From Radio with Love: An Overview of the Role of Radio Observations in Understanding High-Energy Emission from Active Galaxies

NASA Technical Reports Server (NTRS)

Ojha, Roopesh

2012-01-01

The gamma-ray satellite Fermi and the ground based TeV facilities MAGIC, VERITAS and HESS have ushered in a new era in the observation of high-energy emission from active galaxies. The energy budgets of these objects have a major contribution from gamma-rays and it is simply not possible to understand their physics without high-energy observations. Though the exact mechanisms for high-energy production in galaxies remains an open question, gamma-rays typically result from interactions between high-energy particles. Via different interactions these same particles can produce radio emission. Thus the non-thermal nature of gamma-ray emission practically guarantees that high-energy emitters are also radio loud. Aside from their obvious role as a component of multiwavelength analysis, radio observations provide two crucial elements essential to understanding the source structure and physical processes of high-energy emitters: very high timing resolution and very high spatial resolution. A brief overview of the unique role played by radio observations in unraveling the mysteries of the high energy Universe as presented here.

Validation of gamma-ray detection techniques for safeguards monitoring at natural uranium conversion facilities

DOE PAGES

Dewji, Shaheen A.; Lee, Denise L.; Croft, Stephen; ...

2016-03-28

Recent IAEA circulars and policy papers have sought to implement safeguards when any purified aqueous uranium solution or uranium oxides suitable for isotopic enrichment or fuel fabrication exists. Under the revised policy, IAEA Policy Paper 18, the starting point for nuclear material under safeguards was reinterpreted, suggesting that purified uranium compounds should be subject to safeguards procedures no later than the first point in the conversion process. In response to this technical need, a combination of simulation models and experimental measurements were employed to develop and validate concepts of nondestructive assay monitoring systems in a natural uranium conversion plant (NUCP).more » In particular, uranyl nitrate (UO 2(NO 3) 2) solution exiting solvent extraction was identified as a key measurement point (KMP), where gamma-ray spectroscopy was selected as the process monitoring tool. The Uranyl Nitrate Calibration Loop Equipment (UNCLE) facility at Oak Ridge National Laboratory was employed to simulate the full-scale operating conditions of a purified uranium-bearing aqueous stream exiting the solvent extraction process in an NUCP. Nondestructive assay techniques using gamma-ray spectroscopy were evaluated to determine their viability as a technical means for drawing safeguards conclusions at NUCPs, and if the IAEA detection requirements of 1 significant quantity (SQ) can be met in a timely way. This work investigated gamma-ray signatures of uranyl nitrate circulating in the UNCLE facility and evaluated various gamma-ray detector sensitivities to uranyl nitrate. These detector validation activities include assessing detector responses to the uranyl nitrate gamma-ray signatures for spectrometers based on sodium iodide, lanthanum bromide, and high-purity germanium detectors. The results of measurements under static and dynamic operating conditions at concentrations ranging from 10–90 g U/L of natural uranyl nitrate are presented. A range of gamma-ray lines is examined, including attenuation for transmission measurement of density and concentration. It was determined that transmission-corrected gamma-ray spectra provide a reliable way to monitor the 235U concentration of uranyl nitrate solution in transfer pipes in NUCPs. Furthermore, existing predictive and analysis methods are adequate to design and realize practical designs. The 137Cs transmission source employed in this work is viable but not optimal for 235U densitometry determination. Validated simulations assessed the viability of 133Ba and 57Co as alternative densitometry sources. All three gamma-ray detectors are viable for monitoring natural uranium feed; although high-purity germanium is easiest to interpret, it is, however, the least attractive as an installation instrument. Overall, for monitoring throughput in a facility such as UNCLE, emulating the uranium concentration and pump speeds of the Springfields conversion facility in the United Kingdom, an uncertainty of less than 0.17% is required in order to detect the diversion of 1 SQ of uranyl nitrate through changes in uranium concentration over an accountancy period of one year with a detection probability of 50%. As a result, calibrated gamma-ray detection systems are capable of determining the concentration of uranium content in NUCPs, it is only in combination with verifiable operator declarations and supporting data, such as flow rate and enrichment, that safeguards conclusions can be drawn.« less

Characterisation and optimisation of the new Prompt Gamma-ray Activation Analysis (PGAA) facility at FRM II

NASA Astrophysics Data System (ADS)

Canella, Lea; Kudějová, Petra; Schulze, Ralf; Türler, Andreas; Jolie, Jan

2011-04-01

At the research reactor Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) a new Prompt Gamma-ray Activation Analysis (PGAA) facility was installed. The instrument was originally built and operating at the spallation source at the Paul Scherrer Institute in Switzerland. After a careful re-design in 2004-2006, the new PGAA instrument was ready for operation at FRM II. In this paper the main characteristics and the current operation conditions of the facility are described. The neutron flux at the sample position can reach up 6.07×1010 [cm-2 s-1], thus the optimisation of some parameters, e.g. the beam background, was necessary in order to achieve a satisfactory analytical sensitivity for routine measurements. Once the optimal conditions were reached, detection limits and sensitivities for some elements, like for example H, B, C, Si, or Pb, were calculated and compared with other PGAA facilities. A standard reference material was also measured in order to show the reliability of the analysis under different conditions at this instrument.

Intrinsic germanium detector used in borehole sonde for uranium exploration

USGS Publications Warehouse

Senftle, F.E.; Moxham, R.M.; Tanner, A.B.; Boynton, G.R.; Philbin, P.W.; Baicker, J.A.

1976-01-01

A borehole sonde (~1.7 m long; 7.3 cm diameter) using a 200 mm2 planar intrinsic germanium detector, mounted in a cryostat cooled by removable canisters of frozen propane, has been constructed and tested. The sonde is especially useful in measuring X- and low-energy gamma-ray spectra (40–400 keV). Laboratory tests in an artificial borehole facility indicate its potential for in-situ uranium analyses in boreholes irrespective of the state of equilibrium in the uranium series. Both natural gamma-ray and neutron-activation gamma-ray spectra have been measured with the sonde. Although the neutron-activation technique yields greater sensitivity, improvements being made in the resolution and efficiency of intrinsic germanium detectors suggest that it will soon be possible to use a similar sonde in the passive mode for measurement of uranium in a borehole down to about 0.1% with acceptable accuracy. Using a similar detector and neutron activation, the sonde can be used to measure uranium down to 0.01%.

Feasibility study of 235U and 239Pu characterization in radioactive waste drums using neutron-induced fission delayed gamma rays

NASA Astrophysics Data System (ADS)

Nicol, T.; Pérot, B.; Carasco, C.; Brackx, E.; Mariani, A.; Passard, C.; Mauerhofer, E.; Collot, J.

2016-10-01

This paper reports a feasibility study of 235U and 239Pu characterization in 225 L bituminized waste drums or 200 L concrete waste drums, by detecting delayed fission gamma rays between the pulses of a deuterium-tritium neutron generator. The delayed gamma yields were first measured with bare samples of 235U and 239Pu in REGAIN, a facility dedicated to the assay of 118 L waste drums by Prompt Gamma Neutron Activation Analysis (PGNAA) at CEA Cadarache, France. Detectability in the waste drums is then assessed using the MCNPX model of MEDINA (Multi Element Detection based on Instrumental Neutron Activation), another PGNAA cell dedicated to 200 L drums at FZJ, Germany. For the bituminized waste drum, performances are severely hampered by the high gamma background due to 137Cs, which requires the use of collimator and shield to avoid electronics saturation, these elements being very penalizing for the detection of the weak delayed gamma signal. However, for lower activity concrete drums, detection limits range from 10 to 290 g of 235U or 239Pu, depending on the delayed gamma rays of interest. These detection limits have been determined by using MCNPX to calculate the delayed gamma useful signal, and by measuring the experimental gamma background in MEDINA with a 200 L concrete drum mock-up. The performances could be significantly improved by using a higher interrogating neutron emission and an optimized experimental setup, which would allow characterizing nuclear materials in a wide range of low and medium activity waste packages.

KSC-08pd0611

NASA Image and Video Library

2008-03-04

KENNEDY SPACE CENTER, FLA. -- The shipping container holding NASA's Gamma-Ray Large Area Space Telescope, or GLAST, is removed from the truck at the Astrotech payload processing facility near the Kennedy Space Center to begin prelaunch activities. The GLAST will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Kim Shiflett

KSC-08pd0612

NASA Image and Video Library

2008-03-04

KENNEDY SPACE CENTER, FLA. -- The shipping container holding NASA's Gamma-Ray Large Area Space Telescope, or GLAST, is removed from the truck at the Astrotech payload processing facility near the Kennedy Space Center to begin prelaunch activities. The GLAST will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Kim Shiflett

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

NASA Technical Reports Server (NTRS)

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

2010-01-01

The Pulsed Neutron Generator-Gamma Ray And Neutron Detectors (PNG-GRAND) experiment is an innovative application of the active neutron-gamma ray technology so successfully used in oil field well logging and mineral exploration on Earth. The objective of our active neutron-gamma ray technology program at NASA Goddard Space Flight Center (NASA-GSFC) is to bring the PNG-GRAND instrument to the point where it can be flown on a variety of surface lander or rover missions to the Moon, Mars, Menus, asteroids, comets and the satellites of the outer planets. Gamma-Ray Spectrometers (GRS) have been incorporated into numerous orbital planetary science missions and, especially its the case of the Mars Odyssey GRS, have contributed detailed maps of the elemental composition over the entire surface of Mars. However, orbital gamma ray measurements have low spatial sensitivity (100's of km) due to their low surface emission rates from cosmic rays and subsequent need to be averaged over large surface areas. PNG-GRAND overcomes this impediment by incorporating a powerful neutron excitation source that permits high sensitivity surface and subsurface measurements of bulk elemental compositions. PNG-GRAND combines a pulsed neutron generator (PNG) with gamma ray and neutron detectors to produce a landed instrument to determine subsurface elemental composition without needing to drill into a planet's surface a great advantage in mission design. We are currently testing PNG-GRAND prototypes at a unique outdoor neutron instrumentation test facility recently constructed at NASA/GSFC that consists of a 2 m x 2 in x 1 m granite structure placed outdoors in an empty field. Because an independent trace elemental analysis has been performed on the material, this granite sample is a known standard with which to compare both Monte Carlo simulations and our experimentally measured elemental composition data. We will present data from operating PNG-GRAND in various experimental configurations on a known sample in a geometry that is identical to that on a planetary surface. We will also illustrate the use of gamma ray timing techniques to improve sensitivity and will compare the material composition results from our experiments to both an independent laboratory elemental composition analysis and MCNPX computer modeling results.

Structural Shielding Design and Evaluation for Megavoltage X- and Gamma-Ray Radiotherapy Facilities.

PubMed

Glasgow, Glenn P

2006-09-01

Structural Shielding Design and Evaluation for Megavoltage X- and Gamma-Ray Radiotherapy Facilities NCRP Report No. 151, 2005, 246 pp. (Hardcover $100). National Council on Radiation Protection and Measurements, 7910 Woodmont Avenue, Suite 400, Bethesda, MD 20814-3095. ISBN-10 0-0929600-87-8; http://www.NCRPonline.org. © 2006 American Association of Physicists in Medicine.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathews, M.A.; Bowman, H.R.; Huang, L., H.

A low radioactivity calibration facility has been constructed at the Nevada Test Site (NTS). This facility has four calibration models of natural stone that are 3 ft in diameter and 6 ft long, with a 12 in. cored borehole in the center of each model and a lead-shielded run pipe below each model. These models have been analyzed by laboratory natural gamma ray spectroscopy (NGRS) and neutron activation analysis (NAA) for their K, U, and Th content. Also, 42 other elements were analyzed in the NAA. The /sup 222/Rn emanation data were collected. Calibrating the spectral gamma tool in thismore » low radioactivity calibration facility allows the spectral gamma log to accurately aid in the recognition and mapping of subsurface stratigraphic units and alteration features associated with unusual concentrations of these radioactive elements, such as clay-rich zones.« less

Discrimination of irradiated MOX fuel from UOX fuel by multivariate statistical analysis of simulated activities of gamma-emitting isotopes

NASA Astrophysics Data System (ADS)

Åberg Lindell, M.; Andersson, P.; Grape, S.; Hellesen, C.; Håkansson, A.; Thulin, M.

2018-03-01

This paper investigates how concentrations of certain fission products and their related gamma-ray emissions can be used to discriminate between uranium oxide (UOX) and mixed oxide (MOX) type fuel. Discrimination of irradiated MOX fuel from irradiated UOX fuel is important in nuclear facilities and for transport of nuclear fuel, for purposes of both criticality safety and nuclear safeguards. Although facility operators keep records on the identity and properties of each fuel, tools for nuclear safeguards inspectors that enable independent verification of the fuel are critical in the recovery of continuity of knowledge, should it be lost. A discrimination methodology for classification of UOX and MOX fuel, based on passive gamma-ray spectroscopy data and multivariate analysis methods, is presented. Nuclear fuels and their gamma-ray emissions were simulated in the Monte Carlo code Serpent, and the resulting data was used as input to train seven different multivariate classification techniques. The trained classifiers were subsequently implemented and evaluated with respect to their capabilities to correctly predict the classes of unknown fuel items. The best results concerning successful discrimination of UOX and MOX-fuel were acquired when using non-linear classification techniques, such as the k nearest neighbors method and the Gaussian kernel support vector machine. For fuel with cooling times up to 20 years, when it is considered that gamma-rays from the isotope 134Cs can still be efficiently measured, success rates of 100% were obtained. A sensitivity analysis indicated that these methods were also robust.

The Probing In-Situ With Neutron and Gamma Rays (PING) Instrument for Planetary Composition Measurements

NASA Technical Reports Server (NTRS)

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

2012-01-01

The Probing In situ with Neutrons and Gamma rays (PING) instrument (formerly named PNG-GRAND) [I] experiment is an innovative application of the active neutron-gamma ray technology successfully used in oil field well logging and mineral exploration on Earth over many decades. The objective of our active neutron-gamma ray technology program at NASA Goddard Space Flight Center (NASA/GSFC) is to bring PING to the point where it can be flown on a variety of surface lander or rover missions to the Moon, Mars, Venus, asteroids, comets and the satellites of the outer planets and measure their bulk surface and subsurface elemental composition without the need to drill into the surface. Gamma-Ray Spectrometers (GRS) have been incorporated into numerous orbital planetary science missions. While orbital measurements can map a planet, they have low spatial and elemental sensitivity due to the low surface gamma ray emission rates reSUlting from using cosmic rays as an excitation source, PING overcomes this limitation in situ by incorporating a powerful neutron excitation source that permits significantly higher elemental sensitivity elemental composition measurements. PING combines a 14 MeV deuterium-tritium Pulsed Neutron Generator (PNG) with a gamma ray spectrometer and two neutron detectors to produce a landed instrument that can determine the elemental composition of a planet down to 30 - 50 cm below the planet's surface, The penetrating nature of .5 - 10 MeV gamma rays and 14 MeV neutrons allows such sub-surface composition measurements to be made without the need to drill into or otherwise disturb the planetary surface, thus greatly simplifying the lander design, We are cun'ently testing a PING prototype at a unique outdoor neutron instrumentation test facility at NASA/GSFC that provides two large (1.8 m x 1.8 m x ,9 m) granite and basalt test formations placed outdoors in an empty field, Since an independent trace elemental analysis has been performed on both these Columbia River basalt and Concord Gray granite materials, these large samples present two known standards with which to compare PING's experimentally measured elemental composition results, We will present both gamma ray and neutron experimental results from PING measurements of the granite and basalt test formations in various layering configurations and compare the results to the known composition.

Planetary Geochemistry Using Active Neutron and Gamma Ray Instrumentation

NASA Technical Reports Server (NTRS)

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

2010-01-01

The Pulsed Neutron Generator-Gamma Ray And Neutron Detector (PNG-GRAND) experiment is an innovative application of the active neutron-gamma ray technology so successfully used in oil field well logging and mineral exploration on Earth, The objective of our active neutron-gamma ray technology program at NASA Goddard Space Flight Center (NASA/GSFC) is to bring the PNG-GRAND instrument to the point where it can be flown on a variety of surface lander or rover missions to the Moon, Mars, Venus, asterOIds, comets and the satellites of the outer planets, Gamma-Ray Spectrometers have been incorporated into numerous orbital planetary science missions and, especially in the case of Mars Odyssey, have contributed detailed maps of the elemental composition over the entire surface of Mars, Neutron detectors have also been placed onboard orbital missions such as the Lunar Reconnaissance Orbiter and Lunar Prospector to measure the hydrogen content of the surface of the moon, The DAN in situ experiment on the Mars Science Laboratory not only includes neutron detectors, but also has its own neutron generator, However, no one has ever combined the three into one instrument PNG-GRAND combines a pulsed neutron generator (PNG) with gamma ray and neutron detectors to produce a landed instrument that can determine subsurface elemental composition without drilling. We are testing PNG-GRAND at a unique outdoor neutron instrumentation test facility recently constructed at NASA/GSFC that consists of a 2 m x 2 m x 1 m granite structure in an empty field, We will present data from the operation of PNG-GRAND in various experimental configurations on a known sample in a geometry that is identical to that which can be achieved on a planetary surface. We will also compare the material composition results inferred from our experiments to both an independent laboratory elemental composition analysis and MCNPX computer modeling results,

Search for medium-energy gamma-ray pulsars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sweeney, W.E. Jr.

1987-01-01

Results are presented from a search for pulsed gamma rays from four radio pulsars, chosen for their interest to gamma-ray astronomers in previous studies. The data set used for the search consists of gamma-ray events at energies of 1-30 MeV, detected during a 40-hour balloon flight of the UCR double Compton scatter telescope launched at the National Scientific Balloon Facility in Palestine, Texas, USA on September 30, 1978. No statistically significant signals were detected from any of the pulsars. Three sigma upper limits to pulsed 1-30 MeV gamma ray flux from PSR 0950+08, PSR 1822+09, PSR 1929+10, and PSR 1953+29more » are presented. Two complete exposures to PSR 0950+08 were obtained. The reported tentative detection of 1-20 MeV gamma rays from PSR 0950+08 is not confirmed.« less

The development of the gamma-ray Cherenkov telescope at the South Pole

NASA Astrophysics Data System (ADS)

Barbagli, G.; Castellini, G.; Landi, G.; Morse, R.; Tasselli, P. L.; Tilav, S.

1993-05-01

An atmospheric Cherenkov telescope (ACT) designated GASP (Gamma Astronomy at the South Pole) has been installed near the SPASE (South Pole Air Shower Experiment) scintillator array at the South Pole Observing Facility. During the austral summer 1992, it was aimed at objects such as PKS 0537-441 and PSR 1706-44, simultaneously with the Egret detector on the Compton Gamma Ray Observatory (CGRO). Recently observed radio silent quasars that emit gamma rays with enormous intensity may account for the origin of cosmic ray flux at energies that exceed 1016 eV. Other galactic sources like Cygnus X-3 are believed to produce the UHE cosmic gamma flux. In addition to SPASE and GASP, a group of particle detectors (AMANDA, ACA, POOL, MICE) are currently being tested. The above instrumentation will constitute the South Pole Observatory Facility. The members of the GASP collaboration are as follows: Firenze: G. Barbagli G. Castellini, G. Landi, P.L. Tasselli; Purdue: J. Gaidos, F. Loeffler, G. Sembroski; C. Wilson; Smithsonian: K. Harris, M.A. Lawrence, T.C. Weekes; Wisconsin K. Engel, F. Halzen R. Morse, P. Surrey, S. Tilav

Towards a global network of gamma-ray detector calibration facilities

NASA Astrophysics Data System (ADS)

Tijs, Marco; Koomans, Ronald; Limburg, Han

2016-09-01

Gamma-ray logging tools are applied worldwide. At various locations, calibration facilities are used to calibrate these gamma-ray logging systems. Several attempts have been made to cross-correlate well known calibration pits, but this cross-correlation does not include calibration facilities in Europe or private company calibration facilities. Our aim is to set-up a framework that gives the possibility to interlink all calibration facilities worldwide by using `tools of opportunity' - tools that have been calibrated in different calibration facilities, whether this usage was on a coordinated basis or by coincidence. To compare the measurement of different tools, it is important to understand the behaviour of the tools in the different calibration pits. Borehole properties, such as diameter, fluid, casing and probe diameter strongly influence the outcome of gamma-ray borehole logging. Logs need to be properly calibrated and compensated for these borehole properties in order to obtain in-situ grades or to do cross-hole correlation. Some tool providers provide tool-specific correction curves for this purpose. Others rely on reference measurements against sources of known radionuclide concentration and geometry. In this article, we present an attempt to set-up a framework for transferring `local' calibrations to be applied `globally'. This framework includes corrections for any geometry and detector size to give absolute concentrations of radionuclides from borehole measurements. This model is used to compare measurements in the calibration pits of Grand Junction, located in the USA; Adelaide (previously known as AMDEL), located in Adelaide Australia; and Stonehenge, located at Medusa Explorations BV in the Netherlands.

A long duration balloon-borne telescope for solar gamma-ray astronomy

NASA Technical Reports Server (NTRS)

Owens, Alan; Chupp, Edward L.; Dunphy, Philip P.

1989-01-01

A new solar gamma-ray telescope is described which is intended to take advantage of current long-duration ballon facilities such as the RACOON system. The primary scientific objective is to detect and measure gamma-ray lines from solar flares, along with the associated low-energy continuum. The proposed instrument is centered on a multiheaded Ge system and is designed to operate over the energy range 50 keV to 200 200 MeV. In the nuclear transition energy region, the average energy resolution of the primary detectors is over 20 times better than that achieved with the gamma-ray spectrometer on the Solar Maximum Mission satellite.

A long duration balloon-borne telescope for solar gamma-ray astronomy

NASA Astrophysics Data System (ADS)

Owens, Alan; Chupp, Edward L.; Dunphy, Philip P.

A new solar gamma-ray telescope is described which is intended to take advantage of current long-duration ballon facilities such as the RACOON system. The primary scientific objective is to detect and measure gamma-ray lines from solar flares, along with the associated low-energy continuum. The proposed instrument is centered on a multiheaded Ge system and is designed to operate over the energy range 50 keV to 200 200 MeV. In the nuclear transition energy region, the average energy resolution of the primary detectors is over 20 times better than that achieved with the gamma-ray spectrometer on the Solar Maximum Mission satellite.

Future Gamma-Ray Observations of Pulsars and their Environments

NASA Technical Reports Server (NTRS)

Thompson, David J.

2006-01-01

Pulsars and pulsar wind nebulae seen at gamma-ray energies offer insight into particle acceleration to very high energies under extreme conditions. Pulsed emission provides information about the geometry and interaction processes in the magnetospheres of these rotating neutron stars, while the pulsar wind nebulae yield information about high-energy particles interacting with their surroundings. During the next decade, a number of new and expanded gamma-ray facilities will become available for pulsar studies, including Astro-rivelatore Gamma a Immagini LEggero (AGILE) and Gamma-ray Large Area Space Telescope (GLAST) in space and a number of higher-energy ground-based systems. This review describes the capabilities of such observatories to answer some of the open questions about the highest-energy processes involving neutron stars.

NRAO Teams With NASA Gamma-Ray Satellite

NASA Astrophysics Data System (ADS)

2007-06-01

The National Radio Astronomy Observatory (NRAO) is teaming with NASA's upcoming Gamma-ray Large Area Space Telescope (GLAST) to allow astronomers to use both the orbiting facility and ground-based radio telescopes to maximize their scientific payoff. Under the new, streamlined process, astronomers can compete for coordinated observing time and support from both GLAST and NRAO's radio telescopes. GLAST satellite Artist's rendering of the GLAST spacecraft in orbit above the Earth. CREDIT: General Dynamics C4 Systems Click on Image for Larger File Images of NRAO Telescopes Robert C. Byrd Green Bank Telescope Very Long Baseline Array Very Large Array Atacama Large Millimeter/submillimeter Array GLAST is scheduled for launch no earlier than December 14. It will perform a survey of the entire sky at gamma-ray wavelengths every 3 hours using its primary instrument, the Large Area Telescope (LAT). NRAO operates the Very Large Array (VLA) in New Mexico, the continent-wide Very Long Baseline Array (VLBA), and the Robert C. Byrd Green Bank Telescope (GBT) in West Virginia. The NRAO is a research facility of the National Science Foundation (NSF). "Coordinated gamma-ray and radio observations of celestial objects will greatly enhance the ability to fully understand those objects. Astronomy today requires such multiwavelength studies, and this agreement paves the way for exciting, cutting-edge research," said Fred K.Y. Lo, NRAO Director. GLAST will be vastly more capable than previous gamma-ray satellites, and will carry an instrument, the GLAST Burst Monitor, specifically designed to detect gamma-ray bursts. GLAST observers will study objects such as active galaxies, pulsars, and supernova remnants, which are also readily studied with radio telescopes. By working together, NASA's GLAST mission and NSF's NRAO facilities can study flares from blazars over the widest possible range of energies, which is crucial to understanding how black holes, notorious for drawing matter in, can accelerate jets of material to nearly light speed. "The gamma-ray and radio observations will show scientists different aspects of many still-mysterious objects and processes. By providing a simple procedure for astronomers to win observing time on radio telescopes to follow up on our new gamma-ray discoveries, we're ensuring that we get the maximum scientific return from both," said GLAST project scientist Steve Ritz of NASA's Goddard Space Flight Center in Greenbelt, Md. "The importance of this coordinated approach has been highlighted by a recent two-day workshop at Goddard, in which we discussed the scientific benefits and coordination of radio Very Long Baseline Interferometry observations made in conjunction with GLAST." NRAO's radio telescopes have been used for many years as part of multiwavelength observing programs in conjunction with both ground-based and space-based observatories. Usually, however, astronomers had to submit separate observing proposals to two or more review committees, with no guarantee that they would win observing time on all desired telescopes. For its part, NASA spacecraft such as the Compton Gamma-Ray Observatory and the Chandra X-ray Observatory have opened wide new windows on the high-energy universe. Astronomers, including those on a recent NSF Senior Review panel, have urged reductions in administrative barriers to gaining observing time at multiple wavelengths. "This NRAO-GLAST agreement eases the process of winning observing time on NRAO telescopes to complement the GLAST all-sky gamma-ray survey. In particular, the continent-wide VLBA is the only existing radio telescope that can image and monitor the sites of extreme gamma-ray flares in distant galaxies," said Jim Ulvestad, NRAO's Director for VLA-VLBA Operations. "We expect to see arrangements like this become much more common in the future, to the benefit of the science." The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. NASA's GLAST mission is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Habs, D.; Guenther, M. M.; Jentschel, M.

With the planned new {gamma}-beam facilities like MEGa-ray at LLNL (USA) or ELI-NP at Bucharest (Romania) with 10{sup 13}{gamma}/s and a band width of {Delta}E{gamma}/E{gamma} Almost-Equal-To 10{sup -3}, a new era of {gamma} beams with energies up to 20MeV comes into operation, compared to the present world-leading HI{gamma}S facility at Duke University (USA) with 10{sup 8}{gamma}/s and {Delta}E{gamma}/E{gamma} Almost-Equal-To 3 Dot-Operator 10{sup -2}. In the long run even a seeded quantum FEL for {gamma} beams may become possible, with much higher brilliance and spectral flux. At the same time new exciting possibilities open up for focused {gamma} beams. Here wemore » describe a new experiment at the {gamma} beam of the ILL reactor (Grenoble, France), where we observed for the first time that the index of refraction for {gamma} beams is determined by virtual pair creation. Using a combination of refractive and reflective optics, efficient monochromators for {gamma} beams are being developed. Thus, we have to optimize the total system: the {gamma}-beam facility, the {gamma}-beam optics and {gamma} detectors. We can trade {gamma} intensity for band width, going down to {Delta}E{gamma}/E{gamma} Almost-Equal-To 10{sup -6} and address individual nuclear levels. The term 'nuclear photonics' stresses the importance of nuclear applications. We can address with {gamma}-beams individual nuclear isotopes and not just elements like with X-ray beams. Compared to X rays, {gamma} beams can penetrate much deeper into big samples like radioactive waste barrels, motors or batteries. We can perform tomography and microscopy studies by focusing down to {mu}m resolution using Nuclear Resonance Fluorescence (NRF) for detection with eV resolution and high spatial resolution at the same time. We discuss the dominating M1 and E1 excitations like the scissors mode, two-phonon quadrupole octupole excitations, pygmy dipole excitations or giant dipole excitations under the new facet of applications. We find many new applications in biomedicine, green energy, radioactive waste management or homeland security. Also more brilliant secondary beams of neutrons and positrons can be produced.« less

The U.S. Spectrum X Gamma Coordination Facility

NASA Astrophysics Data System (ADS)

Forman, William R.

1999-08-01

Spectrum-X-Gamma (SXG) provides for US participation in a first-class international x-ray mission. Despite launch delays, SXG will provide unique scientific opportunities due to its capability for all-sky monitoring, polarimetry, high resolution spectroscopy, and broad wavelength range-from the ultraviolet (TAUVEX and FUVITA), through the x-ray (SODART and JET-X), to the hard x-ray (MART), and gamma-ray burst detectors. Before describing our completed work, we review the unique properties of SXG and provide some examples of the scientific importance of SXG in the Chandra, XMM, and ASTRO-E era.

The U.S. Spectrum X Gamma Coordination Facility

NASA Technical Reports Server (NTRS)

Forman, William R.

1999-01-01

Spectrum-X-Gamma (SXG) provides for US participation in a first-class international x-ray mission. Despite launch delays, SXG will provide unique scientific opportunities due to its capability for all-sky monitoring, polarimetry, high resolution spectroscopy, and broad wavelength range-from the ultraviolet (TAUVEX and FUVITA), through the x-ray (SODART and JET-X), to the hard x-ray (MART), and gamma-ray burst detectors. Before describing our completed work, we review the unique properties of SXG and provide some examples of the scientific importance of SXG in the Chandra, XMM, and ASTRO-E era.

Development of the Probing In-Situ with Neutron and Gamma Rays (PING) Instrument for Planetary Science Applications

NASA Technical Reports Server (NTRS)

Parsons, A.; Bodnarik, J.; Burger, D.; Evans, L.; Floyd, S; Lim, L.; McClanahan, T.; Namkung, M.; Nowicki, S.; Schweitzer, J.;

Fermi-LAT detection of ongoing gamma-ray activity from the new gamma-ray source Fermi J1654-1055 (PMN J1632-1052)

NASA Astrophysics Data System (ADS)

Kocevski, D.; Ajello, M.; Buson, S.; Buehler, R.; Giomi, M.

2016-02-01

During the week between February 8 and 15, 2016, the Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, observed gamma-ray activity from a new transient source, Fermi J1654-1055.

Measurement of the total activity concentrations of Libyan oil scale

NASA Astrophysics Data System (ADS)

Da Silva, F. C. A.; Bradley, D. A.; Regan, P. H.; Rozaila, Z. Siti

2017-08-01

Twenty-three oil scale samples obtained from the Libyan oil and gas industry production facilities onshore have been measured using high-resolution gamma-ray spectrometry with a shielded HPGe detector, the work being carried out within the Environmental Radioactivity Laboratory at the University of Surrey. The main objectives of this work were to determine the extent to which the predominant radionuclides associated with the uranium and thorium natural decay chains were in secular equilibrium with their decay progeny, also to compare differences between the total activity concentrations (TAC) in secular equilibrium and disequilibrium and to evaluate the measured activities for the predominant gamma-ray emitting decay radionuclides within the 232Th and 238U chains. The oil scale NORM samples did not exhibit radioactive equilibrium between the decay progeny and longer-lived parent radionuclides of the 238U and 232Th series.

Nuclear Physics Laboratory technical progress report, November 1, 1972-- November 1, 1973

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1973-11-01

The experimental program was divided into the areas of nuclear physics (charged-particle experiments, gamma-ray experiments andd beta decay, neutron time-of-flight experiments, x-ray fluorescence analysis, other activities), intermediate enengy physics, and apparatus and facility development. The energy- loss spectrograph, rotating-beam neutron time-of-flight spectrometer, and cyclotron and the rearch done using these facilities are described. The theoretical program has concentrated on the effects of two-step processes in nuclear reactions. The trace element analysis program continued, and a neutron beam for cancer therapy is being developed. Lists of publications and personnel are also included. (RWR)

KSC-08pd0646

NASA Image and Video Library

2008-03-05

KENNEDY SPACE CENTER, FLA. -- In the Astrotech payload processing facility, NASA's Gamma-Ray Large Area Space Telescope, or GLAST, sits uncovered before its move to a work stand in the facility for a complete checkout of the scientific instruments aboard. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Kim Shiflett

DESIGN OF A GAMMA-RAY SOURCE BASED ON INVERSE COMPTON SCATTERING AT THE FAST SUPERCONDUCTING LINAC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mihalcea, D.; Jacobson, B.; Murokh, A.

2016-10-10

A watt-level average-power gamma-ray source is currently under development at the Fermilab Accelerator Science & Technology (FAST) facility. The source is based on the Inverse Compton Scattering of a high-brightness 300-MeV beam against a high-power laser beam circulating in an optical cavity. The back scattered gamma rays are expected to have photon energies up to 1.5 MeV. This paper discusses the optimization of the source, its performances, and the main challenges ahead.

Gamma ray irradiated AgFeO{sub 2} nanoparticles with enhanced gas sensor properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xiuhua, E-mail: xhwang@mail.ahnu.edu.cn; Shi, Zhijie; Yao, Shangwu

2014-11-15

AgFeO{sub 2} nanoparticles were synthesized via a facile hydrothermal method and irradiated by various doses of gamma ray. The products were characterized with X-ray powder diffraction, UV–vis absorption spectrum and transmission electron microscope. The results revealed that the crystal structure, morphology and size of the samples remained unchanged after irradiation, while the intensity of UV–Vis spectra increased with irradiation dose increasing. In addition, gamma ray irradiation improved the performance of gas sensor based on the AgFeO{sub 2} nanoparticles including the optimum operating temperature and sensitivity, which might be ascribed to the generation of defects. - Graphical abstract: Gamma ray irradiationmore » improved the performance of gas sensor based on the AgFeO{sub 2} nanoparticles including sensitivity and optimum operating temperature, which might be ascribed to the generation of defects. - Highlights: • AgFeO{sub 2} nanoparticles were synthesized and irradiated with gamma ray. • AgFeO{sub 2} nanoparticles were employed to fabricate gas sensors to detect ethanol. • Gamma ray irradiation improved the sensitivity and optimum operating temperature.« less

Extended performance gas Cherenkov detector for gamma-ray detection in high-energy density experiments.

PubMed

Herrmann, H W; Kim, Y H; Young, C S; Fatherley, V E; Lopez, F E; Oertel, J A; Malone, R M; Rubery, M S; Horsfield, C J; Stoeffl, W; Zylstra, A B; Shmayda, W T; Batha, S H

2014-11-01

A new Gas Cherenkov Detector (GCD) with low-energy threshold and high sensitivity, currently known as Super GCD (or GCD-3 at OMEGA), is being developed for use at the OMEGA Laser Facility and the National Ignition Facility (NIF). Super GCD is designed to be pressurized to ≤400 psi (absolute) and uses all metal seals to allow the use of fluorinated gases inside the target chamber. This will allow the gamma energy threshold to be run as low at 1.8 MeV with 400 psi (absolute) of C2F6, opening up a new portion of the gamma ray spectrum. Super GCD operating at 20 cm from TCC will be ∼400 × more efficient at detecting DT fusion gammas at 16.7 MeV than the Gamma Reaction History diagnostic at NIF (GRH-6m) when operated at their minimum thresholds.

Monitoring System for the Gold Target by Radiation Detectors in Hadron Experimental Facility at J-PARC

NASA Astrophysics Data System (ADS)

Muto, Ryotaro; Agari, Keizo; Aoki, Kazuya; Bessho, Kotaro; Hagiwara, Masayuki; Hirose, Erina; Ieiri, Masaharu; Iwasaki, Ruri; Katoh, Yohji; Kitagawa, Jun-ichi; Minakawa, Michifumi; Morino, Yuhei; Saito, Kiwamu; Sato, Yoshinori; Sawada, Shin'ya; Shirakabe, Yoshihisa; Suzuki, Yoshihiro; Takahashi, Hitoshi; Tanaka, Kazuhiro; Toyoda, Akihisa; Watanabe, Hiroaki; Yamanoi, Yutaka

2017-09-01

At the Hadron Experimental Facility in J-PARC, we inject a 30-GeV proton beam into a gold target to produce secondary particle beams required for various particle and nuclear physics experiments. The gold target is placed in a hermetic chamber, and helium gas is circulated in the chamber to monitor the soundness of the target. The radioactivity in helium gas is continuously monitored by gamma-ray detectors such as a germanium detector and a NaI(Tl) detector. Beam operations with those target-monitoring systems were successfully performed from April to June and October to December 2015, and from May to June 2016. In this paper, the details of the helium gas circulation system and gamma-ray detectors and the analysis results of the obtained gamma-ray spectra are reported.

Comparison Between the NIST and the KEBS for the Determination of Air Kerma Calibration Coefficients for Narrow X-Ray Spectra and 137Cs Gamma-Ray Beams

PubMed Central

O’Brien, Michelle; Minniti, Ronaldo; Masinza, Stanslaus Alwyn

2010-01-01

Air kerma calibration coefficients for a reference class ionization chamber from narrow x-ray spectra and cesium 137 gamma-ray beams were compared between the National Institute of Standards and Technology (NIST) and the Kenya Bureau of Standards (KEBS). A NIST reference-class transfer ionization chamber was calibrated by each laboratory in terms of the quantity air kerma in four x-ray reference radiation beams of energies between 80 kV and 150 kV and in a cesium 137 gamma-ray beam. The reference radiation qualities used for this comparison are described in detail in the ISO 4037 publication.[1] The comparison began in September 2008 and was completed in March 2009. The results reveal the degree to which the participating calibration facility can demonstrate proficiency in transferring air kerma calibrations under the conditions of the said facility at the time of the measurements. The comparison of the calibration coefficients is based on the average ratios of calibration coefficients. PMID:27134777

Comparison Between the NIST and the KEBS for the Determination of Air Kerma Calibration Coefficients for Narrow X-Ray Spectra and (137)Cs Gamma-Ray Beams.

PubMed

O'Brien, Michelle; Minniti, Ronaldo; Masinza, Stanslaus Alwyn

2010-01-01

Air kerma calibration coefficients for a reference class ionization chamber from narrow x-ray spectra and cesium 137 gamma-ray beams were compared between the National Institute of Standards and Technology (NIST) and the Kenya Bureau of Standards (KEBS). A NIST reference-class transfer ionization chamber was calibrated by each laboratory in terms of the quantity air kerma in four x-ray reference radiation beams of energies between 80 kV and 150 kV and in a cesium 137 gamma-ray beam. The reference radiation qualities used for this comparison are described in detail in the ISO 4037 publication.[1] The comparison began in September 2008 and was completed in March 2009. The results reveal the degree to which the participating calibration facility can demonstrate proficiency in transferring air kerma calibrations under the conditions of the said facility at the time of the measurements. The comparison of the calibration coefficients is based on the average ratios of calibration coefficients.

An Overview of the Current Understanding of Gamma-Ray Bursts in the Fermi Era

NASA Technical Reports Server (NTRS)

Bhat, P. N.; Guiriec, Sylvain

2011-01-01

Gamma-ray bursts are the most luminous explosions in the Universe, and their origin as well as mechanism are the focus of intense research and debate. More than three decades since their serendipitous discovery, followed by several breakthroughs from space-borne and ground-based observations, they remain one of the most interesting astrophysical phenomena yet to be completely understood. Since the launch of Fermi with its unprecedented energy band width spanning seven decades, the study of gamma-ray burst research has entered a new phase. Here we review the current theoretical understanding and observational highlights of gamma-ray burst astronomy and point out some of the potential promises of multi-wavelength observations in view of the upcoming ground based observational facilities .

The Gamma Ray Imaging Detector of the AGILE satellite: A novel application of silicon trackers for detection of astrophysics high-energy photons

NASA Astrophysics Data System (ADS)

Rappoldi, Andrea; AGILE Collaboration

2009-10-01

AGILE is a project of the Italian Space Agency (ASI) Scientific Program dedicated to Gamma ray astrophysics. It is designed to be a very light and compact instrument, capable of photon detections and imaging in both the 30 MeV-50 GeV and 18-60 keV energy ranges, with a large field of view (FOV is ˜3 and ˜1 sr, respectively). The core of the instrument (launched on April 23, 2007 from the Indian Space Research Organization's launch facility) is represented by the Gamma Ray Imaging Detector (GRID), which is a silicon tracker developed by the Italian National Institute of Nuclear Physics (INFN), with a spatial resolution of ˜40 μm. The GRID performances have been studied by means of a GEANT Montecarlo, and tested with a dedicated calibration campaign using the tagged gamma beam available at Beam Test Facility (BTF) of INFN Frascati Laboratory.

Gamma radiation survey of the LDEF spacecraft

NASA Astrophysics Data System (ADS)

Phillips, G. W.; King, S. E.; August, R. A.; Ritter, J. C.; Cutchin, J. H.; Haskins, P. S.; McKisson, J. E.; Ely, D. W.; Weisenberger, A. G.; Piercey, R. B.

1991-06-01

The retrieval of the Long Duration Exposure Facility (LDEF) spacecraft after nearly 6 years in orbit offered a unique opportunity to study the long term buildup of induced radioactivity in the variety of materials on board. The first complete gamma ray survey was conducted of a large spacecraft on LDEF shortly after its return to Earth. A surprising observation was the large Be-7 activity which was seen primarily on the leading edge of the satellite, implying that it was picked up by LDEF in orbit. This is the first known evidence for accretion of a radioactive isotope onto an orbiting spacecraft. Other isotopes seen during the survey, the strongest being Na-22 and Mn-54, are all attributed to activation of spacecraft components in orbit. Be-7 is a spallation product of cosmic rays on nitrogen and oxygen in the upper atmosphere. However, the observed density is much greater than expected due to cosmic ray production in situ. This implies transport of Be-7 from much lower altitudes up to the LDEF orbit.

Investigation of the possibility of gamma-ray diagnostic imaging of target compression at NIF

PubMed Central

Lemieux, Daniel A.; Baudet, Camille; Grim, Gary P.; Barber, H. Bradford; Miller, Brian W.; Fasje, David; Furenlid, Lars R.

2013-01-01

The National Ignition Facility at Lawrence Livermore National Laboratory is the world’s leading facility to study the physics of igniting plasmas. Plasmas of hot deuterium and tritium, undergo d(t,n)α reactions that produce a 14.1 MeV neutron and 3.5 MeV a particle, in the center of mass. As these neutrons pass through the materials surrounding the hot core, they may undergo subsequent (n,x) reactions. For example, 12C(n,n’γ)12C reactions occur in remnant debris from the polymer ablator resulting in a significant fluence of 4.44 MeV gamma-rays. Imaging of these gammas will enable the determination of the volumetric size and symmetry of the ablation; large size and high asymmetry is expected to correlate with poor compression and lower fusion yield. Results from a gamma-ray imaging system are expected to be complimentary to a neutron imaging diagnostic system already in place at the NIF. This paper describes initial efforts to design a gamma-ray imaging system for the NIF using the existing neutron imaging system as a baseline for study. Due to the cross-section and expected range of ablator areal densities, the gamma flux should be approximately 10−3 of the neutron flux. For this reason, care must be taken to maximize the efficiency of the gamma-ray imaging system because it will be gamma starved. As with the neutron imager, use of pinholes and/or coded apertures are anticipated. Along with aperture and detector design, the selection of an appropriate scintillator is discussed. The volume of energy deposition of the interacting 4.44 MeV gamma-rays is a critical parameter limiting the imaging system spatial resolution. The volume of energy deposition is simulated with GEANT4, and plans to measure the volume of energy deposition experimentally are described. Results of tests on a pixellated LYSO scintillator are also presented. PMID:23420688

Investigation of the possibility of gamma-ray diagnostic imaging of target compression at NIF

NASA Astrophysics Data System (ADS)

Lemieux, Daniel A.; Baudet, Camille; Grim, Gary P.; Barber, H. Bradford; Miller, Brian W.; Fasje, David; Furenlid, Lars R.

2011-09-01

The National Ignition Facility at Lawrence Livermore National Laboratory is the world's leading facility to study the physics of igniting plasmas. Plasmas of hot deuterium and tritium, undergo d(t,n)α reactions that produce a 14.1 MeV neutron and 3.5 MeV a particle, in the center of mass. As these neutrons pass through the materials surrounding the hot core, they may undergo subsequent (n,x) reactions. For example, 12C(n,n'γ)12C reactions occur in remnant debris from the polymer ablator resulting in a significant fluence of 4.44 MeV gamma-rays. Imaging of these gammas will enable the determination of the volumetric size and symmetry of the ablation; large size and high asymmetry is expected to correlate with poor compression and lower fusion yield. Results from a gamma-ray imaging system are expected to be complimentary to a neutron imaging diagnostic system already in place at the NIF. This paper describes initial efforts to design a gamma-ray imaging system for the NIF using the existing neutron imaging system as a baseline for study. Due to the cross-section and expected range of ablator areal densities, the gamma flux should be approximately 10-3 of the neutron flux. For this reason, care must be taken to maximize the efficiency of the gamma-ray imaging system because it will be gamma starved. As with the neutron imager, use of pinholes and/or coded apertures are anticipated. Along with aperture and detector design, the selection of an appropriate scintillator is discussed. The volume of energy deposition of the interacting 4.44 MeV gamma-rays is a critical parameter limiting the imaging system spatial resolution. The volume of energy deposition is simulated with GEANT4, and plans to measure the volume of energy deposition experimentally are described. Results of tests on a pixellated LYSO scintillator are also presented.

Investigation of the possibility of gamma-ray diagnostic imaging of target compression at NIF.

PubMed

Lemieux, Daniel A; Baudet, Camille; Grim, Gary P; Barber, H Bradford; Miller, Brian W; Fasje, David; Furenlid, Lars R

2011-09-23

The National Ignition Facility at Lawrence Livermore National Laboratory is the world's leading facility to study the physics of igniting plasmas. Plasmas of hot deuterium and tritium, undergo d(t,n)α reactions that produce a 14.1 MeV neutron and 3.5 MeV a particle, in the center of mass. As these neutrons pass through the materials surrounding the hot core, they may undergo subsequent (n,x) reactions. For example, (12)C(n,n'γ)(12)C reactions occur in remnant debris from the polymer ablator resulting in a significant fluence of 4.44 MeV gamma-rays. Imaging of these gammas will enable the determination of the volumetric size and symmetry of the ablation; large size and high asymmetry is expected to correlate with poor compression and lower fusion yield. Results from a gamma-ray imaging system are expected to be complimentary to a neutron imaging diagnostic system already in place at the NIF. This paper describes initial efforts to design a gamma-ray imaging system for the NIF using the existing neutron imaging system as a baseline for study. Due to the cross-section and expected range of ablator areal densities, the gamma flux should be approximately 10(-3) of the neutron flux. For this reason, care must be taken to maximize the efficiency of the gamma-ray imaging system because it will be gamma starved. As with the neutron imager, use of pinholes and/or coded apertures are anticipated. Along with aperture and detector design, the selection of an appropriate scintillator is discussed. The volume of energy deposition of the interacting 4.44 MeV gamma-rays is a critical parameter limiting the imaging system spatial resolution. The volume of energy deposition is simulated with GEANT4, and plans to measure the volume of energy deposition experimentally are described. Results of tests on a pixellated LYSO scintillator are also presented.

The Gamma-ray Sky with Fermi

NASA Technical Reports Server (NTRS)

Thompson, David

2012-01-01

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

Trigger design for a gamma ray detector of HIRFL-ETF

NASA Astrophysics Data System (ADS)

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

2013-10-01

The Gamma Ray Array Detector (GRAD) is one subsystem of HIRFL-ETF (the External Target Facility (ETF) of the Heavy Ion Research Facility in Lanzhou (HIRFL)). It is capable of measuring the energy of gamma-rays with 1024 CsI scintillators in in-beam nuclear experiments. The GRAD trigger should select the valid events and reject the data from the scintillators which are not hit by the gamma-ray. The GRAD trigger has been developed based on the Field Programmable Gate Array (FPGAs) and PXI interface. It makes prompt trigger decisions to select valid events by processing the hit signals from the 1024 CsI scintillators. According to the physical requirements, the GRAD trigger module supplies 12-bit trigger information for the global trigger system of ETF and supplies a trigger signal for data acquisition (DAQ) system of GRAD. In addition, the GRAD trigger generates trigger data that are packed and transmitted to the host computer via PXI bus to be saved for off-line analysis. The trigger processing is implemented in the front-end electronics of GRAD and one FPGA of the GRAD trigger module. The logic of PXI transmission and reconfiguration is implemented in another FPGA of the GRAD trigger module. During the gamma-ray experiments, the GRAD trigger performs reliably and efficiently. The function of GRAD trigger is capable of satisfying the physical requirements.

Fermi gamma-ray imaging of a radio galaxy.

PubMed

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

2010-05-07

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

TIGRESS: TRIUMF-ISAC gamma-ray escape-suppressed spectrometer

NASA Astrophysics Data System (ADS)

Svensson, C. E.; Amaudruz, P.; Andreoiu, C.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Boston, A. J.; Chakrawarthy, R. S.; Chen, A. A.; Churchman, R.; Drake, T. E.; Finlay, P.; Garrett, P. E.; Grinyer, G. F.; Hackman, G.; Hyland, B.; Jones, B.; Kanungo, R.; Maharaj, R.; Martin, J. P.; Morris, D.; Morton, A. C.; Pearson, C. J.; Phillips, A. A.; Ressler, J. J.; Roy, R.; Sarazin, F.; Schumaker, M. A.; Scraggs, H. C.; Smith, M. B.; Starinsky, N.; Valiente-Dobón, J. J.; Waddington, J. C.; Watters, L. M.

2005-10-01

The TRIUMF-ISAC gamma-ray escape-suppressed spectrometer (TIGRESS) is a new γ-ray detector array being developed for use at TRIUMF's Isotope Separator and Accelerator (ISAC) radioactive ion beam facility. TIGRESS will comprise 12 32-fold segmented clover-type HPGe detectors coupled with 20-fold segmented modular Compton suppression shields and custom digital signal processing electronics. This paper provides an overview of the TIGRESS project and progress in its development to date.

Prompt gamma neutron activation analysis of toxic elements in radioactive waste packages.

PubMed

Ma, J-L; Carasco, C; Perot, B; Mauerhofer, E; Kettler, J; Havenith, A

2012-07-01

The French Alternative Energies and Atomic Energy Commission (CEA) and National Radioactive Waste Management Agency (ANDRA) are conducting an R&D program to improve the characterization of long-lived and medium activity (LL-MA) radioactive waste packages. In particular, the amount of toxic elements present in radioactive waste packages must be assessed before they can be accepted in repository facilities in order to avoid pollution of underground water reserves. To this aim, the Nuclear Measurement Laboratory of CEA-Cadarache has started to study the performances of Prompt Gamma Neutron Activation Analysis (PGNAA) for elements showing large capture cross sections such as mercury, cadmium, boron, and chromium. This paper reports a comparison between Monte Carlo calculations performed with the MCNPX computer code using the ENDF/B-VII.0 library and experimental gamma rays measured in the REGAIN PGNAA cell with small samples of nickel, lead, cadmium, arsenic, antimony, chromium, magnesium, zinc, boron, and lithium to verify the validity of a numerical model and gamma-ray production data. The measurement of a ∼20kg test sample of concrete containing toxic elements has also been performed, in collaboration with Forschungszentrum Jülich, to validate the model in view of future performance studies for dense and large LL-MA waste packages. Copyright © 2012 Elsevier Ltd. All rights reserved.

Development and Attestation of Gamma-Ray Measurement Methodologies for use by Rostekhnadzor Inspectors in the Russian Federation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeff Sanders

2006-09-01

Development and attestation of gamma-ray non-destructive assay measurement methodologies for use by inspectors of the Russian Federal Service for Environmental, Technological, and Nuclear Oversight (Rostekhnadzor, formerly Gosatomnadzor or GAN), as well as for use by Russian nuclear facilities, has been completed. Specifically, a methodology utilizing the gamma-ray multi group analysis (MGA) method for determining plutonium isotopic composition has been developed, while existing methodologies to determining uranium enrichment and isotopic composition have been revised to make them more appropriate to the material types and conditions present in nuclear facilities in the Russian Federation. This paper will discuss the development and revisionmore » of these methodologies, the metrological characteristics of the final methodologies, as well as the limitations and concerns specific to the utilization of these analysis methods in the Russian Federation.« less

KSC-08pd0645

NASA Image and Video Library

2008-03-05

KENNEDY SPACE CENTER, FLA. -- General Dynamics technicians in the Astrotech payload processing facility remove the protective cover over NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The space telescope will be moved to a work stand in the facility for a complete checkout of the scientific instruments aboard. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Kim Shiflett

Space astrophysics with large structures - CASES and P/OF. [Controls, Astrophysics, and Structures Experiment in Space and Pinhole/Occulter Facility

NASA Technical Reports Server (NTRS)

Hudson, Hugh S.; Davis, J. M.

1990-01-01

Space instruments for remote sensing, of the types used for astrophysics and solar-terrestrial physics among many disciplines, will grow to larger physical sizes in the future. The zero-g space environment does not inherently restrict such growth, because relatively lightweight structures can be used. Active servo control of the structures can greatly increase their size for a given mass. The Pinhole/Occulter Facility, a candidate Space Station attached payload, offers an example: it will achieve 0.2 arc s resolution by use of a 50-m baseline for coded-aperture telescopes for hard X-ray and gamma-ray imagers.

Multiwavelength Photometric and Spectropolarimetric Analysis of the FSRQ 3C 279

NASA Astrophysics Data System (ADS)

Patiño-Álvarez, V. M.; Fernandes, S.; Chavushyan, V.; López-Rodríguez, E.; León-Tavares, J.; Schlegel, E. M.; Carrasco, L.; Valdés, J.; Carramiñana, A.

2018-06-01

In this paper, we present light curves for 3C 279 over a time period of six years; from 2008 to 2014. Our multiwavelength data comprise 1 mm to gamma-rays, with additional optical polarimetry. Based on the behaviour of the gamma-ray light curve with respect to other bands, we identified three different activity periods. One of the activity periods shows anomalous behaviour with no gamma-ray counterpart associated with optical and NIR flares. Another anomalous activity period shows a flare in gamma-rays, 1 mm and polarization degree, however, it does not have counterparts in the UV continuum, optical and NIR bands. We find a significant overall correlation of the UV continuum emission, the optical and NIR bands. This correlation suggests that the NIR to UV continuum is co-spatial. We also find a correlation between the UV continuum and the 1 mm data, which implies that the dominant process in producing the UV continuum is synchrotron emission. The gamma-ray spectral index shows statistically significant variability and an anti-correlation with the gamma-ray luminosity. We demonstrate that the dominant gamma-ray emission mechanism in 3C 279 changes over time. Alternatively, the location of the gamma-ray emission zone itself may change depending on the activity state of the central engine.

Influence of gamma-ray skyshine on nuclear facilities design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohta, M.; Tsuji, M.; Kimura, Y.

1986-01-01

In safety analysis of nuclear facilities, skyshine dose rate at site boundary is one of the most important shielding design problems. For nuclear power stations in Japan, the skyshine dose rate at the site boundary has been specified not to exceed 5 mR/yr by the authorities, including total dose contribution from all structures on site, and this guide is commonly applied to other nuclear fuel cycle facilities. Therefore the design criterion dose of each structure on site is, considering plot planning, shielding condition, and so on, defined as a value <5 mR/yr. The purpose of this study is to investigatemore » how skyshine dose standards or other factors have an influence on the design of nuclear facilities, in a parametric survey of gamma-ray skyshine.« less

Gamma-ray imaging assay of cells 3-5 of the east cell line in the 235-F plutonium fuel form facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brand, A. D.; Aucott, T. J.; Diprete, D. P.

In August and September, 2016, scientists from the Savannah River National Laboratory (SRNL) took a series of gamma-ray imaging measurements through the cell windows in front of Cells 3-5 on the east line of the Plutonium Fuel Form (PuFF) Facility using an electrically cooled, high-purity germanium detector. A Germanium Gamma Ray Imager (GeGI) was utilized since it allowed for the location from which the radiation was being emitted to be identified by incoming gamma-ray energy. This measurement technique provided a tool which allowed for the relative concentration of Pu-238 to be mapped throughout each cell. The mapping and new assaymore » data were then used to update the model used in an assay discussed in a 2014 report (SRNL-STI-2014-00629) and to calculate a more accurate value for the holdup in each of the cells [1]. Note that the mapping and new assay data did not replace the previous assay data in the model. Rather, the mapping and new assay data provided additional details on source distribution, which supplemented the previous assay data.« less

A Giant Radio Flare from Cygnus X-3 with Associated Gamma-Ray Emission

NASA Technical Reports Server (NTRS)

Corbel, S.; Dubus, G.; Tomsick, J. A.; Szostek, A.; Corbet, R. H. D.; Miller-Jones, J. C. A.; Richards, J. L.; Pooley, G.; Trushkin, S.; Dubois, R.;

Gamma-Ray Spectroscopy at TRIUMF-ISAC: the New Frontier of Radioactive Ion Beam Research

NASA Astrophysics Data System (ADS)

Ball, G. C.; Andreoiu, C.; Austin, R. A. E.; Bandyopadhyay, D.; Becker, J. A.; Bricault, P.; Brown, N.; Chan, S.; Churchman, R.; Colosimo, S.; Coombes, H.; Cross, D.; Demand, G.; Drake, T. E.; Dombsky, M.; Ettenauer, S.; Finlay, P.; Furse, D.; Garnsworthy, A.; Garrett, P. E.; Green, K. L.; Grinyer, G. F.; Hyland, B.; Hackman, G.; Kanungo, R.; Kulp, W. D.; Lassen, J.; Leach, K. G.; Leslie, J. R.; Mattoon, C.; Melconian, D.; Morton, A. C.; Pearson, C. J.; Phillips, A. A.; Rand, E.; Sarazin, F.; Svensson, C. E.; Sumithrarachchi, S.; Schumaker, M. A.; Triambak, S.; Waddington, J. C.; Walker, P. M.; Williams, S. J.; Wood, J. L.; Wong, J.; Zganjar, E. F.

2009-03-01

High-resolution gamma-ray spectroscopy is essential to fully exploit the unique scientific opportunities at the next generation radioactive ion beam facilities such as the TRIUMF Isotope Separator and Accelerator (ISAC). At ISAC the 8π spectrometer and its associated auxiliary detectors is optimize for β-decay studies while TIGRESS an array of segmented clover HPGe detectors has been designed for studies with accelerated beams. This paper gives a brief overview of these facilities and also presents recent examples of the diverse experimental program carried out at the 8π spectrometer.

The Gamma-ray Universe through Fermi

NASA Technical Reports Server (NTRS)

Thompson, David J.

2012-01-01

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

Applications Using High Flux LCS gamma-ray Beams: Nuclear Security and Contributions to Fukushima

NASA Astrophysics Data System (ADS)

Fujiwara, Mamoru

2014-09-01

Nuclear nonproliferation and security are an important issue for the peaceful use of nuclear energy. Many countries now collaborate together for preventing serious accidents from nuclear terrorism. Detection of hidden long-lived radioisotopes and fissionable nuclides in a non-destructive manner is useful for nuclear safeguards and management of nuclear wastes as well as nuclear security. After introducing the present situation concerning the nuclear nonproliferation and security in Japan, we plan to show the present activities of JAEA to detect the hidden nuclear materials by means of the nuclear resonance fluorescence with energy-tunable, monochromatic gamma-rays generated by Laser Compton Scattering (LCS) with an electron beam. The energy recovery linac (ERL) machine is now under development with the KEK-JAEA collaboration for realizing the new generation of gamma-ray sources. The detection technologies of nuclear materials are currently developed using the existing electron beam facilities at Duke University and at NewSubaru. These developments in Japan will contribute to the nuclear security program in Japan and to the assay of melted nuclear fuels in the Fukushima Daiichi nuclear power plants.

Ultra-High Rate Measurements of Spent Fuel Gamma-Ray Emissions

NASA Astrophysics Data System (ADS)

Rodriguez, Douglas; Vandevender, Brent; Wood, Lynn; Glasgow, Brian; Taubman, Matthew; Wright, Michael; Dion, Michael; Pitts, Karl; Runkle, Robert; Campbell, Luke; Fast, James

2014-03-01

Presently there are over 200,000 irradiated spent nuclear fuel (SNF) assemblies in the world, each containing a concerning amount of weapons-usable material. Both facility operators and safeguards inspectors want to improve composition determination. Current measurements are expensive and difficult so new methods are developed through models. Passive measurements are limited since a few specific decay products and the associated down-scatter overwhelm the gamma rays of interest. Active interrogation methods produce gamma rays beyond 3 MeV, minimizing the impact of the passive emissions that drop off sharply above this energy. New devices like the Ultra-High Rate Germanium (UHRGe) detector are being developed to advance these novel measurement methods. Designed for reasonable resolution at 106 s-1 output rates (compared to ~ 1 - 10 e 3 s-1 standards), SNF samples were directly measured using UHRGe and compared to models. Model verification further enables using Los Alamos National Laboratory SNF assembly models, developed under the Next Generation Safeguards Initiative, to determine emission and signal expectations. Measurement results and future application requirements for UHRGe will be discussed.

Science with the Space Infrared Telescope Facility

NASA Technical Reports Server (NTRS)

Roellig, Thomas L.

2003-01-01

The Space Infrared Telescope Facility (SIRTF), the fourth and final member of NASA's series of Great Observatories, is scheduled to launch on April 15,2003. Together with the Hubbie Space Telescope, the Compton Gamma ray Telescope, and the Chandra X-Ray Telescope this series of observatories offers observational capabilities across the electromagnetic spectrum from the infrared to high-energy gamma rays. SIRTF is based on three focal plane instruments - an infrared spectrograph and two infrared imagers - coupled to a superfluid-helium cooled telescope to achieve unprecedented sensitivity from 3 to 180 microns. Although SIRTF is a powerful general-purpose infrared observatory, its design was based on the capability to address four broad science themes: (1) understanding the structure and composition of the early universe, (2) understanding the nature of brown dwarfs and super-planets, (3) probing protostellar, protoplanetary, and planetary debris disk systems, and (4) understanding the origin and structure of ultraluminous infrared galaxies and active galactic nuclei. This talk will address the design and capabilities of the SIRTF observatory, provide an overview of some of the initial science investigations planned by the SIRTF Guaranteed Time Observers, and give a brief overview of the General Observer proposal process.

Gamma-ray imaging system for real-time measurements in nuclear waste characterisation

NASA Astrophysics Data System (ADS)

Caballero, L.; Albiol Colomer, F.; Corbi Bellot, A.; Domingo-Pardo, C.; Leganés Nieto, J. L.; Agramunt Ros, J.; Contreras, P.; Monserrate, M.; Olleros Rodríguez, P.; Pérez Magán, D. L.

2018-03-01

A compact, portable and large field-of-view gamma camera that is able to identify, locate and quantify gamma-ray emitting radioisotopes in real-time has been developed. The device delivers spectroscopic and imaging capabilities that enable its use it in a variety of nuclear waste characterisation scenarios, such as radioactivity monitoring in nuclear power plants and more specifically for the decommissioning of nuclear facilities. The technical development of this apparatus and some examples of its application in field measurements are reported in this article. The performance of the presented gamma-camera is also benchmarked against other conventional techniques.

Thermal Neutron Die-Way-Time Studies for P and DGNAA of Radioactive Waste Drums at the MEDINA Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mildenberger, Frank; Mauerhofer, Eric

2015-07-01

In Germany, radioactive waste with negligible heat production has to pass through a process of quality checking in order to check its conformance with national regulations prior to its transport, intermediate storage and final disposal. Additionally to its radioactive components, the waste may contain non-radioactive chemically toxic substances that can adversely affect human health and pollute the environment, especially the ground water. After an adequate decay time, the waste radioactivity will become harmless but the non-radioactive substances will persist over time. In principle, these hazardous substances may be quantified from traceability and quality controls performed during the production of themore » waste packages. As a consequence, a research and development program was initiated in 2007 with the aim to develop a nondestructive analytical technique for radioactive waste packages based on prompt and delayed gamma neutron activation analysis (P and DGNAA) employing a DT-neutron generator in pulsed mode. In a preliminary study it was experimentally demonstrated that P and DGNAA is suitable to determine the chemical composition of large samples. In 2010 a facility called MEDINA (Multi Element Detection based on Instrumental Neutron Activation) was developed for the qualitative and quantitative determination of nonradioactive, toxic elements and substances in 200-l steel drums. The determination of hazardous substances and elements is generally achieved measuring the prompt gamma-rays induced by thermal neutrons. Additional information about the composition of the waste matrix could be derived measuring the delayed gamma-rays from short life activation products. However a sensitive detection of these delayed gamma-rays requires that thermal neutrons have almost vanished. Therefore, the thermal neutron die-away-time has to be known in order to achieve an optimal discrimination between prompt and delayed gamma-ray spectra acquisition. Measurements Thermal neutron die-away times have been determined for the following cases: a) the empty chamber, b ) an empty 200-l steel drum, for a 200-l steel drum filled c) with concrete d) with polyethylene and e) with a mixture of polyethylene and concrete by measuring the prompt-gamma ray count rate of relevant isotopes like of {sup 1}H, {sup 10}B, {sup 12}C, {sup 28}Si, {sup 35}Cl, {sup 40}Ca and {sup 56}Fe which are emitted from different parts of the facility and the sample. Additionally, the average die-away-time was determined from the total detector count rate. The neutron generator was operated with a neutron emission of 8x10{sup 7} n.s{sup -1}, a neutron pulse with a length of 250 μs and a repetition time of 5 ms. The spectra were acquired between the neutron pulses over t{sub c}=500 μs after a pre-defined waiting time t{sub D} (multiple of 500 μs). The thermal neutron die-away time was ranging between 0.9 ms and 5 ms according to the sample composition. As an example the measured thermal neutron die-away-time Λ [μs] of a drum filled with concrete is presented. Detailed results of this study will be presented and discussed. (authors)« less

Highlights of GeV Gamma-Ray Astronomy

NASA Technical Reports Server (NTRS)

Thompson, David J.

2010-01-01

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

Research in cosmic and gamma ray astrophysics

NASA Technical Reports Server (NTRS)

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

1989-01-01

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

Swift detection of increased X-ray activity from gamma-ray flaring blazar PKS 1424-41

NASA Astrophysics Data System (ADS)

Ciprini, Stefano; Cutini, Sara

2013-01-01

Following enduring gamma-ray flaring activity of the flat spectrum radio quasar PKS 1424-41 (also known as 2FGL J1428.0-4206, Nolan et al. 2012, ApJS, 199, 31) detected by Fermi LAT during January 2013, two Swift target of opportunity observations were performed on January 24 and 27, 2013. Recent gamma-ray and X-ray flaring activity from the source was observed on January 6 and January 7 (ATel#4714 and ATel #4717).

KSC-08pd0643

NASA Image and Video Library

2008-03-05

KENNEDY SPACE CENTER, FLA. -- A General Dynamics technician in the Astrotech payload processing facility releases a corner of the protective cover over NASA's Gamma-Ray Large Area Space Telescope, or GLAST, after its arrival. GLAST will be moved to a work stand in the facility for a complete checkout of the telescope's scientific instruments. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Kim Shiflett

X-ray remote sensing and in-situ spectroscopy for planetary exploration missions and gamma-ray remote sensing and in-situ spectroscopy for planetary exploration missions

NASA Technical Reports Server (NTRS)

Mahdavi, M.; Giboni, K. L.; Vajda, S.; Schweitzer, J.

1994-01-01

Detectors that will be used for planetary missions must have their responses calibrated in a reproducible manner. A calibration facility is being constructed at Schlumberger-Doll Research for gamma and x ray detectors. With this facility the detector response can be determined in an invariant and reproducible fashion. Initial use of the facility is expected for the MARS94 detectors. Work is continuing to better understand the rare earth oxyorthosilicates and to define their characteristics. This will allow a better use of these scintillators for planetary missions. In a survey of scintillating materials two scintillators were identified as promising candidates besides GSO, LSO, and YSO. These are CdWO4 and CsI(Tl). It will be investigated if a detector with a better overall performance can be assembled with various photon converters. Considerable progress was achieved in photomultiplier design. The length of an 1 inch diameter PMT could be reduced from 4.2 to 2.5 inches without performance degradation. This technology is being employed in the gamma ray detector for the NEAR project. A further weight and size reduction of the detector package can be achieved with miniaturized integrated power supplies.

Research in particle and gamma-ray astrophysics

NASA Technical Reports Server (NTRS)

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

1988-01-01

Research activities in cosmic rays, gamma rays, and astrophysical plasmas are covered. Each activity is described, followed by a bibliography. The research program is directed toward the investigation of the astrophysical aspects of cosmic rays and gamma rays and of the radiation and electromagnetic field environment of the earth and other planets. These investigations were performed by means of energetic particle and photon detector systems flown on spacecraft and balloons.

Internal absorption of gamma-rays in relativistic blobs of active galactic nuclei

NASA Astrophysics Data System (ADS)

Sitarek, Julian; Bednarek, Wlodek

2007-06-01

We investigate the production of gamma-rays in the inverse Compton (IC) scattering process by leptons accelerated inside relativistic blobs in jets of active galactic nuclei. Leptons are injected homogeneously inside the spherical blob and initiate IC e ± pair cascade in the synchrotron radiation (produced by the same population of leptons, SSC model), provided that the optical depth for gamma-rays is larger than unity. It is shown that for likely parameters internal absorption of gamma-rays has to be important. We suggest that new type of blazars might be discovered by the future simultaneous X-ray and γ-ray observations, showing peak emissions in the hard X-rays, and in the GeV γ-rays. Moreover, the considered scenario might be also responsible for the orphan X-ray flares recently reported from BL Lac type active galaxies.

The solar physics Shuttle/Spacelab program and its relationship to studies of the flare build-up

NASA Technical Reports Server (NTRS)

Neupert, W. M.

1976-01-01

The main phase of solar physics (including flare-buildup) research on Shuttle/Spacelab during the 1980s centers around the use of facility instruments for multiple-user, multiple flight operations. Three main facilities are being considered: a meter-class optical telescope for visible and near-UV wavelengths, an EUV/XUV/soft X-ray facility, and a hard X-ray imaging facility (including a full-sun 5-600 keV spectrometer, a nuclear gamma ray spectrometer, and an X-ray polarimeter for the 5-100 keV range). Smaller instruments designed for specific observations and other classes of instruments such as solar monitors that are not on the facility level are also being considered.

Multiwavelength Study of Gamma-Ray Bright Blazars

NASA Astrophysics Data System (ADS)

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

2011-01-01

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

Three-dimensional reconstruction of neutron, gamma-ray, and x-ray sources using spherical harmonic decomposition

NASA Astrophysics Data System (ADS)

Volegov, P. L.; Danly, C. R.; Fittinghoff, D.; Geppert-Kleinrath, V.; Grim, G.; Merrill, F. E.; Wilde, C. H.

2017-11-01

Neutron, gamma-ray, and x-ray imaging are important diagnostic tools at the National Ignition Facility (NIF) for measuring the two-dimensional (2D) size and shape of the neutron producing region, for probing the remaining ablator and measuring the extent of the DT plasmas during the stagnation phase of Inertial Confinement Fusion implosions. Due to the difficulty and expense of building these imagers, at most only a few two-dimensional projections images will be available to reconstruct the three-dimensional (3D) sources. In this paper, we present a technique that has been developed for the 3D reconstruction of neutron, gamma-ray, and x-ray sources from a minimal number of 2D projections using spherical harmonics decomposition. We present the detailed algorithms used for this characterization and the results of reconstructed sources from experimental neutron and x-ray data collected at OMEGA and NIF.

The TRIUMF nuclear structure program and TIGRESS

NASA Astrophysics Data System (ADS)

Garrett, P. E.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Becker, J. A.; Boston, A. J.; Boston, H. C.; Chakrawarthy, R. S.; Churchman, R.; Cline, D.; Cooper, R. J.; Cross, D.; Dashdorj, D.; Demand, G. A.; Dimmock, M. R.; Drake, T.; Finlay, P.; Gagnon, K.; Gallant, A. T.; Green, K. L.; Grint, A. N.; Grinyer, G. F.; Hackman, G.; Harkness, L. J.; Hayes, A. B.; Kanungo, R.; Kulp, W. D.; Leach, K. G.; Lee, G.; Leslie, J. R.; Maharaj, R.; Martin, J.-P.; Mattoon, C.; Mills, W. J.; Morton, A. C.; Nelson, L.; Newman, O.; Nolan, P. J.; Padilla-Rodal, E.; Pearson, C. J.; Phillips, A. A.; Porter-Peden, M.; Ressler, J. J.; Ruiz, C.; Sarazin, F.; Schumaker, M. A.; Scraggs, D. P.; Strange, M. D.; Subramanian, M.; Svensson, C. E.; Waddington, J. C.; Wan, J.; Whitbeck, A.; Williams, S. J.; Wood, J. L.; Wong, J. C.; Wu, C. Y.; Zganjar, E. F.

2007-08-01

The isotope separator and accelerator (ISAC) facility located at the TRIUMF laboratory in Vancouver, Canada, is one of the world's most advanced isotope separator on-line-type radioactive ion beam facilities. An extensive γ-ray spectroscopy programme at ISAC is centred around two major research facilities: (i) the 8π γ-ray spectrometer for β-delayed γ-ray spectroscopy experiments with the low-energy beams from ISAC-I, and (ii) the next generation TRIUMF-ISAC gamma-ray escape suppressed spectrometer (TIGRESS) for in-beam experiments with the accelerated radioactive-ion beams. An overview of these facilities and recent results from the diverse programme of nuclear structure and fundamental interaction studies they support is presented.

The Next Century Astrophysics Program

NASA Technical Reports Server (NTRS)

Swanson, Paul N.

1991-01-01

The Astrophysics Division within the NASA Office of Space Science and Applications (OSSA) has defined a set of major and moderate missions that are presently under study for flight sometime within the next 20 years. These programs include the: Advanced X Ray Astrophysics Facility; X Ray Schmidt Telescope; Nuclear Astrophysics Experiment; Hard X Ray Imaging Facility; Very High Throughput Facility; Gamma Ray Spectroscopy Observatory; Hubble Space Telescope; Lunar Transit Telescope; Astrometric Interferometer Mission; Next Generation Space Telescope; Imaging Optical Interferometer; Far Ultraviolet Spectroscopic Explorer; Gravity Probe B; Laser Gravity Wave Observatory in Space; Stratospheric Observatory for Infrared Astronomy; Space Infrared Telescope Facility; Submillimeter Intermediate Mission; Large Deployable Reflector; Submillimeter Interferometer; and Next Generation Orbiting Very Long Baseline Interferometer.

Future Hard X-ray and Gamma-Ray Missions

NASA Astrophysics Data System (ADS)

Krawczynski, Henric; Physics of the Cosmos (PCOS) Gamma Ray Science Interest Group (GammaSIG) Team

2017-01-01

With four major NASA and ESA hard X-ray and gamma-ray missions in orbit (Swift, NuSTAR, INTEGRAL, and Fermi) hard X-ray and gamma-ray astronomy is making major contributions to our understanding of the cosmos. In this talk, I will summarize the current and upcoming activities of the Physics of the Cosmos Gamma Ray Science Interest Group and highlight a few of the future hard X-ray and gamma-ray mission discussed by the community. HK thanks NASA for the support through the awards NNX14AD19G and NNX16AC42G and for PCOS travel support.

A US coordination Facility for the Spectrum-X-Gamma Observatory

NASA Technical Reports Server (NTRS)

Forman, W.; West, Donald (Technical Monitor)

2001-01-01

We have completed our efforts in support of the Spectrum X Gamma mission under a NASA grant. These activities have included direct support to the mission, developing unifying tools applicable to SXG and other X-ray astronomy missions, and X-ray astronomy research to maintain our understanding of the importance and relevance of SXG to the field. SXG provides: 1) Simultaneous Multiwavelength Capability; 2) Large Field of View High Resolution Imaging Spectroscopy; 3) Sensitive Polarimetry with SXRP (Stellar X-Ray Polarimeter). These capabilities will ensure the fulfillment of the following objectives: understanding the accretion dynamics and the importance of reprocessing, upscattering, and disk viscosity around black holes; studying cluster mergers; spatially resolving cluster cooling flows to detect cooling gas; detecting cool gas in cluster outskirts in absorption; mapping gas in filaments around clusters; finding the 'missing' baryons in the Universe; determining the activity history of the black hole in the Galactic Center of our own central black hole; determining pulsar beam geometry; searching for the Lense-Thirring effect in black hole sources; constraining emission mechanisms and accretion geometry in AGN.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barty, Christopher P.J.

Lasers and laser-based sources are now routinely used to control and manipulate nuclear processes, e.g. fusion, fission and resonant nuclear excitation. Two such “nuclear photonics” activities with the potential for profound societal impact will be reviewed in this presentation: the pursuit of laser-driven inertial confinement fusion at the National Ignition Facility and the development of laser-based, mono-energetic gamma-rays for isotope-specific detection, assay and imaging of materials.

Next generation gamma-ray Cherenkov detectors for the National Ignition Facility.

PubMed

Herrmann, H W; Kim, Y H; McEvoy, A M; Zylstra, A B; Young, C S; Lopez, F E; Griego, J R; Fatherley, V E; Oertel, J A; Stoeffl, W; Khater, H; Hernandez, J E; Carpenter, A; Rubery, M S; Horsfield, C J; Gales, S; Leatherland, A; Hilsabeck, T; Kilkenny, J D; Malone, R M; Hares, J D; Milnes, J; Shmayda, W T; Stoeckl, C; Batha, S H

2016-11-01

The newest generation of Gas Cherenkov Detector (GCD-3) employed in Inertial Confinement Fusion experiments at the Omega Laser Facility has provided improved performance over previous generations. Comparison of reaction histories measured using two different deuterium-tritium fusion products, namely gamma rays using GCD and neutrons using Neutron Temporal Diagnostic (NTD), have provided added credibility to both techniques. GCD-3 is now being brought to the National Ignition Facility (NIF) to supplement the existing Gamma Reaction History (GRH-6m) located 6 m from target chamber center (TCC). Initially it will be located in a reentrant well located 3.9 m from TCC. Data from GCD-3 will inform the design of a heavily-shielded "Super" GCD to be located as close as 20 cm from TCC. It will also provide a test-bed for faster optical detectors, potentially lowering the temporal resolution from the current ∼100 ps state-of-the-art photomultiplier tubes (PMT) to ∼10 ps Pulse Dilation PMT technology currently under development.

Pulsars at the Highest Energies: Questions for AGILE, Fermi (GLAST) and Atmospheric Cherenkov Telescopes

NASA Technical Reports Server (NTRS)

Thompson, D.J.

2008-01-01

Observational studies of gamma-ray pulsars languished in recent years, while theoretical studies made significant strides. Now, with new and improved gamma-ray telescopes coming online, opportunities present themselves for dramatic improvements in our understanding of these objects. The new facilities and better modeling of processes at work in high-energy pulsars should address a number of important open questions, some of which are summarized.

High brightness gamma-ray production at Fermilab Accelerator Science and Technology (FAST) facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mihalcea, Daniel; Jacobson, B.; Murokh, A.

Electron beams with energies of the order of a few 100's of MeV and low transverse emittance, in combination with powerful infrared lasers, allow for the production of high quality gamma rays through Inverse Compton Scattering (ICS). At Fermilab Accelerator Science and Technology (FAST) facility, a 300 MeV beam will be used to generate gamma rays with maximum photon energies of up to ~1.5 MeV and brightness of the order of 10 21 photons/[s-(mm-mrad) 2- 0.1%BW]. Due to the low electron-beam transverse emittance, the relative bandwidth of the scattered radiation is expected to be ≤ 1%. A key challenge towardmore » the production of high radiation dose and brightness is to enhance the energy of the infrared 3 ps laser pulses to the joule level. Finally, in this contribution, we present the plans for the experimental setup, along with comprehensive numerical simulations of the ICS process.« less

Upgrades at the Duke Free Electron Laser Laboratory

NASA Astrophysics Data System (ADS)

Howell, Calvin R.

2004-11-01

Major upgrades to the storage-ring based photon sources at the Duke Free Electron Laser Laboratory (DFELL) are underway. The photon sources at the DFELL are well suited for research in the areas of medicine, biophysics, accelerator physics, nuclear physics and material science. These upgrades, which will be completed by the summer 2006, will significantly enhance the capabilities of the ultraviolet (UV) free-electron laser (FEL) and the high intensity gamma-ray source (HIGS). The HIGS is a relatively new research facility at the DFELL that is operated jointly by the DFELL and the Triangle Universities Nuclear Laboratory. The gamma-ray beam is produced by Compton back scattering of the UV photons inside the FEL optical cavity off the circulating electrons in the storage ring. The gamma-ray beam is 100% polarized and its energy resolution is selected by collimation. The capabilities of the upgraded facility will be described, the status of the upgrades will be summarized, and the proposed first-generation research program at HIGS will be presented.

High brightness gamma-ray production at Fermilab Accelerator Science and Technology (FAST) facility

DOE PAGES

Mihalcea, Daniel; Jacobson, B.; Murokh, A.; ...

2017-03-01

Electron beams with energies of the order of a few 100's of MeV and low transverse emittance, in combination with powerful infrared lasers, allow for the production of high quality gamma rays through Inverse Compton Scattering (ICS). At Fermilab Accelerator Science and Technology (FAST) facility, a 300 MeV beam will be used to generate gamma rays with maximum photon energies of up to ~1.5 MeV and brightness of the order of 10 21 photons/[s-(mm-mrad) 2- 0.1%BW]. Due to the low electron-beam transverse emittance, the relative bandwidth of the scattered radiation is expected to be ≤ 1%. A key challenge towardmore » the production of high radiation dose and brightness is to enhance the energy of the infrared 3 ps laser pulses to the joule level. Finally, in this contribution, we present the plans for the experimental setup, along with comprehensive numerical simulations of the ICS process.« less

Fermi Gamma-Ray Space Telescope: Science Highlights for the First 8 Months

NASA Technical Reports Server (NTRS)

Moiseev, Alexander

2010-01-01

The Fermi Gamma-ray Space Telescope was launched on June 11, 2008 and since August 2008 has successfully been conducting routine science observations of high energy phenomena in the gamma-ray sky. A number of exciting discoveries have been made during its first year of operation, including blazar flares, high-energy gamma-ray bursts, and numerous new,gamma-ray sources of different types, among them pulsars and Active Galactic Nuclei (AGN). fermi-LAT also performed accurate mea.<;urement of the diffuse gamma-radiation which clarifies the Ge V excess reported by EGRET almost 10 years ago, high precision measurement of the high energy electron spectrum, and other observations. An overview of the observatory status and recent results as of April 30, 2009, are presented. Key words: gamma-ray astronomy, cosmic rays, gamma-ray burst, pulsar, blazar. diffuse gamma-radiation

Fermi Gamma-Ray Space Telescope: Highlights of the GeV Sky

NASA Technical Reports Server (NTRS)

Thomspon, D. J.

2011-01-01

Because high-energy gamma rays can be produced by processes that also produce neutrinos. the gamma-ray survey of the sky by the Fermi Gamma-ray Space Telescope offers a view of potenl ial targds for neutrino observations. Gamma-ray bursts. active galactic nuclei, and supernova remnants are all sites where hadronic, neutrino-producing interactions are plausible. Pulsars, pulsar wind nebulae, and binary sources are all phenomena that reveal leptonic particle acceleration through their gamma-ray emission. \\Vhile important to gamma-ray astrophysics. such sources are of less interest to neutrino studies. This talk will present a broad overview of the constantly changing sky seen with the Large Area Telescope (LAT) on the Fermi spacecraft.

High Energy Astronomy Observatory (HEAO)

NASA Image and Video Library

1977-06-01

This photograph is of the High Energy Astronomy Observatory (HEAO)-2 telescope being checked by engineers in the X-Ray Calibration Facility at the Marshall Space Flight Center (MSFC). The MSFC was heavily engaged in the technical and scientific aspects, testing and calibration, of the HEAO-2 telescope. The HEAO-2 was the first imaging and largest x-ray telescope built to date. The X-Ray Calibration Facility was built in 1976 for testing MSFC's HEAO-2. The facility is the world's largest, most advanced laboratory for simulating x-ray emissions from distant celestial objects. It produced a space-like environment in which components related to x-ray telescope imaging are tested and the quality of their performance in space is predicted. The original facility contained a 1,000-foot long by 3-foot diameter vacuum tube (for the x-ray path) cornecting an x-ray generator and an instrument test chamber. Recently, the facility was upgraded to evaluate the optical elements of NASA's Hubble Space Telescope, Chandra X-Ray Observatory and Compton Gamma-Ray Observatory.

Overview of the Chandra X-Ray Observatory Facility

NASA Technical Reports Server (NTRS)

Weisskopf, M. C.; Six, N. Frank (Technical Monitor)

2002-01-01

The Chandra X-Ray Observatory (originally called the Advanced X-Ray Astrophysics Facility - AXAF) is the X-Ray component of NASA's "Great Observatory" Program. Chandra is a NASA facility that provides scientific data to the international astronomical community in response to scientific proposals for its use. The Observatory is the product of the efforts of many organizations in the United States and Europe. The Great Observatories also include the Hubble Space Telescope for space-based observations of astronomical objects primarily in the visible portion of the electromagnetic spectrum, the now defunct Compton Gamma- Ray Observatory that was designed to observe gamma-ray emission from astronomical objects, and the soon-to-be-launched Space Infrared Telescope Facility (SIRTF). The Chandra X-Ray Observatory (hereafter CXO) is sensitive to X-rays in the energy range from below 0.1 to above 10.0 keV corresponding to wavelengths from 12 to 0.12 nanometers. The relationship among the various parts of the electromagnetic spectrum, sorted by characteristic temperature and the corresponding wavelength, is illustrated. The German physicist Wilhelm Roentgen discovered what he thought was a new form of radiation in 1895. He called it X-radiation to summarize its properties. The radiation had the ability to pass through many materials that easily absorb visible light and to free electrons from atoms. We now know that X-rays are nothing more than light (electromagnetic radiation) but at high energies. Light has been given many names: radio waves, microwaves, infrared, visible, ultraviolet, X-ray and gamma radiation are all different forms. Radio waves are composed of low energy particles of light (photons). Optical photons - the only photons perceived by the human eye - are a million times more energetic than the typical radio photon, whereas the energies of X-ray photons range from hundreds to thousands of times higher than that of optical photons. Very low temperature systems (hundreds of degrees below zero Celsius) produce low energy radio and microwave photons, whereas cool bodies like our own (about 30 degrees Celsius) produce infrared radiation. Very high temperatures (millions of degrees Celsius) are one way of producing X-rays.

Future prospects for gamma-ray

NASA Technical Reports Server (NTRS)

Fichtel, C.

1980-01-01

Astrophysical phenomena discussed are: the very energetic and nuclear processes associated with compact objects; astrophysical nucleo-synthesis; solar particle acceleration; the chemical composition of the planets and other bodies of the solar system; the structure of our galaxy; the origin and dynamic pressure effects of the cosmic rays; the high energy particles and energetic processes in other galaxies, especially active ones; and the degree of matter antimater symmetry of the universe. The gamma ray results of GAMMA-I, the gamma ray observatory, the gamma ray burst network, solar polar, and very high energy gamma ray telescopes on the ground provide justification for more sophisticated telescopes.

NRF Based Nondestructive Inspection System for SNM by Using Laser-Compton-Backscattering Gamma-Rays

NASA Astrophysics Data System (ADS)

Ohgaki, H.; Omer, M.; Negm, H.; Daito, I.; Zen, H.; Kii, T.; Masuda, K.; Hori, T.; Hajima, R.; Hayakawa, T.; Shizuma, T.; Kando, M.

2015-10-01

A non-destructive inspection system for special nuclear materials (SNMs) hidden in a sea cargo has been developed. The system consists of a fast screening system using neutron generated by inertial electrostatic confinement (IEC) device and an isotope identification system using nuclear resonance fluorescence (NRF) measurements with laser Compton backscattering (LCS) gamma-rays has been developed. The neutron flux of 108 n/sec has been achieved by the IEC in static mode. We have developed a modified neutron reactor noise analysis method to detect fission neutron in a short time. The LCS gamma-rays has been generated by using a small racetrack microtoron accelerator and an intense sub-nano second laser colliding head-on to the electron beam. The gamma-ray flux has been achieved more than 105 photons/s. The NRF gamma-rays will be measured using LaBr3(Ce) scintillation detector array whose performance has been measured by NRF experiment of U-235 in HIGS facility. The whole inspection system has been designed to satisfy a demand from the sea port.

Radiation Characterization Summary: ACRR Polyethylene-Lead-Graphite (PLG) Bucket Located in the Central Cavity on the 32-Inch Pedestal at the Core Centerline (ACRR-PLG-CC-32-cl).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parma, Edward J.,; Vehar, David W.; Lippert, Lance L.

2015-06-01

This document presents the facility-recommended characterization of the neutron, prompt gamma-ray, and delayed gamma-ray radiation fields in the Annular Core Research Reactor (ACRR) for the polyethylene-lead-graphite (PLG) bucket in the central cavity on the 32-inch pedestal at the core centerline. The designation for this environment is ACRR-PLG-CC-32-cl. The neutron, prompt gamma-ray, and delayed gamma-ray energy spectra, uncertainties, and covariance matrices are presented as well as radial and axial neutron and gamma-ray fluence profiles within the experiment area of the bucket. Recommended constants are given to facilitate the conversion of various dosimetry readings into radiation metrics desired by experimenters. Representative pulsemore » operations are presented with conversion examples. Acknowledgements The authors wish to thank the Annular Core Research Reactor staff and the Radiation Metrology Laboratory staff for their support of this work. Also thanks to David Ames for his assistance in running MCNP on the Sandia parallel machines.« less

The structure, logic of operation and distinctive features of the system of triggers and counting signals formation for gamma-telescope GAMMA-400

NASA Astrophysics Data System (ADS)

Topchiev, N. P.; Galper, A. M.; Arkhangelskiy, A. I.; Arkhangelskaja, I. V.; Kheymits, M. D.; Suchkov, S. I.; Yurkin, Y. T.

2017-01-01

Scientific project GAMMA-400 (Gamma Astronomical Multifunctional Modular Apparatus) relates to the new generation of space observatories intended to perform an indirect search for signatures of dark matter in the cosmic-ray fluxes, measurements of characteristics of diffuse gamma-ray emission and gamma-rays from the Sun during periods of solar activity, gamma-ray bursts, extended and point gamma-ray sources, electron/positron and cosmic-ray nuclei fluxes up to TeV energy region by means of the GAMMA-400 gamma-ray telescope represents the core of the scientific complex. The system of triggers and counting signals formation of the GAMMA-400 gamma-ray telescope constitutes the pipelined processor structure which collects data from the gamma-ray telescope subsystems and produces summary information used in forming the trigger decision for each event. The system design is based on the use of state-of-the-art reconfigurable logic devices and fast data links. The basic structure, logic of operation and distinctive features of the system are presented.

Fermi LAT detection of increased gamma-ray activity from blazar S5 0716+71

NASA Astrophysics Data System (ADS)

Buson, S.

2014-04-01

The Large Area Telescope (LAT), one of two instruments on-board the Fermi Gamma-ray Space Telescope, has observed an increase in gamma-ray activity from a source positionally coincident with the BL Lac object S5 0716+71 (also known as 2FGL J0721.9+7120, Nolan et al. ...

SU-G-IeP4-12: Performance of In-111 Coincident Gamma-Ray Counting: A Monte Carlo Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pahlka, R; Kappadath, S; Mawlawi, O

2016-06-15

Purpose: The decay of In-111 results in a non-isotropic gamma-ray cascade, which is normally imaged using a gamma camera. Creating images with a gamma camera using coincident gamma-rays from In-111 has not been previously studied. Our objective was to explore the feasibility of imaging this cascade as coincidence events and to determine the optimal timing resolution and source activity using Monte Carlo simulations. Methods: GEANT4 was used to simulate the decay of the In-111 nucleus and to model the gamma camera. Each photon emission was assigned a timestamp, and the time delay and angular separation for the second gamma-ray inmore » the cascade was consistent with the known intermediate state half-life of 85ns. The gamma-rays are transported through a model of a Siemens dual head Symbia “S” gamma camera with a 5/8-inch thick crystal and medium energy collimators. A true coincident event was defined as a single 171keV gamma-ray followed by a single 245keV gamma-ray within a specified time window (or vice versa). Several source activities (ranging from 10uCi to 5mCi) with and without incorporation of background counts were then simulated. Each simulation was analyzed using varying time windows to assess random events. The noise equivalent count rate (NECR) was computed based on the number of true and random counts for each combination of activity and time window. No scatter events were assumed since sources were simulated in air. Results: As expected, increasing the timing window increased the total number of observed coincidences albeit at the expense of true coincidences. A timing window range of 200–500ns maximizes the NECR at clinically-used source activities. The background rate did not significantly alter the maximum NECR. Conclusion: This work suggests coincident measurements of In-111 gamma-ray decay can be performed with commercial gamma cameras at clinically-relevant activities. Work is ongoing to assess useful clinical applications.« less

Estimating irradiated nuclear fuel characteristics by nonlinear multivariate regression of simulated gamma-ray emissions

NASA Astrophysics Data System (ADS)

Åberg Lindell, M.; Andersson, P.; Grape, S.; Håkansson, A.; Thulin, M.

2018-07-01

In addition to verifying operator declared parameters of spent nuclear fuel, the ability to experimentally infer such parameters with a minimum of intrusiveness is of great interest and has been long-sought after in the nuclear safeguards community. It can also be anticipated that such ability would be of interest for quality assurance in e.g. recycling facilities in future Generation IV nuclear fuel cycles. One way to obtain information regarding spent nuclear fuel is to measure various gamma-ray intensities using high-resolution gamma-ray spectroscopy. While intensities from a few isotopes obtained from such measurements have traditionally been used pairwise, the approach in this work is to simultaneously analyze correlations between all available isotopes, using multivariate analysis techniques. Based on this approach, a methodology for inferring burnup, cooling time, and initial fissile content of PWR fuels using passive gamma-ray spectroscopy data has been investigated. PWR nuclear fuels, of UOX and MOX type, and their gamma-ray emissions, were simulated using the Monte Carlo code Serpent. Data comprising relative isotope activities was analyzed with decision trees and support vector machines, for predicting fuel parameters and their associated uncertainties. From this work it may be concluded that up to a cooling time of twenty years, the 95% prediction intervals of burnup, cooling time and initial fissile content could be inferred to within approximately 7 MWd/kgHM, 8 months, and 1.4 percentage points, respectively. An attempt aiming to estimate the plutonium content in spent UOX fuel, using the developed multivariate analysis model, is also presented. The results for Pu mass estimation are promising and call for further studies.

Fermi: The Gamma-Ray Large Area Telescope Mission Status

NASA Technical Reports Server (NTRS)

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.

Fermi: The Gamma-Ray Large Area Space Telescope Mission Status

NASA Technical Reports Server (NTRS)

McEnery, Julie E

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 a population of pulsars pulsing only in gamma rays; the detection of photons up to 10s of gigaelectronvolts 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 super-symmetric 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.

Fermi: The Gamma-Ray Large Area Telescope

NASA Technical Reports Server (NTRS)

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.

Fermi: The Gamma-Ray Large Area Telescope

NASA Technical Reports Server (NTRS)

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 10 seconds of gigaelectronvolts 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 super-symmetric 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.

Fermi: The Gamma-Ray Large Area Space Telescope

NASA Technical Reports Server (NTRS)

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.

Evaluation of prompt gamma-ray data and nuclear structure of niobium-94 with statistical model calculations

NASA Astrophysics Data System (ADS)

Turkoglu, Danyal

Precise knowledge of prompt gamma-ray intensities following neutron capture is critical for elemental and isotopic analyses, homeland security, modeling nuclear reactors, etc. A recently-developed database of prompt gamma-ray production cross sections and nuclear structure information in the form of a decay scheme, called the Evaluated Gamma-ray Activation File (EGAF), is under revision. Statistical model calculations are useful for checking the consistency of the decay scheme, providing insight on its completeness and accuracy. Furthermore, these statistical model calculations are necessary to estimate the contribution of continuum gamma-rays, which cannot be experimentally resolved due to the high density of excited states in medium- and heavy-mass nuclei. Decay-scheme improvements in EGAF lead to improvements to other databases (Evaluated Nuclear Structure Data File, Reference Input Parameter Library) that are ultimately used in nuclear-reaction models to generate the Evaluated Nuclear Data File (ENDF). Gamma-ray transitions following neutron capture in 93Nb have been studied at the cold-neutron beam facility at the Budapest Research Reactor. Measurements have been performed using a coaxial HPGe detector with Compton suppression. Partial gamma-ray production capture cross sections at a neutron velocity of 2200 m/s have been deduced relative to that of the 255.9-keV transition after cold-neutron capture by 93Nb. With the measurement of a niobium chloride target, this partial cross section was internally standardized to the cross section for the 1951-keV transition after cold-neutron capture by 35Cl. The resulting (0.1377 +/- 0.0018) barn (b) partial cross section produced a calibration factor that was 23% lower than previously measured for the EGAF database. The thermal-neutron cross sections were deduced for the 93Nb(n,gamma ) 94mNb and 93Nb(n,gamma) 94gNb reactions by summing the experimentally-measured partial gamma-ray production cross sections associated with the ground-state transitions below the 396-keV level and combining that summation with the contribution to the ground state from the quasi-continuum above 396 keV, determined with Monte Carlo statistical model calculations using the DICEBOX computer code. These values, sigmam and sigma 0, were (0.83 +/- 0.05) b and (1.16 +/- 0.11) b, respectively, and found to be in agreement with literature values. Comparison of the modeled population and experimental depopulation of individual levels confirmed tentative spin assignments and suggested changes where imbalances existed.

An airport cargo inspection system based on X-ray and thermal neutron analysis (TNA).

PubMed

Ipe, Nisy E; Akery, A; Ryge, P; Brown, D; Liu, F; Thieu, J; James, B

2005-01-01

A cargo inspection system incorporating a high-resolution X-ray imaging system with a material-specific detection system based on Ancore Corporation's patented thermal neutron analysis (TNA) technology can detect bulk quantities of explosives and drugs concealed in trucks or cargo containers. The TNA process utilises a 252Cf neutron source surrounded by a moderator. The neutron interactions with the inspected object result in strong and unique gamma-ray signals from nitrogen, which is a key ingredient in modern high explosives, and from chlorinated drugs. The TNA computer analyses the gamma-ray signals and automatically determines the presence of explosives or drugs. The radiation source terms and shielding design of the facility are described. For the X-ray generator, the primary beam, leakage radiation, and scattered primary and leakage radiation were considered. For the TNA, the primary neutrons and tunnel scattered neutrons as well as the neutron-capture gamma rays were considered.

Effect of gamma irradiation on hyperthermal composting microorganisms for feasible application in space

NASA Astrophysics Data System (ADS)

Yoon, Minchul; Choi, Jong-il; Yamashita, Masamichi

2013-05-01

The composting system is the most efficient method for processing organic waste in space; however, the composting activity of microorganisms can be altered by cosmic rays. In this study, the effect of ionizing irradiation on composting bacteria was investigated. Sequence analyses of amplified 16S rRNA, 18S rRNA, and amoA genes were used to identify hyperthermal composting microorganisms. The viability of microorganisms in compost soil after gamma irradiation was directly determined using LIVE/DEAD BacLight viability kit. The dominant bacterial genera were Weissella cibaria and Leuconostoc sp., and the fungal genera were Metschnikowia bicuspidata and Pichia guilliermondii. Gamma irradiation up to a dose of 10 kGy did not significantly alter the microbial population. Furthermore, amylase and cellulase activities were maintained after high-dose gamma irradiation. Our results show that hyperthermal microorganisms can be used to recycle agricultural and fermented material in space stations and other human-inhabiting facilities on the Moon, Mars, and other planets.

The high energy cosmic-radiation detection (HERD) facility onboard China's Space Station

NASA Astrophysics Data System (ADS)

Zhang, S. N.; Adriani, O.; Albergo, S.; Ambrosi, G.; An, Q.; Bao, T. W.; Battiston, R.; Bi, X. J.; Cao, Z.; Chai, J. Y.; Chang, J.; Chen, G. M.; Chen, Y.; Cui, X. H.; Dai, Z. G.; D'Alessandro, R.; Dong, Y. W.; Fan, Y. Z.; Feng, C. Q.; Feng, H.; Feng, Z. Y.; Gao, X. H.; Gargano, F.; Giglietto, N.; Gou, Q. B.; Guo, Y. Q.; Hu, B. L.; Hu, H. B.; He, H. H.; Huang, G. S.; Huang, J.; Huang, Y. F.; Li, H.; Li, L.; Li, Y. G.; Li, Z.; Liang, E. W.; Liu, H.; Liu, J. B.; Liu, J. T.; Liu, S. B.; Liu, S. M.; Liu, X.; Lu, J. G.; Mazziotta, M. N.; Mori, N.; Orsi, S.; Pearce, M.; Pohl, M.; Quan, Z.; Ryde, F.; Shi, H. L.; Spillantini, P.; Su, M.; Sun, J. C.; Sun, X. L.; Tang, Z. C.; Walter, R.; Wang, J. C.; Wang, J. M.; Wang, L.; Wang, R. J.; Wang, X. L.; Wang, X. Y.; Wang, Z. G.; Wei, D. M.; Wu, B. B.; Wu, J.; Wu, X.; Wu, X. F.; Xia, J. Q.; Xiao, H. L.; Xu, H. H.; Xu, M.; Xu, Z. Z.; Yan, H. R.; Yin, P. F.; Yu, Y. W.; Yuan, Q.; Zha, M.; Zhang, L.; Zhang, L.; Zhang, L. Y.; Zhang, Y.; Zhang, Y. J.; Zhang, Y. L.; Zhao, Z. G.

2014-07-01

The High Energy cosmic-Radiation Detection (HERD) facility is one of several space astronomy payloads of the cosmic lighthouse program onboard China's Space Station, which is planned for operation starting around 2020 for about 10 years. The main scientific objectives of HERD are indirect dark matter search, precise cosmic ray spectrum and composition measurements up to the knee energy, and high energy gamma-ray monitoring and survey. HERD is composed of a 3-D cubic calorimeter (CALO) surrounded by microstrip silicon trackers (STKs) from five sides except the bottom. CALO is made of about 104 cubes of LYSO crystals, corresponding to about 55 radiation lengths and 3 nuclear interaction lengths, respectively. The top STK microstrips of seven X-Y layers are sandwiched with tungsten converters to make precise directional measurements of incoming electrons and gamma-rays. In the baseline design, each of the four side SKTs is made of only three layers microstrips. All STKs will also be used for measuring the charge and incoming directions of cosmic rays, as well as identifying back scattered tracks. With this design, HERD can achieve the following performance: energy resolution of 1% for electrons and gamma-rays beyond 100 GeV, 20% for protons from 100 GeV to 1 PeV; electron/proton separation power better than 10-5; effective geometrical factors of >3 m2sr for electron and diffuse gamma-rays, >2 m2sr for cosmic ray nuclei. R and D is under way for reading out the LYSO signals with optical fiber coupled to image intensified CCD and the prototype of one layer of CALO.

Gamma-Ray Astronomy Technology Needs

NASA Technical Reports Server (NTRS)

Gehrels, N.; Cannizzo, J. K.

2012-01-01

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

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

NASA Astrophysics Data System (ADS)

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.

KSC-08pd0783

NASA Image and Video Library

2008-03-21

CAPE CANAVERAL, Fla. --- In the Astrotech payload processing facility, the mechanism on NASA's Gamma-Ray Large Area Space Telescope, or GLAST, solar arrays has been released. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Jim Grossmann

KSC-08pd0765

NASA Image and Video Library

2008-03-20

KENNEDY SPACE CENTER, FLA. - In the Astrotech payload processing facility, one of twin solar arrays is positioned on NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Chris Rhodes

Monte Carlo simulation of HERD calorimeter

NASA Astrophysics Data System (ADS)

Xu, M.; Chen, G. M.; Dong, Y. W.; Lu, J. G.; Quan, Z.; Wang, L.; Wang, Z. G.; Wu, B. B.; Zhang, S. N.

2014-07-01

The High Energy cosmic-Radiation Detection (HERD) facility onboard China's Space Station is planned for operation starting around 2020 for about 10 years. It is designed as a next generation space facility focused on indirect dark matter search, precise cosmic ray spectrum and composition measurements up to the knee energy, and high energy gamma-ray monitoring and survey. The calorimeter plays an essential role in the main scientific objectives of HERD. A 3-D cubic calorimeter filled with high granularity crystals as active material is a very promising choice for the calorimeter. HERD is mainly composed of a 3-D calorimeter (CALO) surrounded by silicon trackers (TK) from all five sides except the bottom. CALO is made of 9261 cubes of LYSO crystals, corresponding to about 55 radiation lengths and 3 nuclear interaction lengths, respectively. Here the simulation results of the performance of CALO with GEANT4 and FLUKA are presented: 1) the total absorption CALO and its absorption depth for precise energy measurements (energy resolution: 1% for electrons and gammarays beyond 100 GeV, 20% for protons from 100 GeV to 1 PeV); 2) its granularity for particle identification (electron/proton separation power better than 10-5); 3) the homogenous geometry for detecting particles arriving from every unblocked direction for large effective geometrical factor (<3 m2sr for electron and diffuse gammarays, >2 m2sr for cosmic ray nuclei); 4) expected observational results such as gamma-ray line spectrum from dark matter annihilation and spectrum measurement of various cosmic ray chemical components.

The Penrose photoproduction scenario for NGC 4151: A black hole gamma-ray emission mechanism for active galactic nuclei and Seyfert galaxies. [Compton scattering and pair production

NASA Technical Reports Server (NTRS)

Leiter, D.

1979-01-01

A consistent theoretical interpretation is given for the suggestion that a steepening of the spectrum between X-ray and gamma ray energies may be a general, gamma-ray characteristic of Seyfert galaxies, if the diffuse gamma ray spectrum is considered to be a superposition of unresolved contributions, from one or more classes of extragalactic objects. In the case of NGC 4151, the dominant process is shown to be Penrose Compton scattering in the ergosphere of a Kerr black hole, assumed to exist in the Seyfert's active galactic nucleus.

Gamma-400 Science Objectives Built on the Current HE Gamma-Ray and CR Results

NASA Technical Reports Server (NTRS)

Moiseev, Alexander; Mitchell, John; Thompson, David

2012-01-01

The main scientific interest of the Russian Gamma-400 team: Observe gamma-rays above approximately 50 GeV with excellent energy and angular resolution with the goals of: (1) Studying the fine spectral structure of the isotropic high-energy gamma-radiation, (2) Attempting to identify the many still-unidentified Fermi-LAT gamma-ray sources. Gamma-400 will likely be the only space-based gamma-ray observatory operating at the end of the decade. In our proposed Gamma-400-LE version, it will substantially improve upon the capabilities of Fermi LAT and AGILE in both LE and HE energy range. Measuring gamma-rays from approx 20 MeV to approx 1 TeV for at least 7 years, Gamma-400-LE will address the topics of dark matter, cosmic ray origin and propagation, neutron stars, flaring pulsars, black holes, AGNs, GRBs, and actively participate in multiwavelength campaigns.

Physics Flash August 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kippen, Karen Elizabeth

Physics Flash is the newsletter for the Physics Division at Los Alamos National Laboratory. This newsletter is for August 2016. The following topics are covered: "Accomplishments in the Trident Laser Facility", "David Meyerhofer elected as chair-elect APS Nominating Committee", "HAWC searches for gamma rays from dark matter", "Proton Radiography Facility commissions electromagnetic magnifier", and "Cosmic ray muon computed tomography of spent nuclear fuel in dry storage casks."

Two Active States of the Narrow-Line Gamma-Ray-Loud AGN GB 1310 + 487

NASA Technical Reports Server (NTRS)

Sokolovsky, K. V.; Schinzel, F. K.; Tanaka, Y. T.; Abolmasov, P. K.; Angelakis, E.; Bulgarelli, A.; Carrasco, L.; Cenko, S. B.; Cheung, C. C.; Clubb, K. I.;

Observation of fluctuation of gamma-ray count rate accompanying thunderstorm activity and energy spectrum of gamma rays in the atmosphere up to several kilometers altitude from the ground

NASA Astrophysics Data System (ADS)

Torii, T.; Sanada, Y.; Watanabe, A.

2017-12-01

In the vicinity of the tops of high mountains and in the coastal areas of the Sea of Japan in winter, the generation of high energy photons that lasts more than 100 seconds at the occurrence of thunderclouds has been reported. At the same time, 511 keV gamma rays are also detected. On the other hand, we irradiated a radiosonde equipped with gamma-ray detectors at the time of thunderstorm and observed fluctuation in gamma-ray count-rate. As a result, we found that the gamma-ray count-rate increases significantly near the top of the thundercloud. Therefore, in order to investigate the fluctuation of the energy of the gamma rays, we developed a radiation detector for radiosonde to observe the fluctuation of the low energy gamma-ray spectrum and observed the fluctuation of the gamma-ray spectrum. We will describe the counting rate and spectral fluctuation of gamma-ray detectors for radiosonde observed in the sky in Fukushima prefecture, Japan.

KSC-08pd1137

NASA Image and Video Library

2008-05-04

CAPE CANAVERAL, Fla. -- NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft is moved out of the Astrotech payload processing facility in Titusville, Fla. It is being transported to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date still is to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1123

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

One-dimensional Spatial Distributions of Gamma-ray Emitting Contaminants in Field Lysimeters Using a Collimated Gamma-ray Spectroscopy System.

PubMed

Erdmann, Bryan J; Powell, Brian A; Kaplan, Daniel I; DeVol, Timothy A

2018-05-01

One-dimensional scans of gamma-ray emitting contaminants were conducted on lysimeters from the RadFLEX facility at the Savannah River Nationals Laboratory (SRNL). The lysimeters each contained a contamination source that was buried in SRNL soil. A source consisted of Cs, Co, Ba, and Eu incorporated either into a solid waste form (Portland cement and reducing grout) or applied to a filter paper for direct soil exposure. The lysimeters were exposed to natural environmental conditions for 3 to 4 y. The initial contaminant activities range from 4.0 to 9.0 MBq for the solid wasteforms and 0.25 to 0.47 MBq for the soil-incorporated source. The measurements were performed using a collimated high-purity germanium gamma-ray spectrometer with a spatial resolution of 2.5 mm. These scans showed downward mobility of Co and Ba when the radionuclides were incorporated directly into the SRNL soil. When radionuclides were incorporated into the solid waste forms positioned in the SRNL soil, Cs exhibited both upward and downward dispersion while the other radionuclides showed no movement. This dispersion was more significant for the Portland cement than the reducing grout wasteform. Europium-152 was the only radionuclide of those studied that showed no movement within the spatial resolution of the scanner from the original placement within the lysimeter. Understanding radionuclide movement in the environment is important for developing strategies for waste management and disposal.

A New View of the High Energy Gamma-Ray Sky with the Ferrni Gamma-Ray Space Telescope

NASA Technical Reports Server (NTRS)

McEnery, Julie

2009-01-01

Following its launch in June 2008, high energy gamma-ray observations by the Fermi Gamma-ray Space Telescope have opened a new and important window on a wide variety of phenomena, including pulsars, black holes and active galactic nuclei, gamma-ray bursts, supernova remnants and the origin of cosmic rays, and searches for hypothetical new phenomena such as super symmetric dark matter annihilations. In this talk I will describe the current status of the Fermi observatory and review the science highlights from the first year of observations.

Unidentified Gamma-Ray Sources: Hunting Gamma-Ray Blazars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Massaro, F.; D'Abrusco, R.; Tosti, G.

2012-04-02

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Massaro, F.; Ajello, M.; D'Abrusco, R.

2012-06-10

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

Flaring Activity from S5 0836+71 (4C71.07): What Can We Learn with Limited Multiwavelength Coverage?

NASA Technical Reports Server (NTRS)

Thompson, D. J.; Donato, D.; Akyuz, A.; Fuhrmann, L.; Sokolovsky, K.; Kurtanidze, O.

2011-01-01

After a long period of quiescence in gamma rays, blazar S5 0836+71 (4C71.07) flared in the Spring of 2011. We found only limited multiwavelength coverage of the source. An indication of correlated optical/gamma-ray variability is not surprising for a FSRQ like this one. Radio observations at high frequencies, however, had seen a flare in late 2010, with no apparent related gamma-ray activity. This case seems to differ from the traditional pattern of finding gamma-ray flares during times of rising radio emission.

Fast transient X-rays and gamma ray bursts - Are they stellar flares?

NASA Astrophysics Data System (ADS)

Rao, A. R.; Vahia, M. N.

Short period transient X-ray emissions (FTX) have been observed from several sources in the sky and the largest single group of objects identified with such sources are active stars: flare stars, and RS CVn binaries. The study of the number, source and flux distribution of the fast transient X-ray sources shows that all the FTX emission can be treated as flares in the interbinary regions of active stars. It is suggested that the FTX emission is a common feature of the gamma ray bursts (GRBs). The evidence for the similarity between the hard X-ray flares and GRBs is discussed, and the possibility that the gamma ray bursts are the impulsive precursors of FTX originating from active stars with large scale magnetic activity is examined.

Analytical dose evaluation of neutron and secondary gamma-ray skyshine from nuclear facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayashi, K.; Nakamura, T.

1985-11-01

The skyshine dose distributions of neutron and secondary gamma rays were calculated systematically using the Monte Carlo method for distances up to 2 km from the source. The energy of source neutrons ranged from thermal to 400 MeV; their emission angle from 0 to 90 deg from the ver tical was treated with a distribution of the direction cosine containing five equal intervals. Calculated dose distributions D(r) were fitted to the formula; D(r) = Q exp (-r/lambda)/r. The value of Q and lambda are slowly varied functions of energy. This formula was applied to the benchmark problems of neutron skyshinemore » from fission, fusion, and accelerator facilities, and good agreement was achieved. This formula will be quite useful for shielding designs of various nuclear facilities.« less

The High Energy cosmic-Radiation Detection (HERD) Facility onboard China's Future Space Station

NASA Astrophysics Data System (ADS)

Wu, Bobing

2015-08-01

The High Energy cosmic-Radiation Detection (HERD) facility is one of several space astronomy payloads of the cosmic lighthouse program onboard China's Space Station, which is planned for operation starting around 2020 for about 10 years. The main scientific objectives of HERD are indirect dark matter search, precise cosmic ray spectrum and composition measurements up to the knee energy, and high energy gamma-ray monitoring and survey. HERD is composed of a 3-D cubic calorimeter (CALO) surrounded by microstrip silicon trackers (STKs)from five sides except the bottom. CALO is made of about 10^4 cubes of LYSO crystals, corresponding to about 55 radiation lengths and 3 nuclear interaction lengths, respectively. HERD can achieve the following performance: energy resolution of 1% for electrons and gamma-rays beyond 100 GeV, 20% for protons from 100 GeV to 1 PeV; 2) electron/proton separation power better than 10^5 ; effective geometrical factors of > 3 m^2 sr for electron and diffuse gamma-rays, > 2 m^2 sr for cosmic ray nuclei. The prototype of about 1/40 of HERD calorimeter is under construction. A beam test in CERN with the prototype is approved and will be carried out in Nov. 2015.

Applications of nuclear techniques for in vivo body composition studies at Brookhaven National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cohn, S.H.; Ellis, K.J.; Vartsky, D.

1981-01-01

A series of technical developments and their clinical applications in various nuclear technologies at Brookhaven National Laboratory is described. These include the development of a portable neutron activation facility for measuring cadmium in vivo in kidney and liver, a technique for the measurement of body iron utilizing nuclear resonant scattering of gamma rays, a non-invasive measure of the skeletal levels of lead by an x-ray fluorescence technique, and the development of a pulsed Van de Graaff generator as a source of pulsed neutrons for the measurement of lung silicon. (ACR)

High Energy Astronomy Observatory (HEAO)

NASA Image and Video Library

1977-01-01

This photograph is of the High Energy Astronomy Observatory (HEAO)-2 telescope being evaluated by engineers in the clean room of the X-Ray Calibration Facility at the Marshall Space Flight Center (MSFC). The MSFC was heavily engaged in the technical and scientific aspects, testing and calibration, of the HEAO-2 telescope The HEAO-2 was the first imaging and largest x-ray telescope built to date. The X-Ray Calibration Facility was built in 1976 for testing MSFC's HEAO-2. The facility is the world's largest, most advanced laboratory for simulating x-ray emissions from distant celestial objects. It produced a space-like environment in which components related to x-ray telescope imaging are tested and the quality of their performance in space is predicted. The original facility contained a 1,000-foot long by 3-foot diameter vacuum tube (for the x-ray path) cornecting an x-ray generator and an instrument test chamber. Recently, the facility was upgraded to evaluate the optical elements of NASA's Hubble Space Telescope, Chandra X-Ray Observatory and Compton Gamma-Ray Observatory.

Low energy prompt gamma-ray tests of a large volume BGO detector.

PubMed

Naqvi, A A; Kalakada, Zameer; Al-Anezi, M S; Raashid, M; Khateeb-ur-Rehman; Maslehuddin, M; Garwan, M A

2012-01-01

Tests of a large volume Bismuth Germinate (BGO) detector were carried out to detect low energy prompt gamma-rays from boron and cadmium-contaminated water samples using a portable neutron generator-based Prompt Gamma Neutron Activation Analysis (PGNAA) setup. Inspite of strong interference between the sample- and the detector-associated prompt gamma-rays, an excellent agreement has been observed between the experimental and calculated yields of the prompt gamma-rays, indicating successful application of the large volume BGO detector in the PGNAA analysis of bulk samples using low energy prompt gamma-rays. Copyright © 2011 Elsevier Ltd. All rights reserved.

A generalized method for characterization of 235U and 239Pu content using short-lived fission product gamma spectroscopy

NASA Astrophysics Data System (ADS)

Knowles, Justin; Skutnik, Steven; Glasgow, David; Kapsimalis, Roger

2016-10-01

Rapid nondestructive assay methods for trace fissile material analysis are needed in both nuclear forensics and safeguards communities. To address these needs, research at the Oak Ridge National Laboratory High Flux Isotope Reactor Neutron Activation Analysis facility has developed a generalized nondestructive assay method to characterize materials containing fissile isotopes. This method relies on gamma-ray emissions from short-lived fission products and makes use of differences in fission product yields to identify fissile compositions of trace material samples. Although prior work has explored the use of short-lived fission product gamma-ray measurements, the proposed method is the first to provide a complete characterization of isotopic identification, mass ratios, and absolute mass determination. Successful single fissile isotope mass recoveries of less than 6% recovery bias have been conducted on standards of 235U and 239Pu as low as 12 ng in less than 10 minutes. Additionally, mixtures of fissile isotope standards containing 235U and 239Pu have been characterized as low as 198 ng of fissile mass with less than 7% recovery bias. The generalizability of this method is illustrated by evaluating different fissile isotopes, mixtures of fissile isotopes, and two different irradiation positions in the reactor. It is anticipated that this method will be expanded to characterize additional fissile nuclides, utilize various irradiation facilities, and account for increasingly complex sample matrices.

Next Generation Gamma-Ray Cherenkov Detectors for the National Ignition Facility

DOE PAGES

Herrmann, Hans W.; Kim, Yong Ho; McEvoy, Aaron Matthew; ...

2016-10-19

The newest generation of Gas Cherenkov Detector (GCD-3) employed in Inertial Confinement Fusion experiments at the Omega Laser Facility has provided improved performance over previous generations. Comparison of reaction histories measured using two different deuterium-tritium fusion products, namely gamma rays using GCD and neutrons using Neutron Temporal Diagnostic (NTD), have provided added credibility to both techniques. GCD-3 is now being brought to the National Ignition Facility (NIF) to supplement the existing Gamma Reaction History (GRH-6m) located 6 m from target chamber center (TCC). Initially it will be located in a reentrant well located 3.9 m from TCC. Data from GCD-3more » will inform the design of a heavily-shielded “Super” GCD to be located as close as 20 cm from TCC. In conclusion, it will also provide a test-bed for faster optical detectors, potentially lowering the temporal resolution from the current ~100 ps state-of-the-art photomultiplier tubes (PMT) to ~10 ps Pulse Dilation PMT technology currently under development.« less

NEAR Gamma Ray Spectrometer Characterization and Repair

NASA Technical Reports Server (NTRS)

Groves, Joel Lee; Vajda, Stefan

1998-01-01

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

Large gamma-ray detector arrays and electromagnetic separators

NASA Astrophysics Data System (ADS)

Lee, I.-Yang

2013-12-01

The use of large gamma-ray detector arrays with electromagnetic separators is a powerful combination. Various types of gamma-ray detectors have been used; some provide high detector efficiency such as scintillation detector array, others use Ge detectors for good energy resolution, and recently developed Ge energy tracking arrays gives both high peak-to-background ratio and position resolution. Similarly, different types of separators were used to optimize the performance under different experimental requirements and conditions. For example, gas-filled separators were used in heavy element studies for their large efficiency and beam rejection factor. Vacuum separators with good isotope resolution were used in transfer and fragmentation reactions for the study of nuclei far from stability. This paper presents results from recent experiments using gamma-ray detector arrays in combination with electromagnetic separators, and discusses the physics opportunities provided by these instruments. In particular, we review the performance of the instruments currently in use, and discuss the requirements of instruments for future radioactive beam accelerator facilities.

Giant collimated gamma-ray flashes

NASA Astrophysics Data System (ADS)

Benedetti, Alberto; Tamburini, Matteo; Keitel, Christoph H.

2018-06-01

Bright sources of high-energy electromagnetic radiation are widely employed in fundamental research, industry and medicine1,2. This motivated the construction of Compton-based facilities planned to yield bright gamma-ray pulses with energies up to3 20 MeV. Here, we demonstrate a novel mechanism based on the strongly amplified synchrotron emission that occurs when a sufficiently dense ultra-relativistic electron beam interacts with a millimetre-thickness conductor. For electron beam densities exceeding approximately 3 × 1019 cm-3, electromagnetic instabilities occur, and the ultra-relativistic electrons travel through self-generated electromagnetic fields as large as 107-108 gauss. This results in the production of a collimated gamma-ray pulse with peak brilliance above 1025 photons s-1 mrad-2 mm-2 per 0.1% bandwidth, photon energies ranging from 200 keV to gigaelectronvolts and up to 60% electron-to-photon energy conversion efficiency. These findings pave the way to compact, high-repetition-rate (kilohertz) sources of short (≲30 fs), collimated (milliradian) and high-flux (>1012 photons s-1) gamma-ray pulses.

KSC-08pd0764

NASA Image and Video Library

2008-03-20

KENNEDY SPACE CENTER, FLA. - In the Astrotech payload processing facility, General Dynamics technicians guide one of twin solar arrays toward NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Chris Rhodes

KSC-08pd0781

NASA Image and Video Library

2008-03-21

CAPE CANAVERAL, Fla. --- In the Astrotech payload processing facility, a General Dynamics technician prepares to test the deployment mechanism on the solar arrays on NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Jim Grossmann

KSC-08pd0614

NASA Image and Video Library

2008-03-04

KENNEDY SPACE CENTER, FLA. -- In the Astrotech payload processing facility near the Kennedy Space Center, workers maneuver the shipping container holding NASA's Gamma-Ray Large Area Space Telescope, or GLAST, into place. The GLAST will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Kim Shiflett

KSC-08pd0784

NASA Image and Video Library

2008-03-21

CAPE CANAVERAL, Fla. --- In the Astrotech payload processing facility, NASA's Gamma-Ray Large Area Space Telescope, or GLAST, completes the test of the deployment mechanism on its solar arrays. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Jim Grossmann

KSC-08pd0762

NASA Image and Video Library

2008-03-20

KENNEDY SPACE CENTER, FLA. - In the Astrotech payload processing facility, a General Dynamics technician studies one of twin solar arrays that will be installed on NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Chris Rhodes

KSC-08pd0761

NASA Image and Video Library

2008-03-20

KENNEDY SPACE CENTER, FLA. - In the Astrotech payload processing facility, General Dynamics technicians prepare to install the twin solar arrays on NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Chris Rhodes

KSC-08pd0770

NASA Image and Video Library

2008-03-20

KENNEDY SPACE CENTER, FLA. - In the Astrotech payload processing facility, General Dynamics technicians install the second of twin solar arrays on NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Chris Rhodes

KSC-08pd0763

NASA Image and Video Library

2008-03-20

KENNEDY SPACE CENTER, FLA. - In the Astrotech payload processing facility, General Dynamics technicians lift one of twin solar arrays that will be installed on NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Chris Rhodes

KSC-08pd0782

NASA Image and Video Library

2008-03-21

CAPE CANAVERAL, Fla. --- In the Astrotech payload processing facility, a General Dynamics technician prepares to test the deployment mechanism of the solar arrays on NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Jim Grossmann

KSC-08pd0771

NASA Image and Video Library

2008-03-20

CAPE CANAVERAL, Fla. --- In the Astrotech payload processing facility, a General Dynamics technician finishes the installation of the second of twin solar arrays on NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Chris Rhodes

KSC-08pd0769

NASA Image and Video Library

2008-03-20

KENNEDY SPACE CENTER, FLA. - In the Astrotech payload processing facility, General Dynamics technicians move the second of twin solar arrays toward NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Chris Rhodes

KSC-08pd0766

NASA Image and Video Library

2008-03-20

KENNEDY SPACE CENTER, FLA. - In the Astrotech payload processing facility, General Dynamics technicians install one of twin solar arrays on NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Chris Rhodes

CVD-diamond-based position sensitive photoconductive detector for high-flux x-rays and gamma rays.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shu, D.

1999-04-19

A position-sensitive photoconductive detector (PSPCD) using insulating-type CVD diamond as its substrate material has been developed at the Advanced Photon Source (APS). Several different configurations, including a quadrant pattern for a x-ray-transmitting beam position monitor (TBPM) and 1-D and 2-D arrays for PSPCD beam profilers, have been developed. Tests on different PSPCD devices with high-heat-flux undulator white x-ray beam, as well as with gamma-ray beams from {sup 60}Co sources have been done at the APS and National Institute of Standards and Technology (NIST). It was proven that the insulating-type CVD diamond can be used to make a hard x-ray andmore » gamma-ray position-sensitive detector that acts as a solid-state ion chamber. These detectors are based on the photoconductivity principle. A total of eleven of these TBPMs have been installed on the APS front ends for commissioning use. The linear array PSPCD beam profiler has been routinely used for direct measurements of the undulator white beam profile. More tests with hard x-rays and gamma rays are planned for the CVD-diamond 2-D imaging PSPCD. Potential applications include a high-dose-rate beam profiler for fourth-generation synchrotrons radiation facilities, such as free-electron lasers.« less

Gamma Ray Imaging of Inertial Confinement Fusion Experiments

NASA Astrophysics Data System (ADS)

Wilde, Carl; Volegov, Petr; Geppert-Kleinrath, Verena; Danly, Christopher; Merrill, Frank; Simpson, Raspberry; Fittinghoff, David; Grim, Gary; NIF Nuclear Diagnostic Team Team; Advanced Imaging Team Team

2016-10-01

Experiments consisting of an ablatively driven plastic (CH) shell surrounding a deuterium tritium (DT) fuel region are routinely performed at the National Ignition Facility (NIF). Neutrons produced in the burning fuel in-elastically scatter with carbon atoms in the plastic shell producing 4.4 MeV gamma rays. Providing a spatially resolved distribution of the origin of these gammas can inform models of ablator physics and also provide a bounding volume for the cold fuel (un-burned DT fuel) region. Using the NIF neutron imaging system hardware, initial studies have been performed of the feasibility of imaging these gamma rays. A model of the system has been developed to inform under which experimental conditions this measurement can be made. Presented here is an analysis of the prospects for this diagnostic probe and a proposed set of modifications to the NIF neutron imaging line-of-site to efficiently enable this measurement.

Fermi at Six Months

NASA Technical Reports Server (NTRS)

Hays, Elizabeth

2009-01-01

An overview of the Fermi Gamma-ray Space Telescope's first 6 months in operation is provided. The Fermi Gamma-ray Space Telescope, formerly called GLAST, is a mission to measure the cosmic gamma-ray flux in the energy rage 20 MeV to more than 300 GeV, with supporting measurements for gamma-ray bursts from 8 keV to 30 MeV. It contains a Large Area Telescope capable of viewing the entire sky every 3 hours and a Gamma-ray Burst Monitor for viewing the entire unocculted sky. Since its launch on June 11, 2008 Fermi has provided information on pulsars, gamma ray bursts, relativistic jets, the active galactic nucleus, and a globular star cluster. This presentation describes Fermi's development, mission, instruments and recent findings.

NASA Goddard Space Flight Center, on Behalf of the Fermi Large Area Telescope Collaboration

NASA Technical Reports Server (NTRS)

Thompson, David J.

2010-01-01

Because high-energy gamma rays can be produced by processes that also produce neutrinos, the gamma-ray survey of the sky by the Fermi (Gamma-ray Space Telescope offers a view of potential targets for neutrino observations. Gamma-ray bursts. Active Galactic Nuclei, and supernova remnants are all sites where hadronic, neutrino-producing interactions are plausible. Pulsars, pulsar wind nebulae, and binary sources are all phenomena that reveal leptonic particle acceleration through their gamma-ray emission. While important to gamma-ray astrophysics, such sources are of less interest to neutrino studies. This talk will present a broad overview of the constantly changing sky seen with the Large Area Telescope (LAT)on the Fermi spacecraft.

Characteristics of Gamma-Ray Loud Blazars in the VLBA Imaging and Polarimetry Survey

NASA Technical Reports Server (NTRS)

Linford, J. D.; Taylor, G. B.; Romani, R. W.; Healey, S. E.; Helmboldt, J. F.; Readhead, A. C.; Reeves, R.; Richards, J. L.; Cotter, G.

2010-01-01

The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed as part of the VLBA Imaging and Polarimetry Survey. This large, flux-limited sample of active galactic nuclei (AGNs) provides insights into the mechanism that produces strong gamma-ray emission. At lower flux levels, radio flux density does not directly correlate with gamma-ray flux. We find that the LAT-detected BL Lac objects tend to be similar to the non-LAT BL Lac objects, but that the LAT-detected FSRQs are often significantly different from the non-LAT FSRQs. The differences between the gamma-ray loud and quiet FSRQS can be explained by Doppler boosting; these objects appear to require larger Doppler factors than those of the BL Lac objects. It is possible that the gamma-ray loud FSRQs are fundamentally different from the gamma-ray quiet FSRQs. Strong polarization at the base of the jet appears to be a signature for gamma-ray loud AGNs.

Optimization of a Fast Neutron Scintillator for Real-Time Pulse Shape Discrimination in the Transient Reactor Test Facility (TREAT) Hodoscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, James T.; Thompson, Scott J.; Watson, Scott M.

We present a multi-channel, fast neutron/gamma ray detector array system that utilizes ZnS(Ag) scintillator detectors. The system employs field programmable gate arrays (FPGAs) to do real-time all digital neutron/gamma ray discrimination with pulse height and time histograms to allow count rates in excess of 1,000,000 pulses per second per channel. The system detector number is scalable in blocks of 16 channels.

STS-37 Gamma Ray Observatory (GRO) at KSC Payload Hazardous Servicing Fac

NASA Technical Reports Server (NTRS)

1990-01-01

At the Kennedy Space Center (KSC) Payload Hazardous Servicing Facility, the overhead crane lifts the Gamma Ray Observatory (GRO) from its storage container. GRO, one of four NASA Great Observatories, arrived at KSC on 02-06-90 from the California plant of builder TRW. Weighing a massive 34,700 pounds, GRO will be the heaviest payload without an upper stage ever carried aboard the Space Shuttle. It is scheduled for deployment from Atlantis, Orbiter Vehicle (OV) 104, during STS-37.

STS-37 Gamma Ray Observatory (GRO) at KSC Payload Hazardous Servicing Fac

NASA Technical Reports Server (NTRS)

1990-01-01

Kennedy Space Center (KSC) workers at the Payload Hazardous Servicing Facility are removing the Gamma Ray Observatory (GRO) from its storage container. GRO, one of four NASA Great Observatories, arrived at KSC on 02-06-90 from the California plant of builder TRW. Weighing a massive 34,700 pounds, GRO will be the heaviest payload without an upper stage ever carried aboard the Space Shuttle. It is scheduled for deployment from Atlantis, Orbiter Vehicle (OV) 104, during STS-37.

Nuclear resonance fluorescence in U-238 using LaBr detectors for nuclear security

NASA Astrophysics Data System (ADS)

Hayakawa, Takehito; Negm, Hani; Ohgaki, Hideaki; Daito, Izuru; Kii, Toshiteru; Zen, Heishun; Omer, Mohamed; Shizuma, Toshiyuki; Hajima, Ryoichi

2014-09-01

Recently, a nondestructive measurement method of shielded fissional isotopes such as 235U or 239Pu has been proposed for the nuclear security. These isotopes are measured by using nuclear resonance fluorescence (NRF) with monochromatic energy gamma-ray beams generated by laser Compton-scattering (LCS). We have proposed that one measure scattered gamma-rays from NRF with LCS gamma-ray beams using the LaBr3(Ce) detectors. The LaBr3(Ce) crystals include internal radioisotopes of a meta-stable isotope 138La and alpha decay chains from some actinides as 227Ac. There is a broad pump at about 2 MeV. This pump is considered to be an overlap of alpha-rays from decay chains of some actinides but its detailed structure has not been established. Here we have measured NRF spectra of 238U using the LCS gamma-rays with energy of about 2.5 MeV at the HIgS facility of the Duke University. The background has been evaluated using a simulation code GEAT4. The 9 peaks, 8 NRF gamma-rays plus the Compton scattered gamma-ray of the incident beam, are finally assigned in an energy range of about 200 keV at about 2.5 MeV. The 8 integrated NRF cross-sections measured by LaBr3(Ce) have been consistent with results by an HPGe detector. The three levels are newly assigned using the HPGe detector. Two of them are also measured by LaBr3(Ce).

Discovery of very high energy gamma rays associated with an x-ray binary.

PubMed

Aharonian, F; Akhperjanian, A G; Aye, K-M; Bazer-Bachi, A R; Beilicke, M; Benbow, W; Berge, D; Berghaus, P; Bernlöhr, K; Boisson, C; Bolz, O; Borrel, V; Braun, I; Breitling, F; Brown, A M; Bussons Gordo, J; Chadwick, P M; Chounet, L-M; Cornils, R; Costamante, L; Degrange, B; Dickinson, H J; Djannati-Ataï, A; Drury, L O'c; Dubus, G; Emmanoulopoulos, D; Espigat, P; Feinstein, F; Fleury, P; Fontaine, G; Fuchs, Y; Funk, S; Gallant, Y A; Giebels, B; Gillessen, S; Glicenstein, J F; Goret, P; Hadjichristidis, C; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hofmann, W; Holleran, M; Horns, D; Jacholkowska, A; de Jager, O C; Khélifi, B; Komin, Nu; Konopelko, A; Latham, I J; Le Gallou, R; Lemière, A; Lemoine-Goumard, M; Leroy, N; Lohse, T; Marcowith, A; Martin, J-M; Martineau-Huynh, O; Masterson, C; McComb, T J L; de Naurois, M; Nolan, S J; Noutsos, A; Orford, K J; Osborne, J L; Ouchrif, M; Panter, M; Pelletier, G; Pita, S; Pühlhofer, G; Punch, M; Raubenheimer, B C; Raue, M; Raux, J; Rayner, S M; Reimer, A; Reimer, O; Ripken, J; Rob, L; Rolland, L; Rowell, G; Sahakian, V; Saugé, L; Schlenker, S; Schlickeiser, R; Schuster, C; Schwanke, U; Siewert, M; Sol, H; Spangler, D; Steenkamp, R; Stegmann, C; Tavernet, J-P; Terrier, R; Théoret, C G; Tluczykont, M; Vasileiadis, G; Venter, C; Vincent, P; Völk, H J; Wagner, S J

2005-07-29

X-ray binaries are composed of a normal star in orbit around a neutron star or stellar-mass black hole. Radio and x-ray observations have led to the presumption that some x-ray binaries called microquasars behave as scaled-down active galactic nuclei. Microquasars have resolved radio emission that is thought to arise from a relativistic outflow akin to active galactic nuclei jets, in which particles can be accelerated to large energies. Very high energy gamma-rays produced by the interactions of these particles have been observed from several active galactic nuclei. Using the High Energy Stereoscopic System, we find evidence for gamma-ray emission of >100 gigaelectron volts from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.

KSC-08pd1126

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., technicians lower the overhead crane onto NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The spacecraft is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

KSC-08pd1135

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., technicians stretch protective cover over NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. GLAST is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

KSC-08pd1124

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., technicians prepare NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft for attachment of an overhead crane. The spacecraft is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

KSC-08pd1136

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., technicians stretch protective cover over NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. GLAST is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

KSC-08pd1134

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., technicians begin placing a protective cover over NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. GLAST is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

Low-dose gamma-ray irradiation induces translocation of Nrf2 into nuclear in mouse macrophage RAW264.7 cells.

PubMed

Tsukimoto, Mitsutoshi; Tamaishi, Nana; Homma, Takujiro; Kojima, Shuji

2010-01-01

The transcription factor nuclear erythroid-derived 2-related factor 2 (Nrf2) regulates expression of genes encoding antioxidant proteins involved in cellular redox homeostasis, while gamma-ray irradiation is known to induce reactive oxygen species in vivo. Although activation of Nrf2 by various stresses has been studied, it has not yet been determined whether ionizing irradiation induces activation of Nrf2. Therefore, we investigated activation of Nrf2 in response to gamma-irradiation in mouse macrophage RAW264.7 cells. Irradiation of cells with gamma-rays induced an increase of Nrf2 expression. Even 0.1 Gy of gamma-irradiation induced a translocation of Nrf2 from cytoplasm to the nucleus, indicating the activation of Nrf2 by low-dose irradiation. Expression of heme oxygenase-1, which is regulated by Nrf2, was also increased at 24 h after irradiation with more than 0.1 Gy of gamma-rays. Furthermore, the activation of Nrf2 was suppressed by U0126, which is an inhibitor of the extracellular signal regulated protein kinase 1/2 (ERK1/2) pathway, suggesting involvement of ERK1/2-dependent pathway in the irradiation-induced activation of Nrf2. Our results indicate that low-dose gamma-irradiation induces activation of Nrf2 through ERK1/2-dependent pathways.

Natural soil gamma radioactivity levels and resultant population dose in the cities of Zacatecas and Guadalupe, Zacatecas, Mexico.

PubMed

Mireles, F; Dávila, J I; Quirino, L L; Lugo, J F; Pinedo, J L; Ríos, C

2003-03-01

The study of natural gamma radioactivity was made to determine the concentrations of natural radionuclides in soil. Twenty soil samples collected in the cities of Zacatecas and Guadalupe and their suburban areas in the Mexican state of Zacatecas were analyzed by gamma-ray spectrometry to determine the activity concentrations of 226Ra, 232Th, and 40K. Gamma-spectrometry measurements were made using a hyperpure germanium detector surrounded with shielding material to reduce the background counting rate. The GammaVision-32 MCA emulation software was used for gamma-ray spectrum analysis and the TRUMP card of 2k as a MCA emulator. Conversion factors were used to calculate the dose to the population from outdoor exposure to terrestrial gamma rays. The measured activity concentration of 226Ra varies from 11 to 38 Bq kg(-1), the activity concentration of 232Th varies from 8 to 38 Bq kg(-1). The activity concentration of 40K is in the range 309-1,049 Bq kg(-1). The overall population mean outdoor terrestrial gamma dose rate is 44.94 nGy h(-1).

Multiwavelength Challenges in the Fermi Era

NASA Technical Reports Server (NTRS)

Thompson, D. J.

2010-01-01

The gamma-ray surveys of the sky by AGILE and the Fermi Gamma-ray Space Telescope offer both opportunities and challenges for multiwavelength and multi-messenger studies. Gamma-ray bursts, pulsars, binary sources, flaring Active Galactic Nuclei, and Galactic transient sources are all phenomena that can best be studied with a wide variety of instruments simultaneously or contemporaneously. From the gamma-ray side, a principal challenge is the latency from the time of an astrophysical event to the recognition of this event in the data. Obtaining quick and complete multiwavelength coverage of gamma-ray sources of interest can be difficult both in terms of logistics and in terms of generating scientific interest.

Blazar 3C 66A: Another extragalactic source of ultra-high-energy gamma-ray photons

NASA Astrophysics Data System (ADS)

Neshpor, Yu. I.; Stepanyan, A. A.; Kalekin, O. P.; Fomin, V. P.; Chalenko, N. N.; Shitov, V. G.

1998-03-01

he observations of the object 3C 66A which were carried out with the GT-48 gamma-ray telescope at the Crimean Astrophysical Observatory in November-December 1996 revealed a flux of ultra-high-energy (>10^12 eV) gamma-ray photons from this blazar. According to preliminary estimates, the photon flux is (31) 10^11 photons cm^-2 s^-1. The blazar 3C 66A is the third extragalactic object from which a flux of ultra- high-energy gamma-ray photons was detected. Fluxes of gamma-ray photons were previously detected from the galaxies Mk 421 and Mk 501 at the Whipple observatory. This result provides further evidence that active processes proceed in blazars which are accompanied by the generation of cosmic rays responsible for the emission of gamma-ray photons.

Buildup factor and mechanical properties of high-density cement mixed with crumb rubber and prompt gamma ray study

NASA Astrophysics Data System (ADS)

Aim-O, P.; Wongsawaeng, D.; Tancharakorn, S.; Sophon, M.

2017-09-01

High-density cement mixed with crumb rubber has been studied to be a gamma ray and neutron shielding material, especially for photonuclear reactions that may occur from accelerators where both types of radiation exist. The Buildup factors from gamma ray scattering, prompt and secondary gamma ray emissions from neutron capture and mechanical properties were evaluated. For buildup factor studies, two different geometries were used: narrow beam and broad beam. Prompt Gamma Neutron Activation Analysis (PGNAA) was carried out to determine the prompt and secondary gamma ray emissions. The compressive strength of samples was evaluated by using compression testing machine which was central point loading crushing test. The results revealed that addition of crumb rubber increased the buildup factor. Gamma ray spectra following PGNAA revealed no prompt or secondary gamma ray emission. Mechanical testing indicated that the compressive strength of the shielding material decreased with increasing volume percentage of crumb rubber.

Non-destructive method for determining neutron exposure

DOEpatents

Gold, R.; McElroy, W.N.

1983-11-01

A non-destructive method for determination of neutron exposure in an object, such as a reactor pressure vessel, is based on the observation of characteristic gamma-rays emitted by activation products in the object by using a unique continuous gamma-ray spectrometer. The spectrometer views the object through appropriate collimators to determine the absolute emission rate of these characteristic gamma-rays, thereby ascertaining the absolute activity of given activation products in the object. These data can then be used to deduce the spatial and angular dependence of neutron exposure at regions of interest within the object.

Polarimetric performance of a Laue lens gamma-ray CdZnTe focal plane prototype

NASA Astrophysics Data System (ADS)

Curado da Silva, R. M.; Caroli, E.; Stephen, J. B.; Pisa, A.; Auricchio, N.; Del Sordo, S.; Frontera, F.; Honkimäki, V.; Schiavone, F.; Donati, A.; Trindade, A. M. F.; Ventura, G.

2008-10-01

A gamma-ray telescope mission concept [gamma ray imager (GRI)] based on Laue focusing techniques has been proposed in reply to the European Space Agency call for mission ideas within the framework of the next decade planning (Cosmic Vision 2015-2025). In order to optimize the design of a focal plane for this satellite mission, a CdZnTe detector prototype has been tested at the European Synchrotron Radiation Facility under an ~100% polarized gamma-ray beam. The spectroscopic, imaging, and timing performances were studied and in particular its potential as a polarimeter was evaluated. Polarization has been recognized as being a very important observational parameter in high energy astrophysics (>100 keV) and therefore this capability has been specifically included as part of the GRI mission proposal. The prototype detector tested was a 5 mm thick CdZnTe array with an 11×11 active pixel matrix (pixel area of 2.5×2.5 mm2). The detector was irradiated by a monochromatic linearly polarized beam with a spot diameter of about 0.5 mm over the energy range between 150 and 750 keV. Polarimetric Q factors of 0.35 and double event relative detection efficiency of 20% were obtained. Further measurements were performed with a copper Laue monochromator crystal placed between the beam and the detector prototype. In this configuration we have demonstrated that a polarized beam does not change its polarization level and direction after undergoing a small angle (<1°) Laue diffraction inside a crystal.

AGILE confirmation of gamma-ray activity from the IceCube-170922A error region

NASA Astrophysics Data System (ADS)

Lucarelli, F.; Piano, G.; Pittori, C.; Verrecchia, F.; Tavani, M.; Bulgarelli, A.; Munar-Adrover, P.; Minervini, G.; Ursi, A.; Vercellone, S.; Donnarumma, I.; Fioretti, V.; Zoli, A.; Striani, E.; Cardillo, M.; Gianotti, F.; Trifoglio, M.; Giuliani, A.; Mereghetti, S.; Caraveo, P.; Perotti, F.; Chen, A.; Argan, A.; Costa, E.; Del Monte, E.; Evangelista, Y.; Feroci, M.; Lazzarotto, F.; Lapshov, I.; Pacciani, L.; Soffitta, P.; Sabatini, S.; Vittorini, V.; Pucella, G.; Rapisarda, M.; Di Cocco, G.; Fuschino, F.; Galli, M.; Labanti, C.; Marisaldi, M.; Pellizzoni, A.; Pilia, M.; Trois, A.; Barbiellini, G.; Vallazza, E.; Longo, F.; Morselli, A.; Picozza, P.; Prest, M.; Lipari, P.; Zanello, D.; Cattaneo, P. W.; Rappoldi, A.; Colafrancesco, S.; Parmiggiani, N.; Ferrari, A.; Paoletti, F.; Antonelli, A.; Giommi, P.; Salotti, L.; Valentini, G.; D'Amico, F.

2017-09-01

Following the IceCube observation of a high-energy neutrino candidate event, IceCube-170922A, at T0 = 17/09/22 20:54:30.43 UT (https://gcn.gsfc.nasa.gov/gcn3/21916.gcn3), and the detection of increased gamma-ray activity from a previously known Fermi-LAT gamma-ray source (3FGL J0509.4+0541) in the IceCube-170922A error region (ATel #10791), we have analysed the AGILE-GRID data acquired in the days before and after the neutrino event T0, searching for significant gamma-ray excess above 100 MeV from a position compatible with the IceCube and Fermi-LAT error regions.

All Sky Observations with BATSE and GBM

NASA Technical Reports Server (NTRS)

Wilson-Hodge, Colleen A.

2008-01-01

The Burst and Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory (CGRO) monitored the entire sky from 1991-2000. I will review highlights of BATSE observations including gamma ray bursts, black hole candidates, accreting pulsars, and active galaxies. On 2008 June 11, the Fermi Gamma Ray Space Telescope was launched. The Gamma ray Burst Monitor (GBM) on board Fermi continues the all-sky monitoring legacy started with BATSE. I will review early results and planned observations with GBM.

PKS 2123-463: A Confirmed Gamma-ray Blazar at High Redshift

NASA Technical Reports Server (NTRS)

DAmmando, F.; Rau, A.; Schady, P.; Finke, J.; Orienti, M.; Greiner, J.; Kann, D. A.; Ojha, R.; Foley, A. R.; Stevens, J.;

Improving gross count gamma-ray logging in uranium mining with the NGRS probe

NASA Astrophysics Data System (ADS)

Carasco, C.; Pérot, B.; Ma, J.-L.; Toubon, H.; Dubille-Auchère, A.

2018-01-01

AREVA Mines and the Nuclear Measurement Laboratory of CEA Cadarache are collaborating to improve the sensitivity and precision of uranium concentration measurement by means of gamma ray logging. The determination of uranium concentration in boreholes is performed with the Natural Gamma Ray Sonde (NGRS) based on a NaI(Tl) scintillation detector. The total gamma count rate is converted into uranium concentration using a calibration coefficient measured in concrete blocks with known uranium concentration in the AREVA Mines calibration facility located in Bessines, France. Until now, to take into account gamma attenuation in a variety of boreholes diameters, tubing materials, diameters and thicknesses, filling fluid densities and compositions, a semi-empirical formula was used to correct the calibration coefficient measured in Bessines facility. In this work, we propose to use Monte Carlo simulations to improve gamma attenuation corrections. To this purpose, the NGRS probe and the calibration measurements in the standard concrete blocks have been modeled with MCNP computer code. The calibration coefficient determined by simulation, 5.3 s-1.ppmU-1 ± 10%, is in good agreement with the one measured in Bessines, 5.2 s-1.ppmU-1. Based on the validated MCNP model, several parametric studies have been performed. For instance, the rock density and chemical composition proved to have a limited impact on the calibration coefficient. However, gamma self-absorption in uranium leads to a nonlinear relationship between count rate and uranium concentration beyond approximately 1% of uranium weight fraction, the underestimation of the uranium content reaching more than a factor 2.5 for a 50 % uranium weight fraction. Next steps will concern parametric studies with different tubing materials, diameters and thicknesses, as well as different borehole filling fluids representative of real measurement conditions.

PKS 2123-463: A Confirmed Gamma-ray Blazar at High Redshift

NASA Technical Reports Server (NTRS)

D'Ammando, F.; Rau, A.; Schady, P.; Finke, J.; Orienti, M.; Greiner, J.; Kann, D. A.; Ojha, R.; Foley, A. R.; Stevens, J.;

Universal energy spectrum from point sources

NASA Technical Reports Server (NTRS)

Tomozawa, Yukio

1992-01-01

The suggestion is made that the energy spectrum from point sources such as galactic black hole candidates (GBHC) and active galactic nuclei (AGN) is universal on the average, irrespective of the species of the emitted particles, photons, nucleons, or others. The similarity between the observed energy spectra of cosmic rays, gamma-rays, and X-rays is discussed. In other words, the existing data for gamma-rays and X-rays seem to support the prediction. The expected data from the Gamma Ray Observatory are to provide a further test.

KSC-08pd0767

NASA Image and Video Library

2008-03-20

KENNEDY SPACE CENTER, FLA. - In the Astrotech payload processing facility, General Dynamics technicians use a socket wrench equipped with a torque meter to tighten the bolts holding one of twin solar arrays to NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Chris Rhodes

KSC-08pd0653

NASA Image and Video Library

2008-03-05

KENNEDY SPACE CENTER, FLA. -- In the Astrotech payload processing facility, General Dynamics technicians secure NASA's Gamma-Ray Large Area Space Telescope, or GLAST, onto a work stand. There GLAST will undergo a complete checkout of the scientific instruments aboard. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Kim Shiflett

KSC-08pd0615

NASA Image and Video Library

2008-03-04

KENNEDY SPACE CENTER, FLA. -- In the Astrotech payload processing facility near the Kennedy Space Center, the shipping container covering NASA's Gamma-Ray Large Area Space Telescope, or GLAST, is lifted. Workers will prepare for a complete checkout of the telescope's scientific instruments. The GLAST will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Kim Shiflett

KSC-08pd0768

NASA Image and Video Library

2008-03-20

KENNEDY SPACE CENTER, FLA. - In the Astrotech payload processing facility, one of twin solar arrays awaits processing as General Dynamics technicians install the other of the pair on NASA's Gamma-Ray Large Area Space Telescope, or GLAST. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Chris Rhodes

Mercury and gold concentrations of highly polluted environmental samples determined using prompt gamma-ray analysis and instrument neutron activation analysis

NASA Astrophysics Data System (ADS)

Osawa, Takahito; Hatsukawa, Yuichi; Appel, Peter W. U.; Matsue, Hideaki

2011-04-01

The authors have established a method of determining mercury and gold in severely polluted environmental samples using prompt gamma-ray analysis (PGA) and instrumental neutron activation analysis (INAA). Since large amounts of mercury are constantly being released into the environment by small-scale gold mining in many developing countries, the mercury concentration in tailings and water has to be determined to mitigate environmental pollution. Cold-vapor atomic absorption analysis, the most pervasive method of mercury analysis, is not suitable because tailings and water around mining facilities have extremely high mercury concentrations. On the other hand, PGA can determine high mercury concentrations in polluted samples as it has an appropriate level of sensitivity. Moreover, gold concentrations can be determined sequentially by using INAA after PGA. In conclusion, the analytical procedure established in this work using PGA and INAA is the best way to evaluate the degree of pollution and the tailing resource value. This method will significantly contribute to mitigating problems in the global environment.

First Year PIDDP Report on gamma-ray and x-ray spectroscopy: X-ray remote sensing and in situ spectroscopy for planetary exploration missions and gamma-ray remote sensing and in situ spectroscopy for planetary exploration missions

NASA Technical Reports Server (NTRS)

Mahdavi, M.; Giboni, K. L.; Vajda, S.; Schweitzer, J. S.; Truax, J. A.

1994-01-01

Detectors that will be used for planetary missions must have their responses calibrated in a reproducible manner. In addition, it is important to characterize a detector system at uneven portions of its life cycle, for example after exposure to different amounts of radiation. A calibration and response characterization facility has been constructed at Schlumberger-Doll Research for all types of gamma- and x-ray detectors that may be used for planetary measurement. This facility is currently being tested. Initial use is expected for the MARS 94 detectors. The facility will then also be available for calibrating other detectors as well as arrays of detectors such as the NEAR detector with its central Nal(TI) crystal surrounded with a large BGO crystal. Cadmium telluride detectors are investigated for applications in space explorations. These detectors show an energy resolution of 5 keV for the 122 keV 57Co line. Earlier reported polarization effects are not observed. The detectors can be used at temperatures up to 100 C, although with reduced energy resolution. The thickness of standard detectors is limited to 2 mm. These detectors become fully efficient at bias voltages above 200 V. Initial results for a 1 cm thick detector show that the quality of the material is inferior to the thinner standard detectors and hole trapping affects the pulse height. A detailed characterization of the detector is in progress. Prototypes of photomultipliers based on a Channel Electron Multiplier (CEM) are being built to study their performance. Such photomultipliers promise better timing characteristics and a higher dynamic range while being more compact and of lower in weight.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barty, C J

A renaissance in nuclear physics is occurring around the world because of a new kind of incredibly bright, gamma-ray light source that can be created with short pulse lasers and energetic electron beams. These highly Mono-Energetic Gamma-ray (MEGa-ray) sources produce narrow, laser-like beams of incoherent, tunable gamma-rays and are enabling access and manipulation of the nucleus of the atom with photons or so called 'Nuclear Photonics'. Just as in the early days of the laser when photon manipulation of the valence electron structure of the atom became possible and enabling to new applications and science, nuclear photonics with laser-based gamma-raymore » sources promises both to open up wide areas of practical isotope-related, materials applications and to enable new discovery-class nuclear science. In the United States, the development of high brightness and high flux MEGa-ray sources is being actively pursued at the Lawrence Livermore National Laboratory in Livermore (LLNL), California near San Francisco. The LLNL work aims to create by 2013 a machine that will advance the state of the art with respect to source the peak brightness by 6 orders of magnitude. This machine will create beams of 1 to 2.3 MeV photons with color purity matching that of common lasers. In Europe a similar but higher photon energy gamma source has been included as part of the core capability that will be established at the Extreme Light Infrastructure Nuclear Physics (ELI-NP) facility in Magurele, Romania outside of Bucharest. This machine is expected to have an end point gamma energy in the range of 13 MeV. The machine will be co-located with two world-class, 10 Petawatt laser systems thus allowing combined intense-laser and gamma-ray interaction experiments. Such capability will be unique in the world. In this talk, Dr. Chris Barty from LLNL will review the state of the art with respect to MEGa-ray source design, construction and experiments and will describe both the ongoing projects around the world as well some of the exciting applications that these machines will enable. The optimized interaction of short-duration, pulsed lasers with relativistic electron beams (inverse laser-Compton scattering) is the key to unrivaled MeV-scale photon source monochromaticity, pulse brightness and flux. In the MeV spectral range, such Mono-Energetic Gamma-ray (MEGa-ray) sources can have many orders of magnitude higher peak brilliance than even the world's largest synchrotrons. They can efficiently perturb and excite the isotope-specific resonant structure of the nucleus in a manner similar to resonant laser excitation of the valence electron structure of the atom.« less

Fermi LAT detection of an increase of gamma-ray activity of S5 1044+71

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Orienti, M.

2014-01-01

The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar S5 1044+71 (also known as 2FGL J1048.3+7144, Nolan et al. 2012, ApJS, 199, 31) with radio coordinates R.A.: 162.1150829 deg, Dec: 71.7266494 deg (J2000; Johnston et al. 1995, AJ, 110, 880) at redshift z=1.15 (Polatidis et al.

Fermi LAT detection of a continuing increase of gamma-ray activity of CTA 102

NASA Astrophysics Data System (ADS)

Orienti, M.; D'Ammando, F.

2012-09-01

The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar CTA 102 (also known as 2FGL J2232.4+1143, Nolan et al. 2012, ApJS, 199, 31) with radio coordinates R.A.: 338.1517038 deg, Dec: 11.7308067 deg (J2000, Johnston et al. 1995, AJ, 110, 880) at redshift z=1.037 (Schmidt 1965, ApJ, 141, 1295).

Very High Energy Gamma Ray Extension of GRO Observations

NASA Technical Reports Server (NTRS)

Weekes, Trevor C.

1994-01-01

The membership, progress, and invited talks, publications, and proceedings made by the Whipple Gamma Ray Collaboration is reported for june 1990 through May 1994. Progress was made in the following areas: the May 1994 Markarian Flare at Whipple and EGRET (Energetic Gamma Ray Experiment Telescope) energies; AGN's (Active Galactic Nuclei); bursts; supernova remnants; and simulations and energy spectra.

Very high gamma ray extension of GRO observations

NASA Astrophysics Data System (ADS)

Weekes, Trevor C.

1994-12-01

The membership, progress, and invited talks, publications, and proceedings made by the Whipple Gamma Ray Collaboration is reported for june 1990 through May 1994. Progress was made in the following areas: the May 1994 Markarian Flare at Whipple and EGRET (Energetic Gamma Ray Experiment Telescope) energies; AGN's (Active Galactic Nuclei); bursts; supernova remnants; and simulations and energy spectra.

Long-Term Multiwavelength Studies of High-Redshift Blazar 0836+710

NASA Technical Reports Server (NTRS)

Thompson, D. J.; Akyuz, A.; Donato, D.; Perkins, J. S.; Larsson, S.; Sokolovsky, K.; Fuhrmann, L.; Kurtanidze, O.

2012-01-01

Following gamma-ray flaring activity of high-redshift (z=2.218) blazar 0836+710 in 2011, we have assembled a long-term multiwavelength study of this object. Although this source is monitored regularly by radio telescopes and the Fermi Large Area Telescope, its coverage at other wavelengths is limited. The optical flux appears generally correlated with the gamma-ray flux, while little variability has been seen at X-ray energies. The gamma-ray/radio correlation is complex compared to some other blazars. As for many blazars, the largest variability is seen at gamma-ray wavelengths.

Exploring the High Energy Universe: GLAST Mission and Science

NASA Technical Reports Server (NTRS)

McEnery, Julie

2007-01-01

GLAST, the Gamma-Ray Large Area Space Telescope, is NASA's next-generation high-energy gamma-ray satellite scheduled for launch in Autumn 2007. GLAST will allow measurements of cosmic gamma-ray sources in the 10 MeV to 100 GeV energy band to be made with unprecedented sensitivity. Amongst its key scientific objectives are to understand particle acceleration in Active Galactic Nuclei, Pulsars and Supernovae Remnants, to provide high resolution measurements of unidentified gamma-ray sources, to study transient high energy emission from objects such as gamma-ray bursts, and to probe Dark Matter and the early Universe. Dr. McEnery will present an overview of the GLAST mission and its scientific goals.

Very high energy gamma ray extension of GRO observations

NASA Technical Reports Server (NTRS)

Weekes, Trevor C.

1992-01-01

This has been an exiciting year for high energy gamma-ray astronomy, both from space and from ground-based observatories. It has been a particularly active period for the Whipple Observatory gamma-ray group. In phase 1 of the Compton Gamma Ray Observatory (GRO), there has not been too much opportunity for overlapping observations with the Energetic Gamma Ray Experiment Telescope (EGRET) and the other GRO telescopes; however, significant progress was made in the development of data analysis techniques and in improving the sensitivity of the technique which will have direct application in correlative observations in phase 2. Progress made during the period 1 Jul. 1991 - 31 Dec. 1991 is presented.

Galactic gamma-ray sources, SNOBs, and giant H2 regions

NASA Technical Reports Server (NTRS)

Montmerle, T.

1985-01-01

Progress towards understanding the nature of the COS-B galactic gamma-ray sources was made by two recent developments. The developments are: (1) the existence of extensive wide-latitude CO surveys, from the Northern Hemisphere, and from the Southern Hemisphere which give more precise information on molecular cloud population of the Perseus, Sagittarius, and Carina spiral arms; (2) the study of the time variability of gamma-ray sources in gamma-rays but also at other wavelengths, leading to the discovery of four new variable sources in addition to the already known Crab and Vela pulsars. Three classes of gamma-ray sources are found; invariable sources, active sources, and passive sources.

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

NASA Technical Reports Server (NTRS)

Becker, Peter A.; Kafatos, Menas

1995-01-01

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

KSC-08pd1128

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., technicians check the NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft after being lowered toward the transporter. The spacecraft is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

KSC-08pd1130

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., technicians monitor NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft as it is lowered onto a transporter. The spacecraft is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

KSC-08pd1127

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., technicians lift and move via an overhead crane NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft onto a transporter. The spacecraft is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

KSC-08pd1125

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., technicians attach the cables to the overhead crane that will be used to lift NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The spacecraft is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

KSC-08pd1129

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., the overhead crane continues to lower NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft onto the transporter. The spacecraft is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

KSC-08pd1132

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., technicians check various parts of NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft after its transfer to a transporter. The spacecraft is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

KSC-08pd1131

NASA Image and Video Library

2008-05-03

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., technicians check various parts of NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft after its transfer to a transporter. The spacecraft is being prepared for its move to the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Mike Kerley

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abeysekara, A. U.; Flinders, A.; Archambault, S.

Blazars are variable emitters across all wavelengths over a wide range of timescales, from months down to minutes. It is therefore essential to observe blazars simultaneously at different wavelengths, especially in the X-ray and gamma-ray bands, where the broadband spectral energy distributions usually peak. In this work, we report on three “target-of-opportunity” observations of Mrk 421, one of the brightest TeV blazars, triggered by a strong flaring event at TeV energies in 2014. These observations feature long, continuous, and simultaneous exposures with XMM-Newton (covering the X-ray and optical/ultraviolet bands) and VERITAS (covering the TeV gamma-ray band), along with contemporaneous observationsmore » from other gamma-ray facilities (MAGIC and Fermi -Large Area Telescope) and a number of radio and optical facilities. Although neither rapid flares nor significant X-ray/TeV correlation are detected, these observations reveal subtle changes in the X-ray spectrum of the source over the course of a few days. We search the simultaneous X-ray and TeV data for spectral hysteresis patterns and time delays, which could provide insight into the emission mechanisms and the source properties (e.g., the radius of the emitting region, the strength of the magnetic field, and related timescales). The observed broadband spectra are consistent with a one-zone synchrotron self-Compton model. We find that the power spectral density distribution at ≳4 × 10{sup −4} Hz from the X-ray data can be described by a power-law model with an index value between 1.2 and 1.8, and do not find evidence for a steepening of the power spectral index (often associated with a characteristic length scale) compared to the previously reported values at lower frequencies.« less

All-Sky Monitoring with the Fermi Gamma Ray Burst Monitor

NASA Technical Reports Server (NTRS)

Wilson-Hodge, Colleen A.

2010-01-01

We are currently monitoring the transient hard X-ray/soft gamma ray sky using the Gamma Ray Burst Monitor (GBM) on-board Fermi. The twelve GBM NaI detectors span 8 keV to 1MeV, while the two GBM BGO detectors span about 150 keV to 40 MeV. With GBM, we detect transient events on multiple timescales. Brief events, such as Gamma Ray Bursts, Solar flares, and magnetar bursts are detected with on-board triggers. On longer timescales, we use the Earth occultation technique to monitor a number of sources, including X-ray binaries, AGN, and solar flaring activity. To date we have detected 7 sources above 100 keV. Transient activity from accretion-powered pulsars is monitored using epoch-folding techniques. With GBM we track the pulsed flux and frequency for a number of pulsars. We will present highlights of GBM observations on various timescales.

In-situ gamma-ray assay of the west cell line in the 235-F plutonium fuel form facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Couture, A. H.; Diprete, D.

On August 29th, 2013, scientists from SRNL took a series of in-situ gamma-ray measurements in the maintenance trench beneath Cells 6-9 on the west line of the PuFF facility using an uncollimated, highpurity germanium detector. The detector efficiency was estimated using a combination of MCNP simulations and empirical measurements. Data analysis was performed using three gamma-rays emitted by Pu-238 (99.85 keV, 152.7 keV, and 766.4 keV) providing three independent estimates of the mass of Pu-238 holdup in each of the cells. The weighted mean of these three results was used as the best estimate of Pu-238 holdup in the Westmore » Cell Line of PuFF. The results of the assay measurements are found in the table below along with the results from the scoping assay performed in 2006. All uncertainties in this table (as well as the rest of the report) are given as 1σ. The total holdup in the West Cell Line was 2.4 ± 0.7 grams. This result is 0.6 g higher than the previous estimate, a 0.4σ difference.« less

STS-37 Gamma Ray Observatory (GRO) at KSC Payload Hazardous Servicing Fac

NASA Image and Video Library

1990-02-08

S90-36709 (8 Feb 8, 1990) --- Workers at the Payload Hazardous Servicing Facility are removing the Gamma Ray Observatory from its storage container. GRO, one of four NASA Great Observatories, arrived at the Kennedy Space Center (KSC) February 6 from the California plant of builder TRW. Weighing a massive 34,700 pounds, GRO will be the heaviest payload without an upper stage ever carried aboard the space shuttle. It is scheduled for deployment from the orbiter Atlantis during STS-37 in November 1990.

The 2001 April Burst Activation of SGR 1900-14: Pulse Properties and Torque

NASA Technical Reports Server (NTRS)

Woods, P. M.; Kouveliotou, C.; Goegues, E.; Finger, M. H.; Feroci, M.; Mereghetti, S.; Swank, J. H.; Hurley, K.; Heise, J.; Smith D.

2003-01-01

We report on observations of SGR 1900+14 made with the Rossi X-Ray Timing Explorer (RXTE) and BeppoSAXduring the 2001 April burst activation of the source. Using these data, we measure the spin-down torque on the star and confirm earlier findings that the torque and burst activity are not directly correlated. We compare the X-ray pulse profile to the gamma-ray profile during the April 18 intermediate flare and show that (1) their shapes are similar and (1) the gamma-ray profile aligns closely in phase with the X-ray pulsations. The good phase alignment of the gamma-ray and X-ray profiles suggests that there was no rapid spin-down following this flare of the magnitude inferred for the August 27 giant flare. We discuss how these observations further constrain magnetic field reconfiguration models for the large flares of SGRs.

Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy

NASA Astrophysics Data System (ADS)

Actis, M.; Agnetta, G.; Aharonian, F.; Akhperjanian, A.; Aleksić, J.; Aliu, E.; Allan, D.; Allekotte, I.; Antico, F.; Antonelli, L. A.; Antoranz, P.; Aravantinos, A.; Arlen, T.; Arnaldi, H.; Artmann, S.; Asano, K.; Asorey, H.; Bähr, J.; Bais, A.; Baixeras, C.; Bajtlik, S.; Balis, D.; Bamba, A.; Barbier, C.; Barceló, M.; Barnacka, A.; Barnstedt, J.; Barres de Almeida, U.; Barrio, J. A.; Basso, S.; Bastieri, D.; Bauer, C.; Becerra, J.; Becherini, Y.; Bechtol, K.; Becker, J.; Beckmann, V.; Bednarek, W.; Behera, B.; Beilicke, M.; Belluso, M.; Benallou, M.; Benbow, W.; Berdugo, J.; Berger, K.; Bernardino, T.; Bernlöhr, K.; Biland, A.; Billotta, S.; Bird, T.; Birsin, E.; Bissaldi, E.; Blake, S.; Blanch, O.; Bobkov, A. A.; Bogacz, L.; Bogdan, M.; Boisson, C.; Boix, J.; Bolmont, J.; Bonanno, G.; Bonardi, A.; Bonev, T.; Borkowski, J.; Botner, O.; Bottani, A.; Bourgeat, M.; Boutonnet, C.; Bouvier, A.; Brau-Nogué, S.; Braun, I.; Bretz, T.; Briggs, M. S.; Brun, P.; Brunetti, L.; Buckley, J. H.; Bugaev, V.; Bühler, R.; Bulik, T.; Busetto, G.; Buson, S.; Byrum, K.; Cailles, M.; Cameron, R.; Canestrari, R.; Cantu, S.; Carmona, E.; Carosi, A.; Carr, J.; Carton, P. H.; Casiraghi, M.; Castarede, H.; Catalano, O.; Cavazzani, S.; Cazaux, S.; Cerruti, B.; Cerruti, M.; Chadwick, P. M.; Chiang, J.; Chikawa, M.; Cieślar, M.; Ciesielska, M.; Cillis, A.; Clerc, C.; Colin, P.; Colomé, J.; Compin, M.; Conconi, P.; Connaughton, V.; Conrad, J.; Contreras, J. L.; Coppi, P.; Corlier, M.; Corona, P.; Corpace, O.; Corti, D.; Cortina, J.; Costantini, H.; Cotter, G.; Courty, B.; Couturier, S.; Covino, S.; Croston, J.; Cusumano, G.; Daniel, M. K.; Dazzi, F.; de Angelis, A.; de Cea Del Pozo, E.; de Gouveia Dal Pino, E. M.; de Jager, O.; de La Calle Pérez, I.; de La Vega, G.; de Lotto, B.; de Naurois, M.; de Oña Wilhelmi, E.; de Souza, V.; Decerprit, B.; Deil, C.; Delagnes, E.; Deleglise, G.; Delgado, C.; Dettlaff, T.; di Paolo, A.; di Pierro, F.; Díaz, C.; Dick, J.; Dickinson, H.; Digel, S. W.; Dimitrov, D.; Disset, G.; Djannati-Ataï, A.; Doert, M.; Domainko, W.; Dorner, D.; Doro, M.; Dournaux, J.-L.; Dravins, D.; Drury, L.; Dubois, F.; Dubois, R.; Dubus, G.; Dufour, C.; Durand, D.; Dyks, J.; Dyrda, M.; Edy, E.; Egberts, K.; Eleftheriadis, C.; Elles, S.; Emmanoulopoulos, D.; Enomoto, R.; Ernenwein, J.-P.; Errando, M.; Etchegoyen, A.; Falcone, A. D.; Farakos, K.; Farnier, C.; Federici, S.; Feinstein, F.; Ferenc, D.; Fillin-Martino, E.; Fink, D.; Finley, C.; Finley, J. P.; Firpo, R.; Florin, D.; Föhr, C.; Fokitis, E.; Font, Ll.; Fontaine, G.; Fontana, A.; Förster, A.; Fortson, L.; Fouque, N.; Fransson, C.; Fraser, G. W.; Fresnillo, L.; Fruck, C.; Fujita, Y.; Fukazawa, Y.; Funk, S.; Gäbele, W.; Gabici, S.; Gadola, A.; Galante, N.; Gallant, Y.; García, B.; García López, R. J.; Garrido, D.; Garrido, L.; Gascón, D.; Gasq, C.; Gaug, M.; Gaweda, J.; Geffroy, N.; Ghag, C.; Ghedina, A.; Ghigo, M.; Gianakaki, E.; Giarrusso, S.; Giavitto, G.; Giebels, B.; Giro, E.; Giubilato, P.; Glanzman, T.; Glicenstein, J.-F.; Gochna, M.; Golev, V.; Gómez Berisso, M.; González, A.; González, F.; Grañena, F.; Graciani, R.; Granot, J.; Gredig, R.; Green, A.; Greenshaw, T.; Grimm, O.; Grube, J.; Grudzińska, M.; Grygorczuk, J.; Guarino, V.; Guglielmi, L.; Guilloux, F.; Gunji, S.; Gyuk, G.; Hadasch, D.; Haefner, D.; Hagiwara, R.; Hahn, J.; Hallgren, A.; Hara, S.; Hardcastle, M. J.; Hassan, T.; Haubold, T.; Hauser, M.; Hayashida, M.; Heller, R.; Henri, G.; Hermann, G.; Herrero, A.; Hinton, J. A.; Hoffmann, D.; Hofmann, W.; Hofverberg, P.; Horns, D.; Hrupec, D.; Huan, H.; Huber, B.; Huet, J.-M.; Hughes, G.; Hultquist, K.; Humensky, T. B.; Huppert, J.-F.; Ibarra, A.; Illa, J. M.; Ingjald, J.; Inoue, Y.; Inoue, S.; Ioka, K.; Jablonski, C.; Jacholkowska, A.; Janiak, M.; Jean, P.; Jensen, H.; Jogler, T.; Jung, I.; Kaaret, P.; Kabuki, S.; Kakuwa, J.; Kalkuhl, C.; Kankanyan, R.; Kapala, M.; Karastergiou, A.; Karczewski, M.; Karkar, S.; Karlsson, N.; Kasperek, J.; Katagiri, H.; Katarzyński, K.; Kawanaka, N.; Kȩdziora, B.; Kendziorra, E.; Khélifi, B.; Kieda, D.; Kifune, T.; Kihm, T.; Klepser, S.; Kluźniak, W.; Knapp, J.; Knappy, A. R.; Kneiske, T.; Knödlseder, J.; Köck, F.; Kodani, K.; Kohri, K.; Kokkotas, K.; Komin, N.; Konopelko, A.; Kosack, K.; Kossakowski, R.; Kostka, P.; Kotuła, J.; Kowal, G.; Kozioł, J.; Krähenbühl, T.; Krause, J.; Krawczynski, H.; Krennrich, F.; Kretzschmann, A.; Kubo, H.; Kudryavtsev, V. A.; Kushida, J.; La Barbera, N.; La Parola, V.; La Rosa, G.; López, A.; Lamanna, G.; Laporte, P.; Lavalley, C.; Le Flour, T.; Le Padellec, A.; Lenain, J.-P.; Lessio, L.; Lieunard, B.; Lindfors, E.; Liolios, A.; Lohse, T.; Lombardi, S.; Lopatin, A.; Lorenz, E.; Lubiński, P.; Luz, O.; Lyard, E.; Maccarone, M. C.; Maccarone, T.; Maier, G.; Majumdar, P.; Maltezos, S.; Małkiewicz, P.; Mañá, C.; Manalaysay, A.; Maneva, G.; Mangano, A.; Manigot, P.; Marín, J.; Mariotti, M.; Markoff, S.; Martínez, G.; Martínez, M.; Mastichiadis, A.; Matsumoto, H.; Mattiazzo, S.; Mazin, D.; McComb, T. J. L.; McCubbin, N.; McHardy, I.; Medina, C.; Melkumyan, D.; Mendes, A.; Mertsch, P.; Meucci, M.; Michałowski, J.; Micolon, P.; Mineo, T.; Mirabal, N.; Mirabel, F.; Miranda, J. M.; Mirzoyan, R.; Mizuno, T.; Moal, B.; Moderski, R.; Molinari, E.; Monteiro, I.; Moralejo, A.; Morello, C.; Mori, K.; Motta, G.; Mottez, F.; Moulin, E.; Mukherjee, R.; Munar, P.; Muraishi, H.; Murase, K.; Murphy, A. Stj.; Nagataki, S.; Naito, T.; Nakamori, T.; Nakayama, K.; Naumann, C.; Naumann, D.; Nayman, P.; Nedbal, D.; Niedźwiecki, A.; Niemiec, J.; Nikolaidis, A.; Nishijima, K.; Nolan, S. J.; Nowak, N.; O'Brien, P. T.; Ochoa, I.; Ohira, Y.; Ohishi, M.; Ohka, H.; Okumura, A.; Olivetto, C.; Ong, R. A.; Orito, R.; Orr, M.; Osborne, J. P.; Ostrowski, M.; Otero, L.; Otte, A. N.; Ovcharov, E.; Oya, I.; Oziȩbło, A.; Paiano, S.; Pallota, J.; Panazol, J. L.; Paneque, D.; Panter, M.; Paoletti, R.; Papyan, G.; Paredes, J. M.; Pareschi, G.; Parsons, R. D.; Paz Arribas, M.; Pedaletti, G.; Pepato, A.; Persic, M.; Petrucci, P. O.; Peyaud, B.; Piechocki, W.; Pita, S.; Pivato, G.; Płatos, Ł.; Platzer, R.; Pogosyan, L.; Pohl, M.; Pojmański, G.; Ponz, J. D.; Potter, W.; Prandini, E.; Preece, R.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quel, E.; Quirrenbach, A.; Rajda, P.; Rando, R.; Rataj, M.; Raue, M.; Reimann, C.; Reimann, O.; Reimer, A.; Reimer, O.; Renaud, M.; Renner, S.; Reymond, J.-M.; Rhode, W.; Ribó, M.; Ribordy, M.; Rico, J.; Rieger, F.; Ringegni, P.; Ripken, J.; Ristori, P.; Rivoire, S.; Rob, L.; Rodriguez, S.; Roeser, U.; Romano, P.; Romero, G. E.; Rosier-Lees, S.; Rovero, A. C.; Roy, F.; Royer, S.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Russo, F.; Ryde, F.; Sacco, B.; Saggion, A.; Sahakian, V.; Saito, K.; Saito, T.; Sakaki, N.; Salazar, E.; Salini, A.; Sánchez, F.; Sánchez Conde, M. Á.; Santangelo, A.; Santos, E. M.; Sanuy, A.; Sapozhnikov, L.; Sarkar, S.; Scalzotto, V.; Scapin, V.; Scarcioffolo, M.; Schanz, T.; Schlenstedt, S.; Schlickeiser, R.; Schmidt, T.; Schmoll, J.; Schroedter, M.; Schultz, C.; Schultze, J.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schweizer, T.; Seiradakis, J.; Selmane, S.; Seweryn, K.; Shayduk, M.; Shellard, R. C.; Shibata, T.; Sikora, M.; Silk, J.; Sillanpää, A.; Sitarek, J.; Skole, C.; Smith, N.; Sobczyńska, D.; Sofo Haro, M.; Sol, H.; Spanier, F.; Spiga, D.; Spyrou, S.; Stamatescu, V.; Stamerra, A.; Starling, R. L. C.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Steiner, S.; Stergioulas, N.; Sternberger, R.; Stinzing, F.; Stodulski, M.; Straumann, U.; Suárez, A.; Suchenek, M.; Sugawara, R.; Sulanke, K. H.; Sun, S.; Supanitsky, A. D.; Sutcliffe, P.; Szanecki, M.; Szepieniec, T.; Szostek, A.; Szymkowiak, A.; Tagliaferri, G.; Tajima, H.; Takahashi, H.; Takahashi, K.; Takalo, L.; Takami, H.; Talbot, R. G.; Tam, P. H.; Tanaka, M.; Tanimori, T.; Tavani, M.; Tavernet, J.-P.; Tchernin, C.; Tejedor, L. A.; Telezhinsky, I.; Temnikov, P.; Tenzer, C.; Terada, Y.; Terrier, R.; Teshima, M.; Testa, V.; Tibaldo, L.; Tibolla, O.; Tluczykont, M.; Todero Peixoto, C. J.; Tokanai, F.; Tokarz, M.; Toma, K.; Torres, D. F.; Tosti, G.; Totani, T.; Toussenel, F.; Vallania, P.; Vallejo, G.; van der Walt, J.; van Eldik, C.; Vandenbroucke, J.; Vankov, H.; Vasileiadis, G.; Vassiliev, V. V.; Vegas, I.; Venter, L.; Vercellone, S.; Veyssiere, C.; Vialle, J. P.; Videla, M.; Vincent, P.; Vink, J.; Vlahakis, N.; Vlahos, L.; Vogler, P.; Vollhardt, A.; Volpe, F.; von Gunten, H. P.; Vorobiov, S.; Wagner, S.; Wagner, R. M.; Wagner, B.; Wakely, S. P.; Walter, P.; Walter, R.; Warwick, R.; Wawer, P.; Wawrzaszek, R.; Webb, N.; Wegner, P.; Weinstein, A.; Weitzel, Q.; Welsing, R.; Wetteskind, H.; White, R.; Wierzcholska, A.; Wilkinson, M. I.; Williams, D. A.; Winde, M.; Wischnewski, R.; Wiśniewski, Ł.; Wolczko, A.; Wood, M.; Xiong, Q.; Yamamoto, T.; Yamaoka, K.; Yamazaki, R.; Yanagita, S.; Yoffo, B.; Yonetani, M.; Yoshida, A.; Yoshida, T.; Yoshikoshi, T.; Zabalza, V.; Zagdański, A.; Zajczyk, A.; Zdziarski, A.; Zech, A.; Ziȩtara, K.; Ziółkowski, P.; Zitelli, V.; Zychowski, P.

2011-12-01

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.

Design study of multi-imaging plate system for BNCT irradiation field at Kyoto university reactor.

PubMed

Tanaka, Kenichi; Sakurai, Yoshinori; Kajimoto, Tsuyoshi; Tanaka, Hiroki; Takata, Takushi; Endo, Satoru

2016-09-01

The converter configuration for a multi-imaging plate system was investigated for the application of quality assurance in the irradiation field profile for boron neutron capture therapy. This was performed by the simulation calculation using the PHITS code in the fields at the Heavy Water Neutron Irradiation Facility of Kyoto University Reactor. The converter constituents investigated were carbon for gamma rays, and polyethylene with and without LiF at varied (6)Li concentration for thermal, epithermal, and fast neutrons. Consequently, potential combinations of the converters were found for two components, gamma rays and thermal neutrons, for the standard thermal neutron mode and three components of gamma rays, epithermal neutrons, and thermal or fast neutrons, for the standard mixed or epithermal neutron modes, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Gamma-ray background induced by atmospheric neutrons

NASA Astrophysics Data System (ADS)

Ma, Y.-Q.

1984-03-01

A small piggyback detector system is used to study the reduction of gamma-ray background induced by atmospheric neutrons in the type of actively shielded gamma-ray spectroscopes. The system consists of two 1.5 x 1.5 arcsec NaI crystal units, one of which is surrounded by some neutron shield material. The results of a balloon flight in 1981 are presented. The data show that a shield of 3 cm-thick pure paraffin cannot reduce the gamma-ray background. On the contrary, it may even cause some enhancement.

Gamma ray energy tracking in GRETINA

NASA Astrophysics Data System (ADS)

Lee, I. Y.

2011-10-01

The next generation of stable and exotic beam accelerators will provide physics opportunities to study nuclei farther away from the line of stability. However, these experiments will be more demanding on instrumentation performance. These come from the lower production rate for more exotic beams, worse beam impurities, and large beam velocity from the fragmentation and inverse reactions. Gamma-ray spectroscopy will be one of the most effective tools to study exotic nuclei. However, to fully exploit the physics reach provided by these new facilities, better gamma-ray detector will be needed. In the last 10 years, a new concept, gamma-ray energy tracking array, was developed. Tracking arrays will increase the detection sensitivity by factors of several hundred compared to current arrays used in nuclear physics research. Particularly, the capability of reconstructing the position of the interaction with millimeters resolution is needed to correct the Doppler broadening of gamma rays emitted from high velocity nuclei. GRETINA is a gamma-ray tracking array which uses 28 Ge crystals, each with 36 segments, to cover ¼ of the 4 π of the 4 π solid angle. The gamma ray tracking technique requires detailed pulse shape information from each of the segments. These pulses are digitized using 14-bit 100 MHz flash ADCs, and digital signal analysis algorithms implemented in the on-board FPGAs provides energy, time and selection of pulse traces. A digital trigger system, provided flexible trigger functions including a fast trigger output, and also allows complicated trigger decisions to be made up to 20 microseconds. Further analyzed, carried out in a computer cluster, determine the energy, time, and three-dimensional positions of all gamma-ray interactions in the array. This information is then utilized, together with the characteristics of Compton scattering and pair-production processes, to track the scattering sequences of the gamma rays. GRETINA construction is completed in March 2011, and extensive engineering runs were carried out using radioactive sources, and beams from the 88-Inch Cyclotron at LBNL. The data obtained will be used to optimize its performance. Then the first scientific campaign will start in March 2012 at NSCL MSU.

X-ray and gamma ray emission from petawatt laser-driven nanostructured metal targets

NASA Astrophysics Data System (ADS)

Hill, Matthew; Allan, Peter; Brown, Colin; Hoarty, David; Hobbs, Lauren; James, Steven; Bargsten, Clayton; Hollinger, Reed; Rocca, Jorge; Park, Jaebum; Chen, Hui; London, Richard; Shepherd, Ronnie; Tommasini, Riccardo; Vinko, Sam; Wark, Justin; Marjoribanks, Robin; Neely, David; Spindloe, Chris

2016-10-01

Nano-wire arrays of nickel and gold have been fired at the Orion laser facility using high contrast 1 ω and 2 ω short pulse beams (0.7 ps pulse length, >1020 W cm-2 intensity). Time-resolved and time-integrated K-shell and M-shell emission have been characterized and compared to those of flat foils, investigating the capability of these metamaterial coatings to enhance laser-target coupling and X-ray emission. Bremsstrahlung emission of gamma rays and associated pair production via the Bethe-Heitler process have also been investigated by use of 1 mm-thick gold substrates attached to the gold nanowires. We present our latest experimental data and outline some potential future applications.

Modeled Martian subsurface elemental composition measurements with the Probing In situ with Neutron and Gamma ray instrument

NASA Astrophysics Data System (ADS)

Nowicki, Suzanne F.; Evans, Larry G.; Starr, Richard D.; Schweitzer, Jeffrey S.; Karunatillake, Suniti; McClanahan, Timothy P.; Moersch, Jeffrey E.; Parsons, Ann M.; Tate, Christopher G.

2017-02-01

The Probing In situ with Neutron and Gamma ray (PING) instrument is an innovative application of active neutron-induced gamma ray technology. The objective of PING is to measure the elemental composition of the Martian regolith. This manuscript presents PING's sensitivities as a function of the Martian regolith depth and PING's uncertainties in the measurements as a function of observation time in passive and active mode. The modeled sensitivities show that in PING's active mode, where both a pulsed neutron generator (PNG) and a gamma ray spectrometer (GRS) are used, PING can interrogate the material below the rover to about 20 cm due to the penetrating nature of the high-energy neutrons and the resulting secondary gamma rays observed with the GRS. PING is capable of identifying most major and minor rock-forming elements, including H, O, Na, Mn, Mg, Al, Si, P, S, Cl, Cr, K, Ca, Ti, Fe, and Th. The modeled uncertainties show that PING's use of a PNG reduces the required observation times by an order of magnitude over a passive operating mode where the PNG is turned off. While the active mode allows for more complete elemental inventories with higher sensitivity, the gamma ray signatures of some elements are strong enough to detect in passive mode. We show that PING can detect changes in key marker elements and make thermal neutron measurements in about 1 min that are sensitive to H and Cl.

Sources of GeV Photons and the Fermi Results

NASA Astrophysics Data System (ADS)

Dermer, Charles D.

This chapter presents the elaborated lecture notes on Sources of GeV Photons and the Fermi Results given by Charles D. Dermer at the 40th Saas-Fee Advanced Course on "Astrophysics at Very High Energies". The Fermi Gamma-ray Space Telescope made important discoveries and established new results in various areas of astrophysics: from our solar system to remote gamma-ray bursts, from pulsar physics to limits on dark matter and Lorentz invariance violations. The author gives a broad overview of these results by discussing GeV instrumentation and the GeV sky as seen by Fermi, the Fermi catalogs on gamma-ray sources, pulsars and active galactic nuclei, relativistic jet physics and blazars, gamma-rays from cosmic rays in the Galaxy, from star-forming galaxies and from clusters of galaxies, the diffuse extra-galactic gamma-ray background, micro-quasars, radio galaxies, the extragalactic background light, gamma-ray bursts, Fermi acceleration, ultra-high energy cosmic rays, and black holes.

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

NASA Technical Reports Server (NTRS)

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

Radiobiological studies using gamma and x rays.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Potter, Charles Augustus; Longley, Susan W.; Scott, Bobby R.

2013-02-01

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

Gamma-ray spectrometer experiment, Apollo 17: NaI(T1) detector crystal activation

NASA Technical Reports Server (NTRS)

Trombka, J. I.; Schmadebeck, R. L.; Bielefeld, M.; Okelley, G. D.; Eldridge, J. S.; Northcutt, K. J.; Metzger, A. E.; Schonfeld, E.; Peterson, L. E.; Arnold, J. R.

1973-01-01

An attempt was made to obtain experimental data on proton induced activity and its effect on gamma ray spectral measurements. A NaI(T1) crystal flown in Apollo 17 command module was used for the experiment.

Evaluation of equivalent dose from neutrons and activation products from a 15-MV X-ray LINAC

PubMed Central

Israngkul-Na-Ayuthaya, Isra; Suriyapee, Sivalee; Pengvanich, Phongpheath

2015-01-01

A high-energy photon beam that is more than 10 MV can produce neutron contamination. Neutrons are generated by the [γ,n] reactions with a high-Z target material. The equivalent neutron dose and gamma dose from activation products have been estimated in a LINAC equipped with a 15-MV photon beam. A Monte Carlo simulation code was employed for neutron and photon dosimetry due to mixed beam. The neutron dose was also experimentally measured using the Optically Stimulated Luminescence (OSL) under various conditions to compare with the simulation. The activation products were measured by gamma spectrometer system. The average neutron energy was calculated to be 0.25 MeV. The equivalent neutron dose at the isocenter obtained from OSL measurement and MC calculation was 5.39 and 3.44 mSv/Gy, respectively. A gamma dose rate of 4.14 µSv/h was observed as a result of activations by neutron inside the treatment machine. The gamma spectrum analysis showed 28Al, 24Na, 54Mn and 60Co. The results confirm that neutrons and gamma rays are generated, and gamma rays remain inside the treatment room after the termination of X-ray irradiation. The source of neutrons is the product of the [γ,n] reactions in the machine head, whereas gamma rays are produced from the [n,γ] reactions (i.e. neutron activation) with materials inside the treatment room. The most activated nuclide is 28Al, which has a half life of 2.245 min. In practice, it is recommended that staff should wait for a few minutes (several 28Al half-lives) before entering the treatment room after the treatment finishes to minimize the dose received. PMID:26265661

A Search for the X-ray Counterpart of the Unidentified Gamma-ray Source 3EG J2020+4017 (2CG078+2)

NASA Technical Reports Server (NTRS)

Weisskopf, Martin; Swartz, Douglas A.; Carraminana, Alberto; Carrasco, Luis; Kaplan, David L.; Becker, Werner; Elsner, Ronald F.; Kanbach, Gottfried; ODell, Stephen L.; Tennant, Allyn F.

2006-01-01

We report observations with the Chandra X-ray Observatory of a field in the gamma-Cygni supernova remnant (SNR78.2+2.1) centered on the cataloged location of the unidentified, bright gamma-ray source 3EG J2020+4017. In this search for an X-ray counterpart to the gamma-ray source, we detected 30 X-ray sources. Of these, we found 17 strong-candidate counterparts in optical (visible through near-infrared) cataloged and an additional 3 through our optical observations. Based upon colors and (for several objects) optical spectra, nearly all the optically identified objects appear to be reddened main-sequence stars: None of the X-ray sources with an optical counterpart is a plausible X-ray counterpart to 3EG J2020+4017-if that gamma-ray source is a spin-powered pulsar. Many of the 10 X-ray sources lacking optical counterparts are likely (extragalactic) active galactic nuclei, based upon the sky density of such sources. Although one of the 10 optically unidentified X-ray sources could be the gamma-ray source, there is no auxiliary evidence supporting such an identification

"Chiron": A Proposed Remote Sensing Prompt Gamma Ray Activation Analysis Instrument for a Nuclear Powered Prometheus Mission

NASA Technical Reports Server (NTRS)

Floyd, Samuel R.; Keller, John W.; Dworkin, Jason P.; Mildner, David F. R.

2004-01-01

Prompt Gamma Ray Activation Analysis (PGAA) from neutron capture is an important experimental method that yields information on the elemental abundance of target materials. Gamma ray analysis has been used in planetary exploration missions by taking advantage of the production of neutrons as a result of Galactic Cosmic Ray interaction within the planetary surfaces. The .gamma ray signal that can be obtained from the GCR production of neutrons is very low, so we seek a superior neutron source. NASA s Project Prometheus and the Dept. of Energy aim to develop a nuclear power system for planetary exploration. This provides us with a tremendous opportunity to harness the reactor as a source of neutrons that can be used for PGAA. We envision a narrow stream of neutrons from the reactor directed toward the surface of an asteroid or comet producing the prompt gamma ray signal for analysis. Under ideal conditions of neutron flux and spacecraft orbit, both the signal strength and the spatial resolution will improved by several orders of magnitude over previously missions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thirolf, P. G.; Habs, D.; Filipescu, D.

Next-generation {gamma} beams from laser Compton-backscattering facilities like ELI-NP (Bucharest)] or MEGa-Ray (Livermore) will drastically exceed the photon flux presently available at existing facilities, reaching or even exceeding 10{sup 13}{gamma}/sec. The beam structure as presently foreseen for MEGa-Ray and ELI-NP builds upon a structure of macro-pulses ({approx}120 Hz) for the electron beam, accelerated with X-band technology at 11.5 GHz, resulting in a micro structure of 87 ps distance between the electron pulses acting as mirrors for a counterpropagating intense laser. In total each 8.3 ms a {gamma} pulse series with a duration of about 100 ns will impinge on themore » target, resulting in an instantaneous photon flux of about 10{sup 18}{gamma}/s, thus introducing major challenges in view of pile-up. Novel {gamma} optics will be applied to monochromatize the {gamma} beam to ultimately {Delta}E/E{approx}10{sup -6}. Thus level-selective spectroscopy of higher multipole excitations will become accessible with good contrast for the first time. Fast responding {gamma} detectors, e.g. based on advanced scintillator technology (e.g. LaBr{sub 3}(Ce)) allow for measurements with count rates as high as 10{sup 6}-10{sup 7}{gamma}/s without significant drop of performance. Data handling adapted to the beam conditions could be performed by fast digitizing electronics, able to sample data traces during the micro-pulse duration, while the subsequent macro-pulse gap of ca. 8 ms leaves ample time for data readout. A ball of LaBr{sub 3} detectors with digital readout appears to best suited for this novel type of nuclear photonics at ultra-high counting rates.« less

Fermi LAT detection of renewed gamma-ray flaring activity from the radio galaxy NGC 1275 (Perseus A)

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2013-01-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed GeV gamma-ray flaring activity from a source positionally consistent with NGC 1275 (also known as 2FGL J0319.8+4130, Nolan et al. 2012, ApJS, 199, 31, as Perseus A and 3C 84) a radio galaxy located at the center of the Perseus galaxy cluster (see also Abdo et al. 2009, ApJ, 699, 31).

Fermi LAT detection of gamma-ray flaring activity from the blazar MG J221916+1806 through the Fermi All-sky Variability Analysis (FAVA)

NASA Astrophysics Data System (ADS)

Ajello, M.; Kocevski, D.; Gasparrini, D.; Buehler, R.; Thompson, D.; Ciprini, S.

2014-03-01

During the week between March 17 and March 24, 2014, the Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increased gamma-ray activity from a source positionally coincident with the flat-spectrum radio quasar MG J221916+1806 (also known as 2FGL J2219.1+1805, Nolan et al., 2012, ApJS, 199, 31, and CGRaBS J2219+1806, Healey et al. ...

Probing the Physics of Burning DT Capsules Using Gamma-ray Diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes-Sterbenz, Anna Catherine; Hale, Gerald M.; Jungman, Gerard

2015-02-01

The Gamma Reaction History (GRH) diagnostic developed and lead by the Los Alamos National Laboratory GRH Team is used to determine the bang time and burn width of imploded inertial confinement fusion capsules at the National Ignition Facility. The GRH team is conceptualizing and designing a new Gamma-­to-Electron Magnetic Spectrometer (GEMS), that would be capable of an energy resolution ΔE/E~3-­5%. In this whitepaper we examine the physics that could be explored by the combination of these two gamma-ray diagnostics, with an emphasis on the sensitivity needed for measurements. The main areas that we consider are hydrodynamical mixing, ablator areal densitymore » and density profile, and temporal variations of the density of the cold fuel and the ablator during the DT burn of the capsule.« less

Gamma rays as probe of fission and quasi-fission dynamics in the reaction 32S + 197Au near the Coulomb barrier

NASA Astrophysics Data System (ADS)

Pulcini, A.; Vardaci, E.; Kozulin, E.; Ashaduzzaman, M.; Borcea, C.; Bracco, A.; Brambilla, S.; Calinescu, S.; Camera, F.; Ciemala, M.; de Canditiis, B.; Dorvaux, O.; Harca, I. M.; Itkis, I.; Kirakosyan, V. V.; Knyazheva, G.; Kozulina, N.; Kolesov, I. V.; La Rana, G.; Maj, A.; Matea, I.; Novikov, K.; Petrone, C.; Quero, D.; Rath, P.; Saveleva, E.; Schmitt, C.; Sposito, G.; Stezowski, O.; Trzaska, W. H.; Wilson, J.

2018-05-01

Compound nucleus fission and quasi-fission are both binary decay channels whose common properties make the experimental separation between them difficult. A way to achieve this separation could be to probe the angular momentum of the binary fragments. This can be done detecting gamma rays in coincidence with the two fragments. As a case study, the reaction 32S + 197Au near the Coulomb barrier has been performed at the Tandem ALTO facility at IPN ORSAY. ORGAM and PARIS, two different gamma detectors arrays, are coupled with the CORSET detector, a two-arm time-of-flight spectrometer. TOF-TOF data were analyzed to reconstruct the mass-energy distribution of the primary fragments coupled with gamma multiplicity and spectroscopic analysis. Preliminary results of will be shown.

Modeled Martian subsurface elemental composition measurements with the Probing In situ with Neutron and Gamma ray instrument: Gamma and Neutron Measurements on Mars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nowicki, Suzanne F.; Evans, Larry G.; Starr, Richard D.

Here, the Probing In situ with Neutrons and Gamma rays (PING) instrument is an innovative application of active neutron-induced gamma-ray technology. The objective of PING is to measure the elemental composition of the Martian regolith. As part 2 of a two-part submission, this manuscript presents PING's sensitivities as a function of the Martian regolith depth and PING's uncertainties in the measurements as a function of observation time in passive and active mode. Part 1 of our submission models the associated regolith types. The modeled sensitivities show that in PING's active mode, where both a Pulsed Neutron Generator (PNG) and amore » Gamma-Ray Spectrometer (GRS) are used, PING can interrogate the material below the rover to about 20 cm due to the penetrating nature of the high-energy neutrons and the resulting secondary gamma rays observed with the GRS. PING is capable of identifying most major and minor rock-forming elements, including H, O, Na, Mn, Mg, Al, Si, P, S, Cl, Cr, K, Ca, Ti, Fe and Th. The modeled uncertainties show that PING's use of a PNG reduces the required observation times by an order of magnitude over a passive operating mode where the PNG is turned off. While the active mode allows for more complete elemental inventories with higher sensitivity, the gamma-ray signatures of some elements are strong enough to detect in passive mode. We show that PING can detect changes in key marker elements and make thermal neutron measurements in about 1 minute that are sensitive to H and Cl.« less

Modeled Martian subsurface elemental composition measurements with the Probing In situ with Neutron and Gamma ray instrument: Gamma and Neutron Measurements on Mars

DOE PAGES

Nowicki, Suzanne F.; Evans, Larry G.; Starr, Richard D.; ...

2017-02-01

Here, the Probing In situ with Neutrons and Gamma rays (PING) instrument is an innovative application of active neutron-induced gamma-ray technology. The objective of PING is to measure the elemental composition of the Martian regolith. As part 2 of a two-part submission, this manuscript presents PING's sensitivities as a function of the Martian regolith depth and PING's uncertainties in the measurements as a function of observation time in passive and active mode. Part 1 of our submission models the associated regolith types. The modeled sensitivities show that in PING's active mode, where both a Pulsed Neutron Generator (PNG) and amore » Gamma-Ray Spectrometer (GRS) are used, PING can interrogate the material below the rover to about 20 cm due to the penetrating nature of the high-energy neutrons and the resulting secondary gamma rays observed with the GRS. PING is capable of identifying most major and minor rock-forming elements, including H, O, Na, Mn, Mg, Al, Si, P, S, Cl, Cr, K, Ca, Ti, Fe and Th. The modeled uncertainties show that PING's use of a PNG reduces the required observation times by an order of magnitude over a passive operating mode where the PNG is turned off. While the active mode allows for more complete elemental inventories with higher sensitivity, the gamma-ray signatures of some elements are strong enough to detect in passive mode. We show that PING can detect changes in key marker elements and make thermal neutron measurements in about 1 minute that are sensitive to H and Cl.« less

Induced radioactivity in LDEF components

NASA Technical Reports Server (NTRS)

Harmon, B. A.; Fishman, G. J.; Parnell, T. A.; Laird, C. E.

1991-01-01

The systematics of induced radioactivity on the Long Duration Exposure Facility (LDEF) were studied in a wide range of materials using low level background facilities for detection of gamma rays. Approx. 400 samples of materials processed from structural parts of the spacecraft, as well as materials from onboard experiments, were analyzed at national facilities. These measurements show the variety of radioisotopes that are produced with half-lives greater than 2 wks, most of which are characteristic of proton induced reactions above 20 MeV. For the higher activity, long lived isotopes, it was possible to map the depth and directional dependences of the activity. Due to the stabilized configuration of the LDEF, the induced radioactivity data clearly show contributions from the anisotropic trapped proton flux in the South Atlantic Anomaly. This effect is discussed, along with evidence for activation by galactic protons and thermal neutrons. The discovery of Be-7 was made on leading side parts of the spacecraft, although this was though not to be related to the in situ production of radioisotopes from external particle fluxes.

High Energy Astrophysics with the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Hays, Elizabeth

2009-01-01

This slide presentation reviews some of the findings of the Large Area Telescope (LAT) aboard the Fermi Observatory. It includes information about the LAT, and the Gamma-Ray Burst Monitor (GBM), detection of the quiet sun and the moon in gamma rays, Pulsars observed by the observatory, Globular Star Clusters, Active Galactic Nucleus, and Gamma-Ray Bursts, with specific information about GRB 080916C.

KSC-08pd0617

NASA Image and Video Library

2008-03-04

KENNEDY SPACE CENTER, FLA. -- In the Astrotech payload processing facility near the Kennedy Space Center, workers check NASA's Gamma-Ray Large Area Space Telescope, or GLAST, after removal of the shipping container. The workers will prepare for a complete checkout of the telescope's scientific instruments. The GLAST will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Kim Shiflett

KSC-08pd0654

NASA Image and Video Library

2008-03-05

KENNEDY SPACE CENTER, FLA. -- In the Astrotech payload processing facility, General Dynamics technicians secure NASA's Gamma-Ray Large Area Space Telescope, or GLAST, on a work stand as the overhead crane is lifted away. GLAST will undergo a complete checkout of the scientific instruments aboard. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Kim Shiflett

KSC-08pd0649

NASA Image and Video Library

2008-03-05

KENNEDY SPACE CENTER, FLA. -- In the Astrotech payload processing facility, General Dynamics technicians keep watch as NASA's Gamma-Ray Large Area Space Telescope, or GLAST, is lifted and begins moving toward the work stand in the foreground. There GLAST will undergo a complete checkout of the scientific instruments aboard. The telescope will launch aboard a Delta II rocket May 16 from Launch Pad 17-B on Cape Canaveral Air Force Station. A powerful space observatory, the GLAST will explore the most extreme environments in the universe, and answer questions about supermassive black hole systems, pulsars and the origin of cosmic rays. It also will study the mystery of powerful explosions known as gamma-ray bursts. Photo credit: NASA/Kim Shiflett

Gamma Ray Astronomy

NASA Technical Reports Server (NTRS)

Wu, S. T.

2000-01-01

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

Non-destructive method for determining neutron exposure and constituent concentrations of a body

DOEpatents

Gold, Raymond; McElroy, William N.

1986-01-01

A non-destructive method for determination of neutron exposure and constituent concentrations in an object, such as reactor pressure vessel, is based on the observation of characteristic gamma-rays emitted by activation products in the object by using a unique continuous gamma-ray spectrometer. The spectrometer views the object through appropriate collimators to determine the absolute emission rate of these characteristic gamma-rays, thereby ascertaining the absolute activity of given activation products in the object. These data can then be used to deduce the spatial and angular dependence of neutron exposure or the spatial constituent concentration at regions of interest within the object.

Non-destructive method for determining neutron exposure and constituent concentrations of a body

DOEpatents

Gold, R.; McElroy, W.N.

1984-02-22

A non-destructive method for determination of neutron exposure and constituent concentrations in an object, such as a reactor pressure vessel, is based on the observation of characteristic gamma-rays emitted by activation products in the object by using a unique continuous gamma-ray spectrometer. The spectrometer views the object through appropriate collimators to determine the absolute emission rate of these characteristic gamma-rays, thereby ascertaining the absolute activity of given activation products in the object. These data can then be used to deduce the spatial and angular dependence of neutron exposure or the spatial constituent concentrations at regions of interest within the object.

Detecting Axionlike Particles with Gamma Ray Telescopes

NASA Astrophysics Data System (ADS)

Hooper, Dan; Serpico, Pasquale D.

2007-12-01

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

Determination of photon emission probabilities for the main gamma-rays of ²²³Ra in equilibrium with its progeny.

PubMed

Pibida, L; Zimmerman, B; Fitzgerald, R; King, L; Cessna, J T; Bergeron, D E

2015-07-01

The currently published (223)Ra gamma-ray emission probabilities display a wide variation in the values depending on the source of the data. The National Institute of Standards and Technology performed activity measurements on a (223)Ra solution that was used to prepare several sources that were used to determine the photon emission probabilities for the main gamma-rays of (223)Ra in equilibrium with its progeny. Several high purity germanium (HPGe) detectors were used to perform the gamma-ray spectrometry measurements. Published by Elsevier Ltd.

Design Concepts for the Cherenkov Telescope Array CTA: An Advanced Facility for Ground-Based High-Energy Gamma-Ray Astronomy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Actis, M

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTAmore » is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.« less

Gamma-ray Burst and Gravitational Wave Counterpart Prospects in the MeV Band with AMEGO

NASA Astrophysics Data System (ADS)

Racusin, Judith; AMEGO Team

2018-01-01

The All-sky Medium Energy Gamma-ray Observatory (AMEGO) Probe mission concept is uniquely suited to address open questions in Gamma-ray Burst (GRB) science including the search for counterparts to gravitational-wave events. AMEGO is a wide field of view instrument (~60 deg radius) with a broad energy range (~200 keV to >10 GeV) and excellent continuum sensitivity. The sensitivity improvement will allow for probes of GRB emission mechanisms and jet composition in ways that have not been accessible with previous instruments. Potential for polarization measurement may also have profound impacts on the understanding of GRB mechanisms. AMEGO will also be an excellent facility for the search for gravitational wave counterparts to binary mergers including at least one neutron star, which are thought to produce short duration GRBs. This poster will describe how the AMEGO will advance these fields.

Active interrogation using low-energy nuclear reactions

NASA Astrophysics Data System (ADS)

Antolak, Arlyn; Doyle, Barney; Leung, Ka-Ngo; Morse, Daniel; Provencio, Paula

2005-09-01

High-energy photons and neutrons can be used to interrogate for heavily shielded fissile materials inside sealed cargo containers by detecting their prompt and/or delayed fission signatures. The FIND (Fissmat Inspection for Nuclear Detection) active interrogation system is based on a dual neutron+gamma source that uses low-energy (< 500 keV) proton- or deuteron-induced nuclear reactions to produce high intensities of mono-energetic gamma rays and/or neutrons. The source can be operated in either pulsed (e.g., to detect delayed photofission neutrons and gammas) or continuous (e.g., detecting prompt fission signatures) modes. For the gamma-rays, the source target can be segmented to incorporate different (p,γ) isotopes for producing gamma-rays at selective energies, thereby improving the probability of detection. The design parameters for the FIND system are discussed and preliminary accelerator-based measurements of gamma and neutron yields, background levels, and fission signals for several target materials under consideration are presented.

New applications and developments in the neutron shielding

NASA Astrophysics Data System (ADS)

Uğur, Fatma Aysun

2017-09-01

Shielding neutrons involve three steps that are slowing neutrons, absorption of neutrons, and impregnation of gamma rays. Neutrons slow down with thermal energy by hydrogen, water, paraffin, plastic. Hydrogenated materials are also very effective for the absorption of neutrons. Gamma rays are produced by neutron (radiation) retention on the neutron shield, inelastic scattering, and degradation of activation products. If a source emits gamma rays at various energies, high-energy gamma rays sometimes specify shielding requirements. Multipurpose Materials for Neutron Shields; Concrete, especially with barium mixed in, can slow and absorb the neutrons, and shield the gamma rays. Plastic with boron is also a good multipurpose shielding material. In this study; new applications and developments in the area of neutron shielding will be discussed in terms of different materials.

OPERATIONAL CHARACTERISTICS OF THE ARMOUR FISSION GAS GAMMA FACILITY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Terrell, C.W.; McElroy, W.N.

1958-10-31

As the reactor power level is changed frequently, the radiation levels in the gamma facility fluctuate. Data are presented to show the power dependency of the gamma dose rate and the manner of growth and decay. Additional data show the dependercy of the equilibrium gamma activity on the foel temperature and total system pressure. The final phase of the work is directed toward determining an average gamma energy by attenuation measurements with various thicknesses of several materials. The neutrou flux associated with the gas phase activity is determined by foil measurement. From the measurements of dose rate and average gammamore » energy, calculations to determine the number of curies of gas phase decay gamma activity per watt of reactor power are presented. (auth)« less

Bright x-ray flares in gamma-ray burst afterglows.

PubMed

Burrows, D N; Romano, P; Falcone, A; Kobayashi, S; Zhang, B; Moretti, A; O'brien, P T; Goad, M R; Campana, S; Page, K L; Angelini, L; Barthelmy, S; Beardmore, A P; Capalbi, M; Chincarini, G; Cummings, J; Cusumano, G; Fox, D; Giommi, P; Hill, J E; Kennea, J A; Krimm, H; Mangano, V; Marshall, F; Mészáros, P; Morris, D C; Nousek, J A; Osborne, J P; Pagani, C; Perri, M; Tagliaferri, G; Wells, A A; Woosley, S; Gehrels, N

2005-09-16

Gamma-ray burst (GRB) afterglows have provided important clues to the nature of these massive explosive events, providing direct information on the nearby environment and indirect information on the central engine that powers the burst. We report the discovery of two bright x-ray flares in GRB afterglows, including a giant flare comparable in total energy to the burst itself, each peaking minutes after the burst. These strong, rapid x-ray flares imply that the central engines of the bursts have long periods of activity, with strong internal shocks continuing for hundreds of seconds after the gamma-ray emission has ended.

SKYSHINE-II procedure: calculation of the effects of structure design on neutron, primary gamma-ray and secondary gamma-ray dose rates in air. Supplement number 1. Technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lampley, C.M.

1981-01-01

This report describes many of the computational methods employed within the SKYSHINE-II program. A brief description of the new data base is included, as is a description of the input data requirements and formats needed to properly execute a SKYSHINE-II problem. Utilization instructions for the program are provided for operation of the SKYSHINE-II Code on the Brookhaven National Laboratory Central Scientific Computing Facility (See NUREG/CR-0781, RRA-T7901 for complete information).

THE BRIGHTEST GAMMA-RAY FLARING BLAZAR IN THE SKY: AGILE AND MULTI-WAVELENGTH OBSERVATIONS OF 3C 454.3 DURING 2010 NOVEMBER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vercellone, S.; Romano, P.; Striani, E.

2011-08-01

Since 2005, the blazar 3C 454.3 has shown remarkable flaring activity at all frequencies, and during the last four years it has exhibited more than one {gamma}-ray flare per year, becoming the most active {gamma}-ray blazar in the sky. We present for the first time the multi-wavelength AGILE, Swift, INTEGRAL, and GASP-WEBT data collected in order to explain the extraordinary {gamma}-ray flare of 3C 454.3 which occurred in 2010 November. On 2010 November 20 (MJD 55520), 3C 454.3 reached a peak flux (E >100 MeV) of F{sup p}{sub {gamma}} = (6.8 {+-} 1.0) x 10{sup -5} photons cm{sup -2} s{supmore » -1} on a timescale of about 12 hr, more than a factor of six higher than the flux of the brightest steady {gamma}-ray source, the Vela pulsar, and more than a factor of three brighter than its previous super-flare on 2009 December 2-3. The multi-wavelength data make possible a thorough study of the present event: the comparison with the previous outbursts indicates a close similarity to the one that occurred in 2009. By comparing the broadband emission before, during, and after the {gamma}-ray flare, we find that the radio, optical, and X-ray emission varies within a factor of 2-3, whereas the {gamma}-ray flux by a factor of 10. This remarkable behavior is modeled by an external Compton component driven by a substantial local enhancement of soft seed photons.« less

Measured neutron and gamma spectra from californium-252 in a tissue-equivalent medium.

PubMed

Elson, H R; Stupar, T A; Shapiro, A; Kereiakes, J G

1979-01-01

A method of experimentally obtaining both neutron and gamma-ray spectra in a scattering medium is described. The method utilizes a liquid-organic scintillator (NE-213) coupled with a pulse-shape discrimination circuit. This allows the separation of the neutron-induced pulse-height data from the gamma-ray pulse-height data. Using mathematical unfolding techniques, the two sets of pulse-height data were transformed to obtain the neutron and gamma-ray energy spectra. A small spherical detector was designed and constructed to reduce the errors incurred by attempting spectral measurements in a scattering medium. Demonstration of the utility of the system to obtain the neutron and gamma-ray spectra in a scattering medium was performed by characterizing the neutron and gamma-ray spectra at various sites about a 3.7-microgram (1.5 cm active length) californium-252 source in a tissue-equivalent medium.

Five Years of the Fermi LAT Flare Advocate

NASA Astrophysics Data System (ADS)

Carpenter, Bryce; Ojha, R.; Gasparrini, D.; Ciprini, S.; Fermi LAT Collaboration; Fermi LAT Flare Advocates

2014-01-01

Since the launch of the Fermi satellite, the Fermi Large Area Telescope (LAT) team has run a program that provides a daily review of the the gamma-ray sky as soon as Fermi LAT data becomes available. The Flare Advocate/Gamma-ray Sky Watcher (FA-GSW) program allows a rapid analysis of the Automatic Science Processing (ASP) products and triggers dedicated followup analyses by several LAT science groups such as those studying Galactic transients, extragalactic sources and new gamma-ray sources. Significant gamma-ray detections also trigger rapid communications to the entire astrophysical community via astronomical telegrams and gamma-ray coordination network notices. The FA-GSW program plays a key role in maximizing the science return from Fermi by increasing the rate of multi-frequency observations of sources in an active gamma-ray state. In the past ~5 years blazar flaring activity of varying strength and duty cycles, gravitationally lensed blazars, flares from Galactic sources (like Nova Delphini and the Crab Nebula), unidentified transients near and off the Galactic plane, and emission from the quiet and flaring Sun, represent the range of detections made. Flare Advocates have published about 250 Astronomical Telegrams and they publish a weekly blog. Timely, extensive multi-frequency campaigns have been organized to follow-up on these phenomena leading to some of Fermi’s most interesting results.

Isomer-delayed gamma-ray spectroscopy of neutron-rich 166Tb

DOE PAGES

Gurgi, L. A.; Regan, P. H.; Söderström, P. -A.; ...

2017-09-13

Here, this short paper presents the identification of a metastable, isomeric-state decay in the neutron-rich odd-odd, prolate-deformed nucleus 166Tb. The nucleus of interest was formed using the in-flight fission of a 345 MeV per nucleon 238U primary beam at the RIBF facility, RIKEN, Japan. Gamma-ray transitions decaying from the observed isomeric states in 166Tb were identified using the EURICA gamma-ray spectrometer, positioned at the final focus of the BigRIPS fragments separator. The current work identifies a single discrete gamma-ray transition of energy 119 keV which de-excites an isomeric state in 166Tb with a measured half-life of 3.5(4) μs. The multipolaritymore » assignment for this transition is an electric dipole and is made on the basis internal conversion and decay lifetime arguments. Possible two quasi-particle Nilsson configurations for the initial and final states which are linked by this transition in 166Tb are made on the basis of comparison with Blocked BCS Nilsson calculations, with the predicted ground state configuration for this nucleus arising from the coupling of the v(1-/2)[521] and π(3+/2) Nilsson orbitals.« less

Isomer-delayed gamma-ray spectroscopy of neutron-rich 166Tb

NASA Astrophysics Data System (ADS)

Gurgi, L. A.; Regan, P. H.; Söderström, P.-A.; Watanabe, H.; Walker, P. M.; Podolyák, Zs.; Nishimura, S.; Berry, T. A.; Doornenbal, P.; Lorusso, G.; Isobe, T.; Baba, H.; Xu, Z. Y.; Sakurai, H.; Sumikama, T.; Catford, W. N.; Bruce, A. M.; Browne, F.; Lane, G. J.; Kondev, F. G.; Odahara, A.; Wu, J.; Liu, H. L.; Xu, F. R.; Korkulu, Z.; Lee, P.; Liu, J. J.; Phong, V. H.; Yagi, A.; Zhang, G. X.; Alharbi, T.; Carroll, R. J.; Chae, K. Y.; Dombradi, Zs.; Estrade, A.; Fukuda, N.; Griffin, C.; Ideguchi, E.; Inabe, N.; Kanaoka, H.; Kojouharov, I.; Kubo, T.; Kubono, S.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lee, E. J.; Lee, C. S.; Lotay, G.; Moon, C. B.; Nishizuka, I.; Nita, C. R.; Patel, Z.; Roberts, O. J.; Schaffner, H.; Shand, C. M.; Suzuki, H.; Takeda, H.; Terashima, S.; Vajta, Zs.; Kanaya, S.; Valiente-Dobòn, J. J.

2017-09-01

This short paper presents the identification of a metastable, isomeric-state decay in the neutron-rich odd-odd, prolate-deformed nucleus 166Tb. The nucleus of interest was formed using the in-flight fission of a 345 MeV per nucleon 238U primary beam at the RIBF facility, RIKEN, Japan. Gamma-ray transitions decaying from the observed isomeric states in 166Tb were identified using the EURICA gamma-ray spectrometer, positioned at the final focus of the BigRIPS fragments separator. The current work identifies a single discrete gamma-ray transition of energy 119 keV which de-excites an isomeric state in 166Tb with a measured half-life of 3.5(4) μs. The multipolarity assignment for this transition is an electric dipole and is made on the basis internal conversion and decay lifetime arguments. Possible two quasi-particle Nilsson configurations for the initial and final states which are linked by this transition in 166Tb are made on the basis of comparison with Blocked BCS Nilsson calculations, with the predicted ground state configuration for this nucleus arising from the coupling of the v(1-/2)?[521] and ? π(3+/2) Nilsson orbitals.

Attenuation of X and Gamma Rays in Personal Radiation Shielding Protective Clothing.

PubMed

Kozlovska, Michaela; Cerny, Radek; Otahal, Petr

2015-11-01

A collection of personal radiation shielding protective clothing, suitable for use in case of accidents in nuclear facilities or radiological emergency situations involving radioactive agents, was gathered and tested at the Nuclear Protection Department of the National Institute for Nuclear, Chemical and Biological Protection, Czech Republic. Attenuating qualities of shielding layers in individual protective clothing were tested via spectra measurement of x and gamma rays, penetrating them. The rays originated from different radionuclide point sources, the gamma ray energies of which cover a broad energy range. The spectra were measured by handheld spectrometers, both scintillation and High Purity Germanium. Different narrow beam geometries were adjusted using a special testing bench and a set of various collimators. The main experimentally determined quantity for individual samples of personal radiation shielding protective clothing was x and gamma rays attenuation for significant energies of the spectra. The attenuation was assessed comparing net peak areas (after background subtraction) in spectra, where a tested sample was placed between the source and the detector, and corresponding net peak areas in spectra, measured without the sample. Mass attenuation coefficients, which describe attenuating qualities of shielding layers materials in individual samples, together with corresponding lead equivalents, were determined as well. Experimentally assessed mass attenuation coefficients of the samples were compared to the referred ones for individual heavy metals.

Fermi LAT detection of renewed and strong GeV gamma-ray flares from blazars PKS 0903-57 and PKS 0346-27

NASA Astrophysics Data System (ADS)

Ciprini, Stefano

2018-05-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed high-level gamma-ray activity from sources positionally consistent with the active galaxy PKS 0903-57 (also known as MRC 0903-573 and 3FGL J0904.8-5734, Acero et al. 2015, ApJS, 218, 23) and with the flat spectrum radio quasar PKS 0346-27 (also known as OE -278, TXS 0346-279, MRC 0346-279 and 3FGL J0348.6-2748).

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abeysekara, A. U.; Archambault, S.; Archer, A.

2015-12-20

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

The D-D Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Active Well Coincidence Counter

DOE Office of Scientific and Technical Information (OSTI.GOV)

McElroy, Robert Dennis; Cleveland, Steven L.

The 235U mass assay of bulk uranium items, such as oxide canisters, fuel pellets, and fuel assemblies, is not achievable by traditional gamma-ray assay techniques due to the limited penetration of the item by the characteristic 235U gamma rays. Instead, fast neutron interrogation methods such as active neutron coincidence counting must be used. For international safeguards applications, the most commonly used active neutron systems, the Active Well Coincidence Counter (AWCC), Uranium Neutron Collar (UNCL) and 252Cf Shuffler, rely on fast neutron interrogation using an isotopic neutron source [i.e., 252Cf or Am(Li)] to achieve better measurement accuracies than are possible usingmore » gamma-ray techniques for high-mass, high-density items. However, the Am(Li) sources required for the AWCC and UNCL systems are no longer manufactured, and newly produced systems rely on limited supplies of sources salvaged from disused instruments. The 252Cf shuffler systems rely on the use of high-output 252Cf sources, which while still available have become extremely costly for use in routine operations and require replacement every five to seven years. Lack of a suitable alternative neutron interrogation source would leave a potentially significant gap in the safeguarding of uranium processing facilities. In this work, we made use of Oak Ridge National Laboratory’s (ORNL’s) Large Volume Active Well Coincidence Counter (LV-AWCC) and a commercially available deuterium-deuterium (D-D) neutron generator to examine the potential of the D-D neutron generator as an alternative to the isotopic sources. We present the performance of the LV-AWCC with D-D generator for the assay of 235U based on the results of Monte Carlo N-Particle (MCNP) simulations and measurements of depleted uranium (DU), low enriched uranium (LEU), and highly enriched uranium (HEU) items.« less

Degradation of cyanidin-3-rutinoside and formation of protocatechuic acid methyl ester in methanol solution by gamma irradiation.

PubMed

Lee, Seung Sik; Kim, Tae Hoon; Lee, Eun Mi; Lee, Min Hee; Lee, Ha Yeong; Chung, Byung Yeoup

2014-08-01

Anthocyanins are naturally occurring phenolic compounds having broad biological activities including anti-mutagenesis and anti-carcinogenesis. We studied the effects and the degradation mechanisms of the most common type of anthocyanins, cyanidin-3-rutinoside (cya-3-rut), by using gamma ray. Cya-3-rut in methanol (1mg/ml) was exposed to gamma-rays from 1 to 10kGy. We found that the reddish colour of cya-3-rut in methanol disappeared gradually in a dose-dependent manner and effectively disappeared (>97%) at 10kGy of gamma ray. Concomitantly, a new phenolic compound was generated and identified as a protocatechuic acid methyl ester by liquid chromatography, (1)H, and (13)C NMR. The formation of protocatechuic acid methyl ester increased with increasing irradiation and the amount of protocatechuic acid methyl ester formed by decomposition of cya-3-rut (20μg) at 10kGy of gamma ray was 1.95μg. In addition, the radical-scavenging activities were not affected by gamma irradiation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Research in particles and fields

NASA Technical Reports Server (NTRS)

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

1987-01-01

Discussed are the research activities in Cosmic Rays, Gamma Rays, and Astrophysical Plasmas supported under NASA Grant NGR 05-002-160. The report is divided into sections which describe the activities, followed by a bibliography. This research program is directed toward the investigation of the astrophysical aspects of cosmic rays and gamma rays and of the radiation and electromagnetic field environment of the Earth and other planets. These investigations are carried out by means of energetic particle and photon detector systems flown on spacecraft and balloons.

Research in particles and fields

NASA Technical Reports Server (NTRS)

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

1985-01-01

Research activities in Cosmic Rays, Gamma Rays, and Astrophysical Plasmas supported under NASA Grant NGR 05-002-160 are discussed. The report is divided into sections which describe the activities, followed by a bibliography. This group's research program is directed toward the investigation of the astrophysical aspects of cosmic rays and gamma rays and of the radiation and electromagnetic field environment of the Earth and other planets. These investigations are carried out by means of energetic particle and photon detector systems flown on spacecraft and balloons.

Electron-positron pairs, Compton reflection, and the X-ray spectra of active galactic nuclei

NASA Technical Reports Server (NTRS)

Zdziarski, Andrzej A.; Ghisellini, Gabriele; George, Ian M.; Fabian, A. C.; Svensson, Roland; Done, Chris

1990-01-01

It is shown here that reprocessing of radiation fron nonthermal pair cascades by cold material in the central parts of active galactic nuclei (AGN) gives rise to X-ray and gamma-ray spectra that satisfy current observational constraints. An average 1-30 keV X-ray spectral index alpha(x) of about 0.7 in the compact range 30-300 is obtained for a wide range of Lorentz factors of the injected electrons. The gamma-ray spectra are steep, with alpha(gamma) about two, and satisfy the observational constraints. Radiation from pair cascades exhibits steep power law decreases in soft X-rays similar to those observed in AGN. The overall picture is consistent with AGN having an accretion disk which intercepts and reprocesses a substantial fraction of the nonthermal continuum incident upon it from above and below.

NOTE: Total body-calcium measurements: comparison of two delayed-gamma neutron activation facilities

NASA Astrophysics Data System (ADS)

Ma, R.; Ellis, K. J.; Yasumura, S.; Shypailo, R. J.; Pierson, R. N., Jr.

1999-06-01

This study compares two independently calibrated delayed-gamma neutron activation (DGNA) facilities, one at the Brookhaven National Laboratory (BNL), Upton, New York, and the other at the Children's Nutrition Research Center (CNRC), Houston, Texas that measure total body calcium (TBCa). A set of BNL phantoms was sent to CNRC for neutron activation analysis, and a set of CNRC phantoms was measured at BNL. Both facilities showed high precision (<2%), and the results were in good agreement, within 5%.

Analysis, review, and documentation of the activation data from LDEF material

NASA Technical Reports Server (NTRS)

Laird, C. E.

1992-01-01

Samples removed from Long Duration Exposure Facility (LDEF-1) are being studied at various laboratories to determine the specific activity(pCi/kg) produced in orbit by exposure to protons and neutrons in near-Earth orbit. These activities are being corrected for efficiency, self-attenuation, and background. The activities and associated gamma-ray spectra are being collected, analyzed, documented and reviewed by faculty and graduate students at Eastern Kentucky University. The currently available activation results have been tabulated and reviewed in this report. Approximately 500 spectra have been accumulated for future archival and analysis. The effect of the changing satellite orbit on the activation is reported herein and was calculated using more recent estimates of the flux of Van Allen belt protons.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartemann, F V; Albert, F; Anderson, S G

Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies. The nascent field of nuclear photonics is enabledmore » by the recent maturation of new technologies, including high-gradient X-band electron acceleration, robust fiber laser systems, and hyper-dispersion CPA. Recent work has been performed at LLNL to demonstrate isotope-specific detection of shielded materials via NRF using a tunable, quasi-monochromatic Compton scattering gamma-ray source operating between 0.2 MeV and 0.9 MeV photon energy. This technique is called Fluorescence Imaging in the Nuclear Domain with Energetic Radiation (or FINDER). This work has, among other things, demonstrated the detection of {sup 7}Li shielded by Pb, utilizing gamma rays generated by a linac-driven, laser-based Compton scattering gamma-ray source developed at LLNL. Within this context, a new facility is currently under construction at LLNL, with the goal of generating tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range, at a repetition rate of 120 Hz, and with a peak brightness in the 10{sup 20} photons/(s x mm{sup 2} x mrad{sup 2} x 0.1% bw).« less

Fermi-LAT Observations of Continued Gamma-ray Activity from Nova ASASSN-16ma

NASA Astrophysics Data System (ADS)

Li, Kwan-Lok; Chomiuk, Laura; Strader, Jay; Cheung, C. C.; Jean, P.; Shore, S. N.; Fermi Large Area Telescope Collaboration

2016-11-01

Following the report of a sudden gamma-ray onset detection of nova ASASSN-16ma coincident with the optical peak of 5.5 mag on November 8 (ATel #9736), ASASSN-16ma was observed to slowly decrease in gamma-rays but has remained bright enough to be detectable with Fermi-LAT over the last 9 days (test statistic, TS > 10 per day, except for November 17 with TS=5).

Perspectives on Gamma-Ray Burst Physics and Cosmology with Next Generation Facilities

NASA Astrophysics Data System (ADS)

Yuan, Weimin; Amati, Lorenzo; Cannizzo, John K.; Cordier, Bertrand; Gehrels, Neil; Ghirlanda, Giancarlo; Götz, Diego; Produit, Nicolas; Qiu, Yulei; Sun, Jianchao; Tanvir, Nial R.; Wei, Jianyan; Zhang, Chen

2016-12-01

High-redshift Gamma-Ray Bursts (GRBs) beyond redshift {˜}6 are potentially powerful tools to probe the distant early Universe. Their detections in large numbers and at truly high redshifts call for the next generation of high-energy wide-field instruments with unprecedented sensitivity at least one order of magnitude higher than the ones currently in orbit. On the other hand, follow-up observations of the afterglows of high-redshift GRBs and identification of their host galaxies, which would be difficult for the currently operating telescopes, require new, extremely large facilities of at multi-wavelengths. This chapter describes future experiments that are expected to advance this exciting field, both being currently built and being proposed. The legacy of Swift will be continued by SVOM, which is equipped with a set of space-based multi-wavelength instruments as well as and a ground segment including a wide angle camera and two follow-up telescopes. The established Lobster-eye X-ray focusing optics provides a promising technology for the detection of faint GRBs at very large distances, based on which the THESEUS, Einstein Probe and other mission concepts have been proposed. Follow-up observations and exploration of the reionization era will be enabled by large facilities such as SKA in the radio, the 30 m class telescopes in the optical/near-IR, and the space-borne WFIRST and JWST in the optical/near-IR/mid-IR. In addition, the X-ray and γ-ray polarization experiment POLAR is also introduced.

Instrumental background in balloon-borne gamma-ray spectrometers and techniques for its reduction

NASA Technical Reports Server (NTRS)

Gehrels, N.

1985-01-01

Instrumental background in balloon-borne gamma-ray spectrometers is presented. The calculations are based on newly available interaction cross sections and new analytic techniques, and are the most detailed and accurate published to date. Results compare well with measurements made in the 20 keV to 10 MeV energy range by the Goddard Low Energy Gamma-ray Spectrometer (LEGS). The principal components of the continuum background in spectrometers with GE detectors and thick active shields are: (1) elastic neutron scattering of atmospheric neutrons on the Ge nuclei; (2) aperture flux of atmospheric and cosmic gamma rays; (3) beta decays of unstable nuclides produced by nuclear interactions of atmospheric protons and neutrons with Ge nuclei; and (4) shield leakage of atmospheric gamma rays. The improved understanding of these components leads to several recommended techniques for reducing the background.

The Astrophysics Science Division Annual Report 2008

NASA Technical Reports Server (NTRS)

Oegerle, William; Reddy, Francis; Tyler, Pat

2009-01-01

The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radio wavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. This report includes the Division's activities during 2008.

Radiography apparatus using gamma rays emitted by water activated by fusion neutrons

DOEpatents

Smith, D.L.; Ikeda, Yujiro; Uno, Yoshitomo

1996-11-05

Radiography apparatus includes an arrangement for circulating pure water continuously between a location adjacent a source of energetic neutrons, such as a tritium target irradiated by a deuteron beam, and a remote location where radiographic analysis is conducted. Oxygen in the pure water is activated via the {sup 16}O(n,p){sup 16}N reaction using {sup 14}N-MeV neutrons produced at the neutron source via the {sup 3}H(d,n){sup 4}He reaction. Essentially monoenergetic gamma rays at 6.129 (predominantly) and 7.115 MeV are produced by the 7.13-second {sup 16}N decay for use in radiographic analysis. The gamma rays have substantial penetrating power and are useful in determining the thickness of materials and elemental compositions, particularly for metals and high-atomic number materials. The characteristic decay half life of 7.13 seconds of the activated oxygen is sufficient to permit gamma ray generation at a remote location where the activated water is transported, while not presenting a chemical or radioactivity hazard because the radioactivity falls to negligible levels after 1--2 minutes. 15 figs.

Radiography apparatus using gamma rays emitted by water activated by fusion neutrons

DOEpatents

Smith, Donald L.; Ikeda, Yujiro; Uno, Yoshitomo

1996-01-01

Radiography apparatus includes an arrangement for circulating pure water continuously between a location adjacent a source of energetic neutrons, such as a tritium target irradiated by a deuteron beam, and a remote location where radiographic analysis is conducted. Oxygen in the pure water is activated via the .sup.16 O(n,p).sup.16 N reaction using .sup.14 -MeV neutrons produced at the neutron source via the .sup.3 H(d,n).sup.4 He reaction. Essentially monoenergetic gamma rays at 6.129 (predominantly) and 7.115 MeV are produced by the 7.13-second .sup.16 N decay for use in radiographic analysis. The gamma rays have substantial penetrating power and are useful in determining the thickness of materials and elemental compositions, particularly for metals and high-atomic number materials. The characteristic decay half life of 7.13 seconds of the activated oxygen is sufficient to permit gamma ray generation at a remote location where the activated water is transported, while not presenting a chemical or radioactivity hazard because the radioactivity falls to negligible levels after 1-2 minutes.

Neutron star evolution and emission

NASA Astrophysics Data System (ADS)

Epstein, R. I.; Edwards, B. C.; Haines, T. J.

1997-01-01

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors investigated the evolution and radiation characteristics of individual neutron stars and stellar systems. The work concentrated on phenomena where new techniques and observations are dramatically enlarging the understanding of stellar phenomena. Part of this project was a study of x-ray and gamma-ray emission from neutron stars and other compact objects. This effort included calculating the thermal x-ray emission from young neutron stars, deriving the radio and gamma-ray emission from active pulsars and modeling intense gamma-ray bursts in distant galaxies. They also measured periodic optical and infrared fluctuations from rotating neutron stars and search for high-energy TeV gamma rays from discrete celestial sources.

GLAST Large Area Telescope Multiwavelength Planning

NASA Technical Reports Server (NTRS)

Thompson, D. J.; Cameron, R. A.; Digel, S. W.; Wood, K. S.

2006-01-01

Because gamma-ray astrophysics depends in many ways on multiwavelength studies, the GLAST Large Area Telescope (LAT) Collaboration has started multiwavelength planning well before the scheduled 2007 launch of the observatory. Some of the high-priority needs include: (1) radio and X-ray timing of pulsars; (2) expansion of blazar catalogs, including redshift measurements (3) improved observations of molecular clouds, especially at high galactic latitudes; (4) simultaneous broad-spectrum blazar flare measurements; (5) characterization of gamma-ray transients, including gamma ray bursts; (6) radio, optical, X-ray and TeV counterpart searches for unidentified gamma-ray sources. Work on the first three of these activities is needed before launch. The GLAST Large Area Telescope is an international effort, with U.S. funding provided by the Department of Energy and NASA.

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

PubMed

Tanaka, Kenichi; Endo, Satoru; Hoshi, Masaharu

2010-01-01

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

A Remote-operated System to Map Radiation Dose in the Fukushima Daiichi Primary Containment Vessel

NASA Astrophysics Data System (ADS)

Nancekievill, M.; Jones, A. R.; Joyce, M. J.; Lennox, B.; Watson, S.; Katakura, J.; Okumura, K.; Kamada, S.; Katoh, M.; Nishimura, K.

2018-01-01

This paper describes the development of a submersible system based on a remote-operated vehicle coupled with radiation detectors to map the interior of the reactors at the Fukushima Daiichi nuclear power station. It has the aim oflocating fuel debris. The AVEXIS submersible vehicle used in this study has been designed as a low-cost, potentially disposable, inspection platform that is the smallest of its class and is capable of being deployed through a 150 mm diameter access pipe. To map the gamma-ray environment, a cerium bromide scintillator detector with a small form factor has been incorporated into the AVEXIS to identify radioactive isotopes via gamma-ray spectroscopy. This provides the combined system with the potential to map gamma-ray spectra and particle locations throughout submerged, contaminated facilities, such as Units 1, 2 and 3 of the Fukushima Daiichi nuclear power plant. The hypothesis of this research is to determine the sensitivity of the combined system in a submerged environment that replicates the combination of gamma radiation and water submersion but at lower dose rates.

Method of photon spectral analysis

DOEpatents

Gehrke, Robert J.; Putnam, Marie H.; Killian, E. Wayne; Helmer, Richard G.; Kynaston, Ronnie L.; Goodwin, Scott G.; Johnson, Larry O.

1993-01-01

A spectroscopic method to rapidly measure the presence of plutonium in soils, filters, smears, and glass waste forms by measuring the uranium L-shell x-ray emissions associated with the decay of plutonium. In addition, the technique can simultaneously acquire spectra of samples and automatically analyze them for the amount of americium and .gamma.-ray emitting activation and fission products present. The samples are counted with a large area, thin-window, n-type germanium spectrometer which is equally efficient for the detection of low-energy x-rays (10-2000 keV), as well as high-energy .gamma. rays (>1 MeV). A 8192- or 16,384 channel analyzer is used to acquire the entire photon spectrum at one time. A dual-energy, time-tagged pulser, that is injected into the test input of the preamplifier to monitor the energy scale, and detector resolution. The L x-ray portion of each spectrum is analyzed by a linear-least-squares spectral fitting technique. The .gamma.-ray portion of each spectrum is analyzed by a standard Ge .gamma.-ray analysis program. This method can be applied to any analysis involving x- and .gamma.-ray analysis in one spectrum and is especially useful when interferences in the x-ray region can be identified from the .gamma.-ray analysis and accommodated during the x-ray analysis.

Method of photon spectral analysis

DOEpatents

Gehrke, R.J.; Putnam, M.H.; Killian, E.W.; Helmer, R.G.; Kynaston, R.L.; Goodwin, S.G.; Johnson, L.O.

1993-04-27

A spectroscopic method to rapidly measure the presence of plutonium in soils, filters, smears, and glass waste forms by measuring the uranium L-shell x-ray emissions associated with the decay of plutonium. In addition, the technique can simultaneously acquire spectra of samples and automatically analyze them for the amount of americium and [gamma]-ray emitting activation and fission products present. The samples are counted with a large area, thin-window, n-type germanium spectrometer which is equally efficient for the detection of low-energy x-rays (10-2,000 keV), as well as high-energy [gamma] rays (>1 MeV). A 8,192- or 16,384 channel analyzer is used to acquire the entire photon spectrum at one time. A dual-energy, time-tagged pulser, that is injected into the test input of the preamplifier to monitor the energy scale, and detector resolution. The L x-ray portion of each spectrum is analyzed by a linear-least-squares spectral fitting technique. The [gamma]-ray portion of each spectrum is analyzed by a standard Ge [gamma]-ray analysis program. This method can be applied to any analysis involving x- and [gamma]-ray analysis in one spectrum and is especially useful when interferences in the x-ray region can be identified from the [gamma]-ray analysis and accommodated during the x-ray analysis.

SBS 0846+513: a New Gamma-ray Emitting Narrow-line Seyfert 1 Galaxy

NASA Technical Reports Server (NTRS)

D'Ammando, F.; Orienti, M.; Finke, J.; Raiteri, C. M.; Angelakis, E.; Fuhrmann, L.; Giroletti, M.; Hovatta, T.; Max-Moerbeck, W.; Perkins, J. S.;

Exploring the High Energy Universe: GLAST Mission and Science

NASA Technical Reports Server (NTRS)

McEnery, Julie

2007-01-01

GLAST, the Gamma-Ray Large Area Space Telescope, is NASA's next-generation high-energy gamma-ray satellite scheduled for launch in Autumn 2007. GLAST will allow measurements of cosmic gamma-ray sources in t he 10 MeV to 100 GeV energy band to be made with unprecedented sensi tivity. Amongst its key scientific objectives are to understand part icle acceleration in Active Galactic Nuclei, Pulsars and Supernovae Remnants, to provide high resolution measurements of unidentified ga mma-ray sources, to study transient high energy emission from objects such as gamma-ray bursts, and to probe Dark Matter and the early Uni verse. Dr. McEnery will present an overview of the GLAST mission and its scientific goals.

Modulated high-energy gamma-ray emission from the microquasar Cygnus X-3.

PubMed

Abdo, A A; Ackermann, M; Ajello, M; Axelsson, M; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Baughman, B M; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Brez, A; Brigida, M; Bruel, P; Burnett, T H; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cecchi, C; Celik, O; Chaty, S; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Cominsky, L R; Conrad, J; Corbel, S; Corbet, R; Dermer, C D; de Palma, F; Digel, S W; do Couto e Silva, E; Drell, P S; Dubois, R; Dubus, G; Dumora, D; Farnier, C; Favuzzi, C; Fegan, S J; Focke, W B; Fortin, P; Frailis, M; Fusco, P; Gargano, F; Gehrels, N; Germani, S; Giavitto, G; Giebels, B; Giglietto, N; Giordano, F; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M-H; Grove, J E; Guillemot, L; Guiriec, S; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hill, A B; Hjalmarsdotter, L; Horan, D; Hughes, R E; Jackson, M S; Jóhannesson, G; Johnson, A S; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kawai, N; Kerr, M; Knödlseder, J; Kocian, M L; Koerding, E; Kuss, M; Lande, J; Latronico, L; Lemoine-Goumard, M; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Marchand, L; Marelli, M; Max-Moerbeck, W; Mazziotta, M N; McColl, N; McEnery, J E; Meurer, C; Michelson, P F; Migliari, S; Mitthumsiri, W; Mizuno, T; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nolan, P L; Norris, J P; Nuss, E; Ohsugi, T; Omodei, N; Ong, R A; Ormes, J F; Paneque, D; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Pooley, G; Porter, T A; Pottschmidt, K; Rainò, S; Rando, R; Ray, P S; Razzano, M; Rea, N; Readhead, A; Reimer, A; Reimer, O; Richards, J L; Rochester, L S; Rodriguez, J; Rodriguez, A Y; Romani, R W; Ryde, F; Sadrozinski, H F-W; Sander, A; Saz Parkinson, P M; Sgrò, C; Siskind, E J; Smith, D A; Smith, P D; Spinelli, P; Starck, J-L; Stevenson, M; Strickman, M S; Suson, D J; Takahashi, H; Tanaka, T; Thayer, J B; Thompson, D J; Tibaldo, L; Tomsick, J A; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Vasileiou, V; Vilchez, N; Vitale, V; Waite, A P; Wang, P; Wilms, J; Winer, B L; Wood, K S; Ylinen, T; Ziegler, M

2009-12-11

Microquasars are accreting black holes or neutron stars in binary systems with associated relativistic jets. Despite their frequent outburst activity, they have never been unambiguously detected emitting high-energy gamma rays. The Fermi Large Area Telescope (LAT) has detected a variable high-energy source coinciding with the position of the x-ray binary and microquasar Cygnus X-3. Its identification with Cygnus X-3 is secured by the detection of its orbital period in gamma rays, as well as the correlation of the LAT flux with radio emission from the relativistic jets of Cygnus X-3. The gamma-ray emission probably originates from within the binary system, opening new areas in which to study the formation of relativistic jets.

Evaluation of equivalent dose from neutrons and activation products from a 15-MV X-ray LINAC.

PubMed

Israngkul-Na-Ayuthaya, Isra; Suriyapee, Sivalee; Pengvanich, Phongpheath

2015-11-01

A high-energy photon beam that is more than 10 MV can produce neutron contamination. Neutrons are generated by the [γ,n] reactions with a high-Z target material. The equivalent neutron dose and gamma dose from activation products have been estimated in a LINAC equipped with a 15-MV photon beam. A Monte Carlo simulation code was employed for neutron and photon dosimetry due to mixed beam. The neutron dose was also experimentally measured using the Optically Stimulated Luminescence (OSL) under various conditions to compare with the simulation. The activation products were measured by gamma spectrometer system. The average neutron energy was calculated to be 0.25 MeV. The equivalent neutron dose at the isocenter obtained from OSL measurement and MC calculation was 5.39 and 3.44 mSv/Gy, respectively. A gamma dose rate of 4.14 µSv/h was observed as a result of activations by neutron inside the treatment machine. The gamma spectrum analysis showed (28)Al, (24)Na, (54)Mn and (60)Co. The results confirm that neutrons and gamma rays are generated, and gamma rays remain inside the treatment room after the termination of X-ray irradiation. The source of neutrons is the product of the [γ,n] reactions in the machine head, whereas gamma rays are produced from the [n,γ] reactions (i.e. neutron activation) with materials inside the treatment room. The most activated nuclide is (28)Al, which has a half life of 2.245 min. In practice, it is recommended that staff should wait for a few minutes (several (28)Al half-lives) before entering the treatment room after the treatment finishes to minimize the dose received. © The Author 2015. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

Development of observational and instrumental techniques in hard X-ray and medium energy gamma-ray astronomy

NASA Technical Reports Server (NTRS)

Pelling, M.

1985-01-01

The technical activities, scientific results, related space hardware projects and personnel of the high energy astrophysics program are reported. The development of observational and instrumental techniques in hard X-ray (0.001 to 100 keV) and medium energy gamma-ray (0.1 to 10 MeV) astronomy are examined. Many of these techniques were developed explicitly for use on high altitude balloons where most of the scientific results were obtained. The extensive observational activity using balloons are tabulated. Virtually every research activity will eventually result in a major space hardware development effort.

Results from the energetic gamma-ray experiment telescope (EGRET) on the Compton Observatory

NASA Technical Reports Server (NTRS)

Fichtel, C. E.; Bertsch, D. L.; Dingus, B.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

1993-01-01

The Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) covers the high energy gamma ray energy range, approximately 30 MeV to 30 GeV, with a sensitivity considerably greater than earlier high energy gamma-ray satellites. Thus far, 4 pulsars have been detected and their properties measured, including in 3 cases the energy spectrum as a function of phase. The details of the galactic plane are being mapped and a spectra of the center region has been obtained in good agreement with that expected from cosmic ray interactions. The Magellanic clouds have been examined with the Large Magellanic Cloud (LMC) having been detected at a level consistent with it having a cosmic ray density compatible with quasi-stable equilibrium. Sixteen Active Galactic Nuclei (AGN's) have been seen thus far with a high degree of certainty including 12 quasars and 4 BL Lac objects, but no Seyferts. Time variation has been detected in some of these AGN's

Discovery of localized TeV gamma-ray sources and diffuse TeV gamma-ray emission from the galactic plane with Milagro using a new background rejection technique

NASA Astrophysics Data System (ADS)

Abdo, Aws Ahmad

2007-08-01

Very high energy gamma-rays can be used to probe some of the most powerful astrophysical objects in the universe, such as active galactic nuclei, supernova remnants and pulsar-powered nebulae. The diffuse gamma radiation arising from the interaction of cosmic-ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of cosmic- rays. Milagro is a water Cherenkov detector that continuously views the entire overhead sky. The large field-of-view combined with the long observation time makes Milagro the most sensitive instrument available for the study of large, low surface brightness sources such as the diffuse gamma radiation arising from interactions of cosmic radiation with interstellar matter. In this thesis I present a new background rejection technique for the Milagro detector through the development of a new gamma hadron separation variable. The Abdo variable, A 4 , coupled with the weighting analysis technique significantly improves the sensitivity of the Milagro detector. This new analysis technique resulted in the first discoveries in Milagro. Four localized sources of TeV gamma-ray emission have been discovered, three of which are in the Cygnus region of the Galaxy and one closer to the Galactic center. In addition to these localized sources, a diffuse emission of TeV gamma-rays has been discovered from the Cygnus region of the Galaxy as well. However, the TeV gamma-ray flux as measured at ~12 TeV from the Cygnus region exceeds that predicted from a conventional model of cosmic-ray production and propagation. This observation indicates the existence of either hard-spectrum cosmic-ray sources and/or other sources of TeV gamma rays in the region. Other TeV gamma-ray source candidates with post-trial statistical significances of > 4s have also been observed in the Galactic plane.

Non-destructive in-situ method and apparatus for determining radionuclide depth in media

DOEpatents

Xu, X. George; Naessens, Edward P.

2003-01-01

A non-destructive method and apparatus which is based on in-situ gamma spectroscopy is used to determine the depth of radiological contamination in media such as concrete. An algorithm, Gamma Penetration Depth Unfolding Algorithm (GPDUA), uses point kernel techniques to predict the depth of contamination based on the results of uncollided peak information from the in-situ gamma spectroscopy. The invention is better, faster, safer, and/cheaper than the current practice in decontamination and decommissioning of facilities that are slow, rough and unsafe. The invention uses a priori knowledge of the contaminant source distribution. The applicable radiological contaminants of interest are any isotopes that emit two or more gamma rays per disintegration or isotopes that emit a single gamma ray but have gamma-emitting progeny in secular equilibrium with its parent (e.g., .sup.60 Co, .sup.235 U, and .sup.137 Cs to name a few). The predicted depths from the GPDUA algorithm using Monte Carlo N-Particle Transport Code (MCNP) simulations and laboratory experiments using .sup.60 Co have consistently produced predicted depths within 20% of the actual or known depth.

Conceptual design of the gamma-to-electron magnetic spectrometer for the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Y., E-mail: yhkim@lanl.gov; Herrmann, H. W.; Jorgenson, H. J.

2014-11-15

The Gamma-to-Electron Magnetic Spectrometer (GEMS) diagnostic is designed to measure the prompt γ-ray energy spectrum during high yield deuterium-tritium (DT) implosions at the National Ignition Facility (NIF). The prompt γ-ray spectrum will provide “burn-averaged” observables, including total DT fusion yield, total areal density (ρR), ablator ρR, and fuel ρR. These burn-averaged observables are unique because they are essentially averaged over 4π, providing a global reference for the line-of-sight-specific measurements typical of x-ray and neutron diagnostics. The GEMS conceptual design meets the physics-based requirements: ΔE/E = 3%–5% can be achieved in the range of 2–25 MeV γ-ray energy. Minimum DT neutronmore » yields required for 15% measurement uncertainty at low-resolution mode are: 5 × 10{sup 14} DT-n for ablator ρR (at 0.2 g/cm{sup 2}); 2 × 10{sup 15} DT-n for total DT yield (at 4.2 × 10{sup −5} γ/n); and 1 × 10{sup 16} DT-n for fuel ρR (at 1 g/cm{sup 2})« less

How gamma-rays and electron-beam irradiation would affect the antimicrobial activity of differently processed wild mushroom extracts?

PubMed

Alves, M J; Fernandes, Â; Barreira, J C M; Lourenço, I; Fernandes, D; Moura, A; Ribeiro, A R; Salgado, J; Antonio, A; Ferreira, I C F R

2015-03-01

The effects of irradiation (gamma-rays and electron-beams), up to 10 kGy, in the antimicrobial activity of mushroom species (Boletus edulis, Hydnum repandum, Macrolepiota procera and Russula delica) differently processed (fresh, dried, freeze) were evaluated. Clinical isolates with different resistance profiles from hospitalized patients in Local Health Unit of Mirandela, Northeast of Portugal, were used as target micro-organisms. The mushrooms antimicrobial activity did not suffer significant changes that might compromise applying irradiation as a possible mushroom conservation technology. Two kGy dose (independently of using gamma-rays or electron-beams) seemed to be the most suitable choice to irradiate mushrooms. This study provides important results in antimicrobial activity of extracts prepared from irradiated mushroom species. © 2014 The Society for Applied Microbiology.

Performance of the EGRET astronomical gamma ray telescope

NASA Technical Reports Server (NTRS)

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.

Increased Gamma-ray Activity from the FSRQ PKS 1424-41

NASA Astrophysics Data System (ADS)

Ojha, Roopesh; Dutka, Michael

2012-10-01

The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope has observed increased gamma-ray emission from a source positionally coincident with the flat spectrum radio quasar PKS 1424-41 (1424-418; 2FGL J1428.0-4206, Nolan et al. 2012, ApJS, 199, 31). PKS 1424-41 has the coordinates RA=14h27m56.3s, DEC= -42d06'19.4", J2000, (Johnston et al. 1995, AJ, 110, 880).

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parvin, Daniel; Clarke, Sean; Humes, Sarah J.

2013-07-01

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

High Resolution Rapid Response Observations of Compact Radio Sources with the Ceduna Hobart Interferometer (CHI)

NASA Technical Reports Server (NTRS)

Blanchard, Jay M.; Lovell, James E. J.; Ojha, Roopesh; Kadler, Matthias; Dickey, John M.; Edwards, Philip G.

2011-01-01

Context. Frequent, simultaneous observations across the electromagnetic spectrum are essential to the study of a range of astrophysical phenomena including Active Galactic Nuclei. A key tool of such studies is the ability to observe an object when it flares i.e. exhibits a rapid and significant increase in its flux density. Aims. We describe the specific observational procedures and the calibration techniques that have been developed and tested to create a single baseline radio interferometer. that can rapidly observe a flaring object. This is the only facility that is dedicated to rapid high resolution radio observations of an object south of -30 degrees declination. An immediate application is to provide rapid contemporaneous radio coverage of AGN flaring at y-ray frequencies detected by the Fermi Gamma-ray Space Telescope. Methods. A single baseline interferometer was formed with radio telescopes in Hobart, Tasmania and Ceduna, South Australia. A software correlator was set up at the University of Tasmania to correlate these data. Results. Measurements of the flux densities of flaring objects can be made using our observing strategy within half an hour of a triggering event. These observations can be calibrated with amplitude errors better than 20%. Lower limits to the brightness temperatures of the sources can also be calculated using CHI. Key words. instrumentation:interferometers - galaxies:active - galaxies:jets - galaxies:nuclei quasars:general gamma rays:galaxies- 1.

The High Energy Universe: Ultra-High Energy Events in Astrophysics and Cosmology

NASA Astrophysics Data System (ADS)

Mészáros, Péter

2010-09-01

1. Introduction; 2. The nuts and bolts of the Universe; 3. Cosmology; 4. Cosmic structure formation; 5. Active galaxies; 6. Stellar cataclysms; 7. Gamma ray bursts; 8. GeV and TeV gamma rays; 9. Gravitational waves; 10. Cosmic rays; 11. Neutrinos; 12. Dark dreams, Higgs and beyond.

HAGRID/ VANDLE spectroscopy of Rb decays

NASA Astrophysics Data System (ADS)

King, Thomas; Grzywacz, Robert; Taylor, Steven; Paulauskas, Stanley; Smith, Karl; Vandle Collaboration

2017-09-01

Many neutron-rich isotopes that contribute in both decay heat production and r-process nucleosynthesis have substantial beta-delayed neutron branching ratios. Beta-delayed neutron emission is a relatively complicated mechanism which can leave the daughter in an gamma-emitting excited state. A comprehensive understanding of their energy output and decay strength, S_beta, therefore requires the detection of both neutrons and gamma rays in coincidence. A series of measurements of delayed neutron precursors were performed at the On-Line Test Facility (OLTF) at the Oak Ridge National Laboratories using chemically selective ion sources and an enhanced VANDLE array. The main goal of this experiment was to revisit the decays of IAEA-marked priority precursors, including bromine, rubidium, cesium, and iodine, that are required to model the global properties in the fission of 238U.The unique data set, with neutron and gamma ray coincidences, benefited from the addition of a high-efficiency gamma-ray array, consisting of 16 LaBr3 crystals (HAGRiD), and a set of large volume NaI detectors to the VANDLE array. Characterization of and preliminary results from the new gamma-ray array for the decays of 94Rb and 97Rb will be presented. National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Award No. DE-NA0002132 and the Office of Nuclear Physics, U.S. Department of Energy under Award No. DE-FG02-96ER40983.

Apollo-Soyuz pamphlet no. 2: X-rays, gamma-rays. [experimental design

NASA Technical Reports Server (NTRS)

Page, L. W.; From, T. P.

1977-01-01

The nature of high energy radiation and its penetration through earth's atmosphere is examined with emphasis on X-rays, gamma rays, and cosmic radiation and the instruments used in their detection. The history of radio astronomy and the capabilities of the Uhuru satellite are summarized. The ASTP soft X-ray experiment (MA-048) designed to study the spectra in the range from 0.1 to 10 keV and survey the background over a large section of the sky is described, as well as the determination of SMC C-1 as an X-ray pulsar. The crystal activation experiment (MA-151) used to measure the radioactive isotopes created by cosmic rays in crystals used for gamma ray detectors is also discussed.

Gamma-Ray Imaging for Explosives Detection

NASA Technical Reports Server (NTRS)

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

2008-01-01

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

Multiwavelength Observations of the Soft Gamma Repeater SGR 1900+14 During Its 2001 April Activation

NASA Technical Reports Server (NTRS)

Kouveliotou, C.; Tennant, A.; Woods, P. M.; Weisskopf, M. C.; Hurley, K.; Fender, R. P.; Garrington, S. T.; Patel, S. K.; Goegues, E.

2001-01-01

The soft gamma repeater SGR 1900+14 became active on 2001 April 18 after about two years of quiescence; it had remained at a very low state of activity since the fall of 1998, when it exhibited extraordinary flaring. We have observed the source in the gamma-rays and X-rays with Ulysses and Chandra and in the radio with MERLIN. We report here the confirmation of a two-component X-ray spectrum (power law and blackbody), indicating emission from the neutron star surface. We have determined that there is a dust halo, due to scattering in the interstellar medium, surrounding the source that extends up to approximately 100 arcsec from the center of SGR 1900+14.

OSSE observations of the ultraluminous infrared galaxies ARP 220 and MRK 273

NASA Technical Reports Server (NTRS)

Dermer, C. D.; Shier, L. M.; Sturner, S. J.; McNaron-Brown, K.; Bland-Hawthorn, J.

1997-01-01

The results of oriented scintillation spectrometer experiment (OSSE) observations of the ultraluminous infrared galaxies Arp 220 and Mrk 273 are reported. The pointings of Arp 220 and Mrk 273 concentrated on their upper limits. The gamma ray luminosities from these sources were found to be between one and two orders of magnitude smaller than the infrared luminosities. Multiwavelength luminosity spectra are produced from the radio to the gamma ray regime, and are compared with the typical multiwavelength spectra of active galactic nuclei. The lack of measured gamma ray emission provides no evidence for the existence of buried active galactic nuclei in these ultraluminous infrared galaxies, but is consistent with an origin of the infrared luminosity from starburst activity.

Gamma ray astrophysics and signatures of axion-like particles

NASA Astrophysics Data System (ADS)

Serpico, Pasquale D.

2009-02-01

We propose that axion-like particles (ALPs) with a two-photon vertex, consistent with all astrophysical and laboratory bounds, may lead to effects in the spectra of high-energy gamma-ray sources detectable by satellite or ground-based telescopes. We discuss two kinds of signatures: (i) a peculiar spectral depletion due to gamma rays being converted into ALPs in the magnetic fields of efficient astrophysical accelerators according to the “Hillas criterion”, such as jets of active galactic nuclei or hot spots of radio galaxies; (ii) an appearance of otherwise invisible sources in the GeV or TeV sky due to back-conversion of an ALP flux (associated with gamma-ray emitters suffering some attenuation) in the magnetic field of the Milky Way. These two mechanisms might also provide an exotic way to avoid the exponential cutoff of very high energy gamma-rays expected due to the pair production onto the extragalactic background light.

The 2001 April Burst Activation of SGR 1900+14: Pulse Properties and Torque

NASA Technical Reports Server (NTRS)

Woods, P. M.; Kouveliotou, C.; Goegues, E.; Finger, M. H.; Feroci, M.; Mereghetti, S.; Swank, J. H.; Hurley, K.; Heise, J.; Smith, D.;

KSC-08pd1138

NASA Image and Video Library

2008-05-04

CAPE CANAVERAL, Fla. -- NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft is moved toward the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date still is to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1139

NASA Image and Video Library

2008-05-04

CAPE CANAVERAL, Fla. -- NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft is moved into the Hazardous Processing Facility for fueling. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date still is to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1038

NASA Image and Video Library

2008-04-25

CAPE CANAVERAL, Fla. – At the Astrotech payload processing facility, technicians give NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft a final cleaning. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1036

NASA Image and Video Library

2008-04-25

CAPE CANAVERAL, Fla. – At the Astrotech payload processing facility, technicians conduct black light inspection on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1037

NASA Image and Video Library

2008-04-25

CAPE CANAVERAL, Fla. – At the Astrotech payload processing facility, technicians give NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft a final cleaning. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1034

NASA Image and Video Library

2008-04-25

CAPE CANAVERAL, Fla. – At the Astrotech payload processing facility, technicians conduct black light inspection on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1035

NASA Image and Video Library

2008-04-25

CAPE CANAVERAL, Fla. – At the Astrotech payload processing facility, technicians conduct black light inspection on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Jim Grossmann

Measurement of the high-energy gamma-ray emission from the Moon with the Fermi Large Area Telescope

DOE PAGES

Ackermann, M.; Ajello, M.; Albert, A.; ...

2016-04-08

We have measured the gamma-ray emission spectrum of the Moon using the data collected by the Large Area Telescope onboard the Fermi satellite during its first seven years of operation, in the energy range from 30 MeV up to a few GeV. We have also studied the time evolution of the flux, finding a correlation with the solar activity. We have developed a full Monte Carlo simulation describing the interactions of cosmic rays with the lunar surface. The results of the present analysis can be explained in the framework of this model, where the production of gamma rays is duemore » to the interactions of cosmic-ray proton and helium nuclei with the surface of the Moon. Lastly, we have used our simulation to derive the cosmic-ray proton and helium spectra near Earth from the Moon gamma-ray data.« less

Measurement of the High-Energy Gamma-Ray Emission from the Moon with the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.;

A connection between star formation activity and cosmic rays in the starburst galaxy M82.

PubMed

2009-12-10

Although Galactic cosmic rays (protons and nuclei) are widely believed to be mainly accelerated by the winds and supernovae of massive stars, definitive evidence of this origin remains elusive nearly a century after their discovery. The active regions of starburst galaxies have exceptionally high rates of star formation, and their large size-more than 50 times the diameter of similar Galactic regions-uniquely enables reliable calorimetric measurements of their potentially high cosmic-ray density. The cosmic rays produced in the formation, life and death of massive stars in these regions are expected to produce diffuse gamma-ray emission through interactions with interstellar gas and radiation. M82, the prototype small starburst galaxy, is predicted to be the brightest starburst galaxy in terms of gamma-ray emission. Here we report the detection of >700-GeV gamma-rays from M82. From these data we determine a cosmic-ray density of 250 eV cm(-3) in the starburst core, which is about 500 times the average Galactic density. This links cosmic-ray acceleration to star formation activity, and suggests that supernovae and massive-star winds are the dominant accelerators.

Recent Re-Measurement of Neutron and Gamma-Ray Spectra 1080 Meters from the APRD (Army Pulse Radiation Division) Critical Facility,

DTIC Science & Technology

1984-01-01

TISSUE-EQUIVALENT ION CHAMBER GM - GEIGER-MUELLER COUNTER TE-GM - DIFFERENCE BETWEEN TE AND GM DATA MICRODOSE - MICRODOSIMETRY USING 0.5" ROSSI COUNTER...KERMA 4.26+8 1979 APRO NE-213+PR NEUTRON KERMA 4.26+8 1979 WWD NE-213 NEUTRON KERMA 3.10+8 > 550 KEV 1980 DREO MICRODOSE NEUTRON KERMA 4.32+8 1979...APRD GM GAMMA KERMA 3.86+7 1979 WWD NE-213 GAMMA KERMA 4.34+7 > 450 KEV 1980 DREO MICRODOSE GAMMA KERMA 3.90+7 76 1979 APRD TE TOTAL KERMA 4.50+8 50 c.c

PING Gamma Ray and Neutron Measurements of a Meter-Sized Carbonaceous Asteroid Analog

NASA Technical Reports Server (NTRS)

Bodnarik, J.; Burger, D.; Evans, L.; Floyd, S.; Lim, L.; McClanahan, T.; Namkung, M.; Nowicki, S.; Parsons, A.; Schweitzer, J.;

Precision Gamma-Ray Branching Ratios for Long-Lived Radioactive Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tonchev, Anton

Many properties of the high-energy-density environments in nuclear weapons tests, advanced laser-fusion experiments, the interior of stars, and other astrophysical bodies must be inferred from the resulting long-lived radioactive nuclei that are produced. These radioactive nuclei are most easily and sensitively identified by studying the characteristic gamma rays emitted during decay. Measuring a number of decays via detection of the characteristic gamma-rays emitted during the gamma-decay (the gamma-ray branching ratio) of the long-lived fission products is one of the most straightforward and reliable ways to determine the number of fissions that occurred in a nuclear weapon test. The fission productsmore » 147Nd, 144Ce, 156Eu, and certain other long-lived isotopes play a crucial role in science-based stockpile stewardship, however, the large uncertainties (about 8%) on the branching ratios measured for these isotopes are currently limiting the usefulness of the existing data [1,2]. We performed highly accurate gamma-ray branching-ratio measurements for a group of high-atomic-number rare earth isotopes to greatly improve the precision and reliability with which the fission yield and reaction products in high-energy-density environments can be determined. We have developed techniques that take advantage of new radioactive-beam facilities, such as DOE's CARIBU located at Argonne National Laboratory, to produce radioactive samples and perform decay spectroscopy measurements. The absolute gamma-ray branching ratios for 147Nd and 144Ce are reduced <2% precision. In addition, high-energy monoenergetic neutron beams from the FN Tandem accelerator in TUNL at Duke University was used to produce 167Tm using the 169Tm(n,3n) reaction. Fourtime improved branching ratio of 167Tm is used now to measure reaction-in-flight (RIF) neutrons from a burning DT capsule at NIF [10]. This represents the first measurement of RIF neutrons in any laboratory fusion system, and the magnitude of the signal has important implications for fundamental plasma science and for weapons physics.« less

Radio galaxies dominate the high-energy diffuse gamma-ray background

DOE PAGES

Hooper, Dan; Linden, Tim; Lopez, Alejandro

2016-08-09

It has been suggested that unresolved radio galaxies and radio quasars (sometimes referred to as misaligned active galactic nuclei) could be responsible for a significant fraction of the observed diffuse gamma-ray background. In this study, we use the latest data from the Fermi Gamma-Ray Space Telescope to characterize the gamma-ray emission from a sample of 51 radio galaxies. In addition to those sources that had previously been detected using Fermi data, we report here the first statistically significant detection of gamma-ray emission from the radio galaxies 3C 212, 3C 411, and B3 0309+411B. Combining this information with the radio fluxes,more » radio luminosity function, and redshift distribution of this source class, we find that radio galaxies dominate the diffuse gamma-ray background, generating 77.2(+25.4)(-9.4)% of this emission at energies above ~1 GeV . We discuss the implications of this result and point out that it provides support for scenarios in which IceCube's high-energy astrophysical neutrinos also originate from the same population of radio galaxies.« less

Spectral evolution of active galactic nuclei: A unified description of the X-ray and gamma

NASA Technical Reports Server (NTRS)

Leiter, D.; Boldt, E.

1982-01-01

A model for spectral evolution is presented whereby active galactic nuclei (AGN) of the type observed individually emerge from an earlier stage at z approx = 4 in which they are the thermal X-ray sources responsible for most of the cosmic X-ray background (CXB). The conjecture is pursued that these precursor objects are initially supermassive Schwarzschild black holes with accretion disks radiating near the Eddington luminosity limit. It is noted that after approx. 10 to the 8th power years these central black holes are spun-up to a canonical Kerr equilibrium state (A/M = 0.998; Thorne 1974) and shown how they then can lead to spectral evolution involving non-thermal emission extending to gamma rays, at the expense of reduced thermal disk radiation. That major portion of the CXB remaining after the contribution of usual AGN are considered, while a superposition of AGN sources at z 1 can account for the gamma ray background. Extensive X-ray measurements carried out with the HEAO 1 and 2 missions as well as gamma ray and optical data are shown to compare favorably with principal features of this model.

Gamma ray cosmology: The extra galactic gamma spectrum and methods to detect the underlying source

NASA Technical Reports Server (NTRS)

Cline, David B.

1990-01-01

The possible sources of extragalactic gamma rays and methods to distinguish the different sources are discussed. The sources considered are early universe decays and annihilation of Particles, active galactic nuclei (AGN) sources, and baryon-antibaryon annihilation in a baryon symmetric cosmology. The energy spectrum and possible angular fluctuations due to these sources are described.

Spectrum of Very High Energy Gamma-Rays from the blazar 1ES 1959+650 during Flaring Activity in 2002

NASA Astrophysics Data System (ADS)

Daniel, M. K.; Badran, H. M.; Bond, I. H.; Boyle, P. J.; Bradbury, S. M.; Buckley, J. H.; Carter-Lewis, D. A.; Catanese, M.; Celik, O.; Cogan, P.; Cui, W.; D'Vali, M.; de la Calle Perez, I.; Duke, C.; Falcone, A.; Fegan, D. J.; Fegan, S. J.; Finley, J. P.; Fortson, L. F.; Gaidos, J. A.; Gammell, S.; Gibbs, K.; Gillanders, G. H.; Grube, J.; Hall, J.; Hall, T. A.; Hanna, D.; Hillas, A. M.; Holder, J.; Horan, D.; Humensky, T. B.; Jarvis, A.; Jordan, M.; Kenny, G. E.; Kertzman, M.; Kieda, D.; Kildea, J.; Knapp, J.; Kosack, K.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; Le Bohec, S.; Linton, E.; Lloyd-Evans, J.; Milovanovic, A.; Moriarty, P.; Müller, D.; Nagai, T.; Nolan, S.; Ong, R. A.; Pallassini, R.; Petry, D.; Power-Mooney, B.; Quinn, J.; Quinn, M.; Ragan, K.; Rebillot, P.; Reynolds, P. T.; Rose, H. J.; Schroedter, M.; Sembroski, G. H.; Swordy, S. P.; Syson, A.; Vassiliev, V. V.; Wakely, S. P.; Walker, G.; Weekes, T. C.; Zweerink, J.

2005-03-01

The blazar 1ES 1959+650 was observed in a flaring state with the Whipple 10 m Imaging Atmospheric Cerenkov Telescope in 2002 May. A spectral analysis has been carried out on the data from that time period, and the resulting very high energy gamma-ray spectrum (E>=316 GeV) can be well fitted by a power law of differential spectral index α=2.78+/-0.12stat+/-0.21sys. On 2002 June 4, the source flared dramatically in the gamma-ray range without any coincident increase in the X-ray emission, providing the first unambiguous example of an ``orphan'' gamma-ray flare from a blazar. The gamma-ray spectrum for these data can also be described by a simple power-law fit with α=2.82+/-0.15stat+/-0.30sys. There is no compelling evidence for spectral variability or for any cutoff to the spectrum.

Gamma-ray Astrophysics with AGILE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Longo, Francesco; Tavani, M.; Barbiellini, G.

2007-07-12

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

Fermi LAT detection of increase gamma-ray emission from OJ 248

NASA Astrophysics Data System (ADS)

Orienti, M.; D'Ammando, F.

2012-09-01

The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar OJ 248 (also known as 2FGL J0830.5+2407, Nolan et al. 2012, ApJS, 199, 31) with radio coordinates R.A.: 127.7170254 deg, Dec: 24.1832836 deg (J2000, Johnston et al. 1995, AJ, 110, 880) at redshift z=0.94 (Hewitt & Burbidge 1993, ApJS, 87, 451).

Fermi LAT detection of increased gamma-ray activity from the blazar TXS 1318+225

NASA Astrophysics Data System (ADS)

Torresi, E.; D'Ammando, F.; Tanaka, Y.

2012-11-01

The Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope, has observed an increase in the gamma-ray flux from a source positionally consistent with the flat spectrum radio quasar TXS 1318+225 (z=0.943, Sowards-Emmerd et al. 2003, ApJ, 590, 109; RA=200.2966771 deg, Dec=22.2700300 deg, J2000), also known as 2FGL J1321.1+2215 (Nolan et al. 2012, ApJS, 199, 31).

Low-background gamma-ray spectrometry for the international monitoring system

DOE PAGES

Greenwood, L. R.; Cantaloub, M. G.; Burnett, J. L.; ...

2016-12-28

PNNL has developed two low-background gamma-ray spectrometers in a new shallow underground laboratory, thereby significantly improving its ability to detect low levels of gamma-ray emitting fission or activation products in airborne particulate in samples from the IMS (International Monitoring System). Furthermore, the combination of cosmic veto panels, dry nitrogen gas to reduce radon and low background shielding results in a reduction of the background count rate by about a factor of 100 compared to detectors operating above ground at our laboratory.

Lunar elemental analysis obtained from the Apollo gamma-ray and X-ray remote sensing experiment

NASA Technical Reports Server (NTRS)

Trombka, J. I.; Arnold, J. R.; Adler, I.; Metzger, A. E.; Reedy, R. C.

1974-01-01

Gamma ray and X-ray spectrometers carried in the service module of the Apollo 15 and 16 spacecraft were employed for compositional mapping of the lunar surface. The measurements involved the observation of the intensity and characteristics energy distribution of gamma rays and X-rays emitted from the lunar surface. A large scale compositional map of over 10 percent of the lunar surface was obtained from an analysis of the observed spectra. The objective of the X-ray experiment was to measure the K spectral lines from Mg, Al, and Si. Spectra were obtained and the data were reduced to Al/Si and Mg/Si intensity ratios and ultimately to chemical ratios. The objective of the gamma-ray experiment was to measure the natural and cosmic ray induced activity emission spectrum. At this time, the elemental abundances for Th, U, K, Fe, Ti, Si, and O have been determined over a number of major lunar regions.

Constraints on the gamma-ray emission from the cluster-scale AGN outburst in the Hydra A galaxy cluster

NASA Astrophysics Data System (ADS)

HESS Collaboration; Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker, J.; Bernlöhr, K.; Birsin, E.; Biteau, J.; Bochow, A.; Boisson, C.; Bolmont, J.; Bordas, P.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Büsching, I.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Cologna, G.; Conrad, J.; Couturier, C.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; O'C. Drury, L.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Gast, H.; Gérard, L.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Göring, D.; Grondin, M.-H.; Häffner, S.; Hague, J. D.; Hahn, J.; Hampf, D.; Harris, J.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Jung, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Khélifi, B.; Klochkov, D.; Kluźniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Krayzel, F.; Laffon, H.; Lamanna, G.; Lenain, J.-P.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Maurin, G.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Moderski, R.; Mohamed, M.; Moulin, E.; Naumann, C. L.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nguyen, N.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; de Oña Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perez, J.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raue, M.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sheidaei, F.; Skilton, J. L.; Sol, H.; Spengler, G.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Szostek, A.; Tavernet, J.-P.; Terrier, R.; Tluczykont, M.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Viana, A.; Vincent, P.; Völk, H. J.; Volpe, F.; Vorobiov, S.; Vorster, M.; Wagner, S. J.; Ward, M.; White, R.; Wierzcholska, A.; Zacharias, M.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.; Ali, M. O.

2012-09-01

Context. In some galaxy clusters, powerful active galactic nuclei (AGN) have blown bubbles with cluster scale extent into the ambient medium. The main pressure support of these bubbles is not known to date, but cosmic rays are a viable possibility. For such a scenario copious gamma-ray emission is expected as a tracer of cosmic rays from these systems. Aims: Hydra A, the closest galaxy cluster hosting a cluster scale AGN outburst, located at a redshift of 0.0538, is investigated for being a gamma-ray emitter with the High Energy Stereoscopic System (H.E.S.S.) array and the Fermi Large Area Telescope (Fermi-LAT). Methods: Data obtained in 20.2 h of dedicated H.E.S.S. observations and 38 months of Fermi-LAT data, gathered by its usual all-sky scanning mode, have been analyzed to search for a gamma-ray signal. Results: No signal has been found in either data set. Upper limits on the gamma-ray flux are derived and are compared to models. These are the first limits on gamma-ray emission ever presented for galaxy clusters hosting cluster scale AGN outbursts. Conclusions: The non-detection of Hydra A in gamma-rays has important implications on the particle populations and physical conditions inside the bubbles in this system. For the case of bubbles mainly supported by hadronic cosmic rays, the most favorable scenario, which involves full mixing between cosmic rays and embedding medium, can be excluded. However, hadronic cosmic rays still remain a viable pressure support agent to sustain the bubbles against the thermal pressure of the ambient medium. The largest population of highly-energetic electrons, which are relevant for inverse-Compton gamma-ray production is found in the youngest inner lobes of Hydra A. The limit on the inverse-Compton gamma-ray flux excludes a magnetic field below half of the equipartition value of 16 μG in the inner lobes.

Multiwavelength observations of unidentified high energy gamma ray sources

NASA Technical Reports Server (NTRS)

Halpern, Jules P.

1993-01-01

As was the case for COS B, the majority of high-energy (greater than 100 MeV) gamma-ray sources detected by the EGRET instrument on GRO are not immediately identifiable with cataloged objects at other wavelengths. These persistent gamma-ray sources are, next to the gamma-ray bursts, the least understood objects in the universe. Even a rudimentary understanding of their nature awaits identifications and follow-up work at other wavelengths to tell us what they are. The as yet unidentified sources are potentially the most interesting, since they may represent unrecognized new classes of astronomical objects, such as radio-quiet pulsars or new types of active galactic nuclei (AGN's). This two-year investigation is intended to support the analysis, correlation, and theoretical interpretation of data that we are obtaining at x ray, optical, and radio wavelengths in order to render the gamma-ray data interpretable. According to plan, in the first year concentration was on the identification and study of Geminga. The second year will be devoted to studies of similar unidentified gamma-ray sources which will become available in the first EGRET catalogs. The results obtained so far are presented in the two papers which are reproduced in the Appendix. In these papers, we discuss the pulse profiles of Geminga, the geometry and efficiency of the magnetospheric accelerator, the distance to Geminga, the implications for theories of polar cap heating, the effect of the magnetic field on the surface emission and environment of the neutron star, and possible interpretations of a radio-quiet Geminga. The implications of the other gamma-ray pulsars which were discovered to have high gamma-ray efficiency are also discussed, and the remaining unidentified COS B sources are attributed to a population of efficient gamma-ray sources, some of which may be radio quiet.

Development of an omnidirectional gamma-ray imaging Compton camera for low-radiation-level environmental monitoring

NASA Astrophysics Data System (ADS)

Watanabe, Takara; Enomoto, Ryoji; Muraishi, Hiroshi; Katagiri, Hideaki; Kagaya, Mika; Fukushi, Masahiro; Kano, Daisuke; Satoh, Wataru; Takeda, Tohoru; Tanaka, Manobu M.; Tanaka, Souichi; Uchida, Tomohisa; Wada, Kiyoto; Wakamatsu, Ryo

2018-02-01

We have developed an omnidirectional gamma-ray imaging Compton camera for environmental monitoring at low levels of radiation. The camera consisted of only six CsI(Tl) scintillator cubes of 3.5 cm, each of which was readout by super-bialkali photo-multiplier tubes (PMTs). Our camera enables the visualization of the position of gamma-ray sources in all directions (∼4π sr) over a wide energy range between 300 and 1400 keV. The angular resolution (σ) was found to be ∼11°, which was realized using an image-sharpening technique. A high detection efficiency of 18 cps/(µSv/h) for 511 keV (1.6 cps/MBq at 1 m) was achieved, indicating the capability of this camera to visualize hotspots in areas with low-radiation-level contamination from the order of µSv/h to natural background levels. Our proposed technique can be easily used as a low-radiation-level imaging monitor in radiation control areas, such as medical and accelerator facilities.

Measurement and simulation of a Compton suppression system for safeguards application

NASA Astrophysics Data System (ADS)

Lee, Seung Kyu; Seo, Hee; Won, Byung-Hee; Lee, Chaehun; Shin, Hee-Sung; Na, Sang-Ho; Song, Dae-Yong; Kim, Ho-Dong; Park, Geun-Il; Park, Se-Hwan

2015-11-01

Plutonium (Pu) contents in spent nuclear fuels, recovered uranium (U) or uranium/transuranium (U/TRU) products must be measured in order to secure the safeguardability of a pyroprocessing facility. Self-induced X-Ray fluorescence (XRF) and gamma-ray spectroscopy are useful techniques for determining Pu-to-U ratios and Pu isotope ratios of spent fuel. Photon measurements of spent nuclear fuel by using high-resolution spectrometers such as high-purity germanium (HPGe) detectors show a large continuum background in the low-energy region, which is due in large part to Compton scattering of energetic gamma rays. This paper proposes a Compton suppression system for reducing of the Compton continuum background. In the present study, the system was configured by using an HPGe main detector and a BGO (bismuth germanate: Bi4Ge3O12) guard detector. The system performances for gamma-ray measurement and XRF were evaluated by means of Monte Carlo simulations and measurements of the radiation source. The Monte Carlo N-Particle eXtended (MCNPX) simulations were performed using the same geometry as for the experiments, and considered, for exact results, the production of secondary electrons and photons. As a performance test of the Compton suppression system, the peak-to-Compton ratio, which is a figure of merit to evaluate the gamma-ray detection, was enhanced by a factor of three or more when the Compton suppression system was used.

Elemental analysis using natural gamma-ray spectroscopy

NASA Astrophysics Data System (ADS)

Aksoy, A.; Naqvi, A. A.; Khiari, F. Z.; Abujarad, F.; Al-Ohali, M.; Sumani, M.

1994-12-01

A gamma-ray spectroscopy setup has been recently established to measure the natural gamma-ray activity from potassium ( 40K), uranium ( 238U), and thorium ( 232Th) isotopes in rock samples of oil well-logs. The setup mainly consists of a shielded 135 cm 3 Hyper Pure Germanium (HPGe) detector, a 5 in. × 5 in. NaT(Tl) detector and a PC based data acquisition system. The core samples, with 70-100 g weight, have cylindrical geometry and are sealed such that radon gas from 238U decay would not escape from the sample. For room background subtraction, pure quartz samples identical to core samples were used. The sample is first counted with the HPGe detector to identify the elements through its characteristics gamma rays. Then the elemental concentration is determined by counting the sample with a NaI detector. In order to determine the absolute concentrations, the sample activity is compared with the activities of standards supplied by NIST and IAEA. The concentration of 238U and 232Th has been determined in ppm range with that of 40K in wt.%.

SEARCH FOR GAMMA-RAY EMISSION FROM X-RAY-SELECTED SEYFERT GALAXIES WITH FERMI-LAT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ackermann, M.; Ajello, M.; Allafort, A.

We report on a systematic investigation of the {gamma}-ray properties of 120 hard X-ray-selected Seyfert galaxies classified as 'radio-quiet' objects, utilizing the three-year accumulation of Fermi Large Area Telescope (LAT) data. Our sample of Seyfert galaxies is selected using the Swift Burst Alert Telescope 58 month catalog, restricting the analysis to the bright sources with average hard X-ray fluxes F{sub 14-195keV} {>=} 2.5 Multiplication-Sign 10{sup -11} erg cm{sup -2} s{sup -1} at high Galactic latitudes (|b| > 10 Degree-Sign ). In order to remove 'radio-loud' objects from the sample, we use the 'hard X-ray radio loudness parameter', R{sub rX}, definedmore » as the ratio of the total 1.4 GHz radio to 14-195 keV hard X-ray energy fluxes. Among 120 X-ray bright Seyfert galaxies with R{sub rX} <10{sup -4}, we did not find a statistically significant {gamma}-ray excess (TS > 25) positionally coincident with any target Seyferts, with possible exceptions of ESO 323-G077 and NGC 6814. The mean value of the 95% confidence level {gamma}-ray upper limit for the integrated photon flux above 100 MeV from the analyzed Seyferts is {approx_equal} 4 Multiplication-Sign 10{sup -9} photons cm{sup -2} s{sup -1} , and the upper limits derived for several objects reach {approx_equal} 1 Multiplication-Sign 10{sup -9} photons cm{sup -2} s{sup -1} . Our results indicate that no prominent {gamma}-ray emission component related to active galactic nucleus activity is present in the spectra of Seyferts around GeV energies. The Fermi-LAT upper limits derived for our sample probe the ratio of {gamma}-ray to X-ray luminosities L{sub {gamma}}/L{sub X} < 0.1, and even <0.01 in some cases. The obtained results impose novel constraints on the models for high-energy radiation of 'radio-quiet' Seyfert galaxies.« less

BurstCube: A CubeSat for Gravitational Wave Counterparts

NASA Astrophysics Data System (ADS)

Perkins, Jeremy S.; Racusin, Judith; Briggs, Michael; de Nolfo, Georgia; Caputo, Regina; Krizmanic, John; McEnery, Julie E.; Shawhan, Peter; Morris, David; Connaughton, Valerie; Kocevski, Dan; Wilson-Hodge, Colleen A.; Hui, Michelle; Mitchell, Lee; McBreen, Sheila

2018-01-01

We present BurstCube, a novel CubeSat that will detect and localize Gamma-ray Bursts (GRBs). BurstCube is a selected mission that will detect long GRBs, attributed to the collapse of massive stars, short GRBs (sGRBs), resulting from binary neutron star mergers, as well as other gamma-ray transients in the energy range 10-1000 keV. sGRBs are of particular interest because they are predicted to be the counterparts of gravitational wave (GW) sources soon to be detectable by LIGO/Virgo. BurstCube contains 4 CsI scintillators coupled with arrays of compact low-power Silicon photomultipliers (SiPMs) on a 6U Dellingr bus, a flagship modular platform that is easily modifiable for a variety of 6U CubeSat architectures. BurstCube will complement existing facilities such as Swift and Fermi in the short term, and provide a means for GRB detection, localization, and characterization in the interim time before the next generation future gamma-ray mission flies, as well as space-qualify SiPMs and test technologies for future use on larger gamma-ray missions. The ultimate configuration of BurstCube is to have a set of ~10 BurstCubes to provide all-sky coverage to GRBs for substantially lower cost than a full-scale mission.

Radio Flares from Gamma-ray Bursts

NASA Astrophysics Data System (ADS)

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

2015-06-01

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

Soft gamma-ray detector (SGD) onboard the ASTRO-H mission

NASA Astrophysics Data System (ADS)

Fukazawa, Yasushi; Tajima, Hiroyasu; Watanabe, Shin; Blandford, Roger; Hayashi, Katsuhiro; Harayama, Atsushi; Kataoka, Jun; Kawaharada, Madoka; Kokubun, Motohide; Laurent, Philippe; Lebrun, François; Limousin, Olivier; Madejski, Grzegorz M.; Makishima, Kazuo; Mizuno, Tsunefumi; Mori, Kunishiro; Nakamori, Takeshi; Nakazawa, Kazuhiro; Noda, Hirofumi; Odaka, Hirokazu; Ohno, Masanori; Ohta, Masayuki; Saito, Shin'ya; Sato, Goro; Sato, Rie; Takeda, Shin'ichiro; Takahashi, Hiromitsu; Takahashi, Tadayuki; Tanaka, Yasuyuki; Terada, Yukikatsu; Uchiyama, Hideki; Uchiyama, Yasunobu; Yamaoka, Kazutaka; Yatsu, Yoichi; Yonetoku, Daisuke; Yuasa, Takayuki

2014-07-01

The Soft Gamma-ray Detector (SGD) is one of observational instruments onboard the ASTRO-H, and will provide 10 times better sensitivity in 60{600 keV than the past and current observatories. The SGD utilizes similar technologies to the Hard X-ray Imager (HXI) onboard the ASTRO-H. The SGD achieves low background by constraining gamma-ray events within a narrow field-of-view by Compton kinematics, in addition to the BGO active shield. In this paper, we will present the results of various tests using engineering models and also report the flight model production and evaluations.

Research in cosmic and gamma ray astrophysics

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

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

PubMed

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

2004-09-01

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

Gamma-Ray Astrophysics: New Insight Into the Universe

NASA Technical Reports Server (NTRS)

Fichtel, Carl E.; Trombka, Jacob I.

1997-01-01

During the 15 years that have passed since the first edition of this book was published, there has been a major increase in our knowledge of gamma-ray astronomy. Much of this advance arises from the extensive results that have been forthcoming from the Compton Gamma-Ray Observatory. There has been the discovery of a new class of gamma-ray objects, namely high-energy gamma- ray-emitting blazars, a special class of Active Galactic Nuclei, whose basic high-energy properties now seem to be understood. A much improved picture of our galaxy now exists in the frequency range of gamma rays. The question of whether cosmic rays are galactic or metagalactic now seems settled with certainty. Significant new information exists on the gamma-ray properties of neutron star pulsars, Seyfert galaxies, and gamma-ray bursts. Substantial new insight has been obtained on solar phenomena through gamma-ray observations. Hence, this seemed to be an appropriate time to write a new edition of this book to add the important scientific implications of these many new findings. The special importance of gamma-ray astrophysics had long been recognized by many physicists and astronomers, and theorists had pursued many aspects of the subject well before the experimental results began to become available. The slower development of the experimental side was not because of a lack of incentive, but due to the substantial experimental difficulties that had to be overcome. Thus, as the gamma-ray results became available in much greater number and detail, it was possible to build upon the theoretical work that already existed and to make substantial progress in the study of many of the phenomena involved. Consequently, a much better understanding of many of the astrophysical phenomena mentioned here and others is now possible. Our principal aims in writing this book are the same as they were for the first edition: to provide a text which describes the significance of gamma-ray astrophysics and to assemble in one place a treatment of gamma rays emitted from bodies in the solar i system, from objects in our galaxy, as well as from interactions between cosmic rays and the interstellar medium, and from beyond our galaxy. Thus, this book is intended for those in astrophysics who wish to have the opportunity to learn more about the evolving field of gamma-ray astronomy and its relationship to the high-energy, evolutionary processes occurring in the universe. The last three chapters of the book provide a general discussion of the experimental aspects of the field that seemed best treated together, separately from the astrophysical aspects of gamma-ray astronomy that are discussed in the first ten chapters.

WESF (173)Cs gamma ray sources

NASA Astrophysics Data System (ADS)

Kenna, B. T.

1984-10-01

The Waste Encapsulation and Storage Facility (WESP) at Hanford, Washington has been separating cesium from stored liquid defense waste since 1945. This is done to alleviate the heat generated by the decay of radioactive Cs137. The cesium is converted to CsCl, doubly encapsulated in 316l stainless steel, and placed in storage. The potential utility of these Cs137 capsules as gamma radiation sources was demonstrated. Registration of the capsule with the NRC as a sealed gamma source would facilitate the licensing of non-DOE irradiation facilities using this source. To grant this registration, the NRC requires characteristics of the capsule. It must also be demonstrated that the capsule will maintain its integrity under both normal circumstances and specified abnormal conditions. The required information is provided through collation of results of studies and tests done previously by other laboratories.

The Cosmic-Ray and Gas Content of the Cygnus Region as Measured in Gamma Rays by the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Belfiore, A.; Bellazzini, R.; Berenji, B.;

Interpretation of various radiation backgrounds observed in the gamma-ray spectrometer experiments carried on the Apollo missions and implications for diffuse gamma-ray measurements

NASA Technical Reports Server (NTRS)

Dyer, C. S.; Trombka, J. I.; Metzger, A. E.; Seltzer, S. M.; Bielefeld, M. J.; Evans, L. G.

1975-01-01

Since the report of a preliminary analysis of cosmic gamma-ray measurements made during the Apollo 15 mission, an improved calculation of the spallation activation contribution has been made including the effects of short-lived spallation fragments, which can extend the correction to 15 MeV. In addition, a difference between Apollo 15 and 16 data enables an electron bremsstrahlung contribution to be calculated. A high level of activation observed in a crystal returned on Apollo 17 indicates a background contribution from secondary neutrons. These calculations and observations enable an improved extraction of spurious components and suggest important improvements for future detectors.

Relativistic particles and gamma-ray in quasars and active galactic nuclei

NASA Technical Reports Server (NTRS)

Protheroe, R. J.; Kazanas, D.

1982-01-01

A model for a class of quasars and active galactic nuclei is described in which a shock around a massive black hole randomizes the infall kinetic energy of spherically accreting matter producing a nonthermal spectrum of high energy protons. These protons may be responsible for the secondary production (via tau + or - decay) of the radio emitting high energy electrons and also of high energy gamma rays (via pi decay and inverse Compton interactions of the electrons). The correlation between radio and gamma ray emission implied by the model is in good agreement with observations of 3C273. Observation of the flux of high energy neutrinos from quasars may provide a test for the model.

Relativistic particles and gamma-rays in quasars and active galactic nuclei

NASA Technical Reports Server (NTRS)

Protheroe, R. J.; Kazanas, D.

1983-01-01

A model for a class of quasars and active galactic nuclei is described in which a shock around a massive black hole randomizes the infall kinetic energy of spherically accreting matter producing a nonthermal spectrum of high energy protons. These protons may be responsible for the secondary production (via tau + or - decay) of the radio emitting high energy electrons and also of high energy gamma rays (via Pi decay and inverse Compton interactions of the electrons). The correlation between radio and gamma ray emission implied by the model is in good agreement with observations of 3C273. Observation of the flux of high energy neutrinos from quasars may provide a test for the model.

Induction of skin papillomas in the rabbit, Oryctologus cuniculus, by bites of a blood-sucking insect, Cimex lectularius, irradiated by gamma rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

el-Mofty, M.M.; Sakr, S.A.; Younis, M.W.

Bed bugs, Cimex lectularius, irradiated with gamma rays were allowed to suck blood from shaved areas of the skin of rabbits, Oryctolagus cuniculus, 2 times/week for 5 months and then once weekly for another 5 months. This significantly induced the formation of skin papillomas and sweat gland hyperplasia in five out of nine experimental animals. It is speculated that the saliva of the irradiated bugs was activated by gamma rays and was responsible for the induction of skin papillomas. Because bed bugs play a significant role in the transmission of virus, it is also speculated that there is a virusmore » in the saliva of bugs; this virus may be activated by gamma radiation and causes the development of papillomas in the skin.« less

Research in particles and fields. [cosmic rays, gamma rays, and cosmic plasma

NASA Technical Reports Server (NTRS)

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

1984-01-01

Research activities in cosmic rays, gamma rays, and astrophysical plasmas are reviewed. Energetic particle and photon detector systems flown on spacecraft and balloons were used to carry out the investigations. Specific instruments mentioned are: the high energy isotope spectrometer telescope, the electron/isotope spectrometer, the heavy isotope spectrometer telescope, and magnetometers. Solar flares, planetary magnetospheres, element abundance, the isotopic composition of low energy cosmic rays, and heavy nuclei are among the topics receiving research attention.

Electron Acceleration and Efficiency in Nonthermal Gamma-Ray Sources

NASA Astrophysics Data System (ADS)

Bykov, A. M.; Meszaros, P.

1996-04-01

In energetic nonthermal sources such as gamma-ray bursts, active galactic nuclei, or galactic jets, etc., one expects both relativistic and transrelativistic shocks accompanied by violent motions of moderately relativistic plasma. We present general considerations indicating that these sites are electron and positron accelerators leading to a modified power-law spectrum. The electron (or e+/-) energy index is very hard, ~ gamma -1 or flatter, up to a comoving frame break energy gamma *, and becomes steeper above that. In the example of gamma-ray bursts, the Lorentz factor reaches gamma * ~ 103 for e+/- accelerated by the internal shock ensemble on subhydrodynamical timescales. For pairs accelerated on hydrodynamical timescales in the external shocks, similar hard spectra are obtained, and the break Lorentz factor can be as high as gamma * <~ 105. Radiation from the nonthermal electrons produces photon spectra with shapes and characteristic energies in qualitative agreement with observed generic gamma-ray burst and blazar spectra. The scenario described here provides a plausible way to solve one of the crucial problems of nonthermal high-energy sources, namely, the efficient transfer of energy from the proton flow to an appropriate nonthermal lepton component.

Radiation-assisted grafting of vinylidene chloride onto high-density polyethylene

NASA Astrophysics Data System (ADS)

Nagesh, N.; Dokhale, P. A.; Bhoraskar, V. N.

1999-06-01

6 MeV electrons and Co-60 icons/Journals/Common/gamma" ALT="gamma" ALIGN="TOP"/>-rays were used for grafting vinylidene chloride (VDC) onto high-density polyethylene (HDPE) samples. The HDPE samples were immersed in vinylidene chloride and irradiated either with Co-60 icons/Journals/Common/gamma" ALT="gamma" ALIGN="TOP"/>-rays or with 6 MeV electrons. In both cases, the radiation dose was varied in the range 1.25-7.5 kGy. The grafted samples were characterized by IR spectroscopy to obtain information about the chemical bonds and with the 14 MeV neutron activation analysis technique for estimating the number of chlorine atoms. The formation of stable bonds between the VDC molecules and the polymer chains could be achieved either with 6 MeV electrons or with Co-60 icons/Journals/Common/gamma" ALT="gamma" ALIGN="TOP"/>-rays. Both the number of chlorine atoms and the sample-surface conductivity increased with the radiation dose but the increases achieved with 6 MeV electrons were greater than those achieved with Co-60 icons/Journals/Common/gamma" ALT="gamma" ALIGN="TOP"/>-rays.

Waste inspection tomography (WIT)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernardi, R.T.

1996-12-31

WIT is a self-sufficient mobile semitrailer for nondestructive evaluation and nondestructive assay of nuclear waste drums using x-ray and gamma-ray tomography. The recently completed Phase I included the design, fabrication, and initial testing of all WIT subsystems installed on-board the trailer. Initial test results include 2 MeV digital radiography, computed tomography, Anger camera imaging, single photon emission computed tomography, gamma-ray spectroscopy, collimated gamma scanning, and active and passive computed tomography using a 1.4 mCi source of {sup 166}Ho. These techniques were initially demonstrated on a 55-gallon phantom drum with 3 simulated waste matrices of combustibles, heterogeneous metals, and cement usingmore » check sources of gamma active isotopes such as {sup 137}Cs and {sup 133}Ba with 9-250 {mu}Ci activities. Waste matrix identification, isotopic identification, and attenuation-corrected gamma activity determination were demonstrated nondestructively and noninvasively in Phase I. Currently ongoing Phase II involves DOE site field test demonstrations at LLNL, RFETS, and INEL with real nuclear waste drums. Current WIT experience includes 55 gallon drums of cement, graphite, sludge, glass, metals, and combustibles. Thus far WIT has inspected drums with 0-20 gms of {sup 239}Pu.« less

Future prospects of nuclear reactions induced by gamma-ray beams at ELI-NP

NASA Astrophysics Data System (ADS)

Filipescu, D.; Balabanski, D. L.; Camera, F.; Gheorghe, I.; Ghita, D.; Glodariu, T.; Kaur, J.; Ur, C. A.; Utsunomiya, H.; Varlamov, V. V.

2017-01-01

The future prospects of photonuclear reactions studies at the new Extreme Light Infrastructure—Nuclear Physics (ELI-NP) facility are discussed in view of the pursuit of investigating the electromagnetic response of nuclei using γ-ray beams of unprecedented energy resolution and intensity characteristics. We present here the features of the γ-ray beam source, the emerging ELI-NP experimental program involving photonuclear reactions cross section measurements and spectroscopy and angular measurements of γ-rays and neutrons along with the detection arrays currently under implementation.

Performance tests of a large volume cerium tribromide (CeBr3) scintillation detector.

PubMed

Naqvi, A A; Khiari, F Z; Liadi, F A; Khateeb-Ur-Rehman; Isab, A A

2016-08-01

The response of a large cylindrical 76mm×76mm (height×diameter) cerium tribromide (CeBr3) detector was measured for prompt gamma rays. The total intrinsic activity of the CeBr3 detector, which was measured over 0.33-3.33MeV range, was found to be 0.022±0.001 counts/s/cm(3). The partial intrinsic activity ( due to (227)Ac contamination), was measured over a energy range of 1.22-2.20MeV energy, was found to be 0.007±0.001 counts/s/cm(3). Compared to intrinsic activities of LaBr3:Ce and LaCl3:Ce detectors of equivalent volume, the CeBr3 detector has 7-8 times less total intrinsic activity. The detector response for low energy prompt gamma rays was measured over 0.3-0.6MeVgamma energy range using a portable neutron generator-based Prompt Gamma Neutron Activation Analysis (PGNAA) setup. The experimental yield of boron, cadmium and mercury prompt gamma-rays was measured from water samples contaminated with 0.75-2.5wt% mercury, 0.31-2.50wt% boron, and 0.0625-0.500wt% cadmium, respectively. An excellent agreement has been observed between the calculated and experimental yields of the gamma rays. Also minimum detection limit (MDC) of the CeBr3 detector was measured for boron, cadmium and mercury samples. The CeBr3 detector has 23% smaller value of MDCB and 18% larger value of MDCCd than those of a LaBr3:Ce detector of equivalent size. This study has shown that CeBr3 detector has an excellent response for the low energy prompt gamma-rays with almost an order of magnitude low intrinsic activity as compared to LaCl3:Ce and LaBr3:Ce detectors of equivalent volume. Copyright © 2016 Elsevier Ltd. All rights reserved.

Astronomy and astrophysics for the 1980's. Volume 1 - Report of the Astronomy Survey Committee. Volume 2 - Reports of the Panels

NASA Astrophysics Data System (ADS)

Recommended priorities for astronomy and astrophysics in the 1980s are considered along with the frontiers of astrophysics, taking into account large-scale structure in the universe, the evolution of galaxies, violent events, the formation of stars and planets, solar and stellar activity, astronomy and the forces of nature, and planets, life, and intelligence. Approved, continuing, and previously recommended programs are related to the Space Telescope and the associated Space Telescope Science Institute, second-generation instrumentation for the Space Telescope, and Gamma Ray Observatory, facilities for the detection of solar neutrinos, and the Shuttle Infrared Telescope Facility. Attention is given to the prerequisites for new research initiatives, new programs, programs for study and development, high-energy astrophysics, radio astronomy, theoretical and laboratory astrophysics, data processing and computational facilities, organization and education, and ultraviolet, optical, and infrared astronomy.

Fermi Gamma-Ray Space Telescope - Science Highlights for the First Two Years on Orbit

NASA Technical Reports Server (NTRS)

Moiseev, Alexander

2011-01-01

Fermi science objectives cover probably everything in high energy astrophysics: How do super massive black holes in Active Galactic Nuclei create powerful jets of material moving at nearly light speed? What are the jets made of? What are the mechanisms that produce Gamma-Ray Burst (GRB) explosions? What is the energy budget? How does the Sun generate high-energy gamma-rays in flares? How do the pulsars operate? How many of them are around and how different are they? What are the unidentified gamma-ray sources found by EGRET? What is the origin of the cosmic rays that pervade the Galaxy? What is the nature of dark matter? Fermi LAT successfully operates on the orbit for more than 2 years and demonstrates excellent performance, which is continuously monitored and calibrated. LAT collected> 100 billion on-orbit triggers

Book Review

PubMed Central

Smathers, James. B.

2006-01-01

Structural Shielding Design and Evaluation for Megavoltage X‐ and Gamma Ray Radiotherapy Facilities; National Council on Radiation Protection and Measurements (NCRP Report 151); Issued December 2005, ISBN‐13: 987‐0‐29600‐87‐1; Price $100 USD (hard copy), $80 (down loadable PDF), $170 (combined package)

Cherenkov radiation conversion and collection considerations for a gamma bang time/reaction history diagnostic for the NIF.

PubMed

Herrmann, Hans W; Mack, Joseph M; Young, Carlton S; Malone, Robert M; Stoeffl, Wolfgang; Horsfield, Colin J

2008-10-01

Bang time and reaction history measurements are fundamental components of diagnosing inertial confinement fusion (ICF) implosions and will be essential contributors to diagnosing attempts at ignition on the National Ignition Facility (NIF). Fusion gammas provide a direct measure of fusion interaction rate without being compromised by Doppler spreading. Gamma-based gas Cherenkov detectors that convert fusion gamma rays to optical Cherenkov photons for collection by fast recording systems have been developed and fielded at Omega. These systems have established their usefulness in illuminating ICF physics in several experimental campaigns. Bang time precision better than 25 ps has been demonstrated, well below the 50 ps accuracy requirement defined by the NIF system design requirements. A comprehensive, validated numerical study of candidate systems is providing essential information needed to make a down selection based on optimization of sensitivity, bandwidth, dynamic range, cost, and NIF logistics. This paper presents basic design considerations arising from the two-step conversion process from gamma rays to relativistic electrons to UV/visible Cherenkov radiation.

Mechanism of Hydrophilicity by Radiation-Induced Surface Activation

NASA Astrophysics Data System (ADS)

Honjo, Yoshio; Furuya, Masahiro; Takamasa, Tomoji; Okamoto, Koji

When a metal oxide is irradiated by gamma rays, the irradiated surface becomes hydrophilic. This surface phenomenon is called as radiation-induced surface activation (RISA) hydrophilicity. In order to investigate gamma ray-induced and photoinduced hydrophilicity, the contact angles of water droplets on a titanium dioxide surface were measured in terms of irradiation intensity and time for gamma rays of cobalt-60 and for ultraviolet rays. Reciprocals of the contact angles increased in proportion to the irradiation time before the contact angles reached its super-hydrophilic state. The irradiation time dependency is equal to each other qualitatively. In addition, an effect of ambient gas was investigated. In pure argon gas, the contact angle remains the same against the irradiation time. This clearly indicates that certain humidity is required in ambient gas to take place of RISA hydrophilicity. A single crystal titanium dioxide (100) surface was analyzed by X-ray photoelectron spectrometry (XPS). After irradiation with gamma rays, a peak was found in the O1s spectrum, which indicates the adsorption of dissociative water to a surface 5-fold coordinate titanium site, and the formation of a surface hydroxyl group. We conclude that the RISA hydrophilicity is caused by chemisorption of the hydroxyl group on the surface.

Structure of {sup 81}Ga populated from the {beta}{sup -} decay of {sup 81}Zn

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paziy, V.; Mach, H.; Fraile, L. M.

2013-06-10

We report on the results of the {beta}-decay of {sup 81}Zn. The experiment was performed at the CERN ISOLDE facility in the framework of a systematic ultra-fast timing investigation of neutron-rich nuclei populated in the decay of Zn. The present analysis included {beta}-gated {gamma}-ray singles and {gamma}-{gamma} coincidences from the decay of {sup 81}Zn to {sup 81}Ga and leads to a new and much more extensive level scheme of {sup 81}Ga. A new half-life of {sup 81}Zn is provided.

SMM hard X-ray observations of the soft gamma-ray repeater 1806-20

NASA Technical Reports Server (NTRS)

Kouveliotou, C.; Norris, J. P.; Cline, T. L.; Dennis, B. R.; Desai, U. D.; Orwig, L. E.

1987-01-01

Six bursts from the soft gamma-ray repeater (SGR) 1806-20 have been recorded with the SMM Hard X-ray Burst Spectrometer during a highly active phase in 1983. Rise and decay times of less than 5 ns have been detected. Time profiles of these events indicate low-level emission prior to and after the main peaks. The results suggest that SGRs are distinguished from classical gamma-ray bursts by repetition, softer nonvarying spectra, short durations, simple temporal profiles, and a tendency for source locations to correlate with Population I objects. SGR characteristics differ from those of type I X-ray bursts, but they appear to have similarities with the type II bursts from the Rapid Burster.

Gamma Ray Observatory (GRO) Prelaunch Mission Operations Report (MOR)

NASA Technical Reports Server (NTRS)

1991-01-01

The NASA Astrophysics Program is an endeavor to understand the origin and fate of the universe, to understand the birth and evolution of the large variety of objects in the universe, from the most benign to the most violent, and to probe the fundamental laws of physics by examining their behavior under extreme physical conditions. These goals are pursued by means of observations across the entire electromagnetic spectrum, and through theoretical interpretation of radiations and fields associated with astrophysical systems. Astrophysics orbital flight programs are structured under one of two operational objectives: (1) the establishment of long duration Great Observatories for viewing the universe in four major wavelength regions of the electromagnetic spectrum (radio/infrared/submillimeter, visible/ultraviolet, X-ray, and gamma ray), and (2) obtaining crucial bridging and supporting measurements via missions with directed objectives of intermediate or small scope conducted within the Explorer and Spacelab programs. Under (1) in this context, the Gamma Ray Observatory (GRO) is one of NASA's four Great Observatories. The other three are the Hubble Space Telescope (HST) for the visible and ultraviolet portion of the spectrum, the Advanced X-ray Astrophysics Facility (AXAF) for the X-ray band, and the Space Infrared Telescope Facility (SIRTF) for infrared wavelengths. GRO's specific mission is to study the sources and astrophysical processes that produce the highest energy electromagnetic radiation from the cosmos. The fundamental physical processes that are known to produce gamma radiation in the universe include nuclear reactions, electron bremsstrahlung, matter-antimatter annihilation, elementary particle production and decay, Compton scattering, synchrotron radiation. GRO will address a variety of questions relevant to understanding the universe, such as: the formation of the elements; the structure and dynamics of the Galaxy; the nature of pulsars; the existence of black holes; the possible existence of large amounts of antimatter, energetic and explosive phenomena occurring in galactic nuclei; the origin of the cosmic diffuse background; particle acceleration in the Sun, stars and stellar systems; processes in supernovae; and the origin and evolution of the universe itself.

Test results of a new detector system for gamma ray isotopic measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malcom, J.E.; Bonner, C.A.; Hurd, J.R.

1993-08-01

A new type of gamma-ray detector system for isotopic measurements has been developed. This new system, a ``Duo detector`` array, consists of two intrinsic germanium detectors, a planar followed by a coaxial mounted on the same axis within a single cryostat assembly. This configuration allows the isotopic analysis system to take advantage of spectral data results that are collected simultaneously from different gamma-ray energy regimes. Princeton Gamma Tech (PGT) produced several prototypes of this Duo detector array which were then tested by Rocky Flats personnel until the design was optimized. An application for this detector design is in automated, roboticizedmore » NDA systems such as those being developed at the Los Alamos TA-55 Plutonium Facility. The Duo detector design reduces the space necessary for the isotopic instrument by a factor of two (only one liquid nitrogen dewar is needed), and also reduces the complexity of the mechanical systems and controlling software. Data will be presented on measurements of nuclear material with a Duo detector for a wide variety of matrices. Results indicate that the maximum count rate can be increased up to 100,000 counts per second yet maintaining excellent resolution and energy rate product.« less

MOXE: An X-ray all-sky monitor for Soviet Spectrum-X-Gamma Mission

NASA Technical Reports Server (NTRS)

Priedhorsky, W.; Fenimore, E. E.; Moss, C. E.; Kelley, R. L.; Holt, S. S.

1989-01-01

A Monitoring Monitoring X-Ray Equipment (MOXE) is being developed for the Soviet Spectrum-X-Gamma Mission. MOXE is an X-ray all-sky monitor based on array of pinhole cameras, to be provided via a collaboration between Goddard Space Flight Center and Los Alamos National Laboratory. The objectives are to alert other observers on Spectrum-X-Gamma and other platforms of interesting transient activity, and to synoptically monitor the X-ray sky and study long-term changes in X-ray binaries. MOXE will be sensitive to sources as faint as 2 milliCrab (5 sigma) in 1 day, and cover the 2 to 20 KeV band.

Shape Coexistence in Odd-Mass Nuclei Near Z = 82 Closed Shell; a Study of the Excited States of Gold -185 in the BETA(+)/EC Decay of MERCURY-185.

NASA Astrophysics Data System (ADS)

Papanicolopoulos, Chrysanthos Dionisios

1987-11-01

The excited states of ^{185 }{rm Au} have been studied by the radioactive decay of {^ {185m,g}Hg.} Sources of {^{185m,g}Hg} were produced by the reaction ^{176 }Hf (^{16}O, 7n) ^{185}Hg using 140 MeV ^{16}O beams from the 25 MV folded tandem of the Holifield Heavy Ion Research Facility. Sources of ^{185}Hg were mass-separated on-line using the University Isotope Separator Oak Ridge (UNISOR) facility. Multiscaled spectra of rays, x rays and conversion electrons were obtained together with gamma- gamma - t, gamma- x - t, e ^{-} - gamma - t, and e^{-}- x - t coincidence data. A decay scheme consisting of 82 excited states and 182 transitions was constructed. Bands of states associated with the s_{1over 2}, d_{3over 2} , d_{5over 2}, h_{11over 2} proton -hole configurations and the h_{9over 2} and i_{13over 2} proton-particle (intruder) configurations were constructed. In addition, a number of EO transitions were located: these de-excite levels which are interpreted as resulting from shape coexistence in the ^ {184}Pt and ^{186 }Hg "particle" and "hole" cores. The h _{9over 2} band is compared with calculations made with the Lund model of Larsson et al.

Recent results from the Compton Observatory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michelson, P.F.; Hansen, W.W.

1994-12-01

The Compton Observatory is an orbiting astronomical observatory for gamma-ray astronomy that covers the energy range from about 30 keV to 30 GeV. The Energetic Gamma Ray Experiment Telescope (EGRET), one of four instruments on-board, is capable of detecting and imaging gamma radiation from cosmic sources in the energy range from approximately 20 MeV to 30 GeV. After about one month of tests and calibration following the April 1991 launch, a 15-month all sky survey was begun. This survey is now complete and the Compton Observatory is well into Phase II of its observing program which includes guest investigator observations.more » Among the highlights from the all-sky survey discussed in this presentation are the following: detection of five pulsars with emission above 100 MeV; detection of more than 24 active galaxies, the most distant at redshift greater than two; detection of many high latitude, unidentified gamma-ray sources, some showing significant time variability; detection of at least two high energy gamma-ray bursts, with emission in one case extending to at least 1 GeV. EGRET has also detected gamma-ray emission from solar flares up to energies of at least 2 GeV and has observed gamma-rays from the Large Magellanic Cloud.« less

Molecular and biochemical studies on the effect of gamma rays on lead toxicity in cowpea (Vigna sinensis) plants.

PubMed

Mohamed, Heba Ibrahim

2011-12-01

The effect of lead acetate in the presence or absence of cowpea seeds irradiated with gamma rays on morphological criteria, protein electrophoresis, isozymes, and random amplification of polymorphic DNA-polymerase chain reaction (RAPD-PCR) of leaves was investigated. A highly significant decrease in shoot and root length was observed upon lead acetate exposure (300 and 600 μM). On the other hand, in seeds irradiated with gamma rays (2, 5, and 8 krad), these morphological parameters were increased after lead acetate treatments. Meanwhile, all treatments (lead acetate and gamma rays) caused variations in number, intensity, and/or density of SDS electrophoretic bands of proteins. In addition, electrophoretic studies of esterase, acid phosphatase, peroxidase, polyphenol oxidase, catalase, and superoxide dismutase isozyme activities were increased with increasing the concentrations of lead acetate and gamma ray doses. The variation in DNA profile in response to lead acetate and gamma irradiation treatments was detected by RAPD-PCR technique. The result of RAPD analysis using the five primers indicated the appearance and disappearance of DNA polymorphic bands at all treatments (gamma rays and lead stress). The relatively high concentrations of lead acetate (600 μM) induced more changes in genomic DNA pattern.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Itoh, Ryosuke; Fukazawa, Yasushi; Kanda, Yuka

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

Problems encountered in the use of neutron methods for elemental analysis on planetary surfaces

USGS Publications Warehouse

Senftle, F.; Philbin, P.; Moxham, R.; Boynton, G.; Trombka, J.

1974-01-01

From experimental studies of gamma rays from fast and thermal neutron reactions in hydrogeneous and non-hydrogeneous, semi-infinite samples and from Monte Carlo calculations on soil of a composition which might typically be encountered on planetary surfaces, it is found that gamma rays from fast or inelastic scattering reactions would dominate the observed spectra. With the exception of gamma rays formed by inelastically scattered neutrons on oxygen, useful spectra would be limited to energies below 3 MeV. Other experiments were performed which show that if a gamma-ray detector were placed within 6 m of an isotopic neutron source in a spacecraft, it would be rendered useless for gamma-ray spectrometry below 3 MeV because of internal activation produced by neutron exposure during space travel. Adequate shielding is not practicable because of the size and weight constraints for planetary missions. Thus, it is required that the source be turned off or removed to a safe distance during non-measurement periods. In view of these results an accelerator or an off-on isotopic source would be desirable for practical gamma-ray spectral analysis on planetary surfaces containing but minor amounts of hydrogen. ?? 1974.

Distribution of residual long-lived radioactivity in the inner concrete walls of a compact medical cyclotron vault room.

PubMed

Fujibuchi, Toshioh; Nohtomi, Akihiro; Baba, Shingo; Sasaki, Masayuki; Komiya, Isao; Umedzu, Yoshiyuki; Honda, Hiroshi

2015-01-01

Compact medical cyclotrons have been set up to generate the nuclides necessary for positron emission tomography. In accelerator facilities, neutrons activate the concrete used to construct the vault room; this activation increases with the use of an accelerator. The activation causes a substantial radioactive waste management problem when facilities are decommissioned. In the present study, several concrete cores from the walls, ceiling and floor of a compact medical cyclotron vault room were samples 2 years after the termination of operations, and the radioactivity concentrations of radionuclides were estimated. Cylindrical concrete cores 5 cm in diameter and 10 cm in length were bored from the concrete wall, ceiling and floor. Core boring was performed at 18 points. The gamma-ray spectrum of each sample was measured using a high-purity germanium detector. The degree of activation of the concrete in the cyclotron vault room was analyzed, and the range and tendency toward activation in the vault room were examined. (60)Co and (152)Eu were identified by gamma-ray spectrometry of the concrete samples. (152)Eu and (60)Co are produced principally from the stable isotopes of europium and cobalt by neutron capture reactions. The radioactivity concentration did not vary much between the surface of the concrete and at a depth of 10 cm. Although the radioactivity concentration near the target was higher than the clearance level for radioactive waste indicated in IAEA RS-G-1.7, the mean radioactivity concentration in the walls and floor was lower than the clearance level. The radioactivity concentration of the inner concrete wall of the medical cyclotron vault room was not uniform. The areas exceeding the clearance level were in the vicinity of the target, but most of the building did not exceed the clearance levels.

Discovery of a Nonblazar Gamma-Ray Transient Source Near the Galactic Plane: GRO J1838-04

NASA Technical Reports Server (NTRS)

Tavani, M.; Oliversen, Ronald (Technical Monitor)

2001-01-01

We report the discovery of a remarkable gamma-ray transient source near the Galactic plane, GRO J1838-04. This source was serendipitously discovered by EGRET in 1995 June with a peak intensity of approx. (4 +/- 1) x 10(exp -6) photons/sq cm s (for photon energies larger than 100 MeV) and a 5.9 sigma significance. At that time, GRO J1838-04 was the second brightest gamma-ray source in the sky. A subsequent EGRET pointing in 1995 late September detected the source at a flux smaller than its peak value by a factor of approx. 7. We determine that no radio-loud spectrally flat blazar is within the error box of GRO J1838-04. We discuss the origin of the gamma-ray transient source and show that interpretations in terms of active galactic nuclei or isolated pulsars are highly problematic. GRO J1838-04 provides strong evidence for the existence of a new class of variable gamma-ray sources.

Fermi LAT detection of renewed gamma-ray activity from the FSRQ PKS 2326-502

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Torresi, E.

2012-06-01

The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope has observed an increasing gamma-ray flux from a source positionally consistent with the Flat Spectrum Radio Quasar PKS 2326-502 (also known as 2FGL J2329.2-4956, Nolan et al. 2012, ApJS, 199, 31; R.A.=23:29:20.880 Dec.=-49:55:40.68, J2000.0, Costa and Loyola 1996, A&AS, 115, 75) at redshift z=0.518 (Jauncey et al. 1984, ApJ, 286, 498).

Long duration gamma-ray emission from thunderclouds

NASA Astrophysics Data System (ADS)

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 related to the distance. The glow measured on August 21, 2009 was 20 times brighter than any other glow. This glow was modeled most extensively and it was found that ADELE was in the end of a downward facing avalanche, implying that is was lying between the upper positive and negative screening layer of the thunderstorm. The brightness of this glow also showed that the avalanche was approaching the levels necessary for relativistic feedback. I also show that this glow provides a significant discharge current and for a short while is discharging the cloud as much as nearby lightning.

Analysis of the propagation of neutrons and gamma-rays from the fast neutron source reactor YAYOI

NASA Astrophysics Data System (ADS)

Yoshida, Shigeo; Murata, Isao; Nakagawa, Tsutomu; Saito, Isao

2011-10-01

The skyshine effect is crucial for designing appropriate shielding. To investigate the skyshine effect, the propagation of neutrons was measured and analyzed at the fast neutron source reactor YAYOI. Pulse height spectra and dose distributions of neutron and secondary gamma-ray were measured outside YAYOI, and analyzed with MCNP-5 and JENDL-3.3. Comparison with the experimental results showed good agreement. Also, a semi-empirical formula was successfully derived to describe the dose distribution. The formulae can be used to predict the skyshine effect at YAYOI, and will be useful for estimating the skyshine effect and designing the shield structure for fusion facilities.

KSC-08pd0996

NASA Image and Video Library

2008-04-23

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., workers prepare NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft for star tracker sun shade installation. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Cory Huston

KSC-08pd1032

NASA Image and Video Library

2008-04-25

CAPE CANAVERAL, Fla. – At the Astrotech payload processing facility, technicians install insulation blankets around the star tracker sunshades on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1006

NASA Image and Video Library

2008-04-23

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., a worker adjusts the star tracker sun shade installed on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Kim Shiflett

KSC-08pd1005

NASA Image and Video Library

2008-04-23

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., workers install another of the star tracker sun shades on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Kim Shiflett

KSC-08pd1031

NASA Image and Video Library

2008-04-25

CAPE CANAVERAL, Fla. – At the Astrotech payload processing facility, technicians install insulation blankets around the star tracker sunshades on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1001

NASA Image and Video Library

2008-04-23

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., workers install one of the star tracker sun shades on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Kim Shiflett

KSC-08pd1003

NASA Image and Video Library

2008-04-23

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., a worker adjusts the star tracker sun shades installed on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Kim Shiflett

KSC-08pd0997

NASA Image and Video Library

2008-04-23

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., a worker cleans around the area where star tracker sun shades will be installed on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Kim Shiflett

KSC-08pd0998

NASA Image and Video Library

2008-04-23

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., the star tracker sun shades are waiting to be installed on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Kim Shiflett

KSC-08pd0994

NASA Image and Video Library

2008-04-23

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., workers prepare NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft for star tracker sun shade installation. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Cory Huston

KSC-08pd1033

NASA Image and Video Library

2008-04-25

CAPE CANAVERAL, Fla. – At the Astrotech payload processing facility, technicians install insulation blankets around the star tracker sunshades on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1000

NASA Image and Video Library

2008-04-23

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility in Titusville, Fla., workers install one of the star tracker sun shades on NASA's Gamma-ray Large Area Space Telescope, or GLAST, spacecraft. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date is still to be determined. Photo credit: NASA/Kim Shiflett

In vivo adenylate cyclase activity in ultraviolet- and gamma-irradiated Escherichia coli.

PubMed

Chatterjee, A; Bhattacharya, A K

1988-06-01

The incorporation of [14C]adenine into the cyclic AMP fraction by whole cells of Escherichia coli B/r was taken as a measure of the in vivo adenylate cyclase activity. This activity was significantly inhibited by irradiation of the cells either with 60Co gamma-rays or with UV light from a germicidal lamp, suggesting inhibition of cyclic AMP synthesis. The incubation of cells after irradiation with lower doses (50-100 Gy) of gamma-rays produced a significant increase of in vivo adenylate cyclase activity, whereas there was no significant change after higher doses (150 Gy and above). Dark incubation of cells after irradiation with UV light (54 J m-2) led to recovery of enzyme activity to the level measured in unirradiated cells. Thus it appears that the catabolite repression of L-arabinose isomerase induced by UV light, as well as gamma-irradiation, is due to reduced cyclic AMP synthesis in irradiated cells.

Determination of Trace Concentration in TMD Detectors using PGAA

NASA Astrophysics Data System (ADS)

Tomandl, I.; Viererbl, L.; Kudějová, P.; Lahodová, Z.; Klupák, V.; Fikrle, M.

2015-05-01

Transmutation detectors could be alternative to the traditional activation detector method for neutron fluence dosimetry at power nuclear reactors. This new method require an isotopically highly-sensitive, non-destructive in sense of compactness as well as isotopic content, precise and standardly used analytical method for trace concentration determination. The capability of Prompt Gamma-ray Activation Analysis (PGAA) for determination of trace concentrations of transmuted stable nuclides in the metallic foils of Ni, Au, Cu and Nb, which were irradiated for 21 days in the reactor core at the LVR-15 research reactor in Řež, is reported. The PGAA measurements of these activation foils were performed at the PGAA facility at Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRMII) in Garching.

DESAlert: Enabling Real-Time Transient Follow-Up with Dark Energy Survey Data

DOE PAGES

Poci, A.; Kuehn, K.; Abbott, T.; ...

2016-09-30

Here, the Dark Energy Survey is undertaking an observational programme imaging 1/4 of the southern hemisphere sky with unprecedented photometric accuracy. In the process of observing millions of faint stars and galaxies to constrain the parameters of the dark energy equation of state, the Dark Energy Survey will obtain pre-discovery images of the regions surrounding an estimated 100 gamma-ray bursts over 5 yr. Once gamma-ray bursts are detected by, e.g., the Swift satellite, the DES data will be extremely useful for follow-up observations by the transient astronomy community. We describe a recently-commissioned suite of software that listens continuously for automatedmore » notices of gamma-ray burst activity, collates information from archival DES data, and disseminates relevant data products back to the community in near-real-time. Of particular importance are the opportunities that non-public DES data provide for relative photometry of the optical counterparts of gamma-ray bursts, as well as for identifying key characteristics (e.g., photometric redshifts) of potential gamma-ray burst host galaxies. We provide the functional details of the DESAlert software, and its data products, and we show sample results from the application of DESAlert to numerous previously detected gamma-ray bursts, including the possible identification of several heretofore unknown gamma-ray burst hosts.« less

DESAlert: Enabling Real-Time Transient Follow-Up with Dark Energy Survey Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poci, A.; Kuehn, K.; Abbott, T.

Here, the Dark Energy Survey is undertaking an observational programme imaging 1/4 of the southern hemisphere sky with unprecedented photometric accuracy. In the process of observing millions of faint stars and galaxies to constrain the parameters of the dark energy equation of state, the Dark Energy Survey will obtain pre-discovery images of the regions surrounding an estimated 100 gamma-ray bursts over 5 yr. Once gamma-ray bursts are detected by, e.g., the Swift satellite, the DES data will be extremely useful for follow-up observations by the transient astronomy community. We describe a recently-commissioned suite of software that listens continuously for automatedmore » notices of gamma-ray burst activity, collates information from archival DES data, and disseminates relevant data products back to the community in near-real-time. Of particular importance are the opportunities that non-public DES data provide for relative photometry of the optical counterparts of gamma-ray bursts, as well as for identifying key characteristics (e.g., photometric redshifts) of potential gamma-ray burst host galaxies. We provide the functional details of the DESAlert software, and its data products, and we show sample results from the application of DESAlert to numerous previously detected gamma-ray bursts, including the possible identification of several heretofore unknown gamma-ray burst hosts.« less

Prompt optical emission from gamma-ray bursts with multiple timescale variability of central engine activities

NASA Astrophysics Data System (ADS)

Xu, Si-Yao; Li, Zhuo

2014-04-01

Complete high-resolution light curves of GRB 080319B observed by Swift present an opportunity for detailed temporal analysis of prompt optical emission. With a two-component distribution of initial Lorentz factors, we simulate the dynamical process of shells being ejected from the central engine in the framework of the internal shock model. The emitted radiations are decomposed into different frequency ranges for a temporal correlation analysis between the light curves in different energy bands. The resulting prompt optical and gamma-ray emissions show similar temporal profiles, with both showing a superposition of a component with slow variability and a component with fast variability, except that the gamma-ray light curve is much more variable than its optical counterpart. The variability in the simulated light curves and the strong correlation with a time lag between the optical and gamma-ray emissions are in good agreement with observations of GRB 080319B. Our simulations suggest that the variations seen in the light curves stem from the temporal structure of the shells injected from the central engine of gamma-ray bursts. Future observations with high temporal resolution of prompt optical emission from GRBs, e.g., by UFFO-Pathfinder and SVOM-GWAC, will provide a useful tool for investigating the central engine activity.

The background model in the energy range from 0.1 MeV up to several MeV for low altitude and high inclination satellites.

NASA Astrophysics Data System (ADS)

Arkhangelskaja, I. V.; Arkhangelskiy, A. I.

2016-02-01

The gamma-ray background physical origin for low altitude orbits defined by: diffuse cosmic gamma-emission, atmospheric gamma-rays, gamma-emission formed in interactions of charged particles (both prompt and activation) and transient events such as electrons precipitations and solar flares. The background conditions in the energy range from 0.1 MeV up to several MeV for low altitude orbits differ due to frequency of Earth Radiation Belts - ERBs (included South Atlantic Anomaly - SAA) passes and cosmic rays rigidity. The detectors and satellite constructive elements are activated by trapped in ERBs and moving along magnetic lines charged particles. In this case we propose simplified polynomial model separately for polar and equatorial orbits parts: background count rate temporal profile approximation by 4-5 order polynomials in equatorial regions, and linear approximations, parabolas or constants in polar caps. The polynomials’ coefficients supposed to be similar for identical spectral channels for each analyzed equatorial part taken into account normalization coefficients defined due to Kp-indexes study within period corresponding to calibration coefficients being approximately constants. The described model was successfully applied for the solar flares hard X-ray and gamma-ray emission characteristic studies by AVS-F apparatus data onboard CORONAS-F satellite.

Important role of catalase in the cellular response of the budding yeast Saccharomyces cerevisiae exposed to ionizing radiation.

PubMed

Nishimoto, Takuto; Furuta, Masakazu; Kataoka, Michihiko; Kishida, Masao

2015-03-01

Ionizing radiation indirectly causes oxidative stress in cells via reactive oxygen species (ROS), such as hydroxyl radicals (OH(-)) generated by the radiolysis of water. We investigated how the catalase function was affected by ionizing radiation and analyzed the phenotype of mutants with a disrupted catalase gene in Saccharomyces cerevisiae exposed to radiation. The wild-type yeast strain and isogenic mutants with disrupted catalase genes were exposed to various doses of (60)Co gamma-rays. There was no difference between the wild-type strain and the cta1 disruption mutant following exposure to gamma-ray irradiation. In contrast, there was a significant decrease in the ctt1 disruption mutant, suggesting that this strain exhibited decreased survival on gamma-ray exposure compared with other strains. In all three strains, stationary phase cells were more tolerant to the exposure of gamma-rays than exponential phase cells, whereas the catalase activity in the wild-type strain and cta1 disruption mutant was higher in the stationary phase than in the exponential phase. These data suggest a correlation between catalase activity and survival following gamma-ray exposure. However, this correlation was not clear in the ctt1 disruption mutant, suggesting that other factors are involved in the tolerance to ROS induced by irradiation.

Current Perspectives in High Energy Astrophysics

NASA Technical Reports Server (NTRS)

Ormes, Jonathan F. (Editor)

1996-01-01

High energy astrophysics is a space-age discipline that has taken a quantum leap forward in the 1990s. The observables are photons and particles that are unable to penetrate the atmosphere and can only be observed from space or very high altitude balloons. The lectures presented as chapters of this book are based on the results from the Compton Gamma-Ray Observatory (CGRO) and Advanced Satellite for Cosmology and Astrophysics (ASCA) missions to which the Laboratory for High Energy Astrophysics at NASA's Goddard Space Flight Center made significant hardware contributions. These missions study emissions from very hot plasmas, nuclear processes, and high energy particle interactions in space. Results to be discussed include gamma-ray beaming from active galactic nuclei (AGN), gamma-ray emission from pulsars, radioactive elements in the interstellar medium, X-ray emission from clusters of galaxies, and the progress being made to unravel the gamma-ray burst mystery. The recently launched X-ray Timing Explorer (XTE) and prospects for upcoming Astro-E and Advanced X-ray Astronomy Satellite (AXAF) missions are also discussed.

Calibration of the ART-XC/SRG X-ray Mirror Modules

NASA Technical Reports Server (NTRS)

Gubarev, M.; Ramsey, B.; Zavlin, V.; Swartz, D.; Kolodziejczak, J.; Elsner, R.; Pavlinsky, M.; Tkachenko, A.; Lapshov, I.

2014-01-01

Seven x-ray mirror modules are being fabricated at the Marshall Space Flight Center (MSFC) for the Astronomical Roentgen Telescope (ART) instrument to be launched on board of the Spektrum Roentgen Gamma (SRG) Mission. As they are completed, the modules are tested and calibrated at the MSFC's 104-m Stray Flight Facility. The results of these calibration measurements and comparisons with theoretical models will be presented.

The Energetic Gamma-Ray Experiment Telescope (EGRET) Science Symposium

NASA Technical Reports Server (NTRS)

Fichtel, Carl E. (Editor); Hunter, Stanley D. (Editor); Sreekumar, Parameswaran (Editor); Stecker, Floyd W. (Editor)

1990-01-01

The principle purpose of this symposium is to provide the EGRET (Energetic Gamma-Ray Experiment Telescope) scientists with an opportunity to study and improve their understanding of high energy gamma ray astronomy. The Symposium began with the galactic diffusion radiation both because of its importance in studying galactic cosmic rays, galactic structure, and dynamic balance, and because an understanding of its characteristics is important in the study of galactic sources. The galactic objects to be reviewed included pulsars, bursts, solar flares, and other galactic sources of several types. The symposium papers then proceeded outward from the Milky Way to normal galaxies, active galaxies, and the extragalactic diffuse radiation.

Energy- and time-resolved detection of prompt gamma-rays for proton range verification.

PubMed

Verburg, Joost M; Riley, Kent; Bortfeld, Thomas; Seco, Joao

2013-10-21

In this work, we present experimental results of a novel prompt gamma-ray detector for proton beam range verification. The detection system features an actively shielded cerium-doped lanthanum(III) bromide scintillator, coupled to a digital data acquisition system. The acquisition was synchronized to the cyclotron radio frequency to separate the prompt gamma-ray signals from the later-arriving neutron-induced background. We designed the detector to provide a high energy resolution and an effective reduction of background events, enabling discrete proton-induced prompt gamma lines to be resolved. Measuring discrete prompt gamma lines has several benefits for range verification. As the discrete energies correspond to specific nuclear transitions, the magnitudes of the different gamma lines have unique correlations with the proton energy and can be directly related to nuclear reaction cross sections. The quantification of discrete gamma lines also enables elemental analysis of tissue in the beam path, providing a better prediction of prompt gamma-ray yields. We present the results of experiments in which a water phantom was irradiated with proton pencil-beams in a clinical proton therapy gantry. A slit collimator was used to collimate the prompt gamma-rays, and measurements were performed at 27 positions along the path of proton beams with ranges of 9, 16 and 23 g cm(-2) in water. The magnitudes of discrete gamma lines at 4.44, 5.2 and 6.13 MeV were quantified. The prompt gamma lines were found to be clearly resolved in dimensions of energy and time, and had a reproducible correlation with the proton depth-dose curve. We conclude that the measurement of discrete prompt gamma-rays for in vivo range verification of clinical proton beams is feasible, and plan to further study methods and detector designs for clinical use.

DEATH LINE OF GAMMA-RAY PULSARS WITH OUTER GAPS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Ren-Bo; Hirotani, Kouichi, E-mail: rbwang1225@gmail.com, E-mail: hirotani@tiara.sinica.edu.tw

2011-08-01

We analytically investigate the condition for a particle accelerator to be active in the outer magnetosphere of a rotation-powered pulsar. Within the accelerator (or the gap), the magnetic-field-aligned electric field accelerates electrons and positrons, which emit copious gamma-rays via the curvature process. If one of the gamma-rays emitted by a single pair materializes as a new pair on average, the gap is self-sustained. However, if the neutron-star spin-down rate decreases below a certain limit, the gap becomes no longer self-sustained and the gamma-ray emission ceases. We explicitly compute the multiplicity of cascading pairs and find that the obtained limit correspondsmore » to a modification of the previously derived outer-gap death line. In addition to this traditional death line, we find another death line, which becomes important for millisecond pulsars, by separately considering the threshold of photon-photon pair production. Combining these traditional and new death lines, we give predictions on the detectability of gamma-ray pulsars with Fermi and AGILE. An implication for X-ray observations of heated polar-cap emission is also discussed.« less

Fermi LAT detection of enhanced gamma-ray emission from the Crab Nebula region

NASA Astrophysics Data System (ADS)

Ojha, Roopesh; Buehler, Rolf; Hays, Elizabeth; Dutka, Michael

2012-07-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed a significant increase in the gamma-ray activity from a source positionally consistent with the Crab Nebula on July 3, 2012. Preliminary LAT analysis indicates that the daily-averaged gamma-ray emission (E >100 MeV) from the direction of the Crab doubled from (2.4 +/- 0.5) x 10^-6 ph/cm2/sec (statistical errors only) on July 2nd to (5.5 +/- 0.7) x 10^-6 ph/cm2/sec on July 3rd, a factor of 2 greater than the average flux of (2.75 +/- 0.10) x 10^-6 ph/cm2/sec reported in the second Fermi LAT catalog (2FGL, Nolan et al.

Fermi-LAT detection of increased gamma-ray activity from the FSRQ PKS 1004-217

NASA Astrophysics Data System (ADS)

Kreter, Michael

2018-03-01

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with the flat spectrum radio quasar (FSRQ) PKS 1004-217 (3FGL J1006.7-2159) with coordinates RA: 10h06m46.4136s, DEC: -21d59m20.410s, J2000 (Beasley et al. 2002, ApJS, 141, 13) and redshift z=0.331 (Hewitt & Burbidge 1989, ApJS, 69, 1). Preliminary analysis indicates that on 4 March 2018, this source was in a high-flux state with a daily averaged gamma-ray flux (E > 100MeV) of (0.84+/-0.08) X 10^-6 photons cm^-2 s^-1 (statistical uncertainties only).

Forward directed x-ray from source produced by relativistic electrons from a Self-Modulated Laser Wakefield Accelerator

NASA Astrophysics Data System (ADS)

Lemos, Nuno; Albert, Felicie; Shaw, Jessica; King, Paul; Milder, Avi; Marsh, Ken; Pak, Arthur; Joshi, Chan

2017-10-01

Plasma-based particle accelerators are now able to provide the scientific community with novel light sources. Their applications span many disciplines, including high-energy density sciences, where they can be used as probes to explore the physics of dense plasmas and warm dense matter. A recent advance is in the experimental and theoretical characterization of x-ray emission from electrons in the self-modulated laser wakefield regime (SMLWFA) where little is known about the x-ray properties. A series of experiments at the LLNL Jupiter Laser Facility, using the 1 ps 150 J Titan laser, have demonstrated low divergence electron beams with energies up to 300 MeV and 6 nCs of charge, and betatron x-rays with critical energies up to 20 keV. This work identifies two other mechanisms which produce high energy broadband x-rays and gamma-rays from the SMLWFA: Bremsstrahlung and inverse Compton scattering. We demonstrate the use of Compton scattering and bremsstrahlung to generate x/Gamma-rays from 3 keV up to 1.5 MeV with a source size of 50um and a divergence of 100 mrad. This work is an important step towards developing this x-ray light source on large-scale international laser facilities, and also opens up the prospect of using them for applications. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under the contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC.

Development and verification of signal processing system of avalanche photo diode for the active shields onboard ASTRO-H

NASA Astrophysics Data System (ADS)

Ohno, M.; Kawano, T.; Edahiro, I.; Shirakawa, H.; Ohashi, N.; Okada, C.; Habata, S.; Katsuta, J.; Tanaka, Y.; Takahashi, H.; Mizuno, T.; Fukazawa, Y.; Murakami, H.; Kobayashi, S.; Miyake, K.; Ono, K.; Kato, Y.; Furuta, Y.; Murota, Y.; Okuda, K.; Wada, Y.; Nakazawa, K.; Mimura, T.; Kataoka, J.; Ichinohe, Y.; Uchida, Y.; Katsuragawa, M.; Yoneda, H.; Sato, G.; Sato, R.; Kawaharada, M.; Harayama, A.; Odaka, H.; Hayashi, K.; Ohta, M.; Watanabe, S.; Kokubun, M.; Takahashi, T.; Takeda, S.; Kinoshita, M.; Yamaoka, K.; Tajima, H.; Yatsu, Y.; Uchiyama, H.; Saito, S.; Yuasa, T.; Makishima, K.; ASTRO-H HXI/SGD Team

2016-09-01

The hard X-ray Imager and Soft Gamma-ray Detector onboard ASTRO-H demonstrate high sensitivity to hard X-ray (5-80 keV) and soft gamma-rays (60-600 keV), respectively. To reduce the background, both instruments are actively shielded by large, thick Bismuth Germanate scintillators. We have developed the signal processing system of the avalanche photodiode in the BGO active shields and have demonstrated its effectiveness after assembly in the flight model of the HXI/SGD sensor and after integration into the satellite. The energy threshold achieved is about 150 keV and anti-coincidence efficiency for cosmic-ray events is almost 100%. Installed in the BGO active shield, the developed signal processing system successfully reduces the room background level of the main detector.

Cosmic ray interactions in starbursting galaxies

NASA Astrophysics Data System (ADS)

Yoast-Hull, Tova M.

High quality gamma-ray and radio observations of nearby galaxies offer an unprecedented opportunity to quantitatively study the properties of their cosmic ray populations. Accounting for various interactions and energy losses, I developed a multi-component, single-zone model of the cosmic ray populations in the central molecular zones of star-forming galaxies. Using observational knowledge of the interstellar medium and star formation, I successfully predicted the radio, gamma-ray, and neutrino spectra for nearby starbursts. Using chi-squared tests to compare the models with observational radio and gamma-ray data, I placed constraints on magnetic field strengths, cosmic ray energy densities, and galactic wind (advection) speeds. The initial models were applied to and tested on the prototypical starburst galaxy M82. To further test the model and to explore the differences in environment between starbursts and active galactic nuclei, I studied NGC 253 and NGC 1068, both nearby giant spiral galaxies which have been detected in gamma-rays. Additionally, I demonstrated that the excess GeV energy gamma-ray emission in the Galactic Center is likely not diffuse emission from an additional population of cosmic rays accelerated in supernova remnants. Lastly, I investigated cosmic ray populations in the starburst nuclei of Arp 220, a nearby ultraluminous infrared galaxy which displays a high-intensity mode of star formation more common in young galaxies, and I showed that the nuclei are efficient cosmic-ray proton calorimeters.

Optical flare observed in the flaring gamma-ray blazar Ton 599

NASA Astrophysics Data System (ADS)

Pursimo, Tapio; Sagues, Ana; Telting, John; Ojha, Roopesh

2017-11-01

We report optical photometry of the flat spectrum radio quasar Ton 599, obtained with the 2.56m Nordic Optical Telescope in La Palma, to look for any enhanced optical activity associated with a recent flare in the daily averaged gamma-ray flux (ATel#10931, ATel#10937).

The recent NIR Flare of the Blazar CTA102

NASA Astrophysics Data System (ADS)

Carrasco, L.; Escobedo, G.; Porras, A.; Recillas, E.; Chavushyan, V.; Mayya, D. Y.

2018-01-01

Following the report of increased Gamma-Ray activity detected by AGILE of the high redshift QSO (z=1.037) CTA102 cross identified with the radio source 4C+11.69 and the Gamma-ray source 2FGLJ2232.4+1143 by Lucarelli et al.(ATEL #11045).

Optical flare observed in the flaring gamma-ray blazar S5 1044+71

NASA Astrophysics Data System (ADS)

Pursimo, Tapio; Blay, Pere; Telting, John; Ojha, Roopesh

2017-01-01

We report optical photometry of the blazar S5 1044+71, obtained with the 2.56m Nordic Optical Telescope in La Palma, to look for any enhanced optical activity associated with a recent flare in the daily averaged gamma-ray flux (ATel#9928).

Fermi (Formerly GLAST) at Six Months

NASA Technical Reports Server (NTRS)

Ritz, Steven M.

2009-01-01

The Fermi Gamma-ray Space Telescope, formerly called GLAST, is a mission to measure the cosmic gamma-ray flux in the energy range 20 MeV to more than 300 GeV, with supporting measurements for gamma-ray bursts from 8 keV to 30 MeV. In addition to breakthrough capabilities in energy coverage and localization, the very large field of view enables observations of 20% of the sky at any instant, and the entire sky on a timescale of a few hours. With its recent launch on 11 June 2008, Fermi now opens a new and important window on a wide variety of phenomena, including pulsars, black holes and active galactic nuclei, gamma-ray bursts, the origin of cosmic rays and supernova remnants, and searches for hypothetical new phenomena such as supersymmetric dark matter annihilations. In addition to early results and the science opportunities, this talk includes a description of the instruments and the mission status and plans.

Fermi (nee GLAST) at Six Months

NASA Technical Reports Server (NTRS)

Ritz, Steve

2009-01-01

The Fermi Gamma-ray Space Telescope, formerly called GLAST, is a mission to measure the cosmic gamma-ray flux in the energy range 20 MeV to >300 GeV, with supporting measurements for gamma-ray bursts from 8 keV to 30 MeV. In addition to breakthrough capabilities in energy coverage and localization, the very large field of view enables observations of 20% of the sky at any instant, and the entire sky on a timescale of a few hours. With its recent launch on 11 June 2008, Fermi now opens a new and important window on a wide variety of phenomena, including pulsars, black holes and active galactic nuclei, gamma-ray bursts, the origin of cosmic rays and supernova remnants, and searches for hypothetical new phenomena such as supersymmetric dark matter annihilations. In addition to early results and the science opportunities, this talk includes a description of the instruments and the mission status and plans.

Some aspects of the scientific significance of high energy gamma ray astrophysics

NASA Technical Reports Server (NTRS)

Fichtel, Carl E.

1991-01-01

The attraction of high energy gamma-ray astronomy lies in this radiation relating directly to those processes in astrophysical situations which deviate most from thermo-dynamic equilibrium. Some examples of these phenomena which are known to or expected to emit gamma rays are cosmic rays as they interact in intergalactic space, the high energy particles in the magnetic fields of neutron stars, the death of a black hole, the explosion and residual of a supernova, lumps of Weakly Interacting Massive Particles, energetic solar particles interacting near the sun, and very high energy particles in the extreme conditions associated with active galaxies. Although the intensities are known to be low as seen near the earth, a partially compensating characteristic is that the very penetrating nature of high energy gamma rays increases the probability that they can escape from their origin and reach the solar system.

Gamma irradiation effect on the chemical composition and the antioxidant activity of Ipomoea batatas L.

NASA Astrophysics Data System (ADS)

Tahir, D.; Halide, H.; Wahab, A. W.; Kurniawan, D.

2014-09-01

The chemical composition and antioxidant activity of Ipomoea batatas L. (sweet potato) were studied by x-ray fluorescence (XRF) spectroscopy, Fourier transform infrared spectroscopy, and by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity. The irradiation treatment was performed by using Cs-137 as a gamma sources in experimental equipment. Treatment by irradiation emerges as a possible conservation technique that has been tested successfully in several food products. The amount of chemical composition was changed and resulting new chemical for absorbed dose 40 mSv. Interestingly, it was found that gamma irradiation significantly increased the antioxidant activity, as measured by DPPH radical scavenging capacity. The antioxidant activity of Ipomoea batatas L. extract was dramatically increased in the non-irradiated sample to the sample irradiated at 40 mSv. These results indicate that gamma irradiation of Ipomoea batatas L. extract can enhance its antioxidant activity through the formation of a new chemical compound. Based on these results, increased antioxidant activity of Ipomoea batatas L. extracts by gamma rays can be applied to various industries, especially cosmetics, foodstuffs, and pharmaceuticals.

Measurement and analysis of gamma-rays emitted from spent nuclear fuel above 3 MeV.

PubMed

Rodriguez, Douglas C; Anderson, Elaina; Anderson, Kevin K; Campbell, Luke W; Fast, James E; Jarman, Kenneth; Kulisek, Jonathan; Orton, Christopher R; Runkle, Robert C; Stave, Sean

2013-12-01

The gamma-ray spectrum of spent nuclear fuel in the 3-6 MeV energy range is important for active interrogation since gamma rays emitted from nuclear decay are not expected to interfere with measurements in this energy region. There is, unfortunately, a dearth of empirical measurements from spent nuclear fuel in this region. This work is an initial attempt to partially fill this gap by presenting an analysis of gamma-ray spectra collected from a set of spent nuclear fuel sources using a high-purity germanium detector array. This multi-crystal array possesses a large collection volume, providing high energy resolution up to 16 MeV. The results of these measurements establish the continuum count-rate in the energy region between 3 and 6 MeV. Also assessed is the potential for peaks from passive emissions to interfere with peak measurements resulting from active interrogation delayed emissions. As one of the first documented empirical measurements of passive emissions from spent fuel for energies above 3 MeV, this work provides a foundation for active interrogation model validation and detector development. © 2013 Elsevier Ltd. All rights reserved.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toyoshima, K.; Niwa, O.; Yutsudo, M.

1980-09-01

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

High-energy variability of the Pulsar binary PSR J1311-3430

NASA Astrophysics Data System (ADS)

An, Hongjun; Fermi-LAT Collaboration

2018-01-01

We present analysis results of high-energy observations of the extreme mass-ratio black-widow millisecond pulsar binary PSR J1311-3430. Our studies in the UV, X-ray, and gamma-ray bands confirm the orbital modulation in the gamma-ray band as suggested previously. In addition, we find that the modulation is stronger in the high-energy band. In the lower-energy UV and X-ray bands, we detect flares which were observed previously and attributed to magnetic activities. We find that the optical flares are associated with the X-ray flares, suggesting common origin. We explore possible connections of the variabilities with the intrabinary shock (IBS) and magnetic activity on the low mass companion.

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

ScienceCinema

Isabelle Grenier

2018-04-17

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.

Very fast optical flaring from a possible new Galactic magnetar.

PubMed

Stefanescu, A; Kanbach, G; Słowikowska, A; Greiner, J; McBreen, S; Sala, G

2008-09-25

Highly luminous rapid flares are characteristic of processes around compact objects like white dwarfs, neutron stars and black holes. In the high-energy regime of X-rays and gamma-rays, outbursts with variabilities on timescales of seconds or less are routinely observed, for example in gamma-ray bursts or soft gamma-ray repeaters. At optical wavelengths, flaring activity on such timescales has not been observed, other than from the prompt phase of one exceptional gamma-ray burst. This is mostly due to the fact that outbursts with strong, fast flaring are usually discovered in the high-energy regime; most optical follow-up observations of such transients use instruments with integration times exceeding tens of seconds, which are therefore unable to resolve fast variability. Here we show the observation of extremely bright and rapid optical flaring in the Galactic transient SWIFT J195509.6+261406. Our optical light curves are phenomenologically similar to high-energy light curves of soft gamma-ray repeaters and anomalous X-ray pulsars, which are thought to be neutron stars with extremely high magnetic fields (magnetars). This suggests that similar processes are in operation, but with strong emission in the optical, unlike in the case of other known magnetars.

Gamma-ray mirror technology for NDA of spent fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Descalle, M. A.; Ruz-Armendariz, J.; Decker, T.

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

Multi-particle inspection using associated particle sources

DOEpatents

Bingham, Philip R.; Mihalczo, John T.; Mullens, James A.; McConchie, Seth M.; Hausladen, Paul A.

2016-02-16

Disclosed herein are representative embodiments of methods, apparatus, and systems for performing combined neutron and gamma ray radiography. For example, one exemplary system comprises: a neutron source; a set of alpha particle detectors configured to detect alpha particles associated with neutrons generated by the neutron source; neutron detectors positioned to detect at least some of the neutrons generated by the neutron source; a gamma ray source; a set of verification gamma ray detectors configured to detect verification gamma rays associated with gamma rays generated by the gamma ray source; a set of gamma ray detectors configured to detect gamma rays generated by the gamma ray source; and an interrogation region located between the neutron source, the gamma ray source, the neutron detectors, and the gamma ray detectors.

Conceptual design of the gamma-to-electron magnetic spectrometer for the National Ignition Facility

DOE PAGES

Kim, Y.; Herrmann, H. W.; Jorgenson, H. J.; ...

2014-08-01

The Gamma-to-Electron Magnetic Spectrometer (GEMS) diagnostic is designed to measure the prompt γ-ray energy spectrum during high yield deuterium-tritium (DT) implosions at the National Ignition Facility (NIF). The prompt γ-ray spectrum will provide ‘burn-averaged’ observables, including total DT fusion yield, total areal density (ρR), ablator ρR, and fuel ρR. These burn-averaged observables are unique because they are essentially averaged over 4π, providing a global reference for the line-of-sight-specific measurements typical of x-ray and neutron diagnostics. The GEMS conceptual design meets the physics-based requirements: ΔE/E = 3 - 5% can be achieved in the range of 2 - 25 MeV γ-raymore » energy. Minimum DT neutron yields required for 15% measurement uncertainty at low-resolution mode are: 5×10 14 DT-n for ablator ρR (at 0.2 g/cm 2); 2×10 15 DT-n for total DT yield (at 4.2×10 -5γ /n); and 1×10 16 DT-n for fuel ρR (at 1 g/cm 2).« less

Comparison of experimental results of a Quad-CZT array detector, a NaI(Tl), a LaBr3(Ce), and a HPGe for safeguards applications

NASA Astrophysics Data System (ADS)

Kwak, S.-W.; Choi, J.; Park, S. S.; Ahn, S. H.; Park, J. S.; Chung, H.

2017-11-01

A compound semiconductor detector, CdTe (or CdZnTe), has been used in various areas including nuclear safeguards applications. To address its critical drawback, low detection efficiency, which leads to a long measurement time, a Quad-CZT array-based gamma-ray spectrometer in our previous study has been developed by combining four individual CZT detectors. We have re-designed the developed Quad-CZT array system to make it more simple and compact for a hand-held gamma-ray detector. The objective of this paper aims to compare the improved Quad-CZT array system with the traditional gamma-ray spectrometers (NaI(Tl), LaBr3(Ce), HPGe); these detectors currently have been the most commonly used for verification of nuclear materials. Nuclear materials in different physical forms in a nuclear facility of Korea were measured by the Quad-CZT array system and the existing gamma-ray detectors. For measurements of UO2 pellets and powders, and fresh fuel rods, the Quad-CZT array system turned out to be superior to the NaI(Tl) and LaBr3(Ce). For measurements of UF6 cylinders with a thick wall, the Quad-CZT array system and HPGe gave similar accuracy under the same measurement time. From the results of the field tests conducted, we can conclude that the improved Quad-CZT array system would be used as an alternative to HPGes and scintillation detectors for the purpose of increasing effectivenss and efficiency of safeguards applications. This is the first paper employing a multi-element CZT array detector for measurement of nuclear materials—particularly uranium in a UF6 cylinder—in a real nuclear facility. The present work also suggests that the multi-CZT array system described in this study would be one promising method to address a serious weakness of CZT-based radiation detection.

SKYSINE-II procedure: calculation of the effects of structure design on neutron, primary gamma-ray and secondary gamma-ray dose rates in air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lampley, C.M.

1979-01-01

An updated version of the SKYSHINE Monte Carlo procedure has been developed. The new computer code, SKYSHINE-II, provides a substantial increase in versatility in that the program possesses the ability to address three types of point-isotropic radiation sources: (1) primary gamma rays, (2) neutrons, and (3) secondary gamma rays. In addition, the emitted radiation may now be characterized by an energy emission spectrum product of a new energy-dependent atmospheric transmission data base developed by Radiation Research Associates, Inc. for each of the three source types described above. Most of the computational options present in the original program have been retainedmore » in the new version. Hence, the SKYSHINE-II computer code provides a versatile and viable tool for the analysis of the radiation environment in the vicinity of a building structure containing radiation sources, situated within the confines of a nuclear power plant. This report describes many of the calculational methods employed within the SKYSHINE-II program. A brief description of the new data base is included. Utilization instructions for the program are provided for operation of the SKYSHINE-II code on the Brookhaven National Laboratory Central Scientific Computing Facility. A listing of the source decks, block data routines, and the new atmospheric transmission data base are provided in the appendices of the report.« less

Chandra X-Ray Observations of the Two Brightest Unidentified High Galactic Latitude Fermi-LAT Gamma-Ray Sources

NASA Technical Reports Server (NTRS)

Cheung, C. C.; Donato, D.; Gehrels, N.; Sokolovsky, K. V.; Giroletti, M.

2012-01-01

We present Chandra ACIS-I X-ray observations of 0FGL J1311.9-3419 and 0FGL J1653.4-0200, the two brightest high Galactic latitude (absolute value (beta) >10 deg) gamma-ray sources from the three-month Fermi Large Area Telescope (LAT) bright source list that are still unidentified. Both were also detected previously by EGRET, and despite dedicated multi-wavelength follow-up, they are still not associated with established classes of gamma-ray emitters like pulsars or radio-loud active galactic nuclei. X-ray sources found in the ACIS-I fields of view are cataloged, and their basic properties are determined. These are discussed as candidate counterparts to 0FGL J1311.9-3419 and 0FGL J1653.4-0200, with particular emphasis on the brightest of the 9 and 13 Chandra sources detected within the respective Fermi-LAT 95% confidence regions. Further follow-up studies, including optical photometric and spectroscopic observations, are necessary to identify these X-ray candidate counterparts in order to ultimately reveal the nature of these enigmatic gamma-ray objects.

Effects of Correlated and Uncorrelated Gamma Rays on Neutron Multiplicity Counting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cowles, Christian C.; Behling, Richard S.; Imel, George R.

Neutron multiplicity counting relies on time correlation between neutron events to assay the fissile mass, (α,n) to spontaneous fission neutron ratio, and neutron self-multiplication of samples. Gamma-ray sensitive neutron multiplicity counters may misidentify gamma rays as neutrons and therefore miscalculate sample characteristics. Time correlated and uncorrelated gamma-ray-like signals were added into gamma-ray free neutron multiplicity counter data to examine the effects of gamma ray signals being misidentified as neutron signals on assaying sample characteristics. Multiplicity counter measurements with and without gamma-ray-like signals were compared to determine the assay error associated with gamma-ray-like signals at various gamma-ray and neutron rates. Correlatedmore » and uncorrelated gamma-ray signals each produced consistent but different measurement errors. Correlated gamma-ray signals most strongly led to fissile mass overestimates, whereas uncorrelated gamma-ray signals most strongly lead to (α,n) neutron overestimates. Gamma-ray sensitive neutron multiplicity counters may be able to account for the effects of gamma-rays on measurements to mitigate measurement uncertainties.« less

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

NASA Astrophysics Data System (ADS)

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

2014-11-01

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

New radiation protection calibration facility at CERN.

PubMed

Brugger, Markus; Carbonez, Pierre; Pozzi, Fabio; Silari, Marco; Vincke, Helmut

2014-10-01

The CERN radiation protection group has designed a new state-of-the-art calibration laboratory to replace the present facility, which is >20 y old. The new laboratory, presently under construction, will be equipped with neutron and gamma sources, as well as an X-ray generator and a beta irradiator. The present work describes the project to design the facility, including the facility placement criteria, the 'point-zero' measurements and the shielding study performed via FLUKA Monte Carlo simulations. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Air shower detectors in gamma-ray astronomy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinnis, Gus

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,more » 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.« less

Experimental Determination of the HPGe Spectrometer Efficiency Calibration Curves for Various Sample Geometry for Gamma Energy from 50 keV to 2000 keV

NASA Astrophysics Data System (ADS)

Saat, Ahmad; Hamzah, Zaini; Yusop, Mohammad Fariz; Zainal, Muhd Amiruddin

2010-07-01

Detection efficiency of a gamma-ray spectrometry system is dependent upon among others, energy, sample and detector geometry, volume and density of the samples. In the present study the efficiency calibration curves of newly acquired (August 2008) HPGe gamma-ray spectrometry system was carried out for four sample container geometries, namely Marinelli beaker, disc, cylindrical beaker and vial, normally used for activity determination of gamma-ray from environmental samples. Calibration standards were prepared by using known amount of analytical grade uranium trioxide ore, homogenized in plain flour into the respective containers. The ore produces gamma-rays of energy ranging from 53 keV to 1001 keV. Analytical grade potassium chloride were prepared to determine detection efficiency of 1460 keV gamma-ray emitted by potassium isotope K-40. Plots of detection efficiency against gamma-ray energy for the four sample geometries were found to fit smoothly to a general form of ɛ = AΕa+BΕb, where ɛ is efficiency, Ε is energy in keV, A, B, a and b are constants that are dependent on the sample geometries. All calibration curves showed the presence of a "knee" at about 180 keV. Comparison between the four geometries showed that the efficiency of Marinelli beaker is higher than cylindrical beaker and vial, while cylindrical disk showed the lowest.

CONSTRAINING THE EMISSIVITY OF ULTRAHIGH ENERGY COSMIC RAYS IN THE DISTANT UNIVERSE WITH THE DIFFUSE GAMMA-RAY EMISSION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Xiangyu; Liu Ruoyu; Aharonian, Felix

Ultrahigh cosmic rays (UHECRs) with energies {approx}> 10{sup 19} eV emitted at cosmological distances will be attenuated by cosmic microwave and infrared background radiation through photohadronic processes. Lower energy extragalactic cosmic rays ({approx}10{sup 18}-10{sup 19} eV) can only travel a linear distance smaller than {approx}Gpc in a Hubble time due to the diffusion if the extragalactic magnetic fields are as strong as nano-Gauss. These prevent us from directly observing most of the UHECRs in the universe, and thus the observed UHECR intensity reflects only the emissivity in the nearby universe within hundreds of Mpc. However, UHECRs in the distant universe,more » through interactions with the cosmic background photons, produce UHE electrons and gamma rays that in turn initiate electromagnetic cascades on cosmic background photons. This secondary cascade radiation forms part of the extragalactic diffuse GeV-TeV gamma-ray radiation and, unlike the original UHECRs, is observable. Motivated by new measurements of extragalactic diffuse gamma-ray background radiation by Fermi/Large Area Telescope, we obtained upper limit placed on the UHECR emissivity in the distant universe by requiring that the cascade radiation they produce not exceed the observed levels. By comparison with the gamma-ray emissivity of candidate UHECR sources (such as gamma-ray bursts (GRBs) and active galactic nuclei) at high redshifts, we find that the obtained upper limit for a flat proton spectrum is {approx_equal} 10{sup 1.5} times larger than the gamma-ray emissivity in GRBs and {approx_equal} 10 times smaller than the gamma-ray emissivity in BL Lac objects. In the case of iron nuclei composition, the derived upper limit of UHECR emissivity is a factor of 3-5 times higher. Robust upper limit on the cosmogenic neutrino flux is further obtained, which is marginally reachable by the Icecube detector and the next-generation detector JEM-EUSO.« less

Integrated instrumentation & computation environment for GRACE

NASA Astrophysics Data System (ADS)

Dhekne, P. S.

2002-03-01

The project GRACE (Gamma Ray Astrophysics with Coordinated Experiments) aims at setting up a state of the art Gamma Ray Observatory at Mt. Abu, Rajasthan for undertaking comprehensive scientific exploration over a wide spectral window (10's keV - 100's TeV) from a single location through 4 coordinated experiments. The cumulative data collection rate of all the telescopes is expected to be about 1 GB/hr, necessitating innovations in the data management environment. As real-time data acquisition and control as well as off-line data processing, analysis and visualization environment of these systems is based on the us cutting edge and affordable technologies in the field of computers, communications and Internet. We propose to provide a single, unified environment by seamless integration of instrumentation and computations by taking advantage of the recent advancements in Web based technologies. This new environment will allow researchers better acces to facilities, improve resource utilization and enhance collaborations by having identical environments for online as well as offline usage of this facility from any location. We present here a proposed implementation strategy for a platform independent web-based system that supplements automated functions with video-guided interactive and collaborative remote viewing, remote control through virtual instrumentation console, remote acquisition of telescope data, data analysis, data visualization and active imaging system. This end-to-end web-based solution will enhance collaboration among researchers at the national and international level for undertaking scientific studies, using the telescope systems of the GRACE project.

NEUTRON MULTIPLICITY AND ACTIVE WELL NEUTRON COINCIDENCE VERIFICATION MEASUREMENTS PERFORMED FOR MARCH 2009 SEMI-ANNUAL DOE INVENTORY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dewberry, R.; Ayers, J.; Tietze, F.

The Analytical Development (AD) Section field nuclear measurement group performed six 'best available technique' verification measurements to satisfy a DOE requirement instituted for the March 2009 semi-annual inventory. The requirement of (1) yielded the need for SRNL Research Operations Department Material Control & Accountability (MC&A) group to measure the Pu content of five items and the highly enrich uranium (HEU) content of two. No 14Q-qualified measurement equipment was available to satisfy the requirement. The AD field nuclear group has routinely performed the required Confirmatory Measurements for the semi-annual inventories for fifteen years using sodium iodide and high purity germanium (HpGe)more » {gamma}-ray pulse height analysis nondestructive assay (NDA) instruments. With appropriate {gamma}-ray acquisition modeling, the HpGe spectrometers can be used to perform verification-type quantitative assay for Pu-isotopics and HEU content. The AD nuclear NDA group is widely experienced with this type of measurement and reports content for these species in requested process control, MC&A booking, and holdup measurements assays Site-wide. However none of the AD HpGe {gamma}-ray spectrometers have been 14Q-qualified, and the requirement of reference 1 specifically excluded a {gamma}-ray PHA measurement from those it would accept for the required verification measurements. The requirement of reference 1 was a new requirement for which the Savannah River National Laboratory (SRNL) Research Operations Department (ROD) MC&A group was unprepared. The criteria for exemption from verification were: (1) isotope content below 50 grams; (2) intrinsically tamper indicating or TID sealed items which contain a Category IV quantity of material; (3) assembled components; and (4) laboratory samples. Therefore all (SRNL) Material Balance Area (MBA) items with greater than 50 grams total Pu or greater than 50 grams HEU were subject to a verification measurement. The pass/fail criteria of reference 7 stated 'The facility will report measured values, book values, and statistical control limits for the selected items to DOE SR...', and 'The site/facility operator must develop, document, and maintain measurement methods for all nuclear material on inventory'. These new requirements exceeded SRNL's experience with prior semi-annual inventory expectations, but allowed the AD nuclear field measurement group to demonstrate its excellent adaptability and superior flexibility to respond to unpredicted expectations from the DOE customer. The requirements yielded five SRNL items subject to Pu verification and two SRNL items subject to HEU verification. These items are listed and described in Table 1.« less

Calibration and performance of a real-time gamma-ray spectrometry water monitor using a LaBr3(Ce) detector

NASA Astrophysics Data System (ADS)

Prieto, E.; Casanovas, R.; Salvadó, M.

2018-03-01

A scintillation gamma-ray spectrometry water monitor with a 2″ × 2″ LaBr3(Ce) detector was characterized in this study. This monitor measures gamma-ray spectra of river water. Energy and resolution calibrations were performed experimentally, whereas the detector efficiency was determined using Monte Carlo simulations with EGS5 code system. Values of the minimum detectable activity concentrations for 131I and 137Cs were calculated for different integration times. As an example of the monitor performance after calibration, a radiological increment during a rainfall episode was studied.

All-Sky Earth Occultation Observations with the Fermi Gamma Ray Burst Monitor

NASA Technical Reports Server (NTRS)

Wilson-Hodge, C. A.; Beklen, E.; Bhat, P. N.; Briggs, M.; Camero-Arranz, A.; Case, G.; Chaplin, V.; Cherry, M.; Connaughton, V.; Finger, M.;

In-Beam Studies of High Spin States in Mercury -182 and MERCURY-184

NASA Astrophysics Data System (ADS)

Bindra, Kanwarjit Singh

The high spin states in ^{182 }Hg were studied by using the reaction ^{154}Gd(^{32}S, 4n) at the Holifield Heavy Ion Research Facility. In addition, the in-beam gamma-rays in ^{183}Hg were identified for the first time using the reaction ^{155}Gd(^{32}S, 4n) at the Argonne BGO-FMA facility. Five new bands were observed for the first time in ^{182}Hg by studying the gamma-gamma coincidence relationships. The spins and parities of the nuclear levels were assigned on the basis of the measured ratios of directional correlations for oriented nuclei (DCO ratios). Shape co-existence similar to that observed in ^{184{-}186}Hg was established. The well deformed prolate band was extended to a state with tentative spin (20^+). The 2^+ state of the prolate band was identified at an energy of 548.6 keV which is higher in energy than in ^{184}Hg. A two parameter band mixing calculation yielded an interaction strength of 87 keV between the prolate 2^+ and the oblate 2^+ states. Four of the five new bands were found to be similar in behavior to ones seen in ^{184}Hg. An attempt was made to study the behavior of some of these bands at high spins by analyzing their kinematic and dynamic moments of inertia. The gamma-ray transitions in ^{183}Hg were identified from fragment-gamma and gamma-gamma coincidence measurements. A total of five bands of levels were identified and the spins and parities of the levels were assigned by comparing the level scheme of ^{138 }Hg obtained with that of ^ {185}Hg established previously. The interpretation of these bands in terms of associated quasi-particle configurations also relies on noted similarities with the structure of ^{185}Hg. Shape co-existence was established in ^{183}Hg as a result of this study. Two of the bands associated with the (624) 9/2^+ orbital were found to exhibit signature splitting, as expected for i _{13/2} excitations built on the prolate shape with moderate deformation. Two other bands which do not show signature splitting have been associated with the (514) 7/2- orbital and the gamma-ray transition energies in these bands were found to be "identical" to those present in bands with the same configuration in ^{185 }Hg.

A Novel Approach in the Weakly Interacting Massive Particle Quest: Cross-correlation of Gamma-Ray Anisotropies and Cosmic Shear

NASA Astrophysics Data System (ADS)

Camera, Stefano; Fornasa, Mattia; Fornengo, Nicolao; Regis, Marco

2013-07-01

Both cosmic shear and cosmological gamma-ray emission stem from the presence of dark matter (DM) in the universe: DM structures are responsible for the bending of light in the weak-lensing regime and those same objects can emit gamma rays, either because they host astrophysical sources (active galactic nuclei or star-forming galaxies) or directly by DM annihilations (or decays, depending on the properties of the DM particle). Such gamma rays should therefore exhibit strong correlation with the cosmic shear signal. In this Letter, we compute the cross-correlation angular power spectrum of cosmic shear and gamma rays produced by the annihilation/decay of weakly interacting massive particle DM, as well as by astrophysical sources. We show that this observable provides novel information on the composition of the extragalactic gamma-ray background (EGB), since the amplitude and shape of the cross-correlation signal strongly depend on which class of sources is responsible for the gamma-ray emission. If the DM contribution to the EGB is significant (at least in a definite energy range), although compatible with current observational bounds, its strong correlation with the cosmic shear makes such signal potentially detectable by combining Fermi Large Area Telescope data with forthcoming galaxy surveys, like the Dark Energy Survey and Euclid. At the same time, the same signal would demonstrate that the weak-lensing observables are indeed due to particle DM matter and not to possible modifications of general relativity.

Prediction of ECS and SSC Models for Flux-Limited Samples of Gamma-Ray Blazars

NASA Technical Reports Server (NTRS)

Lister, Matthew L.; Marscher, Alan P.

1999-01-01

The external Compton scattering (ECS) and synchrotron self-Compton (SSC) models make distinct predictions for the amount of Doppler boosting of high-energy gamma-rays emitted by Nazar. We examine how these differences affect the predicted properties of active galactic nucleus (AGN) samples selected on the basis of Murray emission. We create simulated flux-limited samples based on the ECS and SSC models, and compare their properties to those of identified EGRET blazars. We find that for small gamma-ray-selected samples, the two models make very similar predictions, and cannot be reliably distinguished. This is primarily due to the fact that not only the Doppler factor, but also the cosmological distance and intrinsic luminosity play a role in determining whether an AGN is included in a flux-limited gamma-ray sample.

Specification of High Activity Gamma-Ray Sources.

ERIC Educational Resources Information Center

International Commission on Radiation Units and Measurements, Washington, DC.

The report is concerned with making recommendations for the specifications of gamma ray sources, which relate to the quantity of radioactive material and the radiation emitted. Primary consideration is given to sources in teletherapy and to a lesser extent those used in industrial radiography and in irradiation units used in industry and research.…

MAGIC detection of increased activity from FSRQ 3C 279 at very-high-energy gamma rays

NASA Astrophysics Data System (ADS)

Mirzoyan, Razmik

2018-04-01

The MAGIC telescopes observed an increase in the very-high-energy (VHE; > 100 GeV) gamma-ray flux from FSRQ 3C 279 at radio coordinates R.A.=194.04652737 deg and Dec= -5.78931242 deg, J2000.0 (Fey et al. 2004, AJ, 127, 3587).

A TIGHT CONNECTION BETWEEN GAMMA-RAY OUTBURSTS AND PARSEC-SCALE JET ACTIVITY IN THE QUASAR 3C 454.3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jorstad, Svetlana G.; Marscher, Alan P.; Agudo, Ivan

2013-08-20

We analyze the multi-frequency behavior of the quasar 3C 454.3 during three prominent {gamma}-ray outbursts: 2009 Autumn, 2010 Spring, and 2010 Autumn. The data reveal a repeating pattern, including a triple flare structure, in the properties of each {gamma}-ray outburst, which implies similar mechanism(s) and location for all three events. The multi-frequency behavior indicates that the lower frequency events are co-spatial with the {gamma}-ray outbursts, although the {gamma}-ray emission varies on the shortest timescales. We determine that the variability from UV to IR wavelengths during an outburst results from a single synchrotron component whose properties do not change significantly overmore » the different outbursts. Despite a general increase in the degree of optical linear polarization during an outburst, the polarization drops significantly at the peak of the {gamma}-ray event, which suggests that both shocks and turbulent processes are involved. We detect two disturbances (knots) with superluminal apparent speeds in the parsec-scale jet associated with the outbursts in 2009 Autumn and 2010 Autumn. The kinematic properties of the knots can explain the difference in amplitudes of the {gamma}-ray events, while their millimeter-wave polarization is related to the optical polarization during the outbursts. We interpret the multi-frequency behavior within models involving either a system of standing conical shocks or magnetic reconnection events located in the parsec-scale millimeter-wave core of the jet. We argue that {gamma}-ray outbursts with variability timescales as short as {approx}3 hr can occur on parsec scales if flares take place in localized regions such as turbulent cells.« less

Time correlation between the radio and gamma-ray activity in blazars and the production site of the gamma-ray emission

DOE PAGES

Max-Moerbeck, W.; Hovatta, T.; Richards, J. L.; ...

2014-09-22

In order to determine the location of the gamma-ray emission site in blazars, we investigate the time-domain relationship between their radio and gamma-ray emission. Light-curves for the brightest detected blazars from the first 3 years of the mission of the Fermi Gamma-ray Space Telescope are cross-correlated with 4 years of 15GHz observations from the OVRO 40-m monitoring program. The large sample and long light-curve duration enable us to carry out a statistically robust analysis of the significance of the cross-correlations, which is investigated using Monte Carlo simulations including the uneven sampling and noise properties of the light-curves. Modeling the light-curvesmore » as red noise processes with power-law power spectral densities, we find that only one of 41 sources with high quality data in both bands shows correlations with significance larger than 3σ (AO0235+164), with only two more larger than even 2.25σ (PKS 1502+106 and B2 2308+34). Additionally, we find correlated variability in Mrk 421 when including a strong flare that occurred in July-September 2012. These results demonstrate very clearly the difficulty of measuring statistically robust multiwavelength correlations and the care needed when comparing light-curves even when many years of data are used. This should be a caution. In all four sources the radio variations lag the gamma-ray variations, suggesting that the gamma-ray emission originates upstream of the radio emission. Continuous simultaneous monitoring over a longer time period is required to obtain high significance levels in cross-correlations between gamma-ray and radio variability in most blazars.« less

{gamma}-RAY AND PARSEC-SCALE JET PROPERTIES OF A COMPLETE SAMPLE OF BLAZARS FROM THE MOJAVE PROGRAM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lister, M. L.; Hovatta, T.; Aller, M.

We investigate the Fermi Large Area Telescope {gamma}-ray and 15 GHz Very Long Baseline Array radio properties of a joint {gamma}-ray and radio-selected sample of active galactic nuclei (AGNs) obtained during the first 11 months of the Fermi mission (2008 August 4-2009 July 5). Our sample contains the brightest 173 AGNs in these bands above declination -30 Degree-Sign during this period, and thus probes the full range of {gamma}-ray loudness ({gamma}-ray to radio band luminosity ratio) in the bright blazar population. The latter quantity spans at least 4 orders of magnitude, reflecting a wide range of spectral energy distribution (SED)more » parameters in the bright blazar population. The BL Lac objects, however, display a linear correlation of increasing {gamma}-ray loudness with synchrotron SED peak frequency, suggesting a universal SED shape for objects of this class. The synchrotron self-Compton model is favored for the {gamma}-ray emission in these BL Lac objects over external seed photon models, since the latter predict a dependence of Compton dominance on Doppler factor that would destroy any observed synchrotron SED-peak-{gamma}-ray-loudness correlation. The high-synchrotron peaked (HSP) BL Lac objects are distinguished by lower than average radio core brightness temperatures, and none display large radio modulation indices or high linear core polarization levels. No equivalent trends are seen for the flat-spectrum radio quasars (FSRQs) in our sample. Given the association of such properties with relativistic beaming, we suggest that the HSP BL Lac objects have generally lower Doppler factors than the lower-synchrotron peaked BL Lac objects or FSRQs in our sample.« less

RoboPol: first season rotations of optical polarization plane in blazars

DOE PAGES

Blinov, D.; Pavlidou, V.; Papadakis, I.; ...

2015-08-26

Here, we present first results on polarization swings in optical emission of blazars obtained by RoboPol, a monitoring programme of an unbiased sample of gamma-ray bright blazars specially designed for effective detection of such events. A possible connection of polarization swing events with periods of high activity in gamma-rays is investigated using the data set obtained during the first season of operation. It was found that the brightest gamma-ray flares tend to be located closer in time to rotation events, which may be an indication of two separate mechanisms responsible for the rotations. Blazars with detected rotations during non-rotating periodsmore » have significantly larger amplitude and faster variations of polarization angle than blazars without rotations. Our simulations show that the full set of observed rotations is not a likely outcome (probability ≤1.5 × 10 -2) of a random walk of the polarization vector simulated by a multicell model. Furthermore, it is highly unlikely (~5 × 10 -5) that none of our rotations is physically connected with an increase in gamma-ray activity.« less

FAST OPTICAL VARIABILITY OF A NAKED-EYE BURST-MANIFESTATION OF THE PERIODIC ACTIVITY OF AN INTERNAL ENGINE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beskin, G.; Karpov, S.; Bondar, S.

We imaged the position of the naked-eye burst, GRB080319B, before, during, and after its gamma-ray activity with sub-second temporal resolution using the TORTORA wide-field camera. The burst optical prompt emission, which reached 5.3 mag, has been detected, and its periodic optical variability has been discovered in the form of four equidistant flashes with a duration of several seconds. We also detected a strong correlation (r {approx} 0.82) between optical and gamma-ray light curves with a 2 s delay of the optical emission with respect to the gamma-ray emission. The revealed temporal structure of the optical light curve in comparison withmore » the gamma-ray light curve can be interpreted in the framework of the model of shell collisions in the ejecta containing a significant neutron component. All observed emission features reflect the non-stationary behavior of the burst internal engine-supposedly, a hyperaccreting solar-mass black hole formed in the collapse of a massive stellar core.« less

Synchrotron Radiation from Outer Space and the Chandra X-Ray Observatory

NASA Technical Reports Server (NTRS)

Weisskopf, M. C.

2006-01-01

The universe provides numerous extremely interesting astrophysical sources of synchrotron X radiation. The Chandra X-ray Observatory and other X-ray missions provide powerful probes of these and other cosmic X-ray sources. Chandra is the X-ray component of NASA's Great Observatory Program which also includes the Hubble Space telescope, the Spitzer Infrared Telescope Facility, and the now defunct Compton Gamma-Ray Observatory. The Chandra X-Ray Observatory provides the best angular resolution (sub-arcsecond) of any previous, current, or planned (for the foreseeable near future) space-based X-ray instrumentation. We present here a brief overview of the technical capability of this X-Ray observatory and some of the remarkable discoveries involving cosmic synchrotron sources.

Observations with the High Altitude GAmma Ray (HAGAR) telescope array in the Indian Himalayas

NASA Astrophysics Data System (ADS)

Britto, R. J.; Acharya, B. S.; Anupama, G. C.; Bhatt, N.; Bhattacharjee, P.; Bhattacharya, S. S.; Chitnis, V. R.; Cowsik, R.; Dorji, N.; Duhan, S. K.; Gothe, K. S.; Kamath, P. U.; Koul, R.; Mahesh, P. K.; Mitra, A.; Nagesh, B. K.; Parmar, N. K.; Prabhu, T. P.; Rannot, R. C.; Rao, S. K.; Saha, L.; Saleem, F.; Saxena, A. K.; Sharma, S. K.; Shukla, A.; Singh, B. B.; Srinivasan, R.; Srinivasulu, G.; Sudersanan, P. V.; Tickoo, A. K.; Tsewang, D.; Upadhya, S.; Vishwanath, P. R.; Yadav, K. K.

2010-12-01

For several decades, it was thought that astrophysical sources emit high energy photons within the energy range of the gamma-ray region of the electromagnetic spectrum also. These photons originate from interactions of high energy particles from sources involving violent phenomena in the Universe (supernovae, pulsars, Active Galactic Nuclei, etc.) with gas and radiation fields. Since the first reliable detections of cosmic gamma rays in the 1970's, improvements in instrumentation have led gamma-ray astronomy to an established branch of modern Astrophysics, with a constant increase in the number of detected sources. But the 30-300 GeV energy range remained sparsely explored until the launch of the Fermi space telescope in June 2008. The ground-based gamma-ray telescope array HAGAR is the first array of atmospheric Cherenkov telescopes established at a so high altitude (4270 m a.s.l.), and was designed to reach a relatively low energy threshold with quite a low mirror area (31 m^2). It is located at Hanle in India, in the Ladakh region of the Himalayas. Regular source observations have begun with the complete setup of 7 telescopes on Sept. 2008. We report and discuss our estimation of the systematics through dark region studies, and present preliminary results from gamma-ray sources in this paper.

Fermi-LAT Detection of Gravitational Lens Delayed Gamma-Ray Flares from Blazar B0218+357

NASA Technical Reports Server (NTRS)

Cheung, C. C.; Larsson, S.; Scargle, J. D.; Amin, M. A.; Blandford, R. D.; Bulmash, D.; Chiang, J.; Ciprini, S.; Corbet, R. D. H.; Falco, E. E.;

TEMPORAL CORRELATIONS BETWEEN OPTICAL AND GAMMA-RAY ACTIVITY IN BLAZARS

DOE PAGES

Cohen, Daniel P.; Romani, Roger W.; Filippenko, Alexei V.; ...

2014-12-08

For this research, we have been using the 0.76 m Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory to optically monitor a sample of 157 blazars that are bright in gamma-rays being detected with high significance (≥10σ) in one year by the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. We attempt to observe each source on a three-day cadence with KAIT, subject to weather and seasonal visibility. The gamma-ray coverage is essentially continuous. KAIT observations extend over much of the five-year Fermi mission for several objects, and most have >100 optical measurements spanning the last three years.more » These blazars (flat-spectrum radio quasars and BL Lac objects) exhibit a wide range of flaring behavior. Using the discrete correlation function (DCF), here we search for temporal relationships between optical and gamma-ray light curves in the 40 brightest sources in hopes of placing constraints on blazar acceleration and emission zones. We find strong optical-gamma-ray correlation in many of these sources at time delays of ~1 to ~10 days, ranging between –40 and +30 days. A stacked average DCF of the 40 sources verifies this correlation trend, with a peak above 99% significance indicating a characteristic time delay consistent with 0 days. These findings strongly support the widely accepted leptonic models of blazar emission. However, we also find examples of apparently uncorrelated flares (optical flares with no gamma-ray counterpart and gamma-ray flares with no optical counterpart) that challenge simple, one-zone models of blazar emission. Moreover, we find that flat-spectrum radio quasars tend to have gamma-rays leading the optical, while intermediate- and high-synchrotron peak blazars with the most significant peaks have smaller lags/leads. In conclusion, it is clear that long-term monitoring at high cadence is necessary to reveal the underlying physical correlation.« less

Simulating Gamma-Ray Emission in Star-forming Galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pfrommer, Christoph; Pakmor, Rüdiger; Simpson, Christine M.

Star-forming galaxies emit GeV and TeV gamma-rays that are thought to originate from hadronic interactions of cosmic-ray (CR) nuclei with the interstellar medium. To understand the emission, we have used the moving-mesh code Arepo to perform magnetohydrodynamical galaxy formation simulations with self-consistent CR physics. Our galaxy models exhibit a first burst of star formation that injects CRs at supernovae. Once CRs have sufficiently accumulated in our Milky Way–like galaxy, their buoyancy force overcomes the magnetic tension of the toroidal disk field. As field lines open up, they enable anisotropically diffusing CRs to escape into the halo and to accelerate amore » bubble-like, CR-dominated outflow. However, these bubbles are invisible in our simulated gamma-ray maps of hadronic pion-decay and secondary inverse-Compton emission because of low gas density in the outflows. By adopting a phenomenological relation between star formation rate (SFR) and far-infrared emission and assuming that gamma-rays mainly originate from decaying pions, our simulated galaxies can reproduce the observed tight relation between far-infrared and gamma-ray emission, independent of whether we account for anisotropic CR diffusion. This demonstrates that uncertainties in modeling active CR transport processes only play a minor role in predicting gamma-ray emission from galaxies. We find that in starbursts, most of the CR energy is “calorimetrically” lost to hadronic interactions. In contrast, the gamma-ray emission deviates from this calorimetric property at low SFRs due to adiabatic losses, which cannot be identified in traditional one-zone models.« less

Simulating Gamma-Ray Emission in Star-forming Galaxies

NASA Astrophysics Data System (ADS)

Pfrommer, Christoph; Pakmor, Rüdiger; Simpson, Christine M.; Springel, Volker

2017-10-01

Star-forming galaxies emit GeV and TeV gamma-rays that are thought to originate from hadronic interactions of cosmic-ray (CR) nuclei with the interstellar medium. To understand the emission, we have used the moving-mesh code Arepo to perform magnetohydrodynamical galaxy formation simulations with self-consistent CR physics. Our galaxy models exhibit a first burst of star formation that injects CRs at supernovae. Once CRs have sufficiently accumulated in our Milky Way-like galaxy, their buoyancy force overcomes the magnetic tension of the toroidal disk field. As field lines open up, they enable anisotropically diffusing CRs to escape into the halo and to accelerate a bubble-like, CR-dominated outflow. However, these bubbles are invisible in our simulated gamma-ray maps of hadronic pion-decay and secondary inverse-Compton emission because of low gas density in the outflows. By adopting a phenomenological relation between star formation rate (SFR) and far-infrared emission and assuming that gamma-rays mainly originate from decaying pions, our simulated galaxies can reproduce the observed tight relation between far-infrared and gamma-ray emission, independent of whether we account for anisotropic CR diffusion. This demonstrates that uncertainties in modeling active CR transport processes only play a minor role in predicting gamma-ray emission from galaxies. We find that in starbursts, most of the CR energy is “calorimetrically” lost to hadronic interactions. In contrast, the gamma-ray emission deviates from this calorimetric property at low SFRs due to adiabatic losses, which cannot be identified in traditional one-zone models.

DISCOVERY OF A PSEUDOBULGE GALAXY LAUNCHING POWERFUL RELATIVISTIC JETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kotilainen, Jari K.; Olguín-Iglesias, Alejandro; León-Tavares, Jonathan

Supermassive black holes launching plasma jets at close to the speed of light, producing gamma-rays, have ubiquitously been found to be hosted by massive elliptical galaxies. Since elliptical galaxies are generally believed to be built through galaxy mergers, active galactic nuclei (AGN) launching relativistic jets are associated with the latest stages of galaxy evolution. We have discovered a pseudobulge morphology in the host galaxy of the gamma-ray AGN PKS 2004-447. This is the first gamma-ray emitter radio-loud AGN found to have been launched from a system where both the black hole and host galaxy have been actively growing via secularmore » processes. This is evidence of an alternative black hole–galaxy co-evolutionary path to develop powerful relativistic jets, which is not merger driven.« less

[Induction of glutathione and activation of immune functions by low-dose, whole-body irradiation with gamma-rays].

PubMed

Kojima, Shuji

2006-10-01

We first examined the relation between the induction of glutathione and immune functions in mice after low-dose gamma-ray irradiation. Thereafter, inhibition of tumor growth by radiation was confirmed in Ehrlich solid tumor (EST)-bearing mice. The total glutathione level of the splenocytes transiently increased soon after irradiation and reached a maximum at around 4 h postirradiation. Thereafter, the level reverted to the 0 h value by 24 h postirradiation. A significantly high splenocyte proliferative response was also recognized 4 h postirradiation. Natural killer (NK) activity was also increased significantly in a similar manner. The time at which the response reached the maximum coincided well with that of maximum total glutathione levels of the splenocytes in the gamma-ray-irradiated mice. Reduced glutathione exogenously added to splenocytes obtained from normal mice enhanced the proliferative response and NK activity in a dose-dependent manner. The inhibitory effects of radiation on tumor growth was then examined in EST-bearing mice. Repeated low-dose irradiation (0.5 Gy, four times, before and within an early time after inoculation) significantly delayed the tumor growth. Finally, the effect of single low-dose (0.5 Gy), whole-body gamma-ray irradiation on immune balance was examined to elucidate the mechanism underlying the antitumor immunity. The percentage of B cells in blood lymphocytes was selectively decreased after radiation, concomitant with an increase in that of the helper T cell population. The IFN-gamma level in splenocyte culture prepared from EST-bearing mice was significantly increased 48 h after radiation, although the level of IL-4 was unchanged. IL-12 secretion from macrophages was also enhanced by radiation. These results suggest that low-dose gamma-rays induce Th1 polarization and enhance the activities of tumoricidal effector cells, leading to an inhibition of tumor growth.

Gamma-ray Full Spectrum Analysis for Environmental Radioactivity by HPGe Detector

NASA Astrophysics Data System (ADS)

Jeong, Meeyoung; Lee, Kyeong Beom; Kim, Kyeong Ja; Lee, Min-Kie; Han, Ju-Bong

2014-12-01

Odyssey, one of the NASA¡¯s Mars exploration program and SELENE (Kaguya), a Japanese lunar orbiting spacecraft have a payload of Gamma-Ray Spectrometer (GRS) for analyzing radioactive chemical elements of the atmosphere and the surface. In these days, gamma-ray spectroscopy with a High-Purity Germanium (HPGe) detector has been widely used for the activity measurements of natural radionuclides contained in the soil of the Earth. The energy spectra obtained by the HPGe detectors have been generally analyzed by means of the Window Analysis (WA) method. In this method, activity concentrations are determined by using the net counts of energy window around individual peaks. Meanwhile, an alternative method, the so-called Full Spectrum Analysis (FSA) method uses count numbers not only from full-absorption peaks but from the contributions of Compton scattering due to gamma-rays. Consequently, while it takes a substantial time to obtain a statistically significant result in the WA method, the FSA method requires a much shorter time to reach the same level of the statistical significance. This study shows the validation results of FSA method. We have compared the concentration of radioactivity of 40K, 232Th and 238U in the soil measured by the WA method and the FSA method, respectively. The gamma-ray spectrum of reference materials (RGU and RGTh, KCl) and soil samples were measured by the 120% HPGe detector with cosmic muon veto detector. According to the comparison result of activity concentrations between the FSA and the WA, we could conclude that FSA method is validated against the WA method. This study implies that the FSA method can be used in a harsh measurement environment, such as the gamma-ray measurement in the Moon, in which the level of statistical significance is usually required in a much shorter data acquisition time than the WA method.

KSC-08pd1359

NASA Image and Video Library

2008-05-14

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility, technicians lower NASA's Gamma-Ray Large Area Space Telescope, or GLAST, spacecraft toward the payload attach fitting. The fitting will eventually be used to mate GLAST to the Delta II launch vehicle. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date still is to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1358

NASA Image and Video Library

2008-05-14

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility, technicians lower NASA's Gamma-Ray Large Area Space Telescope, or GLAST, spacecraft toward the payload attach fitting. The fitting will eventually be used to mate GLAST to the Delta II launch vehicle. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date still is to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1360

NASA Image and Video Library

2008-05-14

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility, technicians check the placement of NASA's Gamma-Ray Large Area Space Telescope, or GLAST, spacecraft on the payload attach fitting. The fitting will eventually be used to mate GLAST to the Delta II launch vehicle. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date still is to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1352

NASA Image and Video Library

2008-05-14

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility, NASA's Gamma-Ray Large Area Space Telescope, or GLAST, spacecraft is being prepared for a move to an payload attach fitting that will eventually be used to mate GLAST to the Delta II launch vehicle. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date still is to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1354

NASA Image and Video Library

2008-05-14

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility, NASA's Gamma-Ray Large Area Space Telescope, or GLAST, spacecraft will be installed on this payload attach fitting that will eventually be mated to the Delta II launch vehicle. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date still is to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1356

NASA Image and Video Library

2008-05-14

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility, technicians prepare the payload attach fitting that will receive NASA's Gamma-Ray Large Area Space Telescope, or GLAST, spacecraft. The fitting will eventually be used to mate GLAST to the Delta II launch vehicle. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date still is to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1361

NASA Image and Video Library

2008-05-14

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility, technicians check the attachment of NASA's Gamma-Ray Large Area Space Telescope, or GLAST, spacecraft on the payload attach fitting. The fitting will eventually be used to mate GLAST to the Delta II launch vehicle. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date still is to be determined. Photo credit: NASA/Jim Grossmann

KSC-08pd1355

NASA Image and Video Library

2008-05-14

CAPE CANAVERAL, Fla. -- At the Astrotech payload processing facility, technicians prepare NASA's Gamma-Ray Large Area Space Telescope, or GLAST, spacecraft for its move to the payload attach fitting that will eventually be used to mate GLAST to the Delta II launch vehicle. The GLAST is a powerful space observatory that will explore the Universe's ultimate frontier, where nature harnesses forces and energies far beyond anything possible on Earth; probe some of science's deepest questions, such as what our Universe is made of, and search for new laws of physics; explain how black holes accelerate jets of material to nearly light speed; and help crack the mystery of stupendously powerful explosions known as gamma-ray bursts. A launch date still is to be determined. Photo credit: NASA/Jim Grossmann

Spent Fuel Assay with an Ultra-High Rate HPGe Spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fast, James; Fulsom, Bryan; Pitts, Karl

2015-07-01

Traditional verification of spent nuclear fuel (SNF) includes determination of initial enrichment, burnup and cool down time (IE, BU, CT). Along with neutron measurements, passive gamma assay provides important information for determining BU and CT. Other gamma-ray-based assay methods such as passive tomography and active delayed gamma offer the potential to measure the spatial distribution of fission products and the fissile isotopic concentration of the fuel, respectively. All fuel verification methods involving gamma-ray spectroscopy require that the spectrometers manage very high count rates while extracting the signatures of interest. PNNL has developed new digital filtering and analysis techniques to producemore » an ultra-high rate gamma-ray spectrometer from a standard coaxial high-purity germanium (HPGe) crystal. This 37% relative efficiency detector has been operated for SNF measurements at input count rates of 500-1300 kcps and throughput in excess of 150 kcps. Optimized filtering algorithms preserve the spectroscopic capability of the system even at these high rates. This paper will present the results of both passive and active SNF measurement performed with this system at PNNL. (authors)« less

Evaluation of RayXpert® for shielding design of medical facilities

NASA Astrophysics Data System (ADS)

Derreumaux, Sylvie; Vecchiola, Sophie; Geoffray, Thomas; Etard, Cécile

2017-09-01

In a context of growing demands for expert evaluation concerning medical, industrial and research facilities, the French Institute for radiation protection and nuclear safety (IRSN) considered necessary to acquire new software for efficient dimensioning calculations. The selected software is RayXpert®. Before using this software in routine, exposure and transmission calculations for some basic configurations were validated. The validation was performed by the calculation of gamma dose constants and tenth value layers (TVL) for usual shielding materials and for radioisotopes most used in therapy (Ir-192, Co-60 and I-131). Calculated values were compared with results obtained using MCNPX as a reference code and with published values. The impact of different calculation parameters, such as the source emission rays considered for calculation and the use of biasing techniques, was evaluated.

A pulse shape discriminator and an online system for the balloon-borne hard X-ray/gamma-ray detector

NASA Astrophysics Data System (ADS)

Takahashi, T.; Kamae, T.; Tanaka, M.; Gunji, S.; Miyazuki, S.; Tamura, T.; Sekimoto, Y.; Yamaoka, N.; Nishimura, J.; Yajima, N.

Attention is given to a new kind of phoswich counters (the well-type phoswich counter) that will be capable of detecting very low flux hard X-rays/gamma-rays (40-1000 keV) from astronomical objects. A specially designed pulse-shape discriminator (PSD) selects hard X-rays/gamma-rays that has deposited energy only in the detection part. Sixty-four such counters are assembled into an array where each phoswich element acts as an active shield to the neighboring elements too. The ADCs, the TDCs, the hit-pattern latches, and the precision clock are read out by a VME-based online system, stored on an 8-mm video tape, and transmitted to the ground station. The design and performance of the pulse shape discriminator and the online system are described.

Recent Results on SNRs and PWNe from the Fermi Large Area Telescope

NASA Technical Reports Server (NTRS)

Hays, Elizabeth

2010-01-01

Topics include: Fermi LAT Collaboration groups; galactic results from LAT; a GeV, wide-field instrument; the 1FGL catalog, the Fermi LAT 1FGL source catalog, unidentified gamma-ray sources; variability in 1FGL sources; curvature in 1FGL sources; spectral-variability classification; pulsars and their wind nebulae; gamma-ray pulsars and MSPs; GeV PWN search; Crab pulsar and nebula; Vela X nebular of Vela pulsar; MSH 15-52; supernova remnants, resolved GeV sources, galactic transients, LAT unassociated transient detections; gamma rays from a nova; V407 Cyngi - a symbiotic nova; V407 Cygni: a variable star; and March 11 - a nova. Summary slides include pulsars everywhere, blazars, LAT as an electron detector, cosmic ray spectrum, the Large Area Telescope, the Fermi Observatory, LAT sensitivity with time, candidate gamma-ray events, on-orbit energy calibration and rate, a 1 year sky map, LAT automated science processing, reported GeV flares, early activity and spectacular flare, gamma-ray transients near the galactic plane , two early unassociated transients, counter part search - Fermi J0910-5404; counterpart search 3EG J0903-3531, and a new LAT transient - J1057-6027.

DISCOVERY OF A TRANSIENT GAMMA-RAY COUNTERPART TO FRB 131104

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeLaunay, J. J.; Murase, K.; Mészáros, P.

We report our discovery in Swift satellite data of a transient gamma-ray counterpart (3.2 σ confidence) to the fast radio burst (FRB) FRB 131104, the first such counterpart to any FRB. The transient has a duration T {sub 90} ≳ 100 s and a fluence S{sub γ} ≈ 4 × 10{sup −6} erg cm{sup −2}, increasing the energy budget for this event by more than a billion times; at the nominal z ≈ 0.55 redshift implied by its dispersion measure, the burst’s gamma-ray energy output is E{sub γ} ≈ 5 × 10{sup 51} erg. The observed radio to gamma-ray fluencemore » ratio for FRB 131104 is consistent with a lower limit we derive from Swift observations of another FRB, which is not detected in gamma-rays, and with an upper limit previously derived for the brightest gamma-ray flare from SGR 1806−20, which was not detected in the radio. X-ray, ultraviolet, and optical observations beginning two days after the FRB do not reveal any associated afterglow, supernova, or transient; Swift observations exclude association with the brightest 65% of Swift gamma-ray burst (GRB) X-ray afterglows, while leaving the possibility of an associated supernova at much more than 10% the FRB’s nominal distance, D ≳ 320 Mpc, largely unconstrained. Transient high-luminosity gamma-ray emission arises most naturally in a relativistic outflow or shock breakout, such as, for example, from magnetar flares, GRBs, relativistic supernovae, and some types of galactic nuclear activity. Our discovery thus bolsters the case for an extragalactic origin for some FRBs and suggests that future rapid-response observations might identify long-lived counterparts, resolving the nature of these mysterious phenomena and realizing their promise as probes of cosmology and fundamental physics.« less

Gamma bang time/reaction history diagnostics for the National Ignition Facility using 90 degrees off-axis parabolic mirrors.

PubMed

Malone, R M; Herrmann, H W; Stoeffl, W; Mack, J M; Young, C S

2008-10-01

Gas Cherenkov detectors (GCDs) have been used to convert fusion gamma into photons to achieve gamma bang time and reaction history measurements. The GCDs designed for OMEGA used Cassegrain reflector optics in order to fit inside a 10 in. manipulator. A novel design for the National Ignition Facility using 90 degrees off-axis parabolic mirrors will increase light collection efficiency from fusion gammas and achieve minimum time dispersion. The broadband Cherenkov light (from 200 to 800 nm) is relayed into a high-speed detector using three parabolic mirrors. Because light is collected from many source planes throughout the CO(2) gas volume, the detector is positioned at the stop position rather than at an image position. The stop diameter and its position are independent of the light-generation location along the gas cell. The current design collects light from a 100 mm diameter by 500 mm long gas volume. Optical ray tracings demonstrate how light can be collected from different angled trajectories of the Compton electrons as they fly through the CO(2) gas volume. A cluster of four channels will allow for increased dynamic range as well as for different gamma energy threshold sensitivities.

Neutron Capture Gamma-Ray Libraries for Nuclear Applications

NASA Astrophysics Data System (ADS)

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

2011-06-01

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

Characterization of non-CG genomic hypomethylation associated with gamma-ray-induced suppression of CMT3 transcription in Arabidopsis thaliana.

PubMed

Kim, Ji Eun; Lee, Min Hee; Cho, Eun Ju; Kim, Ji Hong; Chung, Byung Yeoup; Kim, Jin-Hong

2013-12-01

Ionizing radiation causes various epigenetic changes, as well as a variety of DNA lesions such as strand breaks, cross-links, oxidative damages, etc., in genomes. However, radiation-induced epigenetic changes have rarely been substantiated in plant genomes. The current study investigates whether DNA methylation of Arabidopsis thaliana genome is altered by gamma rays. We found that genomic DNA methylation decreased in wild-type plants with increasing doses of gamma rays (5, 50 and 200 Gy). Irradiation with 200 Gy significantly increased the expression of transcriptionally inactive centromeric 180-bp (CEN) and transcriptionally silent information (TSI) repeats. This increase suggested that there was a substantial release of transcriptional gene silencing by gamma rays, probably by induction of DNA hypomethylation. High expression of the DNA demethylase ROS1 and low expression of the DNA methyltransferase CMT3 supported this hypothesis. Moreover, Southern blot analysis following digestion of genomic DNA with methylation-sensitive enzymes revealed that the DNA hypomethylation occured preferentially at CHG or CHH sites rather than CG sites, depending on the radiation dose. Unlike CEN and TSI repeats, the number of Ta3, AtSN1 and FWA repeats decreased in transcription but increased in non-CG methylation. In addition, the cmt3-11 mutant showed neither DNA hypomethylation nor transcriptional activation of silenced repeats upon gamma irradiation. Furthermore, profiles of genome-wide transcriptomes in response to gamma rays differed between the wild-type and cmt3-11 mutant. These results suggest that gamma irradiation induced DNA hypomethylation preferentially at non-CG sites of transcriptionally inactive repeats in a locus-specific manner, which depends on CMT3 activity.

Can Winds Driven by Active Galactic Nuclei Account for the Extragalactic Gamma-Ray and Neutrino Backgrounds?

NASA Astrophysics Data System (ADS)

Liu, Ruo-Yu; Murase, Kohta; Inoue, Susumu; Ge, Chong; Wang, Xiang-Yu

2018-05-01

Various observations are revealing the widespread occurrence of fast and powerful winds in active galactic nuclei (AGNs) that are distinct from relativistic jets, likely launched from accretion disks and interacting strongly with the gas of their host galaxies. During the interaction, strong shocks are expected to form that can accelerate nonthermal particles to high energies. Such winds have been suggested to be responsible for a large fraction of the observed extragalactic gamma-ray background (EGB) and the diffuse neutrino background, via the decay of neutral and charged pions generated in inelastic pp collisions between protons accelerated by the forward shock and the ambient gas. However, previous studies did not properly account for processes such as adiabatic losses that may reduce the gamma-ray and neutrino fluxes significantly. We evaluate the production of gamma rays and neutrinos by AGN-driven winds in detail by modeling their hydrodynamic and thermal evolution, including the effects of their two-temperature structure. We find that they can only account for less than ∼30% of the EGB flux, as otherwise the model would violate the independent upper limit derived from the diffuse isotropic gamma-ray background. If the neutrino spectral index is steep with Γ ≳ 2.2, a severe tension with the isotropic gamma-ray background would arise as long as the winds contribute more than 20% of the IceCube neutrino flux in the 10–100 TeV range. At energies ≳ 100 TeV, we find that the IceCube neutrino flux may still be accountable by AGN-driven winds if the spectral index is as small as Γ ∼ 2.0–2.1.

All-Sky Earth Occultation Observations with the Fermi Gamma-Ray Burst Monitor

NASA Technical Reports Server (NTRS)

Wilson-Hodge, C. A.; Beklen, E.; Bhat, P. N.; Briggs, M.; Camero-Arranz, A.; Case, G.; Jenke, P.; Chaplin, V.; Cherry, M.; Connaughton, V.;

SEARCHING FOR NEW {gamma}-RAY BLAZAR CANDIDATES IN THE THIRD PALERMO BAT HARD X-RAY CATALOG WITH WISE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maselli, A.; Cusumano, G.; La Parola, V.

We searched for {gamma}-ray blazar candidates among the 382 unidentified hard X-ray sources of the third Palermo BAT Catalog (3PBC) obtained from the analysis of 66 months of Swift Burst Alert Telescope (BAT) survey data and listing 1586 sources. We adopted a recently developed association method based on the peculiar infrared colors that characterize the {gamma}-ray blazars included in the second catalog of active galactic nuclei detected by the Fermi Large Area Telescope. We used this method exploiting the data of the all-sky survey performed by the Wide-field Infrared Survey Explorer (WISE) to establish correspondences between unidentified 3PBC sources andmore » WISE {gamma}-ray blazar candidates located within the BAT positional uncertainty region at a 99% confidence level. We obtained a preliminary list of candidates for which we analyzed all the available data in the Swift archive to complement the information in the literature and in the radio, infrared, and optical catalogs with the information on their optical-UV and soft X-ray emission. Requiring the presence of radio and soft X-ray counterparts consistent with the infrared positions of the selected WISE sources, as well as a blazar-like radio morphology, we finally obtained a list of 24 {gamma}-ray blazar candidates.« less

Direct measurement of 235U in spent fuel rods with Gamma-ray mirrors

NASA Astrophysics Data System (ADS)

Ruz, J.; Brejnholt, N. F.; Alameda, J. B.; Decker, T. A.; Descalle, M. A.; Fernandez-Perea, M.; Hill, R. M.; Kisner, R. A.; Melin, A. M.; Patton, B. W.; Soufli, R.; Ziock, K.; Pivovaroff, M. J.

2015-03-01

Direct measurement of plutonium and uranium X-rays and gamma-rays is a highly desirable non-destructive analysis method for the use in reprocessing fuel environments. The high background and intense radiation from spent fuel make direct measurements difficult to implement since the relatively low activity of uranium and plutonium is masked by the high activity from fission products. To overcome this problem, we make use of a grazing incidence optic to selectively reflect Kα and Kβ fluorescence of Special Nuclear Materials (SNM) into a high-purity position-sensitive germanium detector and obtain their relative ratios.

Evaluation of the Environmental Gamma-ray Dose Rate by Skyshine Analysis During the Maintenance of an Activated TFC in ITER

NASA Astrophysics Data System (ADS)

Sato, S.; Takatsu, H.; Maki, K.; Yamada, K.; Mori, S.; Iida, H.; Santoro, R. T.

1997-09-01

Gamma-ray exposure dose rates at the ITER site boundary were estimated for the cases of removal of a failed activated Toroidal Field (TF) coil from the torus and removal of a failed activated TF coil together with a sector of the activated Vacuum Vessel (VV). Skyshine analyses were performed using the two-dimensional SN radiation transport code, DOT3.5. The exposure gamma-ray dose rates on the ground at the site boundary (presently assumed to be 1 km from the ITER building), were calculated to be 1.1 and 84 μSv/year for removal of the TF coil without and with a VV sector, respectively. The dose rate level for the latter case is close to the tentative radiation limit of 100 μSv/year so an additional ˜14 cm of concrete is required in the ITER building roof to satisfy the criterion for a safety factor often for the site boundary dose rate.

7th International Fermi Symposium

NASA Astrophysics Data System (ADS)

2017-10-01

The two Fermi instruments have been surveying the high-energy sky since August 2008. The Large Area Telescope (LAT) has discovered more than three thousand gamma-ray sources and many new source classes, bringing the importance of gamma-ray astrophysics to an ever-broadening community. The LAT catalog includes supernova remnants, pulsar wind nebulae, pulsars, binary systems, novae, several classes of active galaxies, starburst galaxies, normal galaxies, and a large number of unidentified sources. Continuous monitoring of the high-energy gamma-ray sky has uncovered numerous outbursts from a wide range of transients. Fermi LAT's study of diffuse gamma-ray emission in our Galaxy revealed giant bubbles, as well as an excess of gamma-rays from the Galactic center region, both observations have become exciting puzzles for the astrophysics community. The direct measurement of a harder-than- expected cosmic-ray electron spectrum may imply the presence of nearby cosmic-ray accelerators. LAT data have provided stringent constraints on new phenomena such as supersymmetric dark-matter annihilations as well as tests of fundamental physics. The full reprocessing of the entire mission dataset with Pass 8 includes improved event reconstruction, a wider energy range, better energy measurements, and significantly increased effective area, all them boosting the discovery potential and the ability to do precision observations with LAT. The Gamma-ray Burst Monitor (GBM) continues to be a prolific detector of gamma-ray transients: magnetars, solar flares, terrestrial gamma-ray flashes and gamma-ray bursts at keV to MeV energies, complementing the higher energy LAT observations of those sources in addition to providing valuable science return in their own right. All gamma-ray data are made immediately available at the Fermi Science Support Center (http://fermi.gsfc.nasa.gov/ssc). These publicly available data and Fermi analysis tools have enabled a large number of important studies. We especially encourage guest investigators worldwide to participate in this symposium to share results and to learn about upcoming opportunities. This meeting will focus on the new scientific investigations and results enabled by Fermi, the mission and instrument characteristics, future opportunities, coordinated observations and analysis techniques. In particular, we also encourage discussion of future prospects/science with Fermi in preparation for the upcoming NASA senior review. Details on the 7th International Fermi Symposium can be found here: https://events.mpe.mpg.de/Fermi2017

In-situ petrophysical properties of hotspot volcanoes. Results from ODP Leg 197, Detroit Seamount and HSDP II borehole, Hawaii

NASA Astrophysics Data System (ADS)

Kock, I.; Pechnig, R.; Buysch, A.; Clauser, C.

2003-04-01

During ODP Leg 197 an extensive logging program was run on Site 1203, Detroit Seamount. This seamount is part of the Emperor seamount chain, a continuation of the Hawaiian volcanic chain. Standard ODP/LDEO logging tool strings were used to measure porosity, density, resistivity, p- and s-wave velocities and gamma ray activity. The FMS-tool yielded detailed high resolution resistivity images of the borehole wall. By interpretation and statistical analysis of the logging parameters a petrophysical classification of the drilled rock content could be derived. The pillow lava recovered in the cores exhibits low porosity, low resistivity and high density. This indicates no or very little vesicles in the non-fractured rock unit. Compared to the pillow basalts, subaerial basalts show increasing porosity, gamma ray and potassium content and decreasing density, resistivity and velocity. A basalt with no or little vesicles and a basalt with average or many vesicles can clearly be distinguished. The volcaniclastics show lower resistivity, lower sonic velocities, higher porosities and lower densities than the basalts. Three different rock types can be distinguished within the volcaniclastics: Tuffs, resedimented tephra and breccia. The tuff shows medium porosity and density, low gamma ray and potassium content. The log responses from the resedimented tephra suggest that the tephra is more easily altered than the tuff. The log responses from the breccia lie between the tuff and tephra log responses, but the breccia can clearly be identified in the FMS borehole images. A similar rock content was found in the Hawaiian Scientific Drilling Project borehole. Gamma ray activity, electrical resistivity and sonic velocity were measured down to 2700 mbsl.. Compared to the 72-76 Ma old Detroit seamount basalts, the HSDP subaerial and submarine lava flows show a significant lower gamma ray activity, while sonic velocity and electrical resistivity are comparable. Deviations between the gamma ray activity might be due to the different primary compositions of the melt or to long lasting low temperature alteration. Investigations on this topic are in progress.

Beta- and gamma-dose measurements of the Godiva IV critical assembly.

PubMed

Hankins, D E

1984-03-01

To aid in the re-evaluation of an exposure that occurred in 1963, information was required on the response of film badges to the beta- and gamma-ray doses from a critical assembly. Of particular interest was the beta spectra from the assembly. The techniques used and the results obtained in this study are of interest to health physicists at facilities where exposures to betas occur. The dose rates from the Los Alamos National Laboratory Godiva IV Critical Assembly were measured at numerous distances from the assembly four and 12 days following a burst. Information was obtained on the beta-particle spectra using absorption curve studies. The beta/gamma dose-rate ratio as a function of distance from the assembly was determined. Shielding provided by various metals, gloves and clothing was measured. The beta- and gamma-ray doses measured were compared with a film packet used in the past at the Nevada Test Site with two types of current TLD personnel badges. Measurements made with a commercial thin-window ion chamber instrument are compared with the dose rates obtained using other dosimeters.

Gamma rays from active galactic nuclei

NASA Technical Reports Server (NTRS)

Kazanas, Demosthenes

1990-01-01

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

Basics of Gamma Ray Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stinnett, Jacob; Venkataraman, Ram

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

Planetary Geochemistry Techniques: Probing In-Situ with Neutron and Gamma Rays (PING) Instrument

NASA Technical Reports Server (NTRS)

Parsons, A.; Bodnarik, J.; Burger, D.; Evans, L.; Floyd, S.; Lin, L.; McClanahan, T.; Nankung, M.; Nowicki, S.; Schweitzer, J.;

Limits on the Emission of Gamma Rays from M31 (The Andromeda Galaxy) with HAWC

NASA Astrophysics Data System (ADS)

Rubenzahl, Ryan; BenZvi, Segev; Wood, Joshua; HAWC Collaboration

2018-01-01

The detection of the Fermi Bubbles suggests that spiral galaxies such as the Milky Way can undergo active periods. Using gamma-ray observations, we can investigate the possibility that such structures are present in other nearby galaxies. We have analyzed the region around the Andromeda Galaxy (Messier Catalog M31) for signs of bubble-like emission using TeV gamma-ray data recorded by the High-Altitude Water Cherenkov Observatory. We fit a model consisting of two 6 kpc bubbles symmetric about and perpendicular to the M31 galactic plane and assume a power-law distribution for the gamma-ray flux. We compare the emission from these bubble regions to that expected from structures similar to the Fermi Bubbles found in the Milky Way. No significant emission was observed. We report upper limits on the TeV flux from Fermi Bubble structures in M31.

Near-infrared and gamma-ray monitoring of TANAMI gamma-ray bright sources

DOE PAGES

Nesci, R.; Tosti, G.; Pursimo, T.; ...

2013-06-18

Context. We present that spectral energy distribution and its variability are basic tools for understanding the physical processes operating in active galactic nuclei (AGN). Aims. In this paper we report the results of a one-year near-infrared (NIR) and optical monitoring of a sample of 22 AGN known to be gamma-ray emitters, aimed at discovering correlations between optical and gamma-ray emission. Methods. We observed our objects with the Rapid Eye Mount (REM) telescope in J,H,K, and R bands nearly twice every month during their visibility window and derived light curves and spectral indexes. We also analyzed the gamma-ray data from themore » Fermi gamma-ray Space Telescope, making weekly averages. Results. Six sources were never detected during our monitoring, proving to be fainter than their historical Two micron all sky survey (2MASS) level. All of the sixteen detected sources showed marked flux density variability, while the spectral indexes remained unchanged within our sensitivity limits. Steeper sources showed, on average, a larger variability. From the NIR light curves we also computed a variability speed index for each detected source. Only one source (PKS 0208-512) underwent an NIR flare during our monitoring. Half of the sources showed a regular flux density trend on a one-year time scale, but do not show any other peculiar characteristic. The broadband spectral index α ro appears to be a good proxy of the NIR spectral index only for BL Lac objects. No clear correlation between NIR and gamma-ray data is evident in our data, save for PKS 0537-441, PKS 0521-360, PKS 2155-304, and PKS 1424-418. In conclusion, the gamma-ray/NIR flux ratio showed a large spread, QSO being generally gamma-louder than BL Lac, with a marked correlation with the estimated peak frequency (ν peak) of the synchrotron emission.« less

Gamma-Radiation-Induced Degradation of Actively Pumped Single-Mode Ytterbium-Doped Optical Laser - Postprint

DTIC Science & Technology

2015-01-01

evaluated using the cobalt (Co)-60 gamma irradiation facility at The Ohio State University. A radiation dose rate of 43 krad(Si)/hr was used to expose the...Table 1. Description of the optical fibers used for in-situ analysis of the radiation damage Optical fiber Core Dopant Core/cladding diameters (μm...University is a pool-type gamma irradiation facility using a common cobalt cylindrical rod irradiator submerged 20 feet into a water tank. A

Some gamma-ray shielding measurements made at altitudes greater than 115000 feet using large Ge(Li) detectors

NASA Technical Reports Server (NTRS)

Chapman, G. T.; Cumby, R. P.; Gibbons, J. H.; Macklin, R. L.; Parker, H. W.

1972-01-01

A series of balloon-flight experiments at altitudes greater than 115,000 feet were conducted to gain information relative to the use of composite shields (passive and/or active) for shielding large-volume, lithium-drifted, germanium (Ge(Li)) detectors used in gamma-ray spectrometers. Data showing the pulse-height spectra of the environmental gamma radiation as measured at 5.3 and 3.8 gms sq cm residual atmosphere with an unshielded diode detector are also presented.

Multi-Wavelength Observations of the Soft Gamma Repeater SGR 1900+14 During its April 2001 Activation

NASA Technical Reports Server (NTRS)

Kouveliotou, C.; Tennant, A. F.; Woods, P.; Hurley, K.; Fender, R. P.; Garrington, S. T.; Patel, S. K.; Gogus, E.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

The soft-gamma repeater SGR became active on 18 April 2001 after about a year of quiescence; it had remained at a very low state of activity since the fall of 1998, when it exhibited extraordinary flaring. We have observed the source in the gamma and X-rays with \\ulysses and \\chandra, and in the radio with MERLIN. We report here the confirmation of a two component X-ray spectrum (power law $+$ blackbody), indicating emission from the neutron star surface. We have determined that there is a dust halo surrounding the source that extends up to $\\gtrsim100^{\\prime\\prime}$ from the SGR center, which is due to the scattering in the Interstellar Medium.

Novel drift structures for silicon and compound semiconductor X-ray and gamma-ray detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patt, B.E.; Iwanczyk, J.S.

Recently developed silicon- and compound-semiconductor-based drift detector structures have produced excellent performance for charged particles, X-rays, and gamma rays and for low-signal visible light detection. The silicon drift detector (SDD) structures that the authors discuss relate to direct X-ray detectors and scintillation photon detectors coupled with scintillators for gamma rays. Recent designs include several novel features that ensure very low dark current and hence low noise. In addition, application of thin window technology ensures a very high quantum efficiency entrance window on the drift photodetector. The main features of the silicon drift structures for X rays and light detection aremore » very small anode capacitance independent of the overall detector size, low noise, and high throughput. To take advantage of the small detector capacitance, the first stage of the electronics needs to be integrated into the detector anode. In the gamma-ray application, factors other than electronic noise dominate, and there is no need to integrate the electronics into the anode. Thus, a different drift structure is needed in conjunction with a high-Z material. The main features in this case are large active detector volume and electron-only induced signal.« less

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

NASA Technical Reports Server (NTRS)

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.;

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

NASA Technical Reports Server (NTRS)

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.;

High energy gamma-ray astronomy; Proceedings of the International Conference, ANN Arbor, MI, Oct. 2-5, 1990

NASA Astrophysics Data System (ADS)

Matthews, James

The present volume on high energy gamma-ray astronomy discusses the composition and properties of heavy cosmic rays greater than 10 exp 12 eV, implications of the IRAS Survey for galactic gamma-ray astronomy, gamma-ray emission from young neutron stars, and high-energy diffuse gamma rays. Attention is given to observations of TeV photons at the Whipple Observatory, TeV gamma rays from millisecond pulsars, recent data from the CYGNUS experiment, and recent results from the Woomera Telescope. Topics addressed include bounds on a possible He/VHE gamma-ray line signal of Galactic dark matter, albedo gamma rays from cosmic ray interactions on the solar surface, source studies, and the CANGAROO project. Also discussed are neural nets and other methods for maximizing the sensitivity of a low-threshold VHE gamma-ray telescope, a prototype water-Cerenkov air-shower detector, detection of point sources with spark chamber gamma-ray telescopes, and real-time image parameterization in high energy gamma-ray astronomy using transputers. (For individual items see A93-25002 to A93-25039)

VizieR Online Data Catalog: 231 AGN candidates from the 2FGL catalog (Doert+, 2014)

NASA Astrophysics Data System (ADS)

Doert, M.; Errando, M.

2016-01-01

The second Fermi-LAT source catalog (2FGL; Nolan et al. 2012, cat. J/ApJS/199/31) is the deepest all-sky survey available in the gamma-ray band. It contains 1873 sources, of which 576 remain unassociated. The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope started operations in 2008. In this work, machine-learning algorithms are used to identify unassociated sources in the 2FGL catalog with properties similar to gamma-ray-emitting Active Galactic Nuclei (AGN). This analysis finds 231 high-confidence AGN candidates (see Table3). (1 data file).

Fermi Gamma-Ray Space Telescope Science Overview

NASA Technical Reports Server (NTRS)

Thompson, David J.

2010-01-01

After more than 2 years of science operations, the Fermi Gamma-ray Space Telescope continues to survey the high-energy sky on a daily basis. In addition to the more than 1400 sources found in the first Fermi Large Area Telescope Catalog (I FGL), new results continue to emerge. Some of these are: (1) Large-scale diffuse emission suggests possible activity from the Galactic Center region in the past; (2) a gamma-ray nova was found, indicating particle acceleration in this binary system; and (3) the Crab Nebula, long thought to be a steady source, has varied in the energy ranges seen by both Fermi instruments.

A NEW RESULT ON THE ORIGIN OF THE EXTRAGALACTIC GAMMA-RAY BACKGROUND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou Ming; Wang Jiancheng, E-mail: mzhou@ynao.ac.cn

2013-06-01

In this paper, we repeatedly use the method of image stacking to study the origin of the extragalactic gamma-ray background (EGB) at GeV bands, and find that the Faint Images of the Radio Sky at Twenty centimeters (FIRST) sources undetected by the Large Area Telescope on the Fermi Gamma-ray Space Telescope can contribute about (56 {+-} 6)% of the EGB. Because FIRST is a flux-limited sample of radio sources with incompleteness at the faint limit, we consider that point sources, including blazars, non-blazar active galactic nuclei, and starburst galaxies, could produce a much larger fraction of the EGB.

Medical isotope identification with large mobile detection systems

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Sanjoy; Maurer, Richard

2012-10-01

The Remote Sensing laboratory (RSL) of National Security Technologies Inc. has built an array of large (5.08 - cm x 10.16 - cm x 40.6 - cm) thallium doped sodium iodide (NaI: Tl) scintillators to locate and screen gamma-ray emitting radioisotopes that are of interests to radiological emergency responders [1]. These vehicle mounted detectors provide the operators with rapid, simple, specific information for radiological threat assessment. Applications include large area inspection, customs inspection, border protection, emergency response, and monitoring of radiological facilities. These RSL mobile units are currently being upgraded to meet the Defense Threat Reduction Agency mission requirements for a next-generation system capable of detecting and identifying nuclear threat materials. One of the challenging problems faced by these gamma-ray detectors is the unambiguous identification of medical isotopes like 131I (364.49 keV [81.7%], 636.99 keV [7.17%]), 99Tcm (140.51 keV [89.1%]) and 67Ga (184.6 keV [19.7%], 300.2 [16.0%], 393.5 [4.5%] that are used in radionuclide therapy and often have overlapping gamma-ray energy regions of interest (ROI). The problem is made worse by short (about 5 seconds) acquisition time of the spectral data necessary for dynamic mobile detectors. This article describes attempts to identify medical isotopes from data collected from this mobile detection system in a short period of time (not exceeding 5 secs) and a large standoff distance (typically 10 meters) The mobile units offer identification capabilities that are based on hardware auto stabilization of the amplifier gain. The 1461 keV gamma-energy line from 40K is tracked. It uses gamma-ray energy windowing along with embedded mobile Gamma Detector Response and Analysis Software (GADRAS) [2] simultaneously to deconvolve any overlapping gamma-energy ROIs. These high sensitivity detectors are capable of resolving complex masking scenarios and exceed all ANSI N42.34 (2006) requirements for the identification of bare, shielded and multiple isotopes.

Carcinostatic effects of platinum nanocolloid combined with gamma irradiation on human esophageal squamous cell carcinoma.

PubMed

Li, Qiang; Tanaka, Yoshiharu; Saitoh, Yasukazu; Tanaka, Hiroshi; Miwa, Nobuhiko

2015-04-15

To explore the carcinostatic effects of platinum nanocolloid (Pt-nc) combined with gamma rays on human esophageal squamous cell carcinoma (ESCC). ESCC-derived KYSE-70 cells were treated with various concentrations of Pt-nc and/or gamma irradiation, and subsequently cultured in phenol red free DMEM with 10% FBS for 48 h. The proliferative status of the KYSE-70 cells was evaluated using trypan blue dye exclusion and WST-8 assays. Cellular and nucleic morphological aspects were evaluated using crystal violet and Hoechst 33342 stainings, respectively. Radiosensitivity was quantified by a cell viability assay, and the activated form of caspase-3, a characteristic apoptosis-related protein, was detected by Western blotting. Although single treatment with either Pt-nc or gamma irradiation could slightly inhibit the growth of the KYSE-70 cells, their combination exerted remarkable carcinostatic effects in a manner dependent on either Pt-nc concentrations or gamma ray doses, compared with the effect of each treatment alone (p<0.05). By fluorescence micrographic observation, the KYSE-70 cells that were treated with Pt-nc and subsequently irradiated with gamma rays, were shown to undergo distinct apoptotic morphological changes. The carcinostatic effect of gamma rays at 7 Gy without Pt-nc was approximately equal to that when 3-Gy irradiation was combined with 100 ppm Pt-nc or that 5-Gy irradiation was combined with 50 ppm Pt-nc. Pt-nc in combination with gamma rays may exert a cooperative effect through platinum- or gamma ray-induced apoptosis resulting in the inhibition of growth of cancer cells, while concurrently enabling the lowering of the radiative dose. Copyright © 2015 Elsevier Inc. All rights reserved.

X-ray and gamma-ray emission of Sagittarius A* as a wind-accreting black hole

NASA Technical Reports Server (NTRS)

Mastichiadis, A.; Ozernoy, L. M.

1994-01-01

If, as many believe, Sgr A* is a massive black hole at the Galactic center, one should expect it to be a source of X-ray and gamma-ray activity, behaving basically as a scaled-down active galactic nucleus. An unavoidable source of accretion is the wind from IRS 16, a nearby group of hot, massive stars. Since the density and velocity of the accreting matter are known from observations, the accretion rate is basically a function of the putative black hole mass, M(sub h), only; this value represents a reliable lower limit to a real rate, given the other possible sources of accreting matter. Based on this and on the theories about shock acceleration in active galactic nuclei, we have estimated the expected production of relativistic particles and their hard radiation. These values turn out to be a function of M(sub h) as well. Comparing our results with available X-ray and gamma-ray observations which show Sgr A* to have a relatively low activity level, we conclude tentatively that the putative black hole in the Galactic center cannot have a mass greater than approximately 6 x 10(exp 3) solar mass. This conclusion is consistent with the upper limits to the black hole mass found by different methods earlier, although much more work is needed to make calculations of shock acceleration around black holes more reliable.

[A NASA / University Joint Venture in Space Science

NASA Technical Reports Server (NTRS)

Wold, Donald C.

1996-01-01

MILAGRO is a water-Cherenkov detector for observing cosmic gamma rays over a broad energy range of 100 GeV to 100 TeV. MILAGRO will be the first detector that has sensitivity overlapping both air-Cherenkov and air-shower detectors. With this detector scientists in the collaboration will study previously observed celestial sources at their known emission energies, extend these observations into a new energy regime, and search for new sources at unexplored energies. The diffuse gamma-radiation component in our galaxy, which originates from interactions of cosmic rays with interstellar gas and photons, provides important information about the density, distribution, and spectrum of the cosmic rays that pervade the interstellar medium. Events in the Compton Gamma Ray Observatory (GRO) are being observed up to about 30 GeV, differing by slightly more than order of magnitude from the low energy threshold of MILAGRO. By looking in coincidence at sources, correlated observations will greatly extend the astrophysics potential of MILAGRO and NASA's GRO. A survey of cosmic-ray observatories is being prepared for scientists and others to provide a resource and reference which describes high energy cosmic-ray research activities around the world. This summary presents information about each research group, such as names of principal investigators, number of persons in the collaboration, energy range, sensitivity, angular resolution, and surface area of detector. Similarly, a survey of gamma-ray telescopes is being prepared to provide a resource and reference which describes gamma-ray telescopes for investigating galactic diffuse gamma-ray flux currently observed in the GeV energy range, but is expected to extend into the TeV range. Two undergraduate students are compiling information about gamma-ray telescopes and high energy cosmic-ray observatories for these surveys. Funding for this project was provided by the Arkansas Space Grant Consortium. Also enclosed Appendix A, B, C, D and E.

Ground level gamma-ray and electric field enhancements during disturbed weather: Combined signatures from convective clouds, lightning and rain

NASA Astrophysics Data System (ADS)

Reuveni, Yuval; Yair, Yoav; Price, Colin; Steinitz, Gideon

2017-11-01

We report coincidences of ground-level gamma-ray enhancements with precipitation events and strong electric fields typical of thunderstorms, measured at the Emilio Segre Cosmic Ray observatory located on the western slopes of Mt. Hermon in northern Israel. The observatory hosts 2 × 2″ Nal(TI) gamma ray scintillation detectors alongside a vertical atmospheric electric field (Ez) mill and conduction current (Jz) plates. During several active thunderstorms that occurred near the Mt. Hermon station in October and November 2015, we recorded prolonged periods of gamma ray enhancements, which lasted tens of minutes and coincided with peaks both in precipitation and the vertical electric field. Two types of events were detected: slow increase (up to 300 min) of atmospheric gamma ray radiation due to radon progeny washout (or rainout) along with minutes of Ez enhancement, which were not associated with the occurrences of nearby CG lightning discharges. The second type showed 30 min bursts of gamma rays, coinciding with minutes of Ez enhancement that closely matched the occurrences of nearby CG lightning discharges, and are superimposed on the radiation from radon daughters washed out to near surface levels by precipitation. We conclude that a superposition of accelerated high energy electrons by thunderstorm electric fields and radon progeny washout (or rainout) explains the relatively fast near surface gamma-ray increase, where the minutes-scale vertical electric field enhancement are presumably caused due to nearby convective clouds. Our results show that the mean exponential half-life depletion times of the residual nuclei produced during events without lightning occurrences were between 25-65 min, compared to 55-100 min when lightning was present, indicating that different types of nuclei were involved.

Sneaky Gamma-Rays: Using Gravitational Lensing to Avoid Gamma-Gamma-Absorption

NASA Astrophysics Data System (ADS)

Boettcher, Markus; Barnacka, Anna

2014-08-01

It has recently been suggested that gravitational lensing studies of gamma-ray blazars might be a promising avenue to probe the location of the gamma-ray emitting region in blazars. Motivated by these prospects, we have investigated potential gamma-gamma absorption signatures of intervening lenses in the very-high-energy gamma-ray emission from lensedblazars. We considered intervening galaxies and individual stars within these galaxies. We find that the collective radiation field of galaxies acting as sources of macrolensing are not expected to lead to significant gamma-gamma absorption. Individual stars within intervening galaxies could, in principle, cause a significant opacity to gamma-gamma absorption for VHE gamma-rays if the impact parameter (the distance of closest approach of the gamma-ray to the center of the star) is small enough. However, we find that the curvature of the photon path due to gravitational lensing will cause gamma-ray photons to maintain a sufficiently large distance from such stars to avoid significant gamma-gamma absorption. This re-inforces the prospect of gravitational-lensing studies of gamma-ray blazars without interference due to gamma-gamma absorption due to the lensing objects.

Measurement of energetic radiation caused by thunderstorm activities by a sounding balloon and ground observation

NASA Astrophysics Data System (ADS)

Torii, T.

2015-12-01

Energetic radiation caused by thunderstorm activity is observed at various places, such as the ground, high mountain areas, and artificial satellites. In order to investigate the radiation source and its energy distribution, we measured energetic radiation by a sounding balloon, and the ground observation. On the measurement inside/above the thundercloud, we conducted a sounding observation using a radiosonde mounted two GM tubes (for gamma-rays, and for beta/gamma-rays), in addition to meteorological instruments. The balloon passed through a region of strong echoes in a thundercloud shown by radar image, at which time an increase in counting rate of the GM tube about 2 orders of magnitude occurred at the altitude from 5 km to 7.5 km. Furthermore, the counting rate of two GM tubes indicated the tendency different depending on movement of a balloon. This result suggests that the ratio for the gamma-rays (energetic photons) of the beta-rays (energetic electrons) varies according to the place in the thundercloud. Furthermore, we carried out a ground observation of the energetic gamma rays during winter thunderstorm at a coastal area facing the Sea of Japan. Two types of the energetic radiation have been observed at this time. We report the outline of these measurements and analysis in the session of the AGU meeting.

Cygnus X-3 Returns to an Active State

NASA Astrophysics Data System (ADS)

McCollough, Michael L.; Koljonen, Karri; Gurwell, Mark A.; Trushkin, Sergei; Pooley, Guy G.

2017-08-01

Cygnus X-3 is a well-known microquasar composed of a mass-donating Wolf-Rayet star and a compact object. Recently, Cygnus X-3 has been in a quiescent state for an extended period of time (2011-2016) but returned to an active state on two occasions during 2016/2017 including quenched/hypersoft states, gamma-ray emission, and major radio flares. During these two periods of activity, we undertook multi-wavelength observing campaigns with observations in the radio (RATAN-600, AMI-LA, Metsähovi), submillimeter (SMA, EHT), X-ray (Swift/XRT, MAXI), hard X-ray (Swift/BAT, NuSTAR), and gamma-ray (AGILE, Fermi, VERITAS). At the peak of the major radio flare in April 2017 observations were made with VERITAS (TeV), NuSTAR (hard X-ray), and the Event Horizon Telescope (submillimeter). In this presentation, I will review these observing campaigns and the insights they provide about Cygnus X-3.

An exceptionally bright flare from SGR 1806-20 and the origins of short-duration gamma-ray bursts.

PubMed

Hurley, K; Boggs, S E; Smith, D M; Duncan, R C; Lin, R; Zoglauer, A; Krucker, S; Hurford, G; Hudson, H; Wigger, C; Hajdas, W; Thompson, C; Mitrofanov, I; Sanin, A; Boynton, W; Fellows, C; von Kienlin, A; Lichti, G; Rau, A; Cline, T

2005-04-28

Soft-gamma-ray repeaters (SGRs) are galactic X-ray stars that emit numerous short-duration (about 0.1 s) bursts of hard X-rays during sporadic active periods. They are thought to be magnetars: strongly magnetized neutron stars with emissions powered by the dissipation of magnetic energy. Here we report the detection of a long (380 s) giant flare from SGR 1806-20, which was much more luminous than any previous transient event observed in our Galaxy. (In the first 0.2 s, the flare released as much energy as the Sun radiates in a quarter of a million years.) Its power can be explained by a catastrophic instability involving global crust failure and magnetic reconnection on a magnetar, with possible large-scale untwisting of magnetic field lines outside the star. From a great distance this event would appear to be a short-duration, hard-spectrum cosmic gamma-ray burst. At least a significant fraction of the mysterious short-duration gamma-ray bursts may therefore come from extragalactic magnetars.

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

NASA Astrophysics Data System (ADS)

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.

Fermi Gamma-Ray Imaging of a Radio Galaxy

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2010-04-01

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

Metal enrichment in the Fermi bubbles as a probe of their origin

NASA Astrophysics Data System (ADS)

Inoue, Yoshiyuki; Nakashima, Shinya; Tahara, Masaya; Kataoka, Jun; Totani, Tomonori; Fujita, Yutaka; Sofue, Yoshiaki

2015-06-01

The Fermi bubbles are gigantic gamma-ray structures in our Galaxy. The physical origin of the bubbles is still under debate. The leading scenarios can be divided into two categories. One is nuclear star-forming activity similar to extragalactic starburst galaxies and the other is past active galactic nucleus (AGN)-like activity of the Galactic center supermassive black hole. In this letter, we propose that metal abundance measurements will provide an important clue to probe their origin. Based on a simple spherically symmetric bubble model, we find that the generated metallicity and abundance patterns of the bubbles' gas strongly depend on assumed star formation or AGN activities. Star formation scenarios predict higher metallicities and abundance ratios of [O/Fe] and [Ne/Fe] than AGN scenarios do because of supernovae ejecta. Furthermore, the resultant abundance depends on the gamma-ray emission process because different mass injection histories are required for the different gamma-ray emission processes due to the acceleration and cooling time scales of non-thermal particles. Future X-ray missions such as ASTRO-H and Athena will give a clue to probe the origin of the bubbles through abundance measurements with their high energy resolution instruments.

A laboratory activity for teaching natural radioactivity

NASA Astrophysics Data System (ADS)

Pilakouta, M.; Savidou, A.; Vasileiadou, S.

2017-01-01

This paper presents an educational approach for teaching natural radioactivity using commercial granite samples. A laboratory activity focusing on the topic of natural radioactivity is designed to develop the knowledge and understanding of undergraduate university students on the topic of radioactivity, to appreciate the importance of environmental radioactivity and familiarize them with the basic technology used in radioactivity measurements. The laboratory activity is divided into three parts: (i) measurements of the count rate with a Geiger-Muller counter of some granite samples and the ambient background radiation rate, (ii) measurement of one of the samples using gamma ray spectrometry with a NaI detector and identification of the radioactive elements of the sample, (iii) using already recorded 24 h gamma ray spectra of the samples from the first part (from the Granite Gamma-Ray Spectrum Library (GGRSL) of our laboratory) and analyzing selected peaks in the spectrum, students estimate the contribution of each radioactive element to the total specific activity of each sample. A brief description of the activity as well as some results and their interpretation are presented.

Design and performance of the GAMMA-400 gamma-ray telescope for dark matter searches

NASA Astrophysics Data System (ADS)

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.; Moiseev, A. A.; Mocchiutti, E.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu.; Papini, P.; Picozza, P.; Rodin, V. G.; Runtso, M. F.; Sparvoli, R.; Spillantini, P.; Suchkov, S. I.; Tavani, M.; Topchiev, N. P.; Vacchi, A.; Vannuccini, E.; Yurkin, Yu. T.; Zampa, N.; Zverev, V. G.; Zirakashvili, V. N.

2013-02-01

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 ~0.01° (Eγ > 100 GeV), the energy resolution ~1% (Eγ > 10 GeV), and the proton rejection factor ~106. GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

A semi-empirical approach to analyze the activities of cylindrical radioactive samples using gamma energies from 185 to 1764 keV.

PubMed

Huy, Ngo Quang; Binh, Do Quang

2014-12-01

This work suggests a method for determining the activities of cylindrical radioactive samples. The self-attenuation factor was applied for providing the self-absorption correction of gamma rays in the sample material. The experimental measurement of a (238)U reference sample and the calculation using the MCNP5 code allow obtaining the semi-empirical formulae of detecting efficiencies for the gamma energies ranged from 185 to 1764keV. These formulae were used to determine the activities of the (238)U, (226)Ra, (232)Th, (137)Cs and (40)K nuclides in the IAEA RGU-1, IAEA-434, IAEA RGTh-1, IAEA-152 and IAEA RGK-1 radioactive standards. The coincidence summing corrections for gamma rays in the (238)U and (232)Th series were applied. The activities obtained in this work were in good agreement with the reference values. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Early Life Of A Gamma-ray Burst

NASA Astrophysics Data System (ADS)

O'Brien, P. T.; Willingale, D.

2006-09-01

We present results for 100 gamma-ray bursts observed promptly by the Swift satellite. Combining the early gamma-ray and X-ray data from the BAT and XRT, we show that although individual GRBs can display complex light curves, including a variety of decay phases and flares, their early emission can be described by a relatively simple combination of central engine activity and the interaction of a relativistic jet with the surrounding environment. We also discuss the later fading, which in the optical/IR has traditionally been explained as a jet-break. The Swift data reveal many bursts have a relatively early break in their X-ray light curves contradicting the standard jet break model derived from optical data. We discuss the implications of this for GRB jet models and for using GRBs as standard candles.

A search for low energy gamma rays from CG 195+4

NASA Technical Reports Server (NTRS)

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

1979-01-01

A 13-deg-wide region of sky containing the high-energy gamma-ray source CG 195+4 was searched for X-ray and gamma-ray emission in the energy interval from 0.035 to 8.737 MeV. The balloon-altitude measurements were undertaken on October 4, 1977, at Palestine, Texas, and used an actively collimated scintillation counter. As a result of the measurements, low upper limits have been found for the spectrum from the source. Combined with the positive detections made with satellites at high energies, the measurements show that the photon number spectrum must have a spectral index harder than 2.0. The data appear inconsistent with models of the source in which the presumed neutron star is surrounded by a cloud thick to X-rays. Negative results of the search for periodicity are discussed.