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Sample records for airborne gamma ray

  1. 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. ...

  2. Airborne gamma ray spectrometer surveying

    International Nuclear Information System (INIS)

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

  3. 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.

  4. Airborne Gamma-Ray Survey in Latvia 1995/96

    DEFF Research Database (Denmark)

    Bargholz, Kim

    1998-01-01

    Based on Airborne Gamma-Ray Spectrometry measurements performed with the Danish AGS equipment in 1995 and 1996 maps of the natural radioactivity have been produdced for selected areas in Latvia. The calibration of the quipment have been improved by comparisons with soil sample measurements....

  5. Reducing Statistical Noise in Airborne Gamma-Ray Data

    DEFF Research Database (Denmark)

    Hovgaard, Jens; Grasty, R. L.

    1997-01-01

    By using the Noise Adjusted Singular Value Decomposition (NASVD) technique it is possible to reconstruct the measured airborne gamma-ray spectra with a noise content that is significant smaller than the noise contained in the original measured spectra. The method can be used for improving the out...

  6. 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....

  7. Airborne magnetic and gamma-ray data acquisition

    International Nuclear Information System (INIS)

    Current aeromagnetic data acquisition has benefited from improvements in measurement precision and compensation systems for removing with closer line spacing than previously, and this has stimulated a demand for lower survey altitudes with flight heights of the order of 60-80 m now common. Radiometric recording of 256 channels of gamma-ray data is now virtually standard and in-flight stabilisation of these systems has improved markedly. Digital acquisition systems are now designed to facilitate both in-flight and post-flight verification of the data. This article briefly outlines he history of the acquisition equipment used in the earlier surveys and details the current sate-of-the-art technology and methodology used in airborne magnetic and gamma-ray surveys. 9 refs., 1 tab., 2 figs

  8. Dose Rate Determination from Airborne Gamma-ray Spectra

    DEFF Research Database (Denmark)

    Bargholz, Kim

    1996-01-01

    The standard method for determination of ground level dose rates from airborne gamma-ray is the integral count rate which for a constant flying altitude is assumed proportional to the dose rate. The method gives reasonably results for natural radioactivity which almost always has the same energy...... distribution. When manmade radioactivity is present, this is no longer the case. Another method based on giving the counts of different channels a different weighting has been examined. The new method is more robust against varying energy distribution, and for energies above 200 keV it gives excellent results....

  9. Calibration procedures in airborne gamma-ray spectrometry

    International Nuclear Information System (INIS)

    The various calibration procedures adopted for airborne gamma-ray spectrometric measurements in Atomic Minerals Division are: (1) Over calibration pads for calculating sensitivities, stripping, and reverse stripping coefficients. Sensitivities are essential for converting the count rates into ground concentrations i.e. ppm (parts per million) in case of uranium and thorium and into percentage for potassium. In order to apply inter-channel corrections to radiometric data, stripping coefficients are essential. (2) Over test strip for calculating linear attenuation coefficients. These linear attenuation coefficients are used for applying height correction to the radiometric data. (3) Computation of sensitivities at nominal flying altitude (122 m) from the data obtained over the test strip for gamma-rays of different energies. In this paper computation of linear attenuation coefficients using test strip data and sensitivities, stripping, and reverse stripping coefficients using calibration pads data have been discussed in detail and results have been reported. The accuracy of the results have been ascertained and errors have been reported. (author). 12 refs., 7 tabs., 6 figs

  10. Airborne Gamma-Ray Spectrometer Experiments Over the Canadian Shield

    International Nuclear Information System (INIS)

    The Geological Survey of Canada and Atomic Energy of Canada Ltd. have produced a high sensitivity spectrometer for radiometric mapping of the Canadian Shield. During 1967 experiments were undertaken in the Bancroft and Elliot Lake areas of Ontario to determine the system parameters. Ground control was provided by measurements with field gamma-ray spectrometers on a 200-ft grid over 3 square miles. An experimental spectrometer employed three 5 x 5 in. (12.5 x 12.5 cm) diam. Nal (Tl) detectors, in order to record the full gamma - spectrum in real-time on magnetic tape. To provide the highest possible count-rates per unit distance at varying heights the spectrometer was flown in a helicopter at 25 mph (40 kmph). A study of the spectra obtained shows that the optimum spectral window widths for measuring the relative abundance of potassium, uranium and thorium are potassium, 40K 1.35 - 1.58 meV, uranium, 214Bi 1.65 - 1.88 meV; thorium, 208Tl 2.42 - 2.62 meV. The recorded data was subsequently processed through a PDP-9 computer to provide corrections for dead-time, Compton scattering and deviations from constant terrain clearance. Based on this work a much more sensitive airborne system was constructed in 1968 and installed in a twin-engined STOL aircraft. The system employs twelve 9 x 4 in. (23 x 10 cm) Nal (Tl) crystals. This detector volume provides a 10% (1 standard deviation) precision in corrected accumulated count in any of the three spectral windows when the aircraft measures radiation over an elapsed distance of 350 ft at a ground speed of 120 mph and 400 tt terrain clearance. The airborne system includes Doppler navigation, radar altimeter, and TV tracking camera equipment. (author)

  11. Airborne system for mapping and tracking extended gamma ray sources

    International Nuclear Information System (INIS)

    An airborne system was developed for mapping and tracking extended sources of airborne or terrestrially distributed γ-ray emitters. The system records 300 channel γ-ray spectral data every three seconds on magnetic tape. Computer programs have been written to isolate the contribution from the particular radionuclide of interest. Aircraft position as sensed by a microwave ranging system is recorded every second on magnetic tape. Measurements of airborne stack releases of 41A concentrations versus time or aircraft position agree well with computer code predictions

  12. The Danish airborne gamma-ray surveying results

    Energy Technology Data Exchange (ETDEWEB)

    Hovgaard, J. [Danish Emergency Management Agency, Birkeroed (Denmark)

    1997-12-31

    The Danish Emergency Management Agency (DEMA) in co-operation with the Technical University of Denmark (TUD), Department of Automation, participated in the international exercise RESUME-95 arranged in Finland in August 1995. DEMA performed measurement with their airborne gamma-ray surveying system. Surveys were done in the three areas known as AREA I, II, III. Results from AREA II (3 km x 6 km) show that the apparent {sup 137}Cs deposition assuming a deposition profile equal to the profile in AREA I based on soil samples varies from a few 10th kBqm{sup -2} up to 110 kBqm{sup -2}. However, a detailed analysis using a new method, Noise Adjusted Singular Value Decomposition (NASVD), shows that the true variations probably are smaller and that the observed differences to some extend are due to major variations in the depth distribution of the cesium. For example agricultural areas appears to have cesium much deeper deposit than the undisturbed areas. Another interesting result is that the NASVD analysis shows that the ration of {sup 134}Cs to {sup 137}Cs is fixed and approximately 0.03 (August 1995) a number in good agreement with the expected ratio from the Chernobyl accident. No true real-time software for source detection is yet integrated in the Danish system. Results from AREA III, however, show that the implemented software for rapid post processing of data worked excellent for detection of radioactive sources. Post analysis using NASVD demonstrates that all sources except for a small {sup 137}Cs source can be localized. (au).

  13. Airborne Gamma-ray Measurements in the Chernobyl Plume

    DEFF Research Database (Denmark)

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

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

  14. Airborne Gamma-ray Measurements in the Chernobyl Plume

    DEFF Research Database (Denmark)

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

    1997-01-01

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

  15. Conversion of Airborne Gamma ray Spectra to Ground Level Air Kerma Rates

    DEFF Research Database (Denmark)

    Bargholz, Kim; Korsbech, Uffe C C

    A new method for relating airborne gamma-ray spectra to dose rates and kerma rates at ground level is presented. Dependent on flying altitude 50 m to 125 m the method gives correct results for gamma energies above 250 keV respective 350 keV. At lower energies the method underestimate the dose or ...

  16. A New Method for Processing Airborne Gamma Ray Spectrometry Data for Mapping Low Level Contaminations

    DEFF Research Database (Denmark)

    Aage, Helle Karina; Korsbech, Uffe C C; Bargholz, Kim;

    1999-01-01

    A new technique for processing airborne gamma ray spectrometry data has been developed. It is based on the noise adjusted singular value decomposition method introduced by Hovgaard in 1997. The new technique opens for mapping of very low contamination levels. It is tested with data from Latvia...

  17. Application of airborne gamma-ray spectrometry in soil/regolith mapping and applied geomorphology

    International Nuclear Information System (INIS)

    Gamma-ray spectrometric surveys are an important source of information for soil, regolith and geomorphological studies, as demonstrated by the interpretation of airborne surveys in Western Australia, central New South Wales and north Queensland. Gamma-rays emitted from the ground surface relate to the primary mineralogy and geochemistry of the bedrock, and the secondary weathered materials. Weathering modifies the distribution and concentration of radioelements from the original bedrock source. Once the radioelement response of bedrock and weathered materials is understood, the gamma-ray data can provide information on geomorphic processes and soil/regolith properties, including their mineralogy, texture, chemistry and style of weathering. This information can contribute significantly to an understanding of the weathering and geomorphic history of a region and, therefore, has the potential to be used in developing more effective land-management strategies and refining geochemical models in support of mineral exploration. Gamma-ray imagery is enhanced when combined with Landsat TM bands and digital elevation models (DEM). This synergy enables geochemical information derived from the gamma-ray data to be interpreted within a geomorphic framework. Draping gamma-ray images over DEMs as 3D landscape perspective views aids interpretation and allows the interpreter to visualise complex relationships between the gamma-ray response and landform features. 44 refs.,1 tab., 11 figs

  18. Environmental radiation monitoring-airborne gamma ray spectrometry over parts of India

    International Nuclear Information System (INIS)

    Airborne gamma-ray spectrometry (AGRS) has been widely accepted as a technique with large applications not for Uranium exploration, geological mapping, mineral exploration, environmental monitoring. The interesting point of AGRS technique is that it provides information of the ground/soil (density 1.40-2.00 gm/cc) about a meter deep in soil and 33 cm in rock types (density 2.5-3.00gm/cc). This information can become quite important consideration for agriculture, environmental scientists and planners in decision making. Gamma ray surveys are broadly based on surface, subsurface and airborne radiometric measurements. Airborne gamma ray spectrometric surveys began in the developed countries and in India during the early 1950's. These methodologies have undergone a great evolution in the development of the system by way of Instrumentation, Calibration and survey techniques, digital signal data processing, interpretation and data management ever since the early 1950's. With proper instrumentation, calibration, airborne gamma ray spectrometers were capable of providing concentrations of naturally occurring radio nuclides such as potassium, uranium and thorium on the area flown. The exposure rates calculated using the radioelemental distributions over various parts of India. The exposure rates vary from 0.4 to 50 microR/hr. In addition to the above variation of the exposure rates, the cosmic background of 3.767 microR/h has also been taken into account while computing the total dose. These exposure rates are found to be well below the maximum permissible rates as approved by the ICRP. In the present paper the studies over the exposure rates (in micro Roentgen units) from various parts of Satpura basin (covering 7000 sq. km), parts of erstwhile Madhya Pradesh, Andhra Pradesh have been presented. (author)

  19. Airborne gamma-ray spectrometric anomaly characteristics and prospecting model for quaternary salt lake type potash deposit

    International Nuclear Information System (INIS)

    On the basis of the airborne gamma-ray spectrometric data, this paper briefly discusses partial scientific research achievements related to prospecting for potash and the establishment of prospecting model for Quaternary salt lake type potash deposit, and furthermore through the analysis on Bieletan and Mahai Potash deposits, it shows that airborne gamma-ray spectrometry is certainly of evident effect in prospecting for Quaternary salt lake type potash deposit

  20. Research on 3-D terrain correction methods of airborne gamma-ray spectrometry survey

    International Nuclear Information System (INIS)

    The general method of height correction is not effectual in complex terrain during the process of explaining airborne gamma-ray spectrometry data, and the 2-D terrain correction method researched in recent years is just available for correction of section measured. A new method of 3-D sector terrain correction is studied. The ground radiator is divided into many small sector radiators by the method, then the irradiation rate is calculated in certain survey distance, and the total value of all small radiate sources is regarded as the irradiation rate of the ground radiator at certain point of aero- survey, and the correction coefficients of every point are calculated which then applied to correct to airborne gamma-ray spectrometry data. The method can achieve the forward calculation, inversion calculation and terrain correction for airborne gamma-ray spectrometry survey in complex topography by dividing the ground radiator into many small sectors. Other factors are considered such as the un- saturated degree of measure scope, uneven-radiator content on ground, and so on. The results of for- ward model and an example analysis show that the 3-D terrain correction method is proper and effectual. (authors)

  1. Airborne gamma-ray spectrometer and magnetometer survey: Sleetmute quadrangle (Alaska). Final report

    International Nuclear Information System (INIS)

    During the months of July, August, and September 1979 an airborne high sensitivity gamma-ray spectrometer and magnetometer survey was carried out over ten 30 x 10 NTMS quadrangles of West-Central Alaska. The results obtained over Sleetmute map are discussed. The final data are presented in four different forms: on magnetic tape; on microfiche; in graphic form as profiles and histograms; and in map form as anomaly maps, flight path maps, and computer printer maps. The histograms and the multiparameter profiles are presented with the anomaly maps and flight path map in a separate bound volume

  2. Airborne gamma-ray spectrometer and magnetometer survey: Ophir quadrangle (Alaska). Final report

    International Nuclear Information System (INIS)

    During July, August, and September 1979, an airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten 30 x 10 NTMS quadrangles of West-Central Alaska. The results obtained over the Ophir map area. The final data are presented in four different forms: on magnetic tape; on microfiche; in graphic form as profiles and histograms; and in map form as anomaly maps, flight path maps; and computer printer maps. The histograms and the multiparameter profiles are presented with the anomaly maps and flight path map in a separate bound volume

  3. Airborne gamma-ray spectrometer and magnetometer survey, Meade River Quadrangle, Alaska. Final report

    International Nuclear Information System (INIS)

    The results obtained from an airborne high sensitivity gamma-ray spectrometer and magnetometer survey over the Meade River map area of Alaska are presented. Based on the criteria outlined in the general section on interpretation, a total of eight uranium anomalies have been outlined on the interpretation map. Most of these are only weakly to moderately anomalous. Zones 3 and 7 are relatively better than the others though none of the anomalies are thought to be of any economic significance. No follow-up work is recommended

  4. Airborne gamma-ray spectrometer and magnetometer survey: north/south tieline. Final report

    International Nuclear Information System (INIS)

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted along the 990 longitude meridian from the Canadian border southward to the Mexican border. A total of 1555 line miles of geophysical data were acquired and, subsequently, compiled. The north-south tieline was flown as part of the National Uranium Resources Evaluation. NURE is a program of the US Department of Energy's Grand Junction, Colorado, office to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States

  5. Airborne gamma-ray spectrometer and magnetometer survey: McGrath Quadrangle (Alaska). Final report

    International Nuclear Information System (INIS)

    During the months of July, August, and September 1979, an airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten 30 x 10 NTMS quadrangle of West-Central Alaska. The results obtained over the McGrath map area are discussed. The final data are presented in four different forms: on magnetic tape; on microfiche; in graphic form as profiles and histograms; and in map form as anomaly maps, flight path maps, and computer printer maps. The histograms and the multiparameter profiles are presented with the anomaly maps and flight path map in a separate volume

  6. The relevance of airborne and ground gamma ray spectrometry to global geochemical baselines

    International Nuclear Information System (INIS)

    The International Geochemical Mapping (IGM) project is a response to the fact that information about the distribution of radioactive and non-radioactive elements in the earth's surface materials is inconsistent and incomplete. The IGM project is organized under the International Geological Correlation Program, sponsored by UNESCO and IUGS. The IAEA has provided support for that part of the project which relates to radioactive elements. These elements, both natural and man-made, are part of the geochemical environment and subject to the same chemical and physical processes as non-radioactive elements. For many reasons their spatial distribution should be studied and recorded as part of a common database. Phase 1 of the IGM project has been concerned with the establishment of recommendations for the conduce of future work. Phase 2 of the project will be concerned with establishing global geochemical baselines for all elements. Gamma ray spectrometry is an efficient method of identifying and quantifying radioactive elements, either by in situ measurements at fixed sites, or from a moving vehicle or aircraft. All modes of measurement are required to establish reliable global baselines. However, airborne gamma ray spectrometry (AGRS) has a unique advantage because it provides a continuous profile over any land surface, independent of surface terrain. With calibrated systems, quantitative correlation of airborne and ground data can be assured within definable limits. The IGM project involves the acquisition of new data and, where quality is acceptable, incorporation of old. 24 refs, 3 figs

  7. A multivariate spatial interpolation of airborne {\\gamma}-ray data using the geological constraints

    CERN Document Server

    Guastaldi, E; Bezzon, G P; Broggini, C; Buso, G P; Caciolli, A; L., Carmignani; Callegari, I; Colonna, T; Dule, K; Fiorentini, G; Xhixha, M Kaçeli; Mantovani, F; Massa, G; Menegazzo, R; Mou, L; Alvarez, C Rossi; Strati, V; Xhixha, G; Zanon, A

    2013-01-01

    In this paper we present maps of K, eU, and eTh abundances of Elba Island (Italy) obtained with a multivariate spatial interpolation of airborne {\\gamma}-ray data using the constraints of the geologic map. The radiometric measurements were performed by a module of four NaI(Tl) crystals of 16 L mounted on an autogyro. We applied the collocated cokriging (CCoK) as a multivariate estimation method for interpolating the primary under-sampled airborne {\\gamma}-ray data considering the well-sampled geological information as ancillary variables. A random number has been assigned to each of 73 geological formations identified in the geological map at scale 1:10,000. The non-dependency of the estimated results from the random numbering process has been tested for three distinct models. The experimental cross-semivariograms constructed for radioelement-geology couples show well-defined co-variability structures for both direct and crossed variograms. The high statistical correlations among K, eU, and eTh measurements a...

  8. Spectra characteristics of airborne gamma-ray spectrometer based on data fusion

    International Nuclear Information System (INIS)

    Background: Airborne gamma-ray spectrometry is made up of multiple NaI (Tl) detector, but the detectors have the different level of noise. Purpose: Aimed at reducing the affection of noise, a weighted least square fusion estimation algorithm is presented to extract the Spectra Characteristics. Methods: The method doesn't need any prior knowledge on the detector, but carries on the variance estimated on-line these data and timely adjust weights of various fusion sensors in order to make the mean-square error of fusion results least all the time. Results: It is used to process the date come from the standard model, the results show that measurement error range of 40K decreased from 17% to 12%. Conclusions: The result has shown that the method can dramatically decrease the error and improve the accuracy. (authors)

  9. The 3D inversion of airborne gamma-ray spectrometric data

    Science.gov (United States)

    Minty, Brian; Brodie, Ross

    2016-07-01

    We present a new method for the inversion of airborne gamma-ray spectrometric line data to a regular grid of radioelement concentration estimates on the ground. The method incorporates the height of the aircraft, the 3D terrain within the field of view of the spectrometer, the directional sensitivity of rectangular detectors, and a source model comprising vertical rectangular prisms with the same horizontal dimensions as the required grid cell size. The top of each prism is a plane surface derived from a best-fit plane to the digital elevation model of the earth's surface within each grid cell area. The method is a significant improvement on current methods, and gives superior interpolation between flight lines. It also eliminates terrain effects that would normally remain in the data after the conventional processing of these data assuming a flat-earth model.

  10. The calibration of portable and airborne gamma-ray spectrometers - theory, problems, and facilities

    International Nuclear Information System (INIS)

    A gamma-ray spectrometer for use in geological exploration possesses four stripping ratios and three window sensitivities which must be determined to make the instrumentation applicable for field assay or airborne measurement of potassium, uranium, and thorium contents in the ground. Survey organizations in many parts of the world perform the instrument calibration using large pads of concrete which simulate a plane ground of known radioelement concentration. Calibration and monitoring trials with twelve facilities in ten countries prove that moisture absorption, radon exhalation, and particle-size effects can offset a radiometric grade assigned to concrete whose aggregate contains an embedded radioactive mineral. These and other calibration problems are discussed from a combined theoretical and practical viewpoint. (author)

  11. Application of airborne gamma-ray spectrometry to geological mapping, mineral exploration and land-use planning

    International Nuclear Information System (INIS)

    Airborne gamma-ray spectrometry data are used to support regional and details bedrock and surficial geological mapping, mineral exploration for a variety of mineral deposit types, environmental radiation monitoring and land-use planning. Recent case histories developed by the Geological Survey of Canada describe the use of airborne gamma-ray spectrometry to map composite igneous intrusions and mixed igneous, metamorphic and sedimentary terranes, with varying proportions of glacial overburden, soil moisture, surface wetness and vegetation cover. Other case histories show that potassium alteration associated with volcanic-hosted massive sulphide, polymetallic, magmatic-hydrothermal vein, and porphyry mineralization can be distinguished, relative to normal lithological radioelement signatures, by characteristic eTh/K ratio lows. These examples show that effective interpretation of airborne gamma-ray spectrometry data must include all airborne variables and incorporate ground spectrometry, superficial and bedrock geochemistry and petrology. This information compliments magnetic, electromagnetic, geological and conventional geochemical data often collected during regional geoscience and mineral exploration programs. (author)

  12. An airborne gamma ray survey of parts of SW Scotland in February 1993. Final Report

    International Nuclear Information System (INIS)

    An airborne gamma ray survey was conducted for the Scottish Office Environment Department of coastal and inland parts of SW Scotland to define existing background levels, to locate features worthy of further attention, and to demonstrate the emergency response capabilities of radiometric methods. Coastal areas were surveyed with 500 m line spacing. Inland areas were specified to 2 km line spacing, however it was possible to achieve 1 km line spacing in the majority of the inland zone. The radiometric maps show clearly the distributions of each individual nuclide and indicate the contribution which individual localised features make to the overall gamma ray dose rate. Naturally occurring nuclides reflect the underlying geological and geomorphological contexts of the landscapes. The main granite intrusions, most notably at Cairnsmore of Fleet, the Loch Doon Granodiorite, Glencairn of Carsphairn, the Dalbeattie granite, and Criffel Pluton are readily visible in 40K, 214Bi and 208Tl maps, and control their local radiation environments. A number of areas of enhanced 214Bi, which may reflect radon potential, were noted. A transient radon associated 214Bi signal was observed on the west of the Wigtown peninsular during the survey. Examination of spectral data in the vicinity Dundrennan has confirmed that there is no evidence of widespread terrestrial contamination arising from the use of depleted uranium projectiles on the range. The 137Cs map indicates the environmental distribution of this nuclide in considerable detail. Levels of 137Cs range from approximately 2 kBq m-2, a level consistent with global weapons' testing fallout, from 2-40 kBq m-2 on terrestrial sites affected by deposition from the Chernobyl accident, and from 40 kBq m-2 to over 200 kBq m-2 on tide washed pastures which have accumulated marine sediments from the Irish sea. (author)

  13. Airborne gamma-ray spectrometer and magnetometer survey: Ukiah quadrangle, California. Final report

    International Nuclear Information System (INIS)

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten (10) areas over northern California and southwestern Oregon. These include the 20 x 10 NTMS quadrangles of Roseburg, Medford, Weed, Alturas, Redding, Susanville, Ukiah, and Chico along with the 10 x 20 areas of the Coos Bay quadrangle and the Crescent City/Eureka areas combined. This report discusses the results obtained over the Ukiah, California, map area. Traverse lines were flown in an east-west direction at a line spacing of six (6) miles. Tie lines were flown north-south approximately eighteen (18) miles apart. A total of 16,880.5 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 1517 line miles are in this quadrangle. The purpose of this study is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States

  14. Airborne gamma-ray spectrometer and magnetometer survey. Volume I. Final report

    International Nuclear Information System (INIS)

    An airborne combined radiometric and magnetic survey was performed for the Department of Energy (DOE) over the area covered by the Mariposa, California and Nevada; Fresno, California; and Bakersfield, Caifornia 1:250,000 National Topographic Map Series (NTMS) 10 x 20 quadrangle maps. The survey was a part of DOE's National Aerial Radiometric Reconnaissance (ARR) program, which in turn is a part of the National Uranium Resource Evaluation (NURE) program. Data were collected by a helicopter equipped with a gamma-ray spectrometer having a large crystal volume, and a high sensitivity proton precession magnetometer. The radiometric system was calibrated at the Walker Field Calibration pads and the Lake Mead Dynamic Test range. Data quality was ensured throughout the survey by daily test flights and equipment checks. Radiometric data were corrected for live time, aircraft and equipment background, cosmic background, atmospheric radon, Compton scatter, and altitude dependence. The corrected data were statistically evaluated, plotted, and contoured to produce anomaly maps based on the radiometric response of individual geological units. These maps were interpreted and an anomaly interpretation map produced. Volume I contains a description of the systems used in the survey, a discussion of the calibration of the systems, the data processing procedures, the data display format, the interpretation rationale, and the interpretation methodology. A separate Volume II for each quadrangle contains the data displays and the interpretation results

  15. Airborne gamma-ray spectrometer and magnetometer survey: Susanville quadrangle, California. Final report

    International Nuclear Information System (INIS)

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten (10) areas over northern California and southwestern Oregon. These include the 20 x 10 NTMS quadrangles of Roseburg, Medford, Weed, Alturas, Redding, Susanville, Ukiah, and Chico along with the 10 x 20 areas of the Coos Bay quadrangle and the Crescent City/Eureka areas combined. This report discusses the results obtained over the Susanville, California, map area. Traverse lines were flown in an east-west direction at a line spacing of six (6) miles. Tie lines were flown north-south approximately eighteen (18) miles apart. A total of 16,880.5 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 1642.8 line miles are in this quadrangle. The purpose of this study is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States

  16. Airborne gamma-ray spectrometer and magnetometer survey: Alturas quadrangle, California. Final report

    International Nuclear Information System (INIS)

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten (10) areas over northern California and southwestern Oregon. These include the 20 x 10 NTMS quadrangles of Roseburg, Medford, Weed, Alturas, Redding, Susanville, Ukiah, and Chico along with the 10 x 20 areas of the Coos Bay quadrangle and the Crescent City/Eureka areas combined. This report discusses the results obtained over the Alturas, California, map area. Traverse lines were flown in an east-west direction at a line spacing of six (6) miles. Tie lines were flown north-south approximately eighteen (18) miles apart. A total of 16,880.5 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 1631.6 line miles are in this quadrangle. The purpose of this study is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States

  17. Airborne gamma-ray spectrometer and magnetometer survey: Eureka quadrangle, California. Final report

    International Nuclear Information System (INIS)

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten (10) areas over northern California and southwestern Oregon. These include the 20 x 10 NTMS quadrangles of Roseburg, Medford, Weed, Alturas, Redding, Susanville, Ukiah, and Chico along with the 10 x 20 areas of the Coos Bay quadrangle and the Crescent City/Eureka areas combined. This report discusses the results obtained over the Eureka/Crescent City, California, map area. Traverse lines were flown in an east-west direction at a line spacing of six (6) miles. Tie lines were flown north-south approximately eighteen (18) miles apart. A total of 16,880.5 line miles of geophysical data were aquired, compiled, and interpreted during the survey, of which 349.5 line miles are in this area. The purpose of this study is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States

  18. Airborne gamma-ray spectrometer and magnetometer survey: Huron quadrangle, South Dakota. Final report

    International Nuclear Information System (INIS)

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over eleven (11) 20 x 10 NTMS quadrangles located in the states of Minnesota and Wisconsin and seven (7) 20 x 10 NTMS quadrangles in North and South Dakota. The quadrangles located within the North and South Dakota survey area include Devil's Lake, New Rockford, Jamestown, Aberdeen, Huron, Mitchell, and Sioux Falls. This report discusses the results obtained over the Huron map area. Traverse lines were flown in an east-west direction at a line spacing of six (6) miles. Tie lines were flown north-south approximately twenty-four (24) miles apart. A total of 21,481 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 1459 line miles are in this quadrangle. The purpose of this study is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States

  19. Airborne gamma-ray spectrometer and magnetometer survey Coos Bay, Oregon. Final report

    International Nuclear Information System (INIS)

    During the months of August, September, and October of 1980, Aero Service Division Western Geophysical Company of America conducted an airborne high sensitivity gamma-ray spectrometer and magnetometer survey over ten (10) areas over northern California and southwestern Oregon. These include the 20 x 10 NTMS quadrangles of Roseburg, Medford, Weed, Alturas, Redding, Susanville, Ukiah, and Chico along with the 10 x 20 areas of the Coos Bay quadrangle and the Crescent City/Eureka areas combined. This report discusses the results obtained over the Coos Bay, Oregon, map area. Line spacing was generally six miles for east/west traverses and eighteen miles for north/south tie lines over the northern one-half of the area. Traverses and tie lines were flown at three miles and twelve miles respectively over the southern one-half of the area. A total of 16,880.5 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 863.8 line miles are in this quadrangle

  20. Airborne gamma-ray spectrometer and magnetometer survey: Chico quadrangle, California. Final report

    International Nuclear Information System (INIS)

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten (10) areas over northern California and southwestern Oregon. These include the 20 x 10 NTMS quadrangles of Roseburg, Medford, Weed, Alturas, Redding, Susanville, Ukiah, and Chico along with the 10 x 20 areas of the Coos Bay quadrangle and the Crescent City/Eureka areas combined. This report discusses the results obtained over the Chico, California, map area. Traverse lines were flown in an east-west direction at a line spacing of three. Tie lines were flown north-south approximately twelve miles apart. A total of 16,880.5 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 3026.4 line miles are in the quadrangle. The purpose of this study is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States

  1. Airborne gamma-ray spectrometer and magnetometer survey, Medford Quadrangle Oregon. Final report

    International Nuclear Information System (INIS)

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten (10) areas over northern California and southwestern Oregon. These include the 20 x 10 NTMS quadrangles of Roseburg, Medford, Weed, Alturas, Redding, Susanville, Ukiah, and Chico along with the 10 x 20 areas of the Coos Bay quadrangle and the Crescent City/Eureka areas combined. This report discusses the results obtained over the Medford, Oregon, map area. Traverse lines were flown in an east-west direction at a line spacing of three miles. Tie lines were flown north-south approximately twelve miles apart. A total of 16,880.5 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 2925 line miles are in this quadrangle. The purpose of this study is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States

  2. Airborne gamma-ray spectrometer and magnetometer survey, Roseburg Quadrangle, Oregon. Final report

    International Nuclear Information System (INIS)

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten (10) areas over northern California and southwestern Oregon. These include the 20 x 10 NTMS quadrangles of Roseburg, Medford, Weed, Alturas, Redding, Susanville, Ukiah, and Chico along with the 10 x 20 areas of the Coos Bay quadrangle and the Crescent City/Eureka areas combined. This report discusses the results obtained over the Roseburg, Oregon, map area. Traverse lines were flown in an east-west direction at a line spacing of six (6) miles. Tie lines were flown north-south approximately eighteen (18) miles apart. A total of 16,880.5 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 1596 line miles are in this quadrangle. The purpose of this study is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States

  3. Airborne gamma-ray spectrometer and magnetometer survey Coos Bay, Oregon. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1981-05-01

    During the months of August, September, and October of 1980, Aero Service Division Western Geophysical Company of America conducted an airborne high sensitivity gamma-ray spectrometer and magnetometer survey over ten (10) areas over northern California and southwestern Oregon. These include the 2/sup 0/ x 1/sup 0/ NTMS quadrangles of Roseburg, Medford, Weed, Alturas, Redding, Susanville, Ukiah, and Chico along with the 1/sup 0/ x 2/sup 0/ areas of the Coos Bay quadrangle and the Crescent City/Eureka areas combined. This report discusses the results obtained over the Coos Bay, Oregon, map area. Line spacing was generally six miles for east/west traverses and eighteen miles for north/south tie lines over the northern one-half of the area. Traverses and tie lines were flown at three miles and twelve miles respectively over the southern one-half of the area. A total of 16,880.5 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 863.8 line miles are in this quadrangle.

  4. Airborne gamma-ray spectrometer and magnetometer survey: Chico quadrangle, California. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1981-05-01

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten (10) areas over northern California and southwestern Oregon. These include the 2/sup 0/ x 1/sup 0/ NTMS quadrangles of Roseburg, Medford, Weed, Alturas, Redding, Susanville, Ukiah, and Chico along with the 1/sup 0/ x 2/sup 0/ areas of the Coos Bay quadrangle and the Crescent City/Eureka areas combined. This report discusses the results obtained over the Chico, California, map area. Traverse lines were flown in an east-west direction at a line spacing of three. Tie lines were flown north-south approximately twelve miles apart. A total of 16,880.5 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 3026.4 line miles are in the quadrangle. The purpose of this study is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States.

  5. Airborne gamma-ray spectrometer and magnetometer survey: Susanville quadrangle, California. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1981-05-01

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten (10) areas over northern California and southwestern Oregon. These include the 2/sup 0/ x 1/sup 0/ NTMS quadrangles of Roseburg, Medford, Weed, Alturas, Redding, Susanville, Ukiah, and Chico along with the 1/sup 0/ x 2/sup 0/ areas of the Coos Bay quadrangle and the Crescent City/Eureka areas combined. This report discusses the results obtained over the Susanville, California, map area. Traverse lines were flown in an east-west direction at a line spacing of six (6) miles. Tie lines were flown north-south approximately eighteen (18) miles apart. A total of 16,880.5 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 1642.8 line miles are in this quadrangle. The purpose of this study is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States.

  6. Airborne gamma-ray spectrometer and magnetometer survey, Mitchell Quadrangle, South Dakota. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1981-04-01

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over eleven (11) 2/sup 0/ x 1/sup 0/ NTMS quadrangles located in the states of Minnesota and Wisconsin and seven (7) 2/sup 0/ x 1/sup 0/ NTMS quadrangles in North and South Dakota. The quadrangles located within the North and South Dakota survey area include Devil's Lake, New Rockford, Jamestown, Aberdeen, Huron, Mitchell, and Sioux Falls. This report discusses the results obtained over the Mitchell map area. The purpose of this program is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States. Traverse lines were flown in an east-west direction at a line spacing of six (6) miles. Tie lines were flown north-south approximately twenty-four (24) miles apart. A total of 21,481 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 1479 line miles are in this quadrangle.

  7. Airborne gamma-ray spectrometer and magnetometer survey, Mitchell Quadrangle, South Dakota. Final report

    International Nuclear Information System (INIS)

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over eleven (11) 20 x 10 NTMS quadrangles located in the states of Minnesota and Wisconsin and seven (7) 20 x 10 NTMS quadrangles in North and South Dakota. The quadrangles located within the North and South Dakota survey area include Devil's Lake, New Rockford, Jamestown, Aberdeen, Huron, Mitchell, and Sioux Falls. This report discusses the results obtained over the Mitchell map area. The purpose of this program is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States. Traverse lines were flown in an east-west direction at a line spacing of six (6) miles. Tie lines were flown north-south approximately twenty-four (24) miles apart. A total of 21,481 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 1479 line miles are in this quadrangle

  8. Airborne gamma-ray spectrometer and magnetometer survey: Huron quadrangle, South Dakota. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1981-04-01

    An airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over eleven (11) 2/sup 0/ x 1/sup 0/ NTMS quadrangles located in the states of Minnesota and Wisconsin and seven (7) 2/sup 0/ x 1/sup 0/ NTMS quadrangles in North and South Dakota. The quadrangles located within the North and South Dakota survey area include Devil's Lake, New Rockford, Jamestown, Aberdeen, Huron, Mitchell, and Sioux Falls. This report discusses the results obtained over the Huron map area. Traverse lines were flown in an east-west direction at a line spacing of six (6) miles. Tie lines were flown north-south approximately twenty-four (24) miles apart. A total of 21,481 line miles of geophysical data were acquired, compiled, and interpreted during the survey, of which 1459 line miles are in this quadrangle. The purpose of this study is to acquire and compile geologic and other information with which to assess the magnitude and distribution of uranium resources and to determine areas favorable for the occurrence of uranium in the United States.

  9. Airborne gamma-ray spectrometer and magnetometer survey: Wenatchee, Concrete, quadrangles (Washington). Final report

    International Nuclear Information System (INIS)

    An airborne combined radiometric and magnetic survey was performed for the Department of Energy (DOE) over the area covered by the Wenatchee and Concrete, 1:250,000 National Topographic Map Series (NTMS), quadrangle maps. The survey was part of DOE's National Uranium Resource Evaluation (NURE) program. Data were collected by a helicopter equipped with a gamma-ray spectrometer with a large crystal volume, and with a high sensitivity proton precession magnetometer. The radiometric system was calibrated at the Walker Field Calibration pads and the Lake Mead Dynamic Test Range. Data quality was ensured during the survey by daily test flights and equipment checks. Radiometric data were corrected for live time, aircraft and equipment background, cosmic background, atmospheric radon, Compton scatter, and altitude dependence. The corrected data were statistically evaluated, plotted, and contoured to produce anomaly maps based on the radiometric response of individual geological units. The anomalies were interpreted and an interpretation map produced. Volume I contains a description of the systems used in the survey, a discussion of the calibration of the systems, the data collection procedures, the data processing procedures, the data presentation, the interpretation rationale, and the interpretation methodology. A separate Volume II for each quadrangle contains the data displays and the interpretation results

  10. Airborne gamma-ray spectrometer and magnetometer survey: Iditarod quadrangle (Alaska). Final report

    International Nuclear Information System (INIS)

    During the months of July, August, and September 1979, an airborne high sensitivity gamma-ray spectrometer and magnetometer survey was conducted over ten 30 x 10 NTMS quadrangles of West-Central Alaska. The results obtained over the Iditarod map area are reported. The final data are presented in four different forms: on magnetic tape; on microfiche; in graphic form as profiles and histograms; and in map form as anomaly maps, flight path maps, and computer printer maps. The histograms and the multiparameter profiles are presented with the anomaly maps and flight path map in a separate volume. Anomalous radioactivity levels are encountered in mine locations on the Idatarod quadrangle, on both the uranium and thorium spectral windows. Three of these are relatively restricted, discrete anomalous features. The other six are in two groups of comparatively long intervals variably high in uranium and thorium series radiation, and they are aligned in such a manner as to suggest that their source is in a length zone or formation enriched in uranium and thorium mineralization

  11. The development of airborne gamma-ray spectrometry: case study in technological innovation and acceptance

    International Nuclear Information System (INIS)

    Airborne γ-ray spectrometry is now accepted as a technique with worldwide applications for geological mapping, mineral exploration and environmental monitoring. The first suggestions to use airborne radiation detectors for uranium exploration were made in 1943. Early results were disappointing; progress resulted from advances in nuclear instrumentation combined with recognition of the need for large detector-crystal arrays. Development of an effective operational system required the integration of geochemical and geological knowledge with nuclear physics, extending over two decades. The establishment of standards and calibration procedures allowed the first maps of surface radioelement concentrations based on quantitative airborne γ-ray spectrometry to be published in 1971. User-acceptance of the method grew from extensive demonstration of its capabilities, made obvious with the introduction of colour map displays. (author)

  12. European coordination of environmental airborne gamma ray spectrometry. Final report 1999

    International Nuclear Information System (INIS)

    This Concerted Action was funded under the EURATOM Nuclear Fission Safety Programme of the Fourth Framework Programme, and was initiated to address transnational issues relating to environmental airborne gamma ray spectrometry (AGS). Significant development of AGS systems and teams has taken place within Europe during the period following the Chernobyl accident. The technique is increasingly recognised as particularly relevant to emergency response. It is also uniquely capable of acquiring data on anthropogenic and natural radionuclides on regional, national and international scales, for reference purposes, ecological studies and epidemiological research. Prior to this EU programme the methodologies and systems used by European AGS teams had undergone rapid and largely uncoordinated development. This raised questions about comparability of systems, applications, and data between teams, duplication of research, the scope for transnational cooperation and standardisation, and future research and development needs in the field. This project, which brought together ten AGS teams from across Europe, was formed to address these issues. The work was conducted in three stages and has largely succeeded in its objectives. An active communication network was developed for collaboration and exchange of information, and to start the process of harmonisation of the different methodologies used by individual AGS teams. Two formal partners' meetings were organised, the first aimed at defining the EU capability in AGS, the second, in the form of an international symposium (RADMAGS), was aimed at reviewing developments on future research needs and the scope for standardisation. This report gives full details of the project and its deliverables together with discussion of the further needs in support of transnational harmonisation of this topic. The European Capability for AGS was defined at an early stage of the project, and monitored throughout. An EU Bibliography on AGS

  13. 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.

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

    International Nuclear Information System (INIS)

    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

  15. The screening effect of a tropical forest on airborne gamma-ray spectrometry

    International Nuclear Information System (INIS)

    This work estimates the screening effect of a tropical rain forest on airborne γ-ray measurements. The screening effect is expressed as a multiplicative coefficient. The results were obtained using cylindrical sources on the ground. A layered approximation was used to obtain a first approximation for the screening coefficient for the biomass of the forest. However, the layered approach, neglects the strong anisotropy of the absorber. This is particularly conspicuous for the trunks of trees that contribute up to 80% to the total value of the screening coefficient. Due to the anisotropy of the absorbers layered calculations may produce upward biased screening coefficient values. A Monte Carlo simulation was used to calculate the effect of anisotropy on the screening coefficient of the biomass. The situations where the anisotropy can be neglected are shown here. An additional source of bias, the radiation from the biomass itself, is also estimated. With the results of this work it is possible to estimate a lower limit for the accuracy of airborne γ-radiation measurements taken over a tropical forest. (author)

  16. Airborne gamma ray measurements conducted during an international trial in Finland

    International Nuclear Information System (INIS)

    The Scottish Universities Research and Reactor Centre (SURRC) contributed to the Resume 95 exercise by developing the calibration site at Vesivehmaa, and by participating in the airborne gamma spectrometry (AGS) part of the study. This paper summarises the airborne survey results from the SURRC team. The AGS tasks included fallout mapping of a 6x3 km area in central Finland with nominal 150 m line spacing, and a time constrained search for an undisclosed number of hidden radioactive sources. Measurements at the calibration site were also taken to provide a basis for traceable cross comparison between each teams' quantification procedures at a single, well characterised, location. A full set of calibrated maps of Chernobyl deposition and natural radionuclides, together with overlays corresponding to topography, roads, rivers and lakes were finished during the survey and displayed at the end of the exercise. The main survey area (Area II) was found to have a mean 137Cs deposition of 64.4±24.4 kBq m-2, based on the calibration appropriate to the Vesivehmaa site. The major point sources in Area III were discovered, although the collimated 137Cs and 60Co sources were not. Retrospective analysis has shown that sources Cs3 and Cs4 were not significantly above local environmental levels in our data set; whereas the low activity 60Co source Co3 was detected. This confirms the improved sensitivity of AGS source searches to nuclides which are not already present as environmental contaminants. The collimated 192Ir was found both using scattered radiation and from full energy lines detected with a Ge detector. The 99mTc was located using a ratio of low energy integrals from the NaI spectra. (EG)

  17. Airborne gamma ray measurements conducted during an international trial in Finland

    Energy Technology Data Exchange (ETDEWEB)

    Sanderson, D.C.W.; Allyson, J.D.; McConville, P.; Murphy, S.; Smith, J. [Scottish Univ. Research and Reactor Centre, Glasgow, Scotland (United Kingdom)

    1997-12-31

    The Scottish Universities Research and Reactor Centre (SURRC) contributed to the Resume 95 exercise by developing the calibration site at Vesivehmaa, and by participating in the airborne gamma spectrometry (AGS) part of the study. This paper summarises the airborne survey results from the SURRC team. The AGS tasks included fallout mapping of a 6x3 km area in central Finland with nominal 150 m line spacing, and a time constrained search for an undisclosed number of hidden radioactive sources. Measurements at the calibration site were also taken to provide a basis for traceable cross comparison between each teams` quantification procedures at a single, well characterised, location. A full set of calibrated maps of Chernobyl deposition and natural radionuclides, together with overlays corresponding to topography, roads, rivers and lakes were finished during the survey and displayed at the end of the exercise. The main survey area (Area II) was found to have a mean {sup 137}Cs deposition of 64.4{+-}24.4 kBq m{sup -2}, based on the calibration appropriate to the Vesivehmaa site. The major point sources in Area III were discovered, although the collimated {sup 137}Cs and {sup 60}Co sources were not. Retrospective analysis has shown that sources Cs3 and Cs4 were not significantly above local environmental levels in our data set; whereas the low activity {sup 60}Co source Co3 was detected. This confirms the improved sensitivity of AGS source searches to nuclides which are not already present as environmental contaminants. The collimated {sup 192}Ir was found both using scattered radiation and from full energy lines detected with a Ge detector. The {sup 99m}Tc was located using a ratio of low energy integrals from the NaI spectra. (EG). 28 refs.

  18. The effects of a tropical rain forest cover on airborne gamma-ray spectrometry

    International Nuclear Information System (INIS)

    Theoretical calculations have been made to estimate the attenuation and the generation of gamma photons by a model of a tropical rain forest environment. For typical flight altitudes of 100 meters, it is shown that a 35 meter high canopy can attenuate from 40% to 60% of the original gamma photons, depending on the energy considered. It is also shown that the 1.46 MeV photopeak of 40-K measured at flight altitudes is completely dominated by the forest generated component, whereas this effect is negligible for the 2.62 MeV of 208-Tl and the 1.76 MeV of 214-Bi. Of major importance are the effects of forest clearings on the gamma-ray spectrum which can lead to serious misinterpretations of aerial profile data if not taken into account. A short review on the biocycles of potassium from the soil to the biomass of the tropical rain forest is included in the article. A simple experiment has also been made to demonstrate the attenuation due to a forest biomass on the gamma radiation emitted by the soil. (Author)

  19. Airborne gamma-ray and magnetic anomaly signatures of serpentinite in relation to soil geochemistry, northern California

    International Nuclear Information System (INIS)

    Serpentinized ultramafic rocks and associated soils in northern California are characterized by high concentrations of Cr and Ni, low levels of radioelements (K, Th, and U) and high amounts of ferrimagnetic minerals (primarily magnetite). Geophysical attributes over ultramafic rocks, which include airborne gamma-ray and magnetic anomaly data, are quantified and provide indirect measurements on the relative abundance of radioelements and magnetic minerals, respectively. Attributes are defined through a statistical modeling approach and the results are portrayed as probabilities in chart and map form. Two predictive models are presented, including one derived from the aeromagnetic anomaly data and one from a combination of the airborne K, Th and U gamma-ray data. Both models distinguish preferential values within the aerogeophysical data that coincide with mapped and potentially unmapped ultramafic rocks. The magnetic predictive model shows positive probabilities associated with magnetic anomaly highs and, to a lesser degree, anomaly lows, which accurately locate many known ultramafic outcrops, but more interestingly, locate potentially unmapped ultramafic rocks, possible extensions of ultramafic bodies that dip into the shallow subsurface, as well as prospective buried ultramafic rocks. The airborne radiometric model shows positive probabilities in association with anomalously low gamma radiation measurements over ultramafic rock, which is similar to that produced by gabbro, metavolcanic rock, and water bodies. All of these features share the characteristic of being depleted in K, Th and U. Gabbro is the only rock type in the study area that shares similar magnetic properties with the ultramafic rock. The aerogeophysical model results are compared to the distribution of ultramafic outcrops and to Cr, Ni, K, Th and U concentrations and magnetic susceptibility measurements from soil samples. Analysis of the soil data indicates high positive correlation between

  20. Airborne gamma-ray and magnetic anomaly signatures of serpentinite in relation to soil geochemistry, northern California

    Science.gov (United States)

    McCafferty, A.E.; Van Gosen, B. S.

    2009-01-01

    Serpentinized ultramafic rocks and associated soils in northern California are characterized by high concentrations of Cr and Ni, low levels of radioelements (K, Th, and U) and high amounts of ferrimagnetic minerals (primarily magnetite). Geophysical attributes over ultramafic rocks, which include airborne gamma-ray and magnetic anomaly data, are quantified and provide indirect measurements on the relative abundance of radioelements and magnetic minerals, respectively. Attributes are defined through a statistical modeling approach and the results are portrayed as probabilities in chart and map form. Two predictive models are presented, including one derived from the aeromagnetic anomaly data and one from a combination of the airborne K, Th and U gamma-ray data. Both models distinguish preferential values within the aerogeophysical data that coincide with mapped and potentially unmapped ultramafic rocks. The magnetic predictive model shows positive probabilities associated with magnetic anomaly highs and, to a lesser degree, anomaly lows, which accurately locate many known ultramafic outcrops, but more interestingly, locate potentially unmapped ultramafic rocks, possible extensions of ultramafic bodies that dip into the shallow subsurface, as well as prospective buried ultramafic rocks. The airborne radiometric model shows positive probabilities in association with anomalously low gamma radiation measurements over ultramafic rock, which is similar to that produced by gabbro, metavolcanic rock, and water bodies. All of these features share the characteristic of being depleted in K, Th and U. Gabbro is the only rock type in the study area that shares similar magnetic properties with the ultramafic rock. The aerogeophysical model results are compared to the distribution of ultramafic outcrops and to Cr, Ni, K, Th and U concentrations and magnetic susceptibility measurements from soil samples. Analysis of the soil data indicates high positive correlation between

  1. Insights into the Structure and Surface Geology of Isla Socorro, Mexico, from Airborne Magnetic and Gamma-Ray Surveys

    Science.gov (United States)

    Paoletti, V.; Gruber, S.; Varley, N.; D'Antonio, M.; Supper, R.; Motschka, K.

    2016-05-01

    The island of Socorro is located in the eastern Pacific Ocean, 650 km off the coast of Mexico. It is a rare example of an oceanic volcanic island whose above sea level volume is made up mostly of peralkaline trachytes and rhyolites, with subordinate mafic rocks. Subaerial volcanism started several hundred thousand years ago and continues until recent times. We present an investigation of surface and subsurface geology of the island, based on the first detailed extensive geophysical survey on the island. Acquired airborne magnetic and gamma-ray data were compared to existing geological information and supplemented with field investigations and satellite imagery. Magnetic data show a wide minimum in the central part of the island, possibly connected to a high-temperature zone in the deeper central portion of the volcano, likely to be due to a still hot magma body. The data also depict two parallel edges possibly suggesting the existence of a nested caldera. Analysis on upward continued magnetic data by recent imaging techniques highlighted two deep sources located around 5 km b.s.l., interpreted as feeding structures that are now filled with crystalline rocks. Gamma-ray data have been interpreted through integration with the geological survey results. Several previously known volcanic deposits have been identified based on radioelement distribution, and others have been redefined based on field evidence. A new succession of volcanic members is proposed, to be verified through more detailed geological mapping, geochemical analyses of rock samples and radiometric dating.

  2. Statistical interpretation of airborne gamma-ray spectrometric data using factor analysis

    International Nuclear Information System (INIS)

    The statistical technique of factor analysis provides a quantitative and non-subjective means of synthesising and correlationg data from gamma-ray spectrometry surveys. Factor analysis was applied to data from an aerial survey of the Freer-Three Rivers area in South Texas. Variables used were corrected count-rates for potassium, uranium, and thorium, total count, and the ratios 214Bi/40K, 214Bi/208Tl, and 208Tl/40K. Analysis showed that three factors were sufficient to represent all seven variables. Statistical groupings correspond reasonably well to the mapped formations in the area, but some patterns suggest geological complexities which do not appear on available maps. The analysis identifies unusual groupings that are unlike surrounding patterns; many of these occur over known oil and gas pools and appear to indicate geochemically abnormal ground. (author)

  3. Airborne gamma ray measurements conducted during an international trial in Finland

    International Nuclear Information System (INIS)

    The Scottish Universities Research and Reactor Centre (SURRC) contributed to the RESUME 95 exercise by developing the calibration site at Vesivehmaa, and by participating in the airborne gamma spectrometry (AGS) part of the study. This report provides a full technical description of the AGS results from the SURRC team. The AGS tasks included fallout mapping of a 6x3 km area in central Finland with nominal 150 m line spacing, and a time constrained search for an undisclosed number of hidden radioactive sources. Measurements at the calibration site were also taken to provide a basis for traceable cross comparison between each teams' quantification procedures at a single, well characterised, location. A decision was taken to transport the SURRC AGS system by land and sea, and to utilise a Finnish Twin Star Helicopter chartered from Helijet OY from Rovaniemi and flown by a UK pilot. Prior to departure the SURRC spectrometer, comprising a 16 l. Nal detector and a 50% GMX detector, was checked, and NaI stripping ratios measured using pads, absorbers and active sheets. Installation and CAA approval details were forwarded to Finland, together with the CV of the proposed pilot, to obtain clearances for the operation. Maps of the study area were digitised to form geographical backdrops for the AGS results. The equipment was transported in a single Landrover, via Harwich, north Germany, and Helsinki; a journey taking 2 days and involving 3 overland stages and two ferries. The system was installed at tested in the Helijet aircraft immediately prior to the study. The SURRC team was the first to fly starting at 8.00 am on the day of study. Fallout mapping in Area II was accomplished within the allotted 2 hour period, and the source search conducted in Area III within the allotted hour. Immediately on landing the positions of 3 hidden sources were reported to the organisers, with paper copies of tabular data available within a few minutes of landing, and initial mapping taking

  4. Airborne gamma-ray spectrometer and magnetometer survey: San Luis Obispo (California), Santa Maria (California). Final report

    International Nuclear Information System (INIS)

    An airborne combined radiometric and magnetic survey was performed over the area covered by the Santa Maria and San Luis Obispo, California 1:250,000 National Topographic Map Series (NTMS) 10 x 20 quadrangle maps. The survey was a part of DOE's National Aerial Radiometric Reconnaissance program, which is in turn a part of the National Uranium Resource Evaluation (NURE) program. Data were collected by a helicopter equipped with a gamma-ray spectrometer having a large crystal volume, and a high sensitivity proton precession magnetometer. The radiometric system was calibrated at the Walker Field Calibration pads and the Lake Mead Dynamic Test range. Data quality was ensured throughout the survey by daily test flights and equipment checks. Radiometric data were corrected for live time, aircraft and equipment background, cosmic background, atmospheric radon, Compton scatter, and altitude dependence. The corrected data were statistically evaluated, plotted and contoured to produce anomaly maps based on the radiometric response of individual geological units. These maps were interpreted and an anomaly interpretation map produced. Volume I contains a description of the systems used in the survey, a discussion of the calibration of the systems, the data processing procedures, the data display format, the interpretation rationale, and the interpretation methodology. A separate Volume II for each quadrangle contains the data displays and the interpretation results

  5. Airborne gamma-ray spectrometer and magnetometer survey, Copalis Beach, Seattle, Cape Flattery, Victoria, Quadrangles (Washington). Final report

    International Nuclear Information System (INIS)

    An airborne combined radiometric and magnetic survey was performed for the Department of Energy (DOE) over the area covered by the Copalis Beach, Seattle, Victoria, and Cape Flattery, 1:250,000 National Topographic Map Series (NTMS), quadrangle maps. The survey was part of DOE's National Uranium Resource Evaluation (NRRE) program. Data were collected by helicopters equipped with gamma-ray spectrometers with large crystal volumes, and with high sensitivity proton precession magnetometers. The radiometric systems were calibrated at the Walker Field Calibration pads and the Lake Mead Dynamic Test Range. Data quality was ensured during the survey by daily test flights and equipment checks. Radiometric data were corrected for live time, aircraft and equipment background, cosmic background, atmospheric radon, Compton Scatter, and altitude dependence. The corrected data were statistically evaluated, plotted, and contoured to produce anomaly maps based on the radiometric response of individual geological units. The anomalies were interpreted and an interpretation map produced. Volume I contains a description of the systems used in the survey, a discussion of the calibration of the systems, the data collection procedure, the data processing procedures, the data presentation; the interpretation rationale, and the interpretation methodology. A separate Volume II for each quadrangle contains the data displays and the interpretation results

  6. Radon potential mapping of the Tralee-Castleisland and Cavan areas (Ireland) based on airborne gamma-ray spectrometry and geology.

    Science.gov (United States)

    Appleton, J D; Doyle, E; Fenton, D; Organo, C

    2011-06-01

    The probability of homes in Ireland having high indoor radon concentrations is estimated on the basis of known in-house radon measurements averaged over 10 km × 10 km grid squares. The scope for using airborne gamma-ray spectrometer data for the Tralee-Castleisland area of county Kerry and county Cavan to predict the radon potential (RP) in two distinct areas of Ireland is evaluated in this study. Airborne data are compared statistically with in-house radon measurements in conjunction with geological and ground permeability data to establish linear regression models and produce radon potential maps. The best agreement between the percentage of dwellings exceeding the reference level (RL) for radon concentrations in Ireland (% > RL), estimated from indoor radon data, and modelled RP in the Tralee-Castleisland area is produced using models based on airborne gamma-ray spectrometry equivalent uranium (eU) and ground permeability data. Good agreement was obtained between the % > RL from indoor radon data and RP estimated from eU data in the Cavan area using terrain specific models. In both areas, RP maps derived from eU data are spatially more detailed than the published 10 km grid map. The results show the potential for using airborne radiometric data for producing RP maps. PMID:21617292

  7. Radon potential mapping of the Tralee-Castleisland and Cavan areas (Ireland) based on airborne gamma-ray spectrometry and geology

    Energy Technology Data Exchange (ETDEWEB)

    Appleton, J D [British Geological Survey (BGS), Keyworth, Nottingham NG12 5GG (United Kingdom); Doyle, E [Geological Survey of Ireland (GSI), Beggars Bush, Haddington Road, Dublin 4 (Ireland); Fenton, D; Organo, C, E-mail: jda@bgs.ac.uk [Radiological Protection Institute of Ireland (RPII), 3 Clonskeagh Square, Dublin 14 (Ireland)

    2011-06-01

    The probability of homes in Ireland having high indoor radon concentrations is estimated on the basis of known in-house radon measurements averaged over 10 km x 10 km grid squares. The scope for using airborne gamma-ray spectrometer data for the Tralee-Castleisland area of county Kerry and county Cavan to predict the radon potential (RP) in two distinct areas of Ireland is evaluated in this study. Airborne data are compared statistically with in-house radon measurements in conjunction with geological and ground permeability data to establish linear regression models and produce radon potential maps. The best agreement between the percentage of dwellings exceeding the reference level (RL) for radon concentrations in Ireland (% > RL), estimated from indoor radon data, and modelled RP in the Tralee-Castleisland area is produced using models based on airborne gamma-ray spectrometry equivalent uranium (eU) and ground permeability data. Good agreement was obtained between the % > RL from indoor radon data and RP estimated from eU data in the Cavan area using terrain specific models. In both areas, RP maps derived from eU data are spatially more detailed than the published 10 km grid map. The results show the potential for using airborne radiometric data for producing RP maps.

  8. 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...

  9. Significance of Airborne Gamma-ray spectrometric data of Umm bisilla Area, central Eastern Desert, Egypt

    International Nuclear Information System (INIS)

    Umm bisilla area, located in the Central Eastern Desert of Egypt, consists mainly of basement rocks. The present investigation of the airborne spectrometric data is to define the meaningful anomalies from the raw data by applying the significance factor techniques, by calculating the significant radioactive provinces. Determination of the gross structural pattern and broad variations in composition of the crystalline basement, to define the relationships between the tectonic features of the area as interpreted from aeromagnetic data, with the significant anomalies revealed from spectrometric data was carried out through the application of different magnetic techniques. Five significant uraniferous zones were detected associated with Umm Bisilla granite, amphibolite, and grey granite. The intersection of the structural lineaments interpreted from aeromagnetic data illustrated good correlation with the significant uranium anomalous zones interpreted from spectrometric data, and indicated that the concentration is structurally. 15 figs

  10. An airborne gamma ray survey of the Duddon Estuary in February 1993

    International Nuclear Information System (INIS)

    An aerial survey of radioactivity of the Duddon estuary (United Kingdom was conducted on 25th February 1993, using an 8 litre NaI detector. Maps of the distribution of 137Cs, 40K, 214Bi, 208Tl and estimated gamma dose rates are presented. The distribution of 137Cs on estuarine and marsh areas is clearly defined, with the greatest concentrations largely following the salt marsh boundaries. The gamma dose rate map indicates that Cs contamination is a controlling dose contributor. Natural radiation shows considerable variations, reflecting the local geological and geomorphological structures. The 214Bi map shows an anomaly in the vicinity of Millom. Since 214Bi is a radon daughter, this signal may have a dynamic component. Alternatively it may originate from industrial or mining wastes in the area. (5 figures). (UK)

  11. Development and Building of Radioactive Concrete Pads for calibration of the airborne and ground gamma-ray spectrometers, used in mineral exploration and hydrocarbons

    International Nuclear Information System (INIS)

    Eight transportable calibration pads were built in to be used as concentration standards for portable and airborne gamma-ray spectrometers calibrations. The pads construction procedure is described in full detail. The pads, with dimensions of 1 m x 1 m x 0,30 m and masses between 593 kg and 673 kg were made radioactive by the addition of different amounts of k-feldspar, caldasite and monazitic sand to the concrete masses. The potassium, uranium and thorium concentration vary significantly in the pads, reaching maximum values of 5,7% of K, 45,6 ppm eU and 137 ppm eTh. The distribution of the gamma radiation flux from the pads surfaces and the heterogeneity magnitudes of the radioactive elements concentration were experimentally established. An example of gamma-ray spectrometer calibration is presented. (author)

  12. Development and calibration of a real-time airborne radioactivity monitor using direct gamma-ray spectrometry with two scintillation detectors

    International Nuclear Information System (INIS)

    The implementation of in-situ gamma-ray spectrometry in an automatic real-time environmental radiation surveillance network can help to identify and characterize abnormal radioactivity increases quickly. For this reason, a Real-time Airborne Radioactivity Monitor using direct gamma-ray spectrometry with two scintillation detectors (RARM-D2) was developed. The two scintillation detectors in the RARM-D2 are strategically shielded with Pb to permit the separate measurement of the airborne isotopes with respect to the deposited isotopes.In this paper, we describe the main aspects of the development and calibration of the RARM-D2 when using NaI(Tl) or LaBr3(Ce) detectors. The calibration of the monitor was performed experimentally with the exception of the efficiency curve, which was set using Monte Carlo (MC) simulations with the EGS5 code system. Prior to setting the efficiency curve, the effect of the radioactive source term size on the efficiency calculations was studied for the gamma-rays from 137Cs. Finally, to study the measurement capabilities of the RARM-D2, the minimum detectable activity concentrations for 131I and 137Cs were calculated for typical spectra at different integration times. - Highlights: • A real-time airborne radioactivity monitor was developed. • The monitor is formed using two scintillation detectors for gamma-ray spectrometry. • The detectors are shielded with Pb. One detector is pointing up and the other down. • The monitors were calibrated using experimental data and Monte Carlo simulations. • The efficiency calculations and MDAC values are given

  13. Airborne gamma-ray spectrometer and magnetometer survey: Weed quadrangle, California. Final report

    International Nuclear Information System (INIS)

    Twelve anamolous areas attributable to gamma radiation in the uranium spectral window, and twenty-three in the thorium channel, have been recognized and delineated on the Weed quadrangle. The majority of the uranium anomalies are located in the southwestern part of the map sheet. Most of these are correlated with the pre-Cretaceous metamorphic rock system and the Mesozoic granitic rocks intrusive into it. Of the twenty-three anomalous areas of increased gamma radiation in the thorium spectral window, most are located in the northeast and the east center in a north-south trending belt. However, this apparent alignment is probably fortuitous as the individual anomalies are correlated with several different rock formations. Three are correlated with upper Cretaceous marine sediments, six with Ordovician marine sediments, two with Mesozoic granitic intrusives, and two with Silurian marine sediments. In the northwestern part of the quadrangle, four thorium radiation anomalies are delineated over exposures of upper Jurassic marine rocks. Anomaly 6, in the southwest, warrants attention as it suggests strong radiation in the uranium channel with little or no thorium radiation. The uranium/thorium and uranium/potassium ratio anomalies are also strong, supporting the likelihood of uranium enrichment. The feature is located on line 540, fiducials 7700 to 7720. Anomaly 7, on line 540, fiducials 8390 to 8420, shows similar characteristics although a minor thorium excursion is present. Anomaly 10, on line 3010 fiducials 9820 to 9840, is also characterized by a strong uranium radiation spike, with minor thorium radiation. The uranium/thorium and uranium/potassium ratio anomalies are well defined and relatively intense

  14. Mapping the terrestrial air-absorbed gamma dose rate based on the data of airborne gamma-ray spectrometry in southern cities of China

    International Nuclear Information System (INIS)

    An environmental radioactivity survey by Airborne Gamma-ray Spectrometry (AGS) on a large scale was undertaken in Zhuhai Zone (ZZ) and Shenzhen Zone (SZ), which include major cities in southern China, covering areas of 3800 km2 and 4660 km2, respectively. The estimated dose rates by AGS have been compared with observed results by ionization chamber and portable dosemeter. Maps of the terrestrial dose rate at 1m above ground level have been calculated based on the data of AGS. The mean dose rates are 84.37 ± 51.69 and 82.10 ± 32.98 nGy/h in ZZ and SZ, and the maximum rates are 343.11 and 368.36 nGy/h, respectively. Dose rates in some places are above 180 nGy/h; the areas covered where 149 km2 in ZZ and 43 km2 in SZ. The dominant geological conditions that evidently contribute to the radioactive anomalies are outcrops of Middle and Late Jurassic and Cretaceous biotitic-granite. The growth of industrialization and urbanization has dramatically altered radiation background. Stone mining results in the increase of radiation levels with maximum dose rates approaching 368.36 nGy/h in an open pit. The investigation results provide valuable background data and give a good example for mapping nationwide natural radiation terrestrial dose rates in China by AGS. (author)

  15. Gamma-ray methods

    International Nuclear Information System (INIS)

    Bulk analysis techniques using gamma radiation are described. The methods include gamma-ray induced reactions, selective gamma-ray scattering and methods which rely on natural radioactivity. The gamma-ray resonance scattering technique can be used for the determination of copper and nickel in bulk samples and drill cores. The application of gamma-gamma methods to iron ore analysis is outlined

  16. The airborne survey of natural gamma radiation level in China

    International Nuclear Information System (INIS)

    Airborne survey of natural gamma radiation level is a fast and effective method for evaluating environment radiation. This paper introduces some results about the investigation of gamma radiation level using airborne gamma ray spectrometer and associated NaI(Tl) crystal detector system by Airborne Survey and Remote Sensing Center of Nuclear Industry. The results of the natural radiation level in the regions surrounding Qinshan Nuclear Power Plant and Shanghai City were showed and analyzed emphatically. Air absorbed dose rate belongs to normal to low. The average is 52.6 nGy/h in Qinshan and 52.2 nGy/h in Shanghai. Among, the maximum is up to 72.5 nGy/h in the mountain forest, the second is approximately 68.4 nGy/h in town, 50∼60 nGy/h in cropland, and 25 nGy/h in beach

  17. The airborne survey of natural gamma radiation level in China

    Energy Technology Data Exchange (ETDEWEB)

    Mingkao, Hu; Renkang, Gu; Jiangqi, Fang; Chongtao, Qiu [Airborne Survey and Remote Sensing Center of Nuclear Industry, Shijiazhuang (China)

    2002-07-01

    Airborne survey of natural gamma radiation level is a fast and effective method for evaluating environment radiation. This paper introduces some results about the investigation of gamma radiation level using airborne gamma ray spectrometer and associated NaI(Tl) crystal detector system by Airborne Survey and Remote Sensing Center of Nuclear Industry. The results of the natural radiation level in the regions surrounding Qinshan Nuclear Power Plant and Shanghai City were showed and analyzed emphatically. Air absorbed dose rate belongs to normal to low. The average is 52.6 nGy/h in Qinshan and 52.2 nGy/h in Shanghai. Among, the maximum is up to 72.5 nGy/h in the mountain forest, the second is approximately 68.4 nGy/h in town, 50{approx}60 nGy/h in cropland, and 25 nGy/h in beach.

  18. Gamma-ray astronomy

    OpenAIRE

    Pohl, Martin

    2001-01-01

    This paper summarizes recents results in gamma-ray astronomy, most of which were derived with data from ground-based gamma-ray detectors. Many of the contributions presented at this conference involve multiwavelength studies which combine ground-based gamma-ray measurements with optical data or space-based X-ray and gamma-ray measurements. Besides measurements of the diffuse emission from the Galaxy, observations of blazars, gamma-ray bursts, and supernova remnants this paper also covers theo...

  19. Utilization of airborne gamma ray spectrometric data for geological mapping, radioactive mineral exploration and environmental monitoring of southeastern Aswan city, South Eastern Desert, Egypt

    Science.gov (United States)

    Youssef, Mohamed A. S.; Elkhodary, Shadia T.

    2013-12-01

    The present work utilizes airborne gamma ray spectrometric data in a trial to refine surface geology of igneous, metamorphic and sedimentary rocks, detect any radioactive mineralization and monitor environment at southeastern Aswan city, South Eastern Desert, Egypt. This area is mainly covered with igneous rocks (younger granites, older granites, metasediments, metavolcanics, metagabbro, Tertiary basalt and ring complex), metamorphic rocks as well as sedimentary rocks (Um Barmil Formation, Timsah Formation, Abu Aggag Formation and wadi sediments). Airborne gamma ray spectrometry can be very helpful in mapping surface geology. This provides estimates of the apparent surface concentrations of the most common naturally occurring radioactive elements, such as potassium (K), equivalent uranium (eU) and equivalent thorium (eTh). This is based on the assumption that, the absolute and relative concentrations of these radioelements vary measurably and significantly with lithology. The composite image technique is used to display simultaneously three parameters of the three radioelement concentrations and their three binary ratios on one image. The technique offers much in terms of lithological discrimination, based on colour differences and showed efficiency in defining areas, where different lithofacies occur within areas mapped as one continuous lithology. The integration between surface geological information and geophysical data led to detailing the surface geology and the contacts between different rock units. Significant locations or favourable areas for uranium exploration are defined, where the measurements exceed (X + 2S), taking X as the arithmetic mean of eU, eU/eTh and eU/K measurements and S as the standard deviation corresponding to each variables. The study area shows the presence of four relatively high uraniferous zones. These zones cannot be ignored and need further ground follow-up. In addition, the trend analysis based on the three radioelement maps and

  20. Airborne gamma-ray spectrometer and magnetometer survey: Forsyth quadrangle, Round Up quadrangle, Hardin quadrangle (Montana), Sheridan quadrangle, (Wyoming). Final report

    International Nuclear Information System (INIS)

    An airborne combined radiometric and magnetic survey was performed for the Department of Energy (DOE) over the area covered by the Forsyth, Hardin, and Sheridan, and Roundup, 1:250,000 National Topographic Map Series (NTMS), quadrangle maps. The survey was part of DOE's National Uranium Resource Evaluation (NURE) program. Data were collected by a helicopter equipped with a gamma-ray spectrometer with a large crystal volume, and with a high sensitivity proton precession magnetometer. The radiometric system was calibrated at the Walker Field Calibration Pads and the Lake Mead Dynamic Test Range. Data quality was ensured during the survey by daily test flights and equipment checks. Radiometric data were corrected for live time, aircraft and equipment background, cosmic background, atmospheric radon, Compton scatter, and altitude dependence. The corrected data were statistically evaluated, plotted, and contoured to produce anomaly maps based on the radiometric response of individual geological units. The anomalies were interpreted and an interpretation map produced. Volume I contains a description of the systems used in the survey, a discussion of the calibration of the systems, the data collection procedures, the data processing procedures, the data presentation, the interpretation rationale, and the interpretation methodology. A separate Volume II for each quadrangle contains the data displays and the interpretation results

  1. Gamma-ray Astronomy

    CERN Document Server

    Hinton, Jim

    2007-01-01

    The relevance of gamma-ray astronomy to the search for the origin of the galactic and, to a lesser extent, the ultra-high-energy cosmic rays has long been recognised. The current renaissance in the TeV gamma-ray field has resulted in a wealth of new data on galactic and extragalactic particle accelerators, and almost all the new results in this field were presented at the recent International Cosmic Ray Conference (ICRC). Here I summarise the 175 papers submitted on the topic of gamma-ray astronomy to the 30th ICRC in Merida, Mexico in July 2007.

  2. Gamma-ray sources

    International Nuclear Information System (INIS)

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

  3. Airborne gamma-ray spectrometer and magnetometer survey, Dryden, Texas; Indian Wells, Texas. Volume I. Detail area. Final report

    International Nuclear Information System (INIS)

    An airborne combined radiometric and magnetic survey was performed for the Department of Energy (DOE) over the Dryden Detail Area and the Indian Wells Detail Area of southwestern Texas. The Dryden Detail Area is within the coverage of the Sanderson, Dryden, Thurston, Pandale, Dryden Crossing, Malvado, and Langtry 15' map sheets of the National Topographic Map Series (NTMS). The Indian Wells Detail is within the coverage of the Indian Wells 15' map sheets of the NTMS. The survey was part of DOE's National Uranium Evaluation (NURE) program. Radiometric data were corrected for live time, aircraft and equipment background, cosmic background, atmospheric radon, Compton scatter, and altitude dependence. The corrected data were statistically evaluated, gridded, and contoured to produce maps of the radiometric variables, uranium, potassium, and thorium; their ratios; and the residual magnetic field. These maps have been analyzed in order to produce a multi-variant analysis contour map based on the radiometric response of the individual geological units. A geochemical analysis has been performed, using the radiometric and magnetic contour maps, the multi-variant analysis map, and factor analysis techniques, to produce a geochemical analysis map for the area

  4. Gamma ray optics

    Energy Technology Data Exchange (ETDEWEB)

    Jentschel, M.; Guenther, M. M.; Habs, D.; Thirolf, P. G. [Institut Laue-Langevin, F38042 Grenoble (France); Max-Planck-Institut fuer Quantenoptik, D-85748 Garching (Germany); Max-Planck-Institut fuer Quantenoptik, D-85748 Garching, Germany and Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany); Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany)

    2012-07-09

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

  5. Gamma-ray astronomy

    Science.gov (United States)

    Ramaty, R.; Lingenfelter, R. E.

    1982-01-01

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

  6. Gamma ray camera

    International Nuclear Information System (INIS)

    An improved Anger-type gamma ray camera utilizes a proximity-type image intensifier tube. It has a greater capability for distinguishing between incident and scattered radiation, and greater spatial resolution capabilities

  7. 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.

  8. Long Duration Gamma-Ray Emission From Thunderclouds

    OpenAIRE

    Kelley, Nicole

    2014-01-01

    Gamma-ray glows are long duration emission coming from thunderclouds. They are one example of high-energy atmospheric physics, a relatively new field studying high-energy phenomena from thunderstorms and lightning. Glows arise from sustained relativistic runaway electron avalanches (RREA). Gamma-ray instruments on the ground, balloons and airplanes have detected glows. The Airborne Detector for Energetic Lightning Emissions (ADELE) is an array of gamma-ray detectors, built at the University o...

  9. Gamma Ray Bursts

    Science.gov (United States)

    Gehrels, Neil; Meszaros, Peter

    2012-01-01

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

  10. Gamma-Ray Bursts

    Science.gov (United States)

    Gehrels, Neil; Mészáros, Péter

    2012-08-01

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

  11. Gamma Ray Bursts

    CERN Document Server

    Gehrels, Neil; 10.1126/science.1216793

    2012-01-01

    Gamma-ray bursts (GRBs) are bright flashes of gamma-rays coming from the cosmos. They occur roughly once per day, last typically 10s of seconds and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.

  12. Chemist's gamma-ray table

    International Nuclear Information System (INIS)

    An edited listing of gamma-ray information has been prepared. Prominent gamma rays originating from nuclides with half lives long enough to be seen in radiochemical experiments are included. Information is ordered by nuclide in one section and by energy in a second section. This shorter listing facilitates identification of nuclides responsible for gamma rays observed in experiments

  13. Gamma ray beam transmutation

    International Nuclear Information System (INIS)

    We have proposed a new approach to nuclear transmutation by a gamma ray beam of Compton scattered laser photon. We obtained 20 MeV gamma ray in this way to obtain transmutation rates with the giant resonance of 197Au and 129Iodine. The rate of the transmutation agreed with the theoretical calculation. Experiments on energy spectrum of positron, electron and neutron from targets were performed for the energy balance and design of the system scheme. The reaction rate was about 1.5∼4% for appropriate photon energies and neutron production rate was up to 4% in the measurements. We had stored laser photon more than 5000 times in a small cavity which implied for a significant improvement of system efficiency. Using these technologies, we have designed an actual transmutation system for 129Iodine which has a 16 million year's activity. In my presentation, I will address the properties of this scheme, experiments results and transmutation system for iodine transmutation

  14. Gamma ray camera

    International Nuclear Information System (INIS)

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

  15. Airborne gamma radiation soil moisture measurements over short flight lines

    Science.gov (United States)

    Peck, Eugene L.; Carrol, Thomas R.; Lipinski, Daniel M.

    1990-01-01

    Results are presented on airborne gamma radiation measurements of soil moisture condition, carried out along short flight lines as part of the First International Satellite Land Surface Climatology Project Field Experiment (FIFE). Data were collected over an area in Kansas during the summers of 1987 and 1989. The airborne surveys, together with ground measurements, provide the most comprehensive set of airborne and ground truth data available in the U.S. for calibrating and evaluating airborne gamma flight lines. Analysis showed that, using standard National Weather Service weights for the K, Tl, and Gc radiation windows, the airborne soil moisture estimates for the FIFE lines had a root mean square error of no greater than 3.0 percent soil moisture. The soil moisture estimates for sections having acquisition time of at least 15 sec were found to be reliable.

  16. Estimation of uranium from multichannel spectra in airborne gamma ray spectrometry using 1.12 MeV and 1.76 MeV photopeaks of 214Bi - an application to Cuddapah basin

    International Nuclear Information System (INIS)

    Present study examines the utility of gamma rays of energies 1.12 MeV and 1.76 MeV of uranium in estimation of uranium in airborne gamma ray spectrometric survey (AGRS) in comparison to the conventional 1.76 MeV alone used world wide. As a case study, the AGRS data of northern part of Cuddapah Basin is considered. Multi-channel processing is applied on this dataset to reduce the spectral noise and use of combined 1.12 MeV and 1.76 MeV has reduced the Poisson's related statistical error. Uranium is estimated using above two energies individually and in combination, using multi-channel processing followed by standard corrections procedure. Result indicates that a combination of both energies has given best estimation due to a reduction in overall noise which helped in demarcating geological entities and litho-contacts. This indicates the efficacy of this technique which improved the radio-geochemistry of study area in understanding the radio-elemental variation. (author)

  17. Cosmic gamma rays from quasars

    International Nuclear Information System (INIS)

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

  18. Cosmic gamma rays from quasars

    Science.gov (United States)

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

    1985-01-01

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

  19. Radar, geologic, airborne gamma ray and Landsat TM digital data integration for geological mapping of the Estrela granite complex (Para State)

    International Nuclear Information System (INIS)

    This work is focused on the geotectonic context of the Carajas Mineral Province, Amazon Craton, which represents the most important Brazilian Mineral Province and hosts iron, cooper, gold, manganese and nickel deposits. At the end of Archean age, during the techno-metamorphic evolution, moderated alkaline granitoids were generated, such as, Estrela Granite Complex (EGC). This work has used digital integration products with the purpose of study the granite suite, its host rock, and the surrounded area. The digital integrated data were gamma-ray and geological data with satellite images (SAR-SAREX e TM-Landsat). The geophysics data, originally in 32 bits and grid format, were interpolated and converted to 8 bits images. The geological data (facies map) was digitalized and converted to a raster format. The remote sensing images were geometrically corrected to guarantee an accuracy on the geological mapping. On the data processing phase, SAR images were digital integrated with gamma-ray data, TM-Landsat image and the raster facies map. The IHS transformation was used as the technique to integrate the multi-source data. On the photogeological interpretation, SAR data were extremely important to permit the extraction of the main tectonic lineaments which occur on the following directions: +/- N45W, +/- N70W, +/- NS, +/- N20E, +/- N45E e +/- N75E. This procedure was done both in analogic and automatic form, being the automatic process more useful to complement information in the extracting process. Among the digital products generated, SAR/GAMA products (uranium, thorium and total count) were the ones that give the most important contribution. The interpretation of the SAR/GAMA's products added to the field campaign have allowed to map the limits of units that occur in the region and four facies of the Estrela Granite Complex were detected. The origin of the granite suite might be related to a magmatic differentiation or to distinct intrusion pulses. The use of the

  20. Gamma ray detector optimization for mobile detectors

    International Nuclear Information System (INIS)

    The Energy Research and Development Administration supports a program enabling a rapid response to situations requiring a mobile, detection-at-a-distance capability for locating lost or stolen nuclear materials. For this application, man-portable, vehicular-borne, and airborne detection systems are used. For gamma ray detection, NaI detectors are usually used. Because weight is a serious constraint, many systems employ unshielded detectors. Results of optimization studies to determine a suitable thickness for 12.7 cm diameter NaI detectors that are commonly used in these applications are presented

  1. Planetary gamma-ray spectroscopy

    International Nuclear Information System (INIS)

    The chemical composition of a planet can be inferred from the gamma rays escaping from its surface and can be used to study its origin and evolution. The measured intensities of certain gamma rays of specific energies can be used to determine the abundances of a number of elements. The major sources of these gamma-ray lines are the decay of natural radionuclides, reactions induced by energetic galactic-cosmic-ray particles, capture of low energy neutrons, and solar-proton-induced radioactivities. The fluxes of the more intense gamma-ray lines emitted from 30 elements were calculated using current nuclear data and existing models. The source strengths for neutron-capture reactions were modified from those previously used. The fluxes emitted from a surface of average lunar composition are reported for 288 gamma-ray lines. These theoretical fluxes have been used elsewhere to convert the data from the Apollo gamma-ray spectrometers to elemental abundances and can be used with results from future missions to map the concentrations of a number of elements over a planet's surface. Detection sensitivities for these elements are examined and applications of gamma-ray spectroscopy for future orbiters to Mars and other solar-system objects are discussed

  2. Planetary gamma-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Reedy, R.C.

    1978-01-01

    The chemical composition of a planet can be inferred from the gamma rays escaping from its surface and can be used to study its origin and evolution. The measured intensities of certain gamma rays of specific energies can be used to determine the abundances of a number of elements. The major sources of these gamma-ray lines are the decay of natural radionuclides, reactions induced by energetic galactic-cosmic-ray particles, capture of low energy neutrons, and solar-proton-induced radioactivities. The fluxes of the more intense gamma-ray lines emitted from 30 elements were calculated using current nuclear data and existing models. The source strengths for neutron-capture reactions were modified from those previously used. The fluxes emitted from a surface of average lunar composition are reported for 288 gamma-ray lines. These theoretical fluxes have been used elsewhere to convert the data from the Apollo gamma-ray spectrometers to elemental abundances and can be used with results from future missions to map the concentrations of a number of elements over a planet's surface. Detection sensitivities for these elements are examined and applications of gamma-ray spectroscopy for future orbiters to Mars and other solar-system objects are discussed.

  3. Airborne gamma-ray spectrometer and magnetometer survey: Las Vegas Quadrangle (Arizona, California, Nevada), Williams Quadrangle (Arizona), Prescott Quadrangle (Arizona), and Kingman Quadrangle (Arizona, California, Nevada). Final report. Volume I

    International Nuclear Information System (INIS)

    A total of 23,091 line miles of gamma-ray spectrometer and magnetometer data were acquired over 20 x 10 NTMS Quadrangle areas of Kingman (Arizona, California, Nevada), Las Vegas (Arizona, California, Nevada), Prescott (Arizona), and Williams (Arizona). Radiometric count rates in general are statistically adequate, with <2.0% of the potassium and thorium count being inadequate and <3% of the uranium count rates, when the data obtained over water and those obtained over the Grand Canyon are excluded. Particularly in the Prescott map area, but also in the Williams, Kingman, and Las Vegas areas, some very high thorium count rates were observed, indicating large areas that may contain up to 100 ppM e thorium or more in outcrop. Some of these regions in the Prescott and Williams Quadrangles may eventually be of economic interest if the breeder reactor becomes a reality. The high thorium content may also be an indication of other lithophile elements in possibly economic concentrations. The possibility exists further that one of the zones of high thorium response may be used for calibration of shine through/shine around in airborne systems due to terrestrial thorium. Areas of apparent anomalous concentrations of thorium and of uranium have been outlined on the interpretation maps and are discussed. The thorium anomalies appear to be related mainly to the Precambrian gneisses and granites. The uranium anomalies are mainly found in the Quaternary/Tertiary volcanics series, the Tertiary rhyolites, the Quaternary alluvial deposits and Quaternary/Tertiary lake bed deposits. In the Las Vegas quadrangle the Tertiary Horse Spring formation is also considered a favorable environment for uranium. In some areas, where the Cambrian Tonto group was not divided on the geological map into the Tapeats sandstone, Pioche/Carrara shales and Muav formation, a subdivision was attempted based on geochemical analysis of the gamma-ray spectrometer data

  4. Gamma-ray Pulsar Revolution

    OpenAIRE

    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 t...

  5. An Airborne and Vehicular Gamma Survey of Greenham Common, Newbury District and Surrounding Areas

    OpenAIRE

    Sanderson, D.C.W; Allyson, J.D.; Cresswell, A.; McConville, P.

    1997-01-01

    The airborne gamma ray survey recorded more than 40,000 scintillation spectra and 20,000 spectra from semiconductor detectors. The vehicular survey produced a further 1346 and 763 spectral sets respectively. The installation, calibration, recording and analysis followed SURRC procedures which have been developed and validated over many years and are fully documented. Pre flight checks on detector performance for energy calibration, energy resolution and sensitivity were performed on a dail...

  6. Gamma rays at airplane altitudes

    International Nuclear Information System (INIS)

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

  7. Cosmic-Rays and Gamma Ray Bursts

    Science.gov (United States)

    Meli, A.

    2013-07-01

    Cosmic-rays are subatomic particles of energies ranging between a few eV to hundreds of TeV. These particles register a power-law spectrum, and it seems that most of them originate from astrophysical galactic and extragalactic sources. The shock acceleration in superalfvenic astrophysical plasmas, is believed to be the main mechanism responsible for the production of the non-thermal cosmic-rays. Especially, the importance of the very high energy cosmic-ray acceleration, with its consequent gamma-ray radiation and neutrino production in the shocks of the relativistic jets of Gamma Ray Bursts, is a favourable theme of study. I will discuss the cosmic-ray shock acceleration mechanism particularly focusing on simulation studies of cosmic-ray acceleration occurring in the relativistic shocks of GRB jets.

  8. Magnetic angle for gamma rays

    International Nuclear Information System (INIS)

    In December 2002 astronomers at the University of California in Berkeley got a lucky break. A bright gamma-ray burst appeared in the sky within 18 degrees of the Sun, which was close enough to be picked up by the RHESSI solar satellite. Analysing data from the satellite, Wayne Coburn and Steven Boggs made the stunning discovery that the gamma rays from the burst - named GRB021206 - were linearly polarized. And not just by any amount, but by 80% - the maximum polarization theoretically possible. The discovery represents a major breakthrough in gamma-ray astronomy (Nature 423 415).Gamma-ray bursts are the most energetic events in the universe, typically corresponding to the conversion of 1% of the mass of the Sun into energy. Every day an average of about one of these brief flashes of gamma rays - which come from any direction in the sky and last a few tens of seconds - are detected. Observations of the optical afterglow of the bursts reveal that they originate in galaxies that are several billions of light-years away. But what causes the bursts, and how the gamma rays are actually produced, have, until recently, remained a mystery. It has been suggested that gamma-ray bursts result from supernovae - the explosions of massive stars that have used up all their fuel - and that the bursts might be the 'birth cries' of black holes. Some of this evidence is circumstantial. It is known, for example, that the host galaxies of the bursts are regions where massive stars are copiously forming. However, observations of the afterglow of GRB980425 in 1998 revealed a spectral signature that would be expected for a supernova. This provided the first compelling, but inconclusive, direct evidence for the link between gamma-ray bursts and supernovae. In March this year, however, this link was dramatically confirmed. The HETE-2 satellite detected a spectacular gamma-ray burst that was among the closest and brightest ever observed. GRB030329 was just two billion light-years away, which

  9. Guidelines for radioelement mapping using gamma ray spectrometry data

    International Nuclear Information System (INIS)

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

  10. Gamma rays in thunderstorms

    International Nuclear Information System (INIS)

    Not only lightning occur in thunderstorms but also luminous flashes that are emitted upwards over the clouds. These flashes have been studied for 20 years. Satellites have detected gamma flashes with an energy of 30 MeV. It was thought that these flashes resulted from collisions between cosmic particles and cloud molecules but recent results from the Italian Agile satellite question this explanation. Gamma flashes with an energy of 100 MeV have been detected which is too high an energy to be explained by collisions with cosmic particles. Another result show the existence of very strong acceleration of electrons in areas where some type of flashes are likely to happen. (A.C.)

  11. 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.

  12. Neutrinos from Gamma Ray Bursts

    CERN Document Server

    Mannheim, K

    2000-01-01

    The observed fluxes of cosmic rays and gamma rays are used to infer the maximum allowed high-energy neutrino flux allowed for Gamma Ray Bursts (GRBs), following Mannheim, Protheroe, and Rachen (2000). It is shown that if GRBs produce the ultrahigh-energy cosmic rays, they should contribute (a) at least 10% of the extragalactic gamma ray background between 3 MeV and 30 GeV, contrary to their observed energy flux which is only a minute fraction of this flux, and (b) a cumulative neutrino flux a factor of 20 below the AMANDA (Neutrino 2000) limit on isotropic neutrinos. This could have two implications, either GRBs do not produce the ultrahigh energy cosmic rays or that the GRBs are strongly beamed and emit most of their power at energies well above 100 GeV implausibly increasing the energy requirements, but consistent with the marginal detections of a few low-redshift GRBs by MILAGRITO, HEGRA-AIROBICC, and the Tibet-Array. All crucial measurements to test the models will be available in the next few years. Thes...

  13. Hypernuclear gamma rays

    International Nuclear Information System (INIS)

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

  14. The GRAD gamma ray spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Rester, A.C.; Piercey, R.B.; Eichhorn, G.; Coldwell, R.L.; McKisson, J.M.; Ely, D.W.; Mann, H.M.; Jenkins, D.A.

    1986-02-01

    A gamma-ray spectrometer for an upcoming space shuttle mission is described. Consisting of a 150 cm/sup 3/ n-type germanium detector set inside active shielding of bismuth germanate and plastic scintillator, the instrument will be used in studies of the Orbiter background and the galactic center.

  15. The GRAD gamma ray spectrometer

    International Nuclear Information System (INIS)

    A gamma-ray spectrometer for an upcoming space shuttle mission is described. Consisting of a 150 cm3 n-type germanium detector set inside active shielding of bismuth germanate and plastic scintillator, the instrument will be used in studies of the Orbiter background and the galactic center

  16. 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.

  17. Gamma ray slush hydrogen monitor

    Science.gov (United States)

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

    1992-01-01

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

  18. Periodicities in gamma ray bursts

    International Nuclear Information System (INIS)

    Gamma ray burst models based on magnetic neutron stars face a problem of account for the scarcity of observed periods. Both this scarcity and the typical period found when any is detected are explained if the neutron stars are accreting in binary systems

  19. 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.

  20. The Gamma-ray Sky with Fermi

    CERN Document Server

    Thompson, D J

    2013-01-01

    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, 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.

  1. 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...... 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)....

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

    OpenAIRE

    Frontera, Filippo

    2004-01-01

    The discovery by the BeppoSAX satellite of X-ray afterglow emission from the gamma-ray burst which occurred on 28 February 1997 produced a revolution in our knowledge of the gamma-ray burst phenomenon. Along with the discovery of X-ray afterglows, the optical afterglows of gamma-ray bursts were discovered and the distance issue was settled, at least for long $\\gamma$-ray bursts. The 30 year mystery of the gamma-ray burst phenomenon is now on the way to solution. Here I rewiew the observationa...

  3. Cascaded Gamma Rays as a Probe of Cosmic Rays

    Science.gov (United States)

    Murase, Kohta

    2014-06-01

    Very-high-energy (VHE) and ultra-high-energy (UHE) gamma rays from extragalactic sources experience electromagnetic cascades during their propagation in intergalactic space. Recent gamma-ray data on TeV blazars and the diffuse gamma-ray background may have hints of the cascade emission, which are especially interesting if it comes from UHE cosmic rays. I show that cosmic-ray-induced cascades can be discriminated from gamma-ray-induced cascades with detailed gamma-ray spectra. I also discuss roles of structured magnetic fields, which suppress inverse-Compton pair halos/echoes but lead to guaranteed signals - synchrotron pair halos/echoes.

  4. Compton suppression gamma ray spectrometry

    International Nuclear Information System (INIS)

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

  5. 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.

  6. Sterilization of pharmaceuticals by gamma ray

    International Nuclear Information System (INIS)

    This paper shows the possibility of sterilization of certain pharmaceuticals and materials involved by gamma radiation from cobalt-60 and cesium-137 sources, and illustrates the importance of gamma ray sterilization compared with other sterilization methods. The paper also reviews some pharmaceuticals and materials involved, which proved the possibility of gamma ray sterilization. (author)

  7. Design, calibration, and application of an airborne gamma spectrometer system in Switzerland

    International Nuclear Information System (INIS)

    Airborne radiometric surveys are finding increasingly wider application in environmental mapping and monitoring. They are the most efficient tool to delimit surface contamination and to locate lost radioactive sources. To secure radiometric capability in survey and emergency situations, a new sensitive airborne system has been built that includes an airborne spectrometer with 256 channels and a sodium iodide detector with a total volume of 16.8 liters. A rack-mounted PC with memory cards is used for data acquisition, with a GPS satellite navigation system for positioning. The system was calibrated with point sources using a mathematical correction to take into account the effects of gamma-ray scattering in the ground and in the atmosphere. The calibration was complemented by high precision ground gamma spectrometry and laboratory measurements on rock samples. In Switzerland, two major research programs make use of the capabilities of airborne radiometric measurements. The first one concerns nuclear power-plant monitoring. The five Swiss nuclear installations (four power plants and one research facility) and the surrounding regions of each site are surveyed annually. The project goal is to monitor the dose-rate distribution and to provide a documented baseline database. The measurements show that all sites (with the exception of the Goesgen power plant) can be identified clearly on the maps. No artificial radioactivity that could not be explained by the Chernobyl release or earlier nuclear weapons tests was detected outside of the fenced sites of the nuclear installations. The second program aims at a better evaluation of the natural radiation level in Switzerland. The survey focused on the crystalline rocks of the Central Massifs of the Swiss Alps because of their relatively high natural radioactivity and lithological variability

  8. 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.

  9. Recommended standards for gamma ray intensities

    Energy Technology Data Exchange (ETDEWEB)

    Bé, Marie-Martine, E-mail: mmbe@cea.fr [LNHB, CEA LIST Saclay, 91191 Gif-sur-Yvette Cedex (France); Chechev, Valery P. [KRI, V.G. Khlopin Radium Institute, St. Petersburg 194021 (Russian Federation)

    2013-11-11

    Gamma ray data are used in more and more areas of application, and so over the years the demand for recommended gamma ray energies and intensities has increased. This paper proposes a list of gamma rays whose intensity is sufficiently well-known and they can be used for the calibration of gamma ray spectrometers and other applications; it is based on studies carried out by an international group of evaluators: the Decay Data Evaluation Project. One goal of this paper is to gather this set of data together in order to facilitate and generalize their use. In the first part, a brief description of the methodology followed throughout the evaluations is given, different methods of gamma ray intensity evaluation are presented, some typical examples of evaluations are shown; in the second part, the list of chosen nuclides is given along with their applications, and finally a list of recommended gamma ray intensities is presented.

  10. Gamma-ray burst polarimeter (GAP)

    International Nuclear Information System (INIS)

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

  11. Mining Gamma-Ray Burst Data

    OpenAIRE

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

    2000-01-01

    Gamma-ray bursts provide what is probably one of the messiest of all astrophysical data sets. Burst class properties are indistinct, as overlapping characteristics of individual bursts are convolved with effects of instrumental and sampling biases. Despite these complexities, data mining techniques have allowed new insights to be made about gamma-ray burst data. We demonstrate how data mining techniques have simultaneously allowed us to learn about gamma-ray burst detectors and data collectio...

  12. Prompt and Delayed Gamma-Rays from Fission

    International Nuclear Information System (INIS)

    The following data about gamma-rays from fission are reported and discussed; Total prompt gamma-ray spectrum, and average number and energy of gamma-rays; X-rays in prompt fission, and excitation of X-rays in matter; gamma-ray spectra as a function of the mass ratio in fission, gamma-lines in those spectra, and Doppler effect-, anisotropy in gamma-emission relative to the direction of fragments; average gamma-energy and gamma-spectra as a function of mass of the fission products; delayed gamma-rays; delayed gamma-rays as a function of fission product mass. (author)

  13. Experimental Measurements and Computer Simulation of Fission Product Gamma-Ray Spectra

    OpenAIRE

    Sanderson, D.C.W; Cresswell, A.; Allyson, J.D.; McConville, P.

    1997-01-01

    Airborne gamma ray spectrometry using high volume scintillation detectors, optionally in conjunction with Ge detectors, has potential for making rapid environmental measurements in response to nuclear accidents. An experimental investigation and computer simulation have been used to characterise the response of such detectors to short lived fission products. Small samples of 235U were irradiated in a research reactor for short periods, to generate fission product sources. Gamma ray spectra w...

  14. Review of Past Nuclear Accidents: Source Terms and Recorded Gamma-Ray Spectra

    OpenAIRE

    Sanderson, D.C.W.; Cresswell, A.; Allyson, J.D.; McConville, P.

    1997-01-01

    Airborne gamma ray spectrometry using high volume scintillation detectors, optionally in conjunction with Ge detectors, has potential for making rapid environmental measurements in response to nuclear accidents. A literature search on past nuclear accidents has been conducted to define the source terms which have been experienced so far. Selected gamma ray spectra recorded after past accidents have also been collated to examine the complexity of observed behaviour.

  15. 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

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

    OpenAIRE

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

    2012-01-01

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

  17. Gamma-ray emission from thunderstorm discharges

    International Nuclear Information System (INIS)

    Fine features of gamma-ray radiation registered during a thunderstorm at Tien-Shan Mountain Cosmic Ray Station are presented. Long duration (100-600 ms) gamma-ray bursts are found. They are for the first time identified with atmospheric discharges (lighting). Gamma-ray emission lasts all the time of the discharge and is extremely non-uniform consisting of numerous flashes. Its peak intensity in the flashes exceeds the gamma-ray background up to two orders of magnitude. Exclusively strong altitude dependence of gamma radiation is found. The observation of gamma radiation at the height 4-8 km could serve as a new important method of atmospheric discharge processes investigation. - Highlights: → Gamma-radiation bursts always accompany the electric discharges in atmosphere. → The gamma burst fill up the time of an atmospheric discharge completely. → The higher is the discharge electric field change - the higher is gamma intensity. → The temporal distribution of gamma intensity during the burst is non-uniform. → The altitude dependence of the burst gamma intensity is dramatic.

  18. Gamma-ray emission from thunderstorm discharges

    Energy Technology Data Exchange (ETDEWEB)

    Gurevich, A.V., E-mail: alex@lpi.r [P. N. Lebedev Physical Institute, Moscow (Russian Federation); Chubenko, A.P. [P. N. Lebedev Physical Institute, Moscow (Russian Federation); Karashtin, A.N. [Radiophysical Research Institute, Nizhny Novgorod (Russian Federation); Mitko, G.G.; Naumov, A.S.; Ptitsyn, M.O.; Ryabov, V.A.; Shepetov, A.L. [P. N. Lebedev Physical Institute, Moscow (Russian Federation); Shlyugaev, Yu.V. [Radiophysical Research Institute, Nizhny Novgorod (Russian Federation); Vildanova, L.I. [Tien-Shan Mountain Cosmic Ray Station, Almaty (Kazakhstan); Zybin, K.P. [P. N. Lebedev Physical Institute, Moscow (Russian Federation)

    2011-04-11

    Fine features of gamma-ray radiation registered during a thunderstorm at Tien-Shan Mountain Cosmic Ray Station are presented. Long duration (100-600 ms) gamma-ray bursts are found. They are for the first time identified with atmospheric discharges (lighting). Gamma-ray emission lasts all the time of the discharge and is extremely non-uniform consisting of numerous flashes. Its peak intensity in the flashes exceeds the gamma-ray background up to two orders of magnitude. Exclusively strong altitude dependence of gamma radiation is found. The observation of gamma radiation at the height 4-8 km could serve as a new important method of atmospheric discharge processes investigation. - Highlights: Gamma-radiation bursts always accompany the electric discharges in atmosphere. The gamma burst fill up the time of an atmospheric discharge completely. The higher is the discharge electric field change - the higher is gamma intensity. The temporal distribution of gamma intensity during the burst is non-uniform. The altitude dependence of the burst gamma intensity is dramatic.

  19. Modulated gamma ray beam absorptiometer

    International Nuclear Information System (INIS)

    The purpose of this paper is to describe the study and operating of a heavy elements content measuring instrument. This apparatus (French patent n0 2184533, December 16, 1974) uses the absorption of a modulated gamma ray beam to measure the concentration of 5 to 500 g per litre uranium of plutonium solutions with an over 1% accuracy. The activity of the fission products present in the solution may rise to 60 Ci/l. An automatic device suppresses all daily checkings and adjustements. The tension obtained is proportional to the content of the heavy element being measured. The influence of the nitric acid content is twenty times as weak as in the case of a conventional densimeter. This apparatus is particularly adapted to fuel reprocessing plants

  20. A 16N gamma-ray facility

    Science.gov (United States)

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

    1997-02-01

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

  1. A 16N gamma-ray facility

    International Nuclear Information System (INIS)

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

  2. Intercomparison of gamma ray analysis software packages

    International Nuclear Information System (INIS)

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

  3. 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.

  4. 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.

  5. Unveiling the Secrets of Gamma Ray Bursts

    CERN Document Server

    Gomboc, A

    2012-01-01

    Gamma Ray Bursts (GRBs) are unpredictable and brief flashes of gamma rays that occur about once a day in random locations in the sky. Since gamma rays do not penetrate the Earth's atmosphere, they are detected by satellites, which automatically trigger ground-based telescopes for follow-up observations at longer wavelengths. In this introduction to Gamma Ray Bursts we review how building a multi-wavelength picture of these events has revealed that they are the most energetic explosions since the Big Bang and are connected with stellar deaths in other galaxies. However, in spite of exceptional observational and theoretical progress in the last 15 years, recent observations raise many questions which challenge our understanding of these elusive phenomena. Gamma Ray Bursts therefore remain one of the hottest topics in modern astrophysics.

  6. Gamma-ray detected radio galaxies

    Science.gov (United States)

    Beckmann, Volker; Soldi, Simona; De Jong, Sandra; Kretschmer, Karsten; Savchenko, Volodymyr

    2016-07-01

    So far 15 radio galaxies have been detected in the gamma-ray domain by CGRO/EGRET and Fermi/LAT, with a few detections also in the VHE range. We search for distinguishing parameters and estimate the total number of gamma-ray emitting radio galaxies that are potentially detectable by Fermi/LAT. We use Fermi/LAT data in comparison with X-ray and hard X-ray data in order to constrain basic parameters such as the total power of the inverse Compton branch and the position of its peak. We search for possible correlations between the radio, UV, X-ray, and gamma-ray domain and derive the number counts distribution. We then compare their properties with those of the radio galaxies in the 3CRR and SMS4 catalogues. The data show no correlation between the peak of the inverse Compton emission and its luminosity. For the gamma-ray detected radio galaxies the luminosities in the various bands are correlated, except for the UV band, but there is no indication of a correlation of peak frequency or luminosity with the spectral slopes in the X-ray or gamma-ray band. The comparison with other bright radio galaxies shows that the gamma-ray detected objects are among those that have the largest X-ray but rather moderate radio fluxes. Their UV and X-ray luminosities are similar, but gamma-ray detected radio galaxies are predominantly of type FR-I, while the 3CRR sample contains mainly FR-II objects. The number counts of the so far gamma-ray detected radio galaxies shows a very shallow slope, indicating that potentially a fraction of radio galaxies has been missed so far or has not been identified as such, although the predicted number of 22 ± 7 is consistent with the observed 15 objects.

  7. Gamma-ray Astronomy and GLAST

    Science.gov (United States)

    McEnery, Julie

    2007-01-01

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

  8. 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...

  9. Gamma-Ray Bursts: The End Game

    Science.gov (United States)

    Lamb, Don

    1997-11-01

    The nature of gamma-ray bursts has been one of the greatest unsolved mysteries in astrophysics for more than a quarter century. A major reason for this is that no definite counterparts to the bursts could be found at other wavelengths, despite intense efforts spanning more than two decades. Consequently, the study of gamma-ray bursts has been isolated from the rest of astronomy. Scientists studying them have had only the laws of physics and the bursts themselves to guide them in attempting to solve the burst mystery. All of this changed dramatically with the discovery earlier this year of fading X-ray and optical sources in the arcminute-sized positional error boxes of several gamma-ray bursts. For the first time, temporal, as well as spatial, coincidence could be used to associate these X-ray and optical sources with the gamma-ray bursts. As a result, the odds are great that the fading X-ray and optical sources are counterparts of the bursts, and that the study of gamma-ray bursts has finally been connected with the rest of astronomy. In this talk, we describe the dramatic new information about the nature of gamma-ray bursts that the X-ray, optical, and radio observations of the fading sources have provided, and emphasize the implications that this information has for the distance scale to the bursts.

  10. Software tool for xenon gamma-ray spectrometer control

    Science.gov (United States)

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

    2016-02-01

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

  11. High Energy Radiation from $\\gamma$ Ray Bursts

    CERN Document Server

    Dermer, C D; Dermer, Charles D.; Chiang, James

    1999-01-01

    Gamma-ray burst (GRB) engines are probed most intimately during the prompt gamma-ray luminous phase when the expanding blast wave is closest to the explosion center. Using GRBs 990123 and 940217 as guides, we briefly review observations of high-energy emission from GRBs and summarize some problems in GRB physics. \\gamma\\gamma transparency arguments imply relativistic beaming. The parameters that go into the external shock model are stated, and we show numerical simulation results of gamma-ray light curves from relativistic blast waves with different amounts of baryon loading. A distinct component due to the synchrotron self-Compton process produces significant emission at GeV and TeV energies. Predictions for spectral and temporal evolution at these energies are presented for a blast wave expanding into uniform surroundings. Observations of the slow decay of GeV-TeV radiation provide evidence for ultra-high energy cosmic ray acceleration in GRBs.

  12. The Polarization Dependence of Gamma-Gamma Absorption - Implications for Gamma-Ray Bursts and Blazars

    CERN Document Server

    Boettcher, Markus

    2014-01-01

    This paper presents an analysis of the dependence of the opacity for high-energy gamma-rays to gamma-gamma absorption by low-energy photons, on the polarization of the gamma-ray and target photons. This process has so far only been considered using the polarization-averaged gamma-gamma absorption cross section. It is demonstrated that in the case of polarized gamma-ray emission, subject to source-intrinsic gamma-gamma absorption by polarized target photons, this may lead to a slight over-estimation of the gamma-gamma opacity by up to ~ 10 % in the case of a perfectly ordered magnetic field. Thus, for realistic astrophysical scenarios with partially ordered magnetic fields, the use of the polarization-averaged gamma-gamma cross section is justified for practical purposes, such as estimates of minimum Doppler factors inferred for gamma-ray bursts and blazars, based on gamma-gamma transparency arguments, and this paper quantifies the small error incurred by the unpolarized-radiation approximation. Furthermore, i...

  13. Gamma-Ray Burst Physics with GLAST

    Energy Technology Data Exchange (ETDEWEB)

    Omodei, N.; /INFN, Pisa

    2006-10-06

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

  14. Gamma-ray emission from globular clusters

    CERN Document Server

    Tam, P H Thomas; Hui, C Y

    2012-01-01

    Over the last few years, the fruitful data provided by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope has revolutionized our understanding of high-energy processes in globular clusters, particularly those involving compact objects like millisecond pulsars (MSPs). Gamma-ray emission between 100 MeV to 10 GeV has been detected from more than a dozen globular clusters in our Galaxy, most notably 47 Tucanae and Terzan 5. Based on a sample of known gamma-ray globular clusters, empirical relations between the gamma-ray luminosity and properties of globular clusters such as stellar encounter rate, metallicity, as well as optical and infrared photon energy density in the cluster, have been derived. The gamma-ray spectra are generally described by a power law with a cut-off at a few GeV. Together with the detection of pulsed gamma-rays from a millisecond pulsar in a globular cluster, such spectral signature gives support that gamma-rays from globular clusters are collective curvature emission from...

  15. Gamma-ray Albedo of the Moon

    Energy Technology Data Exchange (ETDEWEB)

    Moskalenko, Igor V.; Porter, Troy A.

    2007-06-14

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

  16. 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.

  17. Librarian driven analysis of gamma ray spectra

    International Nuclear Information System (INIS)

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

  18. Gamma rays from extragalactic astrophysical sources

    CERN Document Server

    Bosch-Ramon, V

    2011-01-01

    Presently there are several classes of detected gamma-ray extragalatic sources. They are mostly associated to active galactic nuclei (AGN) and (at soft gamma rays) to gamma-ray bursts (GRB), but not only. Active galactic nuclei consist of accreting supermassive black holes hosted by a galaxy that present in some cases powerful relativistic jet activity. These sources, which have been studied in gamma rays for several decades, are probably the most energetic astrophysical objects, and their appearance depends much on whether their jets point to us. Gamma-ray bursts, thought to be associated to collapsing or merging stellar-mass objects at cosmological distances, are also accreting highly relativistic jet sources that shine strongly at high energies. These are very short-duration events, but they are also the most luminous. Recently, star formation galaxies have turned out to be also gamma-ray emitters. On the other hand, clusters of galaxies have not been detected beyond X-rays yet. These are the largest known...

  19. Gamma Ray Astronomy with Magnetized Zevatrons

    CERN Document Server

    Armengaud, E; Miniati, F; Armengaud, Eric; Sigl, Guenter; Miniati, Francesco

    2005-01-01

    Nearby sources of cosmic rays up to a ZeV(=10^21 eV) could be observed with a multi-messenger approach including secondary gamma-rays and neutrinos. If cosmic rays above ~10^18 eV are produced in magnetized environments such as galaxy clusters, the flux of secondary gamma-rays below ~1 TeV can be enhanced up to several orders of magnitudes compared to unmagnetized sources. A particular source of enhancement are synchrotron and cascade photons from e^+e^- pairs produced by protons from sources with relatively steep injection spectra proportional to E^-2.6. Such sources should be visible at the same time in ultra-high energy cosmic ray experiments and gamma-ray telescopes.

  20. INTEGRAL & RXTE View of Gamma-ray Binaries

    OpenAIRE

    Jian LI; Torres, Diego F.; Zhang, Shu; WANG, JIANMIN

    2013-01-01

    Gamma-ray binaries are X-ray binaries with gamma-ray emissions. Their multi-wavelength emissions range from radio, optical, X-ray and to very high energy (TeV). X-ray emissions are crucial to understand the nature of gamma-ray binaries. INTEGRAL and RXTE have covered and monitored most of the gamma-ray binaries in hard and soft X-rays. Here we report the results of several gamma-ray binaries and possible gamma-ray binaries from INTEGRAL and RXTE.

  1. 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...

  2. Gamma rays from clusters of galaxies

    CERN Document Server

    Blasi, P; Brunetti, G; Blasi, Pasquale; Gabici, Stefano; Brunetti, Gianfranco

    2007-01-01

    Clusters of galaxies and the large scale filaments that connect neighboring clusters are expected to be sites of acceleration of charged particles and sources of non-thermal radiation from radio frequencies to gamma rays. Gamma rays are particularly interesting targets of investigation, since they may provide precious information on the nature and efficiency of the processes of acceleration and magnetic confinement of hadrons within clusters of galaxies. Here we review the status of viable scenarios that lead to the production of gamma rays from large scale structures and are compatible with the multifrequency observations that are already available. We also discuss the possibility of detection of gamma rays with space-borne telescopes such as GLAST and ground based Cherenkov telescopes, and the physical information that may be gathered from such observations.

  3. Precision measurements of gamma-ray intensities

    International Nuclear Information System (INIS)

    To determine relative intensities of gamma rays in the region of 280 to 2750 keV, Ge(Li) detectors were calibrated with standard sources and cascade gamma-ray sources. Decay rates of the standard sources were determined by means of the 4πβ-γ or 4πX-γ coincidence method. Experimental conditions were improved and spectra were carefully analyzed. Relative gamma-ray intensities of 56Co, 88Y, sup(110m)Ag, 133Ba, 134Cs, 152Eu, 154Eu, 192Ir and 207Bi were determined within the accuracy of about 0.5% for strong gamma rays. Intensities per decays were obtained from the relative intensities for most of the nuclides. (author)

  4. Gamma ray auto absorption correction evaluation methodology

    International Nuclear Information System (INIS)

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

  5. Supernovae and gamma-ray bursts connection

    Energy Technology Data Exchange (ETDEWEB)

    Valle, Massimo Della [INAF-Napoli, Capodimonte Observatory, Salita Moiariello, 16, I-80131 Napoli (Italy); International Center for Relativistic Astrophysics Network, Piazzale della Repubblica 10, I-65122, Pescara (Italy)

    2015-12-17

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

  6. Supernovae and gamma-ray bursts connection

    Science.gov (United States)

    Valle, Massimo Della

    2015-12-01

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

  7. Gamma Ray Astronomy with Magnetized Zevatrons

    OpenAIRE

    Armengaud, Eric; Sigl, Guenter; Miniati, Francesco

    2005-01-01

    Nearby sources of cosmic rays up to a ZeV(=10^21 eV) could be observed with a multi-messenger approach including secondary gamma-rays and neutrinos. If cosmic rays above ~10^18 eV are produced in magnetized environments such as galaxy clusters, the flux of secondary gamma-rays below ~1 TeV can be enhanced up to several orders of magnitudes compared to unmagnetized sources. A particular source of enhancement are synchrotron and cascade photons from e^+e^- pairs produced by protons from sources...

  8. Airborne gamma spectrometry - towards integration of European operational capability

    International Nuclear Information System (INIS)

    Full text: A nuclear threat can take several forms. The fallout from nuclear weapons or from an accident in a nuclear power reactor may contaminate a large area (>>100,000 km2) whereas the dispersion of single sources, either accidentally or deliberately (dirty bomb), contaminates a much smaller area, perhaps only a few thousand square kilometres or less. Airborne gamma spectrometry (AGS) plays an important role in providing detailed information an the dispersion of radioactive materials. AGS using a fixed-wing or a rotary-wing aircraft is at its best in fallout mapping and in searching for orphan sources. Plume tracking could be a third application but is very complex, and there is a risk of vehicle contamination, which would deteriorate mission capability in the later phases of an accident. Because of obvious advantages, unmanned aerial vehicles could be used to monitor the release rate at the site of an accident and perhaps the plume itself. The aim of the present paper is to discuss ways to utilize existing European airborne monitoring capabilities for multilateral assistance in an accident and to give some thoughts to how an integrated system could be developed to take into account various national measuring strategies. In a large-scale accident, it is to be expected that the European countries use their radiological resources to map their own territory. It is realistic to think of assistance by transferring equipment and staff to another country only in accident scenarios where a country or countries with essential AGS capability would not have been affected by the fallout. Various AGS survey results can be fused only if a common platform for data exchange is available. Formats and protocols have been developed for special cases (ECCOMAGS, Nuclear Fission Safety, 4th and 5th Framework Programmes) but there are no universal solutions applicable to different situations and Instruments. The hardware and software among the European AGS teams are tailor

  9. Cosmic gamma-ray studies at Srinagar

    International Nuclear Information System (INIS)

    Cosmic gamma ray studies being carried out at the Nuclear Research Laboratory at Srinagar and Gulmarg are described and some of the results of observation and possible conclusions are mentioned. These studies use ground base techniques which can detect short-time scale gamma ray bursts from supernovae and primordial black hole (PBH) and also high energy gamma rays from various point sources. A large area photomultiplier system is employed to detect pulses of visible fluorescence radiation which is caused by a gamma ray burst of supernovae of PBH origin. However, any signal out a large number of signals recorded at Gulmarg could not be identified as coinciding with any such event observed elsewhere. It shows that the size of the burst source cannot exceed 30 km., which is in agreement with neutron-star source models. An array using plastic scintillator detectors at the corner of a 10 metre square has been set up at Gulmarg to detect air-shower due to high energy gamma rays. Cerenkov light pulses recorded at Gulmarg have been projected on the sidereal map. A significant excess observed in the right ascension range 20 +- 3 h suggests the possible presence of a quasic-periodic source of gamma rays of energy greater than 1014 eV in the general direction of Cygnus X-3. Future programme of studies is mentioned. (K.M.)

  10. Gamma-ray pulsar studies with COMPTEL

    Science.gov (United States)

    Hermsen, W.; Kuiper, L.; Diehl, R.; Lichti, G.; Schoenfelder, V.; Strong, A. W.; Connors, A.; Ryan, J.; Bennett, K.; Busetta, M.; Carraminana, A.; Buccheri, R.; Grenier, I. A.

    1994-06-01

    Since the launch of the Compton Gamma-Ray Observatory (CGRO) the number of detected gamma-ray pulsars increased from two to six. COMPTEL, on-board CGRO and sensitive to gamma-rays with energies between approximately 0.7 and 30 MeV, detected three of these unambiguously. The classical Crab and Vela pulsars have been observed on several occasions and detailed pulse patterns and spectral parameters have been derived. The new CGRO gamma-ray pulsar PSR B1509-58 has been detected by COMPTEL at a significance level above 4 sigma, consistently in a timing and spatial analysis. A likely detection of Geminga has been obtained at an approximately 3 sigma level. This indication is found in a phase interval in which COS B data showed the presence of a new variable component, Interpeak 2, exhibiting a very soft spectrum above 50 MeV. The diversities in light-curve sphapes and spectral distributions, the apparent time variabilities, and the significant differences in the fractions of the spin-down power radiated at gamma-ray energies in this small sample of gamma-ray pulsars pose important constraints to pulsar modeling.

  11. Long duration gamma-ray emission from thunderclouds

    Science.gov (United States)

    Kelley, Nicole A.

    Gamma-ray glows are long duration emission coming from thunderclouds. They are one example of high-energy atmospheric physics, a relatively new field studying high-energy phenomena from thunderstorms and lightning. Glows arise from sustained relativistic runaway electron avalanches (RREA). Gamma-ray instruments on the ground, balloons and airplanes have detected glows. The Airborne Detector for Energetic Lightning Emissions (ADELE) is an array of gamma-ray detectors, built at the University of California, Santa Cruz. ADELE detected 12 gamma-ray glows during its summer 2009 campaign. ADELE was designed to study another type of high-energy atmospheric physics, terrestrial gamma-ray flashes (TGFs). TGFs are incredibly bright, sub-millisecond bursts of gamma-rays coming from thunderstorms. ADELE was installed on NCAR's Gulfstream V for the summer of 2009. While many glows were detected, only one TGF was observed. In this thesis I present a detailed explanation of the 2009 version of ADELE along with the results of the 2009 campaign. ADELE was modified to become a smaller, autonomous instrument to fly on the NASA drone, a Global Hawk. This was a piggyback to NASA's Hurricane and Severe Storm Sentinel mission. These flights took place during the summer of 2013. The following summer, ADELE flew on an Orion P3 as a piggyback of NOAA's Hurricane Hunters. This newer, modified instrument is discussed in detail in this thesis. The 12 gamma-ray glows from the 2009 campaign are presented, with information about nearby lightning activity. I show that lightning activity is suppressed after a glow. This could be from the glow causing the cloud to discharge and therefore reduce the lightning activity. It is also possible that glows can only occur once lightning activity has diminished. Lightning is also used to find a distance to the glow. Using this distance, it is found that the brightness of glow cannot be explained as a function of distance while the duration of the glow is

  12. Heliospheric Origin of $\\gamma$-Ray Bursts

    CERN Document Server

    Li Ti Pei

    1997-01-01

    Systematic variations of average observational characteristics and correlation properties between different parameters of gamma-ray bursts (GRBs) with time from 1991 April to 1994 September are revealed. It is hard to explain the observed long-term variability by variations of experimental conditions. The variability of GRB properties with the time scale of months to years, together with the similarity between GRBs, solar hard X-ray flares and terrestrial gamma-ray flashes, may indicate an origin of GRBs, at least partly, within the heliosphere. Large-voltage and high-temperature pinch plasma columns produced by disruptive electrical discharges in the outer heliosphere can generate hard X-ray and gamma-ray flashes with energy spectra and spectral evolution characters consistent with that observed in GRBs.

  13. Found: A Galaxy's Missing Gamma Rays

    Science.gov (United States)

    Kohler, Susanna

    2016-04-01

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

  14. Gamma rays from the interstellar medium

    International Nuclear Information System (INIS)

    This thesis describes new gamma-ray views on cosmic rays and the interstellar medium. The author describes the COS-B data base and the pre-launch and in-flight calibration data used for all analyses. Diffuse galactic gamma radiation (> 50 MeV) may be either a result of cosmic-ray-matter interactions, or of the cosmic-ray electrons with the interstellar radiation field (mainly at optical and infrared wavelengths), through the inverse-Compton process. A detailed comparison between the gamma-ray observations of the large complex of interstellar clouds in Orion and Monoceros and the CO and HI surveys of this region is given. It gives insight into the cloud penetration of cosmic rays and in the relation between CO detections and molecular hydrogen column densities. Next, the radial distribution of gamma rays in the Galaxy is studied, as well as the galactic centre (more precisely, the central 400 pc), which contains a large concentration of CO molecules. The H2/CO abundance and the cosmic-ray density in the galactic centre are discussed and compared to the findings for the galactic disk. In various analyses in this thesis a likelihood-ratio method is applied for parameter estimation and hypothesis testing. A general description of this method is added as an appendix. (Auth.)

  15. GRI: the gamma-ray imager mission

    CERN Document Server

    Knödlseder, J

    2006-01-01

    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 the major science themes that are addressed in the gamma-ray regime. With the INTEGRAL observatory, ESA has provided a unique tool to the astronomical community revealing hundreds of sources, new classes of objects, extraordinary views of antimatter annihilation in our Galaxy, and fingerprints of recent nucleosynthesis processes. While INTEGRAL provides the global overview over the soft gamma-ray sky, there is a growing need to perform deeper, more focused investigations of gamma-ray sources. In soft X-rays a...

  16. Gamma-ray binaries and related systems

    CERN Document Server

    Dubus, Guillaume

    2013-01-01

    After initial claims and a long hiatus, it is now established that several binary stars emit high (0.1-100 GeV) and very high energy (>100 GeV) gamma rays. A new class has emerged called 'gamma-ray binaries', since most of their radiated power is emitted beyond 1 MeV. Accreting X-ray binaries, novae and a colliding wind binary (eta Car) have also been detected - 'related systems' that confirm the ubiquity of particle acceleration in astrophysical sources. Do these systems have anything in common ? What drives their high-energy emission ? How do the processes involved compare to those in other sources of gamma rays: pulsars, active galactic nuclei, supernova remnants ? I review the wealth of observational and theoretical work that have followed these detections, with an emphasis on gamma-ray binaries. I present the current evidence that gamma-ray binaries are driven by rotation-powered pulsars. Binaries are laboratories giving access to different vantage points or physical conditions on a regular timescale as ...

  17. Transuranic isotopic analysis using gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D; Decman, D

    1998-10-15

    Transuranic waste typically emits gamma rays that are characteristic of the isotopic composition of the materials. If the area of the gamma ray photopeaks in a High Purity Ge (HPGe) spectrum can be accurately determined and if the gamma ray/x-ray branching ratios and half-lives for the radionuclides in the sample are known the relative concentration of each isotope in the waste can be determined using tomographic techniques. Methods used to accurately determine these photopeaks usually requires a computer code that does multi-peak analysis and unfolding of a given part of the gamma-ray spectrum. Computer techniques allow an accurate determination of the photopeaks and hence the isotopic composition of the waste material. These computer techniques can be automated for different spectra within a wide range of possible isotopic compositions. To improve photopeak statistics all of the spectra taken in a tomographic survey of the sample are summed and are used in the isotopic analysis. The method, accuracy, and limitations of this type of isotopic analysis system will be discussed. The gamma ray acquisition system is currently being upgraded with multiple HPGe detectors to improve the counting statistics obtainable in a given amount of time. The results of the DOE performance evaluations and the progress of the multiple detector upgrade will be discussed.

  18. 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

  19. Determining a pre-mining radiological baseline from historic airborne gamma surveys: A case study

    International Nuclear Information System (INIS)

    Knowing the baseline level of radioactivity in areas naturally enriched in radionuclides is important in the uranium mining context to assess radiation doses to humans and the environment both during and after mining. This information is particularly useful in rehabilitation planning and developing closure criteria for uranium mines as only radiation doses additional to the natural background are usually considered ‘controllable’ for radiation protection purposes. In this case study we have tested whether the method of contemporary groundtruthing of a historic airborne gamma survey could be used to determine the pre-mining radiological conditions at the Ranger mine in northern Australia. The airborne gamma survey was flown in 1976 before mining started and groundtruthed using ground gamma dose rate measurements made between 2007 and 2009 at an undisturbed area naturally enriched in uranium (Anomaly 2) located nearby the Ranger mine. Measurements of 226Ra soil activity concentration and 222Rn exhalation flux density at Anomaly 2 were made concurrent with the ground gamma dose rate measurements. Algorithms were developed to upscale the ground gamma data to the same spatial resolution as the historic airborne gamma survey data using a geographic information system, allowing comparison of the datasets. Linear correlation models were developed to estimate the pre-mining gamma dose rates, 226Ra soil activity concentrations, and 222Rn exhalation flux densities at selected areas in the greater Ranger region. The modelled levels agreed with measurements made at the Ranger Orebodies 1 and 3 before mining started, and at environmental sites in the region. The conclusion is that our approach can be used to determine baseline radiation levels, and provide a benchmark for rehabilitation of uranium mines or industrial sites where historical airborne gamma survey data are available and an undisturbed radiological analogue exists to groundtruth the data. - Highlights: • Data

  20. 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.

  1. 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.

  2. Evaluation of gamma-ray intensities

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  4. 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

    , 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......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 the...

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

    OpenAIRE

    Jones, B B

    2002-01-01

    Part I describes the analysis of periodic and transient signals in EGRET data. A method to search for the transient flux from gamma-ray bursts independent of triggers from other gamma-ray instruments is developed. Several known gamma-ray bursts were independently detected, and there is evidence for a previously unknown gamma-ray burst candidate. Statistical methods using maximum likelihood and Bayesian inference are developed and implemented to extract periodic signals from gamma-ray sources ...

  6. A segmented detector for airbone gamma ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Burgada, G.; Iovene, A.; Petrucci, S.; Tintori, C., E-mail: g.burgada@caen.it [Costruzioni Apparecchiature Elettroniche Nucleari S.p.A. (CAEN), Viareggio (Italy); Alvarez, M.A.G., E-mail: malvarez@if.usp.br [Universidade de Sao Paulo (IF/USP), Sao Paulo, SP (Brazil). Instituto de Fisica; Baldoncini, M.; Xhixha, G.; Strati, V., E-mail: gerti.xhixha@unife.it [University of Ferrara, Department of Physics and Earth Sciences, Ferrara (Italy); Mantovani, F., E-mail: mantovani@fe.infn.it [Istituto Nazionale di Fisica Nucleare (INFN), Ferrara (Italy); Garosi, P.; Mou, L., E-mail: li.mou@libero.it [University of Siena (Italy); Alvarez, C. Rossi, E-mail: rossialvarez@pd.infn.it [Istituto Nazionale di Fisica Nucleare (INFN), Legnaro (Italy)

    2014-07-01

    The airborne gamma-ray spectrometry (AGRS) is widely acknowledged as a very efficient technique for large areas monitoring. The detector system mounted on a helicopter allows for an extensive survey in a single flight time, thus reducing the exposure risk for the operator. Results from AGRS techniques are exploited in many fields, from the geological research to the homeland security for the search of orphan radioactive sources, from the mining and hydrocarbon exploration to the construction industry. The new generation of compact digital data acquisition and online processing equipment allows for faster airborne survey campaigns, and enhances the flexibility of operations. In addition, the algorithm for the extrapolation of the nuclide concentrations from the acquired gamma spectra is a challenging step of the entire technique. We are going to present a new device for advanced AGRS measurements, with an innovative detector configuration and data processing algorithms for optimizing the source localization and the on-line response capabilities. The new compact structure makes the system easily portable by a single operator, and rapidly mountable on most common helicopters. Preliminary feasibility studies have been performed to test the mechanics and the hardware of the whole system, which is intended to work without any human attendance. The first flights are planned by the end of 2014, with the aim of detecting artificial point sources having intensities on the order of 10^8 Bq and natural enriched fields already monitored. (author)

  7. 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.

  8. Status of the Milagro Gamma Ray Observatory

    CERN Document Server

    Maryland Univ. College Park

    2001-01-01

    The Milagro Gamma Ray Observatory, located at an altitude of 8,600 feet in the Jemez Mountains of New Mexico, is the world's first large-area water Cherenkov detector capable of continuously monitoring the entire sky for sources of TeV gamma rays. It is uniquely capable of searching for transient sources of VHE gamma rays. The core of the detector is a 60m x 80m x 8m pond instrumented with 723 PMTs deployed in two layers. This part of the detector is complete and has operated continuously since Jan. 2000. Initial studies including searches for gamma-ray sources are ongoing, and preliminary results are available. The final stage of construction is under way. We are deploying 170 auxiliary "outrigger" water Cherenkov detectors in an area of 40,000 square-meters surrounding the pond, which will significantly enhance our ability to reject background and more accurately reconstruct the gamma-ray direction and energy. In addition, we are lowering the energy threshold of the detector by using custom processing to en...

  9. 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.

  10. Airborne time-series measurement of soil moisture using terrestrial gamma radiation

    Science.gov (United States)

    Carroll, Thomas R.; Lipinski, Daniel M.; Peck, Eugene L.

    1988-01-01

    Terrestrial gamma radiation data and independent ground-based core soil moisture data are analyzed. They reveal the possibility of using natural terrestrial gamma radiation collected from a low-flying aircraft to make reliable real-time soil moisture measurements for the upper 20 cm of soil. The airborne data were compared to the crude ground-based soil moisture data set collected at the core sites.

  11. Gamma-ray Emission from Globular Clusters

    Science.gov (United States)

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

    2016-03-01

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

  12. Lake Mead dynamic test range for calibration of airborne gamma radiation measuring systems

    International Nuclear Information System (INIS)

    Data are presented for calibrating airborne gamma radiation measuring systems for surface concentrations of U, Th, and K. Data are included for six flight paths at altitudes of 200, 400, 600, 800, 1000, and 1200 feet. Lake Mead Dynamic Test Range is described in detail in Volume I of this report

  13. Lake Mead dynamic test range for calibration of airborne gamma radiation measuring systems

    Energy Technology Data Exchange (ETDEWEB)

    1977-01-01

    Data are presented for calibrating airborne gamma radiation measuring systems for surface concentrations of U, Th, and K. Data are included for six flight paths at altitudes of 200, 400, 600, 800, 1000, and 1200 feet. Lake Mead Dynamic Test Range is described in detail in Volume I of this report. (WHK)

  14. Gamma ray source studies using muon tracking

    International Nuclear Information System (INIS)

    A large area (128 m2) streamer tube detector, located within the KASCADE-Grande experiment has been built. We discuss the possibility of observing gamma-ray sources by means of photo-pion produced single isolated muon tracks above the background of cosmic-ray muons using a muon tracking detector (MTD). Properties of the photo-production process in the atmosphere and of the MTD which support the identification of gammas are discussed. The sensitivity of the technique of observing the Crab energy spectrum in the tens of GeV range is discussed. Gamma spectra accumulated from Crab and a Mrk 421 flux correlation with X-ray (RXTE/PCA) are presented.

  15. 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...

  16. Gamma-ray bursters at cosmological distances

    Science.gov (United States)

    Paczynski, B.

    1986-01-01

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

  17. Solution To The Gamma Ray Burst Mystery?

    CERN Document Server

    Dar, Arnon

    1996-01-01

    Photoexcitation and ionization of partially ionized heavy atoms in highly relativistic flows by interstellar photons, followed by their reemission in radiative recombination and decay, boost star-light into beamed $\\gamma$ rays along the flow direction. Repeated excitation/decay of highly relativistic baryonic ejecta from merger or accretion induced collapse of neutron stars in dense stellar regions (DSRs), like galactic cores, globular clusters and super star-clusters, can convert enough kinetic energy in such events in distant galaxies into cosmological gamma ray bursts (GRBs). The model predicts remarkably well all the main observed temporal and spectral properties of GRBs. Its success strongly suggests that GRBs are $\\gamma$ ray tomography pictures of DSRs in galaxies at cosmological distances with unprecedented resolution: A time resolution of $dt\\sim 1~ms$ in a GRB can resolve stars at a Hubble distance which are separated by only $D\\sim 10^{10}cm$. This is equivalent to the resolving power of an optica...

  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. 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.

  20. Gamma-Ray Bursts: Jets and Energetics

    CERN Document Server

    Frail, D A

    2003-01-01

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

  1. Very high energy gamma ray astrophysics

    International Nuclear Information System (INIS)

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

  2. Gamma ray spectrometer for Lunar Scout 2

    Science.gov (United States)

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

    1993-01-01

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

  3. A Shotgun Model for $\\gamma$ Ray Bursts

    CERN Document Server

    Heinz, S

    1999-01-01

    We propose that gamma ray bursts (GRBs) are produced by a shower of heavy blobs running into circumstellar material at highly relativistic speeds. The gamma ray emission is produced in the shocks these bullets drive into the surrounding medium. The short term variability seen in GRBs is set by the slowing-down time of the bullets while the overall duration of the burst is set by the lifetime of the central engine. A requirement of this model is that the ambient medium be dense, consistent with a strong stellar wind. In contrast to other external shock scenarios, the efficiency of the shock can be close to unity.

  4. Gamma rays induced variation in Plantago ovata

    International Nuclear Information System (INIS)

    Plantago ovata Fork., a medicinal herb, requires improvement in seed yield to meet would demand for its seed husk. Mutation breeding has been attempted on account of narrow genetic base of the crop. The mutagen, gamma rays from 60Co sources was tried for its effect on various phenotypic traits, including those related to seed yield. Studies indicate that P. ovata is radio-resistant. Gamma rays also induce alteration in mean and variance of yield related characters which can be exploited to select superior genotypes in this conservative crop

  5. 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.

  6. Gamma-ray surveys in uranium exploration

    International Nuclear Information System (INIS)

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

  7. 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.

  8. 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%

  9. 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.

  10. GammaModeler 3-D gamma-ray imaging technology

    International Nuclear Information System (INIS)

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

  11. Skyshine spectra of gamma rays

    International Nuclear Information System (INIS)

    A study of the spectra of gamma photons back-scattered in vertical direction by infinite air above ground (skyshine) is presented. The source for these measurements is a 650 Ci Cobalt-60 point-source and the skyshine spectra are reported for distances from 150 m to 325 m from the source, measured with a 5 cm x 5 cm NaI(Tl) detector collimated with collimators of 12 mm and 20 mm diameter and 5 cm length. These continuous spectra are unfolded with Gold's iterative technique. The photon-spectra so obtained have a distinct line at 72 keV due to multiply-scattered photons. This is an energy where photoelectric and Compton cross-sections for multiply-scattered photons balance each other. The intensity of the line(I) decreases exponentially with distance (d) from the source obeying a relation of the type I = Isub(o)esup(-μd) where μ is called as ''Multiply-Scatter Coefficient'', a constant of the medium which is air in these measurements. This relationship is explained in terms of a halo around the source comprising of multiply-scattered gamma photons, Isub(0) being the intensity of these scattered photons at the location of cobalt-source. A fraction called as ''Back-scattered Fraction'', the ratio of Isub(0) to the number of original photons from the cobalt-source entering the infinite air, is also calculated. It is shown that with a properly calibrated detector system, this fraction can be used to determine the strength of a large gamma source, viz. a nuclear explosion in air, and for mineral prospecting. These conclusions are general and can be applied to any other infinite medium. Some forward-scatter (transmission) spectra of cobalt-60 source through 10 cm of Pb and 2.5 cm of Al are also reported. (auth.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-03-01

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

  13. Regional radiometric map of Syria, using gamma-ray spectrometer

    International Nuclear Information System (INIS)

    The regional radiometric gamma-ray spectrometry map of Syria, scaled 1/1000000, for surficial concentration of the total radioactivity (Ur), eU, eTh and %K was completely achieved after normalizing the airborne and carbon data sets to match each other. It worthy notice that, the anomalies found to be closely related to either phosphate and/or glauconite deposits. It is worth mentioning that throughout the survey work many scattered occurrences of secondary uranium mineralization were found as spots in some formations and phosphate rocks. Where this phenomena attributes to chemical and physical disseminating instead of accumulating the radioelements. So, that leads to a weak expectation for usual surface uranium deposits where attributed to the oxidizing condition. Then this expectation remains, as an open question requires answering through planning to subsurface prospecting. (Author)

  14. Developments in mercuric iodide gamma ray imaging

    International Nuclear Information System (INIS)

    A mercuric iodide (HgI2) gamma ray imaging array and camera system previously described have been characterized for spatial and energy resolution. Based on these data a new camera is being developed to more fully exploit the potential of the array. Characterization results and design criteria for the new camera will be presented. (orig.)

  15. Developments in mercuric iodide gamma ray imaging

    Science.gov (United States)

    Patt, B. E.; Beyerle, A. G.; Dolin, R. C.; Ortale, C.

    1989-11-01

    A mercuric iodide (HgI2) gamma ray imaging array and camera system previously described have been characterized for spatial and energy resolution. Based on these data a new camera is being developed to more fully exploit the potential of the array. Characterization results and design criteria for the new camera will be presented.

  16. Developments in mercuric iodide gamma ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Patt, B.E.; Beyerle, A.G.; Dolin, R.C.; Ortale, C.

    1987-01-01

    A mercuric iodide gamma-ray imaging array and camera system previously described has been characterized for spatial and energy resolution. Based on this data a new camera is being developed to more fully exploit the potential of the array. Characterization results and design criterion for the new camera will be presented. 2 refs., 7 figs.

  17. Developments in mercuric iodide gamma ray imaging

    Energy Technology Data Exchange (ETDEWEB)

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

    1989-11-01

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

  18. 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…

  19. Gamma ray induced female mutation in castor

    International Nuclear Information System (INIS)

    Three female mutants in castor (Ricinus communis L.) were obtained from 100 to 125 kR gamma-rays treated M2 population. The racemes of these mutants bore only pistillate flowers. This character is monogenic, recessive and these mutants can be used for large scale hybrid seed production

  20. The single backscattering of gamma rays

    International Nuclear Information System (INIS)

    The paper presents the results of the single backscattering investigations of gamma rays in various materials. A simplified mathematical model is given for determining the probability that a photon scattered back by a single Compton scattering is incident on the detector. The probability is calculated as a function of the primary photon energy and the atomic number Z of the scatterer. (Auth.)

  1. Neutrino Balls and Gamma-Ray Bursts

    CERN Document Server

    Holdom, B

    1994-01-01

    We propose a mechanism by which the neutrino emission from a supernova-type explosion can be converted into a gamma-ray burst of total energy $\\sim 10^{50}$ ergs. This occurs naturally if the explosion is situated inside a ball of trapped neutrinos, which in turn may lie at a galactic core. There are possible unique signatures of this scenario.

  2. Primary shutter and gamma ray trap

    International Nuclear Information System (INIS)

    This paper reports on the main radiation shutter and gamma ray trap, which will be used at LNLS front-ends that has been designed. The components external to the UHV chamber have been assembled and are undergoing tests. Vacuum requirements for the chamber have been estimated

  3. The new gamma-ray observatory: CTA

    Science.gov (United States)

    Carr, John

    2016-07-01

    CTA is the next generation gamma-ray observatory and will have a factor 10 better sensitivity compared to existing facilities, as well as many other superior parameters. Aspects of array layout, performance and sites are presented. The broad range of forefront science which will be studied is described.

  4. 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...

  5. Gamma ray bursts of black hole universe

    Science.gov (United States)

    Zhang, T. X.

    2015-07-01

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

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

    Science.gov (United States)

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

    2016-02-01

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

  7. 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.

  8. 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.

  9. Gamma-ray emission from normal galaxies ?

    International Nuclear Information System (INIS)

    Full text: Usual suspects for extragalactic high energy gamma-ray emission are cosmic monsters: supermassive black holes and their surrounding, embedded in Active Galactic Nuclei. Normal galaxies begin to arise from the shadows at high energies, as can be seen with the discovery of high energy gamma-ray emission from the Andromeda galaxy (M 31) by the Fermi collaboration. This emission is expected to originate from cosmic ray (CR) interactions with the interstellar medium in these galaxies. For the first time, measurements of the CR energy density are possible outside our Galaxy. We present a study on the search for high energy emission around normal galaxies in the neighbourhood of our Milky Way. (author)

  10. Interstellar medium structure and content and gamma ray astronomy

    International Nuclear Information System (INIS)

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

  11. High Energy $\\gamma$ Rays from Ultrahigh Energy Cosmic Ray Protons in $\\gamma$ Ray Bursts

    CERN Document Server

    Böttcher, M

    1998-01-01

    It has recently been proposed that ultrahigh energy ($\\gtrsim 10^{19}$ eV) cosmic rays (UHECR) are accelerated by the blast waves associated with GRBs. We calculate the observed synchrotron radiation spectrum from protons and energetic leptons formed in the cascades initiated by photopion production, taking into account $\\gamma\\gamma$ attenuation at the source. Normalizing to the emission characteristics of GRB~970508, we predict $\\sim 10$ MeV - 100 GeV fluxes at a level which may have been observed with EGRET from bright GRBs, and could be detected with the proposed GLAST experiment or with ground-based air Cherenkov telescopes having thresholds $\\lesssim $ several hundred GeV. Besides testing the UHECR origin hypothesis, the short wavelength emission and afterglows can be used to probe the level of the diffuse intergalactic infrared radiation fields or constrain redshifts of GRB sources.

  12. Gamma-ray Spectrometry in Geothermal Exploration: State of the Art Techniques

    Directory of Open Access Journals (Sweden)

    Alistair T. McCay

    2014-07-01

    Full Text Available Gamma-ray spectrometry is a surveying technique that allows the calculation of the heat produced during radioactive decay of potassium, uranium, and thorium within rock. Radiogenic heat producing rocks are often targets for geothermal exploration and production. Hence, refinements in gamma-ray spectrometry surveying will allow better constraint of resources estimation and help to target drilling. Gamma-rays have long half-lengths compared to other radiation produced during radiogenic decay. This property allows the gamma-rays to penetrate far enough through media to be detected by airborne or ground based surveying. A recent example of ground-based surveying in Scotland shows the ability of gamma-ray spectrometry to quickly and efficiently categorize granite plutons as low or high heat producing. Some sedimentary rocks (e.g., black shales also have high radiogenic heat production properties and could be future geothermal targets. Topographical, atmospheric and spatial distribution factors (among others can complicate the collection of accurate gamma-ray data in the field. Quantifying and dealing with such inaccuracies represents an area for further improvement of these techniques for geothermal applications.

  13. Balloon-borne gamma-ray telescope with nuclear emulsion

    OpenAIRE

    Takahashi, Satoru; Group, for the Emulsion Gamma-ray Telescope

    2010-01-01

    By detecting the beginning of electron pairs with nuclear emulsion, precise gamma-ray direction and gamma-ray polarization can be detected. With recent advancement in emulsion scanning system, emulsion analyzing capability is becoming powerful. Now we are developing the balloon-borne gamma-ray telescope with nuclear emulsion. Overview and status of our telescope is described.

  14. Principles and techniques of gamma ray tracers

    International Nuclear Information System (INIS)

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

  15. Shielding evaluation by laser compton scattering gamma-ray

    International Nuclear Information System (INIS)

    Laser Compton scattering gamma-ray beam was used for evaluation of gamma ray shield. The gamma source of a NewSUBARU Synchrotron Radiation Facility can generate the quasi-monochromatic gamma ray beam of 0.5-1.7 MeV by combining a carbon dioxide laser and a 0.5-1.0 GeV electron beam. This gamma-ray source has small divergence of 1/γ radian due to the relativistic effect, where γ is relativistic factor of electron. Small diameter test beam of gamma-ray of about 1 mm in diameter is possible to use at the 10 m from the gamma-ray source by combining the small divergence gamma-ray beam with small hole lead collimator. Test sample size used was 2 cm in diameter. Measured shield factor was compared with calculated value using known shield materials such as lead. (author)

  16. 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.

  17. Gamma-ray pulsars: A gold mine

    Science.gov (United States)

    Grenier, Isabelle A.; Harding, Alice K.

    2015-08-01

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

  18. The Fermi Gamma-Ray Burst Monitor

    CERN Document Server

    Meegan, Charles; Bhat, P N; Bissaldi, Elisabetta; Briggs, Michael S; Connaughton, Valerie; Diehl, Roland; Fishman, Gerald; Greiner, Jochen; Hoover, Andrew S; van der Horst, Alexander J; von Kienlin, Andreas; Kippen, R Marc; Kouveliotou, Chryssa; McBreen, Sheila; Paciesas, W S; Preece, Robert; Steinle, Helmut; Wallace, Mark S; Wilson, Robert B; Wilson-Hodge, Colleen

    2009-01-01

    The Gamma-Ray Burst Monitor (GBM) will significantly augment the science return from the Fermi Observatory in the study of Gamma-Ray Bursts (GRBs). The primary objective of GBM is to extend the energy range over which bursts are observed downward from the energy range of the Large Area Telescope (LAT) on Fermi into the hard X-ray range where extensive previous data exist. A secondary objective is to compute burst locations on-board to allow re-orientiong the spacecraft so that the LAT can observe delayed emission from bright bursts. GBM uses an array of twelve sodium iodide scintillators and two bismuth germanate scintillators to detect gamma rays from ~8 keV to ~40 MeV over the full unocculted sky. The on-board trigger threshold is ~0.7 photons/cm2/s (50-300 keV, 1 s peak). GBM generates on-board triggers for ~250 GRBs per year.

  19. X-ray and gamma ray transmission densitometry

    International Nuclear Information System (INIS)

    Gamma and x-ray attenuation densitometers are systems in which measurements of the attenuation of one or several radiation beams are used to infer the density of the attenuating material. This report contains discussions of theoretical and practical aspects of densitometer design, operation, and data interpretation

  20. The Haleakala Gamma Ray Observatory

    International Nuclear Information System (INIS)

    A 10 m2 multi-mirror telescope for observing Cherenkov light signals from atmospheric cascades is now operating at Mount Haleakala, Maui, Hawaii. It differs from other atmospheric Cherenkov detectors in accepting pulses that originate from single photoelectrons, employing two sets of 18 optically independent phototubes in a logic system with nanosecond time resolution to reject ambient light from the night sky. With an angular aperture of 1.3x10-4 sr, cosmic ray showers are observed at a rate of ≅ 0.5 hz at the zenith, with nearly complete rejection of ambient light. This rate for hadronic showers implies an effective threshold near 100 GeV for electromagnetic showers. Two regions of the sky, one centered on the source and the other separated by from it by 3.60 are simultaneously monitored. Examples of observations of episodic and periodic (pulsar) sources are given. (orig.)

  1. Airborne gamma radiation measurements of soil moisture during FIFE: Activities and results

    Science.gov (United States)

    Peck, Eugene L.

    1992-01-01

    Soil moisture measurements were obtained during the summer of 1987 and 1989 near Manhattan, Kansas, using the National Weather Service (NWS) airborne gamma radiation system. A network of 24 flight lines were established over the research area. Airborne surveys were flown daily during two intensive field campaigns. The data collected was sufficient to modify the NWS standard operational method for estimating soil moisture for the Field Experiment (FIFE) flight lines. The average root mean square error of the soil moisture estimates for shorter FIFE flight lines was found to be 2.5 percent, compared with a reported value of 3.9 percent for NWS flight lines. Techniques were developed to compute soil moisture estimates for portions of the flight lines. Results of comparisons of the airborne gamma radiation soil moisture estimates with those obtained using the NASA Pushbroom Microwave Radiation (PBMR) system and hydrological model are presented. The airborne soil moisture measurements, and real averages computed using all remotely sensed and ground data, have been in support of the research of the many FIFE investigators whose overall goal was the upscale integration of models and the application of satellite remote sensing.

  2. Application of Bayesian decision theory to airborne gamma snow measurement

    Science.gov (United States)

    Bissell, V. C.

    1975-01-01

    Measured values of several variables are incorporated into the calculation of snow water equivalent as measured from an aircraft by snow attenuation of terrestrial gamma radiation. Bayesian decision theory provides a snow water equivalent measurement by taking into account the uncertainties in the individual measurement variables and filtering information about the measurement variables through prior notions of what the calculated variable (water equivalent) should be.

  3. 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

  4. Airborne gamma spectrometric survey in the Chernobyl exclusion zone based on oktokopter UAV type

    International Nuclear Information System (INIS)

    The results of field studies of radioactive contamination condition of RWTSP ''Red Forest'' and ''Neftebaza'' in the Chernobyl zone, obtained by the authors in June 2015 are represented. The technique of detection of local inhomogeneities on the soil surface without contrasting borders by airborne gamma spectrometry from the board of oktokopter UAV type is worked through. The technique of searching and contouring of hidden burial of radioactive waste is practiced

  5. Solar gamma-ray lines and interplanetary solar protons

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimori, M.

    1985-12-01

    Solar gamma-ray lines and protons were simultaneously observed for six flares on 1 April, 4 April, 27 April, 13 May 1981, 1 February, and 6 June, 1982 by Hinotori and Himawari satellites. The time histories of gamma-ray lines and protons are analyzed. The relationship between the gamma-ray line fluences and peak proton fluxes for these flares does not reveal an apparent correlation between them. The present result implies that the protons producing gamma-ray lines in the flare region and protons observed near the earth do not always belong to the same population, and favor the downward streaming model for the gamma-ray line production.

  6. Relativistic effects in gamma-ray bursts

    International Nuclear Information System (INIS)

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

  7. 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

  8. Environmental Effects of Gamma Ray Bursts

    International Nuclear Information System (INIS)

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

  9. 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.

  10. Attenuation of the gamma rays in tissues

    International Nuclear Information System (INIS)

    The mass and lineal attenuation coefficient and of hepatic tissue, muscular, osseous and of brain before gamma rays of 10-3 to 105 MeV were calculated. For the case of the osseous tissue the calculation was made for the cartilage, the cortical tissue and the bone marrow. During the calculations the elementary composition of the tissues of human origin was used. The calculations include by separate the Photoelectric effect, the Compton scattering and the Pair production, as well as the total. For to establish a comparison with the attenuation capacities, the coefficients of the water, the aluminum and the lead also were calculated. The study was complemented measuring the attenuation coefficient of hepatic tissue of bovine before gamma rays of 0.662 MeV of a source of 137 Cs. The measurement was made through of an experiment of photons transmission through samples frozen of hepatic tissue and with a Geiger-Mueller detector. (Author)

  11. Gamma-ray Constraints on Effective Interactions

    CERN Document Server

    Cheung, Kingman; Yuan, Tzu-Chiang

    2011-01-01

    Using an effective interaction approach to describe the interactions between the dark matter particle and the light degrees of freedom of the standard model, we calculate the gamma-ray flux due to the annihilation of the dark matter into quarks, followed by fragmentation into neutral pions which subsequently decay into photons. By comparison to the mid-latitude data released from the Fermi-LAT experiment, we obtain useful constraints on the size of the effective interactions and they are found to be comparable to those deduced from collider, gamma-ray line and anti-matter search experiments. However, the two operators induced by scalar and vector exchange among fermionic dark matter and light quarks that contribute to spin-independent cross sections are constrained more stringently by the recent XENON100 data.

  12. Gamma-Ray Burst Prompt Emission

    CERN Document Server

    Zhang, Bing

    2014-01-01

    The origin of gamma-ray burst (GRB) prompt emission, bursts of gamma-rays lasting from shorter than one second to thousands of seconds, remains not fully understood after more than 40 years of observations. The uncertainties lie in several open questions in the GRB physics, including jet composition, energy dissipation mechanism, particle acceleration mechanism, and radiation mechanism. Recent broad-band observations of prompt emission with Fermi sharpen the debates in these areas, which stimulated intense theoretical investigations invoking very different ideas. I will review these debates, and argue that the current data suggest the following picture: A quasi-thermal spectral component originating from the photosphere of the relativistic ejecta has been detected in some GRBs. Even though in some cases (e.g. GRB 090902B) this component dominates the spectrum, in most GRBs, this component either forms a sub-dominant "shoulder" spectral component in the low energy spectral regime of the more dominant "Band" co...

  13. 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.

  14. Requirements on gamma ray spectrum analysis programs

    International Nuclear Information System (INIS)

    Many programs intended for the evaluation of gamma ray spectra have been written. Most of them cover the basic needs but there are several options a user might want to have which are not incorporated. This paper attempts to list all general and some special requirements on such programs. Recommendations on details of the physical and technical methods to match the requirements and the citation of any existing program are avoided. (author)

  15. Gamma Ray Bursts and their Optical Counterparts

    International Nuclear Information System (INIS)

    Gamma Ray Bursts (GRB) have been discovered 38 years ago and still remain one of the most intriguing puzzles of astrophysics. In this paper we remind briefly the history of GRB studies and review the current experimental evidence with the emphasis on GRB optical counterparts. At the end we introduce '' π of the Sky '' project designed to catch prompt optical emission from GRB sources. (author)

  16. Cosmological parametrization of $\\gamma$ ray burst models

    CERN Document Server

    Linder, E V

    1996-01-01

    Using three parametrizations of the gamma ray burst count data comparison is made to cosmological source models. While simple models can fit and faint end slope constraints, the addition of a logarithmic count range variable describing the curvature of the counts shows that models with no evolution or evolution power law in redshift with index less than 10 fail to satisfy simultaneously all three descriptors of the burst data. The cosmological source density that would be required for a fit is illustrated.

  17. Solution To The Gamma Ray Burst Mystery?

    OpenAIRE

    Shaviv, Nir J.; Dar, Arnon

    1996-01-01

    Photoexcitation and ionization of partially ionized heavy atoms in highly relativistic flows by interstellar photons, followed by their reemission in radiative recombination and decay, boost star-light into beamed $\\gamma$ rays along the flow direction. Repeated excitation/decay of highly relativistic baryonic ejecta from merger or accretion induced collapse of neutron stars in dense stellar regions (DSRs), like galactic cores, globular clusters and super star-clusters, can convert enough kin...

  18. Gamma-ray bursts - a critical review

    International Nuclear Information System (INIS)

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

  19. EXIST's Gamma-Ray Burst Sensitivity

    OpenAIRE

    Band, D. L.; Grindlay, J. E.; Hong, J.; Fishman, G.; Hartmann, D. H.; Garson III, A.; Krawczynski, H.; Barthelmy, S.; Gehrels, N.; Skinner, G.

    2007-01-01

    We use semi-analytic techniques to evaluate the burst sensitivity of designs for the EXIST hard X-ray survey mission. Applying these techniques to the mission design proposed for the Beyond Einstein program, we find that with its very large field-of-view and faint gamma-ray burst detection threshold, EXIST will detect and localize approximately two bursts per day, a large fraction of which may be at high redshift. We estimate that EXIST's maximum sensitivity will be ~4 times greater than that...

  20. Very high energy gamma ray astrophysics

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    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 γ-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 streams

  2. Swift: A Gamma Ray Bursts Explorer

    Science.gov (United States)

    Gehrels, Neil

    2003-01-01

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

  3. Gamma Rays frim the Galactic Centre

    CERN Document Server

    Erlykin, A D

    2007-01-01

    Recent results from the HESS gamma ray telescope have shown the presence of both a diffuse, extended, flux of gamma rays above ~0.4 TeV and discrete sources in and near the Galactic Centre. Here, we put forward a possible explanation in terms of the diffusion of cosmic ray protons from a succession of supernova remnants (SNR) in the SgrA* region of the Galaxy plus a contribution from SNR in the rest of the Galactic Centre Region, to be called the Galactic Centre Ridge (GCR). Protons are favoured over electrons because the mG magnetic fields in the Region will attenuate energetic electrons severely. Prominent features are the need for 'anomalous diffusion' of the protons in the whole region and the adoption of low efficiency for SNR acceleration in the high density regions. The latter is related by us to the well-known low 'cosmic ray gradient' in the Galaxy. A corroborating feature is the close correlation of inferred cosmic ray intensity with the smoothed intensity of 5 GHZ radio radiation. We attribute this...

  4. Gamma-ray astronomy with underground detectors

    CERN Document Server

    Halzen, Francis

    1995-01-01

    Underground detectors measure the directions of up-coming muons of neutrino origin. They can also observe down-going muons made by gamma rays in the Earth's atmosphere. Although gamma ray showers are muon-poor, they produce a sufficient number of muons to detect the sources observed by GeV and TeV telescopes. With a threshold higher by one hundred and a probability of muon production of about 1\\% for the shallower AMANDA and Lake Baikal detectors, these instruments can, for a typical GRO source, match the detection efficiency of a GeV satellite detector since their effective area is larger by a factor 10^4. The muons must have enough energy for accurate reconstruction of their direction. Very energetic muons on the other hand are rare because they are only produced by higher energy gamma rays whose flux is suppressed by the decreasing flux at the source and by absorption on interstellar light. We show that there is a window of opportunity for muon astronomy in the 100~GeV energy region which nicely matches th...

  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. Distribution of Gamma-Ray Bursts

    Science.gov (United States)

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

    2014-01-01

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

  7. Study of p-wave gamma-ray strength functions

    International Nuclear Information System (INIS)

    Gamma-ray strength functions are important for description of the gamma emission channel in nuclear reactions. The impact of different models- Weisskopf's single particle model, Brink's standard Lorentzian and Kopecky's generalized Lorentzian for gamma ray strength functions on the calculation of neutron capture related experimental quantities such as total radiation widths Γγ cross sections and gamma-ray spectra has been studied

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

    International Nuclear Information System (INIS)

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

  9. 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.

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

    International Nuclear Information System (INIS)

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

  11. The solar gamma ray and neutron capabilities of COMPTEL on the Gamma Ray Observatory

    Science.gov (United States)

    Ryan, James M.; Lockwood, John A.

    1989-01-01

    The imaging Compton telescope COMPTEL on the Gamma Ray Observatory (GRO) has unusual spectroscopic capabilities for measuring solar gamma-ray and neutron emission. The launch of the GRO is scheduled for June 1990 near the peak of the sunspot cycle. With a 30 to 40 percent probability for the Sun being in the COMPTEL field-of-view during the sunlit part of an orbit, a large number of flares will be observed above the 800 keV gamma-ray threshold of the telescope. The telescope energy range extends to 30 MeV with high time resolution burst spectra available from 0.1 to 10 MeV. Strong Compton tail suppression of instrumental gamma-ray interactions will facilitate improved spectral analysis of solar flare emissions. In addition, the high signal to noise ratio for neutron detection and measurement will provide new neutron spectroscopic capabilities. Specifically, a flare similar to that of 3 June 1982 will provide spectroscopic data on greater than 1500 individual neutrons, enough to construct an unambiguous spectrum in the energy range of 20 to 200 MeV. Details of the instrument and its response to solar gamma-rays and neutrons will be presented.

  12. Discovery of a Young Gamma-ray Pulsar Associated with an Extended TeV Gamma-ray Source

    OpenAIRE

    Dormody, Michael; Collaboration, for the Fermi-LAT

    2009-01-01

    Since its launch in June 2008, the Large Area Telescope (LAT), onboard the \\emph{Fermi} Gamma-ray Space Telescope, has greatly added to our understanding of gamma-ray pulsars. Its fine point spread function and large effective area, combined with the time-differencing method, make it the first gamma-ray instrument capable of discovering a new population of gamma-ray pulsars. We will present the recent discovery of the youngest (~4600 yr) radio-quiet gamma-ray pulsar discovered in a blind freq...

  13. The Swift Gamma-Ray Burst Mission

    CERN Document Server

    Gehrels, N; Burrows, D N; Chincarini, G L; Cominsky, L R; Giommi, P; Hurley, K C; Marshall, F E; Mason, K O; Mészáros, P; Nousek, J A; Roming, P W A; Wells, A A; White, N E; Team, Swift Science

    2004-01-01

    The Swift mission, scheduled for launch in early 2004, is a multiwavelength observatory for gamma-ray burst (GRB) astronomy. It is the first-of-its-kind autonomous rapid-slewing satellite for transient astronomy and pioneers the way for future rapid-reaction and multiwavelength missions. It will be far more powerful than any previous GRB mission, observing more than 100 bursts per year and performing detailed X-ray and UV/optical afterglow observations spanning timescales from 1 minute to several days after the burst. The objectives are to determine the origin of GRBs; classify GRBs and search for new types; study the interaction of the ultra-relativistic outflows of GRBs with their surrounding medium; and use GRBs to study the early universe out to z>10. The mission is being developed by a NASA-led international collaboration. It will carry three instruments: a new-generation wide-field gamma-ray (15-150 keV) detector; a narrow-field X-ray telescope; and a narrow-field UV/optical telescope. Redshift determin...

  14. The Swift Gamma Ray Burst Mission

    Science.gov (United States)

    Gehrels, Neil

    2004-01-01

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

  15. Is Calvera a Gamma-ray Pulsar?

    CERN Document Server

    Halpern, J P

    2011-01-01

    Originally selected as a neutron star (NS) candidate in the ROSAT All-Sky Survey, 1RXS J141256.0+792204 ("Calvera") was discovered to be a 59 ms X-ray pulsar in a pair of XMM-Newton observations (Zane et al. 2011). Surprisingly, their claimed detection of this pulsar in Fermi gamma-ray data requires no period derivative, severely restricting its dipole magnetic field strength, spin-down luminosity, and distance to small values. This implies that the cooling age of Calvera is much younger than its characteristic spin-down age. If so, it could be a mildly recycled pulsar, or the first "orphaned" central compact object (CCO). Here we show that the published Fermi ephemeris fails to align the pulse phases of the two X-ray observations with each other, which indicates that the Fermi detection is almost certainly spurious. Analysis of additional Fermi data also does not confirm the gamma-ray detection. This leaves the spin-down rate of Calvera less constrained, and its place among the families of NSs uncertain. It ...

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

    International Nuclear Information System (INIS)

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

  17. Testing a Light-weight Compact Gamma Ray Detector for Measuring Snow Water Equivalent

    Science.gov (United States)

    Saiet, E., II; Solie, D. J.; Sturm, M.

    2014-12-01

    The use of gamma ray to measure snow water equivalent (SWE) trace back to the 1970s during the Soviet Union hydrology program. Over the years research has shown that gamma detectors could be used to monitor SWE, and their use significantly expanded. In the 1980s several airborne campaigns were launched in North America to measure SWR; these gamma flights are still in use today. However, these airborne flights require a twin-engine aircraft and a detector with a computer that weighs 250 kg, which is unsuitable for use with unmanned airborne systems (UAS), our primary interest. Here we describe results of tests of a compact gamma detector weighing 2 kg. The envisioned deployment of this detector is on a small quad-copter UAS that can hover low over remote clearings in the boreal forest of interior Alaska. Such a technique may allow SWE estimates in places that otherwise would be difficult to measure. We tested the detector over snow and water bodies and found for SWE between 0 and 50 cm a sensitivity of ± 2 cm SWE, which is sufficient to resolve any significant snowfall in the region. In this presentation we will discuss our preliminary results and our future strategy for deploying the sensor on a UAS.

  18. High-energy gamma-ray afterglows from low-luminosity gamma-ray bursts

    OpenAIRE

    He, Hao-Ning; WANG, XIANG-YU; Yu, Yun-Wei; Meszaros, Peter

    2009-01-01

    The observations of gamma-ray bursts (GRBs) such as 980425, 031203 and 060218, with luminosities much lower than those of other classic bursts, lead to the definition of a new class of GRBs -- low-luminosity GRBs. The nature of the outflow responsible for them is not clear yet. Two scenarios have been suggested: one is the conventional relativistic outflow with initial Lorentz factor of order of $\\Gamma_0\\ga 10$ and the other is a trans-relativistic outflow with $\\Gamma_0\\simeq 1-2$. Here we ...

  19. Measurement of snow water storage in the Lake Saperior basin using aerial gamma-ray spectrometry

    International Nuclear Information System (INIS)

    A pilot project was started in 1977 over the Lake Superior basin to measure water storage on the land area using aerial gamma-ray spectrometry to provide hydrologic information for forecasting inflow to the lake. Two airborne surveys were made, respectively in November 1977 and March 1978 which provided estimates of the increase in snow water equivalent between these surveys. The basin is located on the Canadian Shield and consequently, the gamma radiation count rate is quite variable. The airborne results are compared with ground measurements on selected flight lines and show generally good agreement. Two equipment calibrations in the Ottawa area provided inconsistent parameter values which are consequently also reflected in the results over the Lake Superior basin. The project has demonstrated to-date that the technique can be developed into an operational system for measuring snow cover water equivalent of this vast and remote area by using well calibrated equipment and processing the spectrometric measurements with great care. (Auth.)

  20. 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.

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    Marel, J V D

    2001-01-01

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

  3. List of strong gamma-rays emitted from radionuclides

    International Nuclear Information System (INIS)

    This is a compilation of intense gamma-rays, with energy value greater than 1 keV, emitted from decay of radioactive nuclides. These gamma-rays are three strongest of gamma-rays originating from each radionuclide. These gamma-rays are listed in the order of increasing energy. The table contains the energy and the intensity of the gamma-rays, the parent nuclide, the decay mode and the half-life of the parent nuclide and the total number of gamma-rays originating from the nuclide, and is also accompanied with energies and intensities of other two of the three gamma-rays in the same row. The list can be used as a quick guide to identify radionuclides in gamma-ray spectrometry. An annex contains the list of radionuclides having no measured gamma-ray intensities, together with energy values of the gamma-rays. The numerical values given in the list are taken from the values adopted in the Evaluated Nuclear Structure Data File (ENSDF) maintained by the National Nuclear Data Center at Brookhaven National Laboratory, as of February 1991. The list has also been prepared on a floppy diskette. (author)

  4. Area specific stripping of lower energy windows for AGS and CGS NaI systems[Airborne Gamma Spectrometry; Carbone Gamma Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Korsbech, U.; Aage, H.K. [Technical Univ. of Denmark (Denmark); Bystroem, S.; Wedmark, M. [Geological Survey of Sweden (Sweden); Thorshaug, S. [Norwegian Radiation Protection Agency (Norway); Bargholz, K. [Danish Emergency Management Agency (Denmark)

    2005-05-01

    The report describes the results from a NKS (Nordic Nuclear Safety Research) project aiming at examining the possibilities for extracting stripping factors for Airborne Gamma-ray Spectrometry (AGS) data and Carborne Gamma-ray Spectrometry (CGS) data directly from the recorded set of data, i.e. without having to calibrate the detector systems on beforehand. The project 'NKS project ASSb' has been carried out between 1 August 2004 and 31 March 2005 by a research group composed of persons from Technical University of Denmark (DTU), Danish Emergency Management Agency (DEMA), Geological Survey of Sweden (SGU), and Norwegian Radiation Protection Authority (NRPA). The AGS and CGS data sets used for the project were recorded by SGU, DEMA, NGU (Geological Survey of Norway), and SSI (Swedish Radiation Protection Institute). Most of the project effort has been directed towards analysing AGS and CGS data with point source signals recorded at the Barents Rescue 2001 LIVEX exercise at Boden in Sweden. Possibilities and limitations for the method have been identified. (au)

  5. 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.

  6. Airborne gamma anomalies in the Elbe Valley near Koenigstein, Germany - Origin and variation with time

    International Nuclear Information System (INIS)

    In 1982, an airborne gamma spectrometer survey was undertaken by SDAG WISMUT which was directed at the detection of further uranium mineralization in Saxony and Thuringia. Anomalies outlined along the Elbe river near the existing Koenigstein uranium mine were attributed to one or a combination of the following causes: radioactive residues from uranium processing facilities located upstream, temporary accumulation of Rn-decay products attached to dust particles in the atmosphere at the time of the survey, and radioactive waters emerging from uraniferous rocks along tectonic structures. In 1994, WISMUT GmbH re-evaluated the survey to determine the need for implementing cleanup measures. Subsequent to the verification of the original airborne data, ground surveys were undertaken that included gamma spectrometry, percussion probing and river sediment sampling. The new results did not confirm the magnitude of most of the 1982 airborne anomalies. The general decline of the radioactivity pointed out by the 1994 ground measurements is interpreted to be a result of the partial erosion and dilution of radionuclides in fluvial sediments as well as burial by additional river sediments since. Additional anomalous copper and zinc concentrations are attributed to sources other than mining. The ground follow-up delineated a new anomalous zone that is caused by radionuclides discharged with treated process and mine water. It is the only area, which may require further investigations and possible remedial action. (author)

  7. Gamma rays as probes of the Universe

    Science.gov (United States)

    Horns, Dieter; Jacholkowska, Agnieszka

    2016-06-01

    The propagation of γ rays over very large distances provides new insights on the intergalactic medium and on fundamental physics. On their path to the Earth, γ 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 γ 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 γ-ray bursts and of flaring active galactic nuclei, lower bounds have been set on the energy scale of Quantum Gravity. Another effect that may alter γ-ray propagation is predicted by some models of String Theory, namely the mixing of the γ ray with a light fundamental boson called an "axion-like particle", which does not interact with low-energy photons. Such a mixing would make the Universe more transparent to γ rays than what would otherwise be, in a sense it decreases the amount of modification to the spectrum that comes from the extragalactic background light. The present status of the search for all these phenomena in γ-ray astronomy is reviewed. xml:lang="fr"

  8. Very high energy gamma ray astrophysics

    International Nuclear Information System (INIS)

    Our scientific goal is to discover and study by means of gamma-ray astronomy those regions of the universe where particles are accelerated to extreme energies. The atmospheric Cherenkov technique provides a unique and potentially sensitive window in the region of 1011 to approximately 1014 eV for this purpose. The Whipple Observatory Collaboration is currently engaged in the development of a Cherenkov camera which has the ultimate capability of distinguishing gamma-ray showers from the numerous cosmic-ray background showers by imaging the Cherenkov light from each shower. We have recently demonstrated the potential of the imaging technique with our 18 sigma detection of TeV photons from the Crab Nebula using a camera of 10 elements, pixel spacing 0.25 degrees. This detection represents a factor of 10 improvement in sensitivity compared to a non-imaging detector. The next step in the development of the detector is to obtain a second large reflector, similar to the present 10 meter instrument, for stereoscopic viewing of showers. This project, named GRANITE, is now approved by DOE. With GRANITE it should be possible to probe more deeply in space by a factor of 7, and to fully investigate the possibility of new physics which has been suggested by reports of anomalous radiation from Hercules X-1. 18 refs

  9. 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.

  10. Very high energy gamma ray astrophysics

    Energy Technology Data Exchange (ETDEWEB)

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

    1992-02-01

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

  11. Gamma-Ray Bursts and Cosmology

    Science.gov (United States)

    Norris, Jay P.

    2003-01-01

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

  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. 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.

  14. The short gamma-ray burst revolution

    International Nuclear Information System (INIS)

    Swift, a dedicated gamma-ray burst (GRB) satellite with ultrarapid slewing capability, and a suite of ground-based (ESO) telescopes have recently achieved a major breakthrough: detecting the first afterglows of short-duration GRBs. The faintness of these afterglows and the diversity of old and young host galaxies lend support to the emerging 'standard model', in which they are created during the merging of two compact objects. However, the afterglow light-curve properties and possible high-redshift origin of some short bursts suggests that more than one progenitor type may be involved. (orig.)

  15. Gamma Ray Signatures from Ordinary Cosmic Strings

    OpenAIRE

    MacGibbon, Jane H.; Brandenberger, Robert H.

    1992-01-01

    We calculate the flux of ultra high energy photons from individual ordinary (i.e. non-superconducting) cosmic strings and compare the results with the sensitivity of current and proposed TeV and EeV telescopes. Our calculations give only upper limits for the gamma ray flux, since the source of the photons, jets from particle production at cusps, may be weakened by back reaction effects. For the usual cosmic distribution of strings, the predicted bursts from strings with the value of mass per ...

  16. Classification of Fermi Gamma-RAY Bursts

    CERN Document Server

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

    2015-01-01

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

  17. The Birthplaces of Gamma-Ray Bursts

    CERN Document Server

    Young, P A; Young, Patrick A.

    2007-01-01

    We use population synthesis to construct distributions of gamma-ray bursts (GRBs) for different proposed progenitor models. We use a description of star formation that takes into account the evolution of metallicity with redshift and galaxy mass, the evolution of galaxy mass with redshift, and the star formation rate with galaxy mass and redshift. We compare predicted distributions with redshift and metallicity to observations of GRB host galaxies and find that the the simple models cannot produce the observed distributions, but that current theoretical models can reproduce the observations within some constraints on the fraction of fallback black holes that produce GRBs.

  18. Are Gamma-ray Bursts Universal?

    OpenAIRE

    Eichler, David; Levinson, Amir

    2006-01-01

    It is noted that the Liang-Zhang correlation can be accounted for with the viewing angle interpretation proposed earlier. The Ghirlanda correlation, recently generalized by Nava et al (2006) to a wind profile, can be accounted for by the viewing angle interpretation accordingly generalized to a wind profile. Most of the scatter in the spectra and time-integrated brightness in $\\gamma$-ray bursts (GRB) can thus be accounted for by variation in two parameters, 1) the viewing angle and 2) the je...

  19. Gamma Ray Shielding from Saudi White Sand

    OpenAIRE

    Al-horayess OKLA; Al-Dayel OMAR; Hefne JAMEEL; Al-Ajyan TURKI; Bagazi ALI

    2010-01-01

    This study is a comparison of gamma ray linear attenuation coefficient of two typs of shielding materials made of Saudi white and red sand. Each shield was consisted of one part of cement two parts of sand in addi-tion to water. Different thicknesses were tested. The concentrations of all elements in each shield material were determined by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The results obtained from the ICP-MS were used in MCNP4B (Monte Carlo N-Particle Transport Computer ...

  20. 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...

  1. Gamma ray bursts observed with WATCH‐EURECA

    DEFF Research Database (Denmark)

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

    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...

  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. Improved Gamma-Ray Flux Monitoring at the High Intensity Gamma-Ray Source (HIGS)

    Science.gov (United States)

    Reynolds, Robert

    2002-10-01

    An improved gamma-ray beam flux monitor has been built for use at the High Intensity Gamma-Ray Source at the Duke University Free Electron Laser Laboratories. It is important to know precisely the gamma-ray flux of this beam. It is also important to limit beam attenuation to a minimum while making an accurate flux measurement. The improvements from a more accurate gamma-ray intensity monitor will allow for more precise cross-section measurements and will be valuable to many of the experiments conducted at HIGS. The detector consists of a thin scintillator optically coupled to two photomultiplier tubes, a thin foil, and then another thin scintillator attached to two photomultiplier tubes. The front scintillator is used to veto counts from charged particles emitted upstream in the beam-line. The preliminary tests of the monitor show very promising results and after slight adjustments and calibrations, the detector will be ready to acquire accurate beam intensity measurements while contributing very little to beam attenuation.

  5. 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.

  6. 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.

  7. Fermi GBM Observations of Terrestrial Gamma-Ray Flashes

    Science.gov (United States)

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

    2010-01-01

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

  8. Gamma Rays from Top-Mediated Dark Matter Annihilations

    OpenAIRE

    Jackson, C.B.(Department of Physics, University of Texas at Arlington, Arlington, TX 76019, USA); Servant, Géraldine; Shaughnessy, Gabe; Tim M.P. Tait; Taoso, Marco

    2013-01-01

    Lines in the energy spectrum of gamma rays are a fascinating experimental signal, which are often considered "smoking gun" evidence of dark matter annihilation. The current generation of gamma ray observatories are currently closing in on parameter space of great interest in the context of dark matter which is a thermal relic. We consider theories in which the dark matter's primary connection to the Standard Model is via the top quark, realizing strong gamma ray lines consistent with a therma...

  9. 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.

  10. 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

  11. ICF gamma-ray reaction history diagnostics

    International Nuclear Information System (INIS)

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

  12. 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...

  13. 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...

  14. Gamma-ray burst interaction with dense interstellar medium

    OpenAIRE

    Barkov, Maxim; Bisnovatyi-Kogan, Gennady

    2004-01-01

    Interaction of cosmological gamma ray burst radiation with the dense interstellar medium of host galaxy is considered. Gas dynamical motion of interstellar medium driven by gamma ray burst is investigated in 2D approximation for different initial density distributions of host galaxy matter and different total energy of gamma ray burst. The maximum velocity of motion of interstellar medium is $1.8\\cdot10^4$ km/s. Light curves of gamma ray burst afterglow are calculated for set of non homogeneo...

  15. High energy gamma ray telescope using a cargo airplane

    International Nuclear Information System (INIS)

    A new method to measure high energy gamma rays from astronomical objects is presented. In this method, we use commercial cargo airplanes to get the altitude near the air shower maximum. Gamma rays with the energy greater than 100 GeV can be detected by the lead-glass based detector. Directions of gamma rays are determined by those of the secondary electrons (positrons) in the showers. The angular resolution obtained by this method is considered to be better than 1 degree. The detector is sensitive to the gamma ray point sources. (author)

  16. Gamma-ray spectroscopy on irradiated fuel rods

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

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

  18. Basic properties of Gamma-ray loud blazars

    OpenAIRE

    Cheng, K. S.; Fan, J.H.; Zhang, L.

    1999-01-01

    In this paper, a method is proposed to determine the basic properties of $\\gamma$-ray loud blazars, among them the central black hole mass, M, the Doppler factor, $\\delta$, the propagation angle of the $\\gamma$-rays with respect to the symmetric axis of a two-temperature accretion disk, $\\Phi$, and the distance (i.e. the height above the accretion disk), d at which the $\\gamma$-rays are created, for seven $\\gamma$-ray loud blazars with available GeV variability timescales and in which the abs...

  19. The Radio and Gamma-Ray Luminosities of Blazars

    OpenAIRE

    Zhang, L.; Cheng, K. S.; Fan, J.H.

    2001-01-01

    Based on the $\\gamma$-ray data of blazars in the third EGRET catalog and radio data at 5 GHz, we studied the correlation between the radio and $\\gamma$-ray luminosities using two statistical methods. The first method was the partial correlation analysis method, which indicates that there exist correlations between the radio and $\\gamma$-ray luminosities in both high and low states as well as in the average case. The second method involved a comparison of expected $\\gamma$-ray luminosity distr...

  20. Gamma ray tests of Minimal Dark Matter

    International Nuclear Information System (INIS)

    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

  1. Verifiability of Gamma ray Spectrometric results

    International Nuclear Information System (INIS)

    Full text: With the adoption of the EU legislative the introduction of a quality assurance system and application of quality control procedures become mandatory for testing laboratories. The standard describing the requirements for these laboratories is the ISO 17025 standard. Regarding the service to the client the standard requests cooperation in monitoring the laboratory's performance. The client's confidence in measurement results is especially important in measurements of radioactivity since alternative measurement methods can be very expensive. Therefore the concept of verifiability, i.e. the property of the results, which enables the client to assess their reliability, is implemented. Verifiability is implemented by reporting the activity of 40K and the concentration of potassium in the sample. 40K emits gamma rays and its activity in the sample is determined simultaneously with the activities of other photon emitters. Since the isotopic composition of potassium is constant, the activity of 40K is proportional to the concentration of potassium in the sample, which can be measured chemically. In this way we enable the client to assess the reliability of our measurement of 40K by chemical methods. Disagreement in the potassium concentrations results would cause doubts in the reliability of other results obtained by gamma-ray spectrometry and would result in an assessment of the sample preparation and measurement procedure.(author)

  2. 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...

  3. Structured jets in gamma ray bursts

    International Nuclear Information System (INIS)

    The gamma ray bursts (GRBs) are some of the most powerful explosions in the Universe. Observationally, they are short and very intense pulses of photons in the keV-MeV range. The paradigm is that the gamma rays are emitted at cosmological distances when an ultra-relativistic energy flow is converted to radiation in an optically thin region. Evidence suggests that many of the GRBs originate from the relativistically moving matter beamed in the form of a conical jet. Probably, these jets are not uniform, but rather structured, the energy being distributed with internal angle as some function dependent on the angle between the jet symmetry axis and an arbitrary direction within the jet. Here we investigate the case in which the bulk Lorentz factor of the ejecta varies as a power-law with respect to the axis of the jet. Using a simple kinematical model, under certain assumptions, we can constraint the values of the power-law index. Also, we briefly discuss some important consequences of the jetted GRBs concept in the context of the general understanding of the phenomenon. (authors)

  4. 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...

  5. 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.

  6. 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...

  7. X- and gamma-ray signatures of type Ia supernovae

    International Nuclear Information System (INIS)

    Using a Monte Carlo code, the hard X-ray continuum and gamma-ray line emissions of various theoretical models of Type Ia supernova explosions are investigated. The influence of the distributions of velocity, mass, Ni-56, and heavy elements on the spectral and temporal evolution of the radiations (ultimately derived from the positrons and gamma-ray lines of the decay chain) is described. For the first 300-400 days of the explosion, the correspondence between the parameters of an explosion model and its hard photon signatures is derived. The effect of mixing instabilities is also studied, and estimates of the future detectability of the derived hard X- and gamma-ray features are presented. It is found that OSEE on the Gamma-Ray Observatory can detect both gamma-ray lines and the hard X-ray continuum from any Type Ia supernova within 10 Mpc of earth. 52 refs

  8. High dose gamma-ray standard

    International Nuclear Information System (INIS)

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

  9. Activation of wine bentonite with gamma rays

    International Nuclear Information System (INIS)

    The action of gamma rays on wine bentonite as well as influence of its adsorption and technologic qualities on the composition and stability of wines against protein darkening and precipitation has been studied. The experiments were carried out with wine bentonite produced in the firm Bentonite and irradiated with doses of 0.4, 0.6, 0.8 and 1.0 MR. White and red wines have been treated with irradiated bentonite under laboratory conditions at 1.0 g/dm3. All samples are treated at the same conditions. The flocculation rate of the sediment was determined visually. Samples have been taken 24 h later from the cleared wine layers. The following parameters have been determined: clarification, filtration rate, phenolic compounds, calcium, colour intensity, total extracted substances, etc. The volume of the sediment has been determined also. The control samples have been taken from the same unirradiated wines. The results showed better and faster clarification in on the third, the 20th and the 24th hours with using of gamma-irradiated at doses 0.8 and 1.0 MR. The sediment was the most compact and its volume - the smallest compared to the samples treated with bentonite irradiated with doses of 0.6 and 0.4 MR. This ensures a faster clarification and better filtration of treated wines. The bentonite activated with doses of 0.8 and 1.0 MR adsorbs the phenolic compounds and the complex protein-phenolic molecules better. In the same time it adsorbs less extracted substances compared to untreated bentonite and so preserves all organoleptic properties of wine. The irradiated bentonite adsorbs less the monomers of anthocyan compounds which ensures brighter natural colour of wine. The gamma-rays activation consolidates calcium in the crystal lattice of bentonite particles and in this way eliminates the formation of crystal precipitates

  10. 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).

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

    International Nuclear Information System (INIS)

    The X-ray/gamma-ray spectrometer (XGRS) instrument onboard the Near Earth Asteroid Rendezvous (NEAR) spacecraft will map asteroid 433 Eros in the 0.2 keV to 10 MeV energy region. Measurements of the discrete line X-ray and gamma-ray emissions in this energy domain can be used to obtain both qualitative and quantitative elemental composition maps of the asteroid surface. The NEAR X-ray/gamma-ray spectrometer (XGRS) was turned on for the first time during the week of 7 April 1996. Rendezvous with Eros 433 is expected during December 1998. Observations of solar X-ray spectra during both quiescent and active periods have been made. A gamma-ray transient detection system has been implemented and about three gamma-ray transient events a week have been observed which are associated with either gamma-ray bursts or solar flares

  12. The Most Remote Gamma-Ray Burst

    Science.gov (United States)

    2000-10-01

    ESO Telescopes Observe "Lightning" in the Young Universe Summary Observations with telescopes at the ESO La Silla and Paranal observatories (Chile) have enabled an international team of astronomers [1] to measure the distance of a "gamma-ray burst", an extremely violent, cosmic explosion of still unknown physical origin. It turns out to be the most remote gamma-ray burst ever observed . The exceedingly powerful flash of light from this event was emitted when the Universe was very young, less than about 1,500 million years old, or only 10% of its present age. Travelling with the speed of light (300,000 km/sec) during 11,000 million years or more, the signal finally reached the Earth on January 31, 2000. The brightness of the exploding object was enormous, at least 1,000,000,000,000 times that of our Sun, or thousands of times that of the explosion of a single, heavy star (a "supernova"). The ESO Very Large Telescope (VLT) was also involved in trail-blazing observations of another gamma-ray burst in May 1999, cf. ESO PR 08/99. PR Photo 28a/00 : Sky field near GRB 000131 . PR Photo 28b/00 : The fading optical counterpart of GRB 000131 . PR Photo 28c/00 : VLT spectrum of GRB 000131 . What are Gamma-Ray Bursts? One of the currently most active fields of astrophysics is the study of the mysterious events known as "gamma-ray bursts" . They were first detected in the late 1960's by instruments on orbiting satellites. These short flashes of energetic gamma-rays last from less than a second to several minutes. Despite much effort, it is only within the last few years that it has become possible to locate the sites of some of these events (e.g. with the Beppo-Sax satellite ). Since the beginning of 1997, astronomers have identified about twenty optical sources in the sky that are associated with gamma-ray bursts. They have been found to be situated at extremely large (i.e., "cosmological") distances. This implies that the energy release during a gamma-ray burst within a few

  13. The use of gamma ray data to define the natural radiation environment

    International Nuclear Information System (INIS)

    The natural radiation environment is the major source of radiation exposure to man and consists of both internal and external sources. The most significant internal sources are the radioactive elements 40K and 222Rn which are taken into the body. The external sources are cosmic rays and naturally occurring radioactive isotopes of the 40K, 238U, and 232Th decay series, some or all of which can be found in the ground, in construction materials, and in the air. This report has been prepared to provide a guide for the use of existing gamma ray survey data to define the natural radiation environment, but will only be concerned with the gamma ray exposure resulting from radiation originating in geological materials. The type of data needed to produce maps are available as a result of airborne, carborne, and ground gamma ray surveys in many parts of the world. Although most of these data were acquired for uranium and other mineral exploration and geological mapping purposes, they can be used to provide background radioactivity information. Standardized survey data can be compiled to produce regional maps of gamma ray air dose rates as well as single radioelement maps. Compilation procedures may use either manual or computer techniques. Although this work will primarily be done as national compilations, it will open the possibility of the compilation of radioelement geochemical maps on a regional and global scale. 48 refs, figs and tabs

  14. ICI detector for measuring gamma-ray fluxes in mixed gamma-neutron fields

    International Nuclear Information System (INIS)

    A new gamma-ray detecting device called ICI (Insulator-conductor-insulator) detector has been developed and tested. Like vacuum Compton diode (VCD) and dielectric Compton diode (DCD) generally used in pulsed gamma-ray measurements, ICI detector operates by utilization of the Compton effect and has low sensitivity to gamma-ray fluxes, very fast time response, large linearity and wide dynamic range, it is desired for using the device to measure intense and rapidly changing gamma-ray fluxes. Compared to the existing VCDs and DCDs, the detector requires no vacuum in operation and the active volume is only 2 mm thick. (authors)

  15. Comparison of airborne and terrestrial gamma spectrometry measurements - evaluation of three areas in southern Sweden

    International Nuclear Information System (INIS)

    The Geological Survey of Sweden (SGU) has been conducting airborne gamma spectrometry measurements of natural radioactivity in Sweden for more than 40 years. Today, the database covers about 80% of the country's land surface. This article explores the first step of putting this data into use in radioactive source search at ground level. However, in order to be able to use the airborne background measurements at ground level, SGU data must be validated against terrestrial data. In this work, we compare the SGU data with data measured by a portable backpack system. This is done for three different areas in southern Sweden. The statistical analysis shows that a linear relationship and a positive correlation exist between the air and ground data. However, this linear relationship could be revealed only when the region possessed large enough variations in areal activity. Furthermore, the activity distributions measured show good agreement to those of SGU. We conclude that the SGU database could be used for terrestrial background assessment, given that a linear transfer function is established. - Highlights: → Correlation between ground and air measurements depends on activity variability. → Linear ground-to-air relationship exist given large enough activity variability. → Ground-to-air comparisons through activity distribution functions feasible. → Airborne data can be part of a prognostic tool in search operations on ground.

  16. Discoveries by the Fermi Gamma Ray Space Telescope

    Science.gov (United States)

    Gehrels, Neil

    2011-01-01

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

  17. 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.

  18. VHE gamma-ray observations of Markarian 501

    OpenAIRE

    Whipple Collaboration; Breslin, A. C.; Bond, I. H.; Bradbury, S. M.; J. H. Buckley(Department of Physics, Washington University, St. Louis, USA); 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.

    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...

  19. 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.

  20. Significance of medium energy gamma ray astronomy in the study of cosmic rays

    Science.gov (United States)

    Fichtel, C. E.; Kniffen, D. A.; Thompson, D. J.; Bignami, G. F.; Cheung, C. Y.

    1975-01-01

    Medium energy (about 10 to 30 MeV) gamma ray astronomy provides information on the product of the galactic electron cosmic ray intensity and the galactic matter to which the electrons are dynamically coupled by the magnetic field. Because high energy (greater than 100 MeV) gamma ray astronomy provides analogous information for the nucleonic cosmic rays and the relevant matter, a comparison between high energy and medium energy gamma ray intensities provides a direct ratio of the cosmic ray electrons and nucleons throughout the galaxy. A calculation of gamma ray production by electron bremsstrahlung shows that: bremsstrahlung energy loss is probably not negligible over the lifetime of the electrons in the galaxy; and the approximate bremsstrahlung calculation often used previously overestimates the gamma ray intensity by about a factor of two. As a specific example, expected medium energy gamma ray intensities are calculated for the speral arm model.

  1. Gamma-ray remote sensing of soil properties in a forested area near Batlow, NSW

    International Nuclear Information System (INIS)

    In forested and agricultural areas, reflective remote sensing methods are of limited utility for soil studies due to the variable effects of vegetation. Airborne gamma-ray remote sensing is presented here as a useful technique for soils. Short wavelength gamma-rays are detected from the upper 0.30-0.45 m of the soil . They are emitted from radioactive elements in the soil and largely pass through vegetation cover. In this paper, images of gamma parent elements (K, Th and U) are presented and element associations with soil properties and vegetation are analysed for a forested area near Batlow, NSW. Effects of vegetation are evident in gamma-ray data and in Landsat TM along powerlines and in clearings. A technique for removing this effect in the gamma-ray data is demonstrated. Detailed soil and rock chemistry together with ground gamma-spectrometer measurements were collected to support the interpretation and analysis of the image data. The work focuses mainly on the variation of soil properties within areas mapped as granodiorite lithology. Many areas of deep red soils are accurately mapped by the radiometric K data. The precise origin of these soils is not clear and their parent materials may include contributions from aeolian deposition, in situ weathering of granodiorite, and remnant basalt. . In areas of granodiorite, K patterns are interpreted to be a function of the degree of mineral weathering and can be related to soil depth and erosion status. This study demonstrates the effectiveness of gamma-ray remote sensing for directly mapping soil units and properties (authors). Copyright (1998) Remote Sensing and Photogrammetry Association of Australasia Ltd

  2. 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...

  3. Observed Gamma Ray Radiation Variations Associated with Tropical Zone Rainfall Events

    Science.gov (United States)

    Spjeldvik, W. N.; Martin, I. M.; Gusev, A. A.

    2014-12-01

    Major liquid precipitation events are associated with changes in measurable natural nuclear radiation at ground level. We have observed that gamma radiation from airborne constituents varies with weather conditions, especially rainfall events, as observed with ground level instrumentation at near tropical zone low latitudes. Simultaneous observations of natural gamma ray emissions at the ground level and tropical zone rainfall variation observations have been performed in Sao Jose dos Campos, Sao Paulo, Brazil with temporal resolution accuracy of the order of one minute. This has allowed a detailed comparison of rainfall amounts and monitored gamma ray emission time profiles to estimate the actual radionuclide concentration in the rainwater. The radionuclide fallout time profiles were numerically simulated from the observed gamma rate through a numerical minimization procedure. The radionuclide concentration was calculated as a ratio of the simulated fallout to that of the observed rainfall amounts. Our result shows an anti-correlation between the average values of these parameters at times. The effect is especially pronounced at rapid rainfall onsets. The results obtained are compared with the current models and data, and the causes are discussed. Future research will study gamma ray radiation versus weather events at ground level in the temporal zone (North America) where the natural background radiation is thought to be generally somewhat lower than at ground level on the South American continent.

  4. The nature of the outflow in gamma-ray bursts

    CERN Document Server

    Kumar, P; Panaitescu, A; Willingale, R; O'Brien, P; Burrows, D; Cummings, J; Gehrels, N; Holland, S; Pandey, S B; Vanden Berk, D E; Zane, S

    2007-01-01

    The Swift satellite has enabled us to follow the evolution of gamma-ray burst (GRB) fireballs from the prompt gamma-ray emission to the afterglow phase. The early x-ray and optical data obtained by telescopes aboard the Swift satellite show that the source for prompt gamma-ray emission, the emission that heralds these bursts, is short lived and that its source is distinct from that of the ensuing, long-lived afterglow. Using these data, we determine the distance of the gamma-ray source from the center of the explosion. We find this distance to be 1e15-1e16 cm for most bursts and we show that this is within a factor of ten of the radius of the shock-heated circumstellar medium (CSM) producing the x-ray photons. Furthermore, using the early gamma-ray, x-ray and optical data, we show that the prompt gamma-ray emission cannot be produced in internal shocks, nor can it be produced in the external shock; in a more general sense gamma-ray generation mechanisms based on shock physics have problems explaining the GRB ...

  5. Models of X-ray and gamma-ray emission from Seyfert galaxies

    OpenAIRE

    Svensson, Roland

    1996-01-01

    X-ray and gamma-ray observations of Seyfert 1 galaxies are briefly reviewed. Both thermal and non-thermal model for X-ray and gamma-ray emission are discussed. Particular attention is given to various disc-corona models including both homogeneous and inhomogeneous (patchy) corona models. Recent work on exact radiative transfer in such geometries are reviewed.

  6. Super Luminous Supernova and Gamma Ray Bursts

    CERN Document Server

    Dado, Shlomo

    2012-01-01

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

  7. 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.

  8. Gamma-Ray Bursts as Cosmological Tools

    CERN Document Server

    Petrosian, Vahe; Ryde, Felix

    2009-01-01

    In recent years there has been considerable activity in using gamma-ray bursts as cosmological probes for determining global cosmological parameters complementing results from type Ia supernovae and other methods. This requires a characteristics of the source to be a standard candle. We show that contrary to earlier indications the accumulated data speak against this possibility. Another method would be to use correlation between a distance dependent and a distance independent variable to measure distance and determine cosmological parameters as is done using Cepheid variables and to some extent Type Ia supernovae. Many papers have dealt with the use of so called Amati relation, first predicted by Lloyd, Petrosian and Mallozzi, or the Ghirlanda relation for this purpose. We have argued that these procedure involve many unjustified assumptions which if not true could invalidate the results. In particular, we point out that many evolutionary effects can affect the final outcome. In particular, we demonstrate th...

  9. 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.

  10. The Supernova -- Gamma-Ray Burst Connection

    CERN Document Server

    Woosley, S E

    2006-01-01

    Observations show that at least some gamma-ray bursts (GRBs) happen simultaneously with core-collapse supernovae (SNe), thus linking by a common thread nature's two grandest explosions. We review here the growing evidence for and theoretical implications of this association, and conclude that most long-duration soft-spectrum GRBs are accompanied by massive stellar explosions (GRB-SNe). The kinetic energy and luminosity of well-studied GRB-SNe appear to be greater than those of ordinary SNe, but evidence exists, even in a limited sample, for considerable diversity. The existing sample also suggests that most of the energy in the explosion is contained in nonrelativistic ejecta (producing the supernova) rather than in the relativistic jets responsible for making the burst and its afterglow. Neither all SNe, nor even all SNe of Type Ibc produce GRBs. The degree of differential rotation in the collapsing iron core of massive stars when they die may be what makes the difference.

  11. Hand-held high resolution gamma ray spectrometer

    International Nuclear Information System (INIS)

    A fully portable and a semi-portable high resolution gamma spectrometer are described. These instruments have the resolving capabilities that are inherent to germanium spectrometers and have the portability needed for health physics. The instruments are usable as a gamma-ray or x-ray fluorescence spectrometer

  12. Observational techniques of gamma rays astronomy in low energy

    International Nuclear Information System (INIS)

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

  13. A {sup 16}N gamma-ray facility

    Energy Technology Data Exchange (ETDEWEB)

    Hull, E.L. [Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Pehl, R.H. [Lawrence Berkeley Lab., CA (United States); Stanley, M.R. [Clemson Univ., SC (United States); Foster, C.C. [Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Komisarcik, K. [Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; East, G.W. [Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Vanderwerp, J.D. [Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Friesel, D.L. [Indiana Univ., Bloomington, IN (United States). Cyclotron Facility

    1997-02-01

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

  14. 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)

  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. 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.

  17. Gamma ray irradiation for sludge solubilization and biological nitrogen removal

    International Nuclear Information System (INIS)

    This study was conducted to investigate the effects of gamma ray irradiation on the solubilization of waste sewage sludge. The recovery of an organic carbon source from sewage sludge by gamma ray irradiation was also studied. The gamma ray irradiation showed effective sludge solubilization efficiencies. Both soluble chemical oxygen demand (SCOD) and biochemical oxygen demand (BOD5) increased by gamma ray irradiation. The feasibility of the solubilized sludge carbon source for a biological nitrogen removal was also investigated. A modified continuous bioreactor (MLE process) for a denitrification was operated for 20 days by using synthetic wastewater. It can be concluded that the gamma ray irradiation was useful for the solubilization of sludge and the recovery of carbon source from the waste sewage sludge for biological nitrogen removal. - Research highlights: → This study was conducted to investigate the effects of gamma ray irradiation on the solubilization of waste sewagesludge. → The recovery of an organic carbon source from sewage sludge by gamma ray irradiation was also studied. → It can be concluded that the gamma ray irradiation was useful for the solubilization of sludge and the recovery of carbon source from the waste sewage sludge for biological nitrogen removal.

  18. Gamma ray induced somatic mutations in rose

    International Nuclear Information System (INIS)

    Budwood of 32 rose cultivars (Rosa spp.) was exposed to 3-4 krad of gamma rays and eyes were grafted on Rosa indica var. odorata root stock. Radiosensitivity with respect to sprouting, survival and plant height, and mutation frequency varied with the cultivar and dose of gamma rays. Somatic mutations in flower colour/shape were detected as chimera in 21 cultivars. The size of the mutant sector varied from a narrow streak on a petal to a whole flower and from a portion of a branch to an entire branch. 14 mutants were detected in M1V1, four in M1V2 and three in M1V3. Maximum number of mutations was detected following 3 krad treatment. Eyes from mutant branches were grafted again on root stock and non-chimeric mutants were aimed at by vegetative propagation. Mutants from 11 cultivars only could be isolated in pure form. Isolation of non-chimeric mutants sometimes is difficult due to weak growth of a mutant branch. In such a case, all normal looking branches are removed to force a better growth of the mutant branch. It is advisable to maintain irradiated plants at least for four years with drastic pruning in each year. Nine mutants viz. 'Sharada', 'Sukumari', 'Tangerine Contempo', 'Yellow Contempo', 'Pink Contempo', 'Striped Contempo', 'Twinkle', 'Curio' and 'Light Pink Prize' have already been released as new cultivars for commercialization [ref. MBNL No. 23 and 31] and others are being multiplied and assessed. The mutation spectrum appears to be wider for the cultivars 'Contempo' and 'Imperator'. Pigment composition of the original variety is relevant for the kind of flower colour mutations that can be induced

  19. Gamma ray analysis of multi-component material

    International Nuclear Information System (INIS)

    A method and apparatus is disclosed for analyzing a multi-component material having at least three components using gamma radiation having at least two different energies. Upon irradiation of at least a sample of material, the multi-energy gamma rays which are propagated through the sample are detected. The intensity of the detected gamma rays is measured and the amount of at least one of the components of the material is determined by solving a set of simultaneous equations. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-11

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

  1. Muon Detection of TeV $\\gamma$ Rays from $\\gamma$ Ray Bursts

    CERN Document Server

    Alvarez-Muñiz, J

    1999-01-01

    Because of the limited size of the satellite-borne instruments, it has not been possible to observe the flux of gamma ray bursts (GRB) beyond GeV energy. We here show that it is possible to detect the GRB radiation of TeV energy and above, by detecting the muon secondaries produced when the gamma rays shower in the Earth's atmosphere. Observation is made possible by the recent commissioning of underground detectors (AMANDA, the Lake Baikal detector and MILAGRO) which combine a low muon threshold of a few hundred GeV or less, with a large effective area of 10^3 m^2 or more. Observations will not only provide new insights in the origin and characteristics of GRB, they also provide quantitative information on the diffuse infrared background.

  2. 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.

  3. 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. PMID:23630379

  4. Solar gamma-ray lines and interplanetary solar protons

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimori, M.

    1985-03-01

    Solar gamma-ray lines and protons were simultaneously observed for six flares on April 1, 4, and 27, 1981, May 13, 1981, February 1, 1982, and June 6, 1982 by the Hinotori and Himawari satellites. The flare list is presented, and the time histories of gamma-rays and protons are shown. The relationship between the gamma-ray line fluences and peak proton fluxes for these flares does not reveal an apparent correlation between them. The present results imply that the protons producing gamma-ray lines in the flare region, and protons observed near the earth, do not always belong to the same population, and favor the downward streaming model for the gamma-ray line production. 15 references.

  5. Solar gamma-ray lines and interplanetary solar protons

    Science.gov (United States)

    Yoshimori, M.

    1985-03-01

    Solar gamma-ray lines and protons were simultaneously observed for six flares on April 1, 4, and 27, 1981, May 13, 1981, February 1, 1982, and June 6, 1982 by the Hinotori and Himawari satellites. The flare list is presented, and the time histories of gamma-rays and protons are shown. The relationship between the gamma-ray line fluences and peak proton fluxes for these flares does not reveal an apparent correlation between them. The present results imply that the protons producing gamma-ray lines in the flare region, and protons observed near the earth, do not always belong to the same population, and favor the downward streaming model for the gamma-ray line production.

  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. Contribution of a germanium detector in mobile gamma-ray spectrometry. Spectral analysis and performance

    CERN Document Server

    Gutierrez, S; Bourgeois, C

    2002-01-01

    The sensitivity of the germanium semi-conductor detector is 30 times lower than that of the sodium iodide (NaI) detectors frequently used in airborne spectrometry. Its energy resolution however, is 20 times better, giving more accurate identification of radionuclides, especially when complex spectra are involved. The use of the germanium detector in mobile gamma-ray spectrometry provides a large amount of qualitative and quantitative information. In post-accident situations a germanium detector will be sufficient, and should therefore be used in preference to a NaI detector. An algorithm for detecting the total absorption peaks by studying the variations in the spectral profile of germanium gamma-ray spectra has been developed at the CEA. The use of digital filters that take into account the characteristics of the absorption peaks reduces the statistical fluctuations, making possible detection based on the analysis of the first and second derivatives. The absorption peak is then estimated by subtracting the b...

  8. A carbon survey for the evaluation of diminution of terrestrial gamma ray due to snow cover

    International Nuclear Information System (INIS)

    The experiment was carried out to evaluate diminution of terrestrial gamma rays due to snow cover, in Nagaoka city, Niigata prefecture, in 1987, using a helicopter and a monitoring car. The measurement were performed in autumn before snowfall and in winter. From the measurements over wide areas in and around Nagaoka city, penetration ratios (ratios of terrestrial gamma ray doses on snow covered ground to those on snow free ground) were found to be small in the center of the city but high in the suburbs. Water equivalents were calculated by penetration ratios derived from measured data by airborne survey and carborne survey. The calculated snow equivalents were compared with a published snow depth. The former was 20-30% smaller than the latter with a wide of courses in and around Nagaoka city. (author)

  9. Effect of gamma ray irradiation on sodium borate single crystals

    Science.gov (United States)

    Kalidasan, M.; Asokan, K.; Baskar, K.; Dhanasekaran, R.

    2015-12-01

    In this work, the effects of 5 kGy, 10 kGy and 20 kGy doses of gamma ray irradiation on sodium borate, Na2[B4O5(OH)4]·(H2O)8 single crystals have been studied. Initially these crystals were grown by solution growth technique and identified as monoclinic using X-ray diffraction analysis. X-ray rocking curves confirm the formation of crystalline defects due to gamma rays in sodium borate single crystals. The electron paramagnetic resonance spectra have been recorded to identify the radicals created due to gamma ray irradiation in sodium borate single crystals. The thermoluminescence glow curves due to the defects created by gamma rays in this crystal have been observed and their kinetic parameters were calculated using Chen's peak shape method. The optical absorption increases and photoluminescence spectral intensity decreases for 5 kGy and 20 kGy doses gamma ray irradiated crystals compared to pristine and 10 kGy dose irradiated one. The effect of various doses of gamma rays on vibrational modes of the sodium borate single crystals was studied using FT-Raman and ATR-FTIR spectral analysis. The dielectric permittivity, conductance and dielectric loss versus frequency graphs of these crystals have been analyzed to know the effect of gamma ray irradiation on these parameters.

  10. Search for Sub-TeV Gamma Rays Coincident with BATSE Gamma Ray Bursts

    CERN Document Server

    Poirier, J; Gress, J; Race, D

    2003-01-01

    Project GRAND is a 100m x 100m air shower array of proportional wire chambers (PWCs). There are 64 stations each with eight 1.29 m^2 PWC planes arranged in four orthogonal pairs placed vertically above one another to geometrically measure the angles of charged secondaries. A steel plate above the bottom pair of PWCs differentiates muons (which pass undeflected through the steel) from non-penetrating particles. FLUKA Monte Carlo studies show that a TeV gamma ray striking the atmosphere at normal incidence produces 0.23 muons which reach ground level where their angles and identities are measured. Thus, paradoxically, secondary muons are used as a signature for gamma ray primaries. The data are examined for possible angular and time coincidences with eight gamma ray bursts (GRBs) detected by BATSE. Seven of the GRBs were selected because of their good acceptance by GRAND and high BATSE Fluence. The eighth GRB was added due to its possible coincident detection by Milagrito. For each of the eight candidate GRBs, ...

  11. Lunar gamma-ray emission observed by FERMI

    OpenAIRE

    Giglietto, N.; Collaboration, for the Fermi-LAT

    2009-01-01

    FERMI-LAT is performing an all-sky gamma-ray survey from 30 MeV to 300 GeV with unprecedented sensitivity and angular resolution. FERMI has detected high-energy gamma rays from the Moon produced by interactions of cosmic rays with the lunar surface. This radiation was previously observed by EGRET on CGRO with significantly lower statistical significance. We present the lunar analysis for the first six months of the Mission and showing images of the lunar gamma-ray emission. We also compare th...

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

    DEFF Research Database (Denmark)

    Content, Robert; Sharples, Ray; Page, Mathew J.; Cole, Richard; Walton, David M.; Winter, Berend; Pedersen, Kristian; Hjorth, Jens; Andersen, Michael; Hornstrup, Allan; Den Herder, Jan-Willem A.; Piro, Luigi

    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 is...... path 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....

  13. An updated Gamma Ray Bursts Hubble diagram

    CERN Document Server

    Cardone, V F; Dainotti, M G

    2009-01-01

    Gamma ray bursts (GRBs) have recently attracted much attention as a possible way to extend the Hubble diagram to very high redshift. To this aim, the luminosity (or isotropic emitted energy) of a GRB at redshift z must be evaluated from a correlation with a distance independent quantity so that one can then solve for the luminosity distance D_L(z) and hence the distance modulus mu(z). Averaging over five different two parameters correlations and using a fiducial cosmological model to calibrate them, Schaefer (2007) has compiled a sample of 69 GRBs with measured mu(z) which has since then been widely used to constrain cosmological parameters. We update here that sample by many aspects. First, we add a recently found correlation for the X - ray afterglow and use a Bayesian inspired fitting method to calibrate the different GRBs correlations known insofar assuming a fiducial LCDM model in agreement with the recent WMAP5 data. Averaging over six correlations, we end with a new GRBs Hubble diagram comprising 83 ob...

  14. $\\gamma$-Ray Bursts and Related Phenomena

    CERN Document Server

    Piran, T

    1999-01-01

    Gamma-ray bursts (GRBs) have puzzled astronomers since their accidental discovery in the sixties. The BATSE detector on the COMPTON-GRO satellite has been detecting one burst per day for the last six years. Its findings have revolutionized our ideas about the nature of these objects. They have shown that GRBs are at cosmological distances. This idea was accepted with difficulties at first. However, the recent discovery of an x-ray afterglow by the Italian/Dutch satellite BeppoSAX led to a detection of high red-shift absorption lines in the optical afterglow of GRB970508 and to a confirmation of its cosmological origin. The simplest and practically inevitable interpretation of these observations is that GRBs result from the conversion of the kinetic energy of ultra-relativistic particles flux to radiation in an optically thin region. The "inner engine" that accelerates the particles or generates the Poynting flux is hidden from direct observations. Recent studies suggest the ``internal-external'' model: intern...

  15. 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...

  16. 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 $\

  17. Gamma-Ray Bursts 2012 Conference

    Science.gov (United States)

    It is a pleasure to announce the next combined Fermi/Swift GRB conference covering recent advances in all aspects of gamma-ray burst observations and theory. This conference will be held in Munich, Germany, on 7-11 May 2012, and follows similar previous combined Fermi/Swift meetings in Huntsville (Oct. 2008) and Annapolis (Nov. 2010). Gamma-ray bursts are the most energetic explosions in the Universe and are thought to be the birth signatures of black holes. This is an exciting time in the GRB field as various missions provide a wealth of new data on this still puzzling phenomenon. The Fermi misson provides unprecedented spectral coverage over 7 decades in energy, and among others discovered new spectral components which challenge our standard picture of the prompt emission. The Swift mission continuous to swiftly monitor and locate GRBs in multiple wavebands, providing the basis for all ground-based follow-up observations towards redshift measurements and afterglow and host property investigations. AGILE, INTEGRAL, Suzaku and Konus continue to provide crucial information on GRB properties, and the MAXI mission provides an all sky X-ray monitoring of transients. There is also growing capability for follow-up observations by ground-based telescopes at basically all wavelengths. Besides the classical optical/infrared/radio observations, searches are underway for TeV emission, neutrinos and gravitational waves. Moreover, new experiments are expected to have returned first data, among others POGO on the prompt polarization properties, UFFO on very early optical emission, or ALMA on sub-millimeter properties. And last but not least, the unexpected is bringing us child-like astonishments at least once per year with a "GRB-trigger" which turns out to be not related to GRBs. Complementing all these new observational results, a huge theoretical effort is underway to understand the GRB phenomenon and keep up with the constant new puzzles coming from the data. This conference

  18. 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.

  19. 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.

  20. Gamma ray lines from a universal extra dimension

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-03-01

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

  1. 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.

  2. 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)

  3. 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.

  4. Phytonutrient analysis of gamma rays mutated tomato

    International Nuclear Information System (INIS)

    Full text: With increasing of world population and reducing land resources, good quality food production has become even more important. Mutant breeding is an inevitable way for producing of vegetable crops which are sustainable under varied agro-climatic conditions and have high nutrient capacity. The use of nuclear techniques in plant breeding has been mostly directed for inducing mutations. Since the use of ionizing radiation, such as X-rays, gamma rays, e-beam and neutrons for inducing variation, has become an established technology. Induced mutations have been used in the economic value improvement of major crops such as cereals and solanaceae, which are seed propagated. The economic value of a new variety can be assessed from several parameters. From these not only area planted to the variety and percentage of the area under the crop in the region, increased yield and savings in water but also increased nutritive value, and enhanced quality are also very important parameters which should have taken into consideration. Often, induced mutations lead to more advantages than a simple desired phenotypic change.In this study, tomato seeds were irradiated at the dose of 150 Gy by using 60Co gamma rays irradiator at a fixed dose rate of 0.654 kGy/h. These seeds were planted and M4 stage mutant lines were analysed for phytonutrient capacity by using HPLC system with different types of detectors depending on the analytes to be determined (vitamin C, carotenoids and vitamin E). Accelerated Solvent Extraction technique was used for the extraction of vitamin C from the samples under high pressure of nitrogen gas. For carotenoids and tocopherols extractions, liquid-liquid partition technique was used. Photodiode Array, UV and Fluorescence detectors were used for the determination of vitamin C (L-ascorbic acid), some carotenoids (lutein, β-carotene, lycopene) and vitamin E ( α-, γ-, δ tocopherols), respectively. Results obtained from these analysis were found as follows

  5. High energy gamma-ray production in nuclear reactions

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    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

  7. Quantitative determination of alpha-quartz in airborne dust samples by x-ray diffraction

    International Nuclear Information System (INIS)

    The quantitative determination by X-ray diffractometry of alpha-quartz In airborne respirable dust samples on silver membrane filters is considered. A cobalt anode X-ray tube Is employed. NiO is used as Internal standard In order to compensate for both the variations of specimen absorption and the effect due to the nonuniformity of the incident X-ray beam and to the incomplete homogeneity on the filters of samples and standards. (Author) 17 refs

  8. 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.

  9. Investigating Galaxy Clusters through Gamma-ray Emission

    CERN Document Server

    Miniati, F

    2002-01-01

    We address the role of gamma-ray astronomy in the investigation of nonthermal processes in the large scale structure of the universe. Based on EGRET upper limits on nearby galaxy clusters (GCs) we constrain the acceleration efficiency of CR electrons at intergalactic shocks to <=1 % than the shock ram pressure. That implies a contribution to the cosmic gamma-ray background from intergalactic shocks of order 25 % of the measured level. We model spatial and spectral properties of nonthermal gamma-ray emission due to shock accelerated cosmic-rays (CRs) in GCs and emphasize the importance of imaging capability of upcoming gamma-ray facilities for a correct interpretation of the observational results. GC observations at this photon energy will help us understand the origin of the radio emitting particles, the possible level of CR pressure and the strength of magnetic fields in intracluster environment and possibly will allow us detect the accretion shocks.

  10. Investigating Galaxy Clusters through Gamma-ray Emission

    Science.gov (United States)

    Miniati, Francesco

    We address the role of gamma-ray astronomy in the investigation of nonthermal processes in the large scale structure of the universe. Based on EGRET upper limits on nearby galaxy clusters (GCs) we constrain the acceleration efficiency of CR electrons at intergalactic shocks to <=1 % than the shock ram pressure. That implies a contribution to the cosmic gamma-ray background from intergalactic shocks of order 25 % of the measured level. We model spatial and spectral properties of nonthermal gamma-ray emission due to shock accelerated cosmic-rays (CRs) in GCs and emphasize the importance of imaging capability of upcoming gamma-ray facilities for a correct interpretation of the observational results. GC observations at this photon energy will help us understand the origin of the radio emitting particles, the possible level of CR pressure and the strength of magnetic fields in intracluster environment and possibly will allow us detect the accretion shocks.

  11. A tomographic gamma-ray scanner for industrial applications

    International Nuclear Information System (INIS)

    An experimental computerised tomographic (CT) gamma-ray scanner is being developed for the non-destructive testing of industrial objects. A micro-computer controlled traversing system steps the test object across a collimated gamma-ray beam the transmitted intensity of which is measured by a NaI(Tl) detector for a large number of beam paths both through the object and the surrounding air. These data are used to reconstruct an image of the scanned section in terms of a two-dimensional distribution of linear attenuation coefficients at the gamma-ray energy used. A 100 mCi 241AM source of 59.6 keV gamma-rays has been used initially in order to compare the performance with medical CT X-ray scanners. (orig.)

  12. First Results from the Swift Gamma Ray Burst Mission

    Science.gov (United States)

    Gehreis, Neil

    2005-01-01

    Swift is now in orbit after a beautiful launch on November 20, 2004. It is a multiwavelength observatory designed specifically to study the fascinating gamma-ray bursts. The goals are to determine the origin of bursts and use them to probe the early Universe. A new-technology wide-field gamma-ray camera detects more than a hundred bursts per year. Sensitive narrow-field X-ray and UV/optical telescopes are pointed at the burst location in 20 to 70 sec by an autonomously controlled "swift" spacecraft. For each burst, arcsec positions are determined and optical/UV/X-ray/gamma-ray spectrophotometry performed. Information is also rapidly sent to the ground to a team of more than 50 observers at telescopes around the world. First results from the mission will be presented, including observations of bright GRBs, faint GRBs, short GRBs and a super-giant flare from the soft gamma repeater SGRl806-20.

  13. 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_\

  14. Dark Gamma-Ray Bursts in the Swift Era

    International Nuclear Information System (INIS)

    We propose a new method for the classification of optically dark gamma-ray bursts (GRBs), based on the X-ray and optical-to-X-ray spectral indices of GRB afterglows, and utilizing the spectral capabilities of Swift. This method depends less on model assumptions than previous methods, and can be used as a quick diagnostic tool to identify optically sub-luminous bursts. With this method we can also find GRBs that are extremely bright at optical wavelengths. We show that the previously suggested correlation between the optical darkness and the X-ray/gamma-ray brightness is merely an observational selection effect.

  15. Evaluation of effective dose equivalent from environmental gamma rays

    International Nuclear Information System (INIS)

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

  16. The Keck Solar Two Gamma-Ray Observatory

    International Nuclear Information System (INIS)

    Ground-based telescopes play a role that is complementary to satellite based gamma ray detectors and are expected to provide a rich data set in the 50 GeV-1 TeV region. Heliostat arrays provide a way of making sensitive observations in this energy regime at an economical cost. With close to 2000 heliostat mirrors, the Keck Solar Two Gamma Ray Observatory near Barstow, CA, is the largest such facility in the world, and thus has the potential of being one of the most sensitive gamma ray detectors. A 32-channel camera is now operational: we discuss the current status and future prospects for the instrument

  17. Pulsars in Gamma Rays: What Fermi Is Teaching Us

    CERN Document Server

    Kerr, Matthew

    2012-01-01

    The 2nd Fermi-LAT pulsar catalog includes 117 gamma-ray pulsars, of which roughly one third are millisecond pulsars (MSPs) while the remaining two thirds split evenly into young radio-loud and radio-quiet pulsars. Although this large population will enable future, detailed studies of emission mechanisms and the evolution of the underlying neutron star population, some nearly-universal properties are already clear and unequivocal. We discuss some of these aspects below, including the altitude of the gamma-ray emission site and the shape of the gamma-ray spectrum and its implications for the radiation mechanism.

  18. Energy sources in gamma-ray burst models

    Science.gov (United States)

    Taam, Ronald E.

    1987-01-01

    The current status of energy sources in models of gamma-ray bursts is examined. Special emphasis is placed on the thermonuclear flash model which has been the most developed model to date. Although there is no generally accepted model, if the site for the gamma-ray burst is on a strongly magnetized neutron star, the thermonuclear model can qualitatively explain the energetics of some, but probably not all burst events. The critical issues that may differentiate between the possible sources of energy for gamma-ray bursts are listed and briefly discussed.

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

    OpenAIRE

    Abdo, A. A.

    2009-01-01

    Following its launch in June 2008, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in 3 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 ~10-sigma) gamma-ray sources in these data. These are the best-characterized and best-localized point-like (i.e.,...

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

    OpenAIRE

    Hjorth, Jens,

    2013-01-01

    The observed association between supernovae and gamma-ray bursts represents a cornerstone in our understanding of the nature of gamma-ray bursts. The collapsar model provides a theoretical framework for this connection. A key element is the launch of a bi-polar jet (seen as a gamma-ray burst). The resulting hot cocoon disrupts the star while the 56Ni produced gives rise to radioactive heating of the ejecta, seen as a supernova. In this discussion paper I summarise the observational status of ...

  1. 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.

  2. Cellular response to low Gamma-ray doses

    International Nuclear Information System (INIS)

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

  3. PoGOLite : The Polarised Gamma-ray Observer

    OpenAIRE

    Marini Bettolo, Cecilia

    2008-01-01

    PoGOLite is a balloon-borne experiment which will study polarised soft gamma-ray emission from astrophysical targets in the 25 keV – 80 keV energy range by applying well-type phoswich detector technology. Polarised gamma-rays are expected from a wide variety of sources including rotation-powered pulsars, accreting black holes and neutron stars, and jet-dominated active galaxies. Polarisation measurements provide a powerful probe of the gamma-ray emission mechanism and the distribution of magn...

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

    CERN Document Server

    Abdo, A A; Aller, M F; Kellermann, K I; Kovalev, Y Y; Kovalev, Y A; Lister, M L; Pushkarev, A B

    2009-01-01

    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 ~3' away from the NGC 1275 nucleus, well within the 95% LAT error circle of ~5'.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_gamma = (2.10+-0.23)x 10^{-7} ph (>100 MeV) cm^{-2} s^{-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_gamma 100 MeV) cm^{-2} s^{-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 th...

  5. Nucleosynthesis in Gamma Ray Burst Accretion Disks

    CERN Document Server

    Pruet, J; Hoffman, R D; Pruet, Jason

    2003-01-01

    We follow the nuclear reactions that occur in the accretion disks of stellar mass black holes that are accreting at a very high rate, 0.01 to 1 solar masses per second, as is realized in many current models for gamma-ray bursts (GRBs). The degree of neutronization in the disk is a sensitive function of the accretion rate, black hole mass, Kerr parameter, and disk viscosity. For high accretion rates and low viscosity, material arriving at the black hole will consist predominantly of neutrons. This degree of neutronization will have important implications for the dynamics of the GRB producing jet and perhaps for the synthesis of the r-process. For lower accretion rates and high viscosity, as might be appropriate for the outer disk in the collapsar model, neutron-proton equality persists allowing the possible synthesis of 56Ni in the disk wind. 56Ni must be present to make any optically bright Type Ib supernova, and in particular those associated with GRBs.

  6. Uses Of Gamma Rays In Peas Breeding

    International Nuclear Information System (INIS)

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

  7. 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 ...

  8. Gamma ray induced mutants in Coleus

    International Nuclear Information System (INIS)

    The germplasm collection of Chinese potato (Coleus parviflorus Benth) contains almost no variation for yield contributing traits. The crop does not produce seeds. Treatment of underground tubers with 1 kR, 2 kR, 3 kR and 4 kR gamma rays resulted in 50 morphologically different mutants which are maintained as mutant clones. In the M1V1 generation, suspected mutant sprouts, were carefully removed and grown separately. The most interesting mutant types are the following: (i) erect mutant with spoon shaped light green leaves, 30 cm long inflorescences against 20 cm in the control, cylindrical tubers measuring ca. 7.0 cm long and 3 cm girth against 4 cm and 2.5 cm in the control (ii) early mutants 1 and 2, one having less leaf serration, the other having light green small leaves and dwarf type (iii) fleshy leaf mutant, dark green, thick and smooth leaves. Control plants spread almost in 1 m2 area and bear tubers from the nodes of branches. In the early mutants tuber formation is mainly restricted to the base of the plant, which makes harvest easier. The crop usually matures within 150 - 160 days, the early mutants are ready for harvest 100 days after planting. As the mutants are less spreading, the yield could be increased by closer spacing

  9. Gamma Ray Bursts Cook Book II: Simulation

    CERN Document Server

    Ziaeepour, Houri

    2008-01-01

    In Paper I we presented a detailed formulation of the relativistic shocks and synchrotron emission in the context of Gamma-Ray Burst (GRB) physics. To see how well this model reproduces the observed characteristics of the GRBs and their afterglows, here we present the results of some simulations based on this model. They are meant to reproduce the prompt and afterglow emission in some intervals of time during a burst. We show that this goal is achieved for both short and long GRBs and their afterglows, at least for part of the parameter space. Moreover, these results are the evidence of the physical relevance of the two phenomenological models we have suggested in Paper I for the evolution of the "active region", the synchrotron emitting region in a shock. The dynamical active region model seems to reproduce the observed characteristics of prompt emissions better than the quasi-steady model which is more suitable for afterglows. Therefore these simulations confirm the arguments presented in Paper I about the ...

  10. 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.

  11. The effect of gamma rays on carrots

    International Nuclear Information System (INIS)

    The effects of several doses (5-400 Gy) of gamma rays from a 137Cs source were studied on several biological indices in carrots. Doses higher than 50 Gy reduced the wet weight of the cells in the suspension medium whereas the doses of 5 and 10 Gy affected the wet weight positively and to a lesser extent the dry weight. This may be due to higher water absorption of the irradiated cells since their number was less than that of the control. The different doses did not affect the chromosome number of the cells but reduced the cell division rates. At doses higher than 200 Gy no singel cell was recorded as dividing after two days of irradiation. A week later, however, the cells seemed to have recovered some ability for division, but with an increase of prophase stage in mitosis and also in the mitotic division abnormalities. Cells irradiation with 10 Gy caused the cells to differentiate and to form somatic embryos due to halting the effect of 2,4-D hormon. Higher doses, however, prohibited or reduced cells differentiation, probably due to higher mitotic division abnormalities. Nevertheless, it has been possible to attain mature plants from all treatments except for the 400 Gy. The low doses of 5 and 10 Gy, contrary to the higher ones, affected positively the speed of seed germination, increased the plant height, and also increased the root weight. 11 refs. (author)

  12. 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.

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

    DEFF Research Database (Denmark)

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

    1995-01-01

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

  14. Wide radio beams from gamma-ray pulsars

    CERN Document Server

    Ravi, V; Hobbs, G

    2010-01-01

    We investigate the radio and gamma-ray beaming properties of normal and millisecond pulsars by selecting two samples from the known populations. The first, Sample G, contains pulsars which are detectable in blind searches of gamma-ray data from the Fermi Large Area Telescope. The second, Sample R, contains pulsars detectable in blind radio searches which have spin-down luminosities Edot > 10^{34} erg/s. We analyse the fraction of the gamma-ray-selected Sample G which have detectable radio pulses and the fraction of the radio-selected Sample R which have detectable gamma-ray pulses. Twenty of our 35 Sample G pulsars have already observed radio pulses. This rules out low-altitude polar-cap beaming models if, as is currently believed, gamma-ray beams are generated in the outer magnetosphere and are very wide. We further find that, for the highest-Edot pulsars, the radio and gamma-ray beams have comparable beaming factors, i.e., the beams cover similar regions of the sky as the star rotates. For lower-Edot gamma-...

  15. 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.

  16. {gamma}-ray spectroscopy with a {sup 8}He beam

    Energy Technology Data Exchange (ETDEWEB)

    Podolyak, Zs. E-mail: z.podolyak@surrey.ac.uk; Walker, P.M.; Mach, H.; France, G. de; Sletten, G.; Azaiez, F.; Casandjian, J.M.; Cederwall, B.; Cullen, D.M.; Dombradi, Zs.; Dracoulis, G.D.; Fraile, L.M.; Franchoo, S.; Fynbo, H.; Gorska, M.; Kopatch, Y.; Lane, G.J.; Mandal, S.; Milechina, L.; Molnar, J.; O' Leary, C.; Plociennik, W.; Pucknell, V.; Raddon, P.; Redon, N.; Ruchowska, E.; Stanoiu, M.; Tengblad, O.; Wheldon, C.; Wood, R

    2003-10-01

    The {sup 8}He+{sup 208}Pb reaction was studied in the first experiment with the EXOGAM germanium detector array using beam delivered by the SPIRAL facility. {gamma}-rays from direct and fusion-evaporation reactions were observed with high resolution. {gamma}-{gamma} coincidence data were obtained at a beam intensity level of 10{sup 5} {sup 8}He particles per second. Specially designed absorbers and beam detectors could further reduce the background radiation by orders of magnitude.

  17. 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...

  18. 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.

  19. 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.

  20. 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.

  1. Muon spectrum in air showers initiated by gamma rays

    Science.gov (United States)

    Stephens, S. A.; Streitmatter, R. E.

    1985-01-01

    An analytic representation for the invariant cross-section for the production of charged pions in gamma P interactions was derived by using the available cross-sections. Using this the abundance of muons in a gamma ray initiated air shower is calculated.

  2. 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)

  3. G-function in gamma-ray transport problems

    International Nuclear Information System (INIS)

    In calculations of gamma-ray intensities in the cylindrical geometry, especially when the gamma-log is concerned, one has to deal with some special functions. The appropriate mathematical formulas and computational algorithms, serving for their determination were given, together with the FORTRAN program. (author)

  4. Search of gamma-rays Bremsstrahlung mirror reflection

    International Nuclear Information System (INIS)

    Full text: Total external reflection of soft X-rays is widely used in many X-ray optic systems. At the same time in the wavelength range of gamma rays the corresponding total external reflection on macroscopic smooth surface hasn't been surely verified yet. Samarkand microtron MT-22S with 330 meter flying distance was used for a search experiment of detecting gamma-ray total external reflection. Measured slip angles (i.e. angles between incident ray and reflector surface) are negligible and don't exceed tens of micro-radian. And it is a complicated problem to get required characteristics of collimating, reflecting and detecting gamma rays. The experimental setup was described earlier. Here we report experimental results of very small-angle Bremsstrahlung scattering only in comparison with results of computer simulation by Monte-Carlo method. It is continuous energy spectrum of Bremsstrahlung gamma rays (described by Shift formula) that is the first characteristic property of the experiment. And it is air in the way of gamma rays that is the second one. Continuous energy spectrum provides a use of some range of reflector inclinations (but bounded above) that satisfy the conditions of the total reflection for a corresponding part of gamma ray beam. As for air it absorbs gamma rays on their long way to detectors lowering the ratio of searching effect to background. Horizontal belt type Bremsstrahlung beam was collimated for the experiment. So the beam's horizontal acceptance was relatively wide (∼ 34 mrad). A collimator with gap heights of 100, 50 and 20 μ limited the beam in vertical that results in beam vertical divergences of 125, 62 and 25 μrad, correspondingly. The gap height of 100 μ used for positioning procedure, and the ones of 50 and 20 μ used for measurements. No separate peak of reflected gamma rays was observed at the experiment. However when vertical profiles measured at the reflector inclinations of 0 and 40 μrad are compared one can see gamma

  5. Some deficiencies and solutions in gamma ray spectrometry

    International Nuclear Information System (INIS)

    A number of problems in high-resolution gamma ray spectrometry as well as some deficiencies of existing computer programs for the quantitative evaluation of spectra are discussed and some practical solutions are proposed. (author)

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

    International Nuclear Information System (INIS)

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

  7. 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...

  8. Wavelet-based techniques for the gamma-ray sky

    Science.gov (United States)

    McDermott, Samuel D.; Fox, Patrick J.; Cholis, Ilias; Lee, Samuel K.

    2016-07-01

    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.

  9. 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.

  10. Secondary gamma-ray data for shielding calculation

    International Nuclear Information System (INIS)

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

  11. Gravitational waves from gamma-ray pulsar glitches

    International Nuclear Information System (INIS)

    We use data from pulsar gamma-ray glitches recorded by the Fermi Large Area Telescope as input to theoretical models of gravitational wave signals the glitches might generate. We find that the typical peak amplitude of the gravity wave signal from gamma-ray pulsar glitches lies between 10–23 and 10–35 in dimensionless units, with peak frequencies in the range of 1 to 1000 Hz, depending on the model. We estimate the signal-to-noise ratio (S/N) for all gamma-ray glitches, and discuss detectability with current gravity wave detectors. Our results indicate that the strongest predicted signals are potentially within reach of current detectors, and that pulsar gamma-ray glitches are promising targets for gravity wave searches by current and next-generation detectors.

  12. 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,...

  13. GRANITE, a new very high energy gamma-ray telescope

    International Nuclear Information System (INIS)

    A international collaboration of astrophysicists plan to construct a new 10-meter diameter gamma-ray Cerenkov telescope at the Whipple Observatory on Mt. Hopkins in Arizona. By operation in coincidence with the original 10-meter reflector, the sensitivity for gamma-ray detection will improve by more than an order of magnitude. The new telescope, named GRANITE (for Gamma-Ray Astrophysics New Imaging Telescope), will include a 109-element imaging photon detector wit a 0.2deg pixel size. The entire system consists of a steerable alt-azimuth mount, a faceted mirror assembly, a highly segmented photon detector, and ancillary data acquisition and control electronics. This telescope is considered an engineering prototype for a large array of Cherenkov detectors which will further enhance our ability to detect astrophysical sources of very high energy gamma rays. (orig.)

  14. The Extragalactic Gamma-ray Sky in the Fermi era

    CERN Document Server

    Massaro, F; Ferrara, E C

    2015-01-01

    The Universe is largely transparent to $\\gamma$ rays in the GeV energy range, making these high-energy photons valuable for exploring energetic processes in the cosmos. After seven years of operation, the Fermi {\\it Gamma-ray Space Telescope} has produced a wealth of information about the high-energy sky. This review focuses on extragalactic $\\gamma$-ray sources: what has been learned about the sources themselves and about how they can be used as cosmological probes. Active galactic nuclei (blazars, radio galaxies, Seyfert galaxies) and star-forming galaxies populate the extragalactic high-energy sky. Fermi observations have demonstrated that these powerful non-thermal sources display substantial diversity in energy spectra and temporal behavior. Coupled with contemporaneous multifrequency observations, the Fermi results are enabling detailed, time-dependent modeling of the energetic particle acceleration and interaction processes that produce the $\\gamma$ rays, as well as providing indirect measurements of t...

  15. 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.

  16. Gamma-ray lines: a new window to the universe

    International Nuclear Information System (INIS)

    Line emission in the gamma-ray band, an emerging branch of astronomy based on balloon and satellite data, probes the physics of nucleosynthesis, the interstellar medium, solar flares, supernovae and neutron stars

  17. Development and verification of MCCARD gamma-ray transport routine

    International Nuclear Information System (INIS)

    MCCARD, which is an abbreviation of Monte Carlo for advanced reactor design, is developed at SNU and is designed exclusively for the neutron transport calculation. The MCCARD is capable of depletion analysis and taking into account the temperature feedback effect. Till now, the code does not have the ability of simulating gamma-ray transport behavior. In this study, however, a calculation module for the gamma-ray transport is designed and a capability of estimating gamma-ray contribution to the nuclear characteristics of a given system is added into MCCARD. For verifications of the gamma-ray transport module, benchmark calculation are performed through the SMART 2D pin cell and fuel assembly problems. They are compared with these of MCNP and it is demonstrated that two results agree with each other within the statistical deviations of the Monte Carlo calculations

  18. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1984-01-01

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

  20. Gamma-ray flares from the Crab nebula

    International Nuclear Information System (INIS)

    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 (1015 electron volts) electrons in a region smaller than 1.4 * 10-2 parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory. (authors)

  1. 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.

  2. Gamma-ray lines from dark matter decay

    International Nuclear Information System (INIS)

    No known astrophysical process can generate a monoenergetic gamma-ray with energy in the TeV range, resulting in very stringent constraints on the lifetime of dark matter particles which decay producing gamma-ray lines. We derive in this work constraints on the decay width from observations at current IACTs as well as the estimated sensitivity of the projected CTA. We also discuss the implications of these limits for two dark matter models where the dark matter particle decays at tree level producing gamma-ray lines, namely the gravitino in supersymmetric models without R-parity conservation and a vector of a hidden SU(2) gauge group. We also discuss the constraints on scenarios where the gamma-ray line is generated at the one loop level.

  3. Developments in large gamma-ray detector arrays

    CERN Document Server

    Lee, I Y; Vetter, K

    2003-01-01

    Gamma-ray spectroscopy was revolutionized with the introduction of high energy-resolution semiconductor germanium (Ge) detectors in the early 1960s. This led to the large increase in sensitivity realized by today's arrays of Compton-suppressed Ge detectors. A still larger increase in sensitivity is expected by implementing the new concept of tracking. A tracking array consists of highly segmented Ge detectors (that can cover the full 4 pi solid-angle) in which gamma rays will be identified by measuring and tracking every gamma ray interaction. This article reviews the physics motivation for such detectors and the development of the new technologies involved. The concept of tracking is explained using the example of a proposed array called gamma-ray energy tracking array (GRETA).

  4. Upgrade of the JET gamma-ray cameras

    International Nuclear Information System (INIS)

    Full text: The JET gamma-ray camera diagnostics have already provided valuable information on the gamma-ray imaging of fast ion in JET plasmas. The applicability of gamma-ray imaging to high performance deuterium and deuterium-tritium JET discharges is strongly dependent on the fulfilment of rather strict requirements for the characterisation of the neutron and gamma-ray radiation fields. These requirements have to be satisfied within very stringent boundary conditions for the design, such as the requirement of minimum impact on the co-existing neutron camera diagnostics. The JET Gamma-Ray Cameras (GRC) upgrade project deals with these issues with particular emphasis on the design of appropriate neutron/gamma-ray filters ('neutron attenuators'). Several design versions have been developed and evaluated for the JET GRC neutron attenuators at the conceptual design level. The main design parameter was the neutron attenuation factor. The two design solutions, that have been finally chosen and developed at the level of scheme design, consist of: a) one quasi-crescent shaped neutron attenuator (for the horizontal camera) and b) two quasi-trapezoid shaped neutron attenuators (for the vertical one). The second design solution has different attenuation lengths: a short version, to be used together with the horizontal attenuator for deuterium discharges, and a long version to be used for high performance deuterium and DT discharges. Various neutron-attenuating materials have been considered (lithium hydride with natural isotopic composition and 6Li enriched, light and heavy water, polyethylene). Pure light water was finally chosen as the attenuating material for the JET gamma-ray cameras. The neutron attenuators will be steered in and out of the detector line-of-sight by means of an electro-pneumatic steering and control system. The MCNP code was used for neutron and gamma ray transport in order to evaluate the effect of the neutron attenuators on the neutron field of the

  5. Towards a common analysis framework for gamma-ray astronomy

    CERN Document Server

    Knödlseder, Jürgen; Deil, Christoph; Schulz, Anneli; Grondin, Marie-Hélène; Martin, Pierrick; Brau-Nogué, Sylvie

    2013-01-01

    Thanks to the success of current gamma-ray telescopes (Fermi, H.E.S.S., MAGIC, VERITAS), and in view of the prospects of planned observatories such as the Cherenkov Telescope Array (CTA) or the High-Altitude Water Cherenkov Observatory (HAWC), gamma-ray astronomy is becoming an integral part of modern astrophysical research. Analysis today relies on a large diversity of tools and software frameworks that were specifically and independently developed for each instrument. With the aim of unifying the analysis of gamma-ray data, we are currently developing GammaLib (http://sourceforge.net/projects/gammalib), a C++ library interfaced to Python that provides a framework for an instrument independent analysis of gamma-ray data. On top of GammaLib we have created ctools (http://cta.irap.omp.eu/ctools), a set of analysis executables that is being developed as one of the prototypes for the CTA high-level science analysis framework, but which is equally suited for the analysis of gamma-ray data from the existing Fermi-...

  6. Performance of the EGRET astronomical gamma ray telescope

    Science.gov (United States)

    Nolan, P. L.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hofstadter, R.; Hughes, E. B.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.

    1992-01-01

    On April 5, 1991, the Space Shuttle Atlantis carried the Compton Gamma Ray Observatory (CGRO) into orbit, deploying the satellite on April 7. The EGRET instrument was activated on April 15, and the first month of operations was devoted to verification of the instrument performance. Measurements made during that month and in the subsequent sky survey phase have verified that the instrument time resolution, angular resolution, and gamma ray detection efficiency are all within nominal limits.

  7. Performance of the EGRET astronomical gamma ray telescope

    International Nuclear Information System (INIS)

    On April 5, 1991, the Space Shuttle Atlantis carried the Compton Gamma Ray Observatory (CGRO) into orbit, deploying the satellite on April 7. This paper reports on the EGRET instrument which was activated on April 15, and the first month of operations was devoted to verification of the instrument performance. Measurements made during that month and in the subsequent sky survey phase have verified that the instrument time resolution, angular resolution, and gamma ray detection efficiency are all within nominal limits

  8. Catalogue of gamma rays from radionuclides ordered by nuclide

    International Nuclear Information System (INIS)

    A catalogue of about 28500 gamma-ray energies from 2338 radionuclides is presented. The nuclides are listed in order of increasing (A,Z) of the daughter nuclide. In addition the gamma-ray intensity per 100 decays of the parent (if known) and the decay half-life are given. All data are from a computer processing of a recent ENSDF (Evaluated Nuclear Structure Data File) file. (authors)

  9. Extragalactic Background Light and Gamma-Ray Attenuation

    OpenAIRE

    Primack, Joel R.; Dominguez, Alberto; Gilmore, Rudy C.; Somerville, Rachel S.

    2011-01-01

    Data from (non-) attenuation of gamma rays from active galactic nuclei (AGN) and gamma ray bursts (GRBs) give upper limits on the extragalactic background light (EBL) from the UV to the mid-IR that are only a little above the lower limits from observed galaxies. These upper limits now rule out some EBL models and purported observations, with improved data likely to provide even stronger constraints. We present EBL calculations both based on multiwavelength observations of thousands of galaxie...

  10. Application of multiple gamma-ray spectrum for analytical chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Hatsukawa, Yuichi; Hayakawa, Takehito; Shinohara, Noboru; Oshima, Masumi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2000-01-01

    Feasibility of application of the multi-gamma ray spectrum for analytical chemistry was examined. A specimen in which some minor fission products are included was measured at an array of ten germanium detectors with BGO Compton suppressors, GEMINI, and multiple gamma-ray spectra are measured. Even in very strong radiation fields from {sup 137}Cs isotope, some miner contents, {sup 106}Ru, {sup 125}Sb, {sup 144}Pr, {sup 207}Bi were detected by this method. (author)

  11. TANAMI: Milliarcsecond Resolution Observations of Extragalactic Gamma-ray Sources

    OpenAIRE

    Ojha, Roopesh; Kadler, M.(University Würzburg, Würzburg, Germany); Böck, M.; Booth, R.; Dutka, M. S.; Edwards, P. G.; Fey, A. L.; Fuhrmann, L.; Gaume, R. A.; Hase, H.; Horiuchi, S.; Jauncey, D. L.; Johnston, K.J.; Katz, U.; Lister, M.

    2009-01-01

    The TANAMI (Tracking AGN with Austral Milliarcsecond Interferometry) and associated programs provide comprehensive radio monitoring of extragalactic gamma-ray sources south of declination -30 degrees. Joint quasi-simultaneous observations between the Fermi Gamma-ray Space Telescope and ground based observatories allow us to discriminate between competing theoretical blazar emission models. High resolution VLBI observations are the only way to spatially resolve the sub-parsec level emission re...

  12. The STACEE Ground-Based Gamma-Ray Detector

    OpenAIRE

    STACEE Collaboration; Gingrich, D.M.; Boone, L. M.; Bramel, D.; Carson, J.; Covault, C. E.; Fortin, P.; Hanna, D. S.; Hinton, J. A.; Jarvis, A.; Kildea, J.; Lindner, T.; Mueller, C.; Mukherjee, R.; Ong, R. 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 previ...

  13. Calculation of the decision thresholds in gamma-ray spectrometry

    International Nuclear Information System (INIS)

    A method was developed for calculating the decision thresholds for gamma-ray spectrometric measurements. At the energies where gamma-ray emitters that are present in the nuclide library, but were not identified in the spectrum, radiate, peaks are supposed to appear. The peak areas are calculated by fitting, using the method of least squares, the spectral region of the supposed peaks with a continuous background and the spectrometer response function at the gamma-ray energies where the supposed peaks are positioned. The null measurement uncertainty of a gamma-ray emitter is obtained as the uncertainty of the weighted average of the activities calculated from the areas of the supposed peaks in a spectrum where the specified activity of the gamma-ray emitter is zero. For the calculation of the decision threshold the null measurement uncertainty is used. These decision thresholds overestimate the critical limits calculated with the Currie formula by about 10% in the case of single gamma-ray emitters. For multi-gamma-ray emitters the decision thresholds yield smaller values than the Currie formula. The presence of a peaked background or peaks that are near the supposed peaks increases the decision threshold considerably. - Highlights: • Decision thresholds were calculated for gamma-ray emitters by inducing type-I errors. • Peaks were supposed to appear at energies where the emitters radiate. • In case of a peaked background the peak area was obtained from the background peak area uncertainty. • Decision thresholds were calculated from the uncertainties of the average activities. • The peaked background increases the decision threshold considerably

  14. New capture gamma-ray data for PGAA database

    International Nuclear Information System (INIS)

    A new catalogue of prompt gamma rays has been created on the basis of experiments at the Budapest PGAA facility. It contains elemental spectra and a table with nearly 7000 gamma rays with relative intensity over 1 percent of the strongest line. The average accuracy is about 0.08 keV for energies and about 5 percent for cross-sections in the whole energy range, from about 40 keV to 11 MeV. (author)

  15. Recent results from the FERMI gamma-ray telescope

    International Nuclear Information System (INIS)

    Can we learn about New Physics with astronomical and astroparticle data? Since its launch in 2008, the Large Area Telescope, onboard of the Fermi Gamma-ray Space Telescope, has detected the largest amount of gamma rays in the 20 MeV–300 GeV energy range and electrons and positrons in the 7GeV–1TeV range. These impressive statistics allow one to perform a very sensitive indirect experimental search for dark matter.

  16. Gamma-Rays and Neutrinos from Dark Matter

    OpenAIRE

    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) ...

  17. System for Gamma an X rays fluorescence spectrometric

    International Nuclear Information System (INIS)

    A system for spectrometry of gamma or fluorescence X rays is presented. It sis composed by a Si(Li) semiconductors detector, a charge sensitive preamplifier, a high voltage power supply, a spectrometric amplifier and a monolithic 1024 channels multichannel analyzers or an IBM compatible 4096 channels add - on- card multichannel analyzer. The system can be configured as a 1024 or 4096 channels gamma or fluorescent X rays spectrometer

  18. Effects of galactic gamma rays bursts on planetary atmospheres

    International Nuclear Information System (INIS)

    We discuss the potential past incidence of a galactic gamma ray burst on Earth. Rough estimates for the relative frequencies of this kind of event are given, for the different eons of our planet's geological history. Additionally, we explore the effectiveness of the ozone layer of different paleo-atmospheres to shield the surface of the planet from the ultraviolet flash, which arises as a short-term effect after the incidence of a galactic gamma ray burst. (author)

  19. Validation of Airborne Visible-Infrared Imaging Spectrometer Data at Ray Mine, AZ

    Science.gov (United States)

    Lang, H.; Baloga, S.

    1999-01-01

    We validate 1997 Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) reflectance spectra covering 0.4 meu - 2.4 meu from a stable, flat mineralogically characterized man-made target at Ray Mine, AZ, the site for an EPA/NASA assessment of the utility of remote sensing for monitoring acid drainage from an active open pit mine.

  20. 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...

  1. Significance of medium-energy gamma-ray astronomy in the study of cosmic rays

    Science.gov (United States)

    Fichtel, C. E.; Kniffen, D. A.; Thompson, D. J.; Bignami, G. F.; Cheung, C. Y.

    1976-01-01

    The paper examines the medium-energy (about 10-30 MeV) galactic gamma-ray radiation from primary and secondary electrons and calculates the expected gamma-ray distribution for the specific model of Bignami et al. (1975) on the assumption that the cosmic rays are correlated with the matter on the scale of galactic arms. The energy spectrum typical of regions near the galactic center indicates a dramatic shift from a predominantly cosmic-ray nucleonic mechanism at higher energies to a cosmic-ray electron mechanism at the lower energies. This provides a most important and direct means of probing the cosmic-ray electrons as a function of galactic position by making gamma-ray observations in the few to 40 MeV energy range. Medium-energy gamma-ray astronomy is shown to be a valuable tool in galactic research.

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

    Science.gov (United States)

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

    1999-01-01

    The determination of elemental abundances is one of the highest science objectives of most lunar missions. Such multi-element abundances, ratios, or maps should include results for elements that are diagnostic or important in lunar processes, including heat-producing elements (such as K and Th), important incompatible elements (Th and rare earth elements), H (for polar deposits and regolith maturity), and key variable elements in major lunar provinces (such as Fe and Ti in the maria). Both neutron and gamma-ray spectroscopy can be used to infer elemental abundances; the two complement each other. These elemental abundances need to be determined with high accuracy and precision from measurements such as those made by the gamma-ray spectrometer (GRS) and neutron spectrometers (NS) on Lunar Prospector. As presented here, a series of steps, computer codes, and nuclear databases are needed to properly convert the raw gamma-ray and neutron measurements into good elemental abundances, ratios, and/or maps. Lunar Prospector (LP) is the first planetary mission that has measured neutrons escaping from a planet other than the Earth. The neutron spectrometers on Lunar Prospector measured a wide range of neutron energies. The ability to measure neutrons with thermal (E return, being especially sensitive to both H (using epithermal neutrons) and thermal-neutron-absorbing elements. Neutrons are made in the lunar surface by the interaction of galactic-cosmic-ray (GCR) particles with the atomic nuclei in the surface. Most neutrons are produced with energies above about 0.1 MeV. The flux of fast neutrons in and escaping from the Moon depends on es the intensity of the cosmic rays (which vary with solar activity) and the elemental composition of the surface. Variations in the elemental composition of the lunar surface can affect the flux of fast neutrons by about 25% , with Ti and Fe emitting more fast neutrons than light elements like O and Si. Most elements moderate neutrons to

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

    Science.gov (United States)

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

    2015-02-01

    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.

  4. 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.

  5. 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...

  6. LOCALIZATION OF GAMMA-RAY BURSTS USING THE FERMI GAMMA-RAY BURST MONITOR

    International Nuclear Information System (INIS)

    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

  7. 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...

  8. Spatial distribution of reflected gamma rays by Monte Carlo simulation

    International Nuclear Information System (INIS)

    In nuclear facilities, the reflection of gamma rays of the walls and metals constitutes an unknown origin of radiation. These reflected gamma rays must be estimated and determined. This study concerns reflected gamma rays on metal slabs. We evaluated the spatial distribution of the reflected gamma rays spectra by using the Monte Carlo method. An appropriate estimator for the double differential albedo is used to determine the energy spectra and the angular distribution of reflected gamma rays by slabs of iron and aluminium. We took into the account the principal interactions of gamma rays with matter: photoelectric, coherent scattering (Rayleigh), incoherent scattering (Compton) and pair creation. The Klein-Nishina differential cross section was used to select direction and energy of scattered photons after each Compton scattering. The obtained spectra show peaks at 0.511* MeV for higher source energy. The Results are in good agreement with those obtained by the TRIPOLI code [J.C. Nimal et al., TRIPOLI02: Programme de Monte Carlo Polycinsetique a Trois dimensions, CEA Rapport, Commissariat a l'Energie Atomique.

  9. Spatial distribution of reflected gamma rays by Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Jehouani, A. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, B.P. 2390, 40000 Marrakech (Morocco)], E-mail: jehouani@ucam.ac.ma; Merzouki, A. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, B.P. 2390, 40000 Marrakech (Morocco); Remote Sensing and Geomatics of the Environment Laboratory, Ottawa-Carleton Geoscience Centre, Marion Hall, 140 Louis Pasteur, Ottawa, ON, KIN 6N5 (Canada); Boutadghart, F.; Ghassoun, J. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, B.P. 2390, 40000 Marrakech (Morocco)

    2007-10-15

    In nuclear facilities, the reflection of gamma rays of the walls and metals constitutes an unknown origin of radiation. These reflected gamma rays must be estimated and determined. This study concerns reflected gamma rays on metal slabs. We evaluated the spatial distribution of the reflected gamma rays spectra by using the Monte Carlo method. An appropriate estimator for the double differential albedo is used to determine the energy spectra and the angular distribution of reflected gamma rays by slabs of iron and aluminium. We took into the account the principal interactions of gamma rays with matter: photoelectric, coherent scattering (Rayleigh), incoherent scattering (Compton) and pair creation. The Klein-Nishina differential cross section was used to select direction and energy of scattered photons after each Compton scattering. The obtained spectra show peaks at 0.511{sup *} MeV for higher source energy. The Results are in good agreement with those obtained by the TRIPOLI code [J.C. Nimal et al., TRIPOLI02: Programme de Monte Carlo Polycinsetique a Trois dimensions, CEA Rapport, Commissariat a l'Energie Atomique. ].

  10. Spatial distribution of reflected gamma rays by Monte Carlo simulation

    Science.gov (United States)

    Jehouani, A.; Merzouki, A.; Boutadghart, F.; Ghassoun, J.

    2007-10-01

    In nuclear facilities, the reflection of gamma rays of the walls and metals constitutes an unknown origin of radiation. These reflected gamma rays must be estimated and determined. This study concerns reflected gamma rays on metal slabs. We evaluated the spatial distribution of the reflected gamma rays spectra by using the Monte Carlo method. An appropriate estimator for the double differential albedo is used to determine the energy spectra and the angular distribution of reflected gamma rays by slabs of iron and aluminium. We took into the account the principal interactions of gamma rays with matter: photoelectric, coherent scattering (Rayleigh), incoherent scattering (Compton) and pair creation. The Klein-Nishina differential cross section was used to select direction and energy of scattered photons after each Compton scattering. The obtained spectra show peaks at 0.511∗ MeV for higher source energy. The Results are in good agreement with those obtained by the TRIPOLI code [J.C. Nimal et al., TRIPOLI02: Programme de Monte Carlo Polycinśetique à Trois dimensions, CEA Rapport, Commissariat à l'Energie Atomique. [1

  11. The Gamma-Ray View of the Extragalactic Background Light

    CERN Document Server

    Finke, Justin D

    2010-01-01

    The Extragalactic Background Light (EBL) from the infrared (IR) through the ultraviolet (UV) is dominated by emission from stars, either directly or through absorption and reradiation by dust. It can thus give information on the star formation history of the universe. However, it is difficult to measure directly due to foreground radiation fields from the Galaxy and solar system. Gamma-rays from extragalactic sources at cosmological distances (blazars and gamma-ray bursts) interact with EBL photons creating electron-positron pairs, absorbing the gamma-rays. Given the intrinsic gamma-ray spectrum of a source and its redshift, the EBL can in principle be measured. However, the intrinsic gamma-ray spectra of blazars and GRBs can vary considerably from source to source and the from the same source over short timescales. A maximum intrinsic spectrum can be assumed from theoretical grounds, to give upper limits on the EBL absorption from blazars at low redshift with very high energy (VHE) gamma-ray observations wit...

  12. Inactivation of citrus tristeza virus by gamma ray irradiation

    International Nuclear Information System (INIS)

    The total exposure of gamma ray and the intensity of gamma ray per hour for the inactivation of citrus tristeza virus (CTV) and also the effect on citrus tissues are described. The budwoods of Morita navel orange infected with a severe seedling-yellow strain of CTV were irradiated with gamma ray from a 60Co source for 20 -- 52 hours. The buds or small tissue pieces of the irradiated budwoods were subsequently grafted onto Mexcan lime. CTV was easily inactivated by the irradiation from 10 to 18 kR for from 20 to 52 hours. The higher the total exposure, the higher the rate of inactivation. The CTV in the budwoods was almost inactivated after the irradiation with 20 kR. When the total exposure to gamma ray on budwoods was the same, CTV was more efficiently inactivated by the irradiation for long period with low intensity of gamma ray per hour than that for short period with high intensity per hour. Gamma ray irradiation was effective to eliminate CTV from citrus tissues. (Mori, K.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Atwood, W. B. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Baldini, L. [Universita di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bregeon, J.; Pesce-Rollins, M.; Sgro, C.; Tinivella, M. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Bruel, P. [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France); Chekhtman, A. [Center for Earth Observing and Space Research, College of Science, George Mason University, Fairfax, VA 22030 (United States); Cohen-Tanugi, J. [Laboratoire Univers et Particules de Montpellier, Universite Montpellier 2, CNRS/IN2P3, F-34095 Montpellier (France); Drlica-Wagner, A.; Omodei, N.; Rochester, L. S.; Usher, T. L. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Granot, J. [Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Ra' anana 43537 (Israel); Longo, F. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Razzaque, S. [Department of Physics, University of Johannesburg, Auckland Park 2006 (South Africa); Zimmer, S., E-mail: melissa.pesce.rollins@pi.infn.it, E-mail: nicola.omodei@stanford.edu, E-mail: granot@openu.ac.il [Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm (Sweden)

    2013-09-01

    Based on the experience gained during the four and a half years of the mission, the Fermi-LAT Collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet finalized, we can test the improvements in the new event reconstruction with the special case of the prompt phase of bright gamma-ray bursts (GRBs), where the signal-to-noise ratio is large enough that loose selection cuts are sufficient to identify gamma rays associated with the source. Using the new event reconstruction, we have re-analyzed 10 GRBs previously detected by the Large Area Telescope (LAT) for which an X-ray/optical follow-up was possible and found four new gamma rays with energies greater than 10 GeV in addition to the seven previously known. Among these four is a 27.4 GeV gamma ray from GRB 080916C, which has a redshift of 4.35, thus making it the gamma ray with the highest intrinsic energy ({approx}147 GeV) detected from a GRB. We present here the salient aspects of the new event reconstruction and discuss the scientific implications of these new high-energy gamma rays, such as constraining extragalactic background light models, Lorentz invariance violation tests, the prompt emission mechanism, and the bulk Lorentz factor of the emitting region.

  14. 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. Lag-luminosity relation in gamma-ray burst X-ray flares

    CERN Document Server

    Margutti, R

    2010-01-01

    In strict analogy to prompt pulses, X-ray flares observed by Swift-XRT in long Gamma-Ray Bursts define a lag-luminosity relation: L_p,iso \\propto t_lag^{-0.95+/-0.23}. The lag-luminosity is proven to be a fundamental law extending 5 decades in time and 5 in energy. This is direct evidence that GRB X-ray flares and prompt gamma-ray pulses are produced by the same mechanism.

  16. 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...

  17. 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.

  18. 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.

  19. X Ray Precursors in SGRs: Precessing Gamma Jet Tails

    OpenAIRE

    Fargion, Daniele

    2001-01-01

    Weak isolated X-ray precursor events before the main Gamma Ray Burst, GRB, and also rare Soft Gamma Repeaters, SGR, events are in complete disagreement with any Fireball, or Magnetar, one-shoot explosive scenarios. Fireball model in last two years has been deeply modified into a fountain beamed Jet exploding and interacting on external shells to explain GRB fine time structure. On the contrary earlier we proposed a unified scenario for both GRBs-SGRs where a precessing Gamma Jet (of different...

  20. Pulsed Gamma-Ray Emission From Short-Period Pulsars: Predicted Gamma-Ray Pulsar PSR1951+32

    Science.gov (United States)

    Cheng, K. S.; Ding, K. Y. Winnis

    1995-03-01

    We studied the gamma-ray emission mechanisms from pulsars with period, P, between 4.6 times 10(-2) B12(2/5) s and 0.17 B12(5/12) sin (1/6) theta alpha (-5/4) s in terms of outermagnetospheric gap model. We found that the spectra of all known gamma -ray pulsars can be fitted by two free parameters, namely, alpha r_L, the mean distance to the outergap, and sin theta , the mean pitch angle of the secondary e(+/-) pairs. Gamma-rays from those pulsars with P B12(5/12) sin (1/6) alpha (-5/4) s are mainly emitted by secondary e(+/-) pairs, which are created beyond the outergap, via synchrotron radiation and the gamma-ray emission efficiency is ~ 10(-2) . For pulsars with period approaching ~ 0.17 B12(5/12) sin (1/6) alpha (-5/4) s, their gamma-ray emission efficiency is approaching unity. We used our model to fit the observed spectra of gamma -ray pulsars (Vela, PSR1706-44, PSR1055-52, PSR1509-58, Geminga). All the best fit curves satisfy the constraints of alpha and sin theta . The pulse separation and relative intensity of pulses are function of alpha . In our model, the first three strongest theoretical gamma -ray sources have been detected. PSR1951+32 is predicted to be the fourth strongest gamma -ray pulsar (Cheng and Ding, 1994, ApJ, 432, 724) which is confirmed by the recent GRO result.

  1. Correlation of Supernova Remnant Masers and Gamma-Ray Sources

    CERN Document Server

    Hewitt, John W; Wardle, Mark

    2009-01-01

    Supernova remnants interacting with molecular clouds are potentially exciting systems in which to detect evidence of cosmic ray acceleration. Prominent gamma-ray emission is produced via the decay of neutral pions when cosmic rays encounter the nearby dense clouds. In many of the supernova remnants coincident with gamma-ray sources, the presence of OH(1720 MHz) masers is used to identify interaction with dense gas and to provide a kinematic distance to the system. In this paper we use statistical tests to demonstrate that there is a correlation between these masers and a class of GeV- to TeV-energy gamma-ray sources coincident with interacting remnants. For pion decay, the gamma-ray luminosity provides a direct estimate of the local cosmic ray density. We find the cosmic ray density is enhanced by one to two orders of magnitude over the local solar value, comparable to X-ray-induced ionization in these remnants. The inferred ionization rates are sufficient to explain non-equilibrium chemistry in the post-shoc...

  2. Gamma-ray shielding design and performance test of WASTEF

    International Nuclear Information System (INIS)

    The Waste Safety Testing Facility (WASTEF) was planned in 1978 to test the safety performance of HLW vitrified forms under the simulated conditions of long term storage and disposal, and completed in August 1981. The designed feature of the facility is to treat the vitrified forms contain actual high-level wastes of 5 x 104 Ci in maximum with 5 units of concrete shilded hot cells (3 units : Bate-Gamma cells, 2 units : Alpha-Gamma cells) and one units of Alpha-Gamma lead shielded cell, and to store radioactivity of 106 Ci in maximum. The safety performance of this facility is fundamentally maintained with confinement of radioactivity and shielding of the radiation. This report describes the method of gamma-ray shielding design, evaluation of the shielding test performed by using sealded gamma-ray sources(Co-60). (author)

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

    CERN Document Server

    Yuan, Qiang

    2014-01-01

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

  4. Calibration and control modules for gamma-ray borehole loggers

    International Nuclear Information System (INIS)

    A calibration pad for quantitative evaluation of gamma-ray logs, developed and constructed by CNEA is described. The facility is composed of a set of mineralized modules with which it is intended to reproduce the natural variable conditions found in boreholes drilled for uranium mineral exploration, such as the ore concentration, rock's density and porosity, water content, etc. The facility is able to operate under different radiometric models, as follow: 1) gross-count gamma-ray models; 2) gamma-spectrometer models; 3) neutronic-fission models, and 4) models for determination of magnetic susceptibility, density, neutron-neutron, etc. The gathered information allows the adequate quantitative radiometric evaluation of the ore bodies crossed by exploration holes, and also allows the correlation of gamma-ray logs obtained by different logger-equipments. The paper includes the description of the project development and the standards established for the facility's operation. (M.E.L.)

  5. Response of human lymphocytes to low gamma ray doses

    International Nuclear Information System (INIS)

    Radiation and non-radiation workers lymphocytes were exposed to a low strength gamma-ray field to determine heat shock protein expression in function of radiation dose. Protein identification was carried out using mAb raised against Hsp25, Hsp60, Hsp70 and Hsp90; from these, only Hsp70 protein was detected before and after lymphocyte irradiation. In all cases, an increasing trend of relative amounts of Hsp70 in function to irradiation time was observed. After 70.5 mGy gamma-ray dose, radiation worker's lymphocytes expressed more Hsp70 protein, than non-radiation workers' lymphocytes, indicating a larger tolerance to gamma rays (gamma tolerance), due to an adaptation process developed by their labor condition (Au)

  6. Air shower detectors in gamma-ray astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Sinnis, Gus [Los Alamos National Laboratory

    2008-01-01

    Extensive air shower (EAS) arrays directly detect the particles in an EAS that reach the observation altitude. This detection technique effectively makes air shower arrays synoptic telescopes -- they are capable of simultaneously and continuously viewing the entire overhead sky. Typical air shower detectors have an effective field-of-view of 2 sr and operate nearly 100% of the time. These two characteristics make them ideal instruments for studying the highest energy gamma rays, extended sources and transient phenomena. Until recently air shower arrays have had insufficient sensitivity to detect gamma-ray sources. Over the past decade, the situation has changed markedly. Milagro, in the US, and the Tibet AS{gamma} array in Tibet, have detected very-high-energy gamma-ray emission from the Crab Nebula and the active galaxy Markarian 421 (both previously known sources). Milagro has discovered TeV diffuse emission from the Milky Way, three unidentified sources of TeV gamma rays, and several candidate sources of TeV gamma rays. Given these successes and the suite of existing and planned instruments in the GeV and TeV regime (AGILE, GLAST, HESS, VERITAS, CTA, AGIS and IceCube) there are strong reasons for pursuing a next generation of EAS detectors. In conjunction with these other instruments the next generation of EAS instruments could answer long-standing problems in astrophysics.

  7. 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.

  8. 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.

  9. X-ray variability of GeV gamma-ray emitting radio galaxy NGC 1275

    CERN Document Server

    Fukazawa, Yasushi; Tanaka, Yasuyuki; Itoh, Ryosuke; Nagai, Hiroshi

    2016-01-01

    We analyzed Suzaku/XIS data of 2006--2015 observations of a gamma-ray emitting radio galaxy NGC 1275, and brightening of the nucleus in the X-ray band was found in 2013--2015, correlating with GeV Gamma-ray brightening. This is the first evidence of variability with correlation between GeV gamma-ray and X-ray for NGC 1275. We also analyzed Swift/XRT data of NGC 1275, and found that X-ray was flaring by a factor of $\\sim$5 in several days in 2006, 2010, and 2013. The X-ray spectrum during the flare was featureless and somewhat steeper with a photon index of $\\sim$2 against $\\sim$1.7 in the normal state, indicating that a synchrotron component became brighter. A large Xray to GeV gamma-ray flux ratio in the flare could be explained by the shock-in-jet scenario. On the other hand, a long-term gradual brightening of radio, X-ray, and GeV gamma-ray with a larger gamma-ray amplitude could be origin of other than internal shocks, and then we discuss some possibilities.

  10. The influence of exogenous conditions on mobile measured gamma-ray spectrometry

    Science.gov (United States)

    Dierke, C.; Werban, U.; Dietrich, P.

    2012-12-01

    In the past, gamma ray measurements have been used for geological surveys and exploration using airborne and borehole logging systems. For these applications, the relationships between the measured physical parameter - the concentration of natural gamma emitters 40K, 238U and 232Th - and geological origin or sedimentary developments are well described. Based on these applications and knowledge in combination with adjusted sensor systems, gamma ray measurements are used to derive soil parameters to create detailed soil maps e.g., in digital soil mapping (DSM) and monitoring of soils. Therefore, not only qualitative but also quantitative comparability is necessary. Grain size distribution, type of clay minerals and organic matter content are soil parameters which directly influence the gamma ray emitter concentration. Additionally, the measured concentration is influenced by endogenous processes like soil moisture variation due to raining events, foggy weather conditions, or erosion and deposition of material. A time series of gamma ray measurements was used to observe changes in gamma ray concentration on a floodplain area in Central Germany. The study area is characterised by high variations in grain size distribution and occurrence of flooding events. For the survey, we used a 4l NaI(Tl) detector with GPS connection mounted on a sledge, which is towed across the field sites by a four-wheel-vehicle. The comparison of data from different time steps shows similar structures with minor variation between the data ranges and shape of structures. However, the data measured during different soil moisture contents differ in absolute value. An average increase of soil moisture of 36% leads to a decrease of Th (by 20%), K (by 29%), and U (by 41%). These differences can be explained by higher attenuation of radiation during higher soil moisture content. The different changes in nuclide concentration will also lead to varying ratios. We will present our experiences concerning

  11. Gamma rays application in veterinary immunology

    International Nuclear Information System (INIS)

    Full text: The process based on stimulated action of ionized radiation, change of quality of agricultural goods and row materials, biocides including bactericide action of ionized radiation are among the methods of radiation biotechnology, which can be applied in agriculture. We used the bactericide action of ionized radiation in technological process for creation of fundamentally new preparation possessed by by immunogenic properties and named as 'radio vaccine'. This term is well known and frequently used in scientific papers in the field of applied radiobiology. It is well known that physical (thermal) and chemical actions are used for preparation of vaccine for veterinary. It was noted that this process resulted in destruction of antigenic structure of bacteria cells, with are responsible for immunity creation. The possibility of virulence reduction at constant immunogenic properties of microorganism and keeping its antigenic structure can be achieved by using ionized radiation as one of the factor, which influences on bacteria. Taking into account the necessity of vaccine improvement and increase of quantity of associated vaccine one of the most important problems of veterinary science and particle is creation of vaccines of new generation which are characterized by the ability to form immunity against several diseases of agricultural animals. As a result of many-years investigations using gamma rays radiations in UzSRIV (laboratory of radiobiology) the radiation biotechnology of vaccine preparation was developed. These vaccines are necessary for practical application. Radiation biotechnology allows to prepare high-effective mono-, associated and polyvalent radio vaccines against widespread infection diseases of agricultural animals especially cubs (calves, lambs, young pigs). On the basis of developed radiation biotechnology there were prepared the following vaccines: 'Associated radio vaccine against colibacteriosis and salmonellosis of small horned cattle

  12. Gamma-ray Astronomy: Implications for Fundamental Physics

    CERN Document Server

    Rico, Javier

    2011-01-01

    Gamma-ray Astronomy studies cosmic accelerators through their electromagnetic radiation in the energy range between ~100 MeV and ~100 TeV. The present most sensitive observations in this energy band are performed, from space, by the Large Area Telescope onboard the Fermi satellite and, from Earth, by the Imaging Air Cherenkov Telescopes MAGIC, H.E.S.S. and VERITAS. These instruments have revolutionized the field of Gamma-ray Astronomy, discovering different populations of gamma-ray emitters and studying in detail the non-thermal astrophysical processes producing this high-energy radiation. The scientific objectives of these observatories include also questions of fundamental physics. With gamma-ray instruments we study the origin of Galactic cosmic rays, testing the hypothesis or whether they are mainly produced in supernova explosions. Also, we obtain the most sensitive measurement of the cosmic electron-positron spectrum between 20 GeV and 5 TeV. By observing the gamma-ray emission from sources at cosmologi...

  13. Inverse Compton production of gamma rays in interstellar space

    International Nuclear Information System (INIS)

    The longitude distribution of gamma rays of energy >100MeV produced by the inverse Compton interaction in the galaxy is calculated. Cosmic ray electron density is considered either uniform throughout the galactic plane, or varying in accordance with the model of Paul et al. (1974). Stellar photon intensity is estimated using models of mass distribution in the galactic nucleus and the disc. Contribution of the 2.7 deg K black-body radiation is included. The calculated gamma ray flux from the galactic centre direction is lower than that measured by the SAS II satellite by an order of magnitude

  14. The Gamma-ray Albedo of the Moon

    OpenAIRE

    Moskalenko, Igor V.; Porter, Troy A.

    2007-01-01

    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 a...

  15. Status of ground-based gamma-ray astronomy

    CERN Document Server

    Lemoine-Goumard, Marianne

    2015-01-01

    This article is the write-up of a rapporteur talk given at the 34th ICRC in The Hague, Netherlands. It attempts to review the results and developments presented at the conference and associated to the vibrant field of ground-based gamma-ray astronomy. In total, it aims to give an overview of the 19 gamma-ray sessions, 84 talks and 176 posters presented at the 34th ICRC on this topic. New technical advances and projects will be described with an emphasis given on the cosmic-ray related studies of the Universe.

  16. Ultrahigh Energy Cosmic Rays, The Diffuse High Energy Gamma Ray Background and Anti-protons

    OpenAIRE

    Eichler, David; Idan, Raz; Gavish, Eyal

    2016-01-01

    Theories for the origin of ultrahigh energy cosmic rays (UHECR) may imply a significant diffuse background in secondary $\\gamma$-rays from the pair cascads the UHECR initiate when interacting with background light. It is shown that, because the spectrum of these secondary $\\gamma$-rays is softer than the measured diffuse $\\gamma$-ray background in the 10-1000 GeV range, the addition of a hard component from the decay of TeV dark matter particles, subject to the implied constraints on its para...

  17. 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.

  18. CALET Upper Limits on X-ray and Gamma-ray Counterparts of GW 151226

    OpenAIRE

    Adriani, O.; Akaike, Y.; Asano, K.; Asaoka, Y; Bagliesi, M.G.; Bigongiari, G.; Binns, W. R.; Bonechi, S.; Bongi, M.; Brog, P.; J. H. Buckley(Department of Physics, Washington University, St. Louis, USA); Cannady, N.; G. Castellini(INFN Firenze); Checchia, C.; Cherry, M. L.

    2016-01-01

    We present upper limits in the hard X-ray and gamma-ray bands at the time of the LIGO gravitational-wave event GW 151226 derived from the CALorimetric Electron Telescope (CALET) observation. The main instrument of CALET, CALorimeter (CAL), observes gamma-rays from ~1 GeV up to 10 TeV with a field of view of ~2 sr. The CALET gamma-ray burst monitor (CGBM) views ~3 sr and ~2pi sr of the sky in the 7 keV - 1 MeV and the 40 keV - 20 MeV bands, respectively, by using two different scintillator-bas...

  19. High Energy Gamma Rays from Protons Hitting Compact Objects

    CERN Document Server

    Barbieri, J

    2008-01-01

    In a previous paper the spectrum of positrons produced by matter initially at rest falling onto a massive compact object was calculated. In this paper this calculation is generalized to obtain both the spectrum of in-flight positron annihilation and pi0 decay gamma rays produced when protons with a cosmic ray-like spectrum hit the surface. The resulting pi0 decay gamma ray spectrum reflects the high energy proton energy spectrum, and is largely independent of the mass of the compact object. One notable prediction for all compact objects is a dip in the spectrum below 70 MeV. As applied to the 10^6 solar mass massive compact object near to the center of our galaxy, our theory shows promise for explaining the gamma rays coming from the galactic center as observed by both the Compton satellite and HESS ground based array.

  20. The Fermi view of gamma-ray bursts

    Science.gov (United States)

    Axelsson, Magnus; Fermi/LAT Collaboration

    2015-08-01

    The Fermi mission has brought great advances in the study of GRBs. Over 1500 gamma-ray bursts (GRBs) have been detected by the Gamma-ray Burst Monitor (GBM), and more than 100 of these are also detected by the Fermi Large Area Telescope (LAT) above 30 MeV. These high-energy detections have revealed previously unknown features in GRB spectra, including additional components and spectral cut-offs, as well as delayed and long-lived GeV emission. Interpretation of these new features has proven to be a source of vigorous debate within the GRB community. I will review recent Fermi-LAT observations of GRBs, ranging from the detection of the long-lived GRB 130427A to the broad-band fits of simultaneous X-ray and gamma-ray data, and what they reveal about the origin of the high-energy emission from GRBs.