Science.gov

Sample records for atmospheric gamma-ray imaging

  1. The major atmospheric gamma-ray imaging Cherenkov telescope

    NASA Astrophysics Data System (ADS)

    Garczarczyk, Markus; MAGIC Collaboration

    2011-05-01

    MAGIC is a system of two 17 m diameter Imaging Atmospheric Cherenkov Telescopes (IACTs) for ground-based γ-ray astronomy. During many years, starting with the design phase of the first telescope in 2003, the upgrade of the second telescope in 2008 up to now, novel technologies have been developed, commissioned and continuously improved. Most components and subsystems represent nowadays state of the art techniques and are under consideration to be used in future detectors. The large reflector area, together with small diameter, high quantum efficiency (QE) photomultipliers (PMTs) in combination with an improved trigger and readout system permits an analysis threshold of 25 GeV, the lowest among current IACTs. MAGIC overlaps in energy with the upper end of current satellite experiments and gives the unique opportunity, for the first time, to cross-calibrate ground based versus satellite born detectors. Some selected techniques used in MAGIC, which are in context with this conference, are presented.

  2. Gamma-ray Imaging Methods

    SciTech Connect

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

    2006-10-05

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

  3. Atmospheric gamma-ray and neutron flashes

    SciTech Connect

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

    2008-01-15

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

  4. Medical gamma ray imaging

    DOEpatents

    Osborne, Louis S.; Lanza, Richard C.

    1984-01-01

    A method and apparatus for determining the distribution of a position-emitting radioisotope into an object, the apparatus consisting of a wire mesh radiation converter, an ionizable gas for propagating ionization events caused by electrodes released by the converter, a drift field, a spatial position detector and signal processing circuitry for correlating near-simultaneous ionization events and determining their time differences, whereby the position sources of back-to-back collinear radiation can be located and a distribution image constructed.

  5. Gamma-Ray Imaging for Explosives Detection

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  6. Future Gamma-Ray Imaging of Solar Eruptive Events

    NASA Technical Reports Server (NTRS)

    Shih, Albert

    2012-01-01

    Solar eruptive events, the combination of large solar flares and coronal mass ejections (CMEs), accelerate ions to tens of Gev and electrons to hundreds of MeV. The energy in accelerated particles can be a significant fraction (up to tens of percent) of the released energy and is roughly equipartitioned between ions and electrons. Observations of the gamma-ray signatures produced by these particles interacting with the ambient solar atmosphere probes the distribution and composition of the accelerated population, as well as the atmospheric parameters and abundances of the atmosphere, ultimately revealing information about the underlying physics. Gamma-ray imaging provided by RHESSI showed that the interacting approx.20 MeV/nucleon ions are confined to flare magnetic loops rather than precipitating from a large CME-associated shock. Furthermore, RHESSI images show a surprising, significant spatial separation between the locations where accelerated ions and electrons are interacting, thus indicating a difference in acceleration or transport processes for the two types of particles. Future gamma-ray imaging observations, with higher sensitivity and greater angular resolution, can investigate more deeply the nature of ion acceleration. The technologies being proven on the Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS), a NASA balloon instrument, are possible approaches for future instrumentation. We discuss the GRIPS instrument and the future of studying this aspect of solar eruptive events.

  7. Gamma-ray imaging with germanium detectors

    NASA Astrophysics Data System (ADS)

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

    1993-01-01

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

  8. Gamma-ray imaging with germanium detectors

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  9. Gamma-Ray Imaging Probes.

    NASA Astrophysics Data System (ADS)

    Wild, Walter James

    1988-12-01

    External nuclear medicine diagnostic imaging of early primary and metastatic lung cancer tumors is difficult due to the poor sensitivity and resolution of existing gamma cameras. Nonimaging counting detectors used for internal tumor detection give ambiguous results because distant background variations are difficult to discriminate from neighboring tumor sites. This suggests that an internal imaging nuclear medicine probe, particularly an esophageal probe, may be advantageously used to detect small tumors because of the ability to discriminate against background variations and the capability to get close to sites neighboring the esophagus. The design, theory of operation, preliminary bench tests, characterization of noise behavior and optimization of such an imaging probe is the central theme of this work. The central concept lies in the representation of the aperture shell by a sequence of binary digits. This, coupled with the mode of operation which is data encoding within an axial slice of space, leads to the fundamental imaging equation in which the coding operation is conveniently described by a circulant matrix operator. The coding/decoding process is a classic coded-aperture problem, and various estimators to achieve decoding are discussed. Some estimators require a priori information about the object (or object class) being imaged; the only unbiased estimator that does not impose this requirement is the simple inverse-matrix operator. The effects of noise on the estimate (or reconstruction) is discussed for general noise models and various codes/decoding operators. The choice of an optimal aperture for detector count times of clinical relevance is examined using a statistical class-separability formalism.

  10. Gamma-ray background induced by atmospheric neutrons

    SciTech Connect

    Ma Yu-qian

    1984-01-01

    A small piggyback detector system is used to study the reduction of ..gamma..-ray background induced by atmospheric neutrons in the type of active shielded ..gamma..-ray spectroscopes. The system consists of two phi1X5 x 1X5 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.

  11. Development of gamma ray imaging cameras

    SciTech Connect

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

    1992-05-28

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

  12. Development of gamma ray imaging cameras

    NASA Astrophysics Data System (ADS)

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

    1992-05-01

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

  13. Gamma-Ray Flashes of Atmospheric Origin. The Compton Gamma-Ray Observatory Guest Investigator Program: Cycle 7

    NASA Technical Reports Server (NTRS)

    Mallozzi, Robert S.; Fishman, G. J.; Pendleton, G. N.; Inan, U. S.

    2000-01-01

    The BATSE detectors on the Compton Gamma-Ray Observatory have recorded the first observations of an unexplained terrestrial phenomenon: brief, intense flashes of MeV photons. These events, known as terrestrial gamma-ray flashes, must originate at altitudes above 30 km to be observed by the orbiting detectors. More than 70 of these events have been observed in nine years of observations. The most likely origin of these high-energy photons is bremsstrahlung from relativistic electrons from high altitude electrical discharges above thunderstorm regions. We proposed to analyze observations of temporal and spectral properties of these events, and to produce a catalog of event characteristics. Temporal correlations with radio observations made at Palmer Station, Antarctica and spatial correlations with satellite images of thunderstorm regions near GRO during these events were investigated, aiding in verification and testing of proposed theoretical models of the atmospheric processes believed to be responsible for these unique observations.

  14. 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.

  15. Discovery of intense gamma-ray flashes of atmospheric origin

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.; Bhat, P. N.; Mallozzi, R.; Horack, J. M.; Koshut, T.; Kouveliotou, C.; Pendleton, G. N.; Meegan, C. A.; Wilson, R. B.; Paciesas, W. S.

    1994-01-01

    Observations have been made of a new terrestrial phenomenon: brief (approx. millisecond), intense flashes of gamma rays, observed with space-borne detectors. These flashes must originate at altitudes in the atmosphere above at least 30 km in order to be observable by orbiting detectors aboard the Compton Gamma-Ray Observatory (CGRO). At least a dozen events have been detected over the past 2 years. The photon spectra from the events are very hard and are consistent with bremsstrahlung emission from energetic (MeV) electrons. The most likely origin of these high energy electrons, while speculative at this time, is a rare type of high altitude electrical discharge above thunderstorm regions.

  16. Coded-Aperture Compton Camera for Gamma-Ray Imaging

    NASA Astrophysics Data System (ADS)

    Farber, Aaron M.; Williams, John G.

    2016-02-01

    A novel gamma-ray imaging system is demonstrated, by means of Monte Carlo simulation. Previous designs have used either a coded aperture or Compton scattering system to image a gamma-ray source. By taking advantage of characteristics of each of these systems a new design can be implemented that does not require a pixelated stopping detector. Use of the system is illustrated for a simulated radiation survey in a decontamination and decommissioning operation.

  17. The Advanced Gamma-ray Imaging System (AGIS): Simulation studies

    SciTech Connect

    Maier, G.; Buckley, J.; Bugaev, V.; Fegan, S.; Funk, S.; Konopelko, A.; Vassiliev, V.V.; /UCLA

    2011-06-14

    The Advanced Gamma-ray Imaging System (AGIS) is a next-generation ground-based gamma-ray observatory being planned in the U.S. The anticipated sensitivity of AGIS is about one order of magnitude better than the sensitivity of current observatories, allowing it to measure gamma-ray emission from a large number of Galactic and extra-galactic sources. We present here results of simulation studies of various possible designs for AGIS. The primary characteristics of the array performance - collecting area, angular resolution, background rejection, and sensitivity - are discussed.

  18. Production of gamma rays with energies greater than 30 MeV in the atmosphere

    NASA Technical Reports Server (NTRS)

    Thompson, D.; Fichtel, C.; Kniffen, D.

    1974-01-01

    A three-dimensional study of atmospheric gamma rays with energy greater than 30 MeV has been carried out. Experimental results were obtained from four balloon flights from Palestine, Texas, with a 15 cm by 15 cm digitized wire grid spark chamber. The energy spectrum for downward-moving gamma rays steepens with increasing atmospheric depth. Near the top of the atmosphere, the spectrum steepens with increasing zenith angle. Experimental results compare reasonably well with a three-dimensional Monte Carlo calculation of atmospheric gamma ray production. Inclusion of upward-moving gamma rays makes possible the use of atmospheric secondaries for in-flight calibration of satellite gamma ray detectors.

  19. Development and performance of a gamma-ray imaging detector

    NASA Astrophysics Data System (ADS)

    Gálvez, J. L.; Hernanz, M.; Álvarez, J. M.; La Torre, M.; Álvarez, L.; Karelin, D.; Lozano, M.; Pellegrini, G.; Ullán, M.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

    2012-09-01

    In the last few years we have been working on feasibility studies of future instruments in the gamma-ray range, from several keV up to a few MeV. The innovative concept of focusing gamma-ray telescopes in this energy range, should allow reaching unprecedented sensitivities and angular resolution, thanks to the decoupling of collecting area and detector volume. High sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators, e.g., Supernovae, Classical Novae, Supernova Remnants (SNRs), Gamma-Ray Bursts (GRBs), Pulsars, Active Galactic Nuclei (AGN). In order to achieve the needed performance, a gamma-ray imaging detector with mm spatial resolution and large enough efficiency is required. In order to fulfill the combined requirement of high detection efficiency with good spatial and energy resolution, an initial prototype of a gamma-ray imaging detector based on CdTe pixel detectors is being developed. It consists of a stack of several layers of CdTe detectors with increasing thickness, in order to enhance the gamma-ray absorption in the Compton regime. A CdTe module detector lies in a 11 x 11 pixel detector with a pixel pitch of 1mm attached to the readout chip. Each pixel is bump bonded to a fan-out board made of alumina (Al2O3) substrate and routed to the corresponding input channel of the readout ASIC to measure pixel position and pulse height for each incident gamma-ray photon. We will report the main features of the gamma-ray imaging detector performance such as the energy resolution for a set of radiation sources at different operating temperatures.

  20. Gamma-ray imaging with coaxial HPGe detector

    SciTech Connect

    Niedermayr, T; Vetter, K; Mihailescu, L; Schmid, G J; Beckedahl, D; Kammeraad, J; Blair, J

    2005-04-12

    We report on the first experimental demonstration of Compton imaging of gamma rays with a single coaxial high-purity germanium (HPGe) detector. This imaging capability is realized by two-dimensional segmentation of the outside contact in combination with digital pulse-shape analysis, which enables to image gamma rays in 4{pi} without employing a collimator. We are able to demonstrate the ability to image the 662keV gamma ray from a {sup 137}Cs source with preliminary event selection with an angular accuracy of 5 degree with an relative efficiency of 0.2%. In addition to the 4{pi} imaging capability, such a system is characterized by its excellent energy resolution and can be implemented in any size possible for Ge detectors to achieve high efficiency.

  1. The Advanced Gamma-Ray Imaging System (AGIS): Science Highlights

    SciTech Connect

    Buckley, J.; Coppi, P.; Digel, S.; Funk, S.; Krawczynski, H.; Krennrich, F.; Pohl, M.; Romani, R.; Vassiliev, V.; /UCLA

    2011-11-21

    The Advanced Gamma-ray Imaging System (AGIS), a future gamma-ray telescope consisting of an array of {approx}50 atmospheric Cherenkov telescopes distributed over an area of {approx}1 km{sup 2}, will provide a powerful new tool for exploring the high-energy universe. The order-of-magnitude increase in sensitivity and improved angular resolution could provide the first detailed images of {gamma}-ray emission from other nearby galaxies or galaxy clusters. The large effective area will provide unprecedented sensitivity to short transients (such as flares from AGNs and GRBs) probing both intrinsic spectral variability (revealing the details of the acceleration mechanism and geometry) as well as constraining the high-energy dispersion in the velocity of light (probing the structure of spacetime and Lorentz invariance). A wide field of view ({approx}4 times that of current instruments) and excellent angular resolution (several times better than current instruments) will allow for an unprecedented survey of the Galactic plane, providing a deep unobscured survey of SNRs, X-ray binaries, pulsar-wind nebulae, molecular cloud complexes and other sources. The differential flux sensitivity of {approx}10{sup -13} erg cm{sup -2} sec{sup -1} will rival the most sensitive X-ray instruments for these extended Galactic sources. The excellent capabilities of AGIS at energies below 100 GeV will provide sensitivity to AGN and GRBs out to cosmological redshifts, increasing the number of AGNs detected at high energies from about 20 to more than 100, permitting population studies that will provide valuable insights into both a unified model for AGN and a detailed measurement of the effects of intergalactic absorption from the diffuse extragalactic background light. A new instrument with fast-slewing wide-field telescopes could provide detections of a number of long-duration GRBs providing important physical constraints from this new spectral component. The new array will also have excellent

  2. PANGU: a wide field gamma-ray imager and polarimeter

    NASA Astrophysics Data System (ADS)

    Wu, X.; Walter, R.; Su, M.; Ambrosi, G.; Azzarello, P.; Böttcher, M.; Chang, J.; Chernyakova, M.; Fan, Y.; Farnier, C.; Gargano, F.; Grenier, I.; Hajdas, W.; Mazziotta, M. N.; Pearce, M.; Pohl, M.; Zdziarski, A.

    2016-07-01

    PANGU (the PAir-productioN Gamma-ray Unit) is a gamma-ray telescope with a wide field of view optimized for spectro-imaging, timing and polarization studies. It will map the gamma-ray sky from 10 MeV to a few GeV with unprecedented spatial resolution. This window on the Universe is unique to detect photons produced directly by relativistic particles, via the decay of neutral pions, or the annihilation or decay light from anti-matter and the putative light dark matter candidates. A wealth of questions can be probed among the most important themes of modern physics and astrophysics. The PANGU instrument is a pair-conversion gamma-ray telescope based on an innovative design of a silicon strip tracker. It is light, compact and accurate. It consists of 100 layers of silicon micro-strip detector of 80 x 80 cm2 in area, stacked to height of about 90 cm, and covered by an anticoincidence detector. PANGU relies on multiple scattering effects for energy measurement, reaching an energy resolution between 30-50% for 10 MeV - 1 GeV. The novel tracker will allow the first polarization measurement and provide the best angular resolution ever obtained in the soft gamma ray and GeV band.

  3. A large-area gamma-ray imaging telescope system

    NASA Technical Reports Server (NTRS)

    Koch, D. G.

    1983-01-01

    The concept definition of using the External Tank (ET) of the Space Shuttle as the basis for constructing a large area gamma ray imaging telescope in space is detailed. The telescope will be used to locate and study cosmic sources of gamma rays of energy greater than 100 MeV. Both the telescope properties and the means whereby an ET is used for this purpose are described. A parallel is drawn between those systems that would be common to both a Space Station and this ET application. In addition, those systems necessary for support of the telescope can form the basis for using the ET as part of the Space Station. The major conclusions of this concept definition are that the ET is ideal for making into a gamma ray telescope, and that this telescope will provide a substantial increase in collecting area.

  4. The Gamma-Ray Imaging Spectrometer (GRIS): A new balloon-borne experiment for gamma-ray line astronomy

    NASA Astrophysics Data System (ADS)

    Teegarden, B. J.; Cline, T. L.; Gehrels, N.; Porreca, G.; Tueller, J.; Leventhal, M.; Huters, A. F.; MacCallum, C. J.; Stang, P. D.

    1985-08-01

    High resolution gamma-ray spectroscopy is a relatively new field that holds great promise for further understanding of high energy astrophysical processes. When the high resolution gamma-ray spectrometer (GRSE) was removed from the GRO payload, a balloon program was initiated to permit continued development and improvement of instrumentation in this field, as well as continued scientific observations. The Gamma-Ray Imaging Spectrometer (GRIS) is one of the experiments selected as part of this program. The instrument contains a number of new and innovative features that are expected to produce a significant improvement in source location accuracy and sensitivity over previous balloon and satellite experiments.

  5. A balloon-borne imaging gamma-ray telescope

    NASA Technical Reports Server (NTRS)

    Althouse, W. E.; Cook, W. R.; Cummings, A. C.; Finger, M. H.; Prince, T. A.; Schindler, S. M.; Starr, C. H.; Stone, E. C.

    1985-01-01

    A balloon-borne coded-aperture gamma-ray telescope for galactic and extragalactic astronomy observations is described. The instrument, called Gamma Ray Imaging Payload (GRIP), is designed for measurements in the energy range from 30 keV to 5 MeV with an angular resolution of 0.6 deg over a 20 deg field of view. Distinguishing characteristics of the telescope are a rotating hexagonal coded-aperture mask and a thick NaI scintillation camera. Rotating hexagonal coded-apertures and the development of thick scintillation cameras are discussed.

  6. The Advanced Gamma-ray Imaging System (AGIS) - Simulation Studies

    SciTech Connect

    Maier, G.; Buckley, J.; Bugaev, V.; Fegan, S.; Vassiliev, V. V.; Funk, S.; Konopelko, A.

    2008-12-24

    The Advanced Gamma-ray Imaging System (AGIS) is a US-led concept for a next-generation instrument in ground-based very-high-energy gamma-ray astronomy. The most important design requirement for AGIS is a sensitivity of about 10 times greater than current observatories like Veritas, H.E.S.S or MAGIC. We present results of simulation studies of various possible designs for AGIS. The primary characteristics of the array performance, collecting area, angular resolution, background rejection, and sensitivity are discussed.

  7. Gamma-ray bursts and terrestrial planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Thomas, B. C.; Melott, A. L.

    2006-07-01

    We describe results of modelling the effects on Earth-like planets of long-duration gamma-ray bursts (GRBs) within a few kiloparsecs. A primary effect is generation of nitrogen oxide compounds which deplete ozone. Ozone depletion leads to an increase in solar UVB radiation at the surface, enhancing DNA damage, particularly in marine microorganisms such as phytoplankton. In addition, we expect increased atmospheric opacity due to build-up of nitrogen dioxide produced by the burst and enhanced precipitation of nitric acid. We review here previous work on this subject and discuss recent developments, including further discussion of our estimates of the rates of impacting GRBs and the possible role of short-duration bursts.

  8. A three-dimensional study of 30- to 300-MeV atmospheric gamma rays

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.

    1974-01-01

    A three-dimensional study of atmospheric gamma rays with energy greater than 30 MeV has been carried out. A knowledge of these atmospheric secondaries has significant applications to the study of cosmic gamma rays. For detectors carried on balloons, atmospherically produced gamma rays are the major source of background. For satellite detectors, atmospheric secondaries provide a calibration source. Experimental results were obtained from four balloon flights from Palestine, Texas, with a 15 cm by 15 cm digitized wire grid spark chamber. The energy spectrum for downward-moving gamma rays steepens with increasing atmospheric depth. Near the top of the atmosphere, the spectrum steepens with increasing zenith angle. A new model of atmospheric secondary production has calculated the depth, the energy, and the zenith angle dependence of gamma rays above 30 MeV, using a comprehensive three-dimensional Monte Carlo model of the nucleon-meson-electromagnetic cascade.

  9. A low-energy gamma-ray imaging detector

    NASA Technical Reports Server (NTRS)

    Yin, L. I.; Trombka, J. I.; Seltzer, S. M.

    1979-01-01

    We describe a hard-X-ray/soft-gamma-ray imaging detector, incorporating a microchannel-plate (MCP) electron multiplier for possible use in future telescopes. In contrast to previous attempts using MCP's this approach promises to achieve high quantum detection efficiencies in addition to high spatial and temporal resolution. Preliminary results indicate not only the capability of simultaneous imaging and single-photon counting, but also coarse energy resolution.

  10. 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.

  11. Minute-of-Arc Resolution Gamma ray Imaging Experiment -- MARGIE

    NASA Astrophysics Data System (ADS)

    Altice, P. P.; Cherry, M. L.; Guzik, T. G.; Kappadath, S. C.; Stacy, J. G.; Macri, J.; McConnell, M. L.; Ryan, J. M.; Band, D. L.; Matteson, J. L.; O'Neill, T. J.; Zych, A. D.; Buckley, J.; Hink, P. L.

    1999-04-01

    MARGIE (Minute-of-Arc Resolution Gamma-ray Imaging Experiment) is a large area ( ~ 10(4) cm(2) ), wide field-of-view ( ~ 1 sr), hard X-ray/gamma-ray ( ~ 20--500 keV) coded-mask imaging telescope capable of performing a sensitive survey of both steady and transient cosmic sources. MARGIE has been selected for a NASA mission-concept study for an Ultra Long Duration (100 day) Balloon flight. We describe our program to develop the instrument based on new detector technology of either cadmium-zinc-telluride (CZT) semiconductors or pixellated cesium iodide (CsI) scintillators viewed by fast-timing bi-directional charge-coupled devices (CCDs). The primary scientific objective is to image faint Gamma-Ray Bursts (GRB) in near-real-time at the low intensity end (high-redshift) of the logN--logS distribution, thereby extending the sensitivity of present observations. Other high-priority scientific goals include a wide field survey of the Galactic center, mapping the distribution of the Galactic 511 keV emission and performing high-resolution spectral and temporal studies of active galaxies.

  12. Tumor detection in gamma-ray images

    NASA Astrophysics Data System (ADS)

    Strickland, Robin N.

    1992-12-01

    We describe a nonlinear detector which uses student's t-test to locate tumors occurring in anatomic background. The detector computes the significance of any observed difference between the mean of features extracted from a small, circular search window and the mean of features belonging to an outer, concentric background window. The t-test is applied to search windows at every pixel location in the image. The t-statistic computed from the sample means and variances of the inner and outer regions is thresholded at a chosen significance level to give a positive detection. The response of the detector peaks when the inner window coincides with a bright spot of the same size. Nonuniform anatomic background activity is effectively suppressed, except for structure of the same size and shape as the tumors being sought. Because the t-statistic is a true measure of significance, it can be applied to any set of features which are likely to distinguish tumors. We apply the test to two features, one related to object intensity and the other to object shape. A final determination on the presence and location of tumors is made by a simple combination of the significance levels generated from each feature. Tests are performed using simulated tumors superimposed on clinical images. Performance curves resembling standard receiver-operating-characteristic (ROC) plots show a slight improvement over the prewhitening matched filter. Unlike the matched filter, however, the t-test detector assumes nothing specific about the tumor apart from its size.

  13. Present status of very high energy gamma ray astronomy and plans for an imaging gamma ray telescope in India

    NASA Astrophysics Data System (ADS)

    Bhat, C. L.

    1993-09-01

    The unequivocal detection of the Crab Nebula as the first-ever standard candle in the very high energy (VHE) bracket, made possible by the recently-developed Cerenkov Imaging Technique, marks a water-shed in the 20 year-old history of the TeV gamma-ray astronomy. It gives hope that, as with the Crab today, future detections in the field, too, will be on a firm statistical footing and the attendant investigations, more comprehensive in their content and range. The present mood in the field is one of cautious optimism. This paper gives an overview of the contemporary observational scene in the ground-based gamma-ray astronomy. It closes with an introduction to TACTIC, the first Indian Imaging gamma-ray telescope, presently under-development.

  14. Fiber fed x-ray/gamma ray imaging apparatus

    DOEpatents

    Hailey, Charles J.; Ziock, Klaus-Peter

    1992-01-01

    X-ray/gamma ray imaging apparatus is disclosed for detecting the position, energy, and intensity of x-ray/gamma ray radiation comprising scintillation means disposed in the path of such radiation and capable of generating photons in response to such radiation; first photodetection means optically bonded to the scintillation means and capable of generating an electrical signal indicative of the intensity, and energy of the radiation detected by the scintillation means; second photodetection means capable of generating an electrical signal indicative of the position of the radiation in the radiation pattern; and means for optically coupling the scintillation means to the second photodetection means. The photodetection means are electrically connected to control and storage means which may also be used to screen out noise by rejecting a signal from one photodetection means not synchronized to a signal from the other photodetection means; and also to screen out signals from scattered radiation.

  15. Fiber fed x-ray/gamma ray imaging apparatus

    DOEpatents

    Hailey, C.J.; Ziock, K.P.

    1992-06-02

    X-ray/gamma ray imaging apparatus is disclosed for detecting the position, energy, and intensity of x-ray/gamma ray radiation comprising scintillation means disposed in the path of such radiation and capable of generating photons in response to such radiation; first photodetection means optically bonded to the scintillation means and capable of generating an electrical signal indicative of the intensity, and energy of the radiation detected by the scintillation means; second photodetection means capable of generating an electrical signal indicative of the position of the radiation in the radiation pattern; and means for optically coupling the scintillation means to the second photodetection means. The photodetection means are electrically connected to control and storage means which may also be used to screen out noise by rejecting a signal from one photodetection means not synchronized to a signal from the other photodetection means; and also to screen out signals from scattered radiation. 6 figs.

  16. A compact gamma ray imager for oncology

    NASA Astrophysics Data System (ADS)

    Pani, R.; Soluri, A.; Scafè, R.; Pellegrini, R.; Tatı̀, A.; Scopinaro, F.; De Vincentis, G.; Gigliotti, T.; Festinesi, A.; Garibaldi, F.; Del Guerra, A.

    2002-01-01

    A variety of new techniques based on radiopharmaceuticals are showing a valid support for cancer detection and interventional procedures. Axillary lymph nodes status is the most important prognostic factor for determining breast cancer prognosis. The use of dedicated gamma cameras characterized by low costs and weight, could be easily transferred to detection for bioptical procedures. To this aim this paper presents a new detection system having two heads with 4 and 25 cm 2 Field of View (FOV) and 0.8 and 3.6 kg weight, respectively. This novel scintillation camera is based upon a compact Position Sensitive Photo Multiplier Tube (PSPMT) Hamamatsu R5900-C8 as individual or array assembled. The Hamamatsu R5900-C8 is a metal channel dynode PMT with a crossed wire anode. The overall dimensions are 28×28 mm 2 and 20 mm height. It was coupled to a CsI(Tl) array of individual 3×3×3 mm 3 crystals. The measured intrinsic spatial resolution proved much better than the pixel size. A clinical image obtained from a breast phantom showed a 6 mm sized tumor.

  17. Gamma ray imager on the DIII-D tokamak

    SciTech Connect

    Pace, D. C. Taussig, D.; Eidietis, N. W.; Van Zeeland, M. A.; Watkins, M.; Cooper, C. M.; Hollmann, E. M.; Riso, V.

    2016-04-15

    A gamma ray camera is built for the DIII-D tokamak [J. Luxon, Nucl. Fusion 42, 614 (2002)] that provides spatial localization and energy resolution of gamma flux by combining a lead pinhole camera with custom-built detectors and optimized viewing geometry. This diagnostic system is installed on the outer midplane of the tokamak such that its 123 collimated sightlines extend across the tokamak radius while also covering most of the vertical extent of the plasma volume. A set of 30 bismuth germanate detectors can be secured in any of the available sightlines, allowing for customizable coverage in experiments with runaway electrons in the energy range of 1–60 MeV. Commissioning of the gamma ray imager includes the quantification of electromagnetic noise sources in the tokamak machine hall and a measurement of the energy spectrum of background gamma radiation. First measurements of gamma rays coming from the plasma provide a suitable testbed for implementing pulse height analysis that provides the energy of detected gamma photons.

  18. Gamma ray imager on the DIII-D tokamak

    SciTech Connect

    Pace, D. C.; Cooper, C. M.; Taussig, D.; Eidietis, N. W.; Hollmann, E. M.; Riso, V.; Van Zeeland, M. A.; Watkins, M.

    2016-04-13

    A gamma ray camera is built for the DIII-D tokamak [J. Luxon, Nucl. Fusion 42, 614 (2002)] that provides spatial localization and energy resolution of gamma flux by combining a lead pinhole camera with custom-built detectors and optimized viewing geometry. This diagnostic system is installed on the outer midplane of the tokamak such that its 123 collimated sightlines extend across the tokamak radius while also covering most of the vertical extent of the plasma volume. A set of 30 bismuth germanate detectors can be secured in any of the available sightlines, allowing for customizable coverage in experiments with runaway electrons in the energy range of 1- 60 MeV. Commissioning of the gamma ray imager includes the quantification of electromagnetic noise sources in the tokamak machine hall and a measurement of the energy spectrum of background gamma radiation. In conclusion, first measurements of gamma rays coming from the plasma provide a suitable testbed for implementing pulse height analysis that provides the energy of detected gamma photons.

  19. Gamma ray imager on the DIII-D tokamak

    DOE PAGES

    Pace, D. C.; Cooper, C. M.; Taussig, D.; ...

    2016-04-13

    A gamma ray camera is built for the DIII-D tokamak [J. Luxon, Nucl. Fusion 42, 614 (2002)] that provides spatial localization and energy resolution of gamma flux by combining a lead pinhole camera with custom-built detectors and optimized viewing geometry. This diagnostic system is installed on the outer midplane of the tokamak such that its 123 collimated sightlines extend across the tokamak radius while also covering most of the vertical extent of the plasma volume. A set of 30 bismuth germanate detectors can be secured in any of the available sightlines, allowing for customizable coverage in experiments with runaway electronsmore » in the energy range of 1- 60 MeV. Commissioning of the gamma ray imager includes the quantification of electromagnetic noise sources in the tokamak machine hall and a measurement of the energy spectrum of background gamma radiation. In conclusion, first measurements of gamma rays coming from the plasma provide a suitable testbed for implementing pulse height analysis that provides the energy of detected gamma photons.« less

  20. Gamma ray imager on the DIII-D tokamak

    NASA Astrophysics Data System (ADS)

    Pace, D. C.; Cooper, C. M.; Taussig, D.; Eidietis, N. W.; Hollmann, E. M.; Riso, V.; Van Zeeland, M. A.; Watkins, M.

    2016-04-01

    A gamma ray camera is built for the DIII-D tokamak [J. Luxon, Nucl. Fusion 42, 614 (2002)] that provides spatial localization and energy resolution of gamma flux by combining a lead pinhole camera with custom-built detectors and optimized viewing geometry. This diagnostic system is installed on the outer midplane of the tokamak such that its 123 collimated sightlines extend across the tokamak radius while also covering most of the vertical extent of the plasma volume. A set of 30 bismuth germanate detectors can be secured in any of the available sightlines, allowing for customizable coverage in experiments with runaway electrons in the energy range of 1-60 MeV. Commissioning of the gamma ray imager includes the quantification of electromagnetic noise sources in the tokamak machine hall and a measurement of the energy spectrum of background gamma radiation. First measurements of gamma rays coming from the plasma provide a suitable testbed for implementing pulse height analysis that provides the energy of detected gamma photons.

  1. Gamma ray imager on the DIII-D tokamak.

    PubMed

    Pace, D C; Cooper, C M; Taussig, D; Eidietis, N W; Hollmann, E M; Riso, V; Van Zeeland, M A; Watkins, M

    2016-04-01

    A gamma ray camera is built for the DIII-D tokamak [J. Luxon, Nucl. Fusion 42, 614 (2002)] that provides spatial localization and energy resolution of gamma flux by combining a lead pinhole camera with custom-built detectors and optimized viewing geometry. This diagnostic system is installed on the outer midplane of the tokamak such that its 123 collimated sightlines extend across the tokamak radius while also covering most of the vertical extent of the plasma volume. A set of 30 bismuth germanate detectors can be secured in any of the available sightlines, allowing for customizable coverage in experiments with runaway electrons in the energy range of 1-60 MeV. Commissioning of the gamma ray imager includes the quantification of electromagnetic noise sources in the tokamak machine hall and a measurement of the energy spectrum of background gamma radiation. First measurements of gamma rays coming from the plasma provide a suitable testbed for implementing pulse height analysis that provides the energy of detected gamma photons.

  2. WINKLER - An imaging high resolution gamma-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Nakano, G. H.; Sandie, W. G.; Kilner, J. R.; Pang, F.; Imai, B. B.

    1991-04-01

    The WINKLER high-resolution gamma-ray spectrometer was originally developed to fly on a high-altitude aircraft. Following the discovery of Supernova 1987A in the Large Magellanic Cloud, arrangements were made to perform balloon-borne observations of this event. The instrument was quickly adapted to fit on a gondola furnished by NASA/MSFC in a collaborative effort and was flown in a series of three successful flights from Alice Springs, Australia. The second flight on October 29-31, 1987 resulted in the first high-resolution detection of the 847-keV line emission from the decay of 56Co and provided definitive confirmation of the explosive nucleosynthesis process. WINKLER comprises an array of nine coaxial n-type germanium detectors which are housed in a common vaccuum cryostat and surrounded by an NaI(Tl) scintillator shield that suppresses Compton interactions and gamma-ray background. Gamma-ray images are obtained with a rotational modulation collimator system attached to the spectrometer. Collimator holes in the upper section of the shield define the angular field of view of the instrument to 22 deg FWHM. The energy range of the spectrometer is 20 eV to 8 MeV, and the composite energy resolution from all detectors is 1.5 keV at 100 keV and about 2.5 keV at 1.33 MeV. The total frontal area of the sensor array is 214 cm2 with a volume of 1177 cm3, providing sufficient detection sensitivity for gamma-ray astronomy as well as for land-based applications such as treaty verification monitoring.

  3. OBSERVATION OF DIFFUSE COSMIC AND ATMOSPHERIC GAMMA RAYS AT BALLOON ALTITUDES WITH AN ELECTRON-TRACKING COMPTON CAMERA

    SciTech Connect

    Takada, Atsushi; Nonaka, Naoki; Kubo, Hidetoshi; Nishimura, Hironobu; Ueno, Kazuki; Hattori, Kaori; Kabuki, Shigeto; Kurosawa, Shunsuke; Miuchi, Kentaro; Nagayoshi, Tsutomu; Okada, Yoko; Orito, Reiko; Sekiya, Hiroyuki; Takeda, Atsushi; Tanimori, Toru; Mizuta, Eiichi

    2011-05-20

    We observed diffuse cosmic and atmospheric gamma rays at balloon altitudes with the Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment I (SMILE-I) as the first step toward a future all-sky survey with a high sensitivity. SMILE-I employed an electron-tracking Compton camera comprised of a gaseous electron tracker as a Compton-scattering target and a scintillation camera as an absorber. The balloon carrying the SMILE-I detector was launched from the Sanriku Balloon Center of the Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency on 2006 September 1, and the flight lasted for 6.8 hr, including level flight for 4.1 hr at an altitude of 32-35 km. During the level flight, we successfully detected 420 downward gamma rays between 100 keV and 1 MeV at zenith angles below 60 deg. To obtain the flux of diffuse cosmic gamma rays, we first simulated their scattering in the atmosphere using Geant4, and for gamma rays detected at an atmospheric depth of 7.0 g cm{sup -2} we found that 50% and 21% of the gamma rays at energies of 150 keV and 1 MeV, respectively, were scattered in the atmosphere prior to reaching the detector. Moreover, by using Geant4 simulations and the QinetiQ atmospheric radiation model, we estimated that the detected events consisted of diffuse cosmic and atmospheric gamma rays (79%), secondary photons produced in the instrument through the interaction between cosmic rays and materials surrounding the detector (19%), and other particles (2%). The obtained growth curve was comparable to Ling's model, and the fluxes of diffuse cosmic and atmospheric gamma rays were consistent with the results of previous experiments. The expected detection sensitivity of a future SMILE experiment measuring gamma rays between 150 keV and 20 MeV was estimated from our SMILE-I results and was found to be 10 times better than that of other experiments at around 1 MeV.

  4. Gamma rays from grazing incidence cosmic rays in the earth's atmosphere

    NASA Technical Reports Server (NTRS)

    Ulmer, Andrew

    1994-01-01

    Interactions of grazing incidence, ultra high-energy cosmic rays with the earth's atmosphere may provide a new method of studying energetic cosmic rays with gamma-ray satellites. It is found that these cosmic ray interactions may produce gamma-rays on millisecond timescales which may be detectable by satellites. An extremely low gamma-ray background for transient gamma-ray events and a large area of interaction, the earth's surface, make the scheme plausible. The effective cross section of detection of interactions for cosmic rays above 10(exp 20) eV is found to be more than two orders of magnitude higher than Earth-based detection techniques. This method may eventually offer an efficient way of probing this region of the cosmic-ray energy spectrum where events are scarce. In this paper, a conceptual model is presented for the production of short bursts of gamma-rays based on these grazing incidence encounters with the Earth's atmosphere.

  5. Fabrication of collimators for gamma-ray imaging.

    SciTech Connect

    Makarova, O. V.; Yang, G.; Tang, C.-M.; Mancini, D. C.; Divan, R.; Yaeger, J.; Experimental Facilities Division; Creatv Micro Tech, Inc.

    2004-01-01

    Collimators capable of higher resolution and optimized for greater sensitivity can significantly improve the imaging quality of gamma-cameras for single-photon-emission computed tomography of small animals. We are applying deep x-ray lithography and gold electroforming techniques to fabricate high-resolution collimators with continuous, smooth, and thin septa. Negative SU-8 photoresist was used for mold fabrication. To be efficient, collimators for gamma-cameras designed to image 140 keV gamma-rays should be over 1.5 cm tall. The height of the collimator can be achieved by stacking the appropriate number of layers.

  6. An imaging telescope for high energy gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Frye, G.; Jenkins, T. L.; Owen, A.; Ramsden, D.; Carter, J. N.; Hall, C. J.

    1983-01-01

    Recent tests of a gamma-ray imaging telescope, which incorporated a coded aperture mask and multiwire proportional counter system produced good images of a tritium target source which was used to generate the 20 MeV protons at a proton Van de Graaff accelerator. This paper indicates what performance might be expected if a large area drift chamber were used in conjunction with a coded aperture mask. The prospects for achieving significant scientific results if such a system were flown on a variety of space vehicles are discussed.

  7. Coded-aperture Compton camera for gamma-ray imaging

    NASA Astrophysics Data System (ADS)

    Farber, Aaron M.

    This dissertation describes the development of a novel gamma-ray imaging system concept and presents results from Monte Carlo simulations of the new design. Current designs for large field-of-view gamma cameras suitable for homeland security applications implement either a coded aperture or a Compton scattering geometry to image a gamma-ray source. Both of these systems require large, expensive position-sensitive detectors in order to work effectively. By combining characteristics of both of these systems, a new design can be implemented that does not require such expensive detectors and that can be scaled down to a portable size. This new system has significant promise in homeland security, astronomy, botany and other fields, while future iterations may prove useful in medical imaging, other biological sciences and other areas, such as non-destructive testing. A proof-of-principle study of the new gamma-ray imaging system has been performed by Monte Carlo simulation. Various reconstruction methods have been explored and compared. General-Purpose Graphics-Processor-Unit (GPGPU) computation has also been incorporated. The resulting code is a primary design tool for exploring variables such as detector spacing, material selection and thickness and pixel geometry. The advancement of the system from a simple 1-dimensional simulation to a full 3-dimensional model is described. Methods of image reconstruction are discussed and results of simulations consisting of both a 4 x 4 and a 16 x 16 object space mesh have been presented. A discussion of the limitations and potential areas of further study is also presented.

  8. Detection of the Crab Nebula By UV Imaging of TeV Gamma Ray Air Showers

    NASA Astrophysics Data System (ADS)

    Chantell, M.

    1994-12-01

    With successful detection of TeV gamma ray fluxes from the Crab Nebula and the AGN, MRK421, the Whipple Observatory Gamma Ray Collaboration has demonstrated the sensitivity of the Cherenkov imaging technique in ground-based gamma-ray astronomy. This technique uses an array of 109 blue-sensitive photomultipliers to image the Cherenkov radiation produced when TeV gamma and cosmic rays enter the earth's atmosphere. One major limitation of this technique is the requirement of absolutely dark skies during observations. The presence of the moon rules out the possibility of making observations because of the high sensitivity of the photomultipliers used in the camera. To address this limitation we have developed a camera which utilizes solar-blind photomultpliers with primary sensitivity from 220nm to 280nm allowing observations even in the presence of the full moon. After two years of UV observations of the Crab Nebula we have demonstrated the ability to discriminate gamma rays from the hadronic background with an energy threshold of approximately 1 TeV. The development of this camera makes it possible to increase the duty cycle of the 10 meter telescope allowing observations in bright time. Additionally the insensitivity to background star light allows this camera to observe sources in bright regions of the galactic plane, where high background light levels have limited the usefulness of the visible camera.

  9. Atmospheric gamma ray angle and energy distributions from 2 to 25 MeV

    NASA Technical Reports Server (NTRS)

    Ryan, J. M.; Moon, S. H.; Wilson, R. B.; Zych, A. D.; White, R. S.; Dayton, B.

    1977-01-01

    Results are given for gamma ray fluxes in six energy intervals from 2-25 MeV and five zenith angle intervals from 0-50 deg (downward moving) and five from 130-180 deg (upward moving). Observations were obtained with the University of California, Riverside double Compton scatter gamma ray telescope flown on a balloon to a 3.0 g/sq cm residual atmosphere at a geomagnetic cuttoff of 4.5 GV. It was found that the angular distribution of downward moving gamma rays is relatively flat, increasing slowly from 10-40 deg. The angular distribution of the upward moving gamma rays at 4.2 g/sq cm increases with angle from the vertical. Energy distributions of upward and downward moving gamma rays are in good agreement with the results of previous studies.

  10. Atmospheric gamma ray angle and energy distributions from 2 to 25 MeV

    NASA Technical Reports Server (NTRS)

    Ryan, J. M.; Moon, S. H.; Wilson, R. B.; Zych, A. D.; White, R. S.; Dayton, B.

    1977-01-01

    Results are given for gamma ray fluxes in six energy intervals from 2-25 MeV and five zenith angle intervals from 0-50 deg (downward moving) and five from 130-180 deg (upward moving). Observations were obtained with the University of California, Riverside double Compton scatter gamma ray telescope flown on a balloon to a 3.0 g/sq cm residual atmosphere at a geomagnetic cuttoff of 4.5 GV. It was found that the angular distribution of downward moving gamma rays is relatively flat, increasing slowly from 10-40 deg. The angular distribution of the upward moving gamma rays at 4.2 g/sq cm increases with angle from the vertical. Energy distributions of upward and downward moving gamma rays are in good agreement with the results of previous studies.

  11. High-revolution gamma-ray imaging from the moon

    NASA Technical Reports Server (NTRS)

    Mahoney, William A.

    1990-01-01

    An observatory is suggested for exploiting unique lunar features to perform sensitive, subarcsecond cosmic X-ray and gamma-ray imaging. The observatory would be built in an evolutionary manner and would eventually include several different position-sensitive detector systems which together would cover a broad energy range and address a wide variety of astrophysical problems. High angular resolution would be obtained by using a mobile crane on the flat lunar mare regions to move a coded aperture mask for source tracking with detector/mask separations of up to 5 kilometers.

  12. Gamma-Ray Focusing Optics for Small Animal Imaging

    NASA Technical Reports Server (NTRS)

    Pivovaroff, M. J.; Barber, W. C.; Craig, W. W.; Hasegawa, B. H.; Ramsey, B. D.; Taylor, C.

    2004-01-01

    There is a well-established need for high-resolution radionuclide imaging techniques that provide non-invasive measurement of physiological function in small animals. We, therefore, have begun developing a small animal radionuclide imaging system using grazing incidence mirrors to focus low-energy gamma-rays emitted by I-125, and other radionuclides. Our initial prototype optic, fabricated from thermally-formed glass, demonstrated a resolution of 1500 microns, consistent with the performance predicted by detailed simulations. More recently, we have begun constructing mirrors using a replication technique that reduces low spatial frequency errors in the mirror surface, greatly improving the resolution. Each technique offers particular advantages: e.g., multilayer coatings are easily deposited on glass, while superior resolution is possible with replicated optics. Scaling the results from our prototype optics, which only have a few nested shells, to system where the lens has a full complement of several tens of nested shells, a sensitivity of approx. 1 cps/micro Ci is possible, with the exact number dependent on system magnification and radionuclide species. (Higher levels of efficiency can be obtained with multi-optic imaging systems.) The gamma-ray lens will achieve a resolution as good as 100 microns, independent of the final sensitivity. The combination of high spatial resolution and modest sensitivity will enable in vivo single photon emission imaging studies in small animals.

  13. Ionization of the Lower Martian Atmosphere by Bursts of Astrophysical Gamma-rays

    NASA Astrophysics Data System (ADS)

    Espley, J. R.; Lillis, R. J.; Connerney, J. E.; Kocevski, D.; Farrell, W.

    2009-12-01

    Powerful astrophysical events such as gamma-ray bursters, soft gamma-ray repeaters, and supernovae have been shown to have appreciable effects on planetary atmospheres. We have developed a numerical model to simulate the passage of high energy radiation through the Martian atmosphere. Based on terrestrial observations of the actual energy spectra of astrophysical gamma-ray events, we have used this model to simulate the effects of representative bursts of gamma-rays. We find that most of the gamma-rays reach the lowest parts of the Martian atmosphere and the surface. In this process, many energetic electrons (> 1 keV) are produced per precipitating photon. At Earth, it has been observed that ionization of several orders of magnitude above the background is produced at comparatively low altitudes (>20 km) by astrophysical sources. It is thus possible that powerful astrophysical events can produce significant ionization throughout an entire hemisphere of the lower Martian atmosphere. Observations of ionization at this altitude are severely limited at Mars, but observations from orbiting spacecraft at Mars are potentially useful. For example, electron spectra, magnetic field measurements, and radar soundings can indicate disturbances in the upper atmosphere. We present such observations made during observed astrophysical gamma-ray events and in some cases see unusual ionospheric signatures. We find that our results, both observational and model based, are relevant to studies of atmospheric chemistry, astrobiology, and plasma physics.

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

    SciTech Connect

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

    2010-09-17

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

  15. Coded aperture imaging in X- and gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Caroli, E.; Stephen, J. B.; Di Cocco, G.; Natalucci, L.; Spizzichino, A.

    1987-09-01

    The principles and design considerations of coded aperture imaging systems for high energy astronomy in the X-ray to gamma-ray range are reviewed. A mask consisting of an array of opaque and transparent elements set between the source fluxes and a position-sensitive detection plane is employed for image formation. Direct deconvolution techniques are discussed. Coded aperture mask designs considered include Fresnel zone plates, random pinhole masks, nonredundant and uniformly redundant arrays, and pseudonoise product masks. Various astronomical applications of coded aperture imaging systems are discussed, including the University of Birmingham coded mask X-ray telescope, the Energetic X-ray Imaging and Timing Experiment intended for the XTE satellite, and the ZEBRA coded mask telescope.

  16. 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

  17. Fermi Gamma-Ray Imaging of a Radio Galaxy

    SciTech Connect

    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, x. 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, x. 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.; Johannesson, G.; Johnson, A. S.; Johnson, T. J.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knodlseder, J.; Kocian, x. 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.; Raino, 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.; Parkinson, P. M. S.; Scargle, J. D.; Sgro, C.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Starck, J. L.; Stawarz, L.; Strickman, x. 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.

    2010-04-01

    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-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.

  18. Germanium orthogonal strip detector system for gamma-ray imaging

    NASA Astrophysics Data System (ADS)

    Hull, Ethan L.; Burks, Morgan; Cork, Chris P.; Craig, William W.; Eckels, Del; Fabris, Lorenzo; Lavietes, Anthony D.; Luke, Paul N.; Madden, Norman W.; Pehl, Richard H.; Ziock, Klaus

    2001-12-01

    A germanium-detector based, gamma-ray imaging system has been designed, fabricated, and tested. The detector, cryostat, electronics, readout, and imaging software are discussed. An 11 millimeter thick, 2 millimeter pitch 19x19 orthogonal strip planar germanium detector is used in front of a coaxial detector to provide broad energy coverage. The planar detector was fabricated using amorphous germanium contacts. Each channel is read out with a compact, low noise external FET preamplifier specially designed for this detector. A bank of shaping amplifiers, fast amplifiers, and fast leading edge discriminators were designed and fabricated to process the signals from preamplifiers. The readout system coordinates time coincident x-y strip addresses with an x-strip spectroscopy signal and a spectroscopy signal from the coaxial detector. This information is sent to a computer where an image is formed. Preliminary shadow and pinhole images demonstrate the viability of a germanium based imaging system. The excellent energy resolution of the germanium detector system provides isotopic imaging.

  19. Small Animal Radionuclide Imaging With Focusing Gamma-Ray Optics

    SciTech Connect

    Hill, R; Decker, T; Epstein, M; Ziock, K; Pivovaroff, M J; Craig, W W; Jernigan, J G; Barber, W B; Christensen, F E; Funk, T; Hailey, C J; Hasegawa, B H; Taylor, C

    2004-02-27

    Significant effort currently is being devoted to the development of noninvasive imaging systems that allow in vivo assessment of biological and biomolecular interactions in mice and other small animals. While physiological function in small animals can be localized and imaged using conventional radionuclide imaging techniques such as single-photon emission tomography (SPECT) and positron emission tomography (PET), these techniques inherently are limited to spatial resolutions of 1-2 mm. For this reason, we are developing a small animal radionuclide imaging system (SARIS) using grazing incidence optics to focus gamma-rays emitted by {sup 125}I and other radiopharmaceuticals. We have developed a prototype optic with sufficient accuracy and precision to focus the 27.5 keV photons from {sup 125}I onto a high-resolution imaging detector. Experimental measurements from the prototype have demonstrated that the optic can focus X-rays from a microfocus X-ray tube to a spot having physical dimensions (approximately 1500 microns half-power diameter) consistent with those predicted by theory. Our theoretical and numerical analysis also indicate that an optic can be designed and build that ultimately can achieve 100 {micro}m spatial resolution with sufficient efficiency to perform in vivo single photon emission imaging studies in small animal.

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

    SciTech Connect

    Reedy, R.C.

    1987-01-01

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

  1. Imaging multi-energy gamma-ray fields with a Compton scatter camera

    NASA Astrophysics Data System (ADS)

    Martin, J. B.; Dogan, N.; Gormley, J. E.; Knoll, G. F.; O'Donnell, M.; Wehe, D. K.

    1994-08-01

    Multi-energy gamma-ray fields have been imaged with a ring Compton scatter camera (RCC). The RCC is intended for industrial applications, where there is a need to image multiple gamma-ray lines from spatially extended sources. To our knowledge, the ability of a Compton scatter camera to perform this task had not previously been demonstrated. Gamma rays with different incident energies are distinguished based on the total energy deposited in the camera elements. For multiple gamma-ray lines, separate images are generated for each line energy. Random coincidences and other interfering interactions have been investigated. Camera response has been characterized for energies from 0.511 to 2.75 MeV. Different gamma-ray lines from extended sources have been measured and images reconstructed using both direct and iterative algorithms.

  2. The Gamma-Ray Imager/Polarimeter For Solar Flares (GRIPS)

    NASA Astrophysics Data System (ADS)

    Shih, Albert Y.; Lin, R. P.; Hurford, G. J.; Boggs, S. E.; Zoglauer, A. C.; Wunderer, C. B.; Sample, J. G.; Turin, P.; McBride, S.; Smith, D. M.; Tajima, H.; Luke, P. N.; Amman, M. S.

    2009-01-01

    The new balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from 20 keV to > 10 MeV. GRIPS will address questions relevant to particle acceleration and energy release that have been raised by recent solar flare observations, such as: What causes the spatial separation between energetic electron producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the accelerated electrons, and why do relativistic electron dominate in the corona? How does the composition of accelerated and ambient material vary with space and time, and why? The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM) situated 8 meters from the spectrometer to provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), using a similar technique to rotating-modulation-collimator imaging used on missions such as RHESSI but now taking advantage of the position sensitivity of the spectrometer. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e. as an active scatterer). A balloon platform for this instrument minimizes atmospheric attenuation and accommodates its weight and size, and long-duration balloon flights (LDBFs) from Antarctica allow for month-long uninterrupted observations of the Sun to continuously observe active regions and to maximize the chance of capturing a gamma-ray flare. A continental-US test flight is slated for 2012 with the eventual goal of Antarctic LDBFs of the completed instrument. In addition to the direct science return from these flights, GRIPS will prove these technologies for a future space

  3. The Gamma-Ray Imager/Polarimeter For Solar Flares (GRIPS)

    NASA Astrophysics Data System (ADS)

    Shih, Albert Y.; Lin, R. P.; Hurford, G. J.; Boggs, S. E.; Zoglauer, A. C.; Wunderer, C. B.; Sample, J. G.; Turin, P.; McBride, S.; Smith, D. M.; Tajima, H.; Luke, P. N.; Amman, M. S.

    2009-05-01

    The new balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from 20 keV to > 10 MeV. GRIPS will address questions relevant to particle acceleration and energy release that have been raised by recent solar flare observations, such as: What causes the spatial separation between energetic electron producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the accelerated electrons, and why do relativistic electron dominate in the corona? How does the composition of accelerated and ambient material vary with space and time, and why? The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM) situated 8 meters from the spectrometer to provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), using a similar technique to rotating-modulation-collimator imaging used on missions such as RHESSI but now taking advantage of the position sensitivity of the spectrometer. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e. as an active scatterer). A balloon platform for this instrument minimizes atmospheric attenuation and accommodates its weight and size, and long-duration balloon flights (LDBFs) from Antarctica allow for month-long uninterrupted observations of the Sun to continuously observe active regions and to maximize the chance of capturing a gamma-ray flare. A continental-US test flight is slated for 2012 with the eventual goal of Antarctic LDBFs of the completed instrument. In addition to the direct science return from these flights, GRIPS will prove these technologies for a future space

  4. Scene data fusion: Real-time standoff volumetric gamma-ray imaging

    NASA Astrophysics Data System (ADS)

    Barnowski, Ross; Haefner, Andrew; Mihailescu, Lucian; Vetter, Kai

    2015-11-01

    An approach to gamma-ray imaging has been developed that enables near real-time volumetric (3D) imaging of unknown environments thus improving the utility of gamma-ray imaging for source-search and radiation mapping applications. The approach, herein dubbed scene data fusion (SDF), is based on integrating mobile radiation imagers with real-time tracking and scene reconstruction algorithms to enable a mobile mode of operation and 3D localization of gamma-ray sources. A 3D model of the scene, provided in real-time by a simultaneous localization and mapping (SLAM) algorithm, is incorporated into the image reconstruction reducing the reconstruction time and improving imaging performance. The SDF concept is demonstrated in this work with a Microsoft Kinect RGB-D sensor, a real-time SLAM solver, and a cart-based Compton imaging platform comprised of two 3D position-sensitive high purity germanium (HPGe) detectors. An iterative algorithm based on Compton kinematics is used to reconstruct the gamma-ray source distribution in all three spatial dimensions. SDF advances the real-world applicability of gamma-ray imaging for many search, mapping, and verification scenarios by improving the tractiblity of the gamma-ray image reconstruction and providing context for the 3D localization of gamma-ray sources within the environment in real-time.

  5. Gamma-ray Emission of the Earth's Upper Atmosphere in Geographical Coordinates with Fermi-LAT

    NASA Astrophysics Data System (ADS)

    Madlee, S.; Mitthumsiri, W.; Digel, S.; Ruffolo, D. J.

    2016-12-01

    The Earth is extremely bright in gamma rays as viewed by the Fermi Large Area Telescope (LAT). This gamma-ray emission of the Earth is produced by the interactions of cosmic rays (CRs), high-energy particles in space, with the Earth's upper atmosphere. Here we analyze the Earth's photons in the geographical coordinate system (latitude and longitude) from 58 months of data, using the latest version of the LAT event selection (Pass 8). Preliminary results of our analysis, which are the gamma-ray intensity maps of the Earth at energies from 1 to 10 GeV, will be presented. This study provides a better understanding of the geomagnetic field, the Earth's upper atmosphere, and CRs. This project is partially supported by the Thailand Research Fund (Grant TRG5880173 and RTA5980003).

  6. Design upgrades to the DIII-D gamma ray imager

    NASA Astrophysics Data System (ADS)

    Lvovskiy, A.; Cooper, C. M.; Eidietis, N. W.; Pace, D.; Paz-Soldan, C.

    2016-10-01

    Generation of runaway electrons (RE) in tokamak disruptions can cause damage of plasma facing components. RE studies are necessary in order to provide a reliable mechanism of RE mitigation. For that task a gamma ray imager (GRI) has been developed for DIII-D. It measures the bremsstrahlung emission by RE providing information on RE energy spectrum and RE distribution across a poloidal cross-section. The GRI consists of a lead pinhole camera illuminating a 2D array of 30 BGO detectors placed in the DIII-D mid-plane. First results showed the successful measurements of RE energy spectra in the range 1 - 60 MeV with time resolution 100 μs. They have been obtained in the low-flux quiescent RE regime via pulse-high analysis. The measurements in the high gamma flux post-disruption RE regime showed strong signal saturation. Here we present GRI design upgrades towards signal attenuation and better detector shielding including Monte-Carlo Neutral Particle modeling of GRI irradiation, as well as improved calibration techniques and options to improve electronic noise rejection. Work supported by US DOE under DE-AC05-06OR23100 and DE-FC02-04ER54698.

  7. Gamma-ray imaging system. Innovative technology summary report

    SciTech Connect

    1998-11-01

    The RadScan 600 gamma-ray imaging system is designed to survey large surface areas for radiological contamination with accuracy and efficiency. The resulting survey data are clear, concise, and precise in describing how much contamination is present at exact locations. Data can be permanently stored electronically and on video tape, making storage and retrieval economical and efficient. This technology can perform accurate measurements in high radiation contamination areas while minimizing worker exposure. The RadScan 600 system is a safe and effective alternative to hand-held radiation detection devices. Performance data of the demonstrated survey area of the RadScan 600 system versus the baseline, which is the hand-held radiation detection devices (RO-2 and RO-7) for a given survey, production rate is 72% of the baseline. It should be noted that the innovative technology provides 100% coverage at a unit cost of $8.64/m{sup 2} versus a static measurement of a unit cost of $1.61/m{sup 2} for the baseline.

  8. Image Artifacts Resulting from Gamma-Ray Tracking Algorithms Used with Compton Imagers

    SciTech Connect

    Seifert, Carolyn E.; He, Zhong

    2005-10-01

    For Compton imaging it is necessary to determine the sequence of gamma-ray interactions in a single detector or array of detectors. This can be done by time-of-flight measurements if the interactions are sufficiently far apart. However, in small detectors the time between interactions can be too small to measure, and other means of gamma-ray sequencing must be used. In this work, several popular sequencing algorithms are reviewed for sequences with two observed events and three or more observed events in the detector. These algorithms can result in poor imaging resolution and introduce artifacts in the backprojection images. The effects of gamma-ray tracking algorithms on Compton imaging are explored in the context of the 4π Compton imager built by the University of Michigan.

  9. Instrumental and atmospheric background lines observed by the SMM gamma-ray spectrometer

    NASA Technical Reports Server (NTRS)

    Share, G. H.; Kinzer, R. L.; Strickman, M. S.; Letaw, J. R.; Chupp, E. L.

    1989-01-01

    Preliminary identifications of instrumental and atmospheric background lines detected by the gamma-ray spectrometer on NASA's Solar Maximum Mission satellite (SMM) are presented. The long-term and stable operation of this experiment has provided data of high quality for use in this analysis. Methods are described for identifying radioactive isotopes which use their different decay times. Temporal evolution of the features are revealed by spectral comparisons, subtractions, and fits. An understanding of these temporal variations has enabled the data to be used for detecting celestial gamma-ray sources.

  10. Electron Trajectory Reconstruction for Advanced Compton Imaging of Gamma Rays

    NASA Astrophysics Data System (ADS)

    Plimley, Brian Christopher

    Gamma-ray imaging is useful for detecting, characterizing, and localizing sources in a variety of fields, including nuclear physics, security, nuclear accident response, nuclear medicine, and astronomy. Compton imaging in particular provides sensitivity to weak sources and good angular resolution in a large field of view. However, the photon origin in a single event sequence is normally only limited to the surface of a cone. If the initial direction of the Compton-scattered electron can be measured, the cone can be reduced to a cone segment with width depending on the uncertainty in the direction measurement, providing a corresponding increase in imaging sensitivity. Measurement of the electron's initial direction in an efficient detection material requires very fine position resolution due to the electron's short range and tortuous path. A thick (650 mum), fully-depleted charge-coupled device (CCD) developed for infrared astronomy has 10.5-mum position resolution in two dimensions, enabling the initial trajectory measurement of electrons of energy as low as 100 keV. This is the first time the initial trajectories of electrons of such low energies have been measured in a solid material. In this work, the CCD's efficacy as a gamma-ray detector is demonstrated experimentally, using a reconstruction algorithm to measure the initial electron direction from the CCD track image. In addition, models of fast electron interaction physics, charge transport and readout were used to generate modeled tracks with known initial direction. These modeled tracks allowed the development and refinement of the reconstruction algorithm. The angular sensitivity of the reconstruction algorithm is evaluated extensively with models for tracks below 480 keV, showing a FWHM as low as 20° in the pixel plane, and 30° RMS sensitivity to the magnitude of the out-of-plane angle. The measurement of the trajectories of electrons with energies as low as 100 keV have the potential to make electron

  11. On the potential of atmospheric Cherenkov telescope arrays for resolving TeV gamma-ray sources in the Galactic plane

    NASA Astrophysics Data System (ADS)

    Ambrogi, L.; De Oña Wilhelmi, E.; Aharonian, F.

    2016-07-01

    The potential of an array of imaging atmospheric Cherenkov telescopes to detect gamma-ray sources in complex regions has been investigated. The basic characteristics of the gamma-ray instrument have been parameterized using simple analytic representations. In addition to the ideal (Gaussian form) point spread function (PSF), the impact of more realistic non-Gaussian PSFs with tails has been considered. Simulations of isolated point-like and extended sources have been used as a benchmark to test and understand the response of the instrument. The capability of the instrument to resolve multiple sources has been analyzed and the corresponding instrument sensitivities calculated. The results are of particular interest for weak gamma-ray emitters located in crowded regions of the Galactic plane, where the chance of clustering of two or more gamma-ray sources within 1 deg is high.

  12. An experimental assessment of the imaging quality of the low energy gamma-ray telescope ZEBRA

    NASA Technical Reports Server (NTRS)

    Butler, R. C.; Caroli, E.; Dicocco, G.; Natalucci, L.; Spada, G.; Spizzichino, A.; Stephen, J. B.; Carter, J. N.; Charalambous, P. M.; Dean, A. J.

    1985-01-01

    One gamma-ray detection plane of the ZEBRA telescope, consisting of nine position sensitive scintillation crystal bars designed to operate over the spectral range 0.2 to 10 MeV, has been constructed in the laboratory. A series of experimental images has been generated using a scaled down flight pattern mask in conjunction with a diverging gamma-ray beam. Point and extended sources have been imaged in order to assess quantitatively the performance of the system.

  13. Recent results with a combined gamma-ray and neutron imaging detector

    NASA Astrophysics Data System (ADS)

    Soundara-Pandian, L.; Whitney, C. M.; Johnson, E. B.; Vinci, R.; Glodo, J.; Christian, J. F.; Gervais, J.; Vogel, Sam; Nagarkar, E.; Robertson, F.; Squillante, M. S.; Waer, P.; Squillante, M. R.

    2014-09-01

    Numerous instruments have been developed for performing gamma-ray imaging and neutron imaging for research, nondestructive testing, medicine and national security. However, none are capable of imaging gamma-rays and neutrons simultaneously while also discriminating gamma-rays from the neutron. This paper will describe recent experimental results obtained using a gamma/neutron camera based on Cs2LiYCl6:Ce (CLYC) scintillation crystals, which can discriminate gamma-rays from neutrons. The ability to do this while also having good energy resolution provides a powerful capability for detecting and identifying shielded special nuclear materials for security applications. Also discussed are results obtained using a LaBr3 scintillation crystal.

  14. 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.

  15. 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.

  16. Prompt gamma ray imaging for verification of proton boron fusion therapy: A Monte Carlo study.

    PubMed

    Shin, Han-Back; Yoon, Do-Kun; Jung, Joo-Young; Kim, Moo-Sub; Suh, Tae Suk

    2016-10-01

    The purpose of this study was to verify acquisition feasibility of a single photon emission computed tomography image using prompt gamma rays for proton boron fusion therapy (PBFT) and to confirm an enhanced therapeutic effect of PBFT by comparison with conventional proton therapy without use of boron. Monte Carlo simulation was performed to acquire reconstructed image during PBFT. We acquired percentage depth dose (PDD) of the proton beams in a water phantom, energy spectrum of the prompt gamma rays, and tomographic images, including the boron uptake region (BUR; target). The prompt gamma ray image was reconstructed using maximum likelihood expectation maximisation (MLEM) with 64 projection raw data. To verify the reconstructed image, both an image profile and contrast analysis according to the iteration number were conducted. In addition, the physical distance between two BURs in the region of interest of each BUR was measured. The PDD of the proton beam from the water phantom including the BURs shows more efficient than that of conventional proton therapy on tumour region. A 719keV prompt gamma ray peak was clearly observed in the prompt gamma ray energy spectrum. The prompt gamma ray image was reconstructed successfully using 64 projections. Different image profiles including two BURs were acquired from the reconstructed image according to the iteration number. We confirmed successful acquisition of a prompt gamma ray image during PBFT. In addition, the quantitative image analysis results showed relatively good performance for further study. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  17. Gamma ray flashes add to mystery of upper atmosphere

    NASA Astrophysics Data System (ADS)

    Atmospheric electricity research has come a long way since Benjamin Franklin's kite-flying days. But what researchers have been learning lately about above-thunderstorm electricity has wrought a whole new era of mysteries.For a start, last summer a Colorado meteorologist sparked interest in a terrestrial phenomenon that the community first observed more than 100 years ago: optical flashes that occur above thunderstorms—at least 30 km above Earth. Walter Lyons with the Ft. Collins-based Mission Research Corporation, demonstrated that such flashes are not anomalies, as conventional scientific wisdom had held. He filmed hundreds of flashes during a 2-week period.

  18. A Topological Array Trigger for AGIS, the Advanced Gamma ray Imaging System

    SciTech Connect

    Krennrich, F.; Anderson, J.; Byrum, K.; Dawson, J.; Drake, G.; Haberichter, W.; Kreps, A.; Smith, A.; Buckley, J.; Krawczynski, H.; Imran, A.; Schroedter, M.

    2008-12-24

    Next generation ground based {gamma}-ray observatories such as AGIS{sup 1} and CTA{sup 2} are expected to cover a 1 km{sup 2} area with 50-100 imaging atmospheric Cherenkov telescopes. The stereoscopic view ol air showers using multiple view points raises the possibility to use a topological array trigger that adds substantial flexibility, new background suppression capabilities and a reduced energy threshold. In this paper we report on the concept and technical implementation of a fast topological trigger system, that makes use of real time image processing of individual camera patterns and their combination in a stereoscopic array analysis. A prototype system is currently under construction and we discuss the design and hardware of this topological array trigger system.

  19. Single-Grid-Pair Fourier Telescope for Imaging in Hard-X Rays and gamma Rays

    NASA Technical Reports Server (NTRS)

    Campbell, Jonathan

    2008-01-01

    This instrument, a proposed Fourier telescope for imaging in hard-x rays and gamma rays, would contain only one pair of grids made of an appropriate radiation-absorpting/ scattering material, in contradistinction to multiple pairs of such as grids in prior Fourier x- and gamma-ray telescopes. This instrument would also include a relatively coarse gridlike image detector appropriate to the radiant flux to be imaged. Notwithstanding the smaller number of grids and the relative coarseness of the imaging detector, the images produced by the proposed instrument would be of higher quality.

  20. The Advanced Gamma-ray Imaging System (AGIS) Telescope Optical System Designs

    SciTech Connect

    Bugaev, V.; Buckley, J.; Krawczynski, H.; Diegel, S.; Romani, R.; Falcone, A.; Fegan, S.; Vassiliev, V.; Finley, J.; Guarino, V.; Hanna, D.; Kaaret, P.; Konopelko, A.; Ramsey, B.; Weekes, T.

    2008-12-24

    AGIS is a conceptual design for a future ground-based gamma-ray observatory operating in the energy range 25 GeV-100 TeV, which is based on an array of {approx}20-100 imaging atmospheric Cherenkov telescopes (IACTs). The desired improvement in sensitivity, angular resolution, and reliability of operation of AGIS imposes demanding technological and cost requirements on the design of the IACTs. We are considering several options for the optical system (OS) of the AGIS telescopes, which include the traditional Davies-Cotton design as well as novel two-mirror design. Emerging mirror production technologies based on replication processes such as cold and hot glass slumping, cured carbon fiber reinforced plastic (CFRP), and electroforming provide new opportunities for cost-effective solutions for the design of the OS.

  1. Atmospheric transport of neutrons and gamma rays from a high-altitude nuclear detonation

    SciTech Connect

    Byrd, R.C.

    1995-07-01

    Although radiation outputs from nuclear detonations in free space are well established, few studies exist of effect of atmospheric transport on the resulting intensity, energy, and time signatures. This report presents calculations for generic sources at high altitudes, 20-50 km above the Earth`s surface, in an atmosphere whose density decreases almost exponentially with height. The sources are instantaneous time bursts with simple energy dependences: gamma rays use an evaporation spectrum; neutrons use either a Gaussian fusion or a Maxwell fission spectrum. The observation angles vary from vertical to 5{degrees} below the horizon, and detectors are placed in either geosynchronous or low Earth orbits (100 km). All calculations use the Monte Carlo N-Particle (MCNP) transport code in either its photon, neutron, or coupled neutron-photon modes, with the coupled mode being applied to the production of gamma rays by neutron inelastic scattering. The standard MCNP outputs are analyzed to extract the intensity, energy, and time dependences of the fluence as functions of either source altitude or observation angle. In general, the intensities drop rapidly below about 30-km source altitude or +5` slant angle. Above these limits, the gamma-ray signal loses substantial intensity but still contains most of the original source information. In contrast, neutron scattering produces little or no decrease in intensity, but it rapidly degrades much of the information about the original source spectrum. Finally, although there is abundant gamma-ray production from neutron inelastic scattering, the resulting signatures appear to provide little additional information.

  2. Gamma-ray waveguides

    SciTech Connect

    Tournear, D. M.; Hoffbauer, M. A.; Akhadov, E. A.; Chen, A. T.; Pendleton, S. J.; Williamson, T. L.; Cha, K. C.; Epstein, R. I.

    2008-04-14

    We have developed an approach for gamma-ray optics using layered structures acting as planar waveguides. Experiments demonstrating channeling of 122 keV gamma rays in two prototype waveguides validate the feasibility of this technology. Gamma-ray waveguides allow one to control the direction of radiation up to a few MeV. The waveguides are conceptually similar to polycapillary optics, but can function at higher gamma-ray energies. Optics comprised of these waveguides will be able to collect radiation from small solid angles or concentrate radiation into small area detectors. Gamma-ray waveguides may find applications in medical imaging and treatment, astrophysics, and homeland security.

  3. The Use of Gamma-Ray Imaging to Improve Portal Monitor Performance

    SciTech Connect

    Ziock, Klaus-Peter; Collins, Jeff; Fabris, Lorenzo; Gee, Timothy Felix; Goddard, James K; Habte Ghebretatios, Frezghi; Karnowski, Thomas Paul

    2008-01-01

    We have constructed a prototype, rapid-deployment portal monitor that uses visible-light and gamma-ray imaging to allow simultaneous monitoring of multiple lanes of traffic from the side of a roadway. Our Roadside Tracker uses automated target acquisition and tracking (TAT) software to identify and track vehicles in visible light images. The field of view of the visible camera overlaps with and is calibrated to that of a one-dimensional gamma-ray imager. The TAT code passes information on when vehicles enter and exit the system field of view and when they cross gamma-ray pixel boundaries. Based on this in-formation, the gamma-ray imager "harvests" the gamma-ray data specific to each vehicle, integrating its radiation signature for the entire time that it is in the field of view. In this fashion we are able to generate vehicle-specific radiation signatures and avoid source confusion problems that plague nonimaging approaches to the same problem.

  4. A coded aperture imaging system optimized for hard X-ray and gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Cline, T. L.; Huters, A. F.; Leventhal, M.; Maccallum, C. J.; Reber, J. D.; Stang, P. D.; Teegarden, B. J.; Tueller, J.

    1985-01-01

    A coded aperture imaging system was designed for the Gamma-Ray imaging spectrometer (GRIS). The system is optimized for imaging 511 keV positron-annihilation photons. For a galactic center 511-keV source strength of 0.001 sq/s, the source location accuracy is expected to be + or - 0.2 deg.

  5. Development and Evaluation of Real-Time Volumetric Compton Gamma-Ray Imaging

    NASA Astrophysics Data System (ADS)

    Barnowski, Ross Wegner

    An approach to gamma-ray imaging has been developed that enables near real-time volumetric (3D) imaging of unknown environments thus improving the utility of gamma-ray imaging for source-search and radiation mapping applications. The approach, herein dubbed scene data fusion (SDF), is based on integrating mobile radiation imagers with real time tracking and scene reconstruction algorithms to enable a mobile mode of operation and 3D localization of gamma-ray sources. The real-time tracking allows the imager to be moved throughout the environment or around a particular object of interest, obtaining the multiple perspectives necessary for standoff 3D imaging. A 3D model of the scene, provided in real-time by a simultaneous localization and mapping (SLAM) algorithm, can be incorporated into the image reconstruction reducing the reconstruction time and improving imaging performance. The SDF concept is demonstrated in this work with a Microsoft Kinect RGB-D sensor, a real-time SLAM solver, and two different mobile gamma-ray imaging platforms. The first is a cart-based imaging platform known as the Volumetric Compton Imager (VCI), comprising two 3D position-sensitive high purity germanium (HPGe) detectors, exhibiting excellent gamma-ray imaging characteristics, but with limited mobility due to the size and weight of the cart. The second system is the High Efficiency Multimodal Imager (HEMI) a hand-portable gamma-ray imager comprising 96 individual cm3 CdZnTe crystals arranged in a two-plane, active-mask configuration. The HEMI instrument has poorer energy and angular resolution than the VCI, but is truly hand-portable, allowing the SDF concept to be tested in multiple environments and for more challenging imaging scenarios. An iterative algorithm based on Compton kinematics is used to reconstruct the gamma-ray source distribution in all three spatial dimensions. Each of the two mobile imaging systems are used to demonstrate SDF for a variety of scenarios, including

  6. New observations with the gamma ray imager SIGMA

    NASA Technical Reports Server (NTRS)

    Roques, J. P.; Vedrenne, G.

    1992-01-01

    Results from the use of the gamma ray telescope SIGMA are given. An identification and an extensive study was done of sources contributing to the emission of the Galactic center region above 30 keV. A strong line was observed at 480 keV from Nova Muscae, which may be interpreted as an annihilation line with a redshift due to the presence of a compact object. The soft x-ray tails observed by SIGMA in some transient sources already identified as soft x-ray transients might be a common characteristic of these objects and has to be explained. The unusual spectrum of NGC4151 with a break around 50 keV can characterize a particular state of this kind of object. If it is the case, it has interesting implications for the origin of the Cosmic Diffuse Background.

  7. The gamma-ray observatory

    NASA Technical Reports Server (NTRS)

    1991-01-01

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

  8. ICF ignition capsule neutron, gamma ray, and high energy x-ray images

    NASA Astrophysics Data System (ADS)

    Bradley, P. A.; Wilson, D. C.; Swenson, F. J.; Morgan, G. L.

    2003-03-01

    Post-processed total neutron, RIF neutron, gamma-ray, and x-ray images from 2D LASNEX calculations of burning ignition capsules are presented. The capsules have yields ranging from tens of kilojoules (failures) to over 16 MJ (ignition), and their implosion symmetry ranges from prolate (flattest at the hohlraum equator) to oblate (flattest towards the laser entrance hole). The simulated total neutron images emphasize regions of high DT density and temperature; the reaction-in-flight neutrons emphasize regions of high DT density; the gamma rays emphasize regions of high shell density; and the high energy x rays (>10 keV) emphasize regions of high temperature.

  9. The Advanced Gamma-ray Imaging System (AGIS)--Science Highlights

    SciTech Connect

    Buckley, J.; Krawczynski, H.; Coppi, P.; Digel, S.; Funk, S.; Krennrich, F.; Pohl, M.; Romani, R.; Vassiliev, V.

    2008-12-24

    The Advanced Gamma-ray Imaging System (AGIS), a future gamma-ray telescope consisting of an array of {approx}50 atmospheric Cherenkov telescopes distributed over an area of {approx}1 km{sup 2}, will provide a powerful new tool for exploring the high-energy universe. The order-of-magnitude increase in sensitivity and improved angular resolution could provide the first detailed images of {gamma}-ray emission from other nearby galaxies or galaxy clusters. The large effective area will provide unprecedented sensitivity to short transients (such as flares from AGNs and GRBs) probing both intrinsic spectral variability (revealing the details of the acceleration mechanism and geometry) as well as constraining the high-energy dispersion in the velocity of light (probing the structure of spacetime and Lorentz invariance). A wide field of view ({approx}4 times that of current instruments) and excellent angular resolution (several times better than current instruments) will allow for an unprecedented survey of the Galactic plane, providing a deep unobscured survey of SNRs, X-ray binaries, pulsar-wind nebulae, molecular cloud complexes and other sources. The differential flux sensitivity of {approx}10{sup -13} erg cm{sup -2} sec{sup -1} will rival the most sensitive X-ray instruments for these extended Galactic sources. The excellent capabilities of AGIS at energies below 100 GeV will provide sensitivity to AGN and GRBs out to cosmological redshifts, increasing the number of AGNs detected at high energies from about 20 to more than 100, permitting population studies that will provide valuable insights into both a unified model for AGN and a detailed measurement of the effects of intergalactic absorption from the diffuse extragalactic background light. A new instrument with fast-slewing wide-field telescopes could provide detections of a number of long-duration GRBs providing important physical constraints from this new spectral component. The new array will also have excellent

  10. Compact Gamma-Ray Imager for In-Vivo Gene Imaging

    SciTech Connect

    Greenwald, A. C.

    2000-06-01

    A compact, low-cost, gamma-ray imaging system is needed to study gene expression in small animals. State-of-the-art electronic imaging systems have insufficient resolution and animals must be sacrificed for detailed imaging that precludes time evolution studies. With improved electronics radioactive tracers attached to gene markers can be used to track the absorption and mobility of gene therapy medications in live animals. Other instrumentation being developed for medical applications does not have the response to match the radiation source for this work. The objective of this research was to develop thick film (Cd,Zn)Te detectors matched to the gamma ray energy of {sup 129}I. The detector would be a direct readout device using p-i-n diodes formed from the high Z material absorbing the radiation, with separate readout. Higher quality semiconducting material was expected from epitaxial growth on GaAs, a near lattice matched substrate. In practice, it was difficult to obtain material with high resistance and low leakage current. Spire Corporation achieved the goal of fabricating working detectors in (Cd,Zn)Te deposited on GaAs. The spectra of an alpha emitter ({sup 225}Am) was adequately resolved in thin film devices. Thick p-i-n diodes were fabricated but other processing problems prevented full demonstration of a gamma ray detector.

  11. Gamma ray transients

    NASA Technical Reports Server (NTRS)

    Cline, Thomas L.

    1987-01-01

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

  12. Development of a high resolution liquid xenon imaging chamber for gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Aprile, Elena

    1991-01-01

    The objective was to develop the technology of liquid xenon (LXe) detectors for spectroscopy and imaging of gamma rays from astrophysical sources emitting in the low to medium energy regime. In particular, the technical challenges and the physical processes relevant to the realization of the LXe detector operated as a Time Projection Chamber (TPC) were addressed and studied. Experimental results were obtained on the following topics: (1) long distance drift of free electrons in LXe (purity); (2) scintillation light yield for electrons and alphas in LXe (triggering); and (3) ionization yield for electrons and gamma rays in LXe (energy resolution). The major results from the investigations are summarized.

  13. Extra-light gamma-ray imager for safeguards and homeland security

    SciTech Connect

    Ivanov, Oleg P.; Semin, Ilya A.; Potapov, Victor N.; Stepanov, Vyacheslav E.

    2015-07-01

    Gamma-ray imaging is the most important way to identify unknown gamma-ray emitting objects in decommissioning, security, overcoming accidents. Over the past two decades a system for producing of gamma images in these conditions became more or less portable devices. But in recent years these systems have become the hand-held devices. This is very important, especially in emergency situations, and measurements for safety reasons. We describe the first integrated hand-held instrument for emergency and security applications. The device is based on the coded aperture image formation, position sensitive gamma-ray (X-ray) detector Medipix2 (detectors produces by X-ray Imaging Europe) and tablet computer. The development was aimed at creating a very low weight system with high angular resolution. We present some sample gamma-ray images by camera. Main estimated parameters of the system are the following. The field of view video channel ∼ 490 deg. The field of view gamma channel ∼ 300 deg. The sensitivity of the system with a hexagonal mask for the source of Cs-137 (Eg = 662 keV), is in units of dose D ∼ 100 mR. This option is less then order of magnitude worse than for the heavy, non-hand-held systems (e.g., gamma-camera Cartogam, by Canberra.) The angular resolution of the gamma channel for the sources of Cs-137 (Eg = 662 keV) is about 1.20 deg. (authors)

  14. Imaging performance of the ASIM/MXGS gamma-ray imager using Co57 sources

    NASA Astrophysics Data System (ADS)

    Connell, Paul; Kuvvetl, Irfan

    2017-04-01

    In August/September 2017 the MXGS gamma-ray location imager of the ASIM mission to the ISS, due for launch in late 2017, was exposed to Co57 point and diffuse sources at various locations in the MXGS field of view to test its data acquisition and angular location accuracy. We present here an overview of the test program, the MXGS coded mask geometry and its imaging characteristics, the mathematical imaging methods used, along with location scatter plots and radial error estimates.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  16. A multiple-plate, multiple-pinhole camera for X-ray gamma-ray imaging

    NASA Technical Reports Server (NTRS)

    Hoover, R. B.

    1971-01-01

    Plates with identical patterns of precisely aligned pinholes constitute lens system which, when rotated about optical axis, produces continuous high resolution image of small energy X-ray or gamma ray source. Camera has applications in radiation treatment and nuclear medicine.

  17. High spatial resolution X-ray and gamma ray imaging system using diffraction crystals

    DOEpatents

    Smither, Robert K [Hinsdale, IL

    2011-05-17

    A method and a device for high spatial resolution imaging of a plurality of sources of x-ray and gamma-ray radiation are provided. The device comprises a plurality of arrays, with each array comprising a plurality of elements comprising a first collimator, a diffracting crystal, a second collimator, and a detector.

  18. Imaging with the coded aperture gamma-ray spectrometer SPI aboard INTEGRAL

    NASA Astrophysics Data System (ADS)

    Wunderer, Cornelia B.; Strong, Andrew W.; Attie, David; von Ballmoos, Peter; Connell, Paul; Cordier, Bertrand; Diehl, Roland; Hammer, J. Wolfgang; Jean, Pierre; von Kienlin, Andreas; Knoedlseder, Juergen; Lichti, Giselher G.; Mandrou, Pierre; Paul, Jaques; Paul, Philippe; Reglero, Victor; Roques, Jean-Pierre; Sanchez, Filomeno; Schanne, Stephane; Schoenfelder, Volker; Shrader, Chris; Skinner, Gerald K.; Sturner, Steven J.; Teegarden, Bonnard J.; Vedrenne, Gilbert; Weidenspointner, Georg

    2003-03-01

    ESA's INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) will be launched in October 2002. Its two main instruments are the imager IBIS and the spectrometer SPI. Both emply coded apertures to obtain directional information on the incoming radiation. SPI's detection plane consists of 19 hexagonal Ge detectors, its coded aperture has 63 tungsten-alloy elements of 30 mm thickness.

  19. Handheld real-time volumetric 3-D gamma-ray imaging

    NASA Astrophysics Data System (ADS)

    Haefner, Andrew; Barnowski, Ross; Luke, Paul; Amman, Mark; Vetter, Kai

    2017-06-01

    This paper presents the concept of real-time fusion of gamma-ray imaging and visual scene data for a hand-held mobile Compton imaging system in 3-D. The ability to obtain and integrate both gamma-ray and scene data from a mobile platform enables improved capabilities in the localization and mapping of radioactive materials. This not only enhances the ability to localize these materials, but it also provides important contextual information of the scene which once acquired can be reviewed and further analyzed subsequently. To demonstrate these concepts, the high-efficiency multimode imager (HEMI) is used in a hand-portable implementation in combination with a Microsoft Kinect sensor. This sensor, in conjunction with open-source software, provides the ability to create a 3-D model of the scene and to track the position and orientation of HEMI in real-time. By combining the gamma-ray data and visual data, accurate 3-D maps of gamma-ray sources are produced in real-time. This approach is extended to map the location of radioactive materials within objects with unknown geometry.

  20. Imaging with INTEGRAL. [instrument for fine spectroscopy of celestial gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Dean, A. J.

    1993-01-01

    The INTEGRAL mission was proposed in response to the ESA M2 call for proposals and is dedicated to the fine spectroscopy and imaging of celestial gamma-ray sources in the energy range 15 keV to 10 MeV. Cosmic gamma-rays are emitted on a wide range of angular scales and structures for a diverse population of astronomical objects. The emission, which includes discrete spectral lines and continuum radiation is derived from point sources, localized regions, as well as a diffuse band along the Galactic plane. Much of the gamma-ray sky is composed from transient phenomena which range from the few second timescale associated with gamma-ray bursts to larger lived events lasting some days or more. These class of events pose the challenge of firstly identification and secondly that of precise positional location of 'random' short lived events which arrive isotropically. In this article the imaging requirements are evaluated in light of current observational astronomical data and practical solutions for the INTEGRAL telescope are discussed. Some of the key problems are highlighted.

  1. An investigation of the possibility of detecting gamma-ray flashes originating from the atmosphere of Venus

    NASA Astrophysics Data System (ADS)

    Bagheri, Mahdi; Dwyer, Joseph R.

    2016-09-01

    The Runaway Electrons Avalanche Model Monte Carlo simulation is used to study the propagation of runaway electrons and gamma-ray flashes originating from the atmosphere of Venus, and the possibility of detecting these high-energy gamma rays at low-Venus orbit is also investigated. Relativistic Runaway Electron Avalanche (RREA) lengths and energy spectra at the Venus middle cloud levels have similar values to those of Earth at sea level, with a similar RREA threshold electric field ( 286 kV/m). If electrified clouds in Venus make similar numbers of gamma rays as are made by thunderstorms on Earth during Terrestrial Gamma-ray Flashes (TGFs), then the calculated gamma-ray fluences at low-Venus orbit ( 550 km) have an approximate range of 10-3 photons/cm2 to 4 photons/cm2 for the source altitude between 58 km and 70 km. These gamma-ray fluences are similar to those measured by spacecraft in low-Earth orbit from TGFs. Therefore, if TGF-like events initiate in the middle and upper clouds of Venus, they would be detectable by spacecrafts at low-Venus orbit.

  2. Enhanced Analysis Techniques for an Imaging Neutron and Gamma Ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Madden, Amanda C.

    The presence of gamma rays and neutrons is a strong indicator of the presence of Special Nuclear Material (SNM). The imaging Neutron and gamma ray SPECTrometer (NSPECT) developed by the University of New Hampshire and Michigan Aerospace corporation detects the fast neutrons and prompt gamma rays from fissile material, and the gamma rays from radioactive material. The instrument operates as a double scatter device, requiring a neutron or a gamma ray to interact twice in the instrument. While this detection requirement decreases the efficiency of the instrument, it offers superior background rejection and the ability to measure the energy and momentum of the incident particle. These measurements create energy spectra and images of the emitting source for source identification and localization. The dual species instrument provides superior detection than a single species alone. In realistic detection scenarios, few particles are detected from a potential threat due to source shielding, detection at a distance, high background, and weak sources. This contributes to a small signal to noise ratio, and threat detection becomes difficult. To address these difficulties, several enhanced data analysis tools were developed. A Receiver Operating Characteristic Curve (ROC) helps set instrumental alarm thresholds as well as to identify the presence of a source. Analysis of a dual-species ROC curve provides superior detection capabilities. Bayesian analysis helps to detect and identify the presence of a source through model comparisons, and helps create a background corrected count spectra for enhanced spectroscopy. Development of an instrument response using simulations and numerical analyses will help perform spectra and image deconvolution. This thesis will outline the principles of operation of the NSPECT instrument using the double scatter technology, traditional analysis techniques, and enhanced analysis techniques as applied to data from the NSPECT instrument, and an

  3. Systems for increasing the sensitivity of gamma-ray imagers

    DOEpatents

    Mihailescu, Lucian; Vetter, Kai M.; Chivers, Daniel H.

    2012-12-11

    Systems that increase the position resolution and granularity of double sided segmented semiconductor detectors are provided. These systems increase the imaging resolution capability of such detectors, either used as Compton cameras, or as position sensitive radiation detectors in imagers such as SPECT, PET, coded apertures, multi-pinhole imagers, or other spatial or temporal modulated imagers.

  4. Methods for increasing the sensitivity of gamma-ray imagers

    DOEpatents

    Mihailescu, Lucian [Pleasanton, CA; Vetter, Kai M [Alameda, CA; Chivers, Daniel H [Fremont, CA

    2012-02-07

    Methods are presented that increase the position resolution and granularity of double sided segmented semiconductor detectors. These methods increase the imaging resolution capability of such detectors, either used as Compton cameras, or as position sensitive radiation detectors in imagers such as SPECT, PET, coded apertures, multi-pinhole imagers, or other spatial or temporal modulated imagers.

  5. GPU-based prompt gamma ray imaging from boron neutron capture therapy.

    PubMed

    Yoon, Do-Kun; Jung, Joo-Young; Jo Hong, Key; Sil Lee, Keum; Suk Suh, Tae

    2015-01-01

    The purpose of this research is to perform the fast reconstruction of a prompt gamma ray image using a graphics processing unit (GPU) computation from boron neutron capture therapy (BNCT) simulations. To evaluate the accuracy of the reconstructed image, a phantom including four boron uptake regions (BURs) was used in the simulation. After the Monte Carlo simulation of the BNCT, the modified ordered subset expectation maximization reconstruction algorithm using the GPU computation was used to reconstruct the images with fewer projections. The computation times for image reconstruction were compared between the GPU and the central processing unit (CPU). Also, the accuracy of the reconstructed image was evaluated by a receiver operating characteristic (ROC) curve analysis. The image reconstruction time using the GPU was 196 times faster than the conventional reconstruction time using the CPU. For the four BURs, the area under curve values from the ROC curve were 0.6726 (A-region), 0.6890 (B-region), 0.7384 (C-region), and 0.8009 (D-region). The tomographic image using the prompt gamma ray event from the BNCT simulation was acquired using the GPU computation in order to perform a fast reconstruction during treatment. The authors verified the feasibility of the prompt gamma ray image reconstruction using the GPU computation for BNCT simulations.

  6. GPU-based prompt gamma ray imaging from boron neutron capture therapy

    SciTech Connect

    Yoon, Do-Kun; Jung, Joo-Young; Suk Suh, Tae; Jo Hong, Key; Sil Lee, Keum

    2015-01-15

    Purpose: The purpose of this research is to perform the fast reconstruction of a prompt gamma ray image using a graphics processing unit (GPU) computation from boron neutron capture therapy (BNCT) simulations. Methods: To evaluate the accuracy of the reconstructed image, a phantom including four boron uptake regions (BURs) was used in the simulation. After the Monte Carlo simulation of the BNCT, the modified ordered subset expectation maximization reconstruction algorithm using the GPU computation was used to reconstruct the images with fewer projections. The computation times for image reconstruction were compared between the GPU and the central processing unit (CPU). Also, the accuracy of the reconstructed image was evaluated by a receiver operating characteristic (ROC) curve analysis. Results: The image reconstruction time using the GPU was 196 times faster than the conventional reconstruction time using the CPU. For the four BURs, the area under curve values from the ROC curve were 0.6726 (A-region), 0.6890 (B-region), 0.7384 (C-region), and 0.8009 (D-region). Conclusions: The tomographic image using the prompt gamma ray event from the BNCT simulation was acquired using the GPU computation in order to perform a fast reconstruction during treatment. The authors verified the feasibility of the prompt gamma ray image reconstruction using the GPU computation for BNCT simulations.

  7. Imaging principles and techniques in space-borne gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Schönfelder, Volker

    2004-06-01

    Gamma-ray astronomy in the photon energy band from several 100keV up to say 10GeV can only be performed from space. Tremendous progress has been made in this young research field during the last 40 years. All-Sky maps exist now in continuum and line emission and short gamma-ray bursts-lasting only seconds-can be located to better than 1arcmin. The imaging principles used in gamma-ray astronomy are different at low energies (<30MeV) and at high energies (>30MeV). Low-energy telescopes are based on the photo- or Compton-effect, whereas high-energy telescopes use the pair-production effect. The angular resolutions achieved by modern telescopes are in the range of 0.1 to 1°. A review of previous, current, and future telescopes is given for gamma-ray astronomy in general, and for burst astronomy in particular.

  8. A Fieldable-Prototype Large-Area Gamma-ray Imager for Orphan Source Search

    SciTech Connect

    Ziock, Klaus-Peter; Fabris, Lorenzo; Carr, Dennis; Collins, Jeff; Cunningham, Mark F; Habte Ghebretatios, Frezghi; Karnowski, Thomas Paul; Marchant, William

    2008-01-01

    We have constructed a unique instrument for use in the search for orphan sources. The system uses gamma-ray imaging to "see through" the natural background variations that effectively limit the search range of normal devices to ~10 m. The imager is mounted in a 4.9- m-long trailer and can be towed by a large personal vehicle. Source locations are determined both in range and along the direction of travel as the vehicle moves. A fully inertial platform coupled to a Global Positioning System receiver is used to map the gamma-ray images onto overhead geospatial imagery. The resulting images provide precise source locations, allowing rapid follow-up work. The instrument simultaneously searches both sides of the street to a distance of 50 m (100-m swath) for milliCurieclass sources with near-perfect performance.

  9. The High Altitude Water Cherenlov (HAWC) Gamma ray Detector Response to Atmospheric Electric Field Variations

    NASA Astrophysics Data System (ADS)

    Lara, A.

    2015-12-01

    The High Altitude Water Cherenkov (HAWC) observatory is located at 4100 m a.s.l. in Mexico. HAWC's primary purpose is the study of both: galactic and extra-galactic sources of high energy gamma rays. HAWC consists of 300 large water Cherenkov detectors (WCD), each instrumented with 4 photo-multipliers (PMTs). The HAWC scaler system records the rates of individual PMTs giving the opportunity of study relatively low energy transients as solar energetic particles, the solar modulation of galactic cosmic rays and possible variations of the cosmic ray rate due to atmospheric electric field changes. In this work, we present the observations of scaler rate enhancements associated with thunderstorm activity observed at the HAWC site.In particular, we present preliminary results of the analysis of the time coincidence of the electric field changes and the scaler enhancements.

  10. A liquid xenon imaging telescope for 1-30 MeV gamma-ray astrophysics

    NASA Technical Reports Server (NTRS)

    Aprile, Elena; Mukherjee, Reshmi; Suzuki, Masayo

    1989-01-01

    A study of the primary scintillation light in liquid xenon excited by 241 Am alpha particles and 207 Bi internal conversion electrons are discussed. The time dependence and the intensity of the light at different field strengths have been measured with a specifically designed chamber, equipped with a CaF sub 2 light transmitting window coupled to a UV sensitive PMT. The time correlation between the fast light signal and the charge signal shows that the scintillation signals produced in liquid xenon by ionizing particles provides an ideal trigger in a Time Projection type LXe detector aiming at full imaging of complex gamma-ray events. Researchers also started Monte Carlo calculations to establish the performance of a LXe imaging telescope for high energy gamma-rays.

  11. Measurements with Pinhole and Coded Aperture Gamma-Ray Imaging Systems

    SciTech Connect

    Raffo-Caiado, Ana Claudia; Solodov, Alexander A; Abdul-Jabbar, Najeb M; Hayward, Jason P; Ziock, Klaus-Peter

    2010-01-01

    From a safeguards perspective, gamma-ray imaging has the potential to reduce manpower and cost for effectively locating and monitoring special nuclear material. The purpose of this project was to investigate the performance of pinhole and coded aperture gamma-ray imaging systems at Oak Ridge National Laboratory (ORNL). With the aid of the European Commission Joint Research Centre (JRC), radiometric data will be combined with scans from a three-dimensional design information verification (3D-DIV) system. Measurements were performed at the ORNL Safeguards Laboratory using sources that model holdup in radiological facilities. They showed that for situations with moderate amounts of solid or dense U sources, the coded aperture was able to predict source location and geometry within ~7% of actual values while the pinhole gave a broad representation of source distributions

  12. Machine Learning Search for Gamma-Ray Burst Afterglows in Optical Images

    NASA Astrophysics Data System (ADS)

    Topinka, M.

    2016-06-01

    Thanks to the advances in robotic telescopes, time domain astronomy leads to a large number of transient events detected in images every night. Data mining and machine learning tools used for object classification are presented. The goal is to automatically classify transient events for both further follow-up by a larger telescope and for statistical studies of transient events. Special attention is given to the identification of gamma-ray burst afterglows. Machine learning techniques are used to identify GROND gamma-ray burst afterglow among the astrophysical objects present in the SDSS archival images based on the g'-r', r'-i' and i'-z' color indices. The performance of the support vector machine, random forest and neural network algorithms is compared. A joint meta-classifier, built on top of the individual classifiers, can identify GRB afterglows with the overall accuracy of ≳ 90%.

  13. A liquid xenon imaging telescope for 1-30 MeV gamma-ray astrophysics

    NASA Technical Reports Server (NTRS)

    Aprile, Elena; Mukherjee, Reshmi; Suzuki, Masayo

    1989-01-01

    A study of the primary scintillation light in liquid xenon excited by 241 Am alpha particles and 207 Bi internal conversion electrons are discussed. The time dependence and the intensity of the light at different field strengths have been measured with a specifically designed chamber, equipped with a CaF sub 2 light transmitting window coupled to a UV sensitive PMT. The time correlation between the fast light signal and the charge signal shows that the scintillation signals produced in liquid xenon by ionizing particles provides an ideal trigger in a Time Projection type LXe detector aiming at full imaging of complex gamma-ray events. Researchers also started Monte Carlo calculations to establish the performance of a LXe imaging telescope for high energy gamma-rays.

  14. Motion estimation accuracy for visible-light/gamma-ray imaging fusion for portable portal monitoring

    NASA Astrophysics Data System (ADS)

    Karnowski, Thomas P.; Cunningham, Mark F.; Goddard, James S.; Cheriyadat, Anil M.; Hornback, Donald E.; Fabris, Lorenzo; Kerekes, Ryan A.; Ziock, Klaus-Peter; Gee, Timothy F.

    2010-01-01

    The use of radiation sensors as portal monitors is increasing due to heightened concerns over the smuggling of fissile material. Portable systems that can detect significant quantities of fissile material that might be present in vehicular traffic are of particular interest. We have constructed a prototype, rapid-deployment portal gamma-ray imaging portal monitor that uses machine vision and gamma-ray imaging to monitor multiple lanes of traffic. Vehicles are detected and tracked by using point detection and optical flow methods as implemented in the OpenCV software library. Points are clustered together but imperfections in the detected points and tracks cause errors in the accuracy of the vehicle position estimates. The resulting errors cause a "blurring" effect in the gamma image of the vehicle. To minimize these errors, we have compared a variety of motion estimation techniques including an estimate using the median of the clustered points, a "best-track" filtering algorithm, and a constant velocity motion estimation model. The accuracy of these methods are contrasted and compared to a manually verified ground-truth measurement by quantifying the rootmean- square differences in the times the vehicles cross the gamma-ray image pixel boundaries compared with a groundtruth manual measurement.

  15. Mercuric iodide room-temperature array detectors for gamma-ray imaging

    SciTech Connect

    Patt, B.

    1994-11-15

    Significant progress has been made recently in the development of mercuric iodide detector arrays for gamma-ray imaging, making real the possibility of constructing high-performance small, light-weight, portable gamma-ray imaging systems. New techniques have been applied in detector fabrication and then low noise electronics which have produced pixel arrays with high-energy resolution, high spatial resolution, high gamma stopping efficiency. Measurements of the energy resolution capability have been made on a 19-element protypical array. Pixel energy resolutions of 2.98% fwhm and 3.88% fwhm were obtained at 59 keV (241-Am) and 140-keV (99m-Tc), respectively. The pixel spectra for a 14-element section of the data is shown together with the composition of the overlapped individual pixel spectra. These techniques are now being applied to fabricate much larger arrays with thousands of pixels. Extension of these principles to imaging scenarios involving gamma-ray energies up to several hundred keV is also possible. This would enable imaging of the 208 keV and 375-414 keV 239-Pu and 240-Pu structures, as well as the 186 keV line of 235-U.

  16. Hard X-ray imaging survey of the Galactic plane with the Caltech gamma-ray imaging payload GRIP-2

    NASA Technical Reports Server (NTRS)

    Corbel, S.; Cook, W. R.; Harrison, F. A.; Prince, T. A.; Schindler, S. M.; Wang, S.

    1997-01-01

    In a two-day balloon flight during October 1995, the Caltech coded aperture gamma ray imaging payload (GRIP-2) imaged various fields in the Galactic plane and center in the 25 to 600 keV energy band. The large phoswich detector, the 15 deg field of view, the 30 arcmin angular resolution and 6 arcmin point source localization capability of GRIP-2 provides the possibility of surveying the accreting binary population of the Galaxy at high energy. The instrument is described and preliminary imaging results are reported on. The capabilities of this instrument for hard X-ray/gamma ray imaging are demonstrated.

  17. The Gamma-Ray Imager/Polarimeter for Solar Flares (GRIPS)

    NASA Astrophysics Data System (ADS)

    Shih, A. Y.; Lin, R. P.; Hurford, G. J.; Boggs, S. E.; Zoglauer, A. C.; Wunderer, C. B.; Sample, J. G.; Turin, P.; McBride, S.; Smith, D. M.; Tajima, H.; Luke, P. N.; Amman, M. S.

    2008-12-01

    The new balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from ~20 keV to >~10 MeV. The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded with an energy resolution of a few keV FWHM and a spatial resolution to within <0.1 mm3. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM), a 2-cm thick tungsten grid with pitches that range quasi-continuously from 1 to 13 mm. With the MPRM situated 8 meters from the spectrometer, this instrument will provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), sufficient to separate the 2.2 MeV footpoint sources for almost all flares. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e. as an active scatterer), with an estimated minimum detectable polarization of a few percent at 150--650 keV in an X-class flare. GRIPS will address questions relevant to particle acceleration and energy release that have been raised by recent solar flare observations, such as: What causes the spatial separation between energetic electron producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the accelerated electrons, and why do relativistic electron dominate in the corona? How does the composition of accelerated and ambient material vary with space and time, and why?

  18. The Gamma-Ray Imager/Polarimeter for Solar Flares (GRIPS)

    NASA Technical Reports Server (NTRS)

    Shih, Albert Y.; Lin, Robert P.; Hurford, Gordon J.; Duncan, Nicole A.; Saint-Hilaire, Pascal; Bain, Hazel M.; Boggs, Steven E.; Zoglauer, Andreas C.; Smith, David M.; Tajima, Hiroyasu; hide

    2012-01-01

    The balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from approximately 20 keV to greater than approximately 10 MeV. GRIPS will address questions raised by recent solar flare observations regarding particle acceleration and energy release, such as: What causes the spatial separation between energetic electrons producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the relativistic electrons, and why can they dominate in the corona? How do the compositions of accelerated and ambient material vary with space and time, and why? The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded with an energy resolution of a few keV FWHM and a spatial resolution of less than 0.1 cubic millimeter. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM), a 2.5-centimeter thick tungsten alloy slit/slat grid with pitches that range quasi-continuously from 1 to 13 millimeters. The MPRM is situated 8 meters from the spectrometer to provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), sufficient to separate 2.2 MeV footpoint sources for almost all flares. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e., as an active scatterer), with an estimated minimum detectable polarization of a few percent at 150-650 keV in an X-class flare. GRIPS is scheduled for a continental-US engineering test flight in fall 2013, followed by long or ultra-long duration balloon flights in Antarctica.

  19. The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS)

    NASA Astrophysics Data System (ADS)

    Shih, Albert Y.; Lin, Robert P.; Hurford, Gordon J.; Duncan, Nicole A.; Saint-Hilaire, Pascal; Bain, Hazel M.; Boggs, Steven E.; Zoglauer, Andreas C.; Smith, David M.; Tajima, Hiroyasu; Amman, Mark S.; Takahashi, Tadayuki

    2012-09-01

    The balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from ~20 keV to >~10 MeV. GRIPS will address questions raised by recent solar flare observations regarding particle acceleration and energy release, such as: What causes the spatial separation between energetic electrons producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the relativistic electrons, and why can they dominate in the corona? How do the compositions of accelerated and ambient material vary with space and time, and why? The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded with an energy resolution of a few keV FWHM and a spatial resolution of <0.1 mm3. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM), a 2.5-cm thick tungstenalloy slit/slat grid with pitches that range quasi-continuously from 1 to 13 mm. The MPRM is situated 8 meters from the spectrometer to provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), sufficient to separate 2.2 MeV footpoint sources for almost all flares. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e., as an active scatterer), with an estimated minimum detectable polarization of a few percent at 150-650 keV in an X-class flare. GRIPS is scheduled for a continental-US engineering test flight in fall 2013, followed by long or ultra-long duration balloon flights in Antarctica.

  20. 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

  1. 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.

  2. Minute-of-Arc Resolution Gamma ray Imaging Experiment-MARGIE

    NASA Astrophysics Data System (ADS)

    Kappadath, S. C.; Altice, P. P.; Cherry, M. L.; Guzik, T. G.; Stacy, J. G.; Macri, J.; McConnell, M. L.; Ryan, J. M.; Band, D. L.; Matteson, J. L.; O'Neill, T. J.; Zych, A. D.; Buckley, J.; Hink, P. L.

    2000-04-01

    MARGIE (Minute-of-Arc Resolution Gamma-ray Imaging Experiment) is a large area (~104 cm2), wide field-of-view (~1 sr), hard X-ray/gamma-ray (~20-600 keV) coded-mask imaging telescope capable of performing a sensitive survey of both steady and transient cosmic sources. MARGIE has been selected for a NASA mission-concept study for an Ultra Long Duration (100 day) Balloon flight. We describe our program to develop the instrument based on new detector technology of either cadmium zinc telluride (CZT) semiconductors or pixellated cesium iodide (CsI) scintillators viewed by fast-timing bi-directional charge-coupled devices (CCDs). The primary scientific objectives are to image faint Gamma-Ray Bursts (GRBs) in near-real-time at the low intensity (high-redshift) end of the logN-logS distribution, thereby extending the sensitivity of present observations, and to perform a wide field survey of the Galactic plane. .

  3. Study on detecting spatial distribution of neutrons and gamma rays using a multi-imaging plate system.

    PubMed

    Tanaka, Kenichi; Sakurai, Yoshinori; Endo, Satoru; Takada, Jun

    2014-06-01

    In order to measure the spatial distributions of neutrons and gamma rays separately using the imaging plate, the requirement for the converter to enhance specific component was investigated with the PHITS code. Consequently, enhancing fast neutrons using recoil protons from epoxy resin was not effective due to high sensitivity of the imaging plate to gamma rays. However, the converter of epoxy resin doped with (10)B was found to have potential for thermal and epithermal neutrons, and graphite for gamma rays. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Neutron propagation and 2.2 MeV gamma-ray line production in the solar atmosphere

    NASA Technical Reports Server (NTRS)

    Wang, H. T.; Ramaty, R.

    1974-01-01

    Calculation of the 2.2-MeV gamma-ray line intensity from the sun using a Monte Carlo method for neutron propagation in the solar atmosphere. Detailed results are provided concerning the total gamma-ray yield per neutron and the time profile of the 2.2-MeV line from an instantaneous and monoenergetic neutron source. The parameters which have the most significant effects on the line intensity are the energies of the neutrons, the position of the neutron source on the sun, and the abundance of He-3 in the photosphere. For an isotropic neutron source which is not too close to the limb of the sun, the gamma-ray yield is between about 0.02 to 0.2 photons per neutron, provided that the neutron energies are in the range from 1 to 100 MeV and the ratio He-3/H is less than about .00005.

  5. Neutron propagation and 2.2 MeV gamma-ray line production in the solar atmosphere

    NASA Technical Reports Server (NTRS)

    Wang, H. T.; Ramaty, R.

    1974-01-01

    The 2.2 MeV gamma ray line intensity from the sun was calculated using a Monte Carlo method for neutron propagation in the solar atmosphere. Detailed results are provided on the total gamma ray yield per neutron and on the time profile of the 2.2 MeV line from an instantaneous and monoenergetic neutron source. The parameters which have the most significant effects on the line intensity are the energies of the neutrons, the position of the neutron source on the sun, and the abundance of He-3 in the photosphere. For an isotropic neutron source which is not too close to the limb of the sun, the gamma ray yield is between about 0.02 to 0.2 photons per neutron, provided that the neutron energies are in the range 1 to 100 MeV and the ratio He-3/H is less than about .00005.

  6. Three-dimensional Monte-Carlo simulation of gamma-ray scattering and production in the atmosphere

    SciTech Connect

    Morris, D.J. )

    1989-05-15

    Monte Carlo codes have been developed to simulate gamma-ray scattering and production in the atmosphere. The scattering code simulates interactions of low-energy gamma rays (20 to several hundred keV) from an astronomical point source in the atmosphere; a modified code also simulates scattering in a spacecraft. Four incident spectra, typical of gamma-ray bursts, solar flares, and the Crab pulsar, and 511 keV line radiation have been studied. These simulations are consistent with observations of solar flare radiation scattered from the atmosphere. The production code simulates the interactions of cosmic rays which produce high-energy (above 10 MeV) photons and electrons. It has been used to calculate gamma-ray and electron albedo intensities at Palestine, Texas and at the equator; the results agree with observations in most respects. With minor modifications this code can be used to calculate intensities of other high-energy particles. Both codes are fully three-dimensional, incorporating a curved atmosphere; the production code also incorporates the variation with both zenith and azimuth of the incident cosmic-ray intensity due to geomagnetic effects. These effects are clearly reflected in the calculated albedo by intensity contrasts between the horizon and nadir, and between the east and west horizons.

  7. Development of wide-band X-ray/gamma-ray imagers using reach through APD arrays

    SciTech Connect

    Nakamori, T.; Kataoka, J.; Toizumi, T.; Koizumi, M.; Tanaka, S.; Kanai, Y.; Yatsu, Y.; Kawai, N.; Ishikawa, Y.; Kawai, T.; Kawabata, N.; Matsunaga, Y.

    2009-05-25

    It is quite important to obtain wide band spectra of gamma-ray bursts (GRBs) at the same time in order to probe the emission processes or the structure of GRBs. An avalanche photo diode (APD) is a compact photon sensor with an internal gain of 100. We have developed an X-ray/gamma-ray detector using a back-illuminated reach-through APD (5x5 mm{sup 2}) optically coupled with a conventional CsI(Tl) scintillator, which covers typically from 1 keV to 1 MeV. Further, we developed a 1-dimensional array of the 8/16 APDs (net 16x20 mm{sup 2}) for the purpose of an imaging photon detector to be used in future GRB missions. Here we present the current status and performance of our hybrid detector.

  8. Advanced Laser-Compton Gamma-Ray Sources for Nuclear Materials Detection, Assay and Imaging

    NASA Astrophysics Data System (ADS)

    Barty, C. P. J.

    2015-10-01

    Highly-collimated, polarized, mono-energetic beams of tunable gamma-rays may be created via the optimized Compton scattering of pulsed lasers off of ultra-bright, relativistic electron beams. Above 2 MeV, the peak brilliance of such sources can exceed that of the world's largest synchrotrons by more than 15 orders of magnitude and can enable for the first time the efficient pursuit of nuclear science and applications with photon beams, i.e. Nuclear Photonics. Potential applications are numerous and include isotope-specific nuclear materials management, element-specific medical radiography and radiology, non-destructive, isotope-specific, material assay and imaging, precision spectroscopy of nuclear resonances and photon-induced fission. This review covers activities at the Lawrence Livermore National Laboratory related to the design and optimization of mono-energetic, laser-Compton gamma-ray systems and introduces isotope-specific nuclear materials detection and assay applications enabled by them.

  9. Imaging of heterogeneous materials by prompt gamma-ray neutron activation analysis

    SciTech Connect

    Staples, P.; Prettyman, T.; Lestone, J.

    1998-12-01

    The authors have used a tomographic gamma scanner (TGS) to produce tomographic prompt gamma-ray neutron activation analysis imaging (PGNAA) of heterogeneous matrices. The TGS was modified by the addition of graphite reflectors that contain isotopic neutron sources for sample interrogation. The authors are in the process of developing the analysis methodology necessary for a quantitative assay of large containers of heterogeneous material. This nondestructive analysis (NDA) technique can be used for material characterization and the determination of neutron assay correction factors. The most difficult question to be answered is the determination of the source-to-sample coupling term. To assist in the determination of the coupling term, the authors have obtained images for a range of sample that are very well characterized, such as, homogenous pseudo one-dimensional samples to three-dimensional heterogeneous samples. They then compare the measurements to MCNP calculations. For an accurate quantitative measurement, it is also necessary to determine the sample gamma-ray self attenuation at higher gamma-ray energies, namely pair production should be incorporated into the analysis codes.

  10. Active neutron and gamma-ray imaging of highly enriched uranium for treaty verification.

    PubMed

    Hamel, Michael C; Polack, J Kyle; Ruch, Marc L; Marcath, Matthew J; Clarke, Shaun D; Pozzi, Sara A

    2017-08-11

    The detection and characterization of highly enriched uranium (HEU) presents a large challenge in the non-proliferation field. HEU has a low neutron emission rate and most gamma rays are low energy and easily shielded. To address this challenge, an instrument known as the dual-particle imager (DPI) was used with a portable deuterium-tritium (DT) neutron generator to detect neutrons and gamma rays from induced fission in HEU. We evaluated system response using a 13.7-kg HEU sphere in several configurations with no moderation, high-density polyethylene (HDPE) moderation, and tungsten moderation. A hollow tungsten sphere was interrogated to evaluate the response to a possible hoax item. First, localization capabilities were demonstrated by reconstructing neutron and gamma-ray images. Once localized, additional properties such as fast neutron energy spectra and time-dependent neutron count rates were attributed to the items. For the interrogated configurations containing HEU, the reconstructed neutron spectra resembled Watt spectra, which gave confidence that the interrogated items were undergoing induced fission. The time-dependent neutron count rate was also compared for each configuration and shown to be dependent on the neutron multiplication of the item. This result showed that the DPI is a viable tool for localizing and confirming fissile mass and multiplication.

  11. Imaging Gas Counters for X- and Gamma Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Ramsey, Brian D.

    1995-01-01

    Gas-filled detectors, such as proportional counters, have long been used in x-ray astronomy. They are robust, relatively easy to fabricate, and can provide large collecting areas with reasonable spatial and energy resolution. Despite coming of age in the 50's and 60's, their versatility is such that they are still planned for future missions. A vigorous development program, led mostly by the high energy physics community, has ensured continued improvements in proportional counter technology. These include multistep counters, microstrip technologies and optical avalanche chambers. High fill-gas pressures and the use of suitable converters permit operation up to 100s of GeV. The current status of imaging gas-filled detectors will be reviewed, concentrating on the lower energy region (less than 100 keV) but also briefly covering higher energy applications up to the GeV region. This review is not intended to be exhaustive and draws heavily on work currently in progress at MSFC.

  12. A new gamma ray imaging diagnostic for runaway electron studies at DIII-D

    NASA Astrophysics Data System (ADS)

    Cooper, C. M.; Pace, D. C.; Eidietis, N. W.; Paz-Soldan, C.; Commaux, N.; Shiraki, D.; Hollmann, E. M.; Moyer, R. A.; Risov, V.

    2015-11-01

    A new Gamma Ray Imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at DIII-D. The diagnostic is sensitive to 0.5 - 50 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE dissipation from pellet injection. The GRI consists of a lead ``pinhole camera'' mounted on the midplane with 11x11 counter-current tangential chords 20 cm wide that span the vessel. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE Bremsstrahlung radiation. Detectors operate in current saturation mode at 10 MHz, or the flux is attenuated for Pulse Height Analysis (PHA) capable of discriminating up to ~10k pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. Work supported by the US DOE under DE-AC05-00OR22725, DE-FG02-07ER54917 & DE-FC02-04ER54698.

  13. Focusing and imaging sharp line x-ray and gamma-ray sources using variable-metric diffraction crystals. [Gamma ray telescopes

    SciTech Connect

    Smither, R.K.

    1982-01-01

    A new method has been devised for focusing and imaging the radiation from sharp-line sources of x-rays and gamma-rays, which makes use of variable-metric diffraction crystals. A variable-metric diffraction crystal is one in which the spacings between the crystalline planes is varied as a function of position in the crystal by either the application of a thermal gradient or by changing the composition of a two component or multiple component crystal. This change in planar spacing changes the Bragg diffraction angle for monochromatic radiation as a function of position in the crystal and makes it possible to obtain focusing and in some cases imaging of a sharp-line point source or parallel beam source. This new approach to focusing x-rays and gamma-rays is used to design a number of gamma ray telescopes suitable for focusing the 511 keV annihilation radiation from the strong source of the center of our galaxy. The new designs are surprisingly efficient with approximately 20% of the radiation incident on the variable-metric diffraction crystals being focused on the image spot. Crystals of Ge, Ge + Si, Si, and quartz are used with mosaic widths of 10 arc sec. The size of the telescope can be scaled up or down without affecting the angular resolution or the energy resolution. The largest model described is 50 m long and has 10 crystal diffraction ring assembles with radii between 71 and 200 cm. The total area of the diffraction crystal is 24,610 cm/sup 2/ and the effective area (total x diffraction coefficient x transmission) is 4745 cm/sup 2/. An example of a smaller telescope is also given that is only 12.5 m long and has an effective area of 297 cm/sup 2/.

  14. MO-F-CAMPUS-J-05: Verification for Prompt Gamma Ray Imaging During Proton Boron Fusion Therapy

    SciTech Connect

    Shin, H; Yoon, D; Jung, J; Kim, M; Jang, H; Suh, T

    2015-06-15

    Purpose: The purpose of this study is to verify the acquisition of the three dimensional single photon emission computed tomography (SPECT) image using prompt gamma ray originated from proton boron fusion therapy (PBFT). Methods: The real-time imaging system during the PBFT was simulated to acquire the tomographic image of the prompt gamma ray from treated tumor by the proton boron reaction, using Monte Carlo simulation (MCNPX). We acquired percentage depth dose (PDD) of the proton beam in the water phantom including the boron uptake region (BUR), the energy spectra of the prompt gamma ray and tomographic image which can show treated tumor regions. The prompt gamma ray image was reconstructed using maximum likelihood estimation maximization (MLEM) reconstruction algorithm with 64 projections. In addition, in order to evaluate the reconstructed image, the image profiles between BURs were extracted from the image. Results: In the PDD results, the Bragg-peak was amplified definitely when the proton’s maximum dose level was located at the BUR. This amplification is based on the generation of alpha particles. In addition, the prompt gamma ray peak of 719 keV was observed from the energy spectrum. Through the previous process, the tomographic image of prompt gamma ray from the BUR was reconstructed. The line profile was extracted from image including BURs, and it shows high signal-to-noise ratio. Conclusion: We confirmed that the real-time prompt gamma ray image during the PBFT was successfully deducted, and results of quantitative image analysis show good agreement with the original pattern of the BUR. This study first verified the imaging capability of the PBFT-SPECT system. In conclusion, the PBFT-SPECT system can realize the treated tumor monitoring during the PBFT.

  15. Gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1982-01-01

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

  16. Topics in gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1986-01-01

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

  17. Topics in gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1986-01-01

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

  18. First Flight of the Gamma-Ray Imager Polarimeter for Solar Flares (GRIPS) Instrument

    NASA Technical Reports Server (NTRS)

    Duncan, Nicole; Saint-Hilaire, P.; Shih, A. Y.; Hurford, G. J.; Bain, H. M.; Amman, M.; Mochizuki, A. B.; Hoberman, J.; Olson, J.; Maruca, B. A.; hide

    2016-01-01

    The Gamma-Ray Imager/Polarimeter for Solar ares (GRIPS) instrument is a balloon-borne telescope designed to study solar-flare particle acceleration and transport. We describe GRIPS's first Antarctic long-duration flight in January 2016 and report preliminary calibration and science results. Electron and ion dynamics, particle abundances and the ambient plasma conditions in solar flares can be understood by examining hard X-ray (HXR) and gamma-ray emission (20 keV to 10 MeV). Enhanced imaging, spectroscopy and polarimetry of flare emissions in this energy range are needed to study particle acceleration and transport questions. The GRIPS instrument is specifically designed to answer questions including: What causes the spatial separation between energetic electrons producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the relativistic electrons, and why can they dominate in the corona? How do the compositions of accelerated and ambient material vary with space and time, and why? GRIPS's key technological improvements over the current solar state of the art at HXR/gamma-ray energies, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), include 3D position-sensitive germanium detectors (3D-GeDs) and a single-grid modulation collimator, the multi-pitch rotating modulator (MPRM). The 3D-GeDs have spectral FWHM resolution of a few hundred keV and spatial resolution less than 1cu mm. For photons that Compton scatter, usually greater or equal to 150 keV, the energy deposition sites can be tracked, providing polarization measurements as well as enhanced background reduction through Compton imaging. Each of GRIPS's detectors has 298 electrode strips read out with ASIC/FPGA electronics. In GRIPS's energy range, indirect imaging methods provide higher resolution than focusing optics or Compton imaging techniques. The MPRM grid-imaging system has a single-grid design which provides twice the throughput of a bi-grid imaging system

  19. High resolution x-ray and gamma ray imaging using diffraction lenses with mechanically bent crystals

    DOEpatents

    Smither, Robert K [Hinsdale, IL

    2008-12-23

    A method for high spatial resolution imaging of a plurality of sources of x-ray and gamma-ray radiation is provided. High quality mechanically bent diffracting crystals of 0.1 mm radial width are used for focusing the radiation and directing the radiation to an array of detectors which is used for analyzing their addition to collect data as to the location of the source of radiation. A computer is used for converting the data to an image. The invention also provides for the use of a multi-component high resolution detector array and for narrow source and detector apertures.

  20. Gamma-ray imaging with a Si/CsI(Tl) Compton detector.

    PubMed

    Hoover, A S; Sullivan, J P; Baird, B; Brumby, S P; Kippen, R M; McCluskey, C W; Rawool-Sullivan, M W; Sorensen, E B

    2006-12-01

    We present results from Compton imaging of gamma-ray sources using an instrument constructed from thin silicon scattering detectors and CsI(Tl) absorbing detectors. We have successfully imaged single and double point sources for several common radioactive isotopes ((137)Cs, (60)Co, (22)Na, (54)Mn). The measured angular resolution is 11.6( composite function) FWHM at 662keV. In parallel with the hardware effort, a GEANT4-based simulation code was developed. Comparisons between real and simulated data are discussed.

  1. First flight of the Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument

    NASA Astrophysics Data System (ADS)

    Duncan, Nicole; Saint-Hilaire, P.; Shih, A. Y.; Hurford, G. J.; Bain, H. M.; Amman, M.; Mochizuki, B. A.; Hoberman, J.; Olson, J.; Maruca, B. A.; Godbole, N. M.; Smith, D. M.; Sample, J.; Kelley, N. A.; Zoglauer, A.; Caspi, A.; Kaufmann, P.; Boggs, S.; Lin, R. P.

    2016-07-01

    The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument is a balloon-borne telescope designed to study solar- are particle acceleration and transport. We describe GRIPS's first Antarctic long-duration flight in January 2016 and report preliminary calibration and science results. Electron and ion dynamics, particle abundances and the ambient plasma conditions in solar flares can be understood by examining hard X-ray (HXR) and gamma-ray emission (20 keV to 10 MeV). Enhanced imaging, spectroscopy and polarimetry of are emissions in this energy range are needed to study particle acceleration and transport questions. The GRIPS instrument is specifically designed to answer questions including: What causes the spatial separation between energetic electrons producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the relativistic electrons, and why can they dominate in the corona? How do the compositions of accelerated and ambient material vary with space and time, and why? GRIPS's key technological improvements over the current solar state of the art at HXR/gamma-ray energies, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), include 3D position-sensitive germanium detectors (3D-GeDs) and a single-grid modulation collimator, the multi-pitch rotating modulator (MPRM). The 3D-GeDs have spectral FWHM resolution of a few hundred keV and spatial resolution <1 mm3. For photons that Compton scatter, usually > 150 keV, the energy deposition sites can be tracked, providing polarization measurements as well as enhanced background reduction through Compton imaging. Each of GRIPS's detectors has 298 electrode strips read out with ASIC/FPGA electronics. In GRIPS's energy range, indirect imaging methods provide higher resolution than focusing optics or Compton imaging techniques. The MPRM gridimaging system has a single-grid design which provides twice the throughput of a bi-grid imaging system like RHESSI. The grid is

  2. Tomographic image of prompt gamma ray from boron neutron capture therapy: A Monte Carlo simulation study

    SciTech Connect

    Yoon, Do-Kun; Jung, Joo-Young; Suk Suh, Tae; Jo Hong, Key

    2014-02-24

    Purpose of paper is to confirm the feasibility of acquisition of three dimensional single photon emission computed tomography image from boron neutron capture therapy using Monte Carlo simulation. Prompt gamma ray (478 keV) was used to reconstruct image with ordered subsets expectation maximization method. From analysis of receiver operating characteristic curve, area under curve values of three boron regions were 0.738, 0.623, and 0.817. The differences between length of centers of two boron regions and distance of maximum count points were 0.3 cm, 1.6 cm, and 1.4 cm.

  3. Novel Applications of Rapid Prototyping in Gamma-ray and X-ray Imaging

    PubMed Central

    Miller, Brian W.; Moore, Jared W.; Gehm, Michael E.; Furenlid, Lars R.; Barrett, Harrison H.

    2010-01-01

    Advances in 3D rapid-prototyping printers, 3D modeling software, and casting techniques allow for the fabrication of cost-effective, custom components in gamma-ray and x-ray imaging systems. Applications extend to new fabrication methods for custom collimators, pinholes, calibration and resolution phantoms, mounting and shielding components, and imaging apertures. Details of the fabrication process for these components are presented, specifically the 3D printing process, cold casting with a tungsten epoxy, and lost-wax casting in platinum. PMID:22984341

  4. Latest Progress on the Gamma-Ray Imager/Polarimeter for Solar Flares (GRIPS)

    NASA Technical Reports Server (NTRS)

    Shih, Albert Y.; Lin, Robert P.; Hurford, Gordon J.; Duncan, Nicole A.; Saint-Hilaire, Pascal; Smith, David Miles; Tajima, Hiroyasu; Amman, Mark

    2011-01-01

    We present the latest progress on building the balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument, including testing and calibration of the detectors and development of the imaging and aspect systems. A continental-US test flight is slated for fall 2012. GRIPS will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from approx.20. keV to > approx.10 MeV. The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded with an energy resolution of a few keV FWHM and a spatial resolution to within <0.1 cu mm. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM), a 2.5-cm thick tungsten-alloy grid with pitches that range quasi-continuously from 1 to 13 mm. With the MPRM situated 8 meters from the spectrometer, this instrument will provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), sufficient to separate the 2.2 MeV footpoint sources for almost all flares. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e. as an active scatterer), with an estimated minimum detectable polarization of a few percent at 150-650 keV in an X-class flare. GRIPS will address questions relevant to particle acceleration and energy release that ha-.e been raised by recent solar flare observations, such as: What causes the spatial separation between energetic electron producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the accelerated electrons, and why do relativistic electron dominate in the corona? How does the composition of accelerated and ambient material vary with space and time, and why?

  5. Latest Progress on the Gamma-Ray Imager/Polarimeter for Solar Flares (GRIPS)

    NASA Technical Reports Server (NTRS)

    Shih, Albert Y.; Lin, Robert P.; Hurford, Gordon J.; Duncan, Nicole A.; Saint-Hilaire, Pascal; Smith, David Miles; Tajima, Hiroyasu; Amman, Mark

    2011-01-01

    We present the latest progress on building the balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument, including testing and calibration of the detectors and development of the imaging and aspect systems. A continental-US test flight is slated for fall 2012. GRIPS will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from approx.20. keV to > approx.10 MeV. The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded with an energy resolution of a few keV FWHM and a spatial resolution to within <0.1 cu mm. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM), a 2.5-cm thick tungsten-alloy grid with pitches that range quasi-continuously from 1 to 13 mm. With the MPRM situated 8 meters from the spectrometer, this instrument will provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), sufficient to separate the 2.2 MeV footpoint sources for almost all flares. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e. as an active scatterer), with an estimated minimum detectable polarization of a few percent at 150-650 keV in an X-class flare. GRIPS will address questions relevant to particle acceleration and energy release that ha-.e been raised by recent solar flare observations, such as: What causes the spatial separation between energetic electron producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the accelerated electrons, and why do relativistic electron dominate in the corona? How does the composition of accelerated and ambient material vary with space and time, and why?

  6. Latest Progress on the Gamma-Ray Imager/Polarimeter for Solar Flares (GRIPS)

    NASA Astrophysics Data System (ADS)

    Shih, A. Y.; Lin, R. P.; Hurford, G. J.; Duncan, N. A.; Saint-Hilaire, P.; Smith, D. M.; Tajima, H.; Amman, M.; Grips Team

    2011-12-01

    We present the latest progress on building the balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument, including testing and calibration of the detectors and development of the imaging and aspect systems. A continental-US test flight is slated for fall 2012. GRIPS will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from ~20 keV to >~10 MeV. The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded with an energy resolution of a few keV FWHM and a spatial resolution to within <0.1 mm^3. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM), a 2.5-cm thick tungsten-alloy grid with pitches that range quasi-continuously from 1 to 13 mm. With the MPRM situated 8 meters from the spectrometer, this instrument will provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), sufficient to separate the 2.2 MeV footpoint sources for almost all flares. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e. as an active scatterer), with an estimated minimum detectable polarization of a few percent at 150-650 keV in an X-class flare. GRIPS will address questions relevant to particle acceleration and energy release that have been raised by recent solar flare observations, such as: What causes the spatial separation between energetic electron producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the accelerated electrons, and why do relativistic electron dominate in the corona? How does the composition of accelerated and ambient material vary with space and time, and why?

  7. On the timing between terrestrial gamma ray flashes, radio atmospherics, and optical lightning emission

    NASA Astrophysics Data System (ADS)

    Gjesteland, Thomas; Østgaard, Nikolai; Bitzer, Phillip; Christian, Hugh J.

    2017-07-01

    On 25 October 2012 the Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI) and the Tropical Rainfall Measuring Mission (TRMM) satellites passed over a thunderstorm on the coast of Sri Lanka. RHESSI observed a terrestrial gamma ray flash (TGF) originating from this thunderstorm. Optical measurements of the causative lightning stroke were made by the lightning imaging sensor (LIS) on board TRMM. The World Wide Lightning Location Network (WWLLN) detected the very low frequency (VLF) radio emissions from the lightning stroke. The geolocation from WWLLN, which we also assume is the TGF source location, was in the convective core of the cloud. By using new information about both RHESSI and LIS timing accuracy, we find that the peak in the TGF light curve occurs 230 $\\mu$s before the WWLLN time. Analysis of the optical signal from LIS shows that within the uncertainties, we cannot conclude which comes first: the gamma emission or the optical emission. We have also applied the new information about the LIS timing on a previously published event by {\\O}stgaard et al. (2012). Also for this event we are not able to conclude which signal comes first. More accurate instruments are needed in order to get the exact timing between the TGF and the optical signal.

  8. NMIS with Imaging and Gamma Ray Spectrometry for Pu, HEU, HE and Other Materials

    SciTech Connect

    Mihalczo, John T; Mullens, James Allen

    2012-03-01

    The Nuclear Material Identification System (NMIS) has been under development at ORNL and the National Nuclear Security Administration (NNSA) Y-12 National Security Complex since 1984. In the mid-1990s, what is now the US Department of Energy (DOE) Office of Nuclear Verification (ONV) realized that it was a useful technology for future arms control treaty applications and supported further development of the system. In 2004, fast-neutron imaging was incorporated into the system. In 2007, the ONV decided to develop a fieldable version of the system, designated as FNMIS, for potential use in future treaties. The FNMIS is being developed to be compatible with the eventual incorporation of gamma-ray spectrometry and an information barrier. This report addresses how and what attributes could be determined by the FNMIS system with gamma-ray spectrometry. The NMIS is a time-dependent coincidence system that incorporates tomographic imaging (including mapping of the fission sites) and gamma-ray spectrometry. It utilizes a small, lightweight (30 lb), portable deuterium-tritium (DT) neutron (14.1 MeV) generator (4 x 10{sup 7} neutrons/second) for active interrogation and can also perform passive interrogation. A high-purity germanium (HPGe) gamma-ray detector with multichannel analysis can be utilized in conjunction with the source for active interrogation or passively. The system uses proton recoil scintillators: 32 small 2.5 x 2.5 x 10.2-cm-thick plastic scintillators for imaging and at least two 2 x 2 arrays of 27 x 27 x 10-cm-thick plastic scintillators that detect induced fission radiation. The DT generator contains an alpha detector that time and directionally tags a fan beam of some of the neutrons emitted and subdivides it into pixels. A fast (1 GHz) time correlation processor measures the time-dependent coincidence among all detectors in the system. A computer-controlled scanner moves the small detectors and the source appropriately for scanning a target object for

  9. First flight of the Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS)

    NASA Astrophysics Data System (ADS)

    Saint-Hilaire, Pascal; Shih, Albert Y.; Duncan, Nicole; Bain, Hazel; Maruca, Bennett A.; Kelley, Nicole; Godbole, Niharika; Kaufmann, Pierre; Caspi, Amir; Sample, John; Hoberman, Jane; Mochizuki, Brent; Olson, Jerry; Boggs, Steven E.; Zoglauer, Andreas; Hurford, Gordon J.; Smith, David M.; Tajima, Hiroyasu; Amman, Mark

    2016-05-01

    The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) high altitude balloon payload was successfully flown in January 2016 from Antarctica (Jan 19 to Jan 30).GRIPS provides a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma ray/hard X-ray emissions from ~20 keV to >~10 MeV. GRIPS’s goal is to address questions raised by recent solar flare observations regarding particle acceleration and energy release, such as: What causes the spatial separation between energetic electrons producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the relativistic electrons, and why can they dominate in the corona? How do the compositions of accelerated and ambient material vary with space and time, and why? The spectrometer/polarimeter consists of six 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded with an energy resolution of a few keV FWHM and a spatial resolution <0.1 mm3. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM), a 2.5-cm thick tungsten alloy slit/slat grid with pitches that range quasi-continuously from 1 to 13 mm. The MPRM is situated 8 meters from the spectrometer to provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), sufficient to separate 2.2 MeV footpoint sources for almost all flares. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs, with an estimated minimum detectable polarization of a few percent at 150-650 keV in an X-class flare. GRIPS was also equipped with active BGO shields, and three piggy-back instruments: a solar terahertz radiometer (Solar-T), a hard X-ray spectrometer (SMASH), and a sonic anemometer (TILDAE).We will present an overview of GRIPS's first flight, the performance of its instruments and subsystems, including the solar pointing and aspect systems, and

  10. Gamma-ray imaging observations of the Crab and Cygnus regions

    SciTech Connect

    McConnell, M.L.

    1987-01-01

    This dissertation presents the results from a balloon-borne experiment, referred to as the Directional Gamma-Ray Telescope (DGT), which is designed to image celestial gamma rays over the energy range 160 keV to 9.3 MeV. It utilizes a technique know as coded aperture imaging in order to obtain spatially resolved images of the sky with an angular resolution of 3.8/sup 0/. This detector is the first flight-ready instrument of this type operating at energies above 160 keV. The first successful balloon flight of this instrument took place on 1984 October 1-2. During the thirty hours in which the payload remained at float altitude, imaging observations of a number of sky regions were obtained, including observations of the Crab and Cygnus regions. The Crab Nebulapulsar was observed to have a featureless power-law spectrum, consistent with previous measurements. Emission from Cyg X-1 was observed up to approx. 10 MeV. At energies below 1 MeV, the data are consistent with a single-temperature inverse Compton model, with an electron temperature, kT/sub c/, of approx. 80 keV and an optical depth, r, of approx. 2.0.

  11. Monte Carlo modeling of neutron and gamma-ray imaging systems

    SciTech Connect

    Hall, J.

    1996-04-01

    Detailed numerical prototypes are essential to design of efficient and cost-effective neutron and gamma-ray imaging systems. We have exploited the unique capabilities of an LLNL-developed radiation transport code (COG) to develop code modules capable of simulating the performance of neutron and gamma-ray imaging systems over a wide range of source energies. COG allows us to simulate complex, energy-, angle-, and time-dependent radiation sources, model 3-dimensional system geometries with ``real world`` complexity, specify detailed elemental and isotopic distributions and predict the responses of various types of imaging detectors with full Monte Carlo accuray. COG references detailed, evaluated nuclear interaction databases allowingusers to account for multiple scattering, energy straggling, and secondary particle production phenomena which may significantly effect the performance of an imaging system by may be difficult or even impossible to estimate using simple analytical models. This work presents examples illustrating the use of these routines in the analysis of industrial radiographic systems for thick target inspection, nonintrusive luggage and cargoscanning systems, and international treaty verification.

  12. Spectroscopic CZT detectors development for x- and gamma-ray imaging instruments

    NASA Astrophysics Data System (ADS)

    Quadrini, Egidio M.; Uslenghi, Michela; Alderighi, Monica; Casini, Fabio; D'Angelo, Sergio; Fiorini, Mauro; La Palombara, Nicola; Mancini, Marcello; Monti, Serena; Bazzano, Angela; Di Cosimo, Sergio; Frutti, Massimo; Natalucci, Lorenzo; Ubertini, Pietro; Guadalupi, Giuseppe M.; Sassi, Matteo; Negri, Barbara

    2007-09-01

    In the context of R&D studies financed by the Italian Space Agency (ASI), a feasibility study to evaluate the Italian Industry interest in medium-large scale production of enhanced CZT detectors has been performed by an Italian Consortium. The R&D investment aims at providing in-house source of high quality solid state spectrometers for Space Astrophysics applications. As a possible spin-off industrial applications to Gamma-ray devices for non-destructive inspections in medical, commercial and security fields have been considered by ASI. The short term programme mainly consists of developing proprietary procedures for 2-3" CZT crystals growth, including bonding and contact philosophy, and a newly designed low-power electronics readout chain. The prototype design and breadboarding is based on a fast signal AD conversion with the target in order to perform a new run for an already existing low-power (<0.7 mW/pixel) ASIC. The prototype also provides digital photon energy reconstruction with particular care for multiple events and polarimetry evaluations. Scientific requirement evaluations for Space Astrophysics Satellite applications have been carried out in parallel, targeted to contribute to the ESA Cosmic Vision 2015-2025 Announcement of Opportunity. Detailed accommodation studies are undergoing, as part of this programme, to size a "Large area arcsecond angular resolution Imager" for the Gamma Ray Imager satellite (Knödlseder et al., this conference).and a new Gamma-ray Wide Field Camera for the "EDGE" proposal (Piro et al., this conference). Finally, an extended market study for cost analysis evaluation in view of the foreseen massive detector production has been performed.

  13. Characterization and Applications of a CdZnTe-Based Gamma-Ray Imager

    NASA Astrophysics Data System (ADS)

    Galloway, Michelle Lee

    Detection of electromagnetic radiation in the form of gamma rays provides a means to discover the presence of nuclear sources and the occurrence of highly-energetic events that occur in our terrestrial and astrophysical environment. The highly penetrative nature of gamma rays allows for probing into objects and regions that are obscured at other wavelengths. The detection and imaging of gamma rays relies upon an understanding of the ways in which these high-energy photons interact with matter. The applications of gamma-ray detection and imaging are numerous. Astrophysical observation of gamma rays expands our understanding of the Universe in which we live. Terrestrial detection and imaging of gamma rays enable environmental monitoring of radioactivity. This allows for identification and localization of nuclear materials to prevent illicit trafficking and to ultimately protect against harmful acts. This dissertation focusses on the development and characterization of a gamma-ray detection and imaging instrument and explores its capabilities for the aforementioned applications. The High Efficiency Multimode Imager, HEMI, is a prototype instrument that is based on Cadmium Zinc Telluride (CdZnTe) semiconductor detectors. The detectors are arranged in a two-planar configuration to allow for both Compton and coded-aperture imaging. HEMI was initially developed as a prototype instrument to demonstrate its capabilities for nuclear threat detection, spectroscopy, and imaging. The 96-detector instrument was developed and fully characterized within the laboratory environment, yielding a system energy resolution of 2.4% FWHM at 662 keV, an angular resolution of 9.5 deg. FWHM at 662 keV in Compton mode, and a 10.6 deg. angular resolution in coded aperture mode. After event cuts, the effective area for Compton imaging of the 662 keV photopeak is 0.1 cm 22. Imaging of point sources in both Compton and coded aperture modes have been demonstrated. The minimum detectable activity of

  14. Modular X and gamma rays sensor, a space-based instrument for transient lighting events in high atmosphere

    NASA Astrophysics Data System (ADS)

    Reina, M.; Sabau-Graziati, L.; Rodrigo, J. M.; Reglero, V.

    Doing application of the techniques developed on High Energy Gamma rays detection for LEGRI mission of MINISAT satellite, and the experience acquired with INTEGRAL payloads. The scientific and technician team of INTA-GACE is involved into a international consortium, on developing an instrument to detect High Energy Events of very short time duration, similar to Gamma ray burst. Transient Lighting Events (TLE´s), which are present on Terrestrial high atmosphere, and being object of research recently. A space base instrument, to be located on International Space Station (COLUMBUS module), will be enjoy of a superbly location to monitor the earth atmosphere in order to detect those rare events. At same time new detectors and technical challenges are front the team. This article exposes the actual design status and solutions in the MXGS instrument, to give support to gamma sensors.

  15. Development of gamma ray imaging cameras. Progress report for second year

    SciTech Connect

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

    1992-05-28

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

  16. High-resolution imaging gamma-ray spectroscopy with externally segmented germanium detectors

    NASA Technical Reports Server (NTRS)

    Callas, J. L.; Mahoney, W. A.; Varnell, L. S.; Wheaton, W. A.

    1993-01-01

    Externally segmented germanium detectors promise a breakthrough in gamma-ray imaging capabilities while retaining the superb energy resolution of germanium spectrometers. An angular resolution of 0.2 deg becomes practical by combining position-sensitive germanium detectors having a segment thickness of a few millimeters with a one-dimensional coded aperture located about a meter from the detectors. Correspondingly higher angular resolutions are possible with larger separations between the detectors and the coded aperture. Two-dimensional images can be obtained by rotating the instrument. Although the basic concept is similar to optical or X-ray coded-aperture imaging techniques, several complicating effects arise because of the penetrating nature of gamma rays. The complications include partial transmission through the coded aperture elements, Compton scattering in the germanium detectors, and high background count rates. Extensive electron-photon Monte Carlo modeling of a realistic detector/coded-aperture/collimator system has been performed. Results show that these complicating effects can be characterized and accounted for with no significant loss in instrument sensitivity.

  17. A Fourier transform telescope for sub-arcsecond imaging of X-rays and gamma rays

    NASA Technical Reports Server (NTRS)

    Crannell, C. J.; Orwig, L. E.; Hurford, G. J.; Prince, T. A.

    1986-01-01

    This paper describes a Fourier transform telescope designed to image solar flare X-rays and gamma rays at energies up to 1 MeV with arcsec resolution. The imaging technique makes use of a bigrid collimator divided into a number of smaller areas called subcollimators. The grids in each subcollimator consist of a set of linear apertures so configured that each subcollimator provides a measurement of a single Fourier component of the angular distribution of the source. The imaging concept is therefore a mathematical analog to aperture synthesis in radio astronomy. For X-ray and gamma-ray astronomy, this approach has significant advantages in terms of relaxed requirements for astronomy, this approach has significant advantages in terms of relaxed requirements for position sensitivity in the detector and for control of grid alignment in the large scale telescope structure. The concept of the Fourier transform telescope will be illustrated with numerical parameters of a version now under study for the Pinhole/Occulter Facility.

  18. Gamma-ray imaging as a tool for uranium processing plants

    SciTech Connect

    Ziock, K.P.; Madison, L.; McGinnis, B.R.

    1995-08-03

    Gamma-radiation is frequently used as an analysis and characterization signal to monitor material in the nuclear fuel processing cycle. The selection as a diagnostic is self-evident since the radiation is ubiquitous, characteristic of the isotopes present, and sufficiently penetrating so that measurements may be made remotely. However, save through detector proximity or minimal collimation, the directional nature of the radiation is generally not used in traditional nondestructive assay (NDA) measurements. To demonstrate the additional information available, we used GRIS, the Gamma-Ray Imaging Spectrometer, at the K-25 and Portsmouth gaseous diffusion plants. In this facility, UF{sub 6} gas is enriched in heated equipment and piping which run inside an insulated housing. Occasionally, the process develops uranium deposits due to leakage of wet air or environmental changes within the housing that cause solidification of the process gas. When such deposits occur, traditional NDA techniques frequently require costly and time-consuming entry within the heat shielding to obtain precise information on the deposit unavailable from outside the shielding. In this paper we discuss GRIS, the gamma-ray imaging technique it uses, and present the results of measurements obtained on fuel processing equipment.

  19. Solar Particle Acceleration and The Gamma Ray Imager/Polarimeter for Solar Flares (GRIPS) Instrument

    NASA Astrophysics Data System (ADS)

    Duncan, Nicole; Shih, A. Y.; Hurford, G. J.; Saint-Hilaire, P.; Bain, H.; Zoglauer, A.; Lin, R. P.; Boggs, S. E.

    2013-04-01

    Flares accelerate ions and relativistic electrons proportionally; the ratio of their fluences has been shown to remain constant over three orders of magnitude, a correlation that is independent of flare size. This evidence suggests that ion and electron populations are accelerated together, and possibly by similar mechanisms. In two of the best-observed flares of the last cycle, the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) satellite found the centroids of ion and relativistic electron associated emission to be significantly displaced from one another. This result is surprising; ions and electrons that are accelerated in the same region are thought to be transported along the same field lines, implying that they would enter the chromosphere together and have similar emission source locations. The Gamma-Ray Imager/Polarimeter for Solar Flares (GRIPS) instrument is designed to address particle transport questions by providing enhanced imaging, spectroscopy and polarimetry of gamma/HXR flare emissions 20 keV to > 10MeV). GRIPS’ key technological improvements over the current solar state of the art in HXR/gamma ray energies (RHESSI) include the use of three dimensional germanium detectors (3D-GeDs) and a single grid modulation collimator design, the multi-pitch rotating modulator (MPRM). The 3D-GeDs allow GRIPS to Compton track energy deposition within the crystal, providing significant background reduction and solar polarization measurements. Imaging will be primarily accomplished through the MPRM grid system. The single grid design provides quasi-continuous resolution from 12.5 - 162arcsecs with 2x the throughput of a dual grid imaging system like RHESSI. This spatial resolution will be capable of imaging the separate footpoints of many flare sizes. In comparison, RHESSI images with a minimum of 35arcsecs at HXR/gamma ray energies, making the footpoints resolvable in only the largest of flares. Here, we present a discussion of GRIPS science

  20. TARGET 5: A new multi-channel digitizer with triggering capabilities for gamma-ray atmospheric Cherenkov telescopes

    NASA Astrophysics Data System (ADS)

    Albert, A.; Funk, S.; Katagiri, H.; Kawashima, T.; Murphy, M.; Okumura, A.; Quagliani, R.; Sapozhnikov, L.; Shigenaka, A.; Tajima, H.; Tibaldo, L.; Vandenbroucke, J.; Varner, G.; Wu, T.

    2017-06-01

    TARGET 5 is a new application-specific integrated circuit (ASIC) of the TARGET family, designed for the readout of signals from photosensors in the cameras of imaging atmospheric Cherenkov telescopes (IACTs) for ground-based gamma-ray astronomy. TARGET 5 combines sampling and digitization on 16 signal channels with the formation of trigger signals based on the analog sum of groups of four channels. We describe the ASIC architecture and performance. TARGET 5 improves over the performance of the first-generation TARGET ASIC, achieving: tunable sampling frequency from <0.4 GSa/s to >1 GSa/s; a dynamic range on the data path of 1.2 V with effective dynamic range of 11 bits and DC noise of ∼0.6 mV; 3-dB bandwidth of 500 MHz; crosstalk between adjacent channels <1.3%; charge resolution improving from 40% to <4% between 3 photoelectrons (p.e.) and >100 p.e. (assuming 4 mV per p.e.); and minimum stable trigger threshold of 20 mV (5 p.e.) with trigger noise of 5 mV (1.2 p.e.), which is mostly limited by interference between trigger and sampling operations. TARGET 5 is the first ASIC of the TARGET family used in an IACT prototype, providing one development path for readout electronics in the forthcoming Cherenkov Telescope Array (CTA).

  1. A Compton scatter camera for spectral imaging of 0.5 to 3.0 MeV gamma rays

    SciTech Connect

    Martin, Jeffrey Basil

    1994-01-01

    A prototype Compton scatter camera for imaging gamma rays has been built and tested. This camera addresses unique aspects of gamma-ray imaging at nuclear industrial sites, including gamma-ray energies in the 0.5 to 3.0 MeV range and polychromatic fields. Analytic models of camera efficiency, resolution and contaminating events are developed. The response of the camera bears strong similarity to emission computed tomography devices used in nuclear medicine. A direct Fourier based algorithm is developed to reconstruct two-dimensional images of measured gamma-ray fields. Iterative ART and MLE algorithms are also investigated. The point response of the camera to gamma rays of energies from 0.5 to 2.8 MeV is measured and compared to the analytic models. The direct reconstruction algorithm is at least ten times more efficient than the iterative algorithms are also investigated. The point response of the camera to gamma rays energies from 0.5 to 2.8 MeV is measured and compared to the analytic models. The direct reconstruction algorithm is at least ten times more efficient than the iterative algorithms and produces images that are, in general, of the same quality. Measured images of several phantoms are shown. Important results include angular resolutions as low as 4.4{degrees}, reproduction of phantom size and position within 7%, and contrast recovery of 84% or better. Spectral imaging is demonstrated with independent images from a multi-energy phantom consisting of two sources imaged simultaneously.

  2. High energy gamma-ray observations of the Crab Nebula and pulsar with the Solar Tower Atmospheric Cherenkov Effect Experiment

    NASA Astrophysics Data System (ADS)

    Oser, Scott Michael

    The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a new ground-based atmospheric Cherenkov telescope for gamma-ray astronomy. STACEE uses the large mirror area of a solar heliostat facility to achieve a low energy threshold. A prototype experiment which uses 32 heliostat mirrors with a total mirror area of ~1200 m2 has been constructed. This prototype, called STACEE-32, was used to search for high energy gamma-ray emission from the Crab Nebula and Pulsar. Observations taken between November 1998 and February 1999 yield a strong statistical excess of gamma- like events from the Crab, with a significance of +6.75σ in 43 hours of on-source observing time. No evidence for pulsed emission from the Crab Pulsar was found, and the upper limit on the pulsed fraction of the observed excess was < 5.5% at the 90% confidence level. A subset of the data was used to determine the integral flux of gamma rays from the Crab. We report an energy threshold of Eth = 190 +/- 60 GeV, and a measured integral flux of I(E > Eth) = (2.2 +/- 0.6 +/- 0.2) × 10-10 photons cm-2 s-1. The observed flux is in agreement with a continuation to lower energies of the power law spectrum seen at TeV energies.

  3. A Spherical Active Coded Aperture for 4π Gamma-ray Imaging

    DOE PAGES

    Hellfeld, Daniel; Barton, Paul; Gunter, Donald; ...

    2017-09-22

    Gamma-ray imaging facilitates the efficient detection, characterization, and localization of compact radioactive sources in cluttered environments. Fieldable detector systems employing active planar coded apertures have demonstrated broad energy sensitivity via both coded aperture and Compton imaging modalities. But, planar configurations suffer from a limited field-of-view, especially in the coded aperture mode. In order to improve upon this limitation, we introduce a novel design by rearranging the detectors into an active coded spherical configuration, resulting in a 4pi isotropic field-of-view for both coded aperture and Compton imaging. This work focuses on the low- energy coded aperture modality and the optimization techniquesmore » used to determine the optimal number and configuration of 1 cm3 CdZnTe coplanar grid detectors on a 14 cm diameter sphere with 192 available detector locations.« less

  4. Hard X-ray and gamma-ray imaging spectroscopy for the next solar maximum

    NASA Technical Reports Server (NTRS)

    Hudson, H. S.; Crannell, C. J.; Dennis, B. R.; Spicer, D. S.; Davis, J. M.; Hurford, G. J.; Lin, R. P.

    1990-01-01

    The objectives and principles are described of a single spectroscopic imaging package that can provide effective imaging in the hard X- and gamma-ray ranges. Called the High-Energy Solar Physics (HESP) mission instrument for solar investigation, the device is based on rotating modulation collimators with germanium semiconductor spectrometers. The instrument is planned to incorporate thick modulation plates, and the range of coverage is discussed. The optics permit the coverage of high-contrast hard X-ray images from small- and medium-sized flares with large signal-to-noise ratios. The detectors allow angular resolution of less than 1 arcsec, time resolution of less than 1 arcsec, and spectral resolution of about 1 keV. The HESP package is considered an effective and important instrument for investigating the high-energy solar events of the near-term future efficiently.

  5. Source-Search Sensitivity of a Large-Area, Coded-Aperture, Gamma-Ray Imager

    SciTech Connect

    Ziock, K P; Collins, J W; Craig, W W; Fabris, L; Lanza, R C; Gallagher, S; Horn, B P; Madden, N W; Smith, E; Woodring, M L

    2004-10-27

    We have recently completed a large-area, coded-aperture, gamma-ray imager for use in searching for radiation sources. The instrument was constructed to verify that weak point sources can be detected at considerable distances if one uses imaging to overcome fluctuations in the natural background. The instrument uses a rank-19, one-dimensional coded aperture to cast shadow patterns onto a 0.57 m{sup 2} NaI(Tl) detector composed of 57 individual cubes each 10 cm on a side. These are arranged in a 19 x 3 array. The mask is composed of four-centimeter thick, one-meter high, 10-cm wide lead blocks. The instrument is mounted in the back of a small truck from which images are obtained as one drives through a region. Results of first measurements obtained with the system are presented.

  6. Focal Plane Detectors for the Advanced Gamma-Ray Imaging System (AGIS)

    SciTech Connect

    Otte, A. N.; Williams, D. A.; Byrum, K.; Drake, G.; Horan, D.; Smith, A.; Wagner, R. G.; Falcone, A.; Funk, S.; Tajima, H.; Mukherjee, R.

    2008-12-24

    The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation observatory in ground-based very high energy gamma-ray astronomy. Design goals are ten times better sensitivity, higher angular resolution, and a lower energy threshold than existing Cherenkov telescopes. Simulations show that a substantial improvement in angular resolution may be achieved if the pixel diameter is reduced to the order of 0.05 deg, i.e. two to three times smaller than the pixel diameter of current Cherenkov telescope cameras. At these dimensions, photon detectors with smaller physical dimensions can be attractive alternatives to the classical photomultiplier tube (PMT). Furthermore, the operation of an experiment with the size of AGIS requires photon detectors that are among other things more reliable, more durable, and possibly higher efficiency photon detectors. Alternative photon detectors we are considering for AGIS include both silicon photomultipliers (SiPMs) and multi-anode photomultipliers (MAPMTs). Here we present results from laboratory testing of MAPMTs and SiPMs along with results from the first incorporation of these devices into cameras on test bed Cherenkov telescopes.

  7. Predicted TeV Gamma-ray Spectra and Images of Shell Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Reynolds, S. P.

    1999-04-01

    One supernova remnant, SN 1006, is now known to produce synchrotron X-rays (Koyama et al., 1995, Nature, 378, 255), requiring 100 TeV electrons. SN 1006 has also been seen in TeV gamma rays (Tanimori et al., 1998, ApJ, 497, L25), almost certainly due to cosmic-microwave-background photons being upscattered by those same electrons. Other young supernova remnants should also produce high-energy electrons, even if their X-ray synchrotron emission is swamped by conventional thermal X-ray emission. Upper limits to the maximum energy of shock-accelerated electrons can be found for those remnants by requiring that their synchrotron spectrum steepen enough to fall below observed thermal X-rays (Reynolds and Keohane 1999, ApJ, submitted). For those upper-limit spectra, I present predicted TeV inverse-Compton spectra and images for assumed values of the mean remnant magnetic field. Ground-based TeV gamma-ray observations of remnants may be able to put even more severe limits on the presence of highly energetic electrons in remnants, raising problems for conventional theories of galactic cosmic-ray production in supernova remnants. Detections will immediately confirm that SN 1006 is not alone, and will give mean remnant magnetic field strengths.

  8. Progress of Focusing X-ray and Gamma-ray Optics for Small Animal Imaging

    SciTech Connect

    Pivovaroff, M J; Funk, T; Barber, W C; Ramsey, B D; Hasegawa, B H

    2005-08-05

    Significant effort is currently being devoted to the development of noninvasive imaging systems that allow in vivo assessment of biological and biomolecular interactions in mice and other small animals. Ideally, one would like to discern these functional and metabolic relationships with in vivo radionuclide imaging at spatial resolutions approaching those that can be obtained using the anatomical imaging techniques (i.e., <100 {micro}m), which would help to answer outstanding questions in many areas of biomedicine. In this paper, we report progress on our effort to develop high-resolution focusing X-ray and gamma-ray optics for small-animal radionuclide imaging. The use of reflective optics, in contrast to methods that rely on absorptive collimation like single- or multiple-pinhole cameras, decouples spatial resolution from sensitivity (efficiency). Our feasibility studies have refined and applied ray-tracing routines to design focusing optics for small animal studies. We also have adopted a replication technique to manufacture the X-ray mirrors, and which in experimental studies have demonstrated a spatial resolution of {approx}190 {micro}m. We conclude that focusing optics can be designed and fabricated for gamma-ray energies, and with spatial resolutions, and field of view suitable for in vivo biological studies. While the efficiency of a single optic is limited, fabrication methods now are being developed that may make it possible to develop imaging systems with multiple optics that could collect image data over study times that would be practical for performing radionuclide studies of small animals.

  9. Research and development of a gamma-ray imaging spectrometer in the MeV range in Barcelona

    NASA Astrophysics Data System (ADS)

    Alvarez, José-Manuel; Galvez, José-Luis; Hernanz, Margarita; Isern, Jordi; Lozano, Manuel; Pellegrini, Giulio; Chmeissani, Mokhtar; Cabruja, Enric; Ullán, Miguel

    2010-07-01

    Gamma-ray astrophysics in the MeV energy range plays an important role for the understanding of cosmic explosions and acceleration mechanisms in a variety of galactic and extragalactic sources, e.g., Supernovae, Classical Novae, Supernova Remnants (SNRs), Gamma-Ray Bursts (GRBs), Pulsars, Active Galactic Nuclei (AGN). Through the development of focusing telescopes in the MeV energy range, it will be possible to reach unprecedented sensitivities, compared with those of the currently operating gamma ray telescopes. In order to achieve the needed performance, a detector with mm spatial resolution and very high peak efficiency is required. It will be also desirable that the detector could detect polarization of the source. Our research and development activities in Barcelona aim to study a gamma-ray imaging spectrometer in the MeV range suited for the focal plane of a gamma-ray telescope mission, based on CdTe pixel detectors arranged in multiple layers with increasing thicknesses, to enhance gamma-ray absorption in the Compton regime. We have developed an initial prototype based on several CdTe module detectors, with 11x11 pixels, a pixel pitch of 1mm and a thickness of 2mm. Each pixel is stud-bump bonded to a fanout board and routed to a readout ASIC to measure pixel position, pulse height and rise time information for each incident gamma-ray photon. We will report on the results of an optimization study based on simulations, to select the optimal thickness of each CdTe detector within the module to get the best energy resolution of the spectrometer.

  10. High-Resolution Gamma-Ray Imaging Measurements Using Externally Segmented Germanium Detectors

    NASA Technical Reports Server (NTRS)

    Callas, J.; Mahoney, W.; Skelton, R.; Varnell, L.; Wheaton, W.

    1994-01-01

    Fully two-dimensional gamma-ray imaging with simultaneous high-resolution spectroscopy has been demonstrated using an externally segmented germanium sensor. The system employs a single high-purity coaxial detector with its outer electrode segmented into 5 distinct charge collection regions and a lead coded aperture with a uniformly redundant array (URA) pattern. A series of one-dimensional responses was collected around 511 keV while the system was rotated in steps through 180 degrees. A non-negative, linear least-squares algorithm was then employed to reconstruct a 2-dimensional image. Corrections for multiple scattering in the detector, and the finite distance of source and detector are made in the reconstruction process.

  11. Development of Gamma-Ray Compton Imager Using Room-Temperature 3-D Position Sensitive Semiconductor Detectors

    SciTech Connect

    Zhong He; David Whe; Glenn Knoll

    2003-05-14

    During the three years of this project, two 3-dimensional position sensitive CdZnTe spectrometers were upgraded in collaboration with Johns Hopkins University Applied Physics Laboratory. A prototype Compton-scattering gamma-ray imager was assembled using the two upgraded CdZnTe detectors. The performance of both gamma-ray spectrometers were individually tested. The angular resolution and detection sensitivity of the imaging system were measured using both a point and a line-shaped 137 Cs radiation source. The measurement results are consistent with that obtained from Monte-Carlo simulations performed during the early phase of the project.

  12. Gamma Ray Imaging System (GRIS) GammaCam{trademark}. Final report, January 3, 1994--May 31, 1996

    SciTech Connect

    1996-12-31

    This report describes the activities undertaken during the development of the Gamma Ray Imaging System (GRIS) program now referred to as the GammaCam{trademark}. The purpose of this program is to develop a 2-dimensional imaging system for gamma-ray energy scenes that may be present in nuclear power plants. The report summarizes the overall accomplishments of the program and the most recent GammaCam measurements made at LANL and Estonia. The GammaCam is currently available for sale from AIL Systems as an off-the-shelf instrument.

  13. High resolution phoswich gamma-ray imager utilizing monolithic MPPC arrays with submillimeter pixelized crystals

    NASA Astrophysics Data System (ADS)

    Kato, T.; Kataoka, J.; Nakamori, T.; Kishimoto, A.; Yamamoto, S.; Sato, K.; Ishikawa, Y.; Yamamura, K.; Kawabata, N.; Ikeda, H.; Kamada, K.

    2013-05-01

    We report the development of a high spatial resolution tweezers-type coincidence gamma-ray camera for medical imaging. This application consists of large-area monolithic Multi-Pixel Photon Counters (MPPCs) and submillimeter pixelized scintillator matrices. The MPPC array has 4 × 4 channels with a three-side buttable, very compact package. For typical operational gain of 7.5 × 105 at + 20 °C, gain fluctuation over the entire MPPC device is only ± 5.6%, and dark count rates (as measured at the 1 p.e. level) amount to <= 400 kcps per channel. We selected Ce-doped (Lu,Y)2(SiO4)O (Ce:LYSO) and a brand-new scintillator, Ce-doped Gd3Al2Ga3O12 (Ce:GAGG) due to their high light yield and density. To improve the spatial resolution, these scintillators were fabricated into 15 × 15 matrices of 0.5 × 0.5 mm2 pixels. The Ce:LYSO and Ce:GAGG scintillator matrices were assembled into phosphor sandwich (phoswich) detectors, and then coupled to the MPPC array along with an acrylic light guide measuring 1 mm thick, and with summing operational amplifiers that compile the signals into four position-encoded analog outputs being used for signal readout. Spatial resolution of 1.1 mm was achieved with the coincidence imaging system using a 22Na point source. These results suggest that the gamma-ray imagers offer excellent potential for applications in high spatial medical imaging.

  14. Lunar based gamma ray astronomy

    NASA Astrophysics Data System (ADS)

    Haymes, R. C.

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

  15. A study of the sensitivity of an imaging telescope (GRITS) for high energy gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Yearian, Mason R.

    1990-01-01

    When a gamma-ray telescope is placed in Earth orbit, it is bombarded by a flux of cosmic protons much greater than the flux of interesting gammas. These protons can interact in the telescope's thermal shielding to produce detectable gamma rays, most of which are vetoed. Since the proton flux is so high, the unvetoed gamma rays constitute a significant background relative to some weak sources. This background increases the observing time required to pinpoint some sources and entirely obscures other sources. Although recent telescopes have been designed to minimize this background, its strength and spectral characteristics were not previously calculated in detail. Monte Carlo calculations are presented which characterize the strength, spectrum and other features of the cosmic proton background using FLUKA, a hadronic cascade program. Several gamma-ray telescopes, including SAS-2, EGRET and the Gamma Ray Imaging Telescope System (GRITS), are analyzed, and their proton-induced backgrounds are characterized. In all cases, the backgrounds are either shown to be low relative to interesting signals or suggestions are made which would reduce the background sufficiently to leave the telescope unimpaired. In addition, several limiting cases are examined for comparison to previous estimates and calibration measurements.

  16. SU-C-201-03: Coded Aperture Gamma-Ray Imaging Using Pixelated Semiconductor Detectors

    SciTech Connect

    Joshi, S; Kaye, W; Jaworski, J; He, Z

    2015-06-15

    Purpose: Improved localization of gamma-ray emissions from radiotracers is essential to the progress of nuclear medicine. Polaris is a portable, room-temperature operated gamma-ray imaging spectrometer composed of two 3×3 arrays of thick CdZnTe (CZT) detectors, which detect gammas between 30keV and 3MeV with energy resolution of <1% FWHM at 662keV. Compton imaging is used to map out source distributions in 4-pi space; however, is only effective above 300keV where Compton scatter is dominant. This work extends imaging to photoelectric energies (<300keV) using coded aperture imaging (CAI), which is essential for localization of Tc-99m (140keV). Methods: CAI, similar to the pinhole camera, relies on an attenuating mask, with open/closed elements, placed between the source and position-sensitive detectors. Partial attenuation of the source results in a “shadow” or count distribution that closely matches a portion of the mask pattern. Ideally, each source direction corresponds to a unique count distribution. Using backprojection reconstruction, the source direction is determined within the field of view. The knowledge of 3D position of interaction results in improved image quality. Results: Using a single array of detectors, a coded aperture mask, and multiple Co-57 (122keV) point sources, image reconstruction is performed in real-time, on an event-by-event basis, resulting in images with an angular resolution of ∼6 degrees. Although material nonuniformities contribute to image degradation, the superposition of images from individual detectors results in improved SNR. CAI was integrated with Compton imaging for a seamless transition between energy regimes. Conclusion: For the first time, CAI has been applied to thick, 3D position sensitive CZT detectors. Real-time, combined CAI and Compton imaging is performed using two 3×3 detector arrays, resulting in a source distribution in space. This system has been commercialized by H3D, Inc. and is being acquired for

  17. Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics

    NASA Astrophysics Data System (ADS)

    Tanimori, Toru; Mizumura, Yoshitaka; Takada, Atsushi; Miyamoto, Shohei; Takemura, Taito; Kishimoto, Tetsuro; Komura, Shotaro; Kubo, Hidetoshi; Kurosawa, Shunsuke; Matsuoka, Yoshihiro; Miuchi, Kentaro; Mizumoto, Tetsuya; Nakamasu, Yuma; Nakamura, Kiseki; Parker, Joseph D.; Sawano, Tatsuya; Sonoda, Shinya; Tomono, Dai; Yoshikawa, Kei

    2017-02-01

    Since the discovery of nuclear gamma-rays, its imaging has been limited to pseudo imaging, such as Compton Camera (CC) and coded mask. Pseudo imaging does not keep physical information (intensity, or brightness in Optics) along a ray, and thus is capable of no more than qualitative imaging of bright objects. To attain quantitative imaging, cameras that realize geometrical optics is essential, which would be, for nuclear MeV gammas, only possible via complete reconstruction of the Compton process. Recently we have revealed that “Electron Tracking Compton Camera” (ETCC) provides a well-defined Point Spread Function (PSF). The information of an incoming gamma is kept along a ray with the PSF and that is equivalent to geometrical optics. Here we present an imaging-spectroscopic measurement with the ETCC. Our results highlight the intrinsic difficulty with CCs in performing accurate imaging, and show that the ETCC surmounts this problem. The imaging capability also helps the ETCC suppress the noise level dramatically by ~3 orders of magnitude without a shielding structure. Furthermore, full reconstruction of Compton process with the ETCC provides spectra free of Compton edges. These results mark the first proper imaging of nuclear gammas based on the genuine geometrical optics.

  18. Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics.

    PubMed

    Tanimori, Toru; Mizumura, Yoshitaka; Takada, Atsushi; Miyamoto, Shohei; Takemura, Taito; Kishimoto, Tetsuro; Komura, Shotaro; Kubo, Hidetoshi; Kurosawa, Shunsuke; Matsuoka, Yoshihiro; Miuchi, Kentaro; Mizumoto, Tetsuya; Nakamasu, Yuma; Nakamura, Kiseki; Parker, Joseph D; Sawano, Tatsuya; Sonoda, Shinya; Tomono, Dai; Yoshikawa, Kei

    2017-02-03

    Since the discovery of nuclear gamma-rays, its imaging has been limited to pseudo imaging, such as Compton Camera (CC) and coded mask. Pseudo imaging does not keep physical information (intensity, or brightness in Optics) along a ray, and thus is capable of no more than qualitative imaging of bright objects. To attain quantitative imaging, cameras that realize geometrical optics is essential, which would be, for nuclear MeV gammas, only possible via complete reconstruction of the Compton process. Recently we have revealed that "Electron Tracking Compton Camera" (ETCC) provides a well-defined Point Spread Function (PSF). The information of an incoming gamma is kept along a ray with the PSF and that is equivalent to geometrical optics. Here we present an imaging-spectroscopic measurement with the ETCC. Our results highlight the intrinsic difficulty with CCs in performing accurate imaging, and show that the ETCC surmounts this problem. The imaging capability also helps the ETCC suppress the noise level dramatically by ~3 orders of magnitude without a shielding structure. Furthermore, full reconstruction of Compton process with the ETCC provides spectra free of Compton edges. These results mark the first proper imaging of nuclear gammas based on the genuine geometrical optics.

  19. Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics

    PubMed Central

    Tanimori, Toru; Mizumura, Yoshitaka; Takada, Atsushi; Miyamoto, Shohei; Takemura, Taito; Kishimoto, Tetsuro; Komura, Shotaro; Kubo, Hidetoshi; Kurosawa, Shunsuke; Matsuoka, Yoshihiro; Miuchi, Kentaro; Mizumoto, Tetsuya; Nakamasu, Yuma; Nakamura, Kiseki; Parker, Joseph D.; Sawano, Tatsuya; Sonoda, Shinya; Tomono, Dai; Yoshikawa, Kei

    2017-01-01

    Since the discovery of nuclear gamma-rays, its imaging has been limited to pseudo imaging, such as Compton Camera (CC) and coded mask. Pseudo imaging does not keep physical information (intensity, or brightness in Optics) along a ray, and thus is capable of no more than qualitative imaging of bright objects. To attain quantitative imaging, cameras that realize geometrical optics is essential, which would be, for nuclear MeV gammas, only possible via complete reconstruction of the Compton process. Recently we have revealed that “Electron Tracking Compton Camera” (ETCC) provides a well-defined Point Spread Function (PSF). The information of an incoming gamma is kept along a ray with the PSF and that is equivalent to geometrical optics. Here we present an imaging-spectroscopic measurement with the ETCC. Our results highlight the intrinsic difficulty with CCs in performing accurate imaging, and show that the ETCC surmounts this problem. The imaging capability also helps the ETCC suppress the noise level dramatically by ~3 orders of magnitude without a shielding structure. Furthermore, full reconstruction of Compton process with the ETCC provides spectra free of Compton edges. These results mark the first proper imaging of nuclear gammas based on the genuine geometrical optics. PMID:28155870

  20. Development of a High Resolution Liquid Xenon Imaging Telescope for Medium Energy Gamma Ray Astrophysics

    NASA Technical Reports Server (NTRS)

    Aprile, Elena

    1992-01-01

    In the third year of the research project, we have (1) tested a 3.5 liter prototype of the Liquid Xenon Time Projection Chamber, (2) used a prototype having a 4.4 cm drift gap to study the charge and energy resolution response of the 3.5 liter chamber, (3) obtained an energy resolution as good as that previously measured by us using chambers with drift gaps of the order of millimeters, (4) observed the induction signals produced by MeV gamma rays, (4) used the 20 hybrid charge sensitive preamplifiers for a nondestructive readout of the electron image on the induction wires, (5) performed extensive Monte Carlo simulations to obtain results on efficiency, background rejection capability, and source flux sensitivity, and (6) developed a reconstruction algorithm for events with multiple interaction points.

  1. Compact, high-resolution, gamma ray imaging for scintimammography and other medical diagostic applications

    DOEpatents

    Majewski, Stanislaw; Weisenberger, Andrew G.; Wojcik, Randolph F.; Steinbach, Daniela

    1999-01-01

    A high resolution gamma ray imaging device includes an aluminum housing, a lead screen collimator at an opened end of the housing, a crystal scintillator array mounted behind the lead screen collimator, a foam layer between the lead screen collimator and the crystal scintillator array, a photomultiplier window coupled to the crystal with optical coupling grease, a photomultiplier having a dynode chain body and a base voltage divider with anodes, anode wire amplifiers each connected to four anodes and a multi pin connector having pin connections to each anode wire amplifier. In one embodiment the crystal scintillator array includes a yttrium aluminum perovskite (YAP) crystal array. In an alternate embodiment, the crystal scintillator array includes a gadolinium oxyorthosilicate (GSO) crystal array.

  2. A practical approach to transverse-section gamma-ray imaging.

    PubMed

    Keyes, W I

    1976-01-01

    The object of transverse-section gamma-ray imaging is to display the concentration of radioactive material in a thin transverse slice of the body. The technique is essentially that of reconstructing a density distribution from its projections, and many methods have been developed to perform the reconstruction. This report describes the realization of three such methods, using a small digital computer PDP8 I, and their application to experimental and clinical data obtained from the Aberdeen Section Scanner: (1) simple back projection; (2) the convolution method of Bracewell and Riddle; (3) the linear integral transform method of Radon. The problems of sensitivity variation and attenuation are examined. An approximate attenuation correction procedure is described. The reconstruction method of Bracewell and Riddle was found convenient since then the data were manipulated in a manner where smoothing to reduce statistical noise and correction for absorption could both be readily incorporated.

  3. Micro-Slit Collimators for X-Ray/Gamma-Ray Imaging

    NASA Technical Reports Server (NTRS)

    Appleby, Michael; Fraser, Iain; Klinger, Jill

    2011-01-01

    A hybrid photochemical-machining process is coupled with precision stack lamination to allow for the fabrication of multiple ultra-high-resolution grids on a single array substrate. In addition, special fixturing and etching techniques have been developed that allow higher-resolution multi-grid collimators to be fabricated. Building on past work of developing a manufacturing technique for fabricating multi-grid, high-resolution coating modulation collimators for arcsecond and subarcsecond x-ray and gamma-ray imaging, the current work reduces the grid pitch by almost a factor of two, down to 22 microns. Additionally, a process was developed for reducing thin, high-Z (tungsten or molybdenum) from the thinnest commercially available foil (25 microns thick) down to approximately equal to 10 microns thick using precisely controlled chemical etching

  4. Development of image reconstruction for Gamma-ray CT of large-dimension industrial plants using Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Khorsandi, M.; Feghhi, S. A. H.

    2015-08-01

    In industrial Gamma-ray CT, specifically for large-dimension plants or processes, the simplicity and portability of CT system necessitate to use individual gamma-ray detectors for imaging purposes. Considering properties of the gamma-ray source as well as characteristics of the detectors, including penetration depth, energy resolution, size, etc., the quality of reconstructed images is limited. Therefore, implementation of an appropriate reconstruction procedure is important to improve the image quality. In this paper, an accurate and applicable procedure has been proposed for image reconstruction of Gamma-ray CT of large-dimension industrial plants. Additionally, a portable configuration of tomographic system was introduced and simulated in MCNPX Monte Carlo code. The simulation results were validated through comparison with the experimental results reported in the literature. Evaluations showed that maximum difference between reconstruction error in this work and the benchmark was less than 1.3%. Additional investigation has been carried out on a typical standard phantom introduced by IAEA using the validated procedure. Image quality assessment showed that the reconstruction error was less than 1.7% using different algorithms and a good contrast higher than 76% was obtained. Our overall results are indicative of the fact that the procedures and methods introduced in this work are quite efficient for improving the image quality of gamma CT of industrial plants.

  5. The fate of accreted CNO elements in neutron star atmospheres - X-ray bursts and gamma-ray lines

    NASA Technical Reports Server (NTRS)

    Bildstein, Lars; Salpeter, Edwin E.; Wasserman, Ira

    1992-01-01

    The fate of incident C-12, N-14, and O-16 in accreting neutron star atmospheres is described. When the accreting material is stopped by Coulomb collisions with atmospheric electrons, all incoming elements heavier than helium thermalize at higher altitudes in the atmosphere than the accreting protons. The incoming protons and helium then destroy the elements via nuclear spallation reactions. A small fraction of the nuclear reactions cause nuclear excitation and subsequent gamma-ray emission. The probability for a nucleus to survive this bombardment depends on how long it spends in the hazardous region of the atmosphere. The fractions of incident C-12, N-14, and O-16 that survive proton bombardment are calculated as a function of the accretion rate, and the mass and radius of the neutron star. The subsequent paucity of CNO nuclei decreases hydrogen-burning rates in the deep regions of the atmosphere, thereby reducing the amount of helium available for the unstable nuclear flashes that cause type I X-ray bursts. The gamma-ray line emission from this collisional deceleration scenario is determined.

  6. The Study of Equilibrium factor between Radon-222 and its Daughters in Bangkok Atmosphere by Gamma-ray Spectrometry

    NASA Astrophysics Data System (ADS)

    Rujiwarodom, Rachanee

    2010-05-01

    To study the Equilibrium between radon-222 and its daughters in Bangkok atmosphere by Gamma-ray spectrometry, air sample were collected on 48 activated charcoal canister and 360 glass fiber filters by using a high volume jet-air sampler during December 2007 to November 2008.The Spectra of gamma-ray were measured by using a HPGe (Hyper Pure Germanium Detector). In the condition of secular equilibrium obtaining between Radon-222 and its decay products, radon-222 on activated charcoal canister and its daughters on glass fiber filters collected in the same time interval were calculated. The equilibrium factor (F) in the open air had a value of 0.38 at the minimum ,and 0.75 at the maximum. The average value of equilibrium factor (F) was 0.56±0.12. Based on the results, F had variations with a maximum value in the night to the early morning and decreased in the afternoon. In addition, F was higher in the winter than in the summer. This finding corresponds with the properties of the Earth atmosphere. The equilibrium factor (F) also depended on the concentration of dust in the atmosphere. People living in Bangkok were exposed to average value of 30 Bq/m3 of Radon-222 in the atmosphere. The equilibrium factor (0.56±0.12) and the average value of Radon-222 showed that people were exposed to alpha energy from radon-222 and its daughters decay at 0.005 WL(Working Level) which is lower than the safety standard at 0.02 WL. Keywords: Radon, Radon daughters , equilibrium factor, Gamma -ray spectrum analysis ,Bangkok ,Thailand

  7. Measurement of spatial distribution of neutrons and gamma rays for BNCT using multi-imaging plate system.

    PubMed

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

    2015-12-01

    Quality assurance of the spatial distributions of neutrons and gamma rays was tried using imaging plates (IPs) and converters to enhance the beam components in the epithermal neutron mode of the Kyoto University Reactor. The converters used were 4mm thick epoxy resin with B4C at 6.85 weight-percent (wt%) (10)B for epithermal neutrons, and 3mm thick carbon for gamma rays. Results suggested that the IP signal does not need a sensitivity correction regardless of the incident radiation that produces it.

  8. Application of CdZnTe Gamma-Ray Detector for Imaging Corrosion under Insulation

    SciTech Connect

    Abdullah, J.; Yahya, R.

    2007-05-09

    Corrosion under insulation (CUI) on the external wall of steel pipes is a common problem in many types of industrial plants. This is mainly due to the presence of moisture or water in the insulation materials. This type of corrosion can cause failures in areas that are not normally of a primary concern to an inspection program. The failures are often the result of localised corrosion and not general wasting over a large area. These failures can tee catastrophic in nature or at least have an adverse economic effect in terms of downtime and repairs. There are a number of techniques used today for CUI investigations. The main ones are profile radiography, pulse eddy current, ultrasonic spot readings and insulation removal. A new system now available is portable Pipe-CUI-Profiler. The nucleonic system is based on dual-beam gamma-ray absorption technique using Cadmium Zinc Telluride (CdZnTe) semiconductor detectors. The Pipe-CUI-Profiler is designed to inspect pipes of internal diameter 50, 65, 80, 90, 100, 125 and 150 mm. Pipeline of these sizes with aluminium or thin steel sheathing, containing fibreglass or calcium silicate insulation to thickness of 25, 40 and 50 mm can be inspected. The system has proven to be a safe, fast and effective method of inspecting pipe in industrial plant operations. This paper describes the application of gamma-ray techniques and CdZnTe semiconductor detectors in the development of Pipe-CUI-Profiler for non-destructive imaging of corrosion under insulation of steel pipes. Some results of actual pipe testing in large-scale industrial plant will be presented.

  9. Monte Carlo modeling of cascade gamma rays in (86)Y PET imaging: preliminary results.

    PubMed

    Zhu, Xuping; El Fakhri, Georges

    2009-07-07

    (86)Y is a PET agent that could be used as an ideal surrogate to allow personalized dosimetry in (90)Y radionuclide therapy. However, (86)Y also emits cascade gamma rays. We have developed a Monte Carlo program based on SimSET (Simulation System for Emission Tomography) to model cascade gamma rays in PET imaging. The new simulation was validated with the GATE simulation package. Agreements within 15% were found in spatial resolution, apparent scatter fraction (ratio of coincidences outside peak regions in line source sinograms), single and coincidence statistics and detected photons energy distribution within the PET energy window. A discrepancy of 20% was observed in the absolute scatter fraction, likely caused by differences in the tracking of higher energy cascade gamma photons. On average, the new simulation is 6 times faster than GATE, and the computing time can be further improved by using variance reduction techniques currently available in SimSET. Comparison with phantom acquisitions showed agreements in spatial resolutions and the general shape of projection profiles; however, the standard scatter correction method on the scanner is not directly applicable to (86)Y PET as it leads to incorrect scatter fractions. The new simulation was used to characterize (86)Y PET. Compared with conventional (18)F PET, in which major contamination at low count rates comes from scattered events, cascade gamma-involved events are more important in (86)Y PET. The two types of contaminations have completely different distribution patterns, which should be considered for the corrections of their effects. Our approach will be further improved in the future in the modeling of random coincidences and tracking of high-energy photons, and simulation results will be used for the development of correction methods in (86)Y PET.

  10. The Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Kniffen, Donald A.

    1991-01-01

    The Gamma Ray Observatory (GRO), scheduled for launch by the Space Shuttle in April 1991, weighs 35,000 lbs and will offer 10 to 20 times better sensitivity than any previous gamma ray mission. The four instruments aboard GRO are described. The Burst and Transient Source Experiment (BATSE) will continuously monitor the entire sky for transient gamma-ray events using eight identical, wide-field detectors capable of measuring brightness variations lasting only milliseconds at energies from about 50,000 to 600,000 eV. The Oriented Scintillation Spectrometer Experiment (OSSE) will make comprehensive observations of discrete sources at energies from 100,000 to 10 million eV, where many radioactive elements have emission lines. The observatory's Imaging Compton Telescope will conduct a deep survey of the entire sky at gamma-ray energies between 1 and 30 MeV. The Energetic Gamma Ray Experiment Telescope will cover a broad high-energy spectral range, from about 20 million to 30 billion eV and conduct a sensitive all-sky survey with a wide field of view and good angular resolution.

  11. Gamma ray camera

    DOEpatents

    Perez-Mendez, V.

    1997-01-21

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

  12. Gamma ray camera

    DOEpatents

    Perez-Mendez, Victor

    1997-01-01

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

  13. 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.

  14. Gamma-ray Polarimetry

    SciTech Connect

    Tajima, Hiroyasu

    2003-02-05

    An astrophysics application of a low noise Double-sided Silicon Strip Detector (DSSD) is described. A Semiconductor Multiple-Compton Telescope (SMCT) is being developed to explore the gamma-ray universe in the 0.1-20 MeV energy band. Excellent energy resolution and polarization sensitivity are key features of the SMCT. We have developed prototype modules for a low-noise DSSD system, which reached an energy resolution of 1.3 keV (FWHM) for 122 keV at 0 C. Results of a gamma-ray imaging test are also presented.

  15. Report on the performance of a large-area, gamma-ray imager for search

    SciTech Connect

    Fabris, L; Ziock, K

    2005-10-07

    We are currently constructing a prototype, large-area, gamma-ray detector for conducting vehicle-mounted, mobile-search operations. The system is unique in that it relies on imaging to discriminate point sources of interest from the natural background variations. In a non-imaging instrument the background fluctuations mimic the signature seen from real sources at a distance and one is limited in sensitivity to detecting only those sources that overwhelm the local background variations --not just the counting statistics associated with a given measurement. The net result is that a larger detector is generally not more sensitive to detecting sources in the world at large. [1, 2] In a previous publication [3] we reported on the detection of a 1-mCi source at more than 80 meters from the detector using a proof-of-principle instrument (see Fig. 1) constructed to demonstrate how imaging removes the size limit on search instruments. In this report we document a systematic effort using the same detector to demonstrate that imaging detectors can reliably detect weak radiation sources at many 10's of meters. Specifically, we collected data on a 1-mCi {sup 137}Cs source 65 m from the path of the search instrument.

  16. Primary gamma ray selection in a hybrid timing/imaging Cherenkov array

    NASA Astrophysics Data System (ADS)

    Postnikov, E. B.; Grinyuk, A. A.; Kuzmichev, L. A.; Sveshnikova, L. G.

    2017-06-01

    This work is a methodical study on hybrid reconstruction techniques for hybrid imaging/timing Cherenkov observations. This type of hybrid array is to be realized at the gamma-observatory TAIGA intended for very high energy gamma-ray astronomy (> 30 TeV). It aims at combining the cost-effective timing-array technique with imaging telescopes. Hybrid operation of both of these techniques can lead to a relatively cheap way of development of a large area array. The joint approach of gamma event selection was investigated on both types of simulated data: the image parameters from the telescopes, and the shower parameters reconstructed from the timing array. The optimal set of imaging parameters and shower parameters to be combined is revealed. The cosmic ray background suppression factor depending on distance and energy is calculated. The optimal selection technique leads to cosmic ray background suppression of about 2 orders of magnitude on distances up to 450 m for energies greater than 50 TeV.

  17. Large-area PSPMT based gamma-ray imager with edge reclamation

    SciTech Connect

    Ziock, K-P; Nakae, L

    2000-09-21

    We describe a coded aperture, gamma-ray imager which uses a CsI(Na) scintillator coupled to an Hamamatsu R3292 position-sensitive photomultiplier tube (PSPMT) as the position-sensitive detector. We have modified the normal resistor divider readout of the PSPMT to allow use of nearly the full 10 cm diameter active area of the PSPMT with a single scintillator crystal one centimeter thick. This is a significant performance improvement over that obtained with the standard readout technique where the linearity and position resolution start to degrade at radii as small as 3.5 cm with a crystal 0.75 crn thick. This represents a recovery of over 60% of the PSPMT active area. The performance increase allows the construction of an imager with a field of view 20 resolution elements in diameter with useful quantum efficiency from 60-700 keV. In this paper we describe the readout technique, its implementation in a coded aperture imager and the performance of that imager.

  18. Fast-neutron and gamma-ray imaging with a capillary liquid xenon converter coupled to a gaseous photomultiplier

    NASA Astrophysics Data System (ADS)

    Israelashvili, I.; Coimbra, A. E. C.; Vartsky, D.; Arazi, L.; Shchemelinin, S.; Caspi, E. N.; Breskin, A.

    2017-09-01

    Gamma-ray and fast-neutron imaging was performed with a novel liquid xenon (LXe) scintillation detector read out by a Gaseous Photomultiplier (GPM). The 100 mm diameter detector prototype comprised a capillary-filled LXe converter/scintillator, coupled to a triple-THGEM imaging-GPM, with its first electrode coated by a CsI UV-photocathode, operated in Ne/5%CH4 at cryogenic temperatures. Radiation localization in 2D was derived from scintillation-induced photoelectron avalanches, measured on the GPM's segmented anode. The localization properties of 60Co gamma-rays and a mixed fast-neutron/gamma-ray field from an AmBe neutron source were derived from irradiation of a Pb edge absorber. Spatial resolutions of 12± 2 mm and 10± 2 mm (FWHM) were reached with 60Co and AmBe sources, respectively. The experimental results are in good agreement with GEANT4 simulations. The calculated ultimate expected resolutions for our application-relevant 4.4 and 15.1 MeV gamma-rays and 1–15 MeV neutrons are 2–4 mm and ~ 2 mm (FWHM), respectively. These results indicate the potential applicability of the new detector concept to Fast-Neutron Resonance Radiography (FNRR) and Dual-Discrete-Energy Gamma Radiography (DDEGR) of large objects.

  19. A novel Compton camera design featuring a rear-panel shield for substantial noise reduction in gamma-ray images

    NASA Astrophysics Data System (ADS)

    Nishiyama, T.; Kataoka, J.; Kishimoto, A.; Fujita, T.; Iwamoto, Y.; Taya, T.; Ohsuka, S.; Nakamura, S.; Hirayanagi, M.; Sakurai, N.; Adachi, S.; Uchiyama, T.

    2014-12-01

    After the Japanese nuclear disaster in 2011, large amounts of radioactive isotopes were released and still remain a serious problem in Japan. Consequently, various gamma cameras are being developed to help identify radiation hotspots and ensure effective decontamination operation. The Compton camera utilizes the kinematics of Compton scattering to contract images without using a mechanical collimator, and features a wide field of view. For instance, we have developed a novel Compton camera that features a small size (13 × 14 × 15 cm3) and light weight (1.9 kg), but which also achieves high sensitivity thanks to Ce:GAGG scintillators optically coupled wiith MPPC arrays. By definition, in such a Compton camera, gamma rays are expected to scatter in the ``scatterer'' and then be fully absorbed in the ``absorber'' (in what is called a forward-scattered event). However, high energy gamma rays often interact with the detector in the opposite direction - initially scattered in the absorber and then absorbed in the scatterer - in what is called a ``back-scattered'' event. Any contamination of such back-scattered events is known to substantially degrade the quality of gamma-ray images, but determining the order of gamma-ray interaction based solely on energy deposits in the scatterer and absorber is quite difficult. For this reason, we propose a novel yet simple Compton camera design that includes a rear-panel shield (a few mm thick) consisting of W or Pb located just behind the scatterer. Since the energy of scattered gamma rays in back-scattered events is much lower than that in forward-scattered events, we can effectively discriminate and reduce back-scattered events to improve the signal-to-noise ratio in the images. This paper presents our detailed optimization of the rear-panel shield using Geant4 simulation, and describes a demonstration test using our Compton camera.

  20. Reflight of the Gamma-Ray Arcminute Telescope Imaging System (GRATIS) Payload

    NASA Technical Reports Server (NTRS)

    Hailey, Charles J.

    2000-01-01

    The Gamma-Ray Arcminute Telescope Imaging System (GRATIS) balloon payload was prepared for reflight. This involved repair of damage caused in the previous flight to structural members of the payload (the gondola support structure) as well as damage to some of the pointing system elements and electronics modules. This work was successfully completed. An extensive pre-calibration of the CsI(Na) imaging detectors was then done. The plan was to take several months to calibrate the 36 detectors and to compare the results with the post-calibration from the previous flight in Alice Springs Australia. During the course of the pre-calibrations it was noted that the light output of the crystals was severely degraded in more than half the detectors compared to the values recorded 1.5 years earlier. Subsequent investigation revealed that the light yield degradation was not unreasonable. The CsI crystals had in fact performed well past their rated life from hygroscopic contamination. The crystals had spent the majority of their life either in the desert or in the extremely low humidity conditions of Livermore California. where the GRATIS payload had been based prior to transfer to Columbia. The extreme summer humidity of New York simply exacerbated a degradation process that had been artificially delayed by dry conditions. Because such a large part of the detector array had been degraded we did not feel it was appropriate to refly the payload because the scientific performance would have been compromised.

  1. First On-Site True Gamma-Ray Imaging-Spectroscopy of Contamination near Fukushima Plant

    NASA Astrophysics Data System (ADS)

    Tomono, Dai; Mizumoto, Tetsuya; Takada, Atsushi; Komura, Shotaro; Matsuoka, Yoshihiro; Mizumura, Yoshitaka; Oda, Makoto; Tanimori, Toru

    2017-02-01

    We have developed an Electron Tracking Compton Camera (ETCC), which provides a well-defined Point Spread Function (PSF) by reconstructing a direction of each gamma as a point and realizes simultaneous measurement of brightness and spectrum of MeV gamma-rays for the first time. Here, we present the results of our on-site pilot gamma-imaging-spectroscopy with ETCC at three contaminated locations in the vicinity of the Fukushima Daiichi Nuclear Power Plants in Japan in 2014. The obtained distribution of brightness (or emissivity) with remote-sensing observations is unambiguously converted into the dose distribution. We confirm that the dose distribution is consistent with the one taken by conventional mapping measurements with a dosimeter physically placed at each grid point. Furthermore, its imaging spectroscopy, boosted by Compton-edge-free spectra, reveals complex radioactive features in a quantitative manner around each individual target point in the background-dominated environment. Notably, we successfully identify a “micro hot spot” of residual caesium contamination even in an already decontaminated area. These results show that the ETCC performs exactly as the geometrical optics predicts, demonstrates its versatility in the field radiation measurement, and reveals potentials for application in many fields, including the nuclear industry, medical field, and astronomy.

  2. First On-Site True Gamma-Ray Imaging-Spectroscopy of Contamination near Fukushima Plant

    PubMed Central

    Tomono, Dai; Mizumoto, Tetsuya; Takada, Atsushi; Komura, Shotaro; Matsuoka, Yoshihiro; Mizumura, Yoshitaka; Oda, Makoto; Tanimori, Toru

    2017-01-01

    We have developed an Electron Tracking Compton Camera (ETCC), which provides a well-defined Point Spread Function (PSF) by reconstructing a direction of each gamma as a point and realizes simultaneous measurement of brightness and spectrum of MeV gamma-rays for the first time. Here, we present the results of our on-site pilot gamma-imaging-spectroscopy with ETCC at three contaminated locations in the vicinity of the Fukushima Daiichi Nuclear Power Plants in Japan in 2014. The obtained distribution of brightness (or emissivity) with remote-sensing observations is unambiguously converted into the dose distribution. We confirm that the dose distribution is consistent with the one taken by conventional mapping measurements with a dosimeter physically placed at each grid point. Furthermore, its imaging spectroscopy, boosted by Compton-edge-free spectra, reveals complex radioactive features in a quantitative manner around each individual target point in the background-dominated environment. Notably, we successfully identify a “micro hot spot” of residual caesium contamination even in an already decontaminated area. These results show that the ETCC performs exactly as the geometrical optics predicts, demonstrates its versatility in the field radiation measurement, and reveals potentials for application in many fields, including the nuclear industry, medical field, and astronomy. PMID:28155883

  3. First On-Site True Gamma-Ray Imaging-Spectroscopy of Contamination near Fukushima Plant.

    PubMed

    Tomono, Dai; Mizumoto, Tetsuya; Takada, Atsushi; Komura, Shotaro; Matsuoka, Yoshihiro; Mizumura, Yoshitaka; Oda, Makoto; Tanimori, Toru

    2017-02-03

    We have developed an Electron Tracking Compton Camera (ETCC), which provides a well-defined Point Spread Function (PSF) by reconstructing a direction of each gamma as a point and realizes simultaneous measurement of brightness and spectrum of MeV gamma-rays for the first time. Here, we present the results of our on-site pilot gamma-imaging-spectroscopy with ETCC at three contaminated locations in the vicinity of the Fukushima Daiichi Nuclear Power Plants in Japan in 2014. The obtained distribution of brightness (or emissivity) with remote-sensing observations is unambiguously converted into the dose distribution. We confirm that the dose distribution is consistent with the one taken by conventional mapping measurements with a dosimeter physically placed at each grid point. Furthermore, its imaging spectroscopy, boosted by Compton-edge-free spectra, reveals complex radioactive features in a quantitative manner around each individual target point in the background-dominated environment. Notably, we successfully identify a "micro hot spot" of residual caesium contamination even in an already decontaminated area. These results show that the ETCC performs exactly as the geometrical optics predicts, demonstrates its versatility in the field radiation measurement, and reveals potentials for application in many fields, including the nuclear industry, medical field, and astronomy.

  4. A balloon-borne payload for imaging hard X-rays and gamma rays from solar flares

    NASA Technical Reports Server (NTRS)

    Crannell, Carol J.; Dennis, Brian R.; Orwig, Larry E.; Schmahl, Edward J.; Lang, Frederic L.; Starr, Richard; Norris, Jay P.; Greene, Michael E.; Hurford, Gordon J.; Johnson, W. N.

    1991-01-01

    Hard X-rays and gamma rays provide direct evidence of the roles of accelerated particles in solar flares. An approach that employs a spatial Fourier-transform technique for imaging the sources of these emissions is described, and the development of a balloon-borne imaging device based on this instrumental technique is presented. The detectors, together with the imaging optics, are sensitive to hard X-ray and gamma-ray emission in the energy-range from 20 to 700 keV. This payload, scheduled for its first flight in June 1992, will provide 11-arc second angular resolution and millisecond time resolution with a whole-sun field of view. For subsequent flights, the effective detector area can be increased by as much as a factor of four, and imaging optics with angular resolution as fine as 2 arcsec can be added to the existing gondola and metering structures.

  5. Gamma rays at airplane altitudes

    SciTech Connect

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

    1990-03-20

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

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

    SciTech Connect

    Ferreto, H. F. R. E-mail: ana-feitoza@yahoo.com.br; Oliveira, A. C. F. E-mail: ana-feitoza@yahoo.com.br; Parra, D. F. E-mail: ablugao@ipen.br; Lugão, A. B. E-mail: ablugao@ipen.br; Gaia, R.

    2014-05-15

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

  7. Application of scintillating fiber gamma-ray detectors for medical imaging

    NASA Astrophysics Data System (ADS)

    Chaney, Roy C.; Fenyves, Ervin J.; Nelson, Gregory S.; Anderson, Jon A.; Antich, Peter P.; Atac, Muzaffer

    1993-02-01

    The recently developed plastic scintillating fiber technology started the development of a new generation of high spatial and time resolution gamma ray detectors for medical imaging, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT). A scintillating fiber PET module consisting of two 5 X 5 X 2.5 cm(superscript 3) detector stacks made of parallel 1.0 mm diameter fiber, separated by 20 cm, each viewed by a Hamamatsu R2486 position sensitive photomultiplier was developed and tested. The time resolution of the coincidence system is 10 nsec. The spatial resolution and efficiency of this module turned out to be 2.3 mm (FWHM) and 2.0%, respectively, and independent of the location of the (superscript 22)Na testing source inside a sphere of 2 cm radius around the center of the two fiber stacks. The effect of gammas scattered in a 15 cm diameter water filled glass cylinder into which the (superscript 22)Na was immersed did not change the spatial resolution of the system.

  8. Brief history of ground-based very high energy gamma-ray astrophysics with atmospheric air Cherenkov telescopes

    NASA Astrophysics Data System (ADS)

    Mirzoyan, Razmik

    2014-01-01

    The discovery of the Crab Nebula as the first source of TeV gamma rays in 1989, using the technique of ground-based imaging air Cherenkov telescope, has marked the birthday of observational gamma astronomy in very high energy range. The team led by Trevor Weekes, after twenty years of trial and error, success and misfortune, step-by-step improvements in both the technique and understanding of gamma shower discrimination methods, used the 10 m diameter telescope on Mount Hopkins in Arizona, and succeeded measuring a 9σ signal from the direction of Crab Nebula. As of today over 160 sources of gamma rays of very different types, of both galactic and extra-galactic origin, have been discovered due to this technique. This is a really fast evolving branch in science, rapidly improving our understanding of the most violent and energetic sources and processes in the sky. The study of these sources provides clues to many basic questions in astrophysics, astro-particle physics, physics of cosmic rays and cosmology. Today's telescopes, despite the young age of the technique, offer a solid performance. The technique is still maturing, leading to the next generation large instrument. This article is devoted to outlining the milestones in a long history that step-by-step have made this technique emerge and have brought about today's successful source hunting.

  9. A Search for Early Optical Emission at Gamma-Ray Burst Locations by the Solar Mass Ejection Imager (SMEI)

    NASA Technical Reports Server (NTRS)

    Band, David L.; Buffington, Andrew; Jackson, Bernard V.; Hick, P. Paul; Smith, Aaron C.

    2005-01-01

    The Solar Mass Ejection Imager (SMEI) views nearly every point on the sky once every 102 minutes and can detect point sources as faint as R approx. 10th magnitude. Therefore, SMEI can detect or provide upper limits for the optical afterglow from gamma-ray bursts in the tens of minutes after the burst when different shocked regions may emit optically. Here we provide upper limits for 58 bursts between 2003 February and 2005 April.

  10. Design of Dual-Road Transportable Portal Monitoring System for Visible Light and Gamma-Ray Imaging

    SciTech Connect

    Karnowski, Thomas Paul; Cunningham, Mark F; Goddard Jr, James Samuel; Cheriyadat, Anil M; Hornback, Donald Eric; Fabris, Lorenzo; Kerekes, Ryan A; Ziock, Klaus-Peter; Bradley, Eric Craig; Chesser, Joel B; Marchant, William

    2010-01-01

    The use of radiation sensors as portal monitors is increasing due to heightened concerns over the smuggling of fissile material. Transportable systems that can detect significant quantities of fissile material that might be present in vehicular traffic are of particular interest, especially if they can be rapidly deployed to different locations. To serve this application, we have constructed a rapid-deployment portal monitor that uses visible-light and gamma-ray imaging to allow simultaneous monitoring of multiple lanes of traffic from the side of a roadway. The system operation uses machine vision methods on the visible-light images to detect vehicles as they enter and exit the field of view and to measure their position in each frame. The visible-light and gamma-ray cameras are synchronized which allows the gamma-ray imager to harvest gamma-ray data specific to each vehicle, integrating its radiation signature for the entire time that it is in the field of view. Thus our system creates vehicle-specific radiation signatures and avoids source confusion problems that plague non-imaging approaches to the same problem. Our current prototype instrument was designed for measurement of upto five lanes of freeway traffic with a pair of instruments, one on either side of the roadway. Stereoscopic cameras are used with a third alignment camera for motion compensation and are mounted on a 50 deployable mast. In this paper we discuss the design considerations for the machine-vision system, the algorithms used for vehicle detection and position estimates, and the overall architecture of the system. We also discuss system calibration for rapid deployment. We conclude with notes on preliminary performance and deployment.

  11. Upcoming long-duration balloon flight of the Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS)

    NASA Astrophysics Data System (ADS)

    Shih, Albert Y.; Saint Hilaire, Pascal; Duncan, Nicole A.; Hurford, Gordon J.; Bain, Hazel; Maruca, Bennett A.; Boggs, Steven E.; Zoglauer, Andreas C.; Smith, David; Tajima, Hiroyasu; Amman, Mark S.

    2015-04-01

    We present the status of preparations for the upcoming Antarctic long-duration balloon flight of the balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument in December 2015. GRIPS will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from ~20 keV to >~10 MeV. GRIPS will address questions raised by recent solar flare observations regarding particle acceleration and energy release, such as: What causes the spatial separation between energetic electrons producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the relativistic electrons, and why can they dominate in the corona? How do the compositions of accelerated and ambient material vary with space and time, and why? The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded with an energy resolution of a few keV FWHM and a spatial resolution of <0.1 mm3. Imaging is accomplished by a single multi-pitch rotating modulator (MPRM), a 2.5-cm thick tungsten-alloy slit/slat grid with pitches that range quasi-continuously from 1 to 13 mm. The MPRM is situated 8 meters from the spectrometer to provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), sufficient to separate 2.2 MeV footpoint sources for almost all flares. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e., as an active scatterer), with an estimated minimum detectable polarization of a few percent at 150-650 keV in an X-class flare.

  12. Design of dual-road transportable portal monitoring system for visible light and gamma-ray imaging

    NASA Astrophysics Data System (ADS)

    Karnowski, Thomas P.; Cunningham, Mark F.; Goddard, James S.; Cheriyadat, Anil M.; Hornback, Donald E.; Fabris, Lorenzo; Kerekes, Ryan A.; Ziock, Klaus-Peter; Bradley, E. Craig; Chesser, J.; Marchant, W.

    2010-04-01

    The use of radiation sensors as portal monitors is increasing due to heightened concerns over the smuggling of fissile material. Transportable systems that can detect significant quantities of fissile material that might be present in vehicular traffic are of particular interest, especially if they can be rapidly deployed to different locations. To serve this application, we have constructed a rapid-deployment portal monitor that uses visible-light and gamma-ray imaging to allow simultaneous monitoring of multiple lanes of traffic from the side of a roadway. The system operation uses machine vision methods on the visible-light images to detect vehicles as they enter and exit the field of view and to measure their position in each frame. The visible-light and gamma-ray cameras are synchronized which allows the gamma-ray imager to harvest gamma-ray data specific to each vehicle, integrating its radiation signature for the entire time that it is in the field of view. Thus our system creates vehicle-specific radiation signatures and avoids source confusion problems that plague non-imaging approaches to the same problem. Our current prototype instrument was designed for measurement of upto five lanes of freeway traffic with a pair of instruments, one on either side of the roadway. Stereoscopic cameras are used with a third "alignment" camera for motion compensation and are mounted on a 50' deployable mast. In this paper we discuss the design considerations for the machine-vision system, the algorithms used for vehicle detection and position estimates, and the overall architecture of the system. We also discuss system calibration for rapid deployment. We conclude with notes on preliminary performance and deployment.

  13. X-ray and gamma ray astronomy detectors

    NASA Technical Reports Server (NTRS)

    Decher, Rudolf; Ramsey, Brian D.; Austin, Robert

    1994-01-01

    X-ray and gamma ray astronomy was made possible by the advent of space flight. Discovery and early observations of celestial x-rays and gamma rays, dating back almost 40 years, were first done with high altitude rockets, followed by Earth-orbiting satellites> once it became possible to carry detectors above the Earth's atmosphere, a new view of the universe in the high-energy part of the electromagnetic spectrum evolved. Many of the detector concepts used for x-ray and gamma ray astronomy were derived from radiation measuring instruments used in atomic physics, nuclear physics, and other fields. However, these instruments, when used in x-ray and gamma ray astronomy, have to meet unique and demanding requirements related to their operation in space and the need to detect and measure extremely weak radiation fluxes from celestial x-ray and gamma ray sources. Their design for x-ray and gamma ray astronomy has, therefore, become a rather specialized and rapidly advancing field in which improved sensitivity, higher energy and spatial resolution, wider spectral coverage, and enhanced imaging capabilities are all sought. This text is intended as an introduction to x-ray and gamma ray astronomy instruments. It provides an overview of detector design and technology and is aimed at scientists, engineers, and technical personnel and managers associated with this field. The discussion is limited to basic principles and design concepts and provides examples of applications in past, present, and future space flight missions.

  14. Terrestrial Gamma-Ray Flashes (TGFs)

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2010-01-01

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

  15. Design and imaging performance of achromatic diffractive-refractive x-ray and gamma-ray Fresnel lenses.

    PubMed

    Skinner, Gerald K

    2004-09-01

    Achromatic combinations of a diffractive phase Fresnel lens and a refractive correcting element have been proposed for x-ray and gamma-ray astronomy and for microlithography, but considerations of absorption often dictate that the refractive component be given a stepped profile, resulting in a double Fresnel lens. The imaging performance of corrected Fresnel lenses, with and without stepping, is investigated, and the trade-off between resolution and useful bandwidth in different circumstances is discussed. Provided that the focal ratio is large, correction lenses made from low atomic number materials can be used with x rays in the range of approximately 10-100 keV without stepping. The use of stepping extends the possibility of correction to higher-aperture systems, to energies as low as a few kilo electron volts, and to gamma rays of mega electron volt energy.

  16. Performance evaluation of a multiple-scattering Compton imager for distribution of prompt gamma-rays in proton therapy

    NASA Astrophysics Data System (ADS)

    Lee, Taewoong; Lee, Hyounggun; Kim, Younghak; Lee, Wonho

    2017-01-01

    The purpose of this study is to compare and evaluate the performance of a multiple-scattering Compton imager (MSCI) to measure prompt gamma-rays emitted during proton therapy. Because prompt gamma-rays are generated simultaneously during the proton beam delivery, the falloff position of the Bragg peak of the proton beam can be determined from the distribution of prompt gamma-rays. The detection system was designed using three CdZnTe detector layers that can track radiation of unknown energy on the basis of effective Compton scattering events. The simple back-projection, filtered back-projection, and maximum likelihood expectation maximization (MLEM) algorithms were applied for the reconstructed Compton images. The falloff positions of the Bragg peaks determined from individual MSCIs were compared with the theoretical values calculated using the Monte Carlo N-Particle eXtended code. Moreover, the performance of the MSCI was compared with that of a previously developed system based on a slit collimator gamma camera. In summary, the MSCI with the MLEM reconstruction algorithm was better than the other reconstruction methods in terms of the falloff position of the Bragg peak, the angular resolution, and the signal-to-noise ratio.

  17. Wide Band X-Ray Imager (WXI) And Soft Gamma-Ray Detector (SGD) for the NeXT Mission

    SciTech Connect

    Takahashi, T.

    2005-04-22

    The NeXT mission has been proposed to study high-energy non-thermal phenomena in the universe. The high-energy response of the super mirror will enable us to perform the first sensitive imaging observations up to 80 keV. The focal plane detector, which combines a fully depleted X-ray CCD and a pixellated CdTe detector, will provide spectra and images in the wide energy range from 0.5 keV to 80 keV. In the soft gamma-ray band upto {approx} 1 MeV, a narrow field-of-view Compton gamma-ray telescope utilizing several tens of layers of thin Si or CdTe detector will provide precise spectra with much higher sensitivity than present instruments. The continuum sensitivity will reach several x 10{sup -8} photons/s/keV/cm{sup 2} in the hard X-ray region and a few x 10{sup -7} photons/s/keV/cm{sup 2} in the soft {gamma}-ray region.

  18. New Constraints on Simultaneous Optical Emission from Gamma-Ray Bursts Measured by the Livermore Optical Transient Imaging System Experiment

    NASA Technical Reports Server (NTRS)

    Park, H. S. (Editor); Williams, G. G. (Editor); Ables, E. (Editor); Band, D. L. (Editor); Barthelmy, S. D. (Editor); Bionta, R. M. (Editor); Butterworth, P. S. (Editor); Cline, T. S. (Editor); Ferguson, D. H. (Editor); Fishman, G. J. (Editor)

    1997-01-01

    LOTIS is a gamma-ray burst optical counterpart search experiment located near Lawrence Livermore National Laboratory in California. Since operations began in 1996 October, LOTIS has responded to five triggers as of 1997 July 30, which occurred during good weather conditions. GR-B 970223 (BATSE trigger 6100) was an exceptionally strong burst, lasting approx. 30 s with a peak at approx. 8 s. LOTIS began imaging the error box approx. 11 s after the burst began and achieved simultaneous optical coverage of 100% of the region enclosed by the BATSE 3 sigma error circle and the interplanetary network annulus. No optical transients were observed brighter than the m{}_{V} approx.11 completeness limit of the resulting images, providing a new upper limit on the ratio of simultaneous optical to gamma-ray fluence of R-{L) less than 1.1 x 10 logical and {-4} and on the ratio of simultaneous optical (at 700 mn) to gamma-ray (at 100 keV) flux density of R-{F} less than 305 for a B-type spectrum and R-{F} less than 475 for an M-type spectrum.

  19. Development of the Three-Dimensional Track Imager (3-DTI) for High Sensitivity Medium-Energy Gamma-Ray Polarimeter

    NASA Astrophysics Data System (ADS)

    Hunter, Stanley

    We propose to complete development of the Three-Dimensional Track Imager (3-DTI) detector. The 3-DTI development is motivated by the diverse science goals of the Advance Energetic Pair Telescope (AdEPT); a future instrument for medium-energy gamma-ray polarization. AdEPT will provide exceptional angular resolution approaching the kinematic limit for nuclear pair production ( 2 deg at 30 MeV) over the energy range from 5 MeV to >200 MeV and will be the first instrument in this energy range to be sensitive to gamma-ray polarization. The AdEPT performance can only be achieved with a low density pair-production medium coupled with high resolution electron-positron tracking and energy determination, i.e. accurate measurement of the electron-positron recoil momenta. The 3-DTI detector combines a gas time projection chamber (TPC) with a 400 um pitch two-dimensional Micro-Well Detector (MWD) to provide the high resolution three-dimensional charged particle tracking needed for AdEPT. The proposed work will address the need to tile smaller 12-25 cm2 MWDs together to achieve larger, 50 x 50 cm2 and 1 m2 areas, explore additive manufacturing of MWDs, and measure the long-term MWD performance. We will build a 50 x 50 x 100 cm3 active volume AdEPT prototype that will include zero dead-time streaming mode readout and charge integrating front-end electronics. Software will be developed for this prototype to discriminate between gamma-ray interactions and charged particles, determine the electron energies from multiple scattering and energy loss, and determine the incident direction and polarization of medium-energy gamma-rays.

  20. Gamma ray generator

    SciTech Connect

    Firestone, Richard B; Reijonen, Jani

    2014-05-27

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

  1. Survey of candidate gamma-ray sources at TeV energies using a high-resolution Cerenkov imaging system - 1988-1991

    NASA Technical Reports Server (NTRS)

    Reynolds, P. T.; Akerlof, C. W.; Cawley, M. F.; Chantell, M.; Fegan, D. J.; Hillas, A. M.; Lamb, R. C.; Lang, M. J.; Lawrence, M. A.; Lewis, D. A.

    1993-01-01

    The steady TeV gamma-ray emission from the Crab Nebula has been used to optimize the sensitivity of the Whipple Observatory atmospheric Cerenkov imaging telescope. Using this method, which is of order 20 times more sensitive than the standard method using a simple non-imaging detector, it is possible to detect the Crab Nebula at a significance level in excess of 6 standard deviations (6 sigma) in under 1 hr on source (with a corresponding time observing a background comparison region); a source one-tenth the strength of the Crab Nebula can be detected at the 4 sigma level after 40 hr on the source (and 40 hr on a background region). A variety of sources have been monitored using this technique over the period 1988-1991, but none were detected apart from the Crab Nebula. Upper limits are presented which in many instances are a factor of 10 below the flux of the Crab Nebula. These upper limits assume steady emission from the source and cannot rule out sporadic gamma-ray emission with short duty cycles.

  2. SONGS - A high resolution imaging gamma-ray spectrometer for the Space Station

    NASA Technical Reports Server (NTRS)

    Nakano, G. H.; Chase, L. F.; Kilner, J. R.; Sandie, W. G.; Fishman, G. J.; Paciesas, W. S.

    1989-01-01

    The overall design and the instrumental features of the Space-Station Observer for Nuclear Gamma-ray Spectroscopy (SONGS) instrument are described. SONGS comprises an array of 19 two-segment n-type Ge detectors, which have the capability of determining the interaction site in either the upper or the lower segment or in both segments. The detectors provide high energy resolution of 1 keV at 100 keV and of 2 keV at 1 MeV. The close-packed Ge sensor array provides a natural sensitivity for the measurement of gamma ray polarization in the 100 keV to 1 MeV energy range, making it possible to obtain information on the structure of the magnetosphere of neutron stars and of the accretion disk of black holes.

  3. Active Detection and Imaging of Nuclear Materials with High-Brightness Gamma Rays

    SciTech Connect

    Barty, C J; Gibson, D J; Albert, F; Anderson, S G; Anderson, G G; Betts, S M; Berry, R D; Fisher, S E; Hagmann, C A; Johnson, M S; Messerly, M J; Phan, H H; Semenov, V A; Shverdin, M Y; Tremaine, A M; Hartemann, F V; Siders, C W; McNabb, D P

    2009-02-26

    A Compton scattering {gamma}-ray source, capable of producing photons with energies ranging from 0.1 MeV to 0.9 MeV has been commissioned and characterized, and then used to perform nuclear resonance fluorescence (NRF) experiments. The performances of the two laser systems (one for electron production, one for scattering), the electron photoinjector, and the linear accelerator are also detailed, and {gamma}-ray results are presented. The key source parameters are the size (0.01 mm{sup 2}), horizontal and vertical divergence (6 x 10 mrad{sup 2}), duration (10 ps), spectrum and intensity (10{sup 5} photons/shot). These parameters are summarized by the peak brightness, 1.5 x 10{sup 15} photons/mm{sup 2}/mrad{sup 2}/s/0.1% bandwidth, measured at 478 keV. Additional measurements of the flux as a function of the timing difference between the drive laser pulse and the relativistic photo-electron bunch, {gamma}-ray beam profile, and background evaluations are presented. These results are systematically compared to theoretical models and computer simulations. NRF measurements performed on {sup 7}Li in LiH demonstrate the potential of Compton scattering photon sources to accurately detect isotopes in situ.

  4. Mathematical Investigation of Gamma Ray and Neutron Absorption Grid Patterns for Homeland Defense Related Fourier Imaging Systems

    NASA Technical Reports Server (NTRS)

    Boccio, Dona

    2003-01-01

    Terrorist suitcase nuclear devices typically using converted Soviet tactical nuclear warheads contain several kilograms of plutonium. This quantity of plutonium emits a significant number of gamma rays and neutrons as it undergoes radioactive decay. These gamma rays and neutrons normally penetrate ordinary matter to a significant distance. Unfortunately this penetrating quality of the radiation makes imaging with classical optics impractical. However, this radiation signature emitted by the nuclear source may be sufficient to be imaged from low-flying aerial platforms carrying Fourier imaging systems. The Fourier imaging system uses a pair of co-aligned absorption grids to measure a selected range of spatial frequencies from an object. These grids typically measure the spatial frequency in only one direction at a time. A grid pair that looks in all directions simultaneously would be an improvement over existing technology. A number of grid pairs governed by various parameters were investigated to solve this problem. By examining numerous configurations, it became apparent that an appropriate spiral pattern could be made to work. A set of equations was found to describe a grid pattern that produces straight fringes. Straight fringes represent a Fourier transform of a point source at infinity. An inverse Fourier transform of this fringe pattern would provide an accurate image (location and intensity) of a point source.

  5. Development of the imaging system of the balloon-borne gamma-ray telescope Máscara Codificada (MASCO)

    NASA Astrophysics Data System (ADS)

    Braga, Joa~O.; D'Amico, Flavio; Villela, Thyrso; Mejía, Jorge; Fonseca, Raphael A.; Rinke, Elisete

    2002-10-01

    We report laboratory imaging results of a balloon-borne gamma-ray imaging telescope, Máscara Codificada (Portuguese for ``coded mask,'') designed to obtain high angular resolution (~14 arcmin) images of the sky in the 50 keV-1.8 MeV energy range. The instrument incorporates a coded mask with an aperture pattern based on a 19×19-element modified uniformly redundant array (MURA). This pattern belongs to a subclass of MURAs that are almost completely antisymmetrical for 90° rotations with respect to the lower-right corner of the central element, which allows the implementation of an antimask by a single rotation of the whole mask by 90°. The symmetry properties of the MURAs are discussed. The algorithm for determining the position of the gamma-ray interactions on the instrument's main detector is described and the results of laboratory tests of the imaging system are presented. The mask-antimask subtraction, applied after a flat-fielding procedure, produced a 60% increase in the signal-to-noise ratio of a strong (~100σ) point source (662 keV photons coming from a 137Cs radioactive source) image by eliminating systematic distortions in the instrumental background measured over the detector plane.

  6. Three-dimensional and tomographic imaging device for X-ray and gamma-ray emitting objects

    NASA Technical Reports Server (NTRS)

    Yin, L. I. (Inventor)

    1985-01-01

    An instrument for obtaining quantitative, three-dimensional and tomographic information relating to X-ray and gamma-ray emitting objects and for the orthoscopic viewing of such objects includes a multiple-pinhole aperture plate held spaced from an X-ray or gamma-ray to visible-light converter which is coupled to a visible-light image intensifier. The spacing between the aperture plate and the converter is chosen such that the mini-images of an emitting object formed by the pinholes do not substantially overlap as they impinge on the converter. The output of the image intensifier is digitized by a digitizing camera in terms of position and intensity and fed into a digital computer. The computer may output quantitative information relating to the emitting object directly, such as that relating to tomograms, or provide information in analogue form when coupled with a suitable viewing device to give an orthoscopic, three-dimensional image of the object.

  7. Physics and astrophysics with gamma-ray telescopes

    NASA Astrophysics Data System (ADS)

    Vandenbroucke, J.; Fermi LAT Collaboration

    2012-08-01

    In the past few years gamma-ray astronomy has entered a golden age. A modern suite of telescopes is now scanning the sky over both hemispheres and over six orders of magnitude in energy. At ˜TeV energies, only a handful of sources were known a decade ago, but the current generation of ground-based imaging atmospheric Cherenkov telescopes (H.E.S.S., MAGIC, and VERITAS) has increased this number to nearly one hundred. With a large field of view and duty cycle, the Tibet and Milagro air shower detectors have demonstrated the promise of the direct particle detection technique for TeV gamma rays. At ˜GeV energies, the Fermi Gamma-ray Space Telescope has increased the number of known sources by nearly an order of magnitude in its first year of operation. New classes of sources that were previously theorized to be gamma-ray emitters have now been confirmed observationally. Moreover, there have been surprise discoveries of GeV gamma-ray emission from source classes for which no theory predicted it was possible. In addition to elucidating the processes of high-energy astrophysics, gamma-ray telescopes are making essential contributions to fundamental physics topics including quantum gravity, gravitational waves, and dark matter. I summarize the current census of astrophysical gamma-ray sources, highlight some recent discoveries relevant to fundamental physics, and describe the synergetic connections between gamma-ray and neutrino astronomy. This is a brief overview intended in particular for particle physicists and neutrino astronomers, based on a presentation at the Neutrino 2010 conference in Athens, Greece. I focus in particular on results from Fermi (which was launched soon after Neutrino 2008), and conclude with a description of the next generation of instruments, namely HAWC and the Cherenkov Telescope Array.

  8. Hybrid Pixel-Waveform (HPWF) Enabled CdTe Detectors for Small Animal Gamma-Ray Imaging Applications

    PubMed Central

    Groll, A.; Kim, K.; Bhatia, H.; Zhang, J. C.; Wang, J. H.; Shen, Z. M.; Cai, L.; Dutta, J.; Li, Q.; Meng, L. J.

    2016-01-01

    This paper presents the design and preliminary evaluation of small-pixel CdTe gamma ray detectors equipped with a hybrid pixel-waveform (HPWF) readout system for gamma ray imaging applications with additional discussion on CZT due to its similarity. The HPWF readout system utilizes a pixelated anode readout circuitry which is designed to only provide the pixel address. This readout circuitry works in coincidence with a high-speed digitizer to sample the cathode waveform which provides the energy, timing, and depth-of-interaction (DOI) information. This work focuses on the developed and experimentally evaluated prototype HPWF-CdTe detectors with a custom CMOS pixel-ASIC to readout small anode pixels of 350 μm in size, and a discrete waveform sampling circuitry to digitize the signal waveform induced on the large cathode. The intrinsic timing, energy, and spatial resolution were experimentally evaluated in this paper in conjunction with methods for depth of interaction (DOI) partitioning of the CdTe crystal. While the experimental studies discussed in this paper are primarily for evaluating HPWF detectors for small animal PET imaging, these detectors could find their applications for ultrahigh-resolution SPECT and other imaging modalities. PMID:28516169

  9. Imaging characterization of a new gamma ray detector based on CRY019 scintillation crystal for PET and SPECT applications

    NASA Astrophysics Data System (ADS)

    Polito, C.; Pani, R.; Trigila, C.; Cinti, M. N.; Fabbri, A.; Frantellizzi, V.; De Vincentis, G.; Pellegrini, R.; Pani, R.

    2017-02-01

    In the last 40 years, in the field of Molecular Medicine imaging there has been a huge growth in the employment and in the improvement of detectors for PET and SPECT applications in order to reach accurate diagnosis of the diseases. The most important feature required to these detectors is an high quality of images that is usually obtained benefitting from the development of a wide number of new scintillation crystals with high imaging performances. In this contest, features like high detection efficiency, short decay time, great spectral match with photodetectors, absence of afterglow and low costs are surely attractive. However, there are other factors playing an important role in the realization of high quality images such as energy and spatial resolutions, position linearity and contrast resolution. With the aim to realize an high performace gamma ray detector for PET and SPECT applications, this work is focused on the evaluation of the imaging characteristics of a recently developed scintillation crystal, CRY019.

  10. Design of a modular signal processing board (MSPB) for gamma-ray imaging applications

    NASA Astrophysics Data System (ADS)

    Bieberle, A.; Berger, R.; Yadav, R.; Schleicher, E.; Hampel, U.

    2012-01-01

    In this paper a new modular signal processing board (MSPB) for high-resolution gamma-ray computed tomography (GCT) is presented. The MSPB is optimised for parallel signal processing of eight detector channels operating in pulse counting mode. Signal processing stages comprise of variable gain amplifiers, pulse height discrimination stages, 13-bit counters with corresponding latches as well as logic circuitry for coordinated data transfer with a multitude of MSPBs. The digital signal processing units are realised in commercially available complex programmable logic devices (CPLD). Each MSPB is addressable by an 8-bit DIP-switch, which allows the use of up to 256 modules or 2048 detector pixels within one detector system. The geometry of the MSPB allows a multiple and seamless detector module arrangement, which eases the adaptation of a given gamma-ray detector system to specific industrial and laboratory applications. The choice of the electronic devices and the thermal design was optimised for low power consumption in order to minimise internal heat production, which would affect the characteristics of the detector's intrinsic gain strongly. Thermal measurements have been executed to prove the functionality of the thermal design.

  11. The imaging of extra-galactic low-energy gamma-ray sources prospects, techniques, and instrumentation. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Finger, Mark Harold

    1987-01-01

    Improved understanding of the nature of active galaxies will require detailed observations of 10 to 20 sources, while understanding of their gamma ray luminosity function and its evolution will require the detection of approximately 100 sources. Instruments capable of detecting 100 active galaxies at low-energy, gamma ray energies are achievable. The angular resolution of an instrument, as well as its sensitivity, can limit the number of sources it can observe. An investigation of the angular resolution requirements for future low-energy gamma ray instruments is presented. It was found that the strictest requirements arise not from the need to resolve detectable sources, but from the need to control the level of direction-to-direction fluctuations in the diffuse background level. It was concluded that gamma-ray instruments capable of detecting 100 active galaxies must have sub-degree angular resolution. The use of the coded aperture imaging technique is proposed as a method of achieving accurate control of systematic errors and fine angular resolution without unduly increasing the time needed to conduct full sky surveys. An analysis of coded aperture imaging is presented for instruments that employ masks based on hexagonal uniformly redundant arrays. An instrument, the gamma-ray imaging payload, was built that employs these imaging techniques. The design and testing of the instrument is described in detail. Preliminary results from a balloon flight of the instruments are shown, demonstrating its imaging performance.

  12. The History of Ground-Based Very High Energy Gamma-Ray Astrophysics with the Atmospheric Air Cherenkov Telescope Technique

    NASA Astrophysics Data System (ADS)

    Mirzoyan, Razmik

    2013-06-01

    In the recent two decades the ground-based technique of imaging atmosphericescopes has established itself as a powerful new discipline in science. As of today some ˜ 150 sources of gamma rays of very different types, of both galactic and extragalactic origin, have been discovered due to this technique. The study of these sources is providing clues to many basic questions in astrophysics, astro-particle physics, physics of cosmic rays and cosmology. The current generation of telescopes, despite the young age of the technique, offers a solid performance. The technique is still maturing, leading to the next generation large instrument known under the name Cherenkov Telescope Array. The latter's sensitivity will be an order of magnitude higher than that of the currently best instruments VERITAS, H.E.S.S. and MAGIC. This article is devoted to outlining the milestones in a long history that step-by-step have given shape to this technique and have brought about today's successful source marathon.

  13. A Mechanically-Cooled, Highly-Portable, HPGe-Based, Coded-Aperture Gamma-Ray Imager

    SciTech Connect

    Ziock, Klaus-Peter; Boehnen, Chris Bensing; Hayward, Jason P; Raffo-Caiado, Ana Claudia

    2010-01-01

    Coded-aperture gamma-ray imaging is a mature technology that is capable of providing accurate and quantitative images of nuclear materials. Although it is potentially of high value to the safeguards and arms-control communities, it has yet to be fully embraced by those communities. One reason for this is the limited choice, high-cost, and low efficiency of commercial instruments; while instruments made by research organizations are frequently large and / or unsuitable for field work. In this paper we present the results of a project that mates the coded-aperture imaging approach with the latest in commercially-available, position-sensitive, High Purity Germanium (HPGe) detec-tors. The instrument replaces a laboratory prototype that, was unsuitable for other than demonstra-tions. The original instrument, and the cart on which it is mounted to provide mobility and pointing capabilities, has a footprint of ~ 2/3 m x 2 m, weighs ~ 100 Kg, and requires cryogen refills every few days. In contrast, the new instrument is tripod mounted, weighs of order 25 Kg, operates with a laptop computer, and is mechanically cooled. The instrument is being used in a program that is ex-ploring the use of combined radiation and laser scanner imaging. The former provides information on the presence, location, and type of nuclear materials while the latter provides design verification information. To align the gamma-ray images with the laser scanner data, the Ge imager is fitted and aligned to a visible-light stereo imaging unit. This unit generates a locus of 3D points that can be matched to the precise laser scanner data. With this approach, the two instruments can be used completely independently at a facility, and yet the data can be accurately overlaid based on the very structures that are being measured.

  14. An Intensified EMCCD Camera for Low Energy Gamma Ray Imaging Applications

    PubMed Central

    Meng, L. J.

    2016-01-01

    This paper presents the design and feasibility study of a very-high resolution gamma camera for detecting 27–35 keV X and gamma rays emitted by I-125 labelled radiotracers. This detector consists of a newly developed Electron-multiplying CCD (EMCCD) sensor and a de-magnifier tube coupled to a thin layer of scintillator. A prototype detector was developed and experimentally evaluated. This detector has a detection area of ~ 5 cm2. It provided an intrinsic spatial resolution of < 60 µm FWHM and a high signal-to-noise ratio for detecting the 27–35 keV photons, which ensures an excellent counting efficiency. This detector will be used as the key component for a single photon emission microscope (SPEM) system that is under development.

  15. The Compton Gamma Ray Observatory

    NASA Astrophysics Data System (ADS)

    Gehrels, N.; Chipman, E.; Kniffen, D. A.

    1993-01-01

    The Arthur Holly Compton Gamma Ray Observatory (Compton) was launched by the Space Shuttle Atlantis on 5 April 1991. The spacecraft and instruments are in good health and returning exciting results. The mission provides nearly six orders of magnitude in spectral coverage, from 30 keV to 30 GeV, with sensitivity over the entire range an order of magnitude better than that of previous observations. The 16,000 kilogram observatory contains four instruments on a stabilized platform. The mission began normal operations on 16 May 1991 and is now over half-way through a full-sky survey. The mission duration is expected to be from six to ten years. A Science Support Center has been established at Goddard Space Flight Center for the purpose of supporting a vigorous Guest Investigator Program. New scientific results to date include: (1) the establishment of the isotropy, combined with spatial inhomogeneity, of the distribution of gamma-ray bursts in the sky; (2) the discovery of intense high energy (100 MeV) gamma-ray emission from 3C 279 and other quasars and BL Lac objects, making these the most distant and luminous gamma-ray sources ever detected; (3) one of the first images of a gamma-ray burst; (4) the observation of intense nuclear and position-annihilation gamma-ray lines and neutrons from several large solar flares; and (5) the detection of a third gamma-ray pulsar, plus several other transient and pulsing hard X-ray sources.

  16. Multiwavelength observations of a VHE gamma-ray flare from PKS 1510-089 in 2015

    NASA Astrophysics Data System (ADS)

    Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Arcaro, C.; Babić, A.; Banerjee, B.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Bednarek, W.; Bernardini, E.; Berti, A.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carosi, R.; Carosi, A.; Chatterjee, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Cumani, P.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; de Oña Wilhelmi, E.; Di Pierro, F.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher Glawion, D.; Elsaesser, D.; Engelkemeier, M.; Fallah Ramazani, V.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Gaug, M.; Giammaria, P.; Godinović, N.; Gora, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Hassan, T.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Hughes, G.; Ishio, K.; Konno, Y.; Kubo, H.; Kushida, J.; Kuveždić, D.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; Majumdar, P.; Makariev, M.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Mirzoyan, R.; Moralejo, A.; Moretti, E.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nilsson, K.; Nishijima, K.; Noda, K.; Nogués, L.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Pedaletti, G.; Peresano, M.; Perri, L.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Garcia, J. R.; Reichardt, I.; Rhode, W.; Ribó, M.; Rico, J.; Saito, T.; Satalecka, K.; Schroeder, S.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Šnidarić, I.; Sobczynska, D.; Stamerra, A.; Strzys, M.; Surić, T.; Takalo, L.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Torres, D. F.; Torres-Albà, N.; Toyama, T.; Treves, A.; Vanzo, G.; Vazquez Acosta, M.; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zarić, D.; Desiante, R.; Becerra González, J.; D'Ammando, F.; Larsson, S.; Raiteri, C. M.; Reinthal, R.; Lähteenmäki, A.; Järvelä, E.; Tornikoski, M.; Ramakrishnan, V.; Jorstad, S. G.; Marscher, A. P.; Bala, V.; MacDonald, N. R.; Kaur, N.; Sameer; Baliyan, K.; Acosta-Pulido, J. A.; Lazaro, C.; Martí-nez-Lombilla, C.; Grinon-Marin, A. B.; Pastor Yabar, A.; Protasio, C.; Carnerero, M. I.; Jermak, H.; Steele, I. A.; Larionov, V. M.; Borman, G. A.; Grishina, T. S.

    2017-07-01

    Context. PKS 1510-089 is one of only a few flat spectrum radio quasars detected in the very-high-energy (VHE, > 100 GeV) gamma-ray band. Aims: We study the broadband spectral and temporal properties of the PKS 1510-089 emission during a high gamma-ray state. Methods: We performed VHE gamma-ray observations of PKS 1510-089 with the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes during a long, high gamma-ray state in May 2015. In order to perform broadband modeling of the source, we have also gathered contemporaneous multiwavelength data in radio, IR, optical photometry and polarization, UV, X-ray, and GeV gamma-ray ranges. We construct a broadband spectral energy distribution (SED) in two periods, selected according to VHE gamma-ray state. Results: PKS 1510-089 was detected by MAGIC during a few day-long observations performed in the middle of a long, high optical and gamma-ray state, showing for the first time a significant VHE gamma-ray variability. Similarly to the optical and gamma-ray high state of the source detected in 2012, it was accompanied by a rotation of the optical polarization angle and the emission of a new jet component observed in radio. However, owing to large uncertainty on the knot separation time, the association with the VHE gamma-ray emission cannot be firmly established. The spectral shape in the VHE band during the flare is similar to those obtained during previous measurements of the source. The observed flux variability sets constraints for the first time on the size of the region from which VHE gamma rays are emitted. We model the broadband SED in the framework of the external Compton scenario and discuss the possible emission site in view of multiwavelength data and alternative emission models.

  17. Solar flare gamma-ray and hard x ray imaging with the GRID-on-a-balloon

    NASA Technical Reports Server (NTRS)

    Orwig, Larry E.; Crannell, C. J.; Dennis, Brian R.; Starr, R.; Hurford, G. J.; Hudson, H. S.; Vanbeek, F.; Greene, M. E.; Johnson, W. N.; Norris, J. P.

    1989-01-01

    A primary scientific objective for solar flare research during the rapidly approaching maximum in solar activity is the imaging of gamma-ray and hard x ray sources of solar flare emissions. These goals will be pursued by the Gamma Ray Imaging Device (GRID) instrument, one of three instruments recently selected for NASA's Max '91 Solar Balloon Program. The GRID instrument is based on the technique of Fourier transform imaging and utilizes scanning modulation grid collimator optics to provide full-Sun imaging with 1.9-arcsecond resolution over the energy range from 20 to 700 keV at time resolutions from 0.1 to 2 s. The GRID telescope will employ 32 subcollimators, each composed of a matched pair of high-Z collimator grids separated by 5.2 meters and a phoswich scintillation spectrometer detector having no spatial resolution. The subcollimators and integrally-mounted fine aspect system are contained within a telescope canister which will be pointed to 0.1 degree accuracy and cyclically scanned to produce source modulation. The 32 subcollimators provide a uniform distribution of grid slit orientations and a logarithmic distribution of slit spacings corresponding to angular dimensions of 1.9 arcseconds to several arcminutes. The instrument is several orders of magnitude more sensitive than the HXIS instrument on the Solar Maximum Mission (SMM) and nearly 10 times more sensitive than any similar instrument scheduled to fly during the next solar maximum. The payload, designed for long-duration high-altitude balloon capability, is scheduled for its first science flight (8 to 14 days duration) from the Antarctic in January of 1992.

  18. The very-high-energy gamma-ray sky.

    PubMed

    Aharonian, Felix

    2007-01-05

    Over the past few years, very-high-energy gamma-ray astronomy has emerged as a truly observational discipline, with many detected sources representing different galactic and extragalactic source populations-supernova remnants, pulsar wind nebulae, giant molecular clouds, star formation regions, compact binary systems, and active galactic nuclei. It is expected that observations with the next generation of stereoscopic arrays of imaging atmospheric Cherenkov telescopes over a very broad energy range from 10(10) to 10(15) electron volts will dramatically increase the number of very-high-energy gamma-ray sources, thus having a huge impact on the development of astrophysics, cosmology, and particle astrophysics.

  19. Development of a detector based on Silicon Drift Detectors for gamma-ray spectroscopy and imaging applications

    NASA Astrophysics Data System (ADS)

    Busca, P.; Butt, A. D.; Fiorini, C.; Marone, A.; Occhipinti, M.; Peloso, R.; Quaglia, R.; Bombelli, L.; Giacomini, G.; Piemonte, C.; Camera, F.; Giaz, A.; Million, B.; Nelms, N.; Shortt, B.

    2014-05-01

    This work deals with the development of a new gamma detector based on Silicon Drift Detectors (SDDs) to readout large LaBr3:Ce scintillators for gamma-ray spectroscopy and imaging applications. The research is supported by the European Space Agency through the Technology Research Programme (TRP) and by Istituto Nazionale di Fisica Nucleare (INFN) within the Gamma project. The SDDs, produced at Fondazione Bruno Kessler (FBK) semiconductor laboratories, are designed as monolithic arrays of 3 × 3 units, each one of an active area of 8 mm × 8 mm (overall area of 26 mm × 26 mm). The readout electronics and the architecture of the camera are briefly described and then first experimental results coupling the SDD array with a 1'' × 1'' LaBr3:Ce scintillator are reported. An energy resolution of 3% FWHM at 662 keV has been measured at -20°C, better than coupling the same scintillator with a photomultiplier tube. The same scintillator is also used to evaluate position sensitivity with a 1 mm collimated Cs-137 source. The main difficulty in determining the position of the gamma-ray interaction in the crystal is associated to the high thickness/diameter ratio of the crystal (1:1) and the use of reflectors on all lateral and top sides the crystal. This last choice enhances energy resolution but makes imaging capability more challenging because light is spread over all photodetectors. Preliminary results show that the camera is able to detect shifts in the measured signals, when the source is moved with steps of 5 mm. A modified version of the centroid method is finally implemented to evaluate the imaging capability of the system.

  20. The Role of Gamma-ray Imaging in Performing Radiological Characterisation at the Magnox Storage Ponds at the Bradwell Decommissioning Site - 13628

    SciTech Connect

    Hughes, Karl; Shaw, Tracey

    2013-07-01

    A gamma-ray imaging device has been used to perform radiological characterisation work at the spent fuel ponds complex at the site of the Bradwell Magnox Power Station, which is currently undergoing accelerated decommissioning. The objective of using a gamma-ray imaging system was to independently verify previous radiological survey work and to evaluate the adequacy of the random distribution of the destructive core sampling which had been performed. In performing this work the gamma-ray imager clearly identified the exact locations of the sources of radiation that gave rise to the elevated gamma dose rates measured by conventional health physics surveys of the area. In addition, the gamma-ray imager was able to characterise each hotspot as being either dominated by Cs-137 or by Co-60. The gamma imaging survey was undertaken with a RadScan gamma imaging system deployed on the walkways which run along the lengths of the ponds; this enabled the whole imaging survey to be performed with minimal dose uptake, demonstrating the ALARP principle within decommissioning. (authors)

  1. Recent progress of MPPC-based scintillation detectors in high precision X-ray and gamma-ray imaging

    NASA Astrophysics Data System (ADS)

    Kataoka, J.; Kishimoto, A.; Fujita, T.; Nishiyama, T.; Kurei, Y.; Tsujikawa, T.; Oshima, T.; Taya, T.; Iwamoto, Y.; Ogata, H.; Okochi, H.; Ohsuka, S.; Ikeda, H.; Yamamoto, S.

    2015-06-01

    The multi-pixel photon counter (MPPC) is a promising light sensor for various applications, not only in physics experiments but also in nuclear medicine, industry, and even high-energy astrophysics. In this paper, we present the current status and most recent progress of the MPPC-based scintillation detectors, such as (1) a high-precision X-ray and gamma-ray spectral image sensor, (2) next-generation PET detectors with MRI, TOF, and DOI measurement capabilities, and (3) a compact gamma camera for environmental radiation surveys. We first present a new method of fabricating a Ce:GAGG scintillator plate (1 or 2 mm thick) with ultra-fine resolution (0.2 mm/pixel), cut using a dicing saw to create 50 μm wide micro-grooves. When the plate is optically coupled with a large-area MPPC array, excellent spatial resolution of 0.48 mm (FWHM) and energy resolution of 14% (FWHM) are obtained for 122 keV gamma rays. Hence, the detector can act as a convenient "multi-color" imaging device that can potentially be used for future SPECT and photon-counting CT. We then show a prototype system for a high-resolution MPPC-based PET scanner that can realize ≃1 mm (FWHM) spatial resolution, even under a strong magnetic field of 4.7 T. We develop a front-end ASIC intended for future TOF-PET scanner with a 16-channel readout that achieves a coincidence time resolution of 489 ps (FWHM). A novel design for a module with DOI-measurement capability for gamma rays is also presented by measuring the pulse height ratio of double-sided MPPCs coupled at both ends of scintillation crystal block. Finally, we present the concept of a two-plane Compton camera consisting of Ce:GAGG scintillator arrays coupled with thin MPPC arrays. As a result of the thin and compact features of the MPPC device, the camera not only achieves a small size (14×14×15 cm3) and light weight (1.9 kg) but also excellent sensitivity, compared to the conventional PMT-based pinhole camera used in Fukushima. Finally, we briefly

  2. Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

    NASA Astrophysics Data System (ADS)

    Cooper, C. M.; Pace, D. C.; Paz-Soldan, C.; Commaux, N.; Eidietis, N. W.; Hollmann, E. M.; Shiraki, D.

    2016-11-01

    A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

  3. Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited).

    PubMed

    Cooper, C M; Pace, D C; Paz-Soldan, C; Commaux, N; Eidietis, N W; Hollmann, E M; Shiraki, D

    2016-11-01

    A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

  4. Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

    SciTech Connect

    Cooper, C. M.; Pace, D. C.; Paz-Soldan, C.; Eidietis, N. W.; Commaux, N.; Shiraki, D.; Hollmann, E. M.

    2016-11-15

    A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5–100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead “pinhole camera” mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

  5. Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

    SciTech Connect

    Cooper, C. M.; Pace, D. C.; Paz-Soldan, C.; Commaux, N.; Eidietis, N. W.; Hollmann, E. M.; Shiraki, D.

    2016-08-30

    A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20,000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Furthermore, magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

  6. Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

    DOE PAGES

    Cooper, C. M.; Pace, D. C.; Paz-Soldan, C.; ...

    2016-08-30

    A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20,000 pulses permore » second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Furthermore, magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.« less

  7. Dual isotope notch observer for isotope identification, assay and imaging with mono-energetic gamma-ray sources

    DOEpatents

    Barty, Christopher P.J.

    2013-02-05

    A dual isotope notch observer for isotope identification, assay and imaging with mono-energetic gamma-ray sources includes a detector arrangement consists of three detectors downstream from the object under observation. The latter detector, which operates as a beam monitor, is an integrating detector that monitors the total beam power arriving at its surface. The first detector and the middle detector each include an integrating detector surrounding a foil. The foils of these two detectors are made of the same atomic material, but each foil is a different isotope, e.g., the first foil may comprise U235 and second foil may comprise U238. The integrating detectors surrounding these pieces of foil measure the total power scattered from the foil and can be similar in composition to the final beam monitor. Non-resonant photons will, after calibration, scatter equally from both foils.

  8. OPTIMIZATION OF VIRTUAL FRISCH-GRID CdZnTe DETECTOR DESIGNS FOR IMAGING AND SPECTROSCOPY OF GAMMA RAYS.

    SciTech Connect

    BOLOTNIKOV,A.E.; ABDUL-JABBAR, N.M.; BABALOLA, S.; CAMARDA, G.S.; CUI, Y.; HOSSAIN, A.; JACKSON, E.; JACKSON, H.; JAMES, J.R.; LURYI, A.L.; JAMES, R.B.

    2007-08-21

    In the past, various virtual Frisch-grid designs have been proposed for cadmium zinc telluride (CZT) and other compound semiconductor detectors. These include three-terminal, semi-spherical, CAPture, Frisch-ring, capacitive Frisch-grid and pixel devices (along with their modifications). Among them, the Frisch-grid design employing a non-contacting ring extended over the entire side surfaces of parallelepiped-shaped CZT crystals is the most promising. The defect-free parallelepiped-shaped crystals with typical dimensions of 5x5{approx}12 mm3 are easy to produce and can be arranged into large arrays used for imaging and gamma-ray spectroscopy. In this paper, we report on further advances of the virtual Frisch-grid detector design for the parallelepiped-shaped CZT crystals. Both the experimental testing and modeling results are described.

  9. Development of the 3-D Track Imager for Medium and High-Energy Gamma-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    Hunter, Stanley D.

    2006-01-01

    The Advanced Compton Telescope (ACT) and Advanced Pair Telescope (APT) are envisioned as the next medium (0.3 ^ 50 MeV) and high-energy (30 MeV - greater than 100 GeV) gamma-ray missions. These missions will address many research focus areas of the Structure and Evolution of the Universe Roadmap. These areas include: element formation, matter, energy, & magnetic field interactions in galaxies, AGN & GRB emission, and behavior of matter in extreme environments of black holes & pulsars. Achieving these science goals requires a substantial increases in telescope sensitivity and angular resolution. This talk will discuss how these goals can be met with the three-dimensional track imager (3-DTI), a large volume, low density, time projection chamber with two-dimensional micro-well detector readout and report on our development of a 10 cm x 10 cm x 30 prototype instrument.

  10. Detection of gamma rays from a starburst galaxy.

    PubMed

    Acero, F; Aharonian, F; Akhperjanian, A G; Anton, G; Barres de Almeida, U; Bazer-Bachi, A R; Becherini, Y; Behera, B; Bernlöhr, K; Bochow, A; Boisson, C; Bolmont, J; Borrel, V; Brucker, J; Brun, F; Brun, P; Bühler, R; Bulik, T; Büsching, I; Boutelier, T; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Chounet, L-M; Clapson, A C; Coignet, G; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubois, F; Dubus, G; Dyks, J; Dyrda, M; Egberts, K; Emmanoulopoulos, D; Espigat, P; Farnier, C; Fegan, S; Feinstein, F; Fiasson, A; Förster, A; Fontaine, G; Füssling, M; Gabici, S; Gallant, Y A; Gérard, L; Gerbig, D; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Göring, D; Hauser, D; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Hofverberg, P; Hoppe, S; Horns, D; Jacholkowska, A; de Jager, O C; Jahn, C; Jung, I; Katarzyński, K; Katz, U; Kaufmann, S; Kerschhaggl, M; Khangulyan, D; Khélifi, B; Keogh, D; Klochkov, D; Kluźniak, W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Lamanna, G; Lenain, J-P; Lohse, T; Marandon, V; Martineau-Huynh, O; Marcowith, A; Masbou, J; Maurin, D; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Moulin, E; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Olive, J-F; de Oña Wilhelmi, E; Orford, K J; Ostrowski, M; Panter, M; Paz Arribas, M; Pedaletti, G; Pelletier, G; Petrucci, P-O; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raubenheimer, B C; Raue, M; Rayner, S M; Reimer, O; Renaud, M; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Ruppel, J; Sahakian, V; Santangelo, A; Schlickeiser, R; Schöck, F M; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sikora, M; Skilton, J L; Sol, H; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Superina, G; Szostek, A; Tam, P H; Tavernet, J-P; Terrier, R; Tibolla, O; Tluczykont, M; van Eldik, C; Vasileiadis, G; Venter, C; Venter, L; Vialle, J P; Vincent, P; Vivier, M; Völk, H J; Volpe, F; Wagner, S J; Ward, M; Zdziarski, A A; Zech, A

    2009-11-20

    Starburst galaxies exhibit in their central regions a highly increased rate of supernovae, the remnants of which are thought to accelerate energetic cosmic rays up to energies of approximately 10(15) electron volts. We report the detection of gamma rays--tracers of such cosmic rays--from the starburst galaxy NGC 253 using the High Energy Stereoscopic System (H.E.S.S.) array of imaging atmospheric Cherenkov telescopes. The gamma-ray flux above 220 billion electron volts is F = (5.5 +/- 1.0(stat) +/- 2.8(sys)) x 10(-13) cm(-2) s(-1), implying a cosmic-ray density about three orders of magnitude larger than that in the center of the Milky Way. The fraction of cosmic-ray energy channeled into gamma rays in this starburst environment is five times as large as that in our Galaxy.

  11. Development activities of a CdTe/CdZnTe pixel detector for gamma-ray spectrometry with imaging and polarimetry capability in astrophysics

    NASA Astrophysics Data System (ADS)

    Gálvez, J. L.; Hernanz, M.; Álvarez, J. M.; Álvarez, L.; La Torre, M.; Caroli, E.; Lozano, M.; Pellegrini, G.; Ullán, M.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

    2013-05-01

    In the last few years we have been working on feasibility studies of future instruments in the gamma-ray range, from several keV up to a few MeV, in collaboration with other research institutes. High sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators, e.g., Supernovae, Classical Novae, Supernova Remnants (SNRs), Gamma-Ray Bursts (GRBs), Pulsars, Active Galactic Nuclei (AGN).Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CdZnTe) are very attractive materials for gamma-ray detection, since they have already demonstrated their great performance onboard current space missions, such as IBIS/INTEGRAL and BAT/SWIFT, and future projects like ASIM onboard the ISS. However, the energy coverage of these instruments is limited up to a few hundred keV, and there has not been yet a dedicated instrument for polarimetry.Our research and development activities aim to study a gamma-ray imaging spectrometer in the MeV range based on CdTe detectors, suited either for the focal plane of a focusing mission or as a calorimeter for a Compton camera. In addition, our undergoing detector design is proposed as the baseline for the payload of a balloon-borne experiment dedicated to hard X- and soft gamma-ray polarimetry, currently under study and called CμSP (CZT μ-Spectrometer Polarimeter). Other research institutes such as INAF-IASF, DTU Space, LIP, INEM/CNR, CEA, are involved in this proposal. We will report on the main features of the prototype we are developing at the Institute of Space Sciences, a gamma-ray detector with imaging and polarimetry capabilities in order to fulfil the combined requirement of high detection efficiency with good spatial and energy resolution driven by the science.

  12. Gamma-ray camera flyby

    SciTech Connect

    2010-01-01

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

  13. Experimental comparison of high-density scintillators for EMCCD-based gamma ray imaging.

    PubMed

    Heemskerk, Jan W T; Kreuger, Rob; Goorden, Marlies C; Korevaar, Marc A N; Salvador, Samuel; Seeley, Zachary M; Cherepy, Nerine J; van der Kolk, Erik; Payne, Stephen A; Dorenbos, Pieter; Beekman, Freek J

    2012-07-21

    Detection of x-rays and gamma rays with high spatial resolution can be achieved with scintillators that are optically coupled to electron-multiplying charge-coupled devices (EMCCDs). These can be operated at typical frame rates of 50 Hz with low noise. In such a set-up, scintillation light within each frame is integrated after which the frame is analyzed for the presence of scintillation events. This method allows for the use of scintillator materials with relatively long decay times of a few milliseconds, not previously considered for use in photon-counting gamma cameras, opening up an unexplored range of dense scintillators. In this paper, we test CdWO₄ and transparent polycrystalline ceramics of Lu₂O₃:Eu and (Gd,Lu)₂O₃:Eu as alternatives to currently used CsI:Tl in order to improve the performance of EMCCD-based gamma cameras. The tested scintillators were selected for their significantly larger cross-sections at 140 keV ((99m)Tc) compared to CsI:Tl combined with moderate to good light yield. A performance comparison based on gamma camera spatial and energy resolution was done with all tested scintillators having equal (66%) interaction probability at 140 keV. CdWO₄, Lu₂O₃:Eu and (Gd,Lu)₂O₃:Eu all result in a significantly improved spatial resolution over CsI:Tl, albeit at the cost of reduced energy resolution. Lu₂O₃:Eu transparent ceramic gives the best spatial resolution: 65 µm full-width-at-half-maximum (FWHM) compared to 147 µm FWHM for CsI:Tl. In conclusion, these 'slow' dense scintillators open up new possibilities for improving the spatial resolution of EMCCD-based scintillation cameras.

  14. Energy spectrum and flux of 3- to 20-Mev neutrons and 1- to 10-Mev gamma rays in the atmosphere

    NASA Technical Reports Server (NTRS)

    Klumpar, D. M.; Lockwood, J. A.; Saint Onge, R. N.; Friling, L. A.

    1973-01-01

    An experiment is described which was designed to measure the neutron and gamma ray energy spectrums and fluxes in the energy intervals 3 to 20 MeV and 1 to 10 MeV, respectively. In addition, from the 3 to 20-MeV proton recoil spectrums it is possible to infer the shape of the neutron energy spectrum from 20 to 50 MeV. The detecting system utilized a separate charged particle rejection scheme and a two-parameter display system for the output from the pulse shape discrimination which separated gamma rays from neutrons (n). Two long-duration flights were made with this detector in 1970 at Palestine, Tex. (P sub c = 4.6 Gv) and at Ft. Churchill, Canada (P sub c = 0.3 Gv).

  15. Unveiling the secrets of gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Gomboc, Andreja

    2012-07-01

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

  16. Cosmic-Ray Accelerators in Milky Way studied with the Fermi Gamma-ray Space Telescope

    SciTech Connect

    Kamae, Tuneyoshi; /SLAC /KIPAC, Menlo Park

    2012-05-04

    High-energy gamma-ray astrophysics is now situated at a confluence of particle physics, plasma physics and traditional astrophysics. Fermi Gamma-ray Space Telescope (FGST) and upgraded Imaging Atmospheric Cherenkov Telescopes (IACTs) have been invigorating this interdisciplinary area of research. Among many new developments, I focus on two types of cosmic accelerators in the Milky-Way galaxy (pulsar, pulsar wind nebula, and supernova remnants) and explain discoveries related to cosmic-ray acceleration.

  17. Compton DIV: Using a Compton-Based Gamma-Ray Imager for Design Information Verification of Uranium Enrichment Plants

    SciTech Connect

    Burks, M; Verbeke, J; Dougan, A; Wang, T; Decman, D

    2009-07-04

    A feasibility study has been performed to determine the potential usefulness of Compton imaging as a tool for design information verification (DIV) of uranium enrichment plants. Compton imaging is a method of gamma-ray imaging capable of imaging with a 360-degree field of view over a broad range of energies. These systems can image a room (with a time span on the order of one hour) and return a picture of the distribution and composition of radioactive material in that room. The effectiveness of Compton imaging depends on the sensitivity and resolution of the instrument as well the strength and energy of the radioactive material to be imaged. This study combined measurements and simulations to examine the specific issue of UF{sub 6} gas flow in pipes, at various enrichment levels, as well as hold-up resulting from the accumulation of enriched material in those pipes. It was found that current generation imagers could image pipes carrying UF{sub 6} in less than one hour at moderate to high enrichment. Pipes with low enriched gas would require more time. It was also found that hold-up was more amenable to this technique and could be imaged in gram quantities in a fraction of an hour. another questions arises regarding the ability to separately image two pipes spaced closely together. This depends on the capabilities of the instrument in question. These results are described in detail. In addition, suggestions are given as to how to develop Compton imaging as a tool for DIV.

  18. Gamma-Ray Pulsars

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2011-01-01

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

  19. Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Kouveliotou, Chryssa; Wijers, Ralph A. M. J.; Woosley, Stan

    2012-11-01

    Prologue C. Kouveliotou, R. A . M. J. Wijers and S. E. Woosley; 1. The discovery of the gamma-ray burst phenomenon R. W. Klebesadel; 2. Instrumental principles E. E. Fenimore; 3. The BATSE era G. J. Fishman and C. A. Meegan; 4. The cosmological era L. Piro and K. Hurley; 5. The Swift era N. Gehrels and D. N. Burrows; 6. Discoveries enabled by multi-wavelength afterglow observations of gamma-ray bursts J. Greiner; 7. Prompt emission from gamma-ray bursts T. Piran, R. Sari and R. Mochkovitch; 8. Basic gamma-ray burst afterglows P. Mészáros and R. A. M. J. Wijers; 9. The GRB-supernova connection J. Hjorth and J. S. Bloom; 10. Models for gamma-ray burst progenitors and central engines S. E. Woosley; 11. Jets and gamma-ray burst unification schemes J. Granot and E. Ramirez-Ruiz; 12. High-energy cosmic rays and neutrinos E. Waxman; 13. Long gamma-ray burst host galaxies and their environments J. P. U. Fynbo, D. Malesani and P. Jakobsson; 14. Gamma-ray burst cosmology V. Bromm and A. Loeb; 15. Epilogue R. D. Blandford; Index.

  20. Gamma-ray astrophysics

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  1. Gamma ray detector shield

    DOEpatents

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

    1985-08-26

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

  2. A high resolution liquid xenon imaging telescope for 0.3-10 MeV gamma-ray astrophysics: Construction and initial balloon flights

    NASA Technical Reports Server (NTRS)

    Aprile, Elena

    1994-01-01

    An instrument is described which will provide a direct image of gamma-ray line or continuum sources in the energy range 300 keV to 10 MeV. The use of this instrument to study the celestial distribution of the (exp 26)Al isotope by observing the 1.809 MeV deexcitation gamma-ray line is illustrated. The source location accuracy is 2' or better. The imaging telescope is a liquid xenon time projection chamber coupled with a coded aperture mask (LXe-CAT). This instrument will confirm and extend the COMPTEL observations from the Compton Gamma-Ray Observatory (CGRO) with an improved capability for identifying the actual Galactic source or sources of (exp 26)Al, which are currently not known with certainty. sources currently under consideration include red giants on the asymptotic giant branch (AGB), novae, Type 1b or Type 2 supernovae, Wolf-Rayet stars and cosmic-rays interacting in molecular clouds. The instrument could also identify a local source of the celestial 1.809 MeV gamma-ray line, such as a recent nearby supernova.

  3. Instrumentation for gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  5. Gamma-ray Line Astronomy

    NASA Astrophysics Data System (ADS)

    Diehl, R.

    2005-07-01

    Gamma-ray lines from radioactive isotopes, ejected into interstellar space by cosmic nucleosynthesis events, are observed with new space telescopes. The Compton Observatory had provided a sky survey for the isotopes 56Co, 22Na, 44Ti, and 26Al, detecting supernova radioactivity and the diffuse glow of long-lived radioactivity from massive stars in the Galaxy. High-resolution spectroscopy is now being exploited with Ge detectors: Since 2002, with ESA's INTEGRAL satellite and the RHESSI solar imager two space-based Ge-gamma-ray telescopes are in operation, measuring Doppler broadenings and line shape details of cosmic gamma-ray lines. First year's results include a detection and line shape measurement of annihilation emission, and 26Al emission from the inner Galaxy and from the Cygnus region. 60Fe gamma-ray intensity is surprisingly low; it may have been detected by RHESSI at 10% of the 26Al brightness, yet is not seen by INTEGRAL. 44Ti emission from Cas A and SN1987A is being studied; no other candidate young supernova remnants have been found through 44Ti. 22Na from novae still is not seen.

  6. Hard-X and gamma-ray imaging detector for astrophysics based on pixelated CdTe semiconductors

    NASA Astrophysics Data System (ADS)

    Gálvez, J.-L.; Hernanz, M.; Álvarez, L.; Artigues, B.; Ullán, M.; Lozano, M.; Pellegrini, G.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

    2016-01-01

    Stellar explosions are astrophysical phenomena of great importance and interest. Instruments with high sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators. In order to achieve the needed performance, a hard-X and gamma-ray imaging detector with mm spatial resolution and large enough efficiency is required. We present a detector module which consists of a single CdTe crystal of 12.5 × 12.5mm 2 and 2mm thick with a planar cathode and with the anode segmented in an 11x11 pixel array with a pixel pitch of 1 mm attached to the readout chip. Two possible detector module configurations are considered: the so-called Planar Transverse Field (PTF) and the Parallel Planar Field (PPF). The combination of several modules in PTF or PPF configuration will achieve the desired performance of the imaging detector. The sum energy resolution of all pixels of the CdTe module measured at 122 keV and 356 keV is 3.8% and 2% respectively, in the following operating conditions: PPF irradiation, bias voltage -500 V and temperature -10̂ C.

  7. 3D printing in X-ray and Gamma-Ray Imaging: A novel method for fabricating high-density imaging apertures☆

    PubMed Central

    Miller, Brian W.; Moore, Jared W.; Barrett, Harrison H.; Fryé, Teresa; Adler, Steven; Sery, Joe; Furenlid, Lars R.

    2011-01-01

    Advances in 3D rapid-prototyping printers, 3D modeling software, and casting techniques allow for cost-effective fabrication of custom components in gamma-ray and X-ray imaging systems. Applications extend to new fabrication methods for custom collimators, pinholes, calibration and resolution phantoms, mounting and shielding components, and imaging apertures. Details of the fabrication process for these components, specifically the 3D printing process, cold casting with a tungsten epoxy, and lost-wax casting in platinum are presented. PMID:22199414

  8. PRECISE {gamma}-RAY TIMING AND RADIO OBSERVATIONS OF 17 FERMI {gamma}-RAY PULSARS

    SciTech Connect

    Ray, P. S.; Wolff, M. T.; Grove, J. E.; Gwon, C.; Kerr, M.; Parent, D.; Makeev, A.; Abdo, A. A.; Guillemot, L.; Freire, P. C. C.; Kramer, M.; Ransom, S. M.; Rea, N.; Roberts, M. S. E.; Camilo, F.; Dormody, M.; Harding, A. K.; Johnston, S.; Keith, M.; Michelson, P. F.

    2011-06-01

    We present precise phase-connected pulse timing solutions for 16 {gamma}-ray-selected pulsars recently discovered using the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope plus one very faint radio pulsar (PSR J1124-5916) that is more effectively timed with the LAT. We describe the analysis techniques including a maximum likelihood method for determining pulse times of arrival from unbinned photon data. A major result of this work is improved position determinations, which are crucial for multiwavelength follow-up. For most of the pulsars, we overlay the timing localizations on X-ray images from Swift and describe the status of X-ray counterpart associations. We report glitches measured in PSRs J0007+7303, J1124-5916, and J1813-1246. We analyze a new 20 ks Chandra ACIS observation of PSR J0633+0632 that reveals an arcminute-scale X-ray nebula extending to the south of the pulsar. We were also able to precisely localize the X-ray point source counterpart to the pulsar and find a spectrum that can be described by an absorbed blackbody or neutron star atmosphere with a hard power-law component. Another Chandra ACIS image of PSR J1732-3131 reveals a faint X-ray point source at a location consistent with the timing position of the pulsar. Finally, we present a compilation of new and archival searches for radio pulsations from each of the {gamma}-ray-selected pulsars as well as a new Parkes radio observation of PSR J1124-5916 to establish the {gamma}-ray to radio phase offset.

  9. What could cause terrestrial gamma-ray flashes?

    NASA Astrophysics Data System (ADS)

    Dwyer, J. R.

    2007-12-01

    Despite over a decade of research, the sources of Terrestrial Gamma-ray Flashes (TGFs) remain a mystery. Not only are the exact source locations unknown, the basic mechanism for producing the energetic electrons that emit the high-energy photons is still under active debate. When TGFs were first reported using data from the Burst and Transient Source Experiment (BATSE) on NASA's Compton Gamma-ray Observatory (CGRO), it was almost immediately suggested that the source was associated with sprites or other high altitude (>30 km) phenomena. However, new spectral measurements of TGFs by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite as well as detailed modeling of the gamma-ray propagation through the atmosphere indicate that the source altitudes are, in fact, much lower, between 15 and 21 km. Such altitudes are within the range of thunderstorm tops but are much too low for sprites. Because gamma-rays experience large attenuation in the atmosphere, such low source altitudes imply that the number of runaway electrons at the source must be very large, in excess of 10 to the power 16, which could produce measurable currents and changes in the electric charge moment. In this talk, possible source mechanisms of TGFs will be discussed, including runaway electron production through relativistic runaway electron avalanches acting on the cosmic-ray background and on extensive air showers, runaway electron production by the relativistic feedback mechanism, and runaway electron emission from lightning leaders and/or streamers.

  10. Study of gamma-ray emission by proton beam interaction with injected Boron atoms for future medical imaging applications

    NASA Astrophysics Data System (ADS)

    Petringa, G.; Cirrone, G. A. P.; Caliri, C.; Cuttone, G.; Giuffrida, L.; Larosa, G.; Manna, R.; Manti, L.; Marchese, V.; Marchetta, C.; Margarone, D.; Milluzzo, G.; Picciotto, A.; Romano, F.; Romano, F. P.; Russo, A. D.; Russo, G.; Santonocito, D.; Scuderi, V.

    2017-03-01

    In this work an experimental and theoretical study of gamma-prompt emission has been carried out with the main aim being to understand to what extent this approach can be used during a treatment based on proton-boron fusion therapy. An experimental campaign, carried out with a high purity Germanium detector, has been performed to evaluate the gamma emission from two pure 11B and 10B targets. Furthermore, a set of analytical simulations, using the Talys nuclear reaction code has been performed and the calculated spectra compared with the experimental results. These comparisons allowed us to successfully validate Talys which was then used to estimate the gamma emission when a realistic Boron concentration was considered. Both simulations and experimental results suggest that the gamma emission is low at certain proton energies, thus in order to improve the imaging capabilities, while still maintaining the Boron therapeutic role, we propose the addition of natural Copper bound by a dipyrromethene, BodiPy, to boron atoms. Analytical simulations with Talys suggest that the characteristic spectrum of the copper prompt gamma-rays has several peaks in the energetic regions where the background is negligible.

  11. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1991-01-01

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

  12. Development of a high-precision color gamma-ray image sensor based on TSV-MPPC and diced scintillator arrays

    NASA Astrophysics Data System (ADS)

    Oshima, T.; Kataoka, J.; Kishimoto, A.; Fujita, T.; Kurei, Y.; Nishiyama, T.; Morita, H.; Yamamoto, S.; Ogawa, K.

    2015-12-01

    We developed a high-precision color gamma-ray image sensor with fine spatial resolution that is cost effective, widely applicable, and very sensitive, by using a diced Ce-doped Gd3 Al2 Ga3 O12 (Ce:GAGG) scintillator array coupled with a 3.0×3.0 mm2/pixel 8×8 MPPC-array. The proposed image sensor can measure the energy of individual X-ray photons transmitted through an object. The pixel size of the Ce:GAGG scintillator array is 0.2 mm, and the pixels are separated by 50-μm-wide micro-grooves. The image sensor has an area of 20×20 mm2 and a thickness of 1.0 mm, and it achieves an excellent spatial resolution of 0.3-0.4 mm and energy resolutions of 12% and 18% (FWHM) for 122 and 59.5 keV gamma-rays, respectively. We conducted an experiment to determine the local effective atomic number of metals using dual-energy gamma-ray sources. In addition, we developed a color-composite image using mixed images taken at three energies (31, 59.5, and 88 keV).

  13. Gamma-Ray Telescopes

    NASA Astrophysics Data System (ADS)

    Weekes, T.; Murdin, P.

    2000-11-01

    Gamma-rays are the highest-energy photons in the ELECTROMAGNETIC SPECTRUM and their detection presents unique challenges. On one hand it is easy to detect γ-rays. The interaction cross-sections are large and above a few MeV the pair production interaction, the dominant γ-ray interaction with matter, is easily recognized. Gamma-ray detectors were far advanced when the concept of `γ-ray astronomy' ...

  14. Review on Monte-Carlo Tools for Simulating Relativistic Runaway Electron Avalanches and the Propagation of TerretrialTerrestrial-Gamma Ray Flashes in the Atmosphere

    NASA Astrophysics Data System (ADS)

    Sarria, D.

    2016-12-01

    The field of High Energy Atmospheric Physics (HEAP) includes the study of energetic events related to thunderstorms, such as Terrestrial Gamma-ray Flashes (TGF), associated electron-positron beams (TEB), gamma-ray glows and Thunderstorm Ground Enhancements (TGE). Understanding these phenomena requires accurate models for the interaction of particles with atmospheric air and electro-magnetic fields in the <100 MeV energy range. This study is the next step of the work presented in [C. Rutjes et al., 2016] that compared the performances of various codes in the absence of electro-magnetic fields. In the first part, we quantify simple but informative test cases of electrons in various electric field profiles. We will compare the avalanche length (of the Relativistic Runaway Electron Avalanche (RREA) process), the photon/electron spectra and spatial scattering. In particular, we test the effect of the low-energy threshold, that was found to be very important [Skeltved et al., 2014]. Note that even without a field, it was found to be important because of the straggling effect [C. Rutjes et al., 2016]. For this first part, we will be comparing GEANT4 (different flavours), FLUKA and the custom made code GRRR. In the second part, we test the propagation of these high energy particles in the atmosphere, from production altitude (around 10 km to 18 km) to satellite altitude (600 km). We use a simple and clearly fixed set-up for the atmospheric density, the geomagnetic field, the initial conditions, and the detection conditions of the particles. For this second part, we will be comparing GEANT4 (different flavours), FLUKA/CORSIKA and the custom made code MC-PEPTITA. References : C. Rutjes et al., 2016. Evaluation of Monte Carlo tools for high energy atmospheric physics. Geosci. Model Dev. Under review. Skeltved, A. B. et al., 2014. Modelling the relativistic runaway electron avalanche and the feedback mechanism with geant4. JGRA, doi :10.1002/2014JA020504.

  15. Gamma ray optics

    SciTech Connect

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

    2012-07-09

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

  16. Combining Measurements with Three-Dimensional Laser Scanning System and Coded Aperture Gamma-Ray Imaging Systems for International Safeguards Applications

    SciTech Connect

    Boehnen, Chris Bensing; Bogard, James S; Hayward, Jason P; Raffo-Caiado, Ana Claudia; Smith, Stephen E; Ziock, Klaus-Peter

    2010-01-01

    Being able to verify the operator's declaration in regards to technical design of nuclear facilities is an important aspect of every safeguards approach. In addition to visual observation, it is relevant to know if nuclear material is present or has been present in piping and ducts not declared. The possibility of combining different measurement techniques into one tool should optimize the inspection effort and increase safeguards effectiveness. Oak Ridge National Laboratory (ORNL) is engaged in a technical collaboration project involving two U.S. Department of Energy foreign partners to investigate combining measurements from a three-dimensional (3D) laser scanning system and gamma-ray imaging systems. ORNL conducted simultaneous measurements with a coded-aperture gamma-ray imager and the 3D laser scanner in an operational facility with complex configuration and different enrichment levels and quantities of uranium. This paper describes these measurements and their results.

  17. Comparison of the imaging performances for recently developed monolithic scintillators: CRY018 and CRY019 for dual isotope gamma ray imaging applications

    NASA Astrophysics Data System (ADS)

    Polito, C.; Pani, R.; Trigila, C.; Cinti, M. N.; Fabbri, A.; Frantellizzi, V.; De Vincentis, G.; Pellegrini, R.; Pani, R.

    2017-01-01

    The growing interest for new scintillation crystals with outstanding imaging performances (i.e. resolution and efficiency) has suggested the study of recently discovered scintillators named CRY018 and CRY019. The crystals under investigation are monolithic and have shown enhanced characteristics both for gamma ray spectrometry and for Nuclear Medicine imaging applications such as the dual isotope imaging. Moreover, the non-hygroscopic nature and the absence of afterglow make these scintillators even more attractive for the potential improvement in a wide range of applications. These scintillation crystals show a high energy resolution in the energy range involved in Nuclear Medicine, allowing the discrimination between very close energy values. Moreover, in order to prove their suitability of being powerful imaging systems, the imaging performances like the position linearity and the intrinsic spatial resolution have been evaluated obtaining satisfactory results thanks to the implementation of an optimized algorithm for the images reconstruction.

  18. Electron-tracking Compton gamma-ray camera for small animal and phantom imaging

    NASA Astrophysics Data System (ADS)

    Kabuki, Shigeto; Kimura, Hiroyuki; Amano, Hiroo; Nakamoto, Yuji; Kubo, Hidetoshi; Miuchi, Kentaro; Kurosawa, Shunsuke; Takahashi, Michiaki; Kawashima, Hidekazu; Ueda, Masashi; Okada, Tomohisa; Kubo, Atsushi; Kunieda, Etuso; Nakahara, Tadaki; Kohara, Ryota; Miyazaki, Osamu; Nakazawa, Tetsuo; Shirahata, Takashi; Yamamoto, Etsuji; Ogawa, Koichi; Togashi, Kaori; Saji, Hideo; Tanimori, Toru

    2010-11-01

    We have developed an electron-tracking Compton camera (ETCC) for medical use. Our ETCC has a wide energy dynamic range (200-1300 keV) and wide field of view (3 sr), and thus has potential for advanced medical use. To evaluate the ETCC, we imaged the head (brain) and bladder of mice that had been administered with F-18-FDG. We also imaged the head and thyroid gland of mice using double tracers of F-18-FDG and I-131 ions.

  19. Gamma-Ray Burst Physics with GLAST

    SciTech Connect

    Omodei, N.; /INFN, Pisa

    2006-10-06

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

  20. Development of a new RF coil and gamma-ray radiation shielding assembly for improved MR image quality in SPECT/MRI.

    PubMed

    Ha, Seunghoon; Hamamura, Mark J; Roeck, Werner W; Muftuler, L Tugan; Nalcioglu, Orhan

    2010-05-07

    Magnetic resonance (MR)-based multimodality imaging systems, such as single-photon emission tomography (SPECT)/magnetic resonance imaging (MRI) or positron emission tomography (PET)/MRI, face many difficulties because of problems with the compatibility of the nuclear detector system with the MR system. However, several studies have reported on the design considerations of MR-compatible nuclear detectors for combined SPECT/MRI. In this study, we developed a new radiofrequency (RF) coil and gamma-ray radiation shielding assembly to advance the practical implementation of SPECT/MRI in providing high sensitivity while minimizing the interference between the MRI and SPECT systems. The proposed assembly consists of a three-channel receive-only RF coil and gamma-ray radiation shields made of a specialized lead composite powder designed to reduce conductivity and thus minimizing any effect on the magnetic field arising from the induced eddy currents. A conventional birdcage RF coil was also tested for comparison with the proposed RF coil. Quality (Q)-factors were measured using both RF coils without any shielding, with solid lead shielding, and with our composite lead shielding. Signal-to-noise ratios (SNRs) were calculated using 4 T MR images of phantoms both with and without the new gamma-ray radiation shields. The Q-factor and SNR measurements demonstrate the improved MRI performance due to the new RF coil/gamma-ray radiation shield assembly designed for SPECT/MRI, making it a useful addition to multimodality imaging technology not only for animal studies but also for in vivo study of humans.

  1. The application of two-dimensional imaging to very high energy gamma ray astronomy. [Smithsonian Institution Astrophysical Observatory, Cambridge, Massachusetts

    SciTech Connect

    Weekes, T.C.

    1992-12-01

    After an introductory overview of gamma-ray astronomy, very brief summaries of research results are given. Summary topics may be grouped as follows: observations (survey of candidate gamma-ray sources; Cygnus X-3; Markarian 421; AGN's: general survey; Crab observations: pulsar outburst; Geminga; AE Aqr; bursts; ARTEMIS; muon telescope), technical developments (11m telescope: dedication and performance; 10m mount control; CCD cameras; light cones; filters; GRANITE upgrade; trigger configuration; miror coatings; lightning protection), data analysis (quick look; optical disk archive; false source method), infrastructure, and reviews.

  2. Crystal Identification in Stacked GAGG Scintillators for 4π Direction Sensitive Gamma-ray Imager

    NASA Astrophysics Data System (ADS)

    Fuwa, Yuta; Takahashi, Tone; Kawarabayashi, Jun; Tomita, Hideki; Matui, Daiki; Takada, Eiji; Iguchi, Tetsuo

    To identify two interaction points in stacked Ce:GAGG scintillators for Compton imaging, center of gravity with small area of the MA-PMT outputs, called small area center of gravity (SACG) method, was developed to reduce channel numbers of the MA-PMT. Both longitudinal position and energy resolutions of each scintillator rod by SACG method were evaluated in coincident events in 2 × 2 stacked Ce:GAGG scintillators. Crystal identification was successfully demonstrated in 16 × 16 stacked scintillators.

  3. Hard-X-Ray/Soft-Gamma-Ray Imaging Sensor Assembly for Astronomy

    NASA Technical Reports Server (NTRS)

    Myers, Richard A.

    2008-01-01

    An improved sensor assembly has been developed for astronomical imaging at photon energies ranging from 1 to 100 keV. The assembly includes a thallium-doped cesium iodide scintillator divided into pixels and coupled to an array of high-gain avalanche photodiodes (APDs). Optionally, the array of APDs can be operated without the scintillator to detect photons at energies below 15 keV. The array of APDs is connected to compact electronic readout circuitry that includes, among other things, 64 independent channels for detection of photons in various energy ranges, up to a maximum energy of 100 keV, at a count rate up to 3 kHz. The readout signals are digitized and processed by imaging software that performs "on-the-fly" analysis. The sensor assembly has been integrated into an imaging spectrometer, along with a pair of coded apertures (Fresnel zone plates) that are used in conjunction with the pixel layout to implement a shadow-masking technique to obtain relatively high spatial resolution without having to use extremely small pixels. Angular resolutions of about 20 arc-seconds have been measured. Thus, for example, the imaging spectrometer can be used to (1) determine both the energy spectrum of a distant x-ray source and the angular deviation of the source from the nominal line of sight of an x-ray telescope in which the spectrometer is mounted or (2) study the spatial and temporal development of solar flares, repeating - ray bursters, and other phenomena that emit transient radiation in the hard-x-ray/soft- -ray region of the electromagnetic spectrum.

  4. All-Sky Imaging With the Fermi Gamma-ray Burst Monitor

    NASA Astrophysics Data System (ADS)

    Rodi, James; Case, G.; Cherry, M.; Wilson-Hodge, C.; Camero-Arranz, A.; Chaplin, V.; Finger, M.; Jenke, P.

    2011-09-01

    As demonstrated by BATSE and GBM, Earth occultation with non-imaging detectors can be used as a method for measuring source fluxes by looking at the differences in count rates in a detector that occur when a source moves into or out of occultation by the Earth. The Earth Occultation Technique applied to GBM's array of twelve NaI detectors makes it possible to monitor the entire sky every 26 days in the energy range 8 - 500 keV. The standard Earth Occultation Technique equires a predefined input catalog of source positions. Having an incomplete catalog has been shown to result in increased systematic errors. In order to find sources not included in the input catalog, an indirect imaging method has been developed that uses the projection of the Earth's limb onto the sky at the time a source occults. Over the course of an orbital precession period ( 53 days), all available projection angles are sampled. These projections add constructively near the position of a source, thus allowing the source to be localized. We present all-sky image results in the 12-25, 25-50, and 100-300 keV energy bands for 3 years of data from GBM, and discuss the correlations with the Swift/BAT, INTEGRAL/SPI, and Fermi/LAT catalogs.

  5. Combining Measurements with Three-Dimensional Laser Scanning System and Coded Aperture Gamma-Ray Imaging System for International Safeguards Applications

    SciTech Connect

    Boehnen, Chris Bensing; Bogard, James S; Hayward, Jason P; Raffo-Caiado, Ana Claudia; Smith, Steven E; Ziock, Klaus-Peter

    2010-01-01

    Being able to verify the operator's declaration in regard to the technical design of nuclear facilities is an important aspect of every safeguards approach. In addition to visual observation, it is necessary to know if nuclear material is present or has been present in undeclared piping and ducts. The possibility of combining the results from different measurement techniques into one easily interpreted product should optimize the inspection effort and increase safeguards effectiveness. A collaborative effort to investigate the possibility of combining measurements from a three-dimensional (3D) laser scanning system and gamma-ray imaging systems is under way. The feasibility of the concept has been previously proven with different laboratory prototypes of gamma-ray imaging systems. Recently, simultaneous measurements were conducted with a new highly portable, mechanically cooled, High Purity Germanium (HPGe), coded-aperture gamma-ray imager and a 3D laser scanner in an operational facility with complex configuration and different enrichment levels and quantities of uranium. With specially designed software, data from both instruments were combined and a 3D model of the facility was generated that also identified locations of radioactive sources. This paper provides an overview of the technology, describes the measurements, discusses the various safeguards scenarios addressed, and presents results of experiments.

  6. TRW processing and check out of Gamma Ray Observatory (GRO)

    NASA Technical Reports Server (NTRS)

    1990-01-01

    As they prepare for the shipment of the Gamma Ray Observatory (GRO) from TRW's assembly room to the Kennedy Space Center (KSC), TRW workers and NASA engineers are dwarfed by the heaviest NASA science satellite ever to be deployed by the Space Shuttle into low Earth orbit. GRO is suspended by overhead crane at one end and positioned in rack at the other end. The four GRO instruments include the Oriented Scintillation Spectrometer Experiment (OSSE) (at bottom), the Imaging Compton Telescope (COMPTEL) (center), the Energetic Gamma Ray Experiment Telescope (EGRET) (at top), and the Burst and Transient Source Experiment (BATSE) (located on GRO's corners). GRO, which weighs just over 35,000 pounds (15,876 kilograms), is a space-based observatory scheduled to be put into space by Atlantis, Orbiter Vehicle (OV) 104, next year. GRO is designed to study the universe in an invisible, high-energy form of light known as gamma rays. Gamma rays, which cannot penetrate the Earth's atmosphere, are of i

  7. Gamma Ray Observatory (GRO) in ground support structure at TRW

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The Gamma Ray Observatory (GRO) is positioned in a support structure in TRW's assembly room for checkout and processing prior to shipment to the Kennedy Space Center (KSC). GRO is the heaviest NASA science satellite ever to be deployed by the Space Shuttle into low Earth orbit. GRO's trunnions are locked into the support structure. From left to right are three of the four GRO instruments including the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), and the Energetic Gamma Ray Experiment Telescope (EGRET). The Burst and Transient Source Experiment (BATSE) equipment is located on GRO's corners. GRO, which weighs just over 35,000 pounds (15,876 kilograms), is a space-based observatory scheduled to be put into space by Atlantis, Orbiter Vehicle (OV) 104, next year. GRO is designed to study the universe in an invisible, high-energy form of light known as gamma rays. Gamma rays, which cannot penetrate the Earth's atmosphere, are of interest to

  8. Gamma Ray Observatory (GRO) in ground support structure at TRW

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The Gamma Ray Observatory (GRO) is positioned in a support structure in TRW's assembly room for checkout and processing prior to shipment to the Kennedy Space Center (KSC). GRO is the heaviest NASA science satellite ever to be deployed by the Space Shuttle into low Earth orbit. GRO's trunnions are locked into the support structure. From left to right are three of the four GRO instruments including the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), and the Energetic Gamma Ray Experiment Telescope (EGRET). The Burst and Transient Source Experiment (BATSE) equipment is located on GRO's corners. GRO, which weighs just over 35,000 pounds (15,876 kilograms), is a space-based observatory scheduled to be put into space by Atlantis, Orbiter Vehicle (OV) 104, next year. GRO is designed to study the universe in an invisible, high-energy form of light known as gamma rays. Gamma rays, which cannot penetrate the Earth's atmosphere, are of interest to

  9. A liquid xenon imaging telescope for gamma ray astrophysics: Design and expected performance

    NASA Technical Reports Server (NTRS)

    Aprile, E.; Mukherjee, R.; Chen, D.; Bolotnikov, A.

    1992-01-01

    A high resolution telescope for imaging cosmic x ray sources in the MeV region, with an angular resolution better than 0.5 deg is being developed as balloon-borne payload. The instrument consists of a 3-D liquid xenon TPC as x ray detector, coupled with a coded aperture at a distance of 1 meter. A study of the actual source distribution of the 1.809 MeV line from the decay of Al-26 and the 511 keV positron-electron annihilation line is among the scientific objectives, along with a search for new x ray sources. The telescope design parameters and expected minimum flux sensitivity to line and continuum radiation are presented. The unique capablity of the LXe-TPC as a Compton Polarimeter is also discussed.

  10. Prompt gamma-ray emission for future imaging applications in proton-boron fusion therapy

    NASA Astrophysics Data System (ADS)

    Petringa, G.; Cirrone, G. A. P.; Caliri, C.; Cuttone, G.; Giuffrida, L.; La Rosa, G.; Manna, R.; Manti, L.; Marchese, V.; Marchetta, C.; Margarone, D.; Milluzzo, G.; Picciotto, A.; Romano, F.; Romano, F. P.; Russo, A. D.; Russo, G.; Santonocito, D.; Scuderi, V.

    2017-03-01

    Recently, an approach exploiting the proton therapy biological enhancement by using Boron atoms injected inside a tumor, has been proposed [1-3]. Here, the 11B(p,α)2α nuclear fusion reaction channel, where three alpha particles are produced with an average energy around 4 MeV, is considered [4]. These alphas are able to penetrate the cells nucleus and strongly damage their DNA. In addition, gamma prompts emitted by the proton Boron nuclear reactions can be used for on-line proton beam imaging purposes. In this work an experimental study of the gamma prompt emissions from the proton Boron nuclear reactions has been carried out with the main aim to understand and quantify the most probable emission for future clinical applications.

  11. Interpretations and implications of gamma-ray lines from solar flares, the galactic centre and gamma-ray transients

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1981-01-01

    Gamma-ray line emission from the Sun results from the nuclear interactions of energetic protons and nuclei with the solar atmosphere. These interactions produce gamma-ray lines from neutron capture, positron annihilation, and nuclear deexcitation. Observation of such gamma-rays can provide unique information on high energy processes at the Sun. Details of solar gamma-ray spectroscopy are discussed along with the galactic center 0.511 MeV line. The richness of astronomy at 0.511 MeV is indicated by the great variety of astrophysical positron production mechanisms and by the many astrophysical sites where such mechanisms could operate. Attention is also given to lines from gamma-ray transients, and the prospects for gamma-ray line detections, taking into account gamma-ray lines from processes of nucleosynthesis and lines from low-energy cosmic ray interactions.

  12. Prototype AEGIS: A Pixel-Array Readout Circuit for Gamma-Ray Imaging

    PubMed Central

    Barber, H. Bradford; Augustine, F. L.; Furenlid, L.; Ingram, C. M.; Grim, G. P.

    2015-01-01

    Semiconductor detector arrays made of CdTe/CdZnTe are expected to be the main components of future high-performance, clinical nuclear medicine imaging systems. Such systems will require small pixel-pitch and much larger numbers of pixels than are available in current semiconductor-detector cameras. We describe the motivation for developing a new readout integrated circuit, AEGIS, for use in hybrid semiconductor detector arrays, that may help spur the development of future cameras. A basic design for AEGIS is presented together with results of an HSPICE™ simulation of the performance of its unit cell. AEGIS will have a shaper-amplifier unit cell and neighbor pixel readout. Other features include the use of a single input power line with other biases generated on-board, a control register that allows digital control of all thresholds and chip configurations and an output approach that is compatible with list-mode data acquisition. An 8×8 prototype version of AEGIS is currently under development; the full AEGIS will be a 64×64 array with 300 μm pitch. PMID:26345126

  13. The host galaxies and explosion sites of long-duration gamma ray bursts: Hubble Space Telescope near-infrared imaging

    NASA Astrophysics Data System (ADS)

    Lyman, J. D.; Levan, A. J.; Tanvir, N. R.; Fynbo, J. P. U.; McGuire, J. T. W.; Perley, D. A.; Angus, C. R.; Bloom, J. S.; Conselice, C. J.; Fruchter, > A. S.; Hjorth, J.; Jakobsson, P.; Starling, R. L. C.

    2017-01-01

    We present the results of a Hubble Space Telescope WFC3/F160W SNAPSHOT survey of the host galaxies of 39 long-duration gamma-ray bursts (LGRBs) at z < 3. We have non-detections of hosts at the locations of 4 bursts. Sufficient accuracy to astrometrically align optical afterglow images and determine the location of the LGRB within its host was possible for 31/35 detected hosts. In agreement with other work, we find the luminosity distribution of LGRB hosts is significantly fainter than that of a star formation rate-weighted field galaxy sample over the same redshift range, indicating LGRBs are not unbiasedly tracing the star formation rate. Morphologically, the sample of LGRB hosts are dominated by spiral-like or irregular galaxies. We find evidence for evolution of the population of LGRB hosts towards lower-luminosity, higher concentrated hosts at lower redshifts. Their half-light radii are consistent with other LGRB host samples where measurements were made on rest-frame UV observations. In agreement with recent work, we find their 80 per cent enclosed flux radii distribution to be more extended than previously thought, making them intermediate between core-collapse supernova (CCSN) and super-luminous supernova (SLSN) hosts. The galactocentric projected-offset distribution confirms LGRBs as centrally concentrated, much more so than CCSNe and similar to SLSNe. LGRBs are strongly biased towards the brighter regions in their host light distributions, regardless of their offset. We find a correlation between the luminosity of the LGRB explosion site and the intrinsic column density, NH, towards the burst.

  14. The host galaxies and explosion sites of long-duration gamma ray bursts: Hubble Space Telescope near-infrared imaging

    NASA Astrophysics Data System (ADS)

    Lyman, J. D.; Levan, A. J.; Tanvir, N. R.; Fynbo, J. P. U.; McGuire, J. T. W.; Perley, D. A.; Angus, C. R.; Bloom, J. S.; Conselice, C. J.; Fruchter, A. S.; Hjorth, J.; Jakobsson, P.; Starling, R. L. C.

    2017-05-01

    We present the results of a Hubble Space Telescope WFC3/F160W Snapshot survey of the host galaxies of 39 long-duration gamma-ray bursts (LGRBs) at z < 3. We have non-detections of hosts at the locations of four bursts. Sufficient accuracy to astrometrically align optical afterglow images and determine the location of the LGRB within its host was possible for 31/35 detected hosts. In agreement with other work, we find the luminosity distribution of LGRB hosts is significantly fainter than that of a star formation rate-weighted field galaxy sample over the same redshift range, indicating LGRBs are not unbiasedly tracing the star formation rate. Morphologically, the sample of LGRB hosts is dominated by spiral-like or irregular galaxies. We find evidence for evolution of the population of LGRB hosts towards lower luminosity, higher concentrated hosts at lower redshifts. Their half-light radii are consistent with other LGRB host samples where measurements were made on rest-frame UV observations. In agreement with recent work, we find their 80 per cent enclosed flux radii distribution to be more extended than previously thought, making them intermediate between core-collapse supernova (CCSN) and superluminous supernova (SLSN) hosts. The galactocentric projected-offset distribution confirms LGRBs as centrally concentrated, much more so than CCSNe and similar to SLSNe. LGRBs are strongly biased towards the brighter regions in their host light distributions, regardless of their offset. We find a correlation between the luminosity of the LGRB explosion site and the intrinsic column density, NH, towards the burst.

  15. Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Meszaros, Peter

    2012-01-01

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

  16. Development of a multi-knife-edge slit collimator for prompt gamma ray imaging during proton beam cancer therapy

    NASA Astrophysics Data System (ADS)

    Ready, John Francis, III

    Proton beam usage to treat cancer has recently experienced rapid growth, as it offers the ability to target dose delivery in a patient more precisely than traditional x-ray treatment methods. Protons stop within the patient, delivering the maximum dose at the end of their track--a phenomenon described as the Bragg peak. However, because a large dose is delivered to a small volume, proton therapy is very sensitive to errors in patient setup and treatment planning calculations. Additionally, because all primary beam particles stop in the patient, there is no direct information available to verify dose delivery. These factors contribute to the range uncertainty in proton therapy, which ultimately hinders its clinical usefulness. A reliable method of proton range verification would allow the clinician to fully utilize the precise dose delivery of the Bragg peak. Several methods to verify proton range detect secondary emissions, especially prompt gamma ray (PG) emissions. However, detection of PGs is challenging due to their high energy (2-10 MeV) and low attenuation coefficients, which limit PG interactions in materials. Therefore, detection and collimation methods must be specifically designed for prompt gamma ray imaging (PGI) applications. In addition, production of PGs relies on delivering a dose of radiation to the patient. Ideally, verification of the Bragg peak location exposes patients to a minimal dose, thus limiting the PG counts available to the imaging system. An additional challenge for PGI is the lack of accurate simulation models, which limit the study of PG production characteristics and the relationship between PG distribution and dose delivery. Specific limitations include incorrect modeling of the reaction cross sections, gamma emission yields, and angular distribution of emission for specific photon energies. While simulations can still be valuable assets in designing a system to detect and image PGs, until new models are developed and incorporated

  17. Imaging of Celestial Gamma Ray Sources in the 1 TO 30 Mev Range via Direct Linear Algebraic Deconvolution.

    NASA Astrophysics Data System (ADS)

    Buchholz, James Richard

    1996-01-01

    The results which are presented in this manuscript include an outline of the development and use of Direct Linear Algebraic Deconvolution (DLAD) image reconstruction on the UCR Compton Double Scatter Gamma Ray Telescope data. This telescope is sensitive to the energy range of 1 to 30 MeV. Two sources (Crab Nebula and Pulsar and the Galactic Center) are emphasized in this paper. The northern hemisphere sources (Crab, etc.) were analyzed using data from a 30 September, 1989 UCR balloon-borne flight, and southern hemisphere sources (Galactic Center) were analyzed using data from an 15 April, 1988 UCR balloon flight. Monte Carlo simulation results are presented for discrete (and slightly diffuse) sources transversing the field-of-view of our Compton telescope for a typical non -pointing balloon flight observation. A method is described for producing source images in a fixed celestial coordinate system which are deconvolved from data obtained in a detector coordinate system where the source coordinates are continuously changing. This method has been applied to real data. The Crab Nebula was detected in the 3-10 and 10-30 MeV ranges at fluxes of rm 1.5 times 10^ {-4} phcdot cm^{-2} cdot s^{-1} and rm 1.1 times 10^{-4} phcdot cm^{-2}cdot s^ {-1}, respectively, with statistical significances of 1.2sigma and 1.7sigma , respectively. It is important to note that the method described in this dissertation for estimating the errors in the deconvolved fluxes (section 3.3) provides an underestimation of the significance of these results. Excess emission in the energy range from 1.7 to 1.9 MeV, believed to be due to 1.8 MeV ^ {26}Al de-exitation in the Galactic center and plane regions, was observed at the level of rm 1.1 times 10^{-4} phcdot cm^{-2}cdot s^ {-1} with a calculated significance of 1.4sigma. Due to the low statistical significance of these excesses, these fluxes should be considered upper limits.

  18. Celestial gamma ray study

    NASA Technical Reports Server (NTRS)

    Michelson, Peter F.

    1995-01-01

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

  19. 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.

  20. Scission gamma rays

    SciTech Connect

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Kuznetsov, V. L.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2009-11-15

    Gamma rays probably emitted by the fissioning nucleus {sup 236}U* at the instant of the break of the neck or within the time of about 10{sup -21} s after or before this were discovered in the experiment devoted to searches for the effect of rotation of the fissioning nucleus in the process {sup 235}U(n,{gamma}f) and performed in a polarized beam of cold neutrons from the MEPHISTO Guideline at the FRM II Munich reactor. Detailed investigations revealed that the angular distribution of these gamma rays is compatible with the assumption of the dipole character of the radiation and that their energy spectrum differs substantially from the spectrum of prompt fission gamma rays. In the measured interval 250-600 keV, this spectrum can be described by an exponential function at the exponent value of {alpha} = -5 x 10{sup -3} keV{sup -1}. The mechanism of radiation of such gamma rays is not known at the present time. Theoretical models based on the phenomenon of the electric giant dipole resonance in a strongly deformed fissioning nucleus or in a fission fragment predict harder radiation whose spectrum differs substantially from the spectrum measured in the present study.

  1. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1991-01-01

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

  2. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1992-01-01

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

  3. A Gamma-Ray Camera for Inspection Control

    SciTech Connect

    Danilenko, K.N.; Ignatyev, G.N.; Semenov, D.S; D Chernov, M.Y.; Morgan, J.

    2000-06-29

    The Research Institute of Pulse Technique has constructed a gamma-ray camera for imaging radioactive materials. The work was performed under the DOE Lab to Lab Dismantlement Transparency Program with the Lawrence Livermore National Laboratory (USA). The gamma-ray camera was intended for imaging radioactive materials, including fissile materials, in a storage container. In this case, the spatial resolution established in the specifications for the gamma ray camera was limited for reasons of inspection non-intrusiveness.

  4. Early-time observations of gamma-ray burst error boxes with the Livermore optical transient imaging system

    SciTech Connect

    Williams, G G

    2000-08-01

    Despite the enormous wealth of gamma-ray burst (GRB) data collected over the past several years the physical mechanism which causes these extremely powerful phenomena is still unknown. Simultaneous and early time optical observations of GRBs will likely make an great contribution t o our understanding. LOTIS is a robotic wide field-of-view telescope dedicated to the search for prompt and early-time optical afterglows from gamma-ray bursts. LOTIS began routine operations in October 1996 and since that time has responded to over 145 gamma-ray burst triggers. Although LOTIS has not yet detected prompt optical emission from a GRB its upper limits have provided constraints on the theoretical emission mechanisms. Super-LOTIS, also a robotic wide field-of-view telescope, can detect emission 100 times fainter than LOTIS is capable of detecting. Routine observations from Steward Observatory's Kitt Peak Station will begin in the immediate future. During engineering test runs under bright skies from the grounds of Lawrence Livermore National Laboratory Super-LOTIS provided its first upper limits on the early-time optical afterglow of GRBs. This dissertation provides a summary of the results from LOTIS and Super-LOTIS through the time of writing. Plans for future studies with both systems are also presented.

  5. SU-E-T-335: Dosimetric Investigation of An Advanced Rotating Gamma Ray System for Imaged Guided Radiation Therapy

    SciTech Connect

    Ma, C; Eldib, A; Chibani, O; Li, J; Chen, L; Li, C; Mora, G

    2015-06-15

    Purpose: Co-60 beams have unique dosimetric properties for cranial treatments and thoracic cancers. The conventional concern about the high surface dose is overcome by modern system designs with rotational treatment techniques. This work investigates a novel rotational Gamma ray system for image-guided, external beam radiotherapy. Methods: The CybeRT system (Cyber Medical Corp., China) consists of a ring gantry with either one or two treatment heads containing a Gamma source and a multileaf collimator (MLC). The MLC has 60 paired leaves, and the maximum field size is either 40cmx40cm (40 pairs of 0.5cm central leaves, 20 pairs of 1cm outer leaves), or 22cmx40cm (32 pairs of 0.25cm central leaves, 28 pairs of 0.5cm outer leaves). The treatment head(s) can swing 35° superiorly and 8° inferiorly, allowing a total of 43° non-coplanar beam incident. The treatment couch provides 6-degrees-of-freedom motion compensation and the kV cone-beam CT system has a spatial resolution of 0.4mm. Monte Carlo simulations were used to compute dose distributions and compare with measurements. A retrospective study of 98 previously treated patients was performed to compare CybeRT with existing RT systems. Results: Monte Carlo results confirmed the CybeRT design parameters including output factors and 3D dose distributions. Its beam penumbra/dose gradient was similar to or better than that of 6MV photon beams and its isocenter accuracy is 0.3mm. Co-60 beams produce lower-energy secondary electrons that exhibit better dose properties in low-density lung tissues. Because of their rapid depth dose falloff, Co-60 beams are favorable for peripheral lung tumors with half-arc arrangements to spare the opposite lung and critical structures. Superior dose distributions were obtained for head and neck, breast, spine and lung tumors. Conclusion: Because of its accurate dose delivery and unique dosimetric properties of C-60 sources, CybeRT is ideally suited for advanced SBRT as well as

  6. Demystifying an Unidentified EGRET Source by VHE gamma-ray Observations

    SciTech Connect

    Reimer, Olaf; Funk, Stefan; /KIPAC, Menlo Park

    2007-04-17

    In a novel approach in observational high-energy gamma-ray astronomy, observations carried out by imaging atmospheric Cherenkov telescopes provide necessary templates to pinpoint the nature of intriguing, yet unidentified EGRET gamma-ray sources. Using GeV-photons detected by CGRO EGRET and taking advantage of high spatial resolution images from H.E.S.S. observations, we were able to shed new light on the EGRET observed gamma-ray emission in the Kookaburra complex, whose previous coverage in the literature is some-what contradictory. 3EGJ1420-6038 very likely accounts for two GeV gamma-ray sources (E>1 GeV), both in positional coincidence with the recently reported pulsar wind nebulae (PWN) by HESS in the Kookaburra/Rabbit complex. PWN associations at VHE energies, supported by accumulating evidence from observations in the radio and X-ray band, are indicative for the PSR/plerionic origin of spatially coincident, but still unidentified Galactic gamma-ray sources from EGRET. This not only supports the already suggested connection between variable, but unidentified low-latitude gamma-ray sources with pulsar wind nebulae (3EGJ1420-6038 has been suggested as PWN candidate previously), it also documents the ability of resolving apparently confused EGRET sources by connecting the GeV emission as measured from a large-aperture space-based gamma-ray instrument with narrow field-of-view but superior spatial resolution observations by ground-based atmospheric Cherenkov telescopes, a very promising identification technique for achieving convincing individual source identifications in the era of GLAST-LAT.

  7. The Universe in Gamma Rays

    NASA Astrophysics Data System (ADS)

    Schönfelder, Volker

    After describing cosmic gamma-ray production and absorption, the instrumentation used in gamma-ray astronomy is explained. The main part of the book deals with astronomical results, including the somewhat surprising result that the gamma-ray sky is continuously changing.

  8. CELESTE: A large heliostat array for gamma ray astronomy

    NASA Astrophysics Data System (ADS)

    Smith, D. A.; Bergeret, H.; Cordier, A.; Dumora, D.; Eschstruth, P.; Espigat, P.; Fabre, B.; Fleury, P.; Giebels, B.; Merkel, B.; Meynadier, C.; Paré, E.; Procureur, J.; Québert, J.; Rob, L.; Roy, Ph.; Salamon, M. H.; Schovanek, P.; Vrana, J.

    1997-03-01

    Breakthroughs in high energy gamma ray astronomy both on the ground and in space since circa 1990 sparked campaigns to extend the sensitivity of the atmospheric Cherenkov detectors down to the energy range of the satellite detectors. While the Cherenkov imagers have yielded the best results near 1 TeV, we argue that wavefront sampling is better suited to begin exploration of the sub-100 GeV range. Specifically, we describe work that has been done on Celeste, a project to transform the Themis central receiver solar power plant in the French Pyrenees into a 20 GeV to 200 GeV gamma ray telescope. Celeste will complement the 200 GeV to 20 TeV instruments already running at Themis.

  9. CELESTE: A Large Heliostat Array for Gamma Ray Astronomy

    NASA Astrophysics Data System (ADS)

    Smith, D. A.; Bergeret, H.; Cordier, A.; Dumora, D.; Eschstruth, P.; Espigat, P.; Fabre, B.; Fleury, P.; Giebels, B.; Merkel, B.; Meynadier, C.; Paré, E.; Procureur, J.; Québert, J.; Rob, L.; Roy, Ph.; Salamon, M. H.; Schovanek, P.; Vrana, J.

    1997-03-01

    Breakthroughs in high energy gamma ray astronomy both on the ground and in space since circa 1990 sparked campaigns to extend the sensitivity of the atmospheric Cherenkov detectors down to the energy range of the satellite detectors. While the Cherenkov imagers have yielded the best results near 1 TeV, we argue that wavefront sampling is better suited to begin exploration of the sub-100 GeV range. Specifically, we describe work that has been done on Celeste, a project to transform the Themis central receiver solar power plant in the French Pyrenees into a 20 GeV to 200 GeV gamma ray telescope. Celeste will complement the 200 GeV to 20 TeV instruments already running at Themis.

  10. Diffusion of Cosmic-Rays and Gamma-Ray Sources

    NASA Astrophysics Data System (ADS)

    del Pozo, E. D. C.; Torres, D. F.; Rodríguez Marrero, A. Y.

    It is commonly accepted that supernova remnants (SNR) are one of the most probable scenarios of leptonic and hadronic cosmic-ray (CR) acceleration. Such energetic CR can interact with interstellar gas to produce high-energy gamma rays, which can be detected through ground-based air Cherenkov detectors and space telescopes. Here we present a theoretical model that explains the high energy phenomenology of the neighborhood SNR IC 443, as observed with the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescope and the Energetic Gamma-ray Experiment Telescope (EGRET). We interpret MAGIC J0616 + 225 as delayed TeV emission of CR diffusing from IC 443, what naturally explains the displacement between EGRET and MAGIC sources.

  11. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1994-01-01

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

  12. Technology Needs for Gamma Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2011-01-01

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

  13. Imaging Polarimeter for a Sub-MeV Gamma-Ray All-sky Survey Using an Electron-tracking Compton Camera

    NASA Astrophysics Data System (ADS)

    Komura, S.; Takada, A.; Mizumura, Y.; Miyamoto, S.; Takemura, T.; Kishimoto, T.; Kubo, H.; Kurosawa, S.; Matsuoka, Y.; Miuchi, K.; Mizumoto, T.; Nakamasu, Y.; Nakamura, K.; Oda, M.; Parker, J. D.; Sawano, T.; Sonoda, S.; Tanimori, T.; Tomono, D.; Yoshikawa, K.

    2017-04-01

    X-ray and gamma-ray polarimetry is a promising tool to study the geometry and the magnetic configuration of various celestial objects, such as binary black holes or gamma-ray bursts (GRBs). However, statistically significant polarizations have been detected in few of the brightest objects. Even though future polarimeters using X-ray telescopes are expected to observe weak persistent sources, there are no effective approaches to survey transient and serendipitous sources with a wide field of view (FoV). Here we present an electron-tracking Compton camera (ETCC) as a highly sensitive gamma-ray imaging polarimeter. The ETCC provides powerful background rejection and a high modulation factor over an FoV of up to 2π sr thanks to its excellent imaging based on a well-defined point-spread function. Importantly, we demonstrated for the first time the stability of the modulation factor under realistic conditions of off-axis incidence and huge backgrounds using the SPring-8 polarized X-ray beam. The measured modulation factor of the ETCC was 0.65 ± 0.01 at 150 keV for an off-axis incidence with an oblique angle of 30° and was not degraded compared to the 0.58 ± 0.02 at 130 keV for on-axis incidence. These measured results are consistent with the simulation results. Consequently, we found that the satellite-ETCC proposed in Tanimori et al. would provide all-sky surveys of weak persistent sources of 13 mCrab with 10% polarization for a 107 s exposure and over 20 GRBs down to a 6 × 10-6 erg cm-2 fluence and 10% polarization during a one-year observation.

  14. Gamma ray collimator

    NASA Technical Reports Server (NTRS)

    Casanova, Edgar J. (Inventor)

    1991-01-01

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

  15. Gamma ray collimator

    NASA Technical Reports Server (NTRS)

    Casanova, Edgar J. (Inventor)

    1993-01-01

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

  16. Abundances from solar-flare gamma-ray line spectroscopy

    NASA Technical Reports Server (NTRS)

    Murphy, R. J.; Ramaty, R.; Forrest, D. J.; Kozlovsky, B.

    1985-01-01

    Elemental abundances of the ambient gas at the site of gamma ray line production inthe solar atmosphere are deduced using gamma ray line observations from a solar flare. The resultant abundances are different from local galactic abundances which are thought to be similar to photospheric abundances.

  17. Supernova remnants and pulsar wind nebulae with Imaging Atmospheric Cherenkov Telescopes (IACTs)

    NASA Astrophysics Data System (ADS)

    Eger, Peter

    2015-08-01

    The observation of very-high-energy (VHE, E > 100 GeV) gamma rays is an excellent tool to study the most energetic and violent environments in the Galaxy. This energy range is only accessible with ground-based instruments such as Imaging Atmospheric Cherenkov Telescopes (IACTs) that reconstruct the energy and direction of the primary gamma ray by observing the Cherenkov light from the induced extended air showers in Earths atmosphere. The main goals of Galactic VHE gamma-ray science are the identification of individual sources of cosmic rays (CRs), such as supernova remnants (SNRs), and the study of other extreme astrophysical objects at the highest energies, such as gamma-ray binaries and pulsar wind nebulae (PWNe). One of the main challenges is the discrimination between leptonic and hadronic gamma-ray production channels. To that end, the gamma-ray signal from each individual source needs to be brought into context with the multi-wavelength environment of the astrophysical object in question, particularly with observations tracing the density of the surrounding interstellar medium, or synchrotron radiation from relativistic electrons. In this review presented at the European Cosmic Ray Symposium 2014 (ECRS2014), the most recent developments in the field of Galactic VHE gamma-ray science are highlighted, with particular emphasis on SNRs and PWNe.

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

    SciTech Connect

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

    2012-06-10

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

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

    SciTech Connect

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

    2012-04-02

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

  20. Gamma-Ray Bursts Search with HAWC

    NASA Astrophysics Data System (ADS)

    de Leon, Cederik; Salazar Ibarguen, Humberto; Villaseã+/-Or Cendejas, Luis Manuel; HAWC Collaboration

    2017-01-01

    The High Altitude Water Cherenkov (HAWC) Gamma-ray observatory is a wide field-of-view observatory sensitive to gamma rays in the 100 GeV - 100 TeV energy range, located in Mexico at an altitude of 4100 m. In the present work we present results on the search for excesses in the rates of signals from the individual photomultiplier tubes (PMTs) using the Time to Digital Converters (TDC) of HAWC. This search is based on the implementation of the Moving Average Ratio Analysis (MARA) focused on the characterization of the different physical phenomena that may give rise to such excesses: noise in the PMTs, atmospheric conditions related with thunderstorms and excesses of astrophysical origin such as variable sources of high energy gamma rays and in particular GRBs. In particular we present an analysis over the HAWC historical data for the search of such excesses and elaborate on the possible physical interpretation of the found excesses.

  1. Tycho's Star Shines in Gamma Rays

    NASA Image and Video Library

    2017-09-27

    NASA image relase December 13, 2011 Gamma-rays detected by Fermi's LAT show that the remnant of Tycho's supernova shines in the highest-energy form of light. This portrait of the shattered star includes gamma rays (magenta), X-rays (yellow, green, and blue), infrared (red) and optical data. Credit: Gamma ray, NASA/DOE/Fermi LAT Collaboration; X-ray, NASA/CXC/SAO; Infrared, NASA/JPL-Caltech; Optical, MPIA, Calar Alto, O. Krause et al. and DSS To read more go to: www.nasa.gov/mission_pages/GLAST/news/tycho-star.html NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  2. A Search for Simultaneous Optical Counterparts of Gamma-Ray Bursts (LOTIS: Livermore Optical Transient Imaging System)

    NASA Technical Reports Server (NTRS)

    Park, H.-S.

    1999-01-01

    Under this grant the UC Berkeley PI, K. Hurley, joined the LOTIS collaboration. His task was to provide precise localization data on cosmic gamma-ray bursts, so that the LOTIS automated camera data could be searched more efficiently for evidence of optical emission from gamma-ray burst sources. This was accomplished. A program is now in place which automatically sends Interplanetary Network data on bursts via e-mail to H.S. Park, for every burst detected by the GRB experiment aboard the Ulysses spacecraft (for which K. Hurley is the P.I.). The data consist either of triangulation annuli (obtained when just two spacecraft observe the burst) or error boxes (when three widely separated spacecraft observe it). These define a locus of possible burst positions. The annuli intersect the large error circles of the CGRO-BATSE experiment, and reduce their areas by a factor of approximately 25 or more. The error boxes reduce the areas by factors of several hundred. This in turn reduces the area which must be searched for an optical counterpart. No such counterparts have been observed to date by the LOTIS experiment, but several interesting upper limits have been obtained.

  3. Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.

    1992-01-01

    The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1,2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

  4. Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.

    1992-01-01

    The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1,2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

  5. A 12-bit, 1 MS/s SAR-ADC for a CZT-based multi-channel gamma-ray imager using a new digital calibration method

    NASA Astrophysics Data System (ADS)

    Liu, W.; Wei, T.; Yang, L.; Hu, Y.

    2016-03-01

    The successive approximation register-analog to digital converter (SAR-ADC) is widely used in the CdZnTe-based gamma-ray imager because of its outstanding characteristics of low power consumption, relatively high resolution, and small die size. This study proposes a digital bit-by-bit calibration method using an input ramp signal to further improve the conversion precision and power consumption of an SAR-ADC. The proposed method is based on the sub-radix-2 redundant architecture and the perturbation technique. The proposed calibration algorithm is simpler, more stable, and faster than traditional approaches. The prototype chip of the 12-bit, 1 MS/s radiation-hardened SAR-ADC has been designed and fabricated using the TSMC 0.35 μm 2P4M CMOS process. This SAR-ADC consumes 3 mW power and occupies a core area of 856× 802μm2. The digital bit-by-bit calibration algorithm is implemented via MATLAB for testing flexibility. The effective number of bits for this digitally calibrated SAR-ADC reaches 11.77 bits. The converter exhibits high conversion precision, low power consumption, and radiation-hardened design. Therefore, this SAR-ADC is suitable for multi-channel gamma-ray imager applications.

  6. First Quantitative Imaging of Organic Fluorine within Angiogenic Tissues by Particle Induced Gamma-Ray Emission (PIGE) Analysis: First PIGE Organic Fluorine Imaging

    PubMed Central

    Lavielle, Sébastien; Gionnet, Karine; Ortega, Richard; Devès, Guillaume; Kilarski, Victor; Wehbe, Katia; Bikfalvi, Andreas; Déléris, Gérard

    2011-01-01

    PET (Positron Emission Tomography) allows imaging of the in vivo distribution of biochemical compounds labeled with a radioactive tracer, mainly 18F-FDG (2-deoxy-2-[18F] fluoro-D-glucose). 18F only allows a relatively poor spatial resolution (2-3 mm) which does not allow imaging of small tumors or specific small size tissues, e.g. vasculature. Unfortunately, angiogenesis is a key process in various physiologic and pathologic processes and is, for instance, involved in modern anticancer approaches. Thus ability to visualize angiogenesis could allow early diagnosis and help to monitor the response of cancer to specific chemotherapies. Therefore, indirect analytical techniques are required to assess the localization of fluorinated compounds at a micrometric scale. Multimodality imaging approaches could provide accurate information on the metabolic activity of the target tissue. In this article, PIGE method (Particle Induced Gamma-ray Emission) was used to determine fluorinated tracers by the nuclear reaction of 19F(p,p′γ)19F in tissues. The feasibility of this approach was assessed on polyfluorinated model glucose compounds and novel peptide-based tracer designed for angiogenesis imaging. Our results describe the first mapping of the biodistribution of fluorinated compounds in both vascularized normal tissue and tumor tissue. PMID:24310427

  7. First Quantitative Imaging of Organic Fluorine within Angiogenic Tissues by Particle Induced Gamma-Ray Emission (PIGE) Analysis: First PIGE Organic Fluorine Imaging.

    PubMed

    Lavielle, Sébastien; Gionnet, Karine; Ortega, Richard; Devès, Guillaume; Kilarski, Victor; Wehbe, Katia; Bikfalvi, Andreas; Déléris, Gérard

    2011-03-09

    PET (Positron Emission Tomography) allows imaging of the in vivo distribution of biochemical compounds labeled with a radioactive tracer, mainly 18F-FDG (2-deoxy-2-[18F] fluoro-D-glucose). 18F only allows a relatively poor spatial resolution (2-3 mm) which does not allow imaging of small tumors or specific small size tissues, e.g. vasculature. Unfortunately, angiogenesis is a key process in various physiologic and pathologic processes and is, for instance, involved in modern anticancer approaches. Thus ability to visualize angiogenesis could allow early diagnosis and help to monitor the response of cancer to specific chemotherapies. Therefore, indirect analytical techniques are required to assess the localization of fluorinated compounds at a micrometric scale. Multimodality imaging approaches could provide accurate information on the metabolic activity of the target tissue. In this article, PIGE method (Particle Induced Gamma-ray Emission) was used to determine fluorinated tracers by the nuclear reaction of 19F(p,p'γ)19F in tissues. The feasibility of this approach was assessed on polyfluorinated model glucose compounds and novel peptide-based tracer designed for angiogenesis imaging. Our results describe the first mapping of the biodistribution of fluorinated compounds in both vascularized normal tissue and tumor tissue.

  8. Spectra and angular distributions of atmospheric gamma rays from 0.3 to 10 MeV at lambda = 40 deg

    NASA Technical Reports Server (NTRS)

    Ling, J. C.; Gruber, D. E.

    1977-01-01

    Measurements of the spectral and angular distributions of atmospheric gamma sq cm rays in the energy range 0.3-10 MeV over Palestine, Texas, at residual depths of 2.5 and 70 g/sq cm are reported. In confirmation of the general features of a model prediction, the measurements show at 2.5 g/sq cm upward moving fluxes greater than the downward moving fluxes, the effect increasing with energy, and approximate isotropy at 70 g/sq cm. Numerous characteristic gamma-ray lines were observed, most prominently at 0.511, 1.6, 2.3, 4.4, and 6.1 MeV. Their intensities were also compared with model predictions. Observations were made with an actively shielded scintillator counter with two detectors, one of aperture 50 deg FWHM and the other of 120 deg FWHM. Above 1 MeV, contributions to the counting rate from photons penetrating the shield annulus and from neutron interactions were large; they were studied by means of a Monte Carlo code and are extensively discussed.

  9. Spectra and angular distributions of atmospheric gamma rays from 0.3 to 10 MeV at lambda = 40 deg

    NASA Technical Reports Server (NTRS)

    Ling, J. C.; Gruber, D. E.

    1977-01-01

    Measurements of the spectral and angular distributions of atmospheric gamma sq cm rays in the energy range 0.3-10 MeV over Palestine, Texas, at residual depths of 2.5 and 70 g/sq cm are reported. In confirmation of the general features of a model prediction, the measurements show at 2.5 g/sq cm upward moving fluxes greater than the downward moving fluxes, the effect increasing with energy, and approximate isotropy at 70 g/sq cm. Numerous characteristic gamma-ray lines were observed, most prominently at 0.511, 1.6, 2.3, 4.4, and 6.1 MeV. Their intensities were also compared with model predictions. Observations were made with an actively shielded scintillator counter with two detectors, one of aperture 50 deg FWHM and the other of 120 deg FWHM. Above 1 MeV, contributions to the counting rate from photons penetrating the shield annulus and from neutron interactions were large; they were studied by means of a Monte Carlo code and are extensively discussed.

  10. Interannual similarity and variation in seasonal circulation of Mars' atmospheric Ar as seen by the Gamma Ray Spectrometer on Mars Odyssey

    NASA Astrophysics Data System (ADS)

    Sprague, Ann L.; Boynton, William V.; Forget, Francois; Lian, Yuan; Richardson, Mark; Starr, Richard; Metzger, Albert E.; Hamara, David; Economou, Thanasis

    2012-04-01

    More than 3 Mars' years (MY) of atmospheric argon (Ar) measurements are used to study annual and seasonal variations in atmospheric transport and mixing. Data are obtained over the period 20 May 2002 to 4 May 2008 by the Gamma Subsystem (GS) of the Gamma Ray Spectrometer (GRS) on the Mars Odyssey spacecraft in orbit around Mars. Here we augment previous studies of Mars' Ar in which strong seasonal variations were observed and horizontal meridional mixing coefficients for the southern hemisphere were computed. Comparison of year-to-year seasonal abundance shows strong similarity but also some short-period (˜15°-30° Ls) and interannual variations. Evidence for short periods of strong eddy transport is exhibited during autumn and winter. The seasonal change in Ar concentration for southern latitudes is relatively gradual and well defined, but seasonal changes at high northern latitudes are chaotic and indicate that atmospheric disturbance is ubiquitous. Major topographic landforms (Elysium, Tharsis, Noachis Terra, Hellas) apparently have little control over seasonal Ar concentration at the spatial resolution of the GRS data set. Some indication of local enhanced Ar concentration is present from 30°N to 60°N for the Hellas and Tharsis sectors in late winter and early spring. The data show some significant (3σ) differences between MY 26 and MY 27 in geographical sectors that are likely produced by local weather. The GS data do not show seasonal variation of Ar at equatorial and low-latitude zones, in contrast to those from the Alpha Particle X-ray Spectrometer (APXS) measurements from the Mars Exploration Rovers.

  11. Detection of 6.13 MeV gamma-rays within and at the top of the atmosphere

    NASA Technical Reports Server (NTRS)

    Willett, J. B.; Ling, J. C.; Mahoney, W. A.; Jacobson, A. S.

    1979-01-01

    A measurement of the 6.13 MeV gamma-radiation from excited O-16 in the atmosphere has been made with a high-resolution Ge(Li) spectrometer flown from Palestine, Texas, 1974 June 10, on a high-altitude balloon. This measurement, made both within and near the top of the atmosphere, is found to have the same general profile as predicted by a semiempirical model, but gives a flux about a factor of 2 higher than predicted. Certain variations in the intensity at float altitude have led to the hypothesis of an extraterrestrial source of 6.13 MeV gamma-radiation from the galactic anticenter. The 3 sigma upper limits for a number of other astrophysically significant line fluxes are also given. The data presented here are consistent with either a source or a no-source hypothesis.

  12. Cosmic gamma-ray propagation as a probe for intergalactic media and interactions

    NASA Astrophysics Data System (ADS)

    Huan, Hao

    2012-05-01

    -emission in the universe, producing electron-positron pairs. The pairs then upscatter ambient EBL and cosmic microwave background (CMB) photons to gamma rays, which are mostly high-energy (HE), i.e., between 100 MeV and 100 GeV. These secondary gamma rays could also trigger further pair production processes, resulting in an electromagnetic cascade in the cosmic voids. When there is no magnetic field present, all of the cascade gamma rays travel in virtually the same direction as the primary emissions from the source, adding to the observed gamma-ray flux. If the magnetic field in the voids is not negligible, however, the electron-positron pairs are deflected prior to inverse-Compton (IC) scattering on the background photons, impacting to the cascade photons an angular extension. The angular extension caused by the magnetic field both decreases the directly-observed source flux and creates a gamma-ray halo around the original source. An observation of the gamma-ray halo would therefore present a detection of the cosmic magnetic field, which so far has only upper limits imposed from Faraday rotation measurements of radio galaxies. On the other hand, by placing an upper limit on the HE gamma-ray flux of the source we can also derive a lower limit on the magnetic field. To address the processes involved in VHE gamma-ray propagation, I employ both semi-analytic models and full-scale Monte Carlo simulations derived from first principles. The two ways of approach give complementary perspectives on the physics involved and cross-check with each other to ensure a reliable result. By fitting the predicted cascade flux with observed data in both VHE and HE energy ranges by ground-based imaging atmospheric Cherenkov telescopes (IACTs) and the Fermi Large Area Telescope (LAT), I can place a robust lower limit on the extragalactic magnetic field (EGMF) strength at 10--16 to 10--15 Gauss, or at 10 --18 to 10--17 Gauss for a more conservative assumption on the source livetime. The lower

  13. Solving the Mystery of Short Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2006-01-01

    Gamma-ray bursts are among the most fascinating occurrences in the cosmos. Until this year, the origin of short gamma-ray bursts was a complete mystery. A new NASA satellite named Swift has now captured the first images of these events and found that they are caused by tremendous explosions in the distant universe.

  14. Detection of pulsed gamma rays above 100 GeV from the Crab pulsar.

    PubMed

    Aliu, E; Arlen, T; Aune, T; Beilicke, M; Benbow, W; Bouvier, A; Bradbury, S M; Buckley, J H; Bugaev, V; Byrum, K; Cannon, A; Cesarini, A; Christiansen, J L; Ciupik, L; Collins-Hughes, E; Connolly, M P; Cui, W; Dickherber, R; Duke, C; Errando, M; Falcone, A; Finley, J P; Finnegan, G; Fortson, L; Furniss, A; Galante, N; Gall, D; Gibbs, K; Gillanders, G H; Godambe, S; Griffin, S; Grube, J; Guenette, R; Gyuk, G; Hanna, D; Holder, J; Huan, H; Hughes, G; Hui, C M; Humensky, T B; Imran, A; Kaaret, P; Karlsson, N; Kertzman, M; Kieda, D; Krawczynski, H; Krennrich, F; Lang, M J; Lyutikov, M; Madhavan, A S; Maier, G; Majumdar, P; McArthur, S; McCann, A; McCutcheon, M; Moriarty, P; Mukherjee, R; Nuñez, P; Ong, R A; Orr, M; Otte, A N; Park, N; Perkins, J S; Pizlo, F; Pohl, M; Prokoph, H; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Roache, E; Rose, H J; Ruppel, J; Saxon, D B; Schroedter, M; Sembroski, G H; Sentürk, G D; Smith, A W; Staszak, D; Tešić, G; Theiling, M; Thibadeau, S; Tsurusaki, K; Tyler, J; Varlotta, A; Vassiliev, V V; Vincent, S; Vivier, M; Wakely, S P; Ward, J E; Weekes, T C; Weinstein, A; Weisgarber, T; Williams, D A; Zitzer, B

    2011-10-07

    We report the detection of pulsed gamma rays from the Crab pulsar at energies above 100 giga-electron volts (GeV) with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) array of atmospheric Cherenkov telescopes. The detection cannot be explained on the basis of current pulsar models. The photon spectrum of pulsed emission between 100 mega-electron volts and 400 GeV is described by a broken power law that is statistically preferred over a power law with an exponential cutoff. It is unlikely that the observation can be explained by invoking curvature radiation as the origin of the observed gamma rays above 100 GeV. Our findings require that these gamma rays be produced more than 10 stellar radii from the neutron star.

  15. Can Astrophysical Gamma Ray Sources Mimic Dark Matter Annihilation in Galactic Satellites?

    SciTech Connect

    Baltz, Edward A.; Taylor, James E.; Wai, Lawrence L.; /KIPAC, Menlo Park

    2006-11-01

    The nature of the cosmic dark matter is unknown. The most compelling hypothesis is that dark matter consists of weakly interacting massive particles (WIMPs) in the 100 GeV mass range. Such particles would annihilate in the galactic halo, producing high-energy gamma rays which might be detectable in gamma ray telescopes such as the GLAST satellite. We investigate the ability of GLAST to distinguish between the WIMP annihilation spectrum and the spectrum of known astrophysical source classes. Focusing on the emission from the galactic satellite halos predicted by the cold dark matter model, we find that the WIMP gamma-ray spectrum is unique; the separation from known source classes can be done in a convincing way. We discuss the follow-up of possible WIMP sources with Imaging Atmospheric Cerenkov Telescopes. Finally we discuss the impact that Large Hadron Collider data might have on the study of galactic dark matter.

  16. Modeling of Pulses in Terrestrial Gamma-ray Flashes

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Celestin, Sebastien; Pasko, Victor

    2015-04-01

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

  17. Gamma-ray Astrophysics with AGILE

    SciTech Connect

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

    2007-07-12

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

  18. Gamma-Ray Telescope and Uncertainty Principle

    ERIC Educational Resources Information Center

    Shivalingaswamy, T.; Kagali, B. A.

    2012-01-01

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

  19. Analysis of atmospheric gamma-ray flashes detected in near space with allowance for the transport of photons in the atmosphere

    SciTech Connect

    Babich, L. P. Donskoy, E. N.; Kutsyk, I. M.

    2008-07-15

    Monte Carlo simulations of transport of the bremsstrahlung produced by relativistic runaway electron avalanches are performed for altitudes up to the orbit altitudes where terrestrial gamma-ray flashes (TGFs) have been detected aboard satellites. The photon flux per runaway electron and angular distribution of photons on a hemisphere of radius similar to that of the satellite orbits are calculated as functions of the source altitude z. The calculations yield general results, which are recommended for use in TGF data analysis. The altitude z and polar angle are determined for which the calculated bremsstrahlung spectra and mean photon energies agree with TGF measurements. The correlation of TGFs with variations of the vertical dipole moment of a thundercloud is analyzed. We show that, in agreement with observations, the detected TGFs can be produced in the fields of thunderclouds with charges much smaller than 100 C and that TGFs are not necessarily correlated with the occurrence of blue jets and red sprites.

  20. Open high-level data formats and software for gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Deil, Christoph; Boisson, Catherine; Kosack, Karl; Perkins, Jeremy; King, Johannes; Eger, Peter; Mayer, Michael; Wood, Matthew; Zabalza, Victor; Knödlseder, Jürgen; Hassan, Tarek; Mohrmann, Lars; Ziegler, Alexander; Khelifi, Bruno; Dorner, Daniela; Maier, Gernot; Pedaletti, Giovanna; Rosado, Jaime; Contreras, José Luis; Lefaucheur, Julien; Brügge, Kai; Servillat, Mathieu; Terrier, Régis; Walter, Roland; Lombardi, Saverio

    2017-01-01

    In gamma-ray astronomy, a variety of data formats and proprietary software have been traditionally used, often developed for one specific mission or experiment. Especially for ground-based imaging atmospheric Cherenkov telescopes (IACTs), data and software are mostly private to the collaborations operating the telescopes. However, there is a general movement in science towards the use of open data and software. In addition, the next-generation IACT instrument, the Cherenkov Telescope Array (CTA), will be operated as an open observatory. We have created a Github organisation at https://github.com/open-gamma-ray-astro where we are developing high-level data format specifications. A public mailing list was set up at https://lists.nasa.gov/mailman/listinfo/open-gamma-ray-astro and a first face-to-face meeting on the IACT high-level data model and formats took place in April 2016 in Meudon (France). This open multi-mission effort will help to accelerate the development of open data formats and open-source software for gamma-ray astronomy, leading to synergies in the development of analysis codes and eventually better scientific results (reproducible, multi-mission). This write-up presents this effort for the first time, explaining the motivation and context, the available resources and process we use, as well as the status and planned next steps for the data format specifications. We hope that it will stimulate feedback and future contributions from the gamma-ray astronomy community.

  1. Gamma-ray burst and spectroscopy instrumentation development at the Goddard Space Flight Center

    NASA Technical Reports Server (NTRS)

    Teegarden, B. J.

    1986-01-01

    This paper summarizes the activities that are specifically related to the development of instrumentation for gamma-ray astronomy. Three programs are described: (1) the Gamma-Ray Imaging Spectrometer (GRIS), a balloon-borne array of seven germanium detectors for high-resolution spectrographic studies of persistent gamma-ray sources; (2) the Transient Gamma-Ray Spectrometer (TGRS), a single radiatively-cooled germanium detector for the spectrographic study of gamma-ray bursts, and (3) the Rapidly Moving Telescope (RMT), a ground-based optical telescope for the detection and study of short-lived optical transients, particularly those that occur in coincidence with gamma-ray bursts.

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

    SciTech Connect

    Masarik, J.; Reedy, R.C.

    1994-07-01

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

  3. INTEGRAL: International Gamma Ray Astrophysics Laboratory

    NASA Astrophysics Data System (ADS)

    Winkler, Christoph

    1992-07-01

    INTEGRAL is dedicated to the fine spectroscopy and imaging of celestial gamma ray sources in the energy range 15 keV to 10 MeV. The instruments on INTEGRAL will achieve a gamma ray line sensitivity of 3 times 10 to the minus 6th power ph/sq cm/s, a continuum sensitivity of 3 times 10 to the minus 8th power ph/sq cm/s/keV at 1 MeV (approximately 10 mCrab at 1 MeV) and imaging with an angular resolution of better than 20 minutes. This represents an order of magnitude improvement over the Gamma Ray Observatory (GRO) in line sensitivity, energy resolution and angular resolution. Comparison with the low energy gamma ray telescope Sigma also shows a major advance: the continuum sensitivity improvement is considerably more than one order of magnitude between 100 keV and 1 MeV; and the narrow line sensitivity is increased by nearly two orders of magnitude. INTEGRAL consists of two main instruments: a germanium spectrometer and a caesium iodide coded aperture mask imager. These instruments are supplemented by two monitors: an X-ray monitor and an optical transient camera.

  4. COMBINED MEASUREMENTS WITH THREE-DIMENSIONAL DESIGN INFORMATION VERIFICATION SYSTEM AND GAMMA RAY IMAGING - A COLLABORATIVE EFFORT BETWEEN OAK RIDGE NATIONAL LABORATORY, LAWRENCE LIVERMORE NATIONAL LABORATORY, AND THE JOINT RESEARCH CENTER AT ISPRA

    SciTech Connect

    Mihailescu, L; Vetter, K; Ruhter, W; Chivers, D; Dreicer, M; Coates, C; Smith, S; Hines, J; Caiado, A R; Sequeira, V; Fiocco, M; Goncalves, J G

    2006-06-14

    Oak Ridge National Laboratory (ORNL) and Lawrence Livermore National Laboratory (LLNL) have jointly performed tests to demonstrate combined measurements with a three-dimensional (3D) design information verification (DIV) system and a gamma-ray imager for potential safeguard applications. The 3D DIV system was made available by the European Commission's Joint Research Center to ORNL under a collaborative project between the U.S. Department of Energy and the European Atomic Energy Community (EURATOM). The system is able to create 3D maps of rooms and objects and of identifying changes in positions and modifications with a precision on the order of millimeters. The gamma ray imaging system consists of a 4{pi} field-of-view Compton imaging system which has two fully operational DSSD (Double-Sided Segment Detector) High-Purity Germanium (HPGe) detectors developed at LLNL. The Compton imaging instrument not only provides imaging capabilities, but provides excellent energy resolution which enables the identification of radioisotopes and nuclear materials. Joint Research Center was responsible to merge gamma-ray images with the 3D range maps. The results of preliminary first measurements performed at LLNL demonstrate, for the first time, mapping of panoramic gamma-ray images into 3D range data.

  5. Gamma Ray Bursts - Observations

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Cannizzo, J. K.

    2010-01-01

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

  6. Gamma-ray astronomy: From Fermi up to the HAWC high-energy {gamma}-ray observatory in Sierra Negra

    SciTech Connect

    Carraminana, Alberto; Collaboration: HAWC Collaboration

    2013-06-12

    Gamma-rays represent the most energetic electromagnetic window for the study of the Universe. They are studied both from space at MeV and GeV energies, with instruments like the Fermi{gamma}-ray Space Telescope, and at TeV energies with ground based instruments profiting of particle cascades in the atmosphere and of the Cerenkov radiation of charged particles in the air or in water. The Milagro gamma-ray observatory represented the first instrument to successfully implement the water Cerenkov technique for {gamma}-ray astronomy, opening the ground for the more sensitive HAWC {gamma}-ray observatory, currently under development in the Sierra Negra site and already providing early science results.

  7. Gamma-ray line astrophysics

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.; Ramaty, R.

    1986-01-01

    Recent observations of gamma-ray line emission from solar flares, gamma-ray bursts, the galactic center, the interstellar medium and the jets of SS433 are reviewed. The implications of these observations on high energy processes in these sources are discussed.

  8. The Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Chipman, E.; Kniffen, D.

    1994-01-01

    The Arthur Holly Compton Gamma Ray Observatory Compton) is the second in NASA's series of great Observatories. Launched on 1991 April 5, Compton represents a dramatic increase in capability over previous gamma-ray missions. The spacecraft and scientific instruments are all in good health, and many significant discoveries have already been made. We describe the capabilities of the four scientific instruments, and the observing program of the first 2 years of the mission. Examples of early discoveries by Compton are enumerated, including the discovery that gamma-ray bursts are isotropic but spatially inhomogeneous in their distribution; the discovery of a new class of high-energy extragalacatic gamma-ray sources, the gamma-ray AGNs; the discovery of emission from SN 1987A in the nuclear line of Co-57; and the mapping of emission from Al-26 in the interstellar medium (ISM) near the Galactic center. Future observations will include deep surveys of selected regions of the sky, long-tem studies of individual objects, correlative studies of objects at gamma-ray and other energies, a Galactic plane survey at intermediate gamma-ray energies, and improved statistics on gamma-ray bursts to search for small anisotropies. After completion of the all-sky survey, a Guest Investigator program is in progress with guest observers' time share increasing from 30% upward for the late mission phases.

  9. The Compton Gamma Ray Observatory

    NASA Astrophysics Data System (ADS)

    Gehrels, N.; Chipman, E.; Kniffen, D.

    1994-06-01

    The Arthur Holly Compton Gamma Ray Observatory Compton) is the second in NASA's series of great Observatories. Launched on 1991 April 5, Compton represents a dramatic increase in capability over previous gamma-ray missions. The spacecraft and scientific instruments are all in good health, and many significant discoveries have already been made. We describe the capabilities of the four scientific instruments, and the observing program of the first 2 years of the mission. Examples of early discoveries by Compton are enumerated, including the discovery that gamma-ray bursts are isotropic but spatially inhomogeneous in their distribution; the discovery of a new class of high-energy extragalacatic gamma-ray sources, the gamma-ray AGNs; the discovery of emission from SN 1987A in the nuclear line of Co-57; and the mapping of emission from Al-26 in the interstellar medium (ISM) near the Galactic center. Future observations will include deep surveys of selected regions of the sky, long-tem studies of individual objects, correlative studies of objects at gamma-ray and other energies, a Galactic plane survey at intermediate gamma-ray energies, and improved statistics on gamma-ray bursts to search for small anisotropies. After completion of the all-sky survey, a Guest Investigator program is in progress with guest observers' time share increasing from 30% upward for the late mission phases.

  10. Gamma-ray burst observations

    NASA Technical Reports Server (NTRS)

    Atteia, J.-L.

    1993-01-01

    The most important observational characteristics of gamma-ray bursts are reviewed, with emphasis on X-ray and gamma-ray data. The observations are used to derive some basic properties of the sources. The sources are found to be isotropically distributed; the burster population is limited in space, and the edge of the distribution is visible.

  11. A High Resolution Liquid Xenon Imaging Telescope for 0.3-10 MeV Gamma Ray Astrophysics: Construction and Initial Balloon Flights

    NASA Technical Reports Server (NTRS)

    Aprile, Elena

    1993-01-01

    The results achieved with a 3.5 liter liquid xenon time projection chamber (LXe-TPC) prototype during the first year include: the efficiency of detecting the primary scintillation light for event triggering has been measured to be higher than 85%; the charge response has been measured to be stable to within 0.1% for a period of time of about 30 hours; the electron lifetime has been measured to be in excess of 1.3 ms; the energy resolution has been measured to be consistent with previous results obtained with small volume chambers; X-Y gamma ray imaging has been demonstrated with a nondestructive orthogonal wires readout; Monte Carlo simulation results on detection efficiency, expected background count rate at balloon altitude, background reduction algorithms, telescope response to point-like and diffuse sources, and polarization sensitivity calculations; and work on a 10 liter LXe-TPC prototype and gas purification/recovery system.

  12. Gamma-ray Emission from Globular Clusters

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  13. Gamma Ray Pulsars: Multiwavelength Observations

    NASA Technical Reports Server (NTRS)

    Thompson, David J.

    2004-01-01

    High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The seven or more pulsars seen by instruments on the Compton Gamma Ray Observatory (CGRO) show that: the light curves usually have double-peak structures (suggesting a broad cone of emission); gamma rays are frequently the dominant component of the radiated power; and all the spectra show evidence of a high-energy turnover. For all the known gamma-ray pulsars, multiwavelength observations and theoretical models based on such observations offer the prospect of gaining a broad understanding of these rotating neutron stars. The Gamma-ray Large Area Space Telescope (GLAST), now in planning for a launch in 2006, will provide a major advance in sensitivity, energy range, and sky coverage.

  14. Very high energy gamma-ray emission from Tycho's supernova remnant

    NASA Astrophysics Data System (ADS)

    Saxon, Dana Boltuch

    Supernova remnant (SNR) G120.1+1.4 (also known as Tycho's SNR) is the remnant of one of only five confirmed historical supernovae. As such, it has been well studied across the electromagnetic spectrum. This thesis describes the first statistically significant detection of very high energy (VHE) (˜ 100 GeV to 100 TeV) gamma rays from Tycho's SNR, reported in 2011 by the VERITAS collaboration. The analysis that led to that detection was performed by this author, and this dissertation will discuss the process in detail. Subsequently, a statistically significant detection in high energy (HE) (˜ 30 MeV to 100 GeV) gamma rays was reported by other authors using data from the Fermi Gamma-Ray Space Telescope. Comparison of models to the spectral energy distribution of the photon flux from this remnant in HE and VHE gamma rays favors a hadronic origin for the emission, particularly when combined with current X-ray data, although a leptonic origin cannot be ruled out at this time. This is significant because a confirmed hadronic origin for the gamma-ray emission would identify this SNR as a site of cosmic ray acceleration, providing observational evidence for the idea that SNRs are the source of the Galactic cosmic ray population. Chapter 1 of this dissertation will provide historical background on Tycho's SNR, along with a summary of modern observations of the remnant across the electromagnetic spectrum. Chapter 2 is a discussion of the role played by SNRs in the process of cosmic ray acceleration, including both theoretical underpinnings and observational evidence. Chapter 3 provides an overview of the field of VHE gamma-ray astronomy, with discussions of gamma-ray production mechanisms and gamma-ray source classes. Chapter 4 describes the instruments used to observe HE and VHE gamma rays. Chapter 5 is a discussion of general analysis methods and techniques for data from Imaging Atmospheric Cherenkov Telescopes (IACTs). Chapter 6 provides details about the specific

  15. Development of the instruments for the Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Madden, J. J.; Kniffen, D. A.

    1986-01-01

    The Gamma Ray Observatory (GRO) is to be launched in 1988 by the STS. The GRO will feature four very large instruments: the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), the Energetic Gamma Ray Experiment Telescope (EGRET) and the Burst and Transient Source Experiment (BATSE). The instruments weigh from 900-1200 kg each, and required the development of specialized lifting and dolly devices to permit their assembly, manipulation and testing. The GRO is intended a{s a tool for studying discrete celestial objects such as black holes, neutron stars and other gamma-ray emitting objects, scanning for nucleosynthesis processes, mapping the Galaxy and other, high energy galaxies in terms of gamma rays, searching for cosmological effects and observing gamma ray bursts. The instruments will be sensitive from the upper end mof X-rya wavelengths to the highest energies possible. Details of the hardware and performance specifications of each of the instruments are discussed.

  16. Accelerated and Ambient Abundances in RHESSI Gamma-Ray Flares

    NASA Astrophysics Data System (ADS)

    Smith, D. M.; Shih, A. Y.; Lin, R. P.; Share, G. H.; Murphy, R. J.; Schwartz, R. A.; Tolbert, A. K.

    2005-05-01

    The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) has detected nuclear gamma-ray line emission from at least eleven solar flares over the past three years. These gamma-ray lines are produced when flare-accelerated ions collide with the ambient solar medium. In this paper, we use gamma-ray line ratios and Doppler profiles to constrain the relative fluxes of accelerated protons, alphas, and heavier nuclei in the brighter RHESSI gamma-ray flares. We also study the relative fluxes of narrow lines to compare our conclusions about ambient solar abundances in the interaction region to earlier work from the Solar Maximum Mission Gamma-Ray Spectrometer. The work at the University of California was supported by NASA contract NAS 5-98033.

  17. Development of the instruments for the Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Madden, J. J.; Kniffen, D. A.

    1986-01-01

    The Gamma Ray Observatory (GRO) is to be launched in 1988 by the STS. The GRO will feature four very large instruments: the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), the Energetic Gamma Ray Experiment Telescope (EGRET) and the Burst and Transient Source Experiment (BATSE). The instruments weigh from 900-1200 kg each, and required the development of specialized lifting and dolly devices to permit their assembly, manipulation and testing. The GRO is intended a{s a tool for studying discrete celestial objects such as black holes, neutron stars and other gamma-ray emitting objects, scanning for nucleosynthesis processes, mapping the Galaxy and other, high energy galaxies in terms of gamma rays, searching for cosmological effects and observing gamma ray bursts. The instruments will be sensitive from the upper end mof X-rya wavelengths to the highest energies possible. Details of the hardware and performance specifications of each of the instruments are discussed.

  18. Development of the instruments for the Gamma Ray Observatory

    NASA Astrophysics Data System (ADS)

    Madden, J. J.; Kniffen, D. A.

    1986-01-01

    The Gamma Ray Observatory (GRO) is to be launched in 1988 by the STS. The GRO will feature four very large instruments: the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), the Energetic Gamma Ray Experiment Telescope (EGRET) and the Burst and Transient Source Experiment (BATSE). The instruments weigh from 900-1200 kg each, and required the development of specialized lifting and dolly devices to permit their assembly, manipulation and testing. The GRO is intended as a tool for studying discrete celestial objects such as black holes, neutron stars and other gamma-ray emitting objects, scanning for nucleosynthesis processes, mapping the Galaxy and other, high energy galaxies in terms of gamma rays, searching for cosmological effects and observing gamma ray bursts. The instruments will be sensitive from the upper end mof X-rya wavelengths to the highest energies possible. Details of the hardware and performance specifications of each of the instruments are discussed.

  19. Mobile, hybrid Compton/coded aperture imaging for detection, identification and localization of gamma-ray sources at stand-off distances

    NASA Astrophysics Data System (ADS)

    Tornga, Shawn R.

    The Stand-off Radiation Detection System (SORDS) program is an Advanced Technology Demonstration (ATD) project through the Department of Homeland Security's Domestic Nuclear Detection Office (DNDO) with the goal of detection, identification and localization of weak radiological sources in the presence of large dynamic backgrounds. The Raytheon-SORDS Tri-Modal Imager (TMI) is a mobile truck-based, hybrid gamma-ray imaging system able to quickly detect, identify and localize, radiation sources at standoff distances through improved sensitivity while minimizing the false alarm rate. Reconstruction of gamma-ray sources is performed using a combination of two imaging modalities; coded aperture and Compton scatter imaging. The TMI consists of 35 sodium iodide (NaI) crystals 5x5x2 in3 each, arranged in a random coded aperture mask array (CA), followed by 30 position sensitive NaI bars each 24x2.5x3 in3 called the detection array (DA). The CA array acts as both a coded aperture mask and scattering detector for Compton events. The large-area DA array acts as a collection detector for both Compton scattered events and coded aperture events. In this thesis, developed coded aperture, Compton and hybrid imaging algorithms will be described along with their performance. It will be shown that multiple imaging modalities can be fused to improve detection sensitivity over a broader energy range than either alone. Since the TMI is a moving system, peripheral data, such as a Global Positioning System (GPS) and Inertial Navigation System (INS) must also be incorporated. A method of adapting static imaging algorithms to a moving platform has been developed. Also, algorithms were developed in parallel with detector hardware, through the use of extensive simulations performed with the Geometry and Tracking Toolkit v4 (GEANT4). Simulations have been well validated against measured data. Results of image reconstruction algorithms at various speeds and distances will be presented as well as

  20. Investigation of Martian H2O and CO2 via orbital gamma ray spectroscopy

    NASA Technical Reports Server (NTRS)

    Evans, Larry G.; Squyres, Steven W.

    1987-01-01

    The capability of an orbital gamma ray spectrometer to address presently unanswered questions concerning H2O and CO2 on Mars is investigated. The gamma ray signal produced by the Martian atmosphere and by several simple models of Martian surface materials is calculated. Results are reported for: (1) the production of neutrons in the atmosphere and in the subsurface material by cosmic ray interactions, (2) the scattering of neutrons and the resultant neutron energy spectrum and spatial distributions, (3) the reproduction of gamma rays by neutron prompt capture and nonelastic scatter reactions, (4) the production of gamma rays by natural radionuclides, (5) the attenuation of the gamma ray signal by passage through surface materials and the Martian atmosphere, (6) the production of the gamma ray continuum background, and (7) the uncertainty in gamma ray line strengths that results from the combined signal and background observed by the detector.

  1. Investigation of Martian H2O and CO2 via orbital gamma ray spectroscopy

    NASA Technical Reports Server (NTRS)

    Evans, Larry G.; Squyres, Steven W.

    1987-01-01

    The capability of an orbital gamma ray spectrometer to address presently unanswered questions concerning H2O and CO2 on Mars is investigated. The gamma ray signal produced by the Martian atmosphere and by several simple models of Martian surface materials is calculated. Results are reported for: (1) the production of neutrons in the atmosphere and in the subsurface material by cosmic ray interactions, (2) the scattering of neutrons and the resultant neutron energy spectrum and spatial distributions, (3) the reproduction of gamma rays by neutron prompt capture and nonelastic scatter reactions, (4) the production of gamma rays by natural radionuclides, (5) the attenuation of the gamma ray signal by passage through surface materials and the Martian atmosphere, (6) the production of the gamma ray continuum background, and (7) the uncertainty in gamma ray line strengths that results from the combined signal and background observed by the detector.

  2. Searching for gamma-ray counterpart of gravitational wave transients

    NASA Astrophysics Data System (ADS)

    Sol, H.

    2016-12-01

    With the recent direct detection of gravitational waves (GW), the search for electromagnetic counterpart of gravitational transients appears as a new challenge for astronomers. Information provided by electromagnetic data is complementary to the one deduced from the gravitational signal. Detecting the same event through the two messengers would be highly interesting to better identify the sources and refine their parameters. The scarcity of cosmic sources detected at very high energy (VHE) suggests that the gamma-ray domain could be useful to catch first electromagnetic signatures and reduce error boxes. Present IACT (Imaging Atmospheric Cherenkov Telescopes) like the High Energy Stereoscopic System (H.E.S.S.) operating in Namibia, the Major Atmospheric Gamma Imaging Cherenkov Telescopes (MAGIC) in the Canary Islands and the Very Energetic Radiation Imaging Telescope Array System (VERITAS) in the USA are already participating in the electromagnetic follow up of LIGO-Virgo gravitational wave event candidates. In the next decade the Cherenkov Telescope Array (CTA), operating with a larger field of view, a higher sensitivity in the VHE gamma-ray range between 20 GeV and 300 TeV, and a fast re-positionning, will be perfectly adapted to this observational program.

  3. Ammonia excitation imaging of shocked gas towards the W28 gamma-ray source HESS J1801-233

    NASA Astrophysics Data System (ADS)

    Maxted, Nigel I.; de Wilt, Phoebe; Rowell, Gavin P.; Nicholas, Brent P.; Burton, Michael. G.; Walsh, Andrew; Fukui, Yasuo; Kawamura, Akiko

    2016-10-01

    We present 12 mm Mopra observations of the dense (>103 cm-3) molecular gas towards the north-east of the W28 supernova remnant (SNR). This cloud is spatially well matched to the TeV gamma-ray source HESS J1801-233 and is known to be an SNR-molecular cloud interaction region. Shock-disruption is evident from broad NH3 (1,1) spectral linewidths in regions towards the W28 SNR, while strong detections of spatially extended NH3 (3,3), NH3(4,4) and NH3(6,6) inversion emission towards the cloud strengthen the case for the existence of high temperatures within the cloud. Velocity dispersion measurements and NH3(n,n)/(1,1) ratio maps, where n = 2, 3, 4 and 6, indicate that the source of disruption is from the side of the cloud nearest to the W28 SNR, suggesting that it is the source of cloud-disruption. Towards part of the cloud, the ratio of ortho to para-NH3 is observed to exceed 2, suggesting gas-phase NH3 enrichment due to NH3 liberation from dust-grain mantles. The measured NH3 abundance with respect to H2 is ˜(1.2 ± 0.5) × 10-9, which is not high, as might be expected for a hot, dense molecular cloud enriched by sublimated grain-surface molecules. The results are suggestive of NH3 sublimation and destruction in this molecular cloud, which is likely to be interacting with the W28 SNR shock.

  4. Gamma-ray transfer and energy deposition in supernovae

    NASA Technical Reports Server (NTRS)

    Swartz, Douglas A.; Sutherland, Peter G.; Harkness, Robert P.

    1995-01-01

    Solutions to the energy-independent (gray) radiative transfer equations are compared to results of Monte Carlo simulations of the Ni-56 and Co-56 decay gamma-ray energy deposition in supernovae. The comparison shows that an effective, purely absorptive, gray opacity, kappa(sub gamma) approximately (0. 06 +/- 0.01)Y(sub e) sq cm/g, where Y is the total number of electrons per baryon, accurately describes the interaction of gamma-rays with the cool supernova gas and the local gamma-ray energy deposition within the gas. The nature of the gamma-ray interaction process (dominated by Compton scattering in the relativistic regime) creates a weak dependence of kappa(sub gamma) on the optical thickness of the (spherically symmetric) supernova atmosphere: The maximum value of kappa(sub gamma) applies during optically thick conditions when individual gamma-rays undergo multiple scattering encounters and the lower bound is reached at the phase characterized by a total Thomson optical depth to the center of the atmosphere tau(sub e) approximately less than 1. Gamma-ray deposition for Type Ia supernova models to within 10% for the epoch from maximum light to t = 1200 days. Our results quantitatively confirm that the quick and efficient solution to the gray transfer problem provides an accurate representation of gamma-ray energy deposition for a broad range of supernova conditions.

  5. High energy gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Fichtel, Carl E.

    1987-01-01

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

  6. The LXeCAT instrument for gamma-ray astrophysics

    NASA Technical Reports Server (NTRS)

    Aprile, E.; Xu, F.; Zhou, M.; Doke, T.; Kikuchi, J.; Masuda, K.; Chupp, E. L.; Dunphy, P. P.; Fishman, G.; Pendelton, G.

    1995-01-01

    The Liquid Xenon Coded Aperture Telescope (LXeCAT) and its capability to image astrophysical gamma-ray sources in the MeV region is described. The gamma-ray detector is a Liquid Xenon Time Projection Chamber (LXeTPC) triggered by the primary scintillation light. Effective background rejection is a direct consequence of the intrinsic three-dimensional imaging capability of the LXeTPC. Initial results with a 10 liter prototype confirm an energy resolution of 6% FWHM, a position resolution of 1 mm RMS and a light triggering efficiency higher than 90% for 1 MeV gamma-rays.

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

    NASA Technical Reports Server (NTRS)

    Ryan, James M.; Lockwood, John A.

    1989-01-01

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

  8. WE-EF-303-07: Imaging of Prompt Gamma Rays Emitted During Delivery of Clinical Proton Beams with a Compton Camera: Feasibility Studies for Range Verification

    SciTech Connect

    Polf, J; Avery, S; Mackin, D; Beddar, S

    2015-06-15

    Purpose: Evaluation of a prototype Compton camera (CC) for imaging prompt gamma rays (PG) emitted during clinical proton beam irradiation for in vivo beam range verification. Methods: We irradiated a water phantom with 114 MeV and 150 MeV proton pencil beams at clinical beam currents ranging from 1 nA up to 5 nA. The CC was placed 15 cm from the beam central axis and PGs from 0.2 MeV up to 6.5 MeV were measured during irradiation. From the measured data, 2-dimensional (2D) PG images were reconstructed. One-dimensional (1D) profiles from the PG images were compared to measured depth dose curves. Results: The CC was able to measure PG emission during delivery of both a single 150 MeV pencil beam and a 5 cm x 5 cm mono-energetic layer of 114 MeV pencil beams. From the 2D images, a strong correlation was seen between the depth of the distal falloff of PG emission and the Bragg peak (BP). 1D profiles extracted from the PG images show that the distal 60% falloff of the PG emission lined up well with the distal 90% of the BP. Shifts as small as 3 mm in the beam range could be detected on both the 2D PG images and 1D profiles with an uncertainty of 1.5 mm. With the current CC prototype, a minimum dose delivery of 400 cGy was required to produce usable PG images. Conclusions: It was possible to measure and image PG emission with our prototype CC during proton beam delivery and to detect shifts in the BP range in the images. Therefore prompt gamma imaging with a CC for the purpose of in vivo range verification is feasible. However, for the studied system improvements in detector efficiency and reconstruction algorithms are necessary to make it clinically viable.

  9. Gamma-Ray Observatory - The next great observatory in space

    NASA Technical Reports Server (NTRS)

    Neal, Valerie; Fishman, Gerald; Kniffen, Donald

    1990-01-01

    The Gamma-Ray Observatory (GRO) which is part of NASA's Great Observatories space program is presented. The GRO is equipped with the Burst and Transient Source Experiment (which detects low-energy gamma-ray photons from 20 keV to 600 keV and locates sources of gamma-ray bursts), the Oriented Scintillation Spectrometer Experiment (which detects celestial gamma rays from 100 keV to 10 MeV and identifies the elements producing these rays by measuring the ray's spectra and time variability), the Imaging Compton Telescope (which images gamma rays with energies from 1 to 30 MeV created when cosmic rays interact with interstellar matter), and the Energetic Gamma-Ray Experiment Telescope (which detects high-energy photons associated with the most energetic processes occurring in nature). After the energies of photons from each source are classified, the gamma-ray mechanisms can be modelled. Nuclei, radioactive isotopes, and nuclear reactions can be identified, and the physical conditions at the radiation's source can also be modelled. From these models, theories can be developed about the creation of elements in the explosion and collapse of giant stars, the acceleration of charged particles to velocities approaching the speed of light, and the destruction of matter and antimatter.

  10. Gamma-Ray Observatory - The next great observatory in space

    SciTech Connect

    Neal, V.; Fishman, G.; Kniffen, D. Essex Corp., Huntsville, AL NASA, Marshall Space Flight Center, Huntsville, AL NASA, Goddard Space Flight Center, Greenbelt, MD )

    1990-08-01

    The Gamma-Ray Observatory (GRO) which is part of NASA's Great Observatories space program is presented. The GRO is equipped with the Burst and Transient Source Experiment (which detects low-energy gamma-ray photons from 20 keV to 600 keV and locates sources of gamma-ray bursts), the Oriented Scintillation Spectrometer Experiment (which detects celestial gamma rays from 100 keV to 10 MeV and identifies the elements producing these rays by measuring the ray's spectra and time variability), the Imaging Compton Telescope (which images gamma rays with energies from 1 to 30 MeV created when cosmic rays interact with interstellar matter), and the Energetic Gamma-Ray Experiment Telescope (which detects high-energy photons associated with the most energetic processes occurring in nature). After the energies of photons from each source are classified, the gamma-ray mechanisms can be modelled. Nuclei, radioactive isotopes, and nuclear reactions can be identified, and the physical conditions at the radiation's source can also be modelled. From these models, theories can be developed about the creation of elements in the explosion and collapse of giant stars, the acceleration of charged particles to velocities approaching the speed of light, and the destruction of matter and antimatter.

  11. Jet Shockwaves Produce Gamma Rays

    NASA Image and Video Library

    Theorists believe that GRB jets produce gamma rays by two processes involving shock waves. Shells of material within the jet move at different speeds and collide, generating internal shock waves th...

  12. Gamma-ray-selected AGN

    NASA Astrophysics Data System (ADS)

    Giommi, Paolo

    2016-08-01

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

  13. NDA via gamma-ray active and passive computed tomography

    SciTech Connect

    Decman, D.J.; Martz, H.E.; Roberson, G.P.; Johansson, E.

    1996-10-01

    Gamma-ray-based computed tomography (CT) requires that two different measurements be made on a closed waste container. [MAR92 and ROB94] When the results from these two measurements are combined, it becomes possible to identify and quantify all detectable gamma-ray emitting radioisotopes within a container. All measurements are made in a tomographic manner, i.e., the container is moved sequentially through well- known and accurately reproducible translation, rotation, and elevation positions in order to obtain gamma-ray data that is reconstructed by computer into images that represent waste contents. [ROB94] The two measurements modes are called active (A) and passive (P) CT. In the ACT mode, a collimated gamma-ray source external to the waste container emits multiple, mono-energetic gamma rays that pass through the container and are detected on the opposite side. The attenuated gamma-rays transmitted are measured as a function of both energy and position of the container. Thus, container contents are `mapped` via the measured amount of attenuation suffered at each gamma-ray energy. In effect, a three dimensional (3D) image of gamma- ray attenuation versus waste content is obtained. In the PCT measurement mode, the external radioactive source is shuttered turned- off, and the waste container, is moved through similar positions used for the ACT measurements. However, this time the radiation detectors record any gamma-rays emitted by radioactive sources on the inside of the waste container. Thus, internal radioactive content is mapped or 3D-imaged in the same tomographic manner as the attenuating matrix materials were in the ACT measurement mode.

  14. Can Gamma Ray Bursts be Detected Using Infrasound

    NASA Astrophysics Data System (ADS)

    Palmer, Jahi; McGruder, C.; Hetzer, C.

    2010-01-01

    CAN GAMMA RAY BURST BE DETECTED USING INFRASOUND Infrasound has been used to detect sonic disturbances in earth's atmosphere caused by terrestrial events such as earthquakes and lightning. It may be possible to detect celestial events such as Gamma Ray Bursts (GRB's) through this method. We have searched for GRB's which are known to have caused ionospheric disturbances in infrasonic data. None of the selected GRB's were found to be associated with infrasonic disturbances.

  15. Directional detector of gamma rays

    DOEpatents

    Cox, Samson A.; Levert, Francis E.

    1979-01-01

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

  16. Positronium Annihilation Gamma Ray Laser

    DTIC Science & Technology

    2009-07-01

    estimate of the ignition threshold for DT fuel heated by a burst from an annihilation gamma ray laser; and (IV) A new concept for more rapid laser...distribution; (III) A theoretical estimate of the ignition threshold for DT fuel heated by a burst from an annihilation gamma ray laser; and (IV) A new ...II. Development of Laser systems 26 III. Preliminary estimate of DT ignition 31 IV. New method for cooling positronium 34 CONCLUSIONS

  17. About cosmic gamma ray lines

    NASA Astrophysics Data System (ADS)

    Diehl, Roland

    2017-06-01

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

  18. The gamma ray north-south effect

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  19. Gamma Rays from Martian Dust Storms

    NASA Astrophysics Data System (ADS)

    Arabshahi, Shahab; Majid, Walid; Dwyer, Joseph; Rassoul, Hamid

    2017-04-01

    Martian dust storms are suggested to be able to generate electric fields close to the breakdown values for Mars' atmosphere, i.e. 25 kV/m [Farrel et al. 2006]. Such electric fields could initiate large electrostatic discharges on Mars [Ruf et al. 2009]. Additionally, similar to terrestrial thunderstorms, they might also be able to produce bright bursts of X-rays and gamma rays. On Earth, thunderstorm electric fields could produce avalanche of energetic electrons from single seed electron, through Møller scattering with air atoms and molecules. The process is called Relativistic Runaway Electron Avalanche (RREA), and can then generate large flux of X-rays and gamma rays through bremsstrahlung scattering. In this presentation, we have used detailed Monte Carlo simulations to study the possibility of producing large flux of energetic photon from a RREA-like mechanism inside Martian dust storms.

  20. SuperAGILE and Gamma Ray Bursts

    SciTech Connect

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

    2006-05-19

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

  1. GeV-gamma-ray emission regions

    NASA Image and Video Library

    2017-09-27

    NASA's Fermi Closes on Source of Cosmic Rays New images from NASA's Fermi Gamma-ray Space Telescope show where supernova remnants emit radiation a billion times more energetic than visible light. The images bring astronomers a step closer to understanding the source of some of the universe's most energetic particles -- cosmic rays. Fermi mapped GeV-gamma-ray emission regions (magenta) in the W44 supernova remnant. The features clearly align with filaments detectable in other wavelengths. This composite merges X-rays (blue) from the Germany-led ROSAT mission, infrared (red) from NASA's Spitzer Space Telescope, and radio (orange) from the Very Large Array near Socorro, N.M. Credit: NASA/DOE/Fermi LAT Collaboration, ROSAT, JPL-Caltech, and NRAO/AUI For more information: www.nasa.gov/mission_pages/GLAST/news/cosmic-rays-source....

  2. The Gamma Ray Observatory - Viewing the violent universe

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Kniffen, D. A.

    1991-01-01

    An overview is given of the Gamma Ray Observatory (GRO) experimental satellite and the four instruments that permit the study of space phenomena from 0.03 to 30,000 MeV. The GRO comprises: (1) the Burst and Transient Source Experiment; (2) the Oriented Scintillation Spectrometer Experiment; (3) the Imaging Compton Telescope; and (4) the Energetic Gamma-Ray Experiment Telescope. The GRO is expected to provide data regarding the active galaxies, extragalactic diffuse radiation, the Galactic center, matter-antimatter annihilation, and gamma-ray emission from quasars.

  3. Astrophysical constraints from gamma-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Diehl, Roland; Prantzos, Nikos; von Ballmoos, Peter

    2006-10-01

    Gamma-ray lines from cosmic sources provide unique isotopic information, since they originate from energy level transitions in the atomic nucleus. Gamma-ray telescopes explored this astronomical window in the past three decades, detecting radioactive isotopes that have been ejected in interstellar space by cosmic nucleosynthesis events and nuclei that have been excited through collisions with energetic particles. Astronomical gamma-ray telescopes feature standard detectors of nuclear physics, but have to be surrounded by effective shields against local instrumental background, and need special detector and/or mask arrangements to collect imaging information. Due to exceptionally-low signal/noise ratios, progress in the field has been slow compared with other wavelengths. Despite the difficulties, this young field of astronomy is well established now, in particular due to advances made by the Compton Gamma-Ray Observatory in the 90ies. The most important achievements so far concern: short-lived radioactivities that have been detected in a couple of supernovae (56Co and 57Co in SN1987A, 44Ti in Cas A), the diffuse glow of long-lived 26Al that has been mapped along the entire plane of the Galaxy, several excited nuclei that have been detected in solar flares, and, last but not least, positron annihilation that has been observed in the inner Galaxy since the 70ies. High-resolution spectroscopy is now being performed: since 2002, ESAs INTEGRAL and NASAs RHESSI, two space-based gamma-ray telescopes with Ge detectors, are in operation. Recent results include: imaging and line shape measurements of e e annihilation emission from the Galactic bulge, which can hardly be accounted for by conventional sources of positrons; 26Al emission and line width measurement from the inner Galaxy and from the Cygnus region, which can constrain the properties of the interstellar medium; and a diffuse 60Fe gamma-ray line emission which appears rather weak, in view of current theoretical

  4. CANGAROO-III Search for Gamma Rays from Kepler's Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Enomoto, R.; Higashi, Y.; Yoshida, T.; Tanimori, T.; Bicknell, G. V.; Clay, R. W.; Edwards, P. G.; Gunji, S.; Hara, S.; Hara, T.; Hattori, T.; Hayashi, S.; Hirai, Y.; Inoue, K.; Kabuki, S.; Kajino, F.; Katagiri, H.; Kawachi, A.; Kifune, T.; Kiuchi, R.; Kubo, H.; Kushida, J.; Matsubara, Y.; Mizukami, T.; Mizumoto, Y.; Mizuniwa, R.; Mori, M.; Muraishi, H.; Muraki, Y.; Naito, T.; Nakamori, T.; Nakano, S.; Nishida, D.; Nishijima, K.; Ohishi, M.; Sakamoto, Y.; Seki, A.; Stamatescu, V.; Suzuki, T.; Swaby, D. L.; Thornton, G.; Tokanai, F.; Tsuchiya, K.; Watanabe, S.; Yamada, Y.; Yamazaki, E.; Yanagita, S.; Yoshikoshi, T.; Yukawa, Y.

    2008-08-01

    Kepler's supernova, discovered in 1604 October, produced a remnant that has been well studied observationally in the radio, infrared, optical, and X-ray bands, and theoretically. Some models have predicted a TeV gamma-ray flux that is detectable with current Imaging Cerenkov Atmospheric Telescopes. We report on observations carried out in 2005 April with the CANGAROO-III Telescope. No statistically significant excess was observed, and limitations on the allowed parameter range in the model are discussed.

  5. The GAMCIT gamma ray burst detector

    NASA Technical Reports Server (NTRS)

    Mccall, Benjamin J.; Grunsfeld, John M.; Sobajic, Srdjan D.; Chang, Chinley Leonard; Krum, David M.; Ratner, Albert; Trittschuh, Jennifer E.

    1993-01-01

    The GAMCIT payload is a Get-Away-Special payload designed to search for high-energy gamma-ray bursts and any associated optical transients. This paper presents details on the design of the GAMCIT payload, in the areas of battery selection, power processing, electronics design, gamma-ray detection systems, and the optical imaging of the transients. The paper discusses the progress of the construction, testing, and specific design details of the payload. In addition, this paper discusses the unique challenges involved in bringing this payload to completion, as the project has been designed, constructed, and managed entirely by undergraduate students. Our experience will certainly be valuable to other student groups interested in taking on a challenging project such as a Get-Away-Special payload.

  6. The future of gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Knödlseder, Jürgen

    2016-06-01

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

  7. Gamma Ray Observatory (GRO) inspected by TRW workers at Redondo Beach plant

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The Gamma Ray Observatory (GRO) is positioned on its end and is inspected by TRW workers prior to shipment to the Kennedy Space Center (KSC). GRO is the heaviest NASA science satellite ever to be deployed by the Space Shuttle into low Earth orbit. From bottom to top are three of the four GRO instruments including the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), and the Energetic Gamma Ray Experiment Telescope (EGRET). The Burst and Transient Source Experiment (BATSE) equipment is located on GRO's corners. GRO, which weighs just over 35,000 pounds (15,876 kilograms), is a space-based observatory scheduled to be put into space by Atlantis, Orbiter Vehicle (OV) 104 during STS-37, next year. GRO is designed to study the universe in an invisible, high-energy form of light known as gamma rays. Gamma rays, which cannot penetrate the Earth's atmosphere, are of interest to scientists because these rays provide a reliable record of cosmic change

  8. STS-37 Gamma Ray Observatory (GRO) grappled by RMS

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Backdropped against the Earth's cloud-covered surface, the Gamma Ray Observatory (GRO) with its solar array (SA) panels deployed is grappled by the remote manipulator system (RMS) during STS-37 systems checkout. GRO's four complement instruments are visible: the Energetic Gamma Ray Experiment Telescope (EGRET) (at the bottom); the Imaging Compton Telescope (COMPTEL) (center); the Oriented Scintillation Spectrometer Experiment (OSSE) (top); and Burst and Transient Source Experiment (BATSE) (on four corners).

  9. Gamma-ray tracking method for pet systems

    DOEpatents

    Mihailescu, Lucian; Vetter, Kai M.

    2010-06-08

    Gamma-ray tracking methods for use with granular, position sensitive detectors identify the sequence of the interactions taking place in the detector and, hence, the position of the first interaction. The improved position resolution in finding the first interaction in the detection system determines a better definition of the direction of the gamma-ray photon, and hence, a superior source image resolution. A PET system using such a method will have increased efficiency and position resolution.

  10. PSR 1820-11 : A binary gamma-ray pulsar

    NASA Astrophysics Data System (ADS)

    Li, Ti-pei; Wu, Mei

    1990-09-01

    Significant pulsation structure in phase distribution in the 50-6000MeV gamma-rays from the direction of the binary radio pulsar PSR 1820-11 in the COS-B data was obtained using the folding algorithm. Besides the period search, a spatial analysis was Bade and a clear point-like gamma-ray image was found at the pulsar's position.

  11. Enhancing the quality of radiographic images acquired with point-like gamma-ray sources through correction of the beam divergence and attenuation

    NASA Astrophysics Data System (ADS)

    Silvani, M. I.; Almeida, G. L.; Lopes, R. T.

    2014-11-01

    Radiographic images acquired with point-like gamma-ray sources exhibit a desirable low penumbra effects specially when positioned far away from the set object-detector. Such an arrangement frequently is not affordable due to the limited flux provided by a distant source. A closer source, however, has two main drawbacks, namely the degradation of the spatial resolution - as actual sources are only approximately punctual - and the non-homogeneity of the beam hitting the detector, which creates a false attenuation map of the object being inspected. This non-homogeneity is caused by the beam divergence itself and by the different thicknesses traversed the beam even if the object were an homogeneous flat plate. In this work, radiographic images of objects with different geometries, such as flat plates and pipes have undergone a correction of beam divergence and attenuation addressing the experimental verification of the capability and soundness of an algorithm formerly developed to generate and process synthetic images. The impact of other parameters, including source-detector gap, attenuation coefficient, ratio defective-to-main hull thickness and counting statistics have been assessed for specifically tailored test-objects aiming at the evaluation of the ability of the proposed method to deal with different boundary conditions. All experiments have been carried out with an X-ray sensitive Imaging Plate and reactor-produced 198Au and 165Dy sources. The results have been compared with other technique showing a better capability to correct the attenuation map of inspected objects unveiling their inner structure otherwise concealed by the poor contrast caused by the beam divergence and attenuation, in particular for those regions far apart from the vertical of the source.

  12. The Gamma-Ray Observatory

    SciTech Connect

    Kniffen, D.A. )

    1989-01-01

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

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

    DOE PAGES

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

    2016-07-01

    Here, we demonstrate how the image analysis technique of wavelet decomposition can be applied to the gamma-ray sky to separate emission on different angular scales. New structures on scales that differ from the scales of the conventional astrophysical foreground and background uncertainties can be robustly extracted, allowing a model-independent characterization with no presumption of exact signal morphology. As a test case, we generate mock gamma-ray data to demonstrate our ability to extract extended signals without assuming a fixed spatial template. For some point source luminosity functions, our technique also allows us to differentiate a diffuse signal in gamma-rays from darkmore » matter annihilation and extended gamma-ray point source populations in a data-driven way.« less

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

    SciTech Connect

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

    2016-07-01

    Here, we demonstrate how the image analysis technique of wavelet decomposition can be applied to the gamma-ray sky to separate emission on different angular scales. New structures on scales that differ from the scales of the conventional astrophysical foreground and background uncertainties can be robustly extracted, allowing a model-independent characterization with no presumption of exact signal morphology. As a test case, we generate mock gamma-ray data to demonstrate our ability to extract extended signals without assuming a fixed spatial template. For some point source luminosity functions, our technique also allows us to differentiate a diffuse signal in gamma-rays from dark matter annihilation and extended gamma-ray point source populations in a data-driven way.

  15. Recent developments in semiconductor gamma-ray detectors

    SciTech Connect

    Luke, Paul N.; Amman, Mark; Tindall, Craig; Lee, Julie S.

    2003-10-28

    The successful development of lithium-drifted Ge detectors in the 1960's marked the beginning of the significant use of semiconductor crystals for direct detection and spectroscopy of gamma rays. In the 1970's, high-purity Ge became available, which enabled the production of complex detectors and multi-detector systems. In the following decades, the technology of semiconductor gamma-ray detectors continued to advance, with significant developments not only in Ge detectors but also in Si detectors and room-temperature compound-semiconductor detectors. In recent years, our group at Lawrence Berkeley National Laboratory has developed a variety of gamma ray detectors based on these semiconductor materials. Examples include Ge strip detectors, lithium-drifted Si strip detectors, and coplanar-grid CdZnTe detectors. These advances provide new capabilities in the measurement of gamma rays, such as the ability to perform imaging and the realization of highly compact spectroscopy systems.

  16. Exploring the extreme gamma-ray sky with HESS

    SciTech Connect

    Sol, Helene

    2006-11-03

    The international HESS experiment. High Energy Stereoscopic System, fully operational since January 2004, is opening a new era for extreme gamma-ray astronomy. Located in Namibia, it is now the most sensitive detector for cosmic sources of very high energy (VHE) gamma-rays, in the tera-electron-volt (TeV) range. In July 2005, it had already more than double the number of sources detected at such energies, with the discovery of several active galactic nuclei (AGN), supernova remnants and plerions, a binary pulsar system, a microquasar candidate, and a sample of yet unidentified sources. HESS has also provide for the first time gamma-ray images of extended sources with the first astrophysical jet resolved in gamma-rays, and the first mapping of a shell supernova remnant, which proves the efficiency of in situ acceleration of particles up to 100 TeV and beyond.

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

    SciTech Connect

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

    2016-07-01

    Here, we demonstrate how the image analysis technique of wavelet decomposition can be applied to the gamma-ray sky to separate emission on different angular scales. New structures on scales that differ from the scales of the conventional astrophysical foreground and background uncertainties can be robustly extracted, allowing a model-independent characterization with no presumption of exact signal morphology. As a test case, we generate mock gamma-ray data to demonstrate our ability to extract extended signals without assuming a fixed spatial template. For some point source luminosity functions, our technique also allows us to differentiate a diffuse signal in gamma-rays from dark matter annihilation and extended gamma-ray point source populations in a data-driven way.

  18. Solar Two Gamma-Ray Observatory

    NASA Astrophysics Data System (ADS)

    Tümer, T.; Bhattacharya, D.; Mohideen, U.; Rieben, R.; Souchkov, V.; Tom, H.; Zweerink, J.

    1999-06-01

    The field of high energy gamma-ray astronomy grew tremendously in the last decade due to the launch of the EGRET detector on the Compton Gamma-Ray Observatory in 1991 and the proliferation of ground-based air Čherenkov telescopes (ACTs) such as the Whipple 10 meter reflector. Interestingly, the ground-based telescopes only see 4-5 of the over 170 objects detected by EGRET. A simple extrapolation of the EGRET objects' energy spectra up to the energies which the ACTs are sensitive suggests that many of them should have been detected. The key to resolving this lack of detections is to observe these sources in the previously unobserved 20-250 GeV energy range. The Solar Two Observatory collaboration is developing a secondary optics system on the central tower of the world's largest solar energy pilot plant, Solar Two, to observe gamma-ray sources in this energy range. The progress in building the secondary optics system to be used to image ˜64 heliostats at Solar Two located in Barstow, California, is presented. We hope to design and build this detector over the next 2 years.

  19. 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.

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

    ScienceCinema

    Isabelle Grenier

    2016-07-12

    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.

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

    SciTech Connect

    Isabelle Grenier

    2009-04-01

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

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

    SciTech Connect

    Grenier, Isabelle

    2009-04-01

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

  3. Gamma-ray Polarimetry with the All-sky Medium Energy Gamma-ray Observatory (AMEGO)

    NASA Astrophysics Data System (ADS)

    Kislat, Fabian

    2017-08-01

    The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a next-generation Compton and pair-production telescope. It will allow us to perform sensitive polarimetric observations in the 200keV to 3MeV energy range. Due to its wide field of view it will survey the entire sky every 3 hours, enabling polarization measurements not only of persistent, but also of transient sources such as gamma-ray bursts. The polarization of gamma-rays carries geometric information about compact emission regions that are too small to be imaged at any wavelength, and will thus provide qualitatively new insights. In this paper we discuss AMEGO's polarization sensitivity based on detailed simulations of the instrument. We will use these results to discuss the scientific potential of AMEGO to search for violations of Lorentz invariance. Finally, we present predictions for possible observations based on theoretical models of bright gamma-ray bursts, blazar jets, and the high-energy tail of the galactic black hole binary Cygnus X-1. These predictions will demonstrate AMEGO's ability to distinguish different theoretical models.

  4. Excellent pulse height uniformity response of a new LaBr3:Ce scintillation crystal for gamma ray imaging

    NASA Astrophysics Data System (ADS)

    Pani, R.; Cinti, M. N.; Fabbri, A.; Orlandi, C.; Pellegrini, R.; Scafè, R.; Colarieti-Tosti, M.

    2015-07-01

    Nuclear Medicine SPECT imaging is taking on new challenges, regarding the improvement of quality and contrast of images. In order to reach this goal, energy resolution and Compton rejection capability have to be enhanced. For detectors based on scintillation crystal, the choice of a scintillator with high light yield is suitable; recently one of the major candidates is Lanthanum Tri-Bromide (LaBr3:Ce), with its high 63,000 ph/MeV light yield. Unfortunately, LaBr3:Ce suffers size limitations due to the actual growth techniques (maximum 3 in. diameter) and has also elevated cost. For these reasons, great interest is shown on small field of view detectors based on LaBr3:Ce, thought for imaging of specific physiological process or organ. To improve energy resolution, continuous crystals are more appropriate instead than pixelated ones. Since in a continuous crystal a decrease in position linearity, due to the light reflections, is typically obtained at the edges, an absorbent treatment of surfaces is generally utilized for SPECT applications. On the other hand, light absorption causes a relevant degradation of local energy resolution and pulse height uniformity response, affecting local image contrast. In this work an analysis on a new continuous LaBr3:Ce scintillation crystal with size proper to a small field of view gamma imager but with reflective treatment of surfaces is presented. This leads up to outstanding overall and local energy resolution results and excellent pulse height uniformity response on the whole field of view. Furthermore, preliminary imaging results are satisfactory, compared to the ones from a scintillation crystal with absorbent edges.

  5. Towed seabed gamma ray spectrometer

    SciTech Connect

    Jones, D.G. )

    1994-08-01

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

  6. Source mechanisms of terrestrial gamma-ray flashes

    NASA Astrophysics Data System (ADS)

    Dwyer, J. R.

    2008-05-01

    The source of terrestrial gamma-ray flashes (TGFs) has remained a mystery since their discovery in 1994. Recent Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) observations show that these intense bursts of MeV gamma rays likely originate much deeper in the atmosphere than previously inferred from Burst and Transient Source Experiment (BATSE) data, with the source altitude <21 km. Using existing measurements of the intensity and duration of BATSE and RHESSI TGFs, along with limits on the electric field set by the relativistic feedback mechanism involving backward propagating positrons and x-rays, it is found that TGFs cannot be produced by relativistic runaway electron avalanches acting on natural background radiation or extensive cosmic-ray air showers alone, as has been assumed by many previous models. Instead, the energetic seed particle production most likely involves either relativistic feedback or runaway electron production in the strong electric fields associated with lightning leaders or streamers, similar to the energetic radiation observed on the ground from lightning.

  7. Very High Energy gamma-rays from blazars

    NASA Astrophysics Data System (ADS)

    Sol, Helene

    2014-07-01

    The extragalactic very high energy (VHE) gamma-ray sky is dominated at the moment by more than fifty blazars detected by the present imaging atmospheric Cherenkov telescopes (IACT), with a majority (about 90%) of high-frequency peaked BL Lac objects (HBL) and a small number of low-frequency peaked and intermediate BL Lac objects (LBL and IBL) and flat spectrum radio quasars (FSRQ). A significant variability is often observed, with time scales from a few minutes to months and years. The spectral energy distribution (SED) of these blazars typically shows two bumps from the radio to the TeV range, which can usually be described by leptonic or hadronic processes. While elementary bricks of the VHE emission scenarios seem now reasonably well identified, a global picture of these sources, describing the geometry and dynamics of the VHE zone, is not yet available. Multiwavelength monitoring and global alert network will be important to better constrain the picture, especially with the perspective of CTA, a major project of the next generation in ground-based gamma-ray astronomy.

  8. Upgrade of the JET Gamma-Ray Cameras

    SciTech Connect

    Soare, S.; Curuia, M.; Anghel, M.; Constantin, M.; David, E.; Zoita, V.; Craciunescu, T.; Falie, D.; Pantea, A.; Tiseanu, I.; Kiptily, V.; Prior, P.; Edlington, T.; Griph, S.; Krivchenkov, Y.; Loughlin, M.; Popovichev, S.; Riccardo, V.; Syme, B.; Thompson, V.

    2008-03-12

    The JET gamma-ray camera diagnostics have already provided valuable information on the gamma-ray imaging of fast ion in JET plasmas /1,2/. The applicability of gamma-ray imaging to high performance deuterium and deuterium-tritium JET discharges is strongly dependent on the fulfilment of rather strict requirements for the characterisation of the neutron and gamma-ray radiation fields. These requirements have to be satisfied within very stringent boundary conditions for the design, such as the requirement of minimum impact on the co-existing neutron camera diagnostics. The JET Gamma-Ray Cameras (GRC) upgrade project deals with these issues with particular emphasis on the design of appropriate neutron/gamma-ray filters ('neutron attenuators'). Several design versions have been developed and evaluated for the JET GRC neutron attenuators at the conceptual design level. The main design parameter was the neutron attenuation factor. The two design solutions, that have been finally chosen and developed at the level of scheme design, consist of: a) one quasi-crescent shaped neutron attenuator (for the horizontal camera) and b) two quasi-trapezoid shaped neutron attenuators (for the vertical one). The second design solution has different attenuation lengths: a short version, to be used together with the horizontal attenuator for deuterium discharges, and a long version to be used for high performance deuterium and DT discharges. Various neutron-attenuating materials have been considered (lithium hydride with natural isotopic composition and {sup 6}Li enriched, light and heavy water, polyethylene). Pure light water was finally chosen as the attenuating material for the JET gamma-ray cameras. The neutron attenuators will be steered in and out of the detector line-of-sight by means of an electro-pneumatic steering and control system. The MCNP code was used for neutron and gamma ray transport in order to evaluate the effect of the neutron attenuators on the neutron field of the

  9. Imaging of prompt gamma rays emitted during delivery of clinical proton beams with a Compton camera: feasibility studies for range verification.

    PubMed

    Polf, Jerimy C; Avery, Stephen; Mackin, Dennis S; Beddar, Sam

    2015-09-21

    The purpose of this paper is to evaluate the ability of a prototype Compton camera (CC) to measure prompt gamma rays (PG) emitted during delivery of clinical proton pencil beams for prompt gamma imaging (PGI) as a means of providing in vivo verification of the delivered proton radiotherapy beams. A water phantom was irradiated with clinical 114 MeV and 150 MeV proton pencil beams. Up to 500 cGy of dose was delivered per irradiation using clinical beam currents. The prototype CC was placed 15 cm from the beam central axis and PGs from 0.2 MeV up to 6.5 MeV were measured during irradiation. From the measured data (2D) images of the PG emission were reconstructed. (1D) profiles were extracted from the PG images and compared to measured depth dose curves of the delivered proton pencil beams. The CC was able to measure PG emission during delivery of both 114 MeV and 150 MeV proton beams at clinical beam currents. 2D images of the PG emission were reconstructed for single 150 MeV proton pencil beams as well as for a 5   ×   5 cm mono-energetic layer of 114 MeV pencil beams. Shifts in the Bragg peak (BP) range were detectable on the 2D images. 1D profiles extracted from the PG images show that the distal falloff of the PG emission profile lined up well with the distal BP falloff. Shifts as small as 3 mm in the beam range could be detected from the 1D PG profiles with an accuracy of 1.5 mm or better. However, with the current CC prototype, a dose of 400 cGy was required to acquire adequate PG signal for 2D PG image reconstruction. It was possible to measure PG interactions with our prototype CC during delivery of proton pencil beams at clinical dose rates. Images of the PG emission could be reconstructed and shifts in the BP range were detectable. Therefore PGI with a CC for in vivo range verification during proton treatment delivery is feasible. However, improvements in the prototype CC detection efficiency and reconstruction algorithms are necessary

  10. The application of two-dimensional imaging to very high energy gamma ray astronomy. Annual report, 1 May 1991--30 April 1992

    SciTech Connect

    Weekes, T.C.

    1992-12-01

    After an introductory overview of gamma-ray astronomy, very brief summaries of research results are given. Summary topics may be grouped as follows: observations (survey of candidate gamma-ray sources; Cygnus X-3; Markarian 421; AGN`s: general survey; Crab observations: pulsar outburst; Geminga; AE Aqr; bursts; ARTEMIS; muon telescope), technical developments (11m telescope: dedication and performance; 10m mount control; CCD cameras; light cones; filters; GRANITE upgrade; trigger configuration; miror coatings; lightning protection), data analysis (quick look; optical disk archive; false source method), infrastructure, and reviews.

  11. Color gamma ray camera: Laboratory directed research & development (LDRD) FY 1995

    SciTech Connect

    Bionta, R.M.

    1996-06-01

    Gamma-Ray imaging is a potentially powerful tool for the areas of arms-control, counter proliferation, safeguards and forensics. Combining spectral and spatial information increases the amount of information available for the detection and characterization of Special Nuclear Material (SNM). Two advanced gamma ray imaging technologies have been completed and are nearing completion at LLNL. These include the Gamma Ray Imaging System (GRIS), used to detect sub-600 keV gamma rays, and the Gamma Ray Bar Imaging Telescope (GRABIT), which extends the work of GRIS to larger areas and higher energies ({approximately}1000 keV). We proposed to continue work on a third, complementary type of detector, a Gamma Ray Color Camera (GRCC), which will incorporate spatial and spectral information from a gamma emitter.

  12. The TIGRE Instrument for Intermediate-Energy Gamma-Ray Astronomy

    NASA Astrophysics Data System (ADS)

    O'Neill, T. J.; Blattacharya, D.; Dixon, D. D.; Kong, V.; Minor, C.; Miyagi, T.; Polsen, M.; Zych, A. D.; Samimi, J.; Akyüz, A.

    2000-10-01

    A prototype of the Tracking and Imaging Gamma-Ray Experiment (TIGRE) is being constructed. TIGRE is a Compton gamma-ray telescope concept for a future space mission in high-energy astrophysics. It is sensitive from 300 keV to 10 MeV, with Compton recoil electron tracking to give unique incident event directions. From 10 to 100 MeV it is also an electron-positron gamma-ray pair telescope. Multi-layers of 10 cm x 10 cm x 300 micron silicon strip detectors serve as the Compton converter with electron tracking between successive layers. A position-sensitive calorimeter is used to detect the scattered gamma ray. When germanium or CdZnTe detectors are used for the calorimeter TIGRE has the best achievable performance, approaching few arc minute and few keV resolutions. These will be used to determine the definition and origin of the diffuse line emissions from the Galactic Center Region and measure the development and decay of nuclear line emissions in supernova explosions. Polarization measurements will be possible for the first time. TIGRE's wide field-of-view (>pi sr.) will allow monitoring of many AGN blazars and pulsars in this critical intermediate energy range. The silicon tracker is currently being used with a CsI(Tl) position-sensitive calorimeter. Laboratory measurements and background-limited sensitivities will be presented. Both atmospheric albedo gamma ray and neutron backgrounds are included. The authors wish to acknowledge the continuing support of NASA Grant NAG5-5116.

  13. Quasars, blazars, and gamma rays.

    PubMed

    Dermer, C D; Schlickeiser, R

    1992-09-18

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

  14. Swift's 500th Gamma Ray Burst

    NASA Image and Video Library

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

  15. 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.

  16. From Enigma to Tool: Gamma-Ray Burst Reveals Secrets of Host Galaxy

    NASA Astrophysics Data System (ADS)

    2001-05-01

    Five years ago, astronomers knew almost nothing about Gamma Ray Bursts. Now, a team of observers using the National Science Foundation's Very Large Array (VLA) radio telescope has used a gamma-ray burst as a powerful tool to unveil the nature of the galaxy in which it occurred, more than 7 billion light-years away. VLA Images of GRB980703 Host Galaxy "We believe that gamma-ray bursts may become one of the best available tools for studying the history of star formation in the universe," said Edo Berger, a graduate student at Caltech. Berger worked with Caltech astronomy professor Shri Kulkarni and Dale Frail, an astronomer at the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico, to study a gamma-ray burst first seen on July 3, 1998. The astronomers presented their results at the American Astronomical Society's meeting in Pasadena, CA. "For the first time, we've seen the host galaxy of a gamma-ray burst with a radio telescope," Berger said. "Previously, gamma-ray-burst host galaxies have been seen with optical telescopes, but detecting this galaxy with a radio telescope has given us new clues about the nature of the galaxy itself -- clues we couldn't have gotten any other way," he added. For example, based on optical-telescope studies, astronomers estimated that new stars are forming in the host galaxy at the rate of about the mass equivalent of 20 suns per year. However, data from the radio observations show that the actual star-formation rate is 25 times greater -- the mass equivalent of 500 suns per year. "With the VLA, we are seeing the entire region of star formation in this galaxy, including the areas so dusty that visible light can't get out," said Frail. Gamma-ray bursts are the most powerful explosions since the Big Bang. First discovered in 1967 by a satellite launched to monitor compliance with the atmospheric nuclear test ban treaty, gamma-ray bursts remained one of astronomy's premier mysteries for 30 years. For three decades

  17. Portable compton gamma-ray detection system

    DOEpatents

    Rowland, Mark S.; Oldaker, Mark E.

    2008-03-04

    A Compton scattered gamma-ray detector system. The system comprises a gamma-ray spectrometer and an annular array of individual scintillators. The scintillators are positioned so that they are arrayed around the gamma-ray spectrometer. The annular array of individual scintillators includes a first scintillator. A radiation shield is positioned around the first scintillator. A multi-channel analyzer is operatively connected to the gamma-ray spectrometer and the annular array of individual scintillators.

  18. Cosmic ray albedo gamma rays from the quiet sun

    NASA Technical Reports Server (NTRS)

    Seckel, D.; Stanev, T.; Gaisser, T. K.

    1992-01-01

    We estimate the flux of gamma-rays that result from collisions of high energy galactic cosmic rays with the solar atmosphere. An important aspect of our model is the propagation of cosmic rays through the magnetic fields of the inner solar systems. We use diffusion to model propagation down to the bottom of the corona. Below the corona we trace particle orbits through the photospheric fields to determine the location of cosmic ray interactions in the solar atmosphere and evolve the resultant cascades. For our nominal choice of parameters, we predict an integrated flux of gamma rays (at 1 AU) of F(E(sub gamma) greater than 100 MeV) approximately = 5 x 10(exp -8)/sq cm sec. This can be an order of magnitude above the galactic background and should be observable by the Energetic Gamma Ray experiment telescope (EGRET).

  19. Gamma ray spectroscopy in astrophysics. [conferences

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  20. Nuclear gamma rays from energetic particle interactions

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  1. Elemental mapping of the moon using gamma rays : past, present, and future /

    SciTech Connect

    Reedy, R. C.

    2001-01-01

    The energies and intensities of gamma rays From a planetary surface can be used to infer the elemental composition of an object with no or a thin atmosphere. The Apollo gamma-ray spectrometers in 1972 and 1973 produced many of the results for the distribution of elements in the Moon that are now generally well accepted. Lunar Prospector in 1998 and 1999 globally mapped the Moon with gamma rays and neutrons. Both missions used spectrometers with poor energy resolution ({approx}8-10%). The Japanese plan to send a high-resolution germanium gamma-ray spectrometer to the Moon in about 2004 on their SELENE mission. However, little has been done since the 1970s on the models used to unfold planetary gamma-ray spectra. More work needs to be done on understanding what to expect in future gamma-ray spectra and how to unfold such data.

  2. B-FlaP: Classifying Gamma-ray Blazars Using Machine Learning

    NASA Astrophysics Data System (ADS)

    Thompson, David John; Chiaro, Graziano; Giroletti, Marcello; Salvetti, David; La Mura, Giovanni; Bastieri, Denis

    2017-01-01

    In the Third Fermi Large Area Telescope Catalog of high-energy gamma-ray sources, 573 are listed as Blazar Candidates of Uncertain type (BCU), or sources without a conclusive classification. Blazar Flaring Patterns (B-FlaP) uses Empirical Cumulative Distribution Function and Artificial Neural Network machine-learning techniques for a fast method of screening and classification of BCUs based on gamma-ray data only, when rigorous multiwavelength analysis is not available. In this study radio analysis and direct observations by ground-based optical observatories are used to validate the B-FlaP method. Tests indicate that the method is effective, suggesting that 342 sources are likely BL Lac objects, 154 are likely Flat Spectrum Radio Quasars, with only 77 remaining uncertain. 53 of the BCUs appear to be High Synchrotron Peaked blazars, a class of particular interest to ground-based imaging atmospheric Cherenkov telescopes.

  3. The Tunka detector complex: from cosmic-ray to gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Budnev, N.; Astapov, I.; Barbashina, N.; Bogdanov, A.; Bogorodskii, D.; Boreyko, V.; Büker, M.; Brückner, M.; Chiavassa, A.; Chvalaev, O.; Gress, O.; Gress, T.; Dyachok, A.; Epimakhov, S.; Gafatov, A.; Gorbunov, N.; Grebenyuk, V.; Grinuk, A.; Haungs, A.; Hiller, R.; Horns, D.; Huege, T.; Ivanova, A.; Kalinin, A.; Karpov, N.; Kalmykov, N.; Kazarina, Y.; Kindin, V.; Kirichkov, N.; Kiryuhin, S.; Kleifges, M.; Kokoulin, R.; Komponiest, K.; Konstantinov, A.; Konstantinov, E.; Korobchenko, A.; Korosteleva, E.; Kostunin, D.; Kozhin, V.; Krömer, O.; Kunnas, M.; Kuzmichev, L.; Lenok, V.; Lubsandorzhiev, B.; Lubsandorzhiev, N.; Mirgazov, R.; Mirzoyan, R.; Monkhoev, R.; Nachtigall, R.; Pakhorukov, A.; Panasyuk, M.; Pankov, L.; Petrukhin, A.; Platonov, V.; Poleschuk, V.; Popova, E.; Porelli, A.; Prosin, V.; Ptuskin, V.; Rubtsov, G.; Rühle, C.; Samoliga, V.; Satunin, P.; Savinov, V.; Saunkin, A.; Schröder, F.; Semeney, Yu; Shaibonov (junior, B.; Silaev, A.; Silaev (junior, A.; Skurikhin, A.; Slucka, V.; Spiering, C.; Sveshnikova, L.; Tabolenko, V.; Tkachenko, A.; Tkachev, L.; Tluczykont, M.; Voronin, D.; Wischnewski, R.; Zagorodnikov, A.; Zurbanov, V.; Yashin, I.

    2015-08-01

    TAIGA stands for “Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy” and is a project to build a complex, hybrid detector system for ground-based gamma- ray astronomy from a few TeV to several PeV, and for cosmic-ray studies from 100 TeV to 1 EeV. TAIGA will search for ”PeVatrons” (ultra-high energy gamma-ray sources) and measure the composition and spectrum of cosmic rays in the knee region (100 TeV - 10 PeV) with good energy resolution and high statistics. TAIGA will include Tunka-HiSCORE (an array of wide-angle air Cherenkov stations), an array of Imaging Atmospheric Cherenkov Telescopes, an array of particle detectors, both on the surface and underground, and the TUNKA-133 air Cherenkov array.

  4. Very-High-Energy Gamma-Ray Observations of Active Galactic Nuclei with VERITAS

    NASA Astrophysics Data System (ADS)

    Quinn, John

    2016-08-01

    VERITAS is an array of four imaging atmospheric Cherenkov telescopes for very-high-energy (VHE, E>100 GeV) gamma-ray astronomy that has been in full scientific operation since 2007. The VERITAS collaboration is conducting several key science projects, one of which is the study of active galactic nuclei (AGN). So far, VERITAS has invested more than 3000 hours in observations of AGN, with approximately 150 objects observed. The program has resulted in the successful detection of 34 AGN as VHE gamma-ray sources, with the majority belonging to the blazar AGN subclass. Significant effort is made to acquire multiwavelength data coincident with the VERITAS observations. An overview of the VERITAS AGN program and its key results will be presented.

  5. The gamma-ray spectrometer experiment on the solar maximum mission satellite

    NASA Technical Reports Server (NTRS)

    Chupp, E. L.

    1987-01-01

    The major activities summarized include: Gamma-Ray Spectrometer (GRS) instrument response and flight operation; solar flare studies; cosmic gamma-ray studies; summary of computer operations; search for flare-precursor protons; diffuse galactic annihilation radiation; cosmic ray bursts; atmospheric gamma ray spectrum; gamma ray line emission from supernovae and novae; improved angular resolutions using Earth occultation; and production processing of NASA IPD data. In addition, an updated list of published papers and invited papers or contributed papers presented at scientific meetings is provided.

  6. Recommended Priorities for NASA's Gamma Ray Astronomy Program 1999-2013

    NASA Technical Reports Server (NTRS)

    Carol, Ladd

    1999-01-01

    The Gamma-Ray Astronomy Program Working Group (GRAPWG) recommends priorities for the NASA Gamma-Ray Astronomy Program. The highest priority science topic is nuclear astrophysics and sites of gamma ray line emission. Other high priority topics are gamma ray bursts, hard x-ray emission from accreting black holes and neutron stars, the Advanced Compton Telescope (ACT), the High-resolution Spectroscopic Imager (HSI), and the Energetic X-ray Imaging Survey Telescope (EXIST). The recommendations include special consideration for technology development, TeV astronomy, the ultra-long duration balloon (ULDB) program, the International Space Station, optical telescope support, and data analysis and theory.

  7. Effects of overburden, biomass and atmospheric inversions on energy and angular distributions of gamma rays from U, K, Th, and airborne radon sources. Final report

    SciTech Connect

    Rubin, R.M.; Leggett, D.; Wells, M.B.

    1980-12-01

    This report describes a set of radiation transport calculations that were run with the AHISN S/sub n/ discrete ordinates code and a point kernel code to determine the energy, polar angle and height in air distributions of the total and direct gamma-ray flux densities from: (1) uranium sources of 3.2, 200 and 800 ppM in a sandstone orebody covered with biomass densities of 0, 10.2, 20.4, 51.0 and 102.0 kg/m/sup 2/; (2) thorium sources of 12, 25 and 80 ppM in a sandstone ore body covered with biomass densities of 0, 10.2, 20.4, 51.0 and 102.0 kg/m/sup 2/; (3) potassium source (2.5 wt %) in a sandstone ore body covered with biomass densities of 0, 10.2, 20.4, 51.0 and 102.0 kg/m/sup 2/; (4) constant airborne source with height for no inversion and for inversion layer heights of 65.22, 260.32 and 458.43 m; (5) exponentially decreasing airborne source for no inversion and inversion layer heights of 65.22, 260.32 and 458.43 m; (6) 3.2 ppM uranium source in overburden layers of 10.266, 17.110, 26.399 and 32.509 cm thick; (7) 12 ppM thorium source in overburden layers of 10.266, 17.110, 26.399 and 32.509 cm; (8) 2.5 wt % of potassium in overburden layers of 10.266, 17.110, 26.399 and 32.509 cm thick; and (9) 3.2 ppM, 200 ppM, and 800 ppM uranium source in sandstone orebody covered with overburden thicknesses of 10.266, 17.110, 26.399 and 32.509 cm. Gamma-ray emission from the decay of natural uranium, thorium, radon, and potassium are given in a 45-energy group structure applicable to the energy windows used to map the potential uranium ore reserves.

  8. Advanced gamma ray technology for scanning cargo containers.

    PubMed

    Orphan, Victor J; Muenchau, Ernie; Gormley, Jerry; Richardson, Rex

    2005-01-01

    The shipping industry is striving to increase security for cargo containers without significantly impeding traffic. Three Science Applications International Corporation (SAIC) development programs are supporting this effort. SAIC's ICIS system combines SAIC's VACIS gamma ray imaging, radiation scanning, OCR, elemental analysis and other technologies to scan containers for nuclear materials and other hazards in normal terminal traffic. SAIC's enhanced gamma ray detector improves VACIS image resolution by a factor of three. And SAIC's EmptyView software analyzes VACIS images to automatically verify empty containers.

  9. Detection of terrestrial gamma-ray flashes with the AGILE satellite

    NASA Astrophysics Data System (ADS)

    Ursi, A.; Marisaldi, M.; Tavani, M.; Sanò, P.; Casella, D.; Dietrich, S.

    2017-05-01

    Terrestrial gamma-ray flashes are brief submillisecond gamma-ray emissions, produced during thunderstorms and strictly correlated to lightning and atmospheric electric activity. Serendipitously discovered in 1994 by the Compton Gamma Ray Observatory, these elusive events have been further investigated by several missions and satellites devoted to high-energy astrophysics, such as RHESSI, AGILE and Fermi. Terrestrial gamma-ray flashes are thought to be bremsstrahlung gamma-rays, produced at the top of thunderclouds by avalanches of electrons accelerated within thunderstorm strong electric fields and abruptly braked in the atmosphere. Exhibiting energies ranging from few keV up to several tens of MeV, terrestrial gamma-ray flashes are the most energetic phenomenon naturally occurring on Earth and they can represent a severe risk for airplanes and aircraft transports, both for the crew and the on board electronics, that should be carefully investigated and understood. The AGILE (Astrorivelatore Gamma ad Immagini LEggero) satellite is an entirely Italian mission, launched in 2007 and still operational, aimed at investigating gamma-ray emissions from cosmic sources. The wide energy range and the unique submillisecond trigger logic of its on-board instruments, together with the narrow quasi-equatorial orbit of the spacecraft, make AGILE a very suitable instrument to detect and investigate terrestrial gamma-ray flashes. Recent improvements rose up the terrestrial gamma-ray flashes detection rate and lead to the observation, for the first time, of multiple events occurring within single thunderstorm processes.

  10. Cosmic gamma-ray lines

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1986-01-01

    Recent observations of gamma-ray line emissions from gamma-ray bursts, the ISM, the Galactic center, and solar flares are reviewed, and the implications of these observations for high-energy processes in these sources are discussed. Line observations suggest that magnetized neutron stars are probably the best candidate objects for burst sources. Observations of the 1.809-MeV line from Al-26 decay provide evidence for ongoing nucleosynthesis in the Galaxy and information on the spatial distribution of nucleosynthetic sites. The compact 0.511-MeV line source is probably a black hole at or close to the Galactic center. Solar-flare studies have provided new information on the confinement and escape of charged particles at the sun and on multiple acceleration phases in solar flares.

  11. ESA presents INTEGRAL, its space observatory for Gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    1998-09-01

    A unique opportunity for journalists and cameramen to view INTEGRAL will be provided at ESA/ESTEC, Noordwijk, the Netherlands on Tuesday 22 September. On show will be the full-size structural thermal model which is now beeing examined in ESA's test centre. Following introductions to the project, the INTEGRAL spacecraft can be seen, filmed and photographed in its special clean room environment.. Media representatives wishing to participate in the visit to ESA's test centre and the presentation of INTEGRAL are kindly requested to return by fax the attached registration form to ESA Public relations, Tel. +33 (0) 1.53.69.71.55 - Fax. +33 (0) 1.53.69.76.90. For details please see the attached programme Gamma-ray astronomy - why ? Gamma-rays cannot be detected from the ground since the earth's atmosphere shields us from high energetic radiation. Only space technology has made gamma-astronomy possible. To avoid background radiation effects INTEGRAL will spend most of its time in the orbit outside earth's radiation belts above an altitude of 40'000 km. Gamma-rays are the highest energy form of electromagnetic radiation. Therefore gamma-ray astronomy explores the most energetic phenomena occurring in nature and addresses some of the most fundamental problems in physics. We know for instance that most of the chemical elements in our bodies come from long-dead stars. But how were these elements formed? INTEGRAL will register gamma-ray evidence of element-making. Gamma-rays also appear when matter squirms in the intense gravity of collapsed stars or black holes. One of the most important scientific objectives of INTEGRAL is to study such compact objects as neutron stars or black holes. Besides stellar black holes there may exist much bigger specimens of these extremely dense objects. Most astronomers believe that in the heart of our Milky Way as in the centre of other galaxies there may lurk giant black holes. INTEGRAL will have to find evidence of these exotic objects. Even

  12. ESA presents INTEGRAL, its space observatory for Gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    1998-09-01

    A unique opportunity for journalists and cameramen to view INTEGRAL will be provided at ESA/ESTEC, Noordwijk, the Netherlands on Tuesday 22 September. On show will be the full-size structural thermal model which is now beeing examined in ESA's test centre. Following introductions to the project, the INTEGRAL spacecraft can be seen, filmed and photographed in its special clean room environment.. Media representatives wishing to participate in the visit to ESA's test centre and the presentation of INTEGRAL are kindly requested to return by fax the attached registration form to ESA Public relations, Tel. +33 (0) 1.53.69.71.55 - Fax. +33 (0) 1.53.69.76.90. For details please see the attached programme Gamma-ray astronomy - why ? Gamma-rays cannot be detected from the ground since the earth's atmosphere shields us from high energetic radiation. Only space technology has made gamma-astronomy possible. To avoid background radiation effects INTEGRAL will spend most of its time in the orbit outside earth's radiation belts above an altitude of 40'000 km. Gamma-rays are the highest energy form of electromagnetic radiation. Therefore gamma-ray astronomy explores the most energetic phenomena occurring in nature and addresses some of the most fundamental problems in physics. We know for instance that most of the chemical elements in our bodies come from long-dead stars. But how were these elements formed? INTEGRAL will register gamma-ray evidence of element-making. Gamma-rays also appear when matter squirms in the intense gravity of collapsed stars or black holes. One of the most important scientific objectives of INTEGRAL is to study such compact objects as neutron stars or black holes. Besides stellar black holes there may exist much bigger specimens of these extremely dense objects. Most astronomers believe that in the heart of our Milky Way as in the centre of other galaxies there may lurk giant black holes. INTEGRAL will have to find evidence of these exotic objects. Even

  13. Compton Gamma Ray Observatory Guest Investigator Program

    NASA Technical Reports Server (NTRS)

    Lingenfelter, Richard E.

    1997-01-01

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

  14. Radio imaging of the very-high-energy gamma-ray emission region in the central engine of a radio galaxy.

    PubMed

    Acciari, V A; Aliu, E; Arlen, T; Bautista, M; Beilicke, M; Benbow, W; Bradbury, S M; Buckley, J H; Bugaev, V; Butt, Y; Byrum, K; Cannon, A; Celik, O; Cesarini, A; Chow, Y C; Ciupik, L; Cogan, P; Cui, W; Dickherber, R; Fegan, S J; Finley, J P; Fortin, P; Fortson, L; Furniss, A; Gall, D; Gillanders, G H; Grube, J; Guenette, R; Gyuk, G; Hanna, D; Holder, J; Horan, D; Hui, C M; Humensky, T B; Imran, A; Kaaret, P; Karlsson, N; Kieda, D; Kildea, J; Konopelko, A; Krawczynski, H; Krennrich, F; Lang, M J; LeBohec, S; Maier, G; McCann, A; McCutcheon, M; Millis, J; Moriarty, P; Ong, R A; Otte, A N; Pandel, D; Perkins, J S; Petry, D; Pohl, M; Quinn, J; Ragan, K; Reyes, L C; Reynolds, P T; Roache, E; Roache, E; Rose, H J; Schroedter, M; Sembroski, G H; Smith, A W; Swordy, S P; Theiling, M; Toner, J A; Varlotta, A; Vincent, S; Wakely, S P; Ward, J E; Weekes, T C; Weinstein, A; Williams, D A; Wissel, S; Wood, M; Walker, R C; Davies, F; Hardee, P E; Junor, W; Ly, C; Aharonian, F; Akhperjanian, A G; Anton, G; Barres de Almeida, U; Bazer-Bachi, A R; Becherini, Y; Behera, B; Bernlöhr, K; Bochow, A; Boisson, C; Bolmont, J; Borrel, V; Brucker, J; Brun, F; Brun, P; Bühler, R; Bulik, T; Büsching, I; Boutelier, T; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Chounet, L-M; Clapson, A C; Coignet, G; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubois, F; Dubus, G; Dyks, J; Dyrda, M; Egberts, K; Emmanoulopoulos, D; Espigat, P; Farnier, C; Feinstein, F; Fiasson, A; Förster, A; Fontaine, G; Füssling, M; Gabici, S; Gallant, Y A; Gérard, L; Gerbig, D; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Göhring, D; Hauser, D; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Holleran, M; Hoppe, S; Horns, D; Jacholkowska, A; de Jager, O C; Jahn, C; Jung, I; Katarzyński, K; Katz, U; Kaufmann, S; Kendziorra, E; Kerschhaggl, M; Khangulyan, D; Khélifi, B; Keogh, D; Kluźniak, W; Kneiske, T; Komin, Nu; Kosack, K; Lamanna, G; Lenain, J-P; Lohse, T; Marandon, V; Martin, J M; Martineau-Huynh, O; Marcowith, A; Maurin, D; McComb, T J L; Medina, M C; Moderski, R; Moulin, E; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Olive, J-F; de Oña Wilhelmi, E; Orford, K J; Ostrowski, M; Panter, M; Paz Arribas, M; Pedaletti, G; Pelletier, G; Petrucci, P-O; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raubenheimer, B C; Raue, M; Rayner, S M; Renaud, M; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Ruppel, J; Sahakian, V; Santangelo, A; Schlickeiser, R; Schöck, F M; Schröder, R; Schwanke, U; Schwarzburg, S; Schwemmer, S; Shalchi, A; Sikora, M; Skilton, J L; Sol, H; Spangler, D; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Superina, G; Szostek, A; Tam, P H; Tavernet, J-P; Terrier, R; Tibolla, O; Tluczykont, M; van Eldik, C; Vasileiadis, G; Venter, C; Venter, L; Vialle, J P; Vincent, P; Vivier, M; Völk, H J; Volpe, F; Wagner, S J; Ward, M; Zdziarski, A A; Zech, A; Anderhub, H; Antonelli, L A; Antoranz, P; Backes, M; Baixeras, C; Balestra, S; Barrio, J A; Bastieri, D; Becerra González, J; Becker, J K; Bednarek, W; Berger, K; Bernardini, E; Biland, A; Bock, R K; Bonnoli, G; Bordas, P; Borla Tridon, D; Bosch-Ramon, V; Bose, D; Braun, I; Bretz, T; Britvitch, I; Camara, M; Carmona, E; Commichau, S; Contreras, J L; Cortina, J; Costado, M T; Covino, S; Curtef, V; Dazzi, F; De Angelis, A; De Cea del Pozo, E; Delgado Mendez, C; De los Reyes, R; De Lotto, B; De Maria, M; De Sabata, F; Dominguez, A; Dorner, D; Doro, M; Elsaesser, D; Errando, M; Ferenc, D; Fernández, E; Firpo, R; Fonseca, M V; Font, L; Galante, N; García López, R J; Garczarczyk, M; Gaug, M; Goebel, F; Hadasch, D; Hayashida, M; Herrero, A; Hildebrand, D; Höhne-Mönch, D; Hose, J; Hsu, C C; Jogler, T; Kranich, D; La Barbera, A; Laille, A; Leonardo, E; Lindfors, E; Lombardi, S; Longo, F; López, M; Lorenz, E; Majumdar, P; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Mariotti, M; Martínez, M; Mazin, D; Meucci, M; Miranda, J M; Mirzoyan, R; Miyamoto, H; Moldón, J; Moles, M; Moralejo, A; Nieto, D; Nilsson, K; Ninkovic, J; Oya, I; Paoletti, R; Paredes, J M; Pasanen, M; Pascoli, D; Pauss, F; Pegna, R G; Perez-Torres, M A; Persic, M; Peruzzo, L; Prada, F; Prandini, E; Puchades, N; Reichardt, I; Rhode, W; Ribó, M; Rico, J; Rissi, M; Robert, A; Rügamer, S; Saggion, A; Saito, T Y; Salvati, M; Sanchez-Conde, M; Satalecka, K; Scalzotto, V; Scapin, V; Schweizer, T; Shayduk, M; Shore, S N; Sidro, N; Sierpowska-Bartosik, A; Sillanpää, A; Sitarek, J; Sobczynska, D; Spanier, F; Stamerra, A; Stark, L S; Takalo, L; Tavecchio, F; Temnikov, P; Tescaro, D; Teshima, M; Torres, D F; Turini, N; Vankov, H; Wagner, R M; Zabalza, V; Zandanel, F; Zanin, R; Zapatero, J

    2009-07-24

    The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 10(12) electron volts and are bright sources of very-high-energy (VHE) gamma-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE gamma-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole.

  15. On the origin of gamma ray bursts

    NASA Astrophysics Data System (ADS)

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

    1988-03-01

    It is argued that observations of gamma ray bursts show that the neutron star model is not tenable. A similarity between gamma ray burst characteristics and solar hard X-ray flares is established. The temporal and spectral features observed in the gamma ray bursts are also seen in the solar hard X-ray flares. The only distinction is in the energy contents of the two. Gamma ray bursts may originate from sources which have Sun-like activity. Large scale Sun-like activity is observed in flare stars, RS CVn binaries, and cataclysmic variables, grouped together as magnetically active stellar systems. These systems have enough energy to produce gamma ray bursts. Positional identification between the gamma ray burst error boxes and the magnetically active stellar systems produces an association of 46 objects with 36 error boxes with a probability of chance coincidence of 10 to the minus 10th power. A gamma ray burst that has a spatial and temporal correlation to a soft X-ray flare associated with a magnetically active stellar system and another time coincidence where the gamma ray burst location is not known to be found. Gamma ray bursts should be considered the stellar equivalent of the solar hard X-ray burst. gamma ray burst location is not known are found. Gamma ray bursts should be considered as stellar equivalents of solar hard X-ray bursts.

  16. Periodic gamma-ray emissions from Geminga at or = 10(12) eV

    NASA Technical Reports Server (NTRS)

    Kaul, R. K.; Rawat, H. S.; Sanecha, V. K.; Rannot, R. C.; Sapru, M.; Tickoo, A. K.; Qazi, R. A.; Bhat, C. L.; Razdan, H.; Tonwar, S. C.

    1985-01-01

    Analysis of data from an atmospheric Cerenkov telescope indicated the periodic emission of gamma rays of energy 10 to the 12th power eV, at 60.25 second period, from 2CG 195+4. The gamma ray flux at 99% confidence level is estimated to be 9.5 x 10 to 12 photons/sq cm/s.

  17. SVOM: a new mission for Gamma-Ray Bursts studies

    NASA Astrophysics Data System (ADS)

    Götz, Diego; SVOM Collaboration

    The French Space Agency (CNES) in collaboration with the Chinese National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS) are developing a new mission aiming at studying Gamma-Ray Bursts (GRBs) called SVOM (Space-based multi-band astronomical Variable Objects Monitor). The mission will consist of a set of space borne instruments and a set of ground based ones. The space borne instruments include two wide field of view gamma-ray instruments, and two narrow field ones operating in the X-ray and visible domains. The two gamma-ray instruments are a coded mask soft-gamma ray imager (4-250 keV), ECLAIRs, with a 2 sr field of view, which detects and localizes in real time GRB candidates, and a gamma-ray spectrometer (50 keV-5 MeV), GRM, with the same field of view as ECLAIRs, but without imaging capabilities. The narrow field instruments, used after an autonomous satellite slew for fine localization and afterglow studies, are MXT (0.2-10 keV) and VT (400-950 nm). The space borne instruments are complemented on ground by two dedicated robotic telescopes (GFTs), designed for position refinement and early afterglow studies, and a set of ground wide angle cameras (GWACs) that aim at monitoring the field of view of ECLAIRs with the goal of detecting the prompt optical emission of GRBs.

  18. Telescope for x ray and gamma ray studies in astrophysics

    NASA Technical Reports Server (NTRS)

    Weaver, W. D.; Desai, Upendra D.

    1993-01-01

    Imaging of x-rays has been achieved by various methods in astrophysics, nuclear physics, medicine, and material science. A new method for imaging x-ray and gamma-ray sources avoids the limitations of previously used imaging devices. Images are formed in optical wavelengths by using mirrors or lenses to reflect and refract the incoming photons. High energy x-ray and gamma-ray photons cannot be reflected except at grazing angles and pass through lenses without being refracted. Therefore, different methods must be used to image x-ray and gamma-ray sources. Techniques using total absorption, or shadow casting, can provide images in x-rays and gamma-rays. This new method uses a coder made of a pair of Fresnel zone plates and a detector consisting of a matrix of CsI scintillators and photodiodes. The Fresnel zone plates produce Moire patterns when illuminated by an off-axis source. These Moire patterns are deconvolved using a stepped sine wave fitting or an inverse Fourier transform. This type of coder provides the capability of an instantaneous image with sub-arcminute resolution while using a detector with only a coarse position-sensitivity. A matrix of the CsI/photodiode detector elements provides the necessary coarse position-sensitivity. The CsI/photodiode detector also allows good energy resolution. This imaging system provides advantages over previously used imaging devices in both performance and efficiency.

  19. Physics of Gamma Ray Burst Sources

    NASA Technical Reports Server (NTRS)

    Meszaros, Peter

    2004-01-01

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

  20. Physics of Gamma Ray Burst Sources

    NASA Technical Reports Server (NTRS)

    Meszaros, Peter

    2004-01-01

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

  1. Miniature gamma-ray camera for tumor localization

    SciTech Connect

    Lund, J.C.; Olsen, R.W.; James, R.B.; Cross, E.

    1997-08-01

    The overall goal of this LDRD project was to develop technology for a miniature gamma-ray camera for use in nuclear medicine. The camera will meet a need of the medical community for an improved means to image radio-pharmaceuticals in the body. In addition, this technology-with only slight modifications-should prove useful in applications requiring the monitoring and verification of special nuclear materials (SNMs). Utilization of the good energy resolution of mercuric iodide and cadmium zinc telluride detectors provides a means for rejecting scattered gamma-rays and improving the isotopic selectivity in gamma-ray images. The first year of this project involved fabrication and testing of a monolithic mercuric iodide and cadmium zinc telluride detector arrays and appropriate collimators/apertures. The second year of the program involved integration of the front-end detector module, pulse processing electronics, computer, software, and display.

  2. A New Type of Transient Luminous Events Produced by Terrestrial Gamma-ray Flashes

    NASA Astrophysics Data System (ADS)

    Xu, W.; Celestin, S. J.; Pasko, V. P.; Marshall, R. A.

    2016-12-01

    Discovered in 1994 by the Burst and Transient Source Experiment (BATSE) detector aboard the Compton Gamma-Ray Observatory [Fishman et al., Science, 264, 1313, 1994], Terrestrial Gamma-ray Flashes (TGFs) are high-energy photon bursts originating from the Earth's atmosphere characterized by their close association with thunderstorm activities. Since the discovery, TGFs have also been observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) [Smith et al., Science, 307, 1085, 2005], the Fermi Gamma-ray Space Telescope [Briggs et al., JGR, 115, A07323, 2010], and the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite [Marisaldi et al., JGR, 115, A00E13, 2010]. Space-borne measurements have revealed the temporal and spectral features of TGFs: typically lasting from fractions of to a few milliseconds, having a fluence of fractions of photons/cm2, and exhibiting a hard energy spectra extending up to a few tens of MeVs [Dwyer et al., Space Sci. Rev., 173, 133, 2012]. Moreover, detailed analyses of radio emissions have pointed out the close correlation between TGFs and the initial development stages of normal polarity intra-cloud lightning that transports negative charge upward (+IC) [e.g., Lu et al., GRL, 37, L11806, 2010; JGR, 116, A03316, 2011]. In this work, we show that, while TGFs pass through the atmosphere, the large quantities of energetic electrons knocked out during collisions of gamma-rays with air molecules can generate significant amount of excited species of neutral and ionized nitrogen molecules, thereby leading to production of a new type of transient luminous events (TLEs). The spectroscopic and morphological features of this predicted luminous phenomenon have been theoretically quantified in the framework of Monte Carlo simulations. Considering the measurability of this type of events and its close relation with TGFs, corresponding measurements would provide a novel perspective to investigate TGFs, as well as the initial

  3. Sky and Elemental Planetary Mapping Via Gamma Ray Emissions

    NASA Technical Reports Server (NTRS)

    Roland, John M.

    2011-01-01

    Low-energy gamma ray emissions ((is) approximately 30keV to (is) approximately 30MeV) are significant to astrophysics because many interesting objects emit their primary energy in this regime. As such, there has been increasing demand for a complete map of the gamma ray sky, but many experiments to do so have encountered obstacles. Using an innovative method of applying the Radon Transform to data from BATSE (the Burst And Transient Source Experiment) on NASA's CGRO (Compton Gamma-Ray Observatory) mission, we have circumvented many of these issues and successfully localized many known sources to 0.5 - 1 deg accuracy. Our method, which is based on a simple 2-dimensional planar back-projection approximation of the inverse Radon transform (familiar from medical CAT-scan technology), can thus be used to image the entire sky and locate new gamma ray sources, specifically in energy bands between 200keV and 2MeV which have not been well surveyed to date. Samples of these results will be presented. This same technique can also be applied to elemental planetary surface mapping via gamma ray spectroscopy. Due to our method's simplicity and power, it could potentially improve a current map's resolution by a significant factor.

  4. Evaluate cement with radioactive tracers, directional gamma ray logs

    SciTech Connect

    1996-07-01

    Use of radioactive tracers to evaluate hydraulic fractures has recently been extended through the use of directional gamma ray measurements. The directional gamma ray logging tool determines the azimuthal direction of gamma rays from radioactive isotope-tagged fracture proppants to estimate the fracture direction in well-controlled circumstances. The technology also provides new ways of evaluating primary and squeeze cement jobs by enhancing information from directional gamma ray data with advanced image processing techniques. By tagging the cement with a uniform quantity per unit volume of radioactivity, different levels of gamma ray log response must be attributed to variances in cement quality. Cement evaluation with tracers can help detect: thin cement sheaths; light-weight or low compressive strength cements where the acoustic impedance is near that of water; gas cut cement where the acoustic signal is attenuated; wells with microannulus that cannot be pressured to obtain valid log data; poor casing centralization; and multiple cement stage placement. The paper describes the logging tool, operational procedures, and a log example.

  5. Sky and Elemental Planetary Mapping Via Gamma Ray Emissions

    NASA Technical Reports Server (NTRS)

    Roland, John M.

    2011-01-01

    Low-energy gamma ray emissions ((is) approximately 30keV to (is) approximately 30MeV) are significant to astrophysics because many interesting objects emit their primary energy in this regime. As such, there has been increasing demand for a complete map of the gamma ray sky, but many experiments to do so have encountered obstacles. Using an innovative method of applying the Radon Transform to data from BATSE (the Burst And Transient Source Experiment) on NASA's CGRO (Compton Gamma-Ray Observatory) mission, we have circumvented many of these issues and successfully localized many known sources to 0.5 - 1 deg accuracy. Our method, which is based on a simple 2-dimensional planar back-projection approximation of the inverse Radon transform (familiar from medical CAT-scan technology), can thus be used to image the entire sky and locate new gamma ray sources, specifically in energy bands between 200keV and 2MeV which have not been well surveyed to date. Samples of these results will be presented. This same technique can also be applied to elemental planetary surface mapping via gamma ray spectroscopy. Due to our method's simplicity and power, it could potentially improve a current map's resolution by a significant factor.

  6. Europe's space camera unmasks a cosmic gamma-ray machine

    NASA Astrophysics Data System (ADS)

    1996-11-01

    The new-found neutron star is the visible counterpart of a pulsating radio source, Pulsar 1055-52. It is a mere 20 kilometres wide. Although the neutron star is very hot, at about a million degrees C, very little of its radiant energy takes the form of visible light. It emits mainly gamma-rays, an extremely energetic form of radiation. By examining it at visible wavelengths, astronomers hope to figure out why Pulsar 1055-52 is the most efficient generator of gamma-rays known so far, anywhere the Universe. The Faint Object Camera found Pulsar 1055-52 in near ultraviolet light at 3400 angstroms, a little shorter in wavelength than the violet light at the extremity of the human visual range. Roberto Mignani, Patrizia Caraveo and Giovanni Bignami of the Istituto di Fisica Cosmica in Milan, Italy, report its optical identification in a forthcoming issue of Astrophysical Journal Letters (1 January 1997). The formal name of the object is PSR 1055-52. Evading the glare of an adjacent star The Italian team had tried since 1988 to spot Pulsar 1055-52 with two of the most powerful ground-based optical telescopes in the Southern Hemisphere. These were the 3.6-metre Telescope and the 3.5-metre New Technology Telescope of the European Southern Observatory at La Silla, Chile. Unfortunately an ordinary star 100,000 times brighter lay in almost the same direction in the sky, separated from the neutron star by only a thousandth of a degree. The Earth's atmosphere defocused the star's light sufficiently to mask the glimmer from Pulsar 1055-52. The astronomers therefore needed an instrument in space. The Faint Object Camera offered the best precision and sensitivity to continue the hunt. Devised by European astronomers to complement the American wide field camera in the Hubble Space Telescope, the Faint Object Camera has a relatively narrow field of view. It intensifies the image of a faint object by repeatedly accelerating electrons from photo-electric films, so as to produce

  7. Gamma-ray astronomy: Nuclear transition region

    NASA Technical Reports Server (NTRS)

    Chupp, E. L.

    1976-01-01

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

  8. Gamma-ray astronomy: Nuclear transition region

    NASA Technical Reports Server (NTRS)

    Chupp, E. L.

    1976-01-01

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

  9. Optical Emissions Associated with Terrestrial Gamma-ray Flashes

    NASA Astrophysics Data System (ADS)

    Xu, W.; Celestin, S. J.; Pasko, V. P.

    2013-12-01

    Terrestrial Gamma-ray Flashes (TGFs) are high-energy photon bursts originating from the Earth's atmosphere. After their discovery in 1994 by the Burst and Transient Source Experiment (BATSE) detector aboard the Compton Gamma-Ray Observatory [Fishman et al., Science, 264, 1313, 1994], this phenomenon has been further observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) [Smith et al., Science, 307, 1085, 2005], the Fermi Gamma-ray Space Telescope [Briggs et al., JGR, 115, A07323, 2010] and the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite [Marisaldi et al., JGR, 115, A00E13, 2010]. Measurements have correlated TGFs with initial development stages of normal polarity intracloud lightning that transports negative charge upward (+IC) [e.g., Lu et al., GRL, 37, L11806, 2010; JGR, 116, A03316, 2011]. Moreover, Østgaard et al. [GRL, 40, 2423, 2013] have recently reported, for the first time, space-based observations of optical emissions from TGF-associated IC lightning flashes. The purpose of the present work is to quantify the intensities of optical emissions resulting from the excitation of air molecules produced by conventional streamer discharges in negative corona flashes of stepping negative leaders and by the large amount of electrons involved in TGF events based on two production mechanisms: relativistic runaway electron avalanches (RREAs) [Dwyer and Smith, GRL, 32, L22804, 2005] and production of runaway electrons by high-potential +IC lightning leaders [e.g., Celestin and Pasko, JGR, 116, A03315, 2011; Xu et al., GRL, 39, L08801, 2012]. We employ a Monte Carlo model to simulate the acceleration of electrons in the energy range from sub-eV to GeV in either large-scale homogeneous electric field sustaining RREAs or highly inhomogeneous electric field produced around the lightning leader tip region. With the knowledge of the electron energy distribution function, a model similar to that described in [Liu and Pasko, JGR, 109, A

  10. Optical Emissions Associated with Terrestrial Gamma-ray Flashes

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Celestin, Sebastien; Pasko, Victor

    2015-04-01

    Terrestrial Gamma-ray Flashes (TGFs) are high-energy photon bursts originating from the Earth's atmosphere. After their discovery in 1994 by the Burst and Transient Source Experiment (BATSE) detector aboard the Compton Gamma-Ray Observatory [Fishman et al., Science, 264, 1313, 1994], this phenomenon has been further observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) [Smith et al., Science, 307, 1085, 2005], the Fermi Gamma-ray Space Telescope [Briggs et al., JGR, 115, A07323, 2010] and the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite [Marisaldi et al., JGR, 115, A00E13, 2010]. Measurements have correlated TGFs with initial development stages of normal polarity intracloud lightning that transports negative charge upward (+IC) [e.g., Lu et al., GRL, 37, L11806, 2010; JGR, 116, A03316, 2011]. Moreover, Østgaard et al. [GRL, 40, 2423, 2013] have recently reported, for the first time, space-based observations of optical emissions from TGF-associated IC lightning flashes, and Dwyer et al. [GRL, 40, 4067, 2013] recently quantified optical emissions associated with TGFs based on assumption that these emissions are similar to those produced by extensive air showers. In the present study, we quantify optical emissions resulting from the excitation of air molecules produced by the large population of electrons involved in TGF events based on two possible production mechanisms: relativistic runaway electron avalanches (RREAs) [Dwyer and Smith, GRL, 32, L22804, 2005] and acceleration of thermal runaway electrons produced by high-potential intra-cloud lightning leaders [e.g., Celestin and Pasko, JGR, 116, A03315, 2011; Xu et al., GRL, 39, L08801, 2012]. Using Monte Carlo simulations, we show that electron energy distributions established from these two production mechanisms are inherently different over the full energy range, and also substantially different from those produced in extensive air showers. Moreover, we show that TGFs are

  11. Gamma ray observatory productivity showcase

    NASA Technical Reports Server (NTRS)

    Davis, R. L.; Molgaard, D. A.

    1985-01-01

    The Gamma Ray Observatory (GRO) Program has been proclaimed to be the showcase productivity program for NASA and TRW. Among the multiple disciplines of a large-scale program, there is opportunity and need for improved efficiency, effectiveness, and reduction in the cost of doing business. The efforts and tools that will or have been implemented to achieve this end are described. Since the GRO Program is mainly an engineering program with the build of one satellite, the primary emphasis is placed on improving the efficiency and quality of management and engineering.

  12. COMPACT, TUNABLE COMPTON SCATTERING GAMMA-RAY SOURCES

    SciTech Connect

    Hartemann, F V; Albert, F; Anderson, G G; Anderson, S G; Bayramian, A J; Betts, S M; Chu, T S; Cross, R R; Ebbers, C A; Fisher, S E; Gibson, D J; Ladran, A S; Marsh, R A; Messerly, M J; O'Neill, K L; Semenov, V A; Shverdin, M Y; Siders, C W; McNabb, D P; Barty, C J; Vlieks, A E; Jongewaard, E N; Tantawi, S G; Raubenheimer, T O

    2009-08-20

    Recent progress in accelerator physics and laser technology have enabled the development of a new class of gamma-ray light sources based on Compton scattering between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development at LLNL. High-brightness, relativistic electron bunches produced by the linac interact with a Joule-class, 10 ps laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. The source will be used to excite nuclear resonance fluorescence lines in various isotopes; applications include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented.

  13. Observations of Gamma-Ray Bursts with INTEGRAL

    SciTech Connect

    McGlynn, S.; Hanlon, L.; McBreen, B.; Foley, S.; French, J.; Melady, G.; McBreen, S.; Kienlin, A. von; Preece, R.

    2006-05-19

    The INTEGRAL satellite has two coded-mask {gamma}-ray instruments; the spectrometer (SPI) which is optimised for high resolution {gamma}-ray line spectroscopy, and the imager (IBIS) which can localise GRBs to a precision of a few arcminutes. INTEGRAL was launched 3 years ago and the INTEGRAL Burst Alert System (IBAS) has detected 33 long duration GRBs, the most intense burst by far being GRB 041219 which also had prompt optical emission associated with it. The {gamma}-ray properties of some of these bursts are presented with particular emphasis on spectral results. A subset of 6 GRBs were observed with XMM-Newton and a selection of these results is presented. New results from recent GRBs are also discussed.

  14. STS-37 Gamma Ray Observatory (GRO) grappled by RMS

    NASA Image and Video Library

    1991-04-07

    Backdropped against the Earth's surface, the Gamma Ray Observatory (GRO) with its solar array (SA) panels deployed is grappled by the remote manipulator system (RMS) during STS-37 systems checkout. GRO's four complement instruments are visible: the Energetic Gamma Ray Experiment Telescope (EGRET) (at the bottom); the Imaging Compton Telescope (COMPTEL) (center); the Oriented Scintillation Spectrometer Experiment (OSSE) (top); and Burst and Transient Source Experiment (BATSE) (on four corners). The view was taken by STS-37 crew through an aft flight deck overhead window.

  15. STS-37 Gamma Ray Observatory (GRO) grappled by RMS

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Backdropped against the Earth's surface, the Gamma Ray Observatory (GRO) with its solar array (SA) panels deployed is grappled by the remote manipulator system (RMS) during STS-37 systems checkout. GRO's four complement instruments are visible: the Energetic Gamma Ray Experiment Telescope (EGRET) (at the bottom); the Imaging Compton Telescope (COMPTEL) (center); the Oriented Scintillation Spectrometer Experiment (OSSE) (top); and Burst and Transient Source Experiment (BATSE) (on four corners). The view was taken by STS-37 crew through an aft flight deck overhead window.

  16. STS-37 Gamma Ray Observatory (GRO) grappled by RMS

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Backdropped against the Earth's expansive desert in the Mid East, the Gamma Ray Observatory (GRO) with its solar array (SA) panels deployed is grappled by the remote manipulator system (RMS) during STS-37 systems checkout. GRO's four complement instruments are visible: the Energetic Gamma Ray Experiment Telescope (EGRET) (at the bottom); the Imaging Compton Telescope (COMPTEL) (center); the Oriented Scintillation Spectrometer Experiment (OSSE) (top); and Burst and Transient Source Experiment (BATSE) (on four corners). The view was taken by STS-37 crew through an aft flight deck overhead window.

  17. Observation of Multi-TeV Gamma Rays from the Crab Nebula using the Tibet Air Shower Array.

    PubMed

    Amenomori; Ayabe; Cao; Danzengluobu; Ding; Feng; Fu; Guo; He; Hibino; Hotta; Huang; Huo; Izu; Jia; Kajino; Kasahara; Katayose; Labaciren; Li; Lu; Lu; Luo; Meng; Mizutani; Mu; Nanjo; Nishizawa; Ohnishi; Ohta; Ouchi; Ren; Saito; Sakata; Sasaki; Shi; Shibata; Shiomi; Shirai; Sugimoto; Taira; Tan; Tateyama; Torii; Utsugi; Wang; Wang; Xu; Yamamoto; Yu; Yuan; Yuda; Zhang; Zhang; Zhang; Zhang; Zhang; Zhaxisangzhu; Zhaxiciren; Zhou; Collaboration)

    1999-11-10

    The Tibet experiment, operating at Yangbajing (4300 m above sea level), is the lowest energy air shower array, and the new high-density array constructed in 1996 is sensitive to gamma-ray air showers at energies as low as 3 TeV. With this new array, the Crab Nebula was observed in multi-TeV gamma-rays and a signal was detected at the 5.5 sigma level. We also obtained the energy spectrum of gamma-rays in the energy region above 3 TeV which partially overlaps those observed with imaging atmospheric Cerenkov telescopes. The Crab spectrum observed in this energy region can be represented by the power-law fit dJ&parl0;E&parr0;&solm0;dE=&parl0;4.61+/-0.90&parr0;x10-12&parl0;E&solm0;3 TeV&parr0;-2.62+/-0.17 cm-2 s-1 TeV-1. This is the first observation of gamma-ray signals from point sources with a conventional air shower array using scintillation detectors.

  18. Simulated gamma-ray pulse profile of the Crab pulsar with the Cherenkov Telescope Array

    NASA Astrophysics Data System (ADS)

    Burtovoi, A.; Zampieri, L.

    2016-07-01

    We present simulations of the very high energy (VHE) gamma-ray light curve of the Crab pulsar as observed by the Cherenkov Telescope Array (CTA). The CTA pulse profile of the Crab pulsar is simulated with the specific goal of determining the accuracy of the position of the interpulse. We fit the pulse shape obtained by the Major Atmospheric Gamma-Ray Imaging Cherenkov (MAGIC) telescope with a three-Gaussian template and rescale it to account for the different CTA instrumental and observational configurations. Simulations are performed for different configurations of CTA and for the ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) mini-array. The northern CTA configuration will provide an improvement of a factor of ˜3 in accuracy with an observing time comparable to that of MAGIC (73 h). Unless the VHE spectrum above 1 TeV behaves differently from what we presently know, unreasonably long observing times are required for a significant detection of the pulsations of the Crab pulsar with the high-energy-range sub-arrays. We also found that an independent VHE timing analysis is feasible with Large Size Telescopes. CTA will provide a significant improvement in determining the VHE pulse shape parameters necessary to constrain theoretical models of the gamma-ray emission of the Crab pulsar. One of such parameters is the shift in phase between peaks in the pulse profile at VHE and in other energy bands that, if detected, may point to different locations of the emission regions.

  19. The Fermi Gamma-Ray Space Telescope

    NASA Technical Reports Server (NTRS)

    Thompson, Dave; McEnery, Julie

    2011-01-01

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

  20. PROGRESS ON MARGIE, A GAMMA-RAY BURST ULTRA-LONG DURATION BALLOON MISSION

    SciTech Connect

    D. BAND; ET AL

    2001-02-01

    We are designing the Minute of Arc Resolution Gamma-ray Imaging Experiment (MARGIE) as a 100 day Ultra Long Duration Balloon (ULDB) mission to: (1) detect and localize gamma-ray bursts; and (2) survey the hard X-ray sky. Major advances in designing the CZT detectors increase the sensitivity to higher energy. Design of the gondola has also progressed.

  1. Very high energy gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Grindlay, J. E.

    1976-01-01

    Recent results in ground based very high energy gamma ray astronomy are reviewed. The various modes of the atmospheric Cerenkov technique are described, and the importance of cosmic ray rejection methods is stressed. The positive detections of the Crab pulsar that suggest a very flat spectrum and time-variable pulse phase are discussed. Observations of other pulsars (particularly Vela) suggest these features may be general. Evidence that a 4.8 hr modulated effect was detected from Cyg X-3 is strengthened in that the exact period originally proposed agrees well with a recent determination of the X-ray period. The southern sky observations are reviewed, and the significance of the detection of an active galaxy (NGC 5128) is considered for source models and future observations.

  2. GAMCIT: A gamma ray burst detector

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  3. 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.

  4. Understanding Doppler Broadening of Gamma Rays

    SciTech Connect

    Rawool-Sullivan, Mohini; Sullivan, John P.

    2014-07-03

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

  5. An improved time of flight gamma-ray telescope to monitor diffuse gamma-ray in the energy range 5 MeV - 50 MeV

    NASA Technical Reports Server (NTRS)

    Dacostafereiraneri, A.; Bui-Van, A.; Lavigne, J. M.; Sabaud, C.; Vedrenne, G.; Agrinier, B.; Gouiffes, C.

    1985-01-01

    A time of flight measuring device is the basic triggering system of most of medium and high energy gamma-ray telescopes. A simple gamma-ray telescope has been built in order to check in flight conditions the functioning of an advanced time of flight system. The technical ratings of the system are described. This telescope has been flown twice with stratospheric balloons, its axis being oriented at various Zenital directions. Flight results are presented for diffuse gamma-rays, atmospheric secondaries, and various causes of noise in the 5 MeV-50 MeV energy range.

  6. Gamma ray bursts inner engines

    NASA Astrophysics Data System (ADS)

    Staff, Jan Erling

    Long gamma ray bursts (GRBs) are brief durations of intense, highly variable gamma radiation coming from point like sources in the Universe. GRBs have been seen in connection with Type 1c supernovae. Their isotropical equivalent energy released in gamma rays is in some cases above 10 54 erg, but the engine creating this energy is unknown. In this thesis several models for the engine are explored. It is shown that cannonballs can in principle form from hyperaccreting disks, however the cannonball model requires almost all supernovae to create cannonballs, and our finding then implies that a hyperaccreting disk is a natural consequence in most supernovae, a notion which remains to be confirmed. General relativistic magnetohydrodynamic simulations of the collapsar model have been performed. Within our setup we found that the duration of the collapsar is too short to explain GRBs, and the energy output is not sufficient. Also the supernova connection could not be explained. I find that the more likely candidate for the GRB engine is an accreting quark star. A quark star has a maximum mass, if the mass increases above this the star will collapse to a black hole. This allows for a two stage engine that might be able to explain features observed in GRBs.

  7. Gamma-ray burst populations

    NASA Astrophysics Data System (ADS)

    Virgili, Francisco Javier

    Over the last fifty years the field of gamma-ray bursts has shown incredible growth, but the amassing of data has also left observers and theorists alike wondering about some of the basic questions surrounding these phenomena. Additionally, these events show remarkable individuality and extrema, ranging in redshift throughout the observable universe and over ten orders of magnitude in energy. This work focuses on analyzing groups of bursts that are different from the general trend and trying to understand whether these bursts are from different intrinsic populations and if so, what can be said about their progenitors. This is achieved through numerical Monte Carlo simulations and statistical inference in conjunction with current GRB observations. Chapter 1 gives a general introduction of gamma-ray burst theory and observations in a semi-historical context. Chapter 2 provides an introduction to the theory and practical issues surrounding the numerical simulations and statistics. Chapters 3--5 are each dedicated to a specific problem relating to a different type of GRB population: high-luminosity v. low-luminosity bursts, constraints from high-redshift bursts, and Type I v. Type II bursts. Chapter 6 follows with concluding remarks.

  8. Dark gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Brdar, Vedran; Kopp, Joachim; Liu, Jia

    2017-03-01

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

  9. Hard gamma ray emission from blazars

    NASA Technical Reports Server (NTRS)

    Marscher, Alan P.; Bloom, Steven D.

    1992-01-01

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

  10. Gamma-ray irradiated polymer optical waveguides

    SciTech Connect

    Lai, C.-C.; Wei, T.-Y.; Chang, C.-Y.; Wang, W.-S.; Wei, Y.-Y.

    2008-01-14

    Optical waveguides fabricated by gamma-ray irradiation on polymer through a gold mask are presented. The gamma-ray induced index change is found almost linearly dependent on the dose of the irradiation. And the measured propagation losses are low enough for practical application. Due to the high penetrability of gamma ray, uniform refractive index change in depth can be easily achieved. Moreover, due to large-area printing, the uniformity of waveguide made by gamma-ray irradiation is much better than that by e-beam direct writing.

  11. Low-level gamma-ray spectrometry

    SciTech Connect

    Brodzinski, R.L.

    1990-10-01

    Low-level gamma-ray spectrometry generally equates to high-sensitivity gamma-ray spectrometry that can be attained by background reduction, selective signal identification, or some combination of both. Various methods for selectively identifying gamma-ray events and for reducing the background in gamma-ray spectrometers are given. The relative magnitude of each effect on overall sensitivity and the relative cost'' for implementing them are given so that a cost/benefit comparison can be made and a sufficiently sensitive spectrometer system can be designed for any application without going to excessive or unnecessary expense. 10 refs., 8 figs.

  12. The Mystery of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2004-01-01

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

  13. 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.

  14. Terrestrial gamma-ray flashes produced by energetic electrons during the stepping of lightning leaders

    NASA Astrophysics Data System (ADS)

    Celestin, S. J.; Xu, W.; Pasko, V. P.

    2011-12-01

    Terrestrial gamma-ray flashes (TGFs) are bursts of high-energy photons originating from the Earth's atmosphere in association with thunderstorm activity. TGFs were serendipitously discovered by BATSE detector aboard the Compton Gamma-Ray Observatory originally launched to perform observations of celestial gamma-ray sources [Fishman et al., Science, 264, 1313, 1994]. These events have also been detected by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite [Smith et al., Science, 307, 1085, 2005], the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite [Marisaldi et al., JGR, 115, A00E13, 2010], and the Fermi Gamma-ray Space Telescope [Briggs et al., JGR, 115, A07323, 2010]. Moreover, measurements have correlated TGFs with initial development stages of normal polarity intracloud lightning that transports negative charge upward (+IC) [Lu et al., JGR, 116, A03316, 2011]. Photon spectra corresponding to well-established model of relativistic runaway electron avalanches (RREAs) usually provide a very good agreement with satellite observations [Dwyer and Smith, GRL, 32, L22804, 2005]. However, it has been suggested that long unbranched +IC lightning leaders could produce a sufficient number of energetic electrons to explain TGFs without invoking further amplification in RREAs [Celestin and Pasko, JGR, 116, A03315, 2011]. In this work, we use Monte Carlo models to study the photon spectra at low-orbit satellite altitudes associated with energetic electrons produced during the negative corona flashes of stepping negative leaders in +IC discharges. We show that the obtained spectra agree with current satellite measurements, which suggests that TGFs can be produced directly by lightning discharges.

  15. First limits on the very-high energy gamma-ray afterglow emission of a fast radio burst. H.E.S.S. observations of FRB 150418

    NASA Astrophysics Data System (ADS)

    H.E.S.S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Andersson, T.; Angüner, E. O.; Arakawa, M.; Arrieta, M.; Aubert, P.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Becker Tjus, J.; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Büchele, M.; Bulik, T.; Capasso, M.; Carr, J.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Chrétien, M.; Coffaro, M.; Colafrancesco, S.; Cologna, G.; Condon, B.; Conrad, J.; Cui, Y.; Davids, I. D.; Decock, J.; Degrange, B.; Deil, C.; Devin, J.; Dewilt, P.; Dirson, L.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O.'c.; Dutson, K.; Dyks, J.; Edwards, T.; Egberts, K.; Eger, P.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Funk, S.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Goyal, A.; Grondin, M.-H.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holler, M.; Horns, D.; Ivascenko, A.; Iwasaki, H.; Jacholkowska, A.; Jamrozy, M.; Janiak, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jogler, T.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katsuragawa, M.; Katz, U.; Kerszberg, D.; Khangulyan, D.; Khélifi, B.; Kieffer, M.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Kraus, M.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lees, J.-P.; Lefaucheur, J.; Lefranc, V.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morå, K.; Moulin, E.; Murach, T.; Nakashima, S.; de Naurois, M.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Öttl, S.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Piel, Q.; Pita, S.; Poon, H.; Prokhorov, D.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reimer, A.; Reimer, O.; Renaud, M.; de Los Reyes, R.; Richter, S.; Rieger, F.; Romoli, C.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Saito, S.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Seglar-Arroyo, M.; Settimo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Simoni, R.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stycz, K.; Sushch, I.; Takahashi, T.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tsuji, N.; Tuffs, R.; Uchiyama, Y.; van der Walt, D. J.; van Eldik, C.; van Rensburg, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zanin, R.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Żywucka, N.; Superb Collaboration; Jankowski, F.; Keane, E. F.; Petroff, E.

    2017-01-01

    Aims: Following the detection of the fast radio burst FRB150418 by the SUPERB project at the Parkes radio telescope, we aim to search for very-high energy gamma-ray afterglow emission. Methods: Follow-up observations in the very-high energy gamma-ray domain were obtained with the H.E.S.S. imaging atmospheric Cherenkov telescope system within 14.5 h of the radio burst. Results: The obtained 1.4 h of gamma-ray observations are presented and discussed. At the 99% C.L. we obtained an integral upper limit on the gamma-ray flux of Φγ(E > 350 GeV) < 1.33 × 10-8 m-2 s-1. Differential flux upper limits as function of the photon energy were derived and used to constrain the intrinsic high-energy afterglow emission of FRB 150418. Conclusions: No hints for high-energy afterglow emission of FRB 150418 were found. Taking absorption on the extragalactic background light into account and assuming a distance of z = 0.492 based on radio and optical counterpart studies and consistent with the FRB dispersion, we constrain the gamma-ray luminosity at 1 TeV to L < 5.1 × 1047 erg/s at 99% C.L.

  16. Detection of TeV Gamma-Ray Emission from the Cygnus Region of the Galaxy with Milagro Using a New Background Rejection Technique

    SciTech Connect

    Abdo, A. A.

    2006-10-27

    Milagro is a TeV gamma-ray observatory that utilizes a large water Cherenkov detector to observe extensive air showers (EAS) produced by high energy particles impacting the Earth's atmosphere. Milagro's distinct advantage compared to other TeV gamma-ray detectors is that it views a wide field (2 steradian overhead sky) and it continuously operates (> 90% live time ). These factors give Milagro the potential for discovery of new sources with unknown positions and times, such as gamma-ray bursts, flaring AGNs, and observation of diffuse and extended sources like the Galactic plane or large supernova remnants. Here we present a new technique for improving background rejection in Milagro as well as a gamma-ray image of the Cygnus region at energies near 12.5 TeV. We report the detection of both an extended source and a large area of diffuse gamma-ray emission from this region of the galaxy. This new extended source has an extent of 0.32 {+-} 0.12 degrees and an integral flux above 12.5 TeV of (1.71 {+-} 0.24stat {+-} 0.34sys) x 10-13cm-2s-1 assuming a differential source spectrum of E-2.6. The best-fit location for the source is RA = 304.66 {+-} 0.13stat {+-} 0.25sys degrees and declination 36.96 {+-} 0.08stat {+-} 0.2sys degrees.

  17. Development of a pixelated CdTe detector module for a hard-x and gamma-ray imaging spectrometer application

    NASA Astrophysics Data System (ADS)

    Galvèz, J.-L.; Hernanz, M.; Álvarez, L.; Artigues, B.; Álvarez, J.-M.; Ullán, M.; Lozano, M.; Pellegrini, G.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

    2016-07-01

    Stellar explosions are relevant and interesting astrophysical phenomena. Since long ago we have been working on the characterization of novae and supernovae in X and gamma-rays, with the use of space missions. We have also been involved in feasibility studies of future instruments in the energy range from several keV up to a few MeV, in collaboration with other research institutes. High sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators, e.g., Supernovae and Classical Novae. In order to fulfil the combined requirement of high detection efficiency with good spatial and energy resolution, an initial module prototype based on CdTe pixel detectors is being developed. The detector dimensions are 12.5mm x 12.5mm x 2mm with a pixel pitch of 1mm x 1mm. Two kinds of CdTe pixel detectors with different contacts have been tested: ohmic and Schottky. Each pixel is bump bonded to a fanout board made of Sapphire substrate and routed to the corresponding input channel of the readout VATAGP7.1 ASIC, to measure pixel position and pulse height for each incident gamma-ray photon. The study is complemented by the simulation of the CdTe module performance using the GEANT 4 and MEGALIB tools, which will help us to optimise the detector design. We will report on the spectroscopy characterisation of the CdTe detector module as well as the study of charge sharing.

  18. Constraining faint terrestrial gamma-ray flashes with stacking analyses

    NASA Astrophysics Data System (ADS)

    Smith, D. M.; Buzbee, P.; Aron-Dine, S.; Kelley, N. A.; Holzworth, R. H., II; Hutchins, M. L.; Dwyer, J. R.

    2014-12-01

    We searched for gamma-ray emission from lightning using a satellite (the Reuven Ramaty Solar Spectroscopic Imager (RHESSI)) and an instrument on an aircraft (the Airborne Detector for Energetic Lightning Emissions (ADELE)). Both instruments have detected terrestrial gamma-ray flashes (TGFs) via direct searches for statistically significant bursts of gamma-rays. In our new analysis, we instead identified times when the instruments were near known lightning discharges based on VLF radio data (from the Worldwide Lightning Location Network (WWLLN) in the case of RHESSI and from three North American networks in the case of ADELE). We then stacked together the gamma-ray signals for each instrument, with times adjusted to be relative to the time of radio emission for each discharge (corrected for light propagation time to the spacecraft in the case of RHESSI). The resulting stacked gamma-ray time profile is sensitive to an average level of gamma-ray emission far lower than what can be recognized above background for a single TGF. The summed signal from small, untriggered TGFs is remarkably weak, and preliminary evidence suggests that it comes mostly from distant, bright TGFs observed outside the main bremsstrahlung beam, not from a population of subluminous TGFs near the spacecraft. Under the assumption of a broken power-law differential distribution of TGF intensities, we find that the index must break (harden or cut off) just below the current sensitivity limit of satellites like RHESSI and Fermi, and that less than 1% of lightning can produce a TGF that belongs to the same distribution as those that are observable.

  19. AGILE and Gamma-Ray Bursts

    SciTech Connect

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

    2006-05-19

    AGILE is a Scientific Mission dedicated to high-energy astrophysics supported by ASI with scientific participation of INAF and INFN. The AGILE instrument is designed to simultaneously detect and image photons in the 30 MeV - 50 GeV and 15 - 45 keV energy bands with excellent imaging and timing capabilities, and a large field of view covering {approx} 1/5 of the entire sky at energies above 30 MeV. A CsI calorimeter is capable of GRB triggering in the energy band 0.3-50 MeV. The broadband detection of GRBs and the study of implications for particle acceleration and high energy emission are primary goals of th emission. AGILE can image GRBs with 2-3 arcminutes error boxes in the hard X-ray range, and provide broadband photon-by photon detection in the 15-45 keV, 03-50 MeV, and 30 MeV-30 GeV energy ranges. Microsecond on-board photon tagging and a {approx} 100 microsecond gamma-ray detection deadtime will be crucial for fast GRB timing. On-board calculated GRB coordinates and energy fluxes will be quickly transmitted to the ground by an ORBCOMM transceiver. AGILE have recently (December 2005) completed its gamma-ray calibration. It is now (January 2006) undergoing satellite integration and testing. The PLSV launch is planned in early 2006. AGILE is then foreseen to be fully operational during the summer of 2006. It will be the only mission entirely dedicated to high-energy astrophysics above 30 MeV during the period mid-2006/mid-2007.

  20. Gamma-rays from Dark Matter Annihilation in the Central Region of the Galaxy

    SciTech Connect

    Serpico, Pasquale Dario; Hooper, Dan; /Fermilab /Chicago U., Astron. Astrophys. Ctr.

    2009-02-01

    In this article, we review the prospects for the FERMI satellite (formerly known as GLAST) to detect gamma-rays from dark matter annihilations in the Central Region of the Milky Way, in light of the recent observations and discoveries of Imaging Atmospheric Cherenkov Telescopes. While the existence of significant astrophysical backgrounds in this part of the sky limits FERMI's discovery potential to some degree, this can be mitigated by exploiting the peculiar energy spectrum and angular distribution of the dark matter annihilation signal relative to those of astrophysical backgrounds.

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

    SciTech Connect

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

    2014-11-15

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

  2. The AGILE Mission and Gamma-Ray Bursts

    SciTech Connect

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

    2007-05-01

    The AGILE Mission 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 at the beginning of 2007 and it will provide crucial data for the study of Active Galactic Nuclei, Gamma-Ray Bursts, unidentified gamma-ray sources, Galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing. The AGILE instrument is designed to simultaneously detect and image photons in the 30 MeV - 50 GeV and 15 - 45 keV energy bands with excellent imaging and timing capabilities, and a large field of view covering {approx} 1/5 of the entire sky at energies above 30 MeV. A CsI calorimeter is capable of GRB triggering in the energy band 0.3-50 MeV. The broadband detection of GRBs and the study of implications for particle acceleration and high energy emission are primary goals of the mission. AGILE can image GRBs with 2-3 arcminute error boxes in the hard X-ray range, and provide broadband photon-by photon detection in the 15-45 keV, 03-50 MeV, and 30 MeV-30 GeV energy ranges. Microsecond on-board photon tagging and a {approx} 100 microsecond gamma-ray detection deadtime will be crucial for fast GRB timing. On-board calculated GRB coordinates and energy fluxes will be quickly transmitted to the ground by an ORBCOMM transceiver. AGILE is now (January 2007) undergoing final satellite integration and testing. The PLS V launch is planned in spring 2007. AGILE is then foreseen to be fully operational during the summer of 2007.

  3. The Most Remote Gamma-Ray Burst

    NASA Astrophysics Data System (ADS)

    2000-10-01

    seconds is larger than that of the Sun during its entire life time (about 10,000 million years). "Gamma-ray bursts" are in fact by far the most powerful events since the Big Bang that are known in the Universe. While there are indications that gamma-ray bursts originate in star-forming regions within distant galaxies, the nature of such explosions remains a puzzle. Recent observations with large telescopes, e.g. the measurement of the degree of polarization of light from a gamma-ray burst in May 1999 with the VLT ( ESO PR 08/99), are now beginning to cast some light on this long-standing mystery. The afterglow of GRB 000131 ESO PR Photo 28a/00 ESO PR Photo 28a/00 [Preview - JPEG: 400 x 475 pix - 41k] [Normal - JPEG: 800 x 949 pix - 232k] [Full-Res - JPEG: 1200 x 1424 pix - 1.2Mb] ESO PR Photo 28b/00 ESO PR Photo 28b/00 [Preview - JPEG: 400 x 480 pix - 67k] [Normal - JPEG: 800 x 959 pix - 288k] [Full-Res - JPEG: 1200 x 1439 pix - 856k] Caption : PR Photo 28a/00 is a colour composite image of the sky field around the position of the gamma-ray burst GRB 000131 that was detected on January 31, 2000. It is based on images obtained with the ESO Very Large Telescope at Paranal. The object is indicated with an arrow, near a rather bright star (magnitude 9, i.e., over 1 million times brighter than the faintest objects visible on this photo). This and other bright objects in the field are responsible for various unavoidable imaging effects, caused by optical reflections (ring-shaped "ghost images", e.g. to the left of the brightest star) and detector saturation effects (horizontal and vertical straight lines and coloured "coronae" at the bright objects, and areas of "bleeding", e.g. below the bright star). PR Photo 28b/00 shows the rapid fading of the optical counterpart of GRB 000131 (slightly left of the centre), by means of exposures with the VLT on February 4 (upper left), 6 (upper right), 8 (lower left) and March 5 (lower right). It is no longer visible on the last photo

  4. The GLAST Gamma-Ray Observatory

    SciTech Connect

    Latronico, L.

    2004-10-27

    GLAST is a space mission that will observe the gamma-ray sky between 20MeV and 1TeV with unprecedented resolution and sensitivity. The Large Area Telescope (LAT), the main instrument onboard the GLAST satellite, is built with state-of-the-art particle physics detectors, and combines a large area is-strip tracker-converter, that will measure direction of incoming photons to an imaging CsI e.m. calorimeter for measurements of photon energies; an outer, segmented Anti-Coincidence Detector will reject charged particle background. In this paper they give an overview of the many physics goals and potential reach of the GLAST observatory and describe in detail the instrument design and performance.

  5. 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.

  6. GLAST: Exploring Nature's Highest Energy Processes with the Gamma-ray Large Area Space Telescope

    NASA Technical Reports Server (NTRS)

    Digel, Seth; Myers, J. D.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    The Gamma-ray Large Area Space Telescope (GLAST) is an international and multi-agency space mission that will study the cosmos in the energy range 10 keV-300 GeV. Several successful exploratory missions in gamma-ray astronomy led to the Energetic Gamma Ray Experiment Telescope (EGRET) instrument on the Compton Gamma Ray Observatory (CGRO). Launched in 1991, EGRET made the first complete survey of the sky in the 30 MeV-10 GeV range. EGRET showed the high-energy gamma-ray sky to be surprisingly dynamic and diverse, with sources ranging from the sun and moon to massive black holes at large redshifts. Most of the gamma-ray sources detected by EGRET remain unidentified. In light of the discoveries with EGRET, the great potential of the next generation gamma-ray telescope can be appreciated. GLAST will have an imaging gamma-ray telescope vastly more capable than instruments flown previously, as well as a secondary instrument to augment the study of gamma-ray bursts. The main instrument, the Large Area Telescope (LAT), will have superior area, angular resolution, field of view, and deadtime that together will provide a factor of 30 or more advance in sensitivity, as well as provide capability for study of transient phenomena. The GLAST Burst Monitor (GBM) will have a field of view several times larger than the LAT and will provide spectral coverage of gamma-ray bursts that extends from the lower limit of the LAT down to 10 keV. The basic parameters of the GBM are compared to those of the Burst and Transient Source Experiment (BATSE) instrument on CGRO in Table 1-2. With the LAT and GBM, GLAST will be a flexible observatory for investigating the great range of astrophysical phenomena best studied in high-energy gamma rays. NASA plans to launch GLAST in late 2005.

  7. Gamma Rays from Classical Novae

    NASA Technical Reports Server (NTRS)

    1997-01-01

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

  8. Gamma-Ray Interactions for Reachback Analysts

    SciTech Connect

    Karpius, Peter Joseph; Myers, Steven Charles

    2016-08-02

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

  9. Gamma ray astronomy from satellites and balloons

    NASA Technical Reports Server (NTRS)

    Schoenfelder, V.

    1986-01-01

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

  10. Scanning Gamma Ray Densitometer System for Detonations.

    DTIC Science & Technology

    in loaded detonators and delays. The 317 KEV gamma rays from an Ir192 source were collimated into a beam of 0.002 by 0.100 inch. A scanning system...minus 3%. With Ir192 , density measurements on NOL-130 were reproduced to plus or minus 5%, and on RDX to plus or minus 16%. Based on gamma ray

  11. The History of Gamma-Ray Astronomy

    NASA Astrophysics Data System (ADS)

    Schönfelder, V.

    An overview of the history of gamma-ray astronomy is given starting with predictions in the 1950's and first detections in the 1960's. Tremendous efforts have been made since then, with exciting discoveries, which finally culminated in the ``Golden Age'' of gamma-ray astronomy which we are presently experiencing.

  12. The history of gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Schönfelder, V.

    2002-07-01

    An overview of the history of gamma-ray astronomy is given starting with predictions in the 1950s and first detections in the 1960s. Tremendous efforts have been made since then, with exciting discoveries, which finally culminated in the ``Golden Age'' of gamma-ray astronomy which we are presently experiencing.

  13. Gamma-ray spectral analysis algorithm library

    SciTech Connect

    Egger, A. E.

    2013-05-06

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

  14. ASTRONOMY: Neighborhood Gamma Ray Burst Boosts Theory.

    PubMed

    Schilling, G

    2000-07-07

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

  15. Galactic Diffuse Gamma Ray Emission Is Greater than 10 Gev

    NASA Technical Reports Server (NTRS)

    Hunter, Stanley D.; White, Nicholas E. (Technical Monitor)

    2000-01-01

    AGILE and Gamma-ray Large Area Telescope (GLAST) are the next high-energy gamma-ray telescopes to be flown in space. These instruments will have angular resolution about 5 times better than Energetic Gamma-Ray Experiment Telescope (EGRET) above 10 GeV and much larger field of view. The on-axis effective area of AGILE will be about half that of EGRET, whereas GLAST will have about 6 times greater effective area than EGRET. The capabilities of ground based very high-energy telescopes are also improving, e.g. Whipple, and new telescopes, e.g. Solar Tower Atmospheric Cerenkov Effect Experiment (STACEE), Cerenkov Low Energy Sampling and Timing Experiment (CELESTE), and Mars Advanced Greenhouse Integrated Complex (MAGIC) are expected to have low-energy thresholds and sensitivities that will overlap the GLAST sensitivity above approximately 10 GeV. In anticipation of the results from these new telescopes, our current understanding of the galactic diffuse gamma-ray emission, including the matter and cosmic ray distributions is reviewed. The outstanding questions are discussed and the potential of future observations with these new instruments to resolve these questions is examined.

  16. Flare gamma ray continuum emission from neutral pion decay

    NASA Technical Reports Server (NTRS)

    Alexander, David; Mackinnon, Alec L.

    1992-01-01

    We investigate, in detail, the production of solar flare gamma ray emission above 100 MeV via the interaction of high energy protons with the ambient solar atmosphere. We restrict our considerations to the broadband gamma ray spectrum resulting from the decay of neutral pions produced in p-H reactions. Thick-target calculations are performed to determine the photon fluences. However, proton transport is not considered. Inferences about the form of the proton spectrum at 10-100 MeV have already been drawn from de-excitation gamma ray lines. Our aim is to constrain the proton spectrum at higher energies. Thus, the injected proton spectrum is assumed to have the form of a Bessel Function, characteristics of stochastic energy at higher energies. The detailed shape of the gamma ray spectra around 100 MeV is found to have a strong dependence on the spectral index of the power law and on the turnover energy (from Bessel function to power law). As would be expected, the harder the photon spectrum the wider the 100 MeV feature. The photon spectra are to be compared with observations and used to place limits upon the number of particles accelerated and to constrain acceleration models.

  17. The Gamma-ray galactic diffuse radiation and Cerenkov telescopes

    SciTech Connect

    Chardonnet, P. |; Salati, P. ||; Silk, J.; Grenier, I.; Smoot, G.

    1995-12-01

    By using the PYTHIA version of the Lund Monte Carlo program, we study the photon yield of proton-proton collisions in the energy range between 10 GeV and 1 TeV. The resulting photon spectrum turns out to scale roughly with incident energy. Then, by folding the energy spectrum of cosmic-ray protons with the distribution of HI and CO, the Galactic diffuse emission of {gamma}-rays above 100 GeV is mapped. Prospects for observing that diffuse radiation with atmospheric Cerenkov telescopes are discussed. Present instruments are able to detect the {gamma}-ray glow of the Galactic center. The latter will be mapped by the next generation of telescopes if their energy threshold is decreased. However, a detailed survey of the Galactic ridge will be a real challenge, even in the long term. The MILAGRO project seems more appropriate. Finally, we investigate the {gamma}-ray emission from weakly interacting massive particles clustering at the Galactic center. It has been speculated that those species are a major component of the halo dark matter. We show that their {gamma}-ray signal is swamped in the Galactic diffuse radiation and cannot be observed at TeV energies. {copyright} {ital 1995 The American Astronomical Society.}

  18. 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

  19. Instrumentation of LOTIS: Livermore Optical Transient Imaging System; a fully automated wide field of view telescope system searching for simultaneous optical counterparts of gamma ray bursts

    SciTech Connect

    Park, H.S.; Ables, E.; Barthelmy, S.D.; Bionta, R.M.; Ott, L.L.; Parker, E.L.; Williams, G.G.

    1998-03-06

    LOTIS is a rapidly slewing wide-field-of-view telescope which was designed and constructed to search for simultaneous gamma-ray burst (GRB) optical counterparts. This experiment requires a rapidly slewing ({lt} 10 sec), wide-field-of-view ({gt} 15{degrees}), automatic and dedicated telescope. LOTIS utilizes commercial tele-photo lenses and custom 2048 x 2048 CCD cameras to view a 17.6 x 17.6{degrees} field of view. It can point to any part of the sky within 5 sec and is fully automated. It is connected via Internet socket to the GRB coordinate distribution network which analyzes telemetry from the satellite and delivers GRB coordinate information in real-time. LOTIS started routine operation in Oct. 1996. In the idle time between GRB triggers, LOTIS systematically surveys the entire available sky every night for new optical transients. This paper will describe the system design and performance.

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

    PubMed

    Chadwick, Paula M

    2007-05-15

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