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Sample records for 60co gamma rays

  1. Sensitivity to. gamma. rays of avian sarcoma and murine leukemia viruses. [/sup 60/Co, uv

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    Toyoshima, K. (Osaka Univ., Japan); Niwa, O.; Yutsudo, M.; Sugiyama, H.; Tahara, S.; Sugahara, T.

    1980-09-01

    The direct inactivation of avian and murine oncoviruses by ..gamma.. rays was examined using /sup 60/Co as a ..gamma..-ray source. The inactivation of murine leukemia virus (M-MuLV) followed single-hit kinetics while the subgroup D Schmidt-Ruppin strain of avian sarcoma virus (SR-RSV D) showed multihit inactivation kinetics with an extrapolation number of 5. The two viruses showed similar uv-inactivation kinetics. The genomic RNA of the SR-RSV D strain was degraded by ..gamma.. irradiation faster than its infectivity, but viral clones isolated from the foci formed after ..gamma.. irradiation had a complete genome. These results suggest that SR-RSV D has a strong repair function, possibly connected with reverse transcriptase activity.

  2. A comparison of ionizing radiation damage in CMOS devices from 60Co gamma rays, electrons and protons

    Institute of Scientific and Technical Information of China (English)

    HE Sao-Ping; YAO Zhi-Bin; ZHANG Feng-Qi

    2009-01-01

    Radiation hardened CC4007RH and non-radiation hardened CC4011 devices were irradiated using 80Co gamma rays, 1 MeV electrons and 1--9 MeV protons to compare the ionizing radiation damage of the gamma rays with the charged particles. For all devices examined, with experimental uncertainty, the radiation induced threshold voltage shifts (△Vth) generated by 60Co gamma rays are equal to that of 1 MeV electron and 1-7 MeV proton radiation under 0 gate bias condition. Under 5 V gate bias condition, the distinction of threshold voltage shifts (△Vth) generated by 60Co gamma rays and 1 MeV electrons irradiation are not large, and the radiation damage for protons below 9 MeV is always less than that of 60Co gamma rays. The lower energy the proton has, the less serious the radiation damage becomes.

  3. Radiation quality of tritium: a comparison with 60Co gamma rays.

    Science.gov (United States)

    Chen, Jing

    2013-09-01

    In a previous study, microdosimetric simulations were performed for tritium uniformly distributed in a medium, and for tritium bound to biologically critical sites of dimensions from 10 nm to 2 µm. Results of local energy density, i.e. energy deposition in microscopic regions, are different for these two cases. Based on the spatial distribution of energy deposition, dose mean lineal energies are calculated for tritium in the forms of tritiated water (HTO) and organically bound tritium (OBT). The dose mean lineal energies of OBT are about a factor of 1.7 higher than those of HTO in a wide range of target dimensions of biological interest. The results are consistent with radiobiological findings that OBT is about twice as effective as HTO. In this study, the same calculations were performed for (60)Co gamma rays in a wide range of target dimensions of biological interest (10 nm to 2 µm). Compared with (60)Co gamma rays, the estimated relative biological effectiveness could vary from 1.3 to 3.5 for HTO, and 2.3 to 5.6 for OBT. The results are consistent with radiobiological findings for various biological endpoints in different biological systems that OBT is about twice as effective as HTO.

  4. Study on shelf life extension of papayas irradiated by /sup 60/Co gamma-rays

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    Chang, M.S.; Chen, M.D.; Lin, C.T.; Fu, Y.K.

    1984-11-01

    Papayas are one of the main fresh fruits in Taiwan area. Papaya fruits were treated with hot water to pasteurize peels followed by /sup 60/Co gamma-ray irradiation to extend the ripening time. The purpose of synergetic methods is to extend the shelf life of papaya fruits. This experiment was carried out by seven treatments, which were: (1) control group, (2) hot water treatment only, (3) hot water treatment with a 25 krad ..gamma..-irradiation, (4) hot water treatment with a 50 krad ..gamma..-irradiation, (5) hot water treatment with a 75 krad ..gamma..-irradiation, (6) 75 krad ..gamma..-irradiation only, and (7) hot water treatment with a 100 krad ..gamma..-irradiation. The items of observation were: surface yellowing, surface decaying, quality of texture, and length of period lasted after irradiation for 50% marketable papayas. The results of this study showed that a shelf-life extension of six days could be obtained for papayas subjected to hot water (50 to 55/sup 0/C) treatment and a 100 krad irradiation. 3 refs., 2 figs., 2 tabs.

  5. Perna perna (LINNAEUS, 1758) mussels irradiated by {sup 60}CO gamma rays cytotoxicity evaluation

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    Martini, Gisela A.; Pusceddu, Fabio H.; Rogero, Sizue O.; Rogero, Jose Roberto, E-mail: gisela.martini@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    The aim of the present work was the study of ionizing radiation effects on aquatic biota regarding the location of nuclear facilities nearby coastal areas assuming the risk of leaks and nuclear accidents. Bivalve mollusks have been widely used in the monitoring of aquatic environment studies mainly for their sessile habit and pollutants bioconcentration ability. So marine mussel Perna perna (Bivalvia: Mytilidae) was used as organism test in this study. The study of radioactive toxicity was performed by cytotoxicity test exposing the organisms to 11Gy gamma radiation dose. After radiation the neutral red retention assay evaluated the lysosomal membrane integrity in the mussel hemocytes. 50% lethal dose assay (LD50) of gamma radiation on Perna perna mussels was carried out by exposure the organisms to {sup 60}Co gamma rays at doses ranging from 0 to 3000 Gy. The result of gamma radiation LD50 for these mussels was 1068 Gy and the neutral red retention time of irradiated organisms was about 47% lower than the control, non irradiated organisms. With the obtained results is expected to contribute in the study to identify the range of ionizing radiation doses which can cause toxic effects in marine invertebrates. (author)

  6. Effects of 2. 0 Gy of /sup 60/Co gamma rays irradiation on rat embryos

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    Lee, Juing-Yi; Satow, Yukio

    1987-01-01

    Pregnant rats of Donryu strain were exposed to a whole-body /sup 60/Co ..gamma.. ray irradiation of a single dose of 2.0 Gy (Dose rate: 0.5 Gy/min) on day 7, 8, 9, 10 or 11 of gestation (sperm day = day 0). The rats were sacrificed on day 18 and the offspring were examined for external and visceral malformations. Malformed embryos occurred between days 7 and 11 with the highest incidence occurring on day 9. Dose with 2.0 Gy increased the rate of resorption or death (52.1 %), in the survivors, caused congenital malformation in a majority of embryos (86.5 %) on day 8 of gestation. There is an increase in malformation (93.3 %) and growth retardation, but no increase in mortality (42.9 %) on day 9 of gestation. Relatively few anomalies resulted from irradiation on day 7 of gestation. The peak day for cardiovascular anomalies occurred on day 9 (88.3 % of all survival embryos) with high levels also occurring on day 8 (86.5 %). Cardiovascular anomalies consisted of VSD, hypoplasia of the pulmonary trunk, coarctation of the aorta, double aortic arch, right aortic arch, riding aorta, complete transposition of the aorta, persistent atrioventricular canal, vascular ring, aberrant right subclavian artery and others. Similar anomalies, but at a lower incidence, were produced by /sup 60/Co ..gamma.. ray at dose levels of 2.0 Gy on day 10 or 11 of gestation. Cases of cleft lip and cleft palate or facial cleft were observed seventeen fetuses on day 9 of gestation (31 %). Exencephaly occurred in nine embryos treated on day 9 (16.1 %) and in one embryos treated on day 10. Tail defects appeared with treatment on day 9 with the latter predominating on day 11. The present study show that maximum resorption (52.1 %) was seen with treatment on day 8 whereas the highest rate of malformation (93.3 %) was observed with treatment on day 9. (J.P.N.).

  7. Evaluation of myotoxic activity of Bothropstoxin-1 irradiated with {sup 60}Co gamma rays

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    Mirco, Jessica; Baptista, Janaina A.; Caproni, Priscila; Yoshito, Daniele; Nascimento, Nanci do [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil)], e-mail: jessica.mirco@yahoo.com.br, e-mail: janabap@gmail.com, e-mail: pricaproni@hotmail.com, e-mail: daniyoshito@uol.com.br, e-mail: nnascime@ipen.br

    2009-07-01

    Ionizing radiation has been successfully employed to modify the immunological properties of biomolecules and has been proven to be a powerful tool to attenuate snake venoms toxicity without affecting their immunogenic properties. Snake venoms and their isolated toxins showed structural modifications after gamma radiation process, in aqueous solution, mainly by water radiolysis sub products. Free radical scavengers, such as NaNO{sub 3} and t-butanol, present selective effects on specific radical from water radiolysis. The NaNO{sub 3} has affinity by aqueous electron, while the t-butanol has affinity by hydroxyl radical. At the present work, we have investigated the myotoxic activity of Bothropstoxin-1 (BTHX-1), a K49 phospholipase, present in Bothrops jararacussu crude venom, before and after irradiation process, with or without scavenger substances presence. BTHX-1 was irradiated with 2 kGy of {sup 60}Co gamma rays, in aqueous solution and in the presence of oxygen. BALB/c mice were inoculated with either native or irradiated toxin, with or without scavenger substances. After 3 hours, blood samples were collected and the myotoxic activity was evaluated by LDH (lactate dehydrogenase) release. The muscular tissue damage was directly related to the LDH amounts released. Irradiated Bothropstoxin-1, with or without NaNO{sub 3} substance, caused less damage than their native counterpart. But irradiated toxin, in the presence of t-butanol, was so myotoxic as the native BTHX-1. These results indicate that irradiation of toxic proteins can promote significant modifications on their structures, but still retaining many of the original biological properties of their native counterparts. Additionally, some scavengers substances can change these gamma radiation effects. (author)

  8. Study of irradiated bothropstoxin-1 with {sup 60}Co gamma rays: immune system behavior

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    Caproni, P.; Baptista, J.A.; Almeida, T.L. de; Nascimento, N. [Nuclear and Energy Research Institute (IPEN/CNEN-SP), SP (Brazil). Biotechnology Center; Passos, L.A.C. [State University of Campinas (UNICAMP), SP (Brazil). Lab. of Genetics and Embryo Cryopreservation

    2009-07-01

    Ionizing radiation has been successfully employed to modify the immunological properties of biomolecules. Very promising results were obtained when crude animal venoms, as well as isolated toxins, were treated with 60Co gamma rays, yielding toxoids with good immunogenicity. The achievement of modified antigens with lower toxicity and preserved or improved immunogenicity can be very useful. Ionizing radiation has already been proven to be a powerful tool to attenuate snake venom toxicity without affecting, and even increasing, their immunogenic properties. However, little is known about the modifications that irradiated molecules undergo and even less about the immunological response that such antigens elicit. In the present work, we investigated the immunological behavior of bothropstoxin-1, a K49 phospholipase, before and after irradiation. Structural modifications of the toxin were analyzed by SDS-PAGE. Isogenic mice were immunized with either the native or the irradiated toxin. The circulating antibodies were isotyped and titrated by ELISA. According to our data, irradiation promoted structural modifications in the toxin characterized by higher molecular weight forms of proteins (aggregates and oligomers). The results also indicated that irradiated toxins were immunogenic and antibodies elicited by them were able to recognize the native toxin in ELISA. These findings suggest that irradiation of toxic proteins can promote significant modifications in their structures; however they still retain many of the original antigenic and immunological properties of native proteins. Also, our data indicate that irradiated proteins induce higher titers of IgG2a and IgG2b, suggesting that Th1 cells are predominantly involved in the immune response. (author)

  9. Study of irradiated toxins with {sup 60}Co gamma rays: immune system behavior

    Energy Technology Data Exchange (ETDEWEB)

    Caproni, Priscila; Baptista, Janaina A.; Almeida, Tiago Luiz de; Passos, Luiz A.C.; Nascimento, Nanci do [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mail: pricaproni@hotmail.com

    2007-07-01

    Ionizing radiation has been successfully employed to modify the immunological properties of biomolecules. Very promising results were obtained when crude animal venoms, as well as isolated toxins, were treated with {sup 60}Co gamma rays, yielding toxoids with good immunogenicity. The achievement of modified antigens with lower toxicity and preserved or improved immunogenicity can be useful. Ionizing radiation has been proven to be a powerful tool to attenuate snake venoms toxicity without affecting and even increasing their immunogenic properties. However, little is known about the modifications that irradiated molecules undergo and even less about the immunological response that such antigens elicit. In the present work, we have investigated the immunological behavior of bothropstoxin-I, a K49 phospholipase, before and after irradiation. Structural modifications of the toxin were investigated by SDS-PAGE. Isogenic mice were immunized with either the native or the irradiated toxin. The circulating antibodies were isotyped and titrated by ELISA. According to our data, irradiation promoted structural modifications in the toxin, characterized by higher molecular weight forms of the protein (aggregates and oligomers). Our data indicate that irradiated toxins were immunogenic and the antibodies elicited by them were able to recognize the native toxin in ELISA. These results indicate that irradiation of toxic proteins can promote significant modifications in their structures, but still retain many of the original antigenic and immunological properties of native proteins. Also, our data indicate that the irradiated protein induced higher titers of IgG2a and IgG2b, suggesting that Th1 cells were predominantly involved in the immune response. (author)

  10. Biochemical and pharmacological characterization of irradiated crotamine by gamma rays of {sup 60}Co; Caracterizacao bioquimica e farmacologica da crotamina irradiada por raios gama de {sup 60}Co

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    Oliveira, Karina Corleto

    2014-07-01

    The serum production in Brazil, the only effective treatment in cases of snakebites, uses horses that although large size, have reduced l lifespan compared with horses not immunized. Ionizing radiation has been shown as an excellent tool in reducing the toxicity of venoms and toxins isolated, and promote the achievement of better immunogens for serum production, and contributing to the welfare of serum-producing animals. It is known, however, that the effects of ionizing radiation on protein are characterized by various chemical modifications, such as fragmentation, cross-linking due to aggregation and oxidation products generated by water radiolysis. However, the action of gamma radiation on toxins is not yet fully understood structurally and pharmacologically, a fact that prevents the application of this methodology in the serum production process. So we proposed in this paper the characterization of crotamine, an important protein from the venom of Crotalus durissus terrificus species, irradiated with {sup 60}Co gamma rays. After isolating the toxin by chromatographic techniques and testing to prove the obtaining of pure crotamine, it was irradiated with gamma rays and subjected to structural analysis, Fluorescence and Circular Dichroism. Using high hydrostatic pressure tests were also conducted in order to verify that the conformational changes caused by radiation suffer modifications under high pressures. From the pharmacological point of view, muscle contraction tests were conducted with the objective of limiting the action of crotamine in smooth muscle as well as the change in the action of toxin caused structural changes to the front. Analysis of Circular Dichroism and Fluorescence showed changes in structural conformation of crotamine when subjected to gamma radiation and that such changes possibly occurring in the secondary and tertiary structure of the protein. The observed in pharmacological tests showed that the irradiated crotamine was less effective

  11. Effects of {sup 60}Co gamma-rays, ultraviolet light, and mitomycin C on halobacterium salinarium and thiobacillus intermedius

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    Shahmohammadi, H.R.; Asgarani, E.; Terato, Hiroaki; Ide, Hiroshi; Yamamoto, Osamu [Hiroshima Univ. (Japan)

    1997-03-01

    Lethal effects of {sup 60}Co {gamma}-rays, UV light, and mitomycin C on two kinds of bacteria, Halobacterium salinarium which grows in highly concentrated salt media and Thiobacillus intermedius which requires reduced sulfur compounds, were studied and compared with those on Escherichia coli B/r. D{sub 37} values for H. salinarium, T. intermedius and E. coli B/r were 393, 150, and 92 Gy, respectively, by exposure to {sup 60}Co {gamma}-rays. They were 212, 38, and 10 J/m{sup 2}, respectively, by exposure to UV light and 2.36, 0.25, and 0.53 {mu}g/ml/h, respectively, by exposure to mitomycin C. Against these agents, H salinarium was much more resistant than T. intermedius and E. coli B/r. (author)

  12. Effects of 60Co gamma-rays, ultraviolet light, and mitomycin C on Halobacterium salinarium and Thiobacillus intermedius.

    Science.gov (United States)

    Shahmohammadi, H R; Asgarani, E; Terato, H; Ide, H; Yamamoto, O

    1997-03-01

    Lethal effects of 60Co gamma-rays, UV light, and mitomycin C on two kinds of bacteria, Halobacterium salinarium which grows in highly concentrated salt media and Thiobacillus intermedius which requires reduced sulfur compounds, were studied and compared with those on Escherichia coli B/r. D37 values for H. salinarium, T. intermedius and E. coli B/r were 393, 150, and 92 Gy, respectively, by exposure to 60Co gamma-rays. They were 212, 38, and 10 J/m2, respectively, by exposure to UV light and 2.36, 0.25, and 0.53 microgram/ml/h, respectively, by exposure to mitomycin C. Against these agents, H. salinarium was much more resistant than T. intermedius and E. coli B/r.

  13. Irradiation effect on enzymatic activity of papain with {sup 60}Co-{gamma} rays

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    Furuta, Masakazu; Ohashi, Isao; Oka, Masahito; Hayashi, Toshio [Osaka Prefecture Univ., Sakai (Japan). Research Inst. for Advanced Science and Technology

    1998-12-31

    An investigation was made on the durability of enzyme activity against {sup 60}Co-{gamma} irradiation at a dose up to 55 kGy/h using dry powder and aqueous solution of papain preparations on the market. Hybrid materials including bioactive molecules combined with biocompatible synthetic polymers are expected to have biocompatible properties and also biomimetic functions as a component of artificial organs for human body. The activity of papain in an aqueous solution was rapidly decreased at the early stage of irradiation through oxidation of SH group at its active site with active oxygen produced by the irradiation and then, partially recovered since SH group was reproduced in an anoxic state after O{sub 2} consumption in the solution irradiated at a high dose. A usual radiation method for sterilization was found applicable to decontamination of dry and frozen preparations of papain. When suitable conditions for radiation were chosen and N{sub 2} gas was purged to suppress the formation of free radicals, it was possible to keep the enzyme activity at more than 50% of the initial activity after radiation at 30 kGy. (M.N.)

  14. Dose intercomparison studies for 60Co gamma-ray and electron beam irradiation in the year 2002

    Institute of Scientific and Technical Information of China (English)

    LIN Min; Takuji KOJIMA; Zofia PEIMEL-STUGLIK; CHEN Yun-Dong; CUI Ying; CHEN Ke-Sheng; LI Hua-Zhi; XIAO Zhen-Hong; Slawomir FABISIAK

    2004-01-01

    Dose inter-comparison studies for 60Co γ-ray and 10MeV electron beam irradiation were carried out from July to October in 2002. The purpose of the studies was to check the reliability of the alanine-PE film dosimeters made by CIAE, which will be used as transfer standard dosimetry system mainly for electron beam irradiation.The expanded uncertainty of CIAE alanine/EPR dosimetry system was 4.1% for doses not higher than 10 kGy and 5.4% for those above 10 kGy (k=2). CIAE alanine-PE film dosimeters were sent to JAERI, RISO (National Laboratory in Denmark) and INCT respectively, which were irradiated by 60Co gamma-rays or electron beams in each laboratory. The irradiated dosimeters were then sent back to CIAE for electron paramagnetic resonance (EPR) analysis.The agreements were obtained to be ±1.9% for gamma-ray dose measurement and ±4.3% for electron beam dose measurement, which were all within the combined uncertainty of the reference and CIAE alanine/EPR dosimetry system. Furthermore, the overall mean ratio was found to be 0.995 with 1.8% in the coefficient of variation (CV). The preliminary inter-comparison studies indicated that CIAE film alanine/EPR dosimetry system had the potential to be used as a transfer dosimetry system for high dose measurement.

  15. Comparison of base substitutions in response to nitrogen ion implantation and 60Co-gamma ray irradiation in Escherichia coli

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    Xie Chuan-Xiao

    2004-01-01

    Full Text Available To identify the specificity of base substitutions, a novel experimental system was established based on rifampicin-resistant (Rif r mutant screening and sequencing of the defined region of the rpoB gene in E. coli. We focused on comparing mutational spectra of base substitutions induced by either low energy nitrogen ion beam implantation or 60Co-gamma rays. The most significant difference in the frequency of specific kinds of mutations induced by low energy nitrogen ion beam was that CG ®TA transitions were significantly increased from 32 to 46, AT ®TA transversions were doubled from 7 to 15 in 50 mutants, respectively. The preferential base substitutions induced by nitrogen ion beam implantation were CG ®TA transitions, AT ®GC transitions, AT ®TA transversions, which account for 92.13% (82/89 of the total. The mutations induced by 60Co-gamma rays were preferentially GC ®AT and AT ®GC transitions, which totaled 84.31% (43/51.

  16. Determination of late-time Gamma-Ray (60Co) sensitivity of single diffusion Lot 2N2222A transistors.

    Energy Technology Data Exchange (ETDEWEB)

    DePriest, Kendall Russell; Kajder, Karen C.; Peters, Curtis D. (American Staff Augmentation Providers, LLC, Albuquerque, NM)

    2008-08-01

    Sandia National Laboratories (SNL) has embarked on a program to develop a methodology to use damage relations techniques (alternative experimental facilities, modeling, and simulation) to understand the time-dependent effects in transistors (and integrated circuits) caused by neutron irradiations in the Sandia Pulse Reactor-III (SPR-III) facility. The development of these damage equivalence techniques is necessary since SPR-III was shutdown in late 2006. As part of this effort, the late time {gamma}-ray sensitivity of a single diffusion lot of 2N2222A transistors has been characterized using one of the {sup 60}Co irradiation cells at the SNL Gamma Irradiation Facility (GIF). This report summarizes the results of the experiments performed at the GIF.

  17. Different gamma ray ({sup 60} Co) dose effects on Sorghum genotype germination; Efeito de diferentes doses de radiacao gama do {sup 60} Co sobre a germinacao de genotipos de sorgo (Sorghum bicolor)

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    Tabosa, Jose Nildo; Gomes, Roberto Vicente; Reis, Odemar Vicente dos [Empresa Pernambucana de Pesquisa Agropecuaria (IPA), Recife (Brazil)]. E-mail: tabosa@ipa.br; Colaco, Waldeciro [Universidade Federal de Pernambuco, Recife, PE (Brazil). Dept. de Energia Nuclear]. E-mail: wcolaco@ufpe.br

    2004-08-15

    In agriculture, applying irradiation is a very valuable way of obtaining vegetable products for human and animal consumption. Cobalt-60, one of the main sources of gamma-rays, is considered an important tool in plant breeding programs, which have the objective of promoting genetic variability of cultivars with resistance to adverse environments. In this research, the effects of different {sup 60}Co doses on germination vigor and seed germination velocity of forage sorghum genotypes were evaluated. The study was carried out at the IPA (Empresa Pernambucana de Pesquisa Agropecuaria) in Recife, Pernambuco, Brazil. The work was installed in germination boxes, following laboratory recommendations. Thus, a experiment involving three sorghum genotypes (IPA 467-4-2, IPA 02-03-01, and Sudan 4202), five {sup 60}Co doses (Zero, 150, 300, 350, and 400 Gy), was set up. The sees were irradiated before the beginning of the experiment being exposed to gamma rays from a {sup 60}Co-source (cobalt irradiator) at DEN (Nuclear Engineering Department) of the UFPE (Pernambuco Federal University), Brazil. The work also had the objective of evaluating the sorghum genotypes x {sup 60}Co dose interaction. The main results obtained showed that the sorghum genotype IPA 02-03-01 presented the greatest values of germination and vigor percentages, and seed germination velocity, when compared to the others evaluated, on 350 and 400 Gy of {sup 60}Co doses. (author)

  18. An investigation on the radiation sensitivity of DNA conformations to {sup 60}Co gamma rays by using Geant4 toolkit

    Energy Technology Data Exchange (ETDEWEB)

    Semsarha, F. [Institute of Biochemistry and Biophysics (IBB), University of Tehran, P.O. Box 13145-1384, Tehran (Iran, Islamic Republic of); Goliaei, B., E-mail: goliaei@ibb.ut.ac.ir [Institute of Biochemistry and Biophysics (IBB), University of Tehran, P.O. Box 13145-1384, Tehran (Iran, Islamic Republic of); Raisali, G.; Khalafi, H. [Radiation Applications Research School, Nuclear Science and Technology Research Institute, P.O. Box 11365-3486, Tehran (Iran, Islamic Republic of); Mirzakhanian, L. [Medical Physics Unit, McGill University, 1650 Cedar Avenue, Montreal, Quebec (Canada)

    2014-03-15

    To investigate the impact of conformational properties of genetic material of living cells on radiation-induced DNA damage, single strand breaks (SSB), double strand breaks (DSB) and some microdosimetric quantities of A, B and Z-DNA conformations caused by {sup 60}Co gamma rays, have been calculated. Based on a previous B-DNA geometrical model, models of A and Z forms have been developed. Simple 34 base pairs segments of each model repeated in high number and secondary electron spectrum of {sup 60}Co gamma rays have been simulated in a volume of a typical animal cell nucleus. All simulations in this study have been performed by using the Geant4 (GEometry ANd Tracking 4)-DNA extension of the Geant4 toolkit. The results showed that, B-DNA has the lowest yield of simple strand breaks with 2.23 × 10{sup −10} Gy{sup −1} Da{sup −1} and 1.0 × 10{sup −11} Gy{sup −1} Da{sup −1} for the SSB and DSB damage yield, respectively. The A-DNA has the highest SSB yield with 3.59 × 10{sup −10} Gy{sup −1} Da{sup −1} and the Z-DNA has the highest DSB yields with 1.8 × 10{sup −11} Gy{sup −1} Da{sup −1}. It has been concluded that there is a direct correlation between the hit probability, mean specific imparted energy and SSB yield in each model of DNA. Moreover, there is a direct correlation between the DSB yield and both the mean lineal energy and topological characteristics of each model.

  19. Immune response against bothropstoxin-I irradiated with {sup 60}Co gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Baptista, J.A.; Spencer, P.J.; Higa, O.Z.; Casare, M.S.; Campos, L.A.; Nascimento, N. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Lab. de Biologia Molecular]. E-mail: janabap@gmail.com; Andrade Junior, H.F de [Sao Paulo Univ., SP (Brazil). Inst. de Medicina Tropical de Sao Paulo. Lab. de Protozoologia]. E-mail: hfandrad@usp.br

    2005-07-01

    Ionizing radiation has been successfully employed to modify the immunological properties of biomolecules. Very promising results were obtained when crude animal venoms, as well as isolated toxins, were treated with gamma rays, yielding toxoids with good immunogenicity. Ionizing radiation has proven to be a powerful tool to attenuate snake venoms toxicity without affecting and even increasing their immunogenic properties. However, little is known about the modifications that irradiated molecules undergo and even less about the immunological response that such antigens elicit. In the present work, we investigated the immunological behavior of bothropstoxin-I, a K49 phospholipase, before and after irradiation. Structural modifications of the toxin were investigated by SDS-PAGE and mass spectrometry. Aiming to compare the toxicity between native and irradiated forms of the toxin, an in vitro cytotoxicity assay, using CHO cells, was performed. Isogenic mice were immunized with either the native or the irradiated toxin. The circulating antibodies were isotyped and titrated by ELISA. According to our data, irradiation promoted structural modifications in the toxin, characterized by higher molecular weight forms of the protein (aggregates and oligomers). When analyzed by mass spectrometry, the irradiated bothropstoxin appeared in several oxidized forms. The cytotoxicity assay showed that the modified toxin was 5 folds less toxic than its native counterpart. Irradiated toxins were immunogenic and the antibodies elicited by them were able to recognize the native toxin in ELISA. These results indicate that irradiation of toxic proteins can promote significant modifications in their structures, but still retain many of the original immunological properties. (author)

  20. Structure alteration and immunological properties of {sup 60}Co gamma rays irradiated bothropstoxin-I

    Energy Technology Data Exchange (ETDEWEB)

    Baptista, Janaina A.; Yonamine, Camila Myiagui; Caproni, Priscila; Casare, Murilo; Spencer, Patrick Jack; Nascimento, Nanci do [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mail: janabap@gmail.com; Andrade Junior, Heitor Franco de; Vieira, Daniel Perez; Galisteo Junior, Andres Jimenez [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Instituto de Medicina Tropical de Sao Paulo, SP (Brazil). Lab. de Protozoologia

    2007-07-01

    About 20000 ophidic accidents are registered every year in Brazil. Serum therapy with equine antisera is the only efficient treatment. The venoms employed for immunization are fairly toxic and some venoms present low immunogenicity. Thus, the obtention of modified antigens with lower toxicity and preserved or improved immunogenicity would be useful. These toxins, when submitted to gamma radiation, in aqueous solution, present structural modifications. This occurs due to reactions with the radiolysis products of water. Some scavenger substances, such as NaNO{sub 3} and t-butanol, remove selectively the water radiolysis products. Ionizing radiation has proven to be a powerful tool to attenuate snake venoms toxicity without affecting and even increasing their immunogenic properties. However, the immune mechanisms involved in recognition, processing and presentation of irradiated antigens are yet unclear. In the present work, we investigated the immunological behavior of bothropstoxin-I (Bthx-1), before and after irradiation, in the presence of selective scavengers. Isogenic mice were immunized with either the native or the irradiated toxin, either with or without scavengers. After three immunizations, serum samples were collected and the antibody titers and isotypes were determined by Enzyme Linked Immuno Sorbent Assay. The antigenic characterization of native and irradiated bothropstoxin-I was performed by Western blot. The detection of expression of murine cytokines (IFN-{gamma} and IL-10) was analyzed by RT-PCR (Reverse Transcriptase-Polymerase Chain Reaction). According to our data, irradiation process has promoted structural modifications in the toxin, characterized by higher molecular weight forms of the protein (aggregates and oligomers). Our data also indicate that irradiated toxins, alone or in the presence of NaNO{sub 3}, an aqueous electron scavenger, were immunogenic and the antibodies elicited by them were able to recognize the native toxin. On the other

  1. Numerical simulation of 60Co-gamma irradiation effects on electrical characteristics of n-type FZ silicon X-ray detectors

    Science.gov (United States)

    Vigneshwara Raja, P.; Rao, C. V. S.; Narasimha Murty, N. V. L.

    2016-07-01

    This paper describes the gamma irradiation effects on the electrical characteristics of n-type float zone (FZ) silicon detectors by incorporating a 4-level 60Co-gamma radiation damage model in the commercial device simulator for plasma X-ray tomography diagnostics. In the simulations, a segmented n-type silicon detector (i.e. p+-n-n+ structure) is considered with varying substrate resistivity (ρ = 5.4, 2.5, and 0.3 kΩ cm). The simulation results have been validated with the reported experimental measurements carried out on similar device structures. The 60Co-gamma irradiation induced changes in the electrical characteristics of the detectors are analyzed up to the dose of 3500 Mrad. The possible gamma induced degradation in the X-ray response of the detectors is investigated from the changes in the effective doping concentration and the leakage current of the detectors. The survival of the gamma irradiated detectors is predicted from the simulation studies. The comparison between the 60Co-gamma and 14.1 MeV neutron irradiation effects (typical fusion environments) on silicon detectors is attempted.

  2. (60)Co in cast steel matrix: A European interlaboratory comparison for the characterisation of new activity standards for calibration of gamma-ray spectrometers in metallurgy.

    Science.gov (United States)

    Tzika, Faidra; Burda, Oleksiy; Hult, Mikael; Arnold, Dirk; Marroyo, Belén Caro; Dryák, Pavel; Fazio, Aldo; Ferreux, Laurent; García-Toraño, Eduardo; Javornik, Andrej; Klemola, Seppo; Luca, Aurelian; Moser, Hannah; Nečemer, Marijan; Peyrés, Virginia; Reis, Mario; Silva, Lidia; Šolc, Jaroslav; Svec, Anton; Tyminski, Zbigniew; Vodenik, Branko; Wätjen, Uwe

    2016-08-01

    Two series of activity standards of (60)Co in cast steel matrix, developed for the calibration of gamma-ray spectrometry systems in the metallurgical sector, were characterised using a European interlaboratory comparison among twelve National Metrology Institutes and one international organisation. The first standard, consisting of 14 disc shaped samples, was cast from steel contaminated during production ("originally"), and the second, consisting of 15 similar discs, from artificially-contaminated ("spiked") steel. The reference activity concentrations of (60)Co in the cast steel standards were (1.077±0.019) Bqg(-1) on 1 January 2013 12h00 UT and (1.483±0.022) Bqg(-1) on 1 June 2013 12h00 UT, respectively.

  3. Calculation of direct effects of {sup 60}Co gamma rays on the different DNA structural levels: A simulation study using the Geant4-DNA toolkit

    Energy Technology Data Exchange (ETDEWEB)

    Tajik, Marjan; Rozatian, Amir S.H. [Department of Physics, University of Isfahan, Hezar Jarib Street, Isfahan 81746-73441 (Iran, Islamic Republic of); Semsarha, Farid, E-mail: Semsarha@ibb.ut.ac.ir [Institute of Biochemistry and Biophysics (IBB), University of Tehran, P.O. Box: 13145-1384, Tehran (Iran, Islamic Republic of)

    2015-03-01

    In this study, simple single strand breaks (SSB) and double strand breaks (DSB) due to direct effects of the secondary electron spectrum of {sup 60}Co gamma rays on different organizational levels of a volume model of the B-DNA conformation have been calculated using the Geant4-DNA toolkit. Result of this study for the direct DSB yield shows a good agreement with other theoretical and experimental results obtained by both photons and their secondary electrons; however, in the case of SSB a noticeable difference can be observed. Moreover, regarding the almost constant yields of the direct strand breaks in the different structural levels of the DNA, calculated in this work, and compared with some theoretical studies, it can be deduced that the direct strand breaks yields depend mainly on the primary double helix structure of the DNA and the higher-order structures cannot have a noticeable effect on the direct DNA damage inductions by {sup 60}Co gamma rays. In contrast, a direct dependency between the direct SSB and DSB yields and the volume of the DNA structure has been found. Also, a further study on the histone proteins showed that they can play an important role in the trapping of low energy electrons without any significant effect on the direct DNA strand breaks inductions, at least in the range of energies used in the current study.

  4. 白藜芦醇对60Coγ射线照射小鼠氧化损伤的防护%Radioprotective Effect of Resveratrol on Oxidative Damage in 60Co Gamma Ray Irradiated Mice

    Institute of Scientific and Technical Information of China (English)

    徐冰心; 李成林; 史煜华; 谢京波; 陈阿鑫; 高娇; 任晔; 李建忠; 刘志国

    2012-01-01

    Objective To investigate the radioprotective effect of resveratrol( RES) on gamma-irradiation-induced serum and liver oxidative damage in mice. Methods Thirty male ICR mice were randomized into 5 groups; normal control group, irradiated control group, RES 50,100 and 200 mg·kg-1 irradiated groups. RES was administered respectively to three dosage groups by gavage on 3rd day before irradiation and 7th day after irradiation. Except for normal control, all the mice were whole-body irradiated by 60Co gamma ray(a single dose of 6.0 Gy). The mice were killed on 7th day. The activities of superoxide dismutase (SOD) ,glutathione peroxidase (GSh-Px) and the amount of malondialdehyde( MDA) of the serum and liver were measured. Results Compared with normal control group,the activities of SOD and GSH-Px were significantly decreased while the amount of MDA was significantly increased in irradiated control group mice. Compared with irradiated control, the activities of SOD and GSH-Px tended to increase while the amount of MDA tended to decrease in RES 50 mg ·kg-1' irradiated group mice. The activities of SOD and GSh-Px and the amount of MDA increased with the RES dosage. Conclusion RES has radioprotective effect against oxidative damage to the serum and liver in 60Co rays irradiated mice. This effect of RES depends on the dosage.%目的 研究白藜芦醇对60Coγ射线照射小鼠氧化损伤的防护作用.方法 30只♂ ICR小鼠随机分成5组,正常对照组、照射对照组以及白藜芦醇低、中、高剂量( 50、100、200 mg·kg-1)照射组,照射前3d至照后第7天灌服给药,每天1次,共10次.除正常对照组外,所有小鼠60Coγ射线全身6 Gy辐照1次,照射后第7天小鼠取外周血和肝组织标本,测定血清和肝组织匀浆中超氧化物歧化酶(SOD)、谷胱苷肽过氧化物酶(GSH-Px)活性及丙二醛(MDA)含量.结果与正常对照组比较,照射对照组小鼠血清和肝组织匀浆中SOD和GSH-Px活性显著下降,MDA含量显

  5. The depth-dependence of the biological effectiveness of 60Co gamma rays in a large absorber determined by dicentric chromosomes in human lymphocytes.

    Science.gov (United States)

    Schmid, Ernst; Roos, Hartmut; Kramer, Hans-Michael

    2008-01-01

    Radiobiological evidence is shown concerning a significant depth-dependence of the maximum relative biological effectiveness at limiting low doses (RBE(M)) of (60)Co gamma rays in a cubic polymethylmethacrylate (PMMA) phantom of 30 cm edge length. Using the dose-response curve for the dicentric data in human lymphocytes obtained in the present experiment at a depth of 20 cm, together with the comprehensive and consistent data set determined earlier at smaller depths of the PMMA phantom, there is an increase in the RBE(M) value by a factor of 2.18 +/- 1.25 at a depth of 20 cm relative to 1 cm in the phantom. All the dicentric data are based on identical exposure durations and irradiation temperatures as well as identical culture and evaluation conditions, with blood from the same donor.

  6. The RBE of 3.4 MeV alpha-particles and 0.565 MeV neutrons relative to 60Co gamma-rays for neoplastic transformation of human hybrid cells and the impact of culture conditions.

    Science.gov (United States)

    Frankenberg-Schwager, M; Spieren, S; Pralle, E; Giesen, U; Brede, H J; Thiemig, M; Frankenberg, D

    2010-01-01

    The neoplastic transformation of human hybrid CGL1 cells is affected by perturbations from external influences such as serum batch and concentration, the number of medium changes during the 21-day expression period and cell seeding density. Nevertheless, for doses up to 1.5 Gy, published transformation frequencies for low linear energy transfer (LET) radiations (gamma-rays, MeV electrons or photons) are in good agreement, whereas for higher doses larger variations are reported. The (60)Co gamma-ray data here for doses up to 1.5 Gy, using a low-yield serum batch and only one medium change, are in agreement with published frequencies of neoplastic transformation of human hybrid cells. For 3.4 MeV alpha-particles (LET = 124 keV/mum) and 0.565 MeV monoenergetic neutrons relative to low doses of (60)Co gamma-rays, a maximum relative biological effectiveness (RBE(M)) of 2.8 +/- 0.2 and 1.5 +/- 0.2, respectively, was calculated. Surprisingly, at higher doses of (60)Co gamma-rays lower frequencies of neoplastic transformation were observed. This non-monotonic dose relationship for neoplastic transformation by (60)Co gamma-rays is likely due to the lack of a G2/M arrest observed at low doses resulting in higher transformation frequencies per dose, whereas the lower frequencies per dose observed for higher doses are likely related to the induction of a G2/M arrest.

  7. Study of {sup 60}Co as gamma source in backscatter gamma densitometers

    Energy Technology Data Exchange (ETDEWEB)

    Gholipour Peyvandi, R.; Taheri, A.; Rahmanzadeh Tootkaleh, S.; Askari Lehdarboni, M. [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of); Islami Rad, S.Z. [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of); Univ. of Qom (Iran, Islamic Republic of). Dept. of Physic

    2015-07-15

    In this work the performance of backscatter gamma densitometer is studied using {sup 60}Co as gamma source. The ability of the densitometer to determine the liquid's interfaces in multi-phase flows was assessed. The aim mainly was to investigate the possibility of using {sup 60}Co in this system. Furthermore, a comparison between {sup 60}Co and was done. The obtained results indicate that {sup 60}Co can be advantageous in this regard.

  8. Comparative effects of 60Co gamma-rays and neon and helium ions on cycle duration and division probability of EMT 6 cells. A time-lapse cinematography study.

    Science.gov (United States)

    Collyn-d'Hooghe, M; Hemon, D; Gilet, R; Curtis, S B; Valleron, A J; Malaise, E P

    1981-03-01

    Exponentially growing cultures of EMT 6 cells were irradiated in vitro with neon ions, helium ions or 60Co gamma-rays. Time-lapse cinematography allowed the determination, for individual cells, of cycle duration, success of the mitotic division and the age of the cell at the moment of irradiation. Irradiation induced a significant mitotic delay increasing proportionally with the delivered dose. Using mitotic delay as an endpoint, the r.b.e. for neon ions with respect to 60Co gamma-rays was 3.3 +/- 0.2 while for helium ions it was 1.2 +/- 0.1. Mitotic delay was greatest in those cells that had progressed furthest in their cycle at the time of irradiation. No significant mitotic delay was observed in the post-irradiation generation. Division probability was significantly reduced by irradiation both in the irradiated and in the post-irradiated generation. The reduction in division probability obtained with 3 Gy of neon ions was similar to that obtained after irradiation with 6 Gy of helium ions or 60Co gamma-rays.

  9. Tenth value layers for 60Co gamma rays and for 4, 6, 10, 15, and 18 MV x rays in concrete for beams of cone angles between 0 degrees and 14 degrees calculated by Monte Carlo simulation.

    Science.gov (United States)

    Jaradat, Adnan K; Biggs, Peter J

    2007-05-01

    The calculation of shielding barrier thicknesses for radiation therapy facilities according to the NCRP formalism is based on the use of broad beams (that is, the maximum possible field sizes). However, in practice, treatment fields used in radiation therapy are, on average, less than half the maximum size. Indeed, many contemporary treatment techniques call for reduced field sizes to reduce co-morbidity and the risk of second cancers. Therefore, published tenth value layers (TVLs) for shielding materials do not apply to these very small fields. There is, hence, a need to determine the TVLs for various beam modalities as a function of field size. The attenuation of (60)Co gamma rays and photons of 4, 6, 10, 15, and 18 MV bremsstrahlung x ray beams by concrete has been studied using the Monte Carlo technique (MCNP version 4C2) for beams of half-opening angles of 0 degrees , 3 degrees , 6 degrees , 9 degrees , 12 degrees , and 14 degrees . The distance between the x-ray source and the distal surface of the shielding wall was fixed at 600 cm, a distance that is typical for modern radiation therapy rooms. The maximum concrete thickness varied between 76.5 cm and 151.5 cm for (60)Co and 18 MV x rays, respectively. Detectors were placed at 630 cm, 700 cm, and 800 cm from the source. TVLs have been determined down to the third TVL. Energy spectra for 4, 6, 10, 15, and 18 MV x rays for 10 x 10 cm(2) and 40 x 40 cm(2) field sizes were used to generate depth dose curves in water that were compared with experimentally measured values.

  10. 49. Biological dose assessment by the analyses of chromosomal aberrations and CB micronuclei in two victims accidentally exposed to 60Co gamma-rays

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@Biological doses were estimated by using the yields of dicentrics plus rings(dic+r) and cytokinesis-block micronuclei (CBMN) for two victims of the 60Co radiation source accident occurred on Mar 6,2001 in the City of Xuchang(victim A), and Jun 26,2001 in the City of Kaifeng(victim B), Henan Province, respectively. The whole blood of the victim A (male, 37 years old) and the victim B (female, 27 years old)

  11. Investigation of the /sup 59/Co(n,. gamma. )/sup 60/Co reaction with unpolarized and polarized neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Kopecky, J. (Stichting Energieonderzoek Centrum Nederland, Petten. Nuclear Structure Group); Delfini, M.G. (Stichting Energieonderzoek Centrum Nederland, Petten. Nuclear Structure Group; Rijksuniversiteit Utrecht (Netherlands). Fysisch Lab.); Chrien, R.E. (Brookhaven National Lab., Upton, NY (USA))

    1984-10-15

    Capture of 24 keV neutrons and polarized as well as unpolarized thermal neutrons in /sup 59/Co has been investigated. Of the 350 ..gamma..-rays observed 335 could be placed in a /sup 60/Co level scheme containing 144 levels. The reaction Q-value amounts to 7491.92(8) keV. The chi/sup 2/ analysis of the circularly polarized ..gamma..-rays results in 31 unambiguous spin assignments for /sup 60/Co levels. The fraction of the J=4/sup -/ channel in the thermal capture was determined to be (80 +- 1)%. An average ..gamma..-ray multiplicity of 2.3 gammas per neutron capture was observed. The resulting level scheme is compared to shell-model predictions. Possible reaction mechanisms are discussed.

  12. Microdosimetry of DNA conformations: relation between direct effect of (60)Co gamma rays and topology of DNA geometrical models in the calculation of A-, B- and Z-DNA radiation-induced damage yields.

    Science.gov (United States)

    Semsarha, Farid; Raisali, Gholamreza; Goliaei, Bahram; Khalafi, Hossein

    2016-05-01

    In order to obtain the energy deposition pattern of ionizing radiation in the nanometric scale of genetic material and to investigate the different sensitivities of the DNA conformations, direct effects of (60)Co gamma rays on the three A, B and Z conformations of DNA have been studied. For this purpose, single-strand breaks (SSB), double-strand breaks (DSB), base damage (BD), hit probabilities and three microdosimetry quantities (imparted energy, mean chord length and lineal energy) in the mentioned DNA conformations have been calculated and compared by using GEometry ANd Tracking 4 (Geant4) toolkit. The results show that A-, B- and Z-DNA conformations have the highest yields of DSB (1.2 Gy(-1) Gbp(-1)), SSB (25.2 Gy(-1) Gbp(-1)) and BD (4.81 Gy(-1) Gbp(-1)), respectively. Based on the investigation of direct effects of radiation, it can be concluded that the DSB yield is largely correlated to the topological characteristics of DNA models, although the SSB yield is not. Moreover, according to the comparative results of the present study, a reliable candidate parameter for describing the relationship between DNA damage yields and geometry of DNA models in the theoretical radiation biology research studies would be the mean chord length (4 V/S) of the models.

  13. Performance of a Roos ionization chamber in gamma radiation beams ({sup 60}Co)

    Energy Technology Data Exchange (ETDEWEB)

    Perini, Ana P.; Neves, Lucio P.; Caldas, Linda V.E., E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Among the different types of dosimetry instruments, the ionization chambers are the most practical and and important radiation measurement devices due to their high sensitivity and relatively constant response within a wide range of energies. A commercial PTW ionization chamber (Roos electron chamber) usually utilized in X-ray beams, was tested to verify the possibility of its dosimetric application in {sup 60}Co beams. The main tests in this work were: short- and long-term stability, saturation, ion collection efficiency, polarity effect, leakage current and angular dependence. The characterization tests were performed using a Gammatron {sup 60}Co irradiator and a special goniometer made of PMMA. All results were within international recommendations. The reproducibility test presented results within the recommended limit of {+-}1%, and all coefficients of variation observed in the repeatability test were lower than {+-}0.07%. The ion collection efficiency was better than 99.9% for both polarities. For all pairs of polarity evaluated during the saturation test, the polarity effect was lower than the recommended limit. The maximum variation obtained for angular dependence test was only 0.5%. The chamber tested in this work achieved the expected results in the case of all pre-operational tests realized: stability, leakage current, angular dependence, saturation, ion collection and polarity effect. Evaluating the satisfactory results obtained, it is possible to indicate the usefulness of this ionization chamber for dosimetry in {sup 60}Co gamma radiation beams. (author)

  14. Resveratrol Effects on Life Span and Fertility of Caenorhabditis Elegans Subject to 60Co Gamma Ray Irradiation%白藜芦醇对60Coγ射线照射线虫寿命和生殖的影响

    Institute of Scientific and Technical Information of China (English)

    叶侃; 季晨博; 郭锡熔; 古桂雄

    2011-01-01

    Caenorhabditis elegans was used as experimental model to investigate radiation effect of resveratol on caenorhabdities elegans irradiated by 60Co γray. Treatment with resveratrol can increase average life span and spawning rate, improve the surrival rate of eggs, and protect their mitochondrion function of cacnorhabdities elegans exposure to 60Co rr ray. The results indicate that resveratrol has radiation protection effects, which might be related to its action on ROS decrease and mitochondrial defend.%以线虫作为实验模型,观察白藜芦醇(RES)对受60Coγ射线照射线虫的保护作用.结果表明,白藜芦醇能提高受照射线虫的寿命,增加产卵率,提高卵的存活率,保护其线粒体功能.其作用机制可能与白藜芦醇减轻氧自由基所致的线虫线粒体损伤有关.

  15. Decoloration Kinetics of Waste Cooking Oil by 60Co γ-ray/H2O2

    Science.gov (United States)

    Xiang, Yulin; Xiang, Yuxiu; Wang, Lipeng

    2016-03-01

    In order to decolorize, waste cooking oil, a dark red close to black solution from homes and restaurants, was subjected to 60Co γ-ray/H2O2 treatment. By virtue of UV/Vis spectrophotometric method, the influence of Gamma irradiation to decoloration kinetics and rate constants of the waste cooking oil in the presence of H2O2 was researched. In addition, the influence of different factors such as H2O2 concentration and irradiation dose on the decoloration rate of waste cooking oil was investigated. Results indicated that the decoloration kinetics of waste cooking oil conformed to the first-order reaction. The decoloration rate increased with the increase of irradiation dose and H2O2 concentration. Saponification analysis and sensory evaluation showed that the sample by 60Co γ-ray/H2O2 treatment presented better saponification performance and sensory score. Furthermore, according to cost estimate, the cost of the 60Co γ-ray/H2O2 was lower and more feasible than the H2O2 alone for decoloration of waste cooking oil.

  16. Dose-dependent and gender-related radiation-induced transcription alterations of Gadd45a and Ier5 inhuman lymphocytes exposed to gamma ray emitted by (60)Co.

    Science.gov (United States)

    Tavakoli, Hassan; Manoochehri, Mahdi; Modarres Mosalla, Sayed Mahdi; Ghafori, Mostafa; Karimi, Ali Akbar

    2013-04-01

    Growth arrest DNA damage-inducible 45a gene (Gadd45a) and immediate early response gene 5 (Ier5) have been emphasised as ideal radiation biomarkers in several reports. However, some aspects of radiation-induced transcriptional alterations of these genes are unknown. In this study, gender-dependency and dose-dependency as two factors that may affect radiation-induced transcription of Gadd45a and Ier5 genes were investigated. Human lymphocyte cells from six healthy voluntary blood donors (three women and three men) were irradiated in vitro with doses of 0.5-4.0 Gy from a (60)Co source and RNA isolated 4 h later using the High Pure RNA Isolation Kit. Dose and gender dependency of radiation-induced transcriptional alterations of Gadd45a and Ier5 genes were studied by quantitative real-time polymerase chain reaction. The results showed that as a whole, Gadd45a and Ier5 gave responses to gamma rays, while the responses were independent of radiation doses. Therefore, regardless of radiation dose, Gadd45a and Ier5 can be considered potential radiation biomarkers. Besides, although radiation-induced transcriptional alterations of Gadd45a in female and male lymphocyte samples were insignificant at 0.5 Gy, at other doses, their quantities in female samples were at a significantly higher level than in male samples. Radiation-induced transcription of Ier5 of females samples had a reduction in comparison with male samples at 1 and 2 Gy, but at doses of 0.5 and 4 Gy, females were significantly more susceptible to radiation-induced transcriptional alteration of Ier5.

  17. Immunohistochemical study on effects of [sup 60]Co [gamma] irradiation on salivary gland ducts of rat

    Energy Technology Data Exchange (ETDEWEB)

    Saitoh, Kazuhiko (Meikai Univ., Sakato, Saitama (Japan). School of Dentistry)

    1992-09-01

    Cytokeratin distribution in salivary glands was detected by use of polyclonal antikeratin antiserum (TK) and monoclonal antibodies (KL 1, RGE 53, and RPN 1164). The salivary glands of male rats received either 17.82 Gy or 27.97 Gy [sup 60]Co [gamma] irradiation in a single exposure and were then compared immunohistochemically with those of normal rats. Polyclonal anti-keratin antiserum (TK), which reacts with 41-65 KD keratins, stained almost all ducts in normal glands. RPN 1164 (no. 8 keratin) staining was negative in intercalated ducts of normal parotid and submandibular glands, but strongly positive in both striated and excretory ducts of these glands. Monoclonal antibody KL 1 (55-57 KD keratins) and RGE 53 (no. 18 keratin) did not bind to any ductal or acinar epithelia. Only in the sublingual gland were acini positive for TK staining, possibly indicating myoepithelial cells. No effects of [sup 60]Co [gamma] irradiation were apparent regarding keratin distribution in the intercalated in apical cytoplasm by [sup 60]Co [gamma] irradiation. Also, in the excretory duct, the basal side of the cells exhibited weakened staining following [sup 60]Co [gamma] irradiation were the most significant in the parotid and the least in the sublingual gland. Also this reaction depended upon the doses of [sup 60]Co used. The present findings suggested that negative or weakened staining at the basal and perinuclear portions of striated duct cells specifically reflects the primary or secondary cell damage produced by [sup 60]Co [gamma] irradiation. Since the distribution of cytoskeletal proteins in the cytoplasm reflects certain pathological conditions, immunohistochemical detection of these proteins seem to have a diagnostic value with respect to cellular injury. (J.P.N.) 77 refs.

  18. Activity evaluation from different native or irradiated with {sup 60} Co gamma rays snake venoms and their inhibitory effect on Leishmania (Leishmania) amazonensis; Avaliacao da atividade de diferentes venenos de serpentes, nativos ou irradiados, com radiacao gama de {sup 60} Co, quanto ao poder inibitorio do crescimento de Leishmania (Leishmania) amazonensis

    Energy Technology Data Exchange (ETDEWEB)

    Lourenco, Cecilia de Oliveira

    2000-07-01

    Cutaneous leishmaniasis is a disease, caused by Leishmania parasites, that occurs frequently in tropical and sub-tropical regions of the world. Skin lesions that could results in disfiguring aspect characterize it. The treatment is based on few drugs as antimony salts or pentamidine that are toxic with increasing resistance by the parasite. Alternative forms of disease treatment are in constant search, including natural components as snake venoms. Previous studies demonstrate that some components of snake venoms have an inhibitory effect against those parasites, including Leishmania species. Although snake venoms presented high toxicity, several methods have been described to detoxify most or some of their toxic components, with favorable results by the use of gamma irradiation. In this report we tested several native and irradiated snake venoms for inhibitory effect against Leishmania (Leishmania) amazonensis parasite and LLCMK{sub 2} mammalian cells, with enzymatic tests and electrophoresis. There are significant activity in Acanthophis antarcticus, Agkistrodon bilineatus, Bothrops moojeni, Bothrops jararaca, Hoplocephalus stephensi, Naja melanoleuca, Naja mossambica, Pseudechis australis, Pseudechis colletti, Pseudechis guttatus and Pseudechis porphyriacus, venom being inactive Pseudonaja textilis, Notechis ater niger, Notechis scutatus. Oxyuranus microlepidotus and Oxyuranus scutellatus venoms. After 2 KGy of {sup 60}Co irradiation most venom loses significantly their activity. Venoms with antileishmanial activity presented L-amino acid oxidase (L-AO) activity and showed common protein with a molecular weight about 60kDa in SDS-PAGE. These results indicate that L-AO activity in those venoms are probably related with antileishmanial effect. (author)

  19. 60Co gamma radiation effect on AlGaN/AlN/GaN HEMT devices

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-Ping; LUO Yin-Hong; WANG Wei; ZHANG Ke-Ying; GUO Hong-Xia; GUO Xiao-Qiang; WANG Yuan-Ming

    2013-01-01

    The testing techniques and experimental methods of the 60Co gamma irradiation effect on AlGaN/AlN/GaN high electron mobility transistors (HEMTs) are established.The degradation of the electrical properties of the device under the actual radiation environment are analyzed theoretically,and studies of the total dose effects of gamma radiation on AlGaN/AlN/GaN HEMTs at three different radiation bias conditions are carried out.The degradation patterns of the main parameters of the AlGaN/AlN/GaN HEMTs at different doses are then investigated,and the device parameters that were sensitive to the gamma radiation induced damage and the total dose level induced device damage are obtained.

  20. 60Coγ射线对生理盐水和玉米中黄曲霉孢子的辐照效应研究%Irradiation effect of 60Co gamma ray on Aspergillus flavus spores in normal saline and maize

    Institute of Scientific and Technical Information of China (English)

    钟凯; 高翔; 计融

    2011-01-01

    目的 研究γ射线对黄曲霉孢子辐照效应.方法 两种介质中不同浓度黄曲霉孢子经不同剂量辐照后进行菌落计数,计算D值和理论最小杀灭剂量,并实验验证实际最小杀灭剂量.结果 生理盐水中高浓度孢子D值0.39kGy,最低杀灭剂量2.5kGy,低浓度孢子D值0.47kGy,最低杀灭剂量1.5kGy;玉米中高浓度孢子D值为0.67kGy,最低杀灭剂量3.0kGy,低浓度孢子D值为0.72kGy,最低杀灭剂量2.0kGy.结论 3.0kGy可用于粮食中黄曲霉的杀灭.%Objective To observe irradiation effect of gamma ray on Aspergillus flavus spores.Methods Aspergillus flavus spores of different concentration were prepared on two media and were exposed to gamma ray.D10 values and theoretical minimal sterilizing doses were calculated by colony counting results.Actual minimal sterilizing doses were verified according to theoretical dose.Results D10 value and minimal sterilizing dose of high concentration spore in normal saline were 0.39kGy and 2.5kGy.Those of low concentration spore in normal saline were 0.47kGy and 1.5kGy.D10 value and minimal sterilizing dose of high concentration spore in maize were 0.67kGy and 3.0kGy.Those of low concentration spore in maize were 0.72kGy and 2.0kGy.Conclusion 3.0kGy may be suitable for grain processing to sterilize Aspergillus flavus.

  1. Modifications in structural, cation distribution and magnetic properties of {sup 60}Co gamma irradiated Li-ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Mane, Maheshkumar L. [Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad (M.S.) 431 004 (India); Shirsath, Sagar E., E-mail: shirsathsagar@hotmail.com [Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad (M.S.) 431 004 (India); Dhage, Vinod N.; Jadhav, K.M. [Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad (M.S.) 431 004 (India)

    2011-09-15

    Highlights: {yields} Gamma irradiation induced defects in lithium ferrite. {yields} Modifications in structural and magnetic properties. {yields} Fe{sup 3+} changes to Fe{sup 2+} after gamma irradiation. - Abstract: Polycrystalline samples of Li{sub 0.5}Fe{sub 2.5}O{sub 4} ferrite precursor were prepared by conventional standard double sintering ceramic technique and then irradiated with three different doses of {sup 60}Co gamma rays. The crystal structure and phase orientation of the irradiated and unirradiated samples of Li{sub 0.5}Fe{sub 2.5}O{sub 4} ferrite was done by using X-ray diffraction technique at room temperature. The lattice parameter of the studied samples increased due to the formation of Fe{sup 2+} ions under the ionizing effect of gamma radiation. The strain in the materials due to the irradiation was calculated from XRD data. Scanning electron microscope (SEM) studies indicate that the irradiation causes amorphization, especially at the grain boundaries. The cation distribution was calculated from XRD data analysis. By using cation distribution structural parameters such as theoretical lattice constant, ionic radii of available sites and the oxygen parameter 'u' have been calculated. The estimated cation distribution and other structural parameters shows strong influence of gamma rays on polycrystalline Li-ferrite. The magnetic properties of irradiated and unirradiated lithium ferrite were performed by using pulse field hysteresis loop technique at room temperature. Electrical properties such as diffusion coefficient and dielectric properties were carried out with the influence of gamma irradiation. Activation energy of diffusion process decreased after irradiation. The increase of diffusion coefficient with increasing dose rate of gamma irradiation was reinforced by the increase of Fe{sup 2+} ions and the displacement of metal ions from its original sites under the effect of gamma irradiation.

  2. Microstructural study of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-x}/Ag samples irradiated with {sup 60}Co {gamma} rays at high doses

    Energy Technology Data Exchange (ETDEWEB)

    Rangel, R. [Programa de Postgrado en Fisica de Materiales, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Apartado Postal 2681, CP 22800, Ensenada, BC (Mexico); Galvan, D.H. [CECIMAC-UNAM, Apartado Postal 2681, CP 22800, Ensenada, BC (Mexico); Adem, E. [Instituto de Fisica-UNAM, Apartado Postal 20-364, CP 01000, Mexico DF (Mexico); Bartolo-Perez, P. [CINVESTAV-IPN Unidad Merida, Departamento de Fisica Aplicada, Merida, Yucatan (Mexico); Maple, M.B. [Physics Department and Institute for Pure and Applied Physical Sciences, La Jolla, CA (United States)

    1998-06-01

    We have investigated the damage induced by irradiation in Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-x} silver added samples. The samples were prepared with 0 and 6.5 wt% of silver and irradiated by high-energy {gamma} irradiation (50-150 Mrad). The roles of silver and dosage irradiation are discussed in terms of their effects on microstructure, crystallinity, critical temperature (T{sub c}) and zero-resistance temperature (T{sub 0}). After irradiation, T{sub c} decreased while the room-temperature electrical resistance increased by a factor of 8 for some of the samples. The difference in T{sub 0} between irradiated and non-irradiated YBCO samples was of the order of 10 K. We have found that the difference is bigger for silver-added samples. We have also observed several changes in diffraction patterns of YBCO and YBCO-silver samples. SEM images, EDS and XPS analysis showed that silver resided inside the grains as single atoms and as metallic clusters. The relative concentrations of the elements in samples were quantified by Auger electron spectroscopy. The values showed a gradual increase for radiation doses ranging between 0 and 100 Mrad. For doses up to 100 Mrad, J{sub c} decreased because of the weak-link breakage induced by high doses of {gamma} rays. (author)

  3. Action of Bothrops moojeni venom and its L-amino acid oxidase fraction, treated with {sup 60}Co gamma rays, in Leishmania spp; Acao do veneno de Bothrops moojeni e sua fracao L-aminoacido oxidase, submetida ao tratamento com raios gama de {sup 60}Co, em Leishmania spp

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Andre Gustavo Tempone

    1999-07-01

    Bothrops moojeni venom showed an anti leishmania activity in vitro, as determined by a cell viability assay using the reduction of MTT. After venom purification, by chromatography techniques, the fractions with anti leishmania and L-amino acid oxidase activities, eluted in the same positions. The molecular weight of the enzyme was estimated to be 140 kDa by molecular exclusion chromatography, and 69 kDa, by SDS-PAGE, migrating as a single band, with an isoelectric point of 4.8 as determined by isoelectric focusing. The purified LAO from B. moojeni venom, 135-fold more active than crude venom, showed homo dimeric constitution, and was active against Leishmania spp from the New World, with an effective concentration against L(L). amazonensis of 1.80 {mu}g/ml (EC{sub 50}), L.(V.) panamensis (0.78 |{mu}g/ml) and L.(L.) chagasi (0.63 ({mu}g/ml). Ultrastructural studies of promastigotes affected by LAO demonstrated cell death, with edema in several organelles such as mitochondria and nuclear membrane, before cell disruption and necrosis. The action of LAO was demonstrated to be hydrogen peroxide-dependent. Studies with LLCMK-2 cells, treated with LAO, showed a toxic effect, with an EC{sub 50} of 11|{mu}g/ml. Irradiation of LAO with 6{sup 0C}o gamma rays, did not affect its whole oxidative activity, neither detoxified the enzyme. Amastigotes treated with LAO were not affected by its hydrogen peroxide, otherwise, the exogenous product, killed amastigotes with an EC{sub 50} of 0.67mM. These data could be of help in the development of alternative therapeutic approaches to the treatment of leishmaniasis. (author)

  4. Impaired colony-forming ability following. gamma. irradiation of skin fibroblasts from tuberous scierosis patients. [/sup 60/Co

    Energy Technology Data Exchange (ETDEWEB)

    Paterson, M.C.; Sell, B.M.; Smith, B.P.; Bech-Hansen, N.T.

    1982-05-01

    The radiosensitivity of cultured dermal fibroblasts from human subjects afflicted with tuberous sclerosis (TS), a hereditary neurocutaneous syndrome, was assessed by assaying loss of colony-forming ability in response to acute ..gamma..-ray exposure. Related to control strains from clinically normal donors, three cell lines (GM1635, GM1643, GM2333) from two affected patients displayed enhanced sensitivity to inactivation by /sup 60/Co ..gamma..-ray treatment, whether administered oxically (air-saturated) or hypoxically (N/sub 2/-gassed); a fourth strain (GM1644) from a third patient exhibited normal radiosensitivity under both treatment conditions. The post-..gamma..-irradiaton colony-forming ability of the three hypersensitive TS strains was intermediate between that of normal controls and that of strains from patients inheriting the radiotherapy-sensitive neurovascular disorder ataxia telangiectasia. The variability in the radioresponse of the TS stains (three sensitive and one normal) is not surprising, considering the widely recognized clinical heterogeneity in the disease. Our findings, aside from providing a laboratory marker for early (possible presymptomatic) detection of persons at high risk for TS, may lead to a better understanding of the origin and progressive development of this multifaceted syndrome.

  5. Effect of ethanolic extract of propolis on cell viability of chinese hamster ovary cells (CHO-K1) irradiated with {sup 60}CO gamma-rays using differential staining technique

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Marcos P.M. de; Castro, Renato F. de; Okazaki, Kayo; Vieira, Daniel P., E-mail: dpvieira@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    The objective of present study was to assess the effect of Brazilian propolis (AF-08) on CHO-K1 cells irradiated with {sup 60}Co, through the differential staining technique, using acridine orange and ethidium bromide. The cells were pre-incubated with different concentrations of propolis (50, 100 and 200 μg/mL) for 24h and irradiated with 5 Gy, analyzed at 24 and 48h after exposure. This technique is based on the cell capacity to incorporate fluorescent DNA dyes, where the viable (green), apoptotic (orange/yellow) and necrotic (red) cells can be identified through fluorescence microscopy. Digital high-resolution images were acquired from at least 5 visualization fields, and cells were analyzed using ImageJ and Flowing software. This approach permitted to analyze a large number of cells/sample with the time reduction, much easier and faster, proportioning more statistical power of the technique. The treatment with propolis only was not cytotoxic at 24 and 48h, except for the higher concentration of 200 μg/mL associated or not with radiation, increasing apoptotic and mainly necrotic cells (p<0.001). The data showed a promising use of propolis as well as technique used, pointing out that 200 μg/mL of propolis was cytotoxic, but at lower one (50 μg/mL) presented a radioprotective effect in irradiated CHO-K1 cells. (author)

  6. Gamma 60Co-irradiation of organic matter in the Phosphoria Retort Shale

    Science.gov (United States)

    Lewan, M. D.; Ulmishek, G. F.; Harrison, W.; Schreiner, F.

    1991-04-01

    Irradiation experiments were conducted on a thermally immature rock sample of the Phosphoria Retort Shale and its isolated kerogen. A 60Co-source for gamma radiation was employed at dosages ranging from 81 to 885 Mrads, which are attainable by Paleozoic and Precambrian black shales with syngenetic uranium enrichments. Kerogen elemental, isotopic, and pyrolysate compositions are not affected at these dosages, but the bitumens extracted from the irradiated rock are affected. The major effects are reductions in the amounts of bitumen, acyclic isoprenoids, and high-molecular weight acyclic carboxylic acids. Natural differences in the amounts of bitumen and acyclic isoprenoid due to regional and stratigraphie variations in organic source input and depositional conditions make the radiation-induced reductions in these parameters difficult to use as indicators of natural radiation damage in black shales. However, the preferential reduction in the high-molecular weight acyclic carboxylic acids, which are ubiquitous in the living precursory organic matter, is diagnostic of experimental γ-irradiation but may not be diagnostic of natural irradiation. The overall process associated with radiation damage is polymerization by cross-linking through a free radical mechanism. As a result, irradiation of organic matter in black shales is more likely to retard rather than enhance petroleum generation.

  7. The effect of 60Co-gamma radio-sterilization on Boswellia carterii essential oil composition

    OpenAIRE

    P. Badr; S. Daneshamouz; A.A. Mohammadi; A.R. Akbarizadeh; Afsharypuor, S.

    2016-01-01

    Background and objectives:Gamma-irradiation is used vastly for both decontamination and sterilization of natural products; but these high-energy rays can affect heat-sensitive essential oils. Methods: The oleo-gum-resin of Boswellia carterii (Burseraceae) was sterilized by γ-irradiation at dose 30 KGy. The essential oils obtained by hydrodistillation of non-irradiated Boswellia (NIB) and irradiated Boswellia (IB) were analyzed by GC/MS and the changes were compared. The structure of octyl ace...

  8. Evaluation of fruit productivity and quality in Hass avocado submitted to {sup 60}Co gamma radiation; Evaluacion de productividad y calidad de fruta en aguacate Hass sometido a radiacion gamma de {sup 60}Co

    Energy Technology Data Exchange (ETDEWEB)

    Cruz T, E. De la; Ibanez P, J.; Mijares O, P.; Garcia A, J.M. [Instituto nacional de Investigaciones Nucleares, Departamento de Biologia, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1999-07-01

    Evaluation of productivity, postharvest behavior and fruit quality was performed on four years Hass avocado trees irradiated with {sup 60} Co gamma rays in doses of 5, 10, 15, 20 and 25 Gy, established in the ''La Labor'' Experimental Center of the Centro de Investigaciones Cientificas y Tecnologias del Aguacate en el Estado de Mexico (CICTAMEX) at Temascaltepec Mexico. Productivity had a significant increase in the dose of 15 Gy being the average number of fruits nearly 400 % more than the control at fruit setting, being such difference reduced at fruit harvesting to 300 %. In regard to postharvest performance, the respiration index (mg CO{sub 2}/kg/hr) did not show significant differences among treatments. Also others variables such as physiological weight losses, texture, maturity pattern, and sensorial tests (color, flavor, aroma, texture) were not different in regard to the control. This mean that radiation has altered productivity but not the quality and postharvest behavior of fruits. (Author)

  9. Response of avocado genotypes to improvement through {sup 60}Co gamma radiation; Respuesta de diversos genotipos de aguacate al mejoramiento por radiacion gamma de {sup 60}Co

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, E. De la; Rubi A, M.; Garcia A, J.M. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    Ten avocado genotypes were subjected to gamma radiation from 0 to 45 Gy in 1993. Vegetative and reproductive data were analysed in a factorial design. Genotypes differed significative on height and fruit number. Radiation affected significative fruit number but not tree height. ''Hass'' showed strongest interaction between genotype and doses, for fruit number. (Author)

  10. Effect of 60Co gamma irradiation on dielectric and complex impedance properties of Dy3+ substituted Ni-Zn nanoferrites

    Science.gov (United States)

    Veena, M.; Somashekarappa, A.; Shankaramurthy, G. J.; Jayanna, H. S.; Somashekarappa, H. M.

    2016-12-01

    Nanocrystalline Ni1-xZnxFe2-yDyyO4 (x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0; y=0.0 and 0.1) ferrites were synthesized by combustion method. Ni-Zn-Dy nanoferrites were investigated by X-ray diffraction, scanning electron microscopy, dielectric and impedance properties, before and after γ-irradiation process by 60Co γ-radiation with a dose rate of 310 kGy. The lattice parameter of irradiated samples increased attributed to the conversion of smaller size Fe3+ ions to larger size Fe2+ ions on ionizing effect of gamma radiation. Experimental results reveal that reduction in dielectric constant (ε‧), loss tangent (tan δ), real (Z‧) and imaginary (Z‧‧) impedance and increase in ac conductivity (σac) have been increased with increasing in frequency. It was found that ε‧, tan δ, σac increase, Z‧‧ and Z‧‧ reach a maximum value and thereafter decrease with further Zn ion substitution. The values of ε‧, tan δ and σac decrease with Dy3+ substitution and enhanced after irradiation. The complex impedance analysis suggesting predominant contribution to conduction was through the grain boundary.

  11. Radiosensibilidad de semillas de soya a los rayos gamma 60Co

    Directory of Open Access Journals (Sweden)

    C. de la Fé

    2000-01-01

    Full Text Available El presente estudio se desarrolló en las instalaciones del Instituto Nacional de Ciencias Agrícolas, con el objetivo de evaluar la radiosensibilidad de semillas de soya a los rayos gamma 60Co. Para su ejecución, se seleccionaron e irradiaron muestras de 50 semillas de la variedad Cubasoy-23, las que fueron sembradas en condiciones semicontroladas (macetas en la campaña de primavera, 1997. Las dosis de radiación fueron desde los 50 hasta los 480 Gy, con incrementos de 50 Gy entre las dosis de 50 y 200 Gy e incrementos de 40 Gy entre esta última y la dosis de 480 Gy. Las evaluaciones realizadas consistieron en porcentaje de semillas germinadas a los tres, seis y nueve días de la siembra, altura de las plantas a los 10, 20 y 50 días y número de pares de hojas emitidas a los 10 y 20 días de la siembra. El estudio realizado evidenció la ocurrencia de un efecto fuerte de las dosis aplicadas en el porcentaje de semillas germinadas, resultando las dosis próximas a los 280 Gy las de mayor efecto radioestimulador de la germinación. Desde el punto de vista de la altura de las plantas, el efecto de las dosis aplicadas se correspondió con el descrito para otros materiales biológicos irradiados, caracterizándose este por un aumento a dosis bajas seguido por una reducción cada vez mayor a medida que las dosis aplicadas se incrementaron. Por su parte, la emisión de hojas por las plantas mantuvo un comportamiento en correspondencia con la altura de las plantas. Los resultados del estudio permiten sugerir la aplicación de dosis próximas a los 360 Gy en los trabajos dirigidos a la creación de variabilidad genética en programas de mejora por inducción de mutaciones

  12. [Effect of tonicity of the medium on the sensitivity of Escherichia coli bacteria to gamma-quantum 60Co, ultrasound and hyperthermia].

    Science.gov (United States)

    Morozov, I I; Petin, V G; Morozova, G V

    1998-01-01

    The cell lethality and permeability induced in Escherichia coli B/r and Escherichia coli BS-1 by 60Co gamma-ray irradiation, ultrasound and hyperthermia in media containing different concentrations of NaCl have been investigated. It was shown that independently from the nature of damaging factors hypotonic media increase while hypertonic media in certain range of osmolyte concentration decrease sensitivity of cells to action of this factors. It was proposed that discovered phenomenology was caused by salt modification of status of the cell osmotic homeostasis destabilizing by ionizing radiation, ultrasound or hyperthermia and was not related with the system of dark repair of DNA.

  13. The effect of 60Co-gamma radio-sterilization on Boswellia carterii essential oil composition

    Directory of Open Access Journals (Sweden)

    P. Badr

    2016-10-01

    Full Text Available Background and objectives:Gamma-irradiation is used vastly for both decontamination and sterilization of natural products; but these high-energy rays can affect heat-sensitive essential oils. Methods: The oleo-gum-resin of Boswellia carterii (Burseraceae was sterilized by γ-irradiation at dose 30 KGy. The essential oils obtained by hydrodistillation of non-irradiated Boswellia (NIB and irradiated Boswellia (IB were analyzed by GC/MS and the changes were compared. The structure of octyl acetate as the major component and marker of B. carterii was confirmed by MS/MS. Results: Twenty-five compounds comprising 99.55% of NIB oil and nineteen compounds comprising 98.61% of IB oil were identified. Major constituents which were common for both oils were octyl acetate (52.67 % in NIB, 76.51 % in IB, 1-octanol (6.37 % in NIB, 5.19 % in IB, duva-4, 8, 13-triene-1,3α diol (5.52 % in NIB, 3.94 % in IB, verticiol (13.63 % in NIB and verticillane type diterpene (5.4 % in IB they made up 78.19% and 91.04% of NIB and IB, respectively. Conclusion: Gamma irradiation was an efficient method for sterilization of Boswellia carterii oleo-gum resin, but it resulted in change in the essential oil composition particularly octyl acetate changed from 52.67% to 76.51%.

  14. Study on the energy dependence of gamma radiation detectors for {sup 137}Cs and {sup 60}Co; Estudo da dependencia energetica de detectores de radiacao gama para {sup 137}Cs e {sup 60}Co

    Energy Technology Data Exchange (ETDEWEB)

    Nonato, Fernanda B.C.; Diniz, Raphael E.; Carvalho, Valdir S.; Vivolo, Vitor; Caldas, Linda V.E., E-mail: fbnonato@ipen.b, E-mail: rediniz@ipen.b, E-mail: vcsouza@ipen.b, E-mail: vivolo@ipen.b, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2009-07-01

    38 Geiger-Mueller radiation detectors and 9 ionization chambers were calibrated, viewing to study the energy dependence of the monitor response for gamma radiation fields ({sup 137}Cs and {sup 60}Co). The results were considered satisfactory only for ionization chambers and for some Geiger-Mueller detectors

  15. Influence of 60Co gamma radiation on fluorine plasma treated enhancement-mode highelectron-mobility transistor

    Institute of Scientific and Technical Information of China (English)

    Quan Si; Hao Yue; Ma Xiao-Hua; Yu Hui-You

    2011-01-01

    AlGaN/GaN depletion-mode high-electron-mobility transistor (D-HEMT) and fluorine (F) plasma treated enhancement-mode high-electron-mobility transistor (E-HEMT) are exposed to 60Co gamma radiation with a dose of 1.6 Mrad (Si). No degradation is observed in the performance of D-HEMT. However, the maximum transconductance of E-HEMT is increased after radiation. The 2DEG density and the mobility are calculated from the results of capacitance-voltage measurement. The electron mobility decreases after fluorine plasma treatment and recovers after radiation. Conductance measurements in a frequency range from 10 kHz to 1 MHz are used to characterize the trapping effects in the devices. A new type of trap is observed in the F plasma treated E-HEMT compared with the D-HEMT, but the density of the trap decreases by radiation. Fitting of Gp/ω data yields the trap densities DT = (1 - 3) × 1012 cm-2-·eV-1 and DT = (0.2 - 0.8) × 1012 cm-2·eV-1 before and after radiation, respectively.The time constant is 0.5 ms-6 ms. With F plasma treatment, the trap is introduced by etch damage and degrades the electronic mobility. After 60Co gamma radiation, the etch damage decreases and the electron mobility is improved. The gamma radiation can recover the etch damage caused by F plasma treatment.

  16. 100 Gy 60Co γ-Ray Induced Novel Mutations in Tetraploid Wheat

    Directory of Open Access Journals (Sweden)

    Chuntao Yang

    2014-01-01

    Full Text Available 10 accessions of tetraploid wheat were radiated with 100 Gy 60Co γ-ray. The germination energy, germination rate, special characters (secondary tillering, stalk with wax powder, and dwarf, meiotic process, and high-molecular-weight glutenin subunits (HMW-GSs were observed. Different species has different radiation sensibility. With 1 seed germinated (5%, T. dicoccum (PI434999 is the most sensitive to this dose of radiation. With a seed germination rate of 35% and 40%, this dose also affected T. polonicum (As304 and T. carthlicum (As293. Two mutant dwarf plants, T. turgidum (As2255 253-10 and T. polonicum (As302 224-14, were detected. Abnormal chromosome pairings were observed in pollen mother cells of both T. dicoccoides (As835 237-9 and T. dicoccoides (As838 239-8 with HMW-GS 1Ax silent in seeds from them. Compared with the unirradiated seed of T. polonicum (As304 CK, a novel HMW-GS was detected in seed of T. polonicum (As304 230-7 and its electrophoretic mobility was between 1By8 and 1Dy12 which were the HMW-GSs of Chinese Spring. These mutant materials would be resources for wheat breeding.

  17. Effects of (60)Co gamma irradiation on behavior and gill histoarchitecture of giant fresh water prawn Macrobrachium rosenbergii (DE MAN).

    Science.gov (United States)

    Stalin, A; Broos, K V; Sadiq Bukhari, A; Syed Mohamed, H E; Singhal, R K; Venu-babu, P

    2013-06-01

    Present study was designed to observe the effects of (60)Co gamma radiation in behavioral and histological changes in the gills of giant fresh water prawn Macrobrachium rosenbergii. The adult prawns were irradiated with four different dose levels (3mGy, 30mGy, 300mGy and 3000mGy) and the control group (without irradiation) was maintained separately. Behavioral changes like hyperactivity, loss of balance, reduced swimming rate, slower rate of food intake and convulsions were observed in higher dose levels of 300mGy and 3000mGy. The histological alterations such as accumulated haemocytes in haemocoelic spaces, abnormal gill tips, lifted lamellar epithelium, swollen and fused lamellae, hyperplasic, necrotic, clavate-globate and complete disorganization of lamellae were observed in (60)Co gamma irradiated prawns. Significantly more considerable histological alterations were observed in the highest dose level of 3000mGy, but no mortality was evidenced. This study serves as biomonitoring tool to assess the radiation pollution in the aquatic environment.

  18. Use of {sup 60}Co gamma radiation in increased levels of total polyphenol extracts of bark of Schinus terebinthifolius Raddi

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Gustavo H.F.; Silva, Edvane B.; Silva, Hianna A.M.F.; Amorin, Elba L.C.; Peixoto, Tadeu J.S.; Yara, Ricardo; Lima, Claudia S.A., E-mail: santosghf@hotmail.com, E-mail: edvborges@yahoo.com, E-mail: amdemelo@hotmail.com, E-mail: claudia.salima@gmail.com, E-mail: ricardo.yara@gmail.com, E-mail: tadeu1903@yahoo.com.br, E-mail: elba@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

    2013-07-01

    Schinus terebinthifolius Raddi (Anacardiaceae) is well known as sources of phenolic compounds. Known as mastic pepper, red pepper tree is a plant native to midsize coast of Brazil. Some of its structures have proven antibacterial, anti-inflammatory, antifungal and healing. The aim of this study was to evaluate the difference in the phenol contents of crude extracts that were measured after irradiating the barks of S. terebinthifolius using gamma radiation from {sup 60}Co. The crude extract were divided into a control group and eight experimental groups, which were separated based on the doses of gamma radiation to which they were exposed: 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 20.0 and 50.0 kGy (Assays were performed in triplicate). The results allow observe that gamma radiation promoted in extracts of bark of S. terebinthifolius, many percents increase (p> 0.05) of total polyphenol content between 2.5 kGy (41.93%) and 50.0 kGy (44.52%) compared to 0 kGy (30.07%), with the same gradual to 10.0 kGy, and reaching peak maximum at 10.0 kGy (68.44%). However, the study puts the process of gamma radiation from {sup 60}Co as an alternative significant increase in the percentage of some natural substances of plant material, and subsequently contribute to the augmentation of various therapeutic applications to which they are assigned. (author)

  19. Morphological and histological studies on freshwater prawn Macrobrachium rosenbergii (de man) irradiated with {sup 60}Co gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Stalin, A.; Broos, K.V. [P.G. and Research Department of Zoology, Jamal Mohamed College (Autonomous), Tiruchirappalli 620020, Tamil Nadu (India); Sadiq Bukhari, A., E-mail: abjmc@yahoo.in [P.G. and Research Department of Zoology, Jamal Mohamed College (Autonomous), Tiruchirappalli 620020, Tamil Nadu (India); Syed Mohamed, H.E. [P.G. and Research Department of Zoology, Jamal Mohamed College (Autonomous), Tiruchirappalli 620020, Tamil Nadu (India); Singhal, R.K. [Analytical Spectroscopy Section, Analytical Chemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 4000085 (India); Venu-Babu, P. [Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Center, Trombay, Mumbai 4000085 (India)

    2013-11-15

    Graphical abstract: -- Highlights: •Analyzing the impact of {sup 60}Co gamma radiation (low doses) in M. rosenbergii. •LD{sub 50} identified in 30 Gy; Irradiated exhibits morphological changes than control. •Significantly decreased HSI and histological changes in irradiated groups. •Aberration severities increased as increased of dose level. •Biomonitoring tool in determining low dose radiation pollution in aquatic ecosystem. -- Abstract: This study was framed to investigate the {sup 60}Co gamma radiation induced morphological and histological variations in freshwater prawn Macrobrachium rosenbergii. The LD{sub 50} value of {sup 60}Co gamma irradiated M. rosenbergii observed (by probit analysis) at 30 Gy. Prawns were irradiated to four different dose levels (3 mGy, 30 mGy, 300 mGy and 3000 mGy) using Theratron Phoenix TeleCobalt Unit [P-33] and one control group (without irradiation) maintained separately. Irradiated groups exhibited several morphological variations such as discoloration; damaged rostrum; opaque coloration in cephalothorax; black bands and dot formation in abdomen; deformed uropods and telson in tail regions when compared with control group. The Hepato Somatic Index reflected the severity of radiation on hepatopancreas. Histological variations in gills, hepatopancreas and muscles of irradiated groups were observed. In gills, structural changes such as swollen and fused lamellae, abnormal gill tips, hyperplasic, necrotic and clavate-globate lamellae were observed in gamma irradiated prawns. Accumulation of hemocytes in hemocoelic space, interstitial sinuses filled with abnormal infiltrated hemocytes, the tubular epithelium with ruptured basal laminae, abnormal and coagulated lumen, necrotic tubules, thickened basal laminae, tissue debris, necrotic hepatocytes were observed in irradiated prawn hepatopancreas. In muscle, shrinkage of muscular fiber and necrotic musculature were observed in irradiated prawns. These structural alterations of

  20. Morphological and histological studies on freshwater prawn Macrobrachium rosenbergii (de man) irradiated with (60)Co gamma radiation.

    Science.gov (United States)

    Stalin, A; Broos, K V; Sadiq Bukhari, A; Syed Mohamed, H E; Singhal, R K; Venu-Babu, P

    2013-11-15

    This study was framed to investigate the (60)Co gamma radiation induced morphological and histological variations in freshwater prawn Macrobrachium rosenbergii. The LD50 value of (60)Co gamma irradiated M. rosenbergii observed (by probit analysis) at 30 Gy. Prawns were irradiated to four different dose levels (3 mGy, 30 mGy, 300 mGy and 3,000 mGy) using Theratron Phoenix TeleCobalt Unit [P-33] and one control group (without irradiation) maintained separately. Irradiated groups exhibited several morphological variations such as discoloration; damaged rostrum; opaque coloration in cephalothorax; black bands and dot formation in abdomen; deformed uropods and telson in tail regions when compared with control group. The Hepato Somatic Index reflected the severity of radiation on hepatopancreas. Histological variations in gills, hepatopancreas and muscles of irradiated groups were observed. In gills, structural changes such as swollen and fused lamellae, abnormal gill tips, hyperplasic, necrotic and clavate-globate lamellae were observed in gamma irradiated prawns. Accumulation of hemocytes in hemocoelic space, interstitial sinuses filled with abnormal infiltrated hemocytes, the tubular epithelium with ruptured basal laminae, abnormal and coagulated lumen, necrotic tubules, thickened basal laminae, tissue debris, necrotic hepatocytes were observed in irradiated prawn hepatopancreas. In muscle, shrinkage of muscular fiber and necrotic musculature were observed in irradiated prawns. These structural alterations of the organs it is felt could affect the vital physiological functions such as respiration, osmotic and ionic regulation in gills and muscles; absorption, storage and secretion of the hepatopancreas which in turn could adversely affect the growth and survival of freshwater prawn M. rosenbergii.

  1. Radiolysis of D(+)-carnitine by /sup 60/Co-. gamma. -radiation and formation of L(+)-. beta. -methylcholine

    Energy Technology Data Exchange (ETDEWEB)

    Loester, Heinz; Strack, Erich; Seim, Hermann

    1986-06-01

    The radiolysis of D(+)-carnitine by /sup 60/Co-..gamma..-radiation was examined to obtain optically active ..beta..-methylcholine. It was found that the radiolysis leads to a number of trimethylammonium bases but to no other betaines. (+)-..beta..-Methylcholine and acetonyltrimethylammonium could be identified by means of common analytical methods. The amounts of methylamines formed by irradiation were very small. Racemization of the D(+)-carnitine did not occur during irradiation, L(-)-carnitine was not found when an enzymatical determination method was used. The fact that (+)-..beta..-methylcholine was formed from D(+)-carnitine is pharmacologically important, because acetyl-L(+)-..beta..-methylcholine has a strong interaction with muscarinic receptors.

  2. Effect of {sup 60}Co gamma-irradiation on two-dimensional electron gas transport and device characteristics of AlGaN/GaN HEMTs

    Energy Technology Data Exchange (ETDEWEB)

    Umana-Membreno, G.A.; Dell, J.M.; Parish, G.; Nener, B.D.; Faraone, L. [School of Electrical, Electronic and Computer Engineering, The University ofWestern Australia, Crawley WA 6009 (Australia); Ventury, R.; Mishra, U.K. [Dept. of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106 (United States)

    2005-05-01

    The effect of {sup 60}Co gamma-irradiation on Al{sub 0.33}Ga{sub 0.67}N/GaN high-electron-mobility transistors (HEMTs) has been investigated using DC and geometrical magnetoresistance measurements. The devices studied were of similar epitaxial structure, yet differed in the doping levels of the Al{sub 0.33}Ga{sub 0.67}N barrier layer: (A) nominally undoped and (B) Si-doped with SiN{sub x} passivation. Exposure to cumulative gamma-ray doses up to 20 Mrad(Si) is shown to induce significant changes in drain-current level, threshold voltage and gate leakage current level. Analysis of magnetoresistance characteristics measured at 80 K indicated that irradiation induced an increase in two-dimensional electron-gas (2DEG) density, which leads to negative threshold voltage shifts observable in the drain current versus gate voltage characteristics, attributable to the introduction of defect centers in the Al{sub 0.33}Ga{sub 0.67}N layer and/or at the gate-AlGaN interface. The 2DEG mobility-concentration profiles are shown to remain approximately unchanged for doses up to 20 Mrad(Si). Device failure, evidenced as loss of gate control over the channel and/or excessive gate leakage, occurred after exposure to 30 Mrad(Si) for device A, whereas sample B failed after 20 Mrad(Si) total dose due to failure of half of the gate contact. Degradation of gate and source/drain contacts characteristics with total dose appears to limit the tolerance of the studied HEMTs to {sup 60}Co gamma-irradiation. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. 60Coγ射线2.0 Gy剂量诱导大鼠淋巴细胞基因表达的改变%Study of Differential Gene Expression Profiling in Peripheral Blood Lymphocyte of Rat with 2 .0 Gy Gamma Ray Irradiation

    Institute of Scientific and Technical Information of China (English)

    李建国; 尹晶晶; 秦秀军; 张伟; 周晋源; 闻建华

    2013-01-01

    利用Agilent Rat全基因组芯片技术和实时荧光定量PCR技术,采用60 Coγ射线对SD大鼠全身照射,照射剂量为2.0 Gy ,分析照后6、12、24小时大鼠外周血淋巴细胞的差异表达基因谱和通路,同时对基因芯片结果进行验证。结果表明:(1)照后6小时,差异表达基因有1084个,其中上调的736个,下调的348个;照后12小时,差异表达基因有2590个,其中上调的1621个,下调的969个;照后24小时,差异表达基因有3938个,其中上调的2278个,下调的1660个;3个时间点共同差异表达基因有446个,其中上调的274个,下调的172个。(2)照后6小时,差异表达基因涉及到的通路有18个;照后12小时,差异表达基因涉及到的通路有35个;照后24小时,差异表达基因涉及到的通路有38个。其中通路Cell adhesion molecules、Toxoplasmosis、B cell receptor signaling、Intestinal immune network for IgA Production等在照后3个时间点均有出现。(3)差异表达基因Trmt61a和Enc1的相对定量结果与基因芯片检验结果表达趋势一致。%The study analyzed the differential expression profile and pathway of peripheral blood lymphocyte in SD rats 6 ,12 and 24 hours after irradiation to 2 .0 Gy gamma ray .The results showed that at 6 hours after ir-radiation there were 1084 differentially expressed genes of which 736 genes were up-regulated and 348 genes down-regulated .12 hours after irradiation there were 2590 differentially expressed genes of which 1621 genes were up-regulated and 969 genes down-regulated .24 hours after irradiation there were 3938 differentially ex-pressed genes of which 2278 genes were up-regulated and 1660 genes down-regulated .There were 446 co-ex-pressed differential genes at three time points ,of which 274 genes were up-regulated and 172 genes down-regu-lated .The KEGG analysis revealed that 6h point 18 pathways ,12 hours point 35 pathways ,and 24 hours point

  4. Comparison of the standards for air kerma of the NRC and the BIPM for {sup 60}Co gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C.; Allisy, P.J.; Burns, D.T. [Bureau International des Poids et Mesures (BIPM), 92 - Sevres (France); McCaffrey, J.P.; Ross, C.K. [National Research Council (Canada)

    2010-02-15

    An indirect comparison of the standards for air kerma of the National Research Council (NRC), Canada, and of the Bureau International des Poids et Mesures (BIPM) was carried out in the {sup 60}Co radiation beam of the BIPM in May 2009. The comparison result, based on the calibration coefficients for two transfer standards and expressed as a ratio of the NRC and the BIPM standards for air kerma, is 1.0032 with a combined standard uncertainty of 2.8 * 10{sup -3}. The result of the previous direct comparison in {sup 60}Cogamma rays, made in 1998 and modified in 2007 was 1.0025 (27). The degrees of equivalence between the NRC and the other participants in the key comparison have been calculated and the results are presented in the form of a matrix. A graphical presentation is also given. (authors)

  5. Mortality and growth of cobalt-60 gamma-irradiated adult Pacific oyster, Crassotrea gigas%60Co-γ射线对成体长牡蛎生长的影响及致死效应

    Institute of Scientific and Technical Information of China (English)

    刘晓; 彭小明; 张国范; 赵敏; 郭希明

    2005-01-01

    Effects of ionizing irradiation of 60Coray on mortality and growth of one year-old Pacific oysters ( Crassotrea gigas ) were studied. Irradiation was conducted at 4℃ and without sea water, and the survival, shell length, shell width, whole wet weight and condition index of irradiated oysters were measured. A biphasic dose response effect of 660Co-γ irradiation on Pacific oyster with high stimulatory response dose range to 100 Gy, and strong hormesis effects had been observed. Gamma ray induced mortality happened within 90 days after irradiation, and the relation between dosage ( D ) and mortality at 90 days could be described by the equation of M90 = 0.0041D2- 0. 1816D (R2= 0. 9958) with an LD50/90 of 135 Gy, indicating that the Pacific oyster has strong resistance to 60Co-γ irradiation. Growth in shell length, shell width and whole wet weight of Pacific oyster were also enhanced by 60 Gy of 60Coray. The condition index was also enhanced by 60Co-γ irradiation in the dosage range from 40 to 100 Gy, with the maximum stimulatory response of 2.5 fold of control value at the 40 Gy dosage, suggesting that the accelerating effects of γ ray on growth of the Pacific oyster led to increase in dry meat. Results of this study showed that ionizing irradiation might be useful in the improvement of production traits in shellfish.

  6. Effect of 60Co-gamma radiation on the random walk error of interferometric fiber optic gyroscopes

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Two 60Co-gamma radiation experiments were launched to explore the radiation effect on optical components and interferometric fiber optic gyroscope (IFOG). In optical components radiation experiment, the result showed that polarization-maintaining (PM) fiber coil loss was the most affected parameter in all the RWC (random walk coefficient) related parameters, compared with the weak sensitivity of other components parameters. In the IFOG radiation experiment, the RWC performance degradation was found to be almost due to an increase of the PM fiber attenuation. Based on the experiment result, a RWC prediction model in radiation, which is obtained by embedding PM fiber loss expression into the RWC model, was built following a power law of dose and dose rate. An IFOG RWC in space radiation environment was predicted from radiation dose and dose rate by the RWC prediction model. This RWC value calculated from test data is fully accorded to the RWC value predicted from radiation dose.

  7. Effects of /sup 60/Co-. gamma. irradiation on the cell proliferation kinetics of DMBA-induced tongue carcinoma in hamster

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Toshio

    1987-10-01

    In the vocation of the radiation therapy, it is very important to analize the cell kinetics of the normal and tumor tissues, and the radiation effects. Thus, this study analizes the effects of /sup 60/Co-..gamma.. irradiation to DMBA-induced hamster tongue carcinoma (hereafter ''the tumor'') and normal tongue epithelium (hereafter ''the normal'') by using /sup 3/H-TdR puls labeling technics and percentage labeled mitoses (PLM) method. Result : 1) Cell cycle time (Tc) of the Normal was 42.0 hours, and that of the tumor was 18.1 hours. After irradiation, Tc of the tumor was prolonged, but that of the normal was shortened by about 11 hours. 2) Initial labeling index (L.I.) of the tumor was decreased immidiately after irradiation, but on 7 and 10 days L.I. gained back to the pre-irradiation rate. 3) tumor doubling time (Td) was 6.4 +- 1.6 days, and potential doubling time (Tp) was 18.9 hours. 4) Time of pre-DNA synthetic stage (Tg/sub 1/) of the normal was 31.0 hours and that of the tumor was 8.7 hours. After irradiation, Tg/sub 1/ of the normal was shortened by about 10 hours and that of the tumor was prolonged. 5) After irradiation, time of synthetic stage (Ts) of both the normal and the tumor was slightly prolonged. 6) After irradiation, mitotic stage (Tm) of both the normal and the tumor was not changed. 7) Growth fraction (GF) of the normal was 64.5%, and that of the tumor was 79.8%. After irradiation, it was decreased, while it of the tumor was increased temporarily after irradiation. 8) The rate of cell loss facter of the tumor was 0.88.

  8. Resposta de sementes de amendoim a diferentes doses de radiação gama (60Co Response of peanut seeds to different levels of gamma radiation (60Co

    Directory of Open Access Journals (Sweden)

    Tatiana da S. Santos

    2010-10-01

    Full Text Available A radiação gama, proveniente da fonte de 60Co, é bastante utilizada para esterilização, visando a prevenção da decomposição e a toxidez de origem microbiana em diversos produtos. O grau de radiossensibilidade de um embrião vegetal depende da espécie, do estágio de seu desenvolvimento durante a radiação, da dose empregada e do critério usado para medir o efeito biológico, sendo comumente utilizado o teste de germinação. Objetivou-se, com este trabalho, estudar a sensibilidade do amendoim a radiação gama e seus efeitos na germinação, no vigor e na micoflora das sementes da cultivar BRS Havana, irradiadas com uma fonte de 60Co, tipo gammacell, com taxa de dosagem de 12,5 kGy h-1. As doses testadas em kGy foram as seguintes: 0; 0,5; 1,0; 1,5; 2,0; 2,5; 3,0; 6,0; 9,0; 12,0; 15,0; 18,0; 21,0 e 24,0. Com os resultados obtidos, concluiu-se que as doses acima de 3,0 kGy prejudicaram a viabilidade das sementes e as doses acima de 12 kGy comprometeram totalmente o vigor e a germinação das sementes de amendoim. A radiação a partir da dose 2,0 kGy eliminou os fungos Aspergillus flavus e Aspergillus niger e, a partir da dose 3,0 kGy, eliminou o Aspergillus glaucus. O Penicilium spp. permaneceu em mais de 30% das sementes em todos os tratamentos com radiação, não sendo eliminado até a dose de 24 kGy.The gamma radiation from 60Co source is widely used for sterilization aiming at preventing decomposition and toxicity from microbes in several products. The degree of radiosensitvity of a plant embryo depends on the species, the development stage during radiation, doses used and the criteria used to measure the biological effect, the germination test, being commonly used.This work aimed to study the peanut sensitivity to gamma radiation and its effects in the germination, in the vigour and seeds microflora of cultivar BRS Havana, irradiated with 60Co source, type gammacell with rate of dosage of 12.5 kGy h-1. The tested doses were the

  9. Biochemical and pharmacological studies of native and irradiated crotamine with gamma radiation of {sup 60}Co; Estudo bioquimico e farmacologico das crotaminas nativa e irradiada com radiacao gama de {sup 60}Co

    Energy Technology Data Exchange (ETDEWEB)

    Mitake, Malvina Boni

    2000-07-01

    Ionizing radiation can change the molecular structure and affect the biological properties of biomolecules. This has been employed to attenuate animal toxins. Crotamine is a strongly basic polypeptide from the South American rattlesnake venom, composed of 42 amino acid residues. It induces skeletal muscle spasms leading to a spastic paralysis of hind limbs in mice. The objective of this thesis was carry out biochemical and pharmacological studies of native and irradiated crotamine with {sup 60} Co. Crotamine was purified from Crotalus durissus terrificus venom by Sephadex G-100 gel filtration followed by ion exchange chromatography, using a Fast Performance Liquid Chromatography (FPLC) system. It was irradiated at 2 mg/ml in 0.15 M Na Cl with 2.0 kGy gamma radiation emitted by a {sup 60} Co source. The native and irradiated crotamine were evaluated by biochemical characterization, toxic activity (LD{sub 50} and biodistribution. The native and irradiated crotamine were labelled with 29.6 MBq of {sup 125} I using chloramine T method, and separated in a Sephadex G-50 column. Male Swiss mice (35{+-} 5 g), were injected i.p. with o.1 mL (2.4 x 10{sup 6} cpm/mouse) of {sup 125} I native crotamine or with 0.4 mL (1.3 x 10{sup 6} cpm/mouse) of {sup 125} I irradiated crotamine. At 0.08; 0.25; 0.5; 1; 2; 4; 8; 12 and 24 hours the animal were killed by ether inhalation. Blood, spleen, liver, kidneys, brain, lungs, heart, and skeletal muscle were collected in order to determine radioactivity content. The results showed that gamma radiation did not change the protein concentration, the electroforetic profile or the primary structure of the protein, although differences were shown by spectroscopic techniques. The gamma radiation diminished the toxicity of crotamine, but it did not abolish bioactivity. Biodistribution studies showed that native and irradiated crotamine have hepatic metabolism and renal elimination. The native and irradiated crotamine have affinity by skeletal

  10. Structural and optical analysis of 60Co gamma-irradiated thin films of polycrystalline Ga10Se85Sn5

    Science.gov (United States)

    Ahmad, Shabir; Asokan, K.; Shahid Khan, Mohd.; Zulfequar, M.

    2015-12-01

    The present study focuses on the effects of gamma irradiation on structural and optical properties of polycrystalline Ga10Se85Sn5 thin films with a thickness of ∼300 nm deposited by the thermal evaporation technique on cleaned glass substrates. X-ray diffraction patterns of the investigated thin films show that crystallite growth occurs in the orthorhombic phase structure. The surface study carried out by using the scanning electron microscope (SEM) confirms that the grain size increases with gamma irradiation. The optical parameters were estimated from optical transmission spectra data measured from a UV-vis-spectrophotometer in the wavelength range of 200-1100 nm. The refractive index dispersion data of the investigated thin films follow the single oscillator model. The estimated values of static refractive index n0, oscillator strength Ed, zero frequency dielectric constant ε0, optical conductivity σoptical and the dissipation factor increases after irradiation, while the single oscillator energy Eo decreases after irradiation. It was found that the value of the optical band gap of the investigated thin films decreases and the corresponding absorption coefficient increases continuously with an increase in the dose of gamma irradiation. This post irradiation changes in the values of optical band gap and absorption coefficient were interpreted in terms of the bond distribution model.

  11. 60Coγ射线损伤后小鼠造血系统生理指标的动态变化%Changes of Physiological Indexes in Hematopoietic System of Mice after 60Coγ Ray Irradiation

    Institute of Scientific and Technical Information of China (English)

    侯新然; 王晓波; 袭荣刚; 李忠亮; 高慧媛; 吴立军; 马晓梅

    2012-01-01

    Objective To explore the physiological variation of the hematopoietic system in mice after C07 ray irradiation. Methods Body weight, peripheral blood cell counts,the immune organ index and pathological changes in femoral bone marrow of mice were measured at different times after whole-body irradiation with C07 ray. The doses were 2,4,6 Gy respectively. Results The changes of peripheral blood of mice were different. The white blood cell counts declined most rapidly and obviously,followed by the platelet count,with a dose-effect relationship. Three days after radiation, the immune organ index of mice decreased significantly compared with the immune organ index in mice unirradiated. Myeloid elements in bone marrow were reduced and bone marrow hematopoiesis was depressed. Body weight of irradiated mice grew slowly, without significant difference with mice unirradiated. Conclusion 60Coγ ray radiation can decrease peripheral blood cells, decrease the immune organ index and inhibit bone marrow cell proliferation in mice.%目的 探索小鼠60Coγ射线损伤后造血系统各项生理指标的变化规律.方法 采用60Coγ射线对小鼠进行一次性全身照射,剂量分别为2、4、6 Gy,在不同时间分别测定小鼠体质量,外周血细胞计数,免疫器官指数及股骨骨髓的病理变化.结果 照射后小鼠的外周血象有变化,其中白细胞下降最迅速且明显,其次是血小板,且具有剂量效应关系.照射后3d免疫器官指数下降明显,与对照组比较具有显著性差异;骨髓造血细胞数目迅速减少,出现造血抑制;照射后小鼠体质量增加缓慢,但与对照组比较无显著性差异.结论 60Coγ射线照射可引起小鼠外周血细胞下降,免疫器官指数下降,并抑制骨髓造血细胞增生.

  12. Study of gamma radiation from {sup 60}Co effects on Apis mellifera venom: biochemical, pharmacological and immunological aspects; Estudo dos efeitos da radiacao gama de {sup 60}Co na peconha de Apis mellifera: aspectos bioquimicos, farmacologicos e imunologicos

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Helena

    2001-07-01

    Africanized honeybees are very common insects in Brazil and frequently cause accidents followed by important immunological reactions and even deaths. Their venoms are composed of a complex mixture of substances of general biological actions. Ionizing radiation is able to modify molecular structures affecting the biological properties of proteins. It decreases toxic and enzymatic activities and so, it appears promising as a venom detoxification tool. The main objective of this work was to study the effects of gamma radiation on bee venom, regarding biochemical, pharmacological and immunological aspects. Africanized Apis mellifera whole venom (2 mg/ml) in 0.15 M NaCl solution was irradiated with 2 kGy in a {sup 60}Co source. Native and irradiated bee venoms were submitted to high performance size exclusion chromatography (Tosohaas G2000SW column), high performance reversed phase chromatography in a C-18 column under water/acetonitrile gradient, SDS-PAGE. For both venoms studies have been carried out in UV absorption spectrum, protein concentration, hemolytic activity, and PLA{sub 2} activity analysis, lethality assay (LD{sub 50}). Biodistribution studies was carried out after labelling native and irradiated bee venom with {sup 99m}Tc. The results showed that gamma radiation did not change the protein concentration nor its immunogenicity, although it could be observed that irradiated bee venom UV spectrum and SDS-PAGE profile presented differences when compared to native bee venom. This suggests that some structural alterations in bee venom components could have occurred after irradiation. HPLC-RP profiles showed that gamma radiation could have caused conformational changes, such as unfolding of molecule chains, changing their hydrophobic groups exposuring. The hemolytic and the PLA{sub 2} activities of irradiated bee venom were smaller than the native ones. The gamma radiation diminished the toxicity of bee venom, but did not abolish its bioactivity, like hemolysis

  13. Cosmic Rays: What Gamma Rays Can Say

    OpenAIRE

    2014-01-01

    We will review the main channels of gamma ray emission due to the acceleration and propagation of cosmic rays, discussing the cases of both galactic and extra-galactic cosmic rays and their connection with gamma rays observations.

  14. SPRF60Coγ圃装置研制%THE ESTABLISHMENT OF SPRF COBALT-60 GAMMA FIELD

    Institute of Scientific and Technical Information of China (English)

    王家银; 张运法; 李品芳

    1984-01-01

    SPRF60Coγ圃装置由二阶围墙、帽形伞塔.半地下水井三者良好组合成为一个半封闭型γ圃.既可降低墙外散射剂量,又能在圃内达到引变剂量.对解决城郊建圃中存在的防护剂量与引变剂量关键技术问题有重要意义.

  15. The effects of 60Co γ-ray on poly(ethylene-co-vinyl acetate)/carbon black composites

    Science.gov (United States)

    Lee, Kyoung-Yong; Kim, Ki-Yup

    2008-04-01

    Cables used in a nuclear power plant are irradiation suppressing ones. Until now, researches on the irradiation suppressing cables have mainly been focused on insulation materials. Therefore, in this paper, the non-isothermal crystallization behaviors and degradation characteristics of ethylene vinyl acetate-carbon black (EVA-CB), used as a shielding material, were investigated by means of the Differential scanning calorimetry (DSC) and chemiluminescence analyzer (CL). The specimens were cooled after removing thermal history at 150 °C for 5 min by changing the cooling rates to 5, 7.5, 10, 15 and 20 °C/min with DSC. In addition, after maintaining a thermal equilibrium at each temperature of 25, 50, 75, 100, 125, 150 and 175 °C, their thermoluminescence was measured for 20 min with CL equipment. The 60Co γ-ray was used for irradiation. Tc, T0, T∞ and t1/2 in the DSC experiments are found to decrease gradually as radiation dose increases. Secondly, with the CL experiment, the 0.1, 0.25 and 0.5 MGy EVA-CB composites were found to show a much smaller thermoluminescence than the intact EVA-CB composites, while the 0.75 and 1 MGy EVA-CB composites were found to show a much higher thermoluminescence than ones.

  16. Replication of simian virus 40 in simian virus 40-transformed hamster kidney cells induced by mitomycin C or /sup 60/Co. gamma. irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Rakusanova, T.; Smales, W.P.; Kaplan, J.C.; Black, P.H.

    1978-07-15

    Several clones of simian virus 40 (SV40)-transformed hamster kidney cells, which are heterogeneous for induction of infectious SV40, have been studied. SV40 yields are low after induction with /sup 60/Co ..gamma.. irradiation or mitomycin C. In order to clarify the mechanism(s) by which virus is produced in induced cells, we analyzed the replication of viral DNA and production of virion (V) antigen and infectious virus after induction in various clones as well as in lytically infected permissive cells. Cells replicating SV40 DNA or synthesizing V antigen were visualized by in situ hybridization and immunofluorescence techniques, respectively. Only some cells in induced cultures were found to produce SV40 and those which did were less efficient than lytically infected monkey cells. Mitomycin C or /sup 60/Co ..gamma.. irradiation acted by inducing more cells to replicate virus rather than by increasing the amount of SV40 released from individual cells. A greater proportion of cells could be induced to replicate SV40 DNA than to synthesize V antigen in all induced clones studied. Also, SV40 DNA replication was induced at lower doses of ..gamma.. irradiation than the production of either V antigen or infectious virus suggesting that synthesis of late virus protein is more restricted in induced cells than is replication of SV40 DNA. These findings indicate that one of the effects of induction treatments on SV40-transformed hamster cells is an enhancement of the cells' capacity to support SV40 replication.

  17. INCASOY-35: PRIMERA VARIEDAD DE SOYA OBTENIDA EN CUBA A PARTIR DEL EMPLEO DE TÉCNICAS DE IRRADIACIÓN DE RAYOS GAMMA DE 60Co

    Directory of Open Access Journals (Sweden)

    R. Ortiz

    2005-01-01

    Full Text Available La variedad INCASoy-35 fue obtenida a partir de la irradiación de semillas de la variedad INCASoy-15 con dosis de 240 Gy de rayos gamma 60Co; esta variedad se adapta a siembras de primavera, verano e invierno y puede alcanzar rendimientos de 3 t.ha-1 de granos. Tolera las principales plagas y enfermedades y, en especial, resiste el ataque de nemátodos Meloidogyne incognita. En la época adversa de primavera, las semillas han mostrado tolerancia al deterioro. Tiene capacidad de garantizar altas producciones con bajos insumos, por lo que resulta factible para la agricultura cubana.

  18. Supplementary comparison CCRI(I)-S2 of standards for absorbed dose to water in 60Co gamma radiation at radiation processing dose levels

    DEFF Research Database (Denmark)

    Burns, D. T.; Allisy-Roberts, P. J.; Desrosiers, M. F.

    2011-01-01

    rate effect is presented and discussed briefly. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication......Eight national standards for absorbed dose to water in 60Co gamma radiation at the dose levels used in radiation processing have been compared over the range from 1 kGy to 30 kGy using the alanine dosimeters of the NIST and the NPL as the transfer dosimeters. The comparison was organized...

  19. Influence of gamma ray irradiation on metakaolin based sodium geopolymer

    Energy Technology Data Exchange (ETDEWEB)

    Lambertin, D., E-mail: david.lambertin@cea.fr [CEA, DEN, DTCD/SPDE/LP2C, F-30207 Bagnols-sur-Cèze (France); Boher, C. [CEA, DEN, DTCD/SPDE/LP2C, F-30207 Bagnols-sur-Cèze (France); Dannoux-Papin, A. [CEA, DEN, DTCD/SPDE/LCFI, F-30207 Bagnols-sur-Cèze (France); Galliez, K.; Rooses, A.; Frizon, F. [CEA, DEN, DTCD/SPDE/LP2C, F-30207 Bagnols-sur-Cèze (France)

    2013-11-15

    Effects of gamma irradiation on metakaolin based Na-geopolymer have been investigated by external irradiation. The experiments were carried out in a gamma irradiator with {sup 60}Co sources up to 1000 kGy. Various Na-geopolymer with three H{sub 2}O/Na{sub 2}O ratios have been studied in terms of hydrogen radiolytic yield. The results show that hydrogen production increases linearly with water content. Gamma irradiation effects on Na-geopolymer microstructure have been investigated with porosity measurements and X-ray pair distribution function analysis. A change of pore size distribution and a structural relaxation have been found after gamma ray irradiation.

  20. Influence of gamma ray irradiation on metakaolin based sodium geopolymer

    Science.gov (United States)

    Lambertin, D.; Boher, C.; Dannoux-Papin, A.; Galliez, K.; Rooses, A.; Frizon, F.

    2013-11-01

    Effects of gamma irradiation on metakaolin based Na-geopolymer have been investigated by external irradiation. The experiments were carried out in a gamma irradiator with 60Co sources up to 1000 kGy. Various Na-geopolymer with three H2O/Na2O ratios have been studied in terms of hydrogen radiolytic yield. The results show that hydrogen production increases linearly with water content. Gamma irradiation effects on Na-geopolymer microstructure have been investigated with porosity measurements and X-ray pair distribution function analysis. A change of pore size distribution and a structural relaxation have been found after gamma ray irradiation.

  1. Effect of gamma radiation of {sup 60}Co in the variability of chinese bean [Vigna unguiculata (l.) Walpers] en R{sub 4}M{sub 4}; Efecto de la radiacion gamma de {sup 60}Co en la variabilidad de frijol chino [Vigna unguiculata (l.) Walpers] en R{sub 4}M{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Salmeron E, J.; Bueno J, J.E.; Valencia E, F. [CSAEGro, Iguala, Guerrero, Tel and Fax 01 733 (33) 24328 (Mexico); Cervantes S, T. [IREGEP (Mexico); Cruz T, E. De la [ININ, Departamento de Biologia, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: csaegro@prodigy.net.mx

    2007-07-01

    Selection of plants of Chinese bean coming from seed irradiated with gammas of {sup 60}Co in the generation R{sub 4}M{sub 4} (fourth recurrent irradiation, fourth segregate generation) were carried out, taking as selection approaches the plant architecture, the numbers of sheaths for plant, sheath longitude, position of the sheaths, grain size and resistance to plagues and illnesses. 17 lines were selected for grain and 3 lines with fodder characteristics of black grain color were also obtained. (Author)

  2. GAMMA-400 gamma-ray observatory

    CERN Document Server

    Topchiev, N P; 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; Menshenin, 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

    2015-01-01

    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 energy range of GAMMA-400 is expected to be from ~20 MeV up to TeV energies for gamma rays, up to 20 TeV for electrons + positrons, and up to 10E15 eV for cosmic-ray nuclei. For high-energy gamma rays with energy from 10 to 100 GeV, the GAMMA-400 angular resolution improves from 0.1{\\deg} to ~0.01{\\deg} and energy resolution from 3% to ~1%; the proton rejection factor is ~5x10E5. GAMMA-400 will be installed onboard the Russian space observatory.

  3. Gamma Ray Astronomy

    Science.gov (United States)

    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.

  4. Gamma ray camera

    Science.gov (United States)

    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.

  5. Gamma ray camera

    Science.gov (United States)

    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.

  6. SVOM gamma ray monitor

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

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

  7. SVOM Gamma Ray Monitor

    CERN Document Server

    Dong, Yongwei; Li, Yanguo; Zhang, Yongjie; Zhang, Shuangnan

    2009-01-01

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

  8. Soil compaction and gamma radiation ({sup 60}Co) in the development of the cowpea beans [Vigna unguiculata, (L) Walp]; Compactacao do solo e radiacao gama ({sup 60}Co) no desenvolvimento do feijao caupi [Vigna unguiculata, (L) Walp

    Energy Technology Data Exchange (ETDEWEB)

    Viana, Eliane Ferreira; Colaco, Waldeciro [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Radioagronomia]. E-mails: aroucha@ufpe.br; wcolaco@ufpe.br

    2005-08-15

    The objective is to investigate the effect of compaction and increased doses of gamma radiation on the development of cowpea [Vigna unguiculata, (L) Walp] var. IPA-206 cultivated in a Neossolo fluvic soil, artificially compacted. Significant differences were observed in plant height, with the increase doses in soil density (1.30 Mg.m{sup -3} - compacted soil and 1.70 Mg.m{sup -3} - non-compacted soil), and in response to increased doses of irradiation (y-rays) [ [0, 100, 200 and 300 Gy). The diameter of the stem was significantly reduced in response to the increase in soil density, however the same did not occur in relation to the doses of irradiation (y-rays) holding capacity of the soil was reduced in response to the increase in soil density. (author)

  9. Supplementary comparison CCRI(I)-S2 of standards for absorbed dose to water in {sup 60}Co gamma radiation at radiation processing dose levels

    Energy Technology Data Exchange (ETDEWEB)

    Burns, D.T.; Allisy-Roberts, P.J. [Bureau International des Poids et Mesures, Pavillon de Breteuil, F-92312 Sevres cedex (France); Desrosiers, M.F. [National Institute of Standards and Technology, Gaithersburg, MD (United States); Sharpe, P.H.G. [National Physical Laboratory, Teddington, Middlesex (United Kingdom); Pimpinella, M. [Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, Rome (Italy); Lourenco, V. [CEA Saclay, LIST, Laboratoire National Henri Becquerel, Gif-sur-Yvette (France); Zhang, Y.L. [National Institute of Metrology, Beijing (China); Miller, A. [Riso High Dose reference Laboratory, Riso DTU, Roskilde (Denmark); Generalova, V. [Institute for Physical-Technical and Radiotechnical Measurements, Moscow (Russian Federation); Sochor, V. [Czech Metrology Institute, Brno (Czech Republic)

    2011-06-15

    Eight national standards for absorbed dose to water in {sup 60}Co gamma radiation at the dose levels used in radiation processing have been compared over the range from 1 kGy to 30 kGy using the alanine dosimeters of the NIST and the NPL as the transfer dosimeters. The comparison was organized by the Bureau International des Poids et Mesures, who also participated at the lowest dose level using their radiotherapy-level standard for the same quantity. The national standards are in general agreement within the standard uncertainties, which are in the range from 1 to 2 parts in 10{sup 2}. Evidence of a dose rate effect is presented and discussed briefly. (authors)

  10. Effects of Nitric Oxide on Growth and Sensitivity of Human Glioma A172 Cells to 60Co and X-ray Radiation

    Institute of Scientific and Technical Information of China (English)

    QiuRong; LiuBing; GuoChuanling; LiWenjian; MaQiufeng; LiSha

    2003-01-01

    Nitric oxide (NO)has been implicated both in regression and progression of tumors due to its production by both tumor cells and infiltrating lymphocytes. Ionizing radiation causes the regression of tumors, and can augment the production of NO by macrophages in vitro. The authors examined the effect of nitric oxide (NO) generating agent sodium nitroprusside (SNP) on the growth and radiosensitivity of cultured glioma A172 cells to 60Co or X-ray radiation.

  11. Measurement of 60CO gamma radiation induced attenuation in multimode step-index POF at 530 nm

    Directory of Open Access Journals (Sweden)

    Kovačević Milan S.

    2013-01-01

    Full Text Available As optical fibres are used ever more extensively in space applications, nuclear industry, medicine and high-energy physics experiments, it has become essential to investigate the influence of ionizing radiation on their characteristics. In this work, the radiation-induced attenuation at 530 nm is investigated experimentally in step-index multimode polymethyl-methacrylate plastic optical fibres exposed to low dose-rate gamma radiation. Cumulative doses ranged from 50 Gy to 500 Gy. The radiation induced attenuation has been empirically found to obey the power law RIA= aDb, where D is the total radiation dose and a and b are the constants determined by fitting.

  12. Gamma rays from Galactic pulsars

    OpenAIRE

    2014-01-01

    Gamma rays from young pulsars and milli-second pulsars are expected to contribute to the diffuse gamma-ray emission measured by the {\\it Fermi} Large Area Telescope (LAT) at high latitudes. We derive the contribution of the pulsars undetected counterpart by using information from radio to gamma rays and we show that they explain only a small fraction of the isotropic diffuse gamma-ray background.

  13. Toxoplasma gondii gamma irradiation using Co-60; Irradiacao do Toxoplasma gondii com gama do {sup 60} Co

    Energy Technology Data Exchange (ETDEWEB)

    Serra-Freire, Nicolau Maues [Universidade Federal Rural do Rio de Janeiro, RJ (Brazil). Dept. de Parasitologia Animal; Maliska, Carmelindo [Hospital Central do Exercito, Rio de Janeiro, RJ (Brazil). Servico de Medicina Nuclear; Norberg, Antonio Neres [Instituto de Biologia do Exercito (IBEx), Rio de Janeiro, RJ (Brazil)

    1996-07-01

    The use of nuclear power through radiation for the destruction of microorganisms which cause food deterioration, infections and toxicosis, is specifically for peaceful purposes. Toxoplasma gondii is a protozoa responsible for illnesses in humans and animals. One of the most common ways of transmission is through raw or poorly cooked meat. There is little information on the resistance of T. gondii to radiation. The objective of this research is to determine the Minimum Lethal Dose (MLD) of gamma radiation for those microorganisms. Suspensions of T. gondii containing approximately one million taquizoites/ml were irradiated with doses between up 0,01 up to 0,15 kGy (Kilogray) and inoculated to mice. The surviving T. gondii were re-irradiated with 0,01 up to 0,16 kGy. The irradiated protozoa were totally destroyed with a 0,15 kGy dose (MLD). Taquizoites issued from live protozoa of 0,14 kGy also were completely destroyed with dose of 0,15 kGy. No increase in resistance was observed regarding the non irradiated protozoa. (author)

  14. Study about the sensibility in vitro of different strains of Vibrio cholera 01 exposed to 60 Co gamma radiation; Estudo da sensibilidade in vitro de diferentes cepas de Vibio cholerae 01 a radiacao gama de 60Co

    Energy Technology Data Exchange (ETDEWEB)

    Moraes, Ivany Rodrigues de [Instituto Adolfo Lutz, Sao Paulo, SP (Brazil). Servicos de Saude; Gelli, Dilma Scala; Jakabi, Miyoko [Instituto Adolfo Lutz, Sao Paulo, SP (Brazil). Secao de Microbiologia; Mastro, Nelida Lucia del [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: nlmastro@net.ipen.br

    1998-07-01

    The presence of some microorganisms in food, or the metabolites originated during their own multiplication may bring several diseases to humans: intoxications and food borne infections. Among the agents that may cause those diseases, we find Vibrio cholerae 01. In this experiment, the studies are focused on the radiosensibility in vitro of four strains of V. cholerae 01, exposed to different doses of ionizing radiation of {sup 60} Co. The results are compared with other data related to bacterial food borne diseases, including water. (author)

  15. Study of recombination processes for 'electron-hole' pairs in germanium irradiated by {gamma} rays from {sup 60}Co using the photovoltaic effect in P-N junctions; Etude du processus de recombinaison des paires ''electron-trou'' dans le germanium irradie par les rayons {gamma} du cobalt 60 a l'aide de l'effet photovoltaique dans les jonctions P-N

    Energy Technology Data Exchange (ETDEWEB)

    Zahedi-Mochadam, A.A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-10-01

    Using the photo-voltaic effect in p-n junctions, we have studied, during bombardment, the mechanism of the recombination of 'electron-hole' pairs in the presence of structure defects produced in germanium of the N and P types by {gamma} rays from a Co{sup 60} source. At 310 K the level of the recombination centres is situated 0.25 eV above the conduction band and the capture cross-sections of the holes and of the electrons have the respective values of: {sigma}{sub p} = 4 X 10{sup -15} cm{sup 2} and {sigma}{sub n} = 3 X 10{sup -15} cm{sup 2}. The value of {sigma}{sub n} appears to be under-estimated because the number of defects in P-type samples appears to be lower than that in N-type samples. These results lead to the conclusion that the interstitials are responsible for the recombination. At 80 K it has been found that in N-type samples, a shallow level exists at O.05 eV below the conduction band with a capture cross-section for the holes of {sigma}{sub p} {>=} 10{sup -14} cm{sup 2}. We believe that in this case the recombination of charge carriers is controlled by the neighbouring 'defect-interstitial' pairs. In P-type samples at low temperature, the life-time is practically constant during irradiation. This fact is attributed to a spontaneous annealing of defects ol purely electrical origin. In the last part of the work the study of the photo-voltaic effect applied to the problem of gamma radiation dosimetry is considered. It is shown that such dosimeters, based on this principle, make it possible to measure the intensity of gamma rays over a very wide range. (author) [French] En utilisant l'effet photovoltaique dans les jonctions p-n, nous avons etudie au cours du bombardement le mecanisme de recombinaison des paires 'electron-trou' en presence des defauts de structure introduits dans le germanium de type N et de type P par les rayons gamma d'une source de Co{sup 60}. A 310 K, le niveau des centres de recombinaison se

  16. {sup 60}Co gamma-irradiation effects on electrical properties of a rectifying diode based on a novel macrocyclic Zn octaamide complex

    Energy Technology Data Exchange (ETDEWEB)

    Ocak, Y.S. [Department of Science, Faculty of Education, University of Dicle, Diyarbakir (Turkey); Kilicoglu, T., E-mail: kilicoglutahsin@gmail.co [Department of Physics, Faculty of Art and Science, University of Batman, Batman (Turkey); Department of Physics, Faculty of Art and Science, University of Dicle, Diyarbakir (Turkey); Topal, G. [Department of Chemistry, Faculty of Education, University of Dicle, Diyarbakir (Turkey); Baskan, M.H. [Department of Physics, Faculty of Education, University of Dicle, Diyarbakir (Turkey)

    2010-01-01

    C{sub 36}H{sub 28}N{sub 12}O{sub 8}ZnCl{sub 2}.9/2H{sub 2}O, Zn-octaamide (ZnOA) macrocyclic compound was synthesized to be used in the fabrication of electronic and photoelectronic devices. The structure of new compound was identified by using {sup 1}H NMR, {sup 13}C NMR, IR, UV-vis and LC-MS spectroscopic methods. The Sn/ZnOA/n-Si/Au structure was engineered by forming a thin macrocyclic organic compound layer on n-Si inorganic substrate and then by evaporating Sn metal on the organic layer. It was seen that the device had a good rectifying behaviour and showed Schottky diode properties. The diode was irradiated under {sup 60}Co gamma-source at room temperature. Characteristic parameters of the diode were determined from its current-voltage (I-V) and capacitance voltage (C-V) measurements before and after irradiation. It was observed that gamma-irradiation had clear effects on I-V and C-V properties. Also, it was seen that the barrier height, the ideality factor and the series resistance values decreased after the applied radiation, while the saturation current value increased.

  17. Effects of 60 CoRay Irradiation on the Seed Germination and Seedling Growth of Bauhinia variegata%60Co-γ辐照对洋紫荆种子发芽及幼苗生长的影响

    Institute of Scientific and Technical Information of China (English)

    徐佳琦; 戚嘉敏; 朱雯; 许逸林; 奚如春

    2016-01-01

    Different doses(0, 20, 40, 60, 80, 100 Gy) of 60Coray irradiation were applied to the dry Bauhinia variegata seeds and the effects on seed germination and seedling growth were investigated to explore the mutagenic effects of radiation. The results showed that with the increase of radiation the seed germination rate decreased first and rise again, decreasing from 51.66%(20 Gy) to 42.66%(60 Gy) and rising to 54.33%(100 Gy) after 6 months. Irradiation can promote the growth of the radical, the radical increased from 2.49 cm in the control group to 3.28 cm. Seed germination rate and seedling survival rate were reduced in the irradiation treatment of 40~60 Gy. The inhibition effect on seedling height and its ground diameter growth were found by radiation after seedling grew for six months. Also, the inhibition effect were found on the angle of leaf. However, no obvious deformity in the seedling morphology was found.%分别采用0,20,40,60,80,100 Gy 剂量的60Co-γ射线辐射洋紫荆(Bauhinia variegata)种子,观察测定其种子发芽率和幼苗生长指标,研究辐照对洋紫荆种子的诱变效应。结果表明,在0~100 Gy 辐射剂量内,随着辐照剂量的增加,洋紫荆种子发芽率出现先下降再上升的趋势,由51.66%(20 Gy)降至42.66%(60 Gy),又升高至54.33%(100 Gy)。一定剂量的辐照能促进胚根的生长,其中20 Gy 的辐射下平均胚根长度为3.28 cm,显著大于对照组(2.49 cm)(P<0.05)。40~60 Gy 辐射剂量使种子发芽率和幼苗成活率降低。各辐照处理对幼苗苗高、地径生长具有明显抑制作用,幼苗生长6个月后,各辐照组苗高、地径均显著小于对照组(P<0.05),同时对叶片分裂角度也具有一定的抑制作用但幼苗未出现致畸形态。

  18. 60Coγ射线辐照不同麻种种子的细胞学效应%Cytological Effects on Seeds of Hibiscus cannabinus and Cannabis sativa Irradiated by 60Coγ ray

    Institute of Scientific and Technical Information of China (English)

    周立人; 吴雪琴; 魏晓飞; 李布青

    2003-01-01

    通过5种不同剂量的60Coγ射线对两个不同麻种3个品种材料的种子辐照效应研究表明,低剂量的60Coγ射线辐照能促进麻类作物根尖细胞的有丝分裂.但随着γ射线辐照剂量的增加,根尖细胞有丝分裂指数呈不同程度的下降趋势.60Coγ射线辐照能诱发根尖细胞的染色体畸变和核畸变,出现桥、断片、落后染色体、微核、双核、小核等多种畸变类型,并且辐照剂量越大,根尖细胞畸变类型越多,变异频率越高.研究结果还表明不同麻种、同一麻种不同品种对60Coγ射线的辐射敏感性不同,红麻中杂红305最强,红麻福红2号次之,大麻最弱.

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

    CERN Document Server

    Marisaldi, M; 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; 10.1103/PhysRevLett.105.128501

    2010-01-01

    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 degrees at 50 MeV. Remarkably, all TGF-associated gamma rays are compatible with a terrestrial production site closer to the sub-satellite 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.

  20. Optimization of process parameters for the inactivation of Lactobacillus sporogenes in tomato paste with ultrasound and {sup 60}Co-{gamma} irradiation using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Ye Shengying [College of Food Science, South China Agricultural University, Wushan, Guangzhou, GD 510640 (China)], E-mail: yesy@scau.edu.cn; Qiu Yuanxin; Song Xianliang; Luo Shucan [College of Food Science, South China Agricultural University, Wushan, Guangzhou, GD 510640 (China)

    2009-03-15

    The processing parameters for ultrasound and {sup 60}Co-{gamma} irradiation were optimized for their ability to inactivate Lactobacillus sporogenes in tomato paste using a systematic experimental design based on response surface methodology. Ultrasonic power, ultrasonic processing time and irradiation dose were explored and a central composite rotation design was adopted as the experimental plan, and a least-squares regression model was obtained. The significant influential factors for the inactivation rate of L. sporogenes were obtained from the quadratic model and the t-test analyses for each process parameter. Confirmation of the experimental results indicated that the proposed model was reasonably accurate and could be used to describe the efficacy of the treatments for inactivating L. sporogenes within the limits of the factors studied. The optimized processing parameters were found to be an ultrasonic power of 120 W with a processing time of 25 min and an irradiation dose of 6.5 kGy. These were measured under the constraints of parameter limitation, based on the Monte Carlo searching method and the quadratic model of the response surface methodology, including the a/b value of the Hunter color scale of tomato paste. Nevertheless, the ultrasound treatment prior to irradiation for the inactivation of L. sporogenes in tomato paste was unsuitable for reducing the irradiation dose.

  1. Effect of {sup 60} Co gamma radiation on trehalose level of Saccharomyces boulardii cells; Efeito da radiacao gama {sup 60} Co nos niveis de trealose de celulas de Saccharomyces boulardii

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Raquel Gouvea dos; Neves, Maria Jose [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil). Nucleo de Radiobiologia; Duarte, Rinaldo; Nicoli, Jacques R. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Microbiologia

    1996-07-01

    The medicine Floratil used for diarrhea treatment is composed by lyophilized yeast cells of Saccharomyces boulardii. The action mechanism of this product is unknown. The efficacy of S. boulardii depends on its viability. The increase in the trehalose level in S. cerevisiae cells submitted to a previous sub-lethal level heat shock results in resistance to a lethal shock. The aim of this work was to study weather the cell trehalose level is involved also in the resistance of gamma irradiation. It was noted that the yeast cells surviving to gamma irradiation had more trehalose level than control cells. Apparently there is a positive correlation between of trehalose level and gamma irradiation resistance of S.boulardii cells. (author)

  2. Melatonin attenuates (60) Co γ-ray-induced hematopoietic, immunological and gastrointestinal injuries in C57BL/6 male mice.

    Science.gov (United States)

    Khan, Shahanshah; Adhikari, Jawahar Singh; Rizvi, Moshahid Alam; Chaudhury, Nabo Kumar

    2017-02-01

    Protection of hematopoietic, immunological, and gastrointestinal injuries from deleterious effects of ionizing radiation is prime rational for developing radioprotector. The objective of this study, therefore, was to evaluate the radioprotective potential of melatonin against damaging effects of radiation-induced hematopoietic, immunological, and gastrointestinal injuries in mice. C57BL/6 male mice were intraperitoneally administered with melatonin (50-150 mg/kg) 30 min prior to whole-body radiation exposure of 5 and 7.5 Gy using (60) Co-teletherapy unit. Thirty-day survival against 7.5 Gy was monitored. Melatonin (100 mg/kg) pretreatment showed 100% survival against 7.5 Gy radiation dose. Melatonin pretreatment expanded femoral HPSCs, and inhibited spleenocyte DNA strands breaks and apoptosis in irradiated mice. At this time, it also protected radiation-induced loss of T cell sub-populations in spleen. In addition, melatonin pretreatment enhanced crypts regeneration and increased villi number and length in irradiated mice. Translocation of gut bacteria to spleen, liver and kidney were controlled in irradiated mice pretreated with melatonin. Radiation-induced gastrointestinal DNA strand breaks, lipid peroxidation, and expression of proapoptotic-p53, Bax, and antiapoptotic-Bcl-xL proteins were reversed in melatonin pretreated mice. This increase of Bcl-xL was associated with the decrease of Bax/Bcl-xL ratio. ABTS and DPPH radical assays revealed that melatonin treatment alleviated total antioxidant capacity in hematopoietic and gastrointestinal tissues. Present study demonstrated that melatonin pretreatment was able to prevent hematopoietic, immunological, and gastrointestinal radiation-induced injury, therefore, overcoming lethality in mice. These results suggest potential of melatonin in developing radioprotector for protection of bone marrow, spleen, and gastrointestine in planned radiation exposure scenarios including radiotherapy. © 2016 Wiley

  3. Differential Expression of Retrotransposon WIS 2-1A Response to Vacuum,Low-Energy N+ Implantation and 60Coγ-ray Irradiation in Wheat

    Institute of Scientific and Technical Information of China (English)

    ZHAO Huiru; GU Yunhong; YA Huiyuan; JIAO Zhen; QIN Guangyong

    2009-01-01

    Mutagenesis and retrotransposons have a close relationship,but little attention has been paid yet to the activity of rtrotransposons produced by physical mutagens. The variation of retrotransposon WIS 2-1A activity in wheat(Triticum aestivum L.)embryos at three different growth times(30 h,45 h and 60 h)was investigated after they had been treated with N+ implantation in a vacuum of 5x10-2 Pa and irradiation by 60Coγ-ray respectively.For each of the three growth times the expression of WIS 2-1A showed almost entirely a same trend of downregulation,upregulation,then downregulation,and upregulation again with the increase in dose of N+ implantation,but the expression appeared irregular with the increase in irradiation of 60Coγ-ray.In conclusion,the acutely activating effect of WIS 2-1A stimulated by vacuum and high dose N+ implantation within a shorter incubation time may provide a convenient tool to advance the research on mutagenic breeding and function genes.

  4. Optimization of foaming properties of sludge protein solution by 60Co γ-ray/H2O2 using response surface methodology

    Science.gov (United States)

    Xiang, Yulin; Xiang, Yuxiu; Wang, Lipeng; Zhang, Zhifang

    2016-10-01

    Response surface methodology and Box-Behnken experimental design were used to model and optimize the operational parameters of foaming properties of the sludge protein solution by 60Co γ-ray/H2O2 treatment. The four variables involved in this research were the protein solution concentration, H2O2, pH and dose. In the range studied, statistical analysis of the results showed that selected variables had a significant effect on protein foaming properties. The optimized conditions contained: protein solution concentration 26.50% (v/v), H2O2 concentration 0.30% (v/v), pH value 9.0, and dose 4.81 kGy. Under optimal conditions, the foamability and foam stability approached 23.3 cm and 21.3 cm, respectively. Regression analysis with R2 value of 0.9923 (foamability) and 0.9922 (foam stability) indicated a satisfactory correlation between the experimental data and predicted values (response). In addition, based on a feasibility analysis, the 60Co γ-ray/H2O2 method can improve odor and color of the protein foaming solution.

  5. 60Co γ-rays irradiation effect in DC performance of AlGaN/GaN high electron mobility transistors

    Institute of Scientific and Technical Information of China (English)

    Gu Wenping; Chen Chi; Duan Huantao; Hao Yue; Zhang Jincheng; Wang Chong; Feng Qian; Ma Xiaohua

    2009-01-01

    Unpassivated/passivated AlGaN/GaN high electron mobility transistors(HEMTs) were exposed to 1.25MeV60Co γ-rays at a dose of 1 Mrad(Si).The saturation drain current of the unpassivated devices decreased by 15%at 1 Mrad γ-dose,and the maximal transconductance decreased by 9.1% under the same condition;moreover,either forward or reverse gate bias current was significantly increased,while the threshold voltage is relatively unaffected.By sharp contrast,the passivated devices showed scarcely any change in saturation drain current and maximal transconductance at the same γ dose.Based on the differences between the passivated HEMTs and unpassivated HEMTs,adding the C-V measurement results,the obviously parameter degradation of the unpassivated AlGaN/GaN HEMTs is believed to be caused by the creation of electronegative surface state charges in source-gate spacer and gate-drain spacer at the low dose (1 Mrad).These results reveal that the passivation is effective in reducing the effects of surface state charges induced by the 60Co γ-rays irradiation.so the passivation is an effective reinforced approach.

  6. Applied gamma-ray spectrometry

    CERN Document Server

    Dams, R; Crouthamel, Carl E

    1970-01-01

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

  7. Fission prompt gamma-ray multiplicity distribution measurements and simulations at DANCE

    Energy Technology Data Exchange (ETDEWEB)

    Chyzh, A; Wu, C Y; Ullmann, J; Jandel, M; Bredeweg, T; Couture, A; Norman, E

    2010-08-24

    The nearly energy independence of the DANCE efficiency and multiplicity response to {gamma} rays makes it possible to measure the prompt {gamma}-ray multiplicity distribution in fission. We demonstrate this unique capability of DANCE through the comparison of {gamma}-ray energy and multiplicity distribution between the measurement and numerical simulation for three radioactive sources {sup 22}Na, {sup 60}Co, and {sup 88}Y. The prospect for measuring the {gamma}-ray multiplicity distribution for both spontaneous and neutron-induced fission is discussed.

  8. Airborne gamma-ray spectrometry

    DEFF Research Database (Denmark)

    Hovgaard, Jens

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

  9. Characterization on the microstructure of gamma-ray irradiated Nd2Fe14B magnet.

    Science.gov (United States)

    Han, Young Chul; Kim, Young Hwan; Cha, Hyun Gil; Kim, Chang Woo; Ji, Eun Sun; Heo, Jin Kook; Kwon, Hae Woong; Kang, Young Soo

    2009-02-01

    The effect of 60Co gamma-ray irradiation on the microstructure of Nd2Fe14B magnets was investigated with electron spin resonance (ESR) and thermal mechanical analyzer (TMA). When the 60Co gamma-ray with dose from 0 Mrad to 100 Mrad was exposed to Nd2Fel,4B magnet having different sizes at room temperature, the increased demagnetization properties of the Nd2Fe14B magnets were studied by Hall probe. For all samples, changed Curie temperature and micro-crystal structure of Nd2Fe14B magnet by gamma-ray irradiation has been also studied. Moreover the strong and broad single line shaped ESR signal in the resonance magnetic field is attributed to unpaired electron of iron ions in the sample by the effect of gamma-ray irradiation.

  10. IMMUNE TOLERANCE INDUCED BY GAMMA-RAY IRRADIATION

    Institute of Scientific and Technical Information of China (English)

    练燕; 王延江; 粟永萍; 冉新泽; 艾国平; 刘晓宏; 郭朝华; 程天民

    2003-01-01

    Objective: To detect the existence of immune tolerance induced by gamma-ray irradiation. Methods: Peritoneal cells were harvested from mice subjected to 5 Gy 60Co gamma-ray total body irradiation at 3d, 7d, 15d and 30d, then their counts, morphological changes and IL-12 gene expression were investigated. Results: After irradiation, the peritoneal cells were sharply reduced, the cell morphology shifted from round-like to polymorphic and fusiform with some processes, expression of IL-12 p35 was seriously suppressed, while that of IL-12 p40 greatly enhanced. Conclusion: Our data highly suggest that the gamma-ray irradiation could potentially induce dendritic cell (DC) commitment and immune tolerance.

  11. X-ray versus gamma irradiation effects on polymers

    Energy Technology Data Exchange (ETDEWEB)

    Croonenborghs, B. [Sterigenics EMEAA, Remylaan 4c box 4, 3018 Leuven (Belgium); Smith, M.A. [Sterigenics International, 10811 Withers Cove Park Drive, Charlotte, NC 28278 (United States); Strain, P. [Sterigenics EMEAA, Remylaan 4c box 4, 3018 Leuven (Belgium)], E-mail: pstrain@eu.sterigenics.com

    2007-11-15

    Today, the most common methods used for medical device sterilisation are by gaseous ethylene oxide and by electron beam or gamma irradiation. With X-ray sterilisation about to enter the market, its material compatibility needs to be assessed at doses typically encountered during a sterilisation process. This paper reports on a study that compares the effects of exposing different types of plastics that are commonly used in medical devices to {sup 60}Co or to 5 MeV X-rays. The dose rate for both irradiation modalities was of the same order of magnitude. Under these conditions, both types of radiation are found to have similar effects on polymer properties.

  12. Thermal stability of formulations of PVC irradiated with {gamma} of {sup 60}; Estabilidad termica de formulaciones de PVC irradiadas con {gamma} de {sup 60} Co

    Energy Technology Data Exchange (ETDEWEB)

    Martinez P, M.E.; Carrasco A, H. [ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico)]. E-mail: memp@nuclear.inin.mx; Castaneda F, A.; Benavides C, R.; Garcia R, S.P. [CIQA, 25100 Saltillo, Coahuila (Mexico)

    2004-07-01

    The industry of cables and wires frequently use cable isolations with base of formulations of PVC, in those that stabilizer has usually been used with the help of heavy metals, as the lead, which is toxic. To solve the problem, from the 2002 one has come studying in combined form in the National Institute of Nuclear Research ININ and the Center of Investigation in Applied Chemistry CIQA, the modifications induced by the radiation in formulations with the help of vinyl poly chloride PVC. In these formulations, prepared with cross linking agent, plastifying industrial grade, stuff and non toxic stabilizers of calcium estearate and zinc industrial grade, it is sought to replace the stabilizer of Pb. For this were irradiated it test tubes of PVC with gamma radiation of cobalt 60 to three different dose in atmospheres of air and argon. Later it was determined their thermal stability at different times of heating and it was measured the Young modulus by means of thermo mechanical analysis. Those results obtained together with other techniques of characterization suggest that the irradiated proposed formulation can substitute the one stabilized with lead. (Author)

  13. Gamma-ray-selected AGN

    Science.gov (United States)

    Giommi, Paolo

    2016-08-01

    The gamma-ray band is the most energetic part of the electromagnetic spectrum. As such it is also where selection effects are most severe, as it can only be reached by the most extreme non-thermal AGN. Blazars, with their emission dominated by non-thermal blue-shifted radiation arising in a relativistic jet pointed in the direction of the observer, naturally satisfy this though requirement. For this reason, albeit these sources are intrisically very rare (orders of magnitude less abundant than radio quiet AGN of the same optical magnitude) they almost completely dominate the extragalactic gamma-ray and very high energy sky. I will discuss the emission of different types of blazars and the selection effects that are at play in the gamma-ray band based on recent results from the current generation of gamma-ray astronomy satellites, ground-based Cherenkov telescopes, and Monte Carlo simulations.

  14. Gamma-ray Pulsar Revolution

    CERN Document Server

    Caraveo, Patrizia A

    2013-01-01

    Isolated Neutron Stars (INSs) were the first sources identified in the field of high-energy gamma-ray astronomy. At first, in the 70s, there were only two identified sources, the Crab and Vela pulsars. However, although few in number, these objects were crucial in establishing the very concept of a gamma-ray source. Moreover, they opened up significant discovery space both in the theoretical and phenomenological fronts. The need to explain the copious gamma-ray emission of these pulsars led to breakthrough developments in understanding the structure and physics of neutron star 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. Today we are living through an extraordinary time of discovery. The current generation of gamma-ray detectors has vastly increased the population of known of gamma-ray-emitting neutron stars. The 100 mark was crossed in 2011 and we are now appr...

  15. Proteomics study of progeny of normal human liver cells irradiated by 60Coγ-rays%60Coγ射线照射后人肝细胞子代克隆的蛋白质组学研究

    Institute of Scientific and Technical Information of China (English)

    左雅慧; 王放; 王小莉; 李建国; 王仲文; 童建

    2009-01-01

    目的 探讨经不同剂量60C0 γ射线照射人正常肝细胞后子代克隆的蛋白质表达图谱变化,并对受照射后肝细胞子代的差异蛋白进行质谱鉴定.方法 人正常肝细胞7702分别经不同剂量60Coγ射线照射后,存活细胞克隆继续传代培养至40代,提取细胞总蛋白,进行双向电泳测定,凝胶银染和考染显色,用[mageMaster 2D Platium 510软件对获得的蛋白图谱加以分析,寻找差异表达的蛋白质.选取差异点,胶内原位酶解后进行MALDI-TOF分析和数据库搜索.结果 与对照组相比,各剂量点双向电泳图谱共发现2倍以上差异蛋白质点42个,上调10个,下调32个.成功鉴定出了17个共同差异表达蛋白,这些差异蛋白包括翻译控制肿瘤蛋白、热休克蛋白、氯离子通道蛋白、真核翻译起始因子等.结论 不同剂量的照射可导致人肝细胞子代克隆蛋白质图谱的改变,筛选出的差异蛋白可为探讨电离辐射诱发的基因组不稳定性及其分子机制提供实验依据和理论基础.%Objective To characterize the differential protein expression in the progeny of human liver ceils surviving from ionizing radiation by the proteomic analysis.Methods Two-dimensional electrophoresis gel coupled with mass spectrometry was used to explore the specific protein expression in the progeny of 7702 human liver cells surviving from ionizing radiation.Alterations in expression level of protein spots between the control and the progeny groups were statistically analyzed by ImageMaster 2D Platinum software and mass spectrometry was used to identify the protein spots with significantly altered expression-level.Results The progeny of irradiated ceils were derived from human liver cell line exposed to 0,2,4,6 Gy of 60Co γ-irradiatian.A total of 42 differentially expressed proteins between the control and the progeny of the irradiated cells groups were screened,of which 17 were identified by matrix assistant laser desorption

  16. Effects of Pre-exposure of Mouse Pituitary with Low-dose 60Co γ-ray on Male Reproductive Endocrine Capacity Induced by Subsequent High-dose Irradiation

    Institute of Scientific and Technical Information of China (English)

    ZhangHong; LiWenjian; JingXiaodong; LiuBing; MinFengling; ZhouQingming; XieYi

    2003-01-01

    To investigate the effects of pre-exposure of mouse pituitary with low-dose 60Co γ-ray on male reproductive endocrine capacity induced by subsequent high-dose irradiation, the pituitary of the B6C3F1 hybrid strain male mice were irradiated with 0.05 Gy of 60Co γ-ray as the pre-exposure dose (D1), and were then irradiated with 2 Gy of 60Co γ-ray as challenging irradiation dose (D2) at 4 h after per-exposure. Pituitary gonadotroping hormones --follicle-stimulating hormone (FSH) and luterinzing hormone (LH), serum testosterone, testis weight and sperm count were measured at 35th day after irradiation.

  17. A Green Platform for Preparation of the Well-Defined Polyacrylonitrile: 60Co γ-ray Irradiation-Initiated RAFT Polymerization at Room Temperature

    Directory of Open Access Journals (Sweden)

    Shuangshuang Zhang

    2017-01-01

    Full Text Available 60Co γ-ray irradiation-initiated reversible addition–fragmentation chain transfer (RAFT polymerization at room temperature with 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN as the chain transfer agent was first applied to acrylonitrile (AN polymerization, providing a “green” platform for preparing polyacrylonitrile (PAN-based carbon fibers using an environment-friendly energy source. Various effects of dose rate, molar ratio of the monomer to the chain transfer agent, monomer concentration and reaction time on the AN polymerization behaviors were performed to improve the controllability of molecular the weight and molecular weight distribution of the obtained PAN. The feature of the controlled polymerization was proven by the first-order kinetics, linear increase of the molecular weight with the monomer conversion and a successful chain-extension experiment. The molecular weight and molecular weight distribution of PAN were characterized by size exclusion chromatography (SEC. 1H NMR and Matrix assisted laser desorption ionization/time of flight mass spectra (MALDI-TOF-MS confirmed the chain-end functionality of PAN, which also was supported by the successful chain-extension experiments of original PANs with acrylonitrile and styrene as the second monomers respectively.

  18. Extragalactic Gamma-Ray Astrophysics

    CERN Document Server

    CERN. Geneva

    2016-01-01

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

  19. Terrestrial gamma-ray flashes

    Energy Technology Data Exchange (ETDEWEB)

    Marisaldi, Martino, E-mail: marisaldi@iasfbo.inaf.it [INAF-IASF Bologna, Via Gobetti 101, I-40129 Bologna (Italy); Fuschino, Fabio; Labanti, Claudio [INAF-IASF Bologna, Via Gobetti 101, I-40129 Bologna (Italy); Tavani, Marco [INAF-IASF Roma, Via Fosso del Cavaliere 100, I-00133 Roma (Italy); Argan, Andrea [INAF, Viale del Parco Mellini 84, 00136 Roma (Italy); Del Monte, Ettore [INAF-IASF Roma, Via Fosso del Cavaliere 100, I-00133 Roma (Italy); Longo, Francesco; Barbiellini, Guido [Dipartimento di Fisica Università di Trieste and INFN Trieste, via A. Valerio 2, I-34127 Trieste (Italy); Giuliani, Andrea [INAF-IASF Milano, Via Bassini 15, I-20133 Milano (Italy); Trois, Alessio [INAF Osservatorio Astronomico di Cagliari, loc. Poggio dei Pini, strada 54, I-09012 Capoterra (Italy); Bulgarelli, Andrea; Gianotti, Fulvio; Trifoglio, Massimo [INAF-IASF Bologna, Via Gobetti 101, I-40129 Bologna (Italy)

    2013-08-21

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

  20. Zeptosecond $\\gamma$-ray pulses

    CERN Document Server

    Klaiber, Michael; Keitel, Christoph H

    2007-01-01

    High-order harmonic generation (HHG) in the relativistic regime is employed to obtain zeptosecond pulses of $\\gamma$-rays. The harmonics are generated from atomic systems in counterpropagating strong attosecond laser pulse trains of linear polarization. In this setup recollisions of the ionized electrons can be achieved in the highly relativistic regime via a reversal of the commonly deteriorating drift and without instability of the electron dynamics such as in a standing laser wave. As a result, coherent attosecond $\\gamma$-rays in the 10 MeV energy range as well as coherent zeptosecond $\\gamma$-ray pulses of MeV photon energy for time-resolved nuclear spectroscopy become feasible.

  1. The Gamma-ray Sky with Fermi

    Science.gov (United States)

    Thompson, David

    2012-01-01

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

  2. Effects of Pre-exposure Mouse Pituitary with Low-dose 60Co γ-ray on Growth Hormone (GH) and Body Mass Induced by Subsequent High-dose Irradiation

    Institute of Scientific and Technical Information of China (English)

    ZhangHong; LiWenjian; JingXiaodong; LiuBing; MinFengling; ZhouQingming; XieYi

    2003-01-01

    The pituitary of the B6C3F1 hybrid strain mice were irradiated with 0.05 Gy of 60Co γ-ray as the pre-exposure dose (D1), and were then irradiated with 2 Gy of 60Co γ-ray as challenging irradiation dose (D2) at 4h after per-exposure. Body weight and serum growth hormone (GH) were measured at 35th day after irradiation. The results showed that irradiation of mouse testes with 2 Gy of 60Co γ-ray significantly diminished mousebody weight and level of serum GH (Table). Pre-exposure with a low-dose (0.05 Gy) of 60Co γ-ray significantly alleviated reductions of mouse body weight and level of serum GH induced by subsequent a high-dose (2 Gy) irradiation (Table). The data suggested that low-dose ionizing irradiation can induce adaptive responses to the harmful effects of pituitary by subsequent high-dose exposure.

  3. Living/controlled free radical copolymerization of chlorotrifluoroethene and butyl vinyl ether under 60Co γ-ray irradiation in the presence of S-benzyl O-ethyl dithiocarbonate.

    Science.gov (United States)

    Liu, Lei; Lu, Dan; Wang, Hu; Dong, Qibao; Wang, Pucheng; Bai, Ruke

    2011-07-21

    Living/controlled free radical copolymerization of chlorotrifluoroethene and butyl vinyl ether has been successfully achieved at room temperature under (60)Co γ-ray irradiation in the presence of S-benzyl O-ethyl dithiocarbonate. The alternating and block copolymers have been obtained with well-defined molecular weights and narrow molecular weight distributions.

  4. Gamma-ray Imaging Methods

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-10-05

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

  5. Gamma-ray burst spectra

    Science.gov (United States)

    Teegarden, B. J.

    1982-01-01

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

  6. Dose-effect of nucleoplasmic bridges frequencies in human peripheral blood lymphocytes induced by 60Co γ-rays%60Co γ射线诱导人外周血淋巴细胞核质桥的剂量-效应关系研究

    Institute of Scientific and Technical Information of China (English)

    赵骅; 陆雪; 陈德清; 刘青杰

    2014-01-01

    Objective To establish the analysis criteria of nucleoplasmic bridges (NPB) and a dose-response curve of NPB frequencies in human peripheral blood lymphocytes irradiated by 60Co γ-rays.Methods Human peripheral blood samples were collected from three healthy males,and were irradiated with 0,1,2,3,4,5 and 6 Gy of 60Co γ-rays.A cytokinesis-block micronucleus assay was carried out to analyze NPBs and micronuclei (MN) in binucleated cells.Results NPBs in binucleated cells at each dose level of γ-ray was conformed to the Poisson distribution.The dose-response curve of the γ-ray-induced NPB frequencies in human peripheral lymphocytes followed the linear-quadratic model y =(1.39 × 10-3)x2 + (4.94 × 10-3)x (R2 =0.981,P < 0.05).Conclusions The dose-response curve of NPB frequencies in human peripheral blood lymphocytes induced by 0-6 Gy 60Co γ-rays was established.%目的 确定核质桥判定标准,建立60Co γ射线诱导正常人外周血淋巴细胞中核质桥(NPB)的剂量-效应曲线.方法 用60Co γ射线照射3名健康男性离体外周血,照射剂量分别为0、1、2、3、4、5和6 Gy,剂量率为l Gy/min,采用胞质分裂阻滞微核(CBMN)法进行细胞培养、收获、制片、染色.在光学显微镜下分析双核细胞中NPB及微核(MN).结果 在0~6 Gy 60Co γ射线照射后,人外周血双核淋巴细胞中的NPB符合泊松分布,且NPB频率随吸收剂量增加而增加(H=19.51,P<0.0l),拟合回归方程为线性平方模式y=(1.39×10-3)x2+(4.94×10-3)x (R2 =0.981,P< 0.01).结论 成功建立0~6 Gy60Co γ射线诱导正常人外周血淋巴细胞中NPB的剂量-效应曲线.

  7. Comunicación corta. RADIOESTIMULACIÓN DE LA GERMINACIÓN EN Stevia rebaudiana CULTIVAR KH-IAN VC-142 (EIRETÉ, MEDIANTE EL EMPLEO DE RAYOS GAMMA 60CO

    Directory of Open Access Journals (Sweden)

    María C. González

    2015-01-01

    Full Text Available El presente trabajo tuvo como objetivo evaluar el efecto de bajas dosis de rayos gamma 60 Co en la germinación de las semillas de Stevia rebaudiana . Para ello se irradiaron semillas del cultivar KH-IAN VC-142 (Eireté, con dosis de 10 a 90 Gray (Gy. Se determinó que todas las dosis empleadas incrementaron el número de semillas germinadas pero la dosis de 10 Gy fue la que provocó la mayor estimulación en la germinación de las semillas.

  8. The Gamma-ray Universe through Fermi

    Science.gov (United States)

    Thompson, David J.

    2012-01-01

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

  9. Novae in gamma-rays

    CERN Document Server

    Hernanz, M

    2013-01-01

    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 (511 keV line and a continuum below this energy, with a cut-off at 20-30 keV). The analysis of gamma-ray spectra and light curves is a potential unique and powerful tool both to trace the corresponding isotopes and to give insights on the properties of the expanding envelope determining its transparency. 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 in some particular novae, in symbiotic binaries, where the companion is a red giant with a wind, instead of a main ...

  10. Short duration gamma ray bursts

    Indian Academy of Sciences (India)

    Patrick Das Gupta

    2004-10-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2001-01-01

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

  12. 大剂量rhG-CSF早期单次给药对60Coγ射线照射小鼠的治疗作用%Therapeutic effects of early administration of a single high dose of rhG-CSF on mice irradiated by 60Coγ rays

    Institute of Scientific and Technical Information of China (English)

    韩阿如娜; 余祖胤; 柳晓兰; 从玉文

    2011-01-01

    Objective To observe the therapeutic effects of early administration with a single high dose of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on mice irradiated with 60Co γ rays, and provide a reference for the treatment of acute radiation syndrome (ARS) by using cytokines. Methods Male C57 mice underwent a total body irradiation of 8. Ogy 60Co y ray, and they were treated with rhG-CSF, at 0.5h and 24h, subcutaneously in a dose of 2, 1 and 0. 5mg/kg, respectively. The 30-day survival rate and mean survival time were observed in the lethal irradiated mice. The peripheral blood cell counts and bone marrow nucleated cell counts were evaluated in the sublethally irradiated mice. Results Early administration of a high dose of rhG-CSF significantly increased 30-day survival rate and prolonged mean survival time of mice with lethal irradiation dose. A single injection of rhG-CSF (lmg/kg) at 0. 5h after irradiation was an optimal administration schedule. In addition, early administration with a single high dose of rhG-CSF improved the recovery of bone marrow nucleated cell counts and peripheral blood counts, including white blood cell (WBC), red blood cell (RBC) and platelet in mice exposed to 6. Ogy irradiation. Conclusion Early administration of a single high dose rhG-CSF may have a favorable therapeutic effect on mice irradiated with 60Co y ray.%目的 观察大剂量rhG-CSF早期单次给药对60Coγ射线照射小鼠的治疗作用,为细胞因子治疗急性放射病提供实验依据.方法 雄性C57小鼠,经8.0Gy 60Co γ射线全身照射后于0.5、24h各皮下注射一次不同剂量rhG-CSF(2、1mg/kg和0.5mg/kg),观察致死剂量照射小鼠的30d存活率及平均生存时间.小鼠经6.0Gy 60Co γ射线全身照射后,通过不同给药方案及不同剂量rhG-CSF早期干预,观察亚致死剂量照射小鼠的外周血象和骨髓有核细胞数的变化.结果 大剂量rhG-CSF早期干预明显提高致死剂量照射小鼠的30d存

  13. The Gamma-ray Sky with Fermi

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, D.J. [NASA Goddard Space Flight Center, Greenbelt, Maryland, 20771 (United States)

    2013-10-15

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

  14. Gamma ({sup 60}CO) radiation effects on arcelin protein and evaluation of bean lineages against Acanthoscelides obtectus (Say) and Zabrotes subfasciatus (Boh.) (Col.: Bruchidae);Efeito da radiacao gama ({sup 60}CO) sobre a proteina arcelina e avaliacao de linhagens de feijoeiro a Acanthoscelides obtectus (Say) and Zabrotes subfasciatus (Boh.) (Col.: Bruchidae)

    Energy Technology Data Exchange (ETDEWEB)

    Botelho, Ana Claudia Girardo

    2006-07-01

    The resistance of arcelin carrying seeds of bean lineages (Phaseolus vulgaris L.) against the bean weevils Acanthoscelides obtectus (Say, 1831) and Zabrotes subfasciatus (Bohemann, 1833) (Coleoptera: Bruchidae), and the influence of gamma radiation ({sup 60}CO) on the manifestation of arcelin resistance to Z. subfasciatus were verified. Laboratorial tests, in choice and non-choice tests, with wild specimens carrying Arc-1, Arc-2, Arc-3, Arc-4, Raz-56 and Raz-59 (with Arc-5 alleles) and commercial lineages as control IAC - Carioca and IAC - Arua were conducted. Statistical design was completely randomized, with five repetitions, with 10 g of grains from each lineage samples by portion. Attractiveness, oviposition, emergence, mortality, adults' weigh and longevity, developing period, sexual rate, seeds' weigh loss, infestation and fecundity (Z. subfasciatus) were observed. Gamma radiation doses irradiations, in general, haven't affected the resistance manifestation of lineages carrying arcelin protein variants against the Z. subfasciatus bean weevil, thus, joint application use of both control methods can be recommended. Raz-56 lineage showed high resistance of the antibiosis types and non-preference for oviposition and feeding to Z. subfasciatus, while Raz-59 showed antibiosis and non-preference for feeding, and both (Raz-56 and Raz-59) showed intermediate resistance to A. obtectus, against which lineage Arc-2 was the most harmful to its development, expressing non-preference to feeding and/or antibiosis. (author)

  15. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the LNE-LNHB, France and the BIPM in 60Co gamma radiation

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Delaunay, F.; Donois, M.

    2013-01-01

    An indirect comparison of the standards for air kerma of the Laboratoire National de Métrologie et d'Essais-Laboratoire National Henri Becquerel (LNE-LNHB), France and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in April 2013. The comparison result, evaluated as a ratio of the LNE-LNHB and the BIPM standards for air kerma, is 0.9994 with a combined standard uncertainty of 1.8 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  16. Comparison of the standards for absorbed dose to water of the NRC and the BIPM for {sup 60}Co gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C.; Allisy-Roberts, P.J.; Burns, D.T. [Bureau International des Poids et Mesures (BIPM), 92 - Sevres (France); McCaffrey, J.P.; McEwen, M.R.; Ross, C.K. [National Research Council of Canada, Ottawa (Canada)

    2010-06-15

    A comparison of the standards for absorbed dose to water of the National Research Council of Canada (NRC) and of the Bureau International des Poids et Mesures (BIPM) was carried out in the {sup 60}Co radiation beam of the BIPM in May 2009 under the auspices of the key comparison BIPM.RI(I)-K4. The comparison result, based on the calibration coefficients for two transfer standards and expressed as a ratio of the NRC and the BIPM standards for absorbed dose to water, is 0.9980(52). This result replaces the 1998 NRC value of 0.9976(51) in this key comparison. The degrees of equivalence between the NRC and the other participants in this comparison have been calculated and the results are given in the form of a matrix for the ten national metrology institutes (NMIs) with published results that have taken part in the ongoing comparison for absorbed dose to water. A graphical presentation is also given. (authors)

  17. Key comparison BIPM.RI(I)-K1 of the air-kerma standards of the SCK.CEN, Belgium and the BIPM in 60Co gamma radiation

    Science.gov (United States)

    Kessler, C.; Burns, D.; Mihailescu, L. C.; Chiriotti, S.

    2017-01-01

    A first key comparison of the standards for air kerma of the Laboratory for Nuclear Calibrations (LNK) from the Studiecentrum voor Kernenergie—Centre d'Etude de l'Energie Nucleaire (SCK.CEN), Belgium and of the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in September 2016. The comparison result, evaluated as a ratio of the SCK.CEN and the BIPM standards for air kerma, is 1.0021 with a combined standard uncertainty of 2.6 × 10-3. The results for an indirect comparison made at the same time are consistent with the direct results at the level of 7 parts in 104. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  18. Gamma rays from dark matter

    CERN Document Server

    Bringmann, Torsten

    2011-01-01

    A leading hypothesis for the nature of the elusive dark matter are thermally produced, weakly interacting massive particles that arise in many theories beyond the standard model of particle physics. Their self-annihilation in astrophysical regions of high density provides a potential means of indirectly detecting dark matter through the annihilation products, which nicely complements direct and collider searches. Here, I review the case of gamma rays which are particularly promising in this respect: distinct and unambiguous spectral signatures would not only allow a clear discrimination from astrophysical backgrounds but also to extract important properties of the dark matter particles; powerful observational facilities like the Fermi Gamma-ray Space Telescope or upcoming large, ground-based Cherenkov telescope arrays will be able to probe a considerable part of the underlying, e.g. supersymmetric, parameter space. I conclude with a more detailed comparison of indirect and direct dark matter searches, showing...

  19. Gamma-ray performance of the GAMMA-400 detector

    CERN Document Server

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

    2015-01-01

    GAMMA-400 is a new space mission, designed as a dual experiment, capable to study both high energy gamma rays (from $\\sim$100 MeV to few TeV) and cosmic rays (electrons up to 20 TeV and nuclei up to $\\sim$10$^{15}$ eV). The full simulation framework of GAMMA-400 is based on the Geant4 toolkit. The details of the gamma-ray reconstruction pipeline in the three main instruments (Tracker, Imaging Calorimeter, Homogeneous Calorimeter) will be outlined. The performance of GAMMA-400 (PSF, effective area and sensitivity) have been obtained using this framework. The most updated results on them will be shown.

  20. High Redshift Gamma Ray Bursts

    Science.gov (United States)

    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.

  1. DUAL Gamma-Ray Mission

    CERN Document Server

    Boggs, S; von Ballmoos, P; Takahashi, T; Gehrels, N; Tueller, J; Baring, M; Beacom, J; Diehl, R; Greiner, J; Grove, E; Hartmann, D; Hernanz, M; Jean, P; Johnson, N; Kanbach, G; Kippen, M; Knödlseder, J; Leising, M; Madejski, G; McConnell, M; Milne, P; Motohide, K; Nakazawa, K; Oberlack, U; Phlips, B; Ryan, J; Skinner, G; Starrfield, S; Tajima, H; Wulf, E; Zoglauer, A; Zych, A

    2010-01-01

    Gamma-ray astronomy presents an extraordinary scientific potential for the study of the most powerful sources and the most violent events in the Universe. In order to take full advantage of this potential, the next generation of instrumentation for this domain will have to achieve an improvement in sensitivity over present technologies of at least an order of magnitude. The DUAL mission concept takes up this challenge in two complementary ways: a very long observation of the entire sky, combined with a large collection area for simultaneous observations of Type Ia SNe. While the Wide-Field Compton Telescope (WCT) accumulates data from the full gamma-ray sky (0.1-10 MeV) over the entire mission lifetime, the Laue-Lens Telescope (LLT) focuses on 56Co emission from SNe Ia (0.8-0.9 MeV), collecting gamma-rays from its large area crystal lens onto the WCT. Two separated spacecraft flying in formation will maintain the DUAL payloads at the lens' focal distance.

  2. Effects of low dose rate 60Co γ ray combined with 252Cf neutron irradiation on hematopoietic and antioxidation systems in rats%低剂量率60Co γ射线和252Cf裂变中子混合照射对大鼠造血及抗氧化系统的影响

    Institute of Scientific and Technical Information of China (English)

    莫琳芳; 何颖; 侯登勇; 钱甜甜; 蒋定文; 王岩; 刘玉明; 李珂娴; 王庆蓉

    2013-01-01

    Objective To study the effects of low dose rate 60Co γ ray combined with 252Cf neutron irradiation on hematopoietic and antioxidation systems in rats.Methods Sixteen SD male rats were randomly divided into the irradiation group and the control group,each consisting of 8 rats.The irradiation group was exposed to whole-body 60 Co γray (with daily dose rate of 0.072 Gy) for 1 hour and to 252 Cf neutron (with daily dose rate of 0.085 mGy/h) for 20 hours,for a total of 7 successive days.Peripheral blood cell counts,main organ indices,bone marrow DNA contents,SOD activity and MDA content of rats were monitored,at day 8 after irradiation.Results Compared with those of the control group [(6.2 ± 2.4) × 109/L],WBC of the irradiation group decreased significantly following irradiation [(3.4 ± 1.2) × 109/L],(P < O.05),but no statistical significance could be noted in the changes of various organ indices (P > O.05).Bone marrow DNA contents and serum SOD activity all decreased significantly (P < 0.05),while organ indices and MDA contents seemed to increase,but without statistical significance (P > 0.05).Conclusions 60 Co γirradiation combined with 252Cf neutron irradiation could obviously damage the hemopoietic and anti-oxidation systems of rats.%目的 探讨低剂量率60Co γ射线与252Cf裂变中子混合照射对大鼠的生物效应.方法 16只雄性SD大鼠按数字表法随机分成实验组和对照组,每组8只.实验组每天依次暴露于60Co γ射线1h(剂量率为0.072 Gy/h),252Cf裂变中子20 h(剂量率为0.085 mGy/h),连续7d.照后第8天检测大鼠外周血细胞计数、主要脏器指数、骨髓DNA含量、血清超氧化物歧化酶(SOD)活力及丙二醛(MDA)含量.结果 与对照组[(6.2 ±2.4)×109/L]相比,实验组大鼠外周血白细胞数[(3.4±1.2)×109/L](WBC)显著降低(P<0.05),各项脏器指数变化组间差异无统计学意义(P>0.05),骨髓DNA含量显著降低(P<0.05);血清SOD活力显著降低(P<0

  3. Effects of gamma irradiation of the {sup 60} Co on antimicrobial action of plant extracts of bark and leaves of Schinus terebinthifolius Raddi; Efeitos da radiacao gama do {sup 60} Co sobre a acao antimicrobiana de extratos vegetais de cascas e folhas de Schinus terebinthifolius Raddi

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Edvane Borges da; Santos, Gustavo Henrique Farias dos; Amaral, Ademir de Jesus [Universidade Federal da Pernambuco (GERAR/DEN/UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Estudos em Radioprotecao e Radioecologia; Lima, Jeniffer Maiza de Souza [Universidade Federal da Pernambuco (CAV/UFPE), Vitoria de Santo Antao, PE (Brazil); Xisto, Kesia; Araujo, Rosilma de Oliveira [Universidade Federal da Pernambuco (DA/UFPE), Recife, PE (Brazil). Dept. de Antibioticos

    2014-07-01

    This study aimed to evaluate the potential for antimicrobial activity in vitro of extracts of bark and leaves of S. terebinthifolius treated with {sup 60}Co gamma radiation. 5,0 doses were used; 7.5 and 10 kGy, being held non-irradiated controls. To determine the antimicrobial activity was applied to the disc diffusion technique to evaluate the diameter of the inhibition zones against Gram-positive bacteria, gram-negative bacteria, alcohol-acid-resistant and yeast. Antimicrobial activity was considered significant for halos ≥ 15 mm. The results indicate an intensification of antimicrobial action of bark extracts, the 5.0 kGy, against S. aureus. Was held the micro dilution in broth to determine the minimum inhibitory concentration (MIC) and Minimum Bactericidal Concentration (MBC) of peels extracts, compared to eight clinical isolates of S. aureus. The MBC values showed that ionizing radiation did not produce the increased of anti bacteriostatic action of S. terebinthifolius, but the results indicated that S. terebinthifolius bark extracts can be used as an antimicrobial agent and ionizing radiation as an important alternative in this conservation feature.

  4. Cytotoxicity evaluation of Diethyltoluamide (DEET) in Perna perna (Linnaeus, 1758) mussels non-irradiated and irradiated with {sup 60}Co gamma radiation; Avaliacao da citotoxicidade do dietiltoluamida (DEET) em mexilhoes Perna perna (Linnaeus, 1758) irradiados e nao irradiados com radiacao gama de {sup 60}Co

    Energy Technology Data Exchange (ETDEWEB)

    Martini, Gisela de Assis

    2013-07-01

    Recent studies have identified the presence of several emerging pollutants in aquatic environments. The occurrence in different environmental matrices has been continuously reported, highlighting the need for toxicity studies. The DEET (N,N-diethyl-meta-toluamide) is the active ingredient used in most insect repellents, and is present in many commercially available formulations. Apart from chemical pollutants, aquatic organisms are subject to exposure of ionizing radiation from natural sources or in the vicinity of nuclear power plants. The present study evaluated the toxicity of DEET in organisms irradiated and non-irradiated with {sup 60}Co gamma radiation, and the effects that radiation causes in lysosomes of hemocytes of Perna perna mussel. For this purpose, assays were performed to identify the acute toxicity of DEET concentration and the dose of gamma radiation able to cause mortality. Subsequently, cytotoxicity assays were carried out to assess the stability of the lysosomal membrane in organisms exposed to ionizing radiation and DEET. According to the results obtained in acute toxicity tests, the concentration of DEET that causes mortality of 50% exposed organisms (LC50) is 114,27 mg L{sup -1}, and the radiation dose that causes mortality (LD50) is 1068 Gy. In the cytotoxicity assays, the concentration of the non-observed effect (NOEC) for irradiated and non-irradiated organisms 0.0001 mg L-1 and observed effect concentration (LOEC) at concentrations above this. The IC25 (72h) for non-irradiated organisms was 0.0003 mg L-1 and IC50 (72h) was 0.0008 mg L{sup -1} for irradiated and non-irradiated organisms. Despite of the concentrations of effect found in this study were higher than in the environment, both measurements are in the same order of magnitude and should be also take into account the possible synergistic effects of DEET with other contaminants in the aquatic environment. (author)

  5. Measurements of high-energy {gamma}-rays with LaBr{sub 3}:Ce detectors

    Energy Technology Data Exchange (ETDEWEB)

    Ciemala, M. [Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Krakow (Poland)], E-mail: Michal.Ciemala@ifj.edu.pl; Balabanski, D. [INRNE, Bulgarian Academy of Sciences, BG-1784 Sofia (Bulgaria); Csatlos, M. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), P.O. Box 51, H-4001 Debrecen (Hungary); Daugas, J.M. [CEA, DAM, DIF, F-91297 Arpajon Cedex (France); Georgiev, G. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), IN2P3-CNRS and Universite Paris-Sud, Bat 104-108, F-91405 Orsay Cedex (France); Gulyas, J. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), P.O. Box 51, H-4001 Debrecen (Hungary); Kmiecik, M. [Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Krakow (Poland); Krasznahorkay, A. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), P.O. Box 51, H-4001 Debrecen (Hungary); Lalkovski, S. [Faculty of Physics, University of Sofia, BG-1164 (Bulgaria); Lefebvre-Schuhl, A. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), IN2P3-CNRS and Universite Paris-Sud, Bat 104-108, F-91405 Orsay Cedex (France); Lozeva, R. [Instituut voor Kernen Stralingsfysica (IKS), Katholieke Universiteit Leuven, B-3001 Leuven (Belgium); Maj, A. [Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Krakow (Poland); Vitez, A. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), P.O. Box 51, H-4001 Debrecen (Hungary)

    2009-09-01

    The full-energy peak efficiency calibration and the energy resolution measurements of the 2in.x2in.LaBr{sub 3}{gamma}-ray detector are presented for {gamma}-ray energies in the 700 keV-17.6 MeV range. Measurements were done using a combination of proton-capture nuclear reactions on {sup 27}Al, {sup 23}Na, {sup 39}K, {sup 7}Li and {sup 11}B for high-energy {gamma}-rays, and radioactive sources such as {sup 60}Co and {sup 152}Eu for the lowest energies. At high energies, two {gamma}-rays in a cascade from proton resonance capture were employed using Al, Na{sub 2}WO{sub 4}, K{sub 2}SO{sub 4} and LiBO{sub 2} targets. The obtained results were compared to the simulations performed using a GEANT4 code.

  6. Gamma-Ray Interactions for Reachback Analysts

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-02

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

  7. Gamma-Ray Astronomy Technology Needs

    Science.gov (United States)

    Gehrels, N.; Cannizzo, J. K.

    2012-01-01

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

  8. Measurements of 60Co in spoons activated by neutrons during the JCO criticality accident at Tokai-mura in 1999.

    Science.gov (United States)

    Gasparro, J; Hult, M; Komura, K; Arnold, D; Holmes, L; Johnston, P N; Laubenstein, M; Neumaier, S; Reyss, J-L; Schillebeeckx, P; Tagziria, H; Van Britsom, G; Vasselli, R

    2004-01-01

    Neutron activated items from the vicinity of the place where the JCO criticality accident occurred have been used to determine the fluence of neutrons around the facility and in nearby residential areas. By using underground laboratories for measuring the activation products, it is possible to extend the study to also cover radionuclides with very low activities from long-lived radionuclides. The present study describes gamma-ray spectrometry measurements undertaken in a range of underground laboratories for the purpose of measuring (60)Co more than 2 years after the criticality event. The measurements show that neutron fluence determined from (60)Co activity is in agreement with previous measurements using the short-lived radionuclides (51)Cr and (59)Fe. Limits on contamination of the samples with (60)Co are evaluated and shown to not greatly affect the utility of neutron fluence determinations using (60)Co activation.

  9. Construction of a {gamma}-{gamma} and {beta}-{gamma} coincidence measurement system for precise determination of nuclear data

    Energy Technology Data Exchange (ETDEWEB)

    Furutaka, Kazuyoshi; Nakamura, Shoji; Harada, Hideo; Katoh, Toshio [Japan Nuclear Cycle Development Institute, Tokai Works, Tokai, Ibaraki (Japan)

    1999-03-01

    A {gamma}-{gamma} and {beta}-{gamma} coincidence measurement system was constructed for the precise determination of nuclear data, such as thermal neutron capture cross sections and {gamma}-ray emission probabilities. The validity of the system was tested by a {gamma}-{gamma} coincidence measurement with a {sup 60}Co standard source. (author)

  10. 刺五加多糖对60Coγ射线照射大鼠外周血细胞的影响%Protective effect of Acanthopanax Senticosus polysaccharide on peripheral hematological cells in rats irradiated with 60 Co γ ray

    Institute of Scientific and Technical Information of China (English)

    莫琳芳; 李珂娴; 钱甜甜; 沈先荣; 何颖; 蒋定文; 刘玉明; 侯登勇; 刘琼; 陈伟; 王庆蓉

    2012-01-01

    Objective To investigate the protective effect of Acanthopanax Senticosus polysaccharide on peripheral hematological cells in rats irradiated with 60Co γ ray.Methods Sixty-three male rats were randomly divided into 7 groups,i.e.the normal control group,the irradiation control group,the WR-2721 group,the 523 group and the 3 experimental groups with high (200 mg · kg-1 · d-1 ), moderate (100 mg · kg-1 · d-1) and low (50 mg· kg-1 · d-1) doses of Acanthopanax Senticosus polysaccharide.The marrow-depressed model rats received 5 Gy 60Co γ ray whole body irradiation with a dose absorption rate of (0.388 Gy/h) except those in the normal control group.WBC,RBC and PLT in the peripheral blood were detected with hemocytometer both on the 5th day before irradiation and the 3rd and 10th days after exposure.Results When detected on the 3rd day following irradiation,WBC in the peripheral blood of the irradiated animals decreased to a level of (2.482 ±0.808) × 109 · ml-1,RBC to a level of (7.680 ±0.926) × 1012·ml-1 and PLT to a point of (360.000±43.967) × 109 · ml-1,having a rather significant decrease in the indices,when compared with those of the normal control group (P < 0.01 ). On the 10th day following irradiation,WBC in the peripheral blood of the irradiated control animals decreased to a level of (4.764 ±0.679) × 109 · ml - 1,RBC decreased to (9.004 ± 0.761 ) × 1012 · ml -1 and PLT to ( 390.000 ± 43.967 ) ×109 · ml-1,with all the indices decreasing more obviously than those of the normal control group(P < 0.01 ).Data detection before irradiation with 60Co γ ray indicated that WBC,RBC and PLT in the peripheral blood of the experimental animals elevated to various extent,when compared with those of the normal control group.Detection after irradiation showed that Acanthopanax Senticosus polysaccharide could obviously increase the levels of WBC,RBC and PLT in the peripheral blood of the irradiated animals,when compared with those of the irradiation

  11. The influence of {sup 60}Co gamma radiation on the action of phenolic compounds Anadenanthera colubrina (Vell.) Brenan in the microbiological control of crude extracts

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Gustavo Henrique F. dos; Silva, Edvane B. da, E-mail: santosghf@hotmail.co [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Estudos em Radioprotecao e Radioecologia (GERAR); Sena, Kesia Xisto da Fonseca R. de; Silva, Bruna L., E-mail: kxfrs@bol.com.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Antibioticos; Lima, Claudia S. de A., E-mail: claudia.salima@gmail.co [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Biofisica e Radiobiologia

    2009-07-01

    Anadenanthera colubrina (Vell.) Brenan, known popularly as angico is a tree founded in northeastern of Brazil, and has great economic and ecological interest. These trees are characterized by high levels of tannins. To evaluate the influence of gamma radiation in plant extracts of barks and leaves of angico, we got extracts of barks and leaves in 70% ethanol, which was filtered and evaporated until dryness. It were classified in four groups (non-irradiated, 5; 7.5 and 10 kGy). The total phenols were quantified by Folin-Ciocalteau method, and the tannins, using the precipitation of casein. The antimicrobial activity of extracts was observed using the paper disk diffusion methods against Gram-positive, Gram-negative, acid-alcohol-resistant bacteria: and yeasts. The halos greater than 10 mm were considered actives. It was also performed the Minimal Inhibitory Concentration (MIC) using Gram positive and alcohol-acid resistant bacteria. The results showed that tannins of A. colubrina, were 52 to 57% of total phenols, and leaves, 58 to 60%. The percentage of total phenols and tannins in the barks and leaves of A. colubrina have not statistically significant change when compared with the irradiated control. These results suggest that A. colubrina has antimicrobial activity against the Gram-positive and alcohol-acid -resistant bacteria, confirmed by MIC. The extracts of leaves it was additionally actives against the Gram-negative and against the yeast C. albicans. These results show that the gamma radiation has not influence about the antimicrobial activity of crude extracts of barks and leaves of A. colubrina. (author)

  12. Gravitational microlensing of gamma-ray blazars

    DEFF Research Database (Denmark)

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

    2003-01-01

    We present a detailed study of the effects of gravitational microlensing on compact and distant $\\gamma$-ray blazars. These objects have $\\gamma$-ray emitting regions which are small enough as to be affected by microlensing effects produced by stars lying in intermediate galaxies. We analyze...... the temporal evolution of the gamma-ray magnification for sources moving in a caustic pattern field, where the combined effects of thousands of stars are taken into account using a numerical technique. We propose that some of the unidentified $\\gamma$-ray sources (particularly some of those lying at high...... galactic latitude whose gamma-ray statistical properties are very similar to detected $\\gamma$-ray blazars) are indeed the result of gravitational lensing magnification of background undetected Active Galactic Nuclei (AGNs)....

  13. Origin of $\\gamma$ Ray Bursters

    CERN Document Server

    Mészáros, P

    1999-01-01

    The successful discovery of X-ray, optical and radio afterglows of GRB hasmade possible the identification of host galaxies at cosmological distances.The energy release inferred in these outbursts place them among the mostenergetic and violent events in the Universe. They are thought to be theoutcome of a cataclysmic stellar collapse or compact stellar merger, leading toa relativistically expanding fireball, in which particles are accelerated atshocks and produce nonthermal radiation. The substantial agreement betweenobservations and the theoretical predictions of the fireball shock modelprovide confirmation of the basic aspects of this scenario. Among recent issuesare the collimation of the outflow and its implications for the energetics, theproduction of prompt bright flashes at wavelenghts much longer than gamma-rays,the time structure of the afterglow, its dependence on the central engine orprogenitor system behavior, and the role of the environment on the afterglow.

  14. 五指毛桃水提液对60Coγ射线致小鼠骨髓细胞DNA损伤的防护作用%Protective Role of Aqueous Extract from Fici Hirtae Radix for DNA Damage of Bone Marrow Cells by 60Coγ-Ray in Mice

    Institute of Scientific and Technical Information of China (English)

    王晓平; 段丽菊; 黄翔; 岑业文; 李桂芬

    2011-01-01

    目的 探讨五指毛桃水提液对60Coγ射线所致的小鼠骨髓细胞DNA损伤的防护作用.方法 40只SPF级♂小鼠随机分为5组:阴性对照组给予生理盐水,辐射模型组单纯接受照射,3个五指毛桃剂量组分别给予相当于生药5,10,20 g.kg-1.d-1五指毛桃水提液,连续灌胃7d.除阴性对照组外,所有小鼠接受全身一次性60Coγ射线照射,照射剂量为6Gy.照射24 h后处死小鼠,取股骨,制作骨髓单细胞悬液,用单细胞凝胶电泳实验检测小鼠骨髓细胞DNA损伤情况.结果 辐射模型组小鼠骨髓细胞DNA的尾部DNA百分率(Tail DNA%)和尾矩(Tail Moment)高于阴性对照组(P<0.01),五指毛桃各剂量组的 Tail DNA%和Tail Moment均显著低于辐射模型组(P<0.01),且随着给药剂量的增加,Tail DNA%和Tail Moment降低.结论 五指毛桃水提液对60Coγ射线损伤小鼠骨髓细胞DNA具有一定的防护作用.%OBJECTIVE To investigate the protective role of aqueous extract from Fici Hirtae Radix for bone marrow cells DNA of 60Coγ-ray irradiated mice. METHODS Forty SPF male mice were randomized into 5 groups. Negative control group was given normal saline, irradiated group was radiation model group and 3 Fici Hirtae Radix dose groups were orally given aqueous extracts from Fici Hirtae Radix of 5, 10, 20 g·kg-1·d-1 for 7 consecutive days. Except the negative control group, all mice received 6 Gy irradiation of whole body. After 24 h of irradiation, mice were sacrificed on femur. Single cell suspension was produced. DNA damage was detected using single cell gel electrophoresis experiment. RESULTS The results showed that Tail DNA% and Tail Moment of radiation model mice were higher than negative control group (P<0.01). Tail DNA% and Tail Moment of all Fici Hirtae Radix dose groups were significantly lower than radiation model group(P<0.01). As the dose increased,Tail DNA% and Tail Moment reduced. CONCLUSION Aqueous extracts from Fici Hirtae Radix have

  15. Magnetars and Gamma Ray Bursts

    CERN Document Server

    Bucciantini, N

    2012-01-01

    In the last few years, evidences for a long-lived and sustained engine in Gamma Ray Bursts (GRBs) have increased the attention to the so called millisecond-magnetar model, as a competitive alternative to the standard collapsar scenario. I will review here the key aspects of the {\\it millisecond magnetar} model for Long Duration Gamma Ray Bursts (LGRBs). I will briefly describe what constraints, present observations put on any engine model, both in term of energetic, outflow properties, and the relation with the associated Supernova (SN). For each of these I will show how the millisecond magnetar model satisfies the requirements, what are the limits of the model, how can it be further tested, and what observations might be used to discriminate against it. I will also discuss numerical results that show the importance of the confinement by the progenitor star in explaining the formation of a collimated outflow, how a detailed model for the evolution of the central engine can be built, and show that a wide varie...

  16. Gamma-ray burst models.

    Science.gov (United States)

    King, Andrew

    2007-05-15

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

  17. Photoelectrocatalytic degradation of ethylene with TiO2 modified by 60Coγ-ray irradiation%利用60Co-γ射线辐照使TiO2改性后对乙烯的催化降解效果

    Institute of Scientific and Technical Information of China (English)

    郑森鸿; 叶盛英; 黄迅; 沈生文

    2013-01-01

    Horticultural products are abundant in China. However, a large amount of them were deteriorated due to the lack of appropriate storage and transport technology, resulting in a huge waste. Ethylene gas is one of the main reasons which cause the deterioration of horticultural products in storage. Nanometer TiO2 photoelectrocatalysis technology is a new technique developed in recently. TiO2, under UV light, can degrade organics such as ethylene, so it provides a potentially effective method for keeping free products. However, in practical applications, the mutual composite happens easily, which shorts the lives of the carriers and limits the application of TiO2. The only solution for this problem is to decrease the compositing rate of photoinduced electrons and the holes by modifying the nanometer-sized TiO2. Developing modified method is also a hot topic of researchers here in China and abroad. 60Coray irradiation reduction technique can modify TiO2 and make it more activity for the catalytic degradation of organics. In order to investigate the effect of TiO2, irradiated by 60Co-γray and loaded with activated carbon fibers (ACF), on photoelectrocatalytic degradation of ethylene in the environment of cold storage, the TiO2/ACF photoelecrorcatalysis materials was deposited with nano-Ag (Ag-TiO2/ACF) and irradiated by 60Co-γray. The effects of 60Co-γray irradiation modified TiO2 (10, 15, 20, 25, 30, 40 kGy) on the photoelectrocatalytic degradation rate of ethylene were investigated in a simulated cold storage environment for horticultural product. X-ray diffractometer and X-ray photoelectron spectroscopy were used to characterize the prepared TiO2. Results from X-ray diffraction showed that: the crystal size has reduced. The percent of anatase decreased from 84.97%in pure TiO2 to 82. 98%in TiO2 treated with a 40 kGy irradiation dose. Result of X-ray photoelectron spectroscopy indicated that the amount of Ti3+, hydroxyl oxygen which have better catalytic activity

  18. 60 Coγ射线辐射致LyGDI断裂对K562细胞的延迟性凋亡作用%Delayed K562 cell apoptosis promoted by cleaved LyGDI after 60Co γ-rays irradiation

    Institute of Scientific and Technical Information of China (English)

    孙华丽; 段卫明; 邵彦彦; 肖海楠; 周新文

    2010-01-01

    目的 采用不同剂量的60 Coγ射线照射人红白血病细胞系K562,探究鸟苷酸解离抑制因子-2(LyGDI)在细胞延迟性死亡中的作用以及其调控机制.方法 细胞流式仪PI单染检测细胞周期,藻红B染色观察细胞的凋亡,Western blot分析LyGDI和Rac1蛋白的表达,免疫荧光检测Rac1蛋白在细胞内的分布.结果 K562细胞被阻滞在G2/M期的百分率为71.3%,K562细胞早期凋亡率较低,8 Gy60Co γ射线照射后24 h,凋亡率为14%,呈现出延迟性的细胞凋亡;K562细胞在4 Gy的γ射线照射24 h后,可见LyGDI发生断裂,总的Rac1蛋白表达未发生明显变化,但其在细胞内的分布发生改变,Rac1转移至细胞膜上与少量核内分布,Rac1脱离LyGDI而激活.结论 LyGDI具有增加细胞延迟性凋亡的作用,其断裂使Rac1转移至细胞膜上,诱导Rac1的激活,从而促进了细胞的凋亡.%Objective To elucidate the function and regulatory mechanism of LyGDI involved delayed cell death in the human K562 cells and HL-60 cells induced by 60Co γ-rays. Methods Erythrosine B cells staining was used to count the apoptosis rate. PI staining and flow cytometry were applied to check the cell cycle. The expression of LYGDI and Rac1 was resolved by Western blot by using monoclonal antibody of LyGDI and Racl. The distribution of Racl protein in cells was observed with immunofluorescence by using the confocal microscope. Results The K562 cells showed G2/M phase arrest and the percent age was 71.3%. The apoptosis rate was very low at early post-irradiation stage in the K562 cells. The apoptosis rate was 14% in the K562 cells at 24 h post-irradiation with 8 Gy of γ-rays, and delayed cell apoptosis was present. LyGDI was cleaved in the K562 cells irradiated by 4 Gy 60 Co γ-rays after 24 hours post-irradiation. The expression of Racl protein was not altered at all, but the distribution was changed in the irradiated cells while the Racl protein moved to cell membrane and a little in cell

  19. Effects of {sup 60}Co gamma radiation on toxicity and hemorrhagic, myonecrotic, and edema-forming activities of Cerastes cerastes venom

    Energy Technology Data Exchange (ETDEWEB)

    Abib, H. [Univ. des Sciences et de la Technologie, Lab. de Biologie Cellulaire et Moleculaire, Faculte des Sciences Biologiques, Houari Boumedienne, Bab Ezzouar (Algeria); Laraba-Djebari, F. [Inst. Pasteur d' Algerie, Lab. de Recherche et de Developpement sur les Venins, Alger (Algeria)]. E-mail: flaraba@ibnsina.ands.dz

    2003-12-01

    Antisera are used as effective antidotes against the local effects of snake bites. To improve antisera production and extend the life of surrogates used to produce antibodies, the chronic effects of venom toxicity must be reduced. The present study evaluated the effectiveness of gamma irradiation to reduce the local effects associated with viperid snake bites by evaluating in NMRI mice the toxicity and edematic, hemorrhagic, and myonecrotic activities of native and irradiated Cerastes cerastes venoms. These results indicated that the toxicity of irradiated venoms (1 and 2 kGy) decreased as compared with that of native venom. The edematic and hemorrhagic activities were also reduced in the detoxified samples, particularly with the 2-kGy radiation dose. Furthermore, the creatine phosphokinase (CPK) activity was significantly increased in the serum and decreased in the myocardium after envenomation with native venom, but no significant enzymatic changes were observed in mice envenomated with irradiated venom. Histopathologic evaluation showed that native venom caused severe degenerative changes in the myocardium. In the case of 2-kGy-irradiated venom, no tissue alterations were observed. These results indicate that irradiation of venom with a 2-kGy dose may offer an effective method for reducing the chronic toxic effects of venom in immunized animals. (author)

  20. Response of the Sertoli cell and stem germ cell to /sup 60/Co. gamma. -radiation (dose and dose rate) in testes of immature rats

    Energy Technology Data Exchange (ETDEWEB)

    Erickson, B.H.; Blend, M.J.

    1976-06-01

    Gamma-radiation effects (dose and dose rate) on the Sertoli cells and stem cells of the germinal line in immature rat testes were examined. Prior to Day 4 of postnatal development, the gonocyte or primitive germ cell was the most radiosensitive cell in the testis. From Day 4 to approximately Day 15 the Sertoli cell was the most critical element, and thereafter the stem cell was of first importance. A dose of 100 rads irreversibly reduced the number of Sertoli cells to 63 percent of control. Of the ages tested beyond Day 2, the 9-day testis was most severely affected. It was estimated that a dose of 400 rads would reduce sperm output of the 9-day testis to 21 percent of control. After Day 4 and prior to Day 20, 300 rads produced a permanent decrement in the stem-cell population. Six hundred rads are required to produce this effect in the adult. Dose rate was an important mediator of the radioresponse of both Sertoli and germ cells.

  1. Effect of {sup 60}Co gamma radiation on the levels of phenolic compounds from crude extracts of bark of Spondias luta L

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Gustavo H.F.; Silva, Hianna A.M.F.; Melo, Mychely S., E-mail: santosghf@hotmail.com, E-mail: hiannaamfs@gmail.com, E-mail: mychely.melo@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Silva, Edvane B., E-mail: edvborges@yahoo.com [Universidade Federal de Pernambuco (UFPE), Vitoria de Santo Antao, PE (Brazil). Centro Academinco de Vitoria

    2013-07-01

    Spondias luta L. (Anacardiaceae), popularly known as cajazeira, is a plant widespread in several regions of Brazil, famous for containing phenolic compounds, which are responsible for your characteristic astringent. Ionizing radiations have the ability to cross the material, ionizing atoms and molecules, causing changes in atoms and molecules important. It is known ionizing radiation promotes quantitative and qualitative changes in plant materials, increasing, decreasing or inactivating secondary substances. The objective of this work was to evaluate the effect of gamma radiation as a modifier of the activity of the phenolic compounds of the bark extract of S. luta L. Methods: For the dosage of phenol extracts (control, irradiated with 5 kGy, 10 kGy, 15 kGy and 20 kGy) were diluted in methanol to a final concentration of 200 mg / L. In test tubes were added 50 μL of extract plus 1 ml of distilled water and 500 μl of Folin (diluted 1:10). After 10 minutes in a dark chamber was added 2.5 ml of calcium carbonate to 20% and the content of the tube was homogenized. After 20 minutes was performed with a spectrophotometer at 735 nm. The assay was performed in triplicate and calculated from a standard curve solution of gallic acid and expressed in μEAG (GAE/mg extract). Results: The control extracts, irradiated to 5 kGy, 10 kGy, 15 kGy and 20 kGy, had, respectively, 6.25, 6.70, 6.25, 6.85, 6.45 μEAG/mg of extract. Conclusion: The results showed no significant change in the amount of phenolic compounds, showing that these compounds are radioresistant extract these doses. (author)

  2. Instrumentation for gamma-ray astronomy

    Science.gov (United States)

    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.

  3. Modeling gamma-ray bursts

    Science.gov (United States)

    Maxham, Amanda

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

  4. Radiobiological studies using gamma and x rays.

    Energy Technology Data Exchange (ETDEWEB)

    Potter, Charles Augustus; Longley, Susan W.; Scott, Bobby R.; Lin, Yong; Wilder, Julie; Hutt, Julie A.; Padilla, Mabel T.; Gott, Katherine M.

    2013-02-01

    There are approximately 500 self-shielded research irradiators used in various facilities throughout the U.S. These facilities use radioactive sources containing either 137Cs or 60Co for a variety of biological investigations. A report from the National Academy of Sciences[1] described the issues with security of particular radiation sources and the desire for their replacement. The participants in this effort prepared two peer-reviewed publications to document the results of radiobiological studies performed using photons from 320-kV x rays and 137Cs on cell cultures and mice. The effectiveness of X rays was shown to vary with cell type.

  5. A comparison of the 60Co gamma radiation hardness, breakdown characteristics and the effect of SiNx capping on InAlN and AlGaN HEMTs for space applications

    Science.gov (United States)

    Smith, M. D.; O'Mahony, D.; Vitobello, F.; Muschitiello, M.; Costantino, A.; Barnes, A. R.; Parbrook, P. J.

    2016-02-01

    Electrical performance and stability of InAlN and AlGaN high electron mobility transistors (HEMTs) subjected 9.1 mrad of 60Co gamma radiation and off-state voltage step-stressing until breakdown are reported. Comparison with commercially available production-level AlGaN HEMT devices, which showed negligible drift in DC performance throughout all experiments, suggests degradation mechanisms must be managed and suppressed through development of advanced epitaxial and surface passivation techniques in order to fully exploit the robustness of the III-nitride material system. Of the research level devices without dielectric layer surface capping, InAlN HEMTs exhibited the greater stability compared with AlGaN under off-state bias stressing and gamma irradiation in terms of their DC characteristics, although AlGaN HEMTs had significantly higher breakdown voltages. The effect of plasma-enhanced chemical vapour deposition SiNx surface capping is explored, highlighting the sensitivity of InAlN HEMT performance to surface passivation techniques. InAlN-SiNx HEMTs suffered more from trap related degradation than AlGaN-SiNx devices in terms of radiation hardness and step-stress characteristics, attributed to an increased capturing of carriers in traps at the InAlN/SiNx interface.

  6. X-ray and gamma ray astronomy detectors

    Science.gov (United States)

    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.

  7. Thermoluminescence of Simulated Interstellar Matter after Gamma-ray Irradiation

    CERN Document Server

    Koike, K; Koike, C; Okada, M; Chihara, H

    2002-01-01

    Interstellar matter is known to be strongly irradiated by radiation and several types of cosmic ray particles. Simulated interstellar matter, such as forsterite $\\rm Mg_{2}SiO_{4}$, enstatite $\\rm MgSiO_{3}$ and magnesite $\\rm MgCO_{3}$ has been irradiated with the $\\rm ^{60}Co$ gamma-rays in liquid nitrogen, and also irradiated with fast neutrons at 10 K and 70 K by making use of the low-temperature irradiation facility of Kyoto University Reactor (KUR-LTL. Maximum fast neutron dose is $10^{17}n_f{\\rm /cm^{2}}$). After irradiation, samples are stored in liquid nitrogen for several months to allow the decay of induced radioactivity. We measured the luminescence spectra of the gamma ray irradiated samples during warming to 370K using a spectrophotometer. For the forsterite and magnesite, the spectra exhibit a rather intense peak at about 645 -- 655 nm and 660 nm respectively, whereas luminescence scarcely appeared in olivine sample. The spectra of forsterite is very similar to the ERE of the Red Rectangle.

  8. Prompt gamma-ray activation analysis (PGAA)

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-11-01

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

  9. Gamma ray spectroscopy with PPM resolving power

    CERN Document Server

    Börner, H; Mutti, P

    2002-01-01

    Applications of gamma-ray spectroscopy with ppm resolving power are presented. The extraordinary resolution allows via the Gamma Ray Induced Doppler broadening (GRID) technique to determine lifetimes of excited nuclear levels. This has contributed to important nuclear structure information. We report on the current status of the technique

  10. Handbook on Mobile Gamma-ray Spectrometry

    DEFF Research Database (Denmark)

    Aage, Helle Karina; Korsbech, Uffe C C

    2003-01-01

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

  11. Gamma-ray pulsars: a gold mine

    CERN Document Server

    Grenier, Isabelle A

    2015-01-01

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

  12. Gamma-ray Burst Cosmology

    CERN Document Server

    Wang, F Y; Liang, E W

    2015-01-01

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

  13. KEY COMPARISON: Comparison of the standards for absorbed dose to water of the BNM-LNHB and the BIPM for 60Co γ rays

    Science.gov (United States)

    Allisy-Roberts, P. J.; Burns, D. T.; Kessler, C.; Delaunay, F.; Leroy, E.

    2005-01-01

    A comparison of the standards for absorbed dose to water of the Bureau National de Métrologie - Laboratoire National Henri Becquerel (BNM-LNHB), Saclay, France and of the Bureau International des Poids et Mesures (BIPM) has been made in 60Co radiation under the auspices of the key comparison BIPM.RI(I)-K4. The comparison result expressed as a ratio of the BNM-LNHB and the BIPM standards for absorbed dose to water is 0.9970 (0.0053). The degrees of equivalence between the BNM-LNHB and the other participants in this comparison have been calculated and the results are given in the form of a matrix for the 12 national metrology institutes (NMIs) that have taken part in the ongoing comparison for absorbed dose to water. A graphical presentation is also given. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by Section I of the Consultative Committee for Ionizing Radiation (CCRI(I)), according to the provisions of the Mutual Recognition Arrangement (MRA).

  14. Supernova remnants and gamma-ray sources

    CERN Document Server

    Torres, D F; Dame, T M; Combi, J A; Butt, Y M; Torres, Diego F.; Romero, Gustavo E.; Dame, Thomas M.; Combi, Jorge A.; Butt, Yousaf M.

    2003-01-01

    A review of the possible relationship between $\\gamma$-ray sources and supernova remnants (SNRs) is presented. Particular emphasis is given to the analysis of the observational status of the problem of cosmic ray acceleration at SNR shock fronts. All positional coincidences between SNRs and unidentified $\\gamma$-ray sources listed in the Third EGRET Catalog at low Galactic latitudes are discussed on a case by case basis. For several coincidences of particular interest, new CO(J=1-0) and radio continuum maps are shown, and the mass content of the SNR surroundings is determined. The contribution to the $\\gamma$-ray flux observed that might come from cosmic ray particles (particularly nuclei) locally accelerated at the SNR shock fronts is evaluated. We discuss the prospects for future research in this field and remark on the possibilities for observations with forthcoming $\\gamma$-ray instruments.

  15. Sensitivity of P-Channel MOSFET to X- and Gamma-Ray Irradiation

    Directory of Open Access Journals (Sweden)

    Milić Pejović

    2013-01-01

    Full Text Available Investigation of Al-gate p-channel MOSFETs sensitivity following irradiation using 200 and 280 kV X-ray beams as well as gamma-ray irradiation of 60Co in the dose range from 1 to 5 Gy was performed in this paper. The response followed on the basis of threshold voltage shift and was studied as a function of absorbed dose. It was shown that the most significant change in threshold voltage was in the case of MOSFET irradiation in X-ray fields of 200 kV and when the gate voltage was +5 V. For practical applications in dosimetry, the sensitivity of the investigated MOSFETs was also satisfactory for X-ray tube voltage of 280 kV and for gamma rays. Possible processes in gate oxide caused by radiation and its impact on the response of MOSFETs were also analyzed in this paper.

  16. Effect of Gamma Rays on Fast Neutron Registration in CR-39

    CERN Document Server

    Kobzev, A P; El-Halem, A A; Abdul-Ghaphar, U S; Salama, T A

    2002-01-01

    A set of CR-39 plastic detectors with front PE radiator was exposed to Am-Be neutron source, which has an emission rate of 0.86\\cdot 10^{7} sec^{-1}, and the neutron dose equivalent rate 1 m apart from the source is equal to 11 mrem/hr. Another set of samples was irradiated by a neutron dose of 4 rem, then exposed to different gamma-ray doses using ^{60}Co source. It was found that the track density grows with the increase of neutron dose and etching time. It was also found that the bulk etching rate V_{B}, the track diameter and the sensitivity of the CR-39 plastic detector with respect to the neutron irradiation increased with increasing gamma-ray dose in the range 1?10 Mrad. These results show that CR-39 can be considered as a promising fast neutron dosimeter and gamma-ray dosimeter.

  17. Efeito da irradiação (60Co na frequência fúngica de amendoim in natura em função do tempo de prateleira Gamma-irradiation effect (60Co in fungi frequency of peanut in natura and after storage

    Directory of Open Access Journals (Sweden)

    Guilherme Prado

    2006-10-01

    Full Text Available Foi verificado o efeito da irradiação gama (60Co na capacidade de destruir a microbiota fúngica, em amendoim em grão, cultivar Tatu Vermelho, da safra 2003 (segundo semestre. Os grãos de amendoim, após a irradiação, foram mantidos à temperatura ambiente em embalagem plástica comercial, durante 180 dias. Para a determinação da porcentagem fúngica foi utilizada a técnica do plaqueamento direto utilizando o meio Ágar Dicloran Rosa de Bengala Cloranfenicol (DRBC, desinfetando ou não os grãos com solução de hipoclorito de sódio. Em grãos de amendoim irradiados e desinfetados externamente, observou-se redução da infecção fúngica a 5 kGy e destruição total de fungos a 10 kGy, após 180 dias de armazenamento à temperatura ambiente. Em grãos irradiados e não desinfetados externamente foram verificados, em função do tempo de armazenamento, aumento da população de fungos com a dose de 1 kGy, redução com a dose de 5 kGy e eliminação total com a aplicação de 10 kGy. A irradiação gama, na dose de 10 kGy ou superior, demonstrou ser um processo eficaz na redução da microbiota fúngica de amendoim em grão, cultivar Tatu Vermelho.Gamma-irradiation effect was verified on the capability of destroying the mycoflora of peanuts grain, Tatu Vermelho cultivar, 2003 crop (second semester. The peanuts grains, after irradiation, were kept at room temperature in plastic bags during 180 days. To determine the percentage of fungi, the direct plating technique was used and the grains were plated out on mycological media dicholoran rose bengal chloranphenicol (DRBC, being desinfected or not with sodium hypochlorite solution. Irradiated and desinfected peanuts was observed a reduction of fungi infection at 5 kGy and total fungi destruction at 10 kGy, after 180 days in storage at room temperature. Irradiated and non desinfected grains showed a increase of fungi population with 1 kGy dose, reduction with 5 kGy dose and total

  18. Protection of negative gravitaxis in Euglena gracilis Z against gamma-ray irradiation by Trolox C

    Energy Technology Data Exchange (ETDEWEB)

    Sakashita, Tetsuya; Doi, Masahiro; Yasuda, Hiroshi; Fuma, Shoichi [National Inst. of Radiological Sciences, Chiba (Japan). Research Center for Radiation Safety; Hader, D.P. [Biologie der Friedrich-Alexander Univ., Erlangen (Germany). Inst. fuer Botanik und Pharmazeutische Biologie

    2002-12-01

    The protective effects of Trolox on the inhibition of negative gravitaxis in Euglena gracilis exposed to 200 Gy {sup 60}Co gamma-rays were examined using different concentrations (1, 10 and 100 {mu}M). The orientation precision of the negative gravitaxis was quantified using the r-value. A significant decrease in the r-value was observed in gamma-irradiated samples (0.18+/-0.03) compared to those of non-irradiated samples (0.47+/-0.03). There were no significant changes in the r-value of cells exposed to 200 Gy gamma-rays by the addition of 1 or 10 {mu}M of Trolox. A significant increase (0.19) in the r-value of cells exposed to 200 Gy with 100 {mu}M Trolox was observed. The results indicates that Trolox at a concentration of 100 {mu}M protects negative gravitaxis against {sup 60}Co gamma-ray irradiation at a dose of 200 Gy. It also suggests that the negative gravitaxis of Euglena gracilis is affected by free radicals.(author)

  19. Gamma-Ray Burst Early Afterglows

    CERN Document Server

    Zhang, B

    2005-01-01

    The successful launch and operation of NASA's Swift Gamma-Ray Burst Explorer open a new era for the multi-wavelength study of the very early afterglow phase of gamma-ray bursts (GRBs). GRB early afterglow information is essential to explore the unknown physical composition of GRB jets, the link between the prompt gamma-ray emission and the afterglow emission, the GRB central engine activity, as well as the immediate GRB environment. Here I review some of the recent theoretical efforts to address these problems and describe how the latest Swift data give answers to these outstanding questions.

  20. Atmospheric Cherenkov Gamma-ray Telescopes

    CERN Document Server

    Holder, Jamie

    2015-01-01

    The stereoscopic imaging atmospheric Cherenkov technique, developed in the 1980s and 1990s, is now used by a number of existing and planned gamma-ray observatories around the world. It provides the most sensitive view of the very high energy gamma-ray sky (above 30 GeV), coupled with relatively good angular and spectral resolution over a wide field-of-view. This Chapter summarizes the details of the technique, including descriptions of the telescope optical systems and cameras, as well as the most common approaches to data analysis and gamma-ray reconstruction.

  1. Gamma-ray burst progenitors

    CERN Document Server

    Levan, Andrew; de Grijs, Richard; Langer, Norbert; Xu, Dong; Yoon, Sung-Chul

    2016-01-01

    We review our current understanding of the progenitors of both long and short duration gamma-ray bursts (GRBs). Constraints can be derived from multiple directions, and we use three distinct strands; i) direct observations of GRBs and their host galaxies, ii) parameters derived from modeling, both via population synthesis and direct numerical simulation and iii) our understanding of plausible analog progenitor systems observed in the local Universe. From these joint constraints, we describe the likely routes that can drive massive stars to the creation of long GRBs, and our best estimates of the scenarios that can create compact object binaries which will ultimately form short GRBs, as well as the associated rates of both long and short GRBs. We further discuss how different the progenitors may be in the case of black hole engine or millisecond-magnetar models for the production of GRBs, and how central engines may provide a unifying theme between many classes of extremely luminous transient, from luminous an...

  2. Gamma-Ray Burst Progenitors

    Science.gov (United States)

    Levan, Andrew; Crowther, Paul; de Grijs, Richard; Langer, Norbert; Xu, Dong; Yoon, Sung-Chul

    2016-12-01

    We review our current understanding of the progenitors of both long and short duration gamma-ray bursts (GRBs). Constraints can be derived from multiple directions, and we use three distinct strands; (i) direct observations of GRBs and their host galaxies, (ii) parameters derived from modelling, both via population synthesis and direct numerical simulation and (iii) our understanding of plausible analog progenitor systems observed in the local Universe. From these joint constraints, we describe the likely routes that can drive massive stars to the creation of long GRBs, and our best estimates of the scenarios that can create compact object binaries which will ultimately form short GRBs, as well as the associated rates of both long and short GRBs. We further discuss how different the progenitors may be in the case of black hole engine or millisecond-magnetar models for the production of GRBs, and how central engines may provide a unifying theme between many classes of extremely luminous transient, from luminous and super-luminous supernovae to long and short GRBs.

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

    CERN Document Server

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

    2013-01-01

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

  4. Biological dose estimation for accidental supra-high dose gamma-ray exposure

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y., E-mail: yingchen29@yahoo.com.cn [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 27 Taiping Road, Haidian District, Beijing 100850 (China); Yan, X.K. [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 27 Taiping Road, Haidian District, Beijing 100850 (China); Department of Radiation Safety, Beijing Institute of Nuclear and Chemical Safety, 14 Guan-cun, Dongcheng District, Beijing 100077 (China); Du, J.; Wang, Z.D.; Zhang, X.Q.; Zeng, F.G.; Zhou, P.K. [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 27 Taiping Road, Haidian District, Beijing 100850 (China)

    2011-09-15

    To correctly estimate the biological dose of victims accidentally exposed to a very high dose of {sup 60}Co gamma-ray, a new dose-effect curve of chromosomal dicentrics/multicentrics and rings in the supra-high dose range was established. Peripheral blood from two healthy men was irradiated in vitro with doses of {sup 60}Co gamma-rays ranging from 6 to 22 Gy at a dose rate of 2.0 Gy/min. Lymphocytes were concentrated, cultured and harvested at 52 h, 68 h and 72 h. The numbers of dic + r were counted. The dose-effect curves were established and validated using comparisons with doses from the Tokai-mura accident and were then applied to two victims of supra-high dose exposure accident. The results indicated that there were no significant differences in chromosome aberration frequency among the different culture times from 52 h to 72 h. The 6-22 Gy dose-effect curve was fitted to a linear quadratic model Y = -2.269 + 0.776D - 7.868 x l0{sup -3}D{sup 2}. Using this mathematic model, the dose estimates were similar to data from Tokai-mura which were estimated by PCC ring. Whole body average doses of 9.7 Gy and 18.1 Gy for two victims in the Jining accident were satisfactorily given. We established and successfully applied a new dose-effect curve of chromosomal dicentrics plus ring (dic + r) after 6-22 Gy {gamma}-irradiation from a supra-high dose {sup 60}Co gamma-ray accident.

  5. Preliminary research on the establishment of non-invasive model of radiation-induced oral mucositis in rats by 60 Coγ-rays irradiation%60 Coγ射线照射大鼠建立放射性口腔黏膜炎模型的初步研究

    Institute of Scientific and Technical Information of China (English)

    刘礼; 陶人川; 雍翔智; 蒋兰岚; 曾启新

    2016-01-01

    目的:建立大鼠放射性口腔黏膜炎模型,观察并分析黏膜组织炎症变化过程。方法:选择SD大鼠45只,随机分为9组:空白对照组;实验组8组均用60 Coγ射线以35 Gy剂量单次照射口鼻部。观察大鼠口腔黏膜状况,对炎症期间拒食的大鼠进行灌注流食喂养。分别于放射后1、3、5、7、10、14、21及28 d处死1组实验组大鼠,对照组于28 d处死,取口腔黏膜组织进行HE染色和光镜下观察。结果:放射后5~6 d,大鼠口腔黏膜出现红肿伴有小面积溃疡;7~8 d小溃疡逐渐融合成大面积溃疡,并持续到9~13 d;14 d开始,溃疡逐渐缩小并愈合;21~28 d溃疡完全愈合。 HE染色显示放射后第5 d,黏膜下层出现大量炎性细胞浸润,但上皮层连续完整;第7、10 d,上皮层崩解、脱落;第14 d溃疡底部可见新生肉芽组织及新生毛细血管;第21、28 d,溃疡处有新的上皮组织出现,基底层排列紧密。结论:经60 Coγ射线照射成功建立放射性口腔黏膜炎大鼠模型,炎症从5~8 d开始,第9~13 d达到高峰,14 d左右开始缓解恢复,21~28 d恢复正常。%Objective:To establish a non-invasive model of radiation-induced oral mucositis( RTOM) in rats and ob-serve the dynamic process of the occurrence,development and healing of mucosal inflammation. Methods:After randomly di-viding 45 SD rats into 9 groups,one group was maintained as a blank control group,while each rat of the other 8 groups re-ceived an irradiation of single 35 Gy dose of 60 Coγ-rays. The condition of the oral mucosal was observed everyday. Each group of experimental rats was sacrificed at the 1 st , 3 rd , 5 th , 7 th , 10 th , 14 th , 21 st and 28 th day after the irradiation respectively. However,the control group of rats were sacrificed only on the 28th day. Oral mucosa tissues of the dead rats were harvested. The samples underwent HE staining for histological

  6. Gamma-Ray Astrophysics NSSTC Fermi GBM

    Data.gov (United States)

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

  7. Investigation of the initial and volume recombination losses in gamma versatile cylindrical ionization chamber VGIC developed for gamma ray dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Fares, M.; Mameri, S.; Abdlani, I.; Negara, K. [COMENA, Laboratoire Detection et Mesures, CRNB, BP no. 180 Ain-Oussera 17200 W. de Djelfa (Algeria)

    2015-07-01

    A versatile Gamma ionization chambers are used for flow control in systems with gamma nuclear reactors and reprocessing plants in and monitoring atmosphere around these facilities, this in order to protect staff. In the Laboratory Detection and Measures (LDM) Division for Study and Development of Nuclear Instrumentation (DSDNI) of CRNB, we designed, developed and characterized a versatile gamma ionization chamber (VGIC) to study experimentally its characteristics according to the geometry of the electrodes, the volume and pressure of the filler gas for the design of a gamma sealed chamber. The tests were conducted under the IEC (International Electro-technical Commission). In this paper, we present the results obtained in the various nuclear tests for characterization and calibration that we have made on the ionization chamber gamma VGIC prototype developed at our Department. To do this, three irradiators were operated at the Laboratory Calibration (SSDL) of the Department of Medical Physics Nuclear Research Center of Algiers (CRNA). Irradiator intensive gamma ({sup 60}Co: 1.25 MeV), one medium intensity gamma ({sup 137}Cs: 0.662 MeV) and 3rd low intensity ({sup 60}Co). Saturation curves and linearity were identified and the operating range and the sensitivity of the chamber have been deducted. The (I,V) characteristics of the chamber filled, with argon gas at 3 bar (0.3 M pa) pressure, for gamma ray irradiator sources were studied. To do so, the chamber was irradiated with gamma rays using different numbers of gamma sources (i.e. Up to 5). The plateau region is reached above 200 V and the detector operating voltage is found to be 600 V. It is observed that in the plateau region the slope is constant with an increase in the exposure rate. The (1/I, 1/V) and (I, l/V{sup 2}) characteristic curves reveal the presence of the initial and volume recombination losses. The volume recombination losses are found to be smaller than the initial recombination losses. Finally

  8. Polarization measurements of proton capture gamma rays

    NARCIS (Netherlands)

    Suffert, M.; Endt, P.M.; Hoogenboom, A.M.

    1959-01-01

    The linear polarization has been measured of eight different gamma rays of widely differing energies (Eγ = 0.8 - 8.0 MeV) emitted at resonances in the 24Mg(p, γ)25Al, 30Si(p, γ)31P, and 32S(p, γ)33Cl reactions. The gamma rays emitted at 90° to the proton beam were Compton scattered in a 2″ NaI scint

  9. Soft gamma rays from heavy WIMPs

    Science.gov (United States)

    Krauss, Manuel Ernst; Opferkuch, Toby; Staub, Florian; Winkler, Martin Wolfgang

    2016-12-01

    We propose an explanation of the galactic center gamma ray excess by supersymmetric WIMPs as heavy as 500 GeV. The lightest neutralino annihilates into vector-like leptons or quarks which cascade decay through intermediate Higgs bosons. Due to the long decay chains, the gamma ray spectrum is much softer than naively expected and peaks at GeV energies. The model predicts correlated diboson and dijet signatures to be tested at the LHC.

  10. Supernovae and Gamma-Ray Bursts

    Science.gov (United States)

    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

  11. Change of urine metabolites spectra and its correlation with time in rats exposed to single 60Co γ-rays%单次60Co γ射线照射致大鼠尿液代谢谱变化及其时间相关性

    Institute of Scientific and Technical Information of China (English)

    张慧芳; 杨彪; 郭月凤; 邢利虹; 郭万龙; 党旭红

    2011-01-01

    OBJECTIVE: To investigate effects of urinary metabolites from single exposure to 5' radiation and to screen urinary metabolites related close to 5' radiation damage in rats. METHODS: 15 male adult SD rats were exposed to 60Co γ -rays whole body once at 6.0 Gy, 0.7 Gy/min. Urine was collected from rats one day before irradiation and 1 d, 2 d, 3 d, 4 d, 8 d, 18 d, 30 d and 45 d after irradiation. Urine 1H NMR spectra were acquired, principal component analysis (PCA) and partial least-squares-discriminant analysis (PLS-DA) methods are utilized to analyze 1H NMR spectra data. Then we looked for the metabolites that contributed more in the difference between urine 1H NMR spectra before exposure and every time after expos ure(abbreviateed as common difference metabolites) and analyzed relation between the change of their relative contents and post-irradiation time. RESULTS: 60Co γ irradiation could cause visible change of urine IH NMR spectra. Common difference metabolites were taurine, trimethylamine-N-oxide, praline, ereatinine, citrate, sueeinate, acetate and lactate that coutributed more in change of 1H NMR spectra of urine collected at different times after exposure. For 1-45 d after exposure, the relative contents of proline and taurine were markedly higher than before irradiation, and citrate and suceinate were lower. However, the relative contents of trimethylamine-N-oxide, acetate and lactate first increased 1 d after irradiation and then decreased for 2-45 d after irradiation. CONCLUSION : The disorder of metabolism in rats induced by high-dose γ radiation did not completely recover for 45 days after irradiation, that showed persistent changes of the relative contents of urine taurine, proline, creatinine, citrate, succinate, acetate and lactate in exposed rats. Taurine and proline could become potential combined metabolic markers of acute high-dose radiation injury.%目的:探讨γ射线单次照射对大鼠尿液代谢物的影响,初步筛选与γ辐射

  12. Gamma-ray Irradiation Induces Useful Morphological Variation in Bermudagrass

    Directory of Open Access Journals (Sweden)

    Songul SEVER MUTLU

    2015-12-01

    Full Text Available Bermudagrass, Cynodon dactylon (L. Pers. is a widely used warm-season turfgrass species in warmer regions of the world. Gamma (ɣ irradiation has been used to generate useful variations in turfgrass breeding for various morphological traits. The objective of the present study was to measure and determine variations in morphology and turfgrass characteristics of a native drought resistant bermudagrass germplasm irradiated with 70, 90 or 110 Gy using a 60Co source. The stolons containing a single node were irradiated and immediately planted for regeneration in a greenhouse at the Akdeniz University, Antalya, Turkey. Selected mutants regenerated from the irradiated stolons were clonally propagated and transplanted into plastic pots for further observations of turfgrass characteristics.  Survival rates of stolons exposed to 70, 90 and 110 Gy were 76%, 43% and 17% respectively, 6 weeks after treatment. Dosages of 85 and 57 Gy were determined as LD50 and LD20 for the cuttings, respectively. The linear reduction of survival rate with increasing gamma-rays was highly correlated (r2=0.99. A total of four mutant lines (0.3 % of the irradiated plants showed a distinct dwarfed growth habit. Three of these lines were originated from 70 Gy and one from 110 Gy. These mutant lines exhibited more dwarf growth habit, higher shoot density, finer leaf texture than parental genotype. Mutant lines developed in this study can be used for the development of improved bermudagrass cultivars for landscaping and sports turf.

  13. Peak efficiency calibration for attenuation corrected cylindrical sources in gamma ray spectrometry by the use of a point source.

    Science.gov (United States)

    Aguiar, Julio C; Galiano, Eduardo; Fernandez, Jorge

    2006-12-01

    A theoretical method of determining the gamma-ray peak efficiency for a cylindrical source, based on a modified expression for point sources is derived. A term for the photon self-attenuation is included in the calculation. The method is valid for any source material as long as the source activity concentration is considered to be homogeneous. Results of this expression are checked against experimental data obtained with (241)Am, (57)Co, (137)Cs, and (60)Co sources.

  14. Peak efficiency calibration for attenuation corrected cylindrical sources in gamma ray spectrometry by the use of a point source

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, Julio C. [Autoridad Regulatoria Nuclear, Laboratorio de Espectrometria Gamma, Centro Atomico Ezeiza, B1802AYA, Buenos Aires (Argentina); Galiano, Eduardo [Department of Physics, Laurentian University, Sudbury, Ont., P3E 2C6 (Canada)]. E-mail: egalianoriveros@laurentian.ca; Fernandez, Jorge [Autoridad Regulatoria Nuclear, Laboratorio de Espectrometria Gamma, Centro Atomico Ezeiza, B1802AYA, Buenos Aires (Argentina)

    2006-12-15

    A theoretical method of determining the gamma-ray peak efficiency for a cylindrical source, based on a modified expression for point sources is derived. A term for the photon self-attenuation is included in the calculation. The method is valid for any source material as long as the source activity concentration is considered to be homogeneous. Results of this expression are checked against experimental data obtained with {sup 241}Am, {sup 57}Co, {sup 137}Cs, and {sup 60}Co sources.

  15. Effects of Shielding on Gamma Rays

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-03-13

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

  16. New insights from cosmic gamma rays

    Science.gov (United States)

    Roland, Diehl

    2016-04-01

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

  17. Gamma Ray Bursts in the HAWC Era

    CERN Document Server

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

    2015-01-01

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

  18. Study of the effect of gamma irradiation ({sup 60} Co) on the quality of sugar cane spirit and on the cask of maturation; Estudo do efeito da irradiacao gamma ({sup 60} Co) na qualidade da cachaca e no tonel de envelhecimento

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Mariana Branco de; Horii, Jorge; Alcarde, Andre Ricardo [Universidade de Sao Paulo (USP), Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Dept.de Agroindustria, Alimentos e Nutricao]. E-mails: jhorii@esalq.usp.br; aralcard@esalq.usp.br

    2006-10-15

    The ageing or maturing process of drink improves the sensorial characteristics of the product making it a qualified drink with higher economical value. The traditional maturing method of drinks involves their interaction with wood and irradiation can accelerate this ageing process. Sugar cane spirit and oak barrels with a 20 L capacity were treated using gamma irradiation (150 Gy). Physical-chemical and chromatographic analyses were constantly performed for 390 days during the drink ageing period. The sugar cane spirit and barrel irradiation did not change most volatile components of the same type coefficient such as volatile acidity, esters, superior alcohols and furfural throughout the 390 days. There is evidence, however, that some component parameters like aldehydes, tannin, color and copper concentration are in some way influenced resulting in partial acceleration of the ageing or maturing process. At the end of the ageing period, a sensorial analysis was made using 30 non-trained people who tasted the drink. The ageing process acceleration was confirmed by the sensorial evaluation, where the irradiated sugar cane spirit and/or barrel had higher approval regarding all parameters analyzed (scent, flavor and appearance). (author)

  19. Technology Needs for Gamma Ray Astronomy

    Science.gov (United States)

    Gehrels, Neil

    2011-01-01

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

  20. TeV Gamma-Ray Astrophysics

    CERN Document Server

    Ribó, M

    2008-01-01

    The window of TeV Gamma-Ray Astrophysics was opened less than two decades ago, when the Crab Nebula was detected for the first time. After several years of development, the technique used by imaging atmospheric Cherenkov telescopes like HESS, MAGIC or VERITAS, is now allowing to conduct sensitive observations in the TeV regime. Water Cherenkov instruments like Milagro are also providing the first results after years of integration time. Different types of extragalactic and galactic sources have been detected, showing a variety of interesting phenomena that are boosting theory in very high energy gamma-ray astrophysics. Here I review some of the most interesting results obtained up to now, making special emphasis in the field of X-ray/gamma-ray binaries.

  1. Study on the Immune Protective Effect of Sophora japonical Water Extract on the Spleen Cells of 60CoRay Irradiated Injured Mice%槐白皮水提物对60Co-γ射线损伤小鼠脾细胞的免疫保护作用研究

    Institute of Scientific and Technical Information of China (English)

    张跃进; 董海艳; 张婵; 李安乐; 陈向敏

    2012-01-01

    目的:研究槐白皮水提物对50Co-γ射线损伤小鼠脾细胞的免疫保护作用.方法:实验分为5组,即正常(等容生理盐水)、照射对照(等容生理盐水)和槐白皮水提物高、中、低剂量(0.8、0.4、0.2 mL·kg-1)组.除正常组外其余各组给予60Co-γ射线一次性照射,照射后立即给药,每天1次,连续10d.测定小鼠脾细胞培养上清液中一氧化氮(NO)水平及脾指数.结果:槐白皮水提物中剂量组NO含量显著低于照射对照组(P<0.05);槐白皮水提物中、低剂量组脾指数显著高于照射对照组(P<0.01或P<0.05).结论:槐白皮水提物能降低射线对脾细胞的损伤,具有免疫保护作用.%OBJECTIVE: To evaluate the immune protective effect of Sophora japonical water extract on the spleen cells of 6cCo-y ray irradiated injured mice. METHODS: Mice were randomly divided into 5 groups: normal group (constant volume normal saline), irradiation control group (constant volume normal saline) ,S. Japonical water extract high-dose, medium-dose and low-dose groups(0.8, 0.4, and 0.2 mL?kg"'). All the mice were irradiated with Mco-y ray except normal group, and then S. Japonical water extract was given once a day for 10 days. And then nitric oxide (NO) level and spleen index was detected in spleen cell of mice. RESULTS: NO level of S. Japonical water extract medium-dose group was significantly lower than irradiation control group(P< 0.01), and the spleen index of S. Japonical water extract medium-doce group and low-dose groups was significantly higher than irradiation control group(f <0.01 or P<0.05). CONCLUSIONS: S. Japonical water extract can reduce the damage of the irradiated spleen cells, and have the immune protective function.

  2. On the difference between gamma-ray-detected and non-gamma-ray-detected pulsars

    CERN Document Server

    Rookyard, Simon C; Johnston, Simon; Kerr, Matthew

    2016-01-01

    We compare radio profile widths of young, energetic gamma-ray-detected and non-gamma-ray-detected pulsars. We find that the latter typically have wider radio profiles, with the boundary between the two samples exhibiting a dependence on the rate of rotational energy loss. We also find that within the sample of gamma-ray-detected pulsars, radio profile width is correlated with both the separation of the main gamma-ray peaks and the presence of narrow gamma-ray components. These findings lead us to propose that these pulsars form a single population where the main factors determining gamma ray detectability are the rate of rotational energy loss and the proximity of the line of sight to the rotation axis. The expected magnetic inclination angle distribution will be different for radio pulsars with and without detectable gamma rays, naturally leading to the observed differences. Our results also suggest that the geometry of existing radio and outer-magnetosphere gamma-ray emission models are at least qualitative...

  3. On-line {sup 60}Co monitor for reactor recirculation system piping in primary containment vessel during reactor operation

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Katsunori, E-mail: katsunori.ueno.pa@hitachi.com [Hitachi Research Laboratory, Hitachi, Ltd., Hitachi 319-1224, Ibaraki (Japan); Tadokoro, Takahiro [Hitachi Research Laboratory, Hitachi, Ltd., Hitachi 319-1224, Ibaraki (Japan); Tsuyuki, Mizuho; Matsubara, Hirofumi; Ota, Nobuyuki; Nagase, Makoto [Hitachi-GE Nuclear Energy, Ltd., Hitachi 317-0073, Ibaraki (Japan)

    2014-10-15

    Highlights: • We developed an on-line {sup 60}Co monitor for reactor recirculation system piping during reactor operation. • Energy resolution at 1.4 × 10{sup 6} cps is 33 keV at 1332 keV using a pulse integral method. • A coincidence method is applied to reduce an effect of background gamma rays. • The coincidence counting of {sup 60}Co cascade gamma rays could be detected for a background dose rate of 4.8 mSv/h. - Abstract: Water chemistry control during reactor operation and installation of temporary radiation shielding prior to scheduled outages are carried out in order to reduce workers’ dose exposure caused by {sup 60}Co which is the main radiation source during scheduled outages of boiling water reactor (BWR) power plants. It is necessary to monitor the deposited {sup 60}Co on inner surfaces of reactor recirculation system (RRS) piping to evaluate effects of water chemistry control. We have developed an on-line {sup 60}Co monitor (OLCM) for this purpose. The OLCM applies a pulse integral method as a new method to measure gamma-ray counts of more than 1.0 × 10{sup 6} counts per second (cps) and a coincidence counting method to reduce an effect of background gamma rays caused by {sup 16}N in the measurement of {sup 60}Co cascade gamma rays. Energy resolution at 1.4 × 10{sup 6} cps is 33 keV using the pulse integral method and single LaBr{sub 3}:Ce scintillation detector. The energy resolutions of this detector using the fast response photo multiplier tube (PMT) are 50 keV at 1.5 × 10{sup 6} cps and 59 keV at 2.1 × 10{sup 6} cps. Furthermore, we measured the energy spectra using the pulse integral method, the coincidence counting method and two LaBr{sub 3}:Ce scintillation detectors and examined the transition of coincidence counting for {sup 60}Co detection under high dose rate during reactor operation at the Kyoto University Research Reactor (KUR). The coincidence counting of {sup 60}Co cascade gamma rays could be detected, and the result was

  4. Development of an analytical model for the determination of {sup 60}Co in aqueous samples by atomic absorption and gamma spectrometry techniques; Elaboracion de un modelo analitico para la determinacion de {sup 60}Co en muestras acuosas mediante tecnicas de absorcion atomica y espectrometria gamma

    Energy Technology Data Exchange (ETDEWEB)

    Solis A, N. A.

    2015-07-01

    The applications of the nuclear energy in industry and medicine generate radioactive wastes that must be isolated and confined in order to limit its spread in the biosphere. These types of wastes are generated in hospitals, industry, research centers and nuclear power plants (during de fuel cycle). The radioactive elements (radionuclides) cannot be destroyed by any known method, either chemical or mechanical. Its final destruction is produced by radioactive decay, which makes them stable isotopes, or nuclear transmutation being bombarded with atomic particles. Consequently, the radioactive waste management is to control the radioactive discharges and reduce to tolerable limits, eliminating of effluents and wastes the radionuclides of interest, concentrating them so they can be stored or evacuated so that later not appear in dangerous concentration in the biosphere. In Mexico, the main generators of radioactive wastes are the nuclear power plant of Laguna Verde in Veracruz, Hospitals of the public and private sector, in addition Instituto Nacional de Investigaciones Nucleares (ININ) some institutes and facilities of the UNAM and Instituto Politecnico Nacional (IPN) and industries among others. The aqueous radioactive wastes, particularly those from the nuclear power plants contain traces of cobalt-60. Currently there is no model or analytical technique for the separation of this radionuclide, so it became necessary to develop an analytical model for separation and facilitate their disposal. In this paper was shown that atomic absorption and gamma spectrometry techniques can separate the active concentration of the inactive, which is important because the total concentration can be associated through direct relationships with the wear of metal parts of the nuclear reactor, since the metal alloys of the same reactor containing a fraction of cobalt. Also this analytical and mathematical model that can be reproducible and applicable to full sets of samples and that this

  5. Neutron and Gamma-ray Measurements

    Science.gov (United States)

    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.

  6. Gamma-Ray Pulsars Expected in the Outer Gap Model of Gamma-Ray Emission

    Institute of Scientific and Technical Information of China (English)

    张力; 吴杰; 姜泽军; 梅冬成

    2003-01-01

    We study the possibility of high-energy gamma-ray emission from the known 1130 radio pulsars based on the outer gap model of high-energy emission from pulsars. We estimate the fractional size of outer gap, the integrated flux, the gamma-ray luminosity for each known radio pulsar, and find that only 14% of the known radio pulsars are gamma-ray emitters according to the outer gap model. In the sample of possible 156 gamma-ray pulsars, our statistical analysis indicates that the distributions of the spin-down powers and the ages of these pulsars concentrate mainly on 1033.5-1039 erg/s and 103-107 y, respectively. The predictions of gamma-ray pulsars detected by the AGILE and GLAST missions are given.

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    Observations of the gamma-ray sky reveal the most powerful sources and the most violent events in the Universe. While at lower wavebands the observed emission is generally dominated by thermal processes, the gamma-ray sky provides us with a view on the non-thermal Universe. Here particles...... are accelerated to extreme relativistic energies by mechanisms which are still poorly understood, and nuclear reactions are synthesizing the basic constituents of our world. Cosmic accelerators and cosmic explosions are major science themes that are addressed in the gamma-ray regime. While Fermi will take......, albeit at much more modest sensitivities. There will be clearly a growing need to perform deeper, more focused investigations of gamma-ray sources in the 100-keV to MeV regime. Recent technological advances in the domain of gamma-ray focusing using Lane diffraction and multilayer-coated mirror techniques...

  8. The Infrared-Gamma-Ray Connection: A WISE View of the Extragalactic Gamma-Ray Sky

    CERN Document Server

    Massaro, F

    2016-01-01

    Using data from the WISE all-sky survey we discovered that the non-thermal infrared (IR) emission of blazars, the largest known population of extragalactic gamma-ray sources, has peculiar spectral properties. In this work, we confirm and strengthen our previous analyses using the latest available releases of both the WISE and the Fermi source catalogs. We also show that there is a tight correlation between the mid-IR colors and the gamma-ray spectral index of Fermi blazars. We name this correlation "the infrared--gamma-ray connection". We discuss how this connection links both the emitted powers and the spectral shapes of particles accelerated in jets arising from blazars over ten decades in energy. Based on this evidence, we argue that the infrared--gamma-ray connection is stronger than the well known radio--gamma-ray connection.

  9. Different gamma radiation doses effects of {sup 60} Co on buds of banana plant (Nanicao-AAA) breeded in vitro; Efeito de diferentes doses de radiacao gama do {sup 60} Co em gemas de bananeira (Nanicao-AAA) desenvolvidas in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Gilberto Dias [Pernambuco Univ., Recife, PE (Brazil). Dept. de Botanica; Andrade, Arnobio Goncalves de [Universidade Federal Rural de Pernambuco, Recife, PE (Brazil). Lab. de Quimica Vegetal; Kido, Laureen Michelle Houllou; Franca, Jose Geraldo Eugenio de [Empresa Pernambucasna de Pesquisa Agropecuaria (IPA), Recife, (Brazil); Colaco, Waldeciro [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear

    1999-11-01

    Buds from banana cv. Nanicao-AAA (3 mm x 3 mm) were aseptically cultured in a modified Murashige and Skoog (MS) basal medium supplement with bezylaminepurine and sucrose, and solidified with agar. Buds placed on sterile Petri dishes were irradiated with increasing gamma rays doses (10, 20, 30, and 40 Gy). The statistical design was completely randomized with 5 doses and 30 replications. After irradiation, buds were transferred to 10 ml of the same medium into test tubes, and allowed to grow in a controlled environment (25 deg C, 16 h illumination ) for 4 weeks. There were no significant differences (Tukey, 0,05) between doses in terms of oxidation: in around 20% for all treatments. On the other hand, a statistically significant decrease in the germination of new buds with increased doses of irradiation was observed. The treatment with 40 Gy reduced in 80% the germination of new buds by the end of the evaluated period (4 weeks), resulting in a mean production of 1,5 buds. Mean production in the control was 7,6 buds. no statistically significant differences were detected between treatments with 10, 20, and 30 Gy, with a mean production of 3 buds, less than half obtained in the control. (author) 9 refs., 2 figs.

  10. Gamma-Ray Astronomy from the Ground

    CERN Document Server

    Horns, D

    2016-01-01

    The observation of cosmic gamma-rays from the ground is based upon the detection of gamma-ray initiated air showers. At energies between approximately $10^{11}$ eV and $10^{13}$ eV, the imaging air Cherenkov technique is a particularly successful approach to observe gamma-ray sources with energy fluxes as low as $\\approx 10^{-13}$ erg\\,cm$^{-2}\\,$s$^{-1}$. The observations of gamma-rays in this energy band probe particle acceleration in astrophysical plasma conditions and are sensitive to high energy phenomena beyond the standard model of particle physics (e.g., self-annihilating or decaying dark matter, violation of Lorentz invariance, mixing of photons with light pseudo-scalars). The current standing of the field and its major instruments are summarised briefly by presenting selected highlights. A new generation of ground based gamma-ray instruments is currently under development. The perspectives and opportunities of these future facilities will be discussed.

  11. Stellar Photon Archaeology with Gamma-Rays

    Science.gov (United States)

    Stecker, Floyd W.

    2009-01-01

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

  12. Influence of phantom materials on the energy dependence of LiF:Mg,Ti thermoluminescent dosimeters exposed to 20-300 kV narrow x-ray spectra, 137Cs and 60Co photons.

    Science.gov (United States)

    Massillon-J L, G; Cabrera-Santiago, A; Minniti, R; O'Brien, M; Soares, C G

    2014-08-07

    LiF:Mg,Ti, are widely used to estimate absorbed-dose received by patients during diagnostic or medical treatment. Conveniently, measurements are usually made in plastic phantoms. However, experimental conditions vary from one group to another and consequently, a lack of consensus data exists for the energy dependence of thermoluminescent (TL) response. This work investigated the energy dependence of TLD-100 TL-response and the effect of irradiating the dosimeters in different phantom materials for a broad range of energy photons in an attempt to understand the parameters that affect the discrepancies reported by various research groups. TLD-100s were exposed to 20-300 kV narrow x-ray spectra, (137)Cs and (60)Co photons. Measurements were performed in air, PMMA, wt1, polystyrene and TLDS as surrounding material. Total air-kerma values delivered were between 50 and 150 mGy for x-rays and 50 mGy for (137)Cs and (60)Co beams; each dosimeter was irradiated individually. Relative response, R, defined as the TL-response per air-kerma and relative efficiency, RE, described as the TL-response per absorbed-dose (obtained through Monte Carlo (MC) and analytically) were used to describe the TL-response. Both R and RE are normalized to the responses in a (60)Co beam. The results indicate that the use of different phantom materials affects the TL-response and this response varies with energy and material type. MC simulations reproduced qualitatively the experimental data: a) R increases, reaches a maximum at ~25 keV and decreases; b) RE decreases, down to a minimum at ~60 keV, increases to a maximum at ~150 keV and after decreases. Independent of the phantom materials, RE strongly depends on how the absorbed dose is evaluated and the discrepancies between RE evaluated analytically and by MC simulation are around 4% and 18%, dependent on the photon energy. The comparison between our results and that reported in the literature suggests that the discrepancy observed

  13. Relativistic feedback models of terrestrial gamma-ray flashes and gamma-ray glows

    Science.gov (United States)

    Dwyer, J. R.

    2015-12-01

    Relativistic feedback discharges, also known as dark lightning, are capable of explaining many of the observed properties of terrestrial gamma-ray flashes (TGFs) and gamma-ray glows, both created within thunderstorms. During relativistic feedback discharges, the generation of energetic electrons is self-sustained via the production of backward propagating positrons and back-scattered x-rays, resulting in very larges fluxes of energetic radiation. In addition, ionization produces large electric currents that generate LF/VLF radio emissions and eventually discharge the electric field, terminating the gamma-ray production. In this presentation, new relativistic feedback model results will be presented and compared to recent observations.

  14. Effect of gamma radiation from {sup 60}C in conservation and quality of pepper fresh and pulp; Efeito da radiacao gama do {sup 60}Co na conservacao e qualidade de pimenta in natura e em polpa

    Energy Technology Data Exchange (ETDEWEB)

    Milagres, Regina Celia Rodrigues de Miranda

    2014-07-01

    Capsicum peppers are among the most used and most valued seasoning spices in the world. They are highly susceptible to post harvest decay, therefore the use of irradiation may contribute to conservation of this fruit which has significant nutritional, economic and social value. Were evaluated the effects of gamma radiation of {sup 60}Co in increasing the shelf-life and preservation of quality of pepper 'Dedo-de-moca' (Capsicum baccatum var. Pendulum) fresh and pulp associated or not with another conservation methods. Gamma radiation doses were investigated of 0,25; 0,50; 0,75; 1,00; 1,25; 1,50; 2,00 e 3,00 kGy in fresh fruit and 1,50; 2,00; 3,00; 4,50 e 6,00 kGy in pepper pulp. The use of laboratory pasteurization (85°C/3min), the addition of citric acid (5%) and 5% NaCl were also investigated in the pepper pulp. The samples were stored at 5 °C and or 25 °C. Were performed analysis: visual (disease incidence, turgidity and color); bioactive compounds (carotenoids, capsaicinoids, antioxidant capacity and phenolic compounds); physicochemical (Weight loss, firmness, soluble solids (SS), pH, titratable acidity (TA), ratio, color and moisture); respiratory rate and ethylene production; proximate composition (moisture, soluble and insoluble fiber, ash, protein, ether extract, total and available carbohydrate); microbiological contamination (mesophilic aerobic microorganisms, coliforms at 45 °C, Salmonella spp. and yeasts and molds) and sensory (acceptance test, difference test and paired preference). Radiation doses between 0.25 and 3.00 kGy were not effective to increase shelf-life and maintain fresh pepper quality during storage. There was increased intensity of red color, of incidence of disease, decreased turgidity and changes in physical, chemical and nutritional parameters. In pulp, the doses of gamma radiation of 4.50 and 6.00 kGy and the addition of 5% NaCl no changing sensory attributes, physical-chemical and bioactive compounds. Only the

  15. Estudo do efeito da irradiação gamma (60CO na qualidade da cachaça e no tonel de envelhecimento Study of the effect of gamma irradiation (60co on the quality of sugar cane spirit and on the cask of maturation

    Directory of Open Access Journals (Sweden)

    Mariana Branco de Miranda

    2006-12-01

    Full Text Available O processo de envelhecimento ou maturação das bebidas proporciona uma melhora nas características sensoriais da cachaça, tornando-a de qualidade superior e de maior valor econômico. O método tradicional de maturação de bebidas é sua interação com madeiras, sendo que a irradiação pode acelerar este processo de envelhecimento. A cachaça e os tonéis de carvalho de 20 L de capacidade foram submetidos à irradiação gama (150 Gy. Análises físico-químicas e cromatográficas foram realizadas periodicamente ao longo de 390 dias do período de envelhecimento da bebida. A irradiação da cachaça e do tonel não alterou a maioria dos componentes voláteis do coeficiente de congêneres como acidez volátil, ésteres, álcoois superiores e furfural durante os 390 dias. Há evidências, entretanto, de que os parâmetros de alguns componentes como aldeídos, taninos, cor e teor de cobre são de alguma forma influenciados, resultando em aceleração parcial do processo de maturação ou envelhecimento. Ao final do período de envelhecimento, foi feita uma análise sensorial com 30 provadores não treinados. A aceleração do processo de envelhecimento foi confirmada pela avaliação sensorial, e a cachaça e/ou tonel irradiados receberam maior indicação de aprovação em todos os parâmetros analisados (aroma, sabor e aparência.The ageing or maturing process of drink improves the sensorial characteristics of the product making it a qualified drink with higher economical value. The traditional maturing method of drinks involves their interaction with wood and irradiation can accelerate this ageing process. Sugar cane spirit and oak barrels with a 20 L capacity were treated using gamma irradiation (150 Gy. Physical-chemical and chromatographic analyses were constantly performed for 390 days during the drink ageing period. The sugar cane spirit and barrel irradiation did not change most volatile components of the same type coefficient such

  16. Gamma photometric redshifts for long gamma-ray bursts

    CERN Document Server

    Bagoly, Z; Mészáros, A; Mészáros, P; Horváth, I; Balázs, L G; Vavrek, R

    2003-01-01

    It is known that the soft tail of the gamma-ray bursts' spectra show excesses from the exact power-law dependence. In this article we show that this departure can be detected in the peak flux ratios of different BATSE DISCSC energy channels. This effect allows to estimate the redshift of the bright long gamma-ray bursts in the BATSE Catalog. A verification of these redshifts is obtained for the 8 GRB which have both BATSE DISCSC data and measured optical spectroscopic redshifts. There is good correlation between the measured and esti redshifts, and the average error is $\\Delta z \\approx 0.33$. The method is similar to the photometric redshift estimation of galaxies in the optical range, hence it can be called as "gamma photometric redshift estimation". The estimated redshifts for the long bright gamma-ray bursts are up to $z \\simeq 4$. For the the faint long bursts - which should be up to $z \\simeq 20$ - the redshifts cannot be determined unambiguously with this method.

  17. New insights from cosmic gamma rays

    CERN Document Server

    Diehl, Roland

    2016-01-01

    The measurement of gamma rays from cosmic sources at MeV energies is one of the key tools for nuclear astrophysics, in its study of nuclear reactions and their impacts on objects and phenomena throughout the universe. Gamma rays trace nuclear processes most directly, as they originate from nuclear transitions following radioactive decays or high-energy collisions with excitation of nuclei. Additionally, the unique gamma-ray signature from the annihilation of positrons falls into this astronomical window and is discussed here: Cosmic positrons are often produced from beta-decays, thus also of nuclear physics origins. The nuclear reactions leading to radioactive isotopes occur inside stars and stellar explosions, which therefore constitute the main objects of such studies. In recent years, both thermonuclear and core-collapse supernova radioactivities have been measured, and complement conventional supernova observations with measurements of their prime energy sources. The diffuse radioactive afterglow of massi...

  18. Solar hard X-rays and gamma-rays

    Institute of Scientific and Technical Information of China (English)

    甘为群; 常进; 李友平; 林春梅

    2002-01-01

    We briefly introduce our recent work on the spectral evolution of energetic protons, the beam property of accelerated electrons, the gamma-ray flare classification, the temporal features of the annihilation line, the hard X-ray delayed events, the hydrodynamic process, and the continuum emission in solar flares.

  19. Supernovae and Gamma Ray Bursts

    Directory of Open Access Journals (Sweden)

    M. Della Valle

    2007-01-01

    Full Text Available Se revisa el estatus observacional de la conexi on Supernova (SN/Estallido de Rayos-Gamma (GRB. Recientes (y no tan recientes observaciones de GRBs largos sugieren que una fracci on signi cativa de ellos (pero no todos est an asociados con supernovas brillantes del tipo Ib/c. Estimaciones actuales de las tasas de producci on de GRBs y SNs dan una raz on para GRB/SNe-Ibc en el rango 0:4%

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

    Science.gov (United States)

    Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu V.; Kaplin, V. A.; Kachanov, V. A.; Kheymits, M. D.; Leonov, A. A.; Longo, F.; Mazets, E. P.; Maestro, P.; Marrocchesi, P.; Mereminskiy, I. A.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu

    2012-01-01

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

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

    CERN Document Server

    Galper, A M; Aptekar, R L; Arkhangelskaja, I V; Arkhangelskiy, A I; Boezio, M; Bonvicini, V; Boyarchuk, K A; Fradkin, M I; Gusakov, Yu V; Kaplin, V A; Kachanov, V A; Kheymits, M D; Leonov, A A; Longo, F; Mazets, E P; Maestro, P; Marrocchesi, P; Mereminskiy, I A; Mikhailov, V V; Moiseev, A A; Mocchiutti, E; Mori, N; Moskalenko, I V; Naumov, P Yu; Papini, P; Picozza, P; Rodin, V G; Runtso, M F; Sparvoli, R; Spillantini, P; Suchkov, S I; Tavani, M; Topchiev, N P; Vacchi, A; Vannuccini, E; Yurkin, Yu T; Zampa, N; Zverev, V G; Zirakashvili, V N

    2012-01-01

    The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma rays and cosmic-ray electrons + positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. The GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is ~0.01 deg (E{\\gamma} > 100 GeV), the energy resolution ~1% (E{\\gamma} > 10 GeV), and the proton rejection factor ~10E6. GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

  2. Nuclear forensics using gamma-ray spectroscopy

    CERN Document Server

    Norman, Eric B

    2016-01-01

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

  3. Nuclear Forensics using Gamma-ray Spectroscopy

    Directory of Open Access Journals (Sweden)

    Norman E. B.

    2016-01-01

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

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

    CERN Document Server

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

    2001-01-01

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

  5. Nuclear Forensics using Gamma-ray Spectroscopy

    Science.gov (United States)

    Norman, E. B.

    2016-09-01

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

  6. Gamma rays and the origin of Galactic Cosmic Rays

    Science.gov (United States)

    de Ona Wilhelmi, Emma

    2015-08-01

    Cosmic rays (CRs) are highly energetic nuclei (plus a small fraction of electrons) which fill the Galaxy and carry on average as much energy per unit volume as the energy density of starlight, the interstellar magnetic fields, or the kinetic energy density of interstellar gas. The CR spectrum extends as a featureless power-law up to ~2 PeV (the 'knee') and it is believed to be the result of acceleration of those CRs in Galactic Sources and later diffusion and convection in galactic magnetic fields. Those energetic CRs can interact with the surrounding medium via proton-proton collision resulting in secondary gamma-ray photons, observed from 100 MeV to a few tens of TeV. The results obtained by the current Cherenkov telescopes and gamma-ray satellites with the support of X-ray observations have discovered and identified more than 50 Galactic gamma-ray sources. Among them, the number of Supernova remnants (SNRs) and very-high-energy hard-spectrum sources (natural candidates to originate CRs) are steadily increasing. We expect to increase by a factor 10 at least this population of source with the future CTA experiment. I will review our current knowledge of Galactic gamma-ray sources and their connection with energetic CRs and the scientific prospects for CTA in this field. Those observations, together with a strong multi-wavelenght support from radio to hard X-rays, will finally allow us to establish the origin of the Galactic CRs.

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

    CERN Document Server

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

    2013-01-01

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

  8. Determination of the correction factor for attenuation, dispersion and production of electrons (K{sub wall}) in the wall of graphite of a ionization chamber Pattern National Type CC01 in fields of gamma radiation of {sup 60}Co; Determinacion del factor de correccion por atenuacion, dispersion y produccion de electrones (K{sub wall}) en la pared de grafito de una Camara de Ionizacion Patron Nacional Tipo CC01 en campos de radiacion gamma de {sup 60} Co

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez R, J.T.; Morales P, J.; Cruz E, P. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2001-12-15

    It was determined the Kwall correction factor for the wall of graphite of the chamber of the pattern national type CC01 series 133 for a radiation field Gamma of {sup 60}Co. With this end to measured the currents of ionization l(x) as function of the thickness of the wall of the chamber: X=4,8,12,16 and 20 mm.The mensurations for each thickness consisting of three groups, of sizes n = 30 or 60 data for each group; obtaining 8 complete groups of mensurations independent in eight different dates.The determinate the factor carried out using three regression models: lineal, logarithmic and quadratic, models that were tried to validate with the tests of : i) Shapiro-Wilk and {chi}{sup 2} for the normality of the entrance data ii) Tests of Bartlett for variances homogeneity among groups for each thickness iii) The tests of Duncan for the stockings among groups of each thickness, and iv) The tests of adjustment lack (LOF) for the models used. Nevertheless, alone the models of the group of corresponding mensurations at 01-03-2000 17-08-2001 they can be validated by LOF, but not for tests of normality and homogeneity of variances. Among other assignable causes of variation we have: i) The values captured by the system of mensuration of the variables of it influences: pressure, temperature and relative humidity don{sup t} belong together with the existent ones to the moment to capture the l(x). ii) The mensuration room presents flows of air, for what was suited o diminish their volume and to eliminate the flows of air. iii) A protocol settled down of taking of measures that it consisted in: - Pre-irradiation 5 minutes the chamber after the change of polarity and hood change, with a period of stabilization of 5 minutes after the pre-irradiation. - Pre-irradiation for 5 minutes before the taking of the readings, with the object of eliminating variation sources assigned to currents of escapes or due variations to transitory. iv) To realize corrections for relative humidity of

  9. Stirling Colgate and Gamma-Ray Bursts

    Science.gov (United States)

    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.

  10. Fluorescence in situ hybridization detection of chromosome translocations induced by 60Co γ-rays in human lymphocytes dose-response curve and persistence%用荧光原位杂交技术建立60Coγ射线诱发人外周血淋巴细胞染色体易位率剂量效应曲线及易位的持续性研究

    Institute of Scientific and Technical Information of China (English)

    王晓琳; 李进; 王知权

    2001-01-01

    Objective To study dose-response relationship for chromosome translocation and its persistence measured in human lymphocytes exposed to 60Co γ-rays.Methods The chromosome translocations in human peripheral lymphocytes were detected by fluorescence in situ hybridization using 4# and 7# combination of composite whole chromosome-specific DNA probes and Giemsa stain.Results The dose-response relationship for chromosome translocation induced by 60Co γ-rays in vitro could be described by the function:Y=0.0030+0.0134D+0.0165D2.The frequencies of chromosome translocations induced by 0.5 and 2 Gy γ-irradiation did not diminish over time,so it exhibited excellent persistence.Conclusions The results indicate that retrospective dose-reconstruction can be accomplished using chromosome translocation frequency.%目的研究不同剂量60Coγ射线诱发人外周血淋巴细胞染色体易位率和辐射剂量间的剂量效应关系以及观察易位率在同一剂量、不同时相点的变化。方法采用荧光原位杂交技术和连续Giemsa法,用4号和7号全染色体探针分析0、0.25、0.5、0.75、1和2 Gy 60Coγ射线离体照射诱发人外周血淋巴细胞染色体易位率,同时对两个剂量点进行52和72 h培养,比较其易位率。结果易位率和辐射剂量间的量效关系可以用一个二次多项式方程Y=0.0030+0.0134D+0.0165D2来描述;易位率在52和72 h培养时差异无显著性。结论易位率和辐射剂量间存在良好的量效关系,可作为进行早先照射剂量重建的理论依据。

  11. Research on novel crosslinkers of polyolefins using {gamma}-ray

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Dong Hack; Lee, In jai; Yang, Nam Choul; Hwang, Jo Il; Chung, Woo Young [Hanyang University, Seoul (Korea)

    2001-04-01

    The radiation processing has been widely used as the modification technique to develop new materials such as high performance polymers in which the conventional chemical processing has been unable to apply. For the purpose of using in nuclear power plants, cable materials are required to have excellent physical and chemical properties such as high thermal, radiation and chemical stabilities. Conventional crosslinkers for cable materials such as triallyl cyanurate-based amine derivatives show low melting points and high vapor pressures, which causes the large weight loss due to the high working temperature during the procedure of the film preparation. In this research, we synthesized crosslinkers having imide groups to increase thermal and radiation stabilities. The mixture of LDPE and these crosslinkers was irradiated with 60Co {gamma}-rays at room temperature in nitrogen. The absorbed does range from 1-160KGy. The synthesized crosslinkers showed a good compatibility with LDPE. Among these crosslinkers, m-xylylenedimaleimide is the best in gel fraction enhancement. LDPE crosslinked with m-xylylenedimaleimide displays higher tensile strength than that crosslinked with triallyl cyanurate. In case of elongation property, the usage of m-xylylenedimaleimide crosslinker shows the best result than those of commercial crosslinkers such as triallyl cyanurate and trimethylol propane triacrylate. 24 refs., 21 figs., 1 tabs. (Author)

  12. Effects of γ-ray total body irradiation from a 60Co source on expression level of intrathymic forkhead box protein N1 in mice%60Coγ射线全身照射对小鼠胸腺中叉状头转录因子N1表达水平的影响

    Institute of Scientific and Technical Information of China (English)

    孙玉琦; 武育菁; 刘洁; 潘彬; 徐开林

    2016-01-01

    delta样配体(DLL)4、自身免疫调节蛋白(Aire)与骨形成蛋白(BMP)4 mRNA相对表达水平相比,差异均有统计学意义(CCL25 mRNA相对表达水平:11.2±1.5、11.4±1.2、1.0±0.1,DLL4 mRNA相对表达水平:7.3±0.9、6.3±0.3、1.0±0.1,Aire mRNA相对表达水平:5.1±1.0、5.0±0.1、1.0±0.1,BMP4 mRNA相对表达水平:4.4±1.4、3.6±0.5、1.0±0.1;F=148.862、197.667、73.911、21.471,P=0.000、0.000、0.000、0.000);3组中Foxn1上游基因同源框蛋白(Hox)a3 mRNA相对表达水平相比,差异却无统计学意义(1.4±0.4、0.8±0.3、1.0±0.1相比;F=5.368,P=0.221).与对照组相比,L-TBI 5 d组中Foxn1下游基因CCL25、DLL4与Aire的mRNA相对表达水平均显著增高(p=0.000、0.000、0.000);SL-TBI 5 d组中CCL25、DLL4与Aire mRNA相对表达水平亦显著增高(P=0.000、0.000、0.000).同时,与对照组相比,L-TBI 5 d组、SL-TBI 5 d组中BMP4mRNA相对表达水平存在一定程度的增高,且差异亦有统计学意义(P=0.000、0.000).结论 60C0γ射线TBI可导致小鼠胸腺中Foxn1mRNA表达水平增高,Foxn1表达水平上调及其相关基因表达水平的变化与胸腺受损程度的关系密切.%Objectives To explore the influence of γ-ray total body irradiation (TBI) from a 60Co source induced mice thymus injury on expression levels of forkhead box protein N (Foxn) 1 and related genes,and to analyze the correlation between expression levels of Foxn1,related genes and thymus injury.Methods Sixty five male C57BL/6 mice were chosen as subjects during November and December 2014.Inclusion criteria for choosing mice:all these mice are 6-8 weeks old specific pathogen free (SPF) animals,and weighting between 18.0-21.0 g.Thirty-five mice were randomly devided into 4 groups:① Lethal total body irradiation (L-TBI) 5 d group (n=10),mice received a total dose of 7.5 Gy γ-ray TBI from a 60Co source;② Sublethal total body irradiation (SL-TBI) 5 d group (n=10),mice received a total dose of 5.5 Gy TBI;③SL-TBI 24 d group (n =10),mice

  13. Gamma-ray bursts at high redshift

    NARCIS (Netherlands)

    R.A.M.J. Wijers

    1999-01-01

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

  14. Gamma-Ray Telescope and Uncertainty Principle

    Science.gov (United States)

    Shivalingaswamy, T.; Kagali, B. A.

    2012-01-01

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

  15. Gamma-ray emission from nova outbursts

    CERN Document Server

    Hernanz, M

    2013-01-01

    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 nov...

  16. Gamma-Rays from Intergalactic Shocks

    CERN Document Server

    Keshet, U; Loeb, A; Springel, V; Hernquist, L E; Keshet, Uri; Waxman, Eli; Loeb, Abraham; Springel, Volker; Hernquist, Lars

    2003-01-01

    Structure formation in the intergalactic medium (IGM) produces large-scale, collisionless shock waves, where electrons can be accelerated to highly relativistic energies. Such electrons can Compton scatter cosmic microwave background photons up to gamma-ray energies. We study the radiation emitted in this process using a hydrodynamic cosmological simulation of a LCDM universe. The resulting radiation, extending beyond TeV energies, has roughly constant energy flux per decade in photon energy, in agreement with the predictions of Loeb & Waxman (2000). Assuming that a fraction \\xi_e=0.05 of the shock energy is transferred to the relativistic electrons, as inferred from collisionless non-relativistic shocks in the interstellar medium, we find that the radiation energy flux, e^2 (dJ/de) ~ 50-160 eV cm^{-2} s^{-1} sr^{-1}, constitutes ~10% of the extragalactic gamma-ray background flux. The associated gamma-ray point-sources are too faint to account for the ~60 unidentified EGRET gamma-ray sources, but GLAST s...

  17. Gamma ray observations of the solar system

    Science.gov (United States)

    1981-01-01

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

  18. Gamma Rays From Rotation-Powered Pulsars

    CERN Document Server

    Harding, A K

    2002-01-01

    The seven known gamma-ray pulsars represent a very small fraction of the more than 1000 presently known radio pulsars, yet they can give us valuable information about pulsar particle acceleration and energetics. Although the theory of acceleration and high-energy emission in pulsars has been studied for over 25 years, the origin of the pulsed gamma rays is a question that remains unanswered. Characteristics of the pulsars detected by the Compton Gamma-Ray Observatory could not clearly distinguish between an emission site at the magnetic poles (polar cap models) and emission from the outer magnetosphere (outer gap models). There are also a number of theoretical issues in both type of model which have yet to be resolved. The two types of models make contrasting predictions for the numbers of radio-loud and radio-quiet gamma-ray pulsars and of their spectral characteristics. GLAST will probably detect at least 50 radio-selected pulsars and possibly many more radio-quiet pulsars. With this large sample, it will b...

  19. New shield for gamma-ray spectrometry

    Science.gov (United States)

    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.

  20. Black Hole Accretion in Gamma Ray Bursts

    Directory of Open Access Journals (Sweden)

    Agnieszka Janiuk

    2017-02-01

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

  1. Chandra Imaging of Gamma-Ray Binaries

    CERN Document Server

    Kargaltsev, Oleg; Hare, Jeremy; Pavlov, George G

    2013-01-01

    We review the multiwavelength properties of the few known gamma-ray binaries, focusing on extended emission recently resolved with Chandra. We discuss the implications of these findings for the nature of compact objects and for physical processes operating in these systems.

  2. Gamma-ray Novae: Rare or Nearby?

    CERN Document Server

    Morris, Paul J; Brown, Anthony M; Chadwick, Paula M

    2016-01-01

    Classical Novae were revealed as a surprise source of gamma-rays in Fermi LAT observations. During the first 8 years since the LAT was launched, 6 novae in total have been detected to > 5 sigma in gamma-rays, in contrast to the 69 discovered optically in the same period. We attempt to resolve this discrepancy by assuming all novae are gamma-ray emitters, and assigning peak one-day fluxes based on a flat distribution of the known emitters to a simulated population. To determine optical parameters, the spatial distribution and magnitudes of bulge and disc novae in M31 are scaled to the Milky Way, which we approximate as a disc with a 20 kpc radius and elliptical bulge with semi major axis 3 kpc and axis ratios 2:1 in the xy plane. We approximate Galactic reddening using a double exponential disc with vertical and radial scale heights of r_d = 5 kpc and z_d = 0.2 kpc, and demonstrate that even such a rudimentary model can easily reproduce the observed fraction of gamma-ray novae, implying that these apparently r...

  3. HAWC observatory catches first gamma rays

    Science.gov (United States)

    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.

  4. Gamma-ray Output Spectra from 239Pu Fission

    Directory of Open Access Journals (Sweden)

    Ullmann John

    2015-01-01

    Full Text Available 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.

  5. Gamma-Gamma Absorption in the Broad Line Region Radiation Fields of Gamma-Ray Blazars

    CERN Document Server

    Boettcher, Markus

    2016-01-01

    The expected level of gamma-gamma absorption in the Broad Line Region (BLR) radiation field of gamma-ray loud Flat Spectrum Radio Quasars (FSRQs)is evaluated as a function of the location of the gamma-ray emission region. This is done self-consistently with parameters inferred from the shape of the spectral energy distribution (SED) in a single-zone leptonic EC-BLR model scenario. We take into account all geometrical effects both in the calculation of the gamma-gamma opacity and the normalization of the BLR radiation energy density. As specific examples, we study the FSRQs 3C279 and PKS 1510-089, keeping the BLR radiation energy density at the location of the emission region fixed at the values inferred from the SED. We confirm previous findings that the optical depth due to $\\gamma\\gamma$ absorption in the BLR radiation field exceeds unity for both 3C279 and PKS 1510-089 for locations of the gamma-ray emission region inside the inner boundary of the BLR. It decreases monotonically, with distance from the cen...

  6. High energy gamma-ray emission from Gamma-Ray Bursts -- before GLAST

    CERN Document Server

    Fan, Yi-Zhong

    2008-01-01

    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.

  7. Thermal, tensile and rheological properties of high density polyethylene (HDPE) processed and irradiated by gamma-ray in different atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Ferreto, H. F. R., E-mail: hferreto@ipen.br, E-mail: ana-feitoza@yahoo.com.br; Oliveira, A. C. F., E-mail: hferreto@ipen.br, E-mail: ana-feitoza@yahoo.com.br; Parra, D. F., E-mail: dfparra@ipen.br, E-mail: ablugao@ipen.br; Lugão, A. B., E-mail: dfparra@ipen.br, E-mail: ablugao@ipen.br [Center of Chemistry and Environment, Institute of Energy and Nuclear Research - IPEN (Brazil); Gaia, R., E-mail: renan-gaia7@hotmail.com [Faculdades Oswaldo Cruz (Brazil)

    2014-05-15

    The aim of this paper is to investigate structural changes of high density polyethylene (HDPE) modified by ionizing radiation (gamma rays) in different atmospheres. The gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical-chemical and mechanical properties. Gamma irradiation originates free radicals which can induce chain scission or recombination, providing its annihilation, branching or crosslinking. This polymer was irradiated with gamma source of {sup 60}Co at doses of 5, 10, 20, 50 or 100 kGy at a dose rate of 5 kGy/h. The changes in molecular structure of HDPE, after gamma irradiations were evaluated using thermogravimetric analysis (TGA) and tensile machine and oscillatory rheology. The results showed the variations of the properties depending on the dose at each atmosphere.

  8. Thermal, tensile and rheological properties of high density polyethylene (HDPE) processed and irradiated by gamma-ray in different atmospheres

    Science.gov (United States)

    Ferreto, H. F. R.; Oliveira, A. C. F.; Gaia, R.; Parra, D. F.; Lugão, A. B.

    2014-05-01

    The aim of this paper is to investigate structural changes of high density polyethylene (HDPE) modified by ionizing radiation (gamma rays) in different atmospheres. The gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical-chemical and mechanical properties. Gamma irradiation originates free radicals which can induce chain scission or recombination, providing its annihilation, branching or crosslinking. This polymer was irradiated with gamma source of 60Co at doses of 5, 10, 20, 50 or 100 kGy at a dose rate of 5 kGy/h. The changes in molecular structure of HDPE, after gamma irradiations were evaluated using thermogravimetric analysis (TGA) and tensile machine and oscillatory rheology. The results showed the variations of the properties depending on the dose at each atmosphere.

  9. $\\gamma$-Ray Absorption at High Redshifts and the $\\gamma$-Ray Background

    CERN Document Server

    Stecker, F W

    1997-01-01

    We present results of a calculation of absorption of 10-500 GeV gamma-rays at high redshifts. This calculation requires the determination of the high- redshift evolution of the full spectral energy distribution of the intergalactic photon field. For this, we have primarily followed the recent analysis of Fall, Charlot and Pei. We give our results for the gamma-ray opacity as a function of redshift out to a redshift of 3. We then give predicted gamma-ray spectra for selected blazars and also extend our results on the background from unresolved blazars to an energy of 500 GeV. Absorption effects are predicted to significantly steepen the background spectrum above 20 GeV. Our absorption calculations can be used to place limits on the redshifts of gamma-ray bursts. Our background calculations can be used to determine the observability of multi-GeV lines from dark matter neutralino particles.

  10. Systematic Study of Gamma-ray bright Blazars with Optical Polarization and Gamma-ray Variability

    CERN Document Server

    Itoh, Ryosuke; Fukazawa, Yasushi; Uemura, Makoto; Tanaka, Yasuyuki T; Kawabata, Koji S; Madejski, Grzegorz M; Schinzel, Frank K; Kanda, Yuka; Shiki, Kensei; Akitaya, Hiroshi; Kawabata, Miho; Moritani, Yuki; Nakaoka, Tatsuya; Ohsugi, Takashi; Sasada, Mahito; Takaki, Katsutoshi; Takata, Koji; Ui, Takahiro; Yamanaka, Masayuki; Yoshida, Michitoshi

    2016-01-01

    Blazars are highly variable active galactic nuclei which emit radiation at all wavelengths from radio to gamma-rays. Polarized radiation from blazars is one key piece of evidence for synchrotron radiation at low energies and it also varies dramatically. The polarization of blazars is of interest for understanding the origin, confinement, and propagation of jets. However, even though numerous measurements have been performed, the mechanisms behind jet creation, composition and variability are still debated. We performed simultaneous gamma-ray and optical photopolarimetry observations of 45 blazars between Jul. 2008 and Dec. 2014 to investigate the mechanisms of variability and search for a basic relation between the several subclasses of blazars. We identify a correlation between the maximum degree of optical linear polarization and the gamma-ray luminosity or the ratio of gamma-ray to optical fluxes. Since the maximum polarization degree depends on the condition of the magnetic field (chaotic or ordered), thi...

  11. Re-estimation of absolute gamma ray intensities of 56Mn using k0- standardization

    Institute of Scientific and Technical Information of China (English)

    M. AHMAD; W. AHMAD; M. U. RAJPUT; A. QAYYUM

    2005-01-01

    The thermal neutron capture gamma ray facility at Pakistan Research Reactor (PARR-1) is being used for the re-estimation of various properties like capture cross-sections, resonance integral, absolute gamma intensities, etc.of different isotopes. The data for gamma ray transitions from the capture of thermal neutrons by 55Mn are not in good agreement specifically below 2 MeV. So there is a need to re-estimate its intensities with better accuracy. Analytical grade MnCl2 powder and high purity Mn metal pieces were used in this study. Standard 152Eu and 60Co radioactive sources as well as thermal neutron capture γ-rays in chlorine were chosen for efficiency calibration. The k0standardization technique was applied for these measurements to eliminate systematic errors in efficiencies. Chlorine also acted as a comparator in k0- factor calculations. The results have been tabulated for the main gamma rays from 56Mn in the low as well as in the medium energy regions. The absolute intensities are in good agreement with most of the reported values.

  12. Interaction studies and gamma-ray properties of some low-Z materials

    Directory of Open Access Journals (Sweden)

    Bhosale Rameshwar R.

    2016-01-01

    Full Text Available In present work we use NaI(Tl detector in narrow-beam good geometry set-up for the gamma ray attenuation studies of some low-Z materials. The parameters such as mass attenuation coefficients, effective atomic numbers and effective electron densities, atomic cross-sections, electronic cross-sections of materials for graphitic powder, polycarbonate, polyvinyl chloride, plaster of Paris, gypsum, and limestone were determined using gamma ray sources 57Co, 133Ba, 137Bs, 60Co, and 22Na at energies of 122, 356, 511, 662, 840, 1170, 1275, and 1330 keV. It was observed that the effective atomic numbers and effective electron densities initially decrease and tend to be almost constant as a function of gamma-ray energy. An attempt was done to check the availability of these low-Z materials at large scales and obtainable at low cost as gamma ray shielding materials. The investigated data are useful in electronic industry, plastic industry, building materials, and agriculture fields.

  13. Delayed Nickel Decay in Gamma Ray Bursts

    CERN Document Server

    McLaughlin, G C

    2002-01-01

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

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

    Science.gov (United States)

    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%.

  15. The future of gamma-ray astronomy

    CERN Document Server

    Knödlseder, Jürgen

    2016-01-01

    The field of gamma-ray astronomy has experienced impressive progress over the last decade. Thanks to the advent of a new generation of imaging air Cherenkov telescopes (H.E.S.S., MAGIC, VERITAS) and thanks to the launch of the Fermi-LAT satellite, several thousand gamma-ray sources are known today, revealing an unexpected ubiquity of particle acceleration processes in the Universe. Major scientific challenges are still ahead, such as the identification of the nature of Dark Matter, the discovery and understanding of the sources of cosmic rays, or the comprehension of the particle acceleration processes that are at work in the various objects. This paper presents some of the instruments and mission concepts that will address these challenges over the next decades.

  16. The future of gamma-ray astronomy

    Science.gov (United States)

    Knödlseder, Jürgen

    2016-06-01

    The field of gamma-ray astronomy has experienced impressive progress over the last decade. Thanks to the advent of a new generation of imaging air Cherenkov telescopes (H.E.S.S., MAGIC, VERITAS) and thanks to the launch of the Fermi-LAT satellite, several thousand gamma-ray sources are known today, revealing an unexpected ubiquity of particle acceleration processes in the Universe. Major scientific challenges are still ahead, such as the identification of the nature of Dark Matter, the discovery and understanding of the sources of cosmic rays, or the comprehension of the particle acceleration processes that are at work in the various objects. This paper presents some of the instruments and mission concepts that will address these challenges over the next decades. xml:lang="fr"

  17. The Future of Gamma Ray Astrophysics

    CERN Document Server

    CERN. Geneva

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-02-01

    The GAMMA-400 gamma-ray telescope is intended to measure the fluxes of gamma-rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. Such measurements concern the following scientific tasks: investigation of point sources of gamma-rays, studies of the energy spectra of Galactic and extragalactic diffuse emission, studies of gamma-ray bursts and gamma-ray emission from the Sun, as well as high precision measurements of spectra of high-energy electrons and positrons. Also the GAMMA- 400 instrument provides the possibility for protons and nuclei measurements up to knee. But the main goal for the GAMMA-400 mission is to perform a sensitive search for signatures of dark matter particles in high-energy gamma-ray emission. To fulfill these measurements the GAMMA-400 gamma-ray telescope possesses unique physical characteristics in comparison with previous and present experiments. The major advantage of the GAMMA-400 instrument is excellent angular and energy resolution for gamma-rays above 10 GeV. The GAMMA-400 experiment will be installed onboard of the Navigator space platform, manufactured by the NPO Lavochkin Association. The expected orbit will be a highly elliptical orbit (with apogee 300.000 km and perigee 500 km) with 7 days orbital period. An important profit of such an orbit is the fact that the full sky coverage will always be available for gamma ray astronomy.

  19. gamma. radiolysis of polyethylene grafted with sytrene. [Gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Mitsui, H.; Shimizu, Y.

    1981-06-01

    ..gamma.. radiolysis of polyethylene grafted with styrene of 0-76 wt % was carried out at 30-100/sup 0/C in vacuo with a dose rate of 6.35 x 10/sup 5/ rad/hr. The formation of hydrogen and trans-vinylene unsaturation decreased as the content of styrene unit in polymer increased and the rate of formulation was described by zero-order formation kinetics with respect to each concentration combined with first-order disappearance. The gel fraction changed with the content of styrene unit according to irradation time and temperature. The gel data were evaluated by using the Charlesby-Pinner equation. Kinetic analysis showed that in ..gamma.. radiolysis of polyethylene grafted with styrene the formation of hydrogen is somewhat retarded, the crosslinking and main chain scission are accelerated, and the disappearance of hydrogen and formation and disappearance of trans-vinylene unsaturation are almost entirely unaffected. On the basis of these results the reactions induced by ..gamma.. rays in graft polymer were discussed in connection with the reaction mechanisms of the ..gamma.. radiolyses of polyethylene and polystyrene.

  20. X-Ray and Gamma-Ray Radiation Detector

    DEFF Research Database (Denmark)

    2015-01-01

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

  1. Material recognition using fission gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Viesti, G. [Dipartimento di Fisica dell' Universita di Padova, Via Marzolo 8, I-35131 Padova (Italy); INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy)], E-mail: giuseppe.viesti@pd.infn.it; Sajo-Bohus, L. [Universidad Simon-Bolivar, Laboratorio Fisica Nuclear, Apartado 8900, 1080 A. Caracas (Venezuela, Bolivarian Republic of); Fabris, D. [INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Lunardon, M.; Moretto, S. [Dipartimento di Fisica dell' Universita di Padova, Via Marzolo 8, I-35131 Padova (Italy); INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy); Nebbia, G.; Pesente, S. [INFN Sezione di Padova, Via Marzolo 8, I-35131 Padova (Italy)

    2009-07-21

    Material recognition is studied by measuring the transmission spectrum of {sup 252}Cf fission gamma rays in the energy range E{sub {gamma}}=0.1-5.5 MeV for 0.1-MeV-wide energy bins through a number of elementary samples. Each transmitted spectrum is compared with a library of reference spectra for different elements providing the possibility of material identification. In case of elemental samples with known thickness, this procedure allows the identification of the sample Z with uncertainty typically lower than 3 Z-units over a wide range of elements. Applications to composite materials are also reported.

  2. Gamma ray bursts observed with WATCH‐EURECA

    DEFF Research Database (Denmark)

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

    1994-01-01

    The WATCH wide field x‐ray monitor has the capability of independently locating bright Gamma Ray Bursts to 1° accuracy. We report the preliminary positions of 12 Gamma Ray Bursts observed with the WATCH monitor flown on the ES spacecraft EURECA during its 11 month mission. Also the recurrence...... of the Soft Gamma Repeater SGR 1900+14 in 1992 is verified....

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

    Science.gov (United States)

    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.

  4. NEW GAMMA RAYS FROM DECAY OF 189W

    Institute of Scientific and Technical Information of China (English)

    杨维凡; 赵之正; 等

    1995-01-01

    Radioactivities of 189W are produced through an 192Os(n,α189W reaction.Gamma ray spectroscopy from chemically separated tungsten sources using HPGe detector has revealed the presence of 22 gamma rays assigned to the decay of 189W,of them,18 gamma rays are new ones unreported until now.

  5. BL Lacertae Objects and the Extragalactic Gamma-Ray Background

    CERN Document Server

    Li, Fan

    2011-01-01

    A tight correlation between gamma-ray and radio emission is found for a sample of BL Lacertae (BL Lac) objects detected by Fermi Gamma-ray Space Telescope (Fermi) and the Energetic Gamma-Ray Experiment Telescope (EGRET). The gamma-ray emission of BL Lac objects exhibits strong variability, and the detection rate of gamma-ray BL Lac objects is low, which may be related to the gamma-ray duty cycle of BL Lac objects. We estimate the gamma-ray duty cycle ~ 0.11, for BL Lac objects detected by EGRET and Fermi. Using the empirical relation of gamma-ray emission with radio emission and the estimated gamma-ray duty cycle, we derive the gamma-ray luminosity function (LF) of BL Lac objects from their radio LF. Our derived gamma-ray LF of BL Lac objects can almost reproduce that calculated with the recently released Fermi bright active galactic nuclei (AGN) sample. We find that about 45% of the extragalactic diffuse gamma-ray background (EGRB) is contributed by BL Lac objects. Combining the estimate of the quasar contri...

  6. Study of the action of {sup 60}Co gamma radiation on Salmonella poona, Escherichia coli and Alicyclobacillus acidoterrestris in mango pulp;Estudo da acao da radiacao gama de {sup 60}Co sobre Salmonella poona, Escherichia coli and Alicyclobacillus acidoterrestris em polpa de manga congelada

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Marco Antonio dos Santos

    2009-07-01

    The application of non-thermal treatments has proven effective in inhibiting bacteria such as Salmonella and Escherichia coli. Mango is a fruit of national consumption with a great exportation potential. Meanwhile, outbreaks of foodborne disease related to mango consumption caused mistrust on the degree of food security offered by the product. The objective of this work was to establish the radioresistance of bacteria Escherichia coli, Salmonella Poona and Alicyclobacillus acidoterrestris on the mango pulp by the calculation of the D10 values and to know the radiation effect on the sensory characteristics of the fruit pulp. The microbiological profile of frozen mango pulp available at the local market was also established using conventional methods of plating and Most Probable Number (MPN). The pulps experimentally inoculated with the bacteria listed above were irradiated with doses of 0, 1, 2, 3, 4 and 5 kGy in a {sup 60}Co source. The sensory analysis was performed using a dose of 5 kGy, using the triangular test and the test of acceptance with hedonic scale. The results of this study show that the quality of mango pulp sell in the local market is not satisfactory in accordance with the standards established by the Brazilian law and the literature, showing the need of using other tools to achieve acceptable levels of quality. The D10 values obtained are in the range of 1.01 and 1.09 kGy for E. coli ATCC 8739, 0.60 and 0.98 kGy for S. poona and 0.72 and 0.88 kGy for A. acidoterrestris respectively. The triangular test showed that a 5 kGy radiation dose changed the sensory characteristics of mango pulp. Nevertheless, sensory analysis of a food product prepared with the irradiated pulp obtained good acceptance in the attributes of global appearance, flavor and aroma. (author)

  7. Study of the action of {sup 60}Co gamma radiation on Salmonella poona, Escherichia coli and Alicyclobacillus acidoterrestris in mango pulp; Estudo da acao da radiacao gama de {sup 60}Co sobre Salmonella poona, Escherichia coli e Alicyclobacillus acidoterrestris em polpa de manga congelada

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Marco Antonio dos Santos

    2009-07-01

    The application of non-thermal treatments has proven effective in inhibiting bacteria such as Salmonella and Escherichia coli. Mango is a fruit of national consumption with a great exportation potential. Meanwhile, outbreaks of food borne disease related to mango consumption caused mistrust on the degree of food security offered by the product. The objective of this work was to establish the radioresistance of bacteria Escherichia coli, Salmonella Poona and Alicyclobacillus acidoterrestris on the mango pulp by the calculation of the D10 values and to know the radiation effect on the sensory characteristics of the fruit pulp. The microbiological profile of frozen mango pulp available at the local market was also established using conventional methods of plating and Most Probable Number (MPN). The pulps experimentally inoculated with the bacteria listed above were irradiated with doses of 0, 1, 2, 3, 4 and 5kGy in a {sup 60}Co source. The sensory analysis was performed using a dose of 5 kGy, using the triangular test and the test of acceptance with hedonic scale. The results of this study show that the quality of mango pulp sell in the local market is not satisfactory in accordance with the standards established by the Brazilian law and the literature, showing the need of using other tools to achieve acceptable levels of quality. The D10 values obtained are in the range of 1.01 and 1.09kGy for E. coli ATCC 8739, 0.60 and 0.98kGy for S. poona and 0.72 e 0.88kGy for A. acidoterrestris respectively. The triangular test showed that a 5kGy radiation dose changed the sensory characteristics of mango pulp. Nevertheless, sensory analysis of a food product prepared with the irradiated pulp obtained good acceptance in the attributes of global appearance, flavor and aroma. (author)

  8. Inactivation effect of 60Co gamma ray on cysticerci of Taenia solium in pork%60Coγ射线对猪肉中囊尾蚴的辐照杀灭效应

    Institute of Scientific and Technical Information of China (English)

    钟凯; 高翔; 计融

    2011-01-01

    Objective revealing the relationship between irradiation dose and inactivation ratio for eysticerei of Taenia solium in pork, determining the minimal dose for totally killing cysticerci and providing scientific evidence for setting up relevant hygienic standards of radiation. Methods After Taenia solium infected pork being treated with different irradiation doses; cysticerci were separated and incubated in fresh swine bile. The adjusted inactivation ratio was calculated according to the survival rate. Results There was a linear correlation between irradiation dose and adjusted inactivation ratio, the D10 value was about 3.8 kGy, and a totally killing could be achieved by 4.5 kGy irradiation. Conclusion Irradiation at a dose of 4.5 kGy could be applied as the maximum dose to inactivate cysticerci of Taenia solium in pork processing.%目的 揭示猪肉中囊尾蚴灭活率与辐照剂量的相关关系及最小杀灭剂量,为制定相应辐照卫生规范提供科学依据.方法 以不同剂量Co γ射线处理感染囊尾蚴的猪肉,并用新鲜猪胆汁孵化剥离出的囊尾蚴,根据成活率计算校正灭活率.结果 辐照剂量与校正灭活率具有线性相关,D值约为3.8 kGy,4.5 kGy可完全杀灭囊尾蚴.结论 4.5 kGy γ射线对猪肉中囊尾蚴有很好的杀灭效果.

  9. Critical Test Of Gamma Ray Burst Theories

    CERN Document Server

    Dado, Shlomo

    2016-01-01

    Long and precise follow-up measurements of the X-ray afterglow (AG) of very intense gamma ray bursts (GRBs) provide a critical test of GRB afterglow theories. Here we show that the power-law decline with time of X-ray AG of GRB 130427A, the longest measured X-ray AG of an intense GRB with the Swift, Chandra and XMM Newton satellites, and of all other well measured late-time X-ray afterglow of intense GRBs, is that predicted by the cannonball (CB) model of GRBs from their measured spectral index, while it disagrees with that predicted by the widely accepted fireball (FB) models of GRBs.

  10. Evaluation of radiological data of some saturated fatty acids using gamma ray spectrometry

    Science.gov (United States)

    Kore, Prashant S.; Pawar, Pravina P.; Palani Selvam, T.

    2016-02-01

    Radiological parameters such as mass attenuation coefficients (μm), total attenuation cross section (σtot), molar extinction coefficient (ε), mass energy absorption coefficient (μen/ρ) and effective electronic cross section (σt, el) of saturated fatty acids, namely butyric acid (C4H8O2), caproic acid (C6H12O2), enanthic acid (C7H14O2), caprylic acid (C8H16O2), pelargonic acid (C9H18O2) and valeric acid (C5H10O2) were measured using NaI(Tl)-based gamma spectrometry. Radioactive sources used in the study are 57Co, 133Ba, 137Cs, 54Mn, 60Co and 22Na. Gamma ray transmission method in a narrow beam good geometry set up was used in the study. The measured data were compared against Win-XCOM-based data. The agreement is within 1%.

  11. An Experimental Study on the Effect of 60Co γ Rays Irradiation on Guinea Pig Cochlear Nucleus%豚鼠耳颞部60Coγ射线照射对耳蜗核影响的实验研究

    Institute of Scientific and Technical Information of China (English)

    钟华林; 唐安洲; 谢利红

    2012-01-01

    目的 探讨60Coγ射线照射对豚鼠耳蜗核神经元的影响.方法 48只豚鼠随机分为对照组(8只)和实验组(40只),实验组豚鼠于右耳颞部做一次性40 Gy 60Coγ射线照射后的1、4、7、14、30 d行听性脑干反应(auditory brainstem response,ABR)测试,然后处死,行耳蜗核石蜡切片HE染色及免疫组织化学染色,观察细胞形态及半胱氨酸天冬氨酸蛋白酶3(Caspase 3).对照组不予 60Coγ射线照射,行ABR测试后行耳蜗核HE染色,方法同实验组.结果 对照组ABR反应阈为29.17±1.95 dB SPL,实验组在接受60Coγ射线照射后1、4、7、14、30 d ABR阈值升高,分别为31.88±2.59、35.00±3.17、35.83±2.04、39.17±2.05、41.67±2.58 dB SPL,照射后4、7、14、30 d ABR反应阈与对照组比较差异有统计学意义(P<0.05);实验组各时间点ABR波I、II、III潜伏期及I-II、II-III、I-III波间期延长,与对照组比较差异有统计学意义(P<0.05).结论 60Coγ射线照射可导致耳蜗核损伤;Caspase3表达上调可能与耳蜗核神经元射线损伤有关.%Objective To study the effects of 60Coyrays irradiation on cochicar nucleus neurons. Methods Forty eight guinea pigs were randomly divided into control group(8 guinea pigs)and experimental group(40 guinea pigs). The experimental group animals were tested with the auditory brainstcm response at 1 , 4, 7, 14 and 30 days after irradiation of 40 Gy ,thcn the guinea pigs were sacrificed. All cochlcar nuclei tissues were made into paraffin sections. Sections were stained with hacmatoxylin and cosin and Caspasc 3 immunohistochemistry for light microscopic examination. Results ABR threshold in the control group was 29. 17 ± 1. 95 dB SPL. In experimental group, ABR thresholds were 31.88 ± 2. 59 dB SPL ,35.00 ± 3. 17dB SPL ,35.83 ± 2. 04 dB SPL, 39. 17 ± 2. 05 dB SPL, 41. 67 ±2. 58 dB SPL after 60Co irradiation 1 , 4, 7,14, 30 days groups,respectively. The differences of ABR threshold were statistically significant

  12. News from Cosmic Gamma-ray Line Observations

    CERN Document Server

    Diehl, Roland

    2016-01-01

    The measurement of gamma rays at MeV energies from cosmic radioactivities is one of the key tools for nuclear astrophysics, in its study of nuclear reactions and how they shape objects such as massive stars and supernova explosions. Additionally, the unique gamma-ray signature from the annihilation of positrons falls into this same astronomical window, and positrons are often produced from radioactive beta decays. Nuclear gamma-ray telescopes face instrumental challenges from penetrating gamma rays and cosmic-ray induced backgrounds. But the astrophysical benefits of such efforts are underlined by the discoveries of nuclear gamma~rays from the brightest of the expected sources. In recent years, both thermonuclear and core-collapse supernova radioactivity gamma~rays have been measured in spectral detail, and complement conventional supernova observations with measurements of origins in deep supernova interiors, from the decay of $^{56}$Ni, $^{56}$Co, and $^{44}$Ti. The diffuse afterglow in gamma rays of radioa...

  13. On the X-Ray emission of Gamma Ray Bursts

    CERN Document Server

    Dado, Shlomo; De Rújula, Alvaro

    2007-01-01

    Recent data gathered and triggered by the SWIFT satellite have greatly improved our knowledge of long-duration gamma ray bursts (GRBs) and X-ray flashes (XRFs). This is particularly the case for the X-ray data at all times. We show that the entire X-ray observations are in excellent agreement with the predictions of the `cannonball' model of GRBs and XRFs, which are based on simple physics and were published long before the launch of SWIFT. Two mechanisms underlie these predictions: inverse Compton scattering and synchrotron radiation, generally dominant at early and late times, respectively. The former mechanism provides a unified description of the gamma-ray peaks, X-ray flares and even the optical `humps' seen in some favourable cases; i.e. their very different durations, fluxes and peak-times are related precisely as predicted. The observed smooth or bumpy fast decay of the X-ray light curve is correctly described case-by-case, in minute detail. The `canonical' X-ray plateau, as well as the subsequent gra...

  14. Gamma-Ray Library and Uncertainty Analysis: Passively Emitted Gamma Rays Used in Safeguards Technology

    Energy Technology Data Exchange (ETDEWEB)

    Parker, W

    2009-09-18

    Non-destructive gamma-ray analysis is a fundamental part of nuclear safeguards, including nuclear energy safeguards technology. Developing safeguards capabilities for nuclear energy will certainly benefit from the advanced use of gamma-ray spectroscopy as well as the ability to model various reactor scenarios. There is currently a wide variety of nuclear data that could be used in computer modeling and gamma-ray spectroscopy analysis. The data can be discrepant (with varying uncertainties), and it may difficult for a modeler or software developer to determine the best nuclear data set for a particular situation. To use gamma-ray spectroscopy to determine the relative isotopic composition of nuclear materials, the gamma-ray energies and the branching ratios or intensities of the gamma-rays emitted from the nuclides in the material must be well known. A variety of computer simulation codes will be used during the development of the nuclear energy safeguards, and, to compare the results of various codes, it will be essential to have all the {gamma}-ray libraries agree. Assessing our nuclear data needs allows us to create a prioritized list of desired measurements, and provides uncertainties for energies and especially for branching intensities. Of interest are actinides, fission products, and activation products, and most particularly mixtures of all of these radioactive isotopes, including mixtures of actinides and other products. Recent work includes the development of new detectors with increased energy resolution, and studies of gamma-rays and their lines used in simulation codes. Because new detectors are being developed, there is an increased need for well known nuclear data for radioactive isotopes of some elements. Safeguards technology should take advantage of all types of gamma-ray detectors, including new super cooled detectors, germanium detectors and cadmium zinc telluride detectors. Mixed isotopes, particularly mixed actinides found in nuclear reactor

  15. Gamma-ray irradiation tests of CMOS sensors used in imaging techniques

    Directory of Open Access Journals (Sweden)

    Cappello Salvatore G.

    2014-01-01

    Full Text Available Technologically-enhanced electronic image sensors are used in various fields as diagnostic techniques in medicine or space applications. In the latter case the devices can be exposed to intense radiation fluxes over time which may impair the functioning of the same equipment. In this paper we report the results of gamma-ray irradiation tests on CMOS image sensors simulating the space radiation over a long time period. Gamma-ray irradiation tests were carried out by means of IGS-3 gamma irradiation facility of Palermo University, based on 60Co sources with different activities. To reduce the dose rate and realize a narrow gamma-ray beam, a lead-collimation system was purposely built. It permits to have dose rate values less than 10 mGy/s and to irradiate CMOS Image Sensors during operation. The total ionizing dose to CMOS image sensors was monitored in-situ, during irradiation, up to 1000 Gy and images were acquired every 25 Gy. At the end of the tests, the sensors continued to operate despite a background noise and some pixels were completely saturated. These effects, however, involve isolated pixels and therefore, should not affect the image quality.

  16. TeV gamma-ray astronomy

    Institute of Scientific and Technical Information of China (English)

    Wei Cui

    2009-01-01

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

  17. Are gamma-ray bursts cosmological?

    CERN Document Server

    Horvath, I

    2015-01-01

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

  18. Stellar Photon Archaeology with Gamma-Rays

    Science.gov (United States)

    Stecker, Floyd W.

    2009-01-01

    Ongoing deep surveys of galaxy luminosity distribution functions, spectral energy distributions and backwards evolution models of star formation rates can be used to calculate the past history of intergalactic photon densities and, from them, the present and past optical depth of the Universe to gamma-rays from pair production interactions with these photons. The energy-redshift dependence of the optical depth of the Universe to gamma-rays has become known as the Fazio-Stecker relation (Fazio & Stecker 1970). Stecker, Malkan & Scully have calculated the densities of intergalactic background light (IBL) photons of energies from 0.03 eV to the Lyman limit at 13.6 eV and for 0$ photon densities in the past, i.e., the "archaeo-IBL.", and therefore allow a better measure of the past history of the total star formation rate, including that from galaxies too faint to be observed.

  19. Physics of gamma-ray bursts

    Science.gov (United States)

    Lamb, D. Q.

    1984-01-01

    Attention is given to the accumulating evidence for the view that gamma-ray bursts come from strongly magnetic neutron stars, discussing the physical properties of the emission region and the radiation processes expected in strong magnetic fields, and emphasizing that the observed burst spectra require that the emission region be optically thin. This entails that the energy of the emitting plasma and/or the plasma itself be continuously replenished during a burst, and that the cooling time scale of the emitting plasma be much shorter than the observed duration of the bursts. This characteristic of the cooling time scale implies that the burst intensity and spectrum can vary on extremely short time scales, and that the burst duration must have a separate explanation. It is emphasized that synchrotron emission is favored as the gamma-ray production mechanism; it is the only mechanism capable of satisfying the optical thinness constraint while producing the observed luminosity.

  20. TeV Gamma Ray Astronomy

    CERN Document Server

    Cui, Wei

    2009-01-01

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

  1. Real time gamma-ray signature identifier

    Science.gov (United States)

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

    2012-05-15

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

  2. Do Gamma-Ray Burst Sources Repeat?

    OpenAIRE

    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...

  3. GAMMA-RAY BURSTS, NEW COSMOLOGICAL BEACONS

    Directory of Open Access Journals (Sweden)

    V. Avila-Reese

    2009-01-01

    Full Text Available Long Gamma-Ray Bursts (GRBs are the brightest electromagnetic explosions in the Universe, associated to the death of massive stars. As such, GRBs are potential tracers of the evolution of the cosmic massive star formation, metallicity, and Initial Mass Function. GRBs also proved to be appealing cosmological distance indicators. This opens a unique opportunity to constrain the cosmic expansion history up to redshifts 5-6. A brief review on both subjects is presented here.

  4. Gamma ray tracking with the AGATA demonstrator

    Energy Technology Data Exchange (ETDEWEB)

    Birkenbach, Benedikt; Hess, Herbert; Lewandowski, Lars; Reiter, Peter; Steinbach, Tim; Schneiders, David; Vogt, Andreas [IKP, Universitaet zu Koeln (Germany); Collaboration: AGATA-Collaboration

    2014-07-01

    The performance of the AGATA demonstrator will be discussed based on data taken from a multi-nucleon transfer experiment at the AGATA PRISMA setup at LNL (INFN, Italy). A primary {sup 136}Xe beam of 1 GeV hitting a {sup 238}U target was used to produce a multitude of nuclei in the vicinity of {sup 136}Xe and corresponding reaction partners in the actinide region. The obtained results for in-beam gamma-ray spectroscopy allow for a critical assessment of the novel gamma ray tracking technique and comparison with standard procedure. High resolution spectroscopy of both reaction products after multi-nucleon transfer reaction in the presence of a high background from excited fission fragments is based on pulse-shape analysis (PSA) and gamma-ray tracking (GRT). The quality of the position information is crucial for the final energy resolution after Doppler correction. The impact of the calculated PSA libraries and the initial detector characterization for the PSA and GRT are summarized. Details of the achieved position and energy resolution, peak-to-background optimization are presented and illustrated with results from the neutron-transfer products in Xe and U-isotopes.

  5. Gamma Ray Bursts Cook Book I: Formulation

    CERN Document Server

    Ziaeepour, Houri

    2008-01-01

    Since the suggestion of relativistic shocks as the origin of gamma-ray bursts (GRBs) in early 90's, the mathematical formulation of this process has stayed at phenomenological level. One of the reasons for the slow development of theoretical works in this domain has been the simple power-law behaviour of the afterglows hours or days after the prompt gamma-ray emission. Nowadays with the launch of the Swift satellite, gamma-ray bursts can be observed in multi-wavelength from a few tens of seconds after trigger onward. These observations have leaded to the discovery of features unexplainable by the simple formulation of the shocks and emission processes used up to now. But "devil is in details" and some of these features may be explained with a more detailed formulation of phenomena and without adhoc addition of new processes. Such a formulation is the goal of this work. We present a consistent formulation of the collision between two spherical relativistic shells. The model can be applied to both internal and ...

  6. Bremsstrahlung gamma rays from light Dark Matter

    CERN Document Server

    Cirelli, Marco; Zaharijas, Gabrijela

    2013-01-01

    We discuss the often-neglected role of bremsstrahlung processes on the interstellar gas in computing indirect signatures of Dark Matter (DM) annihilation in the Galaxy, particularly for light DM candidates in the phenomenologically interesting O(10) GeV mass range. Especially from directions close to the Galactic Plane, the expected gamma-ray spectrum is altered via two effects: directly, by the photons emitted in the bremsstrahlung process on the interstellar gas by energetic electrons which are among the DM annihilation byproducts; indirectly, by the modification of the same electron spectrum, due to the additional energy loss process in the diffusion-loss equation (e.g. the resulting inverse Compton emission is altered). We quantify the importance of the bremsstrahlung emission in the GeV energy range, showing that it is the dominant component of the gamma-ray spectrum for some cases. We also find that, in regions in which bremsstrahlung dominates energy losses, the related gamma-ray emission is only moder...

  7. RADIO FLARES FROM GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Kopač, D.; Mundell, C. G.; Kobayashi, S.; Virgili, F. J. [Astrophysics Research Institute, Liverpool John Moores University, Liverpool, L3 5RF (United Kingdom); Harrison, R. [Department of Astrophysics, School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel); Japelj, J.; Gomboc, A. [Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia); Guidorzi, C. [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, I-44122 Ferrara (Italy); Melandri, A., E-mail: D.Kopac@ljmu.ac.uk [INAF/Brera Astronomical Observatory, via Bianchi 46, I-23807, Merate (Italy)

    2015-06-20

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

  8. Gamma-Ray Pulsars Models and Predictions

    CERN Document Server

    Harding, A K

    2001-01-01

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

  9. Afterglow Radiation from Gamma Ray Bursts

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Hadronic Gamma Rays from Supernova Remnants

    CERN Document Server

    Moskalenko, I V; Malkov, M A; Diamond, P H

    2007-01-01

    A gas cloud near a supernova remnant (SNR) provides a target for pp-collisions leading to subsequent gamma-ray emission through neutral pion decay. The assumption of a power-law ambient spectrum of accelerated particles with index near -2 is usually built into models predicting the spectra of very-high energy (VHE) gamma-ray emission from SNRs. However, if the gas cloud is located at some distance from the SNR shock, this assumption is not necessarily correct. In this case, the particles which interact with the cloud are those leaking from the shock and their spectrum is approximately monoenergetic with the injection energy gradually decreasing as the SNR ages. The gamma-ray spectrum resulting from particle interactions with the gas cloud will be flatter than expected, with the cutoff defined by the pion momentum distribution in the laboratory frame. We evaluate the flux of particles escaping from a SNR shock and apply the results to the VHE diffuse emission detected by the HESS at the Galactic centre.

  11. Highlights of GeV Gamma-Ray Astronomy

    Science.gov (United States)

    Thompson, David J.

    2010-01-01

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

  12. Measurement of fast neutrons and secondary gamma rays in graphite

    Energy Technology Data Exchange (ETDEWEB)

    Makarious, A.S.; El-Asyd Abdo, A.; Kansouh, W.A. [Atomic Energy Authority, Cairo (Egypt). Nuclear Research Centre; Bashter, I.I. [Zagazig Univ. (Egypt). Faculty of Science

    1996-05-01

    The spatial fluxes and energy distributions of fast neutrons, total gamma rays and secondary gamma rays transmitted through different thicknesses of graphite have been measured. The graphite samples were arranged in front of one of the horizontal channels of the ET-RR-1 reactor. Gamma ray measurements were carried out for bare, cadmium filtered and boron carbide filtered reactor beams. A fast neutron and gamma ray spectrometer with a stilbene crystal was used to measure the spectrum of fast neutrons and gamma rays. Pulse shape discrimination using the zero cross over technique was used to distinguish the proton pulses from the electron pulses. The total fast neutrons macroscopic cross section and the linear attenuation coefficient for gamma rays were derived both for the whole energy range and at different energies. The obtained values were used to calculate the relaxation lengths for fast neutrons and gamma rays. (Author).

  13. 60Co-γ射线辐照处理对天竺葵、观赏椒种子发芽率及幼苗的影响%The Effect of 60Co-γRay Radiation on the Germination Rate of Seed and Growth of Seeding of Pelargonium and Capsioum annuum L.

    Institute of Scientific and Technical Information of China (English)

    强继业; 夏更寿; 王海棠; 尹瑞新; 王元军

    2005-01-01

    60Co-γ射线辐照处理天竺葵、观赏椒种子,观察其发芽率和幼苗生长情况.结果表明:γ射线辐射对这2种观赏植物的发芽率和幼苗生长发育具有不同的影响.对天竺葵的发芽率有促进作用,但抑制幼苗生长;对观赏椒发芽率作用不显著,对幼苗前期生长有抑制作用.

  14. Determination of gamma ray attenuation coefficients of Al–4% Cu/B4C metal matrix composites at 662, 1173 and 1332 keV

    Indian Academy of Sciences (India)

    I Akkurt; K Günoğlu; A Çalik; M S Karakas

    2014-08-01

    Gamma ray attenuation coefficients of metal matrix composites have been investigated. For this purpose, the linear attenuation coefficients of composites containing boron carbide (B4C) at different rates have been measured using a gamma spectrometer that contains a NaI(Tl) detector and MCA at 662, 1173 and 1332 keV, which are obtained from 137Cs and 60Co sources. The measured results were compared with the calculation obtained using computer code of XCOM for 1 keV–1 GeV gamma energies.

  15. Measurements of neutron distribution in neutrons-gamma-rays mixed field using imaging plate for neutron capture therapy.

    Science.gov (United States)

    Tanaka, Kenichi; Endo, Satoru; Hoshi, Masaharu

    2010-01-01

    The imaging plate (IP) technique is tried to be used as a handy method to measure the spatial neutron distribution via the (157)Gd(n,gamma)(158)Gd reaction for neutron capture therapy (NCT). For this purpose, IP is set in a water phantom and irradiated in a mixed field of neutrons and gamma-rays. The Hiroshima University Radiobiological Research Accelerator is utilized for this experiment. The neutrons are moderated with 20-cm-thick D(2)O to obtain suitable neutron field for NCT. The signal for IP doped with Gd as a neutron-response enhancer is subtracted with its contribution by gamma-rays, which was estimated using IP without Gd. The gamma-ray response of Gd-doped IP to non-Gd IP is set at 1.34, the value measured for (60)Co gamma-rays, in estimating the gamma-ray contribution to Gd-doped IP signal. Then measured distribution of the (157)Gd(n,gamma)(158)Gd reaction rate agrees within 10% with the calculated value based on the method that has already been validated for its reproducibility of Au activation. However, the evaluated distribution of the (157)Gd(n,gamma)(158)Gd reaction rate is so sensitive to gamma-ray energy, e.g. the discrepancy of the (157)Gd(n,gamma)(158)Gd reaction rate between measurement and calculation becomes 30% for the photon energy change from 33keV to 1.253MeV.

  16. Spectra of {gamma} rays feeding superdeformed bands

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-08-01

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

  17. Gamma-ray Production in Supernova Remnants

    CERN Document Server

    Baring, M G

    1997-01-01

    Supernova remnants are widely believed to be a principal source of galactic cosmic rays, produced by diffusive shock acceleration in the environs of the remnant's expanding shock. This review discusses recent modelling of how such energetic particles can produce gamma-rays via interactions with the remnants' ambient interstellar medium, specifically via neutral pion decay, bremsstrahlung and inverse Compton emission. Predictions that relate to the handful of associations between EGRET unidentified sources and known radio/optical/X-ray emitting remnants are summarized. The cessation of acceleration above 1 TeV - 10 TeV energies in young shell-type remnants is critical to model consistency with Whipple's TeV upper limits; these observations provide important diagnostics for theoretical models.

  18. GAMMA RAYS FROM STAR FORMATION IN CLUSTERS OF GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-20

    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.

  19. Relation between $\\gamma$-rays and emission lines for the $\\gamma$-ray loud blazars

    CERN Document Server

    Fan, J H

    2000-01-01

    The relation between the $\\gamma$-ray and the emission line luminosities for a sample of 36 $\\gamma$-ray loud blazars is investigated; an apparent correlation between them, $L_{\\gamma} \\propto L_{Line}^{0.69\\pm0.11}$, with a correlation coefficient $r=0.741$ and a chance probability of $p = 1.9\\times10^{-6}$, is found. It is found, however, that there is no intrinsic correlation between them: the apparent correlation is due to the redshift dependence in a flux-limited sample. Thus no evidence is found to support the argument that the up-scattered soft photons are from the broad emission lines. Our analysis does not conflict with the SSC model. The disk-jet symbiosis and radio/$\\gamma$-ray correlation found in the literature are also discussed. The radio/$\\gamma$-ray correlation may be an apparent correlation caused by the boosting effect since both bands are strongly beamed.

  20. Multiwavelength Studies of gamma-ray Binaries

    Science.gov (United States)

    Aragona, Christina

    2011-01-01

    High mass X-ray binaries (HMXBs) consist of an O or B star orbited by either a neutron star or a black hole. Of the 114 known Galactic HMXBs, a handful of these objects, dubbed gamma-ray binaries, have been observed to produce MeV-TeV emission. The very high energy emission can be produced either by accretion from the stellar wind onto a black hole or a collision between the stellar wind and a relativistic pulsar wind. Both these scenarios make gamma-ray binaries valuable nearby systems for studying the physics of shocks and jets. Currently, the nature of the compact object and the high energy production mechanism is unknown or unconfirmed in over half of these systems. My goal for this dissertation is to constrain the parameters describing two of these systems: LS 5039 and HD 259440. LS 5039 exhibits gamma-ray emission modulated with its orbital period. The system consists of an ON6.5V((f)) star and an unidentified compact companion. Using optical spectra from the CTIO 1.5m telescope, we found LS 5039 to have an orbital period of 3.90608 d and an eccentricity of 0.337. Spectra of the Halpha line observed with SOAR indicate a mass loss rate of ˜ 1.9x10 -8 M yr-1. Observations taken with ATCA at 13 cm, 6 cm, and 3 cm indicate radio fluxes between 10--40 mJy. The measurements show variability with time, indicating a source other than thermal emission from the stellar wind. HD 259440 is a B0pe star that was proposed as the optical counterpart to the gamma-ray source HESS J0632+057. Using optical spectra from the KPNO CF, KPNO 2.1m, and OHP telescopes, we find a best fit stellar effective temperature of 27500--30000 K, a log surface gravity of 3.75--4.0, a mass of 13.2--19.0 Msolar, and a radius of 6.0--9.6 Rsolar. By fitting the spectral energy distribution, we find a distance between 1.1--1.7 kpc. We do not detect any significant radial velocity shifts in our data, ruling out orbital periods shorter than one month. If HD 259440 is a binary, it is likely a long

  1. Gamma ray bursts and their afterglows

    Science.gov (United States)

    Nicuesa Guelbenzu, A.

    2017-03-01

    Gamma-Ray Bursts (GRBs) were among the greatest mysteries in modern astrophysics. They were first observed 50 years ago but it took three decades before optical counterparts could be found and the underlying physical phenomena studied in detail. GRB research represents currently one of the most rapidly growing areas in extragalactic astronomy. This is due in large part to the numerous connections that GRBs have with other disciplines like cosmology, supernovae, stellar evolution, nuclear physics, astroparticle and gravitational wave astronomy. Therefore, their study is of great importance to understand various astrophysical phenomena such as the formation of the first stars, the chemical evolution and the expansion of the Universe. Since gamma radiation can travel along cosmological distances without being affected by any possible intervening absorption, GRBs can be detected from the most distant universe, reaching redshifts up to z = 10 or more.

  2. Description of morphologic characters in avocado trees (Persea americana. Mill) var. Hass, submitted to gamma radiation of {sup 60} Co; Descripcion de caracteres morfologicos en arboles de aguacate (Persea americana. Mill) var. Hass, sometidos a radiacion gama de {sup 60} Co

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval R, L

    2004-07-01

    It was carried out the characterization of 77 trees of avocado ''Hass'' subjected to gamma radiation of Co{sup 60}, in doses of 0, 5, 10,15, 20 and 25 Gy based on previous studies of radiosensitivity with ends of improvement located in the experimental center ''La Labor'' belonging to the foundation Salvador Sanchez Colin. CICTAMEX. S C. in Temascaltepec, Mexico. It was carried out the morphological characterization of this variety according to the nomenclature settled down by the International Office of Genetic Resources (IBPGRI), registering 27 variables for the description of the tree, 33 for description of the fruit and 14 for the characterization of the seed. Regarding the architectural characterization 10 variables were evaluated. Using gamma radiation of Co{sup 60} in the doses of 15 and 20 Gy it was detected a reduction of 22% in the portage of the tree, likewise had reduction the diameter of the trunk and of the foliage. It was found that the reduction in the behavior of the tree induces to a bigger variation of the form of the same one, in the distribution of the branches in the form of the fruit and in the form of the seed you Also detects a remarkable increment in the productivity of some hoist irradiated regarding the architecture of the tree one observes that the angle of inclination of the branches increase when being increased the radiation dose and that the longitude of the annual section of growth decreased significantly in the doses of 20 and 25 Gy. One observes a significant Increment in the I number of buds prolepticos in those hoist irradiated in the I finish mbdulo of rhythmic growth. Io that indicates a change substantial in the I inhabit of growth With the purpose of determining if the changes in morphology and architecture of the tree corresponded with the modification at level meristematico, they were carried out observations to the court microscope of having knitted apical vegetative meristematico

  3. SAS-2 galactic gamma ray results. 2. Localized sources

    Science.gov (United States)

    Hartman, R. C.; Fichtel, C. E.; Kniffen, D. A.; Lamb, R. C.; Thompson, D. J.; Bignami, G. F.; Oegelman, H.; Oezel, M. E.; Tuemer, T.

    1976-01-01

    Gamma-ray emission was detected from the radio pulsars PSR1818-04 and PSR1747-46, in addition to the previously reported gamma-ray emission from the Crab and Vela pulsars. Since the Crab pulsar is the only one observed in the optical and X-ray bands, these gamma-ray observations suggest a uniquely gamma-ray phenomenon occurring in a fraction of the radio pulsars. Using distance estimates it is found that PSR1818-04 has a gamma-ray luminosity comparable to that of the Crab pulsar, while the luminosities of PSR1747-46 and the Vela pulsar are approximately an order of magnitude lower. This survey of SAS-2 data for pulsar correlations has also yielded upper limits to gamma-ray luminosity for 71 other radio pulsars.

  4. 60Co-γ射线照射大鼠损伤作用中硫辛酸对谷胱甘肽的调节与再生%Modulation of lipoic acid and regeneration of glutathion in rats injured by radiation with 60Coray

    Institute of Scientific and Technical Information of China (English)

    赵康涛; 海春旭; 梁欣; 张晓迪; 秦绪军; 刘瑞; 陈宏莉; 谷小刚

    2003-01-01

    目的: 以60Co-γ射线照射大鼠损伤为模型,研究硫辛酸对大鼠谷胱甘肽(glutathione, GSH)的调节和再生作用. 方法: 二级SD大鼠40只,雌雄各半,随机分为4组,为阴性对照组、阳性对照组、低剂量组(硫辛酸0.2 g*L-1),高剂量组(硫辛酸0.4 g*L-1),60Co-γ射线照射剂量为4 Gy. 对阳性组、低剂量组、高剂量组动物进行照射后,低剂量组和高剂量组动物分别给予硫辛酸油溶液灌胃(5 mL*kg-1). 阴性组和阳性组分别给予处理精炼油灌胃作为对照;连续灌胃给药2 d后断头处死,收集全血静置、析出血清,用荧光分光法及分光光度法测定GSH,MDA和谷胱甘肽过氧化物酶(glutathione peroxidase, GPx)等指标. 结果: 辐射损伤引起还原型谷胱甘肽含量的降低而氧化型谷胱甘肽(oxidized glutathione, GSSG)的含量增高(P<0.05);补充了硫辛酸能增加还原型谷胱甘肽的含量,且随着给药剂量的增加而升高(P<0.05),GSSG则呈相反趋势;硫辛酸能降低辐射损伤造成的GPx的活性的应激性增高(P<0.05). 结论: 硫辛酸对辐射损伤造成的氧化损伤具有保护作用,并能调节抗氧化剂GSH的含量,提高机体的抗氧化能力.

  5. Evaluating the effect of gamma radiation ({sup 60}Co) on protein arcelin and its influence in the resistance of Zabrotes subfasciatus (Boh., 1833) (Coleoptera: Bruchidae); Avaliacao do efeito da radiacao gama ({sup 60}Co) sobre a proteina arcelina e sua influencia na resistencia a Zabrotes subsfasciatus (Boh., 1833) (Coleoptera: Bruchidae)

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Valeria Wanderley

    1998-07-01

    The objective of this research was to evaluate the effects of different gamma doses of Cobalt-60 on arcelin protein in the manifestation of resistance to Zabrotes subfasciatus (Boh., 1833). Seeds of four lines of Phaseolus vulgaris carriers of arcelin protein (Arcelin-1, Arcelin-2, Arcelin-3 and Arcelin-4) and a cultivar without this protein were used as control (IAC-Carioca Akyta) obtained from the Instituto Agronomico do Estado de Sao Paulo - Nucleo Experimental de Campinas (IAC), were irradiated in a source of Cobalt-60, of the panoramic type, from the Instituto de Pesquisas Energeticas e Nucleares/CNEN/SP. The activity was approximately 2218.79 Ci, and the dose rate 0.678 kGy/h. The doses used were 0; 0.25; 0.5; 1.0 and 2.0 kGy. The results showed that the radiation doses did not influence the parameters evaluated in the resistance because a high degree of antibiose in the Arcelin-1 and Arcelin-2 lines was maintained. The Arcelin-3 and Arcelin-4 lines also maintained their behavior less expressive of resistance by antibiose only prolonging the period from egg to adult. The electrophoretic analysis of the lines and cultivar were not changed in relation to the radiation doses. But there was a decrease in relation to the intensity of color of the bands (absorbance) with the increase of the doses. (author)

  6. Gamma-ray binaries: pulsars in disguise ?

    CERN Document Server

    Dubus, G

    2006-01-01

    LS 5039 and LSI +61 303 are unique amongst high-mass X-ray binaries (HMXB) for their spatially-resolved radio emission and their counterpart at >GeV gamma-ray energies, canonically attributed to non-thermal particles in an accretion-powered relativistic jet. The only other HMXB known to emit very high energy (VHE) gamma-rays, PSR B1259-63, harbours a non-accreting millisecond pulsar. I investigate whether the interaction of the relativistic wind from a young pulsar with the wind from its stellar companion, as in PSR B1259-63, constitutes a viable scenario to explain the observations of LS 5039 and LSI +61 303. Emission would arise from the shocked pulsar wind material, which then flows away to large distances in a comet-shape tail, reproducing on a smaller scale what is observed in isolated, high motion pulsars interacting with the ISM. Simple expectations for the SED are derived and are shown to depend on few input parameters. Detailed modelling of the particle evolution is compared to the observations from ...

  7. The interplanetary gamma ray burst network

    Science.gov (United States)

    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.

  8. Gamma-ray bursts and collisionless shocks

    CERN Document Server

    Waxman, E

    2006-01-01

    Particle acceleration in collisionless shocks is believed to be responsible for the production of cosmic-rays over a wide range of energies, from few GeV to >10^{20} eV, as well as for the non-thermal emission of radiation from a wide variety of high energy astrophysical sources. A theory of collisionless shocks based on first principles does not, however, exist. Observations of gamma-ray burst (GRB) "afterglows" provide a unique opportunity for diagnosing the physics of relativistic collisionless shocks. Most GRBs are believed to be associated with explosions of massive stars, and their "afterglows," delayed low energy emission following the prompt burst of gamma-rays, are produced by relativistic collisionless shock waves driven by the explosion into the surrounding plasma. Some of the striking characteristics of these shocks include the generation of downstream magnetic fields with energy density exceeding that of the upstream field by ~8 orders of magnitude, the survival of this strong field at distances ...

  9. $\\gamma$-Ray Bursts the Four Crises

    CERN Document Server

    Tavani, M

    1998-01-01

    We discuss some open problems concerning the origin and the emission mechanism of gamma-ray bursts (GRBs) in light of recent developments. If GRBs originate at extragalactic distances, we are facing four crises: (1) an energy crisis, models have to account for more than 10^{53} ergs of energy emitted in the gamma-ray energy band; (2) a spectral crisis, emission models have to account for the surprising `smoothness' of GRB broad-band spectra, with no indication of the predicted spectral `distorsions' caused by inverse Compton scattering in large radiation energy density media, and no evidence for beaming; (3) an afterglow crisis, relativistic shock models have to explain the complexity of the afterglow behavior, the longevity of optical transients detectable up to six months after the burst, the erratic behavior of the radio emission, and the lack of evidence for substantial beaming as indicated by recent searches for GRB afterglows in the X-ray band; (4) a population crisis, from data clearly indicating that ...

  10. Radioisotope identification method for poorly resolved gamma-ray spectrum of nuclear security concern

    Energy Technology Data Exchange (ETDEWEB)

    Ninh, Giang Nguyen; Phongphaeth, Pengvanich, E-mail: phongphaeth.p@chula.ac.th; Nares, Chankow [Nuclear Engineering Department, Faculty of Engineering, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok 10330 (Thailand); Hao, Quang Nguyen [Vietnam Atomic Energy Institute, Ministry of Science and Technology, Hanoi (Viet Nam)

    2016-01-22

    Gamma-ray signal can be used as a fingerprint for radioisotope identification. In the context of radioactive and nuclear materials security at the border control point, the detection task can present a significant challenge due to various constraints such as the limited measurement time, the shielding conditions, and the noise interference. This study proposes a novel method to identify the signal of one or several radioisotopes from a poorly resolved gamma-ray spectrum. In this method, the noise component in the raw spectrum is reduced by the wavelet decomposition approach, and the removal of the continuum background is performed using the baseline determination algorithm. Finally, the identification of radioisotope is completed using the matrix linear regression method. The proposed method has been verified by experiments using the poorly resolved gamma-ray signals from various scenarios including single source, mixing of natural uranium with five of the most common industrial radioactive sources (57Co, 60Co, 133Ba, 137Cs, and 241Am). The preliminary results show that the proposed algorithm is comparable with the commercial method.

  11. Radioisotope identification method for poorly resolved gamma-ray spectrum of nuclear security concern

    Science.gov (United States)

    Ninh, Giang Nguyen; Phongphaeth, Pengvanich; Nares, Chankow; Hao, Quang Nguyen

    2016-01-01

    Gamma-ray signal can be used as a fingerprint for radioisotope identification. In the context of radioactive and nuclear materials security at the border control point, the detection task can present a significant challenge due to various constraints such as the limited measurement time, the shielding conditions, and the noise interference. This study proposes a novel method to identify the signal of one or several radioisotopes from a poorly resolved gamma-ray spectrum. In this method, the noise component in the raw spectrum is reduced by the wavelet decomposition approach, and the removal of the continuum background is performed using the baseline determination algorithm. Finally, the identification of radioisotope is completed using the matrix linear regression method. The proposed method has been verified by experiments using the poorly resolved gamma-ray signals from various scenarios including single source, mixing of natural uranium with five of the most common industrial radioactive sources (57Co, 60Co, 133Ba, 137Cs, and 241Am). The preliminary results show that the proposed algorithm is comparable with the commercial method.

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

    CERN Document Server

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

    2014-01-01

    The measurements of gamma-ray fluxes and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV, which will be implemented by the specially designed GAMMA-400 gamma-ray telescope, concern with the following broad range of science topics. Searching for signatures of dark matter, surveying the celestial sphere in order to study gamma-ray point and extended sources, measuring the energy spectra of Galactic and extragalactic diffuse gamma-ray emission, studying gamma-ray bursts and gamma-ray emission from the Sun, as well as high precision measuring spectra of high-energy electrons and positrons, protons and nuclei up to the knee. To clarify these scientific problems with the new experimental data the GAMMA-400 gamma-ray telescope possesses unique physical characteristics comparing with previous and present experiments. For gamma-ray energies more than 100 GeV GAMMA-400 provides the energy resolution of ~1% and angular resolution better than 0.02 deg. The methods developed to reconstru...

  13. Two classes of gamma-ray bursts

    CERN Document Server

    Katz, J I

    1995-01-01

    Data from the 3B Catalogue suggest that short and long GRB are the results of different classes of events, rather than different parameter values within a single class: Short bursts have harder spectra in the BATSE bands, but chiefly long bursts are detected at photon energies over 1 MeV, implying that their hard photons are radiated by a process not found in short bursts. The values of \\langle V/V_{max} \\rangle for short and long bursts differ by 4.3 \\sigma, implying different spatial distributions. Only the soft gamma-ray radiation mechanisms are the same in both classes.

  14. Gamma ray constraints on decaying dark matter

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  15. The Nature of Gamma Ray Burst Supernovae

    OpenAIRE

    Cano, Zach

    2012-01-01

    Gamma Ray Bursts (GRBs) and Supernovae (SNe) are among the brightest and most energetic physical processes in the universe. It is known that core-collapse SNe arise from the gravitational collapse and subsequent explosion of massive stars (the progen- itors of nearby core-collapse SNe have been imaged and unambiguously identified). It is also believed that the progenitors of long-duration GRBs (L-GRBs) are massive stars, mainly due to the occurrence and detection of very energetic core-collap...

  16. Properties of $\\gamma$-Ray Burst Classes

    CERN Document Server

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

    2000-01-01

    The three gamma-ray burst (GRB) classes identified by statistical clustering analysis (Mukherjee et al. 1998) are examined using the pattern recognition algorithm C4.5 (Quinlan 1986). Although the statistical existence of Class 3 (intermediate duration, intermediate fluence, soft) is supported, the properties of this class do not need to arise from a distinct source population. Class 3 properties can easily be produced from Class 1 (long, high fluence, intermediate hardness) by a combination of measurement error, hardness/intensity correlation, and a newly-identified BATSE bias (the fluence duration bias). Class 2 (short, low fluence, hard) does not appear to be related to Class 1.

  17. Digital Logarithmic Airborne Gamma Ray Spectrometer

    OpenAIRE

    2014-01-01

    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. The spectrometer can clearly distinguish the photopeaks at 239, 352, 583, and 609keV in the low-energy spectral sections after the energ...

  18. Nucleosynthetic Yields from Gamma-Ray Bursts

    CERN Document Server

    Rockefeller, Gabriel; Young, Patrick; Bennett, Michael; Diehl, Steven; Herwig, Falk; Hirschi, Raphael; Hungerford, Aimee; Pignatari, Marco; Magkotsios, Georgios; Timmes, Francis X

    2008-01-01

    The "collapsar" engine for gamma-ray bursts invokes as its energy source the failure of a normal supernova and the formation of a black hole. Here we present the results of the first three-dimensional simulation of the collapse of a massive star down to a black hole, including the subsequent accretion and explosion. The explosion differs significantly from the axisymmetric scenario obtained in two-dimensional simulations; this has important consequences for the nucleosynthetic yields. We compare the nucleosynthetic yields to those of hypernovae. Calculating yields from three-dimensional explosions requires new strategies in post-process nucleosynthesis; we discuss NuGrid's plan for three-dimensional yields.

  19. Polarized gamma-rays with laser-Compton backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Ohgaki, H.; Noguchi, T.; Sugiyama, S. [Electrotechnical Lab., Ibaraki (Japan)] [and others

    1995-12-31

    Polarized gamma-rays were generated through laser-Compton backscattering (LCS) of a conventional Nd:YAG laser with electrons circulating in the electron storage ring TERAS at Electrotechnical Laboratory. We measured the energy, the energy spread, and the yield of the gamma-rays to characterize our gamma-ray source. The gamma-ray energy can be varied by changing the energy of the electrons circulating the storage ring. In our case, the energy of electrons in the storage ring were varied its energy from 200 to 750 MeV. Consequently, we observed gamma-ray energies of 1 to 10 MeV with 1064 run laser photons. Furthermore, the gamma-ray energy was extended to 20 MeV by using the 2nd harmonic of the Nd:YAG laser. This shows a good agreement with theoretical calculation. The gamma-ray energy spread was also measured to be 1% FWHM for -1 MeV gamma-rays and to be 4% FWHM for 10 MeV gamma-rays with a narrow collimator that defined the scattering cone. The gamma-ray yield was 47.2 photons/mA/W/s. This value is consistent with a rough estimation of 59.5 photons/mA/W/s derived from theory. Furthermore, we tried to use these gamma-rays for a nuclear fluorescence experiment. If we use a polarized laser beam, we can easily obtain polarized gamma-rays. Elastically scattered photons from {sup 208} Pb were clearly measured with the linearly polarized gamma-rays, and we could assign the parity of J=1 states in the nucleus. We should emphasize that the polarized gamma-ray from LCS is quit useful in this field, because we can use highly, almost completely, polarized gamma-rays. We also use the LCS gamma-rays to measure the photon absorption coefficients. In near future, we will try to generate a circular polarized gamma-ray. We also have a plan to use an FEL, because it can produce intense laser photons in the same geometric configuration as the LCS facility.

  20. Development of a Small-Sized, Flexible, and Insertable Fiber-Optic Radiation Sensor for Gamma-Ray Spectroscopy

    Directory of Open Access Journals (Sweden)

    Wook Jae Yoo

    2015-08-01

    Full Text Available We fabricated a small-sized, flexible, and insertable fiber-optic radiation sensor (FORS that is composed of a sensing probe, a plastic optical fiber (POF, a photomultiplier tube (PMT-amplifier system, and a multichannel analyzer (MCA to obtain the energy spectra of radioactive isotopes. As an inorganic scintillator for gamma-ray spectroscopy, a cerium-doped lutetium yttrium orthosilicate (LYSO:Ce crystal was used and two solid-disc type radioactive isotopes with the same dimensions, cesium-137 (Cs-137 and cobalt-60 (Co-60, were used as gamma-ray emitters. We first determined the length of the LYSO:Ce crystal considering the absorption of charged particle energy and measured the gamma-ray energy spectra using the FORS. The experimental results demonstrated that the proposed FORS can be used to discriminate species of radioactive isotopes by measuring their inherent energy spectra, even when gamma-ray emitters are mixed. The relationship between the measured photon counts of the FORS and the radioactivity of Cs-137 was subsequently obtained. The amount of scintillating light generated from the FORS increased by increasing the radioactivity of Cs-137. Finally, the performance of the fabricated FORS according to the length and diameter of the POF was also evaluated. Based on the results of this study, it is anticipated that a novel FORS can be developed to accurately measure the gamma-ray energy spectrum in inaccessible locations such as narrow areas and holes.

  1. Effects of gamma-ray and high energy carbon ion irradiation on swimming velocity of Euglena gracilis

    Science.gov (United States)

    Sakashita, T.; Doi, M.; Yasuda, H.; Fuma, S.; Häder, D.-P.

    The effects of gamma-ray and high energy carbon ion irradiation on the swimming velocity of the photosynthetic flagellate Euglena gracilis strain Z were studied, focusing on a dose-effect relationship. Cells were exposed to 60Co gamma-rays at 6 doses of 10, 15, 20, 40, 100 and 200 Gy for water, and also to 290 MeV/amu carbon ions from the Heavy Ion Medical Accelerator in Chiba at 7 doses (5, 10, 15, 20, 50, 100 and 200 Gy for water). The swimming velocity was measured by a biomonitoring system, called ECOTOX. The swimming velocities of Euglena gracilis cells were significantly decreased by >40 Gy gamma-rays and >5 Gy carbon ions, respectively. The 50% effective doses for inhibition, 34±4 Gy (gamma-rays) and 13±1 Gy (290 MeV/amu carbon ions), were estimated from the best fit to data of the logistic model. The relative biological effectiveness (2.6±0.4) was calculated by the ratio of 50% effective doses. The inhibition of the swimming velocity of the cells irradiated with gamma-rays was still present after 3 days, while recovery of the swimming velocity was shown in the cells exposed to 290 MeV/amu carbon ions. It is suggested that ionizing radiation inhibits ATP production and/or increases frictional drag on beating of the flagellum, thus decreasing swimming velocity.

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

    CERN Document Server

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

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Balloon-borne gamma-ray polarimetry

    CERN Document Server

    Pearce, Mark

    2011-01-01

    The physical processes postulated to explain the high-energy emission mechanisms of compact astrophysical sources often yield polarised soft gamma rays (X-rays). PoGOLite is a balloon-borne polarimeter operating in the 25-80 keV energy band. The polarisation of incident photons is reconstructed using Compton scattering and photoelectric absorption in an array of phoswich detector cells comprising plastic and BGO scintillators, surrounded by a BGO side anticoincidence shield. The polarimeter is aligned to observation targets using a custom attitude control system. The maiden balloon flight is scheduled for summer 2011 from the Esrange Space Centre with the Crab and Cygnus X-1 as the primary observational targets.

  5. Gamma-ray burst afterglow theory

    CERN Document Server

    van Eerten, Hendrik

    2013-01-01

    It is by now fairly well established that gamma-ray burst afterglows result from initially relativistic outflows interacting with the medium surrounding the burster and emitting non-thermal radiation ranging from radio to X-rays. However, beyond that, many big and small questions remain about afterglows, with the accumulating amount of observational data at the various frequencies raising as many questions as they answer. In this review I highlight a number of current theoretical issues and how they fit or do not fit within our basic theoretical framework. In addition to theoretical progress I will also emphasize the increasing role and usefulness of numerical studies of afterglow blast waves and their radiation.

  6. SAS-2 galactic gamma ray results, 1

    Science.gov (United States)

    Thompson, D. J.; Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Bignami, G. F.; Lamb, R. C.; Oegelman, H.; Oezel, M. E.; Tuemer, T.

    1976-01-01

    Continuing analysis of the data from the SAS-2 high energy gamma-ray experiment has produced an improved picture of the sky at photon energies above 35 MeV. On a large scale, the diffuse emission from the galactic plane is the dominant feature observed by SAS-2. This galactic plane emission is most intense between galactic longitude 310 and 45 deg, corresponding to a region within 7kpc of the galactic center. Within the high-intensity region, SAS-2 observes peaks around galactic longitudes 315 deg, 330 deg, 345 deg, 0 deg, and 35 deg. These peaks appear to be correlated with such galactic features and components as molecular hydrogen, atomic hydrogen, magnetic fields, cosmic ray concentrations, and photon fields.

  7. Possible distance indicators in gamma-ray pulsars

    Institute of Scientific and Technical Information of China (English)

    Wei Wang

    2011-01-01

    Distance measurement of gamma-ray pulsars is a current challenge in pulsar studies. The Large Area Telescope (LAT) aboard the Fermi gamma-ray observatory discovered more than 70 gamma-ray pulsars including 24 new gamma-selected pulsars with almost no distance information. We study the relation between gammaray emission efficiency (η = Lγ/E) and pulsar parameters for young radio-selected gamma-ray pulsars with known distance information in the first gamma-ray pulsar catalog reported by Fermi/LAT. We have introduced three generation-order parameters to describe the gamma-ray emission properties of pulsars, and find a strong correlation of rη- ζ3, a generation-order parameter which reflects γ-ray photon generation in the pair cascade processes induced by magnetic field absorption in a pulsar's magnetosphere.A good correlation of η- BLC, the magnetic field at the light cylinder radius, is also found. These correlations are the distance indicators in gamma-ray pulsars used to evaluate distances for gamma-selected pulsars. Distances of 25 gamma-selected pulsars are estimated, which could be tested by other distance measurement methods. The physical origin of the correlations may also be interesting for pulsar studies.

  8. Pulse Summing in the gamma-Ray Spectra

    CERN Document Server

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

    2004-01-01

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

  9. AGNs and microquasars as high energy gamma-ray sources

    CERN Document Server

    Paredes, J M

    2004-01-01

    The extragalactic analogs of the microquasars, the quasars, are strong gamma-ray emitters at GeV energies. It is expected that microquasars are also gamma-ray sources, because of the analogy with quasars and because theoretical models predict the high-energy emission. There are two microquasars that appear as the possible counterparts for two unidentified high-energy gamma-ray sources.

  10. Gamma ray bursts, neutron star quakes, and the Casimir effect

    CERN Document Server

    Carlson, C; Pérez-Mercader, J; Carlson, C; Goldman, T; Perez-Mercader, J

    1994-01-01

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

  11. Analysis of Spontaneous,gamma ray-and ethylnitrosourea-induced hprt mutants in HL-60 cells With multiplex PCR

    Institute of Scientific and Technical Information of China (English)

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

    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 100-200μg/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 13spontaneous 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 gammaray-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.

  12. ICF gamma-ray reaction history diagnostics

    Science.gov (United States)

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

    2010-08-01

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

  13. The Space-Based Gamma-Ray Telescope GAMMA-400 and Its Scientific Goals

    CERN Document Server

    Galper, A M; Aptekar, R L; Arkhangelskaja, I V; Arkhangelskiy, A I; Avanesov, G A; Bergstrom, L; Bogomolov, E A; Boezio, M; Bonvicini, V; Boyarchuk, K A; Dogiel, V A; Gusakov, Yu V; Fradkin, M I; Fuglesang, Ch; Hnatyk, B I; Kachanov, V A; Kadilin, V V; Kaplin, V A; Kheymits, M D; Korepanov, V; Larsson, J; Leonov, A A; Longo, F; Maestro, P; Marrocchesi, P; Mikhailov, V V; Mocchiutti, E; Moiseev, A A; Mori, N; Moskalenko, I; Naumov, P Yu; Papini, P; Pearce, M; Picozza, P; Runtso, M F; Ryde, F; Sparvoli, R; Spillantini, P; Suchkov, S I; Tavani, M; Topchiev, N P; Vacchi, A; Vannuccini, E; Vasiliev, G I; Yurkin, Yu T; Zampa, N; Zarikashvili, V N; Zverev, V G

    2013-01-01

    The design of the new space-based gamma-ray telescope GAMMA-400 is presented. GAMMA-400 is optimized for the energy 100 GeV with the best parameters: the angular resolution ~0.01 deg, the energy resolution ~1%, and the proton rejection factor ~10E6, but is able to measure gamma-ray and electron + positron fluxes in the energy range from 100 MeV to 10 TeV. GAMMA-400 is aimed to a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons + positrons, and nuclei.

  14. Long Gamma-Ray Transients from Collapsars

    CERN Document Server

    Woosley, S E

    2011-01-01

    In the collapsar model for common gamma-ray bursts, the formation of a centrifugally supported disk occurs during the first $\\sim$10 seconds 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 gamma-ray burst. A broad range of powers is possible, $10^{47}$ to $10^{50}\\,$erg s$^{-1}$, and t...

  15. The Cosmic Gamma-Ray Bursts

    CERN Document Server

    Djorgovski, S G; Kulkarni, S R; Sari, R; Bloom, J S; Galama, T J; Harrison, F A; Price, P A; Fox, D; Reichart, D; Yost, S; Berger, E; Diercks, A H; Goodrich, R; Chaffee, F H

    2001-01-01

    Cosmic gamma-ray bursts are one of the great frontiers of astrophysics today. They are a playground of relativists and observers alike. They may teach us about the death of stars and the birth of black holes, the physics in extreme conditions, and help us probe star formation in the distant and obscured universe. In this review we summarise some of the remarkable progress in this field over the past few years. While the nature of the GRB progenitors is still unsettled, it now appears likely that at least some bursts originate in explosions of very massive stars, or at least occur in or near the regions of massive star formation. The physics of the burst afterglows is reasonably well understood, and has been tested and confirmed very well by the observations. Bursts are found to be beamed, but with a broad range of jet opening angles; the mean gamma-ray energies after the beaming corrections are ~ 10^51 erg. Bursts are associated with faint ~ 25 mag) galaxies at cosmological redshifts, with ~ 1. The host gal...

  16. Radio flares from gamma-ray bursts

    CERN Document Server

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

    2015-01-01

    We present predictions of centimeter and millimeter radio emission from reverse shocks in the early afterglows of gamma-ray bursts with the goal of determining their detectability with current and future radio facilities. Using a range of GRB properties, such as peak optical brightness and time, isotropic equivalent gamma-ray energy and redshift, we simulate radio light curves in a framework generalized for any circumburst medium structure and including a parametrization of the shell thickness regime that is more realistic than the simple assumption of thick- or thin-shell approximations. Building on earlier work by Mundell et al. (2007) and Melandri et al. (2010) in which the typical frequency of the reverse shock was suggested to lie at radio, rather than optical wavelengths at early times, we show that the brightest and most distinct reverse-shock radio signatures are detectable up to 0.1 -- 1 day after the burst, emphasizing the need for rapid radio follow-up. Detection is easier for bursts with later opt...

  17. Classifying Unidentified Gamma-ray Sources

    CERN Document Server

    Salvetti, David

    2016-01-01

    During its first 2 years of mission the Fermi-LAT instrument discovered more than 1,800 gamma-ray sources in the 100 MeV to 100 GeV range. Despite the application of advanced techniques to identify and associate the Fermi-LAT sources with counterparts at other wavelengths, about 40% of the LAT sources have no a clear identification remaining "unassociated". The purpose of my Ph.D. work has been to pursue a statistical approach to identify the nature of each Fermi-LAT unassociated source. To this aim, we implemented advanced machine learning techniques, such as logistic regression and artificial neural networks, to classify these sources on the basis of all the available gamma-ray information about location, energy spectrum and time variability. These analyses have been used for selecting targets for AGN and pulsar searches and planning multi-wavelength follow-up observations. In particular, we have focused our attention on the search of possible radio-quiet millisecond pulsar (MSP) candidates in the sample of...

  18. Gamma ray tests of Minimal Dark Matter

    Energy Technology Data Exchange (ETDEWEB)

    Cirelli, Marco [Institut de Physique Théorique, Université Paris Saclay, CNRS, CEA, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Hambye, Thomas [Service de Physique Theórique, Université Libre de Bruxelles, Boulevard du Triomphe, CP225, 1050 Brussels (Belgium); Panci, Paolo [Institut d’Astrophysique de Paris, UMR 7095 CNRS, Université Pierre et Marie Curie, 98 bis Boulevard Arago, Paris 75014 (France); Sala, Filippo; Taoso, Marco [Institut de Physique Théorique, Université Paris Saclay, CNRS, CEA, Orme des Merisiers, F-91191 Gif-sur-Yvette (France)

    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.

  19. Novel Features of Gamma Ray from Dark Matter

    CERN Document Server

    Tang, Yong

    2015-01-01

    In this study, we present some general and novel features of gamma ray from dark matter. We find that gamma-ray spectra with sharp features exist in a wide class of dark matter models and mimic the gamma line signals. The generated gamma rays would generally have polynomial-type spectra or power-law with positive index. We illustrate our results in a model-independent framework with generic kinematic analysis. Similar results can also apply for cosmic rays or neutrino cases.

  20. Gamma-ray spectroscopy on irradiated fuel rods

    Energy Technology Data Exchange (ETDEWEB)

    Terremoto, Luis Antonio Albiac [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Engenharia Nuclear], e-mail: laaterre@ipen.br

    2009-07-01

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

  1. GRIPS - Gamma-Ray Burst Investigation via Polarimetry and Spectroscopy

    CERN Document Server

    Greiner, J

    2008-01-01

    The primary scientific goal of the GRIPS mission is to revolutionize our understanding of the early universe using gamma-ray bursts. We propose a new generation gamma-ray observatory capable of unprecedented spectroscopy over a wide range of gamma-ray energies (200 keV--50 MeV) and of polarimetry (200--1000 keV). Secondary goals achievable by this mission include direct measurements of supernova interiors through gamma-rays from radioactive decays, nuclear astrophysics with massive stars and novae, and studies of particle acceleration near compact stars, interstellar shocks, and clusters of galaxies.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-05-15

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

  3. Mercuric Iodide Anticoincidence Shield for Gamma-Ray Spectrometer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to utilize a new detector material, polycrystalline mercuric iodide, for background suppression by active anticoincidence shielding in gamma-ray...

  4. Mercuric Iodide Anticoincidence Shield for Gamma-Ray Spectrometer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We utilize a new detector material, polycrystalline mercuric iodide, for background suppression by active anticoincidence shielding in gamma-ray spectrometers. Two...

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

    DEFF Research Database (Denmark)

    Content, Robert; Sharples, Ray; Page, Mathew J.

    2012-01-01

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

  6. Studying the WHIM with Gamma Ray Bursts

    CERN Document Server

    Branchini, E; Corsi, A; Martizzi, D; Amati, L; Herder, J W den; Galeazzi, M; Gendre, B; Kaastra, J; Moscardini, L; Nicastro, F; Ohashi, T; Paerels, F; Piro, L; Roncarelli, M; Takei, Y; Viel, M

    2009-01-01

    We assess the possibility to detect and characterize the physical state of the missing baryons at low redshift by analyzing the X-ray absorption spectra of the Gamma Ray Burst [GRB] afterglows, measured by a micro calorimeters-based detector with 3 eV resolution and 1000 cm2 effective area and capable of fast re-pointing, similar to that on board of the recently proposed X-ray satellites EDGE and XENIA. For this purpose we have analyzed mock absorption spectra extracted from different hydrodynamical simulations used to model the properties of the Warm Hot Intergalactic Medium [WHIM]. These models predict the correct abundance of OVI absorption lines observed in UV and satisfy current X-ray constraints. According to these models space missions like EDGE and XENIA should be able to detect about 60 WHIM absorbers per year through the OVII line. About 45 % of these have at least two more detectable lines in addition to OVII that can be used to determine the density and the temperature of the gas. Systematic error...

  7. The First Fermi Gamma-ray Burst Monitor (GBM) Terrestrial Gamma-ray Flash (TGF) Catalog

    Science.gov (United States)

    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).

  8. Key comparison BIPM.RI(I)-K4 of the absorbed dose to water standards of the LNE-LNHB, France and the BIPM in 60Co gamma radiation

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Delaunay, F.; Donois, M.

    2013-01-01

    An indirect comparison has been made of the standards for absorbed dose to water in 60Co radiation of the Laboratoire National de Métrologie et d'Essais-Laboratoire National Henri Becquerel (LNE-LNHB), France and of the Bureau International des Poids et Mesures (BIPM). The measurements at the BIPM were carried out in April 2013. The comparison result, based on the calibration coefficients for two transfer standards and evaluated as a ratio of the LNE-LNHB and the BIPM standards for absorbed dose to water, is 0.9971 with a combined standard uncertainty of 3.9 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  9. Assessment of differences between X and gamma rays in order to validate a new generation of irradiators for insect sterilization

    Energy Technology Data Exchange (ETDEWEB)

    Mastrangelo, Thiago; Walder, Julio M.M., E-mail: piaui@cena.usp.b [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil); Parker, Andrew G.; Jessup, Andrew; Orozco-Davila, Dina; Islam, Amirul; Dammalage, Thilakasiri, E-mail: A.Jessup@iaea.or [Joint FAO/IAEA-UN A-2444, Seibersdorf (Austria). Insect Pest Control Subprogramme; Pereira, Rui, E-mail: R.Cardoso-Pereira@iaea.or [Joint FAO/IAEA-UN, Vienna (Austria). Insect Pest Control Subprogramme

    2009-07-01

    Recent fears of terrorism provoked an increase in delays and denials of transboundary shipments of radioisotopes. This represents a serious constraint to sterile insect technique (SIT) programs around the world as they rely on the use of ionizing energy from radioisotopes for insect sterilization. In order to validate a novel Xray irradiator, a series of studies on Ceratitis capitata (Wiedemann) and Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) were carried out, comparing the relative biological effectiveness (RBE) between X-rays and traditional gamma radiation from {sup 60}Co. Male C. capitata pupae and pupae of both sexes of A. fraterculus, both 24 to 48 h before adult emergence, were irradiated with doses ranging from 15 to 120 Gy and 10 to 70 Gy respectively. Estimated mean doses of 91.2 Gy of X and 124.9 Gy of gamma radiation induced 99% sterility in C. capitata males. Irradiated A. fraterculus were 99% sterile at about 40-60 Gy for both radiation treatments. Standard quality control parameters were not significantly affected by the two types of radiation. There were no significant differences between X and gamma radiation regarding mating indices. The RBE did not differ significantly between the tested X and gamma radiation, and X-rays are as biologically effective for SIT purposes as gamma rays are. This work confirms the suitability of this new generation of X-ray irradiators for pest control programs in UN Member States. (author)

  10. Determination of {sup 60}Co sorption in natural clinoptilolite; Determinacion de la sorcion de {sup 60}Co en clinoptilolita natural

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez B, E.; Granados C, F. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    It was studied the clinoptilolite behavior coming from a deposit in Taxco, Guerrero in hydration and stabilization conditions with sodium for determining its sorption properties. The ion exchange process was carried out through gamma spectrometry using a CoCl{sub 2} solution marked with {sup 60} Co at p H 6.5 in different contact times. It was observed a maximum sorption of 0.408 m eq Co{sup +2}/g mineral, from 0.314 m eq Co{sup +2}/g mineral correspond at ion exchange. (Author)

  11. Free ion yield observed in liquid isooctane irradiated by gamma rays. Comparison with the Onsager theory.

    Science.gov (United States)

    Pardo, J; Franco, L; Gómez, F; Iglesias, A; Lobato, R; Mosquera, J; Pazos, A; Pena, J; Pombar, M; Rodríguez, A; Sendón, J

    2004-05-21

    We have analysed data on the free ion yield observed in liquid isooctane irradiated by 60Co gamma rays within the framework of the Onsager theory about initial recombination. Several distribution functions describing the electron thermalization distance have been used and compared with the experimental results: a delta function, a Gaussian-type function and an exponential function. A linear dependence between the free ion yield and the external electric field has been found at low-electric-field values (E < or = 1.2 x 10(3) V mm(-1)) in excellent agreement with the Onsager theory. At higher electric field values, we obtain a solution in power series of the external field using the Onsager theory.

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

    Science.gov (United States)

    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 Ratiocomet assay under alkaline conditions, combined with comet image analysis, can be used to identify irradiation history.

  13. Free ion yield observed in liquid isooctane irradiated by {gamma} rays. Comparison with the Onsager theory

    Energy Technology Data Exchange (ETDEWEB)

    Pardo, J [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Franco, L [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Gomez, F [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Iglesias, A [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Lobato, R [Hospital ClInico Universitario de Santiago, Santiago de Compostela (Spain); Mosquera, J [Hospital ClInico Universitario de Santiago, Santiago de Compostela (Spain); Pazos, A [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Pena, J [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Pombar, M [Hospital ClInico Universitario de Santiago, Santiago de Compostela (Spain); RodrIguez, A [Departamento de FIsica de PartIculas, Facultade de FIsica, 15782 Santiago de Compostela (Spain); Sendon, J [Hospital ClInico Universitario de Santiago, Santiago de Compostela (Spain)

    2004-05-21

    We have analysed data on the free ion yield observed in liquid isooctane irradiated by {sup 60}Co {gamma} rays within the framework of the Onsager theory about initial recombination. Several distribution functions describing the electron thermalization distance have been used and compared with the experimental results: a delta function, a Gaussian-type function and an exponential function. A linear dependence between the free ion yield and the external electric field has been found at low-electric-field values (E {<=} 1.2 x 10{sup 3} V mm{sup -1}) in excellent agreement with the Onsager theory. At higher electric field values, we obtain a solution in power series of the external field using the Onsager theory.

  14. Analysis of adhesion of radiation curable compositions to polyester substrate. [. gamma. rays or electrons

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, W.K.; Barbery, J.; Gupta, B.S.

    1977-07-01

    Properties of bonds produced by radiation curing of adhesives on polyester film were studied. Investigation of bonding in polyester non-wovens had revealed that adhesion of binders to fibers was weak, which resulted in interfacial failures, judged from electron micrographs. If a binder droplet surrounds a cluster of fibers, tearing of binder took place but fibers still peeled out of droplets with interfacial separation. In order to understand the failure mechanism, a study was carried out on Mylar film bonded with adhesives cured by electron beam or gamma-rays from /sup 60/Co. Mixtures of isodecyl acrylate and methyl methacrylate were copolymerized between Mylar films to produce adhesives with a wide range of glass transition temperatures. Hexanediol diacrylate was added in various amounts to produce different degrees of cross-linking. Small amounts of fumed silica (Cab-O-Sil) were added to thicken the monomers used in the /sup 60/Co experiments. By varying rheological properties in this fashion, a maximum peel force of 3.5 lb/in. was obtained. This value is in line with peel strengths from polyester using commercial, prepolymerized adhesives with solubility parameters similar to those used here delta = 8.3 to 9.3). These results show that the primary reason for the poor adhesion of radiation curable adhesives to polyester is their high degree of cross-linking and that radiation curable adhesives are not basically different from other types, except in cases where their unique properties could be utilized with advantage.

  15. SAS-2 galactic gamma-ray results. 2: Localized sources

    Science.gov (United States)

    Hartman, R. C.; Fichtel, C. E.; Kniffen, D. A.; Lamb, R. C.; Thompson, D. J.; Bignami, G. F.; Oegelman, H.; Oezel, M. E.; Tuemer, T.

    1977-01-01

    Gamma ray emission was detected from the radio pulsars PSR 1818-04 and PSR 1747-46, in addition to the previously reported gamma ray emission from the Crab and Vela pulsars. Because the Crab pulsar is the only one observed in the optical and X-ray bands, these gamma ray observations suggest a uniquely gamma ray phenomenon occurring in a fraction of the radio pulsars. PSR 1818-04 has a gamma ray luminosity comparable to that of the Crab pulsar, whereas the luminosities of PSR 1747-46 and the Vela pulsar are approximately an order of magnitude lower. SAS-2 data for pulsar correlations yielded upper limits to gamma ray luminosity for 71 other radio pulsars. For five of the closest pulsars, upper limits for gamma ray luminosity are found to be at least three orders of magnitude lower than that of the Crab pulsar. Gamma ray enhancement near the Milky Way satellite galaxy and the galactic plane in the Cygnus region is also discussed.

  16. MIRAX sensitivity for Gamma Ray Bursts

    Science.gov (United States)

    Sacahui, J. R.; Penacchioni, A. V.; Braga, J.; Castro, M. A.; D'Amico, F.

    2016-03-01

    In this work we present the detection capability of the MIRAX (Monitor e Imageador de RAios-X) experiment for Gamma-Ray Bursts (GRBs). MIRAX is an X-ray astronomy mission designed to perform a wide band hard X-ray (10-200 keV) survey of the sky, especially in the Galactic plane. With a total detection area of 169 cm2, large field of view (FoV, 20 ° × 20 °), angular resolution of 1°45‧ and good spectral and time resolution (∼8% at 60 keV, 10 μs), MIRAX will be optimized for the detection and study of transient sources, such as accreting neutron stars (NS), black holes (BH), Active Galactic Nuclei (AGNs), and both short and long GRBs. This is especially important because MIRAX is expected to operate in an epoch when probably no other hard X-ray wide-field imager will be active. We have performed detailed simulations of MIRAX GRB observations using the GEANT4 package, including the background spectrum and images of GRB sources in order to provide accurate predictions of the sensitivity for the expected GRB rate to be observed. MIRAX will be capable of detecting ∼44 GRBs per year up to redshifts of ∼4.5. The MIRAX mission will be able to contribute significantly to GRB science by detecting a large number of GRBs per year with wide band spectral response. The observations will contribute mainly to the part of GRB spectra where a thermal emission is predicted by the Fireball model. We also discuss the possibility of detecting GRB afterglows in the X-ray band with MIRAX.

  17. The Fermi Gamma-ray Burst Monitor (GBM) Terrestrial Gamma-ray Flash (TGF) Catalog

    Science.gov (United States)

    Stanbro, M.; Briggs, M. S.; Roberts, O.; McBreen, S.; Bhat, N.; Fitzpatrick, G.

    2015-12-01

    We present results from the catalog of Terrestrial Gamma-ray Flashes (TGFs) detected with the Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Space Telescope. The first release, in January 2015, provided data on 2700 TGFs. Updates are extending the catalog at a rate of ~800 TGFs per year. 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 other Bayesian Block durations. The catalog includes separate tables for bright TGFs detected by the flight software and for Terrestrial Electron Beams (TEBs). In January 2016 additional data will be released online from correlating these TGFs with sferics detected by the World Wide Lightning Location Network (WWLLN). Maps of sferics in the vicinity of each TGF will be provided, as will the locations and times of sferics found to be associated with TGFs.

  18. Central Engine Memory of Gamma-Ray Bursts and Soft Gamma-Ray Repeaters

    CERN Document Server

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

    2016-01-01

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

  19. Neutrino astronomy and gamma-ray bursts

    CERN Document Server

    Waxman, E

    2007-01-01

    The construction of large volume detectors of high energy, >1 TeV, neutrinos is mainly driven by the search for extra-Galactic neutrino sources. The existence of such sources is implied by observations of ultra-high energy, >10^{19} eV, cosmic-rays, the origin of which is a mystery. In this lecture I briefly discuss the expected extra-Galactic neutrino signal and the current state of the experimental efforts. Neutrino emission from gamma-ray bursts (GRBs), which are likely sources of both high energy protons and neutrinos, is discussed in some detail. The detection of the predicted GRB neutrino signal, which may become possible in the coming few years, will allow one to identify the sources of ultra-high energy cosmic-rays and to resolve open questions related to the underlying physics of GRB models. Moreover, detection of GRB neutrinos will allow one to test for neutrino properties (e.g. flavor oscillations and coupling to gravity) with an accuracy many orders of magnitude better than is currently possible.

  20. Swift observations of gamma-ray bursts.

    Science.gov (United States)

    Gehrels, Neil

    2007-05-15

    Since its launch on 20 November 2004, the Swift mission has been detecting approximately 100 gamma-ray bursts (GRBs) each year, and immediately (within approx. 90s) starting simultaneous X-ray and UV/optical observations of the afterglow. It has already collected an impressive database, including prompt emission to higher sensitivities than BATSE, uniform monitoring of afterglows and a rapid follow-up by other observatories notified through the GCN. Advances in our understanding of short GRBs have been spectacular. The detection of X-ray afterglows has led to accurate localizations and the conclusion that short GRBs can occur in non-star-forming galaxies or regions, whereas long GRBs are strongly concentrated within the star-forming regions. This is consistent with the NS merger model. Swift has greatly increased the redshift range of GRB detection. The highest redshift GRBs, at z approximately 5-6, are approaching the era of reionization. Ground-based deep optical spectroscopy of high redshift bursts is giving metallicity measurements and other information on the source environment to a much greater distance than other techniques. The localization of GRB 060218 to a nearby galaxy, and the association with SN 2006aj, added a valuable member to the class of GRBs with detected supernova.

  1. The Gamma Ray Bursts Hubble diagram

    CERN Document Server

    Capozziello, S; Dainotti, M G; De Laurentis, M; Izzo, L; Perillo, M

    2011-01-01

    Thanks to their enormous energy release, Gamma Rays Bursts (GRBs) have recently attracted a lot of interest to probe the Hubble diagram (HD) deep into the matter dominated era and hence complement Type Ia Supernovae (SNeIa). We consider here three different calibration methods based on the use of a fiducial LCDM model, on cosmographic parameters and on the local regression on SNeIa to calibrate the scaling relations proposed as an equivalent to the Phillips law to standardize GRBs finding any significant dependence. We then investigate the evolution of these parameters with the redshift to obtain any statistical improvement. Under this assumption, we then consider possible systematics effects on the HDs introduced by the calibration method, the averaging procedure and the homogeneity of the sample arguing against any significant bias.

  2. Search for Gamma Ray Bursts at Chacaltaya

    CERN Document Server

    Vernetto, S

    2001-01-01

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

  3. Black Holes, Supernovae and Gamma Ray Bursts

    CERN Document Server

    Ruffini, Remo

    2013-01-01

    We review recent progress in our understanding of the nature of gamma ray bursts (GRBs) and in particular, of the relationship between short GRBs and long GRBs. The first example of a short GRB is described. The coincidental occurrence of a GRB with a supernova (SN) is explained within the induced gravitational collapse (IGC) paradigm, following the sequence: 1) an initial binary system consists of a compact carbon-oxygen (CO) core star and a neutron star (NS); 2) the CO core explodes as a SN, and part of the SN ejecta accretes onto the NS which reaches its critical mass and collapses to a black hole (BH) giving rise to a GRB; 3) a new NS is generated by the SN as a remnant. The observational consequences of this scenario are outlined.

  4. Relativistic Outflows in Gamma-Ray Bursts

    CERN Document Server

    Aloy, M A

    2007-01-01

    The possibility that gamma-ray bursts (GRBs) were not isotropic emissions was devised theoretically as a way to ameliorate the huge energetic budget implied by the standard fireball model for these powerful phenomena. However, the mechanism by which after the quasy-isotropic release of a few $10^{50} $erg yields a collimated ejection of plasma could not be satisfactory explained analytically. The reason being that the collimation of an outflow by its progenitor system depends on a very complex and non-linear dynamics. That has made necessary the use of numerical simulations in order to shed some light on the viability of some likely progenitors of GRBs. In this contribution I will review the most relevant features shown by these numerical simulations and how they have been used to validate the collapsar model (for long GRBs) and the model involving the merger of compact binaries (for short GRBs).

  5. Statistics of gamma ray burst temporal asymmetry

    CERN Document Server

    Link, B; Link, Bennett; Epstein, Richard

    1996-01-01

    We study the temporal asymmetry of over 600 bursts from the BATSE 3B catalog, encompassing a 200-fold range in peak flux. By comparing the rates of rise and fall of the flux near the highest burst peak, we find that about two-thirds of the bursts exhibit a preferred asymmetry in the sense that the flux rises more rapidly than it falls, confirming the conclusions of previous studies employing smaller databases. The statistical significance of the average time asymmetry of the sample is >99.999\\%; therefore, models that predict time symmetry of the burst profile are ruled out. We find no statistically significant correlation between burst temporal asymmetry and peak. This result is consistent with both cosmological and local interpretations of the gamma ray burst phenomenon.

  6. Perspectives on Gamma-Ray Pulsar Emission

    CERN Document Server

    Baring, Matthew G

    2010-01-01

    Pulsars are powerful sources of radiation across the electromagnetic spectrum. This paper highlights some theoretical insights into non-thermal, magnetospheric pulsar gamma-ray radiation. These advances have been driven by NASA's Fermi mission, launched in mid-2008. The Large Area Telescope (LAT) instrument on Fermi has afforded the discrimination between polar cap and slot gap/outer gap acceleration zones in young and middle-aged pulsars. Altitude discernment using the highest energy pulsar photons will be addressed, as will spectroscopic interpretation of the primary radiation mechanism in the LAT band, connecting to both polar cap/slot gap and outer gap scenarios. Focuses will mostly be on curvature radiation and magnetic pair creation, including population trends that may afford probes of the magnetospheric accelerating potential.

  7. Digital Logarithmic Airborne Gamma Ray Spectrometer

    CERN Document Server

    Zeng, GuoQiang; Li, Chen; Tan, ChengJun; Ge, LiangQuan; Gu, Yi; Cheng, Feng

    2014-01-01

    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. The spectrometer can clearly distinguish the photopeaks at 239, 352, 583, and 609keV in the low-energy spectral sections after the energy calibration. 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, effectively measuring energy from 20keV to 10MeV is possible.

  8. Digital logarithmic airborne gamma ray spectrometer

    Science.gov (United States)

    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.

  9. Gamma-Ray Bursts: A Radio Perspective

    Directory of Open Access Journals (Sweden)

    Poonam Chandra

    2016-01-01

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

  10. Gamma rays from muon capture in {sup 14}N

    Energy Technology Data Exchange (ETDEWEB)

    Stocki, T.J. E-mail: trevor.stocki@crc.ca; Measday, D.F.; Gete, E.; Saliba, M.A.; Moftah, B.A.; Gorringe, T.P

    2002-01-14

    Many new {gamma}-rays have been observed, following muon capture on {sup 14}N. One had been reported before, and the low yield is confirmed, indicating that the nuclear structure of {sup 14}N is still not understood. Gamma rays from {sup 13}C resulting from the reaction {sup 14}N({mu}{sup -},{nu}n){sup 13}C compare favourably with states observed in the reaction {sup 14}N({gamma}, p){sup 13}C. More precise energies are also given for the 7017 and 6730 keV {gamma}-rays in {sup 14}C.

  11. Gamma-Ray Bursts: Pulses and Populations

    Science.gov (United States)

    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

  12. Gamma Rays from Star Formation in Clusters of Galaxies

    CERN Document Server

    Storm, Emma; Profumo, Stefano

    2012-01-01

    Star formation in galaxies is observed to be associated with gamma-ray emission. The detection of gamma rays from star-forming galaxies by the Fermi Large Area Telescope (LAT) has allowed the determination of a functional relationship between star formation rate and gamma-ray luminosity (Ackermann et. al. 2012). Since star formation is known to scale with total infrared (8-1000 micrometers) 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 relationships between gamma-ray luminosity and radio and IR luminosities derived in Ackermann et. al. 2012 to a sample of galaxy clusters from Ackermann et. al. 2010 in order to place lower limits on the gamma-ray emission associated with sta...

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

    DEFF Research Database (Denmark)

    Hovgaard, Jens

    1997-01-01

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

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

    NARCIS (Netherlands)

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

    2010-01-01

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

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

    CERN Document Server

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

    2001-01-01

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

  16. Supernova sheds light on gamma-ray bursts

    CERN Multimedia

    2003-01-01

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

  17. HEAO C-1 gamma-ray spectrometer. [experimental design

    Science.gov (United States)

    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.

  18. Enhanced gamma-ray activity from the Crab nebula

    Science.gov (United States)

    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.

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

    NARCIS (Netherlands)

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

    2010-01-01

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

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

    NARCIS (Netherlands)

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

    2011-01-01

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

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

    NARCIS (Netherlands)

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

    2012-01-01

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

  2. Very High Energy Gamma Ray Extension of GRO Observations

    Science.gov (United States)

    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.

  3. Combined effects of {gamma}-rays and acidification on an experimental model ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Fuma, Shoichi; Ishii, Nobuyoshi; Takeda, Hiroshi [National Inst. of Radiological Sciences, Chiba (Japan); Kawabata, Zen' ichiro [Kyoto Univ. (Japan). Center for Ecological Research; Ichimasa, Yusuke [Ibaraki Univ., Mito (Japan). Faculty of Science

    2002-05-01

    It is necessary to evaluate combined effects of ionizing radiation and other toxic agents on ecosystems, because ecosystems are exposed to these various factors. The authors studied combined effects of {gamma}-rays and acidification on an experimental model ecosystem (microcosm) mimicking aquatic microbial communities. Microcosms, consisted of flagellate algae Euglena gracilis Z as a producer, ciliate protozoa Tetrahymena thermophila B as a consumer and bacteria Escherichia coli DH5{alpha} as a decomposer, were loaded by the following treatments: Irradiation with 100 Gy {sup 60}Co {gamma}-rays; Acidification of culture medium to pH4.0 with the mixture of 0.1 N HNO{sub 3} and 0.1 N H{sub 2}SO{sub 4} (1:1, v/v), which mimicked acid rain; and Irradiation with 100 Gy {gamma}-rays followed by the acidification of the culture medium (pH 4.0). The {gamma}-irradiation induced a temporary decrease in cell densities of E. coli, but did not affect cell densities of the other species. The concentrations of chlorophyll a and ATP in the microcosm were not affected by the {gamma}-irradiation, and chlorophyll a concentrations in a Eu. gracilis cell were not affected, either. The acidification significantly decreased cell densities of T. thermophila, slightly decreased cell densities of E. coli, and slightly increased cell densities of Eu. gracilis. The concentrations of chlorophyll a and ATP in the microcosm were increased by the acidification, although chlorophyll a concentrations in a Eu. gracilis cell were decreased. The combined exposure to {gamma}-rays and acids temporarily decreased cell densities of E. coli, significantly decreased cell densities of T. thermophila, and slightly increased cell densities of Eu. gracilis. The concentrations of chlorophyll a and ATP in the microcosm were increased by the combined exposure, although chlorophyll a concentrations in a Eu. gracilis cell were decreased. The authors therefore conclude that combined exposure to {gamma}-rays and acids

  4. Extragalactic Gamma Ray Excess from Coma Supercluster Direction

    Indian Academy of Sciences (India)

    Pantea Davoudifar; S. Jalil Fatemi

    2011-09-01

    The origin of extragalactic diffuse gamma ray is not accurately known, especially because our suggestions are related to many models that need to be considered either to compute the galactic diffuse gamma ray intensity or to consider the contribution of other extragalactic structures while surveying a specific portion of the sky. More precise analysis of EGRET data however, makes it possible to estimate the diffuse gamma ray in Coma supercluster (i.e., Coma\\A1367 supercluster) direction with a value of ( > 30MeV) ≃ 1.9 × 10-6 cm-2 s-1, which is considered to be an upper limit for the diffuse gamma ray due to Coma supercluster. The related total intensity (on average) is calculated to be ∼ 5% of the actual diffuse extragalactic background. The calculated intensity makes it possible to estimate the origin of extragalactic diffuse gamma ray.

  5. Effect of Conversion Efficiency on Gamma-Ray Burst Energy

    Institute of Scientific and Technical Information of China (English)

    Lei Xu; Zi-Gao Dai

    2004-01-01

    Beaming effect makes it possible that gamma-ray bursts have a standard energy,but the gamma-ray energy release is sensitive to some parameters.Our attention is focused on the effect of the gamma ray conversion efficiency(ηγ),which may range between 0.01 and 0.9,and which probably has a random value for different GRBs under certain conditions.Making use of the afterglow data from the literature,we carried out a complete correction to the conical opening angle formula.Within the framework of the conical jet model,we ran a simple Monte Carlo simulation for random values of ηγ,and found that the gamma-ray energy release is narrowly clustered,whether we use a constant value of ηγ or random values for different gamma-ray bursts.

  6. Gamma-rays as probes of the Universe

    CERN Document Server

    Horns, Dieter

    2016-01-01

    The propagation of $\\gamma$ rays over very large distances provides new insights on the intergalactic medium and on fundamental physics. On their path to the Earth, $\\gamma$ rays can annihilate with diffuse infrared or optical photons of the intergalactic medium, producing $e^+ \\, e^-$ pairs. The density of these photons is poorly determined by direct measurements due to significant galactic foregrounds. Studying the absorption of $\\gamma$ rays from extragalactic sources at different distances allows the density of low-energy diffuse photons to be measured. Gamma-ray propagation may also be affected by new phenomena predicted by extensions of the Standard Model of particle physics. Lorentz Invariance is violated in some models of Quantum Gravity, leading to an energy-dependent speed of light in vacuum. From differential time-of-flight measurements of the most distant $\\gamma$-ray bursts and of flaring active galactic nuclei, lower bounds have been set on the energy scale of Quantum Gravity. Another effect tha...

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

    Science.gov (United States)

    Hjorth, Jens

    2013-06-13

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

  8. Review of GRANAT observations of gamma-ray bursts

    DEFF Research Database (Denmark)

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

    1995-01-01

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

  9. Gamma-ray Explosion in Multiple Compton Scattering Regime

    CERN Document Server

    Gong, Z; Shou, Y R; Qiao, B; Bulanov, S V; Esirkepov, T Zh; Bulanov, S S; Chen, C E; He, X T; Yan, X Q

    2016-01-01

    Gamma-ray explosion from near critical density (NCD) target irradiated by four symmetrical imploding laser pulses is numerically investigated. With peak intensities about $10^{23}$ W/cm$^2$, the laser pulses boost electron energy through direct laser acceleration, while pushing them inward with the ponderomotive force. After backscattering with counter-propagating laser, the accelerated electron will be trapped in the optical lattice or the electromagnetic standing waves (SW) created by the coherent overlapping of the laser pulses, and meanwhile emit gamma-ray photon in Multiple Compton Scattering regime, where electron acts as a medium to transfer energy from laser to gamma-ray. The energy conversion rate from laser pulses to gamma-ray can be as high as around 50\\%. It may become one of the most efficient gamma-ray sources in laboratory.

  10. Real-time airborne gamma-ray background estimation using NASVD with MLE and radiation transport for calibration

    Energy Technology Data Exchange (ETDEWEB)

    Kulisek, J.A., E-mail: Jonathan.Kulisek@pnnl.gov; Schweppe, J.E.; Stave, S.C.; Bernacki, B.E.; Jordan, D.V.; Stewart, T.N.; Seifert, C.E.; Kernan, W.J.

    2015-06-01

    Helicopter-mounted gamma-ray detectors can provide law enforcement officials the means to quickly and accurately detect, identify, and locate radiological threats over a wide geographical area. The ability to accurately distinguish radiological threat-generated gamma-ray signatures from background gamma radiation in real time is essential in order to realize this potential. This problem is non-trivial, especially in urban environments for which the background may change very rapidly during flight. This exacerbates the challenge of estimating background due to the poor counting statistics inherent in real-time airborne gamma-ray spectroscopy measurements. To address this challenge, we have developed a new technique for real-time estimation of background gamma radiation from aerial measurements without the need for human analyst intervention. The method can be calibrated using radiation transport simulations along with data from previous flights over areas for which the isotopic composition need not be known. Over the examined measured and simulated data sets, the method generated accurate background estimates even in the presence of a strong, {sup 60}Co source. The potential to track large and abrupt changes in background spectral shape and magnitude was demonstrated. The method can be implemented fairly easily in most modern computing languages and environments.

  11. Real-time airborne gamma-ray background estimation using NASVD with MLE and radiation transport for calibration

    Science.gov (United States)

    Kulisek, J. A.; Schweppe, J. E.; Stave, S. C.; Bernacki, B. E.; Jordan, D. V.; Stewart, T. N.; Seifert, C. E.; Kernan, W. J.

    2015-06-01

    Helicopter-mounted gamma-ray detectors can provide law enforcement officials the means to quickly and accurately detect, identify, and locate radiological threats over a wide geographical area. The ability to accurately distinguish radiological threat-generated gamma-ray signatures from background gamma radiation in real time is essential in order to realize this potential. This problem is non-trivial, especially in urban environments for which the background may change very rapidly during flight. This exacerbates the challenge of estimating background due to the poor counting statistics inherent in real-time airborne gamma-ray spectroscopy measurements. To address this challenge, we have developed a new technique for real-time estimation of background gamma radiation from aerial measurements without the need for human analyst intervention. The method can be calibrated using radiation transport simulations along with data from previous flights over areas for which the isotopic composition need not be known. Over the examined measured and simulated data sets, the method generated accurate background estimates even in the presence of a strong, 60Co source. The potential to track large and abrupt changes in background spectral shape and magnitude was demonstrated. The method can be implemented fairly easily in most modern computing languages and environments.

  12. More Gamma-ray Bursts from the Fermi Gamma-ray Burst Monitor

    Science.gov (United States)

    Briggs, Michael; Fermi GBM Team Team

    2017-01-01

    The Fermi Gamma-ray Burst Monitor (GBM) Team has developed an offline search for weak gamma-ray bursts which were not already detected in-orbit as ``triggers''. This search is ``untargeted'', searching all of the GBM data without guidance from other observations. The initial version of the search has been operational from January 2016, finding several likely short GRBs per month that are posted to a webpage. The GBM individual photon data are binned to various timescales, a background model is created and the binned data are searched for significant signals above the background that are coincident in two or more detectors. The current search has a latency of several days because several steps require manual intervention. An improved version will be fully automatic so that the latency in detecting candidates will be dominated by the few hours delay in receiving the data. The new version of the search will also include additional detection algorithms to increase the GRB detection rate and will also detect some long GRBs. We will report the candidates via the Gamma-ray Coordinates Network (GCN). These prompt GRB detections and localization should aid multi-messenger observations, in some cases refining localizations on timescales useful for followup observations.

  13. A standard Fricke dosimeter compared to an ionization chamber used for dosimetric characterization of 60Co photon beam

    Science.gov (United States)

    Moussous, Ouiza; Medjadj, Toufik

    2016-06-01

    The main objective of this study was to investigate the Fricke dosimeter water equivalent system for measurement of dosimetric parameters for photon beam. The parameters measured with the Fricke dosimeter were compared to those obtained with an ionization chamber. In this work characteristics for 60Co γ-rays of field sizes ranging from 5 × 5 cm2 to 20 × 20 cm2 are reported. The measurements were carried out in the secondary standard dosimetry laboratory using a collimated 60Co gamma source therapy unit. The 60Co beam output in terms of absorbed dose to water was obtained as per IAEA TRS 398 recommendations using cylindrical ionization chamber, whose ND,w has been supplied by the IAEA's reference laboratory. Specific quantities measured include: output factors, peak scatter factor, lateral beam profiles and percentage depth dose. The Fricke dosimeters were irradiated in a water phantom using the suitable poly (methyl methacrylate), PMMA stand. Our results demonstrate that Fricke dosimeter and ionization chamber agree with each other.

  14. The SVOM gamma-ray burst mission

    CERN Document Server

    Cordier, B; Atteia, J -L; Basa, S; Claret, A; Daigne, F; Deng, J; Dong, Y; Godet, O; Goldwurm, A; Götz, D; Han, X; Klotz, A; Lachaud, C; Osborne, J; Qiu, Y; Schanne, S; Wu, B; Wang, J; Wu, C; Xin, L; Zhang, B; Zhang, S -N

    2015-01-01

    We briefly present the science capabilities, the instruments, the operations, and the expected performance of the SVOM mission. SVOM (Space-based multiband astronomical Variable Objects Monitor) is a Chinese-French space mission dedicated to the study of Gamma-Ray Bursts (GRBs) in the next decade. The SVOM mission encompasses a satellite carrying four instruments to detect and localize the prompt GRB emission and measure the evolution of the afterglow in the visible band and in X-rays, a VHF communication system enabling the fast transmission of SVOM alerts to the ground, and a ground segment including a wide angle camera and two follow-up telescopes. The pointing strategy of the satellite has been optimized to favor the detection of GRBs located in the night hemisphere. This strategy enables the study of the optical emission in the first minutes after the GRB with robotic observatories and the early spectroscopy of the optical afterglow with large telescopes to measure the redshifts. The study of GRBs in the...

  15. Blueshifting may explain the gamma ray bursts

    CERN Document Server

    Krasiński, Andrzej

    2015-01-01

    It is shown that the basic observed properties of the gamma-ray bursts (GRBs) are accounted for if one assumes that the GRBs arise by blueshifting the emission radiation of hydrogen and helium generated during the last scattering epoch. The blueshift generator for a single GRB is a Lema\\^{\\i}tre -- Tolman (L--T) region with a nonconstant bang-time function $t_B(r)$ matched into a Friedmann background. Blueshift visible to the observer arises \\textit{only on radial rays} that are emitted in the L--T region. The paper presents three L--T models with different Big Bang profiles, adapted for the highest and the lowest end of the GRB frequency range. The models account for: (1) The observed frequency range of the GRBs; (2) Their limited duration; (3) The afterglows; (4) Their hypothetical collimation into narrow jets; (5) The large distances to their sources; (6) The multitude of the observed GRBs. Properties (2), (3) and (6) are accounted for only qualitatively. With a small correction of the parameters of the mo...

  16. Egret observations of the extragalactic gamma-ray emission

    DEFF Research Database (Denmark)

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

    1998-01-01

    with the local interstellar gas and radiation, as well as an almost uniformly distributed component that is generally believed to originate outside the Galaxy. Through a careful study and removal of the Galactic diffuse emission, the flux, spectrum, and uniformity of the extragalactic emission are deduced......The all-sky survey in high-energy gamma rays (E > 30 MeV) carried out by EGRET aboard the Compton Gamma Ray Observatory provides a unique opportunity to examine in detail the diffuse gamma-ray emission. The observed diffuse emission has a Galactic component arising from cosmic-ray interactions...

  17. GammaLib - A new framework for the analysis of Astronomical Gamma-Ray Data

    CERN Document Server

    Knödlseder, Jürgen

    2011-01-01

    With the advent of a new generation of telescopes (INTEGRAL, Fermi, H.E.S.S., MAGIC, VERITAS, MILAGRO) and the prospects of planned observatories such as CTA or HAWC, gamma-ray astronomy is becoming an integral part of modern astrophysical research. Analysing gamma-ray data is still a major challenge, and today relies on a large diversity of tools and software frameworks that were specifically developed for each instrument. With the goal of facilitating and unifying the analysis of gamma-ray data, we are currently developing an innovative data analysis toolbox, called the GammaLib, that enables gamma-ray data analysis in an instrument independent way. We will present the basic ideas that are behind the GammaLib, and describe its architecture and usage.

  18. GammaLib: A New Framework for the Analysis of Astronomical Gamma-Ray Data

    Science.gov (United States)

    Knödlseder, J.

    2012-09-01

    With the advent of a new generation of telescopes (INTEGRAL, Fermi, H.E.S.S., MAGIC, VERITAS, MILAGRO) and the prospects of planned observatories such as CTA or HAWC, gamma-ray astronomy is becoming an integral part of modern astrophysical research. Analysing gamma-ray data is still a major challenge, and today relies on a large diversity of tools and software frameworks that were specifically developed for each instrument. With the goal of facilitating and unifying the analysis of gamma-ray data, we are currently developing an innovative data analysis toolbox, called the GammaLib, that enables gamma-ray data analysis in an instrument independent way. We will present the basic ideas that are behind the GammaLib, and describe its architecture and usage.

  19. Galactic sources of high energy neutrinos: Expectation from gamma-ray data

    CERN Document Server

    Sahakyan, N

    2015-01-01

    The recent results from ground based $\\gamma$-ray detectors (HESS, MAGIC, VERITAS) provide a population of TeV galactic $\\gamma$-ray sources which are potential sources of High Energy (HE) neutrinos. Since the $\\gamma$-rays and $\

  20. The Gamma-ray Albedo of the Moon

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-09-28

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

  1. Gamma-ray astronomy: From Fermi up to the HAWC high-energy {gamma}-ray observatory in Sierra Negra

    Energy Technology Data Exchange (ETDEWEB)

    Carraminana, Alberto [Instituto Nacional de Astrofisica, Optica y Electronica Luis Enrique Erro 1, Tonantzintla, Puebla 72840 (Mexico); 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.

  2. Gamma ray lines from a universal extra dimension

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-03-01

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

  3. Nonthermal gamma-ray and X-ray flashes from shock breakout in gamma-ray bursts/supernovae

    CERN Document Server

    Wang, X Y; Waxman, E; Mészáros, P; Wang, Xiang-Yu; Li, Zhuo; Waxman, Eli; Meszaros, Peter

    2006-01-01

    Thermal X-ray emission which is simultaneous with the prompt gamma-rays has been detected for the first time from a supernova connected with a gamma-ray burst (GRB), namely GRB060218/SN2006aj. It has been interpreted as arising from the breakout of a mildly relativistic, radiation-dominated shock from a dense stellar wind surrounding the progenitor star. There is also evidence for the presence of a mildly relativistic ejecta in GRB980425/SN1998bw, based on its X-ray and radio afterglow. Here we study the process of repeated bulk Compton scatterings of shock breakout thermal photons by the mildly relativistic ejecta. During the shock breakout process, a fraction of the thermal photons would be repeatedly scattered between the pre-shock material and the shocked material as well as the mildly relativistic ejecta and, as a result, the thermal photons get boosted to increasingly higher energies. This bulk motion Comptonization mechanism will produce nonthermal gamma-ray and X-ray flashes, which could account for t...

  4. Computers in activation analysis and gamma-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

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

    1979-01-01

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

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

    CERN Document Server

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

    2007-01-01

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

  6. Indirect dark matter searches in gamma and cosmic rays

    Science.gov (United States)

    Conrad, Jan; Reimer, Olaf

    2017-03-01

    Dark matter candidates such as weakly interacting massive particles are predicted to annihilate or decay into Standard Model particles, leaving behind distinctive signatures in gamma rays, neutrinos, positrons, antiprotons, or even antinuclei. Indirect dark matter searches, and in particular those based on gamma-ray observations and cosmic-ray measurements, could detect such signatures. Here we review the strengths and limitations of this approach and look into the future of indirect dark matter searches.

  7. Central Engine Memory of Gamma-Ray Bursts and Soft Gamma-Ray Repeaters

    Science.gov (United States)

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

    2016-04-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bin-Bin; Castro-Tirado, Alberto J. [Instituto de Astrofísica de Andalucá (IAA-CSIC), P.O. Box 03004, E-18080 Granada (Spain); Zhang, Bing, E-mail: zhang.grb@gmail.com [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States)

    2016-04-01

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

  9. The AGATA Spectrometer: next generation gamma-ray spectroscopy

    Science.gov (United States)

    Simpson, J.; AGATA Collaboration

    2015-05-01

    The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation gamma-ray spectrometer. AGATA is based on the technique of gamma-ray energy tracking in electrically segmented high-purity germanium crystals. The spectrometer will have an unparalleled level of detection power for electromagnetic nuclear radiation. The tracking technique requires the accurate determination of the energy, time and position of every interaction as a gamma ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realisation of gamma-ray tracking and AGATA is a result of many technical advances and the spectrometer is now operational. AGATA has been operated in a series of scientific campaigns at Legnaro National Laboratory in Italy and GSI in Germany and is presently being assembled at GANIL in France. The status of the instrument will be reviewed.

  10. Elastic scattering of gamma rays and X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Kane, P.P. [Physics Department, Indian Institute of Technology, Powai, Mumbai 400076 (India)]. E-mail: ppkane@vsnl.com

    2005-12-15

    Studies of elastic gamma ray scattering were pursued independently by the groups of Prof. Ghose and the author for several decades in spite of somewhat meagre support. Several techniques for such studies developed by the two groups and some of the results obtained in the energy range from tens of keV to about 1.5 MeV are described briefly. The theoretical background necessary for understanding these results is also outlined. The results showed the importance of Modified Relativistic Form Factor (MRFF) approximation in the explanation of atomic Rayleigh scattering cross sections in the small angle regime and the necessity for an inclusion of real Delbrueck scattering amplitudes at large scattering angles. Dispersion corrections to form factor amplitudes or the so-called anomalous scattering factors are shown to be needed at photon energies close to electron binding energy thresholds. A few promising future extensions of such studies are indicated at the end.

  11. Gamma-ray induced variability in greengram

    Energy Technology Data Exchange (ETDEWEB)

    Verma, R.K.; Singh, D.P. (Gobind Ballabh Pant Univ. of Agriculture and Technology, Pantnagar (India))

    1984-04-01

    Dry seeds of 'Pusa Baisakhi' greengram (vigna radiata (Linn.) Wilczek) were exposed to /sup 60/CO at doses of 20, 30, 40 and 50 kR. The mean days to maturity, plant height, pods/cluster and 100-seed weight increased at all the doses except at 50 kR for days to maturity. There was a decrease in the mean number of seeds/pods, as well as in pods, clusters, seeds and yield/plant. The irradiated populations showed higher variance over the control at all doses in the M/sub 3/ generation.

  12. Study on mutation induced effect of gamma ray and DES on black bean phaseolus vulgaris

    Energy Technology Data Exchange (ETDEWEB)

    Le Thi Dinh; Pham Le Ha; Nguyen Van Toan; Le Xuan Tham [Nuclear Research Institute, Radiobiology Department, Dalat (Viet Nam)

    2001-03-01

    The study on mutation induced effect of gamma ray and DES on black bean Phaseolus vulgaris was carried out at Radiobiology Department, Nuclear Research Institute of Dalat. Dry seeds of variety No.1847 - Bonita - Cuba in set of 13 black bean varieties were irradiated with gamma ray from {sup 60}Co source at dose range from 150 Gy to 350 Gy and treated with DES at concentration from 0.1% to 0.3% in 2 hours for experiments in laboratory. The doses of 200, 250, 300 Gy and concentration of 0.2% DES in 2 hours were selected to treat dry seeds for experiments on the field. In populations of M{sub 1} generation, the height, number of branches and fruits per plant, number of seeds per fruit were decreased with increasing of irradiation doses. In populations of M{sub 2} generation, individual variants in leaf shape, chlorophyll, short stem, dwarf, early maturity, flowering in very short time were obtained and selected in all treatment cases. Mutation frequency at dose of 300 Gy was higher than that in other treatment cases, but ratio of sterility is also largest. The mutant lines of early maturity and short stem with flowering in very short time are promised materials for further studies. (author)

  13. GLAST and Ground-Based Gamma-Ray Astronomy

    Science.gov (United States)

    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.

  14. Development of irradiator {sup 60}Co sources

    Energy Technology Data Exchange (ETDEWEB)

    Mosca, Rodrigo C.; Moura, Eduardo S.; Zeituni, Carlos A.; Mathor, Monica B., E-mail: rcmosca@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    According to a recent report by the International Agency for Research on Cancer (IARC) / WHO (2008-2010), the global impact of cancer more than doubled in 30 years. In this report, it was estimated that occurred about 12 million new cancer cases and 7 million deaths. In Brazil in 2010, with estimates for the year 2011, point to the occurrence of 489,270 new cases of cancer. Among the possibilities for cancer treatment, radiotherapy is one of the most important therapeutic and resources used to combat it. However, inherent complications of treatment can occur such as tiredness, loss of appetite, radiodermatitis and in more extreme cases late radionecrosis. In order to reproduce a point of radionecrosis in the vicinity of radiodermatitis to mimic these effects in animals, producing a model for assessment of tissue repair, we propose the setting up of an irradiator source of collimated {sup 60}Co. The development of was based on 11 sources of {sup 60}Co with 1 mm thickness that were inserted by inference in stainless steel 'gate-source' screw (patent pending) and later adjusted in a cross-shaped arrangement reinforced so that the beam radiation is directed to a target point, saving for other regions around this target point. The main use of this irradiator with sources of {sup 60}Co is just one cause radionecrosis point (target point) of approximately 5 mm{sup 2} with a surrounding and adjacent area of radiodermatitis around about 8 to 10 mm{sup 2} in laboratory animals for subsequent coating with epidermal-dermal matrix populated by a cell culture of human fibroblasts, keratinocytes and mesenchymal stem cells. With that said, its use will be valuable for evaluation of curative treatments against the bone and radionecrosis or palliative treatment rather than as it is currently assumed. (author)

  15. NDA via gamma-ray active and passive computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Decman, D.J.; Martz, H.E.; Roberson, G.P.; Johansson, E.

    1996-10-01

    Gamma-ray-based computed tomography (CT) requires that two different measurements be made on a closed waste container. [MAR92 and ROB94] When the results from these two measurements are combined, it becomes possible to identify and quantify all detectable gamma-ray emitting radioisotopes within a container. All measurements are made in a tomographic manner, i.e., the container is moved sequentially through well- known and accurately reproducible translation, rotation, and elevation positions in order to obtain gamma-ray data that is reconstructed by computer into images that represent waste contents. [ROB94] The two measurements modes are called active (A) and passive (P) CT. In the ACT mode, a collimated gamma-ray source external to the waste container emits multiple, mono-energetic gamma rays that pass through the container and are detected on the opposite side. The attenuated gamma-rays transmitted are measured as a function of both energy and position of the container. Thus, container contents are `mapped` via the measured amount of attenuation suffered at each gamma-ray energy. In effect, a three dimensional (3D) image of gamma- ray attenuation versus waste content is obtained. In the PCT measurement mode, the external radioactive source is shuttered turned- off, and the waste container, is moved through similar positions used for the ACT measurements. However, this time the radiation detectors record any gamma-rays emitted by radioactive sources on the inside of the waste container. Thus, internal radioactive content is mapped or 3D-imaged in the same tomographic manner as the attenuating matrix materials were in the ACT measurement mode.

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

    DEFF Research Database (Denmark)

    Lund, Niels

    2003-01-01

    The most recent astrophysics mission of ESA is INTEGRAL, a mission dedicated to gamma-ray astronomy (Winkler et al. 2003). INTEGRAL carries two gamma-ray instruments: the imager, IBIS, and the spectrometer, SPI, and in addition an optical monitor, OMC, and an X-ray monitor, JEM-X. INTEGRAL is an ...

  17. Status of space-based gamma-ray astronomy

    CERN Document Server

    Buehler, Rolf

    2015-01-01

    Gamma-ray observations give us a direct view into the most extreme environments of the universe. They help us to study astronomical particle accelerators as supernovae remnants, pulsars, active galaxies or gamma-ray bursts and help us to understand the propagation of cosmic rays through our Milky Way. This article summarizes the status of gamma-ray observations from space; it is the write-up of a rapporteur talk given at the 34th ICRC in The Hague, The Netherlands. The primary instrument used in the presented studies is the Large Area Telescope on-board the Fermi Spacecraft, which images the whole gamma-ray sky at photon energies between 20 MeV and 2 TeV. The Fermi mission is currently in its 8th year of observations. This article will review many of the exciting discoveries made in this time, focusing on the most recent ones.

  18. Gamma-rays from pulsar wind nebulae in starburst galaxies

    Science.gov (United States)

    Mannheim, Karl; Elsässer, Dominik; Tibolla, Omar

    2012-07-01

    Recently, gamma-ray emission at TeV energies has been detected from the starburst galaxies NGC253 (Acero et al., 2009) [1] and M82 (Acciari et al., 2009) [2]. It has been claimed that pion production due to cosmic rays accelerated in supernova remnants interacting with the interstellar gas is responsible for the observed gamma rays. Here, we show that the gamma-ray pulsar wind nebulae left behind by the supernovae contribute to the TeV luminosity in a major way. A single pulsar wind nebula produces about ten times the total luminosity of the Sun at energies above 1 TeV during a lifetime of 105 years. A large number of 3 × 104 pulsar wind nebulae expected in a typical starburst galaxy at a distance of 4 Mpc can readily produce the observed TeV gamma rays.

  19. Detection of Gamma Rays From a Starburst Galaxy

    CERN Document Server

    Acero, F

    2009-01-01

    Starburst galaxies exhibit in their central regions a highly increased rate of supernovae, the remnants of which are thought to accelerate energetic cosmic rays up to energies of ~ 10^15 eV. We report the detection of gamma rays -- tracers of such cosmic rays -- from the starburst galaxy NGC 253 using the H.E.S.S. array of imaging atmospheric Cherenkov telescopes. The gamma-ray flux above 220 GeV is F = (5.5 +/- 1.0stat +/- 2.8sys) x 10^-13 ph. s-1 cm-2, implying a cosmic-ray density about three orders of magnitude larger than that in the center of the Milky Way. The fraction of cosmic-ray energy channeled into gamma rays in this starburst environment is 5 times larger than that in our Galaxy.

  20. Detection of gamma rays from a starburst galaxy.

    Science.gov (United States)

    Acero, F; Aharonian, F; Akhperjanian, A G; Anton, G; Barres de Almeida, U; Bazer-Bachi, A R; Becherini, Y; Behera, B; Bernlöhr, K; Bochow, A; Boisson, C; Bolmont, J; Borrel, V; Brucker, J; Brun, F; Brun, P; Bühler, R; Bulik, T; Büsching, I; Boutelier, T; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Chounet, L-M; Clapson, A C; Coignet, G; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubois, F; Dubus, G; Dyks, J; Dyrda, M; Egberts, K; Emmanoulopoulos, D; Espigat, P; Farnier, C; Fegan, S; Feinstein, F; Fiasson, A; Förster, A; Fontaine, G; Füssling, M; Gabici, S; Gallant, Y A; Gérard, L; Gerbig, D; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Göring, D; Hauser, D; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Hofverberg, P; Hoppe, S; Horns, D; Jacholkowska, A; de Jager, O C; Jahn, C; Jung, I; Katarzyński, K; Katz, U; Kaufmann, S; Kerschhaggl, M; Khangulyan, D; Khélifi, B; Keogh, D; Klochkov, D; Kluźniak, W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Lamanna, G; Lenain, J-P; Lohse, T; Marandon, V; Martineau-Huynh, O; Marcowith, A; Masbou, J; Maurin, D; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Moulin, E; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Olive, J-F; de Oña Wilhelmi, E; Orford, K J; Ostrowski, M; Panter, M; Paz Arribas, M; Pedaletti, G; Pelletier, G; Petrucci, P-O; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raubenheimer, B C; Raue, M; Rayner, S M; Reimer, O; Renaud, M; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Ruppel, J; Sahakian, V; Santangelo, A; Schlickeiser, R; Schöck, F M; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sikora, M; Skilton, J L; Sol, H; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Superina, G; Szostek, A; Tam, P H; Tavernet, J-P; Terrier, R; Tibolla, O; Tluczykont, M; van Eldik, C; Vasileiadis, G; Venter, C; Venter, L; Vialle, J P; Vincent, P; Vivier, M; Völk, H J; Volpe, F; Wagner, S J; Ward, M; Zdziarski, A A; Zech, A

    2009-11-20

    Starburst galaxies exhibit in their central regions a highly increased rate of supernovae, the remnants of which are thought to accelerate energetic cosmic rays up to energies of approximately 10(15) electron volts. We report the detection of gamma rays--tracers of such cosmic rays--from the starburst galaxy NGC 253 using the High Energy Stereoscopic System (H.E.S.S.) array of imaging atmospheric Cherenkov telescopes. The gamma-ray flux above 220 billion electron volts is F = (5.5 +/- 1.0(stat) +/- 2.8(sys)) x 10(-13) cm(-2) s(-1), implying a cosmic-ray density about three orders of magnitude larger than that in the center of the Milky Way. The fraction of cosmic-ray energy channeled into gamma rays in this starburst environment is five times as large as that in our Galaxy.

  1. Comprehensive Monitoring of Gamma-ray Bright Blazars. I. Statistical Study of Optical, X-ray, and Gamma-ray Spectral Slopes

    CERN Document Server

    Williamson, Karen E; Marscher, Alan P; Larionov, Valeri M; Smith, Paul S; Agudo, Iván; Arkharov, Arkady A; Blinov, Dmitry A; Casadio, Carolina; Efimova, Natalia V; Gómez, José L; Hagen-Thorn, Vladimir A; Joshi, Manasvita; Konstantinova, Tatiana S; Kopatskaya, Evgenia N; Larionova, Elena G; Larionova, Liudmilla V; Malmrose, Michael P; McHardy, Ian M; Molina, Sol N; Morozova, Daria A; Schmidt, Gary D; Taylor, Brian W; Troitsky, Ivan S

    2014-01-01

    We present $\\gamma$-ray, X-ray, ultraviolet, optical, and near-infrared light curves of 33 $\\gamma$-ray bright blazars over four years that we have been monitoring since 2008 August with multiple optical, ground-based telescopes and the Swift satellite, and augmented by data from the Fermi Gamma-ray Space Telescope and other publicly available data from Swift. The sample consists of 21 flat-spectrum radio quasars (FSRQs) and 12 BL Lac objects (BL Lacs). We identify quiescent and active states of the sources based on their $\\gamma$-ray behavior. We derive $\\gamma$-ray, X-ray, and optical spectral indices, $\\alpha_\\gamma$, $\\alpha_X$, and $\\alpha_o$, respectively ($F_\

  2. 60Coγ射线半身照射对非照射区域骨髓造血组织基质细胞衍生因子1表达的影响%Influences of 60Coγray irradiation on expression stromal cell derived factor-1 in bone marrow hematopoietic tissue of non-irradiation area in left-half-body ionizing irradiated mice

    Institute of Scientific and Technical Information of China (English)

    高作文; 杨龙; 陈乐如; 娄金书; 张国强; 李开信; 程天民

    2013-01-01

    Objective To invesligale the mouse bone marrow hemalopoielic functions in non-irradiation area after irradiated by way of left-half- body. Methods The 6-8-week male Kunming strain mice were randomly divided into normal control( NC) , total-body-irradiated( TBI) , left-half-body-irradiated( LHBI) , and total-body-shield-irradia-ted( TBSI) groups. Left-half-body-irradiated group was treated with two pieces of 5 cm x 8 cm x 16 cm overlapped lead bricks shielding right-side body and irradiated with 8. 0 Gy60Coγ-ray. The leukocyte in peripheral blood and the number of bone marrow hematopoietic cells( BMHCs) were studied, the concentration of SOD, MDA in mouse serum were measured, and the expression SDF-1 in bone marrow hematopoietic tissues were observed by the Western blotting method and laser scanning confocal microscope combined with immunohistochemistry. Results In the left-half-body irradiated condition, the leucocyte in peripheral blood and the BMHCs were diminished, the concentration of MDA was increased and the SOD was decreased in the mouse serum remarkably ( compared with NC, P <0. 01) ; In non-irradiation area, the SDF-1-positive cells and the expression SDF-1 in bone marrow hematopoietic tissues were reduced significantly. Conclusion Our study suggested that the local irradiation resulted in the decrease of SDF-1-positive cells and the decline expression SDF-1 in bone marrow hematopoietic tissues in non-irradiation area, and the increase of reactive oxygen or free radicals might play an important role in the abnormal expression of SDF-1 in BMHT and the injury of hematopoietic microenvironment.%目的 探讨局部电离辐射对小鼠非照射区域骨髓造血组织基质细胞衍生因子-1(SDF-1)表达的影响.方法 将6~8周龄雄性昆明小鼠随机分为健康对照组、全身照射组、全身屏蔽照射组以及左半身照射组4组,用铅屏蔽建立半身照射模型,以8.0 Gy 60Co γ射线照射,观察小鼠外周血白细胞和骨髓有核

  3. Low permeability asphalt concrete gamma ray shielding properties.

    Science.gov (United States)

    Binney, S E; Sykes, K L

    1997-01-01

    Energy-dependent gamma ray shielding properties were measured as a function of gamma ray energy for a low permeability asphalt concrete that is used as a cap to prevent water infiltration into radioactive waste sites. Experimental data were compared to ISO-PC point kernel shielding calculations. Calculated dose equivalent rates compared well with experimental values, especially considering the poor detector resolution involved. The shielding properties of the asphalt concrete closely resembled those of aluminum. The results presented can be used to determine the asphalt concrete thickness required to reduce dose equivalent rates from several gamma ray emitting radionuclides.

  4. The STACEE-32 Ground Based Gamma-ray Detector

    CERN Document Server

    Hanna, D S; Boone, L M; Chantell, M C; Conner, Z; Covault, C E; Dragovan, M; Fortin, P; Gregorich, D T; Hinton, J A; Mukherjee, R; Ong, R A; Oser, S; Ragan, K; Scalzo, R A; Schütte, D R; Theoret, C G; Tümer, T O; Williams, D A; Zweerink, J A

    2002-01-01

    We describe the design and performance of the Solar Tower Atmospheric Cherenkov Effect Experiment detector in its initial configuration (STACEE-32). STACEE is a new ground-based gamma ray detector using the atmospheric Cherenkov technique. In STACEE, the heliostats of a solar energy research array are used to collect and focus the Cherenkov photons produced in gamma-ray induced air showers. The large Cherenkov photon collection area of STACEE results in a gamma-ray energy threshold below that of previous detectors.

  5. The STACEE Ground-Based Gamma-Ray Detector

    CERN Document Server

    Gingrich, D M; Bramel, D; Carson, J; Covault, C E; Fortin, P; Hanna, D S; Hinton, J A; Jarvis, A; Kildea, J; Lindner, T; Müller, C; Mukherjee, R; Ong, R A; Ragan, K; Scalzo, R A; Theoret, C G; Williams, D A; Zweerink, J A

    2005-01-01

    We describe the design and performance of the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) in its complete configuration. STACEE uses the heliostats of a solar energy research facility to collect and focus the Cherenkov photons produced in gamma-ray induced air showers. The light is concentrated onto an array of photomultiplier tubes located near the top of a tower. The large Cherenkov photon collection area of STACEE results in a gamma-ray energy threshold below that of previous ground-based detectors. STACEE is being used to observe pulsars, supernova remnants, active galactic nuclei, and gamma-ray bursts.

  6. Fundamental Physics With Cosmic High-Energy Gamma Rays

    CERN Document Server

    De Angelis, Alessandro

    2016-01-01

    High-energy photons (above the MeV) are a powerful probe for astrophysics and for fundamental physics under extreme conditions. During the recent years, our knowledge of the high-energy gamma-ray sky has impressively progressed thanks to the advent of new detectors for cosmic gamma rays, at ground (H.E.S.S., MAGIC, VERITAS, HAWC) and in space (AGILE, Fermi). This presentation reviews the present status of the studies of fundamental physics problems with high-energy gamma rays, and discusses the expected experimental developments.

  7. Constraining gamma-ray propagation on cosmic distances

    CERN Document Server

    Biteau, Jonathan

    2013-01-01

    Studying the propagation of gamma rays on cosmological distances encompasses a variety of scientific fields, focusing on diffuse radiation fields such as the extragalactic background light, on the probe of the magnetism of the Universe on large scales, and on physics beyond the standard models of cosmology and particle physics. The measurements, constraints and hints from observations of gamma-ray blazars by airborne and ground-based instruments are briefly reviewed. These observations point to gamma-ray cosmology as one of the major science cases of the Cherenkov Telescope Array, CTA.

  8. Photon energy conversion efficiency in gamma-ray spectrometry.

    Science.gov (United States)

    Švec, Anton

    2016-01-01

    Photon energy conversion efficiency coefficient is presented as the ratio of total energy registered in the collected spectrum to the emitted photon energy. This parameter is calculated from the conventional gamma-ray histogram and in principle is not affected by coincidence phenomena. This feature makes it particularly useful for calibration and measurement of radionuclide samples at close geometries. It complements the number of efficiency parameters used in gamma-ray spectrometry and can partly change the view as to how the gamma-ray spectra are displayed and processed.

  9. Recent Topics on Very High Energy Gamma-ray Astronomy

    CERN Document Server

    Mori, Masaki

    2008-01-01

    With the advent of imaging atmospheric Cherenkov telescopes in late 1980's, ground-based observation of TeV gamma-rays came into reality after struggling trials by pioneers for twenty years, and the number of gamma-ray sources detected at TeV energies has increased to be over seventy now. In this review, recent findings from ground-based very-high-energy gamma-ray observations are summarized (as of 2008 March), and up-to-date problems in this research field are presented.

  10. The Multiwavelength View of Gamma-Ray Loud AGN

    Science.gov (United States)

    Venters, Tonia

    2011-01-01

    The gamma-ray sky observed by the Fermi Large Area Telescope (Fermi-LAT) encodes much information about the high-energy processes in the universe. Of the extragalactic sources sources resolved by the Fermi-LAT, blazars comprise the class of gamma-ray emitters with the largest number of identified members. Unresolved blazars are expected to contribute significantly to the diffuse extragalactic gamma-ray emission. However, blazars are also broadband emitters (from radio to TeV energies), and as such the multiwavelength study of blazars can provide insight into the high-energy processes of the universe.

  11. Gamma-Ray Spectral States of Galactic Black Hole Candidates

    CERN Document Server

    Grove, J E; Kroeger, R A; McNaron-Brown, K; Skibo, J G; Phlips, B F

    1998-01-01

    OSSE has observed seven transient black hole candidates: GRO J0422+32, GX339-4, GRS 1716-249, GRS 1009-45, 4U 1543-47, GRO J1655-40, and GRS 1915+105. Two gamma-ray spectral states are evident and, based on a limited number of contemporaneous X-ray and gamma-ray observations, these states appear to be correlated with X-ray states. The former three objects show hard spectra below 100 keV (photon number indices Gamma < 2) that are exponentially cut off with folding energy ~100 keV, a spectral form that is consistent with thermal Comptonization. This "breaking gamma-ray state" is the high-energy extension of the X-ray low, hard state. In this state, the majority of the luminosity is above the X-ray band, carried by photons of energy ~100 keV. The latter four objects exhibit a "power-law gamma-ray state" with a relatively soft spectral index (Gamma ~ 2.5-3) and no evidence for a spectral break. For GRO J1655-40, the lower limit on the break energy is 690 keV. GRS 1716-249 exhibits both spectral states, with th...

  12. Photospheric Emission in Gamma-Ray Bursts

    CERN Document Server

    Pe'er, Asaf

    2016-01-01

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

  13. Short-Duration Gamma-Ray Bursts

    CERN Document Server

    Berger, Edo

    2013-01-01

    Gamma-ray bursts (GRBs) display a bimodal duration distribution, with a separation between the short- and long-duration bursts at about 2 sec. The progenitors of long GRBs have been identified as massive stars based on their association with Type Ic core-collapse supernovae, their exclusive location in star-forming galaxies, and their strong correlation with bright ultraviolet regions within their host galaxies. Short GRBs have long been suspected on theoretical grounds to arise from compact object binary mergers (NS-NS or NS-BH). The discovery of short GRB afterglows in 2005, provided the first insight into their energy scale and environments, established a cosmological origin, a mix of host galaxy types, and an absence of associated supernovae. In this review I summarize nearly a decade of short GRB afterglow and host galaxy observations, and use this information to shed light on the nature and properties of their progenitors, the energy scale and collimation of the relativistic outflow, and the properties ...

  14. Sensitivity of HAWC to gamma ray bursts

    Science.gov (United States)

    Taboada, Ignacio; HAWC Collaboration

    2012-12-01

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

  15. The Nature of Gamma Ray Burst Supernovae

    CERN Document Server

    Cano, Zach

    2012-01-01

    Gamma Ray Bursts (GRBs) and Supernovae (SNe) are among the brightest and most energetic physical processes in the universe. It is known that core-collapse SNe arise from the gravitational collapse and subsequent explosion of massive stars (the progen- itors of nearby core-collapse SNe have been imaged and unambiguously identified). It is also believed that the progenitors of long-duration GRBs (L-GRBs) are massive stars, mainly due to the occurrence and detection of very energetic core-collapse su- pernovae that happen both temporally and spatially coincident with most L-GRBs. However many outstanding questions regarding the nature of these events exist: How massive are the progenitors? What evolutionary stage are they at when they explode? Do they exist as single stars or in binary systems (or both, and to what fractions)? The work presented in this thesis attempts to further our understanding at the types of progenitors that give rise to long-duration GRB supernovae (GRB-SNe). This work is based on optical ...

  16. Gamma-Ray Bursts: Should cosmologists care?

    Science.gov (United States)

    Laros, J. G.

    1996-03-01

    Gamma-Ray Burst (GRB) locations are distributed isotropically on the sky, but the intensity distribution of the bursts seems clearly incompatible with spatial homogeneity. Of the scenarios that attempt to provide an explanation, there are two that enjoy current popularity: (1) GRBs are produced by high-velocity neutron stars that have formed an extended (˜100 kpc) spherical halo or “corona” around our galaxy. (2) The bursters are at cosmological distances, with redshifts near unity for the weaker events. The major evidence used to argue for or against each of these scenarios remains inconclusive. Assuming, not unreasonably, that the cosmological scenario is correct, one can discuss the advantages and disadvantages of studying GRBs as opposed to other objects at moderate redshift. We find that the advantages of GRBs-high intensity, penetrating radiation, rapid variability, and no expected source evolution-are offset by observational difficulties pertaining to the extraction of cosmological information from GRB data. If the cosmological scenario proves to be correct and if the observational difficulties are overcome, then cosmologists certainly should care.

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

    DEFF Research Database (Denmark)

    Singh, K.; Gerward, Leif

    2002-01-01

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

  18. Sorption of {sup 60} Co on inorganic solids; Sorcion de {sup 60} Co en solidos inorganicos

    Energy Technology Data Exchange (ETDEWEB)

    Granados C, F.; Bulbulian G, S. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Mardel V, B. [UAM-I, 09340 Mexico D.F. (Mexico)

    2003-07-01

    The behavior of sorption of the {sup 60} Co in aqueous solution under static conditions to different values of pH of the aqueous solution (1, 3, 5, 7, and 10) on MgO, MnO{sub 2}, SnO, TiO{sub 2}, activated carbon and calcinate hydrotalcite was investigated. It was found that the best sorbents of the {sup 60} Co was the MnO{sub 2}, activated carbon and TiO{sub 2} whose sorption was incremented when increasing the pH value of the aqueous solutions, in the one case of the hydrated oxides, the {sup 60} Co interacted with the electrically charged surface of the sorbents that depends on the pH of the solution and of the point of zero charge (zpc) of the sorbent. (Author)

  19. Modifications of a method for low energy gamma-ray incident angle reconstruction in the GAMMA-400 gamma-ray telescope

    Science.gov (United States)

    Leonov, A. A.; Galper, A. M.; Topchiev, N. P.; Bonvicini, V.; Adriani, O.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Bakaldin, A. V.; Bobkov, S. G.; Boezio, M.; Dalkarov, O. D.; Egorov, A. E.; Glushkov, N. A.; Gorbunov, M. S.; Gusakov, Yu V.; Hnatyk, B. I.; Kadilin, V. V.; Kaplin, V. A.; Kheymits, M. D.; Korepanov, V. E.; Longo, F.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Moskalenko, I. V.; Naumov, P. Yu; Picozza, P.; Runtso, M. F.; Serdin, O. V.; Sparvoli, R.; Spillantini, P.; Stozhkov, Yu I.; Suchkov, S. I.; Taraskin, A. A.; Tavani, M.; Yurkin, Yu T.; Zverev, V. G.

    2017-01-01

    The GAMMA-400 gamma-ray telescope is designed to measure the gamma-ray fluxes in the energy range from ∼20 MeV to ∼1 TeV, performing a sensitive search for high-energy gamma-ray emission when annihilating or decaying dark matter particles. Such measurements will be also associated with the following scientific goals: searching for new and studying known Galactic and extragalactic discrete high-energy gamma-ray sources (supernova remnants, pulsars, accreting objects, microquasars, active galactic nuclei, blazars, quasars). It will be possible to study their structure with high angular resolution and measuring their energy spectra and luminosity with high-energy resolution; identify discrete gamma-ray sources with known sources in other energy ranges. The major advantage of the GAMMA-400 instrument is excellent angular and energy resolutions for gamma rays above 10 GeV. The gamma-ray telescope angular and energy resolutions for the main aperture at 100-GeV gamma rays are ∼0.01% and ∼1%, respectively. The motivation of presented results is to improve physical characteristics of the GAMMA-400 gamma-ray telescope in the energy range of ∼20-100 MeV, most unexplored range today. Such observations are crucial today for a number of high-priority problems faced by modern astrophysics and fundamental physics, including the origin of chemical elements and cosmic rays, the nature of dark matter, and the applicability range of the fundamental laws of physics. To improve the reconstruction accuracy of incident angle for low-energy gamma rays the special analysis of topology of pair-conversion events in thin layers of converter performed. Choosing the pair-conversion events with more precise vertical localization allows us to obtain significantly better angular resolution in comparison with previous and current space and ground-based experiments. For 50-MeV gamma rays the GAMMA-400 gamma-ray telescope angular resolution is better than 50.

  20. Gamma-Ray and Multiwavelength Emission from Blazars

    Indian Academy of Sciences (India)

    Meg Urry

    2011-03-01

    Blazars are now well understood as approaching relativistic jets aligned with the line of sight. The long-time uncertainty about the demographics of blazars is starting to become clearer: since the Fermi blazar sample includes a larger fraction of high-frequency peaked blazars (like the typical X-ray-selected blazars in, say, the Einstein Slew Survey sample) than did the higher-flux-limit EGRET blazar sample, these low-luminosity sources must be more common than their higher luminosity, low-frequency-peaked cousins. Blazar spectral energy distributions have a characteristic two-component form, with synchrotron radiation at radio through optical (UV, X-ray) frequencies and gamma-rays from X-ray through GeV (TeV) energies.Multiwavelength monitoring has suggested that gamma-ray flares can result from acceleration of electrons at shocks in the jet, and there appears to be an association between the creation of outflowing superluminal radio components in VLBI maps and the gamma-ray flares. In many cases, the gamma-ray emission is produced by inverse Compton upscattering of ambient optical-UV photons, although the contribution from energetic hadrons cannot be ruled out. The next few years of coordinated gamma-ray, X-ray, UV, optical, infrared and radio monitoring of blazars will be important for characterizing jet content, structure, and total power.

  1. The CALET Gamma-ray Burst Monitor (CGBM)

    CERN Document Server

    Yamaoka, Kazutaka; Sakamoto, Takanori; Takahashi, Ichiro; Hara, Takumi; Yamamoto, Tatsuma; Kawakubo, Yuta; Inoue, Ry ota; Terazawa, Shunsuke; Fujioka, Rie; Senuma, Kazumasa; Nakahira, Satoshi; Tomida, Hiroshi; Ueno, Shiro; Torii, Shoji; Cherry, Michael L; Ricciarini, Sergio

    2013-01-01

    The CALET Gamma-ray Burst Monitor (CGBM) is the secondary scientific instrument of the CALET mission on the International Space Station (ISS), which is scheduled for launch by H-IIB/HTV in 2014. The CGBM provides a broadband energy coverage from 7 keV to 20 MeV, and simultaneous observations with the primary instrument Calorimeter (CAL) in the GeV - TeV gamma-ray range and Advanced Star Camera (ASC) in the optical for gamma-ray bursts (GRBs) and other X-gamma-ray transients. The CGBM consists of two kinds of scintillators: two LaBr$_3$(Ce) (7 keV - 1 MeV) and one BGO (100 keV - 20 MeV) each read by a single photomultiplier. The LaBr$_3$(Ce) crystal, used in space for the first time here for celestial gamma-ray observations, enables GRB observations over a broad energy range from low energy X-ray emissions to gamma rays. The detector performance and structures have been verified using the bread-board model (BBM) via vibration and thermal vacuum tests. The CALET is currently in the development phase of the prot...

  2. Fermi: The Gamma-Ray Large Area Telescope

    Science.gov (United States)

    McEnery, Julie

    2015-01-01

    Following its launch in June 2008, high-energy gamma-ray observations by the Fermi Gamma-ray Space Telescope have unveiled over 1000 new sources and opened an important and previously unexplored window on a wide variety of phenomena. These have included the discovery of an population of pulsars pulsing only in gamma rays; the detection of photons up to 10s of GeV from gamma-ray bursts, enhancing our understanding of the astrophysics of these powerful explosions; the detection of hundreds of active galaxies; a measurement of the high energy cosmic-ray electron spectrum which may imply the presence of nearby astrophysical particle accelerators; the determination of the diffuse gamma-ray emission with unprecedented accuracy and the constraints on phenomena such as supersymmetric dark-matter annihilations and exotic relics from the Big Bang. Continuous monitoring of the high-energy gamma-ray sky has uncovered numerous outbursts from active galaxies and the discovery of transient sources in our galaxy. In this talk I will describe the current status of the Fermi observatory and review the science highlights from Fermi.

  3. Fermi: The Gamma-Ray Large Area Telescope Mission Status

    Science.gov (United States)

    McEnery, Julie

    2014-01-01

    Following its launch in June 2008, high-energy gamma-ray observations by the Fermi Gamma-ray Space Telescope have unveiled over 1000 new sources and opened an important and previously unexplored window on a wide variety of phenomena. These have included the discovery of an population of pulsars pulsing only in gamma rays; the detection of photons up to 10s of GeV from gamma-ray bursts, enhancing our understanding of the astrophysics of these powerful explosions; the detection of hundreds of active galaxies; a measurement of the high energy cosmic-ray electron spectrum which may imply the presence of nearby astrophysical particle accelerators; the determination of the diffuse gamma-ray emission with unprecedented accuracy and the constraints on phenomena such as supersymmetric dark-matter annihilations and exotic relics from the Big Bang. Continuous monitoring of the high-energy gamma-ray sky has uncovered numerous outbursts from active galaxies and the discovery of transient sources in our galaxy. In this talk I will describe the current status of the Fermi observatory and review the science highlights from Fermi.

  4. Fermi: The Gamma-Ray Large Area Space Telescope

    Science.gov (United States)

    McEnery, Julie

    2014-01-01

    Following its launch in June 2008, high-energy gamma-ray observations by the Fermi Gamma-ray Space Telescope have unveiled over 1000 new sources and opened an important and previously unexplored window on a wide variety of phenomena. These have included the discovery of an population of pulsars pulsing only in gamma rays; the detection of photons up to 10s of GeV from gamma-ray bursts, enhancing our understanding of the astrophysics of these powerful explosions; the detection of hundreds of active galaxies; a measurement of the high energy cosmic-ray electron spectrum which may imply the presence of nearby astrophysical particle accelerators; the determination of the diffuse gamma-ray emission with unprecedented accuracy and the constraints on phenomena such as supersymmetric dark-matter annihilations and exotic relics from the Big Bang. Continuous monitoring of the high-energy gamma-ray sky has uncovered numerous outbursts from active galaxies and the discovery of transient sources in our galaxy. In this talk I will describe the current status of the Fermi observatory and review the science highlights from Fermi.

  5. Gamma-ray Albedo of Small Solar System Bodies

    Energy Technology Data Exchange (ETDEWEB)

    Moskalenko, I.V.

    2008-03-25

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

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

    Energy Technology Data Exchange (ETDEWEB)

    1976-01-01

    The conference included papers on ..gamma..-ray pulsars, galactic diffuse flux and surveys, radio surveys of external galaxies, galactic distribution of pulsars, and galactic gamma emission. Galactic structure drawing on all branches of galactic astronomy is discussed. New and unpublished material is included. (JFP)

  7. Wavelet-Based Techniques for the Gamma-Ray Sky

    CERN Document Server

    McDermott, Samuel D; Cholis, Ilias; Lee, Samuel K

    2015-01-01

    We demonstrate how the image analysis technique of wavelet decomposition can be applied to the gamma-ray sky to separate emission on different angular scales. New structures on scales that differ from the scales of the conventional astrophysical foreground and background uncertainties can be robustly extracted, allowing a model-independent characterization with no presumption of exact signal morphology. As a test case, we generate mock gamma-ray data to demonstrate our ability to extract extended signals without assuming a fixed spatial template. For some point source luminosity functions, our technique also allows us to differentiate a diffuse signal in gamma-rays from dark matter annihilation and extended gamma-ray point source populations in a data-driven way.

  8. Gamma-ray flares from the Crab Nebula.

    Science.gov (United States)

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

    2011-02-11

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

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

    Data.gov (United States)

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

  10. Gamma-ray emission from individual classical novae

    CERN Document Server

    Gómez-Gomar, J; José, J; Isern, J

    1997-01-01

    Classical novae are important producers of radioactive nuclei, such as be7, n13, f18, na22 and al26. The disintegration of these nuclei produces positrons (except for be7) that through annihilation with electrons produce photons of energies 511 keV and below. Furthermore, be7 and na22 decay producing photons with energies of 478 keV and 1275 keV, respectively, well in the gamma-ray domain. Therefore, novae are potential sources of gamma-ray emission. The properties of gamma-ray spectra and gamma-ray light curves (for the continuum and for the lines at 511, 478 and 1275 keV) have been analyzed, with a special emphasis on the difference between carbon-oxygen and oxygen-neon novae. Predictions of detectability of individual novae by the future SPI spectrometer on board the INTEGRAL satellite are made.

  11. Fireball and cannonball models of gamma ray bursts confront observations

    OpenAIRE

    Dar, Arnon

    2005-01-01

    The two leading contenders for the theory of gamma-ray bursts (GRBs) and their afterglows, the Fireball and Cannonball models, are compared and their predictions are confronted, within space limitations, with key GRB observations, including recent observations with SWIFT

  12. Prompt Optical Observations of $\\gamma$-ray Bursts

    CERN Document Server

    Akerlof, Carl W; Barthelmy, S D; Bloch, J; Butterworth, P S; Casperson, D E; Cline, T; Fletcher, S; Frontera, F; Gisler, G; Heise, J; Hills, J; Hurley, K; Kehoe, R; Lee, B; Marshall, S; McKay, T; Pawl, A; Piro, L; Szymanski, J J; Wren, J; Akerlof, Carl; Balsano, Richard; Barthelmy, Scott; Bloch, Jeff; Butterworth, Paul; Casperson, Don; Cline, Tom; Fletcher, Sandra; Frontera, Fillippo; Gisler, Galen; Heise, John; Hills, Jack; Hurley, Kevin; Kehoe, Robert; Lee, Brian; Marshall, Stuart; Kay, Tim Mc; Pawl, Andrew; Piro, Luigi; Szymanski, John; Wren, Jim

    2000-01-01

    The Robotic Optical Transient Search Experiment (ROTSE) seeks to measure simultaneous and early afterglow optical emission from gamma-ray bursts (GRBs). A search for optical counterparts to six GRBs with localization errors of 1 square degree or better produced no detections. The earliest limiting sensitivity is m(ROTSE) > 13.1 at 10.85 seconds (5 second exposure) after the gamma-ray rise, and the best limit is m(ROTSE) > 16.0 at 62 minutes (897 second exposure). These are the most stringent limits obtained for GRB optical counterpart brightness in the first hour after the burst. Consideration of the gamma-ray fluence and peak flux for these bursts and for GRB990123 indicates that there is not a strong positive correlation between optical flux and gamma-ray emission.

  13. Location and origin of gamma-rays in blazars

    CERN Document Server

    Rani, B; Hodgson, J A; Zensus, J A

    2016-01-01

    One of the most intriguing and challenging quests of current astrophysics is to understand the physical conditions and processes responsible for production of high-energy particles, and emission of \\gamma-rays. A combination of high-resolution Very Long Baseline Interferometry (VLBI) images with broadband flux variability measurements is a unique way to probe the emission mechanisms at the bases of jets. Our analysis of \\gamma-ray flux variability observed by the Fermi-LAT (Large Area Telescope) along with the parsec-scale jet kinematics suggests that the $\\gamma$-ray emission in blazar S5 0716+714 has a significant correlation with the mm-VLBI core flux and the orientation of jet outflow on parsec scales. These results indicate that the inner jet morphology has a tight connection with the observed $\\gamma$-ray flares. An overview of our current understanding on high-energy radiation processes, their origin, and location is presented here.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-07-01

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

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

    Indian Academy of Sciences (India)

    Samit Mandal; J Gerl; H Geissel; K Hauschild; M Hellström; Z Janas; I Kojouharov; Y Kopatch; R C Lemmon; P Mayet; Z Podolyak; P H Regan; H Schaffner; C Schlegel; J Simpson; H J Wollersheim

    2001-07-01

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

  16. Gamma-Ray Imager Polarimeter for Solar Flares Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose here to develop the Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS), the next-generation instrument for high-energy solar observations. GRIPS will...

  17. Diagnosing inertial confinement fusion gamma ray physics (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, H. W.; Hoffman, N.; Wilson, D. C.; Kim, Y. H.; McEvoy, A.; Young, C. S.; Mack, J. M. [Los Alamos National Laboratory, P.O. Box 1663, M/S E526, Los Alamos, New Mexico 87545 (United States); Stoeffl, W.; Dauffy, L. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Horsfield, C. J.; Rubery, M. [Atomic Weapons Establishment, Aldermaston, Reading RG7 4PR (United Kingdom); Miller, E. K. [Special Technologies Laboratory, NSTec, Santa Barbara, California 93111 (United States); Ali, Z. A. [Livermore Operations, NSTec, Livermore, California 94550 (United States)

    2010-10-15

    The gamma reaction history (GRH) diagnostic is a multichannel, time-resolved, energy-thresholded {gamma}-ray spectrometer that provides a high-bandwidth, direct-measurement of fusion reaction history in inertial confinement fusion implosion experiments. 16.75 MeV deuterium+tritium (DT) fusion {gamma}-rays, with a branching ratio of the order of 10{sup -5}{gamma}/(14 MeV n), are detected to determine fundamental burn parameters, such as nuclear bang time and burn width, critical to achieving ignition at the National Ignition Facility. During the tritium/hydrogen/deuterium ignition tuning campaign, an additional {gamma}-ray line at 19.8 MeV, produced by hydrogen+tritium fusion with a branching ratio of unity, will increase the available {gamma}-ray signal and may allow measurement of reacting fuel composition or ion temperature. Ablator areal density measurements with the GRH are also made possible by detection of 4.43 MeV {gamma}-rays produced by inelastic scatter of DT fusion neutrons on {sup 12}C nuclei in the ablating plastic capsule material.

  18. Photocatalysis degradation of ethylene with γ-ray irradiated modified silver-doped TiO2%60Co-γ辐照改性银掺杂纳米TiO2及光催化降解乙烯

    Institute of Scientific and Technical Information of China (English)

    沈生文; 叶盛英; 宋贤良; 李明波; 方一超

    2012-01-01

    为了解60Co-γ射线辐照且以活性炭纤维(ACF)为载体所负载TiO2的半导体材料(TiO2/ACF)对光催化降解冷藏环境中乙烯的影响,该文拟采用60Co-γ辐照制备纳米Ag沉积的TiO2/ACF (Ag-TiO2/ACF)光催化材料,在模拟园艺产品的冷藏环境中,进行了3种不同膜的光催化降解乙烯效果的研究,并利用场发射扫描电镜(FESEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)对所制备的光催化材料进行相关的表征分析.结果表明:在加入分散剂聚乙烯吡咯烷酮后,60C0-γ辐照能使Ag颗粒较好地负载在TiO2上,TiO2均匀分散在ACF膜上而不发生团聚,且TiO2颗粒晶相改变、尺寸变小,有助于提高Ag-TiO2/ACF的催化效率.Ag-TiO2/ACF光催化降解乙烯的效果用一级动力学速率方程描述;经辐照制备的Ag-TiO2/ACF薄膜比未辐照的TiO2/ACF和辐照的TiO2/ACF薄膜光催化降解乙烯的反应速率常数分别提高了44%和37%.研究结果为TiO2光催化技术的进一步的应用提供了参考.%In order to investigate the effect of TiO2 irradiated by 60Co-y ray and loaded by activated carbon fibers on photocatalytic degradation of ethylene in the environment of cold storage, the TiCVACF photocatalytic materials deposited with nano-Ag (Ag-TiO2/ACF) irradiated by 60Co-y ray were prepared, and effects of three different films on the photocatalytic degradation rate of ethylene were investigated in the simulated cold storage environment for horticultural products. Environmental Scanning Electron Microscope (ESEM), Field Scanning Electron Microscope (FESEM) and X-ray diffractometer (XRD) were used to analyze the characterizations of the prepared Ag-TiO2/ACF. Results showed that: 60Co-y ray could make Ag load on the surface of TiO2 well and TiO2 could be dispersed on the ACF uniformly after adding the dispersant of polyethylene pyrrolidone, which could effectively prevent the aggregation of the nano-particles. The average particle size of TiO2

  19. Dark matter properties implied by gamma ray interstellar emission models

    OpenAIRE

    Balázs, Csaba; Li, Tong

    2016-01-01

    We infer dark matter properties from gamma ray residuals extracted using eight different interstellar emission scenarios proposed by the Fermi-LAT Collaboration to explain the Galactic Center gamma ray excess. Adopting the most plausible simplified ansatz, we assume that the dark matter particle is a Majorana fermion interacting with standard fermions via a scalar mediator. Using this theoretical hypothesis and the Fermi residuals we calculate Bayesian evidences, including Fermi-LAT exclusion...

  20. $\\gamma$-rays and neutrinos from dark matter

    CERN Document Server

    Stecker, F W

    1996-01-01

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

  1. Searches for Axionlike Particles Using Gamma-Ray Observations

    CERN Document Server

    Meyer, Manuel

    2016-01-01

    Axionlike particles (ALPs) are a common prediction of theories beyond the Standard Model of particle physics that could explain the entirety of the cold dark matter. These particles could be detected through their mixing with photons in external electromagnetic fields. Here, we provide a short review over ALP searches that utilize astrophysical $\\gamma$-ray observations. We summarize current bounds as well as future sensitivities and discuss the possibility that ALPs alter the $\\gamma$-ray opacity of the Universe.

  2. Constraining gamma-ray propagation on cosmic distances

    OpenAIRE

    Biteau, Jonathan

    2013-01-01

    Studying the propagation of gamma rays on cosmological distances encompasses a variety of scientific fields, focusing on diffuse radiation fields such as the extragalactic background light, on the probe of the magnetism of the Universe on large scales, and on physics beyond the standard models of cosmology and particle physics. The measurements, constraints and hints from observations of gamma-ray blazars by airborne and ground-based instruments are briefly reviewed. These observations point ...

  3. Physics and astrophysics with gamma-ray telescopes

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-15

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

  4. Significant gamma-ray lines from dark matter annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Duerr, Michael [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Fileviez Perez, Pavel; Smirnov, Juri [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany)

    2016-07-01

    Gamma-ray lines from dark matter annihilation are commonly seen as a ''smoking gun'' for the particle nature of dark matter. However, in many dark matter models the continuum background from tree-level annihilations makes such a line invisible. I present two simple extensions of the Standard Model where the continuum contributions are suppressed and the gamma-ray lines are easily visible over the continuum background.

  5. Development and performance of a gamma-ray imaging detector

    Science.gov (United States)

    Gálvez, J. L.; Hernanz, M.; Álvarez, J. M.; La Torre, M.; Álvarez, L.; Karelin, D.; Lozano, M.; Pellegrini, G.; Ullán, M.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

    2012-09-01

    In the last few years we have been working on feasibility studies of future instruments in the gamma-ray range, from several keV up to a few MeV. The innovative concept of focusing gamma-ray telescopes in this energy range, should allow reaching unprecedented sensitivities and angular resolution, thanks to the decoupling of collecting area and detector volume. High sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators, e.g., Supernovae, Classical Novae, Supernova Remnants (SNRs), Gamma-Ray Bursts (GRBs), Pulsars, Active Galactic Nuclei (AGN). In order to achieve the needed performance, a gamma-ray imaging detector with mm spatial resolution and large enough efficiency is required. In order to fulfill the combined requirement of high detection efficiency with good spatial and energy resolution, an initial prototype of a gamma-ray imaging detector based on CdTe pixel detectors is being developed. It consists of a stack of several layers of CdTe detectors with increasing thickness, in order to enhance the gamma-ray absorption in the Compton regime. A CdTe module detector lies in a 11 x 11 pixel detector with a pixel pitch of 1mm attached to the readout chip. Each pixel is bump bonded to a fan-out board made of alumina (Al2O3) substrate and routed to the corresponding input channel of the readout ASIC to measure pixel position and pulse height for each incident gamma-ray photon. We will report the main features of the gamma-ray imaging detector performance such as the energy resolution for a set of radiation sources at different operating temperatures.

  6. Gamma-Ray Burst Class Properties

    Science.gov (United States)

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

    2000-01-01

    Guided by the supervised pattern recognition algorithm C4.5 developed by Quinlan in 1986, we examine the three gamma-ray burst classes identified by Mukherjee et al. in 1998. C4.5 provides strong statistical support for this classification. However, with C4.5 and our knowledge of the Burst and Transient Source Experiment (BATSE) instrument, we demonstrate that class 3 (intermediate fluence, intermediate duration, soft) does not have to be a distinct source population: statistical/systematic errors in measuring burst attributes combined with the well-known hardness/intensity correlation can cause low peak flux class 1 (high fluence, long, intermediate hardness) bursts to take on class 3 characteristics naturally. Based on our hypothesis that the third class is not a distinct one, we provide rules so that future events can be placed in either class 1 or class 2 (low fluence, short, hard). We find that the two classes are relatively distinct on the basis of Band's work in 1993 on spectral parameters alpha, beta, and E (sub peak) alone. Although this does not indicate a better basis for classification, it does suggest that different physical conditions exist for class 1 and class 2 bursts. In the process of studying burst class characteristics, we identify a new bias affecting burst fluence and duration measurements. Using a simple model of how burst duration can be underestimated, we show how this fluence duration bias can affect BATSE measurements and demonstrate the type of effect it can have on the BATSE fluence versus peak flux diagram.

  7. Localization of Gamma-Ray Bursts using the Fermi Gamma-Ray Burst Monitor

    CERN Document Server

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

    2014-01-01

    The Fermi Gamma-ray Burst Monitor (GBM) has detected over 1400 Gamma-Ray Bursts (GRBs) since it began science operations in July, 2008. We use a subset of over 300 GRBs localized by instruments such as Swift, the Fermi Large Area Telescope, INTEGRAL, and MAXI, or through triangulations from the InterPlanetary Network (IPN), to analyze the accuracy of GBM GRB localizations. We find that the reported statistical uncertainties on GBM localizations, which can be as small as 1 degree, underestimate the distance of the GBM positions to the true GRB locations and we attribute this to systematic uncertainties. The distribution of systematic uncertainties is well represented (68% confidence level) by a 3.7 degree Gaussian with a non-Gaussian tail that contains about 10% of GBM-detected GRBs and extends to approximately 14 degrees. A more complex model suggests that there is a dependence of the systematic uncertainty on the position of the GRB in spacecraft coordinates, with GRBs in the quadrants on the Y-axis better l...

  8. LOCALIZATION OF GAMMA-RAY BURSTS USING THE FERMI GAMMA-RAY BURST MONITOR

    Energy Technology Data Exchange (ETDEWEB)

    Connaughton, V.; Briggs, M. S.; Burgess, J. M. [CSPAR and Physics Department, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Goldstein, A.; Wilson-Hodge, C. A. [Astrophysics Office, ZP12, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Meegan, C. A.; Jenke, P.; Pelassa, V.; Xiong, S.; Bhat, P. N. [CSPAR, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Paciesas, W. S. [Universities Space Research Association, Huntsville, AL (United States); Preece, R. D. [Department of Space Science, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Gibby, M. H. [Jacobs Technology, Inc., Huntsville, AL (United States); Greiner, J.; Yu, H.-F. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Gruber, D. [Planetarium Südtirol, Gummer 5, I-39053 Karneid (Italy); Kippen, R. M. [Los Alamos National Laboratory, NM 87545 (United States); Byrne, D.; Fitzpatrick, G.; Foley, S., E-mail: valerie@nasa.gov [School of Physics, University College Dublin, Belfield, Stillorgan Road, Dublin 4 (Ireland); and others

    2015-02-01

    The Fermi Gamma-ray Burst Monitor (GBM) has detected over 1400 gamma-ray bursts (GRBs) since it began science operations in 2008 July. We use a subset of over 300 GRBs localized by instruments such as Swift, the Fermi Large Area Telescope, INTEGRAL, and MAXI, or through triangulations from the InterPlanetary Network, to analyze the accuracy of GBM GRB localizations. We find that the reported statistical uncertainties on GBM localizations, which can be as small as 1°, underestimate the distance of the GBM positions to the true GRB locations and we attribute this to systematic uncertainties. The distribution of systematic uncertainties is well represented (68% confidence level) by a 3.°7 Gaussian with a non-Gaussian tail that contains about 10% of GBM-detected GRBs and extends to approximately 14°. A more complex model suggests that there is a dependence of the systematic uncertainty on the position of the GRB in spacecraft coordinates, with GRBs in the quadrants on the Y axis better localized than those on the X axis.

  9. Airborne Gamma-Ray Survey RISØ 2004

    DEFF Research Database (Denmark)

    Aage, Helle Karina

    The aim of the described survey was to monitor the gamma radiation originating from the waste disposal deposits and the now closed reactor.......The aim of the described survey was to monitor the gamma radiation originating from the waste disposal deposits and the now closed reactor....

  10. Micro-Slit Collimators for X-ray/Gamma-ray Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mikro Systems, Inc. (MSI) will advance the state-of-the-art in high resolution, high-aspect-ratio x-ray/gamma-ray collimator fabrication into the micro-slit regime...

  11. Late Time Emission of Prompt Fission Gamma Rays

    CERN Document Server

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

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Atwood, W. B. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Baldini, L. [Universita di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bregeon, J.; Pesce-Rollins, M.; Sgro, C.; Tinivella, M. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bruel, P. [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France); Chekhtman, A. [Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030 (United States); Cohen-Tanugi, J. [Laboratoire Univers et Particules de Montpellier, Universite Montpellier 2, CNRS/IN2P3, F-34095 Montpellier (France); Drlica-Wagner, A.; Omodei, N.; Rochester, L. S.; Usher, T. L. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Granot, J. [Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Ra' anana 43537 (Israel); Longo, F. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Razzaque, S. [Department of Physics, University of Johannesburg, Auckland Park 2006 (South Africa); Zimmer, S., E-mail: melissa.pesce.rollins@pi.infn.it, E-mail: nicola.omodei@stanford.edu, E-mail: granot@openu.ac.il [Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm (Sweden)

    2013-09-01

    Based on the experience gained during the four and a half years of the mission, the Fermi-LAT Collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet finalized, we can test the improvements in the new event reconstruction with the special case of the prompt phase of bright gamma-ray bursts (GRBs), where the signal-to-noise ratio is large enough that loose selection cuts are sufficient to identify gamma rays associated with the source. Using the new event reconstruction, we have re-analyzed 10 GRBs previously detected by the Large Area Telescope (LAT) for which an X-ray/optical follow-up was possible and found four new gamma rays with energies greater than 10 GeV in addition to the seven previously known. Among these four is a 27.4 GeV gamma ray from GRB 080916C, which has a redshift of 4.35, thus making it the gamma ray with the highest intrinsic energy ({approx}147 GeV) detected from a GRB. We present here the salient aspects of the new event reconstruction and discuss the scientific implications of these new high-energy gamma rays, such as constraining extragalactic background light models, Lorentz invariance violation tests, the prompt emission mechanism, and the bulk Lorentz factor of the emitting region.

  13. Thermal neutron fluence from ultra low-level gamma-ray spectrometry of spoons activated during the JCO criticality accident at Tokai-mura in 1999.

    Science.gov (United States)

    Hult, Mikael; Martínez Canet, María Jose; Johnston, Peter N; Komura, Kazuhisa

    2002-01-01

    During the JCO-accident in Tokai-mura in 1999, the surrounding village was irradiated by an uncontrolled neutron flux. At some locations in that village, the thermal neutron flux was determined retrospectively by measurement of the very low activity of 51Cr and 60Co in stainless-steel spoons using gamma-ray spectrometry in underground laboratories. Activities determined in the HADES underground facility are presented here, together with calibrations performed using a well-defined thermal neutron flux to directly estimate the fluence of thermal neutrons independent of most assumptions. The results show measurable 51Cr in three samples and 60Co in four samples taken from locations at distances of up to 430m from the accident location despite the elapse of 4 half-lives of 51Cr before measurement. Effects of air transport of the samples were considered and shown to be negligible.

  14. Gamma-ray luminosity function of gamma-ray bright AGNs

    Institute of Scientific and Technical Information of China (English)

    Debbijoy Bhattacharya; P. Sreekumar; R. Mukherjee

    2009-01-01

    Detection of γ-ray emissions from a class of active galactic nuclei (viz blazars),has been one of the important findings from the Compton Gamma-Ray Observatory (CGRO). However, their-γ-ray luminosity function has not been well determined. Few at-tempts have been made in earlier works, where BL Lacs and Flat Spectrum Radio Quasars (FSRQs) have been considered as a single source class. In this paper, we investigated the evolution and γ-ray luminosity function of FSRQs and BL Lacs separately. Our investi-gation indicates no evolution for BL Lacs, however FSRQs show significant evolution. Pure luminosity evolution is assumed for FSRQs and exponential and power law evolu-tion models are examined. Due to the small number of sources, the low luminosity end index of the luminosity function for FSRQs is constrained with an upper limit. BL Lac lu-minosity function shows no signature of break. As a consistency check, the model source distributions derived from these luminosity functions show no significant departure from the observed source distributions.

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

    CERN Document Server

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

    2015-01-01

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

  16. Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture

    Energy Technology Data Exchange (ETDEWEB)

    Scott Wilde, Raymond Keegan

    2008-07-01

    The countrate response of a gamma spectrometry system from a neutron radiation source behind a plane of moderating material doped with a nuclide of a large radiative neutron capture cross-section exhibits a countrate response analogous to a gamma radiation source at the same position from the detector. Using a planar, surface area of the neutron moderating material exposed to the neutron radiation produces a larger area under the prompt gamma ray peak in the detector than a smaller area of dimensions relative to the active volume of the gamma detection system.

  17. A new type gamma-ray spectrum monitoring system

    CERN Document Server

    Cheng Bo; Zhou Jian Bin; Zhang Zhi Ming; Tong Yun Fu

    2002-01-01

    This new radiation monitoring system can be used to monitor the radiation of building materials and the radiation of atmosphere, to explore and evaluate rock for building in the field, and this system can be used to monitor the gamma irradiation near the nuclear establishments in the average situation and in the serious situation of the radiation incident have happened. The control core of this monitoring system is SCM-AT89C52, and gamma-ray sensing head consists of scintillator phi 50 mm x 50 mm NaI(Tl) and PMT GDB44. This system can be used to measure the whole gamma-ray spectrum of 256 channels

  18. Detection of Gamma Rays from a Starburst Galaxy

    Science.gov (United States)

    Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Barres de Almeida, U.; Bazer-Bachi, A. R.; Becherini, Y.; Behera, B.; Bernlöhr, K.; Bochow, A.; Boisson, C.; Bolmont, J.; Borrel, V.; Brucker, J.; Brun, F.; Brun, P.; Bühler, R.; Bulik, T.; Büsching, I.; Boutelier, T.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; Drury, L. O.'C.; Dubois, F.; Dubus, G.; Dyks, J.; Dyrda, M.; Egberts, K.; Emmanoulopoulos, D.; Espigat, P.; Farnier, C.; Fegan, S.; Feinstein, F.; Fiasson, A.; Förster, A.; Fontaine, G.; Füßling, M.; Gabici, S.; Gallant, Y. A.; Gérard, L.; Gerbig, D.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Goret, P.; Göring, D.; Hauser, D.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Hofverberg, P.; Hoppe, S.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jahn, C.; Jung, I.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Kerschhaggl, M.; Khangulyan, D.; Khélifi, B.; Keogh, D.; Klochkov, D.; Kluźniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Lamanna, G.; Lenain, J.-P.; Lohse, T.; Marandon, V.; Martineau-Huynh, O.; Marcowith, A.; Masbou, J.; Maurin, D.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Moderski, R.; Moulin, E.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; Olive, J.-F.; Wilhelmi, E. de Oña; Orford, K. J.; Ostrowski, M.; Panter, M.; Arribas, M. Paz; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raubenheimer, B. C.; Raue, M.; Rayner, S. M.; Reimer, O.; Renaud, M.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Sahakian, V.; Santangelo, A.; Schlickeiser, R.; Schöck, F. M.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sikora, M.; Skilton, J. L.; Sol, H.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Superina, G.; Szostek, A.; Tam, P. H.; Tavernet, J.-P.; Terrier, R.; Tibolla, O.; Tluczykont, M.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Venter, L.; Vialle, J. P.; Vincent, P.; Vivier, M.; Völk, H. J.; Volpe, F.; Wagner, S. J.; Ward, M.; Zdziarski, A. A.; Zech, A.

    2009-11-01

    Starburst galaxies exhibit in their central regions a highly increased rate of supernovae, the remnants of which are thought to accelerate energetic cosmic rays up to energies of ~1015 electron volts. We report the detection of gamma rays—tracers of such cosmic rays—from the starburst galaxy NGC 253 using the High Energy Stereoscopic System (H.E.S.S.) array of imaging atmospheric Cherenkov telescopes. The gamma-ray flux above 220 billion electron volts is F = (5.5 ± 1.0stat ± 2.8sys) × 10-13 cm-2 s-1, implying a cosmic-ray density about three orders of magnitude larger than that in the center of the Milky Way. The fraction of cosmic-ray energy channeled into gamma rays in this starburst environment is five times as large as that in our Galaxy.

  19. VHE $\\gamma$-ray observations of Markarian 501

    CERN Document Server

    Breslin, A C; Bradbury, S M; Buckley, J H; Burdett, A M; Carson, M J; Carter-Lewis, D A; Catanese, M; Cawley, M F; Dunlea, S; D'Vali, M; Fegan, D J; Fegan, S J; Finley, J P; Gaidos, J A; Hall, T A; Hillas, A M; Horan, D; Kildea, J; Knapp, J; Krennrich, F; Le Bohec, S; Lessard, R W; Masterson, C; McKernan, B; Quinn, J; Rose, H J; Samuelson, F W; Sembroski, G H; Vasilev, V; Weekes, T C

    1999-01-01

    Markarian 501, a nearby (z=0.033) X-ray selected BL Lacertae object, is a well established source of Very High Energy (VHE, E>=300 GeV) gamma rays. Dramatic variability in its gamma-ray emission on time-scales from years to as short as two hours has been detected. Multiwavelength observations have also revealed evidence that the VHE gamma-ray and hard X-ray fluxes may be correlated. Here we present results of observations made with the Whipple Collaboration's 10 m Atmospheric Cerenkov Imaging Telescope during 1999 and discuss them in the context of observations made on Markarian 501 during the period from 1996-1998.

  20. Dosimetric property of mineral extracted from calamari and exposed to gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Cruz-Zaragoza, E.; Roman-Lopez, J.; Cruz, L. Perez; Furetta, C. [Unidad de Irradiacion y Seguridad Radiologica, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, 04510 Mexico D.F (Mexico); Chiaravalle, E.; Mangiacotti, M.; Marchesani, G. [Centro di Referenza Nazionale per la Ricerca della Radioattivita nel Settore Zootecnico-Veterinario, Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, I-71121 Foggia (Italy)

    2013-07-03

    Dosimetric property of polymineral fraction, quartz mainly, obtained from calamari was investigated. The commercial calamari samples from China and Sud Africa were collected in the markets of Italy. All polymineral debris were extracted and isolated from the whole body of calamari. The surface of the polymineral samples was analyzed by using the Scanning Electron Microscopy (SEM) and their chemical composition was determined using Energy Dispersive Spectroscopy (EDS). The polymineral was exposed to gamma rays ({sup 60}Co) at different doses (0.5-80 Gy) to determine dosimetric property. Thermoluminescent (TL) glow curves showed two peaks centered at around 98-100 Degree-Sign C and 128-138 Degree-Sign C temperature range. The glow curves have been analyzed by using a deconvolution program. A linear dose response between 0.5 to 20 Gy was observed. The TL response of the samples as a function of the time storage, fading, presented a reduction of about 36-40 % at the end of 24 h. The reproducibility of the TL response after ten cycles of irradiation-readout showed an acceptable standard deviation in dosimetry. The polimineral fraction obtained from calamari shows an interesting dosimetric property and it may be useful for dosimetry in gamma radiation field.

  1. Calibration of the 4pi gamma-ray spectrometer using a new numerical simulation approach.

    Science.gov (United States)

    Nafee, Sherif S; Badawi, Mohamed S; Abdel-Moneim, Ali M; Mahmoud, Seham A

    2010-09-01

    The 4pi gamma-counting system is well suited for analysis of small environmental samples of low activity because it combines advantages of the low background and the high detection efficiency due to the 4pi solid angle. A new numerical simulation approach is proposed for the HPGe well-type detector geometry to calculate the full-energy peak and the total efficiencies, as well as to correct for the coincidence summing effect. This method depends on a calculation of the solid angle subtended by the source to the detector at the point of entrance, (Abbas, 2006a). The calculations are carried out for non-axial point and cylindrical sources inside the detector cavity. Attenuation of photons within the source itself (self-attenuation), the source container, the detector's end-cap and the detector's dead layer materials is also taken into account. In the Belgium Nuclear Research Center, low-activity aqueous solutions of (60)Co and (88)Y in small vials are routinely used to calibrate a gamma-ray p-type well HPGe detector in the 60-1836keV energy range. Efficiency values measured under such conditions are in good agreement with those obtained by the numerical simulation.

  2. The effect of the substitution of D{sub 2}O for H{sub 2}O on the degradation of myosin {beta} in solution by heat and by {sup 60}Co {gamma} radiation (1962); Effet de la substitution de D{sub 2}O a H{sub 2}O sur l'alteration de la Myosine B en solution par la chaleur et par les rayons {gamma} du {sup 60}CO (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Pinset-Harstrom, I.; Fritsch, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    (1) Alterations of myosin B produced by heat or irradiation are shown to be qualitatively identical as demonstrated by analytical centrifugation. (2) A considerable isotope effect was demonstrated using 75 per cent D{sub 2}O in the solvent. The sensitivity of myosin B to heat and irradiation is discussed in the light of this isotope effect. (3) Polymers appearing upon heat treatment of myosin B seem to be of a very different nature than the polymers occurring alter a similar treatment upon myosin A. Polymers obtained from myosin B can be depolymerized by ATP and they appear in a much narrower temperature range than myosin A polymers. This fact indicates a considerable difference in the activation enthalpies in the two reactions. (authors) [French] (1) Cette etude montre que les alterations de la myosine B provoquees par la chaleur et par l'irradiation aux rayons {gamma} sont - telles qu'elles apparaissent a l'ultracentrifugation analytique - qualitativement semblables. (2) Nous avons observe un effet isotopique considerable de la presence de 75 pour cent de D{sub 2}O dans le solvant sur la sensibilite de la myosine B envers ces deux agents, et nous avons presente une tentative d'explication de ce fait. (3) Les polymeres qui apparaissent apres un traitement par la chaleur de la myosine semblent etre d'une nature tres differente des polymeres que l'on voit apparaitre apres un traitement identique de la myosine A. Ceux obtenus a partir de le myosine B sont depolymerisables par l'intermediaire de l'ATP et apparaissent dans une zone de temperature beaucoup plus etroite que celles de la myosine A. Ce dernier fait indique une difference considerable de l'enthalpie d'activation des deux reactions. (auteurs)

  3. EFFECT OF LOW DOSE IRRADIATION OF 60Coγ-RAYS ON SEED GERMINATION, SEEDLING GROWTH AND ENZYMES ACTIVITY OF Lactuca sativa%~(60)Coγ射线低剂量辐照对生菜种子萌发、幼苗生长及酶活性的影响

    Institute of Scientific and Technical Information of China (English)

    刘秀清; 章铁

    2012-01-01

    The seeds of Lactuca sativa were irradiated by different doses (10,20,30,40,50Gy) of 60Co Lactuca sativa ; 60 Co γ-rays ; low dose irradiation ; enzyme activity ; germination- rays. The effects of low dose irradiation on seed germination, seedling growth and enzymes activity were investigated. The results indicated that low dose irradiation could promote germination rate, germinating viability, germination rate in the field, root length and height of seedling. The suitable dosage for low dose irradiation for Lactuca sativa was 30Gy. POD activity after irradiation treatment in the range of 10 to 50Gy and CAT activity after irradiation treatment in the range of 20Gy to 40Gy was lower than that of control.%用不同剂量(10、20、30、40和50Gy)60Coγ射线辐照生菜种子,研究其对种子萌发,幼苗生长和酶活性的影响。结果表明,低剂量辐照可显著提高生菜种子的发芽率、发芽势、田间出苗率、幼苗高度和主根长度,对种子萌发和幼苗生长有一定的促进作用。综合考虑各苗期性状指标初步确定生菜低剂量辐照的适宜剂量为30Gy。在所试剂量范围内辐照处理的POD活性均低于对照;在20~40Gy剂量范围内辐照处理的CAT活性与对照相比也有所降低。

  4. THERMAL X-RAY EMISSION FROM THE SHOCKED STELLAR WIND OF PULSAR GAMMA-RAY BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Zabalza, V.; Paredes, J. M. [Departament d' Astronomia i Meteorologia, Institut de Ciencies del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E08028 Barcelona (Spain); Bosch-Ramon, V., E-mail: vzabalza@am.ub.es [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland)

    2011-12-10

    Gamma-ray-loud X-ray binaries are binary systems that show non-thermal broadband emission from radio to gamma rays. If the system comprises a massive star and a young non-accreting pulsar, their winds will collide producing broadband non-thermal emission, most likely originated in the shocked pulsar wind. Thermal X-ray emission is expected from the shocked stellar wind, but until now it has neither been detected nor studied in the context of gamma-ray binaries. We present a semi-analytic model of the thermal X-ray emission from the shocked stellar wind in pulsar gamma-ray binaries, and find that the thermal X-ray emission increases monotonically with the pulsar spin-down luminosity, reaching luminosities of the order of 10{sup 33} erg s{sup -1}. The lack of thermal features in the X-ray spectrum of gamma-ray binaries can then be used to constrain the properties of the pulsar and stellar winds. By fitting the observed X-ray spectra of gamma-ray binaries with a source model composed of an absorbed non-thermal power law and the computed thermal X-ray emission, we are able to derive upper limits on the spin-down luminosity of the putative pulsar. We applied this method to LS 5039, the only gamma-ray binary with a radial, powerful wind, and obtain an upper limit on the pulsar spin-down luminosity of {approx}6 Multiplication-Sign 10{sup 36} erg s{sup -1}. Given the energetic constraints from its high-energy gamma-ray emission, a non-thermal to spin-down luminosity ratio very close to unity may be required.

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

    Science.gov (United States)

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

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

  6. Gamma Rays, Electrons, Hard X-Rays, and the Central Parsec of the Milky Way

    CERN Document Server

    Kistler, Matthew D

    2015-01-01

    The complex interplay of processes at the Galactic Center is at the heart of numerous past, present, and (likely) future mysteries. We aim at a more complete understanding of how spectra extending to >10 TeV result. We first construct a simplified model to account for the peculiar energy and angular dependence of the intense central parsec photon field. This allows for calculating anisotropic inverse Compton scattering and mapping gamma-ray extinction due to gamma gamma -> e^+ e^- attenuation. Coupling these with a method for evolving electron spectra, we examine several clear and present excesses, including the diffuse hard X-rays seen by NuSTAR and GeV gamma rays by Fermi. We address further applications to cosmic rays, dark matter, neutrinos, and gamma rays from the Center and beyond.

  7. Humoral immune response against native or {sup 60}Co irradiated venom and mucus from stingray Paratrygon aiereba

    Energy Technology Data Exchange (ETDEWEB)

    Thomazi, Gabriela Ortega Coelho; Alves, Glaucie Jussilane; Aires, Raquel da Silva; Turibio, Thompson de Oliveira; Rocha, Andre Moreira; Spencer, Patrick Jack; Nascimento, Nanci do, E-mail: 0916@prof.itpacporto.com.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Seibert, Carla Simone, E-mail: carlaseibert@yahoo.com [Universidade Federal do Tocantins (UFT), Porto Nacional, TO (Brazil)

    2015-07-01

    Poisonings and traumas caused by poisonous freshwater fish such as rays are considered a major public health problem and draw attention because of accidents involving these animals cause serious local symptoms and are disabling, keeping the victim away from work. The therapy of these cases is based only on the symptoms of patients, which implies in its low efficiency, causing suffering for the victims. This study aims to evaluate and compare the humoral immune response in animals inoculated with native or {sup 60}Co irradiated Paratrygon aiereba venom and mucus. Ionizing radiation has proven to be an excellent tool to decrease the toxicity of venoms and isolated toxins. The mucus and venom samples of P. aiereba were irradiated using gamma rays from a {sup 60}Co source. Animals models were immunized with the native or irradiated mucus or venom. The assays were conducted to assess the production of antibodies by the immunized animals using enzyme immunoassay and western blotting. Preliminary results show the production of antibodies by the immunized animals. The resulting sera were also checked for antigenic cross- reactivity between venom and mucus, demonstrating the potential of mucus as an antigen for serum production for the specific treatment for accidents by stingrays. However, it is essential to carry out further tests in order to verify the neutralization of the toxin by antibodies formed by animals. (author)

  8. Multi-wavelength emission region of gamma-ray pulsars

    CERN Document Server

    Kisaka, Shota

    2011-01-01

    Recent obserbations by Fermi Gamma-Ray Space Telescope of gamma-ray pulsars have revealed further details of the structure of the emission region. We investigate the emission region for the multi-wavelength light curve using outer gap model. We assume that gamma-ray and non-thermal X-ray photons are emitted from a particle acceleration region in the outer magnetosphere, and UV/optical photons originate above that region. We also assume that gamma-rays are radiated only by outwardly moving particles, whereas the other photons are produced by particles moving inward and outward. We parametrize the altitude of the emission region. We find that the outer gap model can explain the multi-wavelength pulse behavior. From observational fitting, we also find a general tendency for the altitude of the gamma-ray emission region to depend on the inclination angle. In particular, the emission region for low inclination angle is required to be located in very low altitude, which corresponds to the inner region within the la...

  9. Delayed Gamma-ray Spectroscopy for Safeguards Applications

    Energy Technology Data Exchange (ETDEWEB)

    Mozin, Vladimir [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-01-03

    The delayed gamma-ray assay technique utilizes an external neutron source (D-D, D-T, or electron accelerator-driven), and high-resolution gamma-ray spectrometers to perform characterization of SNM materials behind shielding and in complex configurations such as a nuclear fuel assembly. High-energy delayed gamma-rays (2.5 MeV and above) observed following the active interrogation, provide a signature for identification of specific fissionable isotopes in a mixed sample, and determine their relative content. Potential safeguards applications of this method are: 1) characterization of fresh and spent nuclear fuel assemblies in wet or dry storage; 2) analysis of uranium enrichment in shielded or non-characterized containers or in the presence of a strong radioactive background and plutonium contamination; 3) characterization of bulk and waste and product streams at SNM processing plants. Extended applications can include warhead confirmation and warhead dismantlement confirmation in the arms control area, as well as SNM diagnostics for the emergency response needs. In FY16 and prior years, the project has demonstrated the delayed gamma-ray measurement technique as a robust SNM assay concept. A series of empirical and modeling studies were conducted to characterize its response sensitivity, develop analysis methodologies, and analyze applications. Extensive experimental tests involving weapons-grade Pu, HEU and depleted uranium samples were completed at the Idaho Accelerator Center and LLNL Dome facilities for various interrogation time regimes and effects of the neutron source parameters. A dedicated delayed gamma-ray response modeling technique was developed and its elements were benchmarked in representative experimental studies, including highresolution gamma-ray measurements of spent fuel at the CLAB facility in Sweden. The objective of the R&D effort in FY17 is to experimentally demonstrate the feasibility of the delayed gamma-ray interrogation of shielded SNM

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

    DEFF Research Database (Denmark)

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

    1995-01-01

    19 Cosmic Gamma-Ray Bursts were detected by the WATCH wide field X-ray monitor during the 11 months flight of EURECA. The identification of the bursts were complicated by a high frequency of background of events caused by high energy cosmic ray interactions in the detector and by low energy......, trapped particle streams. These background events may simulate the count rate increases characteristic of cosmic gamma bursts. For 12 of the detected events, their true cosmic nature have been confirmed through consistent localizations of the burst sources based on several independent WATCH data sets...

  11. Fluxes of diffuse gamma rays and neutrinos from cosmic-ray interactions with circumgalactic gas

    CERN Document Server

    Kalashev, Oleg

    2016-01-01

    The Milky Way is surrounded by a gravitationally bound gas corona extending up to the Galaxy's virial radius. Interactions of cosmic-ray particles with this gas give rise to energetic secondary gamma rays and neutrinos. We present a quantitative analysis of the neutrino and gamma-ray fluxes from the corona of the Milky Way together with a combined contribution of coronae of other galaxies. The high-energy neutrino flux is insufficient to explain the IceCube results, while the contribution to the FERMI-LAT diffuse gamma-ray flux is not negligible.

  12. Gamma-ray fluxes in Oklo natural reactors

    CERN Document Server

    Gould, C R; Sonzogni, A A; 10.1103/PhysRevC.86.054602

    2012-01-01

    Uncertainty in the operating temperatures of Oklo reactor zones impacts the precision of bounds derived for time variation of the fine structure constant $\\alpha$. Improved $^{176}$Lu/$^{175}$Lu thermometry has been discussed but its usefulness may be complicated by photo excitation of the isomeric state $^{176m}$Lu by $^{176}$Lu($\\gamma,\\gamma^\\prime $) fluorescence. We calculate prompt, delayed and equilibrium $\\gamma$-ray fluxes due to fission of $^{235}$U in pulsed mode operation of Oklo zone RZ10. We use Monte Carlo modeling to calculate the prompt flux. We use improved data libraries to estimate delayed and equilibrium spectra and fluxes. We find $\\gamma$-ray fluxes as a function of energy and derive values for the coefficients $\\lambda_{\\gamma,\\gamma^\\prime}$ that describe burn-up of $^{176}$Lu through the isomeric $^{176m}$Lu state. The contribution of the ($\\gamma,\\gamma^\\prime $) channel to the $^{176}$Lu/$^{175}$Lu isotopic ratio is negligible in comparison to the neutron burn-up channels. Lutetium...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-05-15

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

  14. Gamma-ray shielding effectiveness of novel light-weight clay-flyash bricks

    Science.gov (United States)

    Mann, Harjinder Singh; Brar, G. S.; Mudahar, G. S.

    2016-10-01

    The radiation shielding parameters of lightweight clay-flyash bricks produced with different flyash aggregate compositions have been investigated by using 241Am (59.4 keV), 137Cs (661.6 keV), and 60Co (1173.2 keV and 1332.5 keV) radioactive sources. It was observed that the different percentages of flyash in clay lead to significant variations in these parameters. The elemental compositions of the clay-flyash bricks were analyzed using energy dispersive X-ray fluorescence spectrometry (EDXRF). The obtained results were compared to those pertaining to concrete in order to see the effect of flyash content on the radiation shielding properties. The radiation protection efficiency of the tested clay-flyash bricks demonstrated that multilayer exterior walls built from these bricks could effectively attenuate moderate-energy gamma rays. Bricks using residual flyash could be preferentially used for buildings to address the issues of radiation shielding, cost-effective radioactive waste management and disposal of flyash in a useful manner.

  15. Effects of {sup 60}Co radiation on bothropstoxin-1 structure

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, P.J.; Nascimento, N.; Rogero, J.R. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Div. de Radiobiologia; Byrne, M.; Smith, L.A. [United States Army Medical Research, Frederick, MD (United States). Inst. of Infectious Diseases. Toxinology Div.

    2000-07-01

    Gamma radiation is able to detoxify snake venoms and toxins without significantly affecting their immunogenic properties. This method has been successfully employed to attenuate toxins for antisera production without inducing toxic effects in animals undergoing immunization. However, the mechanism of attenuation is not fully understood and much work remains at the molecular level in order to further characterize the effects of radiation on these proteins. The present study was undertaken to evaluate structural modifications following irradiation of bothropstoxin-1 (bthTx-1), a myotoxin from Bothrops jararacussu. It is believed that the functional form of the toxin is a homodimer with the binding affinity provided by electrostatic and hydrophobic interactions. Purified BthTx-1 was irradiated with 500, 1000 and 2000 Gy of {sup 60}Co gamma radiation. The irradiated and native toxins were compared by mass spectrometry, circular dichroism (CD) and tryptophan fluorescence quenching, results suggest that the monomer-monomer interactions are hydrophobic in nature. No significant differences were observed between the two forms of the toxin by CD spectral interpretation. However, significant losses of secondary structure could be observed when the native and irradiated BthTX-1 were compared after disulfide bond reduction. Fluorescence data indicates that the solvent accessibility of Trp 77 has been modified, which may explain the differences in quaternary structure. (author)

  16. A possible origin of gamma rays from the Fermi Bubbles

    Science.gov (United States)

    Thoudam, Satyendra

    2014-11-01

    One of the most exciting discoveries of recent years is a pair of gigantic gamma-ray emission regions, the so-called Fermi bubbles, above and below the Galactic center. The bubbles, discovered by the Fermi space telescope, extend up to ∼50° in Galactic latitude and are ∼40° wide in Galactic longitude. The gamma-ray emission is also found to correlate with radio, microwave and X-rays emission. The origin of the bubbles and the associated non-thermal emissions are still not clearly understood. Possible explanations for the non-thermal emission include cosmic-ray injection from the Galactic center by high speed Galactic winds/jets, acceleration by multiple shocks or plasma turbulence present inside the bubbles, and acceleration by strong shock waves associated with the expansion of the bubbles. In this paper, I will discuss the possibility that the gamma-ray emission is produced by the injection of Galactic cosmic-rays mainly protons during their diffusive propagation through the Galaxy. The protons interact with the bubble plasma producing π°-decay gamma rays, while at the same time, radio and microwave synchrotron emissions are produced by the secondary electrons/positrons resulting from the π± decays.

  17. Recent high energy gamma-ray results from SAS-2

    Science.gov (United States)

    Thompson, D. J.; Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Bignami, G. F.; Ogelman, H. B.; Ozel, M. E.; Tumer, T.; Lamb, R. C.

    1977-01-01

    Recent developments in gamma-ray astronomy due to the results from SAS-2 have focused on two areas. First, the emission from the plane of the Galaxy is the dominant feature in the gamma-ray sky. The galactic latitude and longitude distributions are consistent with the concept that the high-energy radiation originates from cosmic rays interacting with interstellar matter, and the measurements support a galactic origin for cosmic rays. Second, searches of the SAS-2 data for emission from localized sources have shown three strong discrete gamma-ray sources: the Crab nebula and PSR 0531 + 21, the Vela supernova remnant and PSR 0833-45, and a source near galactic coordinates 193 deg longitude, +3 deg latitude, which does not appear to be associated with other known celestial objects. Evidence has also been found for pulsed gamma-ray emission from two other radio pulsars, PSR 1818-04 and PSR 1747-46. A localized source near longitudes 76-80 deg may be associated with the X-ray source Cyg X-3.

  18. Cosmic ray composition measurements and cosmic ray background free gamma-ray observations with Cherenkov telescopes

    CERN Document Server

    Neronov, A; Vovk, Ie; Mirzoyan, R

    2016-01-01

    Muon component of extensive air showers (EAS) initiated by cosmic ray particles carries information on the primary particle identity. We show that the muon content of EAS could be measured in a broad energy range from 10-100 TeV up to ultra-high-energy cosmic ray range using wide field-of-view imaging atmospheric Cherenkov telescopes observing strongly inclined or nearly horizontal EAS from the ground of from high altitude. Cherenkov emission from muons in such EAS forms a distinct component (halo or tail) of the EAS image in the telescope camera. We show that detection of the muon signal could be used to measure composition of the cosmic ray spectrum in the energy ranges of the knee, the ankle and of the Galactic-to-extragalactic transition. It could also be used to veto the cosmic ray background in gamma-ray observations. This technique provides a possibility for up to two orders of magnitude improvement of sensitivity for gamma-ray flux in the energy band above 10 PeV, compared to KASCADE-Grande, and an or...

  19. PANGU: a wide field gamma-ray imager and polarimeter

    Science.gov (United States)

    Wu, X.; Walter, R.; Su, M.; Ambrosi, G.; Azzarello, P.; Böttcher, M.; Chang, J.; Chernyakova, M.; Fan, Y.; Farnier, C.; Gargano, F.; Grenier, I.; Hajdas, W.; Mazziotta, M. N.; Pearce, M.; Pohl, M.; Zdziarski, A.

    2016-07-01

    PANGU (the PAir-productioN Gamma-ray Unit) is a gamma-ray telescope with a wide field of view optimized for spectro-imaging, timing and polarization studies. It will map the gamma-ray sky from 10 MeV to a few GeV with unprecedented spatial resolution. This window on the Universe is unique to detect photons produced directly by relativistic particles, via the decay of neutral pions, or the annihilation or decay light from anti-matter and the putative light dark matter candidates. A wealth of questions can be probed among the most important themes of modern physics and astrophysics. The PANGU instrument is a pair-conversion gamma-ray telescope based on an innovative design of a silicon strip tracker. It is light, compact and accurate. It consists of 100 layers of silicon micro-strip detector of 80 x 80 cm2 in area, stacked to height of about 90 cm, and covered by an anticoincidence detector. PANGU relies on multiple scattering effects for energy measurement, reaching an energy resolution between 30-50% for 10 MeV - 1 GeV. The novel tracker will allow the first polarization measurement and provide the best angular resolution ever obtained in the soft gamma ray and GeV band.

  20. Sky and Elemental Planetary Mapping Via Gamma Ray Emissions

    Science.gov (United States)

    Roland, John M.

    2011-01-01

    Low-energy gamma ray emissions ((is) approximately 30keV to (is) approximately 30MeV) are significant to astrophysics because many interesting objects emit their primary energy in this regime. As such, there has been increasing demand for a complete map of the gamma ray sky, but many experiments to do so have encountered obstacles. Using an innovative method of applying the Radon Transform to data from BATSE (the Burst And Transient Source Experiment) on NASA's CGRO (Compton Gamma-Ray Observatory) mission, we have circumvented many of these issues and successfully localized many known sources to 0.5 - 1 deg accuracy. Our method, which is based on a simple 2-dimensional planar back-projection approximation of the inverse Radon transform (familiar from medical CAT-scan technology), can thus be used to image the entire sky and locate new gamma ray sources, specifically in energy bands between 200keV and 2MeV which have not been well surveyed to date. Samples of these results will be presented. This same technique can also be applied to elemental planetary surface mapping via gamma ray spectroscopy. Due to our method's simplicity and power, it could potentially improve a current map's resolution by a significant factor.