The increase in S1- mutant fraction in ALC cells treated with colcemid and 137Cs gamma-rays were largely due to chromosome loss and 11p deletions often containing a breakpoint within the centromeric region.

  3. Gamma-rays induction of mutation in conchocelis of Porphyra yezoensis

    NASA Astrophysics Data System (ADS)

    Wang, Su-Juan; Zheng, Yuan-Zhu; Ma, Ling-Bo; Xu, Pu; Zhu, Jian-Yi

    2000-03-01

    Free-living conchocelis of Porphyra yezoensis Ueda (Bangiales, Rhodophyta) were treated with60Co-γ rays of different doses (ranging from 100 Gy to 1000 Gy) to induce mutation. Most of the conchocelis maintained the capability of penetrating into shells, growing and forming colonies in shells, but their vitality was seriously impaired by the irradiation of γ-rays. A few conchocelis pigments were mutagenized directly into different color pigment mutants whose progeny-conchospores and foliose thalli had the same colors. However, some irradiated conchocelis did not show the change in color at the conchocelis stage. The pigment mutation could be observed only after the conchospores of these conchocelis had germinated into young foliose thalli. Irradiation of low dose (100 Gy) promoted the growth of thallus and many with altered morphology were observed. Conchospores of the irradiated conchocelis attached to the culture nets were cultured in the sea, and growth of these progenies was observed and measured.

  4. Gamma-ray bursts and cosmic rays from accretion-induced collapse

    NASA Technical Reports Server (NTRS)

    Dar, Arnon; Kozlovsky, Ben Z.; Nussinov, Shmuel; Ramaty, Reuven

    1992-01-01

    It is shown that the birth of naked or nearly naked neutron stars in accretion-induced collapse or in the bare collapse of white dwarfs can produce cosmological gamma-ray bursts and can provide the required injection rate of cosmic rays into the interstellar space. It is estimated that most of the e(+)e(-) pairs annihilate in flight on a short time scale in the vicinity of the neutron star. It is shown that the gamma-ray bursts, the 0.511 MeV Galactic annihilation radiation, and the cosmic rays exclude the possibility that the large uncertainties in the Galactic pulsar birthrate and the Galactic SN II explosion rate would allow a significant contribution to the pulsar birthrate from naked or nearly naked neutron star formation. The upper bound on the Galactic birthrate of naked or nearly naked neutron stars of less than 1 in 1000 yr makes it very unlikely that a neutrino burst unaccompanied by optical emission from the birth of a naked or nearly naked neutron star will be detected in the near future by underground neutrino telescopes.

  5. Radiation-induced degradation of cyclohexanebutyric acid in aqueous solutions by gamma ray irradiation

    NASA Astrophysics Data System (ADS)

    Jia, Wenbao; He, Yanquan; Ling, Yongsheng; Hei, Daqian; Shan, Qing; Zhang, Yan; Li, Jiatong

    2015-04-01

    The radiation-induced degradation of cyclohexanebutyric acid under gamma ray irradiation was investigated. Degradation experiments were performed with 100 mL sealed Pyrex glass vessels loaded with 80 mL of cyclohexanebutyric acid solutions at various initial concentrations of 10, 20, and 40 mg L-1. The absorbed doses were controlled at 0, 0.65, 1.95, 3.25, 6.5, 9.75, and 13 kGy. The results showed that gamma ray irradiation could effectively degrade cyclohexanebutyric acid in aqueous solutions. The removal rate of cyclohexanebutyric acid increased significantly with the increase of absorbed dose and the decrease of its initial concentration. At the same time, the removal of chemical oxygen demand (COD) was as effective as that of cyclohexanebutyric acid. The kinetic studies showed that the degradation of cyclohexanebutyric acid followed pseudo first-order reaction. Above all, the proposed mechanism obtained when NaNO2, NaNO3 and tert-butanol were added showed that the OH radical played a major role in the gamma degradation process of cyclohexanebutyric acid, while H and eaq- played a minor role in the gamma degradation process. The degradation products were identified by Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass spectrometry (GC/MS) during cyclohexanebutyric acid degradation.

  6. THE INTERNAL-COLLISION-INDUCED MAGNETIC RECONNECTION AND TURBULENCE (ICMART) MODEL OF GAMMA-RAY BURSTS

    SciTech Connect

    Zhang Bing; Yan Huirong

    2011-01-10

    The recent Fermi observation of GRB 080916C shows that the bright photosphere emission associated with a putative fireball is missing, which suggests that the central engine likely launches a Poynting-flux-dominated (PFD) outflow. We propose a model of gamma-ray burst (GRB) prompt emission in the PFD regime, namely, the Internal-Collision-induced MAgnetic Reconnection and Turbulence (ICMART) model. It is envisaged that the GRB central engine launches an intermittent, magnetically dominated wind, and that in the GRB emission region, the ejecta is still moderately magnetized (e.g., 1 {approx}< {sigma} {approx}< 100). Similar to the internal shock (IS) model, the mini-shells interact internally at the radius R{sub IS} {approx} {Gamma}{sup 2} c{Delta}t. Most of these early collisions, however, have little energy dissipation, but serve to distort the ordered magnetic field lines entrained in the ejecta. At a certain point, the distortion of magnetic field configuration reaches the critical condition to allow fast reconnection seeds to occur, which induce relativistic MHD turbulence in the interaction regions. The turbulence further distorts field lines easing additional magnetic reconnections, resulting in a runway release of the stored magnetic field energy (an ICMART event). Particles are accelerated either directly in the reconnection zone, or stochastically in the turbulent regions, which radiate synchrotron photons that power the observed gamma rays. Each ICMART event corresponds to a broad pulse in the GRB light curve, and a GRB is composed of multiple ICMART events. This model retains the merits of IS and other models, but may overcome several difficulties/issues faced by the IS model (e.g., low efficiency, fast cooling, electron number excess, Amati/Yonetoku relation inconsistency, and missing bright photosphere). Within this model, the observed GRB variability timescales could have two components, one slow component associated with the central engine time history, and another fast component associated with relativistic magnetic turbulence in the emission region. The model predicts a decrease of gamma-ray polarization degree and E{sub p} in each ICMART event (broad pulse) during the prompt GRB phase, as well as a moderately magnetized external reverse shock. The model may be applied to the GRBs that have time-resolved, featureless Band-function spectra, such as GRB 080916C and most GRBs detected by Fermi LAT.

  7. Boron analysis for neutron capture therapy using particle-induced gamma-ray emission.

    PubMed

    Nakai, Kei; Yamamoto, Yohei; Okamoto, Emiko; Yamamoto, Tetsuya; Yoshida, Fumiyo; Matsumura, Akira; Yamada, Naoto; Kitamura, Akane; Koka, Masashi; Satoh, Takahiro

    2015-12-01

    The neutron source of BNCT is currently changing from reactor to accelerator, but peripheral facilities such as a dose-planning system and blood boron analysis have still not been established. To evaluate the potential application of particle-induced gamma-ray emission (PIGE) for boron measurement in clinical boron neutron capture therapy, boronophenylalanine dissolved within a cell culture medium was measured using PIGE. PIGE detected 18 μgB/mL f-BPA in the culture medium, and all measurements of any given sample were taken within 20 min. Two hours of f-BPA exposure was required to create a boron distribution image. However, even though boron remained in the cells, the boron on the cell membrane could not be distinguished from the boron in the cytoplasm. PMID:26242558

  8. Comparison of gamma-ray-induced chromosome ring and inversion frequencies

    SciTech Connect

    Muehlmann, M.C.; Bedford, J.S.

    1995-08-01

    A method was used to detect chromosome inversions as apparent or false sister chromatid exchanges (SCEs) in the first mitosis after {gamma} irradiation of human G{sub o} cells. Dose-response relationships for small inversions have not been measured and reported previously, but it has been assumed that these are induced with a frequency equal to that of their easily mesured asymmetrical counterpart, the interstitial deletion. Our experiments confirm this expectation. The results also demonstrate, as others have suggested, that in protocols where SCEs have been reported in the first postirradiation mitosis after incorporation of BrdU in the previous cell cycle, the X- or {gamma}-ray treatment of G{sub o}{sup {minus}} or G{sub 1}-phase cells produces virtually no true SCEs. 23 refs., 3 figs., 2 tabs.

  9. Development of a Reference Database for Particle-Induced Gamma-ray Emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Dimitriou, P.; Becker, H.-W.; Bogdanović-Radović, I.; Chiari, M.; Goncharov, A.; Jesus, A. P.; Kakuee, O.; Kiss, A. Z.; Lagoyannis, A.; Räisänen, J.; Strivay, D.; Zucchiatti, A.

    2016-03-01

    Particle-Induced Gamma-ray Emission (PIGE) is a powerful analytical technique that exploits the interactions of rapid charged particles with nuclei located near a sample surface to determine the composition and structure of the surface regions of solids by measurement of characteristic prompt γ rays. The potential for depth profiling of this technique has long been recognized, however, the implementation has been limited owing to insufficient knowledge of the physical data and lack of suitable user-friendly computer codes for the applications. Although a considerable body of published data exists in the nuclear physics literature for nuclear reaction cross sections with γ rays in the exit channel, there is no up-to-date, comprehensive compilation specifically dedicated to IBA applications. A number of PIGE cross-section data had already been uploaded to the Ion Beam Analysis Nuclear Data Library (IBANDL)

  10. Fermi large area telescope observations of the cosmic-ray induced {gamma}-ray emission of the Earth's atmosphere

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Bloom, E. D.; Borgland, A. W.; Bouvier, A.; Buehler, R.; Cameron, R. A.; Charles, E.; Chiang, J.; Claus, R.; Digel, S. W.; Couto e Silva, E. do; Drell, P. S.; Dubois, R.; Focke, W. B.; Funk, S.; Glanzman, T.

    2009-12-15

    We report on measurements of the cosmic-ray induced {gamma}-ray emission of Earth's atmosphere by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The Large Area Telescope has observed the Earth during its commissioning phase and with a dedicated Earth limb following observation in September 2008. These measurements yielded {approx}6.4x10{sup 6} photons with energies >100 MeV and {approx}250 hours total live time for the highest quality data selection. This allows the study of the spatial and spectral distributions of these photons with unprecedented detail. The spectrum of the emission--often referred to as Earth albedo gamma-ray emission--has a power-law shape up to 500 GeV with spectral index {gamma}=2.79{+-}0.06.

  11. Evaluation of the cosmic-ray induced background in coded aperture high energy gamma-ray telescopes

    NASA Technical Reports Server (NTRS)

    Owens, Alan; Barbier, Loius M.; Frye, Glenn M.; Jenkins, Thomas L.

    1991-01-01

    While the application of coded-aperture techniques to high-energy gamma-ray astronomy offers potential arc-second angular resolution, concerns were raised about the level of secondary radiation produced in a thick high-z mask. A series of Monte-Carlo calculations are conducted to evaluate and quantify the cosmic-ray induced neutral particle background produced in a coded-aperture mask. It is shown that this component may be neglected, being at least a factor of 50 lower in intensity than the cosmic diffuse gamma-rays.

  12. Ion-induced gamma-ray detection of fast ions escaping from fusion plasmas

    SciTech Connect

    Nishiura, M. Mushiake, T.; Doi, K.; Wada, M.; Taniike, A.; Matsuki, T.; Shimazoe, K.; Yoshino, M.; Nagasaka, T.; Tanaka, T.; Kisaki, M.; Fujimoto, Y.; Fujioka, K.; Yamaoka, H.; Matsumoto, Y.

    2014-11-15

    A 12 × 12 pixel detector has been developed and used in a laboratory experiment for lost fast-ion diagnostics. With gamma rays in the MeV range originating from nuclear reactions {sup 9}Be(α, nγ){sup 12}C, {sup 9}Be(d, nγ){sup 12}C, and {sup 12}C(d, pγ){sup 13}C, a high purity germanium (HPGe) detector measured a fine-energy-resolved spectrum of gamma rays. The HPGe detector enables the survey of background-gamma rays and Doppler-shifted photo peak shapes. In the experiments, the pixel detector produces a gamma-ray image reconstructed from the energy spectrum obtained from total photon counts of irradiation passing through the detector's lead collimator. From gamma-ray image, diagnostics are able to produce an analysis of the fast ion loss onto the first wall in principle.

  13. Ion-induced gamma-ray detection of fast ions escaping from fusion plasmas

    NASA Astrophysics Data System (ADS)

    Nishiura, M.; Doi, K.; Taniike, A.; Matsuki, T.; Shimazoe, K.; Mushiake, T.; Yoshino, M.; Nagasaka, T.; Fujimoto, Y.; Fujioka, K.; Tanaka, T.; Kisaki, M.; Yamaoka, H.; Matsumoto, Y.; Wada, M.

    2014-11-01

    A 12 12 pixel detector has been developed and used in a laboratory experiment for lost fast-ion diagnostics. With gamma rays in the MeV range originating from nuclear reactions 9Be(?, n?)12C, 9Be(d, n?)12C, and 12C(d, p?)13C, a high purity germanium (HPGe) detector measured a fine-energy-resolved spectrum of gamma rays. The HPGe detector enables the survey of background-gamma rays and Doppler-shifted photo peak shapes. In the experiments, the pixel detector produces a gamma-ray image reconstructed from the energy spectrum obtained from total photon counts of irradiation passing through the detector's lead collimator. From gamma-ray image, diagnostics are able to produce an analysis of the fast ion loss onto the first wall in principle.

  14. Ion-induced gamma-ray detection of fast ions escaping from fusion plasmas.

    PubMed

    Nishiura, M; Doi, K; Taniike, A; Matsuki, T; Shimazoe, K; Mushiake, T; Yoshino, M; Nagasaka, T; Fujimoto, Y; Fujioka, K; Tanaka, T; Kisaki, M; Yamaoka, H; Matsumoto, Y; Wada, M

    2014-11-01

    A 12 12 pixel detector has been developed and used in a laboratory experiment for lost fast-ion diagnostics. With gamma rays in the MeV range originating from nuclear reactions (9)Be(?, n?)(12)C, (9)Be(d, n?)(12)C, and (12)C(d, p?)(13)C, a high purity germanium (HPGe) detector measured a fine-energy-resolved spectrum of gamma rays. The HPGe detector enables the survey of background-gamma rays and Doppler-shifted photo peak shapes. In the experiments, the pixel detector produces a gamma-ray image reconstructed from the energy spectrum obtained from total photon counts of irradiation passing through the detector's lead collimator. From gamma-ray image, diagnostics are able to produce an analysis of the fast ion loss onto the first wall in principle. PMID:25430369

  15. Comparison of the biological effectiveness of 45 MeV C-ions and {gamma}-rays in inducing early and late effects in normal human primary fibroblasts

    SciTech Connect

    Fratini, E.; Balduzzi, M.; Antonelli, F.; Sorrentino, E.; Esposito, G.; Cuttone, G.; Romano, F.; Dini, V.; Simone, G.; Campa, A.; Tabocchini, M. A.; Belli, M.

    2013-07-18

    Investigation of the mechanisms underlying the biological effects induced by densely ionizing radiation has relevant implications in both radiation protection and therapy. In particular, the possible advantages of hadrontherapy with respect to conventional radiotherapy in terms of high conformal tumor treatment and sparing of healthy tissues are well known. Further improvements are limited by lack of radiobiological knowledge, particularly about the specific cellular response to the damage induced by particles of potential interest for tumor treatment. This study compares early and late effects induced in AG01522 normal human primary fibroblasts by {gamma}-rays and C-ions having E {approx} 45 MeV/u at the cell entrance, corresponding to LET (in water) {approx} 49 keV/{mu}m. Different end points have been investigated, namely: cell killing and lethal mutation, evaluated as early and delayed reproductive cell death, respectively; chromosome damage, as measured by micronuclei induction (MN); DNA damage, in terms of DSB induction and repair, as measured by the H2AX phosphorylation/dephosphorylation kinetics. Linear dose-response relationships were found for cell killing and induction of lethal mutations, with RBEs of about 1.3 and 1.6 respectively, indicating that the presence of genomic instability is greater in the progeny of C-ions irradiated cells. H2AX phosphorylation/dephosphorylation kinetics have shown a maximum foci number at 30 min after irradiation, higher for {gamma}-rays than for C-ions. However, in the first 12 h the fraction of residual {gamma}-H2AX foci was higher for C-ions irradiated cells, indicating a lower removal rate, possibly related to multiple/more complex damage along the particle track, with respect to the sparse lesions produced by {gamma}-rays. MN induction, observed after 72 h from irradiation, was also greater for C-ions. Overall, these data indicate a more severe DNA damage induced by 45 MeV/u C-ions with respect to {gamma}-rays, likely responsible of an increased cellular misrepair, leading to the greater observed levels of chromosome damage and, eventually, of genomic instability. They give strong support to the idea that higher damage severity at molecular level, determined by the typical deposition pattern of densely ionizing radiation, is the earliest relevant factor for the more severe late effects at cellular level.

  16. Microscopic observations of X-ray and gamma-ray induced decomposition of ammonium perchlorate crystals

    NASA Technical Reports Server (NTRS)

    Herley, P. J.; Levy, P. W.

    1972-01-01

    The X-ray and gamma-ray induced decomposition of ammonium perchlorate was studied by optical, transmission, and scanning electron microscopy. This material is a commonly used oxidizer in solid propellents which could be employed in deep-space probes, and where they will be subjected to a variety of radiations for as long as ten years. In some respects the radiation-induced damage closely resembles the effects produced by thermal decomposition, but in other respects the results differ markedly. Similar radiation and thermal effects include the following: (1) irregular or ill-defined circular etch pits are formed in both cases; (2) approximately the same size pits are produced; (3) the pit density is similar; (4) the c face is considerably more reactive than the m face; and (5) most importantly, many of the etch pits are aligned in crystallographic directions which are the same for thermal or radiolytic decomposition. Thus, dislocations play an important role in the radiolytic decomposition process.

  17. Charged Particle Induced Radiation damage of Germanium Detectors in Space: Two Mars Observer Gamma-Ray Detectors

    NASA Technical Reports Server (NTRS)

    Bruekner, J.; Koenen, M.; Evans, L. G.; Starr, R.; Bailey, S. H.; Boynton W. V.

    1997-01-01

    The Mars Observer Gamma-Ray Spectrometer (MO GRS) was designed to measure gamma-rays emitted by the Martian surface. This gamma-ray emission is induced by energetic cosmic-ray particles penetrating the Martian surface and producing many secondary particles and gamma rays. The MO GRS consisted of an high-purity germanium (HPGe) detector with a passive cooler. Since radiation damage due to permanent bombardment of energetic cosmic ray particles (with energies up to several GeV) was expected for the MO GRS HPGe crystal, studies on radiation damage effects of HPGe crystals were carried on earth. One of the HPGe crystals (paradoxically called FLIGHT) was similar to the MO GRS crystal. Both detectors, MO GRS and FLIGHT, contained closed-end coaxial n-type HPGe crystals and had the same geometrical dimensions (5.6 x 5.6 cm). Many other parameters, such as HV and operation temperature, differed in space and on earth, which made it somewhat difficult to directly compare the performance of both detector systems. But among other detectors, detector FLIGHT provided many useful data to better understand radiation damage effects.

  18. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1992-01-01

    Miscellaneous tasks related to mission operations and data analysis for the Burst and Transient Source Experiment on the Gamma Ray Observatory, to collection, analysis, and interpretation of data from the Marshall Space Flight Center Very Low Frequency transient monitoring program, and to compilation and analysis of induced radioactivity data were performed. The results are summarized and relevant references are included.

  19. Mutation measurement in mammalian cells. IV: Comparison of gamma-ray and chemical mutagenesis.

    PubMed

    Puck, T T; Johnson, R; Webb, P; Yohrling, G

    1998-01-01

    The interaction of chemical mutagens with mammalian cells is much more complex than that of gamma-irradiation because of the different ways in which chemical agents react with cell and medium components. Nevertheless, the system previously described for analysis of mutagenesis by gamma-radiation appears applicable to chemical mutagenesis. The approach involves measurement of cell survival, use of caffeine to inhibit repair, analysis of mitotic index changes, and quantitation of microscopically visible structural changes in mitotic chromosomes. The behavior of a variety of chemical mutagens and nonmutagens in this system is described and compared with that of gamma-irradiation. The procedure is simple and the results reasonably quantitative though less so than those of gamma-irradiation. The procedure can be used for environmental monitoring, analysis of mutational events, and individual and epidemiological testing. Mutational events should be classified as primary or secondary depending on whether they represent initial genomic insult, or genomic changes resulting from primary mutation followed by structural changes due to metabolic actions. While caffeine has multiple effects on the mammalian genome, when used under the conditions specified here it appears to act principally as an inhibitor of mutation repair, and so affords a measure of the role of repair in the action of different mutagens on cells in the G2 phase of the life cycle. PMID:9776977

  20. Clonally Expanding Thymocytes Having Lineage Capability in Gamma-Ray-Induced Mouse Atrophic Thymus

    SciTech Connect

    Yamamoto, Takashi; Morita, Shin-ichi; Go, Rieka; Obata, Miki; Katsuragi, Yoshinori; Fujita, Yukari; Maeda, Yoshitaka; Yokoyama, Minesuke; Aoyagi, Yutaka; Ichikawa, Hitoshi; Mishima, Yukio; Kominami, Ryo

    2010-05-01

    Purpose: To characterize, in the setting of gamma-ray-induced atrophic thymus, probable prelymphoma cells showing clonal growth and changes in signaling, including DNA damage checkpoint. Methods and Materials: A total of 111 and 45 mouse atrophic thymuses at 40 and 80 days, respectively, after gamma-irradiation were analyzed with polymerase chain reaction for D-J rearrangements at the TCRbeta locus, flow cytometry for cell cycle, and Western blotting for the activation of DNA damage checkpoints. Results: Limited D-J rearrangement patterns distinct from normal thymus were detected at high frequencies (43 of 111 for 40-day thymus and 21 of 45 for 80-day thymus). Those clonally expanded thymocytes mostly consisted of CD4{sup +}CD8{sup +} double-positive cells, indicating the retention of lineage capability. They exhibited pausing at a late G1 phase of cell cycle progression but did not show the activation of DNA damage checkpoints such as gammaH2AX, Chk1/2, or p53. Of interest is that 17 of the 52 thymuses showing normal D-J rearrangement patterns at 40 days after irradiation showed allelic loss at the Bcl11b tumor suppressor locus, also indicating clonal expansion. Conclusion: The thymocytes of clonal growth detected resemble human chronic myeloid leukemia in possessing self-renewal and lineage capability, and therefore they can be a candidate of the lymphoma-initiating cells.

  1. Gamma-ray-induced damage and recovery behavior in an erbium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Bussjager, Rebecca J.; Hayduk, Michael J.; Johns, Steven T.; Taylor, Linda R.; Taylor, Edward W.

    2002-01-01

    Erbium-doped fiber lasers (EDFLs) may soon find applications in space as high bit rate optical communication systems and photonic analog-to-digital converters (ADCs). The rapid advancement in digital signal processing systems has led to an increased interest in the direct digitization of high- frequency analog signals. The potential high bandwidth, reduced weight, and reduced power requirements makes photonics an attractive technology for wide-band signal conversion as well as for use in space-based platforms. It is anticipated that photonic ADCs will be able to operate at sampling rates and resolutions far greater than current electronic ADCs. The high repetition rates and narrow pulse widths produced by EDFLs allow for high-speed impulse sampling of analog signals thus making it a vital component of a photonic ADC. In this paper we report on the in situ gamma-ray irradiation of an actively mode-locked EDFL operating at 1530 nm. The onset, growth and extent of ionization induced damage under time-resolved operational conditions is presented. The laser consisted of approximately 3 meters of erbium-doped fiber pumped by a laser diode operating at 980 nm. The picosecond pulses produced by the laser were initiated and controlled by a Mach-Zehnder lithium niobate electro-optic modulator. The active mode-locking element allowed for the precise timing control of the laser repetition rate which is critical in high-speed optical networking systems as well as in photonic ADCs.

  2. Neutron-induced gamma-ray production from carbon and nitrogen

    SciTech Connect

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

    1994-06-01

    Gamma-ray production cross sections and angular distributions were measured with five 7.6 cm diameter {times} 7.6 cm long BGO detectors at the high-energy white neutron source of the WNR facility at Los Alamos for targets of C {sup 14}NH{sub 3} and {sup 15}NH{sub 3}. Gamma rays were measured in the energy range from 1.4 to 25 MeV. The incident neutron energies spanned the range from 2 to over 100 MeV. The detectors were positioned at angles of 39{degree}, 55{degree}, 90{degree}, 125{degree}, and 144{degree} with respect to the neutron beam. We have extracted angular distributions and cross sections for the 4.44 and 15.1 MeV {gamma} rays from inelastic excitation of C for 4 < E{sub n} < 150 MeV. In ENDF-B/VI these {gamma}-rays are treated as being isotropic. Our angular distributions show that this is not the case. For the nitrogen isotopes we have extracted angular distributions and cross sections for several {gamma} rays in the neutron energy range, 2 < E{sub n} < 20 MeV.

  3. Early and Late Chromosome Damages in Human Lymphocytes Induced by Gamma Rays and Fe Ions

    NASA Technical Reports Server (NTRS)

    Sunagawa, Mayumi; Zhang, Ye; Yeshitla, Samrawit; Kadhim, Munira; Wilson, Bobby; Wu, Honglu

    2014-01-01

    Chromosomal translocations and inversions are considered stable, and cells containing these types of chromosome aberrations can survive multiple cell divisions. An efficient method to detect an inversion is multi-color banding fluorescent in situ hybridization (mBAND) which allows identification of both inter- and intrachromosome aberrations simultaneously. Post irradiation, chromosome aberrations may also arise after multiple cell divisions as a result of genomic instability. To investigate the stable or late-arising chromosome aberrations induced after radiation exposure, we exposed human lymphocytes to gamma rays and Fe ions ex vivo, and cultured the cells for multiple generations. Chromosome aberrations were analyzed in cells collected at first mitosis and at several time intervals during the culture period post irradiation. With gamma irradiation, about half of the damages observed at first mitosis remained after 7 day- and 14 day- culture, suggesting the transmissibility of damages to the surviving progeny. Detailed analysis of chromosome break ends participating in exchanges revealed a greater fraction of break ends involved in intrachromosome aberrations in the 7- and 14-day samples in comparison to the fraction at first mitosis. In particular, simple inversions were found at 7 and 14 days, but not at the first mitosis, suggesting that some of the aberrations might be formed days post irradiation. In contrast, at the doses that produced similar frequencies of gamma-induced chromosome aberrations as observed at first mitosis, a significantly lower yield of aberrations remained at the same population doublings after Fe ion exposure. At these equitoxic doses, more complex type aberrations were observed for Fe ions, indicating that Fe ion-induced initial chromosome damages are more severe and may lead to cell death. Comparison between low and high doses of Fe ion irradiation in the induction of late damages will also be discussed.

  4. EMISSION PATTERNS AND LIGHT CURVES OF GAMMA RAYS IN THE PULSAR MAGNETOSPHERE WITH A CURRENT-INDUCED MAGNETIC FIELD

    SciTech Connect

    Li, X.; Zhang, L.

    2011-12-20

    We study the emission patterns and light curves of gamma rays in the pulsar magnetosphere with a current-induced magnetic field perturbation. Based on the solution of a static dipole with the magnetic field induced by some currents (perturbation field), we derive the solutions of a static as well as a retarded dipole with the perturbation field in the Cartesian coordinates. The static (retarded) magnetic field can be expressed as the sum of the pure static (retarded) dipolar magnetic field and the static (retarded) perturbation field. We use the solution of the retarded magnetic field to investigate the influence of the perturbation field on the emission patterns and light curves, and apply the perturbed solutions to calculate the gamma-ray light curves for the case of the Vela pulsar. We find that the perturbation field induced by the currents will change the emission patterns and then the light curves of gamma rays, especially for a larger perturbation field. Our results indicate that the perturbation field created by the outward-flowing (inward-flowing) electrons (positrons) can decrease the rotation effect on the magnetosphere and makes emission pattern appear to be smoother relative to that of the pure retarded dipole, but the perturbation field created by the outward-flowing (inward-flowing) positrons (electrons) can make the emission pattern less smooth.

  5. Possible effects on avionics induced by terrestrial gamma-ray flashes

    NASA Astrophysics Data System (ADS)

    Tavani, M.; Argan, A.; Paccagnella, A.; Pesoli, A.; Palma, F.; Gerardin, S.; Bagatin, M.; Trois, A.; Picozza, P.; Benvenuti, P.; Flamini, E.; Marisaldi, M.; Pittori, C.; Giommi, P.

    2013-04-01

    Terrestrial gamma-ray flashes (TGFs) are impulsive (intrinsically sub-millisecond) events associated with lightning in powerful thunderstorms. TGFs turn out to be very powerful natural accelerators known to accelerate particles and generate radiation up to hundreds of MeV energies. The number ratio of TGFs over normal lightning has been measured in tropical regions to be near 10-4. We address in this Article the issue of the possible susceptibility of typical aircraft electronics exposed to TGF particle, gamma ray and neutron irradiation. We consider possible scenarios regarding the intensity, the duration, and geometry of TGFs influencing nearby aircraft, and study their effects on electronic equipment. We calculate, for different assumptions, the total dose and the dose-rate, and estimate single-event-effects. We find that in addition to the electromagnetic component (electrons/positrons, gamma rays) also secondary neutrons produced by gamma-ray photo production in the aircraft structure substantially contribute to single-event effects in critical semiconductors components. Depending on the physical characteristics and geometry, TGFs may deliver a large flux of neutrons within a few milliseconds in an aircraft. This flux is calculated to be orders of magnitude larger than the natural cosmic-ray background, and may constitute a serious hazard to aircraft electronic equipment. We present a series of numerical simulations supporting our conclusions. Our results suggest the necessity of dedicated measurement campaigns addressing the radiative and particle environment of aircraft near or within thunderstorms.

  6. PROTON INDUCED GAMMA-RAY ANALYSIS OF ATMOSPHERIC AEROSOLS FOR CARBON, NITROGEN, AND SULFUR COMPOSITION

    EPA Science Inventory

    A technique for the simultaneous quantitative analysis of carbon, nitrogen, and sulfur using in-beam gamma-ray spectrometry has been developed for use with atmospheric aerosol samples. Samples are collected on quartz filters, and the aerosol composition is determined by analyzing...

  7. Multiple fractions of gamma rays induced resistance to cis-dichloro-diammineplatinum (II) and methotrexate in human HeLa cells

    SciTech Connect

    Osmak, M.; Perovic, S. )

    1989-06-01

    Previous irradiation could induce changes in the cell-sensitivity to additional cytotoxic agents. In this study we examined whether the sensitivity to additional cytotoxic agents was affected in cells irradiated with multiple fractions of gamma rays if these agents were given at the time when the lesions induced in DNA by radiation have already been repaired. Human cervix carcinoma HeLa cells were irradiated daily with 0.5 Gy of gamma rays five times a week for 6 weeks. When the fractionation regimen was completed, that is when the cells had accumulated the total dose of 15 Gy of gamma rays, the sensitivity of these cells to gamma rays, UV light, cis-dichlorodiammineplatinum (II) (cis-DDP), methotrexate (MTX), and hydroxyurea (HU) was examined and compared to control cells. Results revealed that preirradiated cells did not change sensitivity to gamma rays and UV light, but that they increased the resistance to cis-DDP, and MTX (especially for higher concentrations of MTX), and increased sensitivity to HU (for lower concentrations of HU). The increased resistance to cis-DDP was also measurable up to 30 days after the last dose of gamma rays. The results indicate that preirradiation of HeLa cells with multiple fractions of gamma rays could change their sensitivity to additional cytotoxic agents, and that this is a relatively long-lasting effect. Our results suggest that caution is needed in medical application of radiation combined with chemical treatment.

  8. Limits on thunderstorm-induced radioactive chlorine from gamma ray observations

    NASA Astrophysics Data System (ADS)

    Lundberg, J. L.; Millan, R. M.; Eack, K.

    2011-11-01

    We present analysis of thunderstorm data collected with a liquid nitrogen-cooled germanium spectrometer with energies between 13 keV-2.6 MeV that was deployed at Langmuir Lab on South Baldy Peak in New Mexico for June through August 2005. The motivation was to search for gamma ray emissions from radioactive chlorine-39 and chlorine-38, as suggested by Greenfield et al. (2003). Based on the observations, we place an upper limit on the rate of chlorine production through such a process (6.8 × 10-17 chlorine atoms per argon atom). This rate is sufficiently low to suggest that the anomalous gamma ray count increases observed by Greenfield et al. (2003) were not caused by radioactive chlorine.

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  10. Search for Cosmic-Ray-Induced Gamma-Ray Emission in Galaxy Clusters

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cavazzuti, E.; Chaves, R. C. G.; Kuss, M.; Pesce-Rollins, M.; Sgro, C.; Spandre, G.; Tinivella, M.

    2014-01-01

    Current theories predict relativistic hadronic particle populations in clusters of galaxies in addition to the already observed relativistic leptons. In these scenarios hadronic interactions give rise to neutral pions which decay into gamma rays that are potentially observable with the Large Area Telescope (LAT) on board the Fermi space telescope. We present a joint likelihood analysis searching for spatially extended gamma-ray emission at the locations of 50 galaxy clusters in four years of Fermi-LAT data under the assumption of the universal cosmic-ray (CR) model proposed by Pinzke & Pfrommer. We find an excess at a significance of 2.7 delta, which upon closer inspection, however, is correlated to individual excess emission toward three galaxy clusters: A400, A1367, and A3112. We discuss these cases in detail and conservatively attribute the emission to unmodeled background systems (for example, radio galaxies within the clusters).Through the combined analysis of 50 clusters, we exclude hadronic injection efficiencies in simple hadronic models above 21% and establish limits on the CR to thermal pressure ratio within the virial radius, R(sub 200), to be below 1.25%-1.4% depending on the morphological classification. In addition, we derive new limits on the gamma-ray flux from individual clusters in our sample.

  11. Time Variability of VHE Gamma-Ray Induced Pair Cascades in AGN Environments

    NASA Astrophysics Data System (ADS)

    Roustazadeh, Parisa; Thrush, Samantha Elaine; Boettcher, Markus

    2016-01-01

    In a series of previous papers, we had investigated the three-dimensional development of pair cascades initiated by very-high-energy gamma-rays from the relativistic jets of blazars, especially in the case of low-frequency peaked blazars which are expected to host dense radiation environments. Gamma-gamma absorption and pair production leads to the development of pair cascades which will be deflected and partially isotropised by magnetic fields in the nuclear environment. This has been suggested to make a significant contribution to the Fermi gamma-ray emission of radio galaxies. In this work, we present the study of the time dependence of these cascades, demonstrating that they can be variable on time scales much shorter than the light-crossing time through the characteristic extent of the circumnuclear radiation field. Thus, this interpretation is still consistent with the Fermi gamma-ray emission of radio galaxies such as NGC 1275, even considering the recently observed short-term variability.

  12. Cosmic-ray induced gamma-ray emission from the starburst galaxy NGC 253

    SciTech Connect

    Wang, Xilu; Fields, Brian D.

    2014-05-09

    Cosmic rays in galaxies interact with the interstellar medium and give us a direct view of nuclear and particle interactions in the cosmos. For example, cosmic-ray proton interactions with interstellar hydrogen produce gamma rays via PcrPism→π{sup 0}→γγ. For a 'normal' star-forming galaxy like the Milky Way, most cosmic rays escape the Galaxy before such collisions, but in starburst galaxies with dense gas and huge star formation rate, most cosmic rays do suffer these interactions [1,2]. We construct a 'thick-target' model for starburst galaxies, in which cosmic rays are accelerated by supernovae, and escape is neglected. This model gives an upper limit to the gamma-ray emission. Only two free parameters are involved in the model: cosmic-ray proton acceleration energy rate from supernova and the proton injection spectral index. The pionic gamma-radiation is calculated from 10 MeV to 10 TeV for the starburst galaxy NGC 253, and compared to Fermi and HESS data. Our model fits NGC 253 well, suggesting that cosmic rays in this starburst are in the thick target limit, and that this galaxy is a gamma-ray calorimeter.

  13. Rapid, non-destructive carbon analysis of forest soils using neutron-induced gamma-ray spectroscopy

    SciTech Connect

    Wielopolski, L.; Mitra, S.; Yanai, R. D.; Levine, C. R.; Vadeboncoeur, M. A.

    2010-08-01

    Forest soils are pivotal to understanding global carbon (C) cycling and evaluating policies for mitigating global change. However, they are very difficult to monitor because of the heterogeneity of soil characteristics, the difficulty of representative sampling, and the slow time scale of response to environmental change. Here we demonstrate that use of gamma-ray spectroscopy facilitates in situ non-destructive analysis of C and other elements in forest soils. In this approach the element-specific gamma-rays are induced by fast and thermal neutrons interacting with the nuclei of the elements present in the soil. Background gamma-rays emanating from naturally occurring radionuclides in the forest are recorded as well. We applied this approach in a mature northern hardwood forest on glacial till soils at the Bartlett Experimental Forest in New Hampshire, USA. The inelastic neutron scattering (INS) system yielded strong signals in gamma-ray counts/h, from C and other elements present in the soil matrix that included silicon, oxygen, hydrogen, iron, aluminum, manganese and potassium. The INS sensitivity for carbon was 20.656 counts h{sup -1} kg{sup -1} C m{sup -2} based on current net C gamma-ray counts and the data for the O horizon and mineral soil to a depth of 30 cm obtained from a nearby quantitative soil pit (7.35 kg C m{sup -2}). We estimate the minimum detectable change to be {approx}0.34 kg C m{sup -2}, which is {approx}5% of the current soil C content, and the minimum detectable limit to be {approx}0.23 kg C m{sup -1}. Eight % reproducibility from 11 measurements was limited, in part, by the large variability in the system counting geometry due to the uneven forest microtopography. The INS approach has the potential to revolutionize belowground monitoring of C and other elements, because the possibility of detecting a 5% change in forest soils has not been possible with destructive sampling methods.

  14. Gamma ray generator

    DOEpatents

    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.

  15. Enhancement in gamma ray induced decomposition of zirconium and thorium nitrates in sulfate matrix in solid state

    NASA Astrophysics Data System (ADS)

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

    1994-12-01

    Gamma ray induced decomposition of zirconium and thorium nitrates in sulfate matrices doped with common cation and alkali metal (Na, K) cations at various concentrations has been studied. G(NO? 2) values of the nitrate salt are found to increase with the concentration of the sulfate in the binary mixture. Electron spin resonance (ESR), thermoluminescence (TL) and reflectance spectral studies suggest the formation of radical species SO? 4, SO? 3, O? 3, O? 2; which may be responsible for the energy transfer to nitrate. Efficiency of energy transfer follows the order K2SO4 > Na2SO4 > Zr/Th sulfate. A possible mechanism has been suggested.

  16. In vivo elemental analysis by counting neutron-induced gamma rays for medical and biological applications

    NASA Astrophysics Data System (ADS)

    Kehayias, Joseph J.; Ma, Ruimei; Zhuang, Hong; Moore, Robert; Dowling, Lisa

    1995-03-01

    Non-invasive in vivo elemental analysis is a technique used to assess human body composition which is indicative of nutritional status and health condition. The in vivo measurement of the body's major elements is used for a variety of medical studies requiring the determination of the body's compartments (protein, fat, water, bone). Whole body gamma-ray counters, consisting of Nal(Tl) crystal detectors in a shielded room, are used for measuring in vivo the body's Ca, Cl, Na and P by delayed neutron activation analysis. Thermal neutrons from a moderated 238Pu-Be source are used for the measurement of total body nitrogen (and thus protein) and chlorine at low radiation exposure (0.80 mSv). The resulting high energy prompt gamma-rays from nitrogen (10.83 MeV) and chlorine (6.11 MeV) are detected simultaneously with the irradiation. Body fat (the main energy store) and fat distribution (which relates to risk for cardiovascular disease) are measured by detecting C and O in vivo through fast neutron inelastic scattering. A small sealed D-T neutron generator is used for the pulsed (4 - 8 KHz) production of fast neutrons. Carbon and oxygen are detected by counting the 4.44 and 6.13 MeV gamma-rays resulting from the inelastic scattering of the fast neutrons from the 12C and 16O nuclei, respectively. One use of this method is the systematic study of the mechanisms driving the age-associated depletion of the metabolizing, oxygen-consuming cellular compartment of the body. The understanding of this catabolism may suggest ways to maintain lean tissue and thus to preserve quality of life for the very old.

  17. SYNCHROTRON EMISSION FROM VERY HIGH ENERGY GAMMA-RAY-INDUCED PAIR CASCADES IN ACTIVE GALACTIC NUCLEUS ENVIRONMENTS

    SciTech Connect

    Roustazadeh, P.; Boettcher, M.

    2012-05-01

    The discovery of very high energy (VHE; E > 100 GeV) {gamma}-ray emission from intermediate- and low-frequency-peaked blazars suggests that {gamma}{gamma} absorption and pair cascading might occur in these objects. In previous papers, we investigated the Compton emission from VHE {gamma}-ray-induced pair cascades, deflected by moderate magnetic fields, in a largely model-independent way, and demonstrated that this emission can explain the Fermi fluxes and spectra of the radio galaxies Cen A and NGC 1275. In this paper, we describe a generalization of our Monte Carlo cascade code to include the angle-dependent synchrotron output from the cascades, allowing for the application to situations with non-negligible magnetic fields, leading to potentially observable synchrotron signatures, but still not dominating the radiative energy loss of cascade particles. We confirm that the synchrotron radiation from the cascades in NGC 1275 and Cen A is negligible for the parameters used in our previous works. We demonstrate that the magnetic field cannot be determined from a fit of the cascade emission to the {gamma}-ray spectrum alone, and the degeneracy can only be lifted if the synchrotron emission from the cascades is observed as well. We illustrate this fact with the example of NGC 1275. We point out that the cascade synchrotron emission may produce spectral features in the same energy range in which the big blue bump is observed in the spectral energy distributions of several blazars, and may make a non-negligible contribution to this feature. We illustrate this idea with the example of 3C 279.

  18. Chemical warfare agent and high explosive identification by spectroscopy of neutron-induced gamma rays

    SciTech Connect

    Caffrey, A.J.; Cole, J.D.; Gehrke, R.J.; Greenwood, R.C. )

    1992-10-01

    This paper reports on a non-destructive assay method to identify chemical warfare (CW) agents and high explosive (HE) munitions which was tested with actual chemical agents and explosives at the Tooele Army Depot, Tooele, Utah, from 22 April 1991 through 3 May 1991. The assay method exploits the gamma radiation produced by neutron interactions inside a container or munition to identify the elemental composition of its contents. The characteristic gamma-ray signatures of the chemical elements chlorine, phosphorus, and sulfur were observed form the CW agent containers and munitions, in sufficient detail to enable us to reliably discern agents GB (sarin), HD (mustard gas), and VX from one another, and from HE-filled munitions. By detecting of the presence of nitrogen, the key indictor of explosive compounds, and the absence of elements Cl, P, and S, HE shells were also clearly identified.

  19. Gamma-Ray Polarization Induced by Cold Electrons via Compton Processes

    NASA Astrophysics Data System (ADS)

    Chang, Zhe; Jiang, Yunguo; Lin, Hai-Nan

    2013-05-01

    The polarization measurement is an important tool to probe the prompt emission mechanism in gamma-ray bursts (GRBs). The synchrotron photons can be scattered by cold electrons in the outflow via Compton scattering (CS) processes. The observed polarization depends on both the photon energy and the viewing angle. With the typical bulk Lorentz factor Γ ~ 200, photons with energy E > 10 MeV tend to have smaller polarization than photons with energy E < 1 MeV. At the right viewing angle, i.e., θ ~ Γ-1, the polarization achieves its maximal value, and the polarization angle changes 90° relative to the initial polarization direction. Thus, the synchrotron radiation plus CS model can naturally explain the 90° change of the polarization angle in GRB 100826A.

  20. Sex-dependent Differences in Intestinal Tumorigenesis Induced in Apc1638N/+ Mice by Exposure to {gamma} Rays

    SciTech Connect

    Trani, Daniela; Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, District of Columbia; Maastricht Radiation Oncology Lab, GROW-School for Oncology and Developmental Biology, University of Maastricht ; Moon, Bo-Hyun; Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, District of Columbia ; Kallakury, Bhaskar; Hartmann, Dan P.; Datta, Kamal; Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, District of Columbia ; Fornace, Albert J.

    2013-01-01

    Purpose: The purpose of the present study was to assess the effect of 1 and 5 Gy radiation doses and to investigate the interplay of gender and radiation with regard to intestinal tumorigenesis in an adenomatous polyposis coli (APC) mutant mouse model. Methods and Materials: Apc1638N/+ female and male mice were exposed whole body to either 1 Gy or 5 Gy of {gamma} rays and euthanized when most of the treated mice became moribund. Small and large intestines were processed to determine tumor burden, distribution, and grade. Expression of proliferation marker Ki-67 and estrogen receptor (ER)-{alpha} were also assessed by immunohistochemistry. Results: We observed that, with both 1 Gy and 5 Gy of {gamma} rays, females displayed reduced susceptibility to radiation-induced intestinal tumorigenesis compared with males. As for radiation effect on small intestinal tumor progression, although no substantial differences were found in the relative frequency and degree of dysplasia of adenomas in irradiated animals compared with controls, invasive carcinomas were found in 1-Gy- and 5-Gy-irradiated animals. Radiation exposure was also shown to induce an increase in protein levels of proliferation marker Ki-67 and sex-hormone receptor ER-{alpha} in both non tumor mucosa and intestinal tumors from irradiated male mice. Conclusions: We observed important sex-dependent differences in susceptibility to radiation-induced intestinal tumorigenesis in Apc1638N/+ mutants. Furthermore, our data provide evidence that exposure to radiation doses as low as 1 Gy can induce a significant increase in intestinal tumor multiplicity as well as enhance tumor progression in vivo.

  1. Body composition to climate change studies - the many facets of neutron induced prompt gamma-ray analysis

    SciTech Connect

    Mitra,S.

    2008-11-17

    In-vivo body composition analysis of humans and animals and in-situ analysis of soil using fast neutron inelastic scattering and thermal neutron capture induced prompt-gamma rays have been described. By measuring carbon (C), nitrogen (N) and oxygen (O), protein, fat and water are determined. C determination in soil has become important for understanding below ground carbon sequestration process in the light of climate change studies. Various neutron sources ranging from radio isotopic to compact 14 MeV neutron generators employing the associated particle neutron time-of-flight technique or micro-second pulsing were implemented. Gamma spectroscopy using recently developed digital multi-channel analyzers has also been described.

  2. Thermal and Gamma-ray induced relaxation in As-S glasses: modeling and experiment

    SciTech Connect

    Lucas, Pierre; King, Ellyn A.; Erdmann, Robert G.; Riley, Brian J.; Sundaram, S. K.; McCloy, John S.

    2011-09-09

    Enthalpy relaxation is measured in a series of As-S glasses irradiated with gamma rays and these samples are compared with a set of identical control samples kept in the dark. It is shown that gamma irradiation lifts the kinetic barrier for relaxation at room temperature and speeds up the enthalpy release. The measured values of thermal relaxation in the dark agree closely with modeling results obtained by fitting differential scanning calorimetry curves with the TNM equations. The measured values of activation energy for enthalpy relaxation are also in close agreement with that predicted by the TNM model therefore lending credence to the fitting results. These measurements permit extraction of the effect of gamma irradiation on the glass structure for a series of As-S glasses with increasing structural coordination, and gamma irradiation is shown to reduce the structural relaxation time. It is also shown that lower coordination glasses exhibit greater radiation sensitivity but also greater thermal relaxation due to their lower Tg. On the other end, over-coordinated glasses show lower relaxation and almost no radiation sensitivity. This behavior is similar to the glass response under sub-bandgap light irradiation.

  3. Assessment of gamma ray-induced DNA damage in Lasioderma serricorne using the comet assay

    NASA Astrophysics Data System (ADS)

    Kameya, Hiromi; Miyanoshita, Akihiro; Imamura, Taro; Todoriki, Setsuko

    2012-03-01

    We attempted a DNA comet assay under alkaline conditions to verify the irradiation treatment of pests. Lasioderma serricorne (Fabricius) were chosen as test insects and irradiated with gamma rays from a 60Co source at 1 kGy. We conducted the comet assay immediately after irradiation and over time for 7 day. Severe DNA fragmentation in L. serricorne cells was observed just after irradiation and the damage was repaired during the post-irradiation period in a time-dependent manner. The parameters of the comet image analysis were calculated, and the degree of DNA damage and repair were evaluated. Values for the Ratio (a percentage determined by fluorescence in the damaged area to overall luminance, including intact DNA and the damaged area of a comet image) of individual cells showed that no cells in the irradiated group were included in the Ratio<0.1 category, the lowest grade. This finding was observed consistently throughout the 7-day post-irradiation period. We suggest that the Ratio values of individual cells can be used as an index of irradiation history and conclude that the DNA comet assay under alkaline conditions, combined with comet image analysis, can be used to identify irradiation history.

  4. Gamma ray-induced synthesis of hyaluronic acid/chondroitin sulfate-based hydrogels for biomedical applications

    NASA Astrophysics Data System (ADS)

    Zhao, Linlin; Gwon, Hui-Jeong; Lim, Youn-Mook; Nho, Young-Chang; Kim, So Yeon

    2015-01-01

    Hyaluronic acid (HA)/chondroitin sulfate (CS)/poly(acrylic acid) (PAAc) hydrogel systems were synthesized by gamma-ray irradiation without the use of additional initiators or crosslinking agents to achieve a biocompatible hydrogel system for skin tissue engineering. HA and CS derivatives with polymerizable residues were synthesized. Then, the hydrogels composed of glycosaminoglycans, HA, CS, and a synthetic ionic polymer, PAAc, were prepared using gamma-ray irradiation through simultaneous free radical copolymerization and crosslinking. The physicochemical properties of the HA/CS/PAAc hydrogels having various compositions were investigated to evaluate their feasibility as artificial skin substitutes. The gel fractions of the HA/CS/PAAc hydrogels increased in absorbed doses up to 15 kGy, and they exhibited 91-93% gel fractions under 15 kGy radiation. All of the HA/CS/PAAc hydrogels exhibited relatively high water contents of over 90% and reached an equilibrium swelling state within 24 h. The enzymatic degradation kinetics of the HA/CS/PAAc hydrogels depended on both the concentration of the hyaluronidase solution and the ratio of HA/CS/PAAc. The in vitro drug release profiles of the HA/CS/PAAc hydrogels were significantly influenced by the interaction between the ionic groups in the hydrogels and the ionic drug molecules as well as the swelling of the hydrogels. From the cytotoxicity results of human keratinocyte (HaCaT) cells cultured with extracts of the HA/CS/PAAc hydrogels, all of the HA/CS/PAAc hydrogel samples tested showed relatively high cell viabilities of more than 82%, and did not induce any significant adverse effects on cell viability.

  5. Gamma ray transients

    NASA Technical Reports Server (NTRS)

    Cline, Thomas L.

    1987-01-01

    The discovery of cosmic gamma ray bursts was made with systems designed at Los Alamos Laboratory for the detection of nuclear explosions beyond the atmosphere. HELIOS-2 was the first gamma ray burst instrument launched; its initial results in 1976, seemed to deepen the mystery around gamma ray transients. Interplanetary spacecraft data were reviewed in terms of explaining the behavior and source of the transients.

  6. Freshly induced short-lived gamma-ray activity as a measure of fission rates in lightly re-irradiated spent fuel

    NASA Astrophysics Data System (ADS)

    Kröhnert, H.; Perret, G.; Murphy, M. F.; Chawla, R.

    2010-12-01

    A new measurement technique has been developed to determine fission rates in burnt fuel, following re-irradiation in a zero-power research reactor. The development has been made in the frame of the LIFE@PROTEUS program at the Paul Scherrer Institute, which aims at characterizing the interfaces between fresh and highly burnt fuel assemblies in modern LWRs. To discriminate against the high intrinsic gamma-ray activity of the burnt fuel, the proposed measurement technique uses high-energy gamma-rays, above 2000 keV, emitted by short-lived fission products freshly produced in the fuel. To demonstrate the feasibility of this technique, a fresh UO 2 sample and a 36 GWd/t burnt UO 2 sample were irradiated in the PROTEUS reactor and their gamma-ray activities were recorded directly after irradiation. For both fresh and the burnt fuel samples, relative fission rates were derived for different core positions, based on the short-lived 142La (2542 keV), 89Rb (2570 keV), 138Cs (2640 keV) and 95Y (3576 keV) gamma-ray lines. Uncertainties on the inter-position fission rate ratios were mainly due to the uncertainties on the net-area of the gamma-ray peaks and were about 1-3% for the fresh sample, and 3-6% for the burnt one. Thus, for the first time, it has been shown that the short-lived gamma-ray activity, induced in burnt fuel by irradiation in a zero-power reactor, can be used as a quantitative measure of the fission rate. For both fresh and burnt fuel, the measured results agreed, within the uncertainties, with Monte Carlo (MCNPX) predictions.

  7. Gamma-Ray Bursts

    SciTech Connect

    Paciesas, W.S. ); Fishman, G.J. )

    1992-01-01

    This proceedings represents the works presented at the Gamma-Ray Bursts Workshop -- 1991 which was held on the campus of theUniversity of Alabama in Huntsville, October 16-18. The emphasis ofthe Workshop was to present and discuss new observations of gamma-ray bursts made recently by experiments on the Compton Gamma-RayObservatory (CGRO), Granat, Ginga, Pioneer Venus Orbiter, Prognozand Phobos. These presentations were complemented by some groundbased observations, reanalysis of older data, descriptions offuture gamma-ray burst experiments and a wide-ranging list oftheoretical discussions. Over seventy papers are included in theproceedings. Eleven of them are abstracted for the database. (AIP)

  8. Gamma-ray astrophysics

    NASA Technical Reports Server (NTRS)

    Stecker, F. W. (Editor); Trombka, J. I. (Editor)

    1973-01-01

    Conference papers on gamma ray astrophysics are summarized. Data cover the energy region from about 0.3 MeV to a few hundred GeV and theoretical models of production mechanisms that give rise to both galactic and extragalactic gamma rays.

  9. Gamma ray detector shield

    DOEpatents

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

    1985-08-26

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

  10. Gamma-Ray Pulsars

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2011-01-01

    The Fermi Gamma-Ray Space Telescope has revolutionized the study of pulsar physics with the detection of over 80 gamma-ray pulsars. Several new populations have been discovered, including 24 radio quiet pulsars found through gamma-ray pulsations alone and about 20 millisecond gamma-ray pulsars. The gamma-ray pulsations from millisecond pulsars were discovered by both folding at periods of known radio millisecond pulsars or by detecting them as gamma-ray sources that are followed up by radio pulsar searches. The second method has resulted in a phenomenally successful synergy, with -35 new radio MSPs (to date) having been discovered at Fermi unidentified source locations and the gamma-ray pulsations having then been detected in a number of these using the radio timing solutions. The higher sensitivity and larger energy range of the Fermi Large Area Telescope has produced detailed energy-dependent light curves and phase-resolved spectroscopy on brighter pulsars, that have ruled out polar cap models as the major source of the emission in favor of outer magnetosphere accelerators. The large number of gamma-ray pulsars now allows for the first time meaningful population and sub-population studies that are revealing surprising properties of these fascinating sources.

  11. Induced Mutations for Improving Production on Bread and Durum Wheat

    NASA Astrophysics Data System (ADS)

    Stamo, Ilirjana; Ylli, Ariana; Dodbiba, Andon

    2007-04-01

    Wheat is a very important crop and has been bred for food and its improvement is continuous from cross-breeding. Radiation and chemically induced mutations have provided variability in selection for novel varieties. Four bread and one durum wheat cultivars were exposed to gamma rays, Cs 137 with doses 10, 15 and 20 krad (2000 seeds of each dose and cultivars). We have isolated mutant plants with height reduced and on cv Progress spike without chaff.

  12. Induced Mutations for Improving Production on Bread and Durum Wheat

    SciTech Connect

    Stamo, Ilirjana; Ylli, Ariana; Dodbiba, Andon

    2007-04-23

    Wheat is a very important crop and has been bred for food and its improvement is continuous from cross-breeding. Radiation and chemically induced mutations have provided variability in selection for novel varieties. Four bread and one durum wheat cultivars were exposed to gamma rays, Cs 137 with doses 10, 15 and 20 krad (2000 seeds of each dose and cultivars). We have isolated mutant plants with height reduced and on cv Progress spike without chaff.

  13. Formation and conversion of defect centers in low water peak single mode optical fiber induced by gamma rays irradiation

    SciTech Connect

    Wen, J. X.; Luo, W. Y.; Xiao, Z. Y.; Wang, T. Y.; Chen, Z. Y.; Zeng, X. L.

    2010-02-15

    The formation and conversion processes of defect centers in low water peak single mode optical (LWPSM) fiber irradiated with gamma rays were investigated at room temperature using electron spin resonance. Germanium electron center (GEC) and self-trapped hole center (STH) occur when the fibers are irradiated with 1 and 5 kGy cumulative doses, respectively. With the increase in irradiation doses, the GEC defect centers disappear, and new defect centers such as E{sup '} centers (Si and Ge) and nonbridge oxygen hole centers (NBOHCs) generate. The generation of GEC and STH is attributed to the electron transfer, which is completely balanced. This is the main reason that radiation-induced attenuation (RIA) of the LWPSM fiber is only 10 dB/km at communication window. The new defect centers come from the conversion of GEC and STH to E{sup '} centers and NBOHC, and the conversion processes cause bond cleavage, which is the root cause that the RIA of the LWPSM fiber significantly increases up to 180 dB/km at working window. Furthermore, the concentration of new defect centers is saturated easily even by increasing cumulative doses.

  14. mBAND Analysis of Late Chromosome Aberrations in Human Lymphocytes Induced by Gamma Rays and Fe Ions

    NASA Technical Reports Server (NTRS)

    Sunagawa, Mayumi; Zhang, Ye; Yeshitla, Samrawit; Kadhim, Munira; Wilson, Bobby; Wu, Honglu

    2014-01-01

    Chromosomal translocations and inversions are considered stable, and cells containing these types of chromosome aberrations can survive multiple cell divisions. An efficient method to detect an inversion is multi-color banding fluorescent in situ hybridization (mBAND) which allows identification of both inter- and intrachromosome aberrations simultaneously. Post irradiation, chromosome aberrations may also arise after multiple cell divisions as a result of genomic instability. To investigate the stable or late-arising chromosome aberrations induced after radiation exposure, we exposed human lymphocytes to gamma rays and Fe ions ex vivo, and cultured the cells for multiple generations. Chromosome aberrations were analyzed in cells collected at first mitosis and at several time intervals during the culture period post irradiation. With gamma irradiation, about half of the damages observed at first mitosis remained after 7 day- and 14 day- culture, suggesting the transmissibility of damages to the surviving progeny. Detailed analysis of chromosome break ends participating in exchanges revealed a greater fraction of break ends involved in intrachromosome aberrations in the 7- and 14-day samples in comparison to the fraction at first mitosis. In particular, simple inversions were found at 7 and 14 days, but not at the first mitosis, suggesting that some of the aberrations might be formed days post irradiation. In contrast, at the doses that produced similar frequencies of gamma-induced chromosome aberrations as observed at first mitosis, a significantly lower yield of aberrations remained at the same population doublings after Fe ion exposure. At these equitoxic doses, more complex type aberrations were observed for Fe ions, indicating that Fe ion-induced initial chromosome damages are more severe and may lead to cell death. Comparison between low and high doses of Fe ion irradiation in the induction of late damages will also be discussed.

  15. Cell inactivation, mutation and DNA strand-break induction by gamma-rays at very low temperatures.

    PubMed

    Kozubek, S; Rýznar, L; Vítová, H; Mlejnek, P; Slotová, J

    1994-01-01

    Cell inactivation, mutation and DNA strand-break induction by gamma-radiation have been investigated at very low temperatures (-78 degrees C, -196 degrees C, and -268 degrees C). In Escherichia coli Ymel, lacI+-->lacI- and Salmonella typhimurium TA102, his--->his+ dose-modifying factors determined for low radiation doses are similar for both mutation induction and cell inactivation. The sensitivity of repair-deficient strains E. coli polA- and E. coli recA- was also reduced at low temperature to a comparable extent. This suggests that the lesions which are responsible for cell inactivation and mutagenesis could be strongly mutually related and/or that different types of lesions which are responsible for cell inactivation and mutation induction in bacteria are reduced at low temperature to the same or similar extent. Likewise, a lower yield of DNA strand breaks in plasmids irradiated at low temperature was observed. PMID:7708903

  16. Sucrose delays membrane deterioration of chrysanthemum flowers induced by gamma-rays

    NASA Astrophysics Data System (ADS)

    Kikuchi, O. K.; Todoriki, S.; Hayashi, T.

    1998-06-01

    Fluidity of the flower membranes of cut chrysanthemums ( Dendranthema grandiflorum Kitamura) decreased soon after gamma-irradiation at 750Gy and continued to decrease during storage following irradiation. Holding chrysanthemum cut inflorescence in 2% sucrose suppressed the decrease. The results suggest that sugars reduce radiation-induced physiological deterioration of chrysanthemum flower membranes.

  17. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1991-01-01

    Miscellaneous tasks related to the development of the Bursts and Transient Source Experiment on the Gamma Ray Observatory and to analysis of archival data from balloon flight experiments were performed. The results are summarized and relevant references are included.

  18. Gamma ray line astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.

    1984-01-01

    The interpretations and implications of the astrophysical observations of gamma-ray lines are reviewed. At the Galactic Center e(+)-e(-) pairs from a compact object produce an annihilation line that shows no redshift, indicating an annihilation site far removed from this object. In the jets of SS433, gamma-ray lines are produced by inelastic excitations, probably in dust grains, although line emission from fusion reactions has also been considered. Observations of diffuse galactic line emission reveal recently synthesized radioactive aluminum in the interstellar medium. In gamma-ray bursts, redshifted pair annihilation lines are consistent with a neutron star origin for the bursts. In solar flares, gamma-ray line emission reveals the prompt acceleration of protons and nuclei, in close association with the flare energy release mechanism.

  19. Gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1982-01-01

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

  20. Gamma Ray Pulsars: Observations

    NASA Technical Reports Server (NTRS)

    Thompson, David J.; White, Nicholas E. (Technical Monitor)

    2000-01-01

    High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The six or more pulsars seen by CGRO/EGRET show that: the light curves usually have double-peak structures (suggesting a broad cone of emission); gamma rays are frequently the dominant component of the radiated power; and all the spectra show evidence of a high-energy turnover. Unless a new pulsed component appears at higher energies, progress in gamma-ray pulsar studies will be greatest in the 1-20 GeV range. Ground-based telescopes whose energy ranges extend downward toward 10 GeV should make important measurements of the spectral cutoffs. The Gamma-ray Large Area Space Telescope (GLAST), now in planning for a launch in 2005, will provide a major advance in sensitivity, energy range, and sky coverage.

  1. Estrogens decrease {gamma}-ray-induced senescence and maintain cell cycle progression in breast cancer cells independently of p53

    SciTech Connect

    Toillon, Robert-Alain . E-mail: robert.toillon@univ-lille1.fr; Magne, Nicolas; Laios, Ioanna; Castadot, Pierre; Kinnaert, Eric; Van Houtte, Paul; Desmedt, Christine B.Sc.; Leclercq, Guy; Lacroix, Marc

    2007-03-15

    Purpose: Sequential administration of radiotherapy and endocrine therapy is considered to be a standard adjuvant treatment of breast cancer. Recent clinical reports suggest that radiotherapy could be more efficient in association with endocrine therapy. The aim of this study was to evaluate the estrogen effects on irradiated breast cancer cells (IR-cells). Methods and Materials: Using functional genomic analysis, we examined the effects of 17-{beta}-estradiol (E{sub 2}, a natural estrogen) on MCF-7 breast cancer cells. Results: Our results showed that E{sub 2} sustained the growth of IR-cells. Specifically, estrogens prevented cell cycle blockade induced by {gamma}-rays, and no modification of apoptotic rate was detected. In IR-cells we observed the induction of genes involved in premature senescence and cell cycle progression and investigated the effects of E{sub 2} on the p53/p21{sup waf1/cip1}/Rb pathways. We found that E{sub 2} did not affect p53 activation but it decreased cyclin E binding to p21{sup waf1/cip1} and sustained downstream Rb hyperphosphorylation by functional inactivation of p21{sup waf1/cip1}. We suggest that Rb inactivation could decrease senescence and allow cell cycle progression in IR-cells. Conclusion: These results may help to elucidate the molecular mechanism underlying the maintenance of breast cancer cell growth by E{sub 2} after irradiation-induced damage. They also offer clinicians a rational basis for the sequential administration of ionizing radiation and endocrine therapies.

  2. Nuclear gamma rays from 720-MeV alpha-induced reactions on Al-27 and Si-28

    NASA Technical Reports Server (NTRS)

    Lieb, B. J.; Plendl, H. S.; Funsten, H. O.; Stronach, C. E.; Lind, V. G.

    1980-01-01

    Prompt gamma rays from the interaction of 720-MeV alpha particles with Al-27 and Si-28 were detected and analyzed to identify residual nuclei and to determine cross sections for production of specific levels. No gamma-ray transitions were detected from nuclei heavier than the target. From Doppler broadening, the momentum of the residual nuclei was estimated. The results are compared with previous results for 140- and 1600-MeV alphas on Al-27 and approximately 200-MeV positive or negative pions on Al-27 and Si-28 and fitted to a spallation-yield formula.

  3. Gamma Ray Transients

    NASA Astrophysics Data System (ADS)

    Gehrels, N.

    Almost every source in the gamma-ray sky is variable. Transient classification therefore depends on the definition of ``transient'' and on instrument sensitivity thresholds. The sources that most clearly fall in the transient category are those that have large intensity differences between their low (or off) states and their high states and have well defined high states with durations less than about a year. Examples are gamma-ray bursts, solar flares, X-ray novae, jet transients, bursting pulsars and Be binary pulsars. Generally, most accreting neutron stars, galactic black holes and AGN are variable with periods of high intensity that can be labeled as transient outbursts. Supernovae and novae form another class of gamma-ray transient driven by explosive nucleosynthesis. The Compton Gamma Ray Observatory (CGRO) has been observing the gamma-ray sky for 6 years. Many of the scientific discoveries from the mission have related to transient observations. The BATSE instrument onboard is a powerful all-sky monitor with 50 m Crab detection sensitivity above 20 keV. The OSSE instrument has a narrow field-of-view with limited sky coverage, but has excellent sensitivities above 50 keV for specific objects. At higher MeV and GeV energies the COMPTEL and EGRET instruments have wide fields-of-view that give reasonable coverage of the sky. In this talk I will review the different classes of gamma-ray transient and present results from CGRO observations.

  4. Gamma ray optics

    SciTech Connect

    Jentschel, M.; Guenther, M. M.; Habs, D.; Thirolf, P. G.

    2012-07-09

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

  5. Prospects for gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The Solar Maximum Mission and the Gamma Ray Experiment aboard the SMM spacecraft are discussed. Mission plans for interplanetary probes are also discussed. The Gamma Ray observatory and its role in future gamma ray astronomy is highlighted. It is concluded that gamma ray astronomy will be of major importance in the development of astronomical models and in the development of comsological theory.

  6. The gamma-ray observatory

    NASA Technical Reports Server (NTRS)

    1991-01-01

    An overview is given of the Gamma Ray Observatory (GRO) mission. Detection of gamma rays and gamma ray sources, operations using the Space Shuttle, and instruments aboard the GRO, including the Burst and Transient Source Experiment (BATSE), the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), and the Energetic Gamma Ray Experiment Telescope (EGRET) are among the topics surveyed.

  7. Time-Dependence of VHE Gamma-Ray induced Pair Cascades in Radio Galaxies

    NASA Astrophysics Data System (ADS)

    Roustazadeh, Parisa; Boettcher, Markus; Thrush, Samantha

    2016-04-01

    Recently, several intermediate frequency peaked BL Lac objects (IBL), low frequency peaked BL Lac objects (LBL) and flat spectrum radio quasars (FSRQ) were detected as very high energy ( VHE, E > 100 ˜ GeV) γ-ray sources. These discoveries suggest that γγ absorption and pair cascades might occur in those objects, leading to excess γ-ray emission which may be observable also in off-axis viewing directions (i.e., like in radio galaxies) when deflected by moderately strong magnetic fields. Here, we investigate the time dependence of the Compton γ-ray emission from such VHE γ-ray induced pair cascades. We show that the cascade emission is variable on time scales much shorter than the light-crossing time across the characteristic extent of the external radiation field, depending on the viewing angle and γ-ray energy. Thus, we find that the cascade Compton interpretation for the Fermi γ-ray emission from radio galaxies is still consistent with the day-scale variability detected in the Fermi γ-ray emission of radio galaxies, such as NGC 1275, which we use as a specific example.

  8. Simultaneous determination of Si, Al and Na concentrations by particle induced gamma-ray emission and applications to reference materials and ceramic archaeological artifacts

    NASA Astrophysics Data System (ADS)

    Dasari, K. B.; Chhillar, S.; Acharya, R.; Ray, D. K.; Behera, A.; Lakshmana Das, N.; Pujari, P. K.

    2014-11-01

    A particle induced gamma ray emission (PIGE) method using 4 MeV proton beam was standardized for simultaneous determination of Si, Al and Na concentrations and has been applied for non-destructive analysis of several reference materials and archaeological clay pottery samples. Current normalized count rates of gamma-rays for the three elements listed above were obtained by an in situ method using Li as internal standard. The paper presents application of the in situ current normalized PIGE method for grouping study of 39 clay potteries, obtained from Rajasthan and Andhra Pradesh states of India. Grouping of artifacts was carried out using the ratios of SiO2 to Al2O3 concentrations, due to their non volatile nature. Powder samples and elemental standards in pellet forms (cellulose matrix) were irradiated using the 4 MeV proton beam (∼10 nA) from the 3 MV tandem accelerator at IOP Bhubaneswar, and assay of prompt gamma rays was carried out using a 60% relative efficiency HPGe detector coupled to MCA. The concentration ratio values of SiO2/Al2O3 indicated that pottery samples fell into two major groups, which are in good agreement with their collection areas. Reference materials from IAEA and NIST were analyzed for quantification of Si, Al and Na concentrations as a part of validation as well as application of PIGE method.

  9. Gamma ray camera

    DOEpatents

    Perez-Mendez, V.

    1997-01-21

    A gamma ray camera is disclosed for detecting rays emanating from a radiation source such as an isotope. The gamma ray camera includes a sensor array formed of a visible light crystal for converting incident gamma rays to a plurality of corresponding visible light photons, and a photosensor array responsive to the visible light photons in order to form an electronic image of the radiation therefrom. The photosensor array is adapted to record an integrated amount of charge proportional to the incident gamma rays closest to it, and includes a transparent metallic layer, photodiode consisting of a p-i-n structure formed on one side of the transparent metallic layer, and comprising an upper p-type layer, an intermediate layer and a lower n-type layer. In the preferred mode, the scintillator crystal is composed essentially of a cesium iodide (CsI) crystal preferably doped with a predetermined amount impurity, and the p-type upper intermediate layers and said n-type layer are essentially composed of hydrogenated amorphous silicon (a-Si:H). The gamma ray camera further includes a collimator interposed between the radiation source and the sensor array, and a readout circuit formed on one side of the photosensor array. 6 figs.

  10. Gamma ray camera

    DOEpatents

    Perez-Mendez, Victor

    1997-01-01

    A gamma ray camera for detecting rays emanating from a radiation source such as an isotope. The gamma ray camera includes a sensor array formed of a visible light crystal for converting incident gamma rays to a plurality of corresponding visible light photons, and a photosensor array responsive to the visible light photons in order to form an electronic image of the radiation therefrom. The photosensor array is adapted to record an integrated amount of charge proportional to the incident gamma rays closest to it, and includes a transparent metallic layer, photodiode consisting of a p-i-n structure formed on one side of the transparent metallic layer, and comprising an upper p-type layer, an intermediate layer and a lower n-type layer. In the preferred mode, the scintillator crystal is composed essentially of a cesium iodide (CsI) crystal preferably doped with a predetermined amount impurity, and the p-type upper intermediate layers and said n-type layer are essentially composed of hydrogenated amorphous silicon (a-Si:H). The gamma ray camera further includes a collimator interposed between the radiation source and the sensor array, and a readout circuit formed on one side of the photosensor array.

  11. Gamma-ray Output Spectra from 239Pu Fission

    NASA Astrophysics Data System (ADS)

    Ullmann, John

    2015-05-01

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

  12. Hypernuclear gamma rays

    SciTech Connect

    May, M.

    1985-01-01

    The observation of hypernuclear ..gamma.. rays pprovides a method of determining the spin dependence of the ..lambda..-nucleon interaction with a sensitivity not approachable by other means in the forseeable future. The transitions of primary interest are those between states that differ only in the orientation of the spin of the ..lambda.. particle with respect to the angular momentum of the nuclear core. The effective ..lambda..-nucleon interaction can be specified by a small number of ..gamma..-ray measurements. A program of experiments directed at this goal is in progress at Brookhaven National Laboratory. This paper reviews the status of the subject with emphasis on the recent experiment to measure ground state doublet splittings using germanium ..gamma..-ray detectors.

  13. Gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Liang, E. P.; Petrosian, V.

    The physics of gamma bursts and neutron stars is examined in chapters based on papers presented at an AIP Workshop held at Stanford University on July 30-August 3, 1984. Astronomical observations and statistics concerned with the temporal structure of gamma-ray bursts, the log N-log S relation, error boxes and spatial distribution, deep searches for bursters, optical flashes, and burster recurrence time scales are discussed. Emphasis is given to accretion models, the thermonuclear model, winds in gamma-ray bursts, the magnetic flare model, and the starquake model.

  14. Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Gehrels, Neil; Mészáros, Péter

    2012-08-01

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

  15. Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    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.

  16. Variation in sensitivity to. gamma. -ray-induced chromosomal aberrations during the mitotic cycle of the sea urchin egg

    SciTech Connect

    Ejima, Y.; Nakamura, I.; Shiroya, T.

    1982-11-01

    Sea urchin eggs were irradiated with /sup 137/Cs ..gamma.. rays at various stages of the mitotic cycle, and chromosomal aberrations at the first postirradiation mitosis and embryonic abnormalities at later developmental stages were examined. The radiosensitivity of the eggs to both endpoints varied in parallel with the mitotic stage at the time of irradiation, suggesting a possible relationship between chromosomal damage and embryonic abnormalities.

  17. Measurement of Cerenkov Radiation Induced by the Gamma-Rays of Co-60 Therapy Units Using Wavelength Shifting Fiber

    PubMed Central

    Jang, Kyoung Won; Shin, Sang Hun; Kim, Seon Geun; Kim, Jae Seok; Yoo, Wook Jae; Ji, Young Hoon; Lee, Bongsoo

    2014-01-01

    In this study, a wavelength shifting fiber that shifts ultra-violet and blue light to green light was employed as a sensor probe of a fiber-optic Cerenkov radiation sensor. In order to characterize Cerenkov radiation generated in the developed wavelength shifting fiber and a plastic optical fiber, spectra and intensities of Cerenkov radiation were measured with a spectrometer. The spectral peaks of light outputs from the wavelength shifting fiber and the plastic optical fiber were measured at wavelengths of 500 and 510 nm, respectively, and the intensity of transmitted light output of the wavelength shifting fiber was 22.2 times higher than that of the plastic optical fiber. Also, electron fluxes and total energy depositions of gamma-ray beams generated from a Co-60 therapy unit were calculated according to water depths using the Monte Carlo N-particle transport code. The relationship between the fluxes of electrons over the Cerenkov threshold energy and the energy depositions of gamma-ray beams from the Co-60 unit is a near-identity function. Finally, percentage depth doses for the gamma-ray beams were obtained using the fiber-optic Cerenkov radiation sensor, and the results were compared with those obtained by an ionization chamber. The average dose difference between the results of the fiber-optic Cerenkov radiation sensor and those of the ionization chamber was about 2.09%. PMID:24755521

  18. VERY HIGH ENERGY GAMMA-RAY-INDUCED PAIR CASCADES IN BLAZARS AND RADIO GALAXIES: APPLICATION TO NGC 1275

    SciTech Connect

    Roustazadeh, P.; Boettcher, M.

    2010-07-01

    Recent blazar detections by HESS, MAGIC, and VERITAS suggest that very high energy (VHE; E > 100 GeV) {gamma}-rays may be produced in most, if not all, types of blazars, including those that possess intense circumnuclear radiation fields. In this paper, we investigate the interaction of nuclear VHE {gamma}-rays with the circumnuclear radiation fields through {gamma}{gamma} absorption and pair production, and the subsequent Compton-supported pair cascades. We have developed a Monte Carlo code to follow the spatial development of the cascade in full three-dimensional geometry and calculate the radiative output due to the cascade as a function of viewing angle with respect to the primary VHE {gamma}-ray beam (presumably the jet axis of the blazar). We show that even for relatively weak magnetic fields, the cascades can be efficiently isotropized, leading to substantial off-axis cascade emission peaking in the Fermi energy range at detectable levels for nearby radio galaxies. We demonstrate that this scenario can explain the Fermi flux and spectrum of the radio galaxy NGC 1275.

  19. Measurement of Cerenkov radiation induced by the gamma-rays of Co-60 therapy units using wavelength shifting fiber.

    PubMed

    Jang, Kyoung Won; Shin, Sang Hun; Kim, Seon Geun; Kim, Jae Seok; Yoo, Wook Jae; Ji, Young Hoon; Lee, Bongsoo

    2014-01-01

    In this study, a wavelength shifting fiber that shifts ultra-violet and blue light to green light was employed as a sensor probe of a fiber-optic Cerenkov radiation sensor. In order to characterize Cerenkov radiation generated in the developed wavelength shifting fiber and a plastic optical fiber, spectra and intensities of Cerenkov radiation were measured with a spectrometer. The spectral peaks of light outputs from the wavelength shifting fiber and the plastic optical fiber were measured at wavelengths of 500 and 510 nm, respectively, and the intensity of transmitted light output of the wavelength shifting fiber was 22.2 times higher than that of the plastic optical fiber. Also, electron fluxes and total energy depositions of gamma-ray beams generated from a Co-60 therapy unit were calculated according to water depths using the Monte Carlo N-particle transport code. The relationship between the fluxes of electrons over the Cerenkov threshold energy and the energy depositions of gamma-ray beams from the Co-60 unit is a near-identity function. Finally, percentage depth doses for the gamma-ray beams were obtained using the fiber-optic Cerenkov radiation sensor, and the results were compared with those obtained by an ionization chamber. The average dose difference between the results of the fiber-optic Cerenkov radiation sensor and those of the ionization chamber was about 2.09%. PMID:24755521

  20. Gamma Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    2000-01-01

    The project has progressed successfully during this period of performance. The highlights of the Gamma Ray Astronomy teams efforts are: (1) Support daily BATSE data operations, including receipt, archival and dissemination of data, quick-look science analysis, rapid gamma-ray burst and transient monitoring and response efforts, instrument state-of-health monitoring, and instrument commanding and configuration; (2) On-going scientific analysis, including production and maintenance of gamma-ray burst, pulsed source and occultation source catalogs, gamma-ray burst spectroscopy, studies of the properties of pulsars and black holes, and long-term monitoring of hard x-ray sources; (3) Maintenance and continuous improvement of BATSE instrument response and calibration data bases; (4) Investigation of the use of solid state detectors for eventual application and instrument to perform all sky monitoring of X-Ray and Gamma sources with high sensitivity; and (5) Support of BATSE outreach activities, including seminars, colloquia and World Wide Web pages. The highlights of this efforts can be summarized in the publications and presentation list.

  1. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1991-01-01

    Miscellaneous tasks related to the development of the Burst and Transient Source Experiment on the Gamma Ray Observatory and to collection, analysis, and interpretation of data from the MSFC Very Low Frequency transient monitoring program were performed. The results are summarized and relevant references are included.

  2. Celestial gamma ray study

    NASA Technical Reports Server (NTRS)

    Michelson, Peter F.

    1995-01-01

    This report documents the research activities performed by Stanford University investigators as part of the data reduction effort and overall support of the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Observatory. This report is arranged chronologically, with each subsection detailing activities during roughly a one year period of time, beginning in June 1991.

  3. Gamma ray astronomy in perspective

    NASA Technical Reports Server (NTRS)

    1981-01-01

    A brief overview of the development of gamma ray astronomy is presented. Gamma ray telescopes and other optical measuring instruments are highlighted. Emphasis is placed on findings that were unobtainable before gamma ray astronomy. Information on evolution of the solar system, the relationship of the solar system to the galaxy, and the composition of interstellar matter is discussed.

  4. Determination of Fluorine in Fourteen Microanalytical Geologic Reference Materials using SIMS, EPMA, and Proton Induced Gamma Ray Emission (PIGE) Analysis

    NASA Astrophysics Data System (ADS)

    Guggino, S. N.; Hervig, R. L.

    2010-12-01

    Fluorine (F) is a volatile constituent of magmas and hydrous minerals, and trace amounts of F are incorporated into nominally anhydrous minerals such as olivine and clinopyroxene. Microanalytical techniques are routinely used to measure trace amounts of F at both high sensitivity and high spatial resolution in glasses and crystals. However, there are few well-established F concentrations for the glass standards routinely used in microanalytical laboratories, particularly standards of low silica, basaltic composition. In this study, we determined the F content of fourteen commonly used microanalytical glass standards of basaltic, intermediate, and rhyolitic composition. To serve as calibration standards, five basaltic glasses with ~0.2 to 2.5 wt% F were synthesized and characterized. A natural tholeiite from the East Pacific Rise was mixed with variable amounts of CaF2. The mixture was heated in a 1 atmosphere furnace to 1440 °C at fO2 = NNO for 30 minutes and quenched in water. Portions of the run products were studied by electron probe microanalysis (EPMA) and secondary ion mass spectrometry (SIMS). The EPMA used a 15 µm diameter defocused electron beam with a 15 kV accelerating voltage and a 25 nA primary current, a TAP crystal for detecting FKα X-rays, and Biotite 3 as the F standard. The F contents by EPMA agreed with the F added to the basalts after correction for mass loss during melting. The SIMS analyses used a primary beam of 16O- and detection of low-energy negative ions (-5 kV) at a mass resolution that resolved 18OH. Both microanalytical techniques confirmed homogeneity, and the SIMS calibration defined by EPMA shows an excellent linear trend with backgrounds of 2 ppm or less. Analyses of basaltic glass standards based on our synthesized calibration standards gave the following F contents and 2σ errors (ppm): ALV-519 = 83 ± 3; BCR-2G = 359 ± 6; BHVO-2G = 322 ± 15; GSA-1G = 10 ± 1; GSC-1G = 11 ± 1; GSD-1G = 19 ± 2; GSE-1G = 173 ± 1; KL2G (MPI-DING) = 101 ± 1; ML3B-G (MPI-DING) = 49 ± 17. These values are lower than published values for BCR-2 and BHVO-2 (unmelted powders) and the “information values” for the MPI-DING glass standards. Proton Induced Gamma ray Emission (PIGE) was tested for the high silica samples. PIGE analyses (1.7 MeV Tandem Accelerator; reaction type: 19F(p, αγ)16O; primary current = 20-30 nA; incident beam voltage = 1.5 MeV) were calibrated with a crystal of fluor-topaz (F = 20.3 wt%) and gave F values of: NIST 610 = 266 ± 14 ppm; NIST 620 = 54 ± 5 ppm; and UTR-2 = 1432 ± 32 ppm. SIMS calibration defined by the PIGE analyses shows an excellent linear trend with low background similar to the basaltic calibration. The F concentrations of intermediate MPI-DING glasses were determined based on SIMS calibration generated from the PIGE analysis above. The F concentrations and 2σ errors (ppm) are: T1G = 219.9 ± 6.8; StHs/680-G = 278.0 ± 2.0 ppm. This study revealed a large matrix effect between the high-silica and basaltic glasses, thus requiring the use of appropriate standards and separate SIMS calibrations when analyzing samples of different compositions.

  5. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1994-01-01

    The Burst and Transient Source Experiment (BATSE) is one of four instruments on the Compton observatory which was launched by the space shuttle Atlantis on April 5, 1991. As of mid-March, 1994, BATSE detected more than 925 cosmic gamma-ray bursts and more than 725 solar flares. Pulsed gamma rays have been detected from at least 16 sources and emission from at least 28 sources (including most of the pulsed sources) has been detected by the earth occultation technique. UAH participation in BATSE is extensive but can be divided into two main areas, operations and data analysis. The daily BATSE operations tasks represent a substantial level of effort and involve a large team composed of MSFC personnel as well as contractors such as UAH. The scientific data reduction and analysis of BATSE data is also a substantial level of effort in which UAH personnel have made significant contributions.

  6. Topics in gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1986-01-01

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

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

    SciTech Connect

    Pavlik, A.; Vonach, H.; Hitzenberger, H.; Nelson, R.O.; Haight, R.C.; Wender, S.A.; Young, P.G.; Chadwick, M.B.

    1995-02-01

    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 {sup 207}Pb and {sup 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,xn{gamma}) reactions were studied for neutron energies up to 200 MeV by analyzing prominent gamma-transitions in the residual nuclei {sup 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.

  8. Gamma ray collimator

    NASA Technical Reports Server (NTRS)

    Casanova, Edgar J. (Inventor)

    1991-01-01

    A gamma ray collimator including a housing having first and second sections is disclosed. The first section encloses a first section of depleted uranium which is disposed for receiving and supporting a radiation emitting component such as cobalt 60. The second section encloses a depleted uranium member which is provided with a conical cut out focusing portion disposed in communication with the radiation emitting element for focusing the emitted radiation to the target.

  9. Gamma ray collimator

    NASA Technical Reports Server (NTRS)

    Casanova, Edgar J. (Inventor)

    1993-01-01

    A gamma ray collimator including a housing having first and second sections. The first section encloses a first section of depleted uranium which is disposed for receiving and supporting a radiation emitting component such as cobalt 60. The second section encloses a depleted uranium member which is provided with a conical cut-out focusing portion disposed in communication with the radiation emitting element for focusing the emitted radiation to the target.

  10. Induced mutations in rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Induced mutations have a long history in both applied and basic aspects of rice research. During the past fifty years, over 500 rice varieties have been developed worldwide, either directly from induced mutants or as a result of crossing such mutants with other breeding lines. More recently, the gen...

  11. Radiation-induced oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder by gamma rays and electron beams: A clear dependence of dose rate

    NASA Astrophysics Data System (ADS)

    Wang, Honglong; Xu, Lu; Hu, Jiangtao; Wang, Mouhua; Wu, Guozhong

    2015-10-01

    Oxidation is an important effect of irradiation on polyethylene in air. In this work, oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder (ca. 110 μm in diameter) induced by gamma rays (γ ray) and electron beams (EB) in air resulted in some large differences in properties, such as oxidative scission due to dose rate differences. However, other properties, such as surface wettability and thermal stability were not that greatly affected. The dose-rates used were 0.0019 kGy/s from a cobalt-60 gamma source and 92 kGy/s from an electron beam. The chemical structure, oxidation level, surface wettability and thermal stability of irradiated UHMWPE were analyzed by FT-IR, XPS, TGA and the static contact angle. Hydrophilic carboxyl and carbonyl groups were present on the surface of irradiated UHMWPE after irradiation in air, resulting in a decrease in the contact angle. After irradiation at 300 kGy, the gel content of the γ ray-irradiated UHMWPE samples decreased to almost zero, while that of EB irradiated UHMWPE decreased to 57%. For UHMWPE powder irradiated by gamma rays at lower doses, radiation-induced oxidation was complete and consistent with a simple theoretic estimation. Surface wettability was primarily affected by surface oxidation, and the oxidation level of UHMWPE could be easily predicted.

  12. Molecular characterisation of murine acute myeloid leukaemia induced by 56Fe ion and 137Cs gamma ray irradiation.

    PubMed

    Steffen, Leta S; Bacher, Jeffery W; Peng, Yuanlin; Le, Phuong N; Ding, Liang-Hao; Genik, Paula C; Ray, F Andrew; Bedford, Joel S; Fallgren, Christina M; Bailey, Susan M; Ullrich, Robert L; Weil, Michael M; Story, Michael D

    2013-01-01

    Exposure to sparsely ionising gamma- or X-ray irradiation is known to increase the risk of leukaemia in humans. However, heavy ion radiotherapy and extended space exploration will expose humans to densely ionising high linear energy transfer (LET) radiation for which there is currently no understanding of leukaemia risk. Murine models have implicated chromosomal deletion that includes the hematopoietic transcription factor gene, PU.1 (Sfpi1), and point mutation of the second PU.1 allele as the primary cause of low-LET radiation-induced murine acute myeloid leukaemia (rAML). Using array comparative genomic hybridisation, fluorescence in situ hybridisation and high resolution melt analysis, we have confirmed that biallelic PU.1 mutations are common in low-LET rAML, occurring in 88% of samples. Biallelic PU.1 mutations were also detected in the majority of high-LET rAML samples. Microsatellite instability was identified in 42% of all rAML samples, and 89% of samples carried increased microsatellite mutant frequencies at the single-cell level, indicative of ongoing instability. Instability was also observed cytogenetically as a 2-fold increase in chromatid-type aberrations. These data highlight the similarities in molecular characteristics of high-LET and low-LET rAML and confirm the presence of ongoing chromosomal and microsatellite instability in murine rAML. PMID:22987027

  13. Molecular characterisation of murine acute myeloid leukaemia induced by 56Fe ion and 137Cs gamma ray irradiation

    PubMed Central

    Bacher, Jeffery W.

    2013-01-01

    Exposure to sparsely ionising gamma- or X-ray irradiation is known to increase the risk of leukaemia in humans. However, heavy ion radiotherapy and extended space exploration will expose humans to densely ionising high linear energy transfer (LET) radiation for which there is currently no understanding of leukaemia risk. Murine models have implicated chromosomal deletion that includes the hematopoietic transcription factor gene, PU.1 (Sfpi1), and point mutation of the second PU.1 allele as the primary cause of low-LET radiation-induced murine acute myeloid leukaemia (rAML). Using array comparative genomic hybridisation, fluorescence in situ hybridisation and high resolution melt analysis, we have confirmed that biallelic PU.1 mutations are common in low-LET rAML, occurring in 88% of samples. Biallelic PU.1 mutations were also detected in the majority of high-LET rAML samples. Microsatellite instability was identified in 42% of all rAML samples, and 89% of samples carried increased microsatellite mutant frequencies at the single-cell level, indicative of ongoing instability. Instability was also observed cytogenetically as a 2-fold increase in chromatid-type aberrations. These data highlight the similarities in molecular characteristics of high-LET and low-LET rAML and confirm the presence of ongoing chromosomal and microsatellite instability in murine rAML. PMID:22987027

  14. Gamma-ray Output Spectra from 239 Pu Fission

    DOE PAGESBeta

    Ullmann, John

    2015-05-25

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

  15. Unidentified Gamma-Ray Sources: Hunting Gamma-Ray Blazars

    SciTech Connect

    Massaro, F.; D'Abrusco, R.; Tosti, G.; Ajello, M.; Gasparrini, A.Paggi.D.

    2012-04-02

    One of the main scientific objectives of the ongoing Fermi mission is unveiling the nature of the unidentified {gamma}-ray sources (UGSs). Despite the large improvements of Fermi in the localization of {gamma}-ray sources with respect to the past {gamma}-ray missions, about one third of the Fermi-detected objects are still not associated to low energy counterparts. Recently, using the Wide-field Infrared Survey Explorer (WISE) survey, we discovered that blazars, the rarest class of Active Galactic Nuclei and the largest population of {gamma}-ray sources, can be recognized and separated from other extragalactic sources on the basis of their infrared (IR) colors. Based on this result, we designed an association method for the {gamma}-ray sources to recognize if there is a blazar candidate within the positional uncertainty region of a generic {gamma}-ray source. With this new IR diagnostic tool, we searched for {gamma}-ray blazar candidates associated to the UGS sample of the second Fermi {gamma}-ray catalog (2FGL). We found that our method associates at least one {gamma}-ray blazar candidate as a counterpart each of 156 out of 313 UGSs analyzed. These new low-energy candidates have the same IR properties as the blazars associated to {gamma}-ray sources in the 2FGL catalog.

  16. UNIDENTIFIED {gamma}-RAY SOURCES: HUNTING {gamma}-RAY BLAZARS

    SciTech Connect

    Massaro, F.; Ajello, M.; D'Abrusco, R.; Paggi, A.; Tosti, G.; Gasparrini, D.

    2012-06-10

    One of the main scientific objectives of the ongoing Fermi mission is unveiling the nature of unidentified {gamma}-ray sources (UGSs). Despite the major improvements of Fermi in the localization of {gamma}-ray sources with respect to the past {gamma}-ray missions, about one-third of the Fermi-detected objects are still not associated with low-energy counterparts. Recently, using the Wide-field Infrared Survey Explorer survey, we discovered that blazars, the rarest class of active galactic nuclei and the largest population of {gamma}-ray sources, can be recognized and separated from other extragalactic sources on the basis of their infrared (IR) colors. Based on this result, we designed an association method for the {gamma}-ray sources to recognize if there is a blazar candidate within the positional uncertainty region of a generic {gamma}-ray source. With this new IR diagnostic tool, we searched for {gamma}-ray blazar candidates associated with the UGS sample of the second Fermi {gamma}-ray LAT catalog (2FGL). We found that our method associates at least one {gamma}-ray blazar candidate as a counterpart to each of 156 out of 313 UGSs analyzed. These new low-energy candidates have the same IR properties as the blazars associated with {gamma}-ray sources in the 2FGL catalog.

  17. Effects of indirect actions and oxygen on relative biological effectiveness: estimate of DSB induction and conversion induced by gamma rays and helium ions

    PubMed Central

    Tsai, Ju-Ying; Chen, Fang-Hsin; Hsieh, Tsung-Yu; Hsiao, Ya-Yun

    2015-01-01

    Clustered DNA damage other than double-strand breaks (DSBs) can be detrimental to cells and can lead to mutagenesis or cell death. In addition to DSBs induced by ionizing radiation, misrepair of non-DSB clustered damage contributes extra DSBs converted from DNA misrepair via pathways for base excision repair and nucleotide excision repair. This study aimed to quantify the relative biological effectiveness (RBE) when DSB induction and conversion from non-DSB clustered damage misrepair were used as biological endpoints. The results showed that both linear energy transfer (LET) and indirect action had a strong impact on the yields for DSB induction and conversion. RBE values for DSB induction and maximum DSB conversion of helium ions (LET = 120 keV/μm) to 60Co gamma rays were 3.0 and 3.2, respectively. These RBE values increased to 5.8 and 5.6 in the absence of interference of indirect action initiated by addition of 2-M dimethylsulfoxide. DSB conversion was ∼1–4% of the total non-DSB damage due to gamma rays, which was lower than the 10% estimate by experimental measurement. Five to twenty percent of total non-DSB damage due to helium ions was converted into DSBs. Hence, it may be possible to increase the yields of DSBs in cancerous cells through DNA repair pathways, ultimately enhancing cell killing. PMID:25902742

  18. Effects of indirect actions and oxygen on relative biological effectiveness: estimate of DSB induction and conversion induced by gamma rays and helium ions.

    PubMed

    Tsai, Ju-Ying; Chen, Fang-Hsin; Hsieh, Tsung-Yu; Hsiao, Ya-Yun

    2015-07-01

    Clustered DNA damage other than double-strand breaks (DSBs) can be detrimental to cells and can lead to mutagenesis or cell death. In addition to DSBs induced by ionizing radiation, misrepair of non-DSB clustered damage contributes extra DSBs converted from DNA misrepair via pathways for base excision repair and nucleotide excision repair. This study aimed to quantify the relative biological effectiveness (RBE) when DSB induction and conversion from non-DSB clustered damage misrepair were used as biological endpoints. The results showed that both linear energy transfer (LET) and indirect action had a strong impact on the yields for DSB induction and conversion. RBE values for DSB induction and maximum DSB conversion of helium ions (LET = 120 keV/μm) to (60)Co gamma rays were 3.0 and 3.2, respectively. These RBE values increased to 5.8 and 5.6 in the absence of interference of indirect action initiated by addition of 2-M dimethylsulfoxide. DSB conversion was ∼1-4% of the total non-DSB damage due to gamma rays, which was lower than the 10% estimate by experimental measurement. Five to twenty percent of total non-DSB damage due to helium ions was converted into DSBs. Hence, it may be possible to increase the yields of DSBs in cancerous cells through DNA repair pathways, ultimately enhancing cell killing. PMID:25902742

  19. Development of particle induced gamma-ray emission methods for nondestructive determination of isotopic composition of boron and its total concentration in natural and enriched samples.

    PubMed

    Chhillar, Sumit; Acharya, Raghunath; Sodaye, Suparna; Pujari, Pradeep K

    2014-11-18

    We report simple particle induced gamma-ray emission (PIGE) methods using a 4 MeV proton beam for simultaneous and nondestructive determination of the isotopic composition of boron ((10)B/(11)B atom ratio) and total boron concentrations in various solid samples with natural isotopic composition and enriched with (10)B. It involves measurement of prompt gamma-rays at 429, 718, and 2125 keV from (10)B(p,αγ)(7)Be, (10)B(p, p'γ)(10)B, and (11)B(p, p'γ)(11)B reactions, respectively. The isotopic composition of boron in natural and enriched samples was determined by comparing peak area ratios corresponding to (10)B and (11)B of samples to natural boric acid standard. An in situ current normalized PIGE method, using F or Al, was standardized for total B concentration determination. The methods were validated by analyzing stoichiometric boron compounds and applied to samples such as boron carbide, boric acid, carborane, and borosilicate glass. Isotopic compositions of boron in the range of 0.247-2.0 corresponding to (10)B in the range of 19.8-67.0 atom % and total B concentrations in the range of 5-78 wt % were determined. It has been demonstrated that PIGE offers a simple and alternate method for total boron as well as isotopic composition determination in boron based solid samples, including neutron absorbers that are important in nuclear technology. PMID:25312472

  20. Gamma-Ray Localization of Terrestrial Gamma-Ray Flashes

    SciTech Connect

    Marisaldi, M.; Labanti, C.; Fuschino, F.; Bulgarelli, A.; Trifoglio, M.; Di Cocco, G.; Gianotti, F.; Argan, A.; De Paris, G.; Trois, A.; Del Monte, E.; Costa, E.; Di Persio, G.; Donnarumma, I.; Evangelista, Y.; Feroci, M.; Lazzarotto, F.; Pacciani, L.; Rubini, A.; Sabatini, S.

    2010-09-17

    Terrestrial gamma-ray flashes (TGFs) are very short bursts of high-energy photons and electrons originating in Earth's atmosphere. We present here a localization study of TGFs carried out at gamma-ray energies above 20 MeV based on an innovative event selection method. We use the AGILE satellite Silicon Tracker data that for the first time have been correlated with TGFs detected by the AGILE Mini-Calorimeter. We detect 8 TGFs with gamma-ray photons of energies above 20 MeV localized by the AGILE gamma-ray imager with an accuracy of {approx}5-10 deg. at 50 MeV. Remarkably, all TGF-associated gamma rays are compatible with a terrestrial production site closer to the subsatellite point than 400 km. Considering that our gamma rays reach the AGILE satellite at 540 km altitude with limited scattering or attenuation, our measurements provide the first precise direct localization of TGFs from space.

  1. SYNTH - Gamma Ray Spectrum Synthesizer

    Energy Science and Technology Software Center (ESTSC)

    2009-05-18

    SYNTH was designed to synthesize the results of typical gamma-ray spectroscopy experiments. The code allows a user to specify the physical characteristics of a gamma-ray source, the quantity of radionuclides emitting gamma radiation, the source-to-detector distance and the presence and type of any intervening absorbers, the size and type of the gamma-ray detector, and the electronic set-up used to gather the data.

  2. Gamma rays produce superior seedless citrus

    SciTech Connect

    Pyrah, D.

    1984-10-01

    Using gamma radiation, seedless forms of some varieties of oranges and grapefruit are being produced. Since it has long been known that radiation causes mutations in plants and animals, experiments were conducted to determine if seediness could be altered by exposing seeds or budwood to higher than natural doses of gamma radiation. Orange and grapefruit seeds and cuttings exposed to gamma rays in the early 1970's have produced trees that bear fruit superior to that now on the market.

  3. Detection of gamma-ray-induced DNA damages in malformed dominant lethal embryos of the Japanese medaka (Oryzias latipes) using AP-PCR fingerprinting.

    PubMed

    Kubota, Y; Shimada, A; Shima, A

    1992-12-01

    Adult male fish of the medaka HNI strain exposed to 9.5 Gy or 19 Gy (0.95 Gy/min) of gamma-rays were mated with non-irradiated female fish of the Hd-rR strain. Genomic DNA was prepared from malformed individual embryos which were expected to be dominant lethal and used for AP-PCR fingerprinting. By the use of a part of the T3 promoter sequence (20 mer), which, to our knowledge, is not found in the medaka genome as an arbitrary primer, we found polymorphisms in genomic fingerprints which could distinguish the parental strains. On the other hand, we found that the fingerprints of F1 hybrids were the sum of those of their parents. Based on these findings, we analyzed the fingerprints of genomic DNA of each severely malformed embryo, because we expect that radiation-induced genomic damages resulting in severe malformation and eventually in dominant lethals should be detected as changes in paternal fingerprints of F1 hybrids. Indeed, we succeeded in detecting changes in genomic DNA as loss of some paternal bands in fingerprints of malformed embryos. One of 10 malformed embryos obtained from 9.5 Gy gamma-irradiated males had lost one band of the paternal origin and 4 of 12 malformed embryos obtained from 19 Gy gamma-irradiated males had lost 5 bands. These results indicated a possibility that quantitative as well as qualitative estimation of gamma-ray-induced DNA damages can be made by this method which does not require the functional selection based on a specific target gene. PMID:1383799

  4. Cosmic gamma rays

    NASA Astrophysics Data System (ADS)

    Wolfendale, A. W.

    The composition and implications of gamma rays observed by satellites are discussed. SAS II and COS B data from the direction of the Crab and Vela pulsars, 3C273, and the molecular cloud in the vicinity of Rho Oph are examined. It is noted that the 2-3 deg resolution of the detectors demands the consideration that cosmic ray electrons interacting with the interstellar medium could invalidate any positive definition of a particular source. Mechanisms of cosmic ray production by interstellar clouds are reviewed, and evidence is cited for a possible galactic source of some of the emissions. Observations of a 100 MeV flux coming from the direction of 2CGl95 + 04, through a relatively uncluttered region, does suggest a discrete source. Extragalactic rays possibly originate in the galactic halo. Models of equal X ray flux from all directions, with some enhancement from directions containing galaxies, seem to correspond with observations.

  5. Gamma Ray Bursts - Observations

    NASA Technical Reports Server (NTRS)

    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.

  6. Cosmic gamma rays from quasars

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  7. Gamma-Ray Pulsar Revolution

    NASA Astrophysics Data System (ADS)

    Caraveo, Patrizia A.

    2014-08-01

    Isolated neutron stars (INSs) were the first sources identified in the field of high-energy gamma-ray astronomy. In the 1970s, only two sources had been identified, the Crab and Vela pulsars. However, although few in number, these objects were crucial in establishing the very concept of a gamma-ray source. Moreover, they opened up significant discovery space in both the theoretical and phenomenological fronts. The need to explain the copious gamma-ray emission of these pulsars led to breakthrough developments in understanding the structure and physics of neutron star (NS) magnetospheres. In parallel, the 20-year-long chase to understand the nature of Geminga unveiled the existence of a radio-quiet, gamma-ray-emitting INS, adding a new dimension to the INS family. We are living through an extraordinary time of discovery. The current generation of gamma-ray detectors has vastly increased the population of known gamma-ray-emitting NSs. The 100 mark was crossed in 2011, and we are now over 150. The gamma-ray-emitting NS population exhibits roughly equal numbers of radio-loud and radio-quiet young INSs, plus an astonishing, and unexpected, group of isolated and binary millisecond pulsars (MSPs). The number of MSPs is growing so rapidly that they are on their way to becoming the most numerous members of the family of gamma-ray-emitting NSs. Even as these findings have set the stage for a revolution in our understanding of gamma-ray-emitting NSs, long-term monitoring of the gamma-ray sky has revealed evidence of flux variability in the Crab Nebula as well as in the pulsed emission from PSR J2021+4026, challenging a four-decades-old, constant-emission paradigm. Now we know that both pulsars and their nebulae can, indeed, display variable emission.

  8. Genetic dissimilarity of putative gamma-ray-induced 'Preciosa-AAAB-Pome type' banana (Musa sp) mutants based on multivariate statistical analysis.

    PubMed

    Pestana, R K N; Amorim, E P; Ferreira, C F; Amorim, V B O; Oliveira, L S; Ledo, C A S; Silva, S O

    2011-01-01

    Bananas are among the most important fruit crops worldwide, being cultivated in more than 120 countries, mainly by small-scale producers. However, short-stature high-yielding bananas presenting good agronomic characteristics are hard to find. Consequently, wind continues to damage a great number of plantations each year, leading to lodging of plants and bunch loss. Development of new cultivars through conventional genetic breeding methods is hindered by female sterility and the low number of seeds. Mutation induction seems to have great potential for the development of new cultivars. We evaluated genetic dissimilarity among putative 'Preciosa' banana mutants generated by gamma-ray irradiation, using morphoagronomic characteristics and ISSR markers. The genetic distances between the putative 'Preciosa' mutants varied from 0.21 to 0.66, with a cophenetic correlation coefficient of 0.8064. We found good variability after irradiation of 'Preciosa' bananas; this procedure could be useful for banana breeding programs aimed at developing short-stature varieties with good agronomic characteristics. PMID:22033908

  9. High energy gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Fichtel, Carl E.

    1987-01-01

    High energy gamma ray astronomy has evolved with the space age. Nonexistent twenty-five years ago, there is now a general sketch of the gamma ray sky which should develop into a detailed picture with the results expected to be forthcoming over the next decade. The galactic plane is the dominant feature of the gamma ray sky, the longitude and latitude distribution being generally correlated with galactic structural features including the spiral arms. Two molecular clouds were already seen. Two of the three strongest gamma ray sources are pulsars. The highly variable X-ray source Cygnus X-3 was seen at one time, but not another in the 100 MeV region, and it was also observed at very high energies. Beyond the Milky Way Galaxy, there is seen a diffuse radiation, whose origin remains uncertain, as well as at least one quasar, 3C 273. Looking to the future, the satellite opportunities for high energy gamma ray astronomy in the near term are the GAMMA-I planned to be launched in late 1987 and the Gamma Ray Observatory, scheduled for launch in 1990. The Gamma Ray Observatory will carry a total of four instruments covering the entire energy range from 30,000 eV to 3 x 10 to the 10th eV with over an order of magnitude increase in sensitivity relative to previous satellite instruments.

  10. Elemental mapping of planetary surfaces using gamma-ray spectroscopy

    SciTech Connect

    Reedy, R.C.

    1990-01-01

    The gamma rays escaping from a planet can be used to map the concentrations of various elements in its surface. In a planet, the high-energy particles in the galactic cosmic rays induce a cascade of particles that includes many neutrons. The {gamma} rays are made by the nuclear excitations induced by these cosmic-ray particles and their secondaries (especially capture or inelastic-scattering reactions induced by neutrons) and decay of the naturally-occurring radioelements. After a short history of planetary {gamma}-ray spectroscopy and its applications, the {gamma}-ray spectrometer planned for the Mars Observer mission is presented. The results of laboratory experiments that simulate the cosmic-ray bombardments of planetary surfaces or measure cross sections for the production of {gamma} rays and the status of the theoretical calculations for the processes that make and transport neutrons and {gamma} rays will be reviewed. The emphasis here is on studies of Mars and on new ideas, concepts, and problems that have arisen over the last decade, such as Doppler broadening and peaks from neutron scattering with germanium nuclei in a high-resolution {gamma}-ray spectrometer. 31 refs., 1 fig., 1 tab.

  11. Gamma-Ray Localization of Terrestrial Gamma-Ray Flashes

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

    Terrestrial gamma-ray flashes (TGFs) are very short bursts of high-energy photons and electrons originating in Earth’s atmosphere. We present here a localization study of TGFs carried out at gamma-ray energies above 20 MeV based on an innovative event selection method. We use the AGILE satellite Silicon Tracker data that for the first time have been correlated with TGFs detected by the AGILE Mini-Calorimeter. We detect 8 TGFs with gamma-ray photons of energies above 20 MeV localized by the AGILE gamma-ray imager with an accuracy of ˜5-10° at 50 MeV. Remarkably, all TGF-associated gamma rays are compatible with a terrestrial production site closer to the subsatellite point than 400 km. Considering that our gamma rays reach the AGILE satellite at 540 km altitude with limited scattering or attenuation, our measurements provide the first precise direct localization of TGFs from space.

  12. CO sub 2 ter dot minus radical induced cleavage of disulfide bonds in proteins. A gamma-ray and pulse radiolysis mechanistic investigation

    SciTech Connect

    Favaudon, V.; Tourbez, H.; Lhoste, J-M. ); Houee-Levin, C. )

    1990-12-01

    Disulfide bond reduction by the CO{sub 2}{sup {center dot}{minus}} radical was investigated in aponeocarzinostatin, aporiboflavin-binding protein, and bovine immunoglobulin. Protein-bound cysteine free thiols were formed under {gamma}-ray irradiation in the course of a pH-dependent and protein concentration dependent chain reaction. The chain efficiency increased upon acidification of the medium, with an apparent pK{sub a} around 5, and decreased abruptly below pH 3.6. It decreased also at neutral pH as cysteine accumulated. From pulse radiolysis analysis, CO{sub 2}{sup {center dot}{minus}} proved able to induce rapid one-electron oxidation of thiols and of tyrosine phenolic groups in addition to one-electron donation to exposed disulfide bonds. The bulk rate constant of CO{sub 2}{sup {center dot}{minus}} uptake by the native proteins was 5{minus} to 10-fold faster at pH 3 than at pH 8, and the protonated form of the disulfide radical anion, appeared to be the major protein radical species formed under acidic conditions. Formation of the disulfide radical cation, phenoxyl radical Tyr-O{sup {center dot}} disproportionation, and phenoxyl radical induced oxidation of preformed thiol groups should also be taken into consideration to explain the fate of the oxygen-centered phenoxyl radical.

  13. Gamma rays from dark matter

    NASA Astrophysics Data System (ADS)

    Protheroe, Raymond J.

    2001-04-01

    I give a brief review of high energy gamma-ray signatures of dark matter. The decay of massive X-particles and subsequent hadronization have been suggested as the origin of the highest energy cosmic rays. Propagation over cosmological distances to Earth (as would be the case in some topological defect origin models for the X-particles) results in potentially observable gamma-ray fluxes at GeV energies. Massive relic particles on the other hand, would cluster in galaxy halos, including that of our Galaxy, and may give rise to anisotropic gamma ray and cosmic ray signals at ultra high energies. Future observations above 100 Gev of gamma rays due to WIMP annihilation in the halo of the Galaxy may be used to place constraints on supersymmetry parameter space. .

  14. Directional detector of gamma rays

    DOEpatents

    Cox, Samson A.; Levert, Francis E.

    1979-01-01

    A directional detector of gamma rays comprises a strip of an electrical cuctor of high atomic number backed with a strip of a second electrical conductor of low atomic number. These elements are enclosed within an electrical conductor that establishes an electrical ground, maintains a vacuum enclosure and screens out low-energy gamma rays. The detector exhibits a directional sensitivity marked by an increased output in the favored direction by a factor of ten over the output in the unfavored direction.

  15. Gamma-ray line astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1979-01-01

    Gamma-ray astronomy is a valuable source of information on solar activity, supernovae, and nucleosynthesis. Cosmic gamma-ray lines were first observed from solar flares and more recently from the galactic center and a transient event. The latter may give an important insight into nuclear reactions taking place near neutron stars and black holes and a measure of the gravitational redshifts of such objects.

  16. Lightning Generated Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Milikh, Gennady

    1996-01-01

    The prime focus of this effort is to advance the state of understanding of correlation between lightning strokes and gamma-ray flashes. key issue addressed was the revision of the existing models of runaway breakdown in the stratosphere due to low altitude lightning, which are related to the source of gamma-ray flashes. The revision includes the assessment of the effect due to geomagnetic field on the development of runaway discharge.

  17. Gamma-ray spectrometer experiment

    NASA Technical Reports Server (NTRS)

    Arnold, J. R.; Peterson, L. E.; Metzger, A. E.; Trombka, J. I.

    1972-01-01

    The experiments in gamma-ray spectrometry to determine the geochemical composition of the lunar surface are reported. The theory is discussed of discrete energy lines of natural radioactivity, and the lines resulting from the bombardment of the lunar surface by high energy cosmic rays. The gamma-ray spectrometer used in lunar orbit and during transearth coast is described, and a preliminary analysis of the results is presented.

  18. Evolution of Intracluster Cosmic Rays and Gamma-Ray Emission

    NASA Astrophysics Data System (ADS)

    Tsubaki, Shin-Ya; Kitayama, Tetsu; Sato, Katsuhiko

    2003-07-01

    The effect of merger history of clusters of galaxies on intra-cluster cosmic rays (ICCRs) is investigated. Though the effect of merger shock, which is responsible for (in-situ) acceleration of ICCRs, is ignored here, the effect of evolution is important for ICCRs and induced gamma-rays. Taking star formation history into account, we find 1) the gamma-ray flux from a cluster of galaxies is consistent with EGRET observation, and the detection by the GLAST is possible, and 2) the contribution of clusters of galaxies to the diffuse gamma-ray background is not so large, with reasonable parameter range.

  19. Fail-Safe Therapy by Gamma-Ray Irradiation Against Tumor Formation by Human-Induced Pluripotent Stem Cell-Derived Neural Progenitors.

    PubMed

    Katsukawa, Mitsuko; Nakajima, Yusuke; Fukumoto, Akiko; Doi, Daisuke; Takahashi, Jun

    2016-06-01

    Cell replacement therapy holds great promise for Parkinson's disease (PD), but residual undifferentiated cells and immature neural progenitors in the therapy may cause tumor formation. Although cell sorting could effectively exclude these proliferative cells, from the viewpoint of clinical application, there exists no adequate coping strategy in the case of their contamination. In this study, we analyzed a component of proliferative cells in the grafts of human-induced pluripotent stem cell-derived neural progenitors and investigated the effect of radiation therapy on tumor formation. In our differentiating protocol, analyses of neural progenitors (day 19) revealed that the proliferating cells expressed early neural markers (SOX1, PAX6) or a dopaminergic neuron progenitor marker (FOXA2). When grafted into the rat striatum, these immature neurons gradually became postmitotic in the brain, and the rosette structures disappeared at 14 weeks. However, at 4-8 weeks, the SOX1(+)PAX6(+) cells formed rosette structures in the grafts, suggesting their tumorigenic potential. Therefore, to develop a fail-safe therapy against tumor formation, we investigated the effect of radiation therapy. At 4 weeks posttransplantation, when KI67(+) cells comprised the highest ratio, radiation therapy with (137)Cs Gammacell Exactor for tumor-bearing immunodeficient rats showed a significant decrease in graft volume and percentage of SOX1(+)KI67(+) cells in the graft, thus demonstrating the preventive effect of gamma-ray irradiation against tumorigenicity. These results give us critical criteria for the safety of future cell replacement therapy for PD. PMID:27059007

  20. Loss of a putative tumor suppressor locus after gamma-ray-induced neoplastic transformation of HeLa x Skin fibroblast human cell hybrids

    SciTech Connect

    Mendonca, M.S.; Redpath, J.L.; Fasching, C.L.

    1995-07-01

    The nontumorigenic HeLa x skin fibroblast hybrid cell line, CGL1, can be induced to re-express HeLa tumor-associated cell surface antigen, p75-IAP (intestinal alkaline phosphatase), with resulting neoplastic transformation, by exposure to {gamma} radiation. This has allowed the human hybrid system to be developed into a quantitative in vitro model for radiation-induced neoplastic transformation of human cells. Recently, several {gamma}-ray-induced IAP-expression mutants (GIMs) of the nontumorigenic HeLa x skin fibroblast hybrid CGL1 were isolated and all were tumorigenic when injected subcutaneously into nude mice. Control cell lines which were negative for p75-IAP (CONs) were also isolated from irradiated populations, and none were found to be tumorigenic. We have now begun to investigate the molecular basis of radiation-induced neoplastic transformation in this system by studying the potential genetic linkage between p75/IAP expression, tumorigenicity and damage to a putative tumor suppressor locus on fibroblast chromosome 11. Previous analysis of rare spontaneous segregants has indicated that this locus is involved in the regulation of tumorigenicity and in the expression of the HeLa tumor-associated cell surface marker intestinal alkaline phosphatase (p75-IAP) in this system. Therefore, analysis by restriction fragment length polymorphism and chromosome painting have been performed for chromosome 11, and for chromosome 13 as a control, for the p75/IAP-positive GIM and p75/IAP-negative CON cell lines. We report that in five of eight of the GIMs large-scale damage to the fibroblast chromosome 11`s is evident (four GIMs have lost one complete copy of a fibroblast chromosome 11 heavily damaged). None of the CONs, however (0/5), have lost a complete copy of either fibroblast chromosome 11. No large-scale damage to the control chromosome 13`s was detected in the GIMs or CONs. 49 refs., 3 figs., 2 tabs.

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

    SciTech Connect

    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.

  2. Compton Gamma-Ray Observatory

    NASA Technical Reports Server (NTRS)

    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.

  3. Compton Gamma-Ray Observatory

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This photograph shows the Compton Gamma-Ray Observatory being released from the Remote Manipulator System (RMS) arm aboard the Space Shuttle Atlantis during the STS-35 mission in April 1991. The GRO reentered the Earth's atmosphere and ended its successful mission in June 2000. For nearly 9 years, GRO's Burst and Transient Source Experiment (BATSE), designed and built by the Marshall Space Flight Center, kept an unblinking watch on the universe to alert scientist 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 star, 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 BATSE's science program.

  4. Hard X-ray and gamma-rays from supernovae

    NASA Technical Reports Server (NTRS)

    Woosley, S. E.

    1993-01-01

    The hard electromagnetic radiation produced by and accompanying the explosion of supernovae is discussed. This radiation may have three origins: (i) the eruption of the shock wave from the surface of the star; (ii) radioactive decay of unstable isotopes produced during the explosion; and (iii) gamma-rays produced by neutrino annihilation following accretion-induced collapse. Though the latter has been proposed as a mechanism for making cosmological gamma-ray bursts, it is shown that this is unlikely.

  5. Gamma-ray Output Spectra from 239 Pu Fission

    SciTech Connect

    Ullmann, John

    2015-05-25

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

  6. Study of {gamma}-ray irradiation effect on permanent magnets

    SciTech Connect

    Gao, R. S.; Zhen, L.; Shao, W. Z.; Sun, X. Y.; Yang, L.; Hao, X. P.; Wang, B. Y.

    2008-04-01

    Irradiation damage of FeCrCo, AlNiCo, SmCo, and NdFeB permanent magnets was investigated by using {gamma}-ray irradiation. Results of magnetic property measurement show that FeCrCo and NdFeB have more demagnetization than AlNiCo and SmCo. X-ray diffraction analysis shows that {gamma}-ray irradiation leads to the increase of FeCrCo crystal mismatch and decrease of AlNiCo ordering degree. The investigations by positron annihilation spectroscopy technique show that the defects in AlNiCo and SmCo increase after {gamma}-ray irradiation. The defects induced by {gamma}-ray irradiation in NdFeB magnets are not the main source that leads to partial demagnetization. The irradiation resistances of these magnets are discussed in detail considering the thermal stability, coercivity mechanisms, and defect damage.

  7. Gamma-ray exposure from neutron-induced radionuclides in soil in Hiroshima and Nagasaki based on DS02 calculations.

    PubMed

    Imanaka, Tetsuji; Endo, Satoru; Tanaka, Kenichi; Shizuma, Kiyoshi

    2008-07-01

    As a result of joint efforts by Japanese, US and German scientists, the Dosimetry System 2002 (DS02) was developed as a new dosimetry system, to evaluate individual radiation dose to atomic bomb survivors in Hiroshima and Nagasaki. Although the atomic bomb radiation consisted of initial radiation and residual radiation, only initial radiation was reevaluated in DS02 because, for most survivors in the life span study group, the residual dose was negligible compared to the initial dose. It was reported, however, that there were individuals who entered the city at the early stage after the explosion and experienced hemorrhage, diarrhea, etc., which were symptoms of acute radiation syndrome. In this study, external exposure due to radionuclides induced in soil by atomic bomb neutrons was reevaluated based on DS02 calculations, as a function of both the distance from the hypocenters and the elapsed time after the explosions. As a result, exposure rates of 6 and 4 Gy h(-1) were estimated at the hypocenter at 1 min after the explosion in Hiroshima and Nagasaki, respectively. These exposure rates decreased rapidly by a factor of 1,000 1 day later, and by a factor of 1 million 1 week later. Maximum cumulative exposure from the time of explosion was 1.2 and 0.6 Gy at the hypocenters in Hiroshima and Nagasaki, respectively. Induced radiation decreased also with distance from the hypocenters, by a factor of about 10 at 500 m and a factor of three to four hundreds at 1,000 m. Consequently, a significant exposure due to induced radiation is considered feasible to those who entered the area closer to a distance of 1,000 m from the hypocenters, within one week after the bombing. PMID:18368418

  8. The Gamma-Ray Observatory

    NASA Technical Reports Server (NTRS)

    Kniffen, Donald A.

    1989-01-01

    The scientific goals and the design of the NASA Gamma-Ray Observatory (GRO), planned for launch in mid-1990, are described together with the experiments to be performed on the GRO mission and the instruments to be flown on the Observatory. GRO contains a complement of four instruments to span the spectrum from 0.03 to 20,000 MeV in energy, three of which are optimized to make gamma-ray observations using either the photoelectric effect, the Compton scatter, or the pair production processes; the fourth instrument is optimized for high-sensitivity observations of transient events and time-variable sources. The instruments are the Oriented Scintillation Spectrometer Experiment, the Compton Telescope, the Energetic Gamma-Ray Experiment Telescope, and the Burst and Transient Source Experiment.

  9. The Gamma-ray Sky with Fermi

    NASA Technical Reports Server (NTRS)

    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.

  10. Study of radiation dose induced by cosmic-ray origin low-energy gamma rays and electrons near sea level

    NASA Astrophysics Data System (ADS)

    Mrdja, D.; Bikit, I.; Bikit, K.; Slivka, J.; Anicin, I.

    2015-02-01

    For a long time, it has been known that low-energy continuous gamma radiation is present in open air at the Earth's surface. In previous investigations it was assumed that this radiation is produced almost exclusively by gamma photons emitted due to the natural radioactivity, which are backscattered by air above ground. We show that significant amount of this radiation (related to energy region 30-300 keV) that peaks at about 90 keV, is produced by cosmic-rays, with the photon flux of about 3000 m-2 s-1. We find that the contribution of this omnipresent low-energy gamma radiation of cosmic-ray origin, including the corresponding low-energy electron flux, to the doses of general population are non-negligible components of overall doses induced by cosmic rays near sea level.

  11. Gamma-ray Imaging Methods

    SciTech Connect

    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.

  12. Cosmography by gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Capozziello, S.; Izzo, L.

    2008-10-01

    Aims: Relations connecting gamma ray burst quantities can be used to constrain cosmographic parameters of the Hubble law at medium-high redshifts. Methods: We consider a sample of 27 gamma ray bursts to construct the luminosity distance to redshift relation and derive the values of the parameters q_0, j_0, and s_0. The analysis is compared with other methods in the literature. Results: Gamma gay bursts, if calibrated by SNeIa, seem reliable as distance indicators and give cosmographic parameters in agreement with the ΛCDM model.

  13. Towed seabed gamma ray spectrometer

    SciTech Connect

    Jones, D.G. )

    1994-08-01

    For more than 50 years, the measurement of radioactivity has been used for onshore geological surveys and in laboratories. The British Geological Survey (BGS) has extended the use of this type of equipment to the marine environment with the development of seabed gamma ray spectrometer systems. The present seabed gamma ray spectrometer, known as the Eel, has been successfully used for sediment and solid rock mapping, mineral exploration, and radioactive pollution studies. The range of applications for the system continues to expand. This paper examines the technological aspects of the Eel and some of the applications for which it has been used.

  14. The cAMP signaling system inhibits the repair of {gamma}-ray-induced DNA damage by promoting Epac1-mediated proteasomal degradation of XRCC1 protein in human lung cancer cells

    SciTech Connect

    Cho, Eun-Ah; Juhnn, Yong-Sung

    2012-06-01

    Highlights: Black-Right-Pointing-Pointer cAMP signaling system inhibits repair of {gamma}-ray-induced DNA damage. Black-Right-Pointing-Pointer cAMP signaling system inhibits DNA damage repair by decreasing XRCC1 expression. Black-Right-Pointing-Pointer cAMP signaling system decreases XRCC1 expression by promoting its proteasomal degradation. Black-Right-Pointing-Pointer The promotion of XRCC1 degradation by cAMP signaling system is mediated by Epac1. -- Abstract: Cyclic AMP is involved in the regulation of metabolism, gene expression, cellular growth and proliferation. Recently, the cAMP signaling system was found to modulate DNA-damaging agent-induced apoptosis by regulating the expression of Bcl-2 family proteins and inhibitors of apoptosis. Thus, we hypothesized that the cAMP signaling may modulate DNA repair activity, and we investigated the effects of the cAMP signaling system on {gamma}-ray-induced DNA damage repair in lung cancer cells. Transient expression of a constitutively active mutant of stimulatory G protein (G{alpha}sQL) or treatment with forskolin, an adenylyl cyclase activator, augmented radiation-induced DNA damage and inhibited repair of the damage in H1299 lung cancer cells. Expression of G{alpha}sQL or treatment with forskolin or isoproterenol inhibited the radiation-induced expression of the XRCC1 protein, and exogenous expression of XRCC1 abolished the DNA repair-inhibiting effect of forskolin. Forskolin treatment promoted the ubiquitin and proteasome-dependent degradation of the XRCC1 protein, resulting in a significant decrease in the half-life of the protein after {gamma}-ray irradiation. The effect of forskolin on XRCC1 expression was not inhibited by PKA inhibitor, but 8-pCPT-2 Prime -O-Me-cAMP, an Epac-selective cAMP analog, increased ubiquitination of XRCC1 protein and decreased XRCC1 expression. Knockdown of Epac1 abolished the effect of 8-pCPT-2 Prime -O-Me-cAMP and restored XRCC1 protein level following {gamma}-ray irradiation. From these results, we conclude that the cAMP signaling system inhibits the repair of {gamma}-ray-induced DNA damage by promoting the ubiquitin-proteasome dependent degradation of XRCC1 in an Epac-dependent pathway in lung cancer cells.

  15. [Contribution of 210Bi beta-ray induced bremsstrahlung to the emission of Pb-KX-rays observed in the lead shielded gamma-ray background spectrum (author's transl)].

    PubMed

    Shima, K; Mihara, T; Umetani, K; Mikumo, T

    1980-08-01

    Observation of gamma-ray background has been done by using a Ge(Li) semiconductor detector when it was placed inside the lead shielding material. With the aid of a very simple model calculation, the concentration of 210Pb radioisotope embedded in the lead material has been estimated to be 0.1-0.4 (Bq/Pb-g) (3-12 (pCi/Pb-g). The origin of Pb-KX-ray emission, the highest peak in the background spectrum, has been investigated by comparing the 210Pb-47 keV gamma-ray and Pb-KX-ray peak counts. As the results, about 50 +/- 30% of Pb-KX-ray production is estimated to be due to the Pb-K shell photoionization which is induced by the bremsstrahlung of 210Bi beta-ray. PMID:7208990

  16. Apoptosis (cell death) induced in mouse bowel by 1,2-dimethylhydrazine, methylazoxymethanol acetate, and gamma-rays

    SciTech Connect

    Ijiri, K. )

    1989-11-15

    Apoptosis is a pattern of cell death involving nuclear pyknosis, cytoplasmic condensation, and karyorrhexis. The frequency of apoptosis after treatment with two colon carcinogens and radiation was studied in the crypts of five different portions of mouse bowel. When 1,2-dimethylhydrazine (DMH) was injected s.c., the earliest rise in apoptotic incidence after a high dose (200 mg/kg) was noted at 3 h in small intestine and at 6 h in large bowel. After i.p. administration of methylazoxymethanol (MAM) acetate, apoptotic cells were seen in large bowel after 3 h. When the plateau values attained after high doses of DMH were compared, many apoptotic cells were found in the lower part of the large bowel, whereas few such cells were observed in the small intestine and the upper part of the large bowel. This finding was reversed in the case of radiation-induced apoptosis. In the descending colon, a definite circadian rhythm in the apoptotic incidence was observed 6 h after injection of DMH or MAM acetate. Apoptosis showed a high incidence when these drugs were given between 2400 h and 0900 h, but a low incidence after administration between 1200 h and 2100 h. In the small intestine a rhythm was also noted for MAM acetate, but not significantly for DMH.

  17. Gamma ray slush hydrogen monitor

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  18. Quasars, blazars, and gamma rays.

    PubMed

    Dermer, C D; Schlickeiser, R

    1992-09-18

    Before the launch of the Compton Gamma Ray Observatory (CGRO), the only source of >100-megaelectron volt (MeV) gamma radiation known outside our galaxy was the quasar 3C 273. After less than a year of observing, 13 other extragalactic sources have been discovered with the Energetic Gamma Ray Experiment Telescope (EGRET) on CGRO, and it is expected that many more will be found before the full sky survey is complete. All 14 sources show evidence of blazar properties at other wavelengths; these properties include high optical polarization, extreme optical variability, flat-spectrum radio emission associated with a compact core, and apparent superluminal motion. Such properties are thought to be produced by those few, rare extragalactic radio galaxies and quasars that are favorably aligned to permit us to look almost directly down a relativistically outflowing jet of matter expelled from a supermassive black hole. Although the origin of the gamma rays from radio jets is a subject of much controversy, the gamma-ray window probed by CGRO is providing a wealth of knowledge about the central engines of active galactic nuclei and the most energetic processes occurring in nature. PMID:17841159

  19. Gamma-ray camera flyby

    SciTech Connect

    2010-01-01

    Animation based on an actual classroom demonstration of the prototype CCI-2 gamma-ray camera's ability to image a hidden radioactive source, a cesium-137 line source, in three dimensions. For more information see http://newscenter.lbl.gov/feature-stories/2010/06/02/applied-nuclear-physics/.

  20. Advances in gamma-ray line astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1983-01-01

    Gamma ray line observations of solar flares, gamma ray transients, and the galactic center are reviewed and interpreted. Prospects of future line detections are discussed. Previously announced in STAR as N82-27200

  1. The Gamma-ray Universe through Fermi

    NASA Technical Reports Server (NTRS)

    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.

  2. Diagnosing ICF gamma-ray physics

    SciTech Connect

    Herrmann, Hans W; Kim, Y H; Mc Evoy, A; Young, C S; Mack, J M; Hoffman, N; Wilson, D C; Langenbrunner, J R; Evans, S; Sedillo, T; Batha, S H; Dauffy, L; Stoeffl, W; Malone, R; Kaufman, M I; Cox, B C; Tunnel, T W; Miller, E K; Rubery, M

    2010-01-01

    Gamma rays produced in an ICF environment open up a host of physics opportunities we are just beginning to explore. A branch of the DT fusion reaction, with a branching ratio on the order of 2e-5 {gamma}/n, produces 16.7 MeV {gamma}-rays. These {gamma}-rays provide a direct measure of fusion reaction rate (unlike x-rays) without being compromised by Doppler spreading (unlike neutrons). Reaction-rate history measurements, such as nuclear bang time and burn width, are fundamental quantities that will be used to optimize ignition on the National Ignition Facility (NIF). Gas Cherenkov Detectors (GCD) that convert fusion {gamma}-rays to UV/visible Cherenkov photons for collection by fast optical recording systems established their usefulness in illuminating ICF physics in several experimental campaigns at OMEGA. Demonstrated absolute timing calibrations allow bang time measurements with accuracy better than 30 ps. System impulse response better than 95 ps fwhm have been made possible by the combination of low temporal dispersion GCDs, ultra-fast microchannel-plate photomultiplier tubes (PMT), and high-bandwidth Mach Zehnder fiber optic data links and digitizers, resulting in burn width measurement accuracy better than 10ps. Inherent variable energy-thresholding capability allows use of GCDs as {gamma}-ray spectrometers to explore other interesting nuclear processes. Recent measurements of the 4.44 MeV {sup 12}C(n,n{prime}) {gamma}-rays produced as 14.1 MeV DT fusion neutrons pass through plastic capsules is paving the way for a new CH ablator areal density measurement. Insertion of various neutron target materials near target chamber center (TCC) producing secondary, neutron-induced {gamma}y-rays are being used to study other nuclear interactions and as in-situ sources to calibrate detector response and DT branching ratio. NIF Gamma Reaction History (GRH) diagnostics, based on the GCD concept, are now 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: (1) four PMT-based channels mounted to the outside of the target chamber at {approx}6m from TCC (GRH-6m) for the 3e13-3e16 DT neutron yield range expected during the early ignition-tuning campaigns; and (2) several channels located just inside the target bay shield wall at 15 m from TCC (GRH-15m) with optical paths leading through the cement shield wall to well-shielded streak cameras and PMTs for the 1e16-1e20 yield range expected during the DT ignition campaign. Multiple channels at each phase will allow for increased redundancy, reliability, accuracy and flexibility. This suite of diagnostics will make possible exploration of interesting {gamma}-ray physics well beyond the ignition campaign.

  3. Nuclear gamma rays from energetic particle interactions

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  4. Gamma ray spectroscopy in astrophysics. [conferences

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  5. Measurement of deuteron induced gamma-ray emission differential cross sections on natCl from 1.0 to 2.0 MeV

    NASA Astrophysics Data System (ADS)

    Jokar, A.; Kakuee, O.; Lamehi-Rachti, M.

    2016-06-01

    In this research work, measured differential cross sections for gamma-ray emission from the nuclear reactions 35Cl(d,pγ1-0)36Cl (Eγ = 788 keV), 35Cl(d,pγ2-0)36Cl (Eγ = 1165 keV), 37Cl(d,pγ1-0)38Cl (Eγ = 671 keV) and 37Cl(d,pγ2-0)38Cl (Eγ = 755 keV) are presented. For these measurements a thin natural BaCl2 target evaporated onto a 50 μm-thick Mo foil was used. The gamma-rays and backscattered deuterons were detected simultaneously. An HPGe detector placed at an angle of 90° with respect to the beam direction was employed to collect gamma-rays while an ion implanted Si detector placed at a scattering angle of 165° was used to detect backscattered deuterons. The validity of the obtained differential cross sections was verified through a thick target benchmarking experiment. The overall systematic uncertainty of cross section values was estimated to be ±10%.

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

    NASA Astrophysics Data System (ADS)

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

    1999-01-01

    The determination of elemental abundances is one of the highest science objectives of most lunar missions. Such multi-element abundances, ratios, or maps should include results for elements that are diagnostic or important in lunar processes, including heat-producing elements (such as K and Th), important incompatible elements (Th and rare earth elements), H (for polar deposits and regolith maturity), and key variable elements in major lunar provinces (such as Fe and Ti in the maria). Both neutron and gamma-ray spectroscopy can be used to infer elemental abundances; the two complement each other. These elemental abundances need to be determined with high accuracy and precision from measurements such as those made by the gamma-ray spectrometer (GRS) and neutron spectrometers (NS) on Lunar Prospector. As presented here, a series of steps, computer codes, and nuclear databases are needed to properly convert the raw gamma-ray and neutron measurements into good elemental abundances, ratios, and/or maps. Lunar Prospector (LP) is the first planetary mission that has measured neutrons escaping from a planet other than the Earth. The neutron spectrometers on Lunar Prospector measured a wide range of neutron energies. The ability to measure neutrons with thermal (E < 0.1 eV), epithermal (E about equal 0.1 - 1000 eV), and fast (E about 0.1-10 MeV) energies maximizes the scientific return, being especially sensitive to both H (using epithermal neutrons) and thermal-neutron-absorbing elements. Neutrons are made in the lunar surface by the interaction of galactic-cosmic-ray (GCR) particles with the atomic nuclei in the surface. Most neutrons are produced with energies above about 0.1 MeV. The flux of fast neutrons in and escaping from the Moon depends on es the intensity of the cosmic rays (which vary with solar activity) and the elemental composition of the surface. Variations in the elemental composition of the lunar surface can affect the flux of fast neutrons by about 25% , with Ti and Fe emitting more fast neutrons than light elements like O and Si. Most elements moderate neutrons to thermal energies at similar rates. The main exception is when neutrons scatter from H, in which case neutrons can be rapidly thermalized. The cross sections for the absorption of thermal neutrons can vary widely among elements, with major elements like Ti and Fe having high-capture cross sections. Some trace elements, such as Sm and Gd, have such large neutron-absorption cross sections that, despite their low abundances, can absorb significant amounts of thermal neutrons in the Moon. Because the processes affecting neutrons are complicated, good modeling is needed to properly extract elemental information from measured neutron fluxes. The LAHET Code System (LCS) can be use to calculate neutron fluxes from GCR interactions in the Moon. Lunar Gamma-Ray Spectroscopy: The main sources of planetary gamma-rays are the decay of the naturally occurring radioactive isotopes of K, Th, and U and the interactions of GCRs with atomic nuclei in the planet's surface. Most "cosmogenic" gamma-rays are produced by fast and thermal neutrons made in the planet's surface by GCRs, and their production rates can vary with time. Over 300 gamma-ray lines have been identified that can be emitted from planetary surfaces by a variety of production mechanisms. There exist nuclear databases that can be used to identify and quantify other gamma-ray lines. Use will be made of gamma-rays from major elements, particularly those from Si and O, that have not been routinely used in the past. The fluxes of gamma-rays from a given element can vary depending on many factors besides the concentration of that element. For example, the fluxes of neutron-capture gamma-rays in the planetary region of interest depend on (1) the total cross section for elements to absorb thermalized neutrons and (2) the H content of the top meter of the surface. The fluxes of the fast neutrons that induce inelastic-scattering and other nonelastic-scattering reactions can vary with the composition of the surface There are several key steps in preparing gamma-ray data into a form from which accurate elemental abundances can be determined. One needs to identify, quantify, and remove or correct for all backgrounds in the gamma-ray spectra. Among the more important of these backgrounds are features made by the decay of radioactivities made in the GRS by cosmic-ray particles and the prompt and decay gamma-rays emitted from the material surrounding the active elements of the LPGRS and from the LP spacecraft. Gamma-ray spectra obtained during the cruise to the Moon or those measured while LP was at various distances from the Moon can be used to distinguish features in the gamma-ray spectra that are from the Moon and those that are made on the LP spacecraft. Each background-corrected spectrum will be analyzed with existing gamma-ray spectral-unfolding codes to identify the energies and intensities of all peaks. These peaks will be examined when there are potential interferences in the analysis of a given gamma-ray line. Such interferences could be a problem for determining Mg and Al using some of their inelastic-scattering gamma-rays such as the 1.369-MeV gamma-ray from Mg that is also readily made from Al and Si. The key data needed to get elemental abundances from the fluxes of gamma-rays in the processed spectra are good values for the fluxes of gamma-rays that should be emitted from a given region for known or nominal elemental abundances. Such flux determinations were done for analysis of the Apollo gamma-ray data. The codes to do such calculations and the nuclear data used in such calculations have been improved much since then. Additional information contained in original.

  7. Compton Gamma Ray Observatory Guest Investigator Program

    NASA Technical Reports Server (NTRS)

    Lingenfelter, Richard E.

    1997-01-01

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

  8. Terrestrial Gamma-Ray Flashes (TGFs)

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2010-01-01

    This slide presentation reviews the observation of Terrestrial Gamma Ray Flashes (TGFs) by Gamma-Ray Telescopes. These were: (1) BATSE /Compton Observatory, (2) Solar Spectroscopic Imager, (3) AGILE Gamma-ray Telescope, and (4) Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Space Telescope. It contains charts which display the counts over time, a map or the TGFs observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). and a map showing the latitude and longitude of 85 of the TGFs observed by the Fermi GBM.

  9. Proton-induced x-ray emission, proton-induced gamma-ray emission, and x-ray absorption spectroscopy: applications to environmental analysis

    SciTech Connect

    Lytle, N.W.

    1986-01-01

    Two sample preparation techniques, the single-acid wet-oxidation and the lithium metaborate fusion-dissolution, have been applied to PIXE analysis with acceptable trace-element recoveries. A variety of samples have been prepared, including: white bass organs, deer and elk antlers. NRS standard reference materials, IAEA standard animal bone, USGS standard rock samples, and munitions disposal residues. PIGE analysis has been applied to light-element analysis of environment samples. Thin-and thick-target gamma-ray yields were determined for Li, B, O, F, Na, Mg, and Al. Light-elements in coal and oil fly ash were determined with parts per million sensitivity. Nickel and vanadium compounds have been identified in fly ash collected from vanadium compounds have been identified in fly ash collected from the flue lines of an oil-fired power plant using x-ray absorption spectroscopy. VOSO/sub 4/.3H/sub 2/O was the primary vanadium compound and NiO and NiSO/sub 4/ were the primary nickel compounds. NXRAY was written to control data acquisition on a Canberra Series 90 MCA-PDP 11/23PLUS computer system. This program provides for data to be transferred between individual collection regions of the MCA and the host computer, and spectra to be plotted on a HP 7475A graphics plotter.

  10. Gamma-ray burst systematics

    NASA Technical Reports Server (NTRS)

    Klebesadel, R. W.; Fenimore, E. E.; Laros, J. G.; Terrell, J.

    1982-01-01

    A systematic classification of gamma-ray bursts is considered on the basis of temporal and spectral burst features. Three categories of bursts are proposed, and the category of classical (or normal) bursts is subdivided into three classes: very brief, doublet/quasi-periodic, and long irregular. Apparent correlations are discussed between emission lines and the doublet/quasi-periodic class and between absorption lines and the long irregular class.

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

    SciTech Connect

    Reedy, Robert; Frankle, S. C.

    2001-01-01

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

  12. Analysis of noise power spectrum of gamma rays camera

    NASA Astrophysics Data System (ADS)

    Xie, Hongwei; Zhang, Faqiang; Zhang, Jianhua; Chen, Jinchuan; Chen, Dingyang; Li, Linbo

    2014-01-01

    Gamma rays camera is widely used in many studies, including the image diagnostics of the radiation sources, flash photography, and nondestructive assessment (NDA), etc. As a major component of the high sensitivity gamma rays camera, the MCP image intensifier is characterized in the intensified image, tunable shutter time and gain. The gamma rays camera is consisting with rays-fluorescence convertor, the optical imaging system, the MCP image intensifier, CCD and other devices. The performance of the gamma rays camera is mainly dependent on such parameters as the modulation transfer function (MTF), the noise power spectrum (NPS), and the detective quantum efficiency (DQE), etc. All of the parameters are somewhat limited by the noise characteristics of the system. Compared with the standard derivative noise distribution, the NPS, which can reflect the evolution characteristics of the noise of the imaging system with the change of the spatial frequency, could convey more information on the noise distribution in the system. In this paper, theoretical analysis is presented on the major sources of the noise in the gamma rays camera. Based on the analysis, the noise power spectra of the gamma rays camera were calibrated under various radiation dosages respectively with the visible light and gamma rays radiation sources (0.2MeV and 1.25MeV in energy, respectively). As indicated by the experimental results, the noise is majorly induced by the fluctuations of the gain of the MCP image intensifier. And the remarkable noise peak occurs nearby the spatial frequency of about 0.633 Hz/mm. And almost the same phenomena were found with both the 0.2MeV and 1.25MeV radiation energy. Besides, the noise power spectra are in circular symmetrical distribution, whose intensities are rapidly decreased with the increasing spatial frequencies.

  13. Gamma-ray astronomy: Nuclear transition region

    NASA Technical Reports Server (NTRS)

    Chupp, E. L.

    1976-01-01

    This monograph reviews the major theoretical and experimental efforts made during the past 12 years in gamma-ray astronomy over the energy range from 10 keV to about 100 MeV, where nuclear-transition lines are expected. Early attempts to detect celestial gamma rays are recounted, mechanisms of gamma-ray line and continuum production are examined, and formulas giving the various possible differential gamma-ray spectral shapes are provided. Predicted fluxes are discussed for solar gamma rays as well as for gamma emission from supernova remnants, supernovae, neutron stars, flare stars, the galactic core and disk, black holes, and diffuse sources. Gamma-ray interactions with matter are analyzed, particularly the photoelectric effect, Compton scattering from free electrons, and pair production in nuclear fields. Significant results are summarized for observations of gamma rays from the sun as well as from point and extended sources within and beyond the Galaxy, including diffuse fluxes and transient gamma-ray bursts. Factors pertaining to the design of gamma-ray astronomy experiments are considered, especially detector background limitations, gamma-ray production within instruments, and present-day detection methods.

  14. Gamma-Ray Output Spectra from 239Pu Fission

    NASA Astrophysics Data System (ADS)

    Ullmann, John; Jandel, Marian; Bredeweg, Todd; Couture, Aaron; Haight, Robert; O'Donnell, John; Vieira, David; Wu, Ching-Yen; Chyzh, Andrii; Gostic, Julie; Henderson, Roger; Kwan, Elaine

    2011-10-01

    A new measurement of the gamma-ray energy spectrum and multiplicity following neutron-induced fission of 239Pu has been made using DANCE, a highly-segmented, nearly 4 π BaF2 array at the Los Alamos Neutron Science Center. The 239Pu target consisted of an approximately 2 mg/cm2 deposit mounted in a small parallel-plate avalanche chamber inserted into the DANCE in order to tag fission events. The gamma-ray spectra were measured for several strong neutron resonances below 100 eV. The measured spectra were corrected for detector response by using simple parameterizations of the actual fission gamma-ray emission coupled with a GEANT model of the DANCE array. This research was supported by funding from the American Recovery and Reinvestment Act of 2009.

  15. High Redshift Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2012-01-01

    The Swift Observatory has been detecting 100 gamma-ray bursts per year for 7 years and has greatly stimulated the field with new findings. Observations are made of the X-ray and optical afterglow from 1 minute after the burst, continuing for days. GRBs are providing a new tool to study the high redshift universe. Swift has detected several events at z>5 and one at z=9.4 giving information on metallicity, star formation rate and reionization. The talk will present the latest results.

  16. The Fermi Gamma-Ray Space Telescope

    NASA Technical Reports Server (NTRS)

    Thompson, Dave; McEnery, Julie

    2011-01-01

    This slide presentation reviews the Gamma Ray Astronomy as enhanced by the Fermi Gamma Ray Space Telescope and Radio Astronomy as a synergistic relationship. Gamma rays often represent a significant part of the energy budget of a source; therefore, gamma-ray studies can be critical to understanding physical processes in such sources. Radio observations offer timing and spatial resolutions vastly superior to anything possible with gamma-ray telescopes; therefore radio is often the key to understanding source structure. Gamma-ray and radio observations can complement each other, making a great team. It reviews the Fermi Guest Investigator (GI) program, and calls for more cooperative work that involves Fermi and the Very Long Baseline Array (VLBA), a system of ten radio telescopes.

  17. Understanding Doppler Broadening of Gamma Rays

    SciTech Connect

    Rawool-Sullivan, Mohini; Sullivan, John P.

    2014-07-03

    Doppler-broadened gamma ray peaks are observed routinely in the collection and analysis of gamma-ray spectra. If not recognized and understood, the appearance of Doppler broadening can complicate the interpretation of a spectrum and the correct identification of the gamma ray-emitting material. We have conducted a study using a simulation code to demonstrate how Doppler broadening arises and provide a real-world example in which Doppler broadening is found. This report describes that study and its results.

  18. Gamma-Ray Astronomy Technology Needs

    NASA Technical Reports Server (NTRS)

    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.

  19. Gamma-Ray Pulsar Studies with GLAST

    NASA Technical Reports Server (NTRS)

    Thompson, David J.

    2007-01-01

    This viewgraph presentation reviews the prospects of extending the understanding of gamma ray pulsars, and answering the open questions left from the limited observations that are available from current observatories. There are 2 new gamma ray observatories that are either on orbit or will be shortly launched: (1) Astro-rivelatore Gamma a Immagini LEggero (AGILE), and Gamma-ray Large Area Space Telescope (GLAST). On board GLAST there will be two instruments Large Area Telescope (LAT), and GLAST Burst Monitor (GBM).

  20. GAMCIT: A gamma ray burst detector

    NASA Technical Reports Server (NTRS)

    Surka, Derek M.; Grunsfeld, John M.; Warneke, Brett A.

    1992-01-01

    The origin of celestial gamma ray bursts remains one of the great mysteries of modern astrophysics. The GAMCIT Get-Away-Special payload is designed to provide new and unique data in the search for the sources of gamma ray bursts. GAMCIT consists of three gamma ray detectors, an optical CCD camera, and an intelligent electronics system. This paper describes the major components of the system, including the electronics and structural designs.

  1. Gamma-Ray Bursts: a Centauro's Cry?

    NASA Astrophysics Data System (ADS)

    Silagadze, Z. K.

    2004-02-01

    Gamma-ray bursts are enigmatic flashes of gamma-rays at cosmological distances, so bright that the implied energetics is astounding: energies of order of about solar rest-energy are liberated in a time scale of the order of seconds in space regions only a few kilometres in size. Central engines capable to produce such enormous explosions, leading to a highly relativistic expending fireballs, remain a mystery. Here we propose a new candidate for the gamma-ray bursts central engine.

  2. The Andromeda galaxy in gamma-rays

    NASA Technical Reports Server (NTRS)

    Oezel, M. E.; Berkhuijsen, E. M.

    1987-01-01

    Implications of high-energy gamma-ray observations of the Andromeda galaxy with the next generation of satellites Gamma-1 and GRO are discussed in the context of the origin of cosmic rays and gamma-ray processes. The present estimate of the total gamma-ray flux of this galaxy at energies above 100 MeV is a factor of about three less than previous estimates.

  3. Hard gamma ray emission from blazars

    NASA Technical Reports Server (NTRS)

    Marscher, Alan P.; Bloom, Steven D.

    1992-01-01

    The gamma-ray emission expected from compact extragalactic sources of nonthermal radiation is examined. The highly variable objects in this class should produce copious amounts of self-Compton gamma-rays in the compact relativistic jet. This is shown to be a likely interpretation of the hard gamma-ray emission recently detected from the quasar 3C 279 during a period of strong nonthermal flaring at lower frequencies. Ways of discriminating between the self-Compton model and other possible gamma-ray emission mechanisms are discussed.

  4. Gamma-Ray Astrophysics with AGILE

    NASA Astrophysics Data System (ADS)

    Longo, F.; Tavani, M.; Barbiellini, G.; Argan, A.; Basset, M.; Boffelli, F.; Bulgarelli, A.; Caraveo, P.; Chen, A.; Costa, E.; de Paris, G.; Del Monte, E.; Di Cocco, G.; Donnarumma, I.; Feroci, M.; Fiorini, M.; Foggetta, L.; Froslyand, T.; Frutti, M.; Fuschino, F.; Galli, M.; Gianotti, F.; Giuliani, A.; Labanti, C.; Lapshov, I.; Lazzarotto, F.; Liello, F.; Lipari, P.; Marisaldi, M.; Mastropietro, M.; Mattaini, E.; Mauri, F.; Mereghetti, S.; Morelli, E.; Morselli, A.; Pacciani, L.; Pellizzoni, A.; Perotti, F.; Picozza, P.; Pittori, C.; Pontoni, C.; Porrovecchio, G.; Prest, M.; Pucella, G.; Rapisarda, M.; Rossi, E.; Rubini, A.; Soffitta, P.; Traci, A.; Trifoglio, M.; Trois, A.; Vallazza, E.; Vercellone, S.; Zambra, A.; Zanello, D.

    2007-10-01

    The AGILE Mission will explore the gamma-ray Universe with a very innovative instrument combining for the first time a gamma-ray imager (sensitive in the range 30 MeV - 50 GeV) and a hard X-ray imager (sensitive in the range 15-45 keV). AGILE will be operational at the beginning of 2007 and it will provide crucial data for the study of Active Galactic Nuclei, Gamma-Ray Bursts, unidentified gamma-ray sources, Galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing.

  5. The Mystery of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2004-01-01

    Gamma-ray bursts remain one of the greatest mysteries in astrophysics. Observations of gamma-ray bursts made by the BATSE experiment on the Compton Gamma-Ray Observatory will be described. Most workers in the field now believe that they originate from cosmological distances. This view has been reinforced by observations this year of several optical afterglow counterparts to gamma-ray bursts. A summary of these recent discoveries will be presented, along with their implications for models of the burst emission mechanism and the energy source of the bursts.

  6. Relative Biological Effectiveness (RBE) of 131I Radiation Relative to 60Co Gamma Rays

    PubMed Central

    Neshasteh-Riz, Ali; Mahmoud Pashazadeh, Ali; Mahdavi, Seyed Rabie

    2013-01-01

    Objective: To assess relative biological effectiveness (RBE) of 131I radiation relative to 60Co gamma rays in glioblastoma spheroid cells. Materials and Methods: : In this experimental study, glioblastoma spheroid cells were exposed to 131I radiation and 60Co gamma rays. Radiation induced DNA damage was evaluated by alkaline comet assay. Samples of spheroid cells were treated by radiation from 131I for four different periods of time to find the dose-response equation. Spheroid cells were also exposed by 200 cGy of 60Co gamma rays as reference radiation to induce DNA damage as endpoint. Results: Resulted RBE of 131I radiation relative to 60Co gamma rays in 100 µm giloblastoma spheroid cells was equal to 1.16. Conclusion: The finding of this study suggests that 131I photons and electrons can be more effective than 60Co gamma rays to produce DNA damage in glioblastoma spheroid cells. PMID:24027663

  7. The status of low-energy gamma-ray astronomy and the Gamma-Ray Observatory

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.

    1985-01-01

    A brief sketch of the objectives and status of the various subdisciplines in gamma-ray astronomy (below 10 GeV) are presented. The Gamma-Ray Observatory planned for launch in 1988 is described. This NASA observatory and several planned French-Soviet spacecraft are expected to elevate gamma-ray astronomy into a mature observational science for the Space Station era.

  8. Nuclear {gamma}-ray superradiance.

    SciTech Connect

    Adams, B. W.; X-Ray Science Division

    2009-01-01

    Nuclear {gamma}-ray-resonant superradiance is discussed, comparing Dicke's original approach 1 and recent extensions 2,3 of Scully et al. 2-52, 3, 4, 5 involving conditional excitation to the classical resonant-scattering 6-106, 7, 8, 9, 10 and the Hannon-Trammell 11-1411, 12, 13, 14 quantum theories. Relevant questions are whether the sample is optically thin or thick in the excitation and re-radiation processes, the role of superpositions between ground and excited states, Fermi's golden rule, and decoherence due to spatially-dependent near-field interactions 15-1715, 16, 17. The relation of these considerations to experimental results is discussed.

  9. Gamma Rays from Classical Novae

    NASA Technical Reports Server (NTRS)

    1997-01-01

    NASA at the University of Chicago, provided support for a program of theoretical research into the nature of the thermonuclear outbursts of the classical novae and their implications for gamma ray astronomy. In particular, problems which have been addressed include the role of convection in the earliest stages of nova runaway, the influence of opacity on the characteristics of novae, and the nucleosynthesis expected to accompany nova outbursts on massive Oxygen-Neon-Magnesium (ONeMg) white dwarfs. In the following report, I will identify several critical projects on which considerable progress has been achieved and provide brief summaries of the results obtained:(1) two dimensional simulation of nova runaway; (2) nucleosynthesis of nova modeling; and (3) a quasi-analytic study of nucleosynthesis in ONeMg novae.

  10. Effects of rotation of fissioning nuclei in the angular distributions of prompt neutrons and gamma rays originating from the polarized-neutron-induced fission of 233U and 235U nuclei

    NASA Astrophysics Data System (ADS)

    Danilyan, G. V.; Klenke, J.; Kopach, Yu. N.; Krakhotin, V. A.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2014-06-01

    The results of an experiment devoted to searches for effects of rotation of fissioning nuclei in the angular distributions of prompt neutrons and gamma rays originating from the polarized-neutron-induced fission of 233U nuclei are presented. The effects discovered in these angular distributions are opposite in sign to their counterparts in the polarized-neutron-induced fission of 235U nuclei. This is at odds with data on the relative signs of respective effects in the angular distribution of alpha particles from the ternary fission of the same nuclei and may be indicative of problems in the model currently used to describe the effect in question. The report on which this article is based was presented at the seminar held at the Institute of Theoretical and Experimental Physics and dedicated to the 90th anniversary of the birth of Yu.G. Abov, corresponding member of Russian Academy of Sciences, Editor in Chief of the journal Physics of Atomic Nuclei.

  11. Gamma rays from hidden millisecond pulsars

    NASA Technical Reports Server (NTRS)

    Tavani, Marco

    1992-01-01

    The properties were studied of a new class of gamma ray sources consisting of millisecond pulsars totally or partially surrounded by evaporating material from irradiated companion stars. Hidden millisecond pulsars offer a unique possibility to study gamma ray, optical and radio emission from vaporizing binaries. The relevance of this class of binaries for GRO observations and interpretation of COS-B data is emphasized.

  12. ASTRONOMY: Neighborhood Gamma Ray Burst Boosts Theory.

    PubMed

    Schilling, G

    2000-07-01

    Titanic explosions that emit powerful flashes of energetic gamma rays are one of astronomy's hottest mysteries. Now an analysis of the nearest gamma ray burst yet detected has added weight to the popular theory that they are expelled during the death throes of supermassive stars. PMID:17832958

  13. Observations of diffuse galactic gamma rays

    NASA Technical Reports Server (NTRS)

    Simpson, G. A.

    1979-01-01

    The observations of galactic diffuse gamma radiation are reviewed. The connections of the gamma ray observations with galactic structure and cosmic rays are discussed. The high latitude galactic component and the low latitude emission from the galactic plane are examined. The observations in other regions of the gamma ray spectrum are discussed.

  14. Gamma rays from extragalactic astrophysical sources

    NASA Astrophysics Data System (ADS)

    Bosch-Ramon, V.

    2011-11-01

    Presently there are several classes of detected gamma-ray extragalactic sources. They are mostly associated to active galactic nuclei (AGN) and (at soft gamma rays) to gamma-ray bursts (GRB), but not only.Active galactic nuclei consist of accreting supermassive black holeshosted by a galaxy that present in some cases powerful relativistic jet activity. Thesesources, which have been studied in gamma rays for several decades, areprobably the most energetic astrophysical objects, and their appearancedepends much on whether their jets point to us. Gamma-ray bursts, thought to be associated to collapsing or merging stellar-mass objects atcosmological distances, are also accreting highly relativistic jet sources that shine strongly at high energies. These are very short-duration events, but they are also the most luminous. Recently, star formation galaxies have turned out to be also gamma-ray emitters.On the other hand, clusters of galaxies have not been detected beyond X-rays yet. These are the largest knownstructures in the Universe; in their formation through accretion andmerging, shocks and turbulence are generated, which may lead to gamma-ray production. In thiswork, the gamma-ray physics of AGNs is briefly presented, as well as that of starburst galaxies, GRBs and clusters of galaxies.Afterwards, we consider some particular cases ofgamma-ray production in non-blazar AGN jets interacting with their medium at different scales.

  15. Gamma-ray Spectral Analysis Algorithm Library

    Energy Science and Technology Software Center (ESTSC)

    1997-09-25

    The routines of the Gauss Algorithm library are used to implement special purpose products that need to analyze gamma-ray spectra from GE semiconductor detectors as a part of their function. These routines provide the ability to calibrate energy, calibrate peakwidth, search for peaks, search for regions, and fit the spectral data in a given region to locate gamma rays.

  16. The space gamma-ray observatory AGILE

    NASA Astrophysics Data System (ADS)

    Morselli, A.; Barbiellini, G.; Budini, G.; Caraveo, P.; Cocco, V.; Costa, E.; Di Cocco, G.; Labanti, C.; Longo, F.; Mereghetti, S.; Pellizzoni, A.; Perotti, F.; Picozza, P.; Prest, M.; Tavani, M.; Vercellone, S.

    2000-05-01

    Gamma-rays of cosmic origin are a manifestation of the most energetic phenomena in our Universe. Many astrophysical sources emit gamma-rays including relativistic compact stars, massive black holes in active galactic nuclei, gamma-ray burst sources, and our Sun during intense flares. The mission AGILE (Astro-rivelatore Gamma a Immagini LEggero) is an innovative, cost effective gamma ray mission selected by the Italian Space Agency (ASI) as first payload of the Program for Small Scientific Missions. It is designed to detect and image gamma-ray sources in the energy range 30 MeV-50 GeV and operate as an Observatory open to the international community. Primary scientific goals include the study of AGN's, gamma ray bursts, Galactic sources, unidentified gamma ray sources, solar flares and diffuse gamma ray emission. AGILE is planned to be operational during the years 2002-2005. It will an ideal `bridge' between EGRET and GLAST, and support space observations and ground based multiwavelength studies of high energy source

  17. Gamma-ray spectral analysis algorithm library

    Energy Science and Technology Software Center (ESTSC)

    2013-05-06

    The routines of the Gauss Algorithms library are used to implement special purpose products that need to analyze gamma-ray spectra from Ge semiconductor detectors as a part of their function. These routines provide the ability to calibrate energy, calibrate peakwidth, search for peaks, search for regions, and fit the spectral data in a given region to locate gamma rays.

  18. Gamma ray emission from radiative supernova remnants

    NASA Astrophysics Data System (ADS)

    Asvarov, Abdul

    In this presentation we have considered Gamma-ray emission from supernova remnants (SNRs) evolving in high density environments, for which the radiative phase of evolution is more typical. Gamma-rays from such objects are believed to have hadronic origin, i.e. as a result of decay of neutral pi-mesons, created in the p-p collisions of relativistic hadrons (protons, etc.) with interstellar medium protons. DSA mechanism is considered as the main mechanism of acceleration of relativistic particles. We assume that SNR evolves in more or less homogeneous interstellar medium. This is contrary to two main models of origin of Gamma-rays from shell type SNRs, which are: 1) Runaway CR model which considers Gamma-ray emission from molecular clouds illuminated by runaway CRs that have escaped from the SNRs; 2) Crushed Cloud model, which considers the shocked interstellar clouds being responsible for the gamma-ray emission of the SNR. The considered model gives the largest conversion rate of SN energy to gamma-rays. It has been found that under certain (close to real) conditions considered here type of SNRs can easily provide the flux of gamma-rays with energies > 100 MeV, typical for the large number of unidentified sources listed in the recent Fermi LAT source catalog. We have obtained conditions under which SNRs are better observable in gamma-rays than in other bands of the electromagnetic spectrum.

  19. A 16N gamma-ray facility

    NASA Astrophysics Data System (ADS)

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

    1997-02-01

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

  20. Instrumentation for gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Bertsch, David L.; Fichtel, Carl E.; Trombka, Jacob I.

    1988-03-01

    The current status of gamma-ray-telescope technology for ground, airborne, and space observations is surveyed and illustrated with drawings, diagrams, and graphs and tables of typical data. For the low- and medium-energy ranges, consideration is given to detectors and detector cooling systems, background-rejection methods, radiation damage, large-area detectors, gamma-ray imaging, data analysis, and the Compton-interaction region. Also discussed are the gamma-ray interaction process at high energies; multilevel automated spark-chamber gamma-ray telescopes; the Soviet Gamma-1 telescope; the EGRET instrument for the NASA Gamma-Ray Observatory; and Cerenkov, air-shower, and particle-detector instruments for the TeV and PeV ranges. Significant improvements in resolution and sensitivity are predicted for the near future.

  1. Instrumentation for gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Bertsch, David L.; Fichtel, Carl E.; Trombka, Jacob I.

    1988-01-01

    The current status of gamma-ray-telescope technology for ground, airborne, and space observations is surveyed and illustrated with drawings, diagrams, and graphs and tables of typical data. For the low- and medium-energy ranges, consideration is given to detectors and detector cooling systems, background-rejection methods, radiation damage, large-area detectors, gamma-ray imaging, data analysis, and the Compton-interaction region. Also discussed are the gamma-ray interaction process at high energies; multilevel automated spark-chamber gamma-ray telescopes; the Soviet Gamma-1 telescope; the EGRET instrument for the NASA Gamma-Ray Observatory; and Cerenkov, air-shower, and particle-detector instruments for the TeV and PeV ranges. Significant improvements in resolution and sensitivity are predicted for the near future.

  2. Future Missions for Gamma-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Meegan, Charles; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Gamma-ray astronomy has made great advances in recent years, due largely to the recently completed 9-year mission of the Compton Gamma Ray Observatory. In this talk I will give an overview of what advances we may expect in the near future, with particular emphasis on earth-orbiting missions scheduled for flight within the next 5 years. Two missions, the High Energy Transient Explorer and Swift, will provide important new information on the sources of gamma-ray bursts. The Gamma-Ray Large Area Space Telescope will investigate high energy emission from a wide variety of sources, including active galaxies and gamma-ray pulsars. The contributions of ground-based and multiwavelength observations will also be addressed.

  3. Atmospheric gamma-ray and neutron flashes

    SciTech Connect

    Babich, L. P. Kudryavtsev, A. Yu. Kudryavtseva, M. L. Kutsyk, I. M.

    2008-01-15

    Gamma-ray pulses are calculated from 2D numerical simulations of an upward atmospheric discharge in a self-consistent electric field using the multigroup approach to the kinetics of relativistic runaway electrons (REs). Computed {gamma}-ray numbers and spectra are consistent with those of terrestrial {gamma}-ray flashes (TGFs) observed aboard spacecrafts. The RE flux is concentrated mainly within the domain of the Blue Jet fluorescence. This confirms that exactly the domain adjacent to a thundercloud is the source of the observed {gamma}-ray flashes. The yield of photonuclear neutrons is calculated. One {gamma}-ray pulse generates {approx}10{sup 14}-10{sup 15} neutrons. The possibility of the direct deposition of REs to the detector readings and the origin of the lightning-advanced TGFs are discussed.

  4. Gamma-Ray Bursts: An Overview

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    1995-01-01

    A history and overview of the observed properties of gamma-ray bursts are presented. The phenomenon of gamma-ray bursts is without precedent in astronomy, having no observed property that would be a direct indicator of their distance and no counterpart object in another wavelength region. Their brief, random appearance only in the gamma-ray region has made their study difficult. The observed time profiles, spectral properties, and durations of gamma-ray bursts cover a wide range. All proposed models for their origin must be considered speculative. It is humbling to think that even after 25 years since their discovery, the distance scale of gamma-ray bursts is still very much debatable.

  5. AGILE: a Gamma-Ray Mission

    NASA Astrophysics Data System (ADS)

    Tavani, M.; Barbiellini, G.; Budini, G.; Caraveo, P.; Costa, E.; Cocco, V.; Di Cocco, G.; di Pippo, S.; Labanti, C.; Longo, F.; Mereghetti, S.; Morselli, A.; Pellizzoni, A.; Perotti, F.; Picozza, P.; Prest, M.; Vacchi, A.; Vercellone, S.

    1999-04-01

    AGILE is an innovative, cost-effective gamma-ray mission proposed to the Italian Space Agengy (ASI) Program for Small Scientific Missions. It is designed to detect and image gamma-rays in the 30 MeV--50 GeV energy band and operate as an Observatory open to the international community. Primary scientific goals include the study of AGNs, gamma-ray bursts, Galactic sources, unidentified gamma-ray sources, solar flares, and diffuse gamma-ray emission. AGILE is planned to be operational during the year 2002 for a 3-year mission. It will an ideal `bridge' between EGRET and GLAST, and support space observations and ground-based multiwavelength studies of high-energy sources.

  6. The space gamma-ray observatory AGILE

    NASA Astrophysics Data System (ADS)

    Morselli, Aldo

    AGILE (Astro-rivelatore Gamma a Immagini LEggero) is an innovative, cost effective gamma ray mission selected by the Italian Space Agency (ASI) as first payload of the Program for Small Scientific Missions. It is designed to detect and image gamma-ray sources in the energy range 30 MeV-50 GeV and operate as an Observatory open to the international community. Primary scientific goals include the study of AGN's, gamma ray bursts, Galactic sources, unidentified gamma ray sources, solar flares and diffuse gamma ray emission. AGILE is planned to be operational during the year 2002 for a 3-year mission. It will an ideal 'bridge' between EGRET and GLAST, and support space observations and ground based multiwavelength studies of high energy sources

  7. Characteristics of gamma-ray line flares

    NASA Technical Reports Server (NTRS)

    Bai, T.; Dennis, B.

    1983-01-01

    Observations of solar gamma rays by the Solar Maximum Mission (SMM) demonstrate that energetic protons and ions are rapidly accelerated during the impulsive phase. To understand the acceleration mechanisms for these particles, the characteristics of the gamma ray line flares observed by SMM were studied. Some very intense hard X-ray flares without detectable gamma ray lines were also investigated. Gamma ray line flares are distinguished from other flares by: (1) intense hard X-ray and microwave emissions; (2) delay of high energy hard X-rays; (3) emission of type 2 and/or type 4 radio bursts; and (4) flat hard X-ray spectra (average power law index: 3.1). The majority of the gamma ray line flares shared all these characteristics, and the remainder shared at least three of them. Positive correlations were found between durations of spike bursts and spatial sizes of flare loops as well as between delay times and durations of spike bursts.

  8. Observation of entrance channel effects in compound nucleus formation with high energy. gamma. -rays

    SciTech Connect

    Thoennessen, M.; Beene, J.R.; Auble, R.L.; Bertrand, F.E.; Baktash, C.; Halbert, M.L.; Horen, D.J.; Ludemann, C.A. ); Sarantites, D.G.; Stracener, D.W. ); Spang, W. )

    1990-01-01

    We investigated entrance channel effects in the decay of excited {sup 160}Er and {sup 164}Yb, formed with {sup 16}O and {sup 64}Ni beams by measuring high energy (5--25 MeV) {gamma}-ray spectra. Gamma rays from the decay of the giant dipole resonance (GDR) built on highly excited states provide a good probe to study these effects, since the {gamma} rays are emitted in the early stages of the reaction. The {gamma}-ray spectra measured in the {sup 16}O-induced reactions show the typical GDR bump whereas the {gamma}-ray spectra from the more symmetric entrance channels show dramatically different shape. 22 refs., 5 figs., 2 tabs.

  9. Simulation fidelity issues when using gamma-ray simulators for tree testing

    SciTech Connect

    Hartman, E.F.; Browning, J.S.; Drumm, C.R. )

    1990-12-01

    Factors that influence the fidelity of gamma-ray TREE testing have been investigated. Specifically, package-induced dose enhancement in 256 K CMOS SRAMs and dose enhancement from finite-range electrons produced (by gamma-ray interactions) in materials external to the SRAM packages have been studied. Two gamma-ray simulators with significantly different spectra were used in the studies. The spectral differences produced less change in SRAM upset levels than did surrounding materials of equal mass density but differing atomic number. The implication for gamma-ray simulation testing is that individual devices within electronic systems may respond quite differently in gamma-ray TREE testing because of the structural materials within the system than when tests are performed on these individual devices without the system present.

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

    NASA Astrophysics Data System (ADS)

    Prettyman, T.

    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 neutrons and by neutron capture. The production of neutron-induced gamma rays reaches a maximum deep below the surface (e.g. approximately 140g/cm2 for inelastic scattering and approximately 50 g/cm2 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 on order to determine the contribution of individual elements.

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

    SciTech Connect

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

    2001-01-01

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

  12. Modeling gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Maxham, Amanda

    Discovered serendipitously in the late 1960s, gamma-ray bursts (GRBs) are huge explosions of energy that happen at cosmological distances. They provide a grand physical playground to those who study them, from relativistic effects such as beaming, jets, shocks and blastwaves to radiation mechanisms such as synchrotron radiation to galatic and stellar populations and history. Through the Swift and Fermi space telescopes dedicated to observing GRBs over a wide range of energies (from keV to GeV), combined with accurate pinpointing that allows ground based follow-up observations in the optical, infrared and radio, a rich tapestry of GRB observations has emerged. The general picture is of a mysterious central engine (CE) probably composed of a black hole or neutron star that ejects relativistic shells of matter into intense magnetic fields. These shells collide and combine, releasing energy in "internal shocks" accounting for the prompt emission and flaring we see and the "external shock" or plowing of the first blastwave into the ambient surrounding medium has well-explained the afterglow radiation. We have developed a shell model code to address the question of how X-ray flares are produced within the framework of the internal shock model. The shell model creates randomized GRB explosions from a central engine with multiple shells and follows those shells as they collide, merge and spread, producing prompt emission and X-ray flares. We have also included a blastwave model, which can constrain X-ray flares and explain the origin of high energy (GeV) emission seen by the Fermi telescope. Evidence suggests that gamma-ray prompt emission and X-ray flares share a common origin and that at least some flares can only be explained by long-lasting central engine activity. We pay special attention to the time history of central engine activity, internal shocks, and observed flares. We calculate the gamma-ray (Swift/BAT band) and X-ray (Swift/XRT band) lightcurves for arbitrary central engine activity and compare the model results with the observational data. We show that the observed X-ray flare phenomenology can be explained within the internal shock model. The number, width and occurring time of flares are then used to diagnose the central engine activity, putting constraints on the energy, ejection time, width and number of ejected shells. We find that the observed X-ray flare time history generally reflects the time history of the central engine, which reactivates multiple times after the prompt emission phase with progressively reduced energy. This shell model code can be used to constrain broadband observations of GRB 090926A, which showed two flares in both the Swift UVOT and XRT bands. Using the prompt emission fluence to constrain the total energy contained in the blastwave, the internal shock model requires that Lorentz factors of the shells causing flares must be less than the Lorentz factor of the blastwave when the shells are ejected. Recent observations of Gamma-Ray Bursts (GRBs) by the Fermi Large Area Telescope (LAT) revealed a power law decay feature of the high energy emission (above 100 MeV), which led to the suggestion that it originates from an external shock. We analyze four GRBs (080916C, 090510, 090902B and 090926A) jointly detected by Fermi LAT and Gamma-ray Burst Monitor (GBM), which have high quality lightcurves in both instrument energy bands. Using the MeV prompt emission (GBM) data, we can record the energy output from the central engine as a function of time. Assuming a constant radiative efficiency, we are able to track energy accumulation in the external shock using our internal/external shell model code and show that the late time lightcurves fit well within the external shock model, but the early time lightcurves are dominated by the internal shock component which has a shallow decay phase due to the initial pile-up of shells onto the blast wave.

  13. Software tool for xenon gamma-ray spectrometer control

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  15. Gamma-ray Astronomy and GLAST

    NASA Technical Reports Server (NTRS)

    McEnery, Julie

    2007-01-01

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

  16. Future prospects for gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Fichtel, C.

    1981-01-01

    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.

  17. Observations of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.

    1995-01-01

    Some basic observed properties of gamma-ray bursts are reviewed. Although some properties were known 25 years ago, new and more detailed observations have been made by the Compton Observatory in the past three years. The new observation with the greatest impact has been the observed isotropic distribution of bursts along with a deficiency of weak bursts which would be expected from a homogeneous burst distribution. This is not compatible with any known Galactic population of objects. Gamma-ray bursts show an enormous variety of burst morphologies and a wide spread in burst durations. The spectra of gamma-ray bursts are characterized by rapid variations and peak power which is almost entirely in the gamma-ray energy range. Delayed gamma-ray burst photons extending to GeV energies have been detected for the first time. A time dilation effect has also been reported to be observed in gamma-ray, bursts. The observation of a gamma-ray burst counterpart in another wavelength region has yet to be made.

  18. Gamma-Ray Burst Physics with GLAST

    SciTech Connect

    Omodei, N.; /INFN, Pisa

    2006-10-06

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

  19. Detecting axionlike particles with gamma ray telescopes.

    PubMed

    Hooper, Dan; Serpico, Pasquale D

    2007-12-01

    We propose that axionlike particles (ALPs) with a two-photon vertex, consistent with all astrophysical and laboratory bounds, may lead to a detectable signature in the spectra of high-energy gamma-ray sources. This occurs as a result of gamma rays being converted into ALPs in the magnetic fields of efficient astrophysical accelerators according to the "Hillas criterion", such as jets of active galactic nuclei or hot spots of radio galaxies. The discovery of such an effect is possible by GLAST in the 1-100 GeV range and by ground-based gamma-ray telescopes in the TeV range. PMID:18233353

  20. Cosmic gamma-ray lines - Theory

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.; Ramaty, R.

    1980-01-01

    The various processes that lead to gamma-ray line emission and the possible astrophysical sources of such emission are reviewed. The processes of nuclear excitation, radiative capture, positron annihilation, and cyclotron radiation, which may produce gamma-ray line emission from such diverse sources as the interstellar medium, novas, supernovas, pulsars, accreting compact objects, the galactic nucleus and the nuclei of active galaxies are considered. The significance of the relative intensities, widths, and frequency shifts of the lines are also discussed. Particular emphasis is placed on understanding those gamma-ray lines that have already been observed from astrophysical sources.

  1. NEAR Gamma Ray Spectrometer Characterization and Repair

    NASA Technical Reports Server (NTRS)

    Groves, Joel Lee; Vajda, Stefan

    1998-01-01

    This report covers the work completed in the third year of the contract. The principle activities during this period were (1) the characterization of the NEAR 2 Gamma Ray Spectrometer using a neutron generator to generate complex gamma ray spectra and a large Ge Detecter to identify all the major peaks in the spectra; (2) the evaluation and repair of the Engineering Model Unit of the Gamma Ray Spectrometer for the NEAR mission; (3) the investigation of polycapillary x-ray optics for x-ray detection; and (4) technology transfer from NASA to forensic science.

  2. IR observations in gamma-ray blazars

    NASA Technical Reports Server (NTRS)

    Mahoney, W. A.; Gautier, T. N.; Ressler, M. E.; Wallyn, P.; Durouchoux, P.; Higdon, J. C.

    1997-01-01

    The infrared photometric and spectral observation of five gamma ray blazars in coordination with the energetic gamma ray experiment telescope (EGRET) onboard the Compton Gamma Ray Observatory is reported. The infrared measurements were made with a Cassegrain infrared camera and the mid-infrared large well imager at the Mt. Palomar 5 m telescope. The emphasis is on the three blazars observed simultaneously by EGRET and the ground-based telescope during viewing period 519. In addition to the acquisition of broadband spectral measurements for direct correlation with the 100 MeV EGRET observations, near infrared images were obtained, enabling a search for intra-day variability to be carried out.

  3. Fermi Gamma-Ray Space Telescope

    NASA Technical Reports Server (NTRS)

    McEnery, Julie E.; Michelson, Peter F.; Paclesas, William S.; Ritz, Steven

    2012-01-01

    The Fermi Gamma-ray Space Telescope, launched in June 2008, is an observatory designed to survey the high-energy gamma-ray sky. The primary instrument, the Large Area Telescope (LAT), provides observations from 20 MeV to greater than 300 GeV. A second instrument, the Gamma-ray Burst Monitor (GBM), provides observations of transients from less than 10 keV to 40 MeV. We describe the design and performance of the instruments and their subsystems, the spacecraft and the ground system.

  4. Gamma-ray burst cosmology

    NASA Astrophysics Data System (ADS)

    Wang, F. Y.; Dai, Z. G.; Liang, E. W.

    2015-08-01

    Gamma-ray bursts (GRBs) are the most luminous electromagnetic explosions in the Universe, which emit up to 8.8 × 1054 erg isotropic equivalent energy in the hard X-ray band. The high luminosity makes them detectable out to the largest distances yet explored in the Universe. GRBs, as bright beacons in the deep Universe, would be the ideal tool to probe the properties of high-redshift universe: including the cosmic expansion and dark energy, star formation rate, the reionization epoch and the metal enrichment history of the Universe. In this article, we review the luminosity correlations of GRBs, and implications for constraining the cosmological parameters and dark energy. Observations show that the progenitors of long GRBs are massive stars. So it is expected that long GRBs are tracers of star formation rate. We also review the high-redshift star formation rate derived from GRBs, and implications for the cosmic reionization history. The afterglows of GRBs generally have broken power-law spectra, so it is possible to extract intergalactic medium (IGM) absorption features. We also present the capability of high-redshift GRBs to probe the pre-galactic metal enrichment and the first stars.

  5. T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

    SciTech Connect

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Kopach, Yu. N.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2011-05-15

    Study of the T-odd three-vector correlation in the emission of prompt neutrons from {sup 235}U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University of Munich). The sought correlation was not found within experimental error of 2.3 Multiplication-Sign 10{sup -5}. The upper limit for the asymmetry coefficient has been set to vertical bar D{sub n} vertical bar < 6 Multiplication-Sign 10{sup -5} at 99% confidence level, whereas for ternary fission correlation coefficient D{sub {alpha}} = (170{+-}20) Multiplication-Sign 10{sup -5}. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism. At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5 Degree-Sign to the fission axis, the correlation coefficient was found to be (1.57 {+-} 0.20) Multiplication-Sign 10{sup -4}, while at the angle of 67.5 Degree-Sign it is zero within the experimental uncertainty. The existence of ROT effect in the emission of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT effect in the emission of prompt {gamma}-rays.

  6. High-energy gamma rays from the intense 1993 January 31 gamma-ray burst

    NASA Technical Reports Server (NTRS)

    Sommer, M.; Bertsch, D. L.; Dingus, B. L.; Fichtel, C. E.; Fishman, G. J.; Harding, A. K.; Hartman, R. C.; Hunter, S. D.; Hurley, K.; Kanbach, G.

    1994-01-01

    The intense gamma-ray burst of 1993 January 31 was detected by the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Observatory. Sixteen gamma rays above 30 MeV were imaged in the telescope when only 0.04 gamma rays were expected by chance. Two of these gamma rays have energies of approximately 1 GeV, and the five bin spectrum of the 16 events is fitted by a power law of photon spectral index -2.0 +/- 0.4. The high-energy emission extends for at least 25 s. The most probable direction for this burst is determined from the directions of the 16 gamma rays observed by Egret and also by requiring the position to lie on annulus derived by the Interplanetary Network.

  7. Thermal neutron capture gamma-rays

    SciTech Connect

    Tuli, J.K.

    1983-01-01

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

  8. Neutron Detection Gamma Ray Sensitivity Criteria

    SciTech Connect

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

    2011-10-21

    The shortage of 3He 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 ratio GARRn is defined, and it is proposed that the requirement for neutron detection be 0.9 < GARRn < 1.1 at a 10 mR/h exposure rate. An example of results from a 3He based neutron detector are provided showing that this technology can meet the stated requirements. Results from tests of some alternative technologies are also reported.

  9. Gamma-Ray Pulsar Studies With GLAST

    SciTech Connect

    Thompson, D.J.; /NASA, Goddard

    2011-11-23

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

  10. POPULATION SYNTHESIS AND GAMMA RAY BURST PROGENITORS

    SciTech Connect

    C. L. FREYER

    2000-12-11

    Population synthesis studies of binaries are always limited by a myriad of uncertainties from the poorly understood effects of binary mass transfer and common envelope evolution to the many uncertainties that still remain in stellar evolution. But the importance of these uncertainties depends both upon the objects being studied and the questions asked about these objects. Here I review the most critical uncertainties in the population synthesis of gamma-ray burst progenitors. With a better understanding of these uncertainties, binary population synthesis can become a powerful tool in understanding, and constraining, gamma-ray burst models. In turn, as gamma-ray bursts become more important as cosmological probes, binary population synthesis of gamma-ray burst progenitors becomes an important tool in cosmology.

  11. Gamma-Ray Pulsar Studies with GLAST

    SciTech Connect

    Thompson, D. J.

    2008-02-27

    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.

  12. Supernovae and gamma-ray bursts connection

    NASA Astrophysics Data System (ADS)

    Valle, Massimo Della

    2015-12-01

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

  13. Gamma-ray constraints on supernova nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Leising, Mark D.

    1994-01-01

    Gamma-ray spectroscopy holds great promise for probing nucleosynthesis in individual supernova explosions via short-lived radioactivity, and for measuring current global Galactic supernova nucleosynthesis with longer-lived radioactivity. It was somewhat surprising that the former case was realized first for a Type II supernova, when both Co-56 and Co-57 were detected in SN 1987A. These provide unprecedented constraints on models of Type II explosions and nucleosynthesis. Live Al-26 in the Galaxy might come from Type II supernovae, and if it is eventually shown to be so, can constrain massive star evolution, supernova nucleosynthesis, and the Galactic Type II supernova rate. Type Ia supernovae, thought to be thermonuclear explosions, have not yet been detected in gamma-rays. This is somewhat surprising given current models and recent Co-56 detection attempts. Ultimately, gamma-ray measurements can confirm their thermonuclear nature, probe the nuclear burning conditions, and help evaluate their contributions to Galactic nucleosynthesis. Type Ib/c supernovae are poorly understood. Whether they are core collapse or thermonuclear events might be ultimately settled by gamma-ray observations. Depending on details of the nuclear processing, any of these supernova types might contribute to a detectable diffuse glow of Fe-60 gamma-ray lines. Previous attempts at detection have come very close to expected emission levels. Remnants of any type of age less that a few centuries might be detectable as individual spots of Ti-44 gamma-ray line emission. It is in fact quite surprising that previous surveys have not discovered such spots, and the constraints on the combination of nucleosynthesis yields and supernova rates are very interesting. All of these interesting limits and possibilities mean that the next mission, International Gamma-Ray Astrophysics Laboratory (INTEGRAL), if it has sufficient sensitivity, is very likely to lead to the realization of much of the great potential of gamma-ray spectroscopy for understanding supernovae.

  14. Research in cosmic and gamma ray astrophysics

    NASA Technical Reports Server (NTRS)

    Stone, E. C.; Davis, L., Jr.; Mewaldt, R. A.; Prince, T. A.

    1989-01-01

    Research activities in cosmic rays, gamma rays, and astrophysical plasmas are covered. The activities are divided into sections and described, followed by a bibliography. The astrophysical aspects of cosmic rays, gamma rays, and of the radiation and electromagnetic field environment of the Earth and other planets are investigated. These investigations are performed by means of energetic particle and photon detector systems flown on spacecraft and balloons.

  15. The Mystery of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    1998-01-01

    Gamma-ray bursts remain on of the greatest mysteries in astrophysics in spite of recent observational advances and intense theoretical work. Although some of the basic properties of bursts were known 25 years ago, new and more detailed observations have been made by the BATSE (Burst and Transient Source Experiment) experiment on the Compton Gamma Ray Observatory in the past five years. Recent observations of bursts and some proposed models will be discussed.

  16. Gamma-ray binaries and related systems

    NASA Astrophysics Data System (ADS)

    Dubus, Guillaume

    2013-08-01

    After initial claims and a long hiatus, it is now established that several binary stars emit high- (0.1-100 GeV) and very high-energy (>100 GeV) gamma rays. A new class has emerged called "gamma-ray binaries", since most of their radiated power is emitted beyond 1 MeV. Accreting X-ray binaries, novae and a colliding wind binary ( η Car) have also been detected—"related systems" that confirm the ubiquity of particle acceleration in astrophysical sources. Do these systems have anything in common? What drives their high-energy emission? How do the processes involved compare to those in other sources of gamma rays: pulsars, active galactic nuclei, supernova remnants? I review the wealth of observational and theoretical work that have followed these detections, with an emphasis on gamma-ray binaries. I present the current evidence that gamma-ray binaries are driven by rotation-powered pulsars. Binaries are laboratories giving access to different vantage points or physical conditions on a regular timescale as the components revolve on their orbit. I explain the basic ingredients that models of gamma-ray binaries use, the challenges that they currently face, and how they can bring insights into the physics of pulsars. I discuss how gamma-ray emission from microquasars provides a window into the connection between accretion-ejection and acceleration, while η Car and novae raise new questions on the physics of these objects—or on the theory of diffusive shock acceleration. Indeed, explaining the gamma-ray emission from binaries strains our theories of high-energy astrophysical processes, by testing them on scales and in environments that were generally not foreseen, and this is how these detections are most valuable.

  17. Extreme energy gamma rays and neutrinos and their observation in JEM-EUSO Mission

    SciTech Connect

    Shinozaki, K.

    2010-06-01

    The origin of the extreme energy cosmic rays (EECRs) is a mystery in the contemporary astrophysics. The JEM-EUSO Mission that mainly aims establishing astronomy using such EECRs with very high statistics will also have realistic capability of detecting gamma rays and neutrinos with approx10{sup 20} eV energies. Aboard the International Space Station, the JEM-EUSO mission also provides a unique platform to detect and study the air showers from extreme energy gamma rays and neutrinos. In the present paper, we discuss a part of results from our study on properties of gamma ray and neutrino induced air showers and the advantage for space-based observation.

  18. First search for neutrinos in correlation with gamma-ray bursts with the ANTARES neutrino telescope

    SciTech Connect

    2013-03-01

    A search for neutrino-induced muons in correlation with a selection of 40 gamma-ray bursts that occurred in 2007 has been performed with the ANTARES neutrino telescope. During that period, the detector consisted of 5 detection lines. The ANTARES neutrino telescope is sensitive to TeV–PeV neutrinos that are predicted from gamma-ray bursts. No events were found in correlation with the prompt photon emission of the gamma-ray bursts and upper limits have been placed on the flux and fluence of neutrinos for different models.

  19. Gamma-ray Albedo of the Moon

    SciTech Connect

    Moskalenko, Igor V.; Porter, Troy A.

    2007-06-14

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

  20. VLF Remote -Sensing of the Lower Ionosphere with AWESOME Receivers: Solar Flares, Lightning-induced Electron Precipitation, Sudden Ionospheric Disturbances, Sprites, Gravity Waves and Gamma-ray Flares

    NASA Astrophysics Data System (ADS)

    Inan, U. S.; Cohen, M.; Scherrer, P.; Scherrer, D.

    2006-11-01

    Stanford University Very Low Frequency (VLF) radio receivers have been used extensively for remote sensing of the ionosphere and the magnetosphere. Among the phenomena that can be uniquely measured via VLF receivers are radio atmospherics, whistlers, electron precipitation, solar flares, sudden ionospheric disturbances, gravity waves, sprites, and cosmic gamma-ray flares. With the use of simple square air-core magnetic loop antennas of a couple of meters in size, the sensitivity of these instruments allows the measurement of magnetic fields as low as several tens of femtoTesla per root Hz, in the frequency range of ~300 Hz to 50 kHz. This sensitivity well exceeds that required to detect any event above the ambient atmospheric noise floor, determined by the totality of lightning activity on this planet. In recent years, as cost of production, timing accuracy (due to low cost GPS cards), and data handling flexibility of the systems has improved, it has become possible to distribute many of these instruments in the form of arrays, to perform interferometric and holographic imaging of the lower ionosphere. These goals can be achieved using the newest version of the Stanford VLF receiver, known as AWESOME: Atmospheric Weather Educational System for Observation and Modeling of Electromagnetics. In the context of the IHY/UNBSS program for 2007, the AWESOME receivers can be used extensively as part of the United Nations initiative to place scientific instruments in developing countries. Drawing on the Stanford experiences from setting up arrays of VLF receivers, including an interferometer in Alaska, the Holographic Array for Ionospheric and Lightning research (HAIL) consisting of instruments at 13 different high schools in mid-western United States, a broader set of ELF/VLF receivers in Alaska, and various receivers abroad, including in France, Japan, Greece, Turkey, and India, a global network of ELF/VLF receivers offer possibilities for a wide range of scientific topics, as well as serving as a means for educational outreach. Most recently, AWESOME receivers were placed in several North African countries, including Tunisia, Algeria, and Morocco. The new AWESOME version is substantially lower in cost, and easier to set-up and use. Nevertheless, the receivers offer the same ultimate levels of resolution in time, sensitivity and dynamic range, as well as ease of handling of data that is used by researchers conducting cutting edge ionospheric and Space Weather research. In this context, the placement of these systems at underdeveloped host countries provides an open-ended potential for exploration, limited only by the imagination and drive of the users.

  1. Supernovae and Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Panagia, Nino; Sahu, Kailash

    2001-07-01

    Participants; Preface; Gamma-ray burst-supernova relation B. Paczynski; Observations of gamma-ray bursts G. Fishman; Fireballs T. Piran; Gamma-ray mechanisms M. Rees; Prompt optical emission from gamma-ray bursts R. Kehoe, C. Akerlof, R. Balsano, S. Barthelmy, J. Bloch, P. Butterworth, D. Casperson, T. Cline, S. Fletcher, F. Frontera, G. Gisler, J. Heise, J. Hills, K. Hurley, B. Lee, S. Marshall, T. McKay, A. Pawl, L. Piro, B. Priedhorsky, J. Szymanski and J. Wren; X-ray afterglows of gamma-ray bursts L. Piro; The first year of optical-IR observations of SN1998bw I. Danziger, T. Augusteijn, J. Brewer, E. Cappellaro, V. Doublier, T. Galama, J. Gonzalez, O. Hainaut, B. Leibundgut, C. Lidman, P. Mazzali, K. Nomoto, F. Patat, J. Spyromilio, M. Turatto, J. Van Paradijs, P. Vreeswijk and J. Walsh; X-ray emission of Supernova 1998bw in the error box of GRB980425 E. Pian; Direct analysis of spectra of type Ic supernovae D. Branch; The interaction of supernovae and gamma-ray bursts with their surroundings R. Chevalier; Magnetars, soft gamma-ray repeaters and gamma-ray bursts A. Harding; Super-luminous supernova remnants Y. -H. Chu, C. -H. Chen and S. -P. Lai; The properties of hypernovae: SNe Ic 1998bw, 1997ef, and SN IIn 1997cy K. Nomoto, P. Mazzali, T. Nakamura, K. Iwanmoto, K. Maeda, T. Suzuki, M. Turatto, I. Danziger and F. Patat; Collapsars, Gamma-Ray Bursts, and Supernovae S. Woosley, A. MacFadyen and A. Heger; Pre-supernova evolution of massive stars N. Panagia and G. Bono; Radio supernovae and GRB 980425 K. Weiler, N. Panagia, R. Sramek, S. Van Dyk, M. Montes and C. Lacey; Models for Ia supernovae and evolutionary effects P. Hoflich and I. Dominguez; Deflagration to detonation A. Khokhlov; Universality in SN Iae and the Phillips relation D. Arnett; Abundances from supernovae F. -K. Thielemann, F. Brachwitz, C. Freiburghaus, S. Rosswog, K. Iwamoto, T. Nakamura, K. Nomoto, H. Umeda, K. Langanke, G. Martinez-Pinedo, D. Dean, W. Hix and M. Strayer; Sne, GRBs, and the global properties of the Universe B. Schmidt; How good are SNe Ia as standard candles? A. Sandage, G. Tammann and A. Saha; Type Ia supernovae and their implications for cosmology M. Livio; Conference summary: supernovae and gamma-ray bursts J. Wheeler.

  2. Gamma ray astrophysics to the year 2000. Report of the NASA Gamma Ray Program Working Group

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Important developments in gamma-ray astrophysics up to energies of 100 GeV during the last decade are reviewed. Also, the report seeks to define the major current scientific goals of the field and proposes a vigorous program to pursue them, extending to the year 2000. The goals of gamma-ray astronomy include the study of gamma rays which provide the most direct means of studying many important problems in high energy astrophysics including explosive nucleosynthesis, accelerated particle interactions and sources, and high-energy processes around compact objects. The current research program in gamma-ray astronomy in the U.S. including the space program, balloon program and foreign programs in gamma-ray astronomy is described. The high priority recommendations for future study include an Explorer-class high resolution gamma-ray spectroscopy mission and a Get Away Special cannister (GAS-can) or Scout class multiwavelength experiment for the study of gamma-ray bursts. Continuing programs include an extended Gamma Ray Observatory mission, continuation of the vigorous program of balloon observations of the nearby Supernova 1987A, augmentation of the balloon program to provide for new instruments and rapid scientific results, and continuation of support for theoretical research. Long term recommendations include new space missions using advanced detectors to better study gamma-ray sources, the development of these detectors, continued study for the assembly of large detectors in space, collaboration with the gamma-ray astronomy missions initiated by other countries, and consideration of the Space Station attached payloads for gamma-ray experiments.

  3. Mercuric iodine room temperature gamma-ray detectors

    NASA Technical Reports Server (NTRS)

    Patt, Bradley E.; Markakis, Jeffrey M.; Gerrish, Vernon M.; Haymes, Robert C.; Trombka, Jacob I.

    1990-01-01

    high resolution mercuric iodide room temperature gamma-ray detectors have excellent potential as an essential component of space instruments to be used for high energy astrophysics. Mercuric iodide detectors are being developed both as photodetectors used in combination with scintillation crystals to detect gamma-rays, and as direct gamma-ray detectors. These detectors are highly radiation damage resistant. The list of applications includes gamma-ray burst detection, gamma-ray line astronomy, solar flare studies, and elemental analysis.

  4. New insights from cosmic gamma rays

    NASA Astrophysics Data System (ADS)

    Roland, Diehl

    2016-04-01

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

  5. Gamma-ray spectrometry of LDEF samples

    SciTech Connect

    Winn, W.G.

    1991-01-01

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

  6. Gamma-ray spectrometry of LDEF samples

    SciTech Connect

    Winn, W.G.

    1991-12-31

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

  7. Radiation-induced mutation at minisatellite loci

    SciTech Connect

    Dubrova, Y.E. |; Nesterov, V.N.; Krouchinsky, N.G.

    1997-10-01

    We are studying the radiation-induced increase of mutation rate in minisatellite loci in mice and humans. Minisatellite mutations were scored by multilocus DNA fingerprint analysis in the progeny of {gamma}-irradiated and non-irradiated mice. The frequency of mutation in offspring of irradiated males was 1.7 higher that in the control group. Germline mutation at human minisatellite loci was studied among children born in heavily polluted areas of the Mogilev district of Belarus after the Chernobyl accident and in a control population. The frequency of mutation assayed both by DNA fingerprinting and by eight single locus probes was found to be two times higher in the exposed families than in the control group. Furthermore, mutation rate was correlated with the parental radiation dose for chronic exposure {sup 137}Cs, consistent with radiation-induction of germline mutation. The potential use of minisatellites in monitoring germline mutation in humans will be discussed.

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

    SciTech Connect

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

    2009-03-10

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

  9. The GAMMA-400 gamma-ray telescope for precision gamma-ray emission investigations

    NASA Astrophysics Data System (ADS)

    Topchiev, N. P.; Galper, A. M.; Bonvicini, V.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Bakaldin, A. V.; Bergstrom, L.; Berti, E.; Bigongiari, G.; Bobkov, S. G.; Boezio, M.; Bogomolov, E. A.; Bonechi, L.; Bongi, M.; Bottai, S.; Castellini, G.; Cattaneo, P. W.; Cumani, P.; Dalkarov, O. D.; Dedenko, G. L.; De Donato, C.; Dogiel, V. A.; Finetti, N.; Gascon, D.; Gorbunov, M. S.; Gusakov, Yu V.; Hnatyk, B. I.; Kadilin, V. V.; Kaplin, V. A.; Kaplun, A. A.; Kheymits, M. D.; Korepanov, V. E.; Larsson, J.; Leonov, A. A.; Loginov, V. A.; Longo, F.; Maestro, P.; Marrocchesi, P. S.; Martinez, M.; Men'shenin, A. L.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu; Papini, P.; Paredes, J. M.; Pearce, M.; Picozza, P.; Rappoldi, A.; Ricciarini, S.; Runtso, M. F.; Ryde, F.; Serdin, O. V.; Sparvoli, R.; Spillantini, P.; Stozhkov, Yu I.; Suchkov, S. I.; Taraskin, A. A.; Tavani, M.; Tiberio, A.; Tyurin, E. M.; Ulanov, M. V.; Vacchi, A.; Vannuccini, E.; Vasilyev, G. I.; Ward, J. E.; Yurkin, Yu T.; Zampa, N.; Zirakashvili, V. N.; Zverev, V. G.

    2016-02-01

    The GAMMA-400 gamma-ray telescope with excellent angular and energy resolutions is designed to search for signatures of dark matter in the fluxes of gamma-ray emission and electrons + positrons. Precision investigations of gamma-ray emission from Galactic Center, Crab, Vela, Cygnus, Geminga, and other regions will be performed, as well as diffuse gamma-ray emission, along with measurements of high-energy electron + positron and nuclei fluxes. Furthermore, it will study gamma-ray bursts and gamma-ray emission from the Sun during periods of solar activity. The GAMMA-400 energy range is expected to be from ∼20 MeV up to TeV energies for gamma rays, up to 10 TeV for electrons + positrons, and up to 1015 eV for cosmic-ray nuclei. For 100-GeV gamma rays, the GAMMA-400 angular resolution is ∼0.01° and energy resolution is ∼1% the proton rejection factor is ∼5x105. GAMMA-400 will be installed onboard the Russian space observatory.

  10. Determination of the gamma-ray spectrum in a strong neutron/gamma-ray mixed field

    NASA Astrophysics Data System (ADS)

    Liu, Yuan-Hao; Lin, Yi-Chun; Nievaart, Sander; Chou, Wen-Tsae; Liu, Hong-Ming; Jiang, Shiang-Huei

    2011-10-01

    The knowledge of gamma-ray spectrum highly affects the accuracy of the correspondingly derived gamma-ray dose and the correctness of calculated neutron dose in the neutron/gamma-ray mixed field dosimetry when using the paired ionization chambers technique. It is of our interest to develop a method to determine the gamma-ray spectrum in a strong neutron/gamma-ray mixed field. The current type detector, Mg(Ar) ionization chamber with 6 different thick caps incorporated with the unfolding technique, was used to determine the gamma-ray spectrum in the THOR epithermal neutron beam, which contains intense neutrons and gamma rays. The applied caps had nominal thicknesses from 1 to 6 mm. Detector response functions of the applied Mg(Ar) chamber with different caps were calculated using MCNP5 with a validated chamber model. The spectrum unfolding process was performed using the well-known SAND-II algorithm. The unfolded result was found much softer than the originally calculated spectrum at the design stage. A large portion of low energy continuum was shown in the adjusted spectrum. This work gave us a much deeper insight into the THOR epithermal neutron beam and also showed a way to determine the gamma-ray spectrum.

  11. Gamma-ray Emission from Nova Outbursts

    NASA Astrophysics Data System (ADS)

    Hernanz, M.

    2014-12-01

    Classical novae produce radioactive nuclei which are emitters of gamma-rays in the MeV range. Some examples are the lines at 478 and 1275 keV (from 7Be and 22Na) and the positron-electron annihilation emission, with the 511 keV line and a continuum. Gamma-ray spectra and light curves are potential unique tools to trace the corresponding isotopes and to give insights on the properties of the expanding envelope. Another possible origin of gamma-rays is the acceleration of particles up to very high energies, so that either neutral pions or inverse Compton processes produce gamma-rays of energies larger than 100 MeV. MeV photons during nova explosions have not been detected yet, although several attempts have been made in the last decades; on the other hand, GeV photons from novae have been detected with the Fermi satellite in V407 Cyg, a nova in a symbiotic binary, where the companion is a red giant with a wind, instead of a main sequence star as in the cataclysmic variables hosting classical novae. Two more novae have been detected recently (summer 2012) by Fermi, apparently in non symbiotic binaries, thus challenging our understanding of the emission mechanism. Both scenarios (radioactivities and acceleration) of gamma-ray production in novae are discussed.

  12. Stellar Photon Archaeology with Gamma-Rays

    NASA Technical Reports Server (NTRS)

    Stecker, Floyd W.

    2009-01-01

    Ongoing deep surveys of galaxy luminosity distribution functions, spectral energy distributions and backwards evolution models of star formation rates can be used to calculate the past history of intergalactic photon densities and, from them, the present and past optical depth of the Universe to gamma-rays from pair production interactions with these photons. The energy-redshift dependence of the optical depth of the Universe to gamma-rays has become known as the Fazio-Stecker relation (Fazio & Stecker 1970). Stecker, Malkan & Scully have calculated the densities of intergalactic background light (IBL) photons of energies from 0.03 eV to the Lyman limit at 13.6 eV and for 0$ < z < $6, using deep survey galaxy observations from Spitzer, Hubble and GALEX and have consequently predicted spectral absorption features for extragalactic gamma-ray sources. This procedure can also be reversed. Determining the cutoff energies of gamma-ray sources with known redshifts using the recently launched Fermi gamma-ray space telescope may enable a more precise determination of the IBL photon densities in the past, i.e., the "archaeo-IBL.", and therefore allow a better measure of the past history of the total star formation rate, including that from galaxies too faint to be observed.

  13. Gamma-ray limits on neutrino lines

    NASA Astrophysics Data System (ADS)

    Queiroz, Farinaldo S.; Yaguna, Carlos E.; Weniger, Christoph

    2016-05-01

    Monochromatic neutrinos from dark matter annihilations (χχ→ νbar nu) are always produced in association with a gamma-ray spectrum generated by electroweak bremsstrahlung. Consequently, these neutrino lines can be searched for not only with neutrino detectors but also indirectly with gamma-ray telescopes. Here, we derive limits on the dark matter annihilation cross section into neutrinos based on recent Fermi-LAT and HESS data. We find that, for dark matter masses above 200 GeV, gamma-ray data actually set the most stringent constraints on neutrino lines from dark matter annihilation and, therefore, an upper bound on the dark matter total annihilation cross section. In addition, we point out that gamma-ray telescopes, unlike neutrino detectors, have the potential to distinguish the flavor of the final state neutrino. Our results indicate that we have already entered into a new era where gamma-ray telescopes are more sensitive than neutrino detectors to neutrino lines from dark matter annihilation.

  14. The Pulsing Gamma-ray Sky

    NASA Astrophysics Data System (ADS)

    Romani, Roger W.

    2014-01-01

    The Fermi Space Telescope, with its discovery of nearly 150 gamma-ray pulsars has solidified and extended the suspicions of the EGRET era: energetic spin-powered pulsars are fantastic particle accelerators, they emit most of their photon energy in the GeV range and they paint their gamma-ray beams over much of the sky. I summarize here the suite of gamma-ray discoveries and what it has taught us about pulsar populations. Young, classical radio-detectable pulsars, gamma-ray only `Gemingas' and energetic millisecond pulsars are equally represented in the Fermi sky. This sample certainly reveals much about magnetospheric physics. However, by chasing down the pulsars responsible for Fermi sources we continue to discover exotic systems whose study impacts a wide range of high energy astrophysics. Gamma-ray pulsars are revealing details of close binary evolution, testing the equation of state of ultra-dense matter, helping us understand the cosmic ray positrons, and aiding in the search for ultra-low frequency gravitational radiation. I summarize recent progress on these fronts and the prospects for more exciting discoveries to come.

  15. Short gamma-ray bursts: A review

    NASA Astrophysics Data System (ADS)

    D'Avanzo, P.

    2015-09-01

    Gamma-Ray Bursts (GRBs) are rapid, bright flashes of radiation peaking in the gamma-ray band occurring at an average rate of one event per day at cosmological distances. They are characterized by a collimated relativistic outflow pushing through the interstellar medium shining in gamma-rays powered by a central engine. This prompt phase is followed by a fading afterglow emission at longer wavelength, powered in part by the expanding outflow, and in part by continuous energy injection by the central engine. The observed evidences of supernovae associated to long GRBs (those with a duration of the gamma-ray emission > 2 s) brought to a general consensus on indicating the core collapse of massive stars as the progenitor of these events. Following the most accredited model, short GRBs (the events with a duration of the gamma-ray emission ? 2 s) originate from the coalescence of compact binary systems (two neutron stars or neutron star-black hole systems). This paper presents a review of the observational properties of short GRBs and shows how the study of these properties can be used as a tool to unveil their elusive progenitors and provide information on the nature of the central engine powering the observed emission. The increasing evidence for compact object binary progenitors makes short GRBs one of the most promising sources of gravitational waves for the forthcoming Advanced LIGO/Virgo experiments.

  16. Observing Gamma-ray Bursts with GLAST

    NASA Technical Reports Server (NTRS)

    McEnery, Julie

    2008-01-01

    The Gamma-ray Large Area Telescope (GLAST) is a satellite-based observatory to study the high-energy gamma-ray sky. The Large Area Telescope, the main instrument, is a pair-conversion telescope which will survey the sky in the energy range 20 MeV to greater than 300 GeV. The LAT's wide field of view (greater than 2 sr), large effective area and low deadtime combine to provide excellent high-energy gamma-ray observations of GRB. To tie these frontier high-energy observations to the better-known properties at lower energies, a second instrument, the GLAST Burst Monitor (GBM) will provide important spectra and timing in the 8 keV to 30 MeV range. Upon detection of a GRB by the LAT or the GBM, the spacecraft can autonomously repoint to keep the GRB location within the LAT field of view, allowing high-energy afterglow observations. We describe how the instruments, spacecraft, and ground system work together to provide observations of gamma-ray bursts from 8 keV to over 300 GeV and provide rapid notification of these observations to the wider gamma-ray burst community. Analysis and simulation tools dedicated to the GRB science have been developed. In this contribution we show the expected LAT sensitivity obtained with such simulations, and illustrate the results we expect from GLAST observations with spectral and temporal analysis of simulated GRB.

  17. LUMINOSITY EVOLUTION OF GAMMA-RAY PULSARS

    SciTech Connect

    Hirotani, Kouichi

    2013-04-01

    We investigate the electrodynamic structure of a pulsar outer-magnetospheric particle accelerator and the resulting gamma-ray emission. By considering the condition for the accelerator to be self-sustained, we derive how the trans-magnetic-field thickness of the accelerator evolves with the pulsar age. It is found that the thickness is small but increases steadily if the neutron-star envelope is contaminated by sufficient light elements. For such a light element envelope, the gamma-ray luminosity of the accelerator is kept approximately constant as a function of age in the initial 10,000 yr, forming the lower bound of the observed distribution of the gamma-ray luminosity of rotation-powered pulsars. If the envelope consists of only heavy elements, on the other hand, the thickness is greater, but it increases less rapidly than a light element envelope. For such a heavy element envelope, the gamma-ray luminosity decreases relatively rapidly, forming the upper bound of the observed distribution. The gamma-ray luminosity of a general pulsar resides between these two extreme cases, reflecting the envelope composition and the magnetic inclination angle with respect to the rotation axis. The cutoff energy of the primary curvature emission is regulated below several GeV even for young pulsars because the gap thickness, and hence the acceleration electric field, is suppressed by the polarization of the produced pairs.

  18. Digital discrimination of neutrons and gamma-rays in organic scintillation detectors using moment analysis

    SciTech Connect

    Xie Xufei; Zhang Xing; Yuan Xi; Chen Jinxiang; Li Xiangqing; Zhang Guohui; Fan Tieshuan; Yuan Guoliang; Yang Jinwei; Yang Qingwei

    2012-09-15

    Digital discrimination of neutron and gamma-ray events in an organic scintillator has been investigated by moment analysis. Signals induced by an americium-beryllium (Am/Be) isotropic neutron source in a stilbene crystal detector have been sampled with a flash analogue-to-digital converter (ADC) of 1 GSamples/s sampling rate and 10-bit vertical resolution. Neutrons and gamma-rays have been successfully discriminated with a threshold corresponding to gamma-ray energy about 217 keV. Moment analysis has also been verified against the results assessed by a time-of-flight (TOF) measurement. It is shown that the classification of neutrons and gamma-rays afforded by moment analysis is consistent with that achieved by digital TOF measurement. This method has been applied to analyze the data acquired from the stilbene crystal detector in mixed radiation field of the HL-2A tokamak deuterium plasma discharges and the results are described.

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

    SciTech Connect

    Younes, W.

    2014-11-13

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

  20. Probing the Intergalactic Magnetic Field with the Anisotropy of the Extragalactic Gamma-Ray Background

    NASA Technical Reports Server (NTRS)

    Venters, T. M.; Pavlidou, V.

    2012-01-01

    The intergalactic magnetic field (IGMF) may leave an imprint on the anisotropy properties of the extragalactic gamma-ray background, through its effect on electromagnetic cascades triggered by interactions between very high energy photons and the extragalactic background light. A strong IGMF will deflect secondary particles produced in these cascades and will thus tend to isotropize lower energy cascade photons, thus inducing a modulation in the anisotropy energy spectrum of the gamma-ray background. Here we present a simple, proof-of-concept calculation of the magnitude of this effect and demonstrate that the two extreme cases (zero IGMF and IGMF strong enough to completely isotropize cascade photons) would be separable by ten years of Fermi observations and reasonable model parameters for the gamma-ray background. The anisotropy energy spectrum of the Fermi gamma-ray background could thus be used as a probe of the IGMF strength.

  1. Digital discrimination of neutrons and gamma-rays in organic scintillation detectors using moment analysis

    NASA Astrophysics Data System (ADS)

    Xie, Xufei; Zhang, Xing; Yuan, Xi; Chen, Jinxiang; Li, Xiangqing; Zhang, Guohui; Fan, Tieshuan; Yuan, Guoliang; Yang, Jinwei; Yang, Qingwei

    2012-09-01

    Digital discrimination of neutron and gamma-ray events in an organic scintillator has been investigated by moment analysis. Signals induced by an americium-beryllium (Am/Be) isotropic neutron source in a stilbene crystal detector have been sampled with a flash analogue-to-digital converter (ADC) of 1 GSamples/s sampling rate and 10-bit vertical resolution. Neutrons and gamma-rays have been successfully discriminated with a threshold corresponding to gamma-ray energy about 217 keV. Moment analysis has also been verified against the results assessed by a time-of-flight (TOF) measurement. It is shown that the classification of neutrons and gamma-rays afforded by moment analysis is consistent with that achieved by digital TOF measurement. This method has been applied to analyze the data acquired from the stilbene crystal detector in mixed radiation field of the HL-2A tokamak deuterium plasma discharges and the results are described.

  2. Gamma-ray lines from radiative dark matter decay

    SciTech Connect

    Garny, Mathias; Ibarra, Alejandro; Tran, David; Weniger, Christoph E-mail: alejandro.ibarra@ph.tum.de E-mail: weniger@mppmu.mpg.de

    2011-01-01

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

  3. Ground-Based Gamma Ray Astronomy

    NASA Astrophysics Data System (ADS)

    Holder, Jamie

    2014-10-01

    This paper is the write-up of a rapporteur talk given by the author at the 33rd International Cosmic Ray Conference in Rio de Janeiro, Brazil, in 2013. It attempts to summarize results and developments in ground-based gamma-ray observations and instrumentation from among the ˜300 submissions to the gamma-ray sessions of the meeting. Satellite observations and theoretical developments were covered by a companion rapporteur (Stawarz, L., 33rd ICRC, Rio de Janeiro, Brazil, Rapporteur talk: Space-based Gamma-Ray Astronomy, 2013). Any review of this nature is unavoidably subjective and incomplete. Nevertheless, the article should provide a useful status report for those seeking an overview of this exciting and fast-moving field.

  4. Technology Needs for Gamma Ray Astronomy

    NASA Technical Reports Server (NTRS)

    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.

  5. Gamma-Ray Imaging for Explosives Detection

    NASA Technical Reports Server (NTRS)

    deNolfo, G. A.; Hunter, S. D.; Barbier, L. M.; Link, J. T.; Son, S.; Floyd, S. R.; Guardala, N.; Skopec, M.; Stark, B.

    2008-01-01

    We describe a gamma-ray imaging camera (GIC) for active interrogation of explosives being developed by NASA/GSFC and NSWCICarderock. The GIC is based on the Three-dimensional Track Imager (3-DTI) technology developed at GSFC for gamma-ray astrophysics. The 3-DTI, a large volume time-projection chamber, provides accurate, approx.0.4 mm resolution, 3-D tracking of charged particles. The incident direction of gamma rays, E, > 6 MeV, are reconstructed from the momenta and energies of the electron-positron pair resulting from interactions in the 3-DTI volume. The optimization of the 3-DTI technology for this specific application and the performance of the GIC from laboratory tests is presented.

  6. Galaxies and gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Bignami, G. F.; Fichtel, C. E.; Hartman, R. C.; Thompson, D. J.

    1979-01-01

    The nature of the high-energy spectra of several types of active galaxies and their contribution to the measured diffuse gamma-ray emission between 1 and 150 MeV are considered, using X-ray spectra of active galaxies and SAS 2 data regarding the intensity upper limits to the gamma-ray emission above 35 MeV. It is found that a substantial increase in slope of the photon energy spectrum must occur in the low energy gamma-ray region for Seyfert galaxies, BL Lac objects, and emission line galaxies; the power-law spectra observed in the X-ray range must steepen substantially between 50 keV and 50 MeV. In addition, a cosmological integration shows that Seyfert galaxies, BL Lac objects, and quasars may account for most of the 1-150 MeV diffuse background, even without significant evolution.

  7. Gamma-ray imaging with stochastic apertures.

    PubMed

    May, R S; Akcasu, Z; Knoll, G F

    1974-11-01

    The spatial distribution of a radioactive fluid can be measured indirectly by observing the emerging gamma rays. A method is proposed and analyzed for gamma-ray imaging by stochastic time modulation and cross-correlation. Theoretical comparison is made to collimation and coded aperture techniques in gamma-ray image formation. Computed results are presented that illustrate the mean response and statistical error characteristics of this technique. Monte Carlo simulations are performed as a further verification. Because it relies upon a point-by-point reconstruction, rather than upon the integral properties of any particular aperture, the time modulation approach is seen to provide a theoretical basis for obtaining a smooth three-dimensional point response. PMID:20134739

  8. Solar gamma rays and neutron observations

    NASA Technical Reports Server (NTRS)

    Chupp, E. L.; Forrest, D. J.; Suri, A. N.

    1972-01-01

    The present status of knowledge concerning the impulsive and the continuous emission of solar gamma rays and neutrons is reviewed in the light of the recent solar activity in early August 1972. The gamma ray spectrometer on OSO-7 has observed the sun continuously for most of the activity period except for occultation by the earth. In association with the 2B flare on 4 August 1972 and the 3B flare on 7 August 1972, the monitor provides evidence for solar gamma ray line emission in the energy range from 300 keV to 10 MeV. A summary of all the results available from preliminary analysis of the data will be given. Significant improvements in future experiments can be made with more sensitive instruments and more extensive time coverage of the sun.

  9. Gamma-ray bursters at cosmological distances

    NASA Technical Reports Server (NTRS)

    Paczynski, B.

    1986-01-01

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

  10. Gamma-ray and neutron spectroscopy of planetary surfaces and atmospheres

    SciTech Connect

    Reedy, R.C.

    1987-01-01

    The neutrons and gamma rays escaping from a planet can be used to map the concentrations of various elements in its surface. In a planet, the high-energy particles in the galactic cosmic rays induce a cascade of particles that includes many neutrons. The ..gamma.. rays are made by the decay of the naturally-occurring radioelements and by nuclear excitations induced by cosmic-ray particles and their secondaries (especially neutron capture or inelastic scattering reactions). After a short history of planetary ..gamma..-ray and neutron spectroscopy, the ..gamma..-ray spectrometer and active neutron detection system planned for the Mars Observer Mission are presented. The results of laboratory experiments that simulate the cosmic-ray bombardments of planetary surfaces and the status of the theoretical calculations for the processes that make and transport neutrons and ..gamma.. rays will be reviewed. Studies of Mars, including its atmosphere, are emphasized, as are new ideas, concepts, and problems that have arisen over the last decade, such as Doppler broadening and peaks from neutron scattering with germanium nuclei in a ..gamma..-ray spectrometer. 23 refs., 1 fig.

  11. Neutron and Gamma-ray Measurements

    NASA Astrophysics Data System (ADS)

    Krasilnikov, Anatoly V.; Sasao, Mamiko; Kaschuck, Yuri A.; Kiptily, Vasily G.; Nishitani, Takeo; Popovichev, Sergey V.; Bertalot, Luciano

    2008-03-01

    Due to high neutron and gamma-ray yields and large size plasmas many future fusion reactor plasma parameters such as fusion power, fusion power density, ion temperature, fuel mixture, fast ion energy and spatial distributions can be well measured by various fusion product diagnostics. Neutron diagnostics provide information on fusion reaction rate, which indicates how close is the plasma to the ultimate goal of nuclear fusion and fusion power distribution in the plasma core, which is crucial for optimization of plasma breakeven and burn. Depending on the plasma conditions neutron and gamma-ray diagnostics can provide important information, namely about dynamics of fast ion energy and spatial distributions during neutral beam injection, ion cyclotron heating and generated by fast ions MHD instabilities. The influence of the fast particle population on the 2-D neutron source profile was clearly demonstrated in JET experiments. 2-D neutron and gamma-ray source measurements could be important for driven plasma heating profile optimization in fusion reactors. To meat the measurement requirements in ITER the planned set of neutron and gamma ray diagnostics includes radial and vertical neutron and gamma cameras, neutron flux monitors, neutron activation systems and neutron spectrometers. The necessity of using massive radiation shielding strongly influences the diagnostic designs in fusion reactor, determines angular fields of view of neutron and gamma-ray cameras and spectrometers and gives rise to unavoidable difficulties in the absolute calibration. The development, testing in existing tokomaks and a possible engineering integration of neuron and gamma-ray diagnostic systems into ITER are presented.

  12. VHE Gamma-ray Supernova Remnants

    SciTech Connect

    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.

  13. Noiseless coding for the Gamma Ray spectrometer

    NASA Technical Reports Server (NTRS)

    Rice, R.; Lee, J. J.

    1985-01-01

    The payload of several future unmanned space missions will include a sophisticated gamma ray spectrometer. Severely constrained data rates during certain portions of these missions could limit the possible science return from this instrument. This report investigates the application of universal noiseless coding techniques to represent gamma ray spectrometer data more efficiently without any loss in data integrity. Performance results demonstrate compression factors from 2.5:1 to 20:1 in comparison to a standard representation. Feasibility was also demonstrated by implementing a microprocessor breadboard coder/decoder using an Intel 8086 processor.

  14. Radioactivities and gamma-rays from supernovae

    NASA Technical Reports Server (NTRS)

    Woosley, S. E.

    1991-01-01

    An account is given of the implications of several calculations relevant to the estimation of gamma-ray signals from various explosive astronomical phenomena. After discussing efforts to constrain the amounts of Ni-57 and Ti-44 produced in SN 1987A, attention is given to the production of Al-27 in massive stars and SNs. A 'delayed detonation' model of type Ia SNs is proposed, and the gamma-ray signal which may be expected when a bare white dwarf collapses directly into a neutron star is discussed.

  15. Solar gamma rays and other nuclear secondaries

    NASA Technical Reports Server (NTRS)

    Forrest, D. J.; Chupp, E. L.; Suri, A. N.

    1975-01-01

    Observations of solar gamma rays and nuclear secondaries associated with flares provide a direct probe into the behavior of energetic solar particles and the conditions under which they are accelerated, stored, and released on the sun. During the August 1972 series of solar events, gamma ray lines at 0.51, 2.23, 4.4, and 6.1 MeV and isotopes of H and He were detected. These experimental results and the present status of their interpretation are reviewed. The constraints that these observations have on general solar flare particle acceleration models are also discussed.

  16. Gamma ray spectrometer for Lunar Scout 2

    NASA Technical Reports Server (NTRS)

    Moss, C. E.; Burt, W. W.; Edwards, B. C.; Martin, R. A.; Nakano, George H.; Reedy, R. C.

    1993-01-01

    We review the current status of the Los Alamos program to develop a high-resolution gamma-ray spectrometer for the Lunar Scout-II mission, which is the second of two Space Exploration Initiative robotic precursor missions to study the Moon. This instrument will measure gamma rays in the energy range of approximately 0.1 - 10 MeV to determine the composition of the lunar surface. The instrument is a high-purity germanium crystal surrounded by an CsI anticoincidence shield and cooled by a split Stirling cycle cryocooler. It will provide the abundance of many elements over the entire lunar surface.

  17. Gamma ray energy tracking in GRETINA

    NASA Astrophysics Data System (ADS)

    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 March 2011, and extensive engineering runs were carried out using radioactive sources, and beams from the 88-Inch Cyclotron at LBNL. The data obtained will be used to optimize its performance. Then the first scientific campaign will start in March 2012 at NSCL MSU.

  18. Gamma ray astronomy and black hole astrophysics

    NASA Technical Reports Server (NTRS)

    Liang, Edison P.

    1990-01-01

    The study of soft gamma emissions from black-hole candidates is identified as an important element in understanding black-hole phenomena ranging from stellar-mass black holes to AGNs. The spectra of Cyg X-1 and observations of the Galactic Center are emphasized, since thermal origins and MeV gamma-ray bumps are evident and suggest a thermal-pair cloud picture. MeV gamma-ray observations are suggested for studying black hole astrophysics such as the theorized escaping pair wind, the anticorrelation between the MeV gamma bump and the soft continuum, and the relationship between source compactness and temperature.

  19. Gamma ray line observations with OSSE

    NASA Technical Reports Server (NTRS)

    Kurfess, J. D.; Grove, J. E.; Johnson, W. N.; Murphy, R. J.; Share, G. H.; Purcell, W. R.; Leising, M. D.; Harris, M. J.

    1997-01-01

    Observations from the oriented scintillation spectrometer experiment of the gamma ray lines originating from a variety of Galactic center sources are reviewed. Extensive observations were acquired of the Galactic center region, including the 0.511 MeV positron annihilation line and associated positronium continuum and Al-26 emission. The results reviewed include: Co-57 from SN 1987A; limits on Co-56 from SN 1991T; gamma ray lines from solar flares; searches for Ti-44 emission from Cas A, and searches for C-12 and O-16 lines from the Orion region.

  20. Found: A Galaxy's Missing Gamma Rays

    NASA Astrophysics Data System (ADS)

    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]Peng and collaborators argue that this emission is due solely to cosmic-ray interactions with interstellar gas. This picture is supported by the lack of variability in the emission, and the fact that Arp 220s gamma-ray luminosity is consistent with the scaling relation between gamma-ray and infrared luminosity for star-forming galaxies. The authors also argue that, due to Arp 220s high gas density, all cosmic rays will interact with the gas before escaping.Under these two assumptions, Peng and collaborators use the gamma-ray luminosity and the known supernova rate in Arp 220 to estimate how efficiently cosmic rays are acceleratedby supernova remnants in the galaxy. They determine that 4.2 2.6% of the supernova remnants kinetic energy is used to accelerate cosmic rays above 1 GeV.This is the first time such a rate has been measured directly from gamma-ray emission, but its consistent with estimates of 3-10% efficiency in the Milky Way. Future analysis of other ultraluminous infrared galaxies like Arp 220 with Fermi (and Pass 8!) will hopefully reveal more about these recent-merger, starburst environments.CitationFang-Kun Peng et al 2016 ApJ 821 L20. doi:10.3847/2041-8205/821/2/L20

  1. Occurrence in vivo of sister chromatid exchanges at the same locus in successive cell divisions caused by nonrepairable lesions induced by gamma rays

    SciTech Connect

    Morales-Ramirez, P.; Vallarino-Kelly, T.; Rodriguez-Reyes, R.

    1988-01-01

    The capacity of lesions induced by gamma radiation to produce sister chromatid exchanges (SCE) in successive divisions in mouse bone marrow cells in vivo was evaluated using a protocol for the three-way differentiation of sister chromatids. Evidence was obtained that exposure to gamma radiation induces DNA lesions that result in the formation of SCE at the same locus in two successive cell divisions. The relevance of this observation with respect to DNA repair and mutagenesis is discussed.

  2. Gamma-Ray Emission from Galaxy Clusters : DARK MATTER AND COSMIC-RAYS

    NASA Astrophysics Data System (ADS)

    Pinzke, Anders

    The quest for the first detection of a galaxy cluster in the high energy gamma-ray regime is ongoing, and even though clusters are observed in several other wave-bands, there is still no firm detection in gamma-rays. To complement the observational efforts we estimate the gamma-ray contributions from both annihilating dark matter and cosmic-ray (CR) proton as well as CR electron induced emission. Using high-resolution simulations of galaxy clusters, we find a universal concave shaped CR proton spectrum independent of the simulated galaxy cluster. Specifically, the gamma-ray spectra from decaying neutral pions, which are produced by CR protons, dominate the cluster emission. Furthermore, based on our derived flux and luminosity functions, we identify the galaxy clusters with the brightest galaxy clusters in gamma-rays. While this emission is challenging to detect using the Fermi satellite, major observations with Cherenkov telescopes in the near future may put important constraints on the CR physics in clusters. To extend these predictions, we use a dark matter model that fits the recent electron and positron data from Fermi, PAMELA, and H.E.S.S. with remarkable precision, and make predictions about the expected gamma-ray flux from nearby clusters. In order to remain consistent with the EGRET upper limit on the gamma-ray emission from Virgo, we constrain the minimum mass of substructures for cold dark matter halos. In addition, we find comparable levels of gamma-ray emission from CR interactions and dark matter annihilations without Sommerfeld enhancement.

  3. SYSTEMATIC EFFECTS IN EXTRACTING A 'GAMMA-RAY HAZE' FROM SPATIAL TEMPLATES

    SciTech Connect

    Linden, Tim; Profumo, Stefano

    2010-05-10

    Recent claims of a gamma-ray excess in the diffuse galactic emission detected by the Fermi Large Area Telescope made use of spatial templates from the interstellar medium (ISM) column density and the 408 MHz sky as proxies for neutral pion and inverse Compton (IC) gamma-ray emission, respectively. We identify significant systematic effects in this procedure that can artificially induce an additional diffuse component with a morphology strikingly similar to the claimed gamma-ray haze. To quantitatively illustrate this point, we calculate skymaps of the ratio of the gamma-ray emission from neutral pions to the ISM column density, and of IC to synchrotron emission, using detailed galactic cosmic-ray models and simulations. In the regions above and below the galactic center, the ISM template underestimates the gamma-ray emission due to neutral pion decay by approximately 20%. Additionally, the synchrotron template tends to underestimate the IC emission at low energies (few GeV) and to overestimate it at higher energies (tens of GeV) by potentially large factors that crucially depend on the assumed magnetic field structure of the Galaxy. The size of the systematic effects we find is comparable to the size of the claimed 'Fermi haze' signal. We thus conclude that a detailed model for the galactic diffuse emission is necessary in order to conclusively assess the presence of a gamma-ray excess possibly associated with the Wilkinson Microwave Anisotropy Probe haze morphology.

  4. HAWC observatory catches first gamma rays

    NASA Astrophysics Data System (ADS)

    Frías Villegas, Gabriela

    2013-06-01

    The world's largest and most modern gamma-ray observatory has carried out its first successful observations. Located inside the Pico de Orizaba national park in the Mexican state of Puebla, the High-Altitude Water Cherenkov Observatory (HAWC) is a collaboration between 26 Mexican and US institutions.

  5. Physics issues of gamma ray burst emissions

    NASA Technical Reports Server (NTRS)

    Liang, Edison

    1987-01-01

    The critical physics issues in the interpretation of gamma-ray-burst spectra are reviewed. An attempt is made to define the emission-region parameter space satisfying the maximum number of observational and theoretical constraints. Also discussed are the physical mechanisms responsible for the bursts that are most consistent with the above parameter space.

  6. Gamma-ray Astrophysics with AGILE

    SciTech Connect

    Longo, Francesco |; Tavani, M.; Barbiellini, G.; Argan, A.; Basset, M.; Boffelli, F.; Bulgarelli, A.; Caraveo, P.; Cattaneo, P.; Chen, A.; Costa, E.; Del Monte, E.; Di Cocco, G.; Di Persio, G.; Donnarumma, I.; Feroci, M.; Fiorini, M.; Foggetta, L.; Froysland, T.; Frutti, M.

    2007-07-12

    AGILE will explore the gamma-ray Universe with a very innovative instrument combining for the first time a gamma-ray imager and a hard X-ray imager. AGILE will be operational in spring 2007 and it will provide crucial data for the study of Active Galactic Nuclei, Gamma-Ray Bursts, unidentified gamma-ray sources. Galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing. The AGILE instrument is designed to simultaneously detect and image photons in the 30 MeV - 50 GeV and 15 - 45 keV energy bands with excellent imaging and timing capabilities, and a large field of view covering {approx} 1/5 of the entire sky at energies above 30 MeV. A CsI calorimeter is capable of GRB triggering in the energy band 0.3-50 MeV AGILE is now (March 2007) undergoing launcher integration and testing. The PLSV launch is planned in spring 2007. AGILE is then foreseen to be fully operational during the summer of 2007.

  7. New shield for gamma-ray spectrometry

    NASA Technical Reports Server (NTRS)

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

    1969-01-01

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

  8. Gamma-ray Pulsars: Models and Predictions

    NASA Technical Reports Server (NTRS)

    Harding Alice K.; White, Nicholas E. (Technical Monitor)

    2000-01-01

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

  9. Gamma-ray imaging in Fourier space.

    PubMed

    Chou, C; Barrett, H H

    1978-11-01

    A new coded-aperture configuration for gamma-ray imaging is described. It measures a single Fourier component of the object distribution at a time and does not require a position-sensitive detector. If, however, a position-sensitive detector is used, three-dimensional information about the source can be obtained. PMID:19684741

  10. Gamma ray imaging probes. 1: Formalism.

    PubMed

    Wild, W J

    1990-02-10

    A mathematical matrix formalism for a class of I-D temporal coded aperture gamma ray imaging probes is developed. Various code categories are presented. Object estimation is discussed as well as the effect of noise on the reconstruction. PMID:20556163

  11. Gamma-ray Astrophysics with AGILE

    NASA Astrophysics Data System (ADS)

    Longo, Francesco; Tavani, M.; Barbiellini, G.; Argan, A.; Basset, M.; Boffelli, F.; Bulgarelli, A.; Caraveo, P.; Cattaneo, P.; Chen, A.; Costa, E.; Del Monte, E.; Di Cocco, G.; di Persio, G.; Donnarumma, I.; Feroci, M.; Fiorini, M.; Foggetta, L.; Froysland, T.; Frutti, M.; Fuschino, F.; Galli, M.; Gianotti, F.; Giuliani, A.; Labanti, C.; Lapshov, I.; Lazzarotto, F.; Liello, F.; Lipari, P.; Marisaldi, M.; Mastropietro, M.; Mattaini, E.; Mauri, F.; Mereghetti, S.; Morelli, E.; Morselli, A.; Pacciani, L.; Pellizzoni, A.; Perotti, F.; Picozza, P.; Pittori, C.; Pontoni, C.; Porrovecchio, G.; Prest, M.; Rapisarda, M.; Rossi, E.; Rubini, A.; Soffitta, P.; Traci, A.; Trifoglio, M.; Trois, A.; Vallazza, E.; Vercellone, S.; Zanello, D.

    2007-07-01

    AGILE will explore the gamma-ray Universe with a very innovative instrument combining for the first time a gamma-ray imager and a hard X-ray imager. AGILE will be operational in spring 2007 and it will provide crucial data for the study of Active Galactic Nuclei, Gamma-Ray Bursts, unidentified gamma-ray sources. Galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing. The AGILE instrument is designed to simultaneously detect and image photons in the 30 MeV - 50 GeV and 15 - 45 keV energy bands with excellent imaging and timing capabilities, and a large field of view covering ~ 1/5 of the entire sky at energies above 30 MeV. A CsI calorimeter is capable of GRB triggering in the energy band 0.3-50 MeV AGILE is now (March 2007) undergoing launcher integration and testing. The PLSV launch is planned in spring 2007. AGILE is then foreseen to be fully operational during the summer of 2007.

  12. Gamma-Ray Telescope and Uncertainty Principle

    ERIC Educational Resources Information Center

    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…

  13. Gamma-ray Emission from Globular Clusters

    NASA Astrophysics Data System (ADS)

    Tam, Pak-Hin T.; Hui, Chung Y.; Kong, Albert K. H.

    2016-03-01

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

  14. A low activity gamma ray spectrometer

    NASA Astrophysics Data System (ADS)

    Liguori, C.; Sarracino, A.; Sverzellati, P. P.; Zanotti, L.

    1983-01-01

    This paper reports on the features of a gamma ray spectrometer designed for very low activity measurement. Part of the measurements have been performed in an underground laboratory in the Mont Blanc tunnel. Comparative results obtained in different experiment conditions are reported.

  15. Black holes, supernovae and gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Ruffini, Remo

    2015-07-01

    A tribute to Ya.B. Zel'dovich in the occasion of the 100th anniversary of his birth. The three fundamental paradigms for the gamma-ray burst and supernova connections to neutron stars and black holes are outlined.

  16. GAMMA RAY IMAGING FOR ENVIRONMENTAL REMEDIATION

    EPA Science Inventory

    The research is a three year development program to apply high resolution gamma-ray imaging technologies to environmental remediation of radioactive hazards. High resolution, position-sensitive germanium detectors are being developed at the Naval Research Laboratory for space app...

  17. Cascade model of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Sturrock, P. A.; Harding, A. K.; Daugherty, J. K.

    1989-01-01

    If, in a neutron star magnetosphere, an electron is accelerated to an energy of 10 to the 11th or 12th power eV by an electric field parallel to the magnetic field, motion of the electron along the curved field line leads to a cascade of gamma rays and electron-positron pairs. This process is believed to occur in radio pulsars and gamma ray burst sources. Results are presented from numerical simulations of the radiation and photon annihilation pair production processes, using a computer code previously developed for the study of radio pulsars. A range of values of initial energy of a primary electron was considered along with initial injection position, and magnetic dipole moment of the neutron star. The resulting spectra was found to exhibit complex forms that are typically power law over a substantial range of photon energy, and typically include a dip in the spectrum near the electron gyro-frequency at the injection point. The results of a number of models are compared with data for the 5 Mar., 1979 gamma ray burst. A good fit was found to the gamma ray part of the spectrum, including the equivalent width of the annihilation line.

  18. Gamma ray observations of the solar system

    NASA Technical Reports Server (NTRS)

    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.

  19. Gamma ray observations of the solar system

    SciTech Connect

    Not Available

    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.

  20. Mercury Gamma-rays and Neutron Spectrometer for ESA BepiColompo mission: numerical simulation of neutrons and gamma-rays from Mercury subsurface

    NASA Astrophysics Data System (ADS)

    Kozyrev, S. Alexander; Gunko, Natalya; Gurvits, Leonid; Litvak, Maxim; Malakhov, Alexey; Mitrofanov, Igor; Mokrousov, Maxim; Sanin, Anton; Shvetsov, Valery; Timoshenko, Genagy; Tretyakov, Vladislav; Tsygan, Anatoly; Vostrukhin, Andrey

    The nuclear instrument MGNS is under development for implementation on the MPO of Bepi-Colombo mission, as the contribution of Federal Space Agency of Russia to this project. In com-parison of gamma-rays spectrometer onboard NASA's Messenger interplanetary probe, which will provide mapping data for northern hemisphere of the planet only because of elliptical orbit, the MGNS onboard MPO will provide global mapping of the planet with similar coverage of southern and northern hemispheres of the Mercury. For analyse chemistry composition of Mercury subsurface we will apply method of as-called remote sensing of neutrons. This method can be use for study celestial body of Solar system without thick atmospheres, like Moon, Mars, Phobos, Mercury etc. by the analysis of induced nuclear gamma-rays and neutron emission. These gamma-rays and neutrons are produced by energetic galactic cosmic rays colliding with nuclei of regolith within a 1-2 meter layer of subsurface. This report will also describe result of numerical simulation flux of neutrons and gamma-rays lines from Mercury subsurface. The simulation was done for four different theoretical models of surface composition (model: ChM, EM, RM and VM) and for four different surface temperature (90 , 300 , 500 and 725 ). We simulate spectrum of neutron flux generated by Mercury surface and flax of gamma-rays for two major line (Al: 7.724 MeV and Si: 3.539 MeV) as function of temperature and subsurface composition.

  1. Radioprotector WR1065 reduces radiation-induced mutations at the hypoxanthine-guanine phosphoribosyl transferase locus in V79 cells

    SciTech Connect

    Grdina, D.J.; Hill, C.K.; Peraino, C. ); Biserka, N. ); Wells, R.L. . Dept. of Radiology and Radiation Biology)

    1985-06-01

    N-(2-mercaptoethyl)-1,3-diaminopropane (WR1065) protects against radiation-induced cell killing and mutagenesis at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus in V79 Chinese hamster lung fibroblast cells. WR1065 (4 mm) was found to be effective in protecting against radiation-induced cell lethality only if present during irradiation. No protective effect was observed if the protector was added within 5 min after irradiation or 3 h later. The effect of WR1065 on radiation-induced mutation, expressed as resistance to the cytotoxic purine analogue 6-thioguanine (HGPRT), was also investigated. This agent was effective in reducing radiation-induced mutations regardless of when it was administered. Following 10 Gy of /sup 60/Co ..gamma..-rays, the mutation frequencies observed per 10/sup 6/ survivors were 77 +- 8, 27 +- 6, 42 +- 7, and 42 +- 7 for radiation only, and WR1065 present during, immediately after, or 3 h after irradiation. These data suggest that although a segment of radiation-induced damage leading to reproductive death cannot be modulated through the postirradiation action of WR1065, processes leading to the fixation of gross genetic damage and mutation induction in surviving cells can be effectively altered and interfered with leading to a marked reduction in mutation frequency.

  2. Gamma ray bursts of black hole universe

    NASA Astrophysics Data System (ADS)

    Zhang, T. X.

    2015-07-01

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

  3. Studying the High Energy Gamma Ray Sky with Gamma Ray Large Area Space Telescope (GLAST)

    NASA Technical Reports Server (NTRS)

    Kamae, T.; Ohsugi, T.; Thompson, D. J.; Watanabe, K.

    1998-01-01

    Building on the success of the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory, the Gamma Ray Large Area Space Telescope (GLAST) will make a major step in the study of such subjects as blazars, gamma Ray bursts, the search for dark matter, supernova remnants, pulsars, diffuse radiation, and unidentified high energy sources. The instrument will be built on new and mature detector technologies such as silicon strip detectors, low-power low-noise LSI, and a multilevel data acquisition system. GLAST is in the research and development phase, and one full tower (of 25 total) is now being built in collaborating institutes. The prototype tower will be tested thoroughly at Stanford Linear Accelerator Center (SLAC) in the fall of 1999.

  4. High-Resolution Spectroscopy of Gamma-Ray Bursts with the Transient Gamma-Ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Kurczynski, P.; Palmer, D.; Seifert, H.; Teegarden, B. J.; Gehrels, N.; Cline, T. L.; Ramaty, R.; Hurley, K.; Madden, N. W.; Pehl, R. H.

    2000-11-01

    A search for spectral lines in gamma-ray bursts detected with the Transient Gamma-Ray Spectrometer has been unable to confirm their existence. The spectrometer, aboard the Wind spacecraft, has detected gamma-ray bursts and other transients since 1995. We have performed a systematic search for narrow spectral lines in gamma-ray bursts detected with this instrument that augments and extends the results of a similar search of bursts detected with BATSE. This search procedure tests for statistically significant lines at all possible times and durations during a burst using the method of maximum likelihood and C-statistic. Simulations demonstrated the effectiveness of this procedure, particularly on Poisson distributed data, for distinguishing real features from statistical fluctuations. The most promising line candidates were consistent with chance fluctuations, given the large number of spectra searched.

  5. Investigation of gamma rays from the galactic center

    NASA Technical Reports Server (NTRS)

    Helmken, H. F.

    1973-01-01

    Data from Argentine balloon flights made to investigate gamma ray emission from the galactic center are summarized. Data are also summarized from a Palestine, Texas balloon flight to measure gamma rays from NP 0532 and Crab Nebulae.

  6. Swift's 500th Gamma Ray Burst - Duration: 64 seconds.

    NASA Video Gallery

    On April 13, 2010, NASA's Swift Gamma-ray Burst Explorer satellite discovered its 500th burst. Swift's main job is to quickly localize each gamma-ray burst (GRB), report its position so that others...

  7. Gamma ray spectroscopy in astrophysics: Solar gamma ray astronomy on solar maximum mission. [experimental design

    NASA Technical Reports Server (NTRS)

    Forrest, D. J.

    1978-01-01

    The SMM gamma ray experiment and the important scientific capabilities of the instrument are discussed. The flare size detectable as a function of spectrum integration time was studied. A preliminary estimate indicates that a solar gamma ray line at 4.4 MeV one-fifth the intensity of that believed to have been emitted on 4 August 1972 can be detected in approximately 1000 sec with a confidence level of 99%.

  8. Simultaneous optical/gamma-ray observations of GRBs

    NASA Technical Reports Server (NTRS)

    Greiner, J.; Wenzel, W.; Hudec, R.; Moskalenko, E. I.; Metlov, V.; Chernych, N. S.; Getman, V. S.; Ziener, Rainer; Birkle, K.; Bade, N.

    1994-01-01

    Details on the project to search for serendipitous time correlated optical photographic observations of Gamma Ray Bursters (GRB's) are presented. The ongoing photographic observations at nine observatories are used to look for plates which were exposed simultaneously with a gamma ray burst detected by the gamma ray instrument team (BATSE) and contain the burst position. The results for the first two years of the gamma ray instrument team operation are presented.

  9. Gamma-ray astronomy--A status report

    NASA Technical Reports Server (NTRS)

    Holt, Stephen S.

    1994-01-01

    Gamma-rays provide us with powerful insight into the highest energy processes occurring in the cosmos. This review highlights some of the progress in our understanding of gamma-ray astronomy that has been enabled by new data from GRANAT and the Compton Gamma-Ray Observaatory, and suggests requirements for future progress. In particular, the unique role of the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) mission and concurrent multiwavelength observations is highlighted.

  10. Monte Carlo calibration of the SMM gamma ray spectrometer for high energy gamma rays and neutrons

    NASA Technical Reports Server (NTRS)

    Cooper, J. F.; Reppin, C.; Forrest, D. J.; Chupp, E. L.; Share, G. H.; Kinzer, R. L.

    1985-01-01

    The Gamma Ray Spectrometer (GRS) on the Solar Maximum Mission spacecraft was primarily designed and calibrated for nuclear gamma ray line measurements, but also has a high energy mode which allows the detection of gamma rays at energies above 10 MeV and solar neutrons above 20 MeV. The GRS response has been extrapolated until now for high energy gamma rays from an early design study employing Monte Carlo calculations. The response to 50 to 600 MeV solar neutrons was estimated from a simple model which did not consider secondary charged particles escaping into the veto shields. In view of numerous detections by the GRS of solar flares emitting high energy gamma rays, including at least two emitting directly detectable neutrons, the calibration of the high energy mode in the flight model has been recalculated by the use of more sophisticated Monte Carlo computer codes. New results presented show that the GRS response to gamma rays above 20 MeV and to neutrons above 100 MeV is significantly lower than the earlier estimates.

  11. Investigations in cosmic and gamma ray astronomy and nuclear instruments

    NASA Technical Reports Server (NTRS)

    Gregory, J. C.

    1982-01-01

    The Nuclear Radiation Monitor (NRM) is flying on the Spacelab 2 vehicle as part of a set of instrumentation designed to measure the ambient physical environment on Spacelab in orbit. The NRM measures the natural and induced gamma ray activity. The instrument is constituted of a 25 sq in (NaI (T1)) crystal viewed with a single phototube and surrounded by a plastic anticoincidence shield. It is mounted on a pedestal and placed, with its electronics, on the Spacelab pallet. The detector head was designed and a development model fabricated and tested. Extensive software studies for on board and GSE microprocessors for use with the NRM were also made.

  12. Gamma-Ray Telescopes: 400 Years of Astronomical Telescopes

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Cannizzo, John K.

    2010-01-01

    The last half-century has seen dramatic developments in gamma-ray telescopes, from their initial conception and development through to their blossoming into full maturity as a potent research tool in astronomy. Gamma-ray telescopes are leading research in diverse areas such as gamma-ray bursts, blazars, Galactic transients, and the Galactic distribution of Al-26.

  13. Which unidentified EGRET sources are gamma-ray pulsars?

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Cheng, K. S.

    1998-07-01

    We consider high energy gamma -ray radiation from the radio pulsars associated with some unidentified EGRET gamma -ray sources. Calculated efficiencies for the conversion of spin-down power to gamma -rays and the energy spectra of the high energy gamma -rays from these possible gamma -ray pulsars in outer gap models are compared with observed results. Of these possible gamma -ray pulsars, our results indicate that (i) PSR B1900+05 is not a possible gamma -ray pulsar; (ii) although the newly discovered young radio pulsar PSR J1105-6107 is a possible gamma -ray pulsar, it may not account for the observed high energy gamma -ray emission from 2EG J1103-6106; (iii) the high energy gamma -rays from 2EG J1801-2312 and 2EG J1857+0118 may not be produced completely by radio pulsars PSR B1758-23 and PSR B1853+01 respectively; (iv) the counterparts (radio pulsars PSR B1046-58 and PSR B1823-13) of 2EG J1049-5247 and 2EG J1825-1307 are possible gamma -ray pulsars; and (v) 2EG J0008-7307 associated with a young supernova remnant CTA 1 may contain a gamma -ray pulsar with period 0.16>= P>= 0.12 s.

  14. Very High-Energy Gamma-Ray Sources.

    ERIC Educational Resources Information Center

    Weekes, Trevor C.

    1986-01-01

    Discusses topics related to high-energy, gamma-ray astronomy (including cosmic radiation, gamma-ray detectors, high-energy gamma-ray sources, and others). Also considers motivation for the development of this field, the principal results to date, and future prospects. (JN)

  15. Measurement of DNA damage induced by irradiation with gamma-rays from a TRIGA Mark II research reactor in human cells using Fast Micromethod.

    PubMed

    Hassanein, Hamdy; Müller, Claudia I; Schlösser, Dietmar; Kratz, Karl-Ludwig; Senyuk, Olga F; Schröder, Heinz C

    2002-06-01

    The Fast Micromethod is a novel quick and convenient microplate assay for determination of DNA single-strand breaks. This method measures the rate of unwinding of cellular DNA upon exposure to alkaline conditions using a fluorescent dye which preferentially binds to double-stranded DNA. Here we applied this method to determine the levels of DNA single-strand breaks in HeLa cells induced by y-irradiation deriving from fission isotopes and activation products at the TRIGA Mark II research reactor in Mainz. An increased strand scission factor (SSF) value, which is indicative for DNA damage, was found at doses of 1 Gy and higher. A similar increase in SSF value, which further increased in a dose-dependent manner, was found in human peripheral blood mononuclear cells after irradiation with 6 MV X-rays from a linear accelerator to give a total exposure of 0.5 to 10 Gy. PMID:12064446

  16. Gamma-Ray Bursts: A Mystery Story

    NASA Technical Reports Server (NTRS)

    Parsons, Ann

    2007-01-01

    With the success of the Swift Gamma-Ray Burst Explorer currently in orbit, this is quite an exciting time in the history of Gamma Ray Bursts (GRBs). The study of GRBs is a modern astronomical mystery story that began over 30 years ago with the serendipitous discovery of these astronomical events by military satellites in the late 1960's. Until the launch of BATSE on the Compton Gamma-ray Observatory, astronomers had no clue whether GRBs originated at the edge of our solar system, in our own Milky Way Galaxy or incredibly far away near the edge of the observable Universe. Data from BATSE proved that GRBs are distributed isotropically on the sky and thus could not be the related to objects in the disk of our Galaxy. Given the intensity of the gamma-ray emission, an extragalactic origin would require an astounding amount of energy. Without sufficient data to decide the issue, a great debate continued about whether GRBs were located in the halo of our own galaxy or were at extragalactic - even cosmological distances. This debate continued until 1997 when the BeppoSAX mission discovered a fading X-ray afterglow signal in the same location as a GRB. This discovery enabled other telescopes, to observe afterglow emission at optical and radio wavelengths and prove that GRBs were at cosmological distances by measuring large redshifts in the optical spectra. Like BeppoSAX Swift, slews to new GRB locations to measure afterglow emission. In addition to improved GRB sensitivity, a significant advantage of Swift over BeppoSAX and other missions is its ability to slew very quickly, allowing x-ray and optical follow-up measurements to be made as early as a minute after the gamma-ray burst trigger rather than the previous 6-8 hour delay. Swift afterglow measurements along with follow-up ground-based observations, and theoretical work have allowed astronomers to identify two plausible scenarios for the creation of a GRB: either through core collapse of super massive stars or colliding compact objects in distant galaxies. The pieces of the puzzle are beginning to fall into place and yet the story isn't quite finished. I will frame the history of gamma-ray bursts as a mystery story and will end with a description of what we still don't know and what we'll have to do to get the next clues.

  17. Research in cosmic and gamma ray astrophysics

    NASA Technical Reports Server (NTRS)

    Stone, Edward C.; Mewaldt, Richard A.; Prince, Thomas A.

    1992-01-01

    Discussed here is research in cosmic ray and gamma ray astrophysics at the Space Radiation Laboratory (SRL) of the California Institute of Technology. The primary activities discussed involve the development of new instrumentation and techniques for future space flight. In many cases these instrumentation developments were tested in balloon flight instruments designed to conduct new investigations in cosmic ray and gamma ray astrophysics. The results of these investigations are briefly summarized. Specific topics include a quantitative investigation of the solar modulation of cosmic ray protons and helium nuclei, a study of cosmic ray positron and electron spectra in interplanetary and interstellar space, the solar modulation of cosmic rays, an investigation of techniques for the measurement and interpretation of cosmic ray isotopic abundances, and a balloon measurement of the isotopic composition of galactic cosmic ray boron, carbon, and nitrogen.

  18. The gamma ray north-south effect

    NASA Technical Reports Server (NTRS)

    White, R. S.; O'Neill, T. J.; Tumer, O. T.; Zych, A. D.

    1988-01-01

    Theoretical calculations are presented that explain the balloon observations by O'Neill et al. (1987) of a strong north-south anisotropy of atmospheric gamma rays over the Southern Hemisphere, and to predict the north-south ratios. It is shown that the gamma rays that originate at the longest distances from the telescopes give the largest north-south ratios. Comparisons are made of the experimental north-south ratios measured on balloons launched from Alice Springs, Australia, and from Palestine, Texas, U.S., and predictions are made for ratios at other geomagnetic latitudes and longitudes. It is pointed out that observers who measure backgrounds for celestial sources may be misled unless they correct for the north-south effect.

  19. Nuclear isomer suitable for gamma ray laser

    NASA Technical Reports Server (NTRS)

    Jha, S.

    1979-01-01

    The operation of gamma ray lasers (gasers) are studied. It is assumed that the nuclear isomers mentioned in previously published papers have inherent limitations. It is further assumed that the judicious use of Bormann effect or the application of the total external reflection of low energy gamma radiation at grazing angle of incidence may permit the use of a gaser crystal sufficiently long to achieve observable stimulated emission. It is suggested that a long lived 0(+) isomer decaying by low energy gamma ray emission to a short lived 2(+) excited nuclear state would be an attractive gaser candidate. It is also suggested that the nuclear isomer be incorporated in a matrix of refractory material having an electrostatic field gradient whose principal axis lies along the length of the medium. This results in the preferential transmission of electric quadrupole radiation along the length of the medium.

  20. Stirling Colgate and Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Lamb, Donald

    2014-10-01

    Even before the discovery of gamma-ray bursts (GRBs), Stirling Colgate proposed that bursts of x rays and gamma rays might be produced by a relativistic shock created in the supernova explosion of a massive star. We trace the scientific story of GRBs from their detection to the present, highlighting along the way Stirling's interest in them and his efforts to understand them. We summarize our current understanding that short, soft, repeating bursts are produced by magnetic neutron stars; short, hard bursts are produced by the mergers of neutron star-neutron star binaries; and long, hard bursts are produced by the core collapse of massive stars that have lost their hydrogen and helium envelopes. We then discuss some important open questions about GRBs and how they might be answered. We conclude by describing the recent serendipitous discovery of an x-ray burst of exactly the kind he proposed, and the insights into core collapse supernovae and GRBs that it provided.

  1. Gamma ray spectroscopic measurements of Mars.

    PubMed

    Metzger, A E; Arnold, J R

    1970-06-01

    A gamma ray spectrometer placed in orbit around Mars is expected to yield significant compositional data which can be related to the evolution of that planet. Components of the observable gamma ray flux come from the Martian surface, galactic and intergalactic space, and the spacecraft itself. The flux can be detected by a scintillation crystal or solid state detector, either of which combines efficiency of detection with energy resolution, and returns information to the earth as a pulse height distribution in order to detect characteristic energy line structure. The data will be evaluated for evidence of elemental differentiation with reference to terrestrial, meteoritic, solar, and lunar abundances. A lengthy mission will allow the surface of Mars to be mapped in a search for possible correlations between composition and topography or albedo. PMID:20076376

  2. SuperAGILE and Gamma Ray Bursts

    SciTech Connect

    Pacciani, Luigi; Costa, Enrico; Del Monte, Ettore; Donnarumma, Immacolata; Evangelista, Yuri; Feroci, Marco; Frutti, Massimo; Lazzarotto, Francesco; Lapshov, Igor; Rubini, Alda; Soffitta, Paolo; Tavani, Marco; Barbiellini, Guido; Mastropietro, Marcello; Morelli, Ennio; Rapisarda, Massimo

    2006-05-19

    The solid-state hard X-ray imager of AGILE gamma-ray mission -- SuperAGILE -- has a six arcmin on-axis angular resolution in the 15-45 keV range, a field of view in excess of 1 steradian. The instrument is very light: 5 kg only. It is equipped with an on-board self triggering logic, image deconvolution, and it is able to transmit the coordinates of a GRB to the ground in real-time through the ORBCOMM constellation of satellites. Photon by photon Scientific Data are sent to the Malindi ground station at every contact. In this paper we review the performance of the SuperAGILE experiment (scheduled for a launch in the middle of 2006), after its first onground calibrations, and show the perspectives for Gamma Ray Bursts.

  3. Gamma-ray imaging with germanium detectors

    NASA Technical Reports Server (NTRS)

    Mahoney, W. A.; Callas, J. L.; Ling, J. C.; Radocinski, R. G.; Skelton, R. T.; Varnell, L. S.; Wheaton, W. A.

    1993-01-01

    Externally segmented germanium detectors promise a breakthrough in gamma-ray imaging capabilities while retaining the superb energy resolution of germanium spectrometers. By combining existing position-sensitive detectors with an appropriate code aperture, two-dimensional imaging with 0.2-deg angular resolution becomes practical for a typical balloon experiment. Much finer resolutions are possible with larger separations between detectors and the coded aperture as would be applicable for space-based or lunar-based observatories. Two coaxial germanium detectors divided into five external segments have been fabricated and have undergone extensive performance evaluation and imaging testing in our laboratory. These tests together with detailed Monte Carlo modeling calculations have demonstrated the great promise of this sensor technology for future gamma-ray missions.

  4. Properties of multiple event gamma ray bursts

    SciTech Connect

    Lochner, J.C.

    1991-12-31

    We present results from a study of 37 multiple event gamma ray bursts found in the monitoring data of the PVO gamma ray burst detector. We define these bursts as those which have two or more distinct emission events separated by a return to the background intensity. Significant correlation exists between the duration of the first event and the duration of the second event, while some correlation exists between the hardness of the events and only weak correlation exists in the intensity of the events. Although the time profiles of events in a burst may be similar, as measured in the phase portrait, there is no general rule about the degree of similarity of the time profiles. Subdividing the data according to the recurrence time, we find a tendency for the strength of the correlation in the hardness to increase with decreasing separation between the events. 2 refs., 2 figs., 1 tab.

  5. Real time gamma-ray signature identifier

    DOEpatents

    Rowland, Mark; Gosnell, Tom B.; Ham, Cheryl; Perkins, Dwight; Wong, James

    2012-05-15

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

  6. Fissile interrogation using gamma rays from oxygen

    DOEpatents

    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.

  7. Spectral evolution in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Norris, J. P.; Share, G. H.; Messina, D. C.; Matz, M.; Kouveliotou, C.; Dennis, B. R.; Desai, U. D.; Cline, T. L.

    1986-01-01

    The Hard X-ray Burst Spectrometer (HXRBS) and the Gamma-Ray Spectrometer (GRS) on NASA's Solar Maximum Mission satellite have independently monitored cosmic gamma-ray bursts since launch in February 1980. Several bursts with relatively simple pulse structure and sufficient intensity have been analyzed for evidence of spectral variability on time scales shorter than the pulse durations. In many of these bursts pulse structures are found, ranging in duration from 1 to 10 seconds, which exhibit a trend of hard-to-soft spectral evolution. No significant evidence for soft-to-hard evolution has been found. The HXRBS data above 100 keV and the GRS data above 1 MeV indicate that the spectral evolution generally is not due to time-varying absorption features at energies below 100 keV.

  8. Intergalactic thermonuclear gamma-ray line

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1985-01-01

    The possibility of thermonculear reactions occurring in dilute space is briefly considered. X-ray emission from clusters of galaxies demonstrates that perhaps as much as 10 to the 14th solar masses of hot gas (T of about 100 million K) may often surround galaxies in clusters with a density of perhaps 0.004/cu cm. If the ion temperature is 100 million K, the thermonuclear reaction p + d to He-3 + gamma ray should emit gamma rays at a rate of roughly 4 x 10 to the 41st/sec with energy 5.516 + or -0.016 MeV. Such a source in teh virgo cluster at 15.7 Mpc would present a line flux of 1 x 10 to the -11th/sq cm/sec.

  9. Neutron-driven gamma-ray laser

    DOEpatents

    Bowman, Charles D.

    1990-01-01

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

  10. SUB-LUMINOUS {gamma}-RAY PULSARS

    SciTech Connect

    Romani, R. W.; Kerr, M.; Craig, H. A.; Johnston, S.; Cognard, I.; Smith, D. A.

    2011-09-01

    Most pulsars observed by the Fermi Large Area Telescope have {gamma}-ray luminosities scaling with spin-down power E-dot as L{sub {gamma}}{approx}(E-dot x 10{sup 33} erg s{sup -1}){sup 1/2}. However, there exist one detection and several upper limits an order of magnitude or more fainter than this trend. We describe these 'sub-luminous' {gamma}-ray pulsars and discuss the case for this being an orientation effect. Of the 12 known young radio pulsars with E-dot >10{sup 34} erg s{sup -1} and d {<=} 2 kpc several are substantially sub-luminous. The limited available geometrical constraints favor aligned geometries for these pulsars, although no one case for alignment is compelling. In this scenario GeV emission detected from such sub-luminous pulsars can be due to a lower altitude, lower-power accelerator gap.

  11. Gamma ray bursts: a 1983 overview

    SciTech Connect

    Cline, T.L.

    1983-10-01

    Gamma ray burst observations are reviewed with mention of new gamma-ray and optical transient measurements and with discussions of the controversial, contradictory and unresolved issues that have recently emerged: burst spectra appear to fluctuate in time as rapidly as they are measured, implying that any one spectrum may be incorrect. Energy spectra can be obligingly fitted to practically any desired shape, implying, in effect, that no objective spectral resolution exists at all. Burst fluxes and temporal quantities, including the total event energy, are characterized very differently with differing instruments, implying that even elementary knowledge of their properties is instrumentally subjective. Finally, the log N-log S determinations are deficient in the weak bursts, while there is no detection of a source direction anisotropy, implying that Ptolemy was right or that burst source distance estimates are basically guesswork. These issues may remain unsolved until vastly improved instruments are flown.

  12. Gamma Ray Bursts: a 1983 Overview

    NASA Technical Reports Server (NTRS)

    Cline, T. L.

    1983-01-01

    Gamma ray burst observations are reviewed with mention of new gamma-ray and optical transient measurements and with discussions of the controversial, contradictory and unresolved issues that have recently emerged: burst spectra appear to fluctuate in time as rapidly as they are measured, implying that any one spectrum may be incorrect; energy spectra can be obligingly fitted to practically any desired shape, implying, in effect, that no objective spectral resolution exists at all; burst fluxes and temporal quantities, including the total event energy, are characterized very differently with differing instruments, implying that even elementary knowledge of their properties is instrumentally subjective; finally, the log N-log S determinations are deficient in the weak bursts, while there is no detection of a source direction anisotropy, implying that Ptolemy was right or that burst source distance estimates are basically guesswork. These issues may remain unsolved until vastly improved instruments are flown.

  13. Plasma Instabilities in Gamma-Ray Bursts

    SciTech Connect

    Tautz, Robert C.

    2008-12-24

    Magnetic fields are important in a variety of astrophysical scenarios, ranging from possible creation mechanisms of cosmological magnetic fields through relativistic jets such as that from Active Galactic Nuclei and gamma-ray bursts to local phenomena in the solar system. Here, the outstanding importance of plasma instabilities to astrophysics is illustrated by applying the so-called neutral point method to gamma-ray bursts (GRBs), which are assumed to have a homogeneous background magnetic field. It is shown how magnetic turbulence, which is a prerequisite for the creation of dissipation and, subsequently, radiation, is created by the highly relativistic particles in the GRB jet. Using the fact that different particle compositions lead to different instability conditions, conclusions can be drawn about the particle composition of the jet, showing that it is more likely of baryonic nature.

  14. Nucleosynthesis and astrophysical gamma ray spectroscopy

    NASA Technical Reports Server (NTRS)

    Jacobson, Allan S.

    1987-01-01

    The HEAO-3 gamma ray spectrometer has provided evidence in the quest for the understanding of complex element formation in the universe with the discovery of Al-26 in the interstellar medium. It has demonstrated that the synthesis of intermediate mass nuclei is currently going on in the galaxy. This discovery was confirmed by the Solar Maximum Mission. The flux is peaked near the galactic center and indicates about 3 solar masses of Al-26 in the interstellar medium, with an implied ratio of Al-26/Al-27 = .00001. Several possible distributions were studied but the data gathered thus far do not allow discrimination between them. It is felt that only the spaceflight of a high resolution gamma ray spectrometer with adequate sensitivity will ultimately resolve the issue of the source of this material.

  15. Prospects for Nuclear-gamma-ray Astronomy

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1973-01-01

    An analysis was made of prospects for gamma rays coming from two sources outside the solar system: (1) radioactive decay of fresh nuclear products to explosive nucleosynthesis, and (2) scattering of low energy cosmic rays. The former should be detectable and will provide a factual base for many suppositions about the site and history of nucleosynthesis. The latter may be detectable and, if so, will probably provide factual information about high-flux regions of cosmic radiation.

  16. Gamma rays from extragalactic radio sources

    NASA Technical Reports Server (NTRS)

    Dermer, Charles D.; Schlickeiser, Reinhard; Mastichiadis, Apostolos

    1992-01-01

    It is proposed that the important connection between 3C 273 and 3C 279, the first two extragalactic sources detected at greater than 100 MeV energies, is their superluminal nature. In support of this conjecture, we propose a radiation mechanism that focuses gamma rays in the superluminal direction, due to Compton scattering of accretion-disk photons by relativistic nonthermal electrons in the jet.

  17. Compton scatter attenuation gamma ray spectrometer

    NASA Technical Reports Server (NTRS)

    Austin, W. E. (Inventor)

    1973-01-01

    A gamma ray spectrometer is described for use in intense radiation fields such as those in the vicinity of a rocket engine exhaust. A collimated radiation beam is Compton scattered toward shielded spectrometers to reduce the energy and intensity of the radiation and is energy selective among the spectrometers. The scattering targets are changeable to control the percentage of the radiation scattered. Sum-Compton coincidence techniques are employed for data selection.

  18. Gamma-ray Blazars: A Multiwavelength Study

    NASA Astrophysics Data System (ADS)

    Sowards-Emmerd, D.; Romani, R. W.; Michelson, P. F.; Ulvestad, J. S.

    2004-05-01

    We have implemented a new method of identifying candidate blazar counterparts for gamma-ray sources from the Third EGRET (3EG) catalog, selecting flat spectrum radio sources, many with X-ray counterparts. This method was originally applied to all of the northern 3EG sources (ěrtběrt > 10 degrees). Subsequently, we extended the survey south to decl. = -40 degrees, creating a small 8.4 GHz VLA A-array survey targeting flat spectrum radio sources in the area covered by 3EG error boxes. Optical spectroscopy of candidates was obtained using the Hobby-Eberly Telescope. This survey has found dozens of new counterparts, increasing the fraction of 3EG sources (ěrtběrt > 10 degrees) with blazar identifications to nearly 70%. These new counterparts include sources extending to nearly double the redshift of the most distant 3EG IDs. Of equal interest, we find a subset of the 3EG catalog without any plausible blazar counterparts according to our selection criteria, which may represent a new population of gamma-ray emitters. In preparation for the GLAST mission, we have also created a radio/X-ray selected sample with properties similar to the 3EG countparts, but outside the 3EG error contours. Further, in an effort to extend detection of gamma-ray sources below the 3EG threshold, we have developed a new technique to quantify the significance of variable gamma-ray flux at candidate positions. For example, the non-3EG selected radio candidates have a small but significant excess of flux over the random background. Finally, based on this work, we comment on the number of sources we expect GLAST to detect. DSE acknowledges support by SLAC under DOE contract DE-AC03-76SF00515.

  19. Gamma rays from active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Kazanas, Demosthenes

    1990-01-01

    The general properties of Active Galactic Nuclei (AGN) and quasars are reviewed with emphasis on their continuum spectral emission. Two general classes of models for the continuum are outlined and critically reviewed in view of the impending GRO (Gamma Ray Observatory) launch and observations. The importance of GRO in distinguishing between these models and in general in furthering the understanding of AGN is discussed. The very broad terms the status of the current understanding of AGN are discussed.

  20. Semiconductor gamma-ray detectors for nuclear medicine

    NASA Astrophysics Data System (ADS)

    Eskin, Joshua Daniel

    Semiconductor-based gamma-ray-imaging detectors are under development for use in high-resolution nuclear medicine imaging applications. These detectors, based on cadmium zinc telluride, hold great promise for delivering improved spatial resolution and detection efficiency over current methods. This dissertation presents work done on three fronts, all directed toward enhancing the practicality of these imaging devices. Electronic readout systems were built to produce gamma-ray images from the raw signals generated by the imagers. Mathematical models were developed to describe the detection process in detail. Finally, a method was developed for recovering the energy spectrum of the original source by using maximum-likelihood estimation techniques. Two electronics systems were built to read out signals from the imaging detectors. The first system takes signals from a 48 x 48-pixel array at 500 k samples per second. Pulse-height histograms are formed for each pixel in the detector, all in real time. A second system was built to read out four 64 x 64 arrays at 4 million pixels per second. This system is based on digital signal processors and flexible software, making it easily adaptable to new imaging tasks. A mathematical model of the detection process was developed as a tool for evaluating possible detector designs. One part of the model describes how the mobile charge carriers, which are released when a gamma ray is absorbed in a photoelectric interaction, induce signals in a readout circuit. Induced signals follow a 'near- field effect,' wherein only carriers moving close to a pixel electrode produce significant signal. Detector pixels having lateral dimensions that are small compared to the detector thickness will develop a signal primarily due to a single carrier type. This effect is confirmed experimentally in time-resolved measurements and with pulse-height spectra. The second part of the model is a simulation of scattering processes that take place when a gamma ray is absorbed within the detector volume. A separate simulation predicts the spreading of charge carriers due to diffusion and electrostatic forces. The models are used in a technique to improve the energy resolution of the detectors by estimation of the source spectrum using the Expectation-Maximization algorithm.

  1. Distribution of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Diaz Rodriguez, Mariangelly; Smith, M.; Tešic, G.

    2014-01-01

    Gamma-Ray Bursts (GRBs) are known to be bright, irregular flashes of gamma rays that typically last just a few seconds, believed to be caused by stellar collapse or the merger of a pair of compact objects. Through previous work, it has been found that GRBs are distributed roughly uniformly over the entire sky, rather than being confined to the relatively narrow band of the Milky Way. Using the Python programming language, we generated a model of GRBs over cosmological distances, based on current empirical GRB distributions. The grbsim python module uses the acceptance-rejection Monte Carlo method to simulate the luminosity and redshift of a large population of GRBs, including cosmological effects such as dark energy and dark matter terms that modify the large-scale structure of space-time. The results of running grbsim are demonstrated to match the distribution of GRBs observed by the Burst Alert Telescope on NASA’s Swift satellite. The grbsim module will subsequently be used to simulate gamma ray and neutrino events for the Astrophysical Multimessenger Observatory Network.

  2. The HEAO 3 gamma-ray spectrometer

    NASA Technical Reports Server (NTRS)

    Mahoney, W. A.; Ling, J. C.; Jacobson, A. S.; Tapphorn, R. M.

    1980-01-01

    The third High Energy Astronomy Observatory (HEAO 3), successfully launched into low earth orbit on September 20, 1979, carries a large high-resolution gamma-ray spectrometer designed for cosmic nuclear spectroscopy. This gamma-ray spectrometer (the HEAO C-1 experiment) consists of a cluster of four coaxial high-purity germanium detectors, each with a volume of approximately 100 cu cm. Surrounding the germanium detectors is a 6.6-cm thick CsI shield operating in active anticoincidence with the central detectors and defining a field of view of about 30 deg FWHM. An initial energy resolution of 3 keV FWHM at 1.46 MeV was achieved for each detector. All valid events in the germanium detectors are individually analyzed by an 8192-channel pulse area analyzer and transmitted at a maximum rate of 15.6 evens/s for each detector. During a 6-month mission, the experiment will perform a complete sky survey for narrow cosmic gamma-ray line emission to the sensitivity level of about 0.0001 photons/sq cm s over an operating energy range of 0.05-10 MeV.

  3. THE FERMI GAMMA-RAY BURST MONITOR

    SciTech Connect

    Meegan, Charles; Lichti, Giselher; Bissaldi, Elisabetta; Diehl, Roland; Greiner, Jochen; Von Kienlin, Andreas; Steinle, Helmut; Bhat, P. N.; Briggs, Michael S.; Connaughton, Valerie; Paciesas, W. S.; Preece, Robert; Wilson, Robert B.; Fishman, Gerald; Kouveliotou, Chryssa; Van der Horst, Alexander J.; McBreen, Sheila

    2009-09-01

    The Gamma-Ray Burst Monitor (GBM) will significantly augment the science return from the Fermi Observatory in the study of gamma-ray bursts (GRBs). The primary objective of GBM is to extend the energy range over which bursts are observed downward from the energy range of the Large Area Telescope (LAT) on Fermi into the hard X-ray range where extensive previous data sets exist. A secondary objective is to compute burst locations onboard to allow re-orienting the spacecraft so that the LAT can observe delayed emission from bright bursts. GBM uses an array of 12 sodium iodide scintillators and two bismuth germanate scintillators to detect gamma rays from {approx}8 keV to {approx}40 MeV over the full unocculted sky. The onboard trigger threshold is {approx}0.7 photons cm{sup -2} s{sup -1} (50-300 keV, 1 s peak). GBM generates onboard triggers for {approx}250 GRBs per year.

  4. AGILE: A gamma-ray mission

    NASA Astrophysics Data System (ADS)

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

    2000-04-01

    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 5×10-8 ph cm2 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. .

  5. Neutrino bursts from gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Paczynski, Bohdan; Xu, Guohong

    1994-01-01

    If gamma-ray bursts originate at cosmological distances, as strongly indicated by the results from Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory (CGRO), then ultrarelativistic ejecta are the likely consequence of the highly super-Eddington luminosity of the sources. If the energy injection rate varies with time, then the Lorentz factor of the wind also varies, and the shells of ejected matter collide with each other. The collisions between baryons produce pions which decay into high-energy photons, electrons, electron positron pairs, and neutrino pairs. The bulk Lorentz factor of approximately 300 is required if our model is to be compatible with the observed millisecond variability. The strongest gamma-ray bursts are observed to deliver approximately 10(exp -4) ergs/sq cm in 100-200 keV photons. In our scenario more energy may be delivered in a neutrino burst. Typical neutrinos may be approximately 30 GeV if the protons have a Maxwellian energy distribution, and up to approximately TeV if the protons have a power-law distribution. Such neutrino bursts are close to the detection limit of the DUMAND II experiment.

  6. Nuclear gamma rays from solar flares

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1973-01-01

    The theory of gamma ray line emission from solar flares is reviewed and revised. It is shown that the recently observed (Chupp et al., 1972) line emissions at 0.5, 2.2, 4.4 and 6.1 MeV are due to positron annihilation, deuterium deexcitation following neutron capture on hydrogen, and the deexcitation of excited states in carbon and oxygen. From the observed relative line intensities it is possible to determine the spectrum of accelerated protons in the flare region. This spectrum is found to be very similar to that the charged particles from the flare observed near earth. The total numbers of protons at the sun is deduced from the observed absolute line intensities for various interaction models. It is found that if the protons at the sun have a spectrum which is an exponential in rigidity, the total energy in protons is a few times 10 to the 28th power ergs if the gamma rays are produced by protons moving down into the sun; and about 10 to the 30th power ergs if the gamma rays are produced at the site of the acceleration.

  7. Gravitational Waves and gamma-ray Bursts

    NASA Technical Reports Server (NTRS)

    Kochanek, Christopher S.; Piran, Tsvi

    1993-01-01

    If the gamma-ray burst sources detected by GRO are coalescing binaries at cosmological distances there should be a coincident gravitational radiation signal. Using the GRBs rate we predict the gravitational radiation detection rate as a function of the gravitational wave strain at Earth. This method of predicting the rate avoids the large statistical uncertainties in the current estimates that are based on the three neutron star binaries containing pulsars found, so far, in the Galaxy. The brightest gamma-ray bursts should be accompanied by a gravitational pulse detectable by LIGO or VIRGO, and by using the bursts as triggers for LIGO/VIRGO their sensitivity can be improved by 50% and the detection rate increases by a factor of 3. LIGO/VIRGO must reach a strain sensitivity of 10(sup-20.7)h(sub 0) to detect one burst per decade, and a failure to find coincidences at a rate of one per year with a strain sensitivity of 10(sup -20.6)h(sub 0) will rule out the binary hypothesis. If they are detected as gravitational wave sources, the time delay between the gamma-rays and the gravitational waves will help to determine the burst mechanism, and the polarization of the gravitational waves will help to determine the burst geometry.

  8. Afterglow Radiation from Gamma Ray Bursts

    SciTech Connect

    Desmond, Hugh; /Leuven U. /SLAC

    2006-08-28

    Gamma-ray bursts (GRB) are huge fluxes of gamma rays that appear randomly in the sky about once a day. It is now commonly accepted that GRBs are caused by a stellar object shooting off a powerful plasma jet along its rotation axis. After the initial outburst of gamma rays, a lower intensity radiation remains, called the afterglow. Using the data from a hydrodynamical numerical simulation that models the dynamics of the jet, we calculated the expected light curve of the afterglow radiation that would be observed on earth. We calculated the light curve and spectrum and compared them to the light curves and spectra predicted by two analytical models of the expansion of the jet (which are based on the Blandford and McKee solution of a relativistic isotropic expansion; see Sari's model [1] and Granot's model [2]). We found that the light curve did not decay as fast as predicted by Sari; the predictions by Granot were largely corroborated. Some results, however, did not match Granot's predictions, and more research is needed to explain these discrepancies.

  9. Gamma-Rays from Nucleosynthesis Ejecta

    NASA Astrophysics Data System (ADS)

    Diehl, R.

    2016-01-01

    Gamma-ray lines from radioactive decay of unstable isotopes produced in massive- star and supernova nucleosynthesis have been measured with INTEGRAL over the past ten years, complementing the earlier COMPTEL survey. 26Al has become a tool to study specific source regions, such as massive-star groups and associations in nearby regions which can be discriminated from the galactic-plane background, and the inner Galaxy where Doppler shifted lines add to the astronomical information. Recent findings are that superbubbles show a remarkable asymmetry, on average, in the spiral arms of our galaxy. 60Fe is co-produced by the sources of 26Al, and the isotopic ratio from their nucleosynthesis encodes stellar-structure information. Annihilation gamma-rays from positrons in interstellar space show a puzzling bright and extended source region central to our Galaxy, but also may be partly related to nucleosynthesis. 56Ni and 44Ti isotope gamma-rays have been used to constrain supernova explosion mechanisms. Here we summarize latest results using the accumulated multi-year database of observations, and discuss their astrophysical interpretations. We also add a comparison of isotopic ratios between the ISM of the current Galaxy and the solar vicinity at solar-system formation time.

  10. Active neutron and gamma-ray instrumentation for in situ planetary science applications

    NASA Astrophysics Data System (ADS)

    Parsons, A.; Bodnarik, J.; Evans, L.; Floyd, S.; Lim, L.; McClanahan, T.; Namkung, M.; Nowicki, S.; Schweitzer, J.; Starr, R.; Trombka, J.

    2011-10-01

    We describe the development of an instrument capable of detailed in situ bulk geochemical analysis of the surface of planets, moons, asteroids, and comets. This instrument technology uses a pulsed neutron generator to excite the solid materials of a planet and measures the resulting neutron and gamma-ray emission with its detector system. These time-resolved neutron and gamma-ray data provide detailed information about the bulk elemental composition, chemical context, and density distribution of the soil within 50 cm of the surface. While active neutron scattering and neutron-induced gamma-ray techniques have been used extensively for terrestrial nuclear well logging applications, our goal is to apply these techniques to surface instruments for use on any solid solar system body. As described, experiments at NASA Goddard Space Flight Center use a prototype neutron-induced gamma-ray instrument and the resulting data presented show the promise of this technique for becoming a versatile, robust, workhorse technology for planetary science, and exploration of any of the solid bodies in the solar system. The detection of neutrons at the surface also provides useful information about the material. This paper focuses on the data provided by the gamma-ray detector.

  11. Gamma-ray production cross sections from neutron interactions with iron.

    SciTech Connect

    Nelson, R. O.; Laymon, C. M.; Wender, S. A.; Drake, D. M.; Drosg, Manfred; Bobias, S. G.; McGrath, C. A.

    2002-01-01

    The initial purpose of this experiment was to provide a consistent data base of neutron-induced gamma-ray production cross sections over a large energy range for use in estimating elemental composition of the martian surface by observing gamma rays produced by cosmic ray interactions on the planet's surface [Bo02]. However, these data should be useful for other projects such as oil-well logging, accelerator transmutation of nuclear waste, shielding calculations, gamma-ray heating for nuclear reactors and verification of nuclear model calculations and databases. The goal of the measurements was to collect data on the strongest gamma rays from many samples of interest. Because of the available beam time this meant that many of the measurcments were rather short. Despite the short running time the large samples used and the good beam intensity resulted in very satisfactory results. The samples, chosen mainly as common constituents of rock and soil and measured in the same few week period, include: B&, BN, C, Al, Mg, Si, S, Cay Ti, Cr, Mn, and Fe. Be was also used as a neutron scatterer that only produces one gamma ray (478 keV from 7Li) with appreciable intensity. Thus Be can serve as a measure of neutron-induced backgrounds. In this first paper we present results for Fe.

  12. Active Neutron and Gamma-Ray Instrumentation for In Situ Planetary Science Applications

    NASA Technical Reports Server (NTRS)

    Parsons, A.; Bodnarik, J.; Evans, L.; Floyd, A.; Lim, L.; McClanahan, T.; Namkung, M.; Nowicki, S.; Schweitzer, J.; Starr, R.; Trombka, J.

    2011-01-01

    We describe the development of an instrument capable of detailed in situ bulk geochemical analysis of the surface of planets, moons, asteroids, and comets. This instrument technology uses a pulsed neutron generator to excite the solid materials of a planet and measures the resulting neutron and gamma-ray emission with its detector system. These time-resolved neutron and gamma-ray data provide detailed information about the bulk elemental composition, chemical context, and density distribution of the soil within 50 cm of the surface. While active neutron scattering and neutron-induced gamma-ray techniques have been used extensively for terrestrial nuclear well logging applications, our goal is to apply these techniques to surface instruments for use on any solid solar system body. As described, experiments at NASA Goddard Space Flight Center use a prototype neutron-induced gamma-ray instrument and the resulting data presented show the promise of this technique for becoming a versatile, robust, workhorse technology for planetary science, and exploration of any of the solid bodies in the solar system. The detection of neutrons at the surface also provides useful information about the material. This paper focuses on the data provided by the gamma-ray detector.

  13. Future Prospects for Space-Based Gamma Ray Astronomy

    NASA Astrophysics Data System (ADS)

    McConnell, Mark

    2015-04-01

    The gamma-ray sky offers a unique view into broad range of astrophysical phenomena, from nearby solar flares, to galactic pulsars, to gamma-ray bursts at the furthest reaches of the Universe. The Fermi mission has dramatically demonstrated the broad range of topics that can be addressed by gamma-ray observations. The full range of gamma-ray energies is quite broad, covering the electromagnetic spectrum at energies above about 100 keV. The energy range below several hundred GeV is the domain of space-based gamma-ray observatories, a range that is not completely covered by the Fermi LAT instrument. The gamma ray community has recently embarked on an effort to define the next steps for space-based gamma ray astronomy. These discussions are being facilitated through the Gamma-ray Science Interest Group (GammaSIG), which exists to provide community input to NASA in regards to current and future needs of the gamma-ray astrophysics community. The GammaSIG, as a part of the Physics of the Cosmos Program Analysis Group, provides a forum open to all members of the gamma-ray community. The GammaSIG is currently working to bring the community together with a common vision that will be expressed in the form of a community roadmap. This talk will summarize some of the latest results from active gamma ray observatories, including both Fermi and INTEGRAL, and will summarize the status of the community roadmap effort.

  14. Implications of Gamma-Ray Transparency Constraints in Blazars: Minimum Distances and Gamma-Ray Collimation

    NASA Technical Reports Server (NTRS)

    Becker, Peter A.; Kafatos, Menas

    1995-01-01

    We develop a general expression for the gamma - gamma absorption coefficient, alpha(sub gamma(gamma)) for gamma-rays propagating in an arbitrary direction at an arbitrary point in space above an X-ray-emitting accretion disk. The X-ray intensity is assumed to vary as a power law in energy and radius between the outer disk radius, R(sub 0), and the inner radius, R(sub ms) which is the radius of marginal stability for a Schwarzschild black hole. We use our result for alpha(sub gamma(gamma)) to calculate the gamma - gamma optical depth, tau(sub gamma(gamma)) for gamma - rays created at height z and propagating at angle Phi relative to the disk axis, and we show that for Phi = 0 and z greater than or approx equal to R(sub 0), tau(sub gamma(gamma)) proportional to Epsilon(sup alpha)z(sup -2(alpha) - 3), where alpha is the X-ray spectral index and Epsilon is the gamma - ray energy. As an application, we use our formalism to compute the minimum distance between the central black hole and the site of production of the gamma-rays detected by EGRET during the 1991 June flare of 3C 279. In order to obtain an upper limit, we assume that all of the X-rays observed contemporaneously by Ginga were emitted by the disk. Our results suggest that the observed gamma - rays may have originated within less than or approx equal to 45 GM/sq c from a black hole of mass greater than or approx equal to 10(exp 9) solar mass, perhaps in active plasma located above the central funnel of the accretion disk. This raises the possibility of establishing a direct connection between the production of the observed gamma - rays and the accretion of material onto the black hole. We also consider the variation of the optical depth as a function of the angle of propagation Phi. Our results indicate that the "focusing" of the gamma - rays along the disk axis due to pair production is strong enough to explain the observed degree of alignment in blazar sources. If the gamma - rays are produced isotropically in gamma - ray blazars, then these objects should appear as bright MeV sources when viewed along off-axis lines of sight.

  15. The Gamma-ray Large Area Space Telescope and Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    McEnery, Julie; Ritz, Steve

    2006-01-01

    The Gamma-ray Large Area Telescope (GLAST) is a satellite-based observatory to study the high energy gamma-ray sky. The main instrument on GLAST, the Large Area Telescope (LAT) is a pair-conversion telescope that will survey the sky from 20 MeV to greater than 300 GeV. With the GLAST launch in 2007, the LAT will open a new and important window on a wide variety of high energy phenomena, including supermassive black holes and active galactic nuclei, gamma-ray bursts, supernova remnants and cosmic ray acceleration and dark matter. A second instrument, the GLAST Burst Monitor (GBM), greatly enhances GLAST s capability to study GRB by providing important spectral and timing information in the 10 keV to 30 MeV range. We describe how the instruments, spacecraft and ground system work together to provide observations of gamma-ray bursts from 8 keV - 300 GeV and to provide rapid notification of bursts to the wider gamma-ray burst community.

  16. Gravitational waves and short gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Predoi, Valeriu

    2012-07-01

    Short hard gamma-ray bursts (GRB) are believed to be produced by compact binary coalescences (CBC) { either double neutron stars or neutron star{black hole binaries. The same source is expected to emit strong gravitational radiation, detectable with existing and planned gravitational wave observatories. The focus of this work is to describe a series of searches for gravitational waves (GW) from compact binary coalescence (CBC) events triggered by short gamma-ray burst detections. Specifically, we will present the motivation, frameworks, implementations and results of searches for GW associated with short gamma-ray bursts detected by Swift, Fermi{GBM and the InterPlanetary Network (IPN) gamma-ray detectors. We will begin by presenting the main concepts that lay the foundation of gravitational waves emission, as they are formulated in the theory of General Relativity; we will also brie y describe the operational principles of GW detectors, together with explaining the main challenges that the GW detection process is faced with. Further, we will motivate the use of observations in the electromagnetic (EM) band as triggers for GW searches, with an emphasis on possible EM signals from CBC events. We will briefly present the data analysis techniques including concepts as matched{filtering through a collection of theoretical GW waveforms, signal{to{ noise ratio, coincident and coherent analysis approaches, signal{based veto tests and detection candidates' ranking. We will use two different GW{GRB search examples to illustrate the use of the existing coincident and coherent analysis methods. We will also present a series of techniques meant to improve the sensitivity of existing GW triggered searches. These include shifting background data in time in order to obtain extended coincident data and setting a prior on the GRB inclination angle, in accordance with astrophysical observations, in order to restrict the searched parameter space. We will describe the GW data analysis and present results from a GW search around 12 short gamma-ray bursts detected by the InterPlanetary Network (IPN) between 2006 and 2007. The IPN{detected bursts usually have extended localization error boxes and a search for GW was performed at different sky locations across these error regions. Since no GW detection was made, we set upper limits on the distances to the GRB progenitors; we briefly discuss the implications that two IPN GRBs error regions overlap two nearby galaxies.

  17. Gravitational waves and short gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Predoi, Valeriu

    Short hard gamma-ray bursts (GRB) are believed to be produced by compact binary coalescences (CBC), either double neutron stars or neutron star black hole binaries. The same source is expected to emit strong gravitational radiation, detectable with existing and planned gravitational wave observatories. The focus of this work is to describe a series of searches for gravitational waves (GW) from compact binary coalescence (CBC) events triggered by short gamma-ray burst detections. Specifically, we will present the motivation, frameworks, implementations and results of searches for GW associated with short gamma-ray bursts detected by Swift, Fermi{GBM and the InterPlanetary Network (IPN) gamma-ray detectors. We will begin by presenting the main concepts that lay the foundation of gravitational waves emission, as they are formulated in the theory of General Relativity; we will also brie y describe the operational principles of GW detectors, together with explaining the main challenges that the GW detection process is faced with. Further, we will motivate the use of observations in the electromagnetic (EM) band as triggers for GW searches, with an emphasis on possible EM signals from CBC events. We will briefly present the data analysis techniques including concepts as matched filtering through a collection of theoretical GW waveforms, signal{to{ noise ratio, coincident and coherent analysis approaches, signal{based veto tests and detection candidates' ranking. We will use two different GW GRB search examples to illustrate the use of the existing coincident and coherent analysis methods. We will also present a series of techniques meant to improve the sensitivity of existing GW triggered searches. These include shifting background data in time in order to obtain extended coincident data and setting a prior on the GRB inclination angle, in accordance with astrophysical observations, in order to restrict the searched parameter space. We will describe the GW data analysis and present results from a GW search around 12 short gamma-ray bursts detected by the InterPlanetary Network (IPN) between 2006 and 2007. The IPN detected bursts usually have extended localization error boxes and a search for GW was performed at different sky locations across these error regions. Since no GW detection was made, we set upper limits on the distances to the GRB progenitors; we briefly discuss the implications that two IPN GRBs error regions overlap two nearby galaxies.

  18. Gamma ray irradiated silicon nanowires: An effective model to investigate defects at the interface of Si/SiOx

    SciTech Connect

    Yin, Kui; Zhao, Yi; Liu, Liangbin; Lee, Shuit-Tong; Shao, Mingwang E-mail: xuegi@nju.edu.cn; Wang, Xiaoliang E-mail: xuegi@nju.edu.cn Xue, Gi E-mail: xuegi@nju.edu.cn

    2014-01-20

    The effect of gamma ray irradiation on silicon nanowires was investigated. Here, an additional defect emerged in the gamma-ray-irradiated silicon nanowires and was confirmed with electron spin resonance spectra. {sup 29}Si nuclear magnetic resonance spectroscopy showed that irradiation doses had influence on the Q{sup 4} unit structure. This phenomenon indicated that the unique core/shell structure of silicon nanowires might contribute to induce metastable defects under gamma ray irradiation, which served as a satisfactory model to investigate defects at the interface of Si/SiOx.

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

    DOEpatents

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

    2013-02-12

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

  20. TILLING to detect induced mutations in soybean

    PubMed Central

    Cooper, Jennifer L; Till, Bradley J; Laport, Robert G; Darlow, Margaret C; Kleffner, Justin M; Jamai, Aziz; El-Mellouki, Tarik; Liu, Shiming; Ritchie, Rae; Nielsen, Niels; Bilyeu, Kristin D; Meksem, Khalid; Comai, Luca; Henikoff, Steven

    2008-01-01

    Background Soybean (Glycine max L. Merr.) is an important nitrogen-fixing crop that provides much of the world's protein and oil. However, the available tools for investigation of soybean gene function are limited. Nevertheless, chemical mutagenesis can be applied to soybean followed by screening for mutations in a target of interest using a strategy known as Targeting Induced Local Lesions IN Genomes (TILLING). We have applied TILLING to four mutagenized soybean populations, three of which were treated with ethyl methanesulfonate (EMS) and one with N-nitroso-N-methylurea (NMU). Results We screened seven targets in each population and discovered a total of 116 induced mutations. The NMU-treated population and one EMS mutagenized population had similar mutation density (~1/140 kb), while another EMS population had a mutation density of ~1/250 kb. The remaining population had a mutation density of ~1/550 kb. Because of soybean's polyploid history, PCR amplification of multiple targets could impede mutation discovery. Indeed, one set of primers tested in this study amplified more than a single target and produced low quality data. To address this problem, we removed an extraneous target by pretreating genomic DNA with a restriction enzyme. Digestion of the template eliminated amplification of the extraneous target and allowed the identification of four additional mutant alleles compared to untreated template. Conclusion The development of four independent populations with considerable mutation density, together with an additional method for screening closely related targets, indicates that soybean is a suitable organism for high-throughput mutation discovery even with its extensively duplicated genome. PMID:18218134

  1. CdZnTe gamma ray spectrometer for orbital gamma ray spectroscopy.

    SciTech Connect

    Prettyman, T. H.; Feldman, W. C.; Fuller, K. R.; Storms, S. A.; Soldner, S. A.; Lawrence, David J. ,; Browne, M. C.; Moss, C. E.

    2001-01-01

    We present the design and analysis of a new gamma ray spectrometer for planetary science that uses an array of CdZnTe detectors to achieve the detection efficiency needed for orbital measurements. The use of CdZnTe will provide significantly improved pulse height resolution relative to scintillation-based detectors, with commensurate improvement in the accuracy of elemental abundances determined by gamma ray and neutron spectroscopy. The spectrometer can be flown either on the instrument deck of the spacecraft or on a boom. For deck-mounted systems, a BGO anticoincidence shield is included in the design to suppress the response of the CdZnTe detector to gamma rays that originate in the spacecraft. The BGO shield also serves as a backup spectrometer, providing heritage from earlier planetary science missions and reducing the risk associated with the implementation of new technology.

  2. Radiation-induced mutations and plant breeding

    SciTech Connect

    Naqvi, S.H.M.

    1985-01-01

    Ionizing radiation could cause genetic changes in an organism and could modify gene linkages. The induction of mutation through radiation is random and the probability of getting the desired genetic change is low but can be increased by manipulating different parameters such as dose rate, physical conditions under which the material has been irradiated, etc. Induced mutations have been used as a supplement to conventional plant breeding, particularly for creating genetic variability for specific characters such as improved plant structure, pest and disease resistance, and desired changes in maturity period; more than 200 varieties of crop plants have been developed by this technique. The Pakistan Atomic Energy Commission has used this technique fruitfully to evolve better germplasm in cotton, rice, chickpea, wheat and mungbean; some of the mutants have become popular commercial varieties. This paper describes some uses of radiation induced mutations and the results achieved in Pakistan so far.

  3. The axion-photon interaction and gamma ray signals of dark matter

    NASA Astrophysics Data System (ADS)

    Barranco, J.; Carrillo Monteverde, A.; Delepine, D.

    2014-03-01

    We explore two scenarios where the axion-photon interaction could induce additional astrophysical gamma ray signals for the dark matter. In the first scenario, dark compact objects made of axions, named axion stars, could collide with neutron stars. The whole energy of the axion star can be dissipated in the magnetized conducting medium of the neutron star generating gamma rays. The second scenario is an indirect method for observing self-annihilating dark matter trapped in stars: Gamma rays produced by the self-annihilation of neutralinos in the interior of the Sun can be transformed into axions due to photon-axion conversion. Then, the axion will travel freely in the Sun and be converted into photons again. This process is often referred as 'shine light through walls', in this case, the wall will be the solar interior. Hence, GeV gamma rays might pass through the Sun. We may conclude that observation of GeV photons by gamma-ray observatories like HAWC, coming from the Sun, may be a signal of annihilation of neutralinos in the interior of the Sun.

  4. Cosmic gamma-ray background from structure formation in the intergalactic medium

    PubMed

    Loeb; Waxman

    2000-05-11

    The Universe is filled with a diffuse background of gamma-ray radiation, the origin of which remains one of the unsolved puzzles of cosmology. Less than one-quarter of the gamma-ray flux can be attributed to unresolved discrete sources, such as active galactic nuclei; the remainder appears to constitute a truly diffuse background. Here we show that the shock waves induced by gravity in the gas of the intergalactic medium, during the formation of large-scale structures like filaments and sheets of galaxies, produce a population of highly relativistic electrons. These electrons scatter a small fraction of the cosmic microwave background photons in the local Universe up to gamma-ray energies, thereby providing the gamma-ray background. The predicted diffuse flux agrees with the observed background across more than four orders of magnitude in photon energy, and the model predicts that the gamma-ray background, though generated locally, is isotropic to better than five per cent on angular scales larger than a degree. Moreover, the agreement between the predicted and observed background fluxes implies a mean cosmological density of baryons that is consistent with Big Bang nucleosynthesis. PMID:10821264

  5. GAMMA RAYS FROM STAR FORMATION IN CLUSTERS OF GALAXIES

    SciTech Connect

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

    2012-08-20

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

  6. Gamma Rays from Star Formation in Clusters of Galaxies

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

  7. Predicting supernova associated to gamma-ray burst 130427a

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Ruffini, R.; Kovacevic, M.; Bianco, C. L.; Enderli, M.; Muccino, M.; Penacchioni, A. V.; Pisani, G. B.; Rueda, J. A.

    2015-07-01

    Binary systems constituted by a neutron star and a massive star are not rare in the universe. The Induced Gravitational Gamma-ray Burst (IGC) paradigm interprets Gamma-ray bursts as the outcome of a neutron star that collapses into a black hole due to the accretion of the ejecta coming from its companion massive star that underwent a supernova event. GRB 130427A is one of the most luminous GRBs ever observed, of which isotropic energy exceeds 1054 erg. And it is within one of the few GRBs obtained optical, X-ray and GeV spectra simultaneously for hundreds of seconds, which provides an unique opportunity so far to understand the multi-wavelength observation within the IGC paradigm, our data analysis found low Lorentz factor blackbody emission in the Episode 3 and its X-ray light curve overlaps typical IGC Golden Sample, which comply to the IGC mechanisms. We consider these findings as clues of GRB 130427A belonging to the IGC GRBs. We predicted on GCN the emergence of a supernova on May 2, 2013, which was later successfully detected on May 13, 2013.

  8. Radioprotection by fullerenols of Stylonychia mytilus exposed to gamma-rays.

    PubMed

    Zhao, Q; Li, Y; Xu, J; Liu, R; Li, W

    2005-02-01

    The aim was to study the protective effects of fullerenols, C60(OH)x, on Stylonychia mytilus cells exposed to 60Co gamma-rays and the probable mechanisms of fullerenols protection. Ciliated protozoans Smytilus, kept in solutions of fullerenols at different concentrations, were irradiated with 60Co gamma-rays to various dose levels. Surviving cells were counted each day over 5 days after irradiation, and the surviving fraction was calculated. The relations of the surviving fraction to radiation dose and to fullerenols concentration were studied. Superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA) and lipofusion (LIP) levels in S. mytilus were also measured. The surviving fraction of S. mytilus decreased with increasing gamma-ray doses from 100 to 2000 Gy. Fullerenols enhanced the surviving fraction, except for the highest gamma-ray dose level. The maximum protection by fullernols occurred at a concentration of 0.10 mg ml(-1). However, fullerenols at concentration of 0.25 mg ml(-1) yielded a surviving fraction lower than that for the control sample. Fullerenols at a concentration of 0.10 mg ml(-1) increased the SOD and CAT activities in the gamma-ray plus fullerenols (gamma + F) group compared with the levels in both the gamma-ray (gamma) group (p < 0.01) and the control group (p < 0.01). The MDA and LIP levels in the gamma + F groups (p < 0.01) were significantly lower than that in both the control group (p < 0.05) and the gamma group (p < 0.01). At a concentration of 0.25 mg ml(-1), fullerenols reduced the SOD and CAT activities, but increased the MDA and LIP level compared with the control. There was no significant difference in SOD and CAT activities between the gamma + F group and gamma group. While the MDA and LIP level in the gamma + F and gamma groups were similar at a dose of 500 Gy, the LIP level in the gamma + F group was significantly higher than that in the gamma group (p < 0.01) at a dose of 2000 Gy. Fullerenols are good radiation protectors for the protozoan S. mytilus exposed to gamma-rays. The effectiveness of radioprotection depends on both fullerenols concentration and gamma-ray dose. The protective effect of fullerenols on damage induced by gamma-rays seems to be mediated, at least in part, through their anti-oxidative and radical scavenging activities. PMID:16019926

  9. Rapid increase in prescission GDR {gamma}-ray emission with energy

    SciTech Connect

    Hofman, D.J.; Back, B.B.; Paul, P.

    1995-12-31

    A rapid increase in the emission of prescission giant dipole resonance (GDR) {gamma}-rays with bombarding energy is observed in excited Th and Cf nuclei formed in the reactions {sup 16}O+{sup 20B}Pb and {sup 32}S+{sup nat}W,{sup 208}Pb. This increase begins around E{sub exc} = 40 MeV for the {sup 16}O+{sup 208}Pb reaction and E{sub exc} = 70 MeV for the {sup 32}S-induced reactions. The excess {gamma}-ray yield above these thresholds cannot be described within the standard statistical model. Statistical model calculations which include a temperature dependent nuclear dissipation are able to reproduce simultaneously the observed GDR {gamma}-ray spectra and recently measured evaporation residue across sections.

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

    SciTech Connect

    Hochmuth, Kathrin A.; Sigl, Guenter

    2007-12-15

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

  11. Neutron and gamma-ray dose-rates from the Little Boy replica

    SciTech Connect

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

    1984-01-01

    We report dose-rate information obtained at many locations in the near vicinity of, and at distances out to 0.64 km from, the Little Boy replica while it was operated as a critical assembly. The measurements were made with modified conventional dosimetry instruments that used an Anderson-Braun detector for neutrons and a Geiger-Mueller tube for gamma rays with suitable electronic modules to count particle-induced pulses. Thermoluminescent dosimetry methods provide corroborative data. Our analysis gives estimates of both neutron and gamma-ray relaxation lengths in air for comparison with earlier calculations. We also show the neutron-to-gamma-ray dose ratio as a function of distance from the replica. Current experiments and further data analysis will refine these results. 7 references, 8 figures.

  12. Probing the Intergalactic Magnetic Field with the Anisotropy of the Extragalactic Gamma-ray Background

    NASA Technical Reports Server (NTRS)

    Venters, T. M.; Pavlidou, V.

    2013-01-01

    The intergalactic magnetic field (IGMF) may leave an imprint on the angular anisotropy of the extragalactic gamma-ray background through its effect on electromagnetic cascades triggered by interactions between very high energy photons and the extragalactic background light. A strong IGMF will deflect secondary particles produced in these cascades and will thus tend to isotropize lower energy cascade photons, thereby inducing a modulation in the anisotropy energy spectrum of the gamma-ray background. Here we present a simple, proof-of-concept calculation of the magnitude of this effect and demonstrate that current Fermi data already seem to prefer nonnegligible IGMF values. The anisotropy energy spectrum of the Fermi gamma-ray background could thus be used as a probe of the IGMF strength.

  13. Scientific considerations in the design of the Mars observer gamma-ray spectrometer

    SciTech Connect

    Arnold, J.R.; Boynton, W.V.; Englert, P.; Feldman, W.C.; Metzger, A.E.; Reedy, R.C.; Squyres, S.W.; Trombka, J.I.; Wanke, H.

    1987-01-01

    Cosmic-ray primary and secondary particles induce characteristic gamma-ray and neutron emissions from condensed bodies in our solar system. These characteristic emissions can be used to obtain qualitative and quantitative elemental analyses of planetary surfaces from orbital altitudes. Remote sensing gamma-ray spectroscopy has been successfully used to obtain elemental composition of the Moon and Mars during United States Apollo 15 and 16 missions and the Soviet Luna and Mars missions. A remote sensing gamma-ray and neutron spectrometer will be included aboard the United States Mars Observer Mission. If proper care is not taken in the design of the spectrometer and choice of materials in the construction of the detector system and spacecraft, the sensitivity of these remote sensing spectrometers can be greatly degraded. A discussion of these design and material selection problems is presented. 16 refs., 5 figs., 3 tabs.

  14. Scientific considerations in the design of the Mars Observer gamma-ray spectrometer

    NASA Technical Reports Server (NTRS)

    Arnold, J. R.; Boynton, W. V.; Englert, P.; Feldman, W. C.; Reedy, R. C.; Metzger, A. E.; Squyres, S. W.; Trombka, J. I.; Wanke, H.

    1989-01-01

    Cosmic-ray primary and secondary particles induce characteristic gamma-ray and neutron emissions from condensed bodies in our solar system. These characteristic emissions can be used to obtain qualitative and quantitative elemental analyses of planetary surfaces from orbital altitudes. Remote sensing gamma-ray spectroscopy has been successfully used to obtain elemental composition of the Moon and Mars during United States Apollo 15 and 16 missions and the Soviet Luna and Mars missions. A remote sensing gamma-ray and neutron spectrometer will be included aboard the United States Mars Observer Mission. If proper care is not taken in the design of the spectrometer and choice of materials in the construction of the detector system ahd spacecraft, the sensitivity of these remote sensing spectrometers can be greatly degraded. A discussion of these design and material selection problems is presented.

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

    NASA Astrophysics Data System (ADS)

    Capozziello, S.; Lambiase, G.

    2015-11-01

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

  16. Short Gamma-Ray Bursts and Dark Matter Seeding in Neutron Stars

    NASA Astrophysics Data System (ADS)

    Ángeles Pérez-García, M.; Daigne, F.; Silk, J.

    2013-05-01

    We present a mechanism based on internal self-annihilation of dark matter accreted from the galactic halo in the inner regions of neutron stars that may trigger full or partial conversion into a quark star. We explain how this effect may induce a gamma-ray burst (GRB) that could be classified as short, according to the usual definition based on time duration of the prompt gamma-ray emission. This mechanism differs in many aspects from the most discussed scenario associating short GRBs with compact object binary mergers. We list possible observational signatures that should help distinguish between these two possible classes of progenitors.

  17. Gamma-ray astronomy with a large muon detector in the ARGO-YBJ experiment

    SciTech Connect

    Di Sciascio, G.; Di Girolamo, T.; Megna, R.; Saggese, L.; Fratini, K.

    2005-02-21

    The ARGO-YBJ experiment, currently under construction at the YangBaJing Laboratory (Tibet, P.R. China, 4300 m a.s.l.), could be upgraded with a large ({approx} 2500 m2) muon detector both to extend the sensitivity to {gamma}-ray sources to energies greater than {approx} 20 TeV and to perform a cosmic ray primary composition study. In this paper we present an evaluation of the rejection power for proton-induced showers achievable with the upgraded ARGO-YBJ detector. Minimum detectable {gamma}-ray fluxes are calculated for different experimental setups.

  18. SHORT GAMMA-RAY BURSTS AND DARK MATTER SEEDING IN NEUTRON STARS

    SciTech Connect

    Perez-Garcia, M. Angeles

    2013-05-10

    We present a mechanism based on internal self-annihilation of dark matter accreted from the galactic halo in the inner regions of neutron stars that may trigger full or partial conversion into a quark star. We explain how this effect may induce a gamma-ray burst (GRB) that could be classified as short, according to the usual definition based on time duration of the prompt gamma-ray emission. This mechanism differs in many aspects from the most discussed scenario associating short GRBs with compact object binary mergers. We list possible observational signatures that should help distinguish between these two possible classes of progenitors.

  19. Common Gamma-ray Glows above Thunderclouds

    NASA Astrophysics Data System (ADS)

    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.

  20. Short Gamma-Ray Bursts Are Different

    NASA Astrophysics Data System (ADS)

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

    2000-10-01

    We analyze the BATSE time-tagged event (TTE) data for short gamma-ray bursts (durations less than 2 s). We study spectral lag vs. peak flux and hardness ratio, finding an average lag timescale approximately 20 times shorter than that for long bursts. We also use an optimal ``Bayesian block" approach, based on a 1-D Voronoi tesselation method, to identify significantly distinct pulse peaks. Comparison with previous results for long bursts indicates that short bursts clearly have shorter fundamental timescales, and thus are not explicable as an extension of the pulse paradigm for long bursts by mere reduction in the number of pulses.

  1. Gamma-ray burster counterparts - Radio

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.; Cline, Thomas L.; Desai, U. D.; Teegarden, B. J.; Atteia, J.-L.; Barat, C.; Estulin, I. V.; Evans, W. D.; Fenimore, E. E.; Hurley, K.

    1989-01-01

    Many observers and theorists have suggested that gamma-ray bursters (GRBs) are related to highly magnetized rotating, neutron stars, in which case an analogy with pulsars implies that GRBs would be prodigious emitters of polarized radio emission during quiescence. The paper reports on a survey conducted with the Very Large Array radio telescope of 10 small GRB error regions for quiescent radio emission at wavelengths of 2, 6, and 20 cm. The sensitivity of the survey varied from 0.1 to 0.8 mJy. The observations did indeed reveal four radio sources inside the GRB error regions.

  2. Gamma Ray Bursts: an Enigma Being Unraveled

    SciTech Connect

    De Rujula, Alvaro

    2003-05-14

    The best astrophysical accelerators are quasars and the 'progenitors' of GRBs which, after decades of observations and scores of theories, we still do not understand. But, I shall argue, we now know quite well where GRBs come from, and we understand how their 'beams' behave, as they make short pulses of gamma rays and long-duration X-ray, optical and radio 'afterglows'. I shall argue that our understanding of these phenomena, based on the 'Cannonball Model', is unusually simple, precise and successful. The 'sociology' of GRBs is interesting per se and, in this sense, the avatars of the Cannonball Model in confronting the generally accepted 'fireball models' are also quite revealing.

  3. Gamma ray lines from interstellar grains

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.; Ramaty, R.

    1976-01-01

    The existence of very narrow (FWHM or approximately = 5 KeV) gamma ray line emission from interstellar grains is pointed out. The prime candidate for detection is the line at 6.129 Mev from O-16, but other very narrow lines could also be detected at 0.847, 1.369, 1.634, 1.779 and 2.313 Mev from Fe-56, Mg-24, Ne-20, Si-28 and N-14. Measurements of this line emission can provide information on the composition, size and spatial distribution of interstellar grains.

  4. Gamma ray imaging probes. 2: Code optimization.

    PubMed

    Wild, W J

    1990-02-10

    The Hotelling trace is used as a figure of merit for optimizing the azimuthal aperture in a coded aperture gamma ray imaging system. We present simulations for a particular aperture size that incorporates the combined effects of signal and background variability, additive nonstationary noise, aperture code choice, and detector integration time. It is shown that crossing points occur wherein different codes are, in principle, optimal for short vs long detector count times. The optimization approach may be generalized to more complex coded aperture imaging systems. PMID:20556164

  5. Gamma-Ray Astronomy with Cherenkov Telescopes

    SciTech Connect

    Stamerra, A.

    2005-10-12

    The {gamma}-astronomy with Cherenkov telescope has recently made great progress coming to the 2nd generation of instruments. The higher sensitivity and lower energy threshold have brought to discover new sources. The determination of their spectra, necessary for developing models for acceleration, emission and absorption of the {gamma}-rays, will shed new light on the century-old problem of the origin of galactic cosmic rays.A short summary of the current physics objectives in the {gamma}-astronomy and a description of the Cherenkov telescopes technique is given. Some representative observations from the two operative telescopes, HESS and MAGIC are described.

  6. THE ORTHOGONAL GAMMA-RAY BURST MODEL

    SciTech Connect

    Contopoulos, Ioannis; Pugliese, Daniela; Nathanail, Antonios

    2014-01-01

    We explore the analogy between a rotating magnetized black hole and an axisymmetric pulsar and derive the black hole's electromagnetic spindown after its formation in the core collapse of a supermassive star. The spindown shows two characteristic phases: an early Blandford-Znajek phase that lasts a few hundred seconds and a late pulsar-like afterglow phase that lasts much longer. During the first phase, the spindown luminosity decreases almost exponentially, whereas during the afterglow phase it decreases as t {sup –a} with 1 ≲ a ≲ 1.5. We associate our findings with long duration gamma-ray bursts and compare them with observations.

  7. Fermi gamma-ray imaging of a radio galaxy.

    PubMed

    Abdo, A A; Ackermann, M; Ajello, M; Atwood, W B; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Baughman, B M; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Burnett, T H; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cavazzuti, E; Cecchi, C; Celik, O; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Colafrancesco, S; Cominsky, L R; Conrad, J; Costamante, L; Cutini, S; Davis, D S; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; do Couto e Silva, E; Drell, P S; Dubois, R; Dumora, D; Farnier, C; Favuzzi, C; Fegan, S J; Finke, J; Focke, W B; Fortin, P; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Georganopoulos, M; Germani, S; Giebels, B; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grove, J E; Guillemot, L; Guiriec, S; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hughes, R E; Jackson, M S; Jóhannesson, G; Johnson, A S; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kawai, N; Kerr, M; Knödlseder, J; Kocian, M L; Kuss, M; Lande, J; Latronico, L; Lemoine-Goumard, M; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Mazziotta, M N; McConville, W; McEnery, J E; Meurer, C; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nolan, P L; Norris, J P; Nuss, E; Ohsugi, T; Omodei, N; Orlando, E; Ormes, J F; Paneque, D; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Rochester, L S; Rodriguez, A Y; Romani, R W; Roth, M; Ryde, F; Sadrozinski, H F-W; Sambruna, R; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Sgrò, C; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Starck, J-L; Stawarz, Ł; Strickman, M S; Suson, D J; Tajima, H; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Vasileiou, V; Vilchez, N; Vitale, V; Waite, A P; Wallace, E; Wang, P; Winer, B L; Wood, K S; Ylinen, T; Ziegler, M; Hardcastle, M J; Kazanas, D

    2010-05-01

    The Fermi Gamma-ray Space Telescope has detected the gamma-ray glow emanating from the giant radio lobes of the radio galaxy Centaurus A. The resolved gamma-ray image shows the lobes clearly separated from the central active source. In contrast to all other active galaxies detected so far in high-energy gamma-rays, the lobe flux constitutes a considerable portion (greater than one-half) of the total source emission. The gamma-ray emission from the lobes is interpreted as inverse Compton-scattered relic radiation from the cosmic microwave background, with additional contribution at higher energies from the infrared-to-optical extragalactic background light. These measurements provide gamma-ray constraints on the magnetic field and particle energy content in radio galaxy lobes, as well as a promising method to probe the cosmic relic photon fields. PMID:20360067

  8. Highlights of GeV Gamma-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    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.

  9. The gamma-ray light curves of SN 1987A

    NASA Technical Reports Server (NTRS)

    Leising, Mark D.; Share, Gerald H.

    1990-01-01

    Observations of the SN 1987A ejecta in four Co-56-decay gamma-ray lines, obtained using the SMM gamma-ray spectrometer between February 1987 and May 1989, are reported and analyzed. The instrument characteristics and data-reduction procedures are described, and the results are presented in extensive tables and graphs and discussed with reference to theoretical models. Gamma-ray fluxes significantly above possible instrumental levels (as determined from analysis of pre-1987 data) were detected in the second half of 1987 and the first half of 1988. The data are found to favor a model with some Co-56 in regions of low gamma-ray optical depth by 200 d after the SN outburst over models with all Co-56 at one depth within a uniform expanding envelope. Also investigated are the gamma-ray contribution to the total bolometric luminosity and the escape (and potential observability) of Co-57 gamma rays.

  10. Multiwavelength observations of Gamma-Ray Bright Blazars

    NASA Astrophysics Data System (ADS)

    Morozova, D. A.; Troitskiy, I. S.

    2012-05-01

    We have investigated 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. The blazars with faster apparent speeds, 3C 273, 3C 279, PKS 1510-089, and 3C 66A, exhibit stronger variability of the gamma-ray emission with higher flux density. Only blazars with faster apparent speeds show simultaneous optical and gamma-ray brightness variations during the flares. Our results are consisted with models in which the gamma-ray emission arises in high-relativistic jets.

  11. Comparison of activation effects in {gamma}-ray detector materials

    SciTech Connect

    Truscott, P.R.; Evans, H.E.; Dyer, C.S.; Peerless, C.L.; Flatman, J.C.; Cosby, M.; Knight, P.; Moss, C.E.

    1996-06-01

    Activation induced by cosmic and trapped radiation in {gamma}-ray detector materials represents a significant source of background for space-based detector systems. Selection of detector materials should therefore include consideration of this background source. Results are presented from measurements of induced radioactivity in different scintillators activated either as a result of irradiation by mono-energetic protons at accelerator facilities, or flight on board the Space Shuttle. Radiation transport computer codes are used to help compare the effects observed from the scintillators, by identifying and quantifying the influence on the background spectra from more than one hundred of the radionuclides produced by spallation. For the space experiment data, the simulation results also permit determination of the contributions to detector activation from the different sources of radiation in the Shuttle cabin.

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

    SciTech Connect

    Grenier, Isabelle

    2009-04-01

    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.

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

    SciTech Connect

    Isabelle Grenier

    2009-04-01

    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.

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

    ScienceCinema

    Isabelle Grenier

    2010-01-08

    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.

  15. Fermi GBM Observations of Terrestrial Gamma-Ray Flashes

    NASA Technical Reports Server (NTRS)

    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.; Smith, D. M.; Holzworth, R.

    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.

  16. Measuring Cosmological Parameters with Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Amati, Lorenzo; Della Valle, Massimo

    2013-12-01

    In a few dozen seconds, gamma ray bursts (GRBs) emit up to 1054 erg in terms of an equivalent isotropically radiated energy Eiso, so they can be observed up to z 10. Thus, these phenomena appear to be very promising tools to describe the expansion rate history of the universe. Here, we review the use of the Ep,i-Eiso correlation of GRBs to measure the cosmological density parameter ΩM. We show that the present data set of GRBs, coupled with the assumption that we live in a flat universe, can provide independent evidence, from other probes, that ΩM 0.3. We show that current (e.g. Swift, Fermi/GBM, Konus-WIND) and forthcoming gamma ray burst (GRB) experiments (e.g. CALET/GBM, SVOM, Lomonosov/UFFO, LOFT/WFM) will allow us to constrain ΩM with an accuracy comparable to that currently exhibited by Type Ia supernovae (SNe-Ia) and to study the properties of dark energy and their evolution with time.

  17. Environments of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Roming, Peter; Tobler, Jennifer

    2016-01-01

    The death of some of the most massive stars are manifest as long gamma-ray bursts (GRBs). Studying their light curves and spectra are uncovering some of the properties of the "central engine" that remains after the progenitor star collapses, as well as the environment in which they reside. Much of our current understanding comes from data obtained in the gamma-ray to X-ray. Despite this progress in the high-energy regime, our understanding of the soft-energy component (UV/optical) is lacking, particularly with regards to UV/optical flaring from the central engine and distinguishing between interstellar material and wind environments. Although these questions have been addressed for individual bursts, no systematic study in the UV/optical has been done due to the lack of a large homogenous sample. The Swift Ultra-Violet/Optical Telescope (UVOT) has observed more GRBs in the UV/optical than any other telescope. From these observations we have generated a homogenous UV/optical GRB afterglow catalog. From this catalog and coupled with archival Swift X-Ray Telescope (XRT) data, we examine the spectral evolution of GRBs in order to probe the circumburst environment and to test current progenitor models.

  18. Iron K Lines from Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Kallman, T. R.; Meszaros, P.; Rees, M. J.

    2003-01-01

    We present models for reprocessing of an intense flux of X-rays and gamma rays expected in the vicinity of gamma ray burst sources. We consider the transfer and reprocessing of the energetic photons into observable features in the X-ray band, notably the K lines of iron. Our models are based on the assumption that the gas is sufficiently dense to allow the microphysical processes to be in a steady state, thus allowing efficient line emission with modest reprocessing mass and elemental abundances ranging from solar to moderately enriched. We show that the reprocessing is enhanced by down-Comptonization of photons whose energy would otherwise be too high to absorb on iron, and that pair production can have an effect on enhancing the line production. Both "distant" reprocessors such as supernova or wind remnants and "nearby" reprocessors such as outer stellar envelopes can reproduce the observed line fluxes with Fe abundances 30-100 times above solar, depending on the incidence angle. The high incidence angles required arise naturally only in nearby models, which for plausible values can reach Fe line to continuum ratios close to the reported values.

  19. The interplanetary gamma ray burst network

    NASA Astrophysics Data System (ADS)

    Cline, T.

    The Interplanetary Gamma-Ray Burst Network (IPN) is providing gamma-ray burst (GRB) alerts and localizations at the maximum rate anticipated before the launch of the Swift mission. The arc-minute source precision of the IPN is again permitting searches for GRB afterglows in the radio and optical regimes with delays of only hours up to 2 days. The successful addition of the Mars Odyssey mission has compensated for the loss of the asteroid mission NEAR, to reconstitute a fully long- baseline interplanetary network, with Ulysses at > 5 AU and Konus-Wind and HETE-2 near the Earth. In addition to making unassisted GRB localizations that enable a renewed supply of counterpart observations, the Mars/Ulysses/Wind IPN is confirming and reinforcing GRB source localizations with HETE-2. It has also confirmed and reinforced localizations with the BeppoSAX mission before the BeppoSAX termination in May and has detected and localized both SGRs and an unusual hard x-ray transient that is neither an SGR nor a GRB. This IPN is expected to operate until at least 2004.

  20. IS CALVERA A GAMMA-RAY PULSAR?

    SciTech Connect

    Halpern, J. P.

    2011-07-20

    Originally selected as a neutron star (NS) candidate in the ROSAT All-Sky Survey, 1RXS J141256.0+792204 ('Calvera') was discovered to be a 59 ms X-ray pulsar in a pair of XMM-Newton observations by Zane et al. Surprisingly, their claimed detection of this pulsar in Fermi {gamma}-ray data requires no period derivative, severely restricting its dipole magnetic field strength, spin-down luminosity, and distance to small values. This implies that the cooling age of Calvera is much younger than its characteristic spin-down age. If so, it could be a mildly recycled pulsar, or the first 'orphaned' central compact object (CCO). Here we show that the published Fermi ephemeris fails to align the pulse phases of the two X-ray observations with each other, which indicates that the Fermi detection is almost certainly spurious. Analysis of additional Fermi data also does not confirm the {gamma}-ray detection. This leaves the spin-down rate of Calvera less constrained, and its place among the families of NSs uncertain. It could still be either an ordinary pulsar, a mildly recycled pulsar, or an orphaned CCO.

  1. Cross sections relevant to gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Dyer, P.; Bodansky, D.; Maxson, D. R.

    1978-01-01

    Gamma-ray production cross sections were measured for protons and alpha particles incident on targets consisting of nuclei of high cosmic abundance: C-12, N-14, O-16, Ne-20, Mg-24, Si-28 and Fe-56. Solid or gaseous targets were bombarded by monoenergetic beams of protons and alpha particles, and gamma rays were detected by two Ge(Li) detectors. The proton energy for each target was varied from threshold to about 24 MeV (lab); for alphas the range was from threshold to about 27 MeV. For most transitions, it was possible to measure the total cross section by placing the detectors at 30.5 deg and 109.9 deg where the fourth-order Legendre polynomial is zero. For the case of the 16O (E sub gamma = 6.13 MeV, multipolarity E3) cross sections, yields were measured at four angles. Absolute cross sections were obtained by integrating the beam current and by measuring target thicknesses and detector efficiencies. The Ge(Li) detector resolution was a few keV (although the peak widths were greater, due to Doppler broadening).

  2. Development of gamma ray imaging cameras

    SciTech Connect

    Wehe, D.K.; Knoll, G.F.

    1992-05-28

    In January 1990, the Department of Energy initiated this project with the objective to develop the technology for general purpose, portable gamma ray imaging cameras useful to the nuclear industry. The ultimate goal of this R D initiative is to develop the analog to the color television camera where the camera would respond to gamma rays instead of visible photons. The two-dimensional real-time image would be displayed would indicate the geometric location of the radiation relative to the camera's orientation, while the brightness and color'' would indicate the intensity and energy of the radiation (and hence identify the emitting isotope). There is a strong motivation for developing such a device for applications within the nuclear industry, for both high- and low-level waste repositories, for environmental restoration problems, and for space and fusion applications. At present, there are no general purpose radiation cameras capable of producing spectral images for such practical applications. At the time of this writing, work on this project has been underway for almost 18 months. Substantial progress has been made in the project's two primary areas: mechanically-collimated (MCC) and electronically-collimated camera (ECC) designs. We present developments covering the mechanically-collimated design, and then discuss the efforts on the electronically-collimated camera. The renewal proposal addresses the continuing R D efforts for the third year effort. 8 refs.

  3. Development of gamma ray imaging cameras

    NASA Astrophysics Data System (ADS)

    Wehe, D. K.; Knoll, G. F.

    1992-05-01

    In January 1990, the Department of Energy initiated this project with the objective to develop the technology for general purpose, portable gamma ray imaging cameras useful to the nuclear industry. The ultimate goal of this R&D initiative is to develop the analog to the color television camera where the camera would respond to gamma rays instead of visible photons. The two-dimensional real-time image would be displayed and indicate the geometric location of the radiation relative to the camera's orientation, while the brightness and 'color' would indicate the intensity and energy of the radiation and, hence, identify the emitting isotope. There is a strong motivation for developing such a device for applications within the nuclear industry, for both high- and low-level waste repositories, for environmental restoration problems, and for space and fusion applications. At present, there are no general purpose radiation cameras capable of producing spectral images for such practical applications. At the time of this writing, work on this project has been underway for almost 18 months. Substantial progress has been made in the project's two primary areas: mechanically-collimated (MCC) and electronically-collimated camera (ECC) designs. We present developments covering the mechanically-collimated design, and then discuss the efforts on the electronically-collimated camera. The renewal proposal addresses the continuing R&D efforts for the third year effort.

  4. Gamma ray tests of Minimal Dark Matter

    SciTech Connect

    Cirelli, Marco; Hambye, Thomas; Panci, Paolo; Sala, Filippo; Taoso, Marco

    2015-10-12

    We reconsider the model of Minimal Dark Matter (a fermionic, hypercharge-less quintuplet of the EW interactions) and compute its gamma ray signatures. We compare them with a number of gamma ray probes: the galactic halo diffuse measurements, the galactic center line searches and recent dwarf galaxies observations. We find that the original minimal model, whose mass is fixed at 9.4 TeV by the relic abundance requirement, is constrained by the line searches from the Galactic Center: it is ruled out if the Milky Way possesses a cuspy profile such as NFW but it is still allowed if it has a cored one. Observations of dwarf spheroidal galaxies are also relevant (in particular searches for lines), and ongoing astrophysical progresses on these systems have the potential to eventually rule out the model. We also explore a wider mass range, which applies to the case in which the relic abundance requirement is relaxed. Most of our results can be safely extended to the larger class of multi-TeV WIMP DM annihilating into massive gauge bosons.

  5. Gamma-Ray Bursts and Cosmology

    NASA Technical Reports Server (NTRS)

    Norris, Jay P.

    2003-01-01

    The unrivalled, extreme luminosities of gamma-ray bursts (GRBs) make them the favored beacons for sampling the high redshift Universe. To employ GRBs to study the cosmic terrain -- e.g., star and galaxy formation history -- GRB luminosities must be calibrated, and the luminosity function versus redshift must be measured or inferred. Several nascent relationships between gamma-ray temporal or spectral indicators and luminosity or total energy have been reported. These measures promise to further our understanding of GRBs once the connections between the luminosity indicators and GRB jets and emission mechanisms are better elucidated. The current distribution of 33 redshifts determined from host galaxies and afterglows peaks near z $\\sim$ 1, whereas for the full BATSE sample of long bursts, the lag-luminosity relation predicts a broad peak z $\\sim$ 1--4 with a tail to z $\\sim$ 20, in rough agreement with theoretical models based on star formation considerations. For some GRB subclasses and apparently related phenomena -- short bursts, long-lag bursts, and X-ray flashes -- the present information on their redshift distributions is sparse or entirely lacking, and progress is expected in Swift era when prompt alerts become numerous.

  6. The Swift Gamma Ray Burst Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2004-01-01

    Swift is an international mission managed by NASA as part of its MIDEX program. It is a multiwavelength transient observatory for GRB astronomy that will launch in 2004. The goals of the mission are to determine the origin of GRBs and their afterglows and use bursts to probe the early Universe. A wide field gamma-ray camera will detect more than a hundred GRBs per year to 2-5 times fainter than BATSE. Sensitive narrow-field X-ray, and UV/optical telescopes will be pointed at the burst location in 20 to 75 sec by an autonomously controlled 'swift' spacecraft. For each burst, arcsec positions will be determined and optical/UV/x-ray/gamma-ray spectrophotometry performed. Measurements of redshift will be made for many of the bursts. The instrumentation is a combination of superb existing flight-spare hardware and design from XMM and Spectrum-X/JET-X contributed by collaborators in the UK and Italy and development of a coded-aperture camera with a large-area (approx. 0.5 square meter) CdZnTe detector array. The instruments have now completed their fabrication phase and are integrated on the observatory for final testing. Key components of the mission are vigorous follow-up and outreach programs to engage the astronomical community and public in Swift. The talk will describe the mission and its status and give a summary of our plans for GRB operations.

  7. Swift: A Gamma Ray Bursts Explorer

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2003-01-01

    Swift is a NASA gamma-ray burst MIDEX mission that is in development for launch in December 2003. It is a multiwavelength transient observatory for GRB astronomy. The goals of the mission are to determine the origin of GRBs and their afterglows and use bursts to probe the early Universe. It will also.perform a survey of the hard X-ray sky to a sensitivity level of -1 mCrab. A wide-field camera will detect more than a hundred GRBs per year to 5 times fainter than BATSE. Sensitive narrow-field X-ray and UV/optical telescopes will be pointed at the burst location in 20 to 70 sec by an autonomously controlled 'swift' spacecraft. For each burst, arcsec positions will be determined and optical/UV/X-ray/gamma-ray spectrophotometry performed. Measurements of redshift will be made for many of the bursts. The instrumentation is a combination of superb existing flight-spare hardware and design from XMM and Spectrum-X/JET-X contributed by collaborators in the UK and Italy and development of a coded-aperture camera with a large-area (approximately 0.5 square meter) CdZnTe detector array. The hardware is currently in final stages of fabrication and initial stages of integration and test. Key components of the mission are vigorous follow-up and outreach programs to engage the astronomical community and public in Swift.

  8. Very high energy gamma ray astrophysics

    SciTech Connect

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

    1992-02-01

    The second reflector (project GRANITE) is on schedule. At present (January 1992) it and the 10 m reflector are obtaining stereoscopic views of gamma-ray air showers from the Crab Nebula which verify the expected performance of the twin reflector telescopes. With the additional improvements of the upgrade (a pending DOE proposal) the twin reflectors should reach a limiting intensity of 1% that of the Crab. The astonishing early results from the EGRET detector aboard the Compton Gamma Ray Observatory indicate that distant quasars (powered by supermassive black holes) are active at GeV energies. The Whipple instruments are poised to see if such behavior continues above 100 GeV, as well as perform sensitive observations of previously reported GeV (Geminga) and TeV (Hercules X-1, etc.) sources. In addition to observing sources and identifying their location in the sky to one arcminute, experiments are planned to search for WIMPS in the mass range 0.1 to 1 TeV, and to determine the abundance of anti-protons in the cosmic rays. The successful performance of the stereoscopic reflectors demonstrates the feasibility of the concept of arrays of Cherenkov receivers. Design studies for a much larger array (CASITA) are just beginning.

  9. Physics of Gamma Ray Burst Sources

    NASA Technical Reports Server (NTRS)

    Meszaros, Peter

    2004-01-01

    During this grant period, the physics of gamma-ray bursts was investigated. A number of new results have emerged. The importance of pair formation in high compactness burst spectra may help explain x-ray flashes; a universal jet shape is a likely explanation for the distribution of jet break times; gravitational waves may be copiously produced both in short bursts from compact mergers and in long bursts arising from collapsars; x-ray iron lines are likely to be due to interaction with the stellar atmosphere of the progenitor; prompt optical flashes from reverse shocks will give diagnostics on the Lorentz factor and the environment; GeV and TeV emission from bursts may be expected in the external shock; etc. The group working with the PI included postdocs Dr. Bing Zhang (now assistant professor at University of Nevada); Dr. Shiho Kobayashi; graduate student Lijun Gou; collaborators Drs. Tim Kallman and Martin Rees. Meszaros shared with Rees and Dr. Bohan Paczynsky the AAS Rossi Prize in 2000 for their work on the theory of gamma ray bursts. The refereed publications and conference proceedings resulting from this research are summarized below. The PI gave a number of invited talks at major conferences, also listed.

  10. GAMMA-RAY BURST PREDICTIONS FOR THE FERMI GAMMA RAY SPACE TELESCOPE

    SciTech Connect

    Le, Truong; Dermer, Charles D. E-mail: charles.dermer@nrl.navy.mil

    2009-08-01

    Results of a phenomenological model to estimate the gamma-ray burst (GRB) detection rate by the Fermi Gamma-Ray Space Telescope are reported. This estimate is based on the Burst and Transient Source Experiment (BATSE) 4B GRB fluence distribution, the mean ratio of fluences measured at 100 MeV-5 GeV with Energetic Gamma-Ray Experiment Telescope (EGRET) and at 20 keV-2 MeV with BATSE, and the mean EGRET GRB spectrum for the five EGRET spark-chamber GRBs. For a 10% fluence ratio and a number spectral index {alpha}{sub 1} = -2 at 100 MeV- 5 GeV energies, we estimate a rate of {approx}20 and 4 GRBs yr{sup -1} in the Fermi Large Area Telescope field of view (FOV) with at least five photons with energy E>100 MeV and E>1 GeV, respectively. We also estimate {approx}1.5 GRBs yr{sup -1} in the Fermi FOV where at least one photon with energy E>10 GeV is detected. For these parameters, we estimate {approx}1-2 GRBs yr{sup -1} detected with the Fermi telescope with more than 100 {gamma}-rays with E {approx}> 100 MeV. Comparison predictions for {alpha}{sub 1} = -2.2, different fluence ratios, and the AGILE {gamma}-ray satellite are made. Searches for different classes of GRBs using a diagram plotting 100 MeV-10 GeV fluence versus 20 keV- 20 MeV fluence is considered as a way to search for separate classes of GRBs and, specifically, spectral differences between the short-hard and long-duration GRB classes, and for hard components in GRBs.

  11. Gamma ray constraints on the galactic supernova rate

    NASA Technical Reports Server (NTRS)

    Hartmann, D.; The, L.-S.; Clayton, D. D.; Leising, M.; Mathews, G.; Woosley, S. E.

    1992-01-01

    Monte Carlo simulations of the expected gamma-ray signatures of galactic supernovae of all types are performed in order to estimate the significance of the lack of a gamma-ray signal due to supernovae occurring during the last millenium. Using recent estimates of nuclear yields, we determine galactic supernova rates consistent with the historic supernova record and the gamma-ray limits. Another objective of these calculations of galactic supernova histories is their application to surveys of diffuse galactic gamma-ray line emission.

  12. The gamma ray spectrometer for the Solar Maximum Mission

    NASA Technical Reports Server (NTRS)

    Forrest, D. J.; Chupp, E. L.; Ryan, J. M.; Cherry, M. L.; Gleske, I. U.; Reppin, C.; Pinkau, K.; Rieger, E.; Kanbach, G.; Kinzer, R. L.

    1980-01-01

    The paper describes an actively shielded, multicrystal scintillation spectrometer for measurement of the solar gamma ray flux used by the Solar Maximum Mission Gamma Ray Experiment. The instrument provides a 476-channel pulse height spectrum every 16.38 s over the 0.3-9 MeV energy range; the gamma ray spectral analysis can be extended to at least 15 MeV on command. The instrument is designed to measure the intensity, energy, and Doppler shift of narrow gamma ray lines, the intensity of extremely broadened lines, and the photon continuum.

  13. Measurement of Disintegration Rates and Absolute {gamma}-ray Intensities

    SciTech Connect

    DeVries, Daniel J.; Griffin, Henry C.

    2006-03-13

    The majority of practical radioactive materials decay by modes that include {gamma}-ray emission. For questions of 'how much' or 'how pure', one must know the absolute intensities of the major radiations. We are using liquid scintillation counting (LSC) to measurements of disintegration rates, coupled with {gamma}-ray spectroscopy to measure absolute {gamma}-ray emission probabilities. Described is a study of the 227Th chain yielding absolute {gamma}-ray intensities with {approx}0.5% accuracy and information on LSC efficiencies.

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

    SciTech Connect

    Abdo, Aous A.; Ackermann, M.; Ajello, M.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Band, D.L.; Barbiellini, Guido; Bastieri, Denis; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bignami, G.F.; Bloom, Elliott D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brigida, M.; Bruel, P.; Burnett, Thompson H.; /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.

  15. The Goddard program of gamma-ray transient astronomy

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Teegarden, B. J.

    1981-01-01

    The Goddard program of gamma-ray burst studies is briefly reviewed. The past results, present status and future expectations are outlined regarding our endeavors using experiments on balloons. IMP-6 and IMP-7, OGO-3, ISEE-1 and ISEE-3, Helios-2, Solar Maximum Mission, the Einstein Observatory, Solar Polar and the Gamma Ray Observatory, and with the interplanetary gamma-ray burst networks, to which some of these spacecraft sensors contribute. Additional emphasis is given to the recent discovery of a new type of gamma-ray transient, detected on 5 March, 1979.

  16. The Goddard program of gamma ray transient astronomy

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Teegarden, B. J.

    1980-01-01

    Gamma ray burst studies are reviewed. The past results, present status and future expectations are outlined regarding endeavors using experiments on balloons, IMP-6 and -7, OGO-3, ISEE-1 and -3, Helios-2, Solar Maximum Mission, the Einstein Observatory, Solar Polar and the Gamma Ray Observatory, and with the interplanetary gamma ray burst networks, to which some of these spacecraft sensors contribute. Additional emphasis is given to the recent discovery of a new type of gamma ray transient, detected on 1979 March 5.

  17. Search for gamma ray lines from supernovae and supernova remnants

    NASA Technical Reports Server (NTRS)

    Chupp, E. L.; Forrest, D. J.; Suri, A. N.; Adams, R.; Tsai, C.

    1974-01-01

    A gamma ray monitor with a NaI crystal shielded with a cup-shaped CsI cover was contained in the rotating wheel compartment of the OSO-7 spacecraft for measuring the gamma ray spectra from 0.3 to 10 MeV in search for gamma ray lines from a possible remnant in the Gum Nebula and the apparent Type I supernovae in NGC5253. A brief analysis of data yielded no positive indications for X-rays, gamma ray lines, or continuum from these sources.

  18. Soft gamma rays from black holes versus neutron stars

    NASA Technical Reports Server (NTRS)

    Liang, Edison P.

    1992-01-01

    The recent launches of GRANAT and GRO provide unprecedented opportunities to study compact collapsed objects from their hard x ray and gamma ray emissions. The spectral range above 100 keV can now be explored with much higher sensitivity and time resolution than before. The soft gamma ray spectral data is reviewed of black holes and neutron stars, radiation, and particle energization mechanisms and potentially distinguishing gamma ray signatures. These may include soft x ray excesses versus deficiencies, thermal versus nonthermal processes, transient gamma ray bumps versus power law tails, lines, and periodicities. Some of the highest priority future observations are outlines which will shed much light on such systems.

  19. Observations of Gamma-Ray Bursts: An Update

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    1997-01-01

    Gamma-ray bursts remain one of the greatest mysteries in astrophysics. Observations of gamma-ray bursts made by the BATSE experiment on the Compton Gamma-Ray Observatory will be described. Most workers in the field now believe that they originate from cosmological distances. This view has been reinforced by observations this year of several optical afterglow counterparts to gamma-ray bursts. A summary of these recent discoveries will be presented, along with their implications for models of the burst emission mechanism and the energy source of the bursts.

  20. Gamma-ray/neutron spectroscopy from the Mars observer

    NASA Technical Reports Server (NTRS)

    Englert, P.; Reedy, R. C.; Drake, D. M.; Feldman, W. C.; Squyres, S. W.; Evans, L. G.; Boynton, W. V.

    1987-01-01

    The Gamma-Ray Spectrometer (GRS) experiment on Mars Observer will measure gamma rays and neutrons that escape from Mars. The intensities of gamma-ray lines and of the thermal and epithermal neutrons can be used to study many problems related to Martian volcanism and volatiles. The results of theoretical calculations for the production and transport of gamma rays and neutrons indicate that the GRS should be able to determine the abundances of many elements and the amounts and stratigraphy of H2O and CO2 on and in the top meter of the Martian surface. Design considerations of the GRS are discussed.

  1. Future Facilities for Gamma-Ray Pulsar Studies

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.

    2003-01-01

    Pulsars seen at gamma-ray energies offer insight into particle acceleration to very high energies, along with information about the geometry and interaction processes in the magnetospheres of these rotating neutron stars. During the next decade, a number of new gamma-ray facilities will become available for pulsar studies. This brief review describes the motivation for gamma-ray pulsar studies, the opportunities for such studies, and some specific discussion of the capabilities of the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) for pulsar measurements.

  2. Effect of cumulated dose on hydrogen emission from polyethylene irradiated under oxidative atmosphere using gamma rays and ion beams

    NASA Astrophysics Data System (ADS)

    Ferry, M.; Pellizzi, E.; Boughattas, I.; Fromentin, E.; Dauvois, V.; de Combarieu, G.; Coignet, P.; Cochin, F.; Ngono-Ravache, Y.; Balanzat, E.; Esnouf, S.

    2016-01-01

    This work reports the effect of very high doses, up to 10 MGy, on the H2 emission from high density polyethylene (HDPE) irradiated with gamma rays and ion beams, in the presence of oxygen. This was obtained through a two-step procedure. First, HDPE films were pre-aged, at different doses, using either gamma rays or ion beams. In the second step, the pre-aged samples were irradiated in closed glass ampoules for gas quantification, using the same beam type as for pre-ageing. The hydrogen emission rate decreases when dose increases for both gamma rays and ion beams. However, the decreasing rate appears higher under gamma rays than under ion beam irradiations and this is assigned to a lesser oxidation level under the latter. Herein, we show the effectiveness of the radiation-induced defects scavenging effect under oxidative atmosphere, under low and high excitation densities.

  3. The Most Remote Gamma-Ray Burst

    NASA Astrophysics Data System (ADS)

    2000-10-01

    ESO Telescopes Observe "Lightning" in the Young Universe Summary Observations with telescopes at the ESO La Silla and Paranal observatories (Chile) have enabled an international team of astronomers [1] to measure the distance of a "gamma-ray burst", an extremely violent, cosmic explosion of still unknown physical origin. It turns out to be the most remote gamma-ray burst ever observed . The exceedingly powerful flash of light from this event was emitted when the Universe was very young, less than about 1,500 million years old, or only 10% of its present age. Travelling with the speed of light (300,000 km/sec) during 11,000 million years or more, the signal finally reached the Earth on January 31, 2000. The brightness of the exploding object was enormous, at least 1,000,000,000,000 times that of our Sun, or thousands of times that of the explosion of a single, heavy star (a "supernova"). The ESO Very Large Telescope (VLT) was also involved in trail-blazing observations of another gamma-ray burst in May 1999, cf. ESO PR 08/99. PR Photo 28a/00 : Sky field near GRB 000131 . PR Photo 28b/00 : The fading optical counterpart of GRB 000131 . PR Photo 28c/00 : VLT spectrum of GRB 000131 . What are Gamma-Ray Bursts? One of the currently most active fields of astrophysics is the study of the mysterious events known as "gamma-ray bursts" . They were first detected in the late 1960's by instruments on orbiting satellites. These short flashes of energetic gamma-rays last from less than a second to several minutes. Despite much effort, it is only within the last few years that it has become possible to locate the sites of some of these events (e.g. with the Beppo-Sax satellite ). Since the beginning of 1997, astronomers have identified about twenty optical sources in the sky that are associated with gamma-ray bursts. They have been found to be situated at extremely large (i.e., "cosmological") distances. This implies that the energy release during a gamma-ray burst within a few seconds is larger than that of the Sun during its entire life time (about 10,000 million years). "Gamma-ray bursts" are in fact by far the most powerful events since the Big Bang that are known in the Universe. While there are indications that gamma-ray bursts originate in star-forming regions within distant galaxies, the nature of such explosions remains a puzzle. Recent observations with large telescopes, e.g. the measurement of the degree of polarization of light from a gamma-ray burst in May 1999 with the VLT ( ESO PR 08/99), are now beginning to cast some light on this long-standing mystery. The afterglow of GRB 000131 ESO PR Photo 28a/00 ESO PR Photo 28a/00 [Preview - JPEG: 400 x 475 pix - 41k] [Normal - JPEG: 800 x 949 pix - 232k] [Full-Res - JPEG: 1200 x 1424 pix - 1.2Mb] ESO PR Photo 28b/00 ESO PR Photo 28b/00 [Preview - JPEG: 400 x 480 pix - 67k] [Normal - JPEG: 800 x 959 pix - 288k] [Full-Res - JPEG: 1200 x 1439 pix - 856k] Caption : PR Photo 28a/00 is a colour composite image of the sky field around the position of the gamma-ray burst GRB 000131 that was detected on January 31, 2000. It is based on images obtained with the ESO Very Large Telescope at Paranal. The object is indicated with an arrow, near a rather bright star (magnitude 9, i.e., over 1 million times brighter than the faintest objects visible on this photo). This and other bright objects in the field are responsible for various unavoidable imaging effects, caused by optical reflections (ring-shaped "ghost images", e.g. to the left of the brightest star) and detector saturation effects (horizontal and vertical straight lines and coloured "coronae" at the bright objects, and areas of "bleeding", e.g. below the bright star). PR Photo 28b/00 shows the rapid fading of the optical counterpart of GRB 000131 (slightly left of the centre), by means of exposures with the VLT on February 4 (upper left), 6 (upper right), 8 (lower left) and March 5 (lower right). It is no longer visible on the last photo. Technical information about these photos is available below. A gamma-ray burst was detected on January 31, 2000, by an international network of satellites ( Ulysses , NEAR and Konus ) via the InterPlanetary Network (IPN) [2]. It was designated GRB 000131 according to the date of the event. From geometric triangulation by means of the measured, exact arrival times of the signal at the individual satellites, it was possible to determine the direction from which the burst came. It was found to be from a point within a comparatively small sky area (about 50 arcmin 2 or 1/10 of the apparent size of the Moon), just inside the border of the southern constellation Carina (The Keel). Follow-up observations were undertaken by a group of European astronomers [1] with the ESO Very Large Telescope at the Paranal Observatory. A comparison of several exposures with the FORS1 multi-mode instrument at the 8.2-m VLT ANTU telescope during the nights of February 3-4 and 5-6 revealed a faint, point-like object that was fading rapidly - this was identified as the optical counterpart of the gamma-ray burst (the "afterglow"). On the second night, the R-magnitude (brightness) was found to be only 24.4, or 30 million times fainter than visible with the unaided eye in a dark sky. It was also possible to observe it with a camera at the 1.54-m Danish Telescope at the La Silla Observatory , albeit only in a near-infrared band and with a 1-hour exposure. Additional observations were made on February 8 with the SOFI multi-mode instrument at the ESO 3.58-m New Technology Telescope (NTT) at La Silla. The observations were performed partly by the astronomers from the group, partly in "service mode" by ESO staff at La Silla and Paranal. The observations showed that the light from the afterglow was very red, without blue and green light. This indicated a comparatively large distance and, assuming that the light from the explosion would originally have had the same colour (spectral distribution) as that of optical counterparts of other observed gamma-ray bursts, a photometric redshift of 4.35 to 4.70 was deduced [3]. A spectrum of GRB 000131 ESO PR Photo 28c/00 ESO PR Photo 28c/00 [Preview - JPEG: 400 x 332 pix - 22k] [Normal - JPEG: 800 x 663 pix - 62k] Caption : PR Photo 28c/00 shows the spectrum of the afterglow of GRB 000131 , obtained during a 3-hr exposure with the FORS1 multi-mode instrument at VLT ANTU on February 8, 2000. The "Lyman-alpha break" at wavelength 670.1 nm is indicated. Technical information about this photo is available below. An accurate measurement of the redshift - hence the distance - requires spectroscopic observations. A spectrum of GRB 000131 was therefore obtained on February 8, 2000, cf. PR Photo 28c/00 . At this time, the brightness had decreased further and the object had become so faint (R-magnitude 25.3) that a total of 3 hours of exposure time was necessary with VLT ANTU + FORS1 [4]. Still, this spectrum is quite "noisy". The deduced photometric redshift of GRB 000131 predicts that a "break" will be seen in the red region of the spectrum, at a wavelength somewhere between 650 and 700 nm. This break is caused by the strong absorption of light in intergalactic hydrogen clouds along the line of sight. The effect is known as the "Lyman-alpha forest" and is observed in all remote objects [5]. As PR Photo 28c/00 shows, such a break was indeed found at wavelength 670.1 nm. Virtually all light at shorter wavelengths from the optical counterpart of GRB 000131 is absorbed by intervening hydrogen clouds. From the rest wavelength of the Lyman-alpha break (121.6 nm), the redshift of GRB 000131 is then determined as 4.50, corresponding to a travel time of more than 90% of the age of the Universe . The most distant gamma-ray burst so far The measured redshift of 4.50 makes GRB 000131 the most distant gamma-ray burst known (the previous, spectroscopically confirmed record was 3.42). Assuming an age of the Universe of the order of 12 - 14,000 million years, the look-back time indicates that the explosion took place around the time our own galaxy, the Milky Way, was formed and at least 6,000 million years before the solar system was born. GRB 000131 and other gamma-ray bursts are believed to have taken place in remote galaxies. However, due to the huge distance, it has not yet been possible to see the galaxy in which the GRB 000131 event took place (the "host" galaxy). From the observed fading of the afterglow it is possible to estimate that the maximum brightness of this explosion was at least 10,000 times brighter than the host galaxy. Future studies of gamma-ray bursts The present team of astronomers has now embarked upon a detailed study of the surroundings of GRB 000131 with the VLT. A main goal is to observe the properties of the host galaxy. From the observations of about twenty optical counterparts of gamma-ray bursts identified until now, it is becoming increasingly clear that these very rare events are somehow related to the death of massive, short-lived stars . But despite the accumulating amount of excellent data, the details of the mechanism that leads to such dramatic explosions still remain a puzzle to astrophysicists. The detection and present follow-up observations of GRB 000131 highlight the new possibilities for studies of the extremely distant (and very early) Universe, now possible by means of gamma-ray bursts. When observed with the powerful instruments at a large ground-based telescope like the VLT, this incredibly bright class of cosmological objects may throw light on the fundamental processes of star formation in the infant universe. Of no less interest is the opportunity to analyse the chemical composition of the gas clouds at the epoch galaxies formed, by means of the imprints of the corresponding absorption lines on the afterglow spectrum. Waiting for the opportunity In this context, it would be extremely desirable to obtain very detailed (high-dispersion) spectra of the afterglow of a future gamma-ray burst, soon after the detection and while it is still sufficiently bright. It would for instance be possible to observe a gamma-ray burst like GRB 000131 with the UVES spectrograph at VLT KUEYEN at the moment of maximum brightness (that may have been about magnitude 16). An example of chemical studies of clouds at intermediate distance by means of a more nearby quasar is shown in ESO PR Photo 09h/00. Attempts are therefore now made to shorten considerably the various steps needed to perform such observations. This concerns especially the time needed to identify the counterpart of a gamma-ray burst and - to a lesser extent - the necessary reaction time at the VLT to point UVES towards the object (in theory, a matter of minutes only). The launch of the HETE-2 (High Energy Transient Explorer 2) gamma-ray burst satellite on October 9, 2000, is a major step in this direction. Under optimal conditions, a relative accurate sky position of a gamma-ray burst may henceforth reach the astronomy community within only 10-20 seconds of the first detection by this satellite. More information The research described in this press release is the subject of a scientific article by the team, entitled "VLT Identification of the optical afterglow of the gamma-ray burst GRB 000131 at z = 4.50" ; it will appear in a special VLT-issue (Letters to the Editor) of the European journal Astronomy & Astrophysics (December 1, 2000). The results are being presented today (October 18) at the joint CNR/ESO meeting on "Gamma-Ray Burst in the Afterglow Era" in Rome, Italy. Note also the related article in the ESO Messenger (No. 100, p. 32, June 2000). Notes [1]: The team consists of Michael Andersen (University of Oulu, Finland), Holger Pedersen, Jens Hjorth, Brian Lindgren Jensen, Lisbeth Fogh Olsen, Lise Christensen (University of Copenhagen, Denmark), Leslie Hunt (Centro per l'Astronomia Infrarossa e lo Studio del Mezzo, Florence, Italy), Javier Gorosabel (Danish Space Research Institute, Denmark), Johan Fynbo, Palle Møller (European Southern Observatory), Richard Marc Kippen (University of Alabama in Huntsville and NASA/Marshall Space Flight Center, USA), Bjarne Thomsen (University of Århus, Denmark), Marianne Vestergaard (Ohio State University, USA), Nicola Masetti, Eliana Palazzi (Instituto Tecnologie e Studio Radiazoni Extraterresti, Bologna, Italy) Kevin Hurley (University of California, Berkeley, USA), Thomas Cline (NASA Goddard Space Flight Center, Greenbelt, USA), Lex Kaper (Sterrenkundig Instituut ``Anton Pannekoek", the Netherlands) and Andreas O. Jaunsen (formerly University of Oslo, Norway; now ESO-Paranal). [2]: Detailed reports about the early observations of this gamma-ray burst are available at the dedicated webpage within the GRB Coordinates Network website. [3]: The photometric redshift method makes it possible to judge the distance to a remote celestial object (a galaxy, a quasar, a gamma-ray burst afterglow) from its measured colours. It is based on the proportionality between the distance and the velocity along the line of sight (Hubble's law) that reflects the expansion of the Universe. The larger the distance of an object is, the larger is its velocity and, due to the Doppler effect, the spectral shift of its emission towards longer (redder) wavelengths. Thus, the measured colour provides a rough indication of the distance. Examples of this method are shown in ESO PR 20/98 (Photos 48a/00 and 48e/00). [4]: In fact, the object was so faint that the positioning of the spectrograph slit had to be done in "blind" offset, i.e. without actually seeing the object on the slit during the observation. This very difficult observational feat was possible because of excellent preparations by the team of astronomers and the very good precision of the telescope and instrument. [5]: The " Lyman-alpha forest" refers to the crowding of absorption lines from intervening hydrogen clouds, shortward of the strong Lyman-alpha spectral line at rest wavelength 121.6 nm. Good examples in the VLT ANTU + FORS1 spectra of distant quasars are shown in ESO PR Photos 14a-c/99 and, at much higher dispersion, in a spectrum obtained with VLT KUEYEN + UVES, cf. ESO PR 08/00 (Photo 09f/00). Technical information about the photos PR Photo 28a/00 : The photo is based on three 8-min exposures obtained with VLT ANTU and the multi-mode FORS1 instrument. The optical filters were B (seeing 0.9 arcsec; here rendered as blue), V (0.8 arcsec; green) and R (0.7 arcsec; red). The field measures 6.8 x 6.8 arcmin 2. North is up and East is left. PR Photo 28b/00 : The four R-exposures were obtained with VLT ANTU + FORS1 on February 4 (magnitude R = 23.3), 6 (24.4), 8 (25.1) and March 5 (no longer visible). The field measures 48 x 48 arcsec 2. North is up and East is left. PR Photo 28c/00 : The spectrum was obtained during a 3-hr exposure with the FORS1 multi-mode instrument at VLT ANTU on February 8, 2000, when the object's magnitude was only R = 25.3. The mean levels of the spectral continua on either side of the redshifted "Lyman-alpha break" at wavelength 670.1 nm are indicated.

  4. GROSS- GAMMA RAY OBSERVATORY ATTITUDE DYNAMICS SIMULATOR

    NASA Technical Reports Server (NTRS)

    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 ASSEMBLER and has been implemented on a VAX 11/780 under VMS 4.5. It has a virtual memory requirement of 255k. GROSS was developed in 1986.

  5. Enhanced detection of terrestrial gamma-ray flashes by AGILE

    NASA Astrophysics Data System (ADS)

    Marisaldi, M.; Argan, A.; Ursi, A.; Gjesteland, T.; Fuschino, F.; Labanti, C.; Galli, M.; Tavani, M.; Pittori, C.; Verrecchia, F.; D'Amico, F.; Østgaard, N.; Mereghetti, S.; Campana, R.; Cattaneo, P. W.; Bulgarelli, A.; Colafrancesco, S.; Dietrich, S.; Longo, F.; Gianotti, F.; Giommi, P.; Rappoldi, A.; Trifoglio, M.; Trois, A.

    2015-11-01

    At the end of March 2015 the onboard software configuration of the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite was modified in order to disable the veto signal of the anticoincidence shield for the minicalorimeter instrument. The motivation for such a change was the understanding that the dead time induced by the anticoincidence prevented the detection of a large fraction of Terrestrial Gamma-Ray Flashes (TGFs). The configuration change was highly successful resulting in an increase of one order of magnitude in TGF detection rate. As expected, the largest fraction of the new events has short duration (<100 μs), and part of them has simultaneous association with lightning sferics detected by the World Wide Lightning Location Network. The new configuration provides the largest TGF detection rate surface density (TGFs/km2/yr) to date, opening prospects for improved correlation studies with lightning and atmospheric parameters on short spatial and temporal scales along the equatorial region.

  6. Precision Gamma-Ray Spectroscopy at the Institut Laue Langevin

    SciTech Connect

    Boerner, H. G.

    2006-03-13

    Currently the Institut Laue-Langevin follows two main experimental issues in the ILL nuclear physics studies. In the first one thermal neutron capture is used to excite nuclei up to the binding energy. Subsequently emitted gamma rays are characterized with ultra-high precision using the crystal spectrometers GAMS. In the second one, neutron-induced fission allows the study of the structure of heavy neutron-rich isotopes using the LOHENGRIN recoil mass separator. Most of today's measurements at ILL are done using the in-pile target arrangements of these two instruments, but some work is also carried out with neutrons at external positions fed by neutron guides. We will present an overview on the current status of the various experimental approaches and discuss the results and applications of a selected set of measurements.

  7. Gamma ray spectrometry of LDEF samples at SRS

    NASA Technical Reports Server (NTRS)

    Winn, Willard G.

    1991-01-01

    A total of 31 samples from Long Duration Exposure Facility (LDEF), including materials of Al, V, and steel trunnions were analyzed by ultralow level gamma spectrometry. The study quantified particle induced activations of Na-22, Sc-46, Cr-51, Mn-54, Co-56, Co-57, Co-58, and Co-60. The samples of trunnion sections exhibited increasing activity toward the outer end of the trunnion and decreasing activity toward its radial center. The trunnion sections did not include an end piece that collects noticeable Be-7 on its leading surface. No significant Be-7 was detected in the samples analyzed. The most sensitive analyses were performed with a 90 pct. efficient HPGe gamma ray detector, which is enclosed in a purged active/passive active shield.

  8. Search for PEV Gamma Rays with the Kascade Experiment

    NASA Astrophysics Data System (ADS)

    Fessler, F.; KASCADE Collaboration

    2001-08-01

    Data observed with the KASCADE extensive air shower experiment have been analyzed with respect to a possible contribution by primary gamma rays in the energy range of 0.3 to 10 PeV. The study makes use of the good definition of electron and muon numbers by the experiment. Possible gamma induced events are mainly identified by their low muon to electron ratios but, in addition, the steepness and smoothness of the electron lateral distributions are exploited. No positive identifications can be claimed but our results confirm and, in the lower part of the energy range, improve upper limits of a possible gamma contribution made by previous experiments. The distribution on the sky of the 53 most 'gamma-like' events out of a sample of 13.6 million events is indistinguishable from that of all the events registered. The results are based on a measurement time of approximately half a year.

  9. Air pollution induces heritable DNA mutations

    PubMed Central

    Somers, Christopher M.; Yauk, Carole L.; White, Paul A.; Parfett, Craig L. J.; Quinn, James S.

    2002-01-01

    Hundreds of thousands of people worldwide live or work in close proximity to steel mills. Integrated steel production generates chemical pollution containing compounds that can induce genetic damage (1, 2). Previous investigations of herring gulls in the Great Lakes demonstrated elevated DNA mutation rates near steel mills (3, 4) but could not determine the importance of airborne or aquatic routes of contaminant exposure, or eliminate possible confounding factors such as nutritional status and disease burden. To address these issues experimentally, we exposed laboratory mice in situ to ambient air in a polluted industrial area near steel mills. Heritable mutation frequency at tandem-repeat DNA loci in mice exposed 1 km downwind from two integrated steel mills was 1.5- to 2.0-fold elevated compared with those at a reference site 30 km away. This statistically significant elevation was due primarily to an increase in mutations inherited through the paternal germline. Our results indicate that human and wildlife populations in proximity to integrated steel mills may be at risk of developing germline mutations more frequently because of the inhalation of airborne chemical mutagens. PMID:12473746

  10. Short Gamma-Ray Bursts Are Different

    NASA Astrophysics Data System (ADS)

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

    We analyze BATSE time-tagged event (TTE) data for short gamma-ray bursts (T 90 duration < 2.6 s), studying spectral lag vs. peak flux and duration, as well as the number of distinct pulse structures per burst. Performing the cross-correlation between two energy bands, we measure an average lag 20-40 x shorter than for long bursts, and a lag distribution close to symmetric about zero - unlike long bursts. Using a "Bayesian Block" method to identify significantly distinct pulse peaks, we find an order of magnitude fewer pulses than found in studies of long bursts. The disparity in lag magnitude is discontinuous across the 2-s valley between long and short bursts. Thus, short bursts do not appear to be representable as a continuation of long bursts' temporalc haracteristics.

  11. Gamma-ray pulsars: A gold mine

    NASA Astrophysics Data System (ADS)

    Grenier, Isabelle A.; Harding, Alice K.

    2015-08-01

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

  12. Directional detector of gamma ray sources.

    PubMed

    Kronenberg, S; Bruckner, G J; Bechtel, E; Gentner, F

    1996-04-01

    This work describes the design, development, and characterization of an ionization chamber to detect and locate gamma ray sources with intensities down to 100 mu Gy h(-1). The results show that sources of x ray and gamma radiation in the energy range of 14 to 1,250 keV can be located. The directional sensitivity of this type of monitor is dependent on several parameters, such as photon energy, intensity, and the degree of complexity in terms of the number and type of sources in a contaminated area. An application important to the Army is to identify hotspots in a contaminated area and thereby indicate to personnel safer paths around them. Another possible use for this type of monitor may be in security applications in the prevention of shipping or storing clandestine sources. PMID:8617590

  13. The Swift Gamma-Ray Burst Mission

    NASA Astrophysics Data System (ADS)

    Gehrels, N.; Chincarini, G.; Giommi, P.; Mason, K. O.; Nousek, J. A.; Wells, A. A.; White, N. E.; Barthelmy, S. D.; Burrows, D. N.; Cominsky, L. R.; Hurley, K. C.; Marshall, F. E.; Mészáros, P.; Roming, P. W. A.; Angelini, L.; Barbier, L. M.; Belloni, T.; Campana, S.; Caraveo, P. A.; Chester, M. M.; Citterio, O.; Cline, T. L.; Cropper, M. S.; Cummings, J. R.; Dean, A. J.; Feigelson, E. D.; Fenimore, E. E.; Frail, D. A.; Fruchter, A. S.; Garmire, G. P.; Gendreau, K.; Ghisellini, G.; Greiner, J.; Hill, J. E.; Hunsberger, S. D.; Krimm, H. A.; Kulkarni, S. R.; Kumar, P.; Lebrun, F.; Lloyd-Ronning, N. M.; Markwardt, C. B.; Mattson, B. J.; Mushotzky, R. F.; Norris, J. P.; Osborne, J.; Paczynski, B.; Palmer, D. M.; Park, H.-S.; Parsons, A. M.; Paul, J.; Rees, M. J.; Reynolds, C. S.; Rhoads, J. E.; Sasseen, T. P.; Schaefer, B. E.; Short, A. T.; Smale, A. P.; Smith, I. A.; Stella, L.; Tagliaferri, G.; Takahashi, T.; Tashiro, M.; Townsley, L. K.; Tueller, J.; Turner, M. J. L.; Vietri, M.; Voges, W.; Ward, M. J.; Willingale, R.; Zerbi, F. M.; Zhang, W. W.

    2004-08-01

    The Swift mission, scheduled for launch in 2004, is a multiwavelength observatory for gamma-ray burst (GRB) astronomy. It is a first-of-its-kind autonomous rapid-slewing satellite for transient astronomy and pioneers the way for future rapid-reaction and multiwavelength missions. It will be far more powerful than any previous GRB mission, observing more than 100 bursts yr-1 and performing detailed X-ray and UV/optical afterglow observations spanning timescales from 1 minute to several days after the burst. The objectives are to (1) determine the origin of GRBs, (2) classify GRBs and search for new types, (3) study the interaction of the ultrarelativistic outflows of GRBs with their surrounding medium, and (4) use GRBs to study the early universe out to z>10. The mission is being developed by a NASA-led international collaboration. It will carry three instruments: a new-generation wide-field gamma-ray (15-150 keV) detector that will detect bursts, calculate 1'-4' positions, and trigger autonomous spacecraft slews; a narrow-field X-ray telescope that will give 5" positions and perform spectroscopy in the 0.2-10 keV band; and a narrow-field UV/optical telescope that will operate in the 170-600 nm band and provide 0.3" positions and optical finding charts. Redshift determinations will be made for most bursts. In addition to the primary GRB science, the mission will perform a hard X-ray survey to a sensitivity of ~1 mcrab (~2×10-11 ergs cm-2 s-1 in the 15-150 keV band), more than an order of magnitude better than HEAO 1 A-4. A flexible data and operations system will allow rapid follow-up observations of all types of high-energy transients, with rapid data downlink and uplink available through the NASA TDRSS system. Swift transient data will be rapidly distributed to the astronomical community, and all interested observers are encouraged to participate in follow-up measurements. A Guest Investigator program for the mission will provide funding for community involvement. Innovations from the Swift program applicable to the future include (1) a large-area gamma-ray detector using the new CdZnTe detectors, (2) an autonomous rapid-slewing spacecraft, (3) a multiwavelength payload combining optical, X-ray, and gamma-ray instruments, (4) an observing program coordinated with other ground-based and space-based observatories, and (5) immediate multiwavelength data flow to the community. The mission is currently funded for 2 yr of operations, and the spacecraft will have a lifetime to orbital decay of ~8 yr.

  14. Do gamma-ray burst sources repeat?

    NASA Technical Reports Server (NTRS)

    Meegan, Charles A.; Hartmann, Dieter H.; Brainerd, J. J.; Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey; Kouveliotou, Chryssa; Fishman, Gerald; Blumenthal, George; Brock, Martin

    1995-01-01

    The demonstration of repeated gamma-ray bursts from an individual source would severely constrain burst source models. Recent reports (Quashnock and Lamb, 1993; Wang and Lingenfelter, 1993) of evidence for repetition in the first BATSE burst catalog have generated renewed interest in this issue. Here, we analyze the angular distribution of 585 bursts of the second BATSE catalog (Meegan et al., 1994). We search for evidence of burst recurrence using the nearest and farthest neighbor statistic and the two-point angular correlation function. We find the data to be consistent with the hypothesis that burst sources do not repeat; however, a repeater fraction of up to about 20% of the observed bursts cannot be excluded.

  15. Gamma-ray imaging with Compton cameras

    NASA Astrophysics Data System (ADS)

    Phillips, Gary W.

    1995-05-01

    Compton cameras use the kinematics of Compton scattering to construct a source image without the use of collimators or masks. Compton telescopes were first built in the 1970s for astronomical observations. The first laboratory instrument was designed for medical imaging. Recently, three dimensional imaging has been demonstrated using an array of high resolution germanium detectors for characterization of mixed radioactive waste containers. Image resolution depends on the detector accuracy in both energy and position and on the image reconstruction algorithm. Advantages of Compton imaging include a wide field of view, background suppression, the ability to image high energy gamma rays (up to 10 MeV) and the ability to obtain three dimensional images from a fixed position on one side of the source without the need for tomography. The operation of Compton cameras will be reviewed along with recent results and future prospects.

  16. Fundamental Physics with GEV Gamma Rays

    NASA Astrophysics Data System (ADS)

    Profumo, S.

    2010-12-01

    Can we learn about New Physics with astronomical and astro-particle data? Understanding how this is possible is key to unraveling one of the most pressing mysteries at the interface of cosmology and particle physics: the fundamental nature of dark matter. Rapid progress may be within grasp in the context of an approach which combines information from high-energy particle physics with cosmic-ray and traditional astronomical data. I discuss how modifications to the pair annihilation cross section of dark matter with enhanced rates at low relative velocities can lead to a burst of annihilation in the first dark matter halos. I then introduce a novel approach to particle dark matter searches based on the complementarity of astronomical observations across the electromagnetic spectrum, from radio to X-ray and to gamma-ray frequencies.

  17. Gravitational wave: gamma-ray burst connections.

    PubMed

    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. PMID:17293333

  18. Very high energy gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Grindlay, J. E.

    1976-01-01

    Recent results in ground based very high energy gamma ray astronomy are reviewed. The various modes of the atmospheric Cerenkov technique are described, and the importance of cosmic ray rejection methods is stressed. The positive detections of the Crab pulsar that suggest a very flat spectrum and time-variable pulse phase are discussed. Observations of other pulsars (particularly Vela) suggest these features may be general. Evidence that a 4.8 hr modulated effect was detected from Cyg X-3 is strengthened in that the exact period originally proposed agrees well with a recent determination of the X-ray period. The southern sky observations are reviewed, and the significance of the detection of an active galaxy (NGC 5128) is considered for source models and future observations.

  19. A coded aperture gamma ray telescope

    NASA Technical Reports Server (NTRS)

    Mcconnell, M. L.; Forrest, D. J.; Chupp, E. L.; Dunphy, P. P.

    1982-01-01

    A gamma ray telescope is being developed to operate in the energy range 100 keV to 5 MeV, utilizing coded aperture imaging. The design incorporates a mask pattern based on a Uniformly Redundant Array (URA), which has been shown to have ideal imaging characteristics. A mask-anti-mask procedure is used to eliminate the effects of any possible systematic variations in detector background rates. The detector array is composed of 35 elements of the high-Z material Bismuth Germanate (BGO). Results of laboratory testing of the imaging properties will be presented. A southern hemisphere balloon flight is planned for 1982 with the goal of observing the 0.511 MeV radiation from the Galactic Center. Computer calculations show that a point source of this radiation can be located to within + or - 1 deg.

  20. The Swift Gamma Ray Burst Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Chincarini, G.; Giommi, P.; Mason, K. O.; Nousek, J. A.; Wells, A. A.; White, N. E.; Barthelmy, S. D.; Burrows, D. N.; Cominsky, L. R.

    2004-01-01

    The Swift mission: scheduled for launch in early 2004: is a multiwavelength observatory for gamma-ray burst (GRB) astronomy. It is the first-of-its-kind autonomous rapid-slewing satellite for transient astronomy and pioneers the way for future rapid-reaction and multiwavelength missions. It will be far more powerful than any previous GRB mission, observing more than 100 bursts per year and performing detailed X-ray and UV/optical afterglow observations spanning timescales from 1 minute to several days after the burst. The objectives are to: 1) determine the origin of GFU3s; 2) classify GRBs and search for new types; 3) study the interaction of the ultra-relativistic outflows of GRBs with their surrounding medium; and 4) use GRBs to study the early universe out to z greater than 10. The mission is being developed by a NASA-led international collaboration. It will carry three instruments: a new-generation wide-field gamma-ray (15-150 keV) detector that will detect bursts, calculate 1-4 arcmin positions: and trigger autonomous spacecraft slews; a narrow-field X-ray telescope that will give 5 arcsec positions and perform spectroscopy in the 0.2 to 10 keV band; and a narrow-field UV/optical telescope that will operate in the 170-600 nm band and provide 0.3 arcsec positions and optical finding charts. Redshift determinations will be made for most bursts. In addition to the primary GRB science, the mission will perform a hard X-ray survey to a sensitivity of approx. 1 mCrab (approx. 2 x l0(exp -11) erg/sq cm s in the 15-150 keV band), more than an order of magnitude better than HEAO A-4. A flexible data and operations system will allow rapid follow-up observations of all types of high-energy transients. with rapid data downlink and uplink available through the NASA TDRSS system. Swift transient data will be rapidly distributed to the astronomical community and all interested observers are encouraged to participate in follow-up measurements. A Guest Investigator program for the mission will provide funding for community involvement. Innovations from the Swift program applicable to the future include: 1) a large-area gamma-ray detector us- ing the new CdZnTe detectors; 2) an autonomous rapid slewing spacecraft; 3) a multiwavelength payload combining optical, X-ray, and gamma-ray instruments; 4) an observing program coordinated with other ground-based and space-based observatories; and 5) immediate multiwavelength data flow to the community. The mission is currently funded for 2 years of operations and the spacecraft will have a lifetime to orbital decay of approx. 8 years.

  1. Nuclear gamma rays from stellar flares

    NASA Technical Reports Server (NTRS)

    Colgate, S. A.

    1978-01-01

    Solar flare observations are consistent with the phenomenological description that a loop of magnetic flux is convected to the surface of the star and twisted. The resulting inductive current parallel to the field is dissipated at an enhanced rate throughout the field volume by current limiting instabilities. The steady state balance between joule heating and thermal conduction along the field lines of force to the denser, cooler surface establishes a temperature distribution. The expansion of heated and ionized surface layers leads to a pressure balance and hence predictable density and X-ray emission measure. The current limitation instabilities result observationally in the parallel current being transferred to run-away ions that reach a kinetic energy of some finite fraction of the inductive potential drop. The nuclear excitation gamma rays produced by such a run-away ion current are calculated for a white dwarf flare.

  2. Pulsar gamma rays from polar cap regions

    NASA Technical Reports Server (NTRS)

    Chiang, James; Romani, Roger W.

    1992-01-01

    The production is studied of pulsar gamma rays by energetic electrons flowing in the open field region above pulsar polar caps. The propagation was followed of curvature radiation from primary electrons, as well as hard synchrotron radiation generated by secondary pairs, through the pulsar magnetosphere for vacuum dipole open field geometries. Using data from radio and optical observations, models were constructed for the specific geometries and viewing angles appropriate to particular pulsars. These detailed models produce normalized spectra above 10 MeV, pulse profiles, beaming fractions and phase resolved spectra appropriate for direct comparison with COS-B and GRO data. Models are given for the Crab, Vela, and other potentially detectable pulsars; general agreement with existing data is good, although perturbations to the simplified models are needed for close matches. The calculations were extended to the millisecond pulsar range, which allows the production of predictions for the flux and spectra of populations of recycled pulsars and search strategies are pointed out.

  3. The Chase to Capture Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2008-01-01

    Gamma-ray bursts are the most powerful explosions in the universe, thought to be the birth cries of black holes. It has taken 40 years of international cooperation and competition to begin to unravel the mystery of their origin. The most recent chapter in this field is being written by the SWIFT mission, a fast-response satellite with 3 power telescopes. An international team from countries all over the world participates in the chase to capture the fading light of bursts detected by SWIFT. This talk will discuss the challenges and excitement of building this space observatory. New results will be presented on our growing understanding of exploding stars and fiery mergers of orbiting stars.

  4. A Compton scatter attenuation gamma ray spectrometer

    NASA Technical Reports Server (NTRS)

    Austin, W. E.

    1972-01-01

    A Compton scatter attenuation gamma ray spectrometer conceptual design is discussed for performing gamma spectral measurements in monodirectional gamma fields from 100 R per hour to 1,000,000 R per hour. Selectable Compton targets are used to scatter gamma photons onto an otherwise heavily shielded detector with changeable scattering efficiencies such that the count rate is maintained between 500 and 10,000 per second. Use of two sum-Compton coincident detectors, one for energies up to 1.5 MeV and the other for 600 keV to 10 MeV, will allow good peak to tail pulse height ratios to be obtained over the entire spectrum and reduces the neutron recoil background rate.

  5. Digital logarithmic airborne gamma ray spectrometer

    NASA Astrophysics Data System (ADS)

    Zeng, Guo-Qiang; Zhang, Qing-Xian; Li, Chen; Tan, Cheng-Jun; Ge, Liang-Quan; Gu, Yi; Cheng, Feng

    2014-07-01

    A new digital logarithmic airborne gamma ray spectrometer is designed in this study. The spectrometer adopts a high-speed and high-accuracy logarithmic amplifier (LOG114) to amplify the pulse signal logarithmically and to improve the utilization of the ADC dynamic range because the low-energy pulse signal has a larger gain than the high-energy pulse signal. After energy calibration, the spectrometer can clearly distinguish photopeaks at 239, 352, 583 and 609 keV in the low-energy spectral sections. The photopeak energy resolution of 137Cs improves to 6.75% from the original 7.8%. Furthermore, the energy resolution of three photopeaks, namely, K, U, and Th, is maintained, and the overall stability of the energy spectrum is increased through potassium peak spectrum stabilization. Thus, it is possible to effectively measure energy from 20 keV to 10 MeV.

  6. LONG GAMMA-RAY TRANSIENTS FROM COLLAPSARS

    SciTech Connect

    Woosley, S. E.; Heger, Alexander E-mail: alex@physics.umn.edu

    2012-06-10

    In the collapsar model for common gamma-ray bursts (GRBs), the formation of a centrifugally supported disk occurs during the first {approx}10 s following the collapse of the iron core in a massive star. This only occurs in a small fraction of massive stellar deaths, however, and requires unusual conditions. A much more frequent occurrence could be the death of a star that makes a black hole and a weak or absent outgoing shock, but in a progenitor that only has enough angular momentum in its outermost layers to make a disk. We consider several cases where this is likely to occur-blue supergiants with low mass-loss rates, tidally interacting binaries involving either helium stars or giant stars, and the collapse to a black hole of very massive pair-instability supernovae. These events have in common the accretion of a solar mass or so of material through a disk over a period much longer than the duration of a common GRB. A broad range of powers is possible, 10{sup 47}-10{sup 50} erg s{sup -1}, and this brightness could be enhanced by beaming. Such events were probably more frequent in the early universe where mass-loss rates were lower. Indeed, this could be one of the most common forms of gamma-ray transients in the universe and could be used to study first generation stars. Several events could be active in the sky at any one time. Recent examples of this sort of event may have been the Swift transients Sw-1644+57, Sw-2058+0516, and GRB 101225A.

  7. Gamma-Ray Bursts: Pulses and Populations

    NASA Astrophysics Data System (ADS)

    Loredo, Thomas J.; Hakkila, J. E.; Broadbent, M.; Wasserman, I. M.; Wolpert, R. L.

    2013-04-01

    We describe ongoing work on two projects that are enabling more thorough and accurate use of archival BATSE data for elucidating the nature of GRB sources; the methods and tools we are developing will also be valuable for analyzing data from other missions. The first project addresses modeling the spectro-temporal behavior of prompt gamma ray emission from GRBs by modeling gamma ray count and event data with a population of pulses, with the population drawn from one or more families of single-pulse kernels. Our approach is built on a multilevel nonparametric probabilistic framework we have dubbed "Bayesian droplets," and offers several important advances over previous pulse decomposition approaches: (1) It works in the pulse-confusion regime, quantifying uncertainty in the number, locations, and shapes of pulses, even when there is strong overlap. (2) It can self-consistently model pulse behavior across multiple spectral bands. (3) It readily handles a variety of spatio-temporal kernel shapes. (4) It reifies the idea of a burst as a population of pulses, enabling explicit modeling and estimation of the pulse population distribution. We describe the framework and present analyses of prototypical simple and complex GRB light curves. The second project aims to enable accurate demographic modeling of GRBs using the BATSE catalog. We present new calculations of the BATSE sky exposure, encompassing the full duration of the BATSE catalog for the first time, with many improvements over the currently available exposure map. A similar calculation of the detection efficiency is in progress. We also describe public Python software enabling access and accurate modeling of BATSE GRB data. The software enables demographic studies (e.g., modeling log N - log S distributions) with accurate accounting of both selection effects and measurement errors. It also enables spectro-temporal modeling of detailed data from individual GRBs. These projects are supported by NASA through the AISR and ADAP programs.

  8. Long Gamma-Ray Transients from Collapsars

    NASA Astrophysics Data System (ADS)

    Woosley, S. E.; Heger, Alexander

    2012-06-01

    In the collapsar model for common gamma-ray bursts (GRBs), the formation of a centrifugally supported disk occurs during the first ~10 s following the collapse of the iron core in a massive star. This only occurs in a small fraction of massive stellar deaths, however, and requires unusual conditions. A much more frequent occurrence could be the death of a star that makes a black hole and a weak or absent outgoing shock, but in a progenitor that only has enough angular momentum in its outermost layers to make a disk. We consider several cases where this is likely to occur—blue supergiants with low mass-loss rates, tidally interacting binaries involving either helium stars or giant stars, and the collapse to a black hole of very massive pair-instability supernovae. These events have in common the accretion of a solar mass or so of material through a disk over a period much longer than the duration of a common GRB. A broad range of powers is possible, 1047-1050 erg s-1, and this brightness could be enhanced by beaming. Such events were probably more frequent in the early universe where mass-loss rates were lower. Indeed, this could be one of the most common forms of gamma-ray transients in the universe and could be used to study first generation stars. Several events could be active in the sky at any one time. Recent examples of this sort of event may have been the Swift transients Sw-1644+57, Sw-2058+0516, and GRB 101225A.

  9. AGILE and Gamma-Ray Bursts

    SciTech Connect

    Longo, Francesco; Tavani, M.; Barbiellini, G.; Argan, A.; Basset, M.; Boffelli, F.; Bulgarelli, A.; Caraveo, P.; Cattaneo, P.; Chen, A.; Costa, E.; Del Monte, E.; Di Cocco, G.; Di Persio, G.; Donnarumma, I.; Feroci, M.; Fiorini, M.; Foggetta, L.; Froysland, T.; Frutti, M.

    2006-05-19

    AGILE is a Scientific Mission dedicated to high-energy astrophysics supported by ASI with scientific participation of INAF and INFN. The AGILE instrument is designed to simultaneously detect and image photons in the 30 MeV - 50 GeV and 15 - 45 keV energy bands with excellent imaging and timing capabilities, and a large field of view covering {approx} 1/5 of the entire sky at energies above 30 MeV. A CsI calorimeter is capable of GRB triggering in the energy band 0.3-50 MeV. The broadband detection of GRBs and the study of implications for particle acceleration and high energy emission are primary goals of th emission. AGILE can image GRBs with 2-3 arcminutes error boxes in the hard X-ray range, and provide broadband photon-by photon detection in the 15-45 keV, 03-50 MeV, and 30 MeV-30 GeV energy ranges. Microsecond on-board photon tagging and a {approx} 100 microsecond gamma-ray detection deadtime will be crucial for fast GRB timing. On-board calculated GRB coordinates and energy fluxes will be quickly transmitted to the ground by an ORBCOMM transceiver. AGILE have recently (December 2005) completed its gamma-ray calibration. It is now (January 2006) undergoing satellite integration and testing. The PLSV launch is planned in early 2006. AGILE is then foreseen to be fully operational during the summer of 2006. It will be the only mission entirely dedicated to high-energy astrophysics above 30 MeV during the period mid-2006/mid-2007.

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

    SciTech Connect

    Lane, Taylor; Parma, Edward J.

    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.

  11. The sensitivity of EGRET to gamma-ray polarization

    NASA Technical Reports Server (NTRS)

    Mattox, John R.

    1991-01-01

    A Monte Carlo simulation shows that the EGRET gamma-ray telescope aboard the GRO satellite does not have sufficient sensitivity to detect linear polarization, even for 100-percent polarized gamma-ray sources. This is confirmed by analysis of calibration data. Several data selection techniques suggested to enhance polarization sensitivity have been evaluated and found to not significantly improve sensitivity.

  12. Enhanced gamma-ray activity from the Crab nebula

    NASA Astrophysics Data System (ADS)

    Buehler, R.; Ciprini, S.

    2016-01-01

    Preliminary LAT analysis indicates enhanced gamma-ray activity from the Crab nebula. The daily-averaged gamma-ray emission (E > 100 MeV) from the direction of the Crab Nebula has surpassed 4.0 x 10^-6 ph cm^-2 s^-1 five times in the last 12 days.

  13. QUALITY CONTROL FOR ENVIRONMENTAL MEASUREMENTS USING GAMMA-RAY SPECTROMETRY

    EPA Science Inventory

    This report describes the quality control procedures, calibration, collection, analysis, and interpretation of data in measuring the activity of gamma ray-emitting radionuclides in environmental samples. Included in the appendices are basic data for selected gamma ray-emitting ra...

  14. Solving the Mystery of Short Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2006-01-01

    Gamma-ray bursts are among the most fascinating occurrences in the cosmos. Until this year, the origin of short gamma-ray bursts was a complete mystery. A new NASA satellite named Swift has now captured the first images of these events and found that they are caused by tremendous explosions in the distant universe.

  15. Discoveries by the Fermi Gamma Ray Space Telescope

    NASA Technical Reports Server (NTRS)

    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.

  16. A comment on gamma ray lines from He-4

    NASA Technical Reports Server (NTRS)

    Kozlovsky, B.; Ramaty, R.

    1974-01-01

    It is pointed out that excited states of He-4 cannot produce gamma ray line emission of astrophysical significance, contrary to a recent suggestion of Reina et al. (1974). The only possible gamma-ray lines in He-4 are above 25 MeV, but their excitation cross sections appear to be so small that they are probably of little astrophysical significance.

  17. Gamma rays from accretion onto rotating black holes

    NASA Technical Reports Server (NTRS)

    Collins, M. S.

    1978-01-01

    Ionized matter falling onto an isolated, rotating black hole will be heated sufficiently that proton-proton collisions will produce mesons, including neutral pions, which decay into gamma rays. For massive (1000 M sub circled dot), black holes, the resulting gamma-ray luminosity may exceed 10 to the 36th power engs/s, with a spectrum peaked near 20 MeV.

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

    NASA Technical Reports Server (NTRS)

    Meegan, Charles A.

    1990-01-01

    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.

  19. Gamma Ray Astrophysics: New insight into the universe

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Trombka, J. I.

    1981-01-01

    Gamma ray observations of the solar system, the galaxy and extragalactic radiation are reported. Topics include: planets, comets, and asteroids; solar observations; interstellar medium and galactic structure; compact objects; cosmology; and diffuse radiation. The instrumentation used in gamma ray astronomy in covered along with techniques for the analysis of observational spectra.

  20. HEAO C-1 gamma-ray spectrometer. [experimental design

    NASA Technical Reports Server (NTRS)

    Mahoney, W. A.; Ling, J. C.; Willett, J. B.; Jacobson, A. S.

    1978-01-01

    The gamma-ray spectroscopy experiment to be launched on the third High Energy Astronomy Observatory (HEAO C) will perform a complete sky search for narrow gamma-ray line emission to the level of about 00001 photons/sq cm -sec for steady point sources. The design of this experiment and its performance based on testing and calibration to date are discussed.

  1. Very High Energy Gamma Ray Extension of GRO Observations

    NASA Technical Reports Server (NTRS)

    Weekes, Trevor C.

    1994-01-01

    The membership, progress, and invited talks, publications, and proceedings made by the Whipple Gamma Ray Collaboration is reported for june 1990 through May 1994. Progress was made in the following areas: the May 1994 Markarian Flare at Whipple and EGRET (Energetic Gamma Ray Experiment Telescope) energies; AGN's (Active Galactic Nuclei); bursts; supernova remnants; and simulations and energy spectra.

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

    SciTech Connect

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

    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.

  3. The Gamma-Ray Observatory mission objectives and its significance for gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Bertsch, D. L.

    1984-01-01

    The Gamma Ray Observatory (GRO) is an approved NASA mission, programmed for launch in 1988. Its complement of four detectors has established goals: (1) to study the nature of compact gamma-ray sources such as neutron stars and black holes, or objects whose nature is yet to be understood; (2) to search for evidence of nucleosynthesis especially in the regions of supernovae; (3) to study structural features and dynamical properties of the Galaxy; (4) to explore other galaxies, especially the extraordinary types such as radio, Seyferts, and quasars; and (5) to study cosmological effects by examining the diffuse radiation in detail. This paper discusses the design, objectives, and expected scientific results of each of the GRO instruments in view of the GRO mission goals.

  4. Observation of gamma-ray bursts with the SMM gamma-ray spectrometer

    NASA Technical Reports Server (NTRS)

    Share, G. H.; Strickman, M. S.; Kinzer, R. L.; Chupp, E. L.; Forrest, D. J.; Ryan, J. M.; Rieger, E.; Reppin, C.; Kanbach, G.

    1982-01-01

    The gamma-ray spectrometer on SMM is sensitive to bursts within its field of view with intensities greater than 0.000005 erg/sq cm above 100 keV. It has detected 17 events between February 1980 and March 1981 with the characteristics of cosmic gamma-ray bursts. The most intense burst, on 19 April 1980, had a photon spectrum consistent with a power law with spectral index - 2.5 from 300 keV to approximately 7 MeV. It is not possible at present to exclude the sun as the source of this burst. Spectra of 11 of the bursts have been studied for line features with no clear evidence for line emission greater than 300 keV. The continuum radiation from about half of these events have hard emission extending to approximately equal to or greater than 2 MeV.

  5. The First Fermi Gamma-ray Burst Monitor (GBM) Terrestrial Gamma-ray Flash (TGF) Catalog

    NASA Astrophysics Data System (ADS)

    Briggs, Michael; Connaughton, Valerie; Stanbro, Matthew; Zhang, Binbin; Bhat, Narayana; Fishman, Gerald; Roberts, Oliver; Fitzpatrick, Gerard; McBreen, Shelia; Grove, Eric; Chekhtman, Alexandre

    2015-04-01

    We present summary results from the first catalog of Terrestrial Gamma-ray Flashes (TGFs) detected with the Gamma-ray Burst Monitor (GBM) on the Fermi Space Telescope. The catalog reports parameters for over 2700 TGFs. Since the launch of Fermi in 2008 the TGF detection sensitivity of GBM has been improved several times, both in the flight software and in ground analysis. Starting in 2010 July individual photons were downloaded for portions of the orbits, enabling an off-line search that found weaker and shorter TGFs. Since 2012 November 26 this telemetry mode has been extended to continuous coverage. The TGF sample is reliable, with cosmic rays rejected using data both from Fermi GBM and from the Large Area Telescope on Fermi. The online catalog include times (UTC and solar), spacecraft geographic positions, durations, count intensities and Bayesian Block durations. The catalog includes separate tables for bright TGFs detected by the flight software and for Terrestrial Electron Beams (TEBs).

  6. The project EGRET (Energetic Gamma-Ray Experiment Telescope) on NASA's Gamma-Ray Observatory (GRO)

    NASA Technical Reports Server (NTRS)

    Kanbach, G.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kniffen, D. A.; Hughlock, B. W.; Favale, A.; Hofstadter, R.; Hughes, E. B.

    1988-01-01

    The design, predicted performance, and scientific objectives of the 20-30,000-MeV gamma-ray telescope EGRET for the NASA GRO spacecraft (scheduled for Space Shuttle launch to a 450-km 28.5-deg orbit in 1990) are reviewed. The other GRO instruments are briefly characterized, including the burst and transient-source experiment, the oriented scintillation spectrometer, and the imaging Compton telescope. EGRET comprises an anticoincidence system, a spark chamber, a triggering telescope, an NaI total-absorption spectrometer, a gas supply capable of refilling the chamber four times, and support electronics. EGRET will operate with energy resolution about 15 percent, effective area about 2000 sq cm, sensitivity about 5 x 10 to the -8th/sq cm sec, angular resolution 0.1-0.4 deg, and FOV about 40 deg FWHM. Observations of Galactic point sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, and solar flares are planned.

  7. Multiwavelength observations of unidentified high energy gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.

    1995-01-01

    As was the case for COS B, the majority of high-energy (greater than 100 MeV) gamma-ray sources detected by the EGRET instrument on GRO are not immediately identifiable with catalogued objects at other wavelengths. These persistent gamma-ray sources are, next to the gamma-ray bursts, the least understood objects in the universe. This two year investigation is intended to support the analysis, correlation, and theoretical interpretation of data that we are obtaining at x-ray, optical, and radio wavelengths in order to render the gamma-ray data interpretable. This second year was devoted to studies of unidentified gamma-ray sources from the first EGRET catalog, similar to previous observations. Efforts have concentrated on the sources at low and intermediate Galactic latitudes, which are the most plausible pulsar candidates.

  8. Search for medium-energy gamma-ray pulsars

    SciTech Connect

    Sweeney, W.E. Jr.

    1987-01-01

    Results are presented from a search for pulsed gamma rays from four radio pulsars, chosen for their interest to gamma-ray astronomers in previous studies. The data set used for the search consists of gamma-ray events at energies of 1-30 MeV, detected during a 40-hour balloon flight of the UCR double Compton scatter telescope launched at the National Scientific Balloon Facility in Palestine, Texas, USA on September 30, 1978. No statistically significant signals were detected from any of the pulsars. Three sigma upper limits to pulsed 1-30 MeV gamma ray flux from PSR 0950+08, PSR 1822+09, PSR 1929+10, and PSR 1953+29 are presented. Two complete exposures to PSR 0950+08 were obtained. The reported tentative detection of 1-20 MeV gamma rays from PSR 0950+08 is not confirmed.

  9. Development of the instruments for the Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Madden, J. J.; Kniffen, D. A.

    1986-01-01

    The Gamma Ray Observatory (GRO) is to be launched in 1988 by the STS. The GRO will feature four very large instruments: the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), the Energetic Gamma Ray Experiment Telescope (EGRET) and the Burst and Transient Source Experiment (BATSE). The instruments weigh from 900-1200 kg each, and required the development of specialized lifting and dolly devices to permit their assembly, manipulation and testing. The GRO is intended a{s a tool for studying discrete celestial objects such as black holes, neutron stars and other gamma-ray emitting objects, scanning for nucleosynthesis processes, mapping the Galaxy and other, high energy galaxies in terms of gamma rays, searching for cosmological effects and observing gamma ray bursts. The instruments will be sensitive from the upper end mof X-rya wavelengths to the highest energies possible. Details of the hardware and performance specifications of each of the instruments are discussed.

  10. Gamma-ray observations of Cygnus X-1

    NASA Astrophysics Data System (ADS)

    Bassani, L.; Di Cocco, G.; Stephen, J. B.; Dean, A. J.; Perotti, F.

    1989-08-01

    The results of gamma-ray observations of the Galactic black hole candidate Cygnus X-1 are presented. The recent HEAO 3 results reported by Ling et al. (1987) on this source are confirmed: (1) the detection in 1979 of a gamma-ray excess of comparable flux; and (2) a spectral variation above about 25 keV going from 1979 to 1980, which implies and anticorrelation between hard X-ray and gamma-ray luminosities with a pivot point in the 200-400 keV band. A comparison of all the data available at gamma-ray energies gives further support to the existence of this anticorrelation, although its statistical significance is low. The hard X-ray/gamma-ray 1979 spectrum, which is well fitted by a power law with photon index alpha = 1.7, can be interpreted as thermal Comptonization of soft photons or in terms of nonthermal models with copious photon-photon absorption.

  11. Evaluation of Potash Grade with Gamma-ray Logs

    USGS Publications Warehouse

    Nelson, Philip H.

    2007-01-01

    Potassium is an emitter of gamma-ray radiation, consequently deposits of potash can be detected and evaluated using gamma-ray logs. A method originally designed to evaluate uranium deposits in boreholes can also be applied to potash deposits. The method equates the depth-integral of a gamma-ray log to the grade-thickness product of a potash-bearing bed or series of beds. The average grade of a bed is then determined by dividing by the overall bed thickness, which can also be obtained from the gamma-ray log. The method was tested using gamma-ray logs and potash assays from boreholes near Carlsbad, New Mexico.

  12. Gamma ray and microwave emission from 1991 June events

    NASA Technical Reports Server (NTRS)

    Enome, Shinzo; Nakajima, Hiroshi; Hudson, Hugh S.; Schwartz, Richard

    1992-01-01

    The Sun showed unprecedented microwave activities in Jun. 1991, which produced four major and numerous weaker bursts and gamma ray emission measured by the Gamma Ray Observatory. The 4 Jun. 1991 event shows a sharp maximum around 03:41 UT and weak emission a few minutes before the maximum in the gamma ray record of the Burst and Transient Source Experiment (BATSE), with a preliminary estimated energy of 5 MeV. Although the 80-GHz and possible 35-GHz records show more prominent emission in the pre-maximum stage. This strongly suggests the first observational evidence for gamma ray and mm-wave emission from relativistic electrons. Comparisons of the other three major events on 6 Jun. at 01:00 UT, 9 Jun. at 01:34 UT, and 11 Jun. at 01:51 UT between gamma ray and microwave emission are also in progress.

  13. Gamma ray irradiation for sludge solubilization and biological nitrogen removal

    NASA Astrophysics Data System (ADS)

    Kim, Tak-Hyun; Lee, Myunjoo; Park, Chulhwan

    2011-12-01

    This study was conducted to investigate the effects of gamma ray irradiation on the solubilization of waste sewage sludge. The recovery of an organic carbon source from sewage sludge by gamma ray irradiation was also studied. The gamma ray irradiation showed effective sludge solubilization efficiencies. Both soluble chemical oxygen demand (SCOD) and biochemical oxygen demand (BOD 5) increased by gamma ray irradiation. The feasibility of the solubilized sludge carbon source for a biological nitrogen removal was also investigated. A modified continuous bioreactor (MLE process) for a denitrification was operated for 20 days by using synthetic wastewater. It can be concluded that the gamma ray irradiation was useful for the solubilization of sludge and the recovery of carbon source from the waste sewage sludge for biological nitrogen removal.

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

    PubMed

    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. PMID:23630379

  15. The theoretical. gamma. -ray spectrum of quasars. [3C 273

    SciTech Connect

    Dixson, M.E. )

    1991-04-05

    Preliminary results of calculations concerning the theoretical {gamma}-ray spectrum of quasi-stellar objects is presented. The calculated spectra extend (in {gamma}-ray energy) from approximately 0.1 to 1000 MeV. Numerous {gamma}-ray producing mechanisms are presently included to contribute to the total output. These include the decay of neutral pions, electron and positron bremsstrahlung, positron annihilation and {gamma}-ray line emission from eight different elements. Although very preliminary, the resulting model spectrum seems able to account for the observed spectrum. It is also found that the contribution to the total {gamma}-ray spectrum by positron annihilation is significant. The source of emission is considered to be a region of trapped relativistic protons surrounding the central engine of the QSO.

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

    SciTech Connect

    Fan, Yi-Zhong; Piran, Tsvi

    2011-11-29

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

  17. The Agile Gamma-Ray Mission and Gamma-Ray Burst Studies

    NASA Astrophysics Data System (ADS)

    Longo, Francesco; Tavani, Marco; Argan, Andrea; Caraveo, Patrizia; Chen, Andrew; Fiorini, Mauro; Giuliani, Andrea; Mereghetti, Sandro; Perotti, Francesco; Vercellone, Stefano; Barbiellini, Guido; Fedel, Giulio; Pontoni, Cristian; Prest, Michela; Vallazza, Erik; Costa, Enrico; Feroci, Marco; Lapshov, Igor; Rapisarda, Massimo; Rubini, Alda; Soffitta, Paolo; Cocco, Veronica; Morselli, Aldo; Picozza, Piergiorgio; Pittori, Carlotta; Auricchio, Natalia; Di Cocco, Guido; Galli, Marcello; Labanti, Claudio; Morelli, Ennio; Rossi, Elio; Trifoglio, Massimo; Lipari, Paolo; Zanello, Dino

    2002-12-01

    The AGILE satellite (the first of ASI Small Scientific Missions) is planned to be operational in 2003 and will be the only space mission entirely dedicated to gamma-ray astrophysics in the energy range 30 MeV - 50 GeV. AGILE is based on innovative solid state detector technology and will have two imaging detectors: a Silicon tracker (30 MeV-50 GeV), and a coded mask system with Si detectors (Super-AGILE, 10-40 keV). In addition, a CsI Mini-Calorimeter will be able to detect gamma-rays in the range 250 keV - 200 MeV. The instrument large field of view (~1/4 of the whole sky), excellent spatial resolution (a few arcminutes for Super-AGILE, 10-20 arcminutes for the Si-tracker), and unprecedented timing resolution and short deadtimes (~5-100 microseconds) improving EGRET capabilities by three orders of magnitude make of AGILE an ideal instrument to detect gamma-ray bursts

  18. Transient Gamma-Ray Spectrometer Observation of the Bright Gamma-Ray Burst GRB 950822

    NASA Astrophysics Data System (ADS)

    Seifert, H.; Teegarden, B. J.; Cline, T. L.; Gehrels, N.; Zand, J. J. M. in't.; Palmer, D. M.; Ramaty, R.; Hurley, K.; Madden, N. W.; Pehl, R.

    1997-12-01

    The Transient Gamma-Ray Spectrometer (TGRS) on the Wind satellite is designed to perform spectroscopy of bright gamma-ray bursts in the ~20-8000 keV energy range, having a resolution 5-30 times better than that of earlier generation detectors. GRB 950822 was the brightest burst observed by TGRS in its first year of operation, with a peak flux (1024 ms) of ~78.3 photons cm-2 s-1 and a fluence (50-300 keV) of ~1.4 10-4 ergs cm-2 therefore, the GRB data in this paper represent the first high-resolution spectroscopy ever performed on a burst of this brightness. The continuum spectrum of GRB 950822 has the classical gamma-ray burst shape and exhibits typical evolution from hard to soft over the course of the burst. We found no evidence of line features or any other spectral fine structure with significance greater than 3.5 ? in our data.

  19. WIDE RADIO BEAMS FROM {gamma}-RAY PULSARS

    SciTech Connect

    Ravi, V.; Manchester, R. N.; Hobbs, G.

    2010-06-10

    We investigate the radio and {gamma}-ray beaming properties of normal and millisecond pulsars (MSPs) by selecting two samples from the known populations. The first, Sample G, contains pulsars which are detectable in blind searches of {gamma}-ray data from the Fermi Large Area Telescope. The second, Sample R, contains pulsars detectable in blind radio searches which have spin-down luminosities E>10{sup 34} erg s{sup -1}. We analyze the fraction of the {gamma}-ray-selected Sample G which have detectable radio pulses and the fraction of the radio-selected Sample R which have detectable {gamma}-ray pulses. Twenty of our 35 Sample G pulsars have already observed radio pulses. This rules out low-altitude polar-cap beaming models if, as is currently believed, {gamma}-ray beams are generated in the outer magnetosphere and are very wide. We further find that, for the highest-E pulsars, the radio and {gamma}-ray beams have comparable beaming factors, i.e., the beams cover similar regions of the sky as the star rotates. For lower-E {gamma}-ray emitting pulsars, the radio beams have about half of the {gamma}-ray sky coverage. These results suggest that, for high-E young and MSPs, the radio emission originates in wide beams from regions high in the pulsar magnetosphere, probably close to the null-charge surface and to the {gamma}-ray emitting regions. Furthermore, it suggests that for these high-E pulsars, as in the {gamma}-ray case, features in the radio profile represent caustics in the emission beam pattern.

  20. Analysis of Data from the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Kniffen, Donald A.; Elliott, William W.

    1999-01-01

    The final report consists of summaries of work proposed, work accomplished, papers and presentations published and continuing work regarding the cooperative agreement. The work under the agreement is based on high energy gamma ray source data analysis collected from the Energetic Gamma-Ray Experiment Telescope (EGRET).

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

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

    SciTech Connect

    Oliveira, F. G.; Rueda, Jorge A.; Ruffini, R. E-mail: jorge.rueda@icra.it

    2014-06-01

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

  3. Characteristics of the Telescope for High Energy Gamma-ray Astronomy Selected for Definition Studies on the Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    The high energy gamma-ray 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.

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

    NASA Technical Reports Server (NTRS)

    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.

  5. Time-resolved Neutron-gamma-ray Data Acquisition for in Situ Subsurface Planetary Geochemistry

    NASA Technical Reports Server (NTRS)

    Bodnarik, Julie G.; Burger, Dan Michael; Burger, A.; Evans, L. G.; Parsons, A. M.; Schweitzer, J. S.; Starr R. D.; Stassun, K. G.

    2013-01-01

    The current gamma-ray/neutron instrumentation development effort at NASA Goddard Space Flight Center aims to extend the use of active pulsed neutron interrogation techniques to probe the subsurface elemental composition of planetary bodies in situ. Previous NASA planetary science missions, that used neutron and/or gamma-ray spectroscopy instruments, have relied on neutrons produced from galactic cosmic rays. One of the distinguishing features of this effort is the inclusion of a high intensity 14.1 MeV pulsed neutron generator synchronized with a custom data acquisition system to time each event relative to the pulse. With usually only one opportunity to collect data, it is difficult to set a priori time-gating windows to obtain the best possible results. Acquiring time-tagged, event-by-event data from nuclear induced reactions provides raw data sets containing channel/energy, and event time for each gamma ray or neutron detected. The resulting data set can be plotted as a function of time or energy using optimized analysis windows after the data are acquired. Time windows can now be chosen to produce energy spectra that yield the most statistically significant and accurate elemental composition results that can be derived from the complete data set. The advantages of post-processing gamma-ray time-tagged event-by-event data in experimental tests using our prototype instrument will be demonstrated.

  6. Effect of fast neutron, gamma-ray and combined radiations on the thermal decomposition of ammonium perchlorate single crystals

    NASA Technical Reports Server (NTRS)

    Herley, P. J.; Wang, C. S.; Varsi, G.; Levy, P. W.

    1974-01-01

    The thermal decomposition kinetics have been determined for ammonium perchlorate crystals subjected to a fast neutron irradiation or to a fast neutron irradiation followed by a gamma-ray irradiation. Qualitatively, the radiation induced changes are similar to those obtained in this and in previous studies, with samples exposed only to gamma rays. The induction period is shortened and the rate constants, obtained from an Avrami-Erofeyev kinetic analysis, are modified. The acceleratory period constant increases and the decay period constant decreases. When compared on an equal deposited energy basis, the fast neutron induced changes are appreciably larger than the gamma-ray induced changes. Some, or all, of the fast neutron induced effects might be attributable to the introduction of localized regions of concentrated radiation damage ('spikes') by lattice atom recoils which become thermal decomposition sites when the crystals are heated.

  7. Gamma-ray astronomy: From Fermi up to the HAWC high-energy {gamma}-ray observatory in Sierra Negra

    SciTech Connect

    Carraminana, Alberto; Collaboration: HAWC Collaboration

    2013-06-12

    Gamma-rays represent the most energetic electromagnetic window for the study of the Universe. They are studied both from space at MeV and GeV energies, with instruments like the Fermi{gamma}-ray Space Telescope, and at TeV energies with ground based instruments profiting of particle cascades in the atmosphere and of the Cerenkov radiation of charged particles in the air or in water. The Milagro gamma-ray observatory represented the first instrument to successfully implement the water Cerenkov technique for {gamma}-ray astronomy, opening the ground for the more sensitive HAWC {gamma}-ray observatory, currently under development in the Sierra Negra site and already providing early science results.

  8. Energy- and time-resolved detection of prompt gamma-rays for proton range verification

    NASA Astrophysics Data System (ADS)

    Verburg, Joost M.; Riley, Kent; Bortfeld, Thomas; Seco, Joao

    2013-10-01

    In this work, we present experimental results of a novel prompt gamma-ray detector for proton beam range verification. The detection system features an actively shielded cerium-doped lanthanum(III) bromide scintillator, coupled to a digital data acquisition system. The acquisition was synchronized to the cyclotron radio frequency to separate the prompt gamma-ray signals from the later-arriving neutron-induced background. We designed the detector to provide a high energy resolution and an effective reduction of background events, enabling discrete proton-induced prompt gamma lines to be resolved. Measuring discrete prompt gamma lines has several benefits for range verification. As the discrete energies correspond to specific nuclear transitions, the magnitudes of the different gamma lines have unique correlations with the proton energy and can be directly related to nuclear reaction cross sections. The quantification of discrete gamma lines also enables elemental analysis of tissue in the beam path, providing a better prediction of prompt gamma-ray yields. We present the results of experiments in which a water phantom was irradiated with proton pencil-beams in a clinical proton therapy gantry. A slit collimator was used to collimate the prompt gamma-rays, and measurements were performed at 27 positions along the path of proton beams with ranges of 9, 16 and 23 g?cm-2 in water. The magnitudes of discrete gamma lines at 4.44, 5.2 and 6.13 MeV were quantified. The prompt gamma lines were found to be clearly resolved in dimensions of energy and time, and had a reproducible correlation with the proton depth-dose curve. We conclude that the measurement of discrete prompt gamma-rays for in vivo range verification of clinical proton beams is feasible, and plan to further study methods and detector designs for clinical use.

  9. Energy- and time-resolved detection of prompt gamma-rays for proton range verification.

    PubMed

    Verburg, Joost M; Riley, Kent; Bortfeld, Thomas; Seco, Joao

    2013-10-21

    In this work, we present experimental results of a novel prompt gamma-ray detector for proton beam range verification. The detection system features an actively shielded cerium-doped lanthanum(III) bromide scintillator, coupled to a digital data acquisition system. The acquisition was synchronized to the cyclotron radio frequency to separate the prompt gamma-ray signals from the later-arriving neutron-induced background. We designed the detector to provide a high energy resolution and an effective reduction of background events, enabling discrete proton-induced prompt gamma lines to be resolved. Measuring discrete prompt gamma lines has several benefits for range verification. As the discrete energies correspond to specific nuclear transitions, the magnitudes of the different gamma lines have unique correlations with the proton energy and can be directly related to nuclear reaction cross sections. The quantification of discrete gamma lines also enables elemental analysis of tissue in the beam path, providing a better prediction of prompt gamma-ray yields. We present the results of experiments in which a water phantom was irradiated with proton pencil-beams in a clinical proton therapy gantry. A slit collimator was used to collimate the prompt gamma-rays, and measurements were performed at 27 positions along the path of proton beams with ranges of 9, 16 and 23 g cm(-2) in water. The magnitudes of discrete gamma lines at 4.44, 5.2 and 6.13 MeV were quantified. The prompt gamma lines were found to be clearly resolved in dimensions of energy and time, and had a reproducible correlation with the proton depth-dose curve. We conclude that the measurement of discrete prompt gamma-rays for in vivo range verification of clinical proton beams is feasible, and plan to further study methods and detector designs for clinical use. PMID:24077338

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

    SciTech Connect

    Nakar, Ehud; Sari, Re'em

    2012-03-10

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

  11. On a Novel Distance Indicator for Gamma-Ray Bursts Associated with Supernovae

    NASA Astrophysics Data System (ADS)

    Pisani, G. B.; Izzo, L.; Ruffini, R.; Bianco, C. L.; Muccino, M.; Penacchioni, A. V.; Rueda, J. A.; Wang, Y.

    2015-01-01

    In recent years it was proposed that the temporal coincidence of some gamma-ray bursts (GRBs) and a type Ib/c supernovae (SNe) can be explained by the concept of induced gravitational collapse (IGC) of a neutron star (NS) to a black hole (BH) induced by accretion of matter ejected by the SN Ib/c. More recently, this concept has been extended, including a precise description of the progenitor system of such GRB-SN systems...

  12. ICF gamma-ray reaction history diagnostics

    NASA Astrophysics Data System (ADS)

    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 expected burn widths of 10-20 ps associated with ignition. Multiple channels at each phase will allow for increased redundancy, reliability, accuracy and flexibility. In addition, inherent energy thresholding capability combined with this multiplicity will allow exploration of interesting gamma-ray physics well beyond the ignition campaign.

  13. Gamma-Ray Bursts 2012 Conference

    NASA Astrophysics Data System (ADS)

    It is a pleasure to announce the next combined Fermi/Swift GRB conference covering recent advances in all aspects of gamma-ray burst observations and theory. This conference will be held in Munich, Germany, on 7-11 May 2012, and follows similar previous combined Fermi/Swift meetings in Huntsville (Oct. 2008) and Annapolis (Nov. 2010). Gamma-ray bursts are the most energetic explosions in the Universe and are thought to be the birth signatures of black holes. This is an exciting time in the GRB field as various missions provide a wealth of new data on this still puzzling phenomenon. The Fermi misson provides unprecedented spectral coverage over 7 decades in energy, and among others discovered new spectral components which challenge our standard picture of the prompt emission. The Swift mission continuous to swiftly monitor and locate GRBs in multiple wavebands, providing the basis for all ground-based follow-up observations towards redshift measurements and afterglow and host property investigations. AGILE, INTEGRAL, Suzaku and Konus continue to provide crucial information on GRB properties, and the MAXI mission provides an all sky X-ray monitoring of transients. There is also growing capability for follow-up observations by ground-based telescopes at basically all wavelengths. Besides the classical optical/infrared/radio observations, searches are underway for TeV emission, neutrinos and gravitational waves. Moreover, new experiments are expected to have returned first data, among others POGO on the prompt polarization properties, UFFO on very early optical emission, or ALMA on sub-millimeter properties. And last but not least, the unexpected is bringing us child-like astonishments at least once per year with a "GRB-trigger" which turns out to be not related to GRBs. Complementing all these new observational results, a huge theoretical effort is underway to understand the GRB phenomenon and keep up with the constant new puzzles coming from the data. This conference will bring together astrophysicists, neutrino physicists and gravitational wave scientists to discuss the latest data and theories, to build synergistic collaborations between the fields and across wavelengths, and beyond better understanding the GRB phenomenon to develop GRBs as a powerful probe of a variety of fundamental questions in present-day research.

  14. Dawn's Gamma Ray and Neutron Detector

    NASA Astrophysics Data System (ADS)

    Prettyman, Thomas H.; Feldman, William C.; McSween, Harry Y.; Dingler, Robert D.; Enemark, Donald C.; Patrick, Douglas E.; Storms, Steven A.; Hendricks, John S.; Morgenthaler, Jeffery P.; Pitman, Karly M.; Reedy, Robert C.

    2011-12-01

    The NASA Dawn Mission will determine the surface composition of 4 Vesta and 1 Ceres, providing constraints on their formation and thermal evolution. The payload includes a Gamma Ray and Neutron Detector (GRaND), which will map the surface elemental composition at regional spatial scales. Target elements include the constituents of silicate and oxide minerals, ices, and the products of volcanic exhalation and aqueous alteration. At Vesta, GRaND will map the mixing ratio of end-members of the howardite, diogenite, and eucrite (HED) meteorites, determine relative proportions of plagioclase and mafic minerals, and search for compositions not well sampled by the meteorite collection. The large south polar impact basin may provide an opportunity to determine the composition of Vesta’s mantle and lower crust. At Ceres, GRaND will provide chemical information needed to test different models of Ceres’ origin and thermal and aqueous evolution. GRaND is also sensitive to hydrogen layering and can determine the equivalent H2O/OH content of near-surface hydrous minerals as well as the depth and water abundance of an ice table, which may provide information about the state of water in the interior of Ceres. Here, we document the design and performance of GRaND with sufficient detail to interpret flight data archived in the Planetary Data System, including two new sensor designs: an array of CdZnTe semiconductors for gamma ray spectroscopy, and a loaded-plastic phosphor sandwich for neutron spectroscopy. An overview of operations and a description of data acquired from launch up to Vesta approach is provided, including annealing of the CdZnTe sensors to remove radiation damage accrued during cruise. The instrument is calibrated using data acquired on the ground and in flight during a close flyby of Mars. Results of Mars flyby show that GRaND has ample sensitivity to meet science objectives at Vesta and Ceres. Strategies for data analysis are described and prospective results for Vesta are presented for different operational scenarios and compositional models.

  15. X-ray and gamma ray astronomy detectors

    NASA Technical Reports Server (NTRS)

    Decher, Rudolf; Ramsey, Brian D.; Austin, Robert

    1994-01-01

    X-ray and gamma ray astronomy was made possible by the advent of space flight. Discovery and early observations of celestial x-rays and gamma rays, dating back almost 40 years, were first done with high altitude rockets, followed by Earth-orbiting satellites> once it became possible to carry detectors above the Earth's atmosphere, a new view of the universe in the high-energy part of the electromagnetic spectrum evolved. Many of the detector concepts used for x-ray and gamma ray astronomy were derived from radiation measuring instruments used in atomic physics, nuclear physics, and other fields. However, these instruments, when used in x-ray and gamma ray astronomy, have to meet unique and demanding requirements related to their operation in space and the need to detect and measure extremely weak radiation fluxes from celestial x-ray and gamma ray sources. Their design for x-ray and gamma ray astronomy has, therefore, become a rather specialized and rapidly advancing field in which improved sensitivity, higher energy and spatial resolution, wider spectral coverage, and enhanced imaging capabilities are all sought. This text is intended as an introduction to x-ray and gamma ray astronomy instruments. It provides an overview of detector design and technology and is aimed at scientists, engineers, and technical personnel and managers associated with this field. The discussion is limited to basic principles and design concepts and provides examples of applications in past, present, and future space flight missions.

  16. GLAST and Ground-Based Gamma-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    McEnery, Julie

    2008-01-01

    The launch of the Gamma-ray Large Area Space Telescope together with the advent of a new generation of ground-based gamma-ray detectors such as VERITAS, HESS, MAGIC and CANGAROO, will usher in a new era of high-energy gamma-ray astrophysics. GLAST and the ground based gamma-ray observatories will provide highly complementary capabilities for spectral, temporal and spatial studies of high energy gamma-ray sources. Joint observations will cover a huge energy range, from 20 MeV to over 20 TeV. The LAT will survey the entire sky every three hours, allowing it both to perform uniform, long-term monitoring of variable sources and to detect flaring sources promptly. Both functions complement the high-sensitivity pointed observations provided by ground-based detectors. Finally, the large field of view of GLAST will allow a study of gamma-ray emission on large angular scales and identify interesting regions of the sky for deeper studies at higher energies. In this poster, we will discuss the science returns that might result from joint GLAST/ground-based gamma-ray observations and illustrate them with detailed source simulations.

  17. The Gamma-ray Albedo of the Moon

    SciTech Connect

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

    2007-09-28

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

  18. The Gamma-Ray Albedo of the Moon

    SciTech Connect

    Moskalenko, I.V.; Porter, T.A.; /UC, Santa Cruz

    2008-03-25

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

  19. Calculation of the decision thresholds in gamma-ray spectrometry.

    PubMed

    Korun, M; Vodenik, B; Zorko, B

    2014-12-01

    A method was developed for calculating the decision thresholds for gamma-ray spectrometric measurements. At the energies where gamma-ray emitters that are present in the nuclide library, but were not identified in the spectrum, radiate, peaks are supposed to appear. The peak areas are calculated by fitting, using the method of least squares, the spectral region of the supposed peaks with a continuous background and the spectrometer response function at the gamma-ray energies where the supposed peaks are positioned. The null measurement uncertainty of a gamma-ray emitter is obtained as the uncertainty of the weighted average of the activities calculated from the areas of the supposed peaks in a spectrum where the specified activity of the gamma-ray emitter is zero. For the calculation of the decision threshold the null measurement uncertainty is used. These decision thresholds overestimate the critical limits calculated with the Currie formula by about 10% in the case of single gamma-ray emitters. For multi-gamma-ray emitters the decision thresholds yield smaller values than the Currie formula. The presence of a peaked background or peaks that are near the supposed peaks increases the decision threshold considerably. PMID:25233528

  20. Gamma-ray transfer and energy deposition in supernovae

    NASA Technical Reports Server (NTRS)

    Swartz, Douglas A.; Sutherland, Peter G.; Harkness, Robert P.

    1995-01-01

    Solutions to the energy-independent (gray) radiative transfer equations are compared to results of Monte Carlo simulations of the Ni-56 and Co-56 decay gamma-ray energy deposition in supernovae. The comparison shows that an effective, purely absorptive, gray opacity, kappa(sub gamma) approximately (0. 06 +/- 0.01)Y(sub e) sq cm/g, where Y is the total number of electrons per baryon, accurately describes the interaction of gamma-rays with the cool supernova gas and the local gamma-ray energy deposition within the gas. The nature of the gamma-ray interaction process (dominated by Compton scattering in the relativistic regime) creates a weak dependence of kappa(sub gamma) on the optical thickness of the (spherically symmetric) supernova atmosphere: The maximum value of kappa(sub gamma) applies during optically thick conditions when individual gamma-rays undergo multiple scattering encounters and the lower bound is reached at the phase characterized by a total Thomson optical depth to the center of the atmosphere tau(sub e) approximately less than 1. Gamma-ray deposition for Type Ia supernova models to within 10% for the epoch from maximum light to t = 1200 days. Our results quantitatively confirm that the quick and efficient solution to the gray transfer problem provides an accurate representation of gamma-ray energy deposition for a broad range of supernova conditions.