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Sample records for intensity gamma source

  1. A Device for Search of Gamma-Radiation Intensive Sources at the Radiation Accident Condition

    SciTech Connect

    Batiy, Valeriy; Klyuchnykov, A; Kochnev, N; Rudko, Vladimir; shcherbin, vladimir; Yegorov, V; Schmieman, Eric A.

    2005-08-08

    The procedure designed for measuring angular distributions of gamma radiation and for search of gamma radiation intensive sources is described. It is based on application of the original multidetector device ShD-1, for measuring an angular distribution in a complete solid angle (4 pi). The calibration results and data on the angular distributions of intensity of gamma radiation at the roof of Chornobyl NPP ''Shelter'' are presented.

  2. Intense inverse compton {gamma}-ray source from Duke storage ring FEL

    SciTech Connect

    Litvinenko, V.N.; Madey, J.M.J.

    1995-12-31

    We suggest using FEL intracavity power in the Duke storage ring fortrays production via Inverse Compton Backscattering (ICB). The OK-4 FEL driven by the Duke storage ring will tens of watts of average lasing power in the UV/VUV range. Average intracavity power will be in kilowatt range and can be used to pump ICB source. The {gamma}-rays with maximum energy from 40 MeV to 200 MeV with intensity of 0.1-5 10{sup 10}{gamma} per second can be generated. In this paper we present expected parameters of {gamma}-ray beam parameters including its intensity and distribution. We discuss influence of e-beam parameters on collimated {gamma}-rays spectrum and optimization of photon-electron interaction point.

  3. Application of FEL technique for constructing high-intensity, monochromatic, polarized gamma-sources at storage rings

    SciTech Connect

    Saldin, E.L.; Schneidmiller, E.A.; Ulyanov, Yu.N.

    1995-12-31

    A possibility to construct high-intensity tunable monochromatic{gamma}-source at high energy storage rings is discussed. It is proposed to produce {gamma}-quanta by means of Compton backscattering of laser photons on electrons circulating in the storage. The laser light wavelength is chosen in such a way that after the scattering, the electron does not leave the separatrix. So as the probability of the scattering is rather small, energy oscillations are damped prior the next scattering. As a result, the proposed source can operate in {open_quotes}parasitic{close_quote} mode not interfering with the main mode of the storage ring operation. Analysis of parameters of existent storage rings (PETRA, ESRF, Spring-8, etc) shows that the laser light wavelength should be in infrared, {lambda}{approximately} 10 - 400 {mu}m, wavelength band. Installation at storage rings of tunable free-electron lasers with the peak and average output power {approximately} 10 MW and {approximately} 1 kW, respectively, will result in the intensity of the {gamma}-source up to {approximately} 10{sup 14}s{sup -1} with tunable {gamma}-quanta energy from several MeV up to several hundreds MeV. Such a {gamma}-source will reveal unique possibilities for precision investigations in nuclear physics.

  4. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1994-08-16

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  5. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H.

    1994-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  6. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H.

    1995-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  7. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1995-10-17

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  8. Intense fusion neutron sources

    NASA Astrophysics Data System (ADS)

    Kuteev, B. V.; Goncharov, P. R.; Sergeev, V. Yu.; Khripunov, V. I.

    2010-04-01

    The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 1015-1021 neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 1020 neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the neutron itself.

  9. An overview of the research program at the High Intensity Gamma-Ray Source (HIGS) to study light nuclei

    NASA Astrophysics Data System (ADS)

    Ahmed, Mohammad

    2010-02-01

    A program is underway at the HIGS facility to study the response of nucleons and light nuclei, namely the deuteron and 3He, to gamma rays having energies between photodisintegration threshold and 100 MeV. Major components of this program are: 1) the spin response of polarized deuterium and polarized 3He to circularly polarized gamma rays to study the Gerasimov-Drell-Hearn (GDH) sum rule; 2) Compton scattering from protons and deuterons to extract the static electromagnetic polarizabilities of the nucleons; 3) A first measurement of the proton spin-polarizabilities; and 4) measurement of total and differential cross sections of the deuteron and 3He at energies relevant to Big-Bang Nucleosynthesis (BBN). An overview of these programs and initial results will be presented. )

  10. Compton scattering gamma-ray source optimization

    NASA Astrophysics Data System (ADS)

    Hartemann, Frederic; Wu, Sheldon; Albert, Félicie; Barty, Chris

    2012-10-01

    The interaction of a bright relativistic electron beam with an intense laser pulse via Compton scattering can generate tunable gamma-rays for precision nuclear photonics applications. The properties of the gamma-ray phase space will be outlined, in relation with the 6D electron bunch and 6D laser pulse phase space, along with collimation, nonlinear effects and other sources of spectral broadening. Optimization strategies will be outlines within the context of nuclear photonics applications.

  11. Gamma source for active interrogation

    DOEpatents

    Leung, Ka-Ngo; Lou, Tak Pui; Barletta, William A.

    2009-09-29

    A cylindrical gamma generator includes a coaxial RF-driven plasma ion source and target. A hydrogen plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical gamma generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which has many openings. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired.

  12. Gamma source for active interrogation

    SciTech Connect

    Leung, Ka-Ngo; Lou, Tak Pui; Barletta, William A.

    2012-10-02

    A cylindrical gamma generator includes a coaxial RF-driven plasma ion source and target. A hydrogen plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical gamma generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which has many openings. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired.

  13. Inverse compton scattering gamma ray source

    NASA Astrophysics Data System (ADS)

    Boucher, S.; Frigola, P.; Murokh, A.; Ruelas, M.; Jovanovic, I.; Rosenzweig, J. B.; Travish, G.

    2009-09-01

    Special Nuclear Materials (SNM) (e.g. U-235, Pu-239) can be detected by active interrogation with gamma rays (>6 MeV) through photofission. For long-range detection (˜1 km), an intense beam of gamma rays (˜10 14 per second) is required in order to produce measurable number of neutrons. The production of such fluxes of gamma rays, and in the pulse formats useful for detection, presents many technical challenges, and requires novel approaches to the accelerator and laser technology. RadiaBeam is currently designing a gamma ray source based on Inverse Compton Scattering (ICS) from a high-energy electron beam. To achieve this, improvements in photoinjector, linac, final focus, and laser system are planned. These enhanced sub-systems build on parallel work being performed at RadiaBeam, UCLA, and elsewhere. A high-repetition rate photoinjector, a high-gradient S-band linac, and a laser pulse recirculator will be used. The proposed system will be a transportable source of high-flux, high-energy quasi-monochromatic gamma rays for active interrogation of special nuclear materials.

  14. 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.

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

    SciTech Connect

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

    2012-04-02

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

  16. Gamma ray astronomy. [source mechanisms review

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D.

    1974-01-01

    The various source mechanisms for celestial gamma rays are reviewed. The gamma-ray data are examined as a source of information about the processes and source locations for the production of charged particle cosmic rays, galactic structure, explosive nucleosynthesis in supernovae, regions of confinement for cosmic rays, regions where matter-antimatter annihilation occurs, and the general condition in cosmological space both in the past and present. Topics include gamma rays from pi mesons by nuclear interactions, nuclear and supernovae lines, diffuse emission and discrete sources, interstellar absorption and detection of gamma rays, and others. A brief view of the available gamma-ray detection systems and techniques is presented.

  17. Laser Electron Gamma Source. Biennial progress report

    SciTech Connect

    Sandorfi, A.M.; Caracappa, A.; Kuczewski, A.; Kistner, O.C.; Lincoln, F.; Miceli, L.; Thorn, C.E.; Hoblit, S.; Khandaker, M. |

    1994-06-01

    The LEGS facility provides intense, polarized, monochromatic {gamma}-ray beams by Compton backscattering laser light from relativistic electrons circulating in the X-Ray storage ring of the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. With the start of ring operations at 2.8 GeV, LEGS {gamma}-ray energies now extend to 370 MeV. Considerable progress has been made in the development of a new laser system that will increase the beam energies to 470 MeV, and this system is expected to come into operation before the next biennial report. The total flux is administratively held at 6 {times} 10{sup 6} s{sup {minus}1}. The {gamma}-ray energy is determined, with a resolution of 5.5 MeV, by detecting the scattering electrons in a magnetic spectrometer. This spectrometer can `tag` all {gamma}-rays with energies from 185 MeV up to the Compton edge. The beam spot size at the target position is 8 mm (V) {times} 18 mm (H), FWHM. For a single laser wavelength, the linear polarization of the beam is 98% at the Compton edge and decreases to 50% at about 1/2 the energy of the edge. By choosing the laser wavelengths appropriately the polarization can be maintained above 85% throughout the tagging range. During the last two years, experimental running at LEGS occupied an average of 3000 hours annually. Highlights of some of the programs are discussed below.

  18. Intense source of slow positrons

    NASA Astrophysics Data System (ADS)

    Perez, P.; Rosowsky, A.

    2004-10-01

    We describe a novel design for an intense source of slow positrons based on pair production with a beam of electrons from a 10 MeV accelerator hitting a thin target at a low incidence angle. The positrons are collected with a set of coils adapted to the large production angle. The collection system is designed to inject the positrons into a Greaves-Surko trap (Phys. Rev. A 46 (1992) 5696). Such a source could be the basis for a series of experiments in fundamental and applied research and would also be a prototype source for industrial applications, which concern the field of defect characterization in the nanometer scale.

  19. Texas Intense Positron Source (TIPS)

    NASA Astrophysics Data System (ADS)

    O'Kelly, D.

    2003-03-01

    The Texas Intense Positron Source (TIPS) is a state of the art variable energy positron beam under construction at the Nuclear Engineering Teaching Laboratory (NETL). Projected intensities on the order of the order of 10^7 e+/second using ^64Cu as the positron source are expected. Owing to is short half-life (t1/2 12.8 hrs), plans are to produce the ^64Cu isotope on-site using beam port 1 of NETL TRIGA Mark II reactor. Following tungsten moderation, the positrons will be electrostatically focused and accelerated from few 10's of eV up to 30 keV. This intensity and energy range should allow routine performance of several analytical techniques of interest to surface scientists (PALS, PADB and perhaps PAES and LEPD.) The TIPS project is being developed in parallel phases. Phase I of the project entails construction of the vacuum system, source chamber, main beam line, electrostatic/magnetic focusing and transport system as well as moderator design. Initial construction, testing and characterization of moderator and beam transport elements are underway and will use a commercially available 10 mCi ^22Na radioisotope as a source of positrons. Phase II of the project is concerned primarily with the Cu source geometry and thermal properties as well as production and physical handling of the radioisotope. Additional instrument optimizing based upon experience gained during Phase I will be incorporated in the final design. Current progress of both phases will be presented along with motivations and future directions.

  20. Pulsed pyroelectric crystal-powered gamma source

    SciTech Connect

    Chen, A. X.; Antolak, A. J.; Leung, K.-N.; Raber, T. N.; Morse, D. H.

    2013-04-19

    A compact pulsed gamma generator is being developed to replace radiological sources used in commercial, industrial and medical applications. Mono-energetic gammas are produced in the 0.4 - 1.0 MeV energy range using nuclear reactions such as {sup 9}Be(d,n{gamma}){sup 10}B. The gamma generator employs an RF-driven inductively coupled plasma ion source to produce deuterium ion current densities up to 2 mA/mm{sup 2} and ampere-level current pulses can be attained by utilizing an array extraction grid. The extracted deuterium ions are accelerated to approximately 300 keV via a compact stacked pyroelectric crystal system and then bombard the beryllium target to generate gammas. The resulting microsecond pulse of gammas is equivalent to a radiological source with curie-level activity.

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

    SciTech Connect

    DeVries, Daniel J.; Griffin, Henry C.

    2006-03-13

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

  2. Laser-Electron-Gamma-Source. Progress report, July 1986

    SciTech Connect

    Dowell, D.H.; Fineman, B.; Giordano, G.; Kistner, OC.; Matone, G.; Sandorfi, A.M.; Schaerf, C.; Thorn, C.E.; Ziegler, W.

    1986-07-01

    When completed, the Laser Electron Gamma Source (LEGS) is expected to provide intense beams of monochromatic and polarized (circular or linear) gamma rays with energies up to 500 MeV. The gamma-ray beams will be produced by Compton backscattering uv laser light from the electrons circulating in a storage ring. Progress with installation of the facility is described, particularly the Ar-ion laser and tagging spectrometer. Tests of the tagging spectrometer coponents is reported, and a second laser is described for higher energy operation. Estimates are given of expected beam parameters. Experimental equipment for the planned research projects to be carried out at the LEGS facility is discussed. (LEW)

  3. 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.

  4. Three precise gamma-ray burst source locations

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Teegarden, B. J.; Barat, C.; Hurley, K.; Niel, M.; Vedrenne, G.; Evans, W. D.; Klebesadel, R. W.; Laros, J. G.

    1984-01-01

    The precise source regions of three moderately intense gamma ray bursts are derived. These events were observed with the first interplanetary burst sensor network. The optimum locations of the detectors, widely separated throughout the inner solar system, allowed for high accuracy, over-determined source fields of size 0.7 to 7.0 arc-min(2). All three locations are at fairly high galactic latitude in regions of low source confusion; none can be identified with a steady source object. Archived photographs were searched for optical transients that are able to be associated with these source fields; one such association was made.

  5. Commissioning of a Compton-Scattering-Based Gamma Ray Source

    NASA Astrophysics Data System (ADS)

    Gibson, David; Albert, Felicie; Anderson, Scott; Hartemann, Fred; Messerly, Mike; Shverdin, Miro; McNabb, Dennis; Siders, Craig; Barty, Chris

    2009-11-01

    Recently a Compton-scattering based gamma-ray source, in which a high-intensity laser scatters off a high-brightness electron beam and emerges as a narrow-band gamma-ray beam, has been commissioned at Lawrence Livermore National Laboratory. Operating at energies from 0.1 to 0.9 MeV, the source produces fluxes upwards of 10^6 photons/sec with a brightness of 10^ 15 photons/s/mm^2/mrad^2/0.1% BW. Presented here is a discussion of the design and performance of the laser and electron subsystems that are used to drive the source, and an overview of the parameters of the generated gamma-ray beam.

  6. Space-Borne Observations of Intense Gamma-Ray Flashes (TGFs) Above Thunderstorms

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2011-01-01

    Intense millisecond flashes of MeV photons have been observed with space-borne detectors. These terrestrial gamma-ray flashes (TGFs) were discovered with the Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma- Ray Observatory (CGRO) in the early 1990s. They are now being observed with several other instruments, including the Gamma-ray Burst Monitor (GBM) detectors on the Fermi Gamma-ray Space Telescope. Although Fermi-GBM was designed and optimized for the observation of cosmic gamma-ray bursts (GRBs), it has unprecedented capabilities for these TGF observations. On several occasions, intense beams of high-energy electrons and positrons have been observed at the geomagnetic conjugate points of TGFs.

  7. Gamma-ray line intensities for depleted uranium

    SciTech Connect

    Moss, C.E.

    1985-01-01

    Measurements of the gamma-ray line intensities from depleted uranium allowed us to determine which of two conflicting previous experiments was correct. For the 1001-keV line we obtain a branching ratio of 0.834 +- 0.007, in good agreement with one of the previous experiments. A table compares our intensities for several lines with those obtained in previous experiments. 5 refs., 2 figs., 1 tab.

  8. Some neutron and gamma radiation characteristics of plutonium cermet fuel for isotopic power sources

    NASA Technical Reports Server (NTRS)

    Neff, R. A.; Anderson, M. E.; Campbell, A. R.; Haas, F. X.

    1972-01-01

    Gamma and neutron measurements on various types of plutonium sources are presented in order to show the effects of O-17, O-18 F-19, Pu-236, age of the fuel, and size of the source on the gamma and neutron spectra. Analysis of the radiation measurements shows that fluorine is the main contributor to the neutron yields from present plutonium-molybdenum cermet fuel, while both fluorine and Pu-236 daughters contribute significantly to the gamma ray intensities.

  9. Do gamma-ray burst sources repeat?

    NASA Technical Reports Server (NTRS)

    Meegan, C. A.; Hartmann, D. H.; Brainerd, J. J.; Briggs, M.; Paciesas, W. S.; Pendleton, G.; Kouveliotou, C.; Fishman, G.; Blumenthal, G.; Brock, M.

    1994-01-01

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

  10. Compton scattering with low intensity radioactive sources

    NASA Astrophysics Data System (ADS)

    Quarles, Carroll

    2012-03-01

    Compton scattering experiments with gamma rays typically require a ``hot'' source (˜5mCi of Cs137) to observe the scattering as a function of angle. (See Ortec AN34 Experiment #10 Compton Scattering) Here a way is described to investigate Compton scattering with micro Curie level radioactive sources that are more commonly available in the undergraduate laboratory. A vertical-looking 2 inch coaxial hpGe detector, collimated with a 2 inch thick lead shield, was used. Cylindrical Al targets of various thicknesses were placed over the collimator and several available sources were placed around the target so that the average Compton scattering angle into the collimator was 90 deg. A peak could be observed at the expected energy for 90 deg. Compton scattering by doing 24 hour target-in minus target-out runs. The peak was broadened by the spread in the scattering angle due to the variation in the angle of the incoming gamma ray and the angular acceptance of the collimator. A rough analysis can be done by modeling the angular spread due to the geometry and correcting for the gamma ray absorption from the target center. Various target materials and sources can be used and some variation in average Compton scattering angle can be obtained by adjusting the geometry of the source and target.

  11. ON COMPUTING UPPER LIMITS TO SOURCE INTENSITIES

    SciTech Connect

    Kashyap, Vinay L.; Siemiginowska, Aneta; Van Dyk, David A.; Xu Jin; Connors, Alanna; Freeman, Peter E.; Zezas, Andreas E-mail: asiemiginowska@cfa.harvard.ed E-mail: jinx@ics.uci.ed E-mail: pfreeman@cmu.ed

    2010-08-10

    A common problem in astrophysics is determining how bright a source could be and still not be detected in an observation. Despite the simplicity with which the problem can be stated, the solution involves complicated statistical issues that require careful analysis. In contrast to the more familiar confidence bound, this concept has never been formally analyzed, leading to a great variety of often ad hoc solutions. Here we formulate and describe the problem in a self-consistent manner. Detection significance is usually defined by the acceptable proportion of false positives (background fluctuations that are claimed as detections, or Type I error), and we invoke the complementary concept of false negatives (real sources that go undetected, or Type II error), based on the statistical power of a test, to compute an upper limit to the detectable source intensity. To determine the minimum intensity that a source must have for it to be detected, we first define a detection threshold and then compute the probabilities of detecting sources of various intensities at the given threshold. The intensity that corresponds to the specified Type II error probability defines that minimum intensity and is identified as the upper limit. Thus, an upper limit is a characteristic of the detection procedure rather than the strength of any particular source. It should not be confused with confidence intervals or other estimates of source intensity. This is particularly important given the large number of catalogs that are being generated from increasingly sensitive surveys. We discuss, with examples, the differences between these upper limits and confidence bounds. Both measures are useful quantities that should be reported in order to extract the most science from catalogs, though they answer different statistical questions: an upper bound describes an inference range on the source intensity, while an upper limit calibrates the detection process. We provide a recipe for computing upper

  12. OVERVIEW OF MONO-ENERGETIC GAMMA-RAY SOURCES & APPLICATIONS

    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 P; Vlieks, A E; Jongewaard, E N; Tantawi, S G; Raubenheimer, T O

    2010-05-18

    Recent progress in accelerator physics and laser technology have enabled the development of a new class of tunable 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 Mono-Energetic Gamma-ray (MEGa-ray) source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linac designed in collaboration with SLAC NAL will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. This MEGa-ray source will be used to excite nuclear resonance fluorescence 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, along with important applications, including nuclear resonance fluorescence. In conclusion, we have optimized the design of a high brightness Compton scattering gamma-ray source, specifically designed for NRF applications. Two different parameters sets have been considered: one where the number of photons scattered in a single shot reaches approximately 7.5 x 10{sup 8}, with a focal spot size around 8 {micro}m; in the second set, the spectral brightness is optimized by using a 20 {micro}m spot size, with 0.2% relative bandwidth.

  13. Integral-moment analysis of the BATSE gamma-ray burst intensity distribution

    NASA Technical Reports Server (NTRS)

    Horack, John M.; Emslie, A. Gordon

    1994-01-01

    We have applied the technique of integral-moment analysis to the intensity distribution of the first 260 gamma-ray bursts observed by the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory. This technique provides direct measurement of properties such as the mean, variance, and skewness of the convolved luminosity-number density distribution, as well as associated uncertainties. Using this method, one obtains insight into the nature of the source distributions unavailable through computation of traditional single parameters such as V/V(sub max)). If the luminosity function of the gamma-ray bursts is strongly peaked, giving bursts only a narrow range of luminosities, these results are then direct probes of the radial distribution of sources, regardless of whether the bursts are a local phenomenon, are distributed in a galactic halo, or are at cosmological distances. Accordingly, an integral-moment analysis of the intensity distribution of the gamma-ray bursts provides for the most complete analytic description of the source distribution available from the data, and offers the most comprehensive test of the compatibility of a given hypothesized distribution with observation.

  14. ASTRONOMY: A New Source of Gamma Rays.

    PubMed

    Fender, R P

    2000-06-30

    Relativistic outflows or "jets" are collimated streams of high-energy electrons that emit synchrotron radiation at radio wavelengths and have bulk velocities that are a substantial fraction of the speed of light. They trace the outflow of enormous amounts of energy and matter from a central supermassive black hole in distant radio galaxies. As Fender explains in this Perspective, much smaller, more local sources may also produce such jets. Data presented by Paredes et al. point toward association of one such source, a relatively faint x-ray binary, with a gamma-ray source. This and similar pairs may contribute substantially to the production of high-energy particles and photons within our galaxy.

  15. Do gamma-ray burst sources repeat?

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  16. High intensity, pulsed thermal neutron source

    DOEpatents

    Carpenter, J.M.

    1973-12-11

    This invention relates to a high intensity, pulsed thermal neutron source comprising a neutron-producing source which emits pulses of fast neutrons, a moderator block adjacent to the last neutron source, a reflector block which encases the fast neutron source and the moderator block and has a thermal neutron exit port extending therethrough from the moderator block, and a neutron energy- dependent decoupling reflector liner covering the interior surfaces of the thermal neutron exit port and surrounding all surfaces of the moderator block except the surface viewed by the thermal neutron exit port. (Official Gazette)

  17. An industrial radiography exposure device based on measurement of transmitted gamma-ray intensity

    NASA Astrophysics Data System (ADS)

    Polee, C.; Chankow, N.; Srisatit, S.; Thong-Aram, D.

    2015-05-01

    In film radiography, underexposure and overexposure may happen particularly when lacking information of specimen material and hollowness. This paper describes a method and a device for determining exposure in industrial gamma-ray radiography based on quick measurement of transmitted gamma-ray intensity with a small detector. Application software was developed for Android mobile phone to remotely control the device and to display counting data via Bluetooth communication. Prior to film exposure, the device is placed behind a specimen to measure transmitted intensity which is inversely proportional to the exposure. Unlike in using the conventional exposure curve, correction factors for source decay, source-to- film distance, specimen thickness and kind of material are not needed. The developed technique and device make radiographic process economic, convenient and more reliable.

  18. An Intense Terrestrial Gamma-ray Flash Observed at Ground Level

    NASA Astrophysics Data System (ADS)

    Grove, J. E.; Phlips, B. F.; Wulf, E. A.; Hutcheson, A. L.; Mitchell, L. J.; Woolf, R. S.; Johnson, W. N.; Schaal, M.; Uman, M. A.; Jordan, D.; Hare, B.; Rassoul, H.; Bozarth, A.

    2015-12-01

    We report on an intense gamma-ray flash observed at ground level in August 2014 at the International Center for Lightning Research and Testing, Camp Blanding, Florida, that occurred 13 ms after the initiation of the first stroke of an altitude-triggered lightning discharge. The measurements were made with an array of 78 plastic, liquid, and fast inorganic scintillators for robust spectroscopy of high-rate transients. The gamma-ray spectrum, time-intensity profile, and luminosity at the putative source altitude are consistent with those of a Terrestrial Gamma-ray Flash (TGF). The fluence of >100 keV gamma rays at ground level in the ~200 μs flash was in excess of 10 photons / cm2, an order of magnitude brighter than typical TGFs observed from low-Earth orbit. The proximity of the TGF to our large scintillator array allows these to be the most detailed gamma-ray measurements ever made of a TGF. Work at NRL was sponsored by the Chief of Naval Research.

  19. Intense Gamma-Ray Flashes Above Thunderstorms on the Earth and Other Planets

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2010-01-01

    Intense millisecond flashes of MeV photons have been observed with space-borne detectors in Earth orbit. They are expected to be present on other planets that exhibit lightning. The terrestrial gamma-ray flashes (TGFs) were discovered with the Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma-Ray Observatory (CGRO) in the early 1990s. They are now being observed with several other instruments, including the Gamma-ray Burst Monitor (GBM) detectors on the Fermi Gamma-ray Space Telescope. Although Fermi- GBM was designed and optimized for the observation of cosmic gamma-ray bursts (GRBs), it has unprecedented capabilities for TGF observations. The TGFs usually have extremely hard continuous spectra, typical of highly- Comptonized bremsstrahlung radiation. These spectral are harder than those of GRBs, with photons extending to over 40 MeV. The most likely origin of these high-energy photons is bremsstrahlung radiation produced by a relativistic "runaway avalanche" electron beam. Such a beam is expected to be produced in an extended, intense electric field in or above thunderstorm regions. The altitude of origin and beaming characteristics of the radiation are quite uncertain. They have generated considerable observational and theoretical interest in recent years. This talk will give an overview of the all of the space-borne observations of TGFs that have been made thus far. Instruments are being designed specifically for TGF observations from new spacecraft as well as from airborne platforms

  20. Space-Borne Observations of Intense Gamma-Ray Flashes (TGFs) Above Thunderstorms

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2010-01-01

    Intense millisecond flashes of MeV photons are being observed with space-borne detectors. These terrestrial gamma-ray flashes (TGFs) were discovered with the Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma-Ray Observatory (CGRO) in the early 1990s. They are now being observed with several other instruments, including the Gamma-ray Burst Monitor (GBM) detectors on the Fermi Gamma-ray Space Telescope. Although Fermi-GBM was designed and optimized for the observation of cosmic gamma-ray bursts (GRBs), it has unprecedented capabilities for TGF observations. The TGFs usually have extremely hard continuous spectra, typical of highly-Comptonized bremsstrahlung radiation. These spectral are harder than those of GRBs, with photons extending to over 40 MeV. The most likely origin of these high-energy photons is bremsstrahlung radiation produced by a relativistic runaway avalanche electron beam. Such a beam is expected to be produced in an extended, intense electric field in or above thunderstorm regions. The altitude of origin and beaming characteristics of the radiation are quite uncertain. These TGFs may produce an appreciable radiation dose to passengers and crew in nearby aircraft. They have generated considerable observational and theoretical interest in recent years. Instruments are being designed specifically for TGF observations from new spacecraft as well as from airborne platforms.

  1. Intense Photoneutron Sources For Nuclear Material Detection

    NASA Astrophysics Data System (ADS)

    Gozani, Tsahi; Shaw, Timothy; King, Michael

    2011-06-01

    Intense neutron sources are essential for cargo inspection for a broad range of threats from explosives, to contraband, to nuclear materials and especially SNM (Special Nuclear Materials). To be effective over a wide range of cargo materials, in particular for hydrogenous cargo such as food, and to offer practical inspection times, the neutron source must be very strong, typically >1010 neutrons per second. Unfortunately there are currently no reasonably compact and economical neutron generators with the required intensities. The insufficiency and inadequacy of intense neutron sources are especially conspicuous in the ≤2.5 MeV range (low voltage (d,D) generator). This energy range is needed if the strong signature of prompt fission neutrons (≈3 per fission) is to be detected and discerned from the numerous source neutrons. The photonuclear reactions of x-rays from commercial linacs in appropriate converters can provide ample intensities of neutrons. These converters have a very low (γ,n) energy threshold: 1.67 MeV for beryllium and 2.23 MeV for deuterium. The intense x-ray beams provided by commercial x-ray systems, more than compensate for the relatively low (γ,n) cross-sections which are in the milli-barn range. The choice of converter material, the geometrical shape, dimensions and location relative to the x-ray source, determine the efficiency of the neutron conversion. For electron accelerators with less than 10 MeV, the preferred converters, Be and D2O, are also very good neutron moderators. Thus, while increasing the converters' thickness leads to an increase in the overall neutron yield, this causes the softening of the neutron spectrum, which reduces the neutron penetration especially in hydrogenous cargos. Photoneutron sources can be optimized to meet specific needs such as maximum fission signals in various cargo materials of interest. Efficient photoneutron sources with different energy spectra were investigated. Conversion efficiency of more than

  2. Very High-Energy Gamma-Ray Sources.

    ERIC Educational Resources Information Center

    Weekes, Trevor C.

    1986-01-01

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

  3. Measuring The Variability Of Gamma-Ray Sources With AGILE

    SciTech Connect

    Chen, Andrew W.; Vercellone, Stefano; Pellizzoni, Alberto; Tavani, Marco

    2005-02-21

    Variability in the gamma-ray flux above 100 MeV at various time scales is one of the primary characteristics of the sources detected by EGRET, both allowing the identification of individual sources and constraining the unidentified source classes. We present a detailed simulation of the capacity of AGILE to characterize the variability of gamma-ray sources, discussing the implications for source population studies.

  4. Laser System for Livermore's Mono Energetic Gamma-Ray Source

    SciTech Connect

    Gibson, D; Albert, F; Bayramian, A; Marsh, R; Messerly, M; Ebbers, C; Hartemann, F

    2011-03-14

    A Mono-energetic Gamma-ray (MEGa-ray) source, based on Compton scattering of a high-intensity laser beam off a highly relativistic electron beam, requires highly specialized laser systems. To minimize the bandwidth of the {gamma}-ray beam, the scattering laser must have minimal bandwidth, but also match the electron beam depth of focus in length. This requires a {approx}1 J, 10 ps, fourier-transform-limited laser system. Also required is a high-brightness electron beam, best provided by a photoinjector. This electron source requires a second laser system with stringent requirements on the beam including flat transverse and longitudinal profiles and fast rise times. Furthermore, these systems must be synchronized to each other with ps-scale accuracy. Using a novel hyper-dispersion compressor configuration and advanced fiber amplifiers and diode-pumped Nd:YAG amplifiers, we have designed laser systems that meet these challenges for the X-band photoinjector and Compton-scattering source being built at Lawrence Livermore National Laboratory.

  5. Development of Texas intense positron source

    NASA Astrophysics Data System (ADS)

    Köymen, A. R.; Ünlü, K.; Jacobsen, F. M.; Göktepeli, S.; Wehring, B. W.

    1999-02-01

    The Texas Intense Positron Source (TIPS) is a reactor-based low-energy positron beam facility utilizing some novel techniques in positron beam production. This facility will be located at the University of Texas (UT) at Austin Nuclear Engineering Teaching Laboratory (NETL) and is being developed by UT Austin and UT Arlington researchers. TIPS will use a large area (total area of 900-1800 cm 2) 64Cu source to supply fast β + particles for subsequent moderation to form an intense monoenergetic positron beam in the energy range of 0-50 keV with an expected intensity of 10 8 e +/s. Natural copper will be neutron activated near the core of the NETL 1 MW TRIGA Mark II research reactor to produce the 64Cu isotope. The activated source will be transported to the moderator/remoderator assembly, outside the biological shield of the reactor. This assembly combines the primary moderation and posterior remoderation of the fast β + particles into one stage using solid Kr to produce a low-energy positron source of a few eV with a diameter of 8 mm. The low-energy positron beam is then extracted by an electrostatic modified SOA gun and after further acceleration to 5 keV, the beam is focused onto the object slit of a 90° bending magnet. After further focusing and another 90° bend, the beam enters the main accelerator/decelerator that transports the beam onto the target for experimentation. The components of TIPS have been manufactured and are currently being optimized. In this communication we present some of the details of the TIPS facility and furthermore briefly discuss its intended applications.

  6. Picosecond Pulse Recirculation for High Average Brightness Thomson Scattering-based Gamma-ray Sources

    SciTech Connect

    Semenov, V. A.

    2009-06-12

    Pulse recirculation has been successfully demonstrated with the interaction laser system of LLNL's Thomson-Radiated Extreme X-ray (T-REX) source. The recirculation increased twenty-eight times the intensity of the light coming out of the laser system, demonstrating the capability of increasing the gamma-ray flux emitted by T-REX. The technical approach demonstrated could conceivably increase the average gamma-ray flux output by up to a hundred times.

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

    SciTech Connect

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

    2009-05-15

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

  8. Multiwavelength observations of unidentified high energy gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.

    1995-01-01

    As was the case for COS B, the majority of high-energy (greater than 100 MeV) gamma-ray sources detected by the EGRET instrument on GRO are not immediately identifiable with catalogued objects at other wavelengths. These persistent gamma-ray sources are, next to the gamma-ray bursts, the least understood objects in the universe. This two year investigation is intended to support the analysis, correlation, and theoretical interpretation of data that we are obtaining at x-ray, optical, and radio wavelengths in order to render the gamma-ray data interpretable. This second year was devoted to studies of unidentified gamma-ray sources from the first EGRET catalog, similar to previous observations. Efforts have concentrated on the sources at low and intermediate Galactic latitudes, which are the most plausible pulsar candidates.

  9. Multi-gamma-source CT imaging system: a feasibility study with the Poisson noise

    NASA Astrophysics Data System (ADS)

    Wi, Sunhee; Cho, Seungryong

    2016-03-01

    This study was performed to test the feasibility of multi-gamma-source CT imaging system. Gamma-source CT employs radioisotopes that emit monochromatic energy gamma-rays. The advantages of gamma-source CT include its immunity to beam hardening artifacts, its capacity of quantitative CT imaging, and its higher performance in low contrast imaging compared to the conventional x-ray CT. Radioisotope should be shielded by use of a pin-hole collimator so as to make a fine focal spot. Due to its low gamma-ray flux in general, the reconstructed image from a single gamma-source CT would suffer from high noise in data. To address this problem, we proposed a multi-gamma source CT imaging system and developed an iterative image reconstruction algorithm accordingly in this work. Conventional imaging model assumes a single linear imaging system typically represented by Mf = g. In a multi-gamma-source CT system however, the inversion problem is not any more based on a single linear system since one cannot separate a detector pixel value into multiple ones that are corresponding to each rays from the sources. Instead, the imaging model can be constructed by a set of linear system models each of which assumes an estimated measurement g. Based on this model, the proposed algorithm has a weighting step which distributes each projection data into multiple estimated measurements. We used two gamma sources at various positions and with varying intensities in this numerical study to demonstrate its feasibility. Therefore, the measured projection data(g) is separated into each estimated projection data(g1, g2) in this study. The proposed imaging protocol is believed to contribute to both medical and industrial applications.

  10. Determination of X- and gamma-ray emission intensities in the decay of (131)I.

    PubMed

    Lépy, Marie-Christine; Brondeau, Laurine; Bobin, Christophe; Lourenço, Valérie; Thiam, Cheick; Bé, Marie-Martine

    2016-03-01

    The activity per unit mass of an iodine-131 solution was absolutely standardized by both the 4πβ-γ coincidence method and the 4πγ counting technique. The calibrated solution was used to prepare point sources after a preliminary deposit of AgNO3 to prevent the loss of volatile iodine. Relative and absolute photon emission intensities of 15 sgamma-rays and those of the two K X-rays of xenon were determined by gamma-ray spectrometry, with relative uncertainties of 0.8% for the three main emissions.

  11. Activity measurements and determination of gamma-ray emission intensities in the decay of 65Zn.

    PubMed

    Bé, Marie-Martine

    2006-01-01

    An International EUROMET exercise, Action 721, was organized with the objective of obtaining more reliable decay data on the disintegration of 65Zn. Nine laboratories participated, sending their results relating to activity measurements and 1115-keV gamma-ray emission intensity. Participants mainly used the 4pibeta-gamma coincidence method for the activity measurement, the resulting values and uncertainty budgets are described. New gamma-ray emission intensities were also measured in this exercise and, taking into account previously published values, the intensity of the 1115-keV gamma-ray emission has been determined to be 50.22(11)%.

  12. The Los Alamos Intense Neutron Source

    SciTech Connect

    Nebel, R.A.; Barnes, D.C.; Bollman, R.; Eden, G.; Morrison, L.; Pickrell, M.M.; Reass, W.

    1997-10-01

    The Intense Neutron Source (INS) is an Inertial Electrostatic Confinement (IEC) fusion device presently under construction at Los Alamos National Laboratory. It is designed to produce 10{sup 11} neutrons per second steady-state using D-T fuel. Phase 1 operation of this device will be as a standard three grid IEC ion focus device. Expected performance has been predicted by scaling from a previous IEC device. Phase 2 operation of this device will utilize a new operating scheme, the Periodically Oscillating Plasma Sphere (POPS). This scheme is related to both the Spherical Reflect Diode and the Oscillating Penning Trap. With this type of operation the authors hope to improve plasma neutron production to about 10{sup 13} neutrons/second.

  13. Portable, high intensity isotopic neutron source provides increased experimental accuracy

    NASA Technical Reports Server (NTRS)

    Mohr, W. C.; Stewart, D. C.; Wahlgren, M. A.

    1968-01-01

    Small portable, high intensity isotopic neutron source combines twelve curium-americium beryllium sources. This high intensity of neutrons, with a flux which slowly decreases at a known rate, provides for increased experimental accuracy.

  14. Status of the intense pulsed neutron source

    SciTech Connect

    Carpenter, J.M.; Brown, B.S.; Kustom, R.L.; Lander, G.H.; Potts, C.W.; Schulke, A.W.; Wuestefeld, G.

    1985-01-01

    Fortunately in spite of some premature reports of its impending demise, IPNS has passed the fourth anniversary of the first delivery of protons to the targets (May 5, 1981) and is approaching the fourth anniversary of its operation as a scattering facility (August 4, 1981). On June 10, 1984, the RCS delivered its one billionth pulse to the IPNS target - the total number of protons delivered to the targets amounted then to 75 stp cm/sup 3/ of H/sub 2/ gas. Since startup IPNS has improved steadily in terms of the performance of the Rapid Cycling Synchrotron, the source and its moderators and the scattering instruments, and a substantial and productive user program has evolved. This report summarizes the current status of the Intense Pulsed Neutron Source at Argonne National Laboratory. We include reference to recent accelerator operating experience, neutron facility operating experience, improvements to these systems, design work on the ASPUN high-current facility, booster target design, the new solid methane moderator, characterization of the room temperature moderators, and provide some examples of recent results from several of the spectrometers.

  15. Automatic pneumatic source-control system for positioning gamma and neutron calibration sources

    SciTech Connect

    Hunt, G.F.

    1980-10-17

    A microcomputer-based source-control system was developed to move gamma and neutron calibration sources into position for sample irradiation. In addition to monitoring interlocks and system status, the computer calculates for gamma sources the time required for a requested exposure at a specified distance. All system use data is stored, and monthly reports are generated.

  16. Energy sources in gamma-ray burst models

    NASA Technical Reports Server (NTRS)

    Taam, Ronald E.

    1987-01-01

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

  17. Multiwavelength observations of unidentified high energy gamma ray sources

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.

    1993-01-01

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

  18. Compact sources as the origin of the soft gamma-ray emission of the Milky Way.

    PubMed

    Lebrun, F; Terrier, R; Bazzano, A; Bélanger, G; Bird, A; Bouchet, L; Dean, A; Del Santo, M; Goldwurm, A; Lund, N; Morand, H; Parmar, A; Paul, J; Roques, J-P; Schönfelder, V; Strong, A W; Ubertini, P; Walter, R; Winkler, C

    2004-03-18

    The Milky Way is known to be an abundant source of gamma-ray photons, now determined to be mainly diffuse in nature and resulting from interstellar processes. In the soft gamma-ray domain, point sources are expected to dominate, but the lack of sensitive high-resolution observations did not allow for a clear estimate of the contribution from such sources. Even the best imaging experiment revealed only a few point sources, accounting for about 50% of the total Galactic flux. Theoretical studies were unable to explain the remaining intense diffuse emission. Investigating the origin of the soft gamma-rays is therefore necessary to determine the dominant particle acceleration processes and to gain insights into the physical and chemical equilibrium of the interstellar medium. Here we report observations in the soft gamma-ray domain that reveal numerous compact sources. We show that these sources account for the entirety of the Milky Way's emission in soft gamma-rays, leaving at most a minor role for diffuse processes.

  19. Sources of interferon-gamma (IFN-gamma) in early immune response to Listeria monocytogenes.

    PubMed

    Thäle, Carsten; Kiderlen, Albrecht F

    2005-01-01

    Early, innate production of interferon-gamma (IFN-gamma) is a critical step in immunological defense against certain pathogens such as intracellular bacteria (e.g. Listeria monocytogenes), viruses and fungi. While activated T cells and activated natural killer (NK) cells were initially thought to be the only relevant source of IFN-gamma, macrophages (Mphi) and dendritic cells can also be stimulated to produce IFN-gamma in vitro under certain conditions. However, a convincing analysis at single cell level of the source(s) of IFN-gamma in the early immune response to an acute bacterial infection is still missing. In the light of controversial literature, the work presented here aimed to clarify the role of NK cells and other components of the innate cellular immune system in the early IFN-gamma production, thereby avoiding in vitro artifacts whenever possible. Immunocompetent C57BL/6 (wild type (WT)) and T and B cell-deficient C57BL/6 rag-1(-/-) (RAG) mice were infected intravenously with a pathogenic strain of L. monocytogenes. Leukocyte populations of spleen and liver were discriminated by characteristic surface markers and analyzed for intracellular interleukin (IL)-12 and IFN-gamma using flow cytometry. These cells have not been restimulated in vitro nor sorted before analysis. In RAG mice, at least, a large NK1.1+ cell population produced IFN-gamma 19 h p.i. No MHC class II+ population co-expressed intracellular IFN-gamma at this time point. For comparison with the immunocompetent situation, syngeneic WT mice were also infected and sacrificed 9, 19, and 29 h later. At 9 h p.i., the situation resembled that of uninfected mice. At 19 and 29 h p.i. it was again the NK1.1+ population that contained most of the IFN-gamma-positive events. MHC II + CD 19- Mphi/dendritic cells and MHC II+ CD19+ B cells did not co-express intracellular IFN-gamma at these time points. CD3+ T cells were also found to contain intracellular IFN-gamma; most were also CD8+ and some CD4+. These

  20. Final SAS-2 gamma-ray results on sources in the galactic anticenter region

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Lamb, R. C.

    1977-01-01

    Final results are presented for SAS-2 observations of high-energy gamma-rays from the galactic anticenter region. Three main gamma-ray features are shown to characterize this region: a localized source associated with the Crab Nebula and its pulsar, another localized source near galactic coordinates 195 deg, +5 deg, and a general enhancement of the diffuse background 10 to 15 deg south of the galactic plane, which is associated with the Gould Belt. For the Crab, it is found that the radiation is mostly pulsed, the pulsed fraction increases with energy, and the intensity of the radiation in the main and interpulse peaks is approximately the same. The other localized source, provisionally designated as gamma 195+5, is found to have a harder spectrum than the Crab but no obvious radio counterpart; emission from an external galaxy is ruled out.

  1. Specification of High Activity Gamma-Ray Sources.

    ERIC Educational Resources Information Center

    International Commission on Radiation Units and Measurements, Washington, DC.

    The report is concerned with making recommendations for the specifications of gamma ray sources, which relate to the quantity of radioactive material and the radiation emitted. Primary consideration is given to sources in teletherapy and to a lesser extent those used in industrial radiography and in irradiation units used in industry and research.…

  2. Detection of a fast, intense and unusual gamma ray transient

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Pizzichini, G.; Teegarden, B. J.; Evans, W. D.; Klebesadel, R. W.; Laros, J. G.; Hurley, K.; Niel, M.; Vedrenne, G.

    1979-01-01

    An unusual transient pulse of approximately 50 keV was detected by the gamma-ray burst sensor network using nine space probes and satellites. Its characteristics are unlike those of the known variety of gamma-ray bursts and therefore suggest that it was formed either by a completely different origin species or in a very different manner. It is identified with the LMC supernova remnant N49.

  3. Constraints on galactic distributions of gamma-ray burst sources from BATSE observations

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon; Meegan, Charles A.; Pendleton, Geoffrey N.; Fishman, Gerald J.; Wilson, Robert B.; Paciesas, William S.; Brock, Martin N.; Horack, John M.

    1994-01-01

    The paradigm that gamma-ray bursts originate from Galactic sources is studied in detail using the angular and intensity distributions observed by the Burst and Transient Source Experiment (BATSE) on NASA's Compton Gamma Ray Observatory (CGRO). Monte Carlo models of gamma-ray burst spatial distributions and luminosity functions are used to simulate bursts, which are then folded through mathematical models of BATSE selection effects. The observed and computed angular intensity distributions are analyzed using modifications of standard statistical homogeneity and isotropy studies. Analysis of the BATSE angular and intensity distributions greatly constrains the origins and luminosities of burst sources. In particular, it appears that no single population of sources confined to a Galactic disk, halo, or localized spiral arm satisfactorily explains BATSE observations and that effects of the burst luminosity function are secondary when considering such models. One family of models that still satisfies BATSE observations comprises sources located in an extended spherical Galactic corona. Coronal models are limited to small ranges of burst luminosity and core radius, and the allowed parameter space for such models shrinks with each new burst BATSE observes. Multiple-population models of bursts are found to work only if (1) the primary population accounts for the general isotropy and inhomogeneity seen in the BATSE observations and (2) secondary populations either have characteristics similar to the primary population or contain numbers that are small relative to the primary population.

  4. Inverse Compton gamma-ray source for nuclear physics and related applications at the Duke FEL

    SciTech Connect

    O`Shea, P.G.; Litvinenko, V.N.; Madey, J.M.J.

    1995-12-31

    In recent years the development of intense, short-wavelength FEL light sources has opened opportunities for the development new applications of high-energy Compton-backscattered photons. These applications range from medical imaging with X-ray photons to high-energy physics with {gamma}{gamma} colliders. In this paper we discuss the possibilities for nuclear physics studies using polarized Compton backscattered {gamma}-rays from the Duke storage-ring-driven UV-FEL. There are currently a number of projects that produce polarized {gamma}-rays for nuclear physics studies. All of these facilities operate by scattering conventional laser-light against electrons circulating in a storage ring. In our scheme, intra-cavity scattering of the UV-FEL light will produce a {gamma}-flux enhancement of approximately 10{sup 3} over existing sources. The Duke ring can operate at energies up to 1.2 GeV and can produce FEL photons up to 12.5 eV. We plan to generate {gamma}-rays up to 200 MeV in energy with an average flux in excess of 10{sup 7} /s/MeV, using a modest scattering beam of 10-mA average stored current. The {gamma}-ray energy may be tuned by varying the FEL wavelength or by adjusting the stored electron beam energy. Because of the intense flux, we can eliminate the need for photon energy tagging by collimating of the {gamma}-ray beam. We will discuss the characteristics of the device and its research opportunities.

  5. Compact Gamma-Beam Source for Nuclear Security Technologies

    NASA Astrophysics Data System (ADS)

    Gladkikh, P.; Urakawa, J.

    2015-10-01

    A compact gamma-beam source dedicated to the development of the nuclear security technologies by use of the nuclear resonance fluorescence is described. Besides, such source is a very promising tool for novel technologies of the express cargoes inspection to prevent nuclear terrorism. Gamma-beam with the quanta energies from 0.3MeV to 7.2MeV is generated in the Compton scattering of the "green" laser photons on the electron beam with energies from 90MeV to 430MeV. The characteristic property of the proposed gammabeam source is a narrow spectrum (less than 1%) at high average gamma-yield (of 1013γ/s) due to special operation mode.

  6. QUASI-STAR JETS AS UNIDENTIFIED GAMMA-RAY SOURCES

    SciTech Connect

    Czerny, Bozena; Sikora, Marek; Janiuk, Agnieszka

    2012-08-10

    Gamma-ray catalogs contain a considerable amount of unidentified sources. Many of these are located out of the Galactic plane and therefore may have extragalactic origin. Here we assume that the formation of massive black holes in galactic nuclei proceeds through a quasi-star stage and consider the possibility of jet production by such objects. Those jets would be the sources of collimated synchrotron and Compton emission, extending from radio to gamma rays. The expected lifetimes of quasi-stars are of the order of million of years while the jet luminosities, somewhat smaller than that of quasar jets, are sufficient to account for the unidentified gamma-ray sources. The jet emission dominates over the thermal emission of a quasi-star in all energy bands, except when the jet is not directed toward an observer. The predicted synchrotron emission peaks in the IR band, with the flux close to the limits of the available IR all sky surveys. The ratio of the gamma-ray flux to the IR flux is found to be very large ({approx}60), much larger than in BL Lac objects but reached by some radio-loud quasars. On the other hand, radio-loud quasars show broad emission lines while no such lines are expected from quasi-stars. Therefore, the differentiation between various scenarios accounting for the unidentified gamma-ray sources will be possible at the basis of the photometry and spectroscopy of the IR/optical counterparts.

  7. Laser Electron Gamma Source: Biennial progress report, June 1996

    SciTech Connect

    Sandorfi, A.M.

    1996-09-01

    The LEGS facility provides intense, polarized, monochromatic {gamma}-ray beams by Compton backscattering laser light from relativistic electrons circulating in the X-Ray storage ring of the National Synchrotron Light Source at Brookhaven national Laboratory. Since 1990, experiments have concentrated on single polarization observables (polarized beams on unpolarized targets) in nuclear reactions involving the {Delta} resonance. Highlights of the last two years are given. An updated status of LEGS, and recent publications, is available on the WWW via http://WWW.LEGS.BNL.GOV/{approximately}LEGS/. In 1997 a new phase of operations will begin, focusing on double-polarization measurements with circularly polarized photon beams and longitudinally polarized nucleon targets. This work requires the development of (i) a new frozen-spin hydrogen-deuteride target that provides high polarizations for both nuclear species, and (ii) a new large acceptance detector array for measuring total reaction cross sections in both neutral and charged-particle channels. Progress on these instrumentation developments is an ongoing effort of the LEGS Spin Collaboration (LSC) and is discussed in the last section of this report.

  8. Miniature accelerator-driven gamma source concept.

    SciTech Connect

    Garnett, R. W.; Chan, K. D.; Wangler, Thomas P.,; Wood R. L.; Carlsten, B. E.; Kirbie, H. C.

    2003-01-01

    Recent developments in W-band (-100 GHz) traveling wave tube technology at Los Alarnos may lead to a compact high-power W-band RE source. A conceptual design of a compact 8-MeV electron linac that codd be powered by this source is presented, including electromagnetic structure calculations, proposed rnicrojbbrication and manufacturing methods, supporting calculations to estimate accelerator performance, and gumma production rates based on preliminary target geometries and expected output beam current.

  9. Persistent X-ray emission from a gamma-ray burst source

    NASA Technical Reports Server (NTRS)

    Grindlay, J. E.; Cline, T.; Desai, U. D.; Teegarden, B. J.; Pizzichini, G.; Evans, W. D.; Laros, J. G.; Hurley, K. C.; Niel, M.; Klebesadel, R. W.

    1982-01-01

    A quiescent X-ray source detected with the Einstein X-ray Observatory in a location consistent with that of an intense gamma ray burst is shown to be also consistent with the location of the 1928 optical transient, the likely optical counterpart of the gamma ray burst source GBS0117-29. The system appears to be underluminous in X-rays by a factor of 10; possible reasons for this are discussed. The observed X-ray flux would require an accretion rate of about 10 to the -14th (d/1 kpc/)-squared solar masses per year, which is probably too low to be consistent with published nuclear flash models for gamma bursts, unless the distance is substantially greater than about 1 kpc or the burst recurrence time is greater than about 50 yrs, or the accretion rate is highly variable. Such a long recurrence time appears to be inconsistent with the detection of the optical burst.

  10. High-precision source location of the 1978 November 19 gamma-ray burst

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Teegarden, B. J.; Pizzichini, G.; Evans, W. D.; Klebesadel, R. W.; Laros, J. G.; Barat, C.; Hurley, K.; Niel, M.

    1981-01-01

    The celestial source location of the November 19, 1978, intense gamma ray burst has been determined from data obtained with the interplanetary gamma-ray sensor network by means of long-baseline wave front timing instruments. Each of the instruments was designed for studying events with observable spectra of approximately greater than 100 keV, and each provides accurate event profile timing in the several millisecond range. The data analysis includes the following: the triangulated region is centered at (gamma, delta) 1950 = (1h16m32s, -28 deg 53 arcmin), at -84 deg galactic latitude, where the star density is very low and the obscuration negligible. The gamma-ray burst source region, consistent with that of a highly polarized radio source described by Hjellming and Ewald (1981), may assist in the source modeling and may facilitate the understanding of the source process. A marginally identifiable X-ray source was also found by an Einstein Observatory investigation. It is concluded that the burst contains redshifted positron annihilation and nuclear first-excited iron lines, which is consistent with a neutron star origin.

  11. High-intensity sources for light ions

    SciTech Connect

    Leung, K.N.

    1995-10-01

    The use of the multicusp plasma generator as a source of light ions is described. By employing radio-frequency induction discharge, the performance of the multicusp source is greatly improved, both in lifetime and in high brightness H{sup +} and H{sup {minus}} beam production. A new technique for generating multiply-charged ions in this type of ion source is also presented.

  12. (Gamma scattering in condensed matter with high intensity Moessbauer radiation)

    SciTech Connect

    Not Available

    1992-01-01

    This report discusses: quasielastic scattering studies on glycerol; gamma-ray scattering from alkali halides; lattice dynamics in metals; Moessbauer neutron scattering, x-ray diffraction, and macroscopic studies of high {Tc} superconductors containing tungsten; NiAl scattering studies; and atomic interference factors and nuclear Casimir effect.

  13. Cathodoluminescent Source of Intense White Light

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2007-01-01

    The device described exploits cathodoluminescence to generate intense light in the visible and near-infrared regions of the spectrum. In this device, the material to be excited to luminescence is a layer of quartz or alumina powder on an electrically conductive plate exposed to a low-pressure plasma discharge. The plate is electrically biased positively to collect electron current.

  14. Rapidly pulsed, high intensity, incoherent light source

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr.; Brandhorst, H. W., Jr. (Inventor)

    1974-01-01

    A rapid pulsing, high intensity, incoherent light is produced by selectively energizing a plurality of discharge lamps with a triggering circuit. Each lamp is connected to a capacitor, and a power supply is electrically connected to all but one of the capacitors. This last named capacitor is electrically connected to a discharge lamp which is connected to the triggering circuit.

  15. HIGH-INTENSITY, HIGH CHARGE-STATE HEAVY ION SOURCES

    SciTech Connect

    ALESSI,J.G.

    2004-08-16

    There are many accelerator applications for high intensity heavy ion sources, with recent needs including dc beams for RIA, and pulsed beams for injection into synchrotrons such as RHIC and LHC. The present status of sources producing high currents of high charge state heavy ions is reviewed. These sources include ECR, EBIS, and Laser ion sources. Benefits and limitations for these type sources are described. Possible future improvements in these sources are also mentioned.

  16. An improved high intensity recycling helium-3 beam source

    SciTech Connect

    Hedgeland, H.; Kole, P. R.; Allison, W.; Ellis, J.; Jardine, A. P.

    2009-07-15

    We describe an improved high intensity, recycling, supersonic atomic beam source. Changes address several issues previously limiting performance and reliability of the apparatus, including the use of newly available vacuum pumps and modifications to the recycling system. We achieve a source intensity of 2.5x10{sup 19} atoms/s/sr, almost twice that previously achievable during recycling. Current limits on intensity are discussed.

  17. Search for new stellar sources of gamma-rays

    NASA Astrophysics Data System (ADS)

    Martí, Josep; Sánchez-Ayaso, Estrella; Luque-Escamilla, Pedro L.; Sánchez-Sutil, Juan R.

    2013-12-01

    We review and report about the present status of our search for gamma-ray binaries, microquasars, and new kinds of gamma-ray source associated with star forming regions in the Galaxy. The search is being carried out using cross-identification techniques applied to public databases and archives. A few promising candidates have been so far identified. These include the emission line star VES 737 and the central cluster of the Monoceros R2 star forming region. The observational data supporting the proposed associations is shortly presented and discussed.

  18. Design and Initial Operation of a Tunable Compton-Scattering Based Gamma-Ray Source

    NASA Astrophysics Data System (ADS)

    Gibson, David; Anderson, Scott; Betts, Shawn; Johnson, Micah; McNabb, Dennis; Messerly, Mike; Pruet, Jason; Shverdin, Miroslav; Tremaine, Aaron; Hartemann, Fred; Siders, Craig; Barty, Chris

    2007-11-01

    Tunable, monochromatic gamma-ray sources are currently being developed at LLNL for nuclear photo-science and related applications. These novel systems are based on Compton scattering of laser photons by a high brightness relativistic electron beam produced by an rf photoinjector and offer a path to high-brightness high-energy (> 1 MeV) x-ray & gamma-rays due to their favorable scaling with electron energy. The current demonstration source, called the ``Thomson-Radiated Extreme X-Ray" (T-REX) source, targets photon energies up to 1 MeV. With extensive modeling using PARMELA and well-benchmarked custom Compton-scattering simulation codes, the optimal design parameters for an interaction (including factors such as the collision angle, focal spot size, bunch charge, laser intensity, pulse duration, and laser beam path) can be determined. Here we present the results of this optimization, including early experimental results from the newly commissioned system.

  19. Final SAS-2 gamma ray results on sources in the galactic anticenter region

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Lamb, R. C.

    1976-01-01

    Analysis of SAS-2 high energy Gamma ray data from the direction of the galactic anticenter shows that this region is characterized by: a diffuse emission from the galactic plane which has a maximum along b=0 deg and an enhancement toward negative latitudes associated with Gould's Belt, a strong point source in the direction of the Crab nebula, and a second intense localized source near galactic coordinates 195 deg, +5 deg. Gamma ray emission from the Crab source is dominated by a pulsed flux from PSR 0531+21. The total flux above 100MeV is 3.7 + or - 0.8 million/sq cm s. The source near 195 deg, + 5 deg has a flux above 100 MeV of 4.3 + or - 0.9 million/sq cm s. Its spectrum appears flatter than that of the Crab. The diffuse galactic plane emission at negative lattitudes shows a general correlation with the local matter distribution associated with Gould's Belt. The calculated Gamma ray intensity agrees well with the SAS-2 observations.

  20. High-energy gamma-ray sources of cosmological origin

    NASA Astrophysics Data System (ADS)

    Brun, Pierre; Cohen-Tanugi, Johann

    2016-06-01

    The current generation of instruments in gamma-ray astrophysics launched a new era in the search for a dark matter signal in the high-energy sky. Such searches are said indirect, in the sense that the presence of a dark matter particle is inferred from the detection of products of its pair-annihilation or decay. They have recently started to probe the natural domain of existence for weakly interacting massive particles (WIMPs), the favorite dark matter candidates today. In this article, we review the basic framework for indirect searches and we present a status of current limits obtained with gamma-ray observations. We also devote a section to another possible class of cosmological gamma-ray sources, primordial black holes, also considered as a potential constituent of dark matter. xml:lang="fr"

  1. Total Absorption Gamma-ray Spectrometer (TAGS) Intensity Distributions from INL's Gamma-Ray Spectrometry Center

    DOE Data Explorer

    Greenwood, R. E.

    A 252Cf fission-product source and the INL on-line isotope separator were used to supply isotope-separated fission-product nuclides to a total absorption -ray spectrometer. This spectrometer consisted of a large (25.4-cm diameter x 30.5-cm long) NaI(Tl) detector with a 20.3-cm deep axial well in which is placed a 300-mm2 x 1.0-mm Si detector. The spectra from the NaI(Tl) detector are collected both in the singles mode and in coincidence with the B-events detected in the Si detector. Ideally, this detector would sum all the energy of the B- rays in each cascade following the population of daughter level by B- decay, so that the event could be directly associated with a particular daughter level. However, there are losses of energy from attenuation of the rays before they reach the detector, transmission of rays through the detector, escape of secondary photons from Compton scattering, escape of rays through the detector well, internal conversion, etc., and the measured spectra are thus more complicated than the ideal case and the analysis is more complex. Analysis methods have been developed to simulate all of these processes and thus provide a direct measure of the B- intensity distribution as a function of the excitation energy in the daughter nucleus. These data yield more accurate information on the B- distribution than conventional decay-scheme studies for complex decay schemes with large decay energies, because in the latter there are generally many unobserved and observed but unplaced rays. The TAGS data have been analyzed and published [R. E. Greenwood et al., Nucl Instr. and metho. A390(1997)] for 40 fission product-nuclides to determine the B- intensity distributions. [Copied from the TAGS page at http://www.inl.gov/gammaray/spectrometry/tags.shtml]. Those values are listed on this page for quick reference.

  2. Status of the intense pulsed neutron source

    SciTech Connect

    Brown, B.S.; Carpenter, J.M.; Crawford, R.K.; Rauchas, A.V.; Schulke, A.W.; Worlton, T.G.

    1988-01-01

    IPNS is not unique in having concerns about the level of funding, and the future looks good despite these concerns. This report details the progress made at IPNS during the last two years. Other papers in these proceedings discuss in detail the status of the enriched uranium Booster target, the two instruments that are under construction, GLAD and POSY II, and a proposal for research on an Advanced Pulsed Neutron Source (ASPUN) that has been submitted to the Department of Energy (DOE). Further details on IPNS are available in the IPNS Progress Report 1987--1988, available by writing the IPNS Division Office. 9 refs., 3 tabs.

  3. Intense polarized /sup 3/He ion source

    SciTech Connect

    Slobodrian, R.J.; Bertrand, R.; Grioux, J.; Labrie, R.; Lapainte, R.; Meunier, J.F.; Pigeon, G.; Pouliot, L.; Rioux, C.; Roy, R.

    1985-10-01

    This source is based on the atomic polarization of the 2/sup 3/S/sub 1/ metastable state of the neutral atom. A version suitable for operation on the high voltage terminal of a CN Van de Graaff has been constructed, bench tested and installed in the terminal of a 7.5 MV machine. The polarization of the atomic beam is higher than 90%. It is now fully operational and a current of /sup 3/He/sup +/ of 300 nA has been measured after acceleration.

  4. Turbulence generation through intense kinetic energy sources

    NASA Astrophysics Data System (ADS)

    Maqui, Agustin F.; Donzis, Diego A.

    2016-06-01

    Direct numerical simulations (DNS) are used to systematically study the development and establishment of turbulence when the flow is initialized with concentrated regions of intense kinetic energy. This resembles both active and passive grids which have been extensively used to generate and study turbulence in laboratories at different Reynolds numbers and with different characteristics, such as the degree of isotropy and homogeneity. A large DNS database was generated covering a wide range of initial conditions with a focus on perturbations with some directional preference, a condition found in active jet grids and passive grids passed through a contraction as well as a new type of active grid inspired by the experimental use of lasers to photo-excite the molecules that comprise the fluid. The DNS database is used to assert under what conditions the flow becomes turbulent and if so, the time required for this to occur. We identify a natural time scale of the problem which indicates the onset of turbulence and a single Reynolds number based exclusively on initial conditions which controls the evolution of the flow. It is found that a minimum Reynolds number is needed for the flow to evolve towards fully developed turbulence. An extensive analysis of single and two point statistics, velocity as well as spectral dynamics and anisotropy measures is presented to characterize the evolution of the flow towards realistic turbulence.

  5. High Intensity Accelerator and Neutron Source in China

    NASA Astrophysics Data System (ADS)

    Guan, Xialing; Wei, J.; Loong, Chun

    2011-06-01

    High intensity Accelerator is being studied all over world for numerous applications, which includes the waste transmutation, spallation neutron source and material irradiation facilities. The R/D activities of the technology of High intensity accelerator are also developed in China for some year, and have some good facilities around China. This paper will reports the status of some high intensity accelerators and neutron source in China, which including ADS/RFQ; CARR; CSNS; PKUNIFTY & CPHS. This paper will emphatically report the Compact Pulsed Hadron Source (CPHS) led by the Department of Engineering Physics of Tsinghua University in Beijing, China.

  6. Energy spectrum of extragalactic gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Protheroe, R. J.

    1985-01-01

    The result of Monte Carlo electron photon cascade calculations for propagation of gamma rays through regions of extragalactic space containing no magnetic field are given. These calculations then provide upper limits to the expected flux from extragalactic sources. Since gamma rays in the 10 to the 14th power eV to 10 to the 17th power eV energy range are of interest, interactions of electrons and photons with the 3 K microwave background radiation are considered. To obtain an upper limit to the expected gamma ray flux from sources, the intergalactic field is assumed to be so low that it can be ignored. Interactions with photons of the near-infrared background radiation are not considered here although these will have important implications for gamma rays below 10 to the 14th power eV if the near infrared background radiation is universal. Interaction lengths of electrons and photons in the microwave background radiation at a temperature of 2.96 K were calculated and are given.

  7. Development of Compton gamma-ray sources at LLNL

    SciTech Connect

    Albert, F.; Anderson, S. G.; Ebbers, C. A.; Gibson, D. J.; Hartemann, F. V.; Marsh, R. A.; Messerly, M. J.; Prantil, M. A.; Wu, S.; Barty, C. P. J.

    2012-12-21

    Compact Compton scattering gamma-ray sources offer the potential of studying nuclear photonics with new tools. The optimization of such sources depends on the final application, but generally requires maximizing the spectral density (photons/eV) of the gamma-ray beam while simultaneously reducing the overall bandwidth on target to minimize noise. We have developed an advanced design for one such system, comprising the RF drive, photoinjector, accelerator, and electron-generating and electron-scattering laser systems. This system uses a 120 Hz, 250 pC, 2 ps, 0.35 mm mrad electron beam with 250 MeV maximum energy in an X-band accelerator scattering off a 150 mJ, 10 ps, 532 nm laser to generate 5 Multiplication-Sign 10{sup 10} photons/eV/s/Sr at 0.5 MeV with an overall bandwidth of less than 1%. The source will be able to produce photons up to energies of 2.5 MeV. We also discuss Compton scattering gamma-ray source predictions given by numerical codes.

  8. Development of Compton gamma-ray sources at LLNL

    NASA Astrophysics Data System (ADS)

    Albert, F.; Anderson, S. G.; Ebbers, C. A.; Gibson, D. J.; Hartemann, F. V.; Marsh, R. A.; Messerly, M. J.; Prantil, M. A.; Wu, S.; Barty, C. P. J.

    2012-12-01

    Compact Compton scattering gamma-ray sources offer the potential of studying nuclear photonics with new tools. The optimization of such sources depends on the final application, but generally requires maximizing the spectral density (photons/eV) of the gamma-ray beam while simultaneously reducing the overall bandwidth on target to minimize noise. We have developed an advanced design for one such system, comprising the RF drive, photoinjector, accelerator, and electron-generating and electron-scattering laser systems. This system uses a 120 Hz, 250 pC, 2 ps, 0.35 mm mrad electron beam with 250 MeV maximum energy in an X-band accelerator scattering off a 150 mJ, 10 ps, 532 nm laser to generate 5 × 1010 photons/eV/s/Sr at 0.5 MeV with an overall bandwidth of less than 1%. The source will be able to produce photons up to energies of 2.5 MeV. We also discuss Compton scattering gamma-ray source predictions given by numerical codes.

  9. Determination of the optimum-size californium-252 neutron source for borehole capture gamma-ray analysis

    USGS Publications Warehouse

    Senftle, F.E.; Macy, R.J.; Mikesell, J.L.

    1979-01-01

    The fast- and thermal-neutron fluence rates from a 3.7 ??g 252Cf neutron source in a simulated borehole have been measured as a function of the source-to-detector distance using air, water, coal, iron ore-concrete mix, and dry sand as borehole media. Gamma-ray intensity measurements were made for specific spectral lines at low and high energies for the same range of source-to-detector distances in the iron ore-concrete mix and in coal. Integral gamma-ray counts across the entire spectrum were also made at each source-to-detector distance. From these data, the specific neutron-damage rate, and the critical count-rate criteria, we show that in an iron ore-concrete mix (low hydrogen concentration), 252Cf neutron sources of 2-40 ??g are suitable. The source size required for optimum gamma-ray sensitivity depends on the energy of the gamma ray being measured. In a hydrogeneous medium such as coal, similar measurements were made. The results show that sources from 2 to 20 ??g are suitable to obtain the highest gamma-ray sensitivity, again depending on the energy of the gamma ray being measured. In a hydrogeneous medium, significant improvement in sensitivity can be achieved by using faster electronics; in iron ore, it cannot. ?? 1979 North-Holland Publishing Co.

  10. Gamma evaluation combined with isocenter optimal matching in intensity modulated radiation therapy quality assurance

    NASA Astrophysics Data System (ADS)

    Bak, Jino; Choi, Jin Hwa; Park, Suk Won; Park, Kwangwoo; Park, Sungho

    2015-12-01

    Two-dimensional (2D) dose comparisons are widely performed by using a gamma evaluation with patient-specific intensity modulated radiation therapy quality assurance (IMRT QA) or dose delivery quality assurance (DQA). In this way, a pass/fail determination is made for a particular treatment plan. When gamma evaluation results are close to the failure criterion, the pass/fail decision may change applying a small shift to the center of the 2D dose distribution. In this study, we quantitatively evaluated the meaning of such a small relative shift in a 2D dose distribution comparison. In addition, we propose the use of a small shift for a pass/fail criterion in gamma analysis, where the concept of isocenter optimal matching (IOM) is applied to IMRT QA of 20 patients. Gamma evaluations were performed to compare two dose distributions, one with and the other without IOM. In-house software was developed in C++ in order to find IOM values including both translational and rotational shifts. Upon gamma evaluation failure, further investigation was initiated using IOM. In this way, three groups were categorized: group 1 for `pass' on gamma evaluation, group 21 for `fail' on the gamma evaluation and `pass' on the gamma the evaluation with IOM, and group 22 for `fail' on the both gamma evaluations and the IOM calculation. IOM results revealed that some failures could be considered as a `pass'. In group 21, 88.98% (fail) of the averaged gamma pass rate changed to 90.45% (pass) when IOM was applied. On average, a ratio of γ ≥ 1 was reduced by 11.06% in 20 patients. We propose that gamma evaluations that do not pass with a rate of 85% to 90% may be augmented with IOM to reveal a potential pass result.

  11. High-energy gamma radiation from extragalactic radio sources

    NASA Technical Reports Server (NTRS)

    Dermer, C. D.; Schlickeiser, R.; Mastichiadis, A.

    1992-01-01

    We propose that the important relationship between 3C 273 and 3C 279, the first two extragalactic sources detected at over 100 MeV energies, is their superluminal nature. In support of this conjecture, we propose a kinematic focusing mechanism, based on Compton scattering of accretion-disk photons by relativistic nonthermal electrons in the jet, that preferentially emits gamma rays in the superluminal direction.

  12. Gamma-Ray Compton Light Source Development at LLNL

    NASA Astrophysics Data System (ADS)

    Hartemann, Frederic; Anderson, Scott; Gibson, David; Hagmann, Chris; Johnson, Micah; Jovanovic, Igor; Messerly, Mike; Pruet, Jason; Shverdin, Miro; Tremaine, Aaron; McNabb, Dennis; Siders, Craig; Barty, Chris

    2007-03-01

    A new class of tunable, monochromatic gamma-ray sources capable of operating at high peak and average brightness is currently being developed at LLNL for nuclear photo-science and applications. These novel systems are based on Compton scattering of laser photons by a high brightness relativistic electron beam produced by an rf photoinjector. Key technologies, basic scaling laws, and recent experimental results will be presented, along with an overview of future research and development directions.

  13. Compact Gamma-ray Source Technology Development Study

    SciTech Connect

    Anderson, S G; Gibson, D J; Rusnak, B

    2009-09-25

    This study focuses on the applicability of current accelerator and laser technologies to the construction of compact, narrow bandwidth, gamma-ray sources for DHS missions in illicit materials detection. It also identifies research and development areas in which advancement will directly benefit these light sources. In particular, we review the physics of Compton scattering based light sources and emphasize the source properties most important to Nuclear Resonance Fluorescence (NRF) applications of interest. The influences of laser and electron beam properties on the light source are examined in order to evaluate the utility of different technologies for this application. Applicable bulk and fiber-based laser systems and laser recirculation technologies are discussed and Radio Frequency (RF) Linear Accelerator (linac) technologies are examined to determine the optimal frequency and pulse formats achievable.

  14. More data on (possible) gamma ray (point) sources

    NASA Technical Reports Server (NTRS)

    Hermsen, W.

    1990-01-01

    The 2CG catalog of gamma ray sources was compiled before detailed knowledge was available on the fine-scale structure of the diffuse Galactic gamma-ray emission. Two independent analyses to discriminate sources which are either compact objects of due to very local and strong enhancements in the Galactic cosmic-ray distribution from those which are artifacts due to the clumpy gas distribution are about to be completed: a maximum likelihood analysis and a cross correlation analysis. Arguments are given why differences, and therefore confusion, and in resulting source lists can be expected. Detailed analysis of all COS-B gamma-ray data on Geminga (2CG195+04), reveals the existence of a drastic spectral break below 200 MeV. A power-law spectrum with index -1.88 fits the data above about 100 MeV to 3.2 GeV, however, there are also indications for a spectral break above these energies. For energies above about 100 MeV no evidence for a long-term time variability was found. The error region of Geminga was searched for a radio counterpart at wavelengths of 90, 49, 21, 6, and 2 cm using the Westerbork Synthesis Radio Telescope and the Very Large Array. So far, 16 sources were detected in this error region. In the direction of 1E0630+178, the Einstein x ray source proposed to be a Vela-like pulsar and the counterpart of Geminga, no radio source was found at 21, 49, and 90 cm with 3 sigma upper limits on the flux densities ranging from 0.5 mJy at 21 cm to 4.5 mJy at 90 cm. Detailed structures in local molecular cloud complexes are so far only resolved in gamma rays for the closet and most massive complexes, namely those in the Orion-Monoceros and the Ophiuchus regions. For both region, there is circumstantial evidence for gamma ray emission from molecular gas that was photodissociated after the passage of a SN shell.

  15. Methodological problems with gamma-ray burst hardness/intensity correlations

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.

    1993-01-01

    The hardness and intensity are easily measured quantities for all gamma-ray bursts (GRBs), and so, many past and current studies have sought correlations between them. This Letter presents many serious methodological problems with the practical definitions for both hardness and intensity. These difficulties are such that significant correlations can be easily introduced as artifacts of the reduction procedure. In particular, cosmological models of GRBs cannot be tested with hardness/intensity correlations with current instrumentation and the time evolution of the hardness in a given burst may be correlated with intensity for reasons that are unrelated to intrinsic change in the spectral shape.

  16. Gamma-ray observations of Ophiuchus with EGRET: The diffuse emission and point sources

    NASA Technical Reports Server (NTRS)

    Hunter, S. D.; Digel, S. W.; De Geus, E. J.; Kanbach, G.

    1994-01-01

    Observations of the Ophiuchus region made with the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) during the first 2 1/2 years of operation show the diffuse emission from the interstellar gas in Ophiuchus as well as variable emission from two point sources. The gamma-ray emission is modeled in terms of cosmic-ray interactions with atomic and molecular hydrogen in Ophiuchus and with low-energy photons along the line of sight. The model also includes the flux from the two point sources and an isotropic diffuse contribution. The cosmic-ray density is assumed to be uniform. The derived ratio of molecular hydrogen column density to integrated CO intensity is (1.1 +/- 0.2) x 10(exp 20) H-mols/sq cm (K km/s)(exp -1). At the sensitivity and resolution of the gamma-ray data, no variation of this ratio over the modeled region is discernible, nor are any regions of enhanced cosmic-ray density apparent. The model was fitted to seven narrow energy bands to obtain the energy depedence of the gamma-ray production function and the spectra of the point sources. The derived production function is in good agreement with theoretical calculations and the local cosmic-ray electron and proton spectra. The positions of the point sources were determined from maximum likelihood analysis of the gamma-ray emission observed in excess of the diffuse model. We identify one point source with the quasar PKS 1622-253, which has an average flux, E greater than 100 MeV, of (2.5 +/- 0.5) x 10(exp -7) photons/sq cm/s and photon spectral index -1.9 +/- 0.3. The other source, denoted GRO J1631-27, has not yet been identified at other wavelengths. Its average flux, E greater than 100 MeV, is (1.1 +/- 0.4) x 10(exp -7) photons/sq cm/s; however, its spectral index is poorly determined. The spectral index and intensity of the isotropic contribution to the model agree well with the extragalactic diffuse emission derived from the SAS 2 data.

  17. Ion source and injection line for high intensity medical cyclotron

    SciTech Connect

    Jia, XianLu Guan, Fengping; Yao, Hongjuan; Zhang, TianJue; Yang, Jianjun; Song, Guofang; Ge, Tao; Qin, Jiuchang

    2014-02-15

    A 14 MeV high intensity compact cyclotron, CYCIAE-14, was built at China Institute of Atomic Energy (CIAE). An injection system based on the external H− ion source was used on CYCIAE-14 so as to provide high intensity beam, while most positron emission tomography cyclotrons adopt internal ion source. A beam intensity of 100 μA/14 MeV was extracted from the cyclotron with a small multi-cusp H− ion source (CIAE-CH-I type) and a short injection line, which the H− ion source of 3 mA/25 keV H− beam with emittance of 0.3π mm mrad and the injection line of with only 1.2 m from the extraction of ion source to the medial plane of the cyclotron. To increase the extracted beam intensity of the cyclotron, a new ion source (CIAE-CH-II type) of 9.1 mA was used, with maximum of 500 μA was achieved from the cyclotron. The design and test results of the ion source and injection line optimized for high intensity acceleration will be given in this paper.

  18. Ion source and injection line for high intensity medical cyclotron

    NASA Astrophysics Data System (ADS)

    Jia, XianLu; Guan, Fengping; Yao, Hongjuan; Zhang, TianJue; Yang, Jianjun; Song, Guofang; Ge, Tao; Qin, Jiuchang

    2014-02-01

    A 14 MeV high intensity compact cyclotron, CYCIAE-14, was built at China Institute of Atomic Energy (CIAE). An injection system based on the external H- ion source was used on CYCIAE-14 so as to provide high intensity beam, while most positron emission tomography cyclotrons adopt internal ion source. A beam intensity of 100 μA/14 MeV was extracted from the cyclotron with a small multi-cusp H- ion source (CIAE-CH-I type) and a short injection line, which the H- ion source of 3 mA/25 keV H- beam with emittance of 0.3π mm mrad and the injection line of with only 1.2 m from the extraction of ion source to the medial plane of the cyclotron. To increase the extracted beam intensity of the cyclotron, a new ion source (CIAE-CH-II type) of 9.1 mA was used, with maximum of 500 μA was achieved from the cyclotron. The design and test results of the ion source and injection line optimized for high intensity acceleration will be given in this paper.

  19. Particle Acceleration Inside Thunderstorms and the Variation in Source Spectra of Terrestrial Gamma-ray Flashes

    NASA Astrophysics Data System (ADS)

    Cramer, Eric; Dwyer, Joseph R.; Briggs, Michael S.; Rassoul, Hamid K.

    2016-03-01

    One of the unresolved questions in the atmospheric sciences is the origin of Terrestrial Gamma-ray Flashes (TGFs). These flashes are short but intense gamma ray bursts emanating from Earth's atmosphere. This phenomenon has been observed by gamma ray detectors on orbiting satellites, e.g. NASA Fermi, intended to study astrophysical phenomena such as Gamma-ray Bursts. TGFs are thought to originate inside thunderstorms where electrons can be accelerated and emit radiation in the multi MeV range due to bremsstrahlung interactions with air molecules. These so called ``runaway electrons'' are seeded from cosmic ray air showers hitting the Earth's atmosphere from (extra) galactic sources. In this work, we present a Monte Carlo model that simulates particle physics inside a thunderstorm region. The subsequent transport of high energy gamma rays through the Earth's atmosphere and up to satellite orbit is also included. We show that by varying both the potential difference and the ambient electric field inside the thundercloud, different electron and photon energy distributions are produced. This effect may be detectable by orbiting spacecraft, and therefore serves as a method to remote sense the electric fields that exist inside thunderstorms.

  20. Repeating sources of classical gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Wang, V. C.; Lingenfelter, R. E.

    1995-01-01

    From an analysis of the first catalog of the Burst and Transient Source Experiment (BATSE) experiment (Fishman et al. 1993, 1994a) on the Compton Gamma Ray Observatory (CGRO), we find an excessive number of pairs of gamma-ray bursts which are clustered in both a space and time . The angular separation between the two bursts in each pair is less than their positional uncertainties, and the interval between their occurrence times is within several days. Optimizing the signal, we find that the probability of observing such a clustered excess froma Poisson ensemble is approximately 2 x 10(exp -5). We suggest that these bursts arise from repeating sources. A detailed study of the most prolific source, GBS 0855-00, is presented in a separate paper (Wang & Lingenfelter 1993a, b). Unlike most of the 'soft' gamma-ray repeaters, these repeating bursts have relatively hard spectra, complex light curves, and widely varying durations, that are indistinguishable from classical gamma-ray bursts. Although the significance of the clustered excess was optimized a posteriori, because it depends on temporal and spatial bin sized that could not be defined a priori, we can use the optimizations from the first catalog to test subsequent BATSE data sets. Unfortunately, the failure of the on-board tape recorders during the second catalog period seriously reduced the number of accurately positioned bursts (Fishman et al. 1994b), so that we can neither confirm, nor refute, the predicted repitition in that sample, and we must await the results of the third catalog.

  1. Measuring the activity of a {sup 51}Cr neutrino source based on the gamma-radiation spectrum

    SciTech Connect

    Gorbachev, V. V. Gavrin, V. N.; Ibragimova, T. V.; Kalikhov, A. V.; Malyshkin, Yu. M.; Shikhin, A. A.

    2015-12-15

    A technique for the measurement of activities of intense β sources by measuring the continuous gamma-radiation (internal bremsstrahlung) spectra is developed. A method for reconstructing the spectrum recorded by a germanium semiconductor detector is described. A method for the absolute measurement of the internal bremsstrahlung spectrum of {sup 51}Cr is presented.

  2. The Average Intensity and Spectral Evolution of Batse Cosmic Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Mitrofanov, Igor G.; Chernenko, Anton M.; Pozanenko, Alexei S.; Briggs, Michael S.; Paciesas, William S.; Fishman, Gerald J.; Meegan, Charles A.; Sagdeev, Roald Z.

    1996-01-01

    Statistical studies of BATSE gamma-ray bursts are presented: we average the time profiles, aligning the events at their highest peaks. Using the time histories in different energy channels, we summarize the general features of the average intensity and spectral evolution of gamma-ray bursts (GRBS) and compare the average evolution of bright and dim events. While no differences are found between the average intensity histories, the average hardness ratio histories demonstrate a hardness/brightness correlation. The observed lack of differences between the intensity histories of bright and dim bursts is incompatible with cosmological time dilation effects predicted by simple cosmological models. The combined results of no intensity history difference but a hardness history difference between bright and dim bursts places constraints on galactic models for the origin of GRBS.

  3. Status of Identification of VHE Gamma-Ray Sources

    SciTech Connect

    Funk, Stefan; /SLAC

    2006-09-28

    With the recent advances made by Cherenkov telescopes such as H.E.S.S. the field of very high-energy (VHE) {gamma}-ray astronomy has recently entered a new era in which for the first time populations of Galactic sources such as e.g. Pulsar wind nebulae (PWNe) or Supernova remnants (SNRs) can be studied. However, while some of the new sources can be associated by positional coincidence as well as by consistent multi-wavelength data to a known counterpart at other wavelengths, most of the sources remain not finally identified. In the following, the population of Galactic H.E.S.S. sources will be used to demonstrate the status of the identifications, to classify them into categories according to this status and to point out outstanding problems.

  4. Variable optical/infrared counterpart to the transient gamma-ray source J0109+6134

    NASA Astrophysics Data System (ADS)

    Fernández-Valenzuela, E.; Martí, J.; Luque-Escamilla, P. L.; Muñoz-Arjonilla, A. J.; Paredes, J. M.

    2014-01-01

    Context. We investigate the optical/infrared counterpart to the flaring gamma-ray source J0109+6134, which is believed to be a blazar seen through the Galactic plane. Aims: The original aim of this work was to confirm the previously proposed optical counterpart by means of studying its temporal behaviour. The study was later extended to infrared wavelengths as new data became available. Methods: We conducted a long-term differential CCD photometry campaign using the robotic Liverpool telescope. In addition, we used infrared satellite observations to also explore the source variability at these longer wavelengths. Results: Evidence of variability well correlated with gamma-ray flares has been observed so far only in the infrared domain. This fact strongly supports that the proposed optical/infrared counterpart identification is correct. Moreover, our optical photometric campaign revealed an intense optical flare with 1.7 mag amplitude that occurs on time-scales of weeks. This optical event was observed to evolve without a counterpart in the nearly simultaneous gamma-ray monitoring by the Fermi satellite. Gamma-ray orphan optical flares have rarely been observed in other blazars, and J0109+6134 appears to be an interesting additional example for future studies.

  5. Overview of Mono-Energetic Gamma-Ray Sources and Applications

    SciTech Connect

    Hartemann, Fred; Albert, Felicie; Anderson, Scott; Barty, Christopher; Bayramian, Andy; Chu, Tak Sum; Cross, R.; Ebbers, Chris; Gibson, David; Marsh, Roark; McNabb, Dennis; Messerly, Michael; Shverdin, Miroslav; Siders, Craig; Jongewaard, Erik; Raubenheimer, Tor; Tantawi, Sami; Vlieks, Arnold; Semenov, Vladimir; /UC, Berkeley

    2012-06-25

    Recent progress in accelerator physics and laser technology have enabled the development of a new class of tunable 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 Mono-Energetic Gamma-ray (MEGa-ray) source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linac designed in collaboration with SLAC NAL will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. This MEGaray source will be used to excite nuclear resonance fluorescence 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, along with important applications, including nuclear resonance fluorescence.

  6. Strategies for Studying the Sources of Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Norris, J. P.; Hurley, K. C.

    2003-01-01

    The study of gamma ray bursts (GRBs) has rapidly evolved in recent years with the discovery of their cosmological nature and with BATSE, BeppoSAX, HETE and the IPN enabling a wide variety of associated . afterglow measurements. Multiwavelength observations ranging through the radio, optical, soft and hard x-ray, and gamma-ray regimes have exploded the field of GRB interpretation. Also, the Amanda, Milagro and LIGO experiments can search for related neutrino, cosmic-ray photon, and gravitational radiation events, even with the delayed alerts, such as from the IPN. The infrared region, where the optical emissions from sources at the extreme distances may be shifted, will become important but is undersubscribed. The soon-to-be launched Swift mission will greatly broaden the GRB discipline, and a strategy for associated ground-based measurements is outlined. The need for the improved global distribution of all instruments, in particular, robotic infrared detectors, is cited.

  7. Galactic sources of TeV gamma rays.

    NASA Astrophysics Data System (ADS)

    Hillas, A. M.

    A ground-based Cerenkov detector of TeV gamma rays can have a somewhat greater counting rate than the EGRET detector of GeV gamma rays, but with a large background count rate. Using the imaging technique this background can be reduced by orders of magnitude, but so far only one galactic source (the Crab nebula) stands out steadily above noise. At least one other supernova remnant deserves study now in the TeV region. Attention is drawn to the fact that virtually all claimed galactic TeV sources (detected generally by non-imaging techniques) are episodic, generally seeming to pulsate at neutron-star spin frequencies, but there are now two or three sources reported to pulsate somewhat faster than the neutron star, suggesting a seat for the acceleration in the accretion disc. Because of the statistics of emission episodes, we need a technique that can deliver longer observations of particular sources to test the reproducibility of some results.

  8. INTEGRAL/SPI data segmentation to retrieve source intensity variations

    NASA Astrophysics Data System (ADS)

    Bouchet, L.; Amestoy, P. R.; Buttari, A.; Rouet, F.-H.; Chauvin, M.

    2013-07-01

    Context. The INTEGRAL/SPI, X/γ-ray spectrometer (20 keV-8 MeV) is an instrument for which recovering source intensity variations is not straightforward and can constitute a difficulty for data analysis. In most cases, determining the source intensity changes between exposures is largely based on a priori information. Aims: We propose techniques that help to overcome the difficulty related to source intensity variations, which make this step more rational. In addition, the constructed "synthetic" light curves should permit us to obtain a sky model that describes the data better and optimizes the source signal-to-noise ratios. Methods: For this purpose, the time intensity variation of each source was modeled as a combination of piecewise segments of time during which a given source exhibits a constant intensity. To optimize the signal-to-noise ratios, the number of segments was minimized. We present a first method that takes advantage of previous time series that can be obtained from another instrument on-board the INTEGRAL observatory. A data segmentation algorithm was then used to synthesize the time series into segments. The second method no longer needs external light curves, but solely SPI raw data. For this, we developed a specific algorithm that involves the SPI transfer function. Results: The time segmentation algorithms that were developed solve a difficulty inherent to the SPI instrument, which is the intensity variations of sources between exposures, and it allows us to obtain more information about the sources' behavior. Based on observations with INTEGRAL, an ESA project with instruments and science data centre funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Spain, and Switzerland), Czech Republic and Poland with participation of Russia and the USA.

  9. LED intense headband light source for fingerprint analysis

    DOEpatents

    Villa-Aleman, Eliel

    2005-03-08

    A portable, lightweight and high-intensity light source for detecting and analyzing fingerprints during field investigation. On-site field analysis requires long hours of mobile analysis. In one embodiment, the present invention comprises a plurality of light emitting diodes; a power source; and a personal attachment means; wherein the light emitting diodes are powered by the power source, and wherein the power source and the light emitting diodes are attached to the personal attachment means to produce a personal light source for on-site analysis of latent fingerprints. The present invention is available for other applications as well.

  10. Solitary neutron stars as gamma-ray sources

    NASA Astrophysics Data System (ADS)

    Ruderman, M.

    Very high energy particle accelerators exist in the outer magnetospheres of some rapidly spinning solitary radiopulsars. The production of e± pairs and γ-rays associated with these accelerators evolves as the pulsar spins down. Expected evolution proceeds from a weak γ-ray source to a stronger Crab-like pulsar, then to a Vela-like pulsar, to a much stronger Cos B source, and, after several 104years, to an extinct aligned Vela-like neutron star whose further spin-down is quenched. The latter can be reignited to be a transient Gamma Ray Burst source by various "match-like" phenomena. Reasons are given for the different evolution of canonical radiopulsars. Outer magnetosphere accelerators in millisecond pulsars and around magnetized neutron stars with accretion disks are also considered.

  11. Detection of a flaring low-energy gamma-ray source

    NASA Technical Reports Server (NTRS)

    Bhattacharya, Dipen; Owens, Alan

    1994-01-01

    We report the detection of a flaring gamma-ray source by the University of New Hampshire (UNH) balloon-borne coded aperture gamma-ray telescope (DGT) on 1984 October 2. The source was detected at the significance level of 7.2 sigma over the energy range 160-2000 keV. The intensity in the range (160-200) keV was 1.1 Crab. The best-fit position of the source is given by R.A. = 3h 25.8m and Decl. = 67 deg 653 min and is located in the constellation of Camelopardia. The source was visible within the Field of View (FOV) of the telescope for approximately = 2 hr and exhibited signs of flaring. The derived photon spectrum can be equally fitted by an optically thin bremsstrahlung distribution of kT approximately = 52 keV or a power law of the form, dN(E)/dE = 3.7 x 10(exp -6) (E/400)(exp -4.5) photons/sq cm/keV. We compare its spectral characteristics ad energy output to various types of fast X-ray transients. No measurable flux could be detected from CG 135+1, the COS B source which was in the FOV and therefore, we present 2 sigma upper flux limits on its spectral emission over the energy range 160 keV to 9.3 MeV.

  12. [Measuring the sources of discomfort in patients in intensive care].

    PubMed

    Haubertin, Carole; Crozes, Fanny; Le Page, Melody; Seailles, Severine

    2016-05-01

    A study carried out in 2014 in a hospital focused on the sources of discomfort of patients in intensive care. Resulting in raised awareness across all disciplines, it has enabled the actions to be undertaken to improve professional practices to be prioritised, in a culture of compassionate care. PMID:27157560

  13. Identification of High Energy Gamma-Ray Sources And Source Populations in the Era of Deep All-Sky Coverage

    SciTech Connect

    Reimer, Olaf; Torres, Diego F.; /ICREA, Barcelona /Barcelona, IEEC

    2007-04-17

    A large fraction of the anticipated source detections by the Gamma-ray Large Area Space Telescope (GLAST-LAT) will initially be unidentified. We argue that traditional approaches to identify individuals and/or populations of gamma ray sources will encounter procedural limitations. Those limitations are discussed on the background of source identifications from EGRET observations. Generally, our ability to classify (faint) source populations in the anticipated GLAST dataset with the required degree of statistical confidence will be hampered by sheer source wealth. A new paradigm for achieving the classification of gamma ray source populations is discussed.

  14. High intensity line source for x-ray spectrometer calibration

    SciTech Connect

    Thoe, R.S.

    1986-06-01

    A high intensity electron-impact x-ray source using a one-dimensional Pierce lens has been built for the purpose of calibrating a bent crystal x-ray spectrometer. This source focuses up to 100 mA of 20-keV electrons to a line on a liquid-cooled anode. The line (which can serve as a virtual slit for the spectrometer) measures approximately 800 ..mu.. x 2 cm. The source is portable and therefore adaptable to numerous types of spectrometer applications. One particular application, the calibration of a high resolution (r = 10/sup 4/) time-resolved cyrstal spectrometer, will be discussed in detail.

  15. Biological Evolution on the Earth Influenced by Astronomical Objects: Especially Gamma-ray Sources

    NASA Astrophysics Data System (ADS)

    Ponert, J.; Príhoda, P.

    2009-12-01

    Taking in to account 20,000 explosions of intragalactic supernovae per million years, the sources estimated at 1056 - 1057 MeV producing the high intensity of gamma- and xray-radiation even after its reduction through the Earth atmosphere, may have a significant mutagenic action. During the time period of the last 4 billion years not less than one hundred explosions up to the mean distance 126 pc from the Earth. All such explosions were able to evoke a genetic revolution among most taxonomic groups of terrestrial organisms. For mountain organisms, the more frequent supernova explosions in distance up to 400-900 pc are of importance, maritime organisms could be influenced mainly by secondary radiation products, rather than directly by the gamma and X-rays from the supernovae. The mechanisms of macroevolution depending on supernovae is elucidated. Smaller genetical revolutions in the macroevolutional process (formation of genera) took place on the average once every 10 millions or more years, fundamental genetic revolutions once in 100 millions or more years. Also other newly discovered astronomical gamma-ray sources have to be taken in account.

  16. Stereotactic radiosurgery of the brain using the first United States 201 cobalt-60 source gamma knife

    SciTech Connect

    Lunsford, L.D.; Flickinger, J.; Lindner, G.; Maitz, A.

    1989-02-01

    The first United States 201 cobalt-60 source gamma knife for stereotactic radiosurgery of brain tumors and arteriovenous malformations became operational at the University of Pittsburgh on August 14, 1987. Four and one-half years of intensive planning, regulatory agency review, and analysis of published results preceded the first radiosurgical procedure. Installation of this 18,000-kg device and loading of the 201 cobalt-60 sources posed major challenges in engineering, architecture, and radiophysics. In the first 4 months of operation, we treated 52 patients (29 with arteriovenous malformations, 19 with extra-axial neoplasms of the skull base, and 4 with intra-axial malignant tumors). Most patients either had lesions considered inoperable or had residual lesions after attempted surgical resection. Neither surgical mortality nor significant morbidity was associated with gamma knife radiosurgery. As compared with treatment by conventional intracranial surgery (craniotomy), the average length of stay for radiosurgery was reduced by 4 to 14 days, and hospital charges were reduced by as much as 65%. Based on both the previously published results of treatment of more than 2,000 patients worldwide and on our initial clinical experience, we believe that gamma knife stereotactic radiosurgery is a therapeutically effective and economically sound alternative to more conventional neurosurgical procedures, in selected cases.

  17. Status of the Trasco Intense Proton Source and emittance measurements

    NASA Astrophysics Data System (ADS)

    Celona, L.; Ciavola, G.; Gammino, S.; Chines, F.; Presti, M.; Andò, L.; Guo, X. H.; Gobin, R.; Ferdinand, R.

    2004-05-01

    The Trasco Intense Proton Source (TRIPS) was installed at INFN-LNS in May 2000 and has been fully operational since the Fall of 2000; now the source fulfills all the requirements of the TRASCO (Trasmutazione Scorie) project. The proton beam intensity easily exceeds 40 mA at the operating voltage of 80 kV. A set of emittance measurements was carried out for different source conditions and confirmed the simulations performed with the AXCEL code: in all the cases the rms normalized emittance is well lower than the value required for the injection into the RFQ (0.2 π mm mrad); the results will be shown and discussed. Finally a beam reliability of 99.8% has been found during a long run test lasting over 142 h.

  18. Acoustic intensity in the interaction region of a parametric source

    NASA Astrophysics Data System (ADS)

    Lauchle, G. C.; Gabrielson, T. B.; van Tol, D. J.; Kottke, N. F.; McConnell, J. A.

    2003-10-01

    The goal of this project was to measure acoustic intensity in the strong interaction region of a parametric source in order to obtain a clear definition of the source-generation region and to separate the local generation (the reactive field) from propagation (the real or active field). The acoustic intensity vector was mapped in the interaction region of a parametric projector at Lake Seneca. The source was driven with primary signals at 22 kHz and 27 kHz. Receiving sensors were located 8.5 meters from the projector. At that range, the secondary at 5 kHz was between 40 and 45 dB below either primary. For the primary levels used, the plane-wave shock inception distance would have been at least 14 meters. Furthermore, the Rayleigh distance for the projector was about 4 meters so the measurements at 8.5 meters were in the strong interaction region but not in saturation. Absorption was negligible over these ranges. The intensity measurements were made at fixed range but varying azimuth angle and varying depth thus developing a two-dimensional cross-section of the secondary beam. Measurements of both the active and reactive intensity vectors will be presented along with a discussion of measurement error. [Work supported by ONR Code 321SS.

  19. A polarized look at nucleons: Laser electron gamma source

    SciTech Connect

    The LEGS Collaboration

    1991-12-31

    As the title suggests we are going to look at reactions induced on nucleons by polarized photons. The results I am going to show today are from the Laser Electron Gamma Source, or ``LEGS`` facility, at Brookhaven National Laboratory. At LEGS, gamma ray beams are produced by backscattering laser light from relativistic electrons. I will only summarize the main characteristics of this facility, and leave an in depth description to Dr. Schaerf who will discuss LEGS and other similar backscattering facilities on Wednesday. Reactions with polarized photons inevitably reflect interference terms that for the most part remain hidden in spin-averaged unpolarized measurements. This provides a tool for probing interactions that depend upon spin. In particular, we are going to look today at two cases where the polarization is used to probe the tensor interaction. First, we will examine the tensor force between a proton-neutron pair in deuterium. Secondly, we will examine the tensor force between quarks in a proton that produces a small E2 component that is mixed with the predominantly M1 excitation of the delta resonance.The magnitude of this E2 components provides a sensitive probe of the structure of the Nucleon.

  20. A polarized look at nucleons: Laser electron gamma source

    SciTech Connect

    Not Available

    1991-01-01

    As the title suggests we are going to look at reactions induced on nucleons by polarized photons. The results I am going to show today are from the Laser Electron Gamma Source, or LEGS'' facility, at Brookhaven National Laboratory. At LEGS, gamma ray beams are produced by backscattering laser light from relativistic electrons. I will only summarize the main characteristics of this facility, and leave an in depth description to Dr. Schaerf who will discuss LEGS and other similar backscattering facilities on Wednesday. Reactions with polarized photons inevitably reflect interference terms that for the most part remain hidden in spin-averaged unpolarized measurements. This provides a tool for probing interactions that depend upon spin. In particular, we are going to look today at two cases where the polarization is used to probe the tensor interaction. First, we will examine the tensor force between a proton-neutron pair in deuterium. Secondly, we will examine the tensor force between quarks in a proton that produces a small E2 component that is mixed with the predominantly M1 excitation of the delta resonance.The magnitude of this E2 components provides a sensitive probe of the structure of the Nucleon.

  1. Space-Borne Observations of Intense Gamma-Ray Flashes Above Thunderstorms

    NASA Technical Reports Server (NTRS)

    Fishman, Jerry

    2005-01-01

    Intense millisecond flashes of MeV photons were discovered with the space-borne detectors of the Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma-Ray Observatory (CGRO). These flashes originate at altitudes above at least 30 km, in order to be observable by the orbiting detectors. Over the entire CGRO mission, from 1991 until 2000, about 70 of these events were observed. Nearly all TGFs had short (millisecond) durations and sub-ms rise-times and fall-times, however a small fraction of them had longer timescales associated with them. Most were single pulses, but about a dozen had double pulses and a few had more than two pulses. The TGFs are observed in a photon-by-photon recording mode, with each photon from eight independent detectors being tagged to the nearest two microseconds in four energy channels. The TGFs show very hard spectra, in most cases there are more photons recorded above 300 keV than below. Several of the TGFs were also recorded by the thicker (but smaller area) spectroscopy detectors that provided improved spectral resolution than the large area detectors. The temporal and spectral characteristics of the events and the capabilities of the detectors will be described in more detail than the in the original paper. The association of TGFs with thunderstorms is primarily statistical; the TGFs show a strong correlation with the global distribution of lightning, as observed with recent satellites. There has also been an association based upon coincidences with spheric events, however, this association is debatable due to the high spherics rate and the non-directionality of the detectors. This talk gives an update of the BATSE observations of TGFs were published by the BATSE instrument team over ten years ago.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  3. TRIPS: The high intensity proton source for the TRASCO project

    NASA Astrophysics Data System (ADS)

    Celona, L.; Ciavola, G.; Gammino, S.; Gobin, R.; Ferdinand, R.

    2000-02-01

    The TRASCO project (trasmutazione scorie) is a R&D program whose goal is the design of an accelerator driving system for nuclear waste transmutation. The high current continuous wave proton linear accelerator will drive a subcritical system to transmutate nuclear wastes, while producing energy. The proton source TRIPS is a high intensity microwave source, which should be highly reliable and that should provide a minimum proton current of 50 mA with a r-r' root mean square normalized emittance lower than 0.2 π mm mrad. A program of cooperation has been entered into with CEA-Saclay, where the IPHI project is in progress and the proton source SILHI has been designed and built using goals close to those of TRIPS. The construction of TRIPS is underway and the first beam is scheduled for the first half of 2000. The main features of this source and the results of the optics calculations are presented.

  4. A capillary discharge plasma source of intense VUV radiation

    SciTech Connect

    Sobel'man, Igor I; Shevelko, A P; Yakushev, O F; Knight, L V; Turley, R S

    2003-01-31

    The results of investigation of a capillary discharge plasma, used as a source of intense VUV radiation and soft X-rays, are presented. The plasma was generated during the discharge of low-inductance condensers in a gas-filled ceramic capillary. Intense line radiation was observed in a broad spectral range (30-400 A) in various gases (CO{sub 2}, Ne, Ar, Kr, Xe). The absolute radiation yield for the xenon discharge was {approx}5 mJ (2{pi} sr){sup -1} pulse{sup -1} within a spectral band of width 9 A at 135 A. Such a radiation source can be used for various practical applications, such as EUV projection lithography, microscopy of biological objects in a 'water window', reflectometry, etc. (special issue devoted to the 80th anniversary of academician n g basov's birth)

  5. Generation of ultra-intense gamma-ray train by QED harmonics

    NASA Astrophysics Data System (ADS)

    Liu, Chen; Shen, Baifei; Zhang, Xiaomei; Ji, Liangliang; Wang, Wenpeng; Xu, Jiancai; Zhao, Xueyan; Yi, Longqing; Shi, Yin; Zhang, Lingang; Xu, Tongjun; Pei, Zhikun; Xu, Zhizhan

    2016-08-01

    In nonlinear media, photons may combine into a photon of energy and momentum of all those photons. This process, called harmonic generation, happens in nonlinear crystal, gas, and relativistic plasma. When the laser intensity reaches 1022 W/cm2, QED effects appear and play a significant role in the harmonic generation. In contrast to the gas and relativistic high-order harmonic generation processes, harmonics influenced by QED effects are usually not coherent because of the characteristic of random radiation, while the property of high intensity and ultra-short duration is conserved. In this work, the generation of high-order harmonics with QED effects is investigated by one- and two-dimensional particle-in-cell simulations. Studies have shown that interacting with a laser pulse with the intensity of I =5.35 ×1023W /cm 2 , such harmonics can produce ultra-short gamma-ray train with periodic structures. The period of gamma-ray train is half of the laser period, and the peak intensity is 1.4 ×1022W /cm 2 from one-dimensional simulation when ions are considered immobile. This new harmonic production with QED effects are crucial to light-matter interaction in strong field and can be verified in experiments by 10 PW laser facilities in the near future.

  6. Transport of intensity phase imaging using Bessel sources

    NASA Astrophysics Data System (ADS)

    Petruccelli, Jonathan C.; Chakraborty, Tonmoy

    2016-05-01

    Propagation-based phase contrast using the transport of intensity equation (TIE) allows rapid, deterministic phase retrieval from defocused images. For weakly attenuating objects, phase can be retrieved from a single image. However, the TIE suffers from significant low frequency artifacts due to enhancement of noise during phase retrieval. We demonstrate that by patterning the illumination source as approximately a modified Bessel function of the 2nd kind of zero order, quantitative phase can be imaged directly at the detector within a spatial frequency band. Outside of that band, Bessel sources still improve low frequency performance in phase retrieval.

  7. Dosimetric comparison of tools for intensity modulated radiation therapy with gamma analysis: a phantom study

    NASA Astrophysics Data System (ADS)

    Akbas, Ugur; Okutan, Murat; Demir, Bayram; Koksal, Canan

    2015-07-01

    Dosimetry of the Intensity Modulated Radiation Therapy (IMRT) is very important because of the complex dose distributions. Diode arrays are the most common and practical measurement tools for clinical usage for IMRT. Phantom selection is critical for QA process. IMRT treatment plans are recalculated for the phantom irradiation in QA. Phantoms are made in different geometrical shapes to measure the doses of different types of irradiation techniques. Comparison of measured and calculated dose distributions for IMRT can be made by using gamma analysis. In this study, 10 head-and-neck IMRT QA plans were created with Varian Eclipse 8.9 treatment planning system. Water equivalent RW3-slab phantoms, Octavius-2 phantom and PTW Seven29 2D-array were used for QA measurements. Gantry, collimator and couch positions set to 00 and QA plans were delivered to RW3 and Octavius phantoms. Then the positions set to original angles and QA plans irradiated again. Measured and calculated fluence maps were evaluated with gamma analysis for different DD and DTA criteria. The effect of different set-up conditions for RW3 and Octavius phantoms in QA plan delivery evaluated by gamma analysis. Results of gamma analysis show that using RW3-slab phantoms with setting parameters to 00 is more appropriate for IMRT QA.

  8. Optimal Design of a Tunable Thomson-Scattering Based Gamma-Ray Source

    SciTech Connect

    Gibson, D J; Anderson, S G; Betts, S M; Hartemann, F V; Jovanovic, I; McNabb, D P; Messerly, M J; Pruet, J A; Shverdin, M Y; Siders, C W; Tremaine, A M; Barty, C J

    2007-06-07

    Thomson-Scattering based systems offer a path to high-brightness high-energy (> 1 MeV) x-ray and {gamma}-ray sources due to their favorable scaling with electron energy. LLNL is currently engaged in an effort to optimize such a device, dubbed the ''Thomson-Radiated Extreme X-Ray'' (T-REX) source, targeting up to 680 keV photon energy. Such a system requires precise design of the interaction between a high-intensity laser pulse and a high-brightness electron beam. Presented here are the optimal design parameters for such an interaction, including factors such as the collision angle, focal spot size, optimal bunch charge, and laser energy. These parameters were chosen based on extensive modeling using PARMELA and in-house, well-benchmarked scattering simulation codes.

  9. GAMMA-RAY COMPTON LIGHT SOURCE DEVELOPMENT AT LLNL

    SciTech Connect

    Hartemann, F V; Anderson, S G; Gibson, D J; Hagmann, C A; Johnson, M S; Jovanovic, I; Messerly, M J; Pruet, J A; Shverdin, M Y; Tremaine, A M; McNabb, D P; Siders, C W; Barty, C J

    2007-08-15

    A new class of tunable, monochromatic {gamma}-ray sources capable of operating at high peak and average brightness is currently being developed at LLNL for nuclear photoscience and applications. These novel systems are based on Compton scattering of laser photons by a high brightness relativistic electron beam produced by an rf photoinjector. A prototype, capable of producing > 10{sup 8} 0.7 MeV photons in a single shot, with a fractional bandwidth of 1%, and a repetition rate of 10 Hz, is currently under construction at LLNL; this system will be used to perform nuclear resonance fluorescence experiments. A new symmetrized S-band rf gun, using a Mg photocathode, will produce up to 1 nC of charge in an 8 ps bunch, with a normalized emittance modeled at 0.8 mm.mrad; electrons are subsequently accelerated up to 120 MeV to interact with a 500 mJ, 10 ps, 355 nm laser pulse and generate {gamma}-rays. The laser front end is a fiber-based system, using corrugated-fiber Bragg gratings for stretching, and drives both the frequency-quadrupled photocathode illumination laser and the Nd:YAG interaction laser. Two new technologies are used in the laser: a hyper-Michelson temporal pulse stacker capable of producing 8 ps square UV pulses, and a hyper-dispersion compressor for the interaction laser. Other key technologies, basic scaling laws, and recent experimental results will also be presented, along with an overview of future research and development directions.

  10. Degree of polarization and source counts of faint radio sources from Stacking Polarized intensity

    SciTech Connect

    Stil, J. M.; George, S. J.; Keller, B. W.; Taylor, A. R.

    2014-06-01

    We present stacking polarized intensity as a means to study the polarization of sources that are too faint to be detected individually in surveys of polarized radio sources. Stacking offers not only high sensitivity to the median signal of a class of radio sources, but also avoids a detection threshold in polarized intensity, and therefore an arbitrary exclusion of sources with a low percentage of polarization. Correction for polarization bias is done through a Monte Carlo analysis and tested on a simulated survey. We show that the nonlinear relation between the real polarized signal and the detected signal requires knowledge of the shape of the distribution of fractional polarization, which we constrain using the ratio of the upper quartile to the lower quartile of the distribution of stacked polarized intensities. Stacking polarized intensity for NRAO VLA Sky Survey (NVSS) sources down to the detection limit in Stokes I, we find a gradual increase in median fractional polarization that is consistent with a trend that was noticed before for bright NVSS sources, but is much more gradual than found by previous deep surveys of radio polarization. Consequently, the polarized radio source counts derived from our stacking experiment predict fewer polarized radio sources for future surveys with the Square Kilometre Array and its pathfinders.

  11. Detection and Location of Gamma-Ray Sources with a Modulating Coded Mask

    SciTech Connect

    Anderson, Dale N.; Stromswold, David C.; Wunschel, Sharon C.; Peurrung, Anthony J.; Hansen, Randy R.

    2006-01-31

    This paper presents methods of detecting and locating a concelaed nuclear gamma-ray source with a coded aperture mask. Energetic gamma rays readily penetrate moderate amounts of shielding material and can be detected at distances of many meters. The detection of high energy gamma-ray sources is vitally important to national security for several reasons, including nuclear materials smuggling interdiction, monitoring weapon components under treaties, and locating nuclear weapons and materials in the possession terrorist organizations.

  12. LASER TECHNOLOGY FOR PRECISION MONOENERGETIC GAMMA-RAY SOURCE R&D AT LLNL

    SciTech Connect

    Shverdin, M Y; Bayramian, A; Albert, F; Anderson, S G; Betts, S M; Chu, T S; Cross, R R; Gibson, D J; Marsh, R; Messerly, M; Phan, H; Prantil, M; Wu, S; Ebbers, C; Scarpetti, R D; Hartemann, F V; Siders, C W; McNabb, D P; Bonanno, R E; Barty, C P

    2010-04-20

    Generation of mono-energetic, high brightness gamma-rays requires state of the art lasers to both produce a low emittance electron beam in the linac and high intensity, narrow linewidth laser photons for scattering with the relativistic electrons. Here, we overview the laser systems for the 3rd generation Monoenergetic Gamma-ray Source (MEGa-ray) currently under construction at Lawrence Livermore National Lab (LLNL). We also describe a method for increasing the efficiency of laser Compton scattering through laser pulse recirculation. The fiber-based photoinjector laser will produce 50 {micro}J temporally and spatially shaped UV pulses at 120 Hz to generate a low emittance electron beam in the X-band RF photoinjector. The interaction laser generates high intensity photons that focus into the interaction region and scatter off the accelerated electrons. This system utilizes chirped pulse amplification and commercial diode pumped solid state Nd:YAG amplifiers to produce 0.5 J, 10 ps, 120 Hz pulses at 1064 nm and up to 0.2 J after frequency doubling. A single passively mode-locked Ytterbium fiber oscillator seeds both laser systems and provides a timing synch with the linac.

  13. H- Ion Sources for High Intensity Proton Drivers

    SciTech Connect

    Dudnikov, Vadim; Johnson, Rolland P.; Stockli, Martin P; Welton, Robert F; Dudnikova, Galina

    2010-01-01

    Spallation neutron source user facilities require reliable, intense beams of protons. The technique of H- charge exchange injection into a storage ring or synchrotron can provide the needed beam currents, but may be limited by the ion sources that have currents and reliability that do not meet future requirements and emittances that are too large for efficient acceleration. In this project we are developing an H- source which will synthesize the most important developments in the field of negative ion sources to provide high current, small emittance, good lifetime, high reliability, and power efficiency. We describe planned modifications to the present external antenna source at SNS that involve: 1) replacing the present 2 MHz plasma-forming solenoid antenna with a 60 MHz saddle-type antenna and 2) replacing the permanent multicusp magnet with a weaker electromagnet, in order to increase the plasma density near the outlet aperture. The SNS test stand will then be used to verify simulations of this approach that indicate significant improvements in H- output current and efficiency, where lower RF power will allow higher duty factor, longer source lifetime, and/or better reliability.

  14. High-entropy fireballs and jets in gamma-ray burst sources

    NASA Technical Reports Server (NTRS)

    Meszaros, P.; Rees, M. J.

    1992-01-01

    Two mechanisms whereby compact coalescing binaries can produce relatively 'clean' fireballs via neutrino-antineutrino annihilation are proposed. Preejected mass due to tidal heating will collimate the fireball into jets. The resulting anisotropic gamma-ray emission can be efficient and intense enough to provide an acceptable model for gamma-ray bursts, if these originate at cosmological distances.

  15. Hints of the Existence of Axion-Like-Particles From the Gamma-Ray Spectra of Cosmological Sources

    SciTech Connect

    Sanchez-Conde, M.A.; Paneque, D.; Bloom, E.; Prada, F.; Dominguez, A.; /IAA, Granada /Seville U.

    2009-06-23

    Axion Like Particles (ALPs) are predicted to couple with photons in the presence of magnetic fields. This effect may lead to a significant change in the observed spectra of gamma-ray sources such as AGNs. Here we carry out a detailed study that for the first time simultaneously considers in the same framework both the photon/axion mixing that takes place in the gamma-ray source and that one expected to occur in the intergalactic magnetic fields. An efficient photon/axion mixing in the source always means an attenuation in the photon flux, whereas the mixing in the intergalactic medium may result in a decrement and/or enhancement of the photon flux, depending on the distance of the source and the energy considered. Interestingly, we find that decreasing the value of the intergalactic magnetic field strength, which decreases the probability for photon/axion mixing, could result in an increase of the expected photon flux at Earth if the source is far enough. We also find a 30% attenuation in the intensity spectrum of distant sources, which occurs at an energy that only depends on the properties of the ALPs and the intensity of the intergalactic magnetic field, and thus independent of the AGN source being observed. Moreover, we show that this mechanism can easily explain recent puzzles in the spectra of distant gamma-ray sources, like the possible detection of TeV photons from 3C 66A (a source located at z=0.444) by MAGIC and VERITAS, which should not happen according to conventional models of photon propagation over cosmological distances. Another puzzle is the recent published lower limit to the EBL intensity at 3.6 {micro}m (which is almost twice larger as the previous one), which implies very hard spectra for some detected TeV gamma-ray sources located at z=0.1-0.2. The consequences that come from this work are testable with the current generation of gamma-ray instruments, namely Fermi (formerly known as GLAST) and imaging atmospheric Cherenkov telescopes like

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

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  17. 1979 January 13 - An intense gamma-ray burst with a possible associated optical transient

    NASA Technical Reports Server (NTRS)

    Barat, C.; Hurley, K.; Niel, M.; Vedrenne, G.; Cline, T.; Desai, U.; Schaefer, B.; Teegarden, B.; Evans, W. D.; Fenimore, E. E.

    1984-01-01

    The time history, energy spectra, and precise localization of the intense January 13, 1979 gamma-ray burst, observed by five spacecraft in the interplanetary network, are presented. The time history displays a pulse-afterpulse structure suggestive of periodicity. Fine time resolution spectral analysis shows that a wide variety of models can be used to fit individual spectra, while spectra integrated over longer periods are well fitted by a thermal synchrotron law, making it difficult to identify any specific emission mechanism. The precise localization may be consistent with an archival optical transient having no quiescent counterpart down to 22d mag on recent plates.

  18. Using Intensive Variables to Constrain Magma Source Regions

    NASA Astrophysics Data System (ADS)

    Edwards, B. R.; Russell, J. K.

    2006-05-01

    In the modern world of petrology, magma source region characterization is commonly the realm of trace element and isotopic geochemistry. However, major element analyses of rocks representing magmatic compositions can also be used to constrain source region charactertistics, which enhance the results of isotopic and trace element studies. We show examples from the northern Cordilleran volcanic province (NCVP), in the Canadian Cordillera, where estimations of thermodynamic intensive variables are used to resolve different source regions for mafic alkaline magmas. We have taken a non-traditional approach to using the compositions of three groups of mafic, alkaline rocks to characterize the source regions of magmas erupted in the NCVP. Based on measured Fe2O3 and FeO in rocks from different locations, the Atlin volcanic district (AVD), the Fort Selkirk volcanic complex (FSVC), the West Tuya volcanic field, (WTVF), we have estimated oxygen fugacities (fO2) for the source regions of magmas based on the model of Kress and Carmichael (1991) and the computational package MELTS/pMelts (Ghiorso and Sack, 1995; Ghiorso et al., 2002). We also have used Melts/pMelts to estimate liquidus conditions for the compositions represented by the samples as well as activities of major element components. The results of our calculations are useful for distinguishing between three presumably different magma series: alkaline basalts, basanites, and nephelinites (Francis and Ludden, 1990; 1995). Calculated intensive variables (fO2, activities SiO2, KAlSiO4, Na2SiO3) show clear separation of the samples into two groups: i) nephelinites and ii) basanites/alkaline basalts. The separation is especially evident on plots of log fO2 versus activity SiO2. The source region for nephelinitic magmas in the AVD is up to 2 log units more oxidized than that for the basanites/basalts as well as having a distinctly lower range of activities of SiO2. Accepting that our assumptions about the magmas

  19. Arcsec source location measurements in gamma-ray astronomy from a lunar observatory

    NASA Technical Reports Server (NTRS)

    Koch, David G.; Hughes, E. B.

    1990-01-01

    The physical processes typically used in the detection of high energy gamma-rays do not permit good angular resolution, which makes difficult the unambiguous association of discrete gamma-ray sources with objects emitting at other wavelengths. This problem can be overcome by placing gamma-ray detectors on the moon and using the horizon as an occulting edge to achieve arcsec resolution. For the purpose of discussion, this concept is examined for gamma rays above about 20 MeV for which pair production dominates the detection process and locally-generated nuclear gamma rays do not contribute to the background.

  20. Development of a transport system for the copper source of the Texas Intense Positron Source facility

    NASA Astrophysics Data System (ADS)

    Doron, O.; Biegalski, S. R.; O'Kelly, S.; Hurst, B. J.

    2006-01-01

    The transport system design and construction for The Texas Intense Positron Source (TIPS) facility has been completed. This facility is located on beam port 1 of The University of Texas at Austin TRIGA Mark II 1.1 MW research reactor. The TIPS will provide a high intensity, variable energy positron beam for use in material studies. The natural copper source is transported into beam port 1 of the reactor where it is irradiated at close proximity to the reactor core. The transport system is an L-shaped aluminum channel that utilizes pulleys to drive a source cart. The copper source is transported on the cart into and out of the beam port for irradiation. After removal from the beam port, the activated copper positron source will be placed into a vacuum chamber where the positrons are moderated with annealed tungsten foil and electrostatically extracted.

  1. Average Emissivity Curve of BATSE Gamma-Ray Bursts with Different Intensities

    NASA Technical Reports Server (NTRS)

    Mitrofanov, Igor G.; Anfimov, Dimitrij S.; Litvak, Maxim L.; Briggs, Michael S.; Paciesas, W. S.; Pendleton, Geoffrey N.; Preece, Robert D.

    1998-01-01

    Six intensity groups with $/sim 150$ BATSE gamma-ray bursts each are compared using average emissivity curves. Time-stretch factors for each of the dimmer groups are estimated with respect to the brightest group. Which serves as the reference taking into account the systematics of counts-produced noise effects and choice statistics. The effect of stretching/intensity anti-correlation is found at the average back slopes of bursts with good statistical significance. A stretch factor $/sim 2$ is found between the 150 dimmest bursts with peak flux $less than 0.45$ ph cm$(exp -2)$ s$(exp -1)$, and the 147 brightest bursts with peak flux $greater than 4.1$ ph cm$(exp -2}$ s$(exp -1)$. On the other hand, only a marginally significant stretching effect $V(sub ec) 1.4$ is seen at the average rise fronts.

  2. Weak {gamma}-transition intensities in the electron capture decay of {sup 144}Pm

    SciTech Connect

    Robinson, S.J.; Altgilbers, A.S.; Hindi, M.M.; Norman, E.B.; Larimer, R.

    1996-09-01

    We have determined the absolute intensity of weak {gamma} transitions in the level scheme of {sup 144}Nd, observed following the electron capture decay of {sup 144}Pm. The absolute intensity of the 1397-keV {ital E}3 branch from the 2093-keV (5{sub 1}{sup {minus}}) level was determined to be (4.9 {plus_minus} 0.7) {times} 10{sup {minus}4}{percent}. This leads to a revised absolute transition rate of {ital B}({ital E}3;5{sub 1}{sup {minus}}{r_arrow}2{sup +}{sub 1})=26{sub {minus}12}{sup +15} Weisskopf units, which is still consistent with an interpretation of the 5{sub 1}{sup {minus}} level based on quadrupole-octupole coupling. {copyright} {ital 1996 The American Physical Society.}

  3. Primary gamma-rays with E gamma or = to 10(15) eV: Evidence for ultrahigh energy particle acceleration in galactic sources

    NASA Technical Reports Server (NTRS)

    Aharonian, F. A.; Mamidjanian, E. A.; Nikolsky, S. I.; Tukish, E. I.

    1985-01-01

    The recently observed primary ultra high energy gamma-rays (UHEGR) testify to the cosmic ray (CR) acceleration in the Galaxy. The available data may be interpreted as gamma-ray production due to photomeson production in CR sources.

  4. The risk of retina damage from high intensity light sources.

    PubMed

    Pollak, V A; Romanchuk, K G

    1980-05-01

    The risk of thermal damage to the retina of the eye by exposure to excessive light intensities from continuous and pulsed man-made sources is discussed. The probability of injury increases, the larger the radiant power absorbed by the retina and the smaller the size of the retinal image of the source. A mehtod of estimating the temperature increase of the immediately affected area of the retina is presented. The time constants involved are also briefly considered. Using numerical values from literature for the relevant parameters of the eye, threshold values for a variety of conditions can be established. Below these values little risk of retina damage should exist. The degree of hazard when these values are exceeded depends upon the circumstances. A case study of a welding accident showed good agreement between the conclusions of the theoretical analysis and clinical findings.

  5. Study of the intensity noise and intensity modulation in a of hybrid soliton pulsed source

    SciTech Connect

    Dogru, Nuran; Oziazisi, M Sadetin

    2005-10-31

    The relative intensity noise (RIN) and small-signal intensity modulation (IM) of a hybrid soliton pulsed source (HSPS) with a linearly chirped Gaussian apodised fibre Bragg grating (FBG) are considered in the electric-field approximation. The HSPS is described by solving the dynamic coupled-mode equations. It is shown that consideration of the carrier density noise in the HSPS in addition to the spontaneous noise is necessary to analyse accurately noise in the mode-locked HSPS. It is also shown that the resonance peak spectral splitting (RPSS) of the IM near the frequency inverse to the round-trip time of light in the external cavity can be eliminated by selecting an appropriate linear chirp rate in the Gaussian apodised FBG. (laser applications and other topics in quantum electronics)

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  7. Application of a Multidimensional Wavelet Denoising Algorithm for the Detection and Characterization of Astrophysical Sources of Gamma Rays

    SciTech Connect

    Digel, S.W.; Zhang, B.; Chiang, J.; Fadili, J.M.; Starck, J.-L.; /Saclay /Stanford U., Statistics Dept.

    2005-12-02

    Zhang, Fadili, & Starck have recently developed a denoising procedure for Poisson data that offers advantages over other methods of intensity estimation in multiple dimensions. Their procedure, which is nonparametric, is based on thresholding wavelet coefficients. The restoration algorithm applied after thresholding provides good conservation of source flux. We present an investigation of the procedure of Zhang et al. for the detection and characterization of astrophysical sources of high-energy gamma rays, using realistic simulated observations with the Large Area Telescope (LAT). The LAT is to be launched in late 2007 on the Gamma-ray Large Area Space Telescope mission. Source detection in the LAT data is complicated by the low fluxes of point sources relative to the diffuse celestial background, the limited angular resolution, and the tremendous variation of that resolution with energy (from tens of degrees at {approx}30 MeV to 0.1{sup o} at 10 GeV). The algorithm is very fast relative to traditional likelihood model fitting, and permits immediate estimation of spectral properties. Astrophysical sources of gamma rays, especially active galaxies, are typically quite variable, and our current work may lead to a reliable method to quickly characterize the flaring properties of newly-detected sources.

  8. Diffuse gamma radiation. [intensity, energy spectrum and spatial distribution from SAS 2 observations

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

    1978-01-01

    Results are reported for an investigation of the intensity, energy spectrum, and spatial distribution of the diffuse gamma radiation detected by SAS 2 away from the galactic plane in the energy range above 35 MeV. The gamma-ray data are compared with relevant data obtained at other wavelengths, including 21-cm emission, radio continuum radiation, and the limited UV and radio information on local molecular hydrogen. It is found that there are two quite distinct components to the diffuse radiation, one of which shows a good correlation with the galactic matter distribution and continuum radiation, while the other has a much steeper energy spectrum and appears to be isotropic at least on a coarse scale. The galactic component is interpreted in terms of its implications for both local and more distant regions of the Galaxy. The apparently isotropic radiation is discussed partly with regard to the constraints placed on possible models by the steep energy spectrum, the observed intensity, and an upper limit on the anisotropy.

  9. Neutron production enhancements for the Intense Pulsed Neutron Source.

    SciTech Connect

    Iverson, E. B.

    1999-01-04

    The Intense Pulsed Neutron Source (IPNS) was the first high energy spallation neutron source in the US dedicated to materials research. It has operated for sixteen years, and in that time has had a very prolific record concerning the development of new target and moderator systems for pulsed spallation sources. IPNS supports a very productive user program on its thirteen instruments, which are oversubscribed by more than two times, meanwhile having an excellent overall reliability of 95%. Although the proton beam power is relatively low at 7 kW, the target and moderator systems are very efficient. The typical beam power which gives an equivalent flux for long-wavelength neutrons is about 60 kW, due to the use of a uranium target and liquid and solid methane moderators, precluded at some sources due to a higher accelerator power. The development of new target and moderator systems is by no means stagnant at IPNS. They are presently considering numerous enhancements to the target and moderators that offer prospects for increasing the useful neutron production by substantial factors. Many of these enhancements could be combined, although their combined benefit has not yet been well established. Meanwhile, IPNS is embarking on a coherent program of study concerning these improvements and their possible combination and implementation. Moreover, any improvements accomplished at IPNS would immediately increase the performance of IPNS instruments.

  10. Helios 2-Vela-Ariel 5 gamma-ray burst source position

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Trainor, J.; Pizzichini, G.; Spizzichino, A.; Klebesadel, R.; Ricketts, M.; Helmken, H.

    1979-01-01

    The gamma-ray burst of January 28, 1976, one of 18 events thus far detected in interplanetary space with Helios 2, was also observed with the Vela 5A and 6A and the Ariel 5 satellites. A small source field is obtained from the intersection of the region derived from the observed time delays between Helios 2 and Vela 5A and 6A, with the source region independently found with the Ariel 5 X-ray detector. This area contains neither any steady X-ray source as scanned by HEAO 1 nor any previously cataloged X-ray, radio, or infrared sources, X-ray transients, quasars, Seyferts, globular clusters, flare stars, pulsars, white dwarfs, or high enery gamma-ray sources. The region is, however, within the source field of a gamma-ray transient observed in 1974 by Jacobson et al. (1978) which exhibited nuclear gamma-ray line structure.

  11. Helios-2 Vela-Ariel-5 gamma-ray burst source position

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Trainor, J. H.; Desai, U. D.; Klebesadel, R. W.; Ricketts, M.; Heluken, H.

    1979-01-01

    The gamma-ray burst of 28 January 1976, one of 18 events thus far detected in interplanetary space with Helios-2, was also observed with the Vela-5A, -6A and the Ariel-5 satellites. A small source field is obtained from the intersection of the region derived from the observed time delays between Helios-2 and Vela-5A and -6A with the source region independently found with the Ariel-5 X-ray detector. This area contains neither any steady X-ray source as scanned by HEAO-A nor any previously catalogued X-ray, radio or infrared sources, X-ray transients, quasars, seyferts, globular clusters, flare stars, pulsars, white dwarfs or high energy gamma-ray sources. The region is however, within the source field of a gamma-ray transient observed in 1974, which exhibited nuclear gamma-ray line structure.

  12. Precise source location of the anomalous 1979 March 5 gamma ray transient

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Teegarden, B. J.; Evans, W. D.; Klebesadel, R. W.; Laros, J. G.; Barat, C.; Hurley, K.; Niel, M.; Vedrenne, G.

    1981-01-01

    Refinements in the source direction analysis of the observations of the unusual gamma ray transient are presented. The final results from the interplanetary gamma ray burst network produce a 0.1 arc sq. min. error box. It is nested inside the initially determined 2 arc sq min. source region. This smaller source location is within both the optical and X-ray contours of N49 although not positioned at either contour center.

  13. ATel draft: Fermi LAT detection of a new Gamma-ray Source PKS 2247-131

    NASA Astrophysics Data System (ADS)

    Buson, S.

    2016-07-01

    The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed strong gamma-ray emission from a source positionally consistent with the radio source PKS 2247-131 with coordinates RA=342.4983854 deg, Dec=-12.8546736 deg (J2000; Beasley et al. 2002, ApJS, 141, 13). This source is not in any published LAT catalog and was not detected by AGILE or EGRET.

  14. Gamma ray burst source locations with the Ulysses/Compton/PVO network

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Hurley, K. C.; Boer, M.; Sommer, M.; Niel, M.; Fishman, G. J.; Kouveliotou, C.; Meegan, C. A.; Paciesas, W. S.; Wilson, R. B.

    1992-01-01

    The new interplanetary gamma-ray burst network will determine source fields with unprecedented accuracy. The baseline of the Ulysses mission and the locations of Pioneer-Venus Orbiter and of Mars Observer will ensure precision to a few tens of arc seconds. Combined with the event phenomenologies of the Burst and Transient Source Experiment on Compton Observatory, the source locations to be achieved with this network may provide a basic new understanding of the puzzle of gamma ray bursts.

  15. A high intensity dc H- source for low energy injection

    NASA Astrophysics Data System (ADS)

    Kuo, T.; Baartman, R.; Dutto, G.; Hahto, S.; ńrje, J.; Liukkonen, E.

    2002-02-01

    While a 20 mA dc H- source system at 25-30 keV beam energy has been developed at TRIUMF several years ago, another recent demand on the system is to provide a 4 to 5 mA H- at the 4-6 keV energy range. We found that at this low energy range, the existing source/extraction system can only give ˜1 mA with poor emittance due to strong space-charge effect. Fortunately, a very special source/extraction mechanism together with the use of neutralization was discovered and developed to overcome this difficulty. Up to 4 mA with a normalized rms emittance of 0.15 π mm mr has been achieved at 6 keV. This performance finds its usefulness for injection systems where lower beam energy and higher beam intensity are required. A copy of the TRIUMF system was constructed and successfully tested in the summer of 2000 for the "H- Acceleration Project" for the K130 cyclotron at Jyväskylä University, Finland.

  16. Gamma-ray bursts during neutron star formation. Gamma-ray bursts and transient X-ray sources

    NASA Technical Reports Server (NTRS)

    Cohen, J. M.; Desai, U. D.; Holt, S. S.

    1973-01-01

    Discussions are presented of the associations between cosmic gamma ray bursts and transient X-ray sources, and the release of gravitational binding energy during the formation of neutron stars. The model for studying the associations is described along with the release of neutrinos during the collapse of white dwarfs.

  17. Utilization of the intense pulsed neutron source (IPNS) at Argonne National Laboratory for neutron activation analysis

    SciTech Connect

    Heinrich, R.R.; Greenwood, L.R.; Popek, R.J.; Schulke, A.W. Jr.

    1983-01-01

    The Intense Pulsed Neutron Source (IPNS) neutron scattering facility (NSF) has been investigated for its applicability to neutron activation analysis. A polyethylene insert has been added to the vertical hole VT3 which enhances the thermal neutron flux by a factor of two. The neutron spectral distribution at this position has been measured by the multiple-foil technique which utilized 28 activation reactions and the STAYSL computer code. The validity of this spectral measurement was tested by two irradiations of National Bureau of Standards SRM-1571 (orchard leaves), SRM-1575 (pine needles), and SRM-1645 (river sediment). The average thermal neutron flux for these irradiations normalized to 10 ..mu..amp proton beam is 4.0 x 10/sup 11/ n/cm/sup 2/-s. Concentrations of nine trace elements in each of these SRMs have been determined by gamma-ray spectrometry. Agreement of measured values to certified values is demonstrated to be within experiment error.

  18. General Purpose Kernel Integration Shielding Code System-Point and Extended Gamma-Ray Sources.

    1981-06-11

    PELSHIE3 calculates dose rates from gamma-emitting sources with different source geometries and shielding configurations. Eight source geometries are provided and are called by means of geometry index numbers. Gamma-emission characteristics for 134 isotopes, attenuation coefficients for 57 elements or shielding materials and Berger build-up parameters for 17 shielding materials can be obtained from a direct access data library by specifying only the appropriate library numbers. A different option allows these data to be read frommore » cards. For extended sources, constant source strengths as well as exponential and Bessel function source strength distributions are allowed in most cases.« less

  19. Precision linac and laser technologies for nuclear photonics gamma-ray sources

    SciTech Connect

    Albert, F.; Hartemann, F. V.; Anderson, S. G.; Cross, R. R.; Gibson, D. J.; Hall, J.; Marsh, R. A.; Messerly, M.; Wu, S. S.; Siders, C. W.; Barty, C. P. J.

    2012-05-15

    Tunable, high precision gamma-ray sources are under development to enable nuclear photonics, an emerging field of research. This paper focuses on the technological and theoretical challenges related to precision Compton scattering gamma-ray sources. In this scheme, incident laser photons are scattered and Doppler upshifted by a high brightness electron beam to generate tunable and highly collimated gamma-ray pulses. The electron and laser beam parameters can be optimized to achieve the spectral brightness and narrow bandwidth required by nuclear photonics applications. A description of the design of the next generation precision gamma-ray source currently under construction at Lawrence Livermore National Laboratory is presented, along with the underlying motivations. Within this context, high-gradient X-band technology, used in conjunction with fiber-based photocathode drive laser and diode pumped solid-state interaction laser technologies, will be shown to offer optimal performance for high gamma-ray spectral flux, narrow bandwidth applications.

  20. Astrophysical Ionizing Radiation and Earth: A Brief Review and Census of Intermittent Intense Sources

    NASA Astrophysics Data System (ADS)

    Melott, Adrian L.; Thomas, Brian C.

    2011-05-01

    Cosmic radiation backgrounds are a constraint on life, and their distribution will affect the Galactic Habitable Zone. Life on Earth has developed in the context of these backgrounds, and characterizing event rates will elaborate the important influences. This in turn can be a base for comparison with other potential life-bearing planets. In this review, we estimate the intensities and rates of occurrence of many kinds of strong radiation bursts by astrophysical entities, ranging from gamma-ray bursts at cosmological distances to the Sun itself. Many of these present potential hazards to the biosphere; on timescales long compared with human history, the probability of an event intense enough to disrupt life on the land surface or in the oceans becomes large. Both photons (e.g., X-rays) and high-energy protons and other nuclei (often called "cosmic rays") constitute hazards. For either species, one of the mechanisms that comes into play even at moderate intensities is the ionization of Earth's atmosphere, which leads through chemical changes (specifically, depletion of stratospheric ozone) to increased ultraviolet B flux from the Sun reaching the surface. UVB is extremely hazardous to most life due to its strong absorption by the genetic material DNA and subsequent breaking of chemical bonds. This often leads to mutation or cell death. It is easily lethal to the microorganisms that lie at the base of the food chain in the ocean. We enumerate the known sources of radiation and characterize their intensities at Earth and rates or upper limits on these quantities. When possible, we estimate a "lethal interval," our best estimate of how often a major extinction-level event is probable given the current state of knowledge; we base these estimates on computed or expected depletion of stratospheric ozone. In general, moderate-level events are dominated by the Sun, but the far more severe infrequent events are probably dominated by gamma-ray bursts and supernovae. We note

  1. Astrophysical ionizing radiation and Earth: a brief review and census of intermittent intense sources.

    PubMed

    Melott, Adrian L; Thomas, Brian C

    2011-05-01

    Cosmic radiation backgrounds are a constraint on life, and their distribution will affect the Galactic Habitable Zone. Life on Earth has developed in the context of these backgrounds, and characterizing event rates will elaborate the important influences. This in turn can be a base for comparison with other potential life-bearing planets. In this review, we estimate the intensities and rates of occurrence of many kinds of strong radiation bursts by astrophysical entities, ranging from gamma-ray bursts at cosmological distances to the Sun itself. Many of these present potential hazards to the biosphere; on timescales long compared with human history, the probability of an event intense enough to disrupt life on the land surface or in the oceans becomes large. Both photons (e.g., X-rays) and high-energy protons and other nuclei (often called "cosmic rays") constitute hazards. For either species, one of the mechanisms that comes into play even at moderate intensities is the ionization of Earth's atmosphere, which leads through chemical changes (specifically, depletion of stratospheric ozone) to increased ultraviolet B flux from the Sun reaching the surface. UVB is extremely hazardous to most life due to its strong absorption by the genetic material DNA and subsequent breaking of chemical bonds. This often leads to mutation or cell death. It is easily lethal to the microorganisms that lie at the base of the food chain in the ocean. We enumerate the known sources of radiation and characterize their intensities at Earth and rates or upper limits on these quantities. When possible, we estimate a "lethal interval," our best estimate of how often a major extinction-level event is probable given the current state of knowledge; we base these estimates on computed or expected depletion of stratospheric ozone. In general, moderate-level events are dominated by the Sun, but the far more severe infrequent events are probably dominated by gamma-ray bursts and supernovae. We note

  2. Astrophysical ionizing radiation and Earth: a brief review and census of intermittent intense sources.

    PubMed

    Melott, Adrian L; Thomas, Brian C

    2011-05-01

    Cosmic radiation backgrounds are a constraint on life, and their distribution will affect the Galactic Habitable Zone. Life on Earth has developed in the context of these backgrounds, and characterizing event rates will elaborate the important influences. This in turn can be a base for comparison with other potential life-bearing planets. In this review, we estimate the intensities and rates of occurrence of many kinds of strong radiation bursts by astrophysical entities, ranging from gamma-ray bursts at cosmological distances to the Sun itself. Many of these present potential hazards to the biosphere; on timescales long compared with human history, the probability of an event intense enough to disrupt life on the land surface or in the oceans becomes large. Both photons (e.g., X-rays) and high-energy protons and other nuclei (often called "cosmic rays") constitute hazards. For either species, one of the mechanisms that comes into play even at moderate intensities is the ionization of Earth's atmosphere, which leads through chemical changes (specifically, depletion of stratospheric ozone) to increased ultraviolet B flux from the Sun reaching the surface. UVB is extremely hazardous to most life due to its strong absorption by the genetic material DNA and subsequent breaking of chemical bonds. This often leads to mutation or cell death. It is easily lethal to the microorganisms that lie at the base of the food chain in the ocean. We enumerate the known sources of radiation and characterize their intensities at Earth and rates or upper limits on these quantities. When possible, we estimate a "lethal interval," our best estimate of how often a major extinction-level event is probable given the current state of knowledge; we base these estimates on computed or expected depletion of stratospheric ozone. In general, moderate-level events are dominated by the Sun, but the far more severe infrequent events are probably dominated by gamma-ray bursts and supernovae. We note

  3. High intensity neutrino source superconducting solenoid cyrostat design

    SciTech Connect

    Page, T.M.; Nicol, T.H.; Feher, S.; Terechkine, I.; Tompkins, J.; /Fermilab

    2006-06-01

    Fermi National Accelerator Laboratory (FNAL) is involved in the development of a 100 MeV superconducting linac. This linac is part of the High Intensity Neutrino Source (HINS) R&D Program. The initial beam acceleration in the front end section of the linac is achieved using room temperature spoke cavities, each of which is combined with a superconducting focusing solenoid. These solenoid magnets are cooled with liquid helium at 4.5K, operate at 250 A and have a maximum magnetic field strength of 7.5 T. The solenoid cryostat will house the helium vessel, suspension system, thermal shield, multilayer insulation, power leads, instrumentation, a vacuum vessel and cryogenic distribution lines. This paper discusses the requirements and detailed design of these superconducting solenoid cryostats.

  4. High Intensity Neutrino Source Superconducting Solenoid Cryostat Design

    NASA Astrophysics Data System (ADS)

    Page, T. M.; Nicol, T. H.; Feher, S.; Terechkine, I.; Tompkins, J.

    2008-03-01

    Fermi National Accelerator Laboratory (FNAL) is involved in the development of a 100 MeV superconducting linac. This linac is part of the High Intensity Neutrino Source (HINS) R&D Program. The initial beam acceleration in the front end section of the linac is achieved using room temperature spoke cavities, each of which is combined with a superconducting focusing solenoid. These solenoid magnets are cooled with liquid helium at 4.5 K, operate at 250 A and have a maximum magnetic field strength of 7.5 T. The solenoid cryostat will house the helium vessel, suspension system, thermal shield, multilayer insulation, power leads, instrumentation, a vacuum vessel and cryogenic distribution lines. This paper discusses the requirements and detailed design of these superconducting solenoid cryostats.

  5. HIGH INTENSITY LOW-ENERGY POSITRON SOURCE AT JEFFERSON

    SciTech Connect

    Serkan Golge, Bogdan Wojtsekhowski, Branislav Vlahovic

    2012-07-01

    We present a novel concept of a low-energy e{sup +} source with projected intensity on the order of 10{sup 10} slow e{sup +}/s. The key components of this concept are a continuous wave e{sup -} beam, a rotating positron-production target, a synchronized raster/anti-raster, a transport channel, and extraction of e{sup +} into a field-free area through a magnetic plug for moderation in a cryogenic solid. Components were designed in the framework of GEANT4-based (G4beamline) Monte Carlo simulation and TOSCA magnetic field calculation codes. Experimental data to demonstrate the effectiveness of the magnetic plug is presented.

  6. Coherent Cherenkov radiation as an intense THz source

    NASA Astrophysics Data System (ADS)

    Bleko, V.; Karataev, P.; Konkov, A.; Kruchinin, K.; Naumenko, G.; Potylitsyn, A.; Vaughan, T.

    2016-07-01

    Diffraction and Cherenkov radiation of relativistic electrons from a dielectric target has been proposed as mechanism for production of intense terahertz (THz) radiation. The use of an extremely short high-energy electron beam of a 4th generation light source (X-ray free electron laser) appears to be very promising. A moderate power from the electron beam can be extracted and converted into THz radiation with nearly zero absorption losses. The initial experiment on THz observation will be performed at CLARA/VELA FEL test facility in the UK to demonstrate the principle to a wider community and to develop the radiator prototype. In this paper, we present our theoretical predictions (based on the approach of polarization currents), which provides the basis for interpreting the future experimental measurements. We will also present our hardware design and discuss a plan of the future experiment.

  7. Non-association of a celestial gamma ray source with the new Milky Way satellite galaxy

    NASA Technical Reports Server (NTRS)

    Lamb, R. C.; Thompson, D. J.; Fichtel, C. E.

    1975-01-01

    The newly discovered satellite galaxy located in the Milky Way galactic anti-center region is discussed along with the possibility that a nearby gamma ray source is associated with it. The factors which led to the conclusion that the gamma ray excess is not associated with the galaxy are considered.

  8. Three-dimensional localization of low activity gamma-ray sources in real-time scenarios

    NASA Astrophysics Data System (ADS)

    Sharma, Manish K.; Alajo, Ayodeji B.; Lee, Hyoung K.

    2016-03-01

    Radioactive source localization plays an important role in tracking radiation threats in homeland security tasks. Its real-time application requires computationally efficient and reasonably accurate algorithms even with limited data to support detection with minimum uncertainty. This paper describes a statistic-based grid-refinement method for backtracing the position of a gamma-ray source in a three-dimensional domain in real-time. The developed algorithm used measurements from various known detector positions to localize the source. This algorithm is based on an inverse-square relationship between source intensity at a detector and the distance from the source to the detector. The domain discretization was developed and implemented in MATLAB. The algorithm was tested and verified from simulation results of an ideal case of a point source in non-attenuating medium. Subsequently, an experimental validation of the algorithm was performed to determine the suitability of deploying this scheme in real-time scenarios. Using the measurements from five known detector positions and for a measurement time of 3 min, the source position was estimated with an accuracy of approximately 53 cm. The accuracy improved and stabilized to approximately 25 cm for higher measurement times. It was concluded that the error in source localization was primarily due to detection uncertainties. In verification and experimental validation of the algorithm, the distance between 137Cs source and any detector position was between 0.84 m and 1.77 m. The results were also compared with the least squares method. Since the discretization algorithm was validated with a weak source, it is expected that it can localize the source of higher activity in real-time. It is believed that for the same physical placement of source and detectors, a source of approximate activity 0.61-0.92 mCi can be localized in real-time with 1 s of measurement time and same accuracy. The accuracy and computational efficiency

  9. The intriguing nature of the high-energy gamma ray source XSS J12270-4859

    NASA Astrophysics Data System (ADS)

    de Martino, D.; Falanga, M.; Bonnet-Bidaud, J.-M.; Belloni, T.; Mouchet, M.; Masetti, N.; Andruchow, I.; Cellone, S. A.; Mukai, K.; Matt, G.

    2010-06-01

    Context. The nature of the hard X-ray source XSS J12270-4859 is still unclear. It was claimed to be a possible magnetic cataclysmic variable of the Intermediate Polar type from its optical spectrum and a possible 860 s X-ray periodicity in RXTE data. However, recent observations do not support the latter variability, leaving this X-ray source still unclassified. Aims: To investigate its nature we present a broad-band X-ray and gamma ray study of this source based on a recent XMM-Newton observation and archival INTEGRAL and RXTE data. Using the Fermi/LAT 1-year point source catalogue, we tentatively associate XSS J12270-4859 with 1FGL J1227.9-4852, a source of high-energy gamma rays with emission up to 10 GeV. We further complement the study with UV photometry from XMM-Newton and ground-based optical and near-IR photometry. Methods: We have analysed both timing and spectral properties in the gamma rays, X-rays, UV and optical/near-IR bands of XSS J12270-4859. Results: The X-ray emission is highly variable, showing flares and intensity dips. The flares consist of flare-dip pairs. Flares are detected in both X-rays and the UV range, while the subsequent dips are present only in the X-ray band. Further aperiodic dipping behaviour is observed during X-ray quiescence, but not in the UV. The broad-band 0.2-100 keV X-ray/soft gamma ray spectrum is featureless and well described by a power law model with Γ = 1.7. The high-energy spectrum from 100 MeV to 10 GeV is represented by a power law index of 2.45. The luminosity ratio between 0.1-100 GeV and 0.2-100 keV is ~0.8, indicating that the GeV emission is a significant component of the total energy output. Furthermore, the X-ray spectrum does not greatly change during flares, quiescence and the dips seen in quiescence. The X-ray spectrum however hardens during the post-flare dips, where a partial covering absorber is also required to fit the spectrum. Optical photometry acquired at different epochs reveals a period of 4

  10. The Intensity Distribution for Gamma-Ray Bursts Observed with BATSE

    NASA Technical Reports Server (NTRS)

    Pendleton, Geoffrey N.; Mallozzi, Robert S.; Paciesas, William S.; Briggs, Michael S.; Preece, Robert D.; Koshut, Tom M.; Horack, John M.; Meegan, Charles A.; Fishman, Gerald J.; Hakkila, Jon; Kouveliotou, Cryssa

    1996-01-01

    The intensity distributions of gamma-ray bursts observed by BATSE from 19 April 1991 to 19 September 1994 are presented. For this data set, (V/V(sub max)) is 0.329 +/- 0.011, which is 15.5 sigma away from the value of 0.5 expected for a homogeneous distribution. Standard cosmological model parameters are obtained by fitting the differentially binned peak flux distribution expressed in units of photons cm(exp -2) s(exp -1) in the energy range 50-300 keV. The value of z calculated for a peak flux of 1 photon cm(exp -2) s(exp -1) is 0.8 +/- 0.33. The procedures used to produce the peak flux data and C(sub p)/C(sub lim) data are presented. The differences between the two representations of burst intensity are emphasized so that researchers can determine which type of data is most appropriate for their studies. The sky sensitivity correction as a function of intensity for the peak flux data is also described.

  11. Measurement of gamma-ray intensities of 231Th using semiconductor detectors

    NASA Astrophysics Data System (ADS)

    Chatani, Hiroshi

    1999-04-01

    Nuclide 231Th was yielded by the 232Th(n, 2n) reaction with neutron irradiation in the Kyoto University Reactor (KUR). Moreover, the thorium was purified chemically. Gamma-ray spectra of thorium have been measured using low-energy photon spectrometers and a high-purity germanium detector. Relative γ-ray intensities ranging from 25 to 352 keV in the decay of 231Th have been determined with satisfactory accuracy. The results are in very good agreement with those of earlier studies. We observe two new γ-rays at 77.69 and 177.66 keV, whose intensities are found to be (0.063±0.010)% and (0.00095±0.00020)%, respectively, relative to that of 84.21 keV taken as 100%. Absolute intensity of 84.21 keV γ-ray which is the most prominent one from the decay of 231Th and that of 185.739 keV following the decay of 235U are also determined from the secular equilibrium for 235U- 231Th. The results obtained in two cases are (6.60±0.25)% and (58±2)%, respectively.

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  13. Gamma-Ray Burst Subclasses: Separating Instrumental Biases from Potential Source Populations

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon

    1999-01-01

    Instrumental effects mar gamma-ray burst observations. These effects can alter whether or not bursts trigger, as well as changing measured burst properties. The Burst And Transient Source Experiment (BATSE) on NASA's Compton Gamma-Ray Observatory (CGRO) has provided the largest database of gamma-ray bursts observed to date. It also provides an excellent laboratory for studying instrumental biases. We examine trigger biases and burst property biases as they pertain to previously identified gamma-ray burst classes. We also study some burst class properties in the new age of burst afterglow studies.

  14. Gamma-ray burst locations from the Burst and Transient Source Experiment

    NASA Technical Reports Server (NTRS)

    Brock, M. N.; Meegan, C. A.; Roberts, F. E.; Fishman, G. J.; Wilson, R. B.; Paciesas, W. S.; Pendleton, G. N.

    1992-01-01

    The Burst and Transient Source Experiment (BATSE) consists of eight anisotropic gamma-ray spectrometers at the corners of the Compton Gamma Ray Observatory. BATSE monitors the full sky from a fixed orientation and determines the direction of gamma-ray bursts with an accuracy appropriate for studying the bursts' celestial distribution. We describe the calculation of gamma-ray burst directions from measurements made by BATSE. We present a sample of calculated directions from BATSE's measurement of solar flaxes and compare the calculated directions with the solar direction. We describe the systematic errors apparent in these data and discuss ongoing efforts to correct them.

  15. Intense gamma-ray lines from hidden vector dark matter decay

    SciTech Connect

    Arina, Chiara; Hambye, Thomas; Ibarra, Alejandro; Weniger, Christoph E-mail: thambye@ulb.ac.be E-mail: christoph.weniger@desy.de

    2010-03-01

    Scenarios with hidden, spontaneously broken, non-abelian gauge groups contain a natural dark matter candidate, the hidden vector, whose longevity is due to an accidental custodial symmetry in the renormalizable Lagrangian. Nevertheless, non-renormalizable dimension six operators break the custodial symmetry and induce the decay of the dark matter particle at cosmological times. We discuss in this paper the cosmic ray signatures of this scenario and we show that the decay of hidden vector dark matter particles generically produce an intense gamma ray line which could be observed by the Fermi-LAT experiment, if the scale of custodial symmetry breaking is close to the Grand Unification scale. This gamma line proceeds directly from a tree level dark matter 2-body decay in association with a Higgs boson. Within this model we also perform a determination of the relic density constraints taking into account the dark matter annihilation processes with one dark matter particle in the final state. The corresponding direct detection rates can be easily of order the current experimental sensitivities.

  16. The PhIX High Intensity Plasma Source

    NASA Astrophysics Data System (ADS)

    Goulding, R. H.; Caughman, J. B. O.; Peng, Y.-K. M.; Rapp, J.; Rasmussen, D. A.; Biewer, T. M.; Canik, J. M.; Chen, G.; Diem, S. J.; Meitner, S. J.; Owen, L. W.

    2012-10-01

    The Physics Integration eXperiment (PhIX) is a linear high-intensity rf plasma source presently being constructed at ORNL that combines a high density helicon plasma generator with an electron heating section. It will be used to explore the physics related to heating an overdense, streaming plasma in a linear geometry by whistler waves and Electron Bernstein Waves (EBW), including optimization of heating efficiency and maximization of particle flux. Interactions between the plasma production and heating regions, and the source and a downstream target, will also be investigated. Experiments using the device will provide data for the design of an rf powered high particle flux (˜10^24/m^2- s), high heat flux(˜10 MW /m^2) steady-state linear plasma-materials test station (PMTS). In preparatory experiments, the helicon device has operated at power levels up to 90 kW, producing high plasma densities in He (6 x10^19 m-3) and D (> 4 x10^19 m-3), and has also operated at high magnetic field strength up to 0.5 T. Separate ECH experiments have demonstrated both whistler and EBW coupling at 6 GHz to an overdense plasma. A review of these experiments will be presented, as well as an overview of PhIX and its status.

  17. Fermi Establishes Classical Novae as a Distinct Class of Gamma-ray Sources

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Albert, A.; Baldini, L.; Ballet, J.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Ferrara, E. C.; Harding, A. K.; Hays, E.; Perkins, J. S.; Thompson, D. J.

    2014-01-01

    A classical nova results from runaway thermonuclear explosions on the surface of a white dwarf that accretes matter from a low-mass main-sequence stellar companion. In 2012 and 2013, three novae were detected in gamma rays and stood in contrast to the first gamma-ray detected nova V407 Cygni 2010, which belongs to a rare class of symbiotic binary systems. Despite likely differences in the compositions and masses of their white dwarf progenitors, the three classical novae are similarly characterized as soft spectrum transient gamma-ray sources detected over 2-3 week durations. The gamma-ray detections point to unexpected high-energy particle acceleration processes linked to the mass ejection from thermonuclear explosions in an unanticipated class of Galactic gamma-ray sources.

  18. X-ray and gamma-ray astronomy. [origins of extraterrestrial radiation sources

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Accomplishments in the fields of X-ray and gamma ray astronomy are discussed. Data obtained from IMP and OGO satellites are analyzed to determine the sources of interplanetary radiation bursts. The energy spectrum of cosmic gamma ray bursts as observed by IMP-6 is described. The application of cooling blackbody techniques as a method for examining cosmic gamma ray bursts is reported. The experimental results and theoretical interpretation of high energy diffuse gamma rays are investigated. The structure of the SAS-2 satellite is depicted and the accomplishments are examined. Other sources of gamma radiation to include galactic fermi, Cygnus X-1, supernovae, and the planet Jupiter are proposed. Data obtained from the Pioneer 10 space probe are presented in graph form.

  19. Constraints on neutron star models of gamma-burst sources from the Einstein Observatory

    NASA Technical Reports Server (NTRS)

    Pizzichini, G.; Gottardi, M.; Atteia, J.-L.; Barat, C.; Hurley, K.; Niel, M.; Vedrenne, G.; Laros, J. G.; Cline, T. L.; Desai, U. D.

    1986-01-01

    Six Einstein observations of five gamma-ray burst sources are presented and discussed. With one possible exception, no point source was detected in any of the observations. The data are interpreted in the framework of neutron star models for gamma bursters. Upper limits are derived for the surface temperatures of the neutron stars assumed to be responsible for the bursts. It is shown that the lack of soft X-ray emission may impose stringent constraints on accretion rates onto neutron stars.

  20. New Spherical Gamma-Ray and Neutron Emitting Sources for Testing of Radiation Detection Instruments

    PubMed Central

    Lucas, L.; Pibida, L.

    2009-01-01

    The National Institute of Standards and Technology (NIST) has developed new gamma-ray and neutron emitting sources for testing radiation detection systems. These radioactive sources were developed for testing of detection systems in maritime applications. This required special source characteristics. PMID:27504230

  1. The discovery of a source of repeated soft short gamma bursts in Sagittarius

    NASA Technical Reports Server (NTRS)

    Atteia, J. L.; Boer, M.; Vedrenne, G.; Niel, M.; Hurley, K.; Laros, J.; Fenimore, E.; Klebesadel, R.; Kuznetsov, A. V.; Kouveliotou, C.

    1987-01-01

    Twelve short cosmic gamma-ray bursts were observed during July-December, 1983. The results of the localization of this source on the basis of Prognoz-9 and ICE data are presented. The source is situated 10 deg away from the Galactic Center. These localizations indicate that the January 7, 1979 burst originated from the same source.

  2. Science of Compact X- and Gamma-ray Sources: MAXI and GLAST

    NASA Technical Reports Server (NTRS)

    Thompson, Dave

    2008-01-01

    MAXI and GLAST will be surveying the sky simultaneously. Compact objects that may show variability will be excellent targets for coordinated multiwavelength studies. Gamma-ray bursts (and afterglows), pulsars, high-mass X-ray binaries, microquasars, and active galactic nuclei are all objects whose X- and gamma-ray relationship can be explored by such observations. Of particular interest will be variable unidentified gamma-ray sources, whose contemporaneous observations by MAXI may prove decisive in identifying the source of the high-energy emission.

  3. Average Emissivity Curve of Batse Gamma-Ray Bursts with Different Intensities

    NASA Technical Reports Server (NTRS)

    Mitrofanov, Igor G.; Litvak, Maxim L.; Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey N.; Preece, Robert D.; Meegan, Charles A.

    1999-01-01

    Six intensity groups with approximately 150 BATSE gamma-ray bursts each are compared using average emissivity curves. Time stretch factors for each of the dimmer groups are estimated with respect to the brightest group, which serves as the reference, taking into account the systematics of counts-produced noise effects and choice statistics. A stretching/intensity anticorrelation is found with good statistical significance during the average back slopes of bursts. A stretch factor approximately 2 is found between the 150 dimmest bursts, with peak flux less than 0.45 photons/sq cm.s, and the 147 brightest bursts, with peak flux greater than 4.1 photons/sq cm.s. On the other hand, while a trend of increasing stretching factor may exist for rise fronts for bursts with decreasing peak flux from greater than 4.1 photons/sq cm.s down to 0.7 photons/sq cm.s, the magnitude of the stretching factor is less than approximately 1.4 and is therefore inconsistent with stretching factor of back slope.

  4. Improvement in the practical implementation of neutron source strength calibration using prompt gamma rays.

    PubMed

    Khabaz, Rahim; Rene Vega-Carrillo, Hector

    2013-08-01

    In this study, the neutron emission rate from neutron sources using prompt gamma rays in hydrogen was determined, and several improvements were applied. Using Monte Carlo calculations, the best positions for the source, moderator and detector relative to each other were selected. For (241)Am-Be and (252)Cf sources, the sizes for polyethylene spheres with the highest efficiency were 12- and 10-inch, respectively. In addition, a new shielding cone was designed to account for scattered neutrons and gamma rays. The newly designed shielding cone, which is 45 cm in length, provided suitable attenuation for the source radiation.

  5. Operation of the Proto-MPEX High Intensity Plasma Source

    NASA Astrophysics Data System (ADS)

    Caughman, J. B. O.; Goulding, R. H.; Biewer, T. M.; Bigelow, T. S.; Campbell, I. H.; Diem, S. J.; Martin, E. H.; Pesavento, P. V.; Rapp, J.; Ray, H. B.; Shaw, G. C.; Showers, M. A.; Luo, G.-N.

    2015-11-01

    The Prototype Materials Plasma Experiment (Proto-MPEX) is a linear high-intensity rf plasma source that combines a high-density helicon plasma generator with electron and ion heating sections. It is being used to study the physics of heating over-dense plasmas in a linear configuration. The helicon plasma is produced by coupling 13.56 MHz rf power at levels up to 100 kW. Microwaves at 28 GHz (~ 150 kW) are coupled to the electrons in the over-dense helicon plasma via Electron Bernstein Waves (EBW). Ion cyclotron heating (~ 30 kW) will be via a magnetic beach approach. Plasma diagnostics include Thomson Scattering and a retarding field energy analyzer near the target, while a microwave interferometer and double-Langmuir probes are used to determine plasma parameters elsewhere in the system. Filterscopes are being used to measure D-alpha emission and He line ratios at multiple locations, and IR cameras image the target plates to determine heat deposition. High plasma densities in the helicon region have been produced in He (>3x1019/m3) and D (>1.5x1019/m3) , and operation with on-axis magnetic field strength >1 T has been demonstrated. Details of the experimental results and future plans for studying plasma surface/RF antenna interactions will be presented. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC-05-00OR22725.

  6. A dual neutron/gamma source for the Fissmat Inspection for Nuclear Detection (FIND) system.

    SciTech Connect

    Doyle, Barney Lee; King, Michael; Rossi, Paolo; McDaniel, Floyd Del; Morse, Daniel Henry; Antolak, Arlyn J.; Provencio, Paula Polyak; Raber, Thomas N.

    2008-12-01

    Shielded special nuclear material (SNM) is very difficult to detect and new technologies are needed to clear alarms and verify the presence of SNM. High-energy photons and neutrons can be used to actively interrogate for heavily shielded SNM, such as highly enriched uranium (HEU), since neutrons can penetrate gamma-ray shielding and gamma-rays can penetrate neutron shielding. Both source particles then induce unique detectable signals from fission. In this LDRD, we explored a new type of interrogation source that uses low-energy proton- or deuteron-induced nuclear reactions to generate high fluxes of mono-energetic gammas or neutrons. Accelerator-based experiments, computational studies, and prototype source tests were performed to obtain a better understanding of (1) the flux requirements, (2) fission-induced signals, background, and interferences, and (3) operational performance of the source. The results of this research led to the development and testing of an axial-type gamma tube source and the design/construction of a high power coaxial-type gamma generator based on the {sup 11}B(p,{gamma}){sup 12}C nuclear reaction.

  7. Clinical Realization of Sector Beam Intensity Modulation for Gamma Knife Radiosurgery: A Pilot Treatment Planning Study

    SciTech Connect

    Ma, Lijun; Mason, Erica; Sneed, Penny K.; McDermott, Michael; Polishchuk, Alexei; Larson, David A.; Sahgal, Arjun

    2015-03-01

    Purpose: To demonstrate the clinical feasibility and potential benefits of sector beam intensity modulation (SBIM) specific to Gamma Knife stereotactic radiosurgery (GKSRS). Methods and Materials: SBIM is based on modulating the confocal beam intensities from individual sectors surrounding an isocenter in a nearly 2π geometry. This is in contrast to conventional GKSRS delivery, in which the beam intensities from each sector are restricted to be either 0% or 100% and must be identical for any given isocenter. We developed a SBIM solution based on available clinical planning tools, and we tested it on a cohort of 12 clinical cases as a proof of concept study. The SBIM treatment plans were compared with the original clinically delivered treatment plans to determine dosimetric differences. The goal was to investigate whether SBIM would improve the dose conformity for these treatment plans without prohibitively lengthening the treatment time. Results: A SBIM technique was developed. On average, SBIM improved the Paddick conformity index (PCI) versus the clinically delivered plans (clinical plan PCI = 0.68 ± 0.11 vs SBIM plan PCI = 0.74 ± 0.10, P=.002; 2-tailed paired t test). The SBIM plans also resulted in nearly identical target volume coverage (mean, 97 ± 2%), total beam-on times (clinical plan 58.4 ± 38.9 minutes vs SBIM 63.5 ± 44.7 minutes, P=.057), and gradient indices (clinical plan 3.03 ± 0.27 vs SBIM 3.06 ± 0.29, P=.44) versus the original clinical plans. Conclusion: The SBIM method is clinically feasible with potential dosimetric gains when compared with conventional GKSRS.

  8. H- Ion Sources for High Intensity Proton Drivers

    SciTech Connect

    Johnson, Rolland Paul; Dudnikov, Vadim

    2015-02-20

    Existing RF Surface Plasma Sources (SPS) for accelerators have specific efficiencies for H+ and H- ion generation around 3 to 5 mA/cm2 per kW, where about 50 kW of RF power is typically needed for 50 mA beam current production. The Saddle Antenna (SA) SPS described here was developed to improve H- ion production efficiency, reliability and availability for pulsed operation as used in the ORNL Spallation Neutron Source . At low RF power, the efficiency of positive ion generation in the plasma has been improved to 200 mA/cm2 per kW of RF power at 13.56 MHz. Initial cesiation of the SPS was performed by heating cesium chromate cartridges by discharge as was done in the very first versions of the SPS. A small oven to decompose cesium compounds and alloys was developed and tested. After cesiation, the current of negative ions to the collector was increased from 1 mA to 10 mA with RF power 1.5 kW in the plasma (6 mm diameter emission aperture) and up to 30 mA with 4 kW RF power in the plasma and 250 Gauss longitudinal magnetic field. The ratio of electron current to negative ion current was improved from 30 to 2. Stable generation of H- beam without intensity degradation was demonstrated in the aluminum nitride (AlN) discharge chamber for 32 days at high discharge power in an RF SPS with an external antenna. Some modifications were made to improve the cooling and cesiation stability. The extracted collector current can be increased significantly by optimizing the longitudinal magnetic field in the discharge chamber. While this project demonstrated the advantages of the pulsed version of the SA RF SPS as an upgrade to the ORNL Spallation Neutron Source, it led to a possibility for upgrades to CW machines like the many cyclotrons used for commercial applications. Four appendices contain important details of the work carried out under this grant.

  9. Searching for Gamma-Ray Blazar Candidates Among the Unidentified INTEGRAL Sources

    SciTech Connect

    Massaro, F.; Paggi, A.; D'Abrusco, R.; Tosti, G.; /Perugia U.

    2012-04-02

    The identification of low-energy counterparts for {gamma}-ray sources is one of the biggest challenge in modern {gamma}-ray astronomy. Recently, we developed and successfully applied a new association method to recognize {gamma}-ray blazar candidates that could be possible counterparts for the unidentified {gamma}-ray sources above 100 MeV in the second Fermi Large Area Telescope (LAT) catalog (2FGL). This method is based on the Infrared (IR) colors of the recent Wide-Field Infrared Survey Explorer (WISE) all-sky survey. In this letter we applied our new association method to the case of unidentified INTEGRAL sources (UISs) listed in the fourth soft gamma-ray source catalog (4IC). Only 86 UISs out of the 113 can be analyzed, due to the sky coverage of the WISE Preliminary data release. Among these 86 UISs, we found that 18 appear to have a {gamma}-ray blazar candidate within their positional error region. Finally, we analyzed the Swift archival data available for 10 out these 18 {gamma}-ray blazar candidates, and we found that 7 out of 10 are clearly detected in soft X-rays and/or in the optical-ultraviolet band. We cannot confirm the associations between the UISs and the selected {gamma}-ray blazar candidates due to the discrepancies between the INTEGRAL and the soft X-ray spectra. However, the discovery of the soft X-ray counterparts for the selected {gamma}-ray blazar candidates adds an important clue to help understand their origin and to confirm their blazar nature.

  10. SEARCHING FOR {gamma}-RAY BLAZAR CANDIDATES AMONG THE UNIDENTIFIED INTEGRAL SOURCES

    SciTech Connect

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

    2012-05-10

    The identification of low-energy counterparts for {gamma}-ray sources is one of the biggest challenges in modern {gamma}-ray astronomy. Recently, we developed and successfully applied a new association method to recognize {gamma}-ray blazar candidates that could be possible counterparts for the unidentified {gamma}-ray sources above 100 MeV in the second Fermi Large Area Telescope Catalog. This method is based on the infrared colors of the recent Wide-Field Infrared Survey Explorer (WISE) all-sky survey. In this Letter, we applied our new association method to the case of unidentified INTEGRAL sources (UISs) listed in the fourth soft gamma-ray source catalog. Only 86 UISs out of the 113 can be analyzed due to the sky coverage of the WISE Preliminary Data Release. Among these 86 UISs, we found that 18 appear to have a {gamma}-ray blazar candidate within their positional error region. Finally, we analyzed Swift archival data available for 10 out of these 18 {gamma}-ray blazar candidates, and we found that 7 out of 10 are clearly detected in soft X-rays and/or in the optical-ultraviolet band. We cannot confirm the associations between the UISs and the selected {gamma}-ray blazar candidates due to the discrepancies between the INTEGRAL and the soft X-ray spectra. However, the discovery of the soft X-ray counterparts for the selected {gamma}-ray blazar candidates adds an important clue to help us understand their origin and to confirm their blazar nature.

  11. Identification and control of spacecraft radiation sources of interference to X-ray and gamma-ray experiments

    NASA Technical Reports Server (NTRS)

    Metzger, A. E.; Trombka, J. I.

    1972-01-01

    Apollo 15 and 16 will carry instruments for the purpose of measuring X-ray and gamma ray fluxes from the lunar surface and in cis-lunar space. The intensity levels expected are low over most of the energy range of interest, requiring that background contributions be minimized. The radiation sources on Apollo determined and their interference with these instruments evaluated. The results were used as a basis for dealing with this problem and for recommendations applicable to future manned and unmanned missions.

  12. Fermi LAT detection of a new high-energy transient gamma-ray source Fermi J0751-5136

    NASA Astrophysics Data System (ADS)

    Kocevski, D.; Buson, S.

    2016-08-01

    During the week from 18 July through 25 July, 2016, the Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, observed gamma-ray activity from a previously unidentified transient source.

  13. The Nature of Unidentified Galactic High-Energy Gamma-Ray Sources

    NASA Astrophysics Data System (ADS)

    Carramiñana, Alberto; Reimer, Olaf; Thompson, David J.

    2001-10-01

    This is the first book dedicated to unidentified celestial gamma-ray sources. The launch of the Compton Gamma-Ray Observatory allowed the first all-sky surveys in gamma-rays, the most energetic form of electromagnetic radiation. The Energetic Gamma-Ray Experiment Telescope discovered more than 270 sources of high-energy protons, more than half of which are not identified with known celestial objects. Most of these objects belong to the Milky Way and more than one class of sources are present among the unidentified sources. Unravelling the nature of all these objects requires the combination of different sorts of instruments, like radio telescopes, optical telescopes, and X-ray satellites, together with the next generations of space and ground-based gamma-ray telescopes. This book presents the current knowledge on the subject and outlines strategies for identification of objects with current astronomical facilities. It provides a forward look by outlining the prospects of future generation gamma-ray telescopes. The contributions are detailed and represent valuable material for undergraduate and postgraduate astrophysics students and researchers in the field. Link: http://www.wkap.nl/prod/b/1-4020-0010-3

  14. Radiation reaction in the interaction of ultraintense laser with matter and gamma ray source

    NASA Astrophysics Data System (ADS)

    Ong, J. F.; Teo, W. R.; Moritaka, Toseo; Takabe, H.

    2016-05-01

    Radiation reaction (RR) force plays an important role in gamma ray production in the interaction of ultraintense laser with relativistic counterpropagating electron at intensity 1022 W/cm2 and beyond. The relationship between emission spectrum and initial kinetic energy of electron at such intensities is yet to be clear experimentally. On the other hand, the energy from both the relativistic electron beam and laser pulse may be converted into the gamma rays. Therefore, the conversion efficiency of energy purely from laser pulse into gamma rays is of great interest. We present simulation results of an electron dynamics in strong laser field by taking into account the RR effects. We investigated how the RR effects influence the emission spectrum and photon number distribution for different laser condition. We showed that the peaks of emission spectra are suppressed if higher initial kinetic energy of electron interacts with long laser pulse duration. We then list the conversion efficiencies of laser pulse energy into gamma ray. We note that an electron with energy of 40 MeV would convert up to 80% of the total of electromagnetic work and initial kinetic energy of electron when interacting with 10 fs laser pulse at intensity 2 ×1023 W/cm2. For a bunch of electron with charge 1 nC would emit around 0.1 J of energy into gamma ray emission.

  15. Cygnus X-3 and other ultra-high-energy gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Barnard, John J.

    1987-01-01

    Recently, several binary X-ray sources have been found to be sources of ultrahigh-energy gamma emission. Air-shower observations indicate photon energies above about 1 PeV. Observations from Cyg X-3 are reviewed and compared with data on the sources Her X-1, Vel X-1, and LMC X-4. Current theoretical models for the production of gamma rays and the acceleration of high-energy particles are discussed, and the consequences for the evolution of such systems are examined.

  16. A search for gamma-ray point sources with the Carpet shower array

    NASA Technical Reports Server (NTRS)

    Alexeenko, V. V.; Chudakov, A. E.; Khaerdinov, N. S.; Lidvansky, A. S.; Navarra, G.; Ozrokov, S. S.; Sklyarov, V. V.; Tizengauzen, V. A.

    1985-01-01

    A search for super-high energy gamma-ray point sources has been carried out. The well known source Cyg X-3 was observed first and preliminary results of data analysis are presented. There is not positive excess of showers from the source region, but phase analysis discovers a small pulse at phase 0.6 which corresponds to the integral flux (6 + or - 3) X 10 to the minus 14th power cm-2 sec-1 at E sub gamma 3x10 to the 14th power eV.

  17. Summary Comments: Nuclear Physics and Gamma-Ray Sources for Nuclear Security and Nonproliferation

    NASA Astrophysics Data System (ADS)

    Barty, C. P. J.

    2015-10-01

    The Nuclear Physics and Gamma-ray Sources for Nuclear Security and Nonproliferation (NPNSNP) meeting held in Tokai-mura, Japan from January 28th to 30th, 2014 revealed both the rapid evolution and growth of monoenergetic, laser-Compton, gamma-ray source technology and the emergence of numerous important applications enabled by this technology. More than 500M of large-scale source and development activities were represented at the meeting, including all of the major projects in the United States, Europe and Japan. The meeting was both highly stimulating intellectually and provided an excellent venue for the exploration of new collaborations between groups...

  18. A distance limit for a class of model gamma-ray burst sources

    NASA Technical Reports Server (NTRS)

    Schmidt, W. K. H.

    1977-01-01

    Gamma ray burst sources are presumably not larger than 10 to the 9th power cm as inferred from observed flux variations. If they are homogeneous and isotropically radiating, then from photon density considerations, they would have to be optically thick due to gamma-gamma pair production when assumed to be too far away. Deviations of observed photo spectra from an exponential shape around 1 MeV lead to an upper limit of the possible distance of such sources of only 2 kpc from the sun. Thus the sources must be galactic unless the radiation is highly beamed or emerges from a relativistically moving shell. This conclusion depends only on observed parameters. The possible presence of particles and fields in the sources would require them to be even closer.

  19. Multiwavelength Studies of the Peculiar Gamma-ray Source 3EG J1835+5918

    NASA Technical Reports Server (NTRS)

    Reimer, O.; Brazier, K. T. S.; Carraminana, A.; Kanbach, G.; Nolan, P. L.; Thompson, D. J.

    1999-01-01

    The source 3EG J1835+5918 was discovered early in the CGRO (Compton Gamma Ray Observatory) mission by EGRET as a bright unidentified gamma-ray source outside the galactic plane. Especially remarkable, it has not been possible to identify this object with any known counterpart in any other wavelengths band since then. Analyzing our recent ROSAT HRI observation, for the first time we are able to suggest X-ray counterparts of 3EG J1835+5918. The discovered X-ray sources were subject of deep optical investigations in order to reveal their nature and conclude on the possibility of being counterparts for this peculiar gamma-ray source.

  20. Gamma-Ray Bursts as Sources of Strong Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Granot, Jonathan; Piran, Tsvi; Bromberg, Omer; Racusin, Judith L.; Daigne, Frédéric

    2015-10-01

    Gamma-Ray Bursts (GRBs) are the strongest explosions in the Universe, which due to their extreme character likely involve some of the strongest magnetic fields in nature. This review discusses the possible roles of magnetic fields in GRBs, from their central engines, through the launching, acceleration and collimation of their ultra-relativistic jets, to the dissipation and particle acceleration that power their γ-ray emission, and the powerful blast wave they drive into the surrounding medium that generates their long-lived afterglow emission. An emphasis is put on particular areas in which there have been interesting developments in recent years.

  1. Variability of Point Sources of Gamma Rays Detected by the Fermi Large-Area Telescope

    NASA Astrophysics Data System (ADS)

    Wallace, Eric

    The Large Area Telescope (LAT) aboard the Fermi Gamma-Ray Space Telescope has revolutionized gamma-ray astronomy, allowing the detection of thousands of point sources of gamma rays. Variability studies are of significant interest as a potential source of information about the emission mechanisms, and as a means to identify gamma-ray sources with known sources in other wavelengths and to improve detection sensitivity in searches for new sources. The inclusion of temporal resolution, however, adds to the already considerable complexity of the required analysis, and as a result, variability studies have generally been limited either in scope or in detail, or both, compared to time-integrated spectral analyses. pointlike is a software package designed for fast maximum likelihood analysis of LAT data, allowing for interactive and large-scale analyses. Here, we present an application of pointlike to the characterization of the variability of the full sample of known gamma-ray point sources. We describe the construction of light curves in one-month time bins, spanning the first 42 months of the Fermi mission, for a sample of 2652 sources. We discuss the use of the detection significance in individual months to improve the significance of detection of marginal sources, and show that including that measure of significance increases the set of significantly detected sources by nearly 20% compared to using only the average significance. We describe a statistical measure of the significance of variability in a light curve, and examine the variability of thesample as whole, and of subsets associated with particular source types, especially pulsars. We discuss the use of pulsars, which are generally non-variable on long timescales, to calibrate variability statistics, and to assess the importance of systematic errors in estimates of variability. Finally, we discuss the potential to extend the method to produce light curves of longer duration and finer time binning, and to search

  2. Beta decay of the fission product 125Sb and a new complete evaluation of absolute gamma ray transition intensities

    NASA Astrophysics Data System (ADS)

    Rajput, M. U.; Ali, N.; Hussain, S.; Mujahid, S. A.; MacMahon, D.

    2012-04-01

    The radionuclide 125Sb is a long-lived fission product, which decays to 125Te by negative beta emission with a half-life of 1008 day. The beta decay is followed by the emission of several gamma radiations, ranging from low to medium energy, that can suitably be used for high-resolution detector calibrations, decay heat calculations and in many other applications. In this work, the beta decay of 125Sb has been studied in detail. The complete published experimental data of relative gamma ray intensities in the beta decay of the radionuclide 125Sb has been compiled. The consistency analysis was performed and discrepancies found at several gamma ray energies. Evaluation of the discrepant data was carried out using Normalized Residual and RAJEVAL methods. The decay scheme balance was carried out using beta branching ratios, internal conversion coefficients, populating and depopulating gamma transitions to 125Te levels. The work has resulted in the consistent conversion factor equal to 29.59(13) %, and determined a new evaluated set of the absolute gamma ray emission probabilities. The work has also shown 22.99% of the delayed intensity fraction as outgoing from the 58 d isomeric 144 keV energy level and 77.01% of the prompt intensity fraction reaching to the ground state from the other excited states. The results are discussed and compared with previous evaluations. The present work includes additional experimental data sets which were not included in the previous evaluations. A new set of recommended relative and absolute gamma ray emission probabilities is presented.

  3. The Structure of the Strongly Lensed Gamma-Ray Source B2 0218+35

    NASA Astrophysics Data System (ADS)

    Barnacka, Anna; Geller, Margaret J.; Dell’Antonio, Ian P.; Zitrin, Adi

    2016-04-01

    Strong gravitational lensing is a powerful tool for resolving the high-energy universe. We combine the temporal resolution of Fermi-LAT, the angular resolution of radio telescopes, and the independently and precisely known Hubble constant from the analysis by the Planck collaboration, to resolve the spatial origin of gamma-ray flares in the strongly lensed source B2 0218+35. The lensing model achieves 1 mas spatial resolution of the source at gamma-ray energies. The data imply that the gamma-ray flaring sites are separate from the radio core: the bright gamma-ray flare (MJD: 56160-56280) occurred 51+/- 8 pc from the 15 GHz radio core, toward the central engine. This displacement is significant at the ∼ 3σ level, and is limited primarily by the precision of the Hubble constant. B2 0218+35 is the first source where the position of the gamma-ray emitting region relative to the radio core can be resolved. We discuss the potential of an ensemble of strongly lensed high-energy sources for elucidating the physics of distant variable sources based on data from Chandra and SKA.

  4. BALLERINA - Pirouettes in search of gamma burst sources

    SciTech Connect

    Brandt, Soeren; Lund, Niels

    1999-12-15

    The cosmological origin of gamma-ray bursts (GRBs) has now been established with reasonable certainty. Many more bursts will need to be studied to establish the typical distance scale, and to map out the large variability in properties, which have been indicated by the first handful of events. We are proposing BALLERINA, a small satellite to provide accurate gamma burst positions at a rate an order of magnitude larger than from Beppo-SAX. On the experimental side, it remains a challenge to ensure the earliest detection of the X-ray afterglow. The mission proposed here allows for the first time systematic studies of the soft X-ray emission in the time interval from only a few minutes after the onset of the burst to a few hours later. In addition to positions of GRBs with accuracy better than 1'reported to the ground within a few minutes of the burst, essential for follow-up work, BALLERINA will on its own provide observations in an uncharted region of parameter space. Secondary objectives of the BALLERINA mission includes observations of the earliest phases of the outbursts of X-ray novae and other X-ray transients. BALLERINA is one of four missions currently under study for the Danish Small Satellite Program. The selection will be announced in 1999 for a planned launch in 2002-2003.

  5. BALLERINA-Pirouettes in search of gamma burst sources

    NASA Astrophysics Data System (ADS)

    Brandt, Søren; Lund, Niels

    1999-12-01

    The cosmological origin of gamma-ray bursts (GRBs) has now been established with reasonable certainty. Many more bursts will need to be studied to establish the typical distance scale, and to map out the large variability in properties, which have been indicated by the first handful of events. We are proposing BALLERINA, a small satellite to provide accurate gamma burst positions at a rate an order of magnitude larger than from Beppo-SAX. On the experimental side, it remains a challenge to ensure the earliest detection of the X-ray afterglow. The mission proposed here allows for the first time systematic studies of the soft X-ray emission in the time interval from only a few minutes after the onset of the burst to a few hours later. In addition to positions of GRBs with accuracy better than 1'reported to the ground within a few minutes of the burst, essential for follow-up work, BALLERINA will on its own provide observations in an uncharted region of parameter space. Secondary objectives of the BALLERINA mission includes observations of the earliest phases of the outbursts of X-ray novae and other X-ray transients. BALLERINA is one of four missions currently under study for the Danish Small Satellite Program. The selection will be announced in 1999 for a planned launch in 2002-2003.

  6. Efficient gamma-ray generation by ultra-intense laser pulses obliquely incident on a planar plasma layer

    NASA Astrophysics Data System (ADS)

    Serebryakov, D. A.; Nerush, E. N.

    2016-04-01

    We have carried out numerical simulations of oblique incidence of a laser pulse with an intensity of I = 1.33 × 1023 W cm-2 on a planar plasma layer and found the plasma density and the angle of incidence of p-polarised laser pulses that correspond to the highest gamma-ray generation efficiency and high gamma-ray directivity. The shape of the plasma surface has been determined by simulation and conditions have been considered that lead to an increase in generation efficiency.

  7. A correlation between hard gamma-ray sources and cosmic voids along the line of sight

    SciTech Connect

    Furniss, A.; Sutter, P. M.; Primack, J. R.; Dominguez, A.

    2014-11-25

    We estimate the galaxy density along lines of sight to hard extragalactic gamma-ray sources by correlating source positions on the sky with a void catalog based on the Sloan Digital Sky Survey (SDSS). Extragalactic gamma-ray sources that are detected at very high energy (VHE; E > 100 GeV) or have been highlighted as VHE-emitting candidates in the Fermi Large Area Telescope hard source catalog (together referred to as “VHE-like” sources) are distributed along underdense lines of sight at the 2.4σ level. There is a less suggestive correlation for the Fermi hard source population (1.7σ). A correlation between 10-500 GeV flux and underdense fraction along the line of sight for VHE-like and Fermi hard sources is found at 2.4σ and 2.6σ, calculated from the Pearson correlation coefficients of r = 0.57 and 0.47, respectively. The preference for underdense sight lines is not displayed by gamma-ray emitting galaxies within the second Fermi catalog, containing sources detected above 100 MeV, or the SDSS DR7 quasar catalog. We investigate whether this marginal correlation might be a result of lower extragalactic background light (EBL) photon density within the underdense regions and find that, even in the most extreme case of a entirely underdense sight line, the EBL photon density is only 2% less than the nominal EBL density. Translating this into gamma-ray attenuation along the line of sight for a highly attenuated source with opacity τ(E, z) ~ 5, we estimate that the attentuation of gamma-rays decreases no more than 10%. This decrease, although non-neglible, is unable to account for the apparent hard source correlation with underdense lines of sight.

  8. A correlation between hard gamma-ray sources and cosmic voids along the line of sight

    DOE PAGES

    Furniss, A.; Sutter, P. M.; Primack, J. R.; Dominguez, A.

    2014-11-25

    We estimate the galaxy density along lines of sight to hard extragalactic gamma-ray sources by correlating source positions on the sky with a void catalog based on the Sloan Digital Sky Survey (SDSS). Extragalactic gamma-ray sources that are detected at very high energy (VHE; E > 100 GeV) or have been highlighted as VHE-emitting candidates in the Fermi Large Area Telescope hard source catalog (together referred to as “VHE-like” sources) are distributed along underdense lines of sight at the 2.4σ level. There is a less suggestive correlation for the Fermi hard source population (1.7σ). A correlation between 10-500 GeV fluxmore » and underdense fraction along the line of sight for VHE-like and Fermi hard sources is found at 2.4σ and 2.6σ, calculated from the Pearson correlation coefficients of r = 0.57 and 0.47, respectively. The preference for underdense sight lines is not displayed by gamma-ray emitting galaxies within the second Fermi catalog, containing sources detected above 100 MeV, or the SDSS DR7 quasar catalog. We investigate whether this marginal correlation might be a result of lower extragalactic background light (EBL) photon density within the underdense regions and find that, even in the most extreme case of a entirely underdense sight line, the EBL photon density is only 2% less than the nominal EBL density. Translating this into gamma-ray attenuation along the line of sight for a highly attenuated source with opacity τ(E, z) ~ 5, we estimate that the attentuation of gamma-rays decreases no more than 10%. This decrease, although non-neglible, is unable to account for the apparent hard source correlation with underdense lines of sight.« less

  9. On the possibility of observing cosmic ray sources in high energy gamma rays

    NASA Technical Reports Server (NTRS)

    Ormes, J. F.

    1987-01-01

    If cosmic rays are accelerated by strong shocks, then cosmic ray sources should be characterized by spectra, dN/dE alpha E exp -(2.0-2.2), reflecting the strength of those shocks. This is expected from the 'standard leaky box' model of cosmic ray propagation in which the source spectra are harder than the observed spectra because higher energy particles have shorter residence times in the galactic magnetic fields. Furthermore, data on cosmic ray nucleons suggest that these sources might be surrounded by material. If the latter is true, such sources should be observable in gamma rays at energies beyond 1 GeV where the angular resolution of gamma-ray telescopes is optimized and the background is significantly reduced. For identified sources, the source location accuracy can be shown to improve with increasing energy in spite of the decreasing statistics, as long as the gamma-ray spectrum is harder than dN/dE alpha E exp -gamma. A Monte Carlo model is used to predict the photon spectra which would be expected from cosmic ray sources under varying assumptions about the strength of the shocks in the acceleration region.

  10. A Comprehensive Approach to Gamma-Ray Source Identification in the GLAST-LAT Era

    SciTech Connect

    Caraveo, Patrizia A.; Reimer, Olaf; /Stanford U., HEPL /KIPAC, Menlo Park

    2007-11-13

    Unveiling the nature of a vast number of unidentified sources is the most compelling problem facing today's high-energy (MeV-to-GeV) gamma-ray astronomy. However, unidentified sources are not peculiar to high-energy gamma-ray astronomy, they have been an ever-present phenomenon in astronomy. Indeed, every time a new astronomical window was opened, astronomers found sources they were not able to identify, i.e. to associate with previously known objects. This can happen either because such sources belong to a genuinely new (thus unknown) class or because their positions are not known accurately enough to allow for an unambiguous association between the newly found emitter and a known object. Thus, the lack of identification is frequently ascribed to poor angular resolution. Being unidentified, however, is a 'temporary' status: sooner or later better tools will allow the source identification, i.e. either its classification within a given class of astronomical objects or its recognition as belonging to a new class. Owing to the intrinsic limitations of gamma-ray detection technique, however, the instruments' angular resolution has not yet reached the minimum level required to permit the transition from the unidentified limbo to the paradise of known objects, thus creating a continuing unidentified high-energy gamma-ray source problem. Different approaches towards source identification have been pursued in the past. Here we will review the state of the art as well as the strategies devised for the GLAST era.

  11. Gamma-gamma colliders

    SciTech Connect

    Kim, K.J.; Sessler, A.

    1996-06-01

    Gamma-gamma colliders make intense beams of gamma rays and have them collide so as to make elementary particles. The authors show, in this article, that constructing a gamma-gamma collider as an add-on to an electron-positron linear collider is possible with present technology and that it does not require much additional cost. Furthermore, they show that the resulting capability is very interesting from a particle physics point of view. An overview of a linear collider, with a second interaction region devoted to {gamma}{gamma} collisions is shown.

  12. Spectral analysis of shielded gamma ray sources using precalculated library data

    NASA Astrophysics Data System (ADS)

    Holmes, Thomas Wesley; Gardner, Robin P.

    2015-11-01

    In this work, an approach has been developed for determining the intensity of a shielded source by first determining the thicknesses of three different shielding materials from a passively collected gamma-ray spectrum by making comparisons with predetermined shielded spectra. These evaluations are dependent on the accuracy and validity of the predetermined library spectra which were created by changing the thicknesses of the three chosen materials lead, aluminum and wood that are used to simulate any actual shielding. Each of the spectra produced was generated using MCNP5 with a sufficiently large number of histories to ensure a low relative error at each channel. The materials were held in the same respective order from source to detector, where each material consisted of three individual thicknesses and a null condition. This then produced two separate data sets of 27 total shielding material situations and subsequent predetermined libraries that were created for each radionuclide source used. The technique used to calculate the thicknesses of the materials implements a Levenberg-Marquardt nonlinear search that employs a tri-linear interpolation with the respective predetermined libraries within each channel for the supplied input unknown spectrum. Given that the nonlinear parameters require an initial guess for the calculations, the approach demonstrates first that when the correct values are input, the correct thicknesses are found. It then demonstrates that when multiple trials of random values are input for each of the nonlinear parameters, the average of the calculated solutions that successfully converges also produced the correct thicknesses. Under situations with sufficient information known about the detection situation at hand, the method was shown to behave in a manner that produces reasonable results and can serve as a good preliminary solution. This technique has the capability to be used in a variety of full spectrum inverse analysis problems

  13. 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.

  14. Statistical Measurement of the Gamma-Ray Source-count Distribution as a Function of Energy

    NASA Astrophysics Data System (ADS)

    Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza; Fornengo, Nicolao; Regis, Marco

    2016-08-01

    Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. We employ the 1-point probability distribution function of six years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy. To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 and 171 GeV. It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of ˜50 GeV. The index below the break is between 1.95 and 2.0. For higher energies, a simple power-law fits the data, with an index of {2.2}-0.3+0.7 in the energy band between 50 and 171 GeV. Upper limits on further possible breaks as well as the angular power of unresolved sources are derived. We find that point-source populations probed by this method can explain {83}-13+7% ({81}-19+52%) of the extragalactic gamma-ray background between 1.04 and 1.99 GeV (50 and 171 GeV). The method has excellent capabilities for constraining the gamma-ray luminosity function and the spectra of unresolved blazars.

  15. Brazilian gamma-neutron dosemeter: response to 241AmBe and 252Cf neutron sources.

    PubMed

    Souto, E B; Campos, L L

    2011-03-01

    With the aim of improving the monitoring of workers potentially exposed to neutron radiation in Brazil, the IPEN/CNEN-SP in association with PRO-RAD designed and developed a passive individual gamma-neutron mixed-field dosemeter calibrated to be used to (241)AmBe sources. To verify the dosimetry system response to different neutron spectra, prototypes were irradiated with a (252)Cf source and evaluated using the dose-calculation algorithm developed for (241)AmBe sources.

  16. High-power laser-driven source of ultra-short X-ray and gamma-ray pulses

    NASA Astrophysics Data System (ADS)

    Esirkepov, T. Zh.; Bulanov, S. V.; Zhidkov, A. G.; Pirozhkov, A. S.; Kando, M.

    2009-11-01

    A novel ultra-bright high-intensity source of X-ray and gamma radiation is suggested. It is based on the double Doppler effect, where a relativistic flying mirror reflects a counter-propagating electromagnetic radiation causing its frequency multiplication and intensification, and on the inverse double Doppler effect, where the mirror acquires energy from an ultra-intense co-propagating electromagnetic wave. The role of the flying mirror is played by a high-density thin plasma slab accelerating in the radiation pressure dominant regime. Frequencies of high harmonics generated at the flying mirror by a relativistically strong counter-propagating radiation udergo multiplication with the same factor as the fundamental frequency of the reflected radiation, approximately equal to the quadruple of the square of the mirror Lorentz factor.

  17. Development of a High-Average-Power Compton Gamma Source for Lepton Colliders

    SciTech Connect

    Pogorelsky, Igor; Polyanskiy, Mikhail N.; Yakimenko, Vitaliy; Platonenko, Viktor T.

    2009-01-22

    Gamma-({gamma}{sup -}) ray beams of high average power and peak brightness are of demand for a number of applications in high-energy physics, material processing, medicine, etc. One of such examples is gamma conversion into polarized positrons and muons that is under consideration for projected lepton colliders. A {gamma}-source based on the Compton backscattering from the relativistic electron beam is a promising candidate for this application. Our approach to the high-repetition {gamma}-source assumes placing the Compton interaction point inside a CO{sub 2} laser cavity. A laser pulse interacts with periodical electron bunches on each round-trip inside the laser cavity producing the corresponding train of {gamma}-pulses. The round-trip optical losses can be compensated by amplification in the active laser medium. The major challenge for this approach is in maintaining stable amplification rate for a picosecond CO{sub 2}-laser pulse during multiple resonator round-trips without significant deterioration of its temporal and transverse profiles. Addressing this task, we elaborated on a computer code that allows identifying the directions and priorities in the development of such a multi-pass picosecond CO{sub 2} laser. Proof-of-principle experiments help to verify the model and show the viability of the concept. In these tests we demonstrated extended trains of picosecond CO{sub 2} laser pulses circulating inside the cavity that incorporates the Compton interaction point.

  18. Utilization of recycled neutron source to teach prompt gamma analysis activation-PGNA

    NASA Astrophysics Data System (ADS)

    Delgado-Correal, Camilo; Munera, Hector

    2008-03-01

    Neutron activation analysis based on prompt gamma ray emission has significantly developed during the past twenty years. The technique is particularly suited for the identification of low atomic number elements, as nitrogen that is a main component of drugs and explosives. Identification of these substances is important in the context of humanitarian demining, and in the control of illicit traffic of drugs and explosives. As a good example of recycling of radioactive sources, a ^241Am-Be neutron source emitting 10^7neutron/s, that was not longer in use for other purposes at Ingeominas, was used to build a neutron irradiator that can be used to teach prompt gamma ray analysis, and other nuclear techniques. We irradiated individual samples, each about 4 gram, of three different elements: nitrogen in urea, silicon in milled rock, and cadmium in cadmium oxide. The prompt gamma rays emitted in the nuclear reactions ^112Cd (neutron,gamma) ^113Cd, ^28Si (neutron,gamma) ^29Si and ^14N (neutron,gamma) ^15N were identified using a well-type NaI (Tl) detector, connected to a multi-channel analyzer.

  19. 10 CFR 35.600 - Use of a sealed source in a remote afterloader unit, teletherapy unit, or gamma stereotactic...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Photon Emitting Remote Afterloader Units, Teletherapy Units, and..., teletherapy unit, or gamma stereotactic radiosurgery unit. A licensee shall use sealed sources in...

  20. 10 CFR 35.600 - Use of a sealed source in a remote afterloader unit, teletherapy unit, or gamma stereotactic...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Photon Emitting Remote Afterloader Units, Teletherapy Units, and..., teletherapy unit, or gamma stereotactic radiosurgery unit. A licensee shall use sealed sources in...

  1. 10 CFR 35.600 - Use of a sealed source in a remote afterloader unit, teletherapy unit, or gamma stereotactic...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Photon Emitting Remote Afterloader Units, Teletherapy Units, and..., teletherapy unit, or gamma stereotactic radiosurgery unit. A licensee shall use sealed sources in...

  2. 10 CFR 35.600 - Use of a sealed source in a remote afterloader unit, teletherapy unit, or gamma stereotactic...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Photon Emitting Remote Afterloader Units, Teletherapy Units, and..., teletherapy unit, or gamma stereotactic radiosurgery unit. A licensee shall use sealed sources in...

  3. 10 CFR 35.600 - Use of a sealed source in a remote afterloader unit, teletherapy unit, or gamma stereotactic...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Photon Emitting Remote Afterloader Units, Teletherapy Units, and..., teletherapy unit, or gamma stereotactic radiosurgery unit. A licensee shall use sealed sources in...

  4. The Distribution of Cosmic-Ray Sources in the Galaxy, Gamma-Rays and the Gradient in the CO-to-H2 Relation

    NASA Technical Reports Server (NTRS)

    Strong, A. W.; Moskalenko, I. V.; Reimer, O.; Diehl, S.; Diehl, R.

    2004-01-01

    We present a solution to the apparent discrepancy between the radial gradient in the diffuse Galactic gamma-ray emissivity and the distribution of supernova remnants, believed to be the sources of cosmic rays. Recent determinations of the pulsar distribution have made the discrepancy even more apparent. The problem is shown to be plausibly solved by a variation in the Wco-to-N(H2) scaling factor. If this factor increases by a factor of 5-10 from the inner to the outer Galaxy, as expected from the Galactic metallicity gradient and supported by other evidence, we show that the source distribution required to match the radial gradient of gamma-rays can be reconciled with the distribution of supernova remnants as traced by current studies of pulsars. The resulting model fits the EGRET gamma-ray profiles extremely well in longitude, and reproduces the mid-latitude inner Galaxy intensities better than previous models.

  5. A new population of very high energy gamma-ray sources in the Milky Way.

    PubMed

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

    2005-03-25

    Very high energy gamma-rays probe the long-standing mystery of the origin of cosmic rays. Produced in the interactions of accelerated particles in astrophysical objects, they can be used to image cosmic particle accelerators. A first sensitive survey of the inner part of the Milky Way with the High Energy Stereoscopic System (HESS) reveals a population of eight previously unknown firmly detected sources of very high energy gamma-rays. At least two have no known radio or x-ray counterpart and may be representative of a new class of "dark" nucleonic cosmic ray sources.

  6. Magnetometer Application for GAMMA-400 Telescope Switching into the Mode with Increased Low Energy Charged Particles Intensity Registration

    NASA Astrophysics Data System (ADS)

    Khyzhniak, E. V.; Arkhangelskaja, I. V.; Chasovikov, E. N.; Arkhangelskiy, A. I.; Topchiev, N. P.

    GAMMA-400 is an international project of a high apogee orbital astrophysical observatory for studying the characteristics of high-energy gamma-emission, electrons/positrons and light nuclei fluxes. The energy range for γ-rays and electrons/positrons registration in the main aperture is from ∼0.1 GeV to ∼3.0 TeV. Also, this aperture allows high energy light nuclei fluxes characteristics investigation. Moreover, special aperture configuration allows registering of gamma-quanta, electrons (positrons) and light nuclei from the lateral directions too. The spacecraft GAMMA-400 orbit will be located in the Earth's magnetosphere and will pass front shock wave from magnetosphere interaction with the solar wind, turbulent-transition region, magnetopause and so on. During the satellite's movement through various Earth's magnetosphere regions its anticoincidence detectors will register high intensity fluxes of low energy charged particles captured by the magnetic field. The working area sections of GAMMA-400 detector systems used as anticoincidence shield are about 1 m2 each. The high intensity low energy charged particles flux influence on anticoincidence detectors should be taken into account during particle identification. This article presents a comparison between Earth's magnetosphere theoretical model according to SPENVIIS package and real data measured by detectors onboard THEMIS series satellites. The differences between these two datasets indicate that the calculated data are not sufficient to make short time predictions of variations of magnetic induction in the outer magnetosphere. A special trigger marker flag will be produced by GAMMA-400 counting and triggers signals formation system accordingly to the data of two onboard magnetometers. This flag's presence leads to special algorithms execution start, putting the plastic detectors into a dedicated working mode taking into account possible high count rates of external detector layers.

  7. Observations of discrete gamma ray sources with SAS-2. [compact sources centered on Crab nebula and Vela X supernova remnant

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    Compact gamma ray sources centered on the Crab nebula and the Vela X supernova remnant are considered. An excess in the galactic radiation was observed in both regions. Data indicate that a large fraction of this flux is pulsed. The excess from the Vela region could reflect either a large-scale galactic feature, such as a superposition of spiral arm segments, or it could be associated with the Vela supernova remnant. Low-energy gamma ray bursts were observed in the SAS-2 anticoincidence shielding.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  9. Projection of needs for gamma radiation sources and other radioisotopes and assessment of alternatives for providing radiation sources

    SciTech Connect

    Ross, W.A.; Jensen, G.A.; Clark, L.L.; Eakin, D.E.; Jarrett, J.H.; Katayama, Y.B.; McKee, R.W.; Morgan, L.G.; Nealey, S.M.; Platt, A.M.; Tingey, G.L.

    1989-06-01

    Pacific Northwest Laboratory reviewed the projected uses and demands for a variety of nuclear byproducts. Because the major large-scale near-term demand is for gamma irradiation sources, this report concentrates on the needs for gamma sources and evaluates the options for providing the needed material. Projections of possible growth in the irradiation treatment industry indicate that there will be a need for 180 to 320 MCi of /sup 60/Co (including /sup 137/Cs equivalent) in service in the year 2000. The largest current and projected use of gamma irradiation is for the sterilization of medical devices and disposable medical supplies. Currently, 40% of US disposable medical products are treated by irradiation, and within 10 years it is expected that 90% will be treated in this manner. Irradiation treatment of food for destruction of pathogens or parasites, disinfestation, or extension of allowable storage periods is estimated to require an active inventory of 75 MCi of /sup 60/Co-equivalent gamma source in about a decade. 90 refs., 7 figs., 25 tabs.

  10. On the high-energy gamma-ray signature of cosmic-ray sources

    NASA Technical Reports Server (NTRS)

    Ormes, J. F.; Ozel, M. E.; Morris, D. J.

    1988-01-01

    Monte Carlo simulations of the gamma-ray emission from hypothetical cosmic-ray sources are performed. Sources which might correspond to acceleration by supernova shocks in 'average' interstellar conditions and deep within giant molecular clouds are considered. The consequences of dropping the common assumption that the cosmic-ray spectrum at the sources is the same as that observed at earth are examined. Spectral effects which can be related to the depth of the material shroud and the population of accelerated particles are explored using these simulations and are described. The results are compared with the COS B catalog of gamma-ray sources, and the implications for the underlying particle populations and source mechanisms are discussed.

  11. SWIFT X-RAY TELESCOPE MONITORING OF FERMI-LAT GAMMA-RAY SOURCES OF INTEREST

    SciTech Connect

    Stroh, Michael C.; Falcone, Abe D.

    2013-08-15

    We describe a long-term Swift monitoring program of Fermi gamma-ray sources, particularly the 23 gamma-ray ''sources of interest''.We present a systematic analysis of the Swift X-Ray Telescope light curves and hardness ratios of these sources, and we calculate excess variability. We present data for the time interval of 2004 December 22 through 2012 August 31. We describe the analysis methods used to produce these data products, and we discuss the availability of these data in an online repository, which continues to grow from more data on these sources and from a growing list of additional sources. This database should be of use to the broad astronomical community for long-term studies of the variability of these objects and for inclusion in multiwavelength studies.

  12. Preview of the BATSE Earth Occultation Catalog of Low Energy Gamma Ray Sources

    NASA Technical Reports Server (NTRS)

    Harmon, B. A.; Wilson, C. A.; Fishman, G. J.; McCollough, M. L.; Robinson, C. R.; Sahi, M.; Paciesas, W. S.; Zhang, S. N.

    1999-01-01

    The Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma Ray Observatory (CGRO) has been detecting and monitoring point sources in the high energy sky since 1991. Although BATSE is best known for gamma ray bursts, it also monitors the sky for longer-lived sources of radiation. Using the Earth occultation technique to extract flux information, a catalog is being prepared of about 150 sources potential emission in the large area detectors (20-1000 keV). The catalog will contain light curves, representative spectra, and parametric data for black hole and neutron star binaries, active galaxies, and super-nova remnants. In this preview, we present light curves for persistent and transient sources, and also show examples of what type of information can be obtained from the BATSE Earth occultation database. Options for making the data easily accessible as an "on line" WWW document are being explored.

  13. A Bibliography of Sources for Intensive English Program Administration.

    ERIC Educational Resources Information Center

    Gawienowski, Mary F.

    The bibliography presents over 100 citations of papers, articles, and reports on diverse aspects of the administration of intensive English language programs. The works are produced by both individuals and organizations. Citations include basic bibliographic information and a brief annotation. Topics addressed include: specific program profiles…

  14. 3-D localization of gamma ray sources with coded apertures for medical applications

    NASA Astrophysics Data System (ADS)

    Kaissas, I.; Papadimitropoulos, C.; Karafasoulis, K.; Potiriadis, C.; Lambropoulos, C. P.

    2015-09-01

    Several small gamma cameras for radioguided surgery using CdTe or CdZnTe have parallel or pinhole collimators. Coded aperture imaging is a well-known method for gamma ray source directional identification, applied in astrophysics mainly. The increase in efficiency due to the substitution of the collimators by the coded masks renders the method attractive for gamma probes used in radioguided surgery. We have constructed and operationally verified a setup consisting of two CdTe gamma cameras with Modified Uniform Redundant Array (MURA) coded aperture masks of rank 7 and 19 and a video camera. The 3-D position of point-like radioactive sources is estimated via triangulation using decoded images acquired by the gamma cameras. We have also developed code for both fast and detailed simulations and we have verified the agreement between experimental results and simulations. In this paper we present a simulation study for the spatial localization of two point sources using coded aperture masks with rank 7 and 19.

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

    SciTech Connect

    Hochmuth, Kathrin A.; Sigl, Guenter

    2007-12-15

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

  16. Solar wind interaction with the Reiner Gamma crustal magnetic anomaly: Connecting source magnetization to surface weathering

    NASA Astrophysics Data System (ADS)

    Poppe, Andrew R.; Fatemi, Shahab; Garrick-Bethell, Ian; Hemingway, Doug; Holmström, Mats

    2016-03-01

    Remanent magnetization has long been known to exist in the lunar crust, yet both the detailed topology and ultimate origin(s) of these fields remains uncertain. Some crustal magnetic fields coincide with surface albedo anomalies, known as lunar swirls, which are thought to be formed by differential surface weathering of the regolith underlying crustal fields due to deflection of incident solar wind protons. Here, we present results from a three-dimensional, self-consistent, plasma hybrid model of the solar wind interaction with two different possible source magnetizations for the Reiner Gamma anomaly. We characterize the plasma interaction with these fields and the resulting spatial distribution of charged-particle weathering of the surface and compare these results to optical albedo measurements of Reiner Gamma. The model results constrain the proposed source magnetizations for Reiner Gamma and suggest that vertical crustal magnetic fields are required to produce the observed "dark lanes."

  17. High intensity muon beam source for neutrino beam experiments

    NASA Astrophysics Data System (ADS)

    Kamal Sayed, Hisham

    2015-09-01

    High intensity muon beams are essential for Muon accelerators like Neutrino Factories and Muon Colliders. In this study we report on a global optimization of the muon beam production and capture based on end-to-end simulations of the Muon Front End. The study includes the pion beam production target geometry, capture field profile, and forming muon beam into microbunches for further acceleration. The interplay between the transverse and longitudinal beam dynamics during the capture and transport of muon beam is evaluated and discussed. The goal of the optimization is to provide a set of design parameters that delivers high intensity muon beam that could be fit within the acceptance of a muon beam accelerator.

  18. Precision X-Band Linac Technologies for Nuclear Photonics Gamma-Ray Sources

    SciTech Connect

    Hartemann, F V; Albert, F; Anderson, S G; Bayramian, A J; Cross, R R; Ebbers, C A; Gibson, D J; Houck, T L; Marsh, R A; Messerly, M J; Siders, C W; McNabb, D P; Barty, C J; Adolphsen, C E; Chu, T S; Jongewaard, E N; Tantawi, S G; Vlieks, A E; Wang, F; Wang, J W; Raubenheimer, T O; Ighigeanu, D; Toma, M; Cutoiu, D

    2011-08-31

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

  19. The Third EGRET Catalog of High-Energy Gamma-Ray Sources

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.; Bertsch, D. L.; Bloom, S. D.; Chen, A. W.; Deines-Jones, P.; Esposito, J. A.; Fichtel, C. E.; Friedlander, D. P.; Hunter, S. D.; McDonald, L. M.; Sreekumar, P.; Thompson, D. J.; Jones, B. B.; Lin, Y. C.; Michelson, P. F.; Nolan, P. L.; Tompkins, W. F.; Kanbach, G.; Mayer-Hasselwander, H. A.; Muecke, A.

    1998-01-01

    The third catalog of high-energy gamma-ray sources detected by the EGRET telescope on the Compton Gamma Ray Observatory includes data from 1991 April 22 to 1995 October 3 (Cycles 1, 2, 3, and 4 of the mission). In addition to including more data than the second EGRET catalog (Thompson et al. 1995) and its supplement (Thompson et al. 1996), this catalog uses completely reprocessed data (to correct a number of mostly minimal errors and problems). The 271 sources (E greater than 100 MeV) in the catalog include the single 1991 solar flare bright enough to be detected as a source, the Large Magellanic Cloud, five pulsars, one probable radio galaxy detection (Cen A), and 66 high-confidence identifications of blazars (BL Lac objects, flat-spectrum radio quasars, or unidentified flat-spectrum radio sources). In addition, 27 lower-confidence potential blazar identifications are noted. Finally, the catalog contains 170 sources not yet identified firmly with known objects, although potential identifications have been suggested for a number of those. A figure is presented that gives approximate upper limits for gamma-ray sources at any point in the sky, as well as information about sources listed in the second catalog and its supplement which do not appear in this catalog.

  20. The Third EGRET Catalog of High-Energy Gamma-Ray Sources

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.; Bertsch, D. L.; Bloom, S. D.; Chen, A. W.; Deines-Jones, P.; Esposito, J. A.; Fichtel, C. E.; Friedlander, D. P.; Hunter, S. D.; McDonald, L. M.; Sreekumar, P.; Thompson, D. J.; Jones, B. B.; Lin, Y. C.; Michelson, P. F.; Nolan, P. L.; Tompkins, W. F.; Kanbach, G.; Mayer-Hasselwander, A.; Muecke, A.

    1998-01-01

    The third catalog of high-energy gamma-ray sources detected by the EGRET telescope on the Compton Gamma Ray Observatory includes data from 1991 April 22 to 1995 October 3 (Cycles 1, 2, 3, and 4 of the mission). In addition to including more data than the second EGRET catalog and its supplement, this catalog uses completely reprocessed data (to correct a number of mostly minimal errors and problems). The 271 sources (E greater than 100 MeV) in the catalog include the single 1991 solar flare bright enough to be detected as a source, the Large Magellanic Cloud, five pulsars, one probable radio galaxy detection (Cen A), and 66 high-confidence identifications of blazars (BL Lac objects, flat-spectrum radio quasars, or unidentified flat-spectrum radio sources). In addition, 27 lower-confidence potential blazar identifications are noted. Finally, the catalog contains 170 sources not yet identified firmly with known objects, although potential identifications have been suggested for a number of those. A figure is presented that gives approximate upper limits for gamma-ray sources at any point in the sky, as well as information about sources listed in the second catalog and its supplement which do not appear in this catalog.

  1. AGILE detection of enhanced gamma-ray activity from a new unidentified source at high Galactic latitude, AGLJ0917+1511

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    AGILE is detecting intense gamma-ray emission above 100 MeV from an unidentified source, AGLJ0917+1511, at Galactic coordinates (l,b)=(214.99, 39.00) deg (R.A., Dec.= 139.27, 15.196 deg, J2000), with a statistical 95% c.l. elliptical error region with major and minor axes of 0.58 deg and 0.47 deg, respectively.

  2. 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.

  3. [Technical features and roles of cobalt-57 flood sources for daily quality control of gamma cameras].

    PubMed

    Wagatsuma, Kei; Miwa, Kenta; Akimoto, Kenta; Tsushima, Hiroyuki; Miyaji, Noriaki; Umeda, Takuro; Murata, Taisuke; Takiguchi, Tomohiro; Koizumi, Mitsuru

    2014-02-01

    Quality control (QC) detects changes in the performance of gamma cameras that could adversely affect interpretations of clinical studies. We used plate and sheet (57)Co flood sources to measure extrinsic uniformity during daily QC. Each source, when placed on the top of a collimated detector, allowed the acquisition of uniform images from both detectors, thus reducing the amount of time needed to perform daily QC. No serious problems with the gamma camera system were revealed by visual checks, and changes in detector sensitivity were rapidly determined by observing daily variations in the measured values of extrinsic uniformity. Furthermore, (57)Co flood sources confer advantages in that they shorten the time required for preparation of flood sources and reduce the consequent exposure of medical staff to radiation.

  4. Mapping Correlation of Two Point Sources in the Gamma-Ray Sky

    SciTech Connect

    Gibson, Alexander

    2015-08-20

    The Fermi Gamma-Ray Space Telescope has been taking data on high energy photons or γ rays since June 11th, 2008, and people have been cataloging and profiling point sources of these γ rays ever since. After roughly one year of being in operation over 1400 sources were cataloged. Now, in 2015 we have 3033 sources cataloged. With the increasing amount of sources it’s important to think about the limitations of likelihood analysis for highly correlated sources. In this paper I will present the problems of using likelihood analysis for sources that are highly correlated as well as show under what circumstances sources can be considered highly correlated. Dark matter over densities may show up as a point source, so it is a necessary step to learn how the two signals will interact to allow for a proper search for dark matter.

  5. MEG sensor and source measures of visually induced gamma-band oscillations are highly reliable.

    PubMed

    Tan, H-R M; Gross, J; Uhlhaas, P J

    2016-08-15

    High frequency brain oscillations are associated with numerous cognitive and behavioral processes. Non-invasive measurements using electro-/magnetoencephalography (EEG/MEG) have revealed that high frequency neural signals are heritable and manifest changes with age as well as in neuropsychiatric illnesses. Despite the extensive use of EEG/MEG-measured neural oscillations in basic and clinical research, studies demonstrating test-retest reliability of power and frequency measures of neural signals remain scarce. Here, we evaluated the test-retest reliability of visually induced gamma (30-100Hz) oscillations derived from sensor and source signals acquired over two MEG sessions. The study required participants (N=13) to detect the randomly occurring stimulus acceleration while viewing a moving concentric grating. Sensor and source MEG measures of gamma-band activity yielded comparably strong reliability (average intraclass correlation, ICC=0.861). Peak stimulus-induced gamma frequency (53-72Hz) yielded the highest measures of stability (ICCsensor=0.940; ICCsource=0.966) followed by spectral signal change (ICCsensor=0.890; ICCsource=0.893) and peak frequency bandwidth (ICCsensor=0.856; ICCsource=0.622). Furthermore, source-reconstruction significantly improved signal-to-noise for spectral amplitude of gamma activity compared to sensor estimates. Our assessments highlight that both sensor and source derived estimates of visually induced gamma-band oscillations from MEG signals are characterized by high test-retest reliability, with source derived oscillatory measures conferring an improvement in the stability of peak-frequency estimates. Importantly, our finding of high test-retest reliability supports the feasibility of pharma-MEG studies and longitudinal aging or clinical studies. PMID:27153980

  6. MEG sensor and source measures of visually induced gamma-band oscillations are highly reliable.

    PubMed

    Tan, H-R M; Gross, J; Uhlhaas, P J

    2016-08-15

    High frequency brain oscillations are associated with numerous cognitive and behavioral processes. Non-invasive measurements using electro-/magnetoencephalography (EEG/MEG) have revealed that high frequency neural signals are heritable and manifest changes with age as well as in neuropsychiatric illnesses. Despite the extensive use of EEG/MEG-measured neural oscillations in basic and clinical research, studies demonstrating test-retest reliability of power and frequency measures of neural signals remain scarce. Here, we evaluated the test-retest reliability of visually induced gamma (30-100Hz) oscillations derived from sensor and source signals acquired over two MEG sessions. The study required participants (N=13) to detect the randomly occurring stimulus acceleration while viewing a moving concentric grating. Sensor and source MEG measures of gamma-band activity yielded comparably strong reliability (average intraclass correlation, ICC=0.861). Peak stimulus-induced gamma frequency (53-72Hz) yielded the highest measures of stability (ICCsensor=0.940; ICCsource=0.966) followed by spectral signal change (ICCsensor=0.890; ICCsource=0.893) and peak frequency bandwidth (ICCsensor=0.856; ICCsource=0.622). Furthermore, source-reconstruction significantly improved signal-to-noise for spectral amplitude of gamma activity compared to sensor estimates. Our assessments highlight that both sensor and source derived estimates of visually induced gamma-band oscillations from MEG signals are characterized by high test-retest reliability, with source derived oscillatory measures conferring an improvement in the stability of peak-frequency estimates. Importantly, our finding of high test-retest reliability supports the feasibility of pharma-MEG studies and longitudinal aging or clinical studies.

  7. Comptonization of diffuse ambient radiation by a relativistic jet: The source of gamma rays from blazars?

    NASA Technical Reports Server (NTRS)

    Sikora, Marek; Begelman, Mitchell C.; Rees, Martin J.

    1994-01-01

    Recent Energy Gamma Ray Experiment Telescope (EGRET) observations of blazars have revealed strong, variable gamma-ray fluxes with no signatures of gamma-ray absorption by pair production. This radiation probably originates from the inner parts of relativistic jets which are aimed nearly toward us. On sub-parsec scales, the jet will be pervaded by radiation from the broad-line region, as well as by photons from the central continuum source (some of which will be scattered by thermal plasma). In a frame moving with the relativistic outflow, the energy of this ambient radiation would be enhanced. This radiation would be Comptonized by both cold and relativistic electrons in the jet, yielding (in the observer's frame) a collimated beam of X-rays and gamma rays. On the assumption that this process dominates self-Comptonization of synchrotron radiation, we develop a self-consistent model for variable gamma-ray emission, involving a single population of relativistic electrons accelerated by a disturbance in the jet. The spectral break between the X-ray and gamma-ray band, observed in 3C 279 and deduced for other blazars, results from inefficient radiative cooling of lower energy electrons. The existence of such a break strongly favors a model involving Comptonization of an external radiation field over a synchrotron self-Compton model. We derive constraints on such model parameters as the location and speed of the source, its dimensions and internal physical parameters, the maximum photon energies produced in the source, and the density and distribution of ambient radiation. Finally, we discuss how observations might discriminate between our model and alternative ones invoking Comptonization of ambient radiation.

  8. Ammonia sources and sinks in an intensively managed grassland canopy

    NASA Astrophysics Data System (ADS)

    David, M.; Loubet, B.; Cellier, P.; Mattsson, M.; Schjoerring, J. K.; Nemitz, E.; Roche, R.; Riedo, M.; Sutton, M. A.

    2009-09-01

    Grasslands represent canopies with a complex structure where sources and sinks of ammonia (NH3) may coexist at the plant level. Moreover, management practices such as mowing, hay production and grazing may change the composition of the sward and hence the source-sink relationship at the canopy level as well as the interaction with the atmosphere. There is therefore a need to understand the exchange of ammonia between grasslands and the atmosphere better, especially regarding the location and magnitude of sources and sinks. Fluxes of atmospheric NH3 within a grassland canopy were assessed in the field and under controlled conditions using a dynamic chamber technique (cuvette). These cuvette measurements were combined with extraction techniques to estimate the ammonium (NH4+) concentration and the pH of a given part of the plant or soil, leading to an estimated ammonia compensation point (Cp). The combination of the cuvette and the extraction techniques was used to identify the potential sources and sinks of NH3 within the different compartments of the grassland: the soil, the litter or senescent "litter leaves", and the functioning "green leaves". A set of six field experiments and six laboratory experiments were performed in which the different compartments were either added or removed from the cuvettes. The results show that the cuvette measurements agree with the extraction technique in ranking the strength of compartment sources. It suggests that in the studied grassland the green leaves were mostly a sink for NH3 with a compensation point around 0.1-0.4 μg m-3 and an NH3 flux of 6 to 7 ng m-2 s-1. Cutting of the grass did not increase the NH3 fluxes of the green leaves. The litter was found to be the largest source of NH3 in the canopy, with a Cp of up to 1000 μg m-3 NH3 and an NH3 flux up to 90 ng m-2 s-1. The litter was found to be a much smaller NH3 source when dried (Cp=160 μg m-3 and FNH3=35 ng m-2 s-1 NH3). Moreover emissions from the litter were found

  9. SAS-2 observations of high energy gamma rays from discrete sources

    NASA Technical Reports Server (NTRS)

    Kniffen, D. A.; Fichtel, C. E.; Hartman, R. C.; Lamb, R. C.; Thompson, D. J.

    1977-01-01

    The SAS-2 identified six localized high energy (greater than 35 MeV) gamma ray sources. Four of these are the radio pulsars, PSR 0531+21, PSR 0833-45, PSR 1818-04, and PSR 1717-46 discovered in a search of 75 radio pulsars. The fact that only one of these is observed in X-rays, and the significant differences in pulse profiles in the gamma ray and radio observations, leads to the speculation that different mechanisms are involved.

  10. An Analysis of Gamma-ray Burst Time Profiles from the Burst and Transient Source Experiment

    NASA Technical Reports Server (NTRS)

    Lestrade, John Patrick

    1996-01-01

    This proposal requested funding to measure the durations of gamma-ray bursts (GRB) in the 4B catalog as well as to study the structure of GRB time profiles returned by the Burst And Transient Source Experiment (BATSE) on board the Compton Gamma-Ray Observatory. The duration (T90) was to be measured using the same techniques and algorithms developed by the principal investigator for the 3B data. The profile structure studies fall into the two categories of variability and fractal analyses.

  11. A Comparison of Simple Algorithms for Gamma-ray Spectrometers in Radioactive Source Search Applications

    SciTech Connect

    Jarman, Kenneth D.; Runkle, Robert C.; Anderson, Kevin K.; Pfund, David M.

    2008-03-01

    Large variation in time-dependent ambient gamma-ray radiation challenges the search for radiation sources. A common strategy to reduce the effects of background variation is to raise detection thresholds, but at the price of reduced detection sensitivity. We present simple algorithms that both reduce background variation and maintain trip-wire detection sensitivity with gamma-ray spectrometry. The best-performing algorithms focus on the spectral shape over several energy bins using Spectral Comparison Ratios and dynamically predict background with the Kalman Filter.

  12. A future, intense source of negative hydrogen ions

    NASA Technical Reports Server (NTRS)

    Siefken, Hugh; Stein, Charles

    1994-01-01

    By directly heating lithium hydride in a vacuum, up to 18 micro-A/sq cm of negative hydrogen has been obtained from the crystal lattice. The amount of ion current extracted and analyzed is closely related to the temperature of the sample and to the rate at which the temperature is changed. The ion current appears to be emission limited and saturates with extraction voltage. For a fixed extraction voltage, the ion current could be maximized by placing a grid between the sample surface and the extraction electrode. Electrons accompanying the negative ions were removed by a magnetic trap. A Wein velocity filter was designed and built to provide definitive mass analysis of the extracted ion species. This technique when applied to other alkali hydrides may produce even higher intensity beams possessing low values of emittance.

  13. Intensity noise in long-wavelength superluminescent sources

    NASA Astrophysics Data System (ADS)

    Lee, Chung E.; Taylor, Henry F.

    1991-05-01

    Noise in broadband 1.3-micron superluminescent diodes (SLDs) is investigated experimentally, using a balanced detector arrangement to determine the excess noise factor as a function of photodetector current. Measurements were made in both the low-frequency 1/f regime (below 500 kHz) and the high-frequency quantum noise spectral region. The data at higher frequencies are in agreement with predictions of the quantum amplifier model, with values of the spontaneous emission coupling factor ranging from 1.2 to 1.9. It is also found that noise for one polarization of the light is uncorrelated with the noise for the orthogonal polarization over the 0-1 MHz frequency range. This implies that the 1/f noise is not related to carrier density (gain) fluctuations in the active region of the device. An integrated optic chip design to compensate for the excess intensity noise in fiber gyroscopes is proposed.

  14. A New Paradigm for Identification of Classes of High Energy Gamma-Ray Sources

    SciTech Connect

    Torres, D F; Reimer, O

    2005-04-08

    A large fraction of the expected number of source detections of the forthcoming observatory Gamma-ray Large Area Space Telescope (GLAST) will be initially unidentified. We argue that traditional methodological approaches to identify individual detections and/or populations of gamma-ray sources present procedural limitations. These limitations will hamper our ability to classify the populations lying in the anticipated dataset with the required degree of confidence, in particular for those for which no member has yet been detected convincingly with the predecessor experiment EGRET. Here we suggest a new paradigm for achieving the classification of gamma-ray source populations that is based on implementing an a priori protocol to search for theoretically-motivated candidates. It is essential that such paradigm will be defined before the data is unblinded, in order to protect the discovery potential of the sample. Key to the new procedure is a quantitative assessment of the confidence level by which new populations can be claimed to have been discovered. When needed, small number statistics is applied for population studies in gamma-ray astronomy. Although we refer here explicitly only to the case of GLAST, the scheme we present can certainly be adapted to other experiments confronted with a similar combination of problems.

  15. Selective source blocking for Gamma Knife radiosurgery of trigeminal neuralgia based on analytical dose modelling

    NASA Astrophysics Data System (ADS)

    Li, Kaile; Ma, Lijun

    2004-08-01

    We have developed an automatic critical region shielding (ACRS) algorithm for Gamma Knife radiosurgery of trigeminal neuralgia. The algorithm selectively blocks 201 Gamma Knife sources to minimize the dose to the brainstem while irradiating the root entry area of the trigeminal nerve with 70-90 Gy. An independent dose model was developed to implement the algorithm. The accuracy of the dose model was tested and validated via comparison with the Leksell GammaPlan (LGP) calculations. Agreements of 3% or 3 mm in isodose distributions were found for both single-shot and multiple-shot treatment plans. After the optimized blocking patterns are obtained via the independent dose model, they are imported into the LGP for final dose calculations and treatment planning analyses. We found that the use of a moderate number of source plugs (30-50 plugs) significantly lowered (~40%) the dose to the brainstem for trigeminal neuralgia treatments. Considering the small effort involved in using these plugs, we recommend source blocking for all trigeminal neuralgia treatments with Gamma Knife radiosurgery.

  16. Single-source gamma radiation procedures for improved calibration and measurements in porous media

    SciTech Connect

    Oostrom, M.; Hofstee, C.; Dane, H.; Lenhard, R.J.

    1998-08-01

    When dual-energy gamma radiation systems are employed for measurements in porous media, count rates from both sources are often used to compute parameter values. However, for several applications, the count rates of just one source are insufficient. These applications include the determination of volumetric liquid content values in two-liquid systems and salt concentration values in water-saturated porous media. Single-energy gamma radiation procedures for three applications are described in this paper. Through an error analysis, single-source procedures are shown to reduce the probable error in the determinations considerably. Example calculations and simple column experiments were conducted for each application to compare the performance of the new single-source and standard dual-source methods. In all cases, the single-source methods provided more reliable data than the traditional dual-source methods. In addition, a single-source calibration procedure is proposed to determine incident count rates indirectly. This procedure, which requires packing under saturated conditions, can be used in all single- and dual-source applications and yields accurate porosity and dry bulk density values.

  17. Temperature of thermal X-ray and. gamma. -ray sources

    SciTech Connect

    Gould, R.J.

    1982-07-01

    A framework is developed for the accurate determination of the temperature of a source, assuming that it is optically thin and emits a bremsstrahlung spectrum. The temperature can be measured from the shape of the spectral distribution, and an explicit relation is derived for the temperature in terms of this slope and a sum of correction terms to the limiting form of the bremsstrahlung formula. The corrections can be evaluted easily in terms of simple, though accurate, asymptotic formulae and are due to (i) correction to an asymptotic form of a modified Bessel function, (ii) a lowest-order correction to the Born approximation to the bremsstrahlung cross-section, (iii) relativistic corrections to the plasma electron energy distribution and to the nonrelativistic limit to the electron-ion bremstrahlung cross section, (iv) the contribution from electron-electron bremsstrahlung. For the case where there is a distribution of temperatures in the plasma, an additional correction is derived in terms of the rms variation in the plasma temperature. Some corresponding results for highly relativistic plasmas are given. The intermediate domain (kTapprox.m/sub e/c/sup 2/) is also discussed, and a rough general formula is suggested.

  18. The source altitude, electric current, and intrinsic brightness of terrestrial gamma ray flashes

    NASA Astrophysics Data System (ADS)

    Cummer, Steven A.; Briggs, Michael S.; Dwyer, Joseph R.; Xiong, Shaolin; Connaughton, Valerie; Fishman, Gerald J.; Lu, Gaopeng; Lyu, Fanchao; Solanki, Rahulkumar

    2014-12-01

    Many details of how thunderstorms generate terrestrial gamma ray flashes (TGFs) and other forms of high-energy radiation remain uncertain, including the basic question of where they are produced. We exploit the association of distinct low-frequency radio emissions with generation of terrestrial gamma ray flashes (TGFs) to directly measure for the first time the TGF source altitude. Analysis of two events reveals source altitudes of 11.8 ± 0.4 km and 11.9 ± 0.9 km. This places the source region in the interior of the thunderstorm between the two main charge layers and implies an intrinsic TGF brightness of approximately 1018 runaway electrons. The electric current in this nontraditional lightning process is found to be strong enough to drive nonlinear effects in the ionosphere, and in one case is comparable to the highest peak current lightning processes on the planet.

  19. Highlights from VERITAS on VHE gamma-ray sources in our Galaxy

    NASA Astrophysics Data System (ADS)

    Ong, Rene A.

    2014-05-01

    VERITAS is a major ground-based detector of very high energy (VHE, E >100 GeV) gamma rays and cosmic rays. VERITAS consists of an array of four 12 m-diameter atmospheric Cherenkov telescopes that has been fully operational since September 2007. VERITAS has detected many astrophysical sources of VHE gamma rays, including at least 17 VHE sources that are likely Galactic in origin. This paper describes some of the Galactic source highlights from VERITAS with an emphasis on those aspects that relate to the origin of cosmic rays. Specifically, topics include the VERITAS discovery of VHE emission from the Tycho and CTA 1 supernova remnants, the identification of HESS J0632+057 as a new VHE binary, a substantially improved view of the gamma-ray emission in the Cygnus OB1 region, and the recent remarkable discovery of VHE emission from the Crab pulsar. In 2009, VERITAS was upgraded by relocation of one of the telescopes, leading to a significant improvement in sensitivity. A program to further improve the performance of VERITAS, involving the upgrade of the telescope trigger systems and the telescope cameras, was completed in summer 2012. The upgrade has led to an improved sensitivity and a lower energy threshold for VERITAS, allowing it to perform deeper observations of known Galactic and extragalactic sources and to detect fainter and more distant sources.

  20. Turbulence generation through intense localized sources of energy

    NASA Astrophysics Data System (ADS)

    Maqui, Agustin; Donzis, Diego

    2015-11-01

    Mechanisms to generate turbulence in controlled conditions have been studied for nearly a century. Most common methods include passive and active grids with a focus on incompressible turbulence. However, little attention has been given to compressible flows, and even less to hypersonic flows, where phenomena such as thermal non-equilibrium can be present. Using intense energy from lasers, extreme molecule velocities can be generated from photo-dissociation. This creates strong localized changes in both the hydrodynamics and thermodynamics of the flow, which may perturb the flow in a way similar to an active grid to generate turbulence in hypersonic flows. A large database of direct numerical simulations (DNS) are used to study the feasibility of such an approach. An extensive analysis of single and two point statistics, as well as spectral dynamics is used to characterize the evolution of the flow towards realistic turbulence. Local measures of enstrophy and dissipation are studied to diagnose the main mechanisms for energy exchange. As commonly done in compressible flows, dilatational and solenoidal components are separated to understand the effect of acoustics on the development of turbulence. Further results for cases that assimilate laboratory conditions will be discussed. The authors gratefully acknowledge the support of AFOSR.

  1. Mapping correlation of a simulated dark matter source and a point source in the gamma-ray sky - Oral Presentation

    SciTech Connect

    Gibson, Alexander

    2015-08-23

    In my research, I analyzed how two gamma-ray source models interact with one another when optimizing to fit data. This is important because it becomes hard to distinguish between the two point sources when they are close together or looking at low energy photons. The reason for the first is obvious, the reason why they become harder to distinguish at lower photon energies is the resolving power of the Fermi Gamma-Ray Space Telescope gets worse at lower energies. When the two point sources are highly correlated (hard to distinguish between), we need to change our method of statistical analysis. What I did was show that highly correlated sources have larger uncertainties associated with them, caused by an optimizer not knowing which point source’s parameters to optimize. I also mapped out where their is high correlation for 2 different theoretical mass dark matter point sources so that people analyzing them in the future knew where they had to use more sophisticated statistical analysis.

  2. The Burst and Transient Source Experiment (BATSE) Earth Occultation Catalog of Low-Energy Gamma-Ray Sources

    NASA Technical Reports Server (NTRS)

    Harmon, B. A.; Wilson, C. A.; Fishman, G. J.; Connaughton, V.; Henze, W.; Paciesas, W. S.; Finger, M. H.; McCollough, M. L.; Sahi, M.; Peterson, B.

    2004-01-01

    The Burst and Transient Source Experiment (BATSE), aboard the Compton Gamma Ray Observatory (CGRO), provided a record of the low-energy gamma-ray sky (approx. 20-1000 keV) between 1991 April and 2000 May (9.1 yr). BATSE monitored the high-energy sky using the Earth occultation technique (EOT) for point sources whose emission extended for times on the order of the CGRO orbital period (approx. 92 min) or greater. Using the EOT to extract flux information, a catalog of sources using data from the BATSE Large Area Detectors has been prepared. The first part of the catalog consists of results from the all-sky monitoring of 58 sources, mostly Galactic, with intrinsic variability on timescales of hours to years. For these sources, we have included tables of flux and spectral data, and outburst times for transients. Light curves (or flux histories) have been placed on the World Wide Web. We then performed a deep sampling of these 58 objects, plus a selection of 121 more objects, combining data from the entire 9.1 yr BATSE data set. Source types considered were primarily accreting binaries, but a small number of representative active galaxies, X-ray-emitting stars, and supernova remnants were also included. The sample represents a compilation of sources monitored and/or discovered with BATSE and other high-energy instruments between 1991 and 2000, known sources taken from the HEAO 1 A-4 and Macomb & Gehrels catalogs. The deep sample results include definite detections of 83 objects and possible detections of 36 additional objects. The definite detections spanned three classes of sources: accreting black hole and neutron star binaries, active galaxies, and Supernova remnants. The average fluxes measured for the fourth class, the X-ray emitting stars, were below the confidence limit for definite detection.

  3. MeV Mono-Energetic Gamma Ray Compton Scattering Source R&D

    NASA Astrophysics Data System (ADS)

    Hartemann, Fred; Albert, Felicie; Anderson, Scott; Chu, Sam; Cross, Rick; Ebbers, Chris; Gibson, David; Messerly, Mike; Semenov, Vlad; Shverdin, Miro; Siders, Craig; McNabb, Dennis; Barty, Chris; Vlieks, Arnold; Tantawi, Sami

    2009-11-01

    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 γ-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.

  4. UNVEILING THE NATURE OF THE UNIDENTIFIED GAMMA-RAY SOURCES. III. GAMMA-RAY BLAZAR-LIKE COUNTERPARTS AT LOW RADIO FREQUENCIES

    SciTech Connect

    Massaro, F.; Funk, S.; D'Abrusco, R.; Paggi, A.; Giroletti, M.; Masetti, N.; Tosti, G.; Nori, M.

    2013-07-01

    About one-third of the {gamma}-ray sources listed in the second Fermi Large Area Telescope catalog (2FGL) have no firmly established counterpart at lower energies and so are classified as unidentified gamma-ray sources (UGSs). Here, we propose a new approach to find candidate counterparts for the UGSs based on the 325 MHz radio survey performed with the Westerbork Synthesis Radio Telescope in the northern hemisphere. First, we investigate the low-frequency radio properties of blazars, the largest known population of {gamma}-ray sources; then we search for sources with similar radio properties combining the information derived from the Westerbork Northern Sky Survey (WENSS) with those of the NRAO Very Large Array Sky Survey. We present a list of candidate counterparts for 32 UGSs with at least one counterpart in the WENSS. We also performed an extensive research in the literature to look for infrared and optical counterparts of the {gamma}-ray blazar candidates selected using the low-frequency radio observations to confirm their nature. On the basis of our multifrequency research, we identify 23 new {gamma}-ray blazar candidates out of the 32 UGSs investigated. Comparison with previous results on the UGSs is also presented. Finally, we speculate on the advantages of using low-frequency radio observations to associate UGSs and to search for {gamma}-ray pulsar candidates.

  5. Performance Characteristics Of An Intensity Modulated Advanced X-Ray Source (IMAXS) For Homeland Security Applications

    NASA Astrophysics Data System (ADS)

    Langeveld, Willem G. J.; Brown, Craig; Christensen, Phil. A.; Condron, Cathie; Hernandez, Michael; Ingle, Mike; Johnson, William A.; Owen, Roger D.; Ross, Randy; Schonberg, Russell G.

    2011-06-01

    X-ray cargo inspection systems for the detection and verification of threats and contraband must address stringent, competitive performance requirements. High x-ray intensity is needed to penetrate dense cargo, while low intensity is desirable to minimize the radiation footprint, i.e. the size of the controlled area, required shielding and the dose to personnel. In a collaborative effort between HESCO/PTSE Inc., XScell Corp., Stangenes Industries, Inc. and Rapiscan Laboratories, Inc., an Intensity Modulated Advanced X-ray Source (IMAXS) was designed and produced. Cargo inspection systems utilizing such a source have been projected to achieve up to 2 inches steel-equivalent greater penetration capability, while on average producing the same or smaller radiation footprint as present fixed-intensity sources. Alternatively, the design can be used to obtain the same penetration capability as with conventional sources, but reducing the radiation footprint by about a factor of three. The key idea is to anticipate the needed intensity for each x-ray pulse by evaluating signal strength in the cargo inspection system detector array for the previous pulse. The IMAXS is therefore capable of changing intensity from one pulse to the next by an electronic signal provided by electronics inside the cargo inspection system detector array, which determine the required source intensity for the next pulse. We report on the completion of a 9 MV S-band (2998 MHz) IMAXS source and comment on its performance.

  6. Nonthermal processes around collapsed objects: High energy gamma ray sources in the radio sky

    NASA Technical Reports Server (NTRS)

    Helfand, David J.; Ruderman, Malvin; Applegate, James H.; Becker, Robert H.

    1993-01-01

    In our proposal responding to the initial Guest Observer NRA for the Compton Gamma Ray Observatory, 'Nonthermal Processes Around Collapsed Objects: High Energy Gamma Ray Sources in the Radio Sky', we stated that 'At high energies - the identity of the principal Galactic source population remains unknown' although the 'one certain source of high energy emission is young radio pulsars'. These two statements remain true, although at this writing, eighteen months after the beginning of the Compton allsky survey, much of the gamma-ray data required to greatly extend our knowledge of the Galaxy's high energy emission has been collected. The thrust of the program supported by our grant was to collect and analyze a complementary set of data on the Milky Way at radio wavelengths in order to help identify the dominant Pop 1 component of the Galaxy's gamma ray sources, and to pursue theoretical investigations on the origins and emission mechanisms of young pulsars, the one component of this population identified to date. We summarize here our accomplishments under the grant. In Section 2, we describe our VLA surveys of the Galactic Plane along with the current status of the radio source catalogs derived therefrom; unfortunately, owing to the TDRSS antenna problem and subsequent extension of the Sky Survey, we were not able to carry out a comparison with the EGRET data directly, although everything is now in place to do so as soon as it becomes available. In Section 2, we summarize our progress on the theoretical side, including the substantial completion of a dissertation on pulsar origins and work on the high energy emission mechanisms of isolated pulsars. We list the personnel supported by the grant in section 4 and provide a complete bibliography of publications supported in whole or in part by the grant in the final section.

  7. Neutron intensity monitor with activation foil for p-Li neutron source for BNCT--Feasibility test of the concept.

    PubMed

    Murata, Isao; Otani, Yuki; Sato, Fuminobu

    2015-12-01

    Proton-lithium (p-Li) reaction is being examined worldwide as a candidate nuclear production reaction for accelerator based neutron source (ABNS) for BNCT. In this reaction, the emitted neutron energy is not so high, below 1 MeV, and especially in backward angles the energy is as low as about 100 keV. The intensity measurement was thus known to be difficult so far. In the present study, a simple method was investigated to monitor the absolute neutron intensity of the p-Li neutron source by employing the foil activation method based on isomer production reactions in order to cover around several hundreds keV. As a result of numerical examination, it was found that (107)Ag, (115)In and (189)Os would be feasible. Their features found out are summarized as follows: (107)Ag: The most convenient foil, since the half life is short. (115)In: The accuracy is the best at 0°, though it cannot be used for backward angles. And (189)Os: Suitable nuclide which can be used in backward angles, though the gamma-ray energy is a little too low. These would be used for p-Li source monitoring depending on measuring purposes in real BNCT scenes. PMID:26242557

  8. A High Intensity Linac for the National Spallation Neutron Source

    NASA Astrophysics Data System (ADS)

    Jason, A.; Bhatia, T.; Billen, J.; Schrage, D.; Kurennoy, S.; Krawczyk, F.; Lynch, M.; Nath, S.; Shafer, R.; Takeda, H.; Tallerico, P.; Wangler, T.; Wood, R.; Young, L.; Grand, P.; McKenzie-Wilson, R.

    1997-05-01

    The National Spallation Neutron Source to be constructed at Oak Ridge National Laboratory, requires a linac capable of delivering up to 5 MW of beam power to an accumulator ring with a nominal 6.2% duty factor and an energy of 1 GeV. Los Alamos, responsible for the linac design, has developed an appropriate room-temperature linac that consists of a drift-tube section from 2.5 to 20 MeV, a coupled-cavity drift-tube section to 100 MeV, and a coupled-cavity section to 1 GeV. The initial scenario requires an average 1.1-mA beam current with a corresponding 28 mA peak current and a 1.2-Mhz chopped time structure corresponding to the ring period. Upgrade to a 4.4 mA average current requires funneling with a peak current of 112 mA in the high-energy sections. Further parameters are presented along with beam dynamics and structure choices and mechanical and rf engineering considerations.

  9. Intensity-Modulated Advanced X-ray Source (IMAXS) for Homeland Security Applications

    NASA Astrophysics Data System (ADS)

    Langeveld, Willem G. J.; Johnson, William A.; Owen, Roger D.; Schonberg, Russell G.

    2009-03-01

    X-ray cargo inspection systems for the detection and verification of threats and contraband require high x-ray energy and high x-ray intensity to penetrate dense cargo. On the other hand, low intensity is desirable to minimize the radiation footprint. A collaboration between HESCO/PTSE Inc., Schonberg Research Corporation and Rapiscan Laboratories, Inc. has been formed in order to design and build an Intensity-Modulated Advanced X-ray Source (IMAXS). Such a source would allow cargo inspection systems to achieve up to two inches greater imaging penetration capability, while retaining the same average radiation footprint as present fixed-intensity sources. Alternatively, the same penetration capability can be obtained as with conventional sources with a reduction of the average radiation footprint by about a factor of three. The key idea is to change the intensity of the source for each x-ray pulse based on the signal strengths in the inspection system detector array during the previous pulse. In this paper we describe methods to accomplish pulse-to-pulse intensity modulation in both S-band (2998 MHz) and X-band (9303 MHz) linac sources, with diode or triode (gridded) electron guns. The feasibility of these methods has been demonstrated. Additionally, we describe a study of a shielding design that would allow a 6 MV X-band source to be used in mobile applications.

  10. The BATSE Earth Occultation Catalog of Low Energy Gamma-Ray Sources

    NASA Technical Reports Server (NTRS)

    Harmon, B. A.; Wilson-Hodge, C. A.; Fishman, G. J.; Paciesas, W. S.; Zhang, S. N.; Finger, M. H.; Connaughton, V.; Koshut, T. M.; Henze, W.; McCollough, M. L.

    2004-01-01

    The Burst and Transient Source Experiment (BATSE),aboard the COmptOn Gamma Ray Observatory (CGRO), provided a record of the hard X-ray/low energy gamma ray sky between April 1991 and June 2000. During that time, a catalog of known sources was derived from existing catalogs such as HEAO A-4 (Levine et al. 19841, as well as new transient sources discovered with RATSE and other X-ray monitors operating in the CGRO era. The Earth Occultation Technique (Harmon et al. 2001, astro-ph/0109069) was used to monitor a combination of these sources, mostly galactic, totaling about 175 objects. The catalog will present the global properties of these sources and their probability of detection (>lO mCrab, 20-100 keV) with BATSE. Systematic errors due to unknown sources or background components are included. Cursory analyses to search for new transients (35-80 mCrab in the 20-100 keV band) and super-orbital periods in known binary sources are also presented. Whole mission light curves and associated data production/analysis tools are being delivered to the HEASARC for public use.

  11. The BATSE Earth Occultation Catalog of Low Energy Gamma Ray Sources

    NASA Technical Reports Server (NTRS)

    Harmon, B. A.; WilsonHodge, C. A.; Fishman, G. J.; Paciesas, W.

    2002-01-01

    The Burst and Transient Source Experiment (BATSE), aboard the Compton Gamma Ray Observatory (CGRO), provided a record of the hard X-ray/low energy gamma ray sky between April 1991 and June 2000. During that time, a catalog of known sources was derived from existing catalogs such as HEAO A-4, as well as new transient sources discovered with BATSE and other X-ray monitors operating in the CGRO era. The Earth Occultation Technique was used to monitor a combination of these sources, mostly galactic, totaling to about 175 objects. The catalog will present the global properties of these sources and their probability of detection (> 10 mCrab, 20-100 keV) with BATSE. Systematic errors due to unknown sources or background components are included. Cursory analyses to search for new transients (35-80 mCrab in the 20-100 keV band) and super-orbital periods in known binary sources are also presented. Whole mission light curves and associated data production/analysis tools are being delivered to the HEASARC for public use.

  12. The BATSE Earth Occultation Catalog of Low Energy Gamma Ray Sources

    NASA Technical Reports Server (NTRS)

    Harmon, B. A.; Wilson-Hodge, C. A.; Fishman, G. J.; Paciesas, W. S.; Zhang, S. N.; Finger, M. H.; Connaughton, V.; Koshut, T. M.; Henze, W.; McCollough, M. L.; Six, N. Frank (Technical Monitor)

    2002-01-01

    The Burst and Transient Source Experiment (BATSE), aboard the Compton Gamma Ray Observatory (CGRO), provided a record of the hard X-ray/low energy gamma ray sky between April 1991 and June 2000. During that time, a catalog of known sources was derived from existing catalogs such as HEAO A-4 (Levine et al. 1984), as well as new transient sources discovered with BATSE and other X-ray monitors operating in the CGRO era. The Earth Occultation Technique (Harmon et al. 2001, astro-ph/0109069) was used to monitor a combination of these sources, mostly galactic, totaling to about 175 objects. The catalog will present the global properties of these sources and their probability of detection (greater than 10 mCrab, 20-100 keV) with BATSE. Systematic errors due to unknown sources or background components are included. Cursory analyses to search for new transients (35-80 mCrab in the 20-100 keV band) and super-orbital periods in known binary sources are also presented. Whole mission light curves and associated data production/analysis tools are being delivered to the High Energy Astrophysics Science Archive Research Center (HEASARC) for public use.

  13. Intense Pulsed Neutron Source progress report for 1991

    SciTech Connect

    Not Available

    1991-12-31

    The IPNS Progress Report 10th Anniversary Edition is being published in recognition of the first ten years of successful IPNS operation. To emphasize the significance of this milestone, we wanted this report to stand apart from the previous IPNS Progress Reports, and the best way to do this, we thought, was to make the design and organization of the report significantly different. In their articles, authors were asked to emphasize not only advances made since IPNS began operating but also the groundwork that was laid at its predecessor facilities - Argonne`s ZING-P and ZING-P` prototype pulsed neutron sources and CP-5 reactor. Each article stands as a separate chapter in the report, since each represents a particular instrument or class of instruments, system, technique, or area of research. In some cases, contributions were similar to review articles in scientific journals, complete with extensive lists of references. Ten-year cumulative lists of members of IPNS committees and of scientists who have visited or done experiments at IPNS were assembled. A list of published and ``in press`` articles in journals, books, and conference proceedings, resulting from work done at IPNS during the past ten years, was compiled. And archival photographs of people and activities during the ten-year history of IPNS were located and were used liberally throughout the report. The titles of the chapters in this report are: accelerator; computer; radiation effects; powder; stress; single crystal; superconductivity; amorphous; small angle; reflection; quasielastic; inelastic; inelastic magnetic; deep inelastic; user program; the future; and publications.

  14. Intense Pulsed Neutron Source progress report for 1991

    SciTech Connect

    Schriesheim, Alan

    1991-01-01

    The IPNS Progress Report 10th Anniversary Edition is being published in recognition of the first ten years of successful IPNS operation. To emphasize the significance of this milestone, we wanted this report to stand apart from the previous IPNS Progress Reports, and the best way to do this, we thought, was to make the design and organization of the report significantly different. In their articles, authors were asked to emphasize not only advances made since IPNS began operating but also the groundwork that was laid at its predecessor facilities - Argonne's ZING-P and ZING-P' prototype pulsed neutron sources and CP-5 reactor. Each article stands as a separate chapter in the report, since each represents a particular instrument or class of instruments, system, technique, or area of research. In some cases, contributions were similar to review articles in scientific journals, complete with extensive lists of references. Ten-year cumulative lists of members of IPNS committees and of scientists who have visited or done experiments at IPNS were assembled. A list of published and in press'' articles in journals, books, and conference proceedings, resulting from work done at IPNS during the past ten years, was compiled. And archival photographs of people and activities during the ten-year history of IPNS were located and were used liberally throughout the report. The titles of the chapters in this report are: accelerator; computer; radiation effects; powder; stress; single crystal; superconductivity; amorphous; small angle; reflection; quasielastic; inelastic; inelastic magnetic; deep inelastic; user program; the future; and publications.

  15. Determination of the gamma emission intensities of ¹¹¹Ag.

    PubMed

    Collins, Sean; Keightley, John; Gilligan, Chris; Gasparro, Joel; Pearce, Andy

    2014-05-01

    A radioactive solution of (111)Ag, standardised by the absolute measurement methods 4π(PC)-γ and 4π(LS)-γ coincidence counting at the National Physical Laboratory (NPL), was measured by two independently calibrated HPGe γ spectrometers in order to estimate the γ emission intensities and to determine the absolute intensity, with the aim of improving the currently published values. An absolute intensity value of 6.68 (7)% was obtained for the 342.1 keV γ emission, which is in agreement with previously reported values, but greatly reduces the uncertainty. Additionally, this work proposes a new emission intensity for the 450.0 keV γ emission that has not been previously reported, with an absolute intensity of 0.000482 (12)%. An investigation of the published γ emission intensities shows significant discrepancies that require resolution.

  16. Locating very high energy gamma-ray sources with arcminute accuracy

    NASA Technical Reports Server (NTRS)

    Akerlof, C. W.; Cawley, M. F.; Chantell, M.; Harris, K.; Lawrence, M. A.; Fegan, D. J.; Lang, M. J.; Hillas, A. M.; Jennings, D. G.; Lamb, R. C.

    1991-01-01

    The angular accuracy of gamma-ray detectors is intrinsically limited by the physical processes involved in photon detection. Although a number of pointlike sources were detected by the COS B satellite, only two have been unambiguously identified by time signature with counterparts at longer wavelengths. By taking advantage of the extended longitudinal structure of VHE gamma-ray showers, measurements in the TeV energy range can pinpoint source coordinates to arcminute accuracy. This has now been demonstrated with new data analysis procedures applied to observations of the Crab Nebula using Cherenkov air shower imaging techniques. With two telescopes in coincidence, the individual event circular probable error will be 0.13 deg. The half-cone angle of the field of view is effectively 1 deg.

  17. HAWC sensitivity to Galactic TeV gamma-ray sources

    NASA Astrophysics Data System (ADS)

    Hui, Michelle

    2013-04-01

    The High Altitude Water Cherenkov (HAWC) Observatory is a second generation detector of TeV gamma rays based on the water Cherenkov technique. It will comprise an array of 300 water Cherenkov detectors. It is an all-sky surveying instrument with greater than 90% duty cycle, a field of view of 2 sr, and angular resolution of 0.1 degrees for energies above 10 TeV. The HAWC Observatory is currently under construction in Sierra Negra in the state of Puebla, Mexico. The site is at a latitude of 19 degrees North, and an altitude of 4100 m. Ten percent of the array started data taking in September, 2012, and one third of the full array will be operational by Summer 2013. I will present the sensitivity of the HAWC Observatory to known Galactic gamma-ray sources, including the complex Cygnus region, and regions with unidentified source associations.

  18. Locating very high energy gamma ray sources with arc minute accuracy

    NASA Technical Reports Server (NTRS)

    Akerlof, C. W.; Cawley, M. F.; Chantell, M.; Fegan, D. J.; Harris, K.; Hillas, A. M.; Jennings, D. G.; Lamb, R. C.; Lawrence, M. A.; Lang, M. J.

    1992-01-01

    The angular accuracy of gamma-ray detectors is intrinsically limited by the physical processes involved in photon detection. Although a number of point-like sources were detected by the COS-B satellite, only two were unambiguously identified by time signature with counterparts at longer wavelengths. By taking advantage of the extended longitudinal structure of Very High Energy gamma-ray showers, measurements in the TeV energy range can pinpoint source coordinates to arc minute accuracy. This was demonstrated using Cerenkov air shower imaging techniques. With two telescopes in coincidence, the individual event circular probable error will be 0.13 deg. The half-cone angle of the field of view is effectively 1 deg.

  19. Can Handheld Plastic Detectors Do Both Gamma and Neutron Isotopic Identification with Directional Source Location?

    SciTech Connect

    Robert Hayes

    2008-04-18

    This paper demonstrates, through MCNPX simulations, that a compact hexagonal array of detectors can be utilized to do both gamma isotopic identification (ID) along with neutron identification while simultaneously finding the direction of the source relative to the detector array. The detector array itself is composed of seven borated polyvinyl toluene (PVT) hexagonal light pipes approximately 4 inches long and with a 1.25 inch face-to-face thickness assembled in a tight configuration. The gamma ID capability is realized through judicious windowing algorithms as is the neutron spectral unfolding. By having multiple detectors in different relative positions, directional determination of the source can be realized. By further adding multiplicity counters to the neutron counts, fission events can be measured.

  20. Characterization and reconstruction of planar sources that generate identical intensity distributions in the Fraunhofer zone.

    PubMed

    Martínez-Herrero, R; Mejías, P M

    1981-12-01

    A general explicit form of the correlation functions of all the partially coherent quasi-monochromatic sources that generate identical intensity distributions at the far (Fraunhofer) zone is given. The common characteristic part of all of these correlation functions is pointed out. Also, the possibility is shown for reconstructing (in unique way), from intensity data at the far zone, any source whose correlation function at some region Omega depends on the coordinate difference only.

  1. Correlative studies of astrophysical sources of very high and ultra high energy gamma-rays

    NASA Technical Reports Server (NTRS)

    Akerlof, Carl W.

    1993-01-01

    During the period of this contract, June 1, 1991 to November 14, 1992, the major results of our research effort have come from the Whipple air shower experiment in Tucson, AZ. The most notable development has been the discovery of TeV photons from the BL Lac object, Markarian 421. This result depended critically on the identification of Mrk 421 by the EGRET team as a source of GeV gamma rays.

  2. Are gamma-ray bursts the sources of ultra-high energy cosmic rays?

    NASA Astrophysics Data System (ADS)

    Baerwald, Philipp; Bustamante, Mauricio; Winter, Walter

    2015-03-01

    We reconsider the possibility that gamma-ray bursts (GRBs) are the sources of the ultra-high energy cosmic rays (UHECRs) within the internal shock model, assuming a pure proton composition of the UHECRs. For the first time, we combine the information from gamma-rays, cosmic rays, prompt neutrinos, and cosmogenic neutrinos quantitatively in a joint cosmic ray production and propagation model, and we show that the information on the cosmic energy budget can be obtained as a consequence. In addition to the neutron model, we consider alternative scenarios for the cosmic ray escape from the GRBs, i.e., that cosmic rays can leak from the sources. We find that the dip model, which describes the ankle in UHECR observations by the pair production dip, is strongly disfavored in combination with the internal shock model because (a) unrealistically high baryonic loadings (energy in protons versus energy in electrons/gamma-rays) are needed for the individual GRBs and (b) the prompt neutrino flux easily overshoots the corresponding neutrino bound. On the other hand, GRBs may account for the UHECRs in the ankle transition model if cosmic rays leak out from the source at the highest energies. In that case, we demonstrate that future neutrino observations can efficiently test most of the parameter space - unless the baryonic loading is much larger than previously anticipated.

  3. One-particle spectroscopic intensities as a signature of shape phase transition: The {gamma}-unstable case

    SciTech Connect

    Alonso, C. E.; Arias, J. M.; Vitturi, A.

    2006-08-15

    We investigate the evolution of one-particle spectroscopic intensities as a possible signature of shape phase transitions. The study describes the odd systems in terms of the interacting boson-fermion model. We consider the particular case of an odd j=3/2 particle coupled to an even-even boson core that undergoes a phase transition from spherical U(5) to {gamma}-unstable O(6) situation. At the critical point, our findings are compared with the one-particle spectroscopic intensities that can be obtained within the E(5/4) model proposed by[F. Iachello, Phys. Rev. Lett. 95, 052503 (2005); F. Iachello, in Symmetries and Low-Energy Phase Transitions in Nuclear Structure Physics, edited by G. Lo Bianco (University of Camerino Press, Camerino, Italy, in press)].

  4. REVISITING THE GAMMA-RAY SOURCE 2FGL J1823.8+4312

    SciTech Connect

    Stern, Daniel; Assef, Roberto J.

    2013-02-20

    One of the great challenges of gamma-ray astronomy is identifying the lower energy counterparts to these high-energy sources. Recently, in this journal, Massaro et al. attempted to find the counterpart of 2FGL J1823.8+4312, a gamma-ray active galactic nucleus (AGN) of uncertain type from the Second Fermi Large Area Telescope catalog. After considering mid-infrared data in the field from the Wide-field Infrared Survey Explorer (WISE), those authors conclude that the preferred identification of 2FGL J1823.8+4312 is WISE J182352.33+431452.5, despite the fact that the mid-infrared source is undetected at radio energies. They claim that WISE J182352.33+431452.5 constitutes the discovery of a new class of extragalactic X-ray source, either a radio-faint blazar or the prototype of a new class of active galaxy with an enigmatic spectral energy distribution. This conclusion is claimed to be independent of whether or not the WISE source is the actual counterpart to 2FGL J1823.8+4312. Based on a re-analysis of public data in this field and new spectroscopy from Palomar, we conclude that WISE J182352.33+431452.5 is a dust-reddened quasar at z = 0.560, a representative example of a very common extragalactic AGN class. Were WISE J182352.33+431452.5 to be associated with the gamma-ray emission, this would be an unusual and exciting discovery. However, we argue that 2FGL J1823.8+4312 is more likely associated with either WISE J182409.25+431404.7 or, more likely, WISE J182419.04+430949.6, two radio-loud sources in the field. The former is a radio-loud quasar and the latter is an optically variable source with a featureless blue spectrum.

  5. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE BURST AND TRANSIENT SOURCE EXPERIMENT 5B CATALOG OF COSMIC GAMMA-RAY BURSTS

    SciTech Connect

    Hurley, K.; Briggs, M. S.; Kippen, R. M.; Kouveliotou, C.; Fishman, G.; Cline, T.; Trombka, J.; McClanahan, T.; Boynton, W.; Starr, R.; McNutt, R.; Boer, M.

    2011-09-01

    We present Interplanetary Network localization information for 343 gamma-ray bursts observed by the Burst and Transient Source Experiment (BATSE) between the end of the 4th BATSE catalog and the end of the Compton Gamma-Ray Observatory (CGRO) mission, obtained by analyzing the arrival times of these bursts at the Ulysses, Near Earth Asteroid Rendezvous (NEAR), and CGRO spacecraft. For any given burst observed by CGRO and one other spacecraft, arrival time analysis (or 'triangulation') results in an annulus of possible arrival directions whose half-width varies between 11 arcsec and 21{sup 0}, depending on the intensity, time history, and arrival direction of the burst, as well as the distance between the spacecraft. This annulus generally intersects the BATSE error circle, resulting in an average reduction of the area of a factor of 20. When all three spacecraft observe a burst, the result is an error box whose area varies between 1 and 48,000 arcmin{sup 2}, resulting in an average reduction of the BATSE error circle area of a factor of 87.

  6. Fermi LAT Detection of a New Gamma-ray Source Associated with B2 0748+33

    NASA Astrophysics Data System (ADS)

    Cheung, C. C.

    2016-10-01

    The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed strong gamma-ray emission from a source positionally consistent with the flat-spectrum radio quasar B2 0748+33 with coordinates R.A. = 117.9736383 deg, Decl.

  7. Erratum to ATel 6655: Fermi LAT Detection of a new Gamma-ray source Fermi J0507-5641

    NASA Astrophysics Data System (ADS)

    Carpenter, B.; Ojha, R.

    2014-11-01

    (The flux units have been corrected to x10^-6 photons cm^-2 s^-1.) The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed strong gamma-ray emission from a new source.

  8. Generation of short gamma-ray pulses on electron bunches formed in intense interfering laser beams with tilted fronts

    SciTech Connect

    Korobkin, V V; Romanovskiy, M Yu; Trofimov, V A; Shiryaev, O B

    2014-05-30

    It is shown that in the interference of multiple laser pulses with a relativistic intensity, phase and amplitude fronts of which are tilted at an angle with respect to their wave vector, effective traps of charged particles, which are moving at the velocity of light, are formed. Such traps are capable of capturing and accelerating the electrons produced in the ionisation of low-density gas by means of laser radiation. The accelerated electrons in the traps form a bunch, whose dimensions in all directions are much smaller than the laser radiation wavelength. Calculations show that the energy of accelerated electrons may amount to several hundred GeV at experimentally accessible relativistic laser intensities. As a result of the inverse Compton scattering, gamma-quanta with a high energy and narrow radiation pattern are emitted when these electrons interact with a laser pulse propagating from the opposite direction. The duration of emitted gamma-ray pulses constitutes a few attoseconds. The simulation is performed by solving the relativistic equation of motion for an electron with a relevant Lorentz force. (interaction of radiation with matter)

  9. Spectral properties of blast-wave models of gamma-ray burst sources

    NASA Technical Reports Server (NTRS)

    Meszaros, P.; Rees, M. J.; Papathanassiou, H.

    1994-01-01

    We calculate the spectrum of blast-wave models of gamma-ray burst sources, for various assumptions about the magnetic field density and the relativistic particle acceleration efficiency. For a range of physically plausible models we find that the radiation efficiency is high and leads to nonthermal spectra with breaks at various energies comparable to those observed in the gamma-ray range. Radiation is also predicted at other wavebands, in particular at X-ray, optical/UV, and GeV/TeV energies. We discuss the spectra as a function of duration for three basic types of models, and for cosmological, halo, and galactic disk distances. We also evaluate the gamma-ray fluences and the spectral characteristics for a range of external densities. Impulsive burst models at cosmological distances can satisfy the conventional X-ray paucity constraint S(sub x)/S(sub gamma)less than a few percent over a wide range of durations, but galactic models can do so only for bursts shorter than a few seconds, unless additional assumptions are made. The emissivity is generally larger for bursts in a denser external environment, with the efficiency increasing up to the point where all the energy input is radiated away.

  10. Net effect of many gravitational fields on the intensity of celestial light sources. Master's thesis

    SciTech Connect

    Cipperly, G.E.

    1982-12-01

    This thesis investigates the lens-like action of the gravitational fields of celestial bodies, which can alter the apparent intensity of more distant sources. Previous work in this area has shown that the chance of an individual body being sufficiently well aligned with a source to cause a very large gravitational intensity change is small. The issue addressed in this study is the possibility of there being a significant total change in the intensity of a source due to the combined effects of the gravitational fields of all celestial bodies, and in particular, the potential impact on intensity distance measurements, that is, determination of the distances of celestial light sources by means of intensity comparisons. It is first shown that the problem can be treated in flat space by associating an appropriate index of refraction with gravitational fields. A wave approach is taken in deriving the total deflection of a ray by the field of a single point mass. A statistical analysis is then performed to determine the expression for the mean total change in the intensity of celestial light sources due to the combined fields of all intervening bodies.

  11. Unveiling the Gamma-Ray Source Count Distribution Below the Fermi Detection Limit with Photon Statistics

    NASA Astrophysics Data System (ADS)

    Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza; Fornengo, Nicolao; Vittino, Andrea

    2016-08-01

    The source-count distribution as a function of their flux, {dN}/{dS}, is one of the main quantities characterizing gamma-ray source populations. We employ statistical properties of the Fermi Large Area Telescope (LAT) photon counts map to measure the composition of the extragalactic gamma-ray sky at high latitudes (| b| ≥slant 30°) between 1 and 10 GeV. We present a new method, generalizing the use of standard pixel-count statistics, to decompose the total observed gamma-ray emission into (a) point-source contributions, (b) the Galactic foreground contribution, and (c) a truly diffuse isotropic background contribution. Using the 6 yr Fermi-LAT data set (P7REP), we show that the {dN}/{dS} distribution in the regime of so far undetected point sources can be consistently described with a power law with an index between 1.9 and 2.0. We measure {dN}/{dS} down to an integral flux of ˜ 2× {10}-11 {{cm}}-2 {{{s}}}-1, improving beyond the 3FGL catalog detection limit by about one order of magnitude. The overall {dN}/{dS} distribution is consistent with a broken power law, with a break at {2.1}-1.3+1.0× {10}-8 {{cm}}-2 {{{s}}}-1. The power-law index {n}1={3.1}-0.5+0.7 for bright sources above the break hardens to {n}2=1.97+/- 0.03 for fainter sources below the break. A possible second break of the {dN}/{dS} distribution is constrained to be at fluxes below 6.4× {10}-11 {{cm}}-2 {{{s}}}-1 at 95% confidence level. The high-latitude gamma-ray sky between 1 and 10 GeV is shown to be composed of ˜25% point sources, ˜69.3% diffuse Galactic foreground emission, and ˜6% isotropic diffuse background.

  12. Time correlations between low and high energy gamma rays from discrete sources

    NASA Technical Reports Server (NTRS)

    Ellsworth, R. W.

    1995-01-01

    Activities covered the following areas: (1) continuing analysis of the Cygnus Experiment data on the shadowing of cosmic rays by the moon and sun, which led to a direct confirmation of the angular resolution of the CYGNUS EAS array; and (2) development of analysis methods for the daily search overlapping with EGRET targets. To date, no steady emission of ultrahigh energy (UHE) gamma rays from any source has been detected by the Cygnus Experiment, but some evidence for sporadic emission had been found. Upper limits on steady fluxes from 49 sources in the northern hemisphere have been published. In addition, a daily search of 51 possible sources over the interval April 1986 to June 1992 found no evidence for emission. From these source lists, four candidates were selected for comparison with EGRET data.

  13. Photo-nuclear astrophysics in NewSUBARU {gamma}-ray source

    SciTech Connect

    Hayakawa, Takehito

    2010-08-12

    A laser Compton scattering (LCS){gamma}-ray source has been installed at an electron storage ring NewSUBARU at SPring-8. We have studied the nuclear physics using this LCS g-ray source. The half-lives of unstable isotopes, {sup 184}Re and {sup 164}Ho{sup m}, produced by photo-induced reactions have been measured. These half-lives are shorter than previous recommended values by 7% and 3%, respectively. These changes of the half-lives affects to evaluation of cross-sections using the activation method. We have discussed a problem of the residual ratio of an isomer in {sup 180}Ta in supernova explosions. The unstable ground state and the metastable isomer are linked by ({gamma}, {gamma}') reactions. We have developed a new time-dependent model to calculate the isomer ratio in supernovae. The solar abundance of {sup 180}Ta is reproduced by the supernova neutrino process with the present calculated isomer ratio.

  14. Determining X-ray source intensity and confidence bounds in crowded fields

    SciTech Connect

    Primini, F. A.; Kashyap, V. L.

    2014-11-20

    We present a rigorous description of the general problem of aperture photometry in high-energy astrophysics photon-count images, in which the statistical noise model is Poisson, not Gaussian. We compute the full posterior probability density function for the expected source intensity for various cases of interest, including the important cases in which both source and background apertures contain contributions from the source, and when multiple source apertures partially overlap. A Bayesian approach offers the advantages of allowing one to (1) include explicit prior information on source intensities, (2) propagate posterior distributions as priors for future observations, and (3) use Poisson likelihoods, making the treatment valid in the low-counts regime. Elements of this approach have been implemented in the Chandra Source Catalog.

  15. Design support of the Burst and Transient Source Experiment (BATSE) of the Gamma Ray Observatory (GRO) mission

    NASA Technical Reports Server (NTRS)

    Stephan, E. A., Jr.

    1986-01-01

    Engineering design specifications and development of the large area detector and photomultiplier tube assemblies for the Burst and Transient Source Experiment (BATSE) of the Gamma Ray Observatory (GRO) mission are examined.

  16. Abstracts of papers to be presented at the fifth symposium on x- and gamma-ray sources and applications

    SciTech Connect

    Not Available

    1981-01-01

    The program and abstracts of papers are presented. Topics include radiation sources, radiation detectors, mathematical models and data analysis, gamma-ray spectroscopy, instrumentation, applications of x-ray fluorescence, PIXE, and x-ray absorption. (ACR)

  17. Discovery of new X-ray sources near the unidentified gamma-ray source HESS J1841-055

    NASA Astrophysics Data System (ADS)

    Nobukawa, K. K.; Nobukawa, M.; Tsuru, T. G.; Koyama, K.

    2015-06-01

    HESS J1841-055 is a diffuse unidentified gamma-ray source with the size of ∼1°.3 × 1°. No conclusive counterpart in other wavelengths has so far detected. To search for X-rays responsible for the TeV emission, the Suzaku observations were conducted, which covered a half region of the HESS source. In the soft band (0.5-2.0 keV), we discovered a diffuse emission, Suzaku J1840.2-0552, with the size of ∼10‧ . Since its spectrum was fitted by an optically thin thermal plasma model, Suzaku J1840.2-0552 is likely to be a supernova remnant. We also discovered an extended source, Suzaku J1840.2-0544, in the hard band (2.0-8.0 keV) with an emission line at 6.1 keV. From the spectral feature and large interstellar absorption, this source is likely to be a cluster of galaxies behind the Galactic plane at the red-shift of ∼0.09. The other diffuse source spatially overlaps with the SNR candidate G26.6-0.2, which shows a non-thermal dominant spectrum. Since no other candidate is found in the hard X-ray band, we infer that these largely extended sources could be possible counterparts of HESS J1841-055.

  18. Report from the NSLS workshop: Sources and applications of high intensity uv-vuv light

    SciTech Connect

    Johnson, E.D.; Hastings, J.B.

    1990-01-01

    A workshop was held to evaluate sources and applications of high intensity, ultra violet (UV) radiation for biological, chemical, and materials sciences. The proposed sources are a UV free electron laser (FEL) driven by a high brightness linac and undulators in long, straight sections of a specially designed low energy (400 MeV) storage ring. These two distinct types of sources will provide a broad range of scientific opportunities that were discussed in detail during the workshop.

  19. Report from the NSLS workshop: Sources and applications of high intensity uv-vuv light

    SciTech Connect

    Johnson, E.D.; Hastings, J.B.

    1990-12-31

    A workshop was held to evaluate sources and applications of high intensity, ultra violet (UV) radiation for biological, chemical, and materials sciences. The proposed sources are a UV free electron laser (FEL) driven by a high brightness linac and undulators in long, straight sections of a specially designed low energy (400 MeV) storage ring. These two distinct types of sources will provide a broad range of scientific opportunities that were discussed in detail during the workshop.

  20. Observations of the Unidentified Gamma-Ray Source TeV J2032+4130 by VERITAS

    NASA Astrophysics Data System (ADS)

    Aliu, E.; Aune, T.; Behera, B.; Beilicke, M.; Benbow, W.; Berger, K.; Bird, R.; Buckley, J. H.; Bugaev, V.; Cardenzana, J. V.; Cerruti, M.; Chen, X.; Ciupik, L.; Connolly, M. P.; Cui, W.; Duke, C.; Dumm, J.; Errando, M.; Falcone, A.; Federici, S.; Feng, Q.; Finley, J. P.; Fortin, P.; Fortson, L.; Furniss, A.; Galante, N.; Gillanders, G. H.; Griffin, S.; Griffiths, S. T.; Grube, J.; Gyuk, G.; Hanna, D.; Holder, J.; Hughes, G.; Humensky, T. B.; Kaaret, P.; Kargaltsev, Oleg; Kertzman, M.; Khassen, Y.; Kieda, D.; Krawczynski, H.; Lang, M. J.; Madhavan, A. S.; Maier, G.; Majumdar, P.; McCann, A.; Moriarty, P.; Mukherjee, R.; Nieto, D.; O'Faoláin de Bhróithe, A.; Ong, R. A.; Otte, A. N.; Pandel, D.; Perkins, J. S.; Pohl, M.; Popkow, A.; Prokoph, H.; Quinn, J.; Ragan, K.; Rajotte, J.; Reyes, L. C.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Sembroski, G. H.; Skole, C.; Staszak, D.; Telezhinsky, I.; Theiling, M.; Tucci, J. V.; Tyler, J.; Varlotta, A.; Vincent, S.; Wakely, S. P.; Weekes, T. C.; Weinstein, A.; Welsing, R.; Williams, D. A.; Zitzer, B.

    2014-03-01

    TeV J2032+4130 was the first unidentified source discovered at very high energies (VHEs; E > 100 GeV), with no obvious counterpart in any other wavelength. It is also the first extended source to be observed in VHE gamma rays. Following its discovery, intensive observational campaigns have been carried out in all wavelengths in order to understand the nature of the object, which have met with limited success. We report here on a deep observation of TeV J2032+4130 based on 48.2 hr of data taken from 2009 to 2012 by the Very Energetic Radiation Imaging Telescope Array System experiment. The source is detected at 8.7 standard deviations (σ) and is found to be extended and asymmetric with a width of 9.'5 ± 1.'2 along the major axis and 4.'0 ± 0.'5 along the minor axis. The spectrum is well described by a differential power law with an index of 2.10 ± 0.14stat ± 0.21sys and a normalization of (9.5 ± 1.6stat ± 2.2sys) × 10-13 TeV-1 cm-2 s-1 at 1 TeV. We interpret these results in the context of multiwavelength scenarios which particularly favor the pulsar wind nebula interpretation.

  1. Observations of the unidentified gamma-ray source TeV J2032+4130 by Veritas

    SciTech Connect

    Aliu, E.; Errando, M.; Aune, T.; Behera, B.; Chen, X.; Federici, S.; Beilicke, M.; Buckley, J. H.; Bugaev, V.; Benbow, W.; Cerruti, M.; Berger, K.; Bird, R.; Cardenzana, J. V.; Ciupik, L.; Connolly, M. P.; Cui, W.; Duke, C.; Dumm, J.; Falcone, A. E-mail: gareth.hughes@desy.de; and others

    2014-03-01

    TeV J2032+4130 was the first unidentified source discovered at very high energies (VHEs; E > 100 GeV), with no obvious counterpart in any other wavelength. It is also the first extended source to be observed in VHE gamma rays. Following its discovery, intensive observational campaigns have been carried out in all wavelengths in order to understand the nature of the object, which have met with limited success. We report here on a deep observation of TeV J2032+4130 based on 48.2 hr of data taken from 2009 to 2012 by the Very Energetic Radiation Imaging Telescope Array System experiment. The source is detected at 8.7 standard deviations (σ) and is found to be extended and asymmetric with a width of 9.'5 ± 1.'2 along the major axis and 4.'0 ± 0.'5 along the minor axis. The spectrum is well described by a differential power law with an index of 2.10 ± 0.14{sub stat} ± 0.21{sub sys} and a normalization of (9.5 ± 1.6{sub stat} ± 2.2{sub sys}) × 10{sup –13} TeV{sup –1} cm{sup –2} s{sup –1} at 1 TeV. We interpret these results in the context of multiwavelength scenarios which particularly favor the pulsar wind nebula interpretation.

  2. A new class of galactic discrete gamma ray sources: Chaotic winds of massive stars

    NASA Technical Reports Server (NTRS)

    Chen, Wan; White, Richard L.

    1992-01-01

    We propose a new class of galactic discrete gamma-ray sources, the chaotic, high mass-loss-rate winds from luminous early-type stars. Early-type stellar winds are highly unstable due to intrinsic line-driven instabilities, and so are permeated by numerous strong shocks. These shocks can accelerate a small fraction of thermal electrons and ions to relativistic energies via the first-order Fermi mechanism. A power-law-like photon spectrum extending from keV to above 10 MeV energies is produced by inverse Compton scattering of the extremely abundant stellar UV photons by the relativistic electrons. In addition, a typical pi(sup 0)-decay gamma-ray spectrum is generated by proton-ion interactions in the densest part of the winds.

  3. 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.

  4. Search for discrete gamma-ray sources emitting at energies greater than 10/sup 15/ eV

    SciTech Connect

    Samorski, M.; Stamm, W.

    1984-02-15

    The data of the extensive air shower experiment at Kiel have been scanned systematically for possible discrete ..gamma..-ray sources in the energy range E>10/sup 15/ eV and in the declination band delta = 25/sup 0/-75/sup 0/. Photon fluxes for celestial positions with the statistically most significant excesses of showers and 3 sigma upper limit photon fluxes for COS B ..gamma..-ray sources visible to the extensive air shower experiment at Kiel are presented.

  5. A WISE blazar candidate counterpart of the gamma-ray flaring source nearby NRAO 676 (TXS 2159+505)

    NASA Astrophysics Data System (ADS)

    Massaro, F.; Paggi, A.; D'Abrusco, R.

    2012-06-01

    Following the Fermi LAT detection of a new gamma-ray flaring source in the vicinity of the the flat spectrum radio quasar NRAO 676 (TXS 2159+505) (ATEL #4182), we searched in the Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010 AJ, 140, 1868) catalog at the position of the Fermi source for a gamma-ray blazar candidate using the association procedure outlined in Massaro, F.......

  6. Is the Stellar System WR 11 a Gamma-Ray Source?

    NASA Astrophysics Data System (ADS)

    Benaglia, Paula

    2016-04-01

    Many early-type stars are in systems; some of them have been indicated as putative high-energy emitters. The radiation would be produced at the region where two stellar winds collide. Compelling evidence of such emission was found only for the colliding-wind binary (CWB) Eta Car, which was associated to a GeV source. Very recently, the closest CWB, WR 11, was proposed as a counterpart of a 6σ emission excess, measured with the Fermi LAT satellite. We sought evidence to support or reject the hypothesis that WR 11 is responsible of the gamma-ray excess. Archive radio interferometric data at 1.4 and 2.5 GHz taken with the Australia Telescope Compact Array along 16 dates were reduced. The sizes of the field-of-view at 2.5 GHz and of the central region of the Fermi LAT excess are alike. We analysed the emission of the WR 11 field, characterised the radio sources detected and derived their spectral indices, to investigate their nature. Eight sources with fluxes above 10 mJy were detected at both frequencies. All but one (WR 11) showed negative spectral indices. Four of them were identified with known objects, including WR 11. A fifth source, labeled here S6, is a promising candidate to produce gamma-ray emission, besides the CWB WR 11.

  7. Analysis of Multi-band Photometry of Violently Variable Gamma-Ray Sources

    NASA Astrophysics Data System (ADS)

    Kadowaki, Jennifer; Malkan, M. A.

    2013-01-01

    We studied the relationship between rapid variations in the jet intensities and changes in accretion disk activity of blazar subtype, Flat Spectrum Radio Quasar (FSRQ). Fifteen known FSRQs were specifically chosen for their prominent big blue bumps with redshifts near z=1, in order for the rest-frame UV to be redshifted into the blue-band pass. Flux changes for these 15 FSRQs were monitored for 15 observational nights in BVRI-bands and 20 nights in JHK-bands over a 12 month period using NASA's Fermi Gamma-ray Space Telescope, Lick Observatory's Nickel Telescope, and Kitt Peak National Observatory's 2.1 m Telescope. With 6.3’ x 6.3’ field of view for Nickel’s Direct Imaging Camera and 20’ x 20’ for Flamingos IR Imaging Spectrometer, approximately a half dozen, bright and non-variable stars were available to compare the concurrent changes in each of the quasar’s brightness. This process of differential photometry yielded photometric measurements of quasar brightness with 1-2% level precision. Light curves were then created for these 15 monitored quasars in optical, infrared, and gamma-ray energy bands. Dominating the redder emission spectrum due to non-thermal, synchrotron radiation and compton scattering of gamma-rays off high energy electrons, jet activity was compared to bluer spectral regions having strong accretion disk component with rest frame of approximately 2000 Angstroms. Most of the targeted FSRQs varied significantly over the 12 month monitoring period, with varying levels of fluctuations for each observed wavelength. Some correlations between gamma-ray and optical wavelengths were also present, which will be further discussed in the poster.

  8. Distinguishing mechanisms of gamma frequency oscillations in human current source signals using a computational model of a laminar neocortical network

    PubMed Central

    Lee, Shane; Jones, Stephanie R.

    2013-01-01

    Gamma frequency rhythms have been implicated in numerous studies for their role in healthy and abnormal brain function. The frequency band has been described to encompass as broad a range as 30–150 Hz. Crucial to understanding the role of gamma in brain function is an identification of the underlying neural mechanisms, which is particularly difficult in the absence of invasive recordings in macroscopic human signals such as those from magnetoencephalography (MEG) and electroencephalography (EEG). Here, we studied features of current dipole (CD) signals from two distinct mechanisms of gamma generation, using a computational model of a laminar cortical circuit designed specifically to simulate CDs in a biophysically principled manner (Jones et al., 2007, 2009). We simulated spiking pyramidal interneuronal gamma (PING) whose period is regulated by the decay time constant of GABAA-mediated synaptic inhibition and also subthreshold gamma driven by gamma-periodic exogenous excitatory synaptic drive. Our model predicts distinguishable CD features created by spiking PING compared to subthreshold driven gamma that can help to disambiguate mechanisms of gamma oscillations in human signals. We found that gamma rhythms in neocortical layer 5 can obscure a simultaneous, independent gamma in layer 2/3. Further, we arrived at a novel interpretation of the origin of high gamma frequency rhythms (100–150 Hz), showing that they emerged from a specific temporal feature of CDs associated with single cycles of PING activity and did not reflect a separate rhythmic process. Last we show that the emergence of observable subthreshold gamma required highly coherent exogenous drive. Our results are the first to demonstrate features of gamma oscillations in human current source signals that distinguish cellular and circuit level mechanisms of these rhythms and may help to guide understanding of their functional role. PMID:24385958

  9. The GeV-TeV Connection in Galactic gamma-ray Sources

    SciTech Connect

    Funk, S.; Reimer, O.; Torres, Diego F.; Hinton, J.A.; /Leeds U.

    2007-09-28

    Recent observations by atmospheric Cherenkov telescopes such as H.E.S.S. and MAGIC have revealed a large number of new sources of very-high-energy (VHE) gamma-rays above 100 GeV, mostly concentrated along the Galactic plane. At lower energies (100 MeV - 10 GeV) the satellite-based instrument EGRET revealed a population of sources clustering along the Galactic Plane. Given their adjacent energy bands a systematic correlation study between the two source classes seems appropriate. While only a few of the sources connect, both in terms of positional coincidence and spectral consistency, most of the detections occur only in one or the other energy domain. In these cases, for the first time consistent upper limits in the other energy band have been derived. Here, the populations of Galactic sources in both energy domains are characterized on observational as well as on theoretical grounds, followed by an interpretation on their similarities and differences. The observational data at this stage suggest rather different major source populations at GeV and TeV energies. With regards to preparations for the upcoming GLAST mission that will cover the energy range bridging GeV and TeV instruments this paper investigates the connection between the population of sources in these bands and concludes with predictions for commonly observable sources for GLAST-LAT detections.

  10. Intensity distribution of the X-ray source for the AXAF VETA-I mirror test

    NASA Technical Reports Server (NTRS)

    Zhao, Ping; Kellogg, Edwin M.; Schwartz, Daniel A.; Shao, Yibo; Fulton, M. A.

    1993-01-01

    Intensity distribution measurements of the X-ray source for the AXAF VETA-I mirror test are reported. During the VETA-I test, microscope pictures were taken for each used anode immediately after it was brought out of the source chamber. The source sizes and the intensity distribution structures are shown. They are compared and shown to agree with the results from pinhole camera measurements. It is demonstrated that under operating conditions characteristic of the VETA-I test, all the source sizes have an FWHM of less than 0.45 mm. For a source of this size at 528 m away, the angular size to VETA is less than 0.17 arcsec, which is small compared to the on-ground VETA angular resolution. These results were crucial for VETA data analysis and for obtaining the on-ground and predicted in-orbit VETA point response function.

  11. Intensity distribution of the x ray source for the AXAF VETA-I mirror test

    NASA Technical Reports Server (NTRS)

    Zhao, Ping; Kellogg, Edwin M.; Schwartz, Daniel A.; Shao, Yibo; Fulton, M. Ann

    1992-01-01

    The X-ray generator for the AXAF VETA-I mirror test is an electron impact X-ray source with various anode materials. The source sizes of different anodes and their intensity distributions were measured with a pinhole camera before the VETA-I test. The pinhole camera consists of a 30 micrometers diameter pinhole for imaging the source and a Microchannel Plate Imaging Detector with 25 micrometers FWHM spatial resolution for detecting and recording the image. The camera has a magnification factor of 8.79, which enables measuring the detailed spatial structure of the source. The spot size, the intensity distribution, and the flux level of each source were measured with different operating parameters. During the VETA-I test, microscope pictures were taken for each used anode immediately after it was brought out of the source chamber. The source sizes and the intensity distribution structures are clearly shown in the pictures. They are compared and agree with the results from the pinhole camera measurements. This paper presents the results of the above measurements. The results show that under operating conditions characteristic of the VETA-I test, all the source sizes have a FWHM of less than 0.45 mm. For a source of this size at 528 meters away, the angular size to VETA is less than 0.17 arcsec which is small compared to the on ground VETA angular resolution (0.5 arcsec, required and 0.22 arcsec, measured). Even so, the results show the intensity distributions of the sources have complicated structures. These results were crucial for the VETA data analysis and for obtaining the on ground and predicted in orbit VETA Point Response Function.

  12. Einstein observations of the 1978 November 19 gamma ray burst source field

    NASA Technical Reports Server (NTRS)

    Pizzichini, G.; Cline, T. L.; Desai, U. D.; Mushotzky, R.; Teegarden, B. J.; Evans, W. D.; Klebesadel, R. W.; Laros, J. G.; Barat, C.; Hurley, K.

    1982-01-01

    It is pointed out that several years after the discovery of cosmic gamma ray bursts (GRB) their sources have not yet been identified, although searches have been conducted in optical, X-ray, and radio wavelengths. The three smallest error boxes are now related to the events of Mar. 5, 1979, Apr. 6, 1979, and Nov. 19, 1978. X-ray observations, with the Imaging Proportional Counter (IPC) of the Einstein Observatory, were made for all three locations. A description is presented of the results of the 8200 second IPC observation of the Nov. 19, 1978 GRB, made on July 1 and 2, 1980. Three sources were detected. However, two of them were outside the GRB error box. The third source is located well inside the burst error box.

  13. Design of a 2 MeV Compton scattering gamma-ray source for DNDO missions

    SciTech Connect

    Hartemann, F V; Albert, F

    2009-08-24

    Nuclear resonance fluorescence-based isotope-specific detection and imaging is a powerful new technology that can enable access to new mission spaces for DNDO. Within this context, the development of advanced mono-energetic gamma ray sources plays an important role in the DNDO R&D portfolio, as it offers a faster, more precise, and safer alternative to conventional Bremsstrahlung sources. In this report, a specific design strategy is presented, along with a series of theoretical and computational tools, with the goal of optimizing source parameters for DNDO applications. In parallel, key technologies are outlined, along with discussions justifying specific choices and contrasting those with other alternatives. Finally, a complete conceptual design is described, and machine parameters are presented in detail.

  14. Mixed Source Interrogation of Steel Shielded Special Nuclear Material Using an Intense Pulsed Source

    NASA Astrophysics Data System (ADS)

    Hill, C.; Clemett, C. D.; Campbell, B.; Martin, P. N.; Threadgold, J.; O'Malley, J.

    This paper explores the benefits of using a mixed photon and neutron radiation source for active detection of special nuclear material. More than fifty irradiations were performed using an 8 MV electron accelerator employing and induction voltage adder (IVA). The experiments used a high atomic number converter to produce a Bremsstrahlung photon spectrum which was then used to create a neutron source via a nuclear interaction with heavy water (deuterium oxide, D2O). This mixed particle source was used to irradiate a depleted uranium (DU) sample, inducing fission in the sample. Several thicknesses of steel shielding were tested in order to compare the performance of the mixed photon and neutron source to a Bremsstrahlung-only source. An array of detectors were fielded to record both photons and neutrons emitted by the fission reactions. A correlation between steel shielding and a detection figure-of-merit can be seen in all cases where the Bremsstrahlung-only source was used. The same relationship for the mixed photon-neutron source is less consistent. The data collected from the fielded detectors is compared to MCNP6 calculations and good agreement is found.

  15. On the Nature of the Gamma-ray Source 2FGL J1823.8 4312: The Discovery of a New Class of Extragalactic X-ray Sources

    SciTech Connect

    Massaro, Francesco

    2012-08-03

    One of the unsolved mysteries of gamma-ray astronomy concerns the nature of the unidentified gamma-ray sources. Recently, using the Second Fermi LAT source catalog (2FGL) and the Wide-field Infrared Survey Explorer (WISE) archive, we discovered that the WISE counterparts of gamma-ray blazars, a class of active galactic nuclei, delineate a region (the WISE Gamma-ray Strip) in the 3-dimensional infrared color space well separated from the locus of the other astronomical objects. Based on this result, we built an association procedure to recognize if there areWISE blazar candidates within the positional uncertainty region of the unidentified gamma-ray sources. Here we report on our analysis of 2FGL J1823.8+4312, a gamma-ray active galactic nucleus of uncertain type associated with the X-ray source 1RXS J182418.7+430954 according to the 2FGL, to verify whether it is a blazar. Applying our association method we found two sources with IR colors typical of gamma-ray blazars, located within the 99.9% confidence region of 2FGL J1823.8+4312: WISE J182352.33+431452.5 and WISE J182409.25+431404.7. Then we searched in the Chandra, NVSS and SDSS archival observations for their counterparts. We discovered that WISE J182352.33+431452.5, our preferred gamma-ray blazar candidate according to our WISE association procedure, is detected in the optical and in the X-rays but not in the radio, making it extremely unusual if it is a blazar. Given its enigmatic spectral energy distribution, we considered the possibility that it is a 'radio faint blazar' or the prototype of a new class of extragalactic sources, our conclusion is independent of whether WISE J182352.33+431452.5 is the actual counterpart of 2FGL J1823.8+4312.

  16. Discovery of a New TeV Gamma-Ray Source: VER J0521+211

    NASA Astrophysics Data System (ADS)

    Archambault, S.; Arlen, T.; Aune, T.; Behera, B.; Beilicke, M.; Benbow, W.; Bird, R.; Bouvier, A.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cesarini, A.; Ciupik, L.; Connolly, M. P.; Cui, W.; Errando, M.; Falcone, A.; Federici, S.; Feng, Q.; Finley, J. P.; Fortson, L.; Furniss, A.; Galante, N.; Gall, D.; Gillanders, G. H.; Griffin, S.; Grube, J.; Gyuk, G.; Hanna, D.; Holder, J.; Hughes, G.; Humensky, T. B.; Kaaret, P.; Kertzman, M.; Khassen, Y.; Kieda, D.; Krawczynski, H.; Krennrich, F.; Kumar, S.; Lang, M. J.; Madhavan, A. S.; Maier, G.; Majumdar, P.; McArthur, S.; McCann, A.; Millis, J.; Moriarty, P.; Mukherjee, R.; O'Faoláin de Bhróithe, A.; Ong, R. A.; Otte, A. N.; Park, N.; Perkins, J. S.; Pohl, M.; Popkow, A.; Prokoph, H.; Quinn, J.; Ragan, K.; Reyes, L. C.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Saxon, D. B.; Sembroski, G. H.; Smith, A. W.; Staszak, D.; Telezhinsky, I.; Theiling, M.; Varlotta, A.; Vassiliev, V. V.; Vincent, S.; Wakely, S. P.; Weekes, T. C.; Weinstein, A.; Welsing, R.; Williams, D. A.; Zitzer, B.; VERITAS Collaboration; Böttcher, M.; Fegan, S. J.; Fortin, P.; Halpern, J. P.; Kovalev, Y. Y.; Lister, M. L.; Liu, J.; Pushkarev, A. B.; Smith, P. S.

    2013-10-01

    We report the detection of a new TeV gamma-ray source, VER J0521+211, based on observations made with the VERITAS imaging atmospheric Cherenkov Telescope Array. These observations were motivated by the discovery of a cluster of >30 GeV photons in the first year of Fermi Large Area Telescope observations. VER J0521+211 is relatively bright at TeV energies, with a mean photon flux of (1.93 ± 0.13stat ± 0.78sys) × 10-11 cm-2 s-1 above 0.2 TeV during the period of the VERITAS observations. The source is strongly variable on a daily timescale across all wavebands, from optical to TeV, with a peak flux corresponding to ~0.3 times the steady Crab Nebula flux at TeV energies. Follow-up observations in the optical and X-ray bands classify the newly discovered TeV source as a BL Lac-type blazar with uncertain redshift, although recent measurements suggest z = 0.108. VER J0521+211 exhibits all the defining properties of blazars in radio, optical, X-ray, and gamma-ray wavelengths.

  17. DISCOVERY OF A NEW TeV GAMMA-RAY SOURCE: VER J0521+211

    SciTech Connect

    Archambault, S.; Arlen, T.; Aune, T.; Behera, B.; Federici, S.; Beilicke, M.; Buckley, J. H.; Bugaev, V.; Benbow, W.; Bird, R.; Bouvier, A.; Byrum, K.; Cesarini, A.; Connolly, M. P.; Ciupik, L.; Cui, W.; Feng, Q.; Finley, J. P.; Errando, M.; Falcone, A. E-mail: errando@astro.columbia.edu E-mail: sfegan@llr.in2p3.fr; Collaboration: VERITAS Collaboration; and others

    2013-10-20

    We report the detection of a new TeV gamma-ray source, VER J0521+211, based on observations made with the VERITAS imaging atmospheric Cherenkov Telescope Array. These observations were motivated by the discovery of a cluster of >30 GeV photons in the first year of Fermi Large Area Telescope observations. VER J0521+211 is relatively bright at TeV energies, with a mean photon flux of (1.93 ± 0.13{sub stat} ± 0.78{sub sys}) × 10{sup –11} cm{sup –2} s{sup –1} above 0.2 TeV during the period of the VERITAS observations. The source is strongly variable on a daily timescale across all wavebands, from optical to TeV, with a peak flux corresponding to ∼0.3 times the steady Crab Nebula flux at TeV energies. Follow-up observations in the optical and X-ray bands classify the newly discovered TeV source as a BL Lac-type blazar with uncertain redshift, although recent measurements suggest z = 0.108. VER J0521+211 exhibits all the defining properties of blazars in radio, optical, X-ray, and gamma-ray wavelengths.

  18. X-ray follow-up observations of unidentified VHE {gamma}-ray sources

    SciTech Connect

    Puehlhofer, Gerd

    2008-12-24

    A large fraction of the recently discovered Galactic Very High Energy (VHE) source population remains unidentified to date. VHE {gamma}-ray emission traces high energy particles in these sources, but for example in case of hadronic processes also the gas density at the emission site. Moreover, the particles have sufficiently long lifetimes to be able to escape from their acceleration sites. Therefore, the {gamma}-ray sources or at least the areas of maximum surface brightness are in many cases spatially offset from the actual accelerators. A promising way to identify the objects in which the particles are accelerated seems to be to search for emission signatures of the acceleration process (like emission from shock-heated plasma). Also the particles themselves (through primary or secondary synchrotron emission) can be traced in lower wavebands. Those signatures are best visible in the X-ray band, and current X-ray observatories are well suited to conduct such follow-up observations. Some aspects of the current status of these investigations are reviewed.

  19. Inference of Dim Gamma-Ray Point Sources Using Probabilistic Catalogues

    NASA Astrophysics Data System (ADS)

    Daylan, Tansu; Portillo, Stephen K. N.; Finkbeiner, Douglas P.

    2016-07-01

    Poisson regression of the Fermi-LAT data in the inner Milky Way reveals an extended gamma-ray excess. The anomalous emission falls steeply away from the galactic center and has an energy spectrum that peaks at 1-2 GeV. An important question is whether the signal is coming from a collection of unresolved point sources, possibly recycled pulsars, or constitutes a truly diffuse emission component. Previous analyses have relied on non-Poissonian template fits or wavelet decomposition of the Fermi-LAT data, which find evidence for a population of dim point sources just below the 3FGL flux limit. In order to draw conclusions about a potentially dim population, we propose to sample from the catalog space of point sources, where the model dimensionality, i.e., the number of sources, is unknown. Although being a computationally expensive sampling problem, this approach allows us to infer the number, flux and radial distribution of the point sources consistent with the observed count data. Probabilistic cataloging is specifically useful in the crowded field limit, such as in the galactic disk, where the typical separation between point sources is comparable to the PSF. Using this approach, we recover the results of the deterministic Fermi-LAT 3FGL catalog, as well as sub-detection threshold information and fold the point source parameter degeneracies into the model-choice problem of whether an emission is coming from unresolved MSPs or dark matter annihilation.

  20. An upper limit on the cosmic-ray luminosity of individual sources from gamma-ray observations

    SciTech Connect

    Supanitsky, A.D.; Souza, V. de E-mail: vitor@ifsc.usp.br

    2013-12-01

    Different types of extragalactic objects are known to produce TeV gamma-rays. Some of these objects are the most probable candidates to accelerate cosmic rays up to 10{sup 20} eV. It is very well known that gamma-rays can be produced as a result of the cosmic ray propagation through the intergalactic medium. These gamma-rays contribute to the total flux observed in the direction of the source. In this paper we propose a new method to derive an upper limit on the cosmic-ray luminosity of an individual source based on the measured upper limit on the integral flux of GeV-TeV gamma-rays. We show how it is possible to calculate an upper limit on the cosmic-ray luminosity of a particular source and we explore the parameter space in which the current GeV-TeV gamma-ray measurements can offer a useful determination. We study in detail two particular sources, Pictor A and NGC 7469, and we calculate the upper limit on the proton luminosity of each source based on the upper limit on the integral gamma-ray flux measured by the H.E.S.S. telescopes.

  1. GRPANL: a program for fitting complex peak groupings for gamma and x-ray energies and intensities

    SciTech Connect

    Gunnink, R.; Ruhter, W.D.

    1980-01-01

    GRPANL is a general-purpose peak-fitting program that calculates gamma-ray and x-ray energies and intensities from a given spectral region. The program requires that the user supply input information such as the first and last channels of the region, the channels to be used as pre- and post-region background, the system gain and zero-intercept, and a list of approximate energy values at which peaks occur in the region. Because the peak position and peak-shape parameters enter nonlinearly into the peak-fitting algorithm, an iterative least-square procedure is used in the fitting process. The program iterates until either all convergence criteria are met or ten iterations have elapsed. The code described here allows for twenty free parameters and a region as large as 240 data channels. This code runs on an LSI-11 computer with 32K memory and disk-storage capability.

  2. Modelling gamma-ray photon emission and pair production in high-intensity laser–matter interactions

    SciTech Connect

    Ridgers, C.P.; Kirk, J.G.; Duclous, R.; Blackburn, T.G.; Brady, C.S.; Bennett, K.; Arber, T.D.; Bell, A.R.

    2014-03-01

    In high-intensity (>10{sup 21} Wcm{sup −2}) laser–matter interactions gamma-ray photon emission by the electrons can strongly affect the electron's dynamics and copious numbers of electron–positron pairs can be produced by the emitted photons. We show how these processes can be included in simulations by coupling a Monte Carlo algorithm describing the emission to a particle-in-cell code. The Monte Carlo algorithm includes quantum corrections to the photon emission, which we show must be included if the pair production rate is to be correctly determined. The accuracy, convergence and energy conservation properties of the Monte Carlo algorithm are analysed in simple test problems.

  3. Spectral evolution of gamma-ray bursts detected by the SIGNE experiment. 1: Correlation between intensity and spectral hardness

    NASA Technical Reports Server (NTRS)

    Kargatis, Vincent E.; Liang, Edison P.; Hurley, Kevin C.; Barat, C.; Eveno, E.; Niel, M.

    1994-01-01

    We study the continuum spectral evolution of 16 gamma-ray bursts detected by the Franco-Soviet SIGNE experiment in 1981-1982 by fitting time resolved (0.5 s) spectra in count space with simple thermal bremsstrahlung and synchrotron models. We find that there is no single characteristic of spectral evolution: we see hard-to-soft, soft-to-hard, luminosity-hardness tracking, and chaotic evolution. We perform correlation studies between instantaneous burst intensity and spectral temperature for seven bursts. While we basically confirm the existence of a correlation between these variables as originally claimed by Golenetskii et al. (1983) we find higher values and a broader range of correlation indices.

  4. UNVEILING THE NATURE OF UNIDENTIFIED GAMMA-RAY SOURCES. I. A NEW METHOD FOR THE ASSOCIATION OF GAMMA-RAY BLAZARS

    SciTech Connect

    D'Abrusco, R.; Paggi, A.; Smith, H. A.; Massaro, F.; Masetti, N.; Giroletti, M.

    2013-06-01

    We present a new method for identifying blazar candidates by examining the locus, i.e., the region occupied by the Fermi {gamma}-ray blazars in the three-dimensional color space defined by the WISE infrared colors. This method is a refinement of our previous approach that made use of the two-dimensional projection of the distribution of WISE {gamma}-ray-emitting blazars (the Strip) in the three WISE color-color planes. In this paper, we define the three-dimensional locus by means of a principal component analysis of the color distribution of a large sample of blazars composed of all the ROMA-BZCAT sources with counterparts in the WISE All-Sky Catalog associated with {gamma}-ray sources in the second Fermi-LAT catalog (2FGL; the WISE Fermi blazars sample, WFB). Our new procedure yields a total completeness of c {sub tot} {approx} 81% and a total efficiency of e {sub tot} {approx} 97%. We also obtain local estimates of the efficiency and completeness as functions of the WISE colors and galactic coordinates of the candidate blazars. The catalog of all WISE candidate blazars associated with the WFB sample is also presented, complemented by archival multi-frequency information for the alternative associations. Finally, we apply the new association procedure to all {gamma}-ray blazars in the 2FGL and provide a catalog containing all the {gamma}-ray candidate blazars selected according to our procedure.

  5. Choked Jets and Low-Luminosity Gamma-Ray Bursts as Hidden Neutrino Sources

    NASA Astrophysics Data System (ADS)

    Senno, Nicholas; Murase, Kohta; Mészáros, Peter

    2016-03-01

    I will discuss choked gamma-ray burst (GRB) jets as possible sources of very high-energy (VHE) cosmic neutrinos. The jet propagation physics and radiation constraints are taken into account. We find that efficient shock acceleration of cosmic rays inside a high density stellar environment is possible for sufficiently low-powered jets and/or jets buried in an extended optically think envelope. Such conditions are favorable also for the GRB jets to become stalled. Such choked jets may explain transrelativistic SNe or low-luminosity GRBs by launching quasi-spherical shocks that breakout in the optically thick wind. Focusing on this possibility, we calculate the resulting diffuse neutrino spectra using the latest results of the local llGRB rate and luminosity function. We confirm that llGRBs can potentially give a significant contribution to the measured neutrino flux. The results are compatible with the IceCube (IC) data around 10-100 TeV without contradicting other IC limits on classical GRBs. Choked and llGRBs are dark in GeV-TeV gamma rays, and do not contribute significantly to the Fermi diffuse gamma-ray background. Precursor TeV neutrinos emerging prior to the shock breakout emission can be used as smoking gun evidence for a choked jet model for llGRBs.

  6. Gamma-ray constraints on maximum cosmogenic neutrino fluxes and UHECR source evolution models

    SciTech Connect

    Gelmini, Graciela B.; Kalashev, Oleg; Semikoz, Dmitri V. E-mail: kalashev@ms2.inr.ac.ru

    2012-01-01

    The dip model assumes that the ultra-high energy cosmic rays (UHECRs) above 10{sup 18} eV consist exclusively of protons and is consistent with the spectrum and composition measure by HiRes. Here we present the range of cosmogenic neutrino fluxes in the dip-model which are compatible with a recent determination of the extragalactic very high energy (VHE) gamma-ray diffuse background derived from 2.5 years of Fermi/LAT data. We show that the largest fluxes predicted in the dip model would be detectable by IceCube in about 10 years of observation and are within the reach of a few years of observation with the ARA project. In the incomplete UHECR model in which protons are assumed to dominate only above 10{sup 19} eV, the cosmogenic neutrino fluxes could be a factor of 2 or 3 larger. Any fraction of heavier nuclei in the UHECR at these energies would reduce the maximum cosmogenic neutrino fluxes. We also consider here special evolution models in which the UHECR sources are assumed to have the same evolution of either the star formation rate (SFR), or the gamma-ray burst (GRB) rate, or the active galactic nuclei (AGN) rate in the Universe and found that the last two are disfavored (and in the dip model rejected) by the new VHE gamma-ray background.

  7. Pointlike gamma ray sources as signatures of distant accelerators of ultrahigh energy cosmic rays.

    PubMed

    Gabici, Stefano; Aharonian, Felix A

    2005-12-16

    We discuss the possibility of observing distant accelerators of ultrahigh energy cosmic rays in synchrotron gamma rays. Protons propagating away from their acceleration sites produce extremely energetic electrons during photopion interactions with cosmic microwave background photons. If the accelerator is embedded in a magnetized region, these electrons will emit high energy synchrotron radiation. The resulting synchrotron source is expected to be pointlike, steady, and detectable in the GeV-TeV energy range if the magnetic field is at the nanoGauss level.

  8. A new array for the study of ultra high energy gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Brooke, G.; Lambert, A.; Ogden, P. A.; Patel, M.; Ferrett, J. C.; Reid, R. J. O.; Watson, A. A.; West, A. A.

    1985-01-01

    The design and operation of a 32 x 1 10 to the 15th power sq m array of scintillation detectors for the detection of 10 to the 15th power eV cosmic rays is described with an expected angular resolution of 1 deg, thus improving the present signal/background ratio for gamma ray sources. Data are recorded on a hybrid CAMAC, an in-house system which uses a laser and Pockel-Cell arrangement to routinely calibrate the timing stability of the detectors.

  9. Online Analysis of {gamma}-ray Sources with H.E.S.S

    SciTech Connect

    Fuessling, M.; Dalton, M.; Kerschhaggl, M.; Schwanke, U.; Jung, I.; Stegmann, C.

    2008-12-24

    Some of the {gamma}-ray sources detected by the H.E.S.S. experiment display irregular, often flare-like emission behaviour. A method to detect these outbursts as fast as possible is highly desirable. At H.E.S.S., first results from an offline analysis of pre-calibrated data can be obtained on-site approximately one hour after run end. We present a development and implementation of online analysis software that performs calibration and analysis of data at the time they are being taken allowing for a fast confirmation of observational results and appropriate reaction by the on-site shift crew.

  10. Possible optical transient in Triangulum and its relation to the gamma-ray burst sources

    NASA Astrophysics Data System (ADS)

    Hudec, R.; Peresty, R.; Meinunger, L.; Wenzel, W.; Motch, C.

    1989-11-01

    The serendipitous discovery of a possible optical transient near Beta Trianguli is reported. Bright star-like plate faults such as this (about 6 mag above emulsion fog) are very unlikely and have never been observed during the examination of about 5000 sq cm of archival plates. Detailed analysis of the image density profile confirms that the new object is essentially identical to surrounding stars. All kinds of possible nonastrophysical explanation for the optical flash are reviewed and it is concluded that a terrestrial or artificial origin is very improbable. Finally, this possible optical transient is discussed in the framework of the current search for optical counterparts to gamma-gay burst sources.

  11. A biotechnological project with a gamma radiation source of 100,000 Ci

    NASA Astrophysics Data System (ADS)

    Lombardo, J. H.; Smolko, E. E.

    A project for the production of radiovaccines and other bio-medical products is presented which includes a radiation facility provided with a gamma ray source equivalent to 100,000 Ci of Co-60. The whole process incorporates novel basic features in virus production and inactivation steps. The former is carried out in animals previously subjected to immunodepression through electromagnetic radiation. The later is obtained at low temperatures by using either electromagnetic or particle radiations. A vaccine manufacture process is shown to illustrate the utilization of ionizing radiations to obtain a foot and mouth disease virus (FMDV) vaccine with good antigenic quality and low cost.

  12. Shock wave induced by a high-intensity power source in hypersonic flow

    NASA Astrophysics Data System (ADS)

    Shneider, M. N.; Gimelshein, S. F.; Raizer, Yu. P.

    2010-04-01

    An upstream structure of a parabolic shock wave induced in a hypersonic flow by a steady-state high-intensity heat source is examined. A similarity analysis is used to derive a simple analytic expression that allows one to predict the shock wave upstream stand-off distance. The solution of Navier-Stokes is obtained to provide basis for the validation of the analytic expression; a reasonable agreement is obtained between the analytic and numerical results for a number of power source intensities.

  13. Utilizing Gas Filled Cavities for the Generation of an Intense Muon Source

    SciTech Connect

    Stratakis, Diktys; Neuffer, David V.

    2015-05-01

    A key requirement for designing intense muon sources is operating rf cavities in multi-tesla magnetic fields. Recently, a proof-of-principle experiment demonstrated that an rf cavity filed with high pressure hydrogen gas could meet this goal. In this study, rigorous simulation is used to design and evaluate the performance of an intense muon source with gas filled cavities. We present a new lattice design and compare our results with conventional schemes. We detail the influence of gas pressure on the muon production rate.

  14. Utilizing gas-filled cavities for the generation of an intense muon source

    SciTech Connect

    Stratakis, Diktys; Neuffer, David V.

    2015-05-03

    A key requirement for designing intense muon sources is operating rf cavities in multi-tesla magnetic fields. Recently, a proof-of-principle experiment demonstrated that an rf cavity filed with high pressure hydrogen gas could meet this goal. In this study, rigorous simulation is used to design and evaluate the performance of an intense muon source with gas filled cavities. We present a new lattice design and compare our results with conventional schemes. We detail the influence of gas pressure on the muon production rate.

  15. Rainfall intensity and phosphorus source effects on phosphorus transport in surface runoff from soil trays.

    PubMed

    Shigaki, Francirose; Sharpley, Andrew; Prochnow, Luis Ignacio

    2007-02-01

    Phosphorus runoff from agricultural fields amended with mineral fertilizers and manures has been linked to freshwater eutrophication. A rainfall simulation study was conducted to evaluate the effects of different rainfall intensities and P sources differing in water soluble P (WSP) concentration on P transport in runoff from soil trays packed with a Berks loam and grassed with annual ryegrass (Lolium multiflorum Lam.). Triple superphosphate (TSP; 79% WSP), low-grade super single phosphate (LGSSP; 50% WSP), North Carolina rock phosphate (NCRP; 0.5% WSP) and swine manure (SM; 70% WSP), were broadcast (100 kg total P ha-1) and rainfall applied at 25, 50 and 75 mm h-1 1, 7, 21, and 56 days after P source application. The concentration of dissolved reactive (DRP), particulate (PP), and total P (TP) was significantly (P<0.01) greater in runoff with a rainfall intensity of 75 than 25 mm h-1 for all P sources. Further, runoff DRP increased as P source WSP increased, with runoff from a 50 mm h-1 rain 1 day after source application having a DRP concentration of 0.25 mg L-1 for NCRP and 28.21 mg L-1 for TSP. In contrast, the proportion of runoff TP as PP was greater with low (39% PP for NCRP) than high WSP sources (4% PP for TSP) averaged for all rainfall intensities. The increased PP transport is attributed to the detachment and transport of undissolved P source particles during runoff. These results show that P source water solubility and rainfall intensity can influence P transport in runoff, which is important in evaluating the long-term risks of P source application on P transport in surface runoff.

  16. The emittances and brightnesses of high-intensity negative ion sources

    SciTech Connect

    Alton, G.D.; McConnell, J.W.

    1987-01-01

    The emittances of high-intensity ion beams extracted from cesium sputter negative ion sources equipped with cylindrical and ellipsoidal solid tungsten and spiral-wound tantalum (General Ionex Corporation, Model 860), and cesium surface ionizers have been measured for several ion species, including /sup 12/C/sup -/, /sup 28/Si/sup -/, /sup 58/Ni/sup -/, and /sup 197/Au/sup -/. While certain sets of data from the ellipsoidal and cylindrical geometry ionizer sources suggest a moderate growth in emittance with increasing negative ion beam intensity I over the range of intensities investigated (5 less than or equal to 1 less than or equal to 60 ..mu..A) of perhaps 20%, not all data exhibit this dependence, especially those from the Model 860 source. As well, no evidence of an emittance dependence on ion mass of a monotonic nature was found. The emittances of ion beams at the 80% intensity level from the Model 860 source are found to be higher on the average by factors of 1.8 and 1.7, respectively, than those from sources equipped with ellipsoidal and cylindrical geometry cesium surface ionizers.

  17. Intensity Distribution and Luminosity Function of the Swift Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Dai, Xinyu

    2009-05-01

    Using the sample of long gamma-ray bursts (GRBs) detected by Swift-BAT before 2007 June, we measure the cumulative distribution of the peak photon fluxes (log N-log P) of the Swift bursts. Compared with the BATSE sample, we find that the two distributions are consistent after correcting the bandpass difference, suggesting that the two instruments sample the same population of bursts. We also compare the log N-log P distributions for subsamples of the Swift bursts and find evidence for a deficit (99.75% confident) of dark bursts without optical counterparts at high peak flux levels, suggesting different redshift or γ-ray luminosity distributions for these bursts. The consistency between the log N-log P distributions for the optically detected bursts with and without redshift measurements indicates that the current sample of the Swift bursts with redshift measurements, although selected heterogeneously, represents a fair sample of the nondark bursts. We calculate the luminosity functions of this sample in two redshift bins (z < 1 and z >= 1), and find that a broken power law is needed to fit the low-redshift bin, where dN/dL vprop L -1.27±0.06 for high luminosities (L peak > 5 × 1048 ergs-1) and dN/dL vprop L -2.3±0.3 for low luminosities, confirming the results of several studies for a population of low-luminosity GRBs.

  18. The neutron-gamma Feynman variance to mean approach: Gamma detection and total neutron-gamma detection (theory and practice)

    NASA Astrophysics Data System (ADS)

    Chernikova, Dina; Axell, Kåre; Avdic, Senada; Pázsit, Imre; Nordlund, Anders; Allard, Stefan

    2015-05-01

    Two versions of the neutron-gamma variance to mean (Feynman-alpha method or Feynman-Y function) formula for either gamma detection only or total neutron-gamma detection, respectively, are derived and compared in this paper. The new formulas have particular importance for detectors of either gamma photons or detectors sensitive to both neutron and gamma radiation. If applied to a plastic or liquid scintillation detector, the total neutron-gamma detection Feynman-Y expression corresponds to a situation where no discrimination is made between neutrons and gamma particles. The gamma variance to mean formulas are useful when a detector of only gamma radiation is used or when working with a combined neutron-gamma detector at high count rates. The theoretical derivation is based on the Chapman-Kolmogorov equation with the inclusion of general reactions and corresponding intensities for neutrons and gammas, but with the inclusion of prompt reactions only. A one energy group approximation is considered. The comparison of the two different theories is made by using reaction intensities obtained in MCNPX simulations with a simplified geometry for two scintillation detectors and a 252Cf-source. In addition, the variance to mean ratios, neutron, gamma and total neutron-gamma are evaluated experimentally for a weak 252Cf neutron-gamma source, a 137Cs random gamma source and a 22Na correlated gamma source. Due to the focus being on the possibility of using neutron-gamma variance to mean theories for both reactor and safeguards applications, we limited the present study to the general analytical expressions for Feynman-alpha formulas.

  19. Morphometric analysis in gamma-ray astronomy using Minkowski functionals. Source detection via structure quantification

    NASA Astrophysics Data System (ADS)

    Göring, D.; Klatt, M. A.; Stegmann, C.; Mecke, K.

    2013-07-01

    Aims: H.E.S.S. observes an increasing number of large extended sources. A new technique based on the structure of the sky map is developed to account for these additional structures by comparing them with the common point source analysis. Methods: Minkowski functionals are powerful measures from integral geometry. They can be used to quantify the structure of the counts map, which is then compared with the expected structure of a pure Poisson background. Gamma-ray sources lead to significant deviations from the expected background structure. The standard likelihood ratio method is exclusively based on the number of excess counts and discards all further structure information of large extended sources. The morphometric data analysis incorporates this additional geometric information in an unbiased analysis, i.e., without the need of any prior knowledge about the source. Results: We have successfully applied our method to data of the H.E.S.S. experiment. The morphometric analysis presented here is dedicated to detecting faint extended sources.

  20. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H.

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant. These detectors, based on silicon carbide (SiC) semiconductor are designed to have larger active volumes than previously available SiC detectors, and are being tested for their response to alpha particles, X-rays and low energy gamma rays, and fast neutrons. Specifically, SiC radiation detectors with larger areas and 100-micrometer thick active regions have been designed and manufactured according to detector-design specifications. Detectors based on a Schottky diode design were specified in order to minimize the effects of the detector entrance window on alpha particle measurements. During manufacture of the Schottky diodes, the manufacturer also provided a set of large-volume SiC p-i-n diodes for testing Extensive alpha particle measurements have been carried out to test and quantify the response of the SiC Schottky diodes. Exposures to 148-Gd, 213-Po, 217-At, 221-Fr, 225-Ac, 237-Np, 238-Pu, 240-Pu, and 242-Pu sources were used to obtain detailed alpha response data in the alpha energy range from 3182.787 keV to 8375.9 ke

  1. Atlantic Salmon (Salmo salar L.) as a Marine Functional Source of Gamma-Tocopherol

    PubMed Central

    Menoyo, David; Sanz-Bayón, Carmen; Nessa, Anna Hesby; Esatbeyoglu, Tuba; Faizan, Mohammad; Pallauf, Kathrin; De Diego, Nuria; Wagner, Anika Eva; Ipharraguerre, Ignacio; Stubhaug, Ingunn; Rimbach, Gerald

    2014-01-01

    Gamma tocopherol (gT) exhibits beneficial cardiovascular effects partly due to its anti-inflammatory activity. Important sources of gT are vegetable oils. However, little is known to what extent gT can be transferred into marine animal species such as Atlantic salmon by feeding. Therefore, in this study we have investigated the transfer of dietary gT into salmon. To this end, fish were fed a diet supplemented with 170 ppm gT for 16 weeks whereby alpha tocopherol levels were adjusted to 190 ppm in this and the control diet. Feeding gT-rich diets resulted in a three-fold increase in gT concentrations in the liver and fillet compared to non-gT-supplemented controls. Tissue alpha tocopherol levels were not decreased indicating no antagonistic interaction between gamma- and alpha tocopherol in salmon. The concentration of total omega 3 fatty acids slightly increased in response to dietary gT. Furthermore, dietary gT significantly decreased malondialdehyde in the fillet, determined as a biomarker of lipid peroxidation. In the liver of gT fed salmon we observed an overall down-regulation of genes involved in lipid homeostasis. Additionally, gT improved the antioxidant capacity by up-regulating Gpx4a gene expression in the pyloric caeca. We suggest that Atlantic salmon may provide a marine functional source capable of enriching gT for human consumption. PMID:25501796

  2. Lightning Leader Progression and Source Altitudes in Terrestrial Gamma Ray Flashes

    NASA Astrophysics Data System (ADS)

    Cummer, S. A.; Briggs, M. S.; Connaughton, V.; Fishman, G. J.; Dwyer, J. R.

    2014-12-01

    Radio emissions continue to provide a unique view into the electrodynamics of terrestrial gamma ray flash (TGF) production. Exploiting the simultaneity of a distinct low frequency radio pulse with TGF production [Cummer et al., GRL, 2011], we have begun to measure the source altitude of individual TGFs. We continue our analysis of events that produced radio emissions that are sufficiently distinct to estimate the TGF source altitude from the timing of ground and ionospheric reflections. Moreover, an even smaller (but nonempty) subset of measured radio emissions enable altitude estimation of the sequence of lightning leader pulses that precede and follow the TGF. With these results we will attempt to paint a clearer observational picture of what happens before, during, and after TGFs.

  3. 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.

  4. CARTOGAM - a portable gamma camera for remote localisation of radioactive sources in nuclear facilities

    NASA Astrophysics Data System (ADS)

    Gal, O.; Izac, C.; Jean, F.; Lainé, F.; Lévêque, C.; Nguyen, A.

    2001-03-01

    We have developed a compact gamma-imaging system, CARTOGAM, for remote localisation of radioactive sources in nuclear facilities. This system is under industrial development and commercialisation by the firm EURISYS Mesures. The most specific characteristics of CARTOGAM lie in its size (8 cm in diameter) and mass (15 kg for the detection head, including the shield), which make it portable by a person. As an example, CARTOGAM detects a 660 keV source producing a 0.4 μGy/h dose rate at the camera location in 10 min. The angular resolution at that energy ranges from 1° to 3°, depending on the field of view (30° or 50°) and scintillator thickness (2 or 4 mm). We present here a review of the specifications of the camera and show a few images illustrating its performance.

  5. X-band RF Photoinjector for Laser Compton X-ray and Gamma-ray Sources

    SciTech Connect

    Marsh, R. A.; Anderson, G. G.; Anderson, S. G.; Gibson, D. J.; Barty, C. J.

    2015-05-06

    Extremely bright narrow bandwidth gamma-ray sources are expanding the application of accelerator technology and light sources in new directions. An X-band test station has been commissioned at LLNL to develop multi-bunch electron beams. This multi-bunch mode will have stringent requirements for the electron bunch properties including low emittance and energy spread, but across multiple bunches. The test station is a unique facility featuring a 200 MV/m 5.59 cell X-band photogun powered by a SLAC XL4 klystron driven by a Scandinova solid-state modulator. This paper focuses on its current status including the generation and initial characterization of first electron beam. Design and installation of the inverse-Compton scattering interaction region and upgrade paths will be discussed along with future applications.

  6. Electron Linac design to drive bright Compton back-scattering gamma-ray sources

    SciTech Connect

    Bacci, A.; Rossi, A. R.; Serafini, L.; Alesini, D.; Bellaveglia, M.; Boni, R.; Chiadroni, E.; Di Pirro, G.; Esposito, A.; Ferrario, M.; Gallo, A.; Gatti, G.; Ghigo, A.; Spataro, B.; Vaccarezza, C.; Antici, P.; Migliorati, M.; Mostacci, A.; Palumbo, L.; Cianchi, A.; and others

    2013-05-21

    The technological development in the field of high brightness linear accelerators and high energy/high quality lasers enables today designing high brilliance Compton-X and Gamma-photon beams suitable for a wide range of applications in the innovative field of nuclear photonics. The challenging requirements of this kind of source comprise: tunable energy (1-20 MeV), very narrow bandwidth (0.3%), and high spectral density (10{sup 4} photons/s/eV). We present here a study focused on the design and the optimization of an electron Linac aimed to meet the source specifications of the European Extreme Light Infrastructure-Nuclear Physics project, currently funded and seeking for an innovative machine design in order to outperform state-of-the-art facilities. We show that the phase space density of the electron beam, at the collision point against the laser pulse, is the main quality factor characterizing the Linac.

  7. Neutrophils Are a Source of Gamma Interferon during Acute Salmonella enterica Serovar Typhimurium Colitis

    PubMed Central

    Spees, Alanna M.; Kingsbury, Dawn D.; Wangdi, Tamding; Xavier, Mariana N.; Tsolis, Renée M.

    2014-01-01

    Gamma interferon (IFN-γ) is an important driver of intestinal inflammation during colitis caused by Salmonella enterica serovar Typhimurium. Here we used the mouse colitis model to investigate the cellular sources of IFN-γ in the cecal mucosa during the acute phase of an S. Typhimurium infection. While IFN-γ staining was detected in T cells, NK cells, and inflammatory monocytes at 2 days after infection, the majority of IFN-γ-positive cells in the cecal mucosa were neutrophils. Furthermore, neutrophil depletion blunted mucosal Ifng expression and reduced the severity of intestinal lesions during S. Typhimurium infection. We conclude that neutrophils are a prominent cellular source of IFN-γ during the innate phase of S. Typhimurium-induced colitis. PMID:24421037

  8. Public Data Set: Impedance of an Intense Plasma-Cathode Electron Source for Tokamak Plasma Startup

    DOE Data Explorer

    Hinson, Edward T. [University of Wisconsin-Madison] (ORCID:000000019713140X); Barr, Jayson L. [University of Wisconsin-Madison] (ORCID:0000000177685931); Bongard, Michael W. [University of Wisconsin-Madison] (ORCID:0000000231609746); Burke, Marcus G. [University of Wisconsin-Madison] (ORCID:0000000176193724); Fonck, Raymond J. [University of Wisconsin-Madison] (ORCID:0000000294386762); Perry, Justin M. [University of Wisconsin-Madison] (ORCID:0000000171228609)

    2016-05-31

    This data set contains openly-documented, machine readable digital research data corresponding to figures published in E.T. Hinson et al., 'Impedance of an Intense Plasma-Cathode Electron Source for Tokamak Plasma Startup,' Physics of Plasmas 23, 052515 (2016).

  9. Intense proton beam source for ITER neutral-beam spectroscopy diagnostics

    NASA Astrophysics Data System (ADS)

    Bartsch, R. R.; Davis, H. A.; Henins, I.; Greenly, J. B.

    An intense proton beam has been developed to evaluate a gas-cell neutralizer for use in an intense-neutral beam source for Tokomak Spectroscopy diagnostics. The allowed energy range of the proton stream is determined to be 50 to 70 keV from neutralization and reionization cross-sections and from the alpha particle charge exchange recombination intensity as a function of energy (baseline diagnostic). The neutralization evaluation source uses a flashover anode, magnetized, ion-diode. Neutral probes sensitive to energetic atomic and molecular hydrogen, developed to evaluate neutralizer performance, show neutral fluence from the ion-diode during the beam pulse. An array of Rogowski current probes, used to study the evolution of the current path, suggests that expansion of the anode plasma along the radial insulating magnetic field leads to impedance collapse.

  10. Intense proton beam source for ITER neutral-beam spectroscopy diagnostics

    SciTech Connect

    Bartsch, R.R.; Davis, H.A.; Henins, I.; Greenly, J.B.

    1994-09-01

    An intense proton beam has been developed to evaluate a gas-cell neutralizer for use in an intense-neutral beam source for Tokomak Spectroscopy diagnostics. The allowed energy range of the proton stream is determined to be 50 to 70 keV from neutralization and reionization cross-sections and from the alpha particle charge exchange recombination intensity as a function of energy (baseline diagnostic). The neutralization evaluation source uses a flashover anode, magnetized, ion-diode. Neutral probes sensitive to energetic atomic and molecular hydrogen, developed to evaluate neutralizer performance, show neutral fluence from the ion-diode during the beam pulse. An array of Rogowski current probes, used to study the evolution of the current path, suggests that expansion of the anode plasma along the radial insulating magnetic field leads to impedance collapse.

  11. DEVELOPMENT OF A PRECISION TUNABLE GAMMA-RAY SOURCE DRIVEN BY A COMPACT X-BAND LINAC

    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; Messerly, M J; Semenov, V A; Shverdin, M Y; Siders, C W; McNabb, D P; Barty, C J; Vlieks, A E; Jongewaard, E N; Tantawi, S G

    2009-04-30

    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.

  12. Low intensity X-ray and gamma-ray imaging device. [fiber optics

    NASA Technical Reports Server (NTRS)

    Yin, L. I. (Inventor)

    1979-01-01

    A radiation to visible light converter is combined with a visible light intensifier. The converter is a phosphor or scintillator material which is modified to block ambient light. The intensifier includes fiber optics input and output face plates with a photocathode-microchannel plate amplifier-phosphor combination. Incoming radiation is converted to visible light by the converter which is piped into the intensifier by the input fiber optics face plate. The photocathode converts the visible light to electrons which are amplified by a microchannel plate amplifier. The electrons are converted back to light by a phosphor layer and piped out for viewing by the output fiber optics faces plate. The converter-intensifier combination may be further combined with its own radiation source or used with an independent source.

  13. NIR photometry of the Gamma-Ray source Fermi J1654-1055 and 3FGLJ1037.5-2821

    NASA Astrophysics Data System (ADS)

    Carrasco, L.; Recillas, E.; Porras, A.; Chavushyan, V.; Leon-Tavares, J.

    2016-03-01

    Following the reports of flaring in Gamma-rays (Atel #8721 and Atel #8740) of the sources 3FGLJ10378.5-2821 identified with the high redshift (z=1.066) quasar PKSB1035-28 and FermiJ1654-1055 tentatively identified with the radio source PMNJ1632-1052.

  14. CANGAROO-III OBSERVATION OF TeV GAMMA RAYS FROM THE UNIDENTIFIED GAMMA-RAY SOURCE HESS J1614-518

    SciTech Connect

    Mizukami, T.; Kubo, H.; Tanimori, T.; Kabuki, S.; Yoshida, T.; Nakamori, T.; Enomoto, R.; Kifune, T.; Akimoto, M.; Ishioka, H.; Kawachi, A.; Bicknell, G. V.; Clay, R. W.; Edwards, P. G.; Gunji, S.; Hara, S.; Hara, T.; Hayashi, S.; Kajino, F.; Katagiri, H. E-mail: kubo@cr.scphys.kyoto-u.ac.jp

    2011-10-20

    We report the detection, with the CANGAROO-III imaging atmospheric Cherenkov telescope array, of a very high energy gamma-ray signal from the unidentified gamma-ray source HESS J1614-518, which was discovered in the H.E.S.S. Galactic plane survey. Diffuse gamma-ray emission was detected above 760 GeV at the 8.9{sigma} level during an effective exposure of 54 hr from 2008 May to August. The spectrum can be represented by a power law: (8.2 {+-} 2.2{sub stat} {+-} 2.5{sub sys}) x 10{sup -12} x (E/1 TeV){sup -}{gamma} cm{sup -2} s{sup -1} TeV{sup -1} with a photon index {gamma} of 2.4 {+-} 0.3{sub stat} {+-} 0.2{sub sys}, which is compatible with that of the H.E.S.S. observations. By combining our result with multiwavelength data, we discuss the possible counterparts for HESS J1614-518 and consider radiation mechanisms based on hadronic and leptonic processes for a supernova remnant (SNR), stellar winds from massive stars, and a pulsar wind nebula (PWN). Although a leptonic origin from a PWN driven by an unknown pulsar remains possible, hadronic-origin emission from an unknown SNR is preferred.

  15. High intensity compact Compton X-ray sources: Challenges and potential of applications

    NASA Astrophysics Data System (ADS)

    Jacquet, M.

    2014-07-01

    Thanks to the exceptional development of high power femtosecond lasers in the last 15 years, Compton based X-ray sources are in full development over the world in the recent years. Compact Compton sources are able to combine the compactness of the instrument with a beam of high intensity, high quality, tunable in energy. In various fields of applications such as biomedical science, cultural heritage preservation and material science researches, these sources should provide an easy working environment and the methods currently used at synchrotrons could be largely developed in a lab-size environment as hospitals, labs, or museums.

  16. Choked jets and low-luminosity gamma-ray bursts as hidden neutrino sources

    NASA Astrophysics Data System (ADS)

    Senno, Nicholas; Murase, Kohta; Mészáros, Peter

    2016-04-01

    We consider gamma-ray burst (GRB) jets that are choked by extended material as sources of high-energy cosmic neutrinos. We take into account the jet propagation physics both inside the progenitor star and the surrounding dense medium. Radiation constraints, which are relevant for high-energy neutrino production, are considered as well. Efficient shock acceleration of cosmic rays is possible for sufficiently low-power jets and/or jets buried in a dense, extended wind or outer envelope. Such conditions also favor GRB jets to become stalled, and the necessary conditions for stalling are explicitly derived. Such choked jets may explain transrelativistic supernovae (SNe) and low-luminosity (LL) GRBs, giving a unified picture of GRBs and GRB-SNe. Focusing on this unified scenario for GRBs, we calculate the resulting neutrino spectra from choked jets, including the relevant microphysical processes such as multipion production in p p and p γ interactions, as well as the energy losses of mesons and muons. We obtain diffuse neutrino spectra using the latest results for the luminosity function of LL GRBs. Although uncertainties are large, we confirm that LL GRBs can potentially give a significant contribution to the diffuse neutrino flux. Our results are consistent with the present IceCube data and do not violate the stacking limits on classical high-luminosity GRBs. We find that high-energy neutrino production in choked jets is dominated by p γ interactions. These sources are dark in GeV-TeV gamma rays and do not contribute significantly to the Fermi diffuse gamma-ray background. Assuming stalled jets can launch a quasispherical shock in the dense medium, "precursor" TeV neutrinos emerging prior to the shock breakout gamma-ray emission can be used as smoking-gun evidence for a choked jet model for LL GRBs. Our results strengthen the relevance of wide field-of-view sky monitors with better sensitivities in the 1-100 keV range.

  17. Including signal intensity increases the performance of blind source separation on brain imaging data.

    PubMed

    Li, Ming; Liu, Yadong; Chen, Fanglin; Hu, Dewen

    2015-02-01

    When analyzing brain imaging data, blind source separation (BSS) techniques critically depend on the level of dimensional reduction. If the reduction level is too slight, the BSS model would be overfitted and become unavailable. Thus, the reduction level must be set relatively heavy. This approach risks discarding useful information and crucially limits the performance of BSS techniques. In this study, a new BSS method that can work well even at a slight reduction level is presented. We proposed the concept of "signal intensity" which measures the significance of the source. Only picking the sources with significant intensity, the new method can avoid the overfitted solutions which are nonexistent artifacts. This approach enables the reduction level to be set slight and retains more useful dimensions in the preliminary reduction. Comparisons between the new and conventional algorithms were performed on both simulated and real data. PMID:25314698

  18. OCT imaging with temporal dispersion induced intense and short coherence laser source

    NASA Astrophysics Data System (ADS)

    Manna, Suman K.; le Gall, Stephen; Li, Guoqiang

    2016-10-01

    Lower coherence length and higher intensity are two indispensable requirements on the light source for high resolution and large penetration depth OCT imaging. While tremendous interest is being paid on engineering various laser sources to enlarge their bandwidth and hence lowering the coherence length, here we demonstrate another approach by employing strong temporal dispersion onto the existing laser source. Cholesteric liquid crystal (CLC) cells with suitable dispersive slope at the edge of 1-D organic photonic band gap have been designed to provide maximum reduction in coherence volume while maintaining the intensity higher than 50%. As an example, the coherence length of a multimode He-Ne laser is reduced by more than 730 times.

  19. Cigarette-Smoking Intensity and Interferon-Gamma Release Assay Conversion among Persons Who Inject Drugs: A Cohort Study

    PubMed Central

    Shin, Sanghyuk S.; Gallardo, Manuel; Lozada, Remedios; Abramovitz, Daniela; Burgos, Jose Luis; Laniado-Laborin, Rafael; Rodwell, Timothy C.; Novotny, Thomas E.; Strathdee, Steffanie A.; Garfein, Richard S.

    2012-01-01

    We analyzed data from a longitudinal cohort study of persons who inject drugs (PWID) in Tijuana, Mexico, to explore whether cigarette smoking increases the risk of interferon gamma release assay (IGRA) conversion. PWID were recruited using respondent driven sampling (RDS). QuantiFERON-TB Gold In-Tube (QFT) assay conversion was defined as interferon-gamma concentrations <0.35 IU/mL at baseline and ≥0.7 IU/mL at 18 months. We used multivariable Poisson regression adjusted for RDS weights to estimate risk ratios (RRs). Of 129 eligible participants, 125 (96.9%) smoked at least one cigarette during followup with a median of 11 cigarettes smoked daily, and 52 (40.3%) had QFT conversion. In bivariate analysis, QFT conversion was not associated with the number of cigarettes smoked daily (P = 0.716). Controlling for age, gender, education, and alcohol use, the RRs of QFT conversion for smoking 6–10, 11–15, and ≥16 cigarettes daily compared to smoking 0–5 cigarettes daily were 0.9 (95% confidence interval (CI), 0.5–1.6), 0.5 (95% CI, 0.3–1.2), and 0.7 (95% CI, 0.3–1.6), respectively. Although this study did not find an association between self-reported smoking intensity and QFT conversion, it was not powered sufficiently to negate such an association. Larger longitudinal studies are needed to fully explore this relationship. PMID:23304497

  20. High-intensity and high-brightness source of moderated positrons using a brilliant γ beam

    NASA Astrophysics Data System (ADS)

    Hugenschmidt, C.; Schreckenbach, K.; Habs, D.; Thirolf, P. G.

    2012-01-01

    Presently, large efforts are conducted toward the development of highly brilliant γ beams via Compton back scattering of photons from a high-brilliance electron beam, either on the basis of a normal-conducting electron linac or a (super-conducting) Energy Recovery Linac (ERL). Particularly, ERLs provide an extremely brilliant electron beam, thus enabling the generation of highest-quality γ beams. A 2.5 MeV γ beam with an envisaged intensity of 1015 photons s-1, as ultimately envisaged for an ERL-based γ-beam facility, narrow band width (10-3), and extremely low emittance (10-4 mm2 mrad2) offers the possibility to produce a high-intensity bright polarized positron beam. Pair production in a face-on irradiated W converter foil (200 μm thick, 10 mm long) would lead to the emission of 2×1013 (fast) positrons per second, which is four orders of magnitude higher compared to strong radioactive 22Na sources conventionally used in the laboratory. Using a stack of converter foils and subsequent positron moderation, a high-intensity low-energy beam of moderated positrons can be produced. Two different source setups are presented: a high-brightness positron beam with a diameter as low as 0.2 mm, and a high-intensity beam of 3×1011 moderated positrons per second. Hence, profiting from an improved moderation efficiency, the envisaged positron intensity would exceed that of present high-intensity positron sources by a factor of 100.

  1. Galactic sources of high energy neutrinos: Expectation from gamma-ray data

    NASA Astrophysics Data System (ADS)

    Sahakyan, N.

    2016-07-01

    The recent results from ground based γ-ray detectors (HESS, MAGIC, VERITAS) provide a population of TeV galactic γ-ray sources which are potential sources of High Energy (HE) neutrinos. Since the γ-rays and ν-s are produced from decays of neutral and charged pions, the flux of TeV γ-rays can be used to estimate the upper limit of ν flux and vice versa; the detectability of ν flux implies a minimum flux of the accompanying γ-rays (assuming the internal and the external absorption of γ-rays is negligible). Using this minimum flux, it is possible to find the sources which can be detected with cubic-kilometer telescopes. I will discuss the possibility to detect HE neutrinos from powerful galactic accelerators, such as Supernova Remnants (SNRs) and Pulsar Wind Nebulae (PWNe) and show that likely only RX J1713.7-3946, RX J0852.0-4622 and Vela X can be detected by current generation of instruments (IceCube and Km3Net). It will be shown also, that galactic binary systems could be promising sources of HE ν-s. In particular, ν-s and γ-rays from Cygnus X-3 will be discussed during recent gamma-ray activity, showing that in the future such kind of activities could produce detectable flux of HE ν-s.

  2. An electronically-collimated portable gamma-ray detector for locating environmental radiation sources

    NASA Astrophysics Data System (ADS)

    Matthews, Kenneth L., II; Smith, Blair M.; Lackie, Adam W.; Hill, William H., Jr.; Wang, Wei-Hsung; Cherry, Michael L.

    2006-08-01

    We are developing a detector system for locating environmental radiation sources. The design emphasizes compact size (ideally hand-held), wide field of view and high detection efficiency, and uses cadmium-zinc-telluride (CZT) detectors and electronic collimation via Compton-scatter detection. The detector design is a 6-sided box with a primary scatter detector on one end. GEANT4 simulations, allowing variations of detector parameters and source energies/locations, provided performance estimates. A partial prototype, using 16x16-pixel 38x38x5-mm 3 CZT detectors, was developed and tested. Two methods to calculate source direction in real-time from the Compton scatter data were evaluated: (1) filtered backprojection of cones onto a sphere; (2) intersection with the sphere of bounding boxes circumscribed around the cones. Simulation results of the 6-sided box with the current CZT modules indicated 1-5% of incident gamma rays produce valid direction angles, with an angular resolution of ~15°. The directional algorithms allowed a FOV (directional error <10°) of approximately +/-60°. The direction algorithms converge on a source direction estimate in as few as 100 detected events. With improvements in detector energy and spatial resolution, reasonable performance seems achievable for a range of radioisotopes, e.g., from Am-241 through Co-60.

  3. Suzaku Observation of the Unidentified Gamma-ray Source HESS J1841-055

    NASA Astrophysics Data System (ADS)

    Nobukawa, Kumiko

    HESS J1841-055 is an unidentified Gamma-ray source and spread across 1 degree. There is not yet a conclusive counterpart in any other wave length. We observed HESS J1841-055 with Suzaku. Several sources were found in the region. (1) High mass X-ray binary AX J1841.0-0536 exhibited many short flares with the time-scales of a few hundred seconds and a large flare with the peak flux (1.0-10 keV) of ≤2×10(-10) erg s(-1) cm(-2) . The source had a high dynamical range (ratio of the peak luminosity in the large flare to the quiescent emission), which spanned 3 orders of magnitudes. (2) Soft (0.5-2.0 keV) diffuse X-ray emission is a supernova remnant candidate, since its spectrum was fit by an optically thin thermal plasma model. (3) 2 arcminutes extended source in the hard band (2.0-8.0 keV) had a high column density of N_mathrm{H}˜10(23) cm(-2) and a red-shifted iron line. It can be a new candidate of a cluster of galaxy.

  4. TOWARD IDENTIFYING THE UNASSOCIATED GAMMA-RAY SOURCE 1FGL J1311.7-3429 WITH X-RAY AND OPTICAL OBSERVATIONS

    SciTech Connect

    Kataoka, J.; Takahashi, Y.; Maeda, K.; Yatsu, Y.; Kawai, N.; Urata, Y.; Tsai, A.; Cheung, C. C.; Totani, T.; Makiya, R.; Hanayama, H.; Miyaji, T.

    2012-10-01

    We present deep optical and X-ray follow-up observations of the bright unassociated Fermi-LAT gamma-ray source 1FGL J1311.7-3429. The source was already known as an unidentified EGRET source (3EG J1314-3431, EGR J1314-3417), hence its nature has remained uncertain for the past two decades. For the putative counterpart, we detected a quasi-sinusoidal optical modulation of {Delta}m {approx} 2 mag with a period of {approx_equal}1.5 hr in the Rc, r', and g' bands. Moreover, we found that the amplitude of the modulation and peak intensity changed by {approx}>1 mag and {approx}0.5 mag, respectively, over our total six nights of observations from 2012 March to May. Combined with Swift UVOT data, the optical-UV spectrum is consistent with a blackbody temperature, kT {approx_equal} 1 eV and the emission volume radius R{sub bb} {approx_equal} 1.5 Multiplication-Sign 10{sup 4} d{sub kpc} km (d{sub kpc} is the distance to the source in units of 1 kpc). In contrast, deep Suzaku observations conducted in 2009 and 2011 revealed strong X-ray flares with a light curve characterized with a power spectrum density of P(f) {proportional_to} f {sup -2.0{+-}0.4}, but the folded X-ray light curves suggest an orbital modulation also in X-rays. Together with the non-detection of a radio counterpart, and significant curved spectrum and non-detection of variability in gamma-rays, the source may be the second 'radio-quiet' gamma-ray emitting millisecond pulsar candidate after 1FGL J2339.7-0531, although the origin of flaring X-ray and optical variability remains an open question.

  5. Toward Identifying the Unassociated Gamma-Ray Source 1FGL J1311.7-3429 with X-Ray and Optical Observations

    NASA Astrophysics Data System (ADS)

    Kataoka, J.; Yatsu, Y.; Kawai, N.; Urata, Y.; Cheung, C. C.; Takahashi, Y.; Maeda, K.; Totani, T.; Makiya, R.; Hanayama, H.; Miyaji, T.; Tsai, A.

    2012-10-01

    We present deep optical and X-ray follow-up observations of the bright unassociated Fermi-LAT gamma-ray source 1FGL J1311.7-3429. The source was already known as an unidentified EGRET source (3EG J1314-3431, EGR J1314-3417), hence its nature has remained uncertain for the past two decades. For the putative counterpart, we detected a quasi-sinusoidal optical modulation of Δm ~ 2 mag with a period of sime1.5 hr in the Rc, r', and g' bands. Moreover, we found that the amplitude of the modulation and peak intensity changed by gsim1 mag and ~0.5 mag, respectively, over our total six nights of observations from 2012 March to May. Combined with Swift UVOT data, the optical-UV spectrum is consistent with a blackbody temperature, kT sime 1 eV and the emission volume radius R bb ~= 1.5 × 104 d kpc km (d kpc is the distance to the source in units of 1 kpc). In contrast, deep Suzaku observations conducted in 2009 and 2011 revealed strong X-ray flares with a light curve characterized with a power spectrum density of P(f) vprop f -2.0 ± 0.4, but the folded X-ray light curves suggest an orbital modulation also in X-rays. Together with the non-detection of a radio counterpart, and significant curved spectrum and non-detection of variability in gamma-rays, the source may be the second "radio-quiet" gamma-ray emitting millisecond pulsar candidate after 1FGL J2339.7-0531, although the origin of flaring X-ray and optical variability remains an open question.

  6. Discovery of a new population of high-energy gamma-ray sources in the Milky Way

    PubMed

    Gehrels; Macomb; Bertsch; Thompson; Hartman

    2000-03-23

    One of the great mysteries of the high-energy gamma-ray sky is the group of approximately 170 unidentified point sources found along the Galactic plane. They are more numerous than all other high-energy gamma-ray sources combined and, despite 20 years of effort, no clear counterparts have been found at other wavelengths. Here we report a new population of such objects. A cluster of approximately 20 faint sources appears north of the Galactic Centre, which is part of a broader class of faint objects at mid-latitudes. In addition, we show in a model-independent way that the mid-latitude sources are distinct from the population of bright unidentified sources along the Galactic plane. The distribution on the sky indicates that the faint mid-latitude sources are associated with the Gould belt of massive stars and gas clouds at approximately 600 light years distance, as has been previously suggested.

  7. Carbon source recovery from waste activated sludge by alkaline hydrolysis and gamma-ray irradiation for biological denitrification.

    PubMed

    Kim, Tak-Hyun; Nam, Youn-Ku; Park, Chulhwan; Lee, Myunjoo

    2009-12-01

    The recovery of an organic carbon source from a waste activated sludge by using alkaline hydrolysis and radiation treatment was studied, and the feasibility of the solubilized sludge carbon source for a biological denitrification was also investigated. The effects of an alkaline treatment and gamma-ray irradiation on a biodegradability enhancement of the sludge were also studied. A modified continuous bioreactor for a denitrification (MLE reactor) was operated by using a synthetic wastewater for 47 days. Alkaline treatment of pH 10 and gamma-ray irradiation of 20 kGy were found to be the optimum carbon source recovery conditions. COD removal of 84% and T-N removal of 51% could be obtained by using the solubilized sludge carbon source through the MLE denitrification process. It can be concluded that the carbon source recovered from the waste activated sludge was successfully employed as an alternative carbon source for a biological denitrification.

  8. Response-surface models for deterministic effects of localized irradiation of the skin by discrete {beta}/{gamma} -emitting sources

    SciTech Connect

    Scott, B.R.

    1995-12-01

    Individuals who work at nuclear reactor facilities can be at risk for deterministic effects in the skin from exposure to discrete {Beta}- and {gamma}-emitting ({Beta}{gamma}E) sources (e.g., {Beta}{gamma}E hot particles) on the skin or clothing. Deterministic effects are non-cancer effects that have a threshold and increase in severity as dose increases (e.g., ulcer in skin). Hot {Beta}{gamma}E particles are {sup 60}Co- or nuclear fuel-derived particles with diameters > 10 {mu}m and < 3 mm and contain at least 3.7 kBq (0.1 {mu}Ci) of radioactivity. For such {Beta}{gamma}E sources on the skin, it is the beta component of the dose that is most important. To develop exposure limitation systems that adequately control exposure of workers to discrete {Beta}{gamma}E sources, models are needed for systems that adequately control exposure of workers to discrete {Beta}{gamma}E sources, models are needed for evaluating the risk of deterministic effects of localized {Beta} irradiation of the skin. The purpose of this study was to develop dose-rate and irradiated-area dependent, response-surface models for evaluating risks of significant deterministic effects of localized irradiation of the skin by discrete {Beta}{gamma}E sources and to use modeling results to recommend approaches to limiting occupational exposure to such sources. The significance of the research results as follows: (1) response-surface models are now available for evaluating the risk of specific deterministic effects of localized irradiation of the skin; (2) modeling results have been used to recommend approaches to limiting occupational exposure of workers to {Beta} radiation from {Beta}{gamma}E sources on the skin or on clothing; and (3) the generic irradiated-volume, weighting-factor approach to limiting exposure can be applied to other organs including the eye, the ear, and organs of the respiratory or gastrointestinal tract and can be used for both deterministic and stochastic effects.

  9. REPORT OF THE SNOWMASS M6 WORKING GROUP ON HIGH INTENSITY PROTON SOURCES.

    SciTech Connect

    CHOU,W.; WEI,J.

    2001-08-14

    The M6 working group had more than 40 active participants (listed in Section 4). During the three weeks at Snowmass, there were about 50 presentations, covering a wide range of topics associated with high intensity proton sources. The talks are listed in Section 5. This group also had joint sessions with a number of other working groups, including E1 (Neutrino Factories and Muon Colliders), E5 (Fixed-Target Experiments), M1 (Muon Based Systems), T4 (Particle Sources), T5 (Beam dynamics), T7 (High Performance Computing) and T9 (Diagnostics). The M6 group performed a survey of the beam parameters of existing and proposed high intensity proton sources, in particular, of the proton drivers. The results are listed in Table 1. These parameters are compared with the requirements of high-energy physics users of secondary beams in Working Groups E1 and E5. According to the consensus reached in the E1 and E5 groups, the U.S. HEP program requires an intense proton source, a 1-4 MW Proton Driver, by the end of this decade.

  10. Computation of instantaneous and time-averaged active acoustic intensity field around rotating source

    NASA Astrophysics Data System (ADS)

    Mao, Yijun; Xu, Chen; Qi, Datong

    2015-02-01

    A vector aeroacoustics method is developed to analyze the acoustic energy flow path from the rotating source. In this method, the instantaneous and time-averaged active acoustic intensity vectors are evaluated from the time-domain and frequency-domain acoustic pressure and acoustic velocity formulations, respectively. With the above method, the acoustic intensity vectors and the acoustic energy streamlines are visualized to investigate the propagation feature of the noise radiated from the monopole and dipole point sources and the rotor in subsonic rotation. The result reveals that a portion of the acoustic energy spirals many circles before moving towards the far field, and another portion of the acoustic energy firstly flows inward along the radial direction and then propagates along the axial direction. Further, an acoustic black hole exists in the plane of source rotation, from which the acoustic energy cannot escape once the acoustic energy flows into it. Moreover, by visualizing the acoustic intensity field around the rotating sources, the acoustic-absorption performance of the acoustic liner built in the casing and centerbody is discussed.

  11. Neutrino-Gamma Multi-Messenger Source Detection via the Astrophysical Multi-Messenger Observatory Network

    NASA Astrophysics Data System (ADS)

    Fixelle, Josh; Miles, S.; AMON

    2014-01-01

    The idea of multi-messenger event detection has long been explored in the context of above-threshold analysis performed by the IceCube collaboration using Swift BAT and by the Amanda collaboration using BATSE. While these investigations produced null results, they left the event space of sub-threshold events untouched. This untapped event space, combined with the addition of new observatories for various bands and messenger types, provides the obvious niche for a GBN style network to exist: AMON. We consider Monte-carlo models of pair-wise detection between sub-threshold IceCube neutrino doublets, sub-threshold neutrino-gamma doublets with Swift BAT, and with sub-threshold higher multiplicity neutrino-gamma coincidences with Fermi LAT. Several detection methods were considered and compared to the status quo analyses of neutrino doublets by IceCube, demonstrating significant sensitivity gain. The MC model analysis was followed by an archival doublet analysis between IceCube-40 and Fermi LAT data within their co-temporal window of observation. Several methods for detecting statistical signal excess in the archival analysis were considered, providing an upper limit on source population parameters for the given analysis sensitivity.

  12. Is the gamma-ray source 3FGL J2212.5+0703 a dark matter subhalo?

    NASA Astrophysics Data System (ADS)

    Bertoni, Bridget; Hooper, Dan; Linden, Tim

    2016-05-01

    In a previous paper, we pointed out that the gamma-ray source 3FGL J2212.5+\\linebreak 0703 shows evidence of being spatially extended. If a gamma-ray source without detectable emission at other wavelengths were unambiguously determined to be spatially extended, it could not be explained by known astrophysics, and would constitute a smoking gun for dark matter particles annihilating in a nearby subhalo. With this prospect in mind, we scrutinize the gamma-ray emission from this source, finding that it prefers a spatially extended profile over that of a single point-like source with 5.1σ statistical significance. We also use a large sample of active galactic nuclei and other known gamma-rays sources as a control group, confirming, as expected, that statistically significant extension is rare among such objects. We argue that the most likely (non-dark matter) explanation for this apparent extension is a pair of bright gamma-ray sources that serendipitously lie very close to each other, and estimate that there is a chance probability of ~2% that such a pair would exist somewhere on the sky. In the case of 3FGL J2212.5+0703, we test an alternative model that includes a second gamma-ray point source at the position of the radio source BZQ J2212+0646, and find that the addition of this source alongside a point source at the position of 3FGL J2212.5+0703 yields a fit of comparable quality to that obtained for a single extended source. If 3FGL J2212.5+0703 is a dark matter subhalo, it would imply that dark matter particles have a mass of ~18–33 GeV and an annihilation cross section on the order of σ v ~ 10‑26 cm3/s (for the representative case of annihilations to bbar b), similar to the values required to generate the Galactic Center gamma-ray excess.

  13. Is the gamma-ray source 3FGL J2212.5+0703 a dark matter subhalo?

    DOE PAGES

    Bertoni, Bridget; Hooper, Dan; Linden, Tim

    2016-05-23

    In a previous study, we pointed out that the gamma-ray source 3FGL J2212.5+0703 shows evidence of being spatially extended. If a gamma-ray source without detectable emission at other wavelengths were unambiguously determined to be spatially extended, it could not be explained by known astrophysics, and would constitute a smoking gun for dark matter particles annihilating in a nearby subhalo. With this prospect in mind, we scrutinize the gamma-ray emission from this source, finding that it prefers a spatially extended profile over that of a single point-like source with 5.1σ statistical significance. We also use a large sample of active galactic nuclei and other known gamma-rays sources as a control group, confirming, as expected, that statistically significant extension is rare among such objects. We argue that the most likely (non-dark matter) explanation for this apparent extension is a pair of bright gamma-ray sources that serendipitously lie very close to each other, and estimate that there is a chance probability of ~2% that such a pair would exist somewhere on the sky. In the case of 3FGL J2212.5+0703, we test an alternative model that includes a second gamma-ray point source at the position of the radio source BZQ J2212+0646, and find that the addition of this source alongside a point source at the position of 3FGL J2212.5+0703 yields a fit of comparable quality to that obtained for a single extended source. If 3FGL J2212.5+0703 is a dark matter subhalo, it would imply that dark matter particles have a mass of ~18–33 GeV and an annihilation cross section on the order of σv ~ 10–26 cm(3)/s (for the representative case of annihilations tomore » $$b\\bar{b}$$), similar to the values required to generate the Galactic Center gamma-ray excess.« less

  14. Is the gamma-ray source 3FGL J2212.5+0703 a dark matter subhalo?

    NASA Astrophysics Data System (ADS)

    Bertoni, Bridget; Hooper, Dan; Linden, Tim

    2016-05-01

    In a previous paper, we pointed out that the gamma-ray source 3FGL J2212.5+\\linebreak 0703 shows evidence of being spatially extended. If a gamma-ray source without detectable emission at other wavelengths were unambiguously determined to be spatially extended, it could not be explained by known astrophysics, and would constitute a smoking gun for dark matter particles annihilating in a nearby subhalo. With this prospect in mind, we scrutinize the gamma-ray emission from this source, finding that it prefers a spatially extended profile over that of a single point-like source with 5.1σ statistical significance. We also use a large sample of active galactic nuclei and other known gamma-rays sources as a control group, confirming, as expected, that statistically significant extension is rare among such objects. We argue that the most likely (non-dark matter) explanation for this apparent extension is a pair of bright gamma-ray sources that serendipitously lie very close to each other, and estimate that there is a chance probability of ~2% that such a pair would exist somewhere on the sky. In the case of 3FGL J2212.5+0703, we test an alternative model that includes a second gamma-ray point source at the position of the radio source BZQ J2212+0646, and find that the addition of this source alongside a point source at the position of 3FGL J2212.5+0703 yields a fit of comparable quality to that obtained for a single extended source. If 3FGL J2212.5+0703 is a dark matter subhalo, it would imply that dark matter particles have a mass of ~18-33 GeV and an annihilation cross section on the order of σ v ~ 10-26 cm3/s (for the representative case of annihilations to bbar b), similar to the values required to generate the Galactic Center gamma-ray excess.

  15. A figure of merit for blazar-like source identification in the gamma-ray energy band

    SciTech Connect

    Cavazzuti, Elisabetta; Pittori, Carlotta; Giommi, Paolo; Colafrancesco, Sergio

    2007-07-12

    The microwave to gamma-ray slope {alpha}{mu}{gamma} can be used as a viable figure of merit for blazar-like source identification in gamma-rays. Taking into account the constraints from the observed extragalactic gamma-ray background, one can estimate the maximum duty cycle allowed for a selected sample of low energy peaked (LBL) blazars, in order to be detectable for the nominal sensitivity values of AGILE and GLAST gamma-ray experiments. This work is based on the results of a recently derived blazar radio LogN-LogS obtained by combining several multi-frequency surveys. We present our estimates of duty cycle constraints applied on a sample composed by 146 high latitude and 74 medium latitude LBL blazars from the new WMAP3 yr catalog. Our results can be used as an indicator to identify good gamma-ray blazar candidates: sources with high values of duty cycle can in principle be detectable also in a ''steady'' state by AGILE and GLAST without over-predicting the extragalactic background.

  16. Origin of ultra-high-energy gamma-rays from Cygnus X-3 and related sources

    NASA Technical Reports Server (NTRS)

    Kazanas, D.; Ellison, D. C.

    1986-01-01

    Diffusive shock acceleration of ions is examined as the mechanism responsible for the ultrahigh energy (UHE) gamma ray emission observed from Cygnus X-3 and several other binary X-ray sources at energies of 10 to the 15th eV and higher. The shock acceleration can under reasonable assumptions be sufficiently short to allow acceleration of ions to energies near 10 to the 16th eV. It is proposed that the subsequent proton-proton collisions and photodissociation of He-4 can produce a flux of neutrons that escapes from the acceleration site despite high magnetic fields. These neutrons, by interacting with the binary companion, produce the observed UHE radiation.

  17. Open-source hardware and software and web application for gamma dose rate network operation.

    PubMed

    Luff, R; Zähringer, M; Harms, W; Bleher, M; Prommer, B; Stöhlker, U

    2014-08-01

    The German Federal Office for Radiation Protection operates a network of about 1800 gamma dose rate stations as a part of the national emergency preparedness plan. Each of the six network centres is capable of operating the network alone. Most of the used hardware and software have been developed in-house under open-source license. Short development cycles and close cooperation between developers and users ensure robustness, transparency and fast maintenance procedures, thus avoiding unnecessary complex solutions. This also reduces the overall costs of the network operation. An easy-to-expand web interface has been developed to make the complete system available to other interested network operators in order to increase cooperation between different countries. The interface is also regularly in use for education during scholarships of trainees supported, e.g. by the 'International Atomic Energy Agency' to operate a local area dose rate monitoring test network.

  18. Design and Operation of a tunable MeV-level Compton-scattering-based (gamma-ray) source

    SciTech Connect

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

    2009-07-07

    A mono-energetic gamma-ray (MEGa-ray) source based on Compton-scattering, targeting nuclear physics applications such as nuclear resonance fluorescence, has been constructed and commissioned at Lawrence Livermore National Laboratory. In this paper, the overall architecture of the system, as well as some of the critical design decisions made in the development of the source, are discussed. 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 initial {gamma}-ray results are presented.

  19. Overview of the High Intensity Neutrino Source Linac R&D program at Fermilab

    SciTech Connect

    Webber, R.C.; Appollinari, G.; Carneiro, J.P.; Gonin, I.; Hanna, B.; Hays, S.; Khabiboulline, T.; Lanfranco, G.; Madrak, R.L.; Moretti, A.; Nicol, T.; /Fermilab /Argonne

    2008-09-01

    The Fermilab High Intensity Neutrino Source (HINS) Linac R&D program is building a first-of-a-kind 60 MeV superconducting H- linac. The HINS Linac incorporates superconducting solenoids for transverse focusing, high power RF vector modulators for independent control of multiple cavities powered from a single klystron, and superconducting spoke-type accelerating cavities starting at 10 MeV. This will be the first application and demonstration of any of these technologies in a low-energy, high-intensity proton/H- linear accelerator. The HINS effort is relevant to a high intensity, superconducting H- linac that might serve the next generation of neutrino physics and muon storage ring/collider experiments. An overview of the HINS program, machine design, status, and outlook is presented.

  20. Physics of high-intensity nanosecond electron source: Charge limit phenomenon in GaAs photocathodes

    SciTech Connect

    Herrera-Gomez, A. |; Vergara, G.; Spicer, W.E.

    1996-05-01

    GaAs negative electron affinity cathodes are used as high-intensity, short-time electron source at the Stanford Linear Accelerator Center. When the cathodes are illuminated with high-intensity laser pulses draw peak currents that are extremely high, typically of tens of Amperes. Because of the high currents, some nonlinear effects are present. Very noticeable is the so-called charge limit (CL) effect, which consists of a limit on the total charge in each pulse; that is, the total bunch charge stops increasing as the light pulse intensity increases. The CL effect is directly related to a photovoltage built up in the surface as a consequence of the photoelectrons coming from the bulk. We discuss possible ways to minimize the formation of the surface photovoltage. {copyright} {ital 1996 American Institute of Physics.}

  1. Detection of embedded radiation sources using temporal variation of gamma spectral data.

    SciTech Connect

    Shokair, Isaac R.

    2011-09-01

    Conventional full spectrum gamma spectroscopic analysis has the objective of quantitative identification of all the isotopes present in a measurement. For low energy resolution detectors, when photopeaks alone are not sufficient for complete isotopic identification, such analysis requires template spectra for all the isotopes present in the measurement. When many isotopes are present it is difficult to make the correct identification and this process often requires many trial solutions by highly skilled spectroscopists. This report investigates the potential of a new analysis method which uses spatial/temporal information from multiple low energy resolution measurements to test the hypothesis of the presence of a target spectrum of interest in these measurements without the need to identify all the other isotopes present. This method is referred to as targeted principal component analysis (TPCA). For radiation portal monitor applications, multiple measurements of gamma spectra are taken at equally spaced time increments as a vehicle passes through the portal and the TPCA method is directly applicable to this type of measurement. In this report we describe the method and investigate its application to the problem of detection of a radioactive localized source that is embedded in a distributed source in the presence of an ambient background. Examples using simulated spectral measurements indicate that this method works very well and has the potential for automated analysis for RPM applications. This method is also expected to work well for isotopic detection in the presence of spectrally and spatially varying backgrounds as a result of vehicle-induced background suppression. Further work is needed to include effects of shielding, to understand detection limits, setting of thresholds, and to estimate false positive probability.

  2. First beam from the TRASCO intense proton source (TRIPS) at INFN-LNS

    NASA Astrophysics Data System (ADS)

    Ciavola, G.; Celona, L.; Gammino, S.; Chines, F.; Campisano, C.

    2002-02-01

    The TRASCO intense proton source (TRIPS) was installed at INFN-LNS in May 2000 and the commissioning is in progress. This article describes the design of the source along with the first results and the next developments. The source has been able to deliver more than 20 mA of protons with high reliability from a 4.5 mm extraction aperture at 65 kV, largely above the minimum requested current density. The goals in terms of beam energy (80 keV) and current (60 mA from 8 mm extraction aperture) have been achieved. Further optimization of the source is under way, with special care given to the reliability needed for the accelerator driving system purpose.

  3. Improvement of beam emittance of the CEA high intensity proton source SILHI

    NASA Astrophysics Data System (ADS)

    Gobin, R.; Beauvais, P.-Y.; Ferdinand, R.; Leroy, P.-A.; Celona, L.; Ciavola, G.; Gammino, S.

    1999-06-01

    The emittance of the intense proton beam extracted by the source SILHI at Commisariat à l'Energie Atomique (CEA)-Saclay is a key parameter for the design of the IPHI Project RFQ. This parameter has a relevant role even for the design of an intense proton source for the TRASCO project of Istituto Nazionale di Fisica Nucleare (INFN). The tests performed in the framework of CEA-INFN collaboration have been mainly devoted to a 75 mA beam emittance investigation injecting different gases in the beam line. The results show that the rms normalized emittance decreases up to a factor 3 while the beam losses induced by recombination are contained within 5%. Normalized emittance in r-r' plane of about 0.1 π min mrad have been obtained using Ar and Kr.

  4. The Molecular Environment of the Gamma-Ray Source TeV J2032+4130

    NASA Astrophysics Data System (ADS)

    Butt, Yousaf M.; Schneider, Nicola; Dame, T. M.; Brunt, Christopher

    2008-04-01

    The mysterious very high energy gamma-ray source, TeV J2032+4130, is coincident with the powerful Cygnus OB2 stellar association, although a physical association between the two remains uncertain. It is possible that the detected very high energy photons are produced via an overdensity of locally accelerated cosmic rays impinging on molecular clouds in the source region. In order to test this hypothesis, we used the Kitt Peak 12 m, the Heinrich Hertz Submillimeter Telescope (HH-SMT), and the Five College Radio Astronomy Observatory (FCRAO) to obtain observations in the J = 1 → 0 and J = 2 → 1 lines of both 12CO and 13CO. We report here on the detection of significant molecular material toward the TeV source region which could be acting as the target of locally accelerated CRs. We also find evidence of compact molecular clumps, showing large line widths in the CO spectra, possibly indicative of energetic processes in this region of Cygnus OB2.

  5. Design of an Intense Muon Source with a Carbon and Mercury Target

    SciTech Connect

    Stratakis, Diktys; Berg, J. Scott; Neuffer, David; Ding, Xiaoping

    2015-06-01

    In high-intensity sources, muons are produced by firing high energy protons onto a target to produce pions. The pions decay to muons which are captured and accelerated. In the present study, we examine the performance of the channel for two different target scenarios: one based on liquid mercury and another one based on a solid carbon target. We produce distributions with the two different target materials and discuss differences in particle spectrum near the sources. We then propagate the distributions through our capture system and compare the full system performance for the two target types.

  6. Design of an intense muon source with a carbon and mercury target

    SciTech Connect

    Stratakis, D.; Berg, J. S.; Neuffer, D.; Ding, X.

    2015-05-03

    In high-intensity sources, muons are produced by firing high energy protons onto a target to produce pions. The pions decay to muons which are captured and accelerated. In the present study, we examine the performance of the channel for two different target scenarios: one based on liquid mercury and another one based on a solid carbon target. We produce distributions with the two different target materials and discuss differences in particle spectrum near the sources. We then propagate the distributions through our capture system and compare the full system performance for the two target types.

  7. Goddard contributions to the Los Alamos Conference on Transient Cosmic Gamma and X-ray Sources

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Conference papers, covering the orgin and instrumentation for measuring the position of cosmic gamma ray bursts, are presented. Summaries cover gamma ray detectors, energy speectra, and the stellar super flare hypothesis.

  8. The development of the high intensity electron cyclotron resonance ion source at China Institute of Atomic Energy

    NASA Astrophysics Data System (ADS)

    Tang, B.; Ma, R.; Ma, Y.; Chen, L.; Huang, Q.; Liang, H.; Cui, B.; Jiang, W.

    2014-02-01

    High-current microwave ion source has been under development over 15 years for accelerator driven sub-critical system research at China Institute of Atomic Energy, and the beam intensity higher than 140 mA proton beam is produced by this ion source with long lifetime and high reliability. The emittance of high intensity continue-wave and pulse beam is measured on a test-bench in the laboratory. Based on the good performance of this proton ion source, a new 120 mA deuterium ion source is proposed for a high intensity neutron generator. The ion source details and status will be presented.

  9. A 4-point in-situ method to locate a discrete gamma-ray source in 3-D space.

    PubMed

    Byun, Jong-In; Choi, Hee-Yeoul; Yun, Ju-Yong

    2010-02-01

    The determination of the source position (x,y,z) of a discrete gamma-ray source using peak count rates from four measurement points was studied. We derived semi-empirical formulas to find the position under the condition to neglect attenuation effects by obstacles between the target source and the detector. To validate the methodology, we performed the locating experiments for a (137)Cs small volume source placed at 10 different positions on the floor of a laboratory using the formulas derived in this study. In this study, a portable HPGe gamma spectrometry system with a virtual point detector concept was used. The calculation results for the source positions were compared with reference values measured with a rule. The applicability of the methodology was estimated based on the differences of the results. PMID:19932029

  10. Impact of source segregation intensity of solid waste on fuel consumption and collection costs.

    PubMed

    Di Maria, Francesco; Micale, Caterina

    2013-11-01

    Fuel consumption and collection costs of solid waste were evaluated by the aid of a simulation model for a given collection area of a medium-sized Italian city. Using the model it is possible to calculate time, collected waste and fuel consumption for a given waste collection route. Starting from the data for the current waste collection scenario with a Source Segregated (SS) intensity of 25%, all the main model error evaluated was ⩽1.2. SS intensity scenarios of 25%, 30%, 35% and 52% were simulated. Results showed an increase in the average fuel consumed by the collection vehicles that went from about 3.3L/tonne for 25% SS intensity to about 3.8L/tonne for a SS intensity of 52%. Direct collection costs, including crews and vehicle purchase, ranged from about 40€/tonne to about 70€/tonne, respectively, for 25% and 52% SS intensity. The increase in fuel consumption and collection costs depends on the density of the waste collected, on the collection vehicle compaction ratio and on the waste collection vehicle utilization factor (WCVUF). In particular a reduction of about 50% of the WCVUF can lead to an average increase of about 80% in fuel consumption and 100% in collection costs. PMID:23871186

  11. High-power, photofission-inducing bremsstrahlung source for intense pulsed active detection of fissile material

    NASA Astrophysics Data System (ADS)

    Zier, J. C.; Mosher, D.; Allen, R. J.; Commisso, R. J.; Cooperstein, G.; Hinshelwood, D. D.; Jackson, S. L.; Murphy, D. P.; Ottinger, P. F.; Richardson, A. S.; Schumer, J. W.; Swanekamp, S. B.; Weber, B. V.

    2014-06-01

    Intense pulsed active detection (IPAD) is a promising technique for detecting fissile material to prevent the proliferation of special nuclear materials. With IPAD, fissions are induced in a brief, intense radiation burst and the resulting gamma ray or neutron signals are acquired during a short period of elevated signal-to-noise ratio. The 8 MV, 200 kA Mercury pulsed-power generator at the Naval Research Laboratory coupled to a high-power vacuum diode produces an intense 30 ns bremsstrahlung beam to study this approach. The work presented here reports on Mercury experiments designed to maximize the photofission yield in a depleted-uranium (DU) object in the bremsstrahlung far field by varying the anode-cathode (AK) diode gap spacing and by adding an inner-diameter-reducing insert in the outer conductor wall. An extensive suite of diagnostics was fielded to measure the bremsstrahlung beam and DU fission yield as functions of diode geometry. Delayed fission neutrons from the DU proved to be a valuable diagnostic for measuring bremsstrahlung photons above 5 MeV. The measurements are in broad agreement with particle-in-cell and Monte Carlo simulations of electron dynamics and radiation transport. These show that with increasing AK gap, electron losses to the insert and outer conductor wall increase and that the electron angles impacting the bremsstrahlung converter approach normal incidence. The diode conditions for maximum fission yield occur when the gap is large enough to produce electron angles close to normal, yet small enough to limit electron losses.

  12. A tunable, linac based, intense, broad-band THz source forpump-probe experiments

    SciTech Connect

    Schmerge, J.; Adolphsen, C.; Corbett, J.; Dolgashev, V.; Durr, H.; Fazio, M.; Fisher, A.; Frisch, J.; Gaffney, K.; Guehr, M.; Hastings, J.; Hettel, B.; Hoffmann, M.; Hogan, M.; Holtkamp, N.; Huang, X.; Huang, Z.; Kirchmann, P.; LaRue, J.; Limborg, C.; Lindenberg, A.; Loos, H.; Maxwell, T.; Nilsson, A.; Raubenheimer, T.; Reis, D.; Ross, M.; Shen, Z. -X.; Stupakov, G.; Tantawi, S.; Tian, K.; Wu, Z.; Xiang, D.; Yakimenko, V.

    2015-02-02

    We propose an intense THz source with tunable frequency and bandwidth that can directly interact with the degrees of freedom that determine the properties of materials and thus provides a new tool for controlling and directing these ultrafast processes as well as aiding synthesis of new materials with new functional properties. This THz source will broadly impact our understanding of dynamical processes in matter at the atomic-scale and in real time. Established optical pumping schemes using femtosecond visible frequency laser pulses for excitation are extended into the THz frequency regime thereby enabling resonant excitation of bonds in correlated solid state materials (phonon pumping), to drive low energy electronic excitations, to trigger surface chemistry reactions, and to all-optically bias a material with ultrashort electric fields or magnetic fields. A linac-based THz source can supply stand-alone experiments with peak intensities two orders of magnitude stronger than existing laser-based sources, but when coupled with atomic-scale sensitive femtosecond x-ray probes it opens a new frontier in ultrafast science with broad applications to correlated materials, interfacial and liquid phase chemistry, and materials in extreme conditions.

  13. ASPUN: design for an Argonne super-intense pulsed neutron source

    SciTech Connect

    Khoe, T.K.; Kustom, R.L.

    1983-01-01

    Argonne pioneered the pulsed spallation neutron source with the ZING-P and IPNS-I concepts. IPNS-I is now a reliable and actively used source for pulsed spallation neutrons. The accelerator is a 500-MeV, 8 to 9 ..mu..a, 30-Hz rapid-cycling proton synchrotron. Other proton spallation sources are now in operation or in construction. These include KENS-I at the National Laboratory for High Energy Physics in Japan, the WNR/PSR at Los Alamos National Laboratory in the USA, and the SNS at the Rutherford Appleton Laboratory in England. Newer and bolder concepts are being developed for more-intense pulsed spallation neutron sources. These include SNQ at the KFA Laboratory in Juelich, Germany, ASTOR at the Swiss Institute for Nuclear Physics in Switzerland, and ASPUN, the Argonne concept. ASPUN is based on the Fixed-Field Alternating Gradient concept. The design goal is to provide a time-averaged beam of 3.5 ma at 1100 MeV on a spallation target in intense bursts, 100 to 200 nanoseconds long, at a repetition rate of no more than 60 to 85 Hz.

  14. An Investigation of 154Eu as a High-Precision Multi-{gamma}-Ray Intensity Calibration Standard for Detector Arrays

    SciTech Connect

    Kulp, W.D.; Wood, J.L.; Krane, K. S.; Loats, J.; Schmelzenbach, P.D.; Stapels, C.J.; Norman, E.B.

    2005-05-24

    The decay of 154Eu has been studied using {gamma}-ray singles and {gamma} - {gamma} coincidence spectroscopy with an array of Compton-suppressed Ge detectors. Particular attention to coincidence summing in the analysis, with consideration of detailed decay cascades and angular correlation effects, suggests that previous studies have overlooked necessary corrections. It is concluded that 154Eu provides 26 {gamma} rays that can be used for relative efficiency calibrations from 120 to 1600 keV at the 0.7% precision level and that this precision could be improved in the future.

  15. A modified high-intensity Cs sputter negative-ion source with multi-target mechanism

    NASA Astrophysics Data System (ADS)

    Houzhi, Si; Weizhong, Zhang; Jinhau, Zhu; Guangtian, Du; Tiaorong, Zhang; Xiang, Gao

    1993-04-01

    The source is based on Middleton's high-intensity mode, but modified to a multi-target version. It is equipped with a spherical molybdenum ionizer, a 20-position target wheel and a vacuum lock for loading and unloading sample batches. A metal-ceramic bonded section protected by a specially designed labyrinth shielding system results in reliable insulation of the cathode and convenient control of cesium vapor. The latter is particularly important when an oversupply of cesium occurs. The source was developed for accelerator mass spectrometry (AMS) applications. Recently, three versions based on the prototype of the source have been successfully tested to meet different requirements: (a) single target version, (b) multi-target version with manual sample change, and (c) multi-target version with remote control sample change. Some details of the technical and operational characteristics are presented.

  16. VERITAS 2008-2009 MONITORING OF THE VARIABLE GAMMA-RAY SOURCE M 87

    SciTech Connect

    Acciari, V. A.; Benbow, W.; Aliu, E.; Arlen, T.; Chow, Y. C.; Aune, T.; Beilicke, M.; Buckley, J. H.; Bugaev, V.; Dickherber, R.; Boltuch, D.; Bradbury, S. M.; Byrum, K.; Cannon, A.; Cesarini, A.; Ciupik, L.; Cogan, P.; Cui, W.; Finley, J. P.; Duke, C.

    2010-06-10

    M 87 is a nearby radio galaxy that is detected at energies ranging from radio to very high energy (VHE) gamma rays. Its proximity and its jet, misaligned from our line of sight, enable detailed morphological studies and extensive modeling at radio, optical, and X-ray energies. Flaring activity was observed at all energies, and multi-wavelength correlations would help clarify the origin of the VHE emission. In this paper, we describe a detailed temporal and spectral analysis of the VERITAS VHE gamma-ray observations of M 87 in 2008 and 2009. In the 2008 observing season, VERITAS detected an excess with a statistical significance of 7.2 standard deviations ({sigma}) from M 87 during a joint multi-wavelength monitoring campaign conducted by three major VHE experiments along with the Chandra X-ray Observatory. In 2008 February, VERITAS observed a VHE flare from M 87 occurring over a 4 day timespan. The peak nightly flux above 250 GeV was (1.14 {+-} 0.26) x 10{sup -11} cm{sup -2} s{sup -1}, which corresponded to 7.7% of the Crab Nebula flux. M 87 was marginally detected before this 4 day flare period, and was not detected afterward. Spectral analysis of the VERITAS observations showed no significant change in the photon index between the flare and pre-flare states. Shortly after the VHE flare seen by VERITAS, the Chandra X-ray Observatory detected the flux from the core of M 87 at a historical maximum, while the flux from the nearby knot HST-1 remained quiescent. Acciari et al. presented the 2008 contemporaneous VHE gamma-ray, Chandra X-ray, and Very Long Baseline Array radio observations which suggest the core as the most likely source of VHE emission, in contrast to the 2005 VHE flare that was simultaneous with an X-ray flare in the HST-1 knot. In 2009, VERITAS continued its monitoring of M 87 and marginally detected a 4.2{sigma} excess corresponding to a flux of {approx}1% of the Crab Nebula. No VHE flaring activity was observed in 2009.

  17. The enigmatic gamma-ray source XSS J12270-4859 aka 1FGL J1227.9-4852

    NASA Astrophysics Data System (ADS)

    Belloni, Tomaso; de Martino, Domitilla; Falanga, Maurizio; Bonnet-Bidaud, Jean-Marc; Mouchet, Martine; Masetti, Nicola; Mukai, Koji; Matt, Giorgio

    XSS J12270-4859 is an enigmatic source. First classified as a possible magnetic CV, its 860s peri-odicity was not confirmed. Remarkably, the source lies only 1.2 arcminutes from the Fermi/LAT source 1FGL J1227.9-4852, which emits gamma-rays up to 10 GeV. We report the results of the analysis of data over energies from the IR to gamma-rays, using data from ground-based IR-optical-UV telescopes, XMM-Newton, RXTE, INTEGRAL and Fermi. The XMM and RXTE light curves show high variability in the form of flares and dip, with the flares detected also in the UV band. Complex spectral variability is observed. The 0.2-100 keV spectrum is fitted with a power law with photon index 1.7, while the gamma-ray 100 MeV-10 GeV spectrum has a steeper index (2.5). The GeV emission is a significant component of the spectrum, with a peak energy between 1 and 100 MeV. Optical photometry reveals a 4.32 hr period, possibly of orbital nature. This source could be another rare gamma-ray binary of LMXB nature.

  18. Ultracompact Accelerator Technology for a Next-Generation Gamma-Ray Source

    SciTech Connect

    Marsh, R A; Albert, F; Anderson, S G; Gibson, D J; Wu, S S; Hartemann, F V; Barty, C J

    2012-05-14

    This presentation reported on the technology choices and progress manufacturing and testing the injector and accelerator of the 250 MeV ultra-compact Compton Scattering gamma-ray Source under development at LLNL for homeland security applications. This paper summarizes the status of various facets of current accelerator activities at LLNL. The major components for the X-band test station have been designed, fabricated, and await installation. The XL-4 klystron has been delivered, and will shortly be dressed and installed in the ScandiNova modulator. High power testing of the klystron into RF loads will follow, including adjustment of the modulator for the klystron load as necessary. Assembly of RF transport, test station supports, and accelerator components will follow. Commissioning will focus on processing the RF gun to full operating power, which corresponds to 200 MV/m peak electric field on the cathode surface. Single bunch benchmarking of the Mark 1 design will provide confidence that this first structure operates as designed, and will serve as a solid starting point for subsequent changes, such as a removable photocathode, and the use of various cathode materials for enhanced quantum efficiency. Charge scaling experiments will follow, partly to confirm predictions, as well as to identify important causes of emittance growth, and their scaling with charge. Multi-bunch operation will conclude testing of the Mark 1 RF gun, and allow verification of code predictions, direct measurement of bunch-to-bunch effects, and initial implementation compensation mechanisms. Modeling will continue and focus on supporting the commissioning and experimental program, as well as seeking to improve all facets of linac produced Compton gamma-rays.

  19. Roselle (Hibiscus sabdariffa) seed oil is a rich source of gamma-tocopherol.

    PubMed

    Mohamed, R; Fernández, J; Pineda, M; Aguilar, M

    2007-04-01

    The antioxidant potential of roselle (Hibiscus sabdariffa L.) extracts was studied. Different plant organs, including seeds, stems, leaves, and sepals, were analyzed with respect to their water-soluble antioxidant capacity, lipid-soluble antioxidant capacity, and tocopherol content, revealing that roselle seeds are a good source of lipid-soluble antioxidants, particularly gamma-tocopherol. Roselle seed oil was extracted and characterized, and its physicochemical parameters are summarized: acidity, 2.24%; peroxide index, 8.63 meq/kg; extinction coefficients at 232 (k(232)) and 270 nm (k(270)), 3.19 and 1.46, respectively; oxidative stability, 15.53 h; refractive index, 1.477; density, 0.92 kg/L; and viscosity, 15.9 cP. Roselle seed oil belongs to the linoleic/oleic category, its most abundant fatty acids being C18:2 (40.1%), C18:1 (28%), C16:0 (20%), C18:0 (5.3%), and C19:1 (1.7%). Sterols include beta-sitosterol (71.9%), campesterol (13.6%), Delta-5-avenasterol (5.9%), cholesterol (1.35%), and clerosterol (0.6%). Total tocopherols were detected at an average concentration of 2000 mg/kg, including alpha-tocopherol (25%), gamma-tocopherol (74.5%), and delta-tocopherol (0.5%). The global characteristics of roselle seed oil suggest that it could have important industrial applications, adding to the traditional use of roselle sepals in the elaboration of karkade tea.

  20. X-ray intensity and source size characterizations for the 25 kV upgraded Manson source at Sandia National Laboratories

    NASA Astrophysics Data System (ADS)

    Loisel, G.; Lake, P.; Gard, P.; Dunham, G.; Nielsen-Weber, L.; Wu, M.; Norris, E.

    2016-11-01

    At Sandia National Laboratories, the x-ray generator Manson source model 5 was upgraded from 10 to 25 kV. The purpose of the upgrade is to drive higher characteristics photon energies with higher throughput. In this work we present characterization studies for the source size and the x-ray intensity when varying the source voltage for a series of K-, L-, and M-shell lines emitted from Al, Y, and Au elements composing the anode. We used a 2-pinhole camera to measure the source size and an energy dispersive detector to monitor the spectral content and intensity of the x-ray source. As the voltage increases, the source size is significantly reduced and line intensity is increased for the three materials. We can take advantage of the smaller source size and higher source throughput to effectively calibrate the suite of Z Pulsed Power Facility crystal spectrometers.

  1. A High-Intensity, RF Plasma-Sputter Negative Ion Source

    SciTech Connect

    Alton, G.D.; Bao, Y.; Cui, B.; Lohwasser, R.; Reed, C.A.; Zhang, T.

    1999-03-02

    A high-intensity, plasma-sputter negative-ion source based on the use of RF power for plasma generation has been developed that can be operated in either pulsed or dc modes. The source utilizes a high-Q, self-igniting, inductively coupled antenna system, operating at 80 MHz that has been optimized to generate Cs-seeded plasmas at low pressures (typically, <1 mTorr for Xe). The source is equipped with a 19-mm diameter spherical-sector cathode machined from the desired material. To date, the source has been utilized to generate dc negative-ion beams from a variety of species, including: C{sup {minus}}(610 {micro}A); F{sup {minus}}(100 {micro}A); Si{sup {minus}}(500 {micro}A); S{sup {minus}}(500 {micro}A); P{sup {minus}}(125 {micro}A); Cl{sup {minus}}(200 {micro}A); Ni{sup {minus}}(150 {micro}A); Cu{sup {minus}}(230 {micro}A); Ge{sup {minus}}(125 {micro}A); As{sup {minus}}(100 {micro}A); Se{sup {minus}}(200 {micro}A); Ag{sup {minus}}(70 {micro}A); Pt{sup {minus}}(125 {micro}A); Au{sup {minus}}(250 {micro}A). The normalized emittance {var_epsilon}{sub n} of the source at the 80% contour is: {var_epsilon}{sub n} = 7.5 mm.mrad.(MeV){sup 1/2}. The design principles of the source, operational parameters, ion optics, emittance and intensities for a number of negative-ion species will be presented in this report.

  2. Tsunami Source Identification on the 1867 Tsunami Event Based on the Impact Intensity

    NASA Astrophysics Data System (ADS)

    Wu, T. R.

    2014-12-01

    The 1867 Keelung tsunami event has drawn significant attention from people in Taiwan. Not only because the location was very close to the 3 nuclear power plants which are only about 20km away from the Taipei city but also because of the ambiguous on the tsunami sources. This event is unique in terms of many aspects. First, it was documented on many literatures with many languages and with similar descriptions. Second, the tsunami deposit was discovered recently. Based on the literatures, earthquake, 7-meter tsunami height, volcanic smoke, and oceanic smoke were observed. Previous studies concluded that this tsunami was generated by an earthquake with a magnitude around Mw7.0 along the Shanchiao Fault. However, numerical results showed that even a Mw 8.0 earthquake was not able to generate a 7-meter tsunami. Considering the steep bathymetry and intense volcanic activities along the Keelung coast, one reasonable hypothesis is that different types of tsunami sources were existed, such as the submarine landslide or volcanic eruption. In order to confirm this scenario, last year we proposed the Tsunami Reverse Tracing Method (TRTM) to find the possible locations of the tsunami sources. This method helped us ruling out the impossible far-field tsunami sources. However, the near-field sources are still remain unclear. This year, we further developed a new method named 'Impact Intensity Analysis' (IIA). In the IIA method, the study area is divided into a sequence of tsunami sources, and the numerical simulations of each source is conducted by COMCOT (Cornell Multi-grid Coupled Tsunami Model) tsunami model. After that, the resulting wave height from each source to the study site is collected and plotted. This method successfully helped us to identify the impact factor from the near-field potential sources. The IIA result (Fig. 1) shows that the 1867 tsunami event was a multi-source event. A mild tsunami was trigged by a Mw7.0 earthquake, and then followed by the submarine

  3. Timing and Fermi LAT Analysis of Four Millisecond Pulsars Discovered in Parkes Radio Searches of Gamma-ray Sources

    NASA Astrophysics Data System (ADS)

    Ray, Paul S.; Ransom, Scott M.; Camilo, Fernando M.; Kerr, Matthew; Reynolds, John; Sarkissian, John; Freire, Paulo; Thankful Cromartie, H.; Barr, Ewan D.

    2016-01-01

    We present phase-connected timing solutions for four binary millisecond pulsars discovered in searches of Fermi LAT gamma-ray sources using the Parkes radio telescope. Follow-up timing observations of PSRs J0955-6150, J1012-4235, J1036-8317, and J1946-5403 have yielded timing models with precise orbital and astrometric parameters. For each pulsar, we also did a gamma-ray spectral analysis using LAT Pass 8 data and generated photon probabilities for use in a weighted H-test pulsation test. In all 4 cases, we detect significant gamma-ray pulsations, confirming the identification with the gamma-ray source originally targeted in the discovery observations. We describe the results of the pulse timing and gamma-ray spectral and timing analysis and the characteristics of each of the systems. The Fermi-LAT Collaboration acknowledges support for LAT development, operation and data analysis from NASA and DOE (United States), CEA/Irfu and IN2P3/CNRS (France), ASI and INFN (Italy), MEXT, KEK, and JAXA (Japan), and the K.A. Wallenberg Foundation, the Swedish Research Council and the National Space Board (Sweden). Science analysis support in the operations phase from INAF (Italy) and CNES (France) is also gratefully acknowledged. NRL participation was funded by NASA.

  4. Five New Millisecond Pulsars from a Radio Survey of 14 Unidentified Fermi-LAT Gamma-Ray Sources

    NASA Technical Reports Server (NTRS)

    Kerr, M.; Camilo, F.; Johnson, T. J.; Ferrara, E. C.; Guillemot, L.; Harding, A. K.; Hessels, J.; Johnson, S.; Keith, M.; Kramer, M.; Ransom, S. M.; Ray, P. S.; Reynolds, J. E.; Sarkissian, J.; Wood, K. S.

    2012-01-01

    We have discovered five millisecond pulsars (MSPs) in a survey of 14 unidentified Ferm;'LAT sources in the southern sky using the Parkes radio telescope. PSRs J0101-6422, J1514-4946, and J1902-5105 reside in binaries, while PSRs J1658-5324 and J1747-4036 are isolated. Using an ephemeris derived from timing observations of PSR JOl01-6422 (P=2.57ms, DH=12pc/cubic cm ), we have detected gamma-ray pulsations and measured its proper motion. Its gamma-ray spectrum (a power law of Gamma = 0.9 with a cutoff at 1.6 GeV) and efficiency are typical of other MSPs, but its radio and gamma-ray light curves challenge simple geometric models of emission. The high success rate of this survey -- enabled by selecting gamma-ray sources based on their detailed spectral characteristics -- and other similarly successful searches indicate that a substantial fraction of the local population of MSPs may soon be known.

  5. A microchip laser source with stable intensity and frequency used for self-mixing interferometry.

    PubMed

    Zhang, Shaohui; Zhang, Shulian; Tan, Yidong; Sun, Liqun

    2016-05-01

    We present a stable 40 × 40 × 30 mm(3) Laser-diode (LD)-pumped-microchip laser (ML) laser source used for self-mixing interferometry which can measure non-cooperative targets. We simplify the coupling process of pump light in order to make its polarization and intensity robust against environmental disturbance. Thermal frequency stabilization technology is used to stabilize the laser frequency of both LD and ML. Frequency stability of about 1 × 10(-7) and short-term intensity fluctuation of 0.1% are achieved. The theoretical long-term displacement accuracy limited by frequency and intensity fluctuation is about 10 nm when the measuring range is 0.1 m. The line-width of this laser is about 25 kHz corresponding to 12 km coherent length and 6 km measurement range for self-mixing interference. The laser source has been equipped to a self-mixing interferometer, and it works very well. PMID:27250399

  6. Report of the Snowmass M6 Working Group on high intensity proton sources

    SciTech Connect

    Weiren Chou and J. Wei

    2002-08-20

    The U.S. high-energy physics program needs an intense proton source, a 1-4 MW Proton Driver (PD), by the end of this decade. This machine will serve as a stand-alone facility that will provide neutrino superbeams and other high intensity secondary beams such as kaons, muons, neutrons, and anti-protons (cf. E1 and E5 group reports) and also serve as the first stage of a neutrino factory (cf. M1 group report). It can also be a high brightness source for a VLHC. Based on present accelerator technology and project construction experience, it is both feasible and cost-effective to construct a 1-4 MW Proton Driver. Two recent PD design studies have been made, one at FNAL and the other at the BNL. Both designed PD's for 1 MW proton beams at a cost of about U.S. $200M (excluding contingency and overhead) and both designs were upgradeable to 4 MW. An international collaboration between FNAL, BNL and KEK on high intensity proton facilities is addressing a number of key design issues. The superconducting (sc) RF cavities, cryogenics, and RF controls developed for the SNS can be directly adopted to save R&D efforts, cost, and schedule. PD studies are also actively being pursued at Europe and Japan.

  7. Exploring the nature of the unidentified very-high-energy gamma-ray source HESS J1507-622

    NASA Astrophysics Data System (ADS)

    Domainko, W.; Ohm, S.

    2012-09-01

    Context. Several extended sources of very-high-energy (VHE; E > 100 GeV) gamma rays have been found that lack counterparts belonging to an established class of VHE gamma-ray emitters. Aims: The nature of the first unidentified VHE gamma-ray source with significant angular offset from the Galactic plane of 3.5°, HESS J1507-622, is explored. Methods.Fermi-LAT data in the high-energy (HE, 100 MeV < E < 100 GeV) gamma-ray range collected over 34 month are used to describe the spectral energy distribution (SED) of the source. Additionally, implications of the off-plane location of the source for a leptonic and hadronic gamma-ray emission model are investigated. Results: HESS J1507-622 is detected in the Fermi energy range and its spectrum is best described by a power law in energy with Γ = 1.7 ± 0.1stat ± 0.2sys and integral flux between (0.3-300) GeV of F = (2.0 ± 0.5stat ± 1.0sys) × 10-9 cm-2 s-1. The SED constructed from the Fermi and H.E.S.S. data for this source does not support a smooth power-law continuation from the VHE to the HE gamma-ray range. With the available data it is not possible to discriminate between a hadronic and a leptonic scenario for HESS J1507-622. The location and compactness of the source indicate a considerable physical offset from the Galactic plane for this object. In case of a multiple-kpc distance, this challenges a pulsar wind nebula (PWN) origin for HESS J1507-622 since the time of travel for a pulsar born in the Galactic disk to reach such a location would exceed the inverse Compton (IC) cooling time of electrons that are energetic enough to produce VHE gamma-rays. However, an origin of this gamma-ray source connected to a pulsar that was born off the Galactic plane in the explosion of a hypervelocity star cannot be excluded. Conclusions: The nature of HESS J1507-622 is still unknown to date, and a PWN scenario cannot be ruled out in general. On the contrary HESS J1507-622 could be the first discovered representative of a

  8. MOPA FEL Scheme as a Source of Primary Photons for Gamma-Gamma Collider at TESLA and SBLC

    NASA Astrophysics Data System (ADS)

    Saldin, E. L.; Schneidmiller, E. A.; Yurkov, M. V.

    1997-05-01

    The project of a Linear Collider (TESLA and SBLC options) is developed by the international TESLA collaboration. This project includes the second interaction region for γ γ and γe collisions as an additional option. High energy gamma-quanta are produced in the process of Compton backscattering of the laser photons on the electrons of the main linear accelerator. In the present study of the Linear Collider Project it has been accepted to use Master Oscillator -- Power Amplifier (MOPA) free electron laser (FEL) scheme as a laser system. In this scheme the optical pulse from Nd glass laser (λ = 1 μm, 1 MW peak power) is amplified by FEL amplifier up to the power of about 500 GW. These parameters of the laser system allows one to obtain 70 % conversion efficiency of the electrons into high energy gamma-quanta. The driving beam for the FEL amplifier is produced by the linear rf accelerator identical to the main accelerator, but with lower accelerating gradient due to higher beam load. Such a choice fits well to both TESLA and SBLC options. It is important that the requirements to the parameters of the FEL driving electron beam are rather moderate and can be provided by injector consisting of gridded thermoionic gun and subharmonic buncher.

  9. SOILD: A computer model for calculating the effective dose equivalent from external exposure to distributed gamma sources in soil

    SciTech Connect

    Chen, S.Y.; LePoire, D.; Yu, C. ); Schafetz, S. ); Mehta, P. )

    1991-01-01

    The SOLID computer model was developed for calculating the effective dose equivalent from external exposure to distributed gamma sources in soil. It is designed to assess external doses under various exposure scenarios that may be encountered in environmental restoration programs. The models four major functional features address (1) dose versus source depth in soil, (2) shielding of clean cover soil, (3) area of contamination, and (4) nonuniform distribution of sources. The model is also capable of adjusting doses when there are variations in soil densities for both source and cover soils. The model is supported by a data base of approximately 500 radionuclides. 4 refs.

  10. 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.

  11. Investigating the peculiar emission from the new VHE gamma-ray source H1722+119

    NASA Astrophysics Data System (ADS)

    Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Banerjee, B.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Buson, S.; Carosi, A.; Chatterjee, A.; Clavero, R.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; 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.; Fallah Ramazani, V.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giammaria, P.; Godinović, N.; González Muñoz, A.; Gora, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Hanabata, Y.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Hughes, G.; Idec, W.; Kodani, K.; Konno, Y.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; Majumdar, P.; Makariev, M.; Mallot, K.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Moretti, E.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nilsson, K.; Nishijima, K.; Noda, K.; Nogués, L.; Orito, R.; Overkemping, A.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Pedaletti, G.; Perri, L.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Rhode, W.; Ribó, M.; Rico, J.; Rodriguez Garcia, J.; Saito, T.; Satalecka, K.; Schultz, C.; Schweizer, T.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Stamerra, A.; Steinbring, T.; Strzys, M.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Torres, D. F.; Toyama, T.; Treves, A.; Verguilov, V.; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zanin, R.; D'Ammando, F.; Berdyugin, A.; Hovatta, T.; Max-Moerbeck, W.; Raiteri, C. M.; Readhead, A. C. S.; Reinthal, R.; Richards, J. L.; Verrecchia, F.; Villata, M.

    2016-07-01

    The Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes observed the BL Lac object H1722+119 (redshift unknown) for six consecutive nights between 2013 May 17 and 22, for a total of 12.5 h. The observations were triggered by high activity in the optical band measured by the KVA (Kungliga Vetenskapsakademien) telescope. The source was for the first time detected in the very high energy (VHE, E > 100 GeV) γ-ray band with a statistical significance of 5.9σ. The integral flux above 150 GeV is estimated to be (2.0 ± 0.5) per cent of the Crab nebula flux. We used contemporaneous high energy (HE, 100 MeV < E < 100 GeV) γ-ray observations from Fermi-Large Area Telescope to estimate the redshift of the source. Within the framework of the current extragalactic background light models, we estimate the redshift to be z = 0.34 ± 0.15. Additionally, we used contemporaneous X-ray to radio data collected by the instruments on board the Swift satellite, the KVA, and the Owens Valley Radio Observatory telescope to study multifrequency characteristics of the source. We found no significant temporal variability of the flux in the HE and VHE bands. The flux in the optical and radio wavebands, on the other hand, did vary with different patterns. The spectral energy distribution of H1722+119 shows surprising behaviour in the ˜3 × 1014-1018 Hz frequency range. It can be modelled using an inhomogeneous helical jet synchrotron self-Compton model.

  12. Transverse Beam Halo Measurements at High Intensity Neutrino Source (HINS) using Vibrating Wire Monitor

    SciTech Connect

    Chung, M.; Hanna, B.; Scarpine, V.; Shiltsev, V.; Steimel, J.; Artinian, S.; Arutunian, S.

    2015-02-26

    The measurement and control of beam halos will be critical for the applications of future high-intensity hadron linacs. In particular, beam profile monitors require a very high dynamic range when used for the transverse beam halo measurements. In this study, the Vibrating Wire Monitor (VWM) with aperture 60 mm was installed at the High Intensity Neutrino Source (HINS) front-end to measure the transverse beam halo. A vibrating wire is excited at its resonance frequency with the help of a magnetic feedback loop, and the vibrating and sensitive wires are connected through a balanced arm. The sensitive wire is moved into the beam halo region by a stepper motor controlled translational stage. We study the feasibility of the vibrating wire for the transverse beam halo measurements in the low-energy front-end of the proton linac.

  13. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H.

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant. These detectors, based on silicon carbide (SiC) semiconductor are designed to have larger active volumes than previously available SiC detectors, and are being tested for their response to alpha particles, X-rays and low energy gamma rays, and fast neutrons. Specifically, SiC radiation detectors with larger areas and 100-micrometer thick active regions have been designed and manufactured according to detector-design specifications. Detectors based on a Schottky diode design were specified in order to minimize the effects of the detector entrance window on alpha particle measurements. During manufacture of the Schottky diodes, the manufacturer also provided a set of large-volume SiC p-i-n diodes for testing Extensive alpha particle measurements have been carried out to test and quantify the response of the SiC Schottky diodes. Exposures to 148-Gd, 213-Po, 217-At, 221-Fr, 225-Ac, 237-Np, 238-Pu, 240-Pu, and 242-Pu sources were used to obtain detailed alpha response data in the alpha energy range from 3182.787 keV to 8375.9 ke

  14. An intense, high-repetition nanosecond light source using a commercially available Xe-arc lamp

    NASA Astrophysics Data System (ADS)

    Araki, Tsutomu; Yamada, Akihisa; Uchida, Teruo

    1993-07-01

    We describe the construction and emission characteristics of a Xe light source that produces broadband emission spectrum (250-650 nm) and high-repetition pulsed light of nanosecond duration. The standard dc-operated Xe-arc lamp, which is commercially available, is employed as the primary light source, with modified circuitry to realize pulsed operation. A dc voltage higher than 5 kV is applied to the electrode gap through a high-value resistor in order to generate a periodical discharge of current between the electrode gap. In order to further increase the intensity of the light pulses, the electrical polarity of the electrode must be in inverse connection relative to the normal connection under the dc operation. Intense light pulses as large as 20 W (peak value) of 3 ns width were generated repetitively from the Xe lamp. Fluorescence lifetimes of a quinine-sulfate solution and a fluorescent cell nucleus were measured to demonstrate the usefulness of the light source.

  15. The study towards high intensity high charge state laser ion sources.

    PubMed

    Zhao, H Y; Jin, Q Y; Sha, S; Zhang, J J; Li, Z M; Liu, W; Sun, L T; Zhang, X Z; Zhao, H W

    2014-02-01

    As one of the candidate ion sources for a planned project, the High Intensity heavy-ion Accelerator Facility, a laser ion source has been being intensively studied at the Institute of Modern Physics in the past two years. The charge state distributions of ions produced by irradiating a pulsed 3 J/8 ns Nd:YAG laser on solid targets of a wide range of elements (C, Al, Ti, Ni, Ag, Ta, and Pb) were measured with an electrostatic ion analyzer spectrometer, which indicates that highly charged ions could be generated from low-to-medium mass elements with the present laser system, while the charge state distributions for high mass elements were relatively low. The shot-to-shot stability of ion pulses was monitored with a Faraday cup for carbon target. The fluctuations within ±2.5% for the peak current and total charge and ±6% for pulse duration were demonstrated with the present setup of the laser ion source, the suppression of which is still possible.

  16. The study towards high intensity high charge state laser ion sources.

    PubMed

    Zhao, H Y; Jin, Q Y; Sha, S; Zhang, J J; Li, Z M; Liu, W; Sun, L T; Zhang, X Z; Zhao, H W

    2014-02-01

    As one of the candidate ion sources for a planned project, the High Intensity heavy-ion Accelerator Facility, a laser ion source has been being intensively studied at the Institute of Modern Physics in the past two years. The charge state distributions of ions produced by irradiating a pulsed 3 J/8 ns Nd:YAG laser on solid targets of a wide range of elements (C, Al, Ti, Ni, Ag, Ta, and Pb) were measured with an electrostatic ion analyzer spectrometer, which indicates that highly charged ions could be generated from low-to-medium mass elements with the present laser system, while the charge state distributions for high mass elements were relatively low. The shot-to-shot stability of ion pulses was monitored with a Faraday cup for carbon target. The fluctuations within ±2.5% for the peak current and total charge and ±6% for pulse duration were demonstrated with the present setup of the laser ion source, the suppression of which is still possible. PMID:24593615

  17. Intense antineutrino source based on a lithium converter. Proposal for a promising experiment for studying oscillations

    NASA Astrophysics Data System (ADS)

    Lyashuk, V. I.; Lutostansky, Yu. S.

    2016-03-01

    An intense electron-antineutrino source with a hard spectrum (E_{{{tilde v}_e}}^{max} = 13 MeV and < {{E_{{{tilde v}_e}}}} rangle = 6.5MeV) can be created on the basis of the short-lived isotope 8Li (β--decay, T 1/2 = 0.84 s) formed via the ( n, γ) activation of 7Li. In contrast to a reactor antineutrino spectrum whose uncertainty is large, particularly in the high-energy region {E_{{{tilde v}_e}}} > 6 MeV, which is experimentally relevant, the lithium {tilde v_e} spectrum is accurately determined. The proposed accelerator-driven experimental scheme with a neutron-producing target and a lithium converter as an intense {tilde v_e} source is an alternative to a nuclear reactor. The required amount of high-purity 7Li will be reduced in many times by using the suggested heavy-water LiOD solutions. A possible experiment involving the lithium source on search for sterile neutrinos in the mass region Δ m 2 ≥ 0.2 eV2 with a very high sensitivity to mixing-angle values down to sin2(2Θ) ≈ (7-10) × 10-4 at the 95% C.L. has been considered.

  18. SU-E-I-79: Source Geometry Dependence of Gamma Well-Counter Measurements

    SciTech Connect

    Park, M; Belanger, A; Kijewski, M

    2015-06-15

    Purpose: To determine the effect of liquid sample volume and geometry on counting efficiency in a gamma well-counter, and to assess the relative contributions of sample geometry and self-attenuation. Gamma wellcounters are standard equipment in clinical and preclinical studies, for measuring patient blood radioactivity and quantifying animal tissue uptake for tracer development and other purposes. Accurate measurements are crucial. Methods: Count rates were measured for aqueous solutions of 99m- Tc at four liquid volume values in a 1-cm-diam tube and at six volume values in a 2.2-cm-diam vial. Total activity was constant for all volumes, and data were corrected for decay. Count rates from a point source in air, supported by a filter paper, were measured at seven heights between 1.3 and 5.7 cm from the bottom of a tube. Results: Sample volume effects were larger for the tube than for the vial. For the tube, count efficiency relative to a 1-cc volume ranged from 1.05 at 0.05 cc to 0.84 at 3 cc. For the vial, relative count efficiency ranged from 1.02 at 0.05 cc to 0.87 at 15 cc. For the point source, count efficiency relative to 1.3 cm from the tube bottom ranged from 0.98 at 1.8 cm to 0.34 at 5.7 cm. The relative efficiency of a 3-cc liquid sample in a tube compared to a 1-cc sample is 0.84; the average relative efficiency for the solid sample in air between heights in the tube corresponding to the surfaces of those volumes (1.3 and 4.8 cm) is 0.81, implying that the major contribution to efficiency loss is geometry, rather than attenuation. Conclusion: Volume-dependent correction factors should be used for accurate quantitation radioactive of liquid samples. Solid samples should be positioned at the bottom of the tube for maximum count efficiency.

  19. The detector response matrices of the burst and transient source experiment (BATSE) on the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Pendleton, Geoffrey N.; Paciesas, William S.; Mallozzi, Robert S.; Koshut, Tom M.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Horack, John M.; Lestrade, John Patrick

    1995-01-01

    The detector response matrices for the Burst And Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory (CGRO) are described, including their creation and operation in data analysis. These response matrices are a detailed abstract representation of the gamma-ray detectors' operating characteristics that are needed for data analysis. They are constructed from an extensive set of calibration data coupled with a complex geometry electromagnetic cascade Monte Carlo simulation code. The calibration tests and simulation algorithm optimization are described. The characteristics of the BATSE detectors in the spacecraft environment are also described.

  20. Numerical simulation of a triode source of intense radial converging electron beam

    NASA Astrophysics Data System (ADS)

    Altsybeyev, V.; Engelko, V.; Ovsyannikov, A.; Ovsyannikov, D.; Ponomarev, V.; Fetzer, R.; Mueller, G.

    2016-10-01

    The results of numerical simulations of a triode source of an intense radial converging electron beam are presented. The role of the initial transverse velocity of electrons, defocusing effect of the controlling grid, the beam self-magnetic field, backscattering of electrons, and ion flow from the target is analyzed. It was found that the ion flow from the target essentially increases the value of the electron current. The influence of the beam self-magnetic field on electron trajectories leads to the fact that there is a critical value of the cathode-grid voltage dividing the mode of the source operation into stable and unstable. The influence of initial transverse electron energies on the beam focusing is essentially higher than the influence of the controlling grid. Backscattering of the beam electrons from the target surface increases the target ion current so that the source operation may become unstable and the distribution of the beam power density on the target becomes nonuniform with a maximum in the center. Electrons passing by the target drift along the source axis. This leads to diminishing the power density at the center of the target and to the exit of peripheral electrons from the source. Conditions for achieving required electron beam parameters (the electron kinetic energy—120 keV, the beam energy density on the target ˜40 J/cm2 on a maximum possible length of the target surface) were determined.

  1. Uncertainties and biases of source masses derived from fits of integrated fluxes or image intensities

    NASA Astrophysics Data System (ADS)

    Men'shchikov, A.

    2016-09-01

    Fitting spectral distributions of total fluxes or image intensities are two standard methods for estimating the masses of starless cores and protostellar envelopes. These mass estimates, which are the main source and basis of our knowledge of the origin and evolution of self-gravitating cores and protostars, are uncertain. It is important to clearly understand sources of statistical and systematic errors stemming from the methods and minimize the errors. In this model-based study, a grid of radiative transfer models of starless cores and protostellar envelopes was computed and their total fluxes and image intensities were fitted to derive the model masses. To investigate intrinsic effects related to the physical objects, all observational complications were explicitly ignored. Known true values of the numerical models allow assessment of the qualities of the methods and fitting models, as well as the effects of nonuniform temperatures, far-infrared opacity slope, selected subsets of wavelengths, background subtraction, and angular resolutions. The method of fitting intensities gives more accurate masses for more resolved objects than the method of fitting fluxes. With the latter, a fitting model that assumes optically thin emission gives much better results than the one allowing substantial optical depths. Temperature excesses within the objects above the mass-averaged values skew their spectral shapes towards shorter wavelengths, leading to masses underestimated typically by factors 2-5. With a fixed opacity slope deviating from the true value by a factor of 1.2, masses are inaccurate within a factor of 2. The most accurate masses are estimated by fitting just two or three of the longest wavelength measurements. Conventional algorithm of background subtraction is a likely source of large systematic errors. The absolute values of masses of the unresolved or poorly resolved objects in star-forming regions are uncertain to within at least a factor of 2-3.

  2. Reactor target from metal chromium for "pure" high-intensive artificial neutrino source

    NASA Astrophysics Data System (ADS)

    Gavrin, V. N.; Kozlova, Yu. P.; Veretenkin, E. P.; Logachev, A. V.; Logacheva, A. I.; Lednev, I. S.; Okunkova, A. A.

    2016-03-01

    The paper presents the first results of development of manufacturing technology of metallic chromium targets from highly enriched isotope 50Cr for irradiation in a high flux nuclear reactor to obtain a compact high intensity neutrino source with low content of radionuclide impurities and minimum losses of enriched isotope. The main technological stages are the hydrolysis of chromyl fluoride, the electrochemical reduction of metallic chromium, the hot isostatic pressing of chromium powder and the electrical discharge machining of chromium bars. The technological stages of hot isostatic pressing of chromium powder and of electrical discharge machining of Cr rods have been tested.

  3. A fast chopper for the Fermilab High Intensity Neutrino Source (HINS)

    SciTech Connect

    Madrak, R.; Wildman, D.; Dymokde-Bradshaw, A.; Hares, J.; Kellett, P.

    2008-10-01

    A fast chopper capable of kicking single 2.5 MeV H-bunches spaced at 325 MHz, at rates greater than 50 MHz is needed for the Fermilab High Intensity Neutrino Source (HINS) [1]. Four 1.2 kV fast pulsers, designed and manufactured by Kentech Instruments Ltd., will drive a 0.5 m long meander made from a copper plated ceramic composite. Test results showing pulses from the first 1.2 kV pulser and meander results will be presented.

  4. Development of target system for intense neutron source of p-Li reaction.

    PubMed

    Kamada, So; Takada, Masashi; Suda, Mitsuru; Hamano, Tsuyoshi; Imaseki, Hitoshi; Hoshi, Masaharu; Fujii, Ryo; Nakamura, Masaru; Sato, Hitoshi; Higashimata, Atsushi; Arai, Seiji

    2014-06-01

    A target cooling system was developed for an intense neutron source of p-Li reaction. The system consists of target cooling devices and protection devices for lithium evaporation. A pin-structure cooling device was developed to enhance cooling power. Functional graded material was utilized for the evaporation of lithium. Test experiments were performed by using the neutron exposure accelerator system for biological effect experiments (NASBEE) at the National Institute of Radiological Sciences (NIRS) in Japan. The target system was confirmed to be applicable for accelerator-based boron neutron capture therapy.

  5. MeV negative ion source from ultra-intense laser-matter interaction

    SciTech Connect

    Ter-Avetisyan, S.; Ramakrishna, B.; Doria, D.; Prasad, R.; Borghesi, M.; Andreev, A. A.; Steinke, S.; Schnuerer, M.; Nickles, P. V.; Tikhonchuk, V.

    2012-02-15

    Experimental demonstration of negative ion acceleration to MeV energies from sub-micron size droplets of water spray irradiated by ultra-intense laser pulses is presented. Thanks to the specific target configuration and laser parameters, more than 10{sup 9} negative ions per steradian solid angle in 5% energy bandwidth are accelerated in a stable and reliable manner. To our knowledge, by virtue of the ultra-short duration of the emission, this is by far the brightest negative ion source reported. The data also indicate the existence of beams of neutrals with at least similar numbers and energies.

  6. High-Intensity Continuous Wave Slow Positron Source at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Golge, Serkan; Vlahovic, Branislav; Wojtsekhowski, Bogdan

    2013-04-01

    We present a novel concept of an electron linac-based slow positron source with projected intensity on the order of 10^10 slow e^+/s. The key components of this concept are a Continuous Wave (CW) electron beam, a rotating positron-production target, a synchronized raster/anti-raster, a transport channel, and extraction of positrons into a field-free area through a magnetic field terminator plug for moderation in a solid Neon moderator. The feasibility calculations were completed in the framework of GEANT4 simulation and OPERA-3D magnetic field calculation code.

  7. Data acquisition system for the neutron scattering instruments at the intense pulsed neutron source

    SciTech Connect

    Crawford, R.K.; Daly, R.T.; Haumann, J.R.; Hitterman, R.L.; Morgan, C.B.; Ostrowski, G.E.; Worlton, T.G.

    1981-01-01

    The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a major new user-oriented facility which is now coming on line for basic research in neutron scattering and neutron radiation damage. This paper describes the data-acquisition system which will handle data acquisition and instrument control for the time-of-flight neutron-scattering instruments at IPNS. This discussion covers the scientific and operational requirements for this system, and the system architecture that was chosen to satisfy these requirements. It also provides an overview of the current system implementation including brief descriptions of the hardware and software which have been developed.

  8. CANGAROO-III Observation of TeV Gamma Rays from the Unidentified Gamma-Ray Source HESS J1614-518

    NASA Astrophysics Data System (ADS)

    Mizukami, T.; Kubo, H.; Yoshida, T.; Nakamori, T.; Enomoto, R.; Tanimori, T.; Akimoto, M.; Bicknell, G. V.; Clay, R. W.; Edwards, P. G.; Gunji, S.; Hara, S.; Hara, T.; Hayashi, S.; Ishioka, H.; Kabuki, S.; Kajino, F.; Katagiri, H.; Kawachi, A.; Kifune, T.; Kiuchi, R.; Kunisawa, T.; Kushida, J.; Matoba, T.; Matsubara, Y.; Matsuzawa, I.; Mizumura, Y.; Mizumoto, Y.; Mori, M.; Muraishi, H.; Naito, T.; Nakayama, K.; Nishijima, K.; Ohishi, M.; Otake, Y.; Ryoki, S.; Saito, K.; Sakamoto, Y.; Stamatescu, V.; Suzuki, T.; Swaby, D. L.; Thornton, G.; Tokanai, F.; Toyota, Y.; Tsuchiya, K.; Yanagita, S.; Yokoe, Y.; Yoshikoshi, T.; Yukawa, Y.

    2011-10-01

    We report the detection, with the CANGAROO-III imaging atmospheric Cherenkov telescope array, of a very high energy gamma-ray signal from the unidentified gamma-ray source HESS J1614-518, which was discovered in the H.E.S.S. Galactic plane survey. Diffuse gamma-ray emission was detected above 760 GeV at the 8.9σ level during an effective exposure of 54 hr from 2008 May to August. The spectrum can be represented by a power law: (8.2 ± 2.2stat ± 2.5sys) × 10-12 × (E/1 TeV)-γ cm-2 s-1 TeV-1 with a photon index γ of 2.4 ± 0.3stat ± 0.2sys, which is compatible with that of the H.E.S.S. observations. By combining our result with multiwavelength data, we discuss the possible counterparts for HESS J1614-518 and consider radiation mechanisms based on hadronic and leptonic processes for a supernova remnant (SNR), stellar winds from massive stars, and a pulsar wind nebula (PWN). Although a leptonic origin from a PWN driven by an unknown pulsar remains possible, hadronic-origin emission from an unknown SNR is preferred.

  9. Comparison of EEG and MEG in source localization of induced human gamma-band oscillations during visual stimulus.

    PubMed

    Mideksa, K G; Hoogenboom, N; Hellriegel, H; Krause, H; Schnitzler, A; Deuschl, G; Raethjen, J; Heute, U; Muthuraman, M

    2015-08-01

    High frequency gamma oscillations are indications of information processing in cortical neuronal networks. Recently, non-invasive detection of these oscillations have become one of the main research areas in magnetoencephalography (MEG) and electroencephalography (EEG) studies. The aim of this study, which is a continuation of our previous MEG study, is to compare the capability of the two modalities (EEG and MEG) in localizing the source of the induced gamma activity due to a visual stimulus, using a spatial filtering technique known as dynamic imaging of coherent sources (DICS). To do this, the brain activity was recorded using simultaneous MEG and EEG measurement and the data were analyzed with respect to time, frequency, and location of the strongest response. The spherical head modeling technique, such as, the three-shell concentric spheres and an overlapping sphere (local sphere) have been used as a forward model to calculate the external electromagnetic potentials and fields recorded by the EEG and MEG, respectively. Our results from the time-frequency analysis, at the sensor level, revealed that the parieto-occipital electrodes and sensors from both modalities showed a clear and sustained gamma-band activity throughout the post-stimulus duration and that both modalities showed similar strongest gamma-band peaks. It was difficult to interpret the spatial pattern of the gamma-band oscillatory response on the scalp, at the sensor level, for both modalities. However, the source analysis result revealed that MEG3 sensor type, which measure the derivative along the longitude, showed the source more focally and close to the visual cortex (cuneus) as compared to that of the EEG.

  10. Comparison of EEG and MEG in source localization of induced human gamma-band oscillations during visual stimulus.

    PubMed

    Mideksa, K G; Hoogenboom, N; Hellriegel, H; Krause, H; Schnitzler, A; Deuschl, G; Raethjen, J; Heute, U; Muthuraman, M

    2015-08-01

    High frequency gamma oscillations are indications of information processing in cortical neuronal networks. Recently, non-invasive detection of these oscillations have become one of the main research areas in magnetoencephalography (MEG) and electroencephalography (EEG) studies. The aim of this study, which is a continuation of our previous MEG study, is to compare the capability of the two modalities (EEG and MEG) in localizing the source of the induced gamma activity due to a visual stimulus, using a spatial filtering technique known as dynamic imaging of coherent sources (DICS). To do this, the brain activity was recorded using simultaneous MEG and EEG measurement and the data were analyzed with respect to time, frequency, and location of the strongest response. The spherical head modeling technique, such as, the three-shell concentric spheres and an overlapping sphere (local sphere) have been used as a forward model to calculate the external electromagnetic potentials and fields recorded by the EEG and MEG, respectively. Our results from the time-frequency analysis, at the sensor level, revealed that the parieto-occipital electrodes and sensors from both modalities showed a clear and sustained gamma-band activity throughout the post-stimulus duration and that both modalities showed similar strongest gamma-band peaks. It was difficult to interpret the spatial pattern of the gamma-band oscillatory response on the scalp, at the sensor level, for both modalities. However, the source analysis result revealed that MEG3 sensor type, which measure the derivative along the longitude, showed the source more focally and close to the visual cortex (cuneus) as compared to that of the EEG. PMID:26738178

  11. The Cosmic Rays and Gamma-Quanta Local Sources Spectra Distinction and Formation of Uniform Cosmic Ray Spectrum

    NASA Astrophysics Data System (ADS)

    Georgievna Sinitysna, Vera; Nikolsky, S. I.

    2003-07-01

    The obtained experimental data about local sources of gamma-quanta are characteristic by the following fact. Though the observed metagalactic sources (active galactic nuclei) are 106 - 107 times more powerful, unlike the galactic one, the gamma-quanta energy spectra from both galactic and metagalactic sources can be averaged with spectrum index F (> Eγ ) ˜ Eγ 1.3±0.15 . This result puts - under doubt the assumption about the galactic origin of observable cosmic ray flux. Uniform cosmic ray spectrum is forming in "infinite" number of elastic (or inelastic) collisions with relict photons in intergalactic space, where the cosmic rays are 0.999... part of their time as the common volume of extragalactic space exceeds more then thousand times the total galactic volume in Universe. Accordingly, the observable spectrum distribution has index of (2.72 ± 0.02) = 2.718..., that is Napier's number. The local sources of extra-high energy cosmic radiation search by the EAS flux excess at narrow angular interval at the direction on supposed sources did not give conformable results because of extremely low flux of showers generated by gamma-quanta, which is connected with the process of accumulation of charged particles in Metagalaxy, which includes intergalactic space. This was confirmed at experiments in the ionization calorimeter with Pb absorb ent of total EAS formed by gamma-quanta which have no muons and hadrons flux determination. The analysis of such showers showed that between EAS on observation level of 3760 m high above sea level the "no hadron" showers flux is slight 0.005 ± 0.001 of full EAS flux; "no muons" showers showed the same result at 0.004 ± 0.001 EAS with primary energy > (3 - 4)1014 eV not a single muon was observed (Fig. 1). As a consequence of small flux of EAS containing no hadrons and muons searching of high-energy gamma-quanta stellar sources it was advisable to concentrate on observations of probable high-energy gamma-quanta sources at narrow

  12. Rapid firing of printed pastes for BSF solar cell under high intensity light source

    SciTech Connect

    Okamoto, K.; Nammori, T.; Nunoi, T.; Takemoto, T.; Tsuji, T.

    1982-09-01

    This paper describes a technique of rapid firing of screen-printed aluminum paste for back surface field (BSF) solar cell under high intensity light source. Excellent antireflection coating and shallow junction were formed at the same time with a phosphoric-titanate compound solution spun over etched P-type silicon surface. An aluminum paste was printed on the rear surface of the cell. A P/sup +/ layer was formed by alloying an aluminum paste under high energy density visible light source. The silicon substrate absorbed light energy from heating lamps efficiently due to the effect of original TiO/sub 2/ anti-reflection coating. As a result, it is possible to fire an aluminum paste effectively in less than 30 seconds because of the high heating rate of the substrate.

  13. Muon catalyzed fusion in plasma state and high intensity DT fusion neutron source

    SciTech Connect

    Takahashi, Hiroshi

    1989-01-01

    dt/mu/ molecular formation rates in a plasma state of DT mixture by d and t ions are, respectively, 63 and 77 times higher than the ones by electrons. High plasma oscillation frequency in a high electron density plasma enhances the formation rate in the high temperature dt mixture. The DT muon catalyzed fusion has the ability to produce much higher intensity 14 MeV neutron source (in order of 5 /times/ 10/sup 16/n/cm/sup 2//sec) than other means of stripping and spallation approaches. Such neutrons can be used for testing of first wall material candidates for magnetic fusion reactors, for incinerating fission products (e.g., Cs/sup 137/) and for creating high thermal flux neutron sources, on the order of 10/sup 17/n/cm/sup 2//sec. 12 refs., 2 figs.

  14. On the relationship between intensity and resolution of pulsed-source back-scattering spectrometers

    SciTech Connect

    Robinson, R.A.

    1994-08-01

    In a recent paper on the high-resolution pulsed-source back-scattering spectrometer LAM-80ET, Ikeda et al. noted that the observed intensity I varies linearly with energy resolution {Delta}{epsilon}, on changing order of analyser reflection. This is apparently at variance with reactor folklore, which is based solely on phase-space arguments, in which it is assumed that I {proportional_to} {Delta}{epsilon}{sup 2}. We discuss this problem in terms of (a) resolution-volume arguments, (b) the energy dependence of source flux, (c) the appropriate jacobian for transformation from time-of-flight to energy scan, (d) a simple model for resolution of the spectrometer and (e) the wavelength variation of critical angle for the neutron guide. Making suitable simplifying approximations, we arrive at the form I {proportional_to} {Delta}{epsilon}{sup 4/3}.

  15. Loading a fountain clock with an enhanced low-velocity intense source of atoms

    NASA Astrophysics Data System (ADS)

    Dobrev, G.; Gerginov, V.; Weyers, S.

    2016-04-01

    We present experimental work for improved atom loading in the optical molasses of a cesium fountain clock, employing a low-velocity intense source of atoms [Lu et al., Phys. Rev. Lett 77, 3331 (1996), 10.1103/PhysRevLett.77.3331], which we modify by adding a dark-state pump laser. With this modification the atom source has a mean flux of 4 ×108 atoms/s at a mean atom velocity of 8.6 m/s. Compared to fountain operation using background gas loading, we achieve a significant increase of the loaded and detected atom number by a factor of 40. Operating the fountain clock with a total number of detected atoms Nat=2.9 ×106 in the quantum projection noise-limited regime, a frequency instability σy(1 s ) =2.7 ×10-14 is demonstrated.

  16. Long lifetime, low intensity light source for use in nighttime viewing of equipment maps and other writings

    DOEpatents

    Frank, Alan M.; Edwards, William R.

    1983-01-01

    A long-lifetime light source with sufficiently low intensity to be used for reading a map or other writing at nighttime, while not obscuring the user's normal night vision. This light source includes a diode electrically connected in series with a small power source and a lens properly positioned to focus at least a portion of the light produced by the diode.

  17. Possible Class of Nearby Gamma-Ray Burst/Gravitational Wave Sources

    NASA Technical Reports Server (NTRS)

    Norris, Jay P.

    2003-01-01

    A possible subclass of gamma-ray bursts - those with few, wide pulses, spectral lags of order one to several seconds, and soft spectra - has been identified. Their Log[N]-Log[Fp] distribution approximates a -3/2 power-law, suggesting homogeneity and relatively nearby sources. These mostly dim bursts account for approximately 50% of the BATSE sample of long bursts near that instrument s trigger threshold, suggesting that this subluminous class constitutes a more common variety than the more familiar burst sources which lie at truly cosmological distances. Theoretical scenarios predicted such a class, motivated by their exemplar GRB 980425 (SN 1998bw) lying at a distance of approximately 38 Mpc. The observations are explained by invoking off-axis viewing of the GRB jet and/or bulk Lorentz factors of order a few. Long-lag bursts show a tendency to concentrate near the Supergalactic Plane with a quadrupole moment of -0.10 plus or minus 0.04, similar to that for SNe type Ib/c within the same volume. The rate of the observed subluminous bursts is of order 1/4 that of SNe Ib/c. Evidence for a sequential relationship between SNe Ib/c and GRBs is critiqued for two cases, as simultaneity of the SN and GRB events may be important for detection of the expected gravitational wave signal; at most, SN to GRB delays appear to be a few days. SN asymmetries and ultrarelativistic GRB jets suggest the possibility of rapid rotation in the pre-collapse objects, a primary condition required for highly nonaxisymmetric SN collapse to produce strong gravitational waves.

  18. Proton Linac Front End for High Intensity Neutrino Source at Fermilab

    NASA Astrophysics Data System (ADS)

    Tam, Wai-Ming; Apollinari, Giorgio; Madrak, Robyn; Moretti, Alfred; Ristori, Leonardo; Romanov, Gennady; Steimel, James; Webber, Robert; Wildman, David

    2008-04-01

    Fermilab has recently proposed the construction of an 8 GeV superconducting linac for the exploration of the high intensity frontier. The High Intensity Neutrino Source (HINS) R&D program was established to explore the feasibility of certain technical solutions proposed for the front end of a high intensity linac. The low energy (˜60 MeV) section operates at 325 MHz and comprises an RFQ, two re-buncher cavities, 16 room temperature (RT) and 29 superconducting cross-bar H-type resonators, and superconducting solenoid focusing elements. One of the distinguishing features of this linac is the use of one klystron to feed multiple radio frequency (RF) elements. As an example, the RFQ, the re-bunchers and the 16 RT cavities are powered by a single 2.5 MW pulsed klystron. To achieve individual control over the phase and the voltage amplitude, each of the RF elements is equipped with a high power vector modulator. The RF control system will be discussed. The first RT cavity is completed with a power coupler, two mechanical tuners, vacuum and cooling systems, and has been RF conditioned. Preliminary tests on resonance frequency stability control and tests results of the cavity resonance frequency response to cooling water temperature and tuner position will also be discussed.

  19. Uranium enrichment measurements using the intensity ratios of self-fluorescence X-rays to 92* keV gamma ray in UXK alpha spectral region.

    PubMed

    Yücel, H; Dikmen, H

    2009-04-30

    In this paper, the known multigroup gamma-ray analysis method for uranium (MGAU) as one of the non-destructive gamma-ray spectrometry methods has been applied to certified reference nuclear materials (depleted, natural and enriched uranium) containing (235)U isotope in the range of 0.32-4.51% atom (235)U. Its analysis gives incorrect results for the low component (235)U in depleted and natural uranium samples where the build-up of the decay products begins to interfere with the analysis. The results reveal that the build-up of decay products seems to be significant and thus the algorithms for the presence of decay products should be improved to resulting in the correct enrichment value. For instance, for the case of (235)U analysis in depleted uranium or natural ore samples, self-induced X-rays such as 94.6 keV and 98.4 keV lying in UXK(alpha) spectral region used by MGAU can be excluded from the calculation. Because the significant increases have been observed in the intensities of uranium self-induced X-rays due to gamma-ray emissions with above 100 keV energy arising from decay products of (238)U and (235)U and these parents. Instead, the use of calibration curve to be made between the intensity ratios of self-fluorescence X-rays to 92(*)keV gamma-ray and the certified (235)U abundances is suggested for the determination of (235)U when higher amounts of decay products are detected in the gamma-ray spectrum acquired for the MGAU analysis. PMID:19203602

  20. μCF based 14 MeV intense neutron source

    NASA Astrophysics Data System (ADS)

    Anisimov, V. V.; Cavalleri, E.; Karmanov, F. I.; Konobeyev, A. Yu.; Latysheva, L. N.; Ponomarev, L. I.; Pshenichnov, I. A.; Slobodtchouk, V. I.; Vecchi, M.

    1999-06-01

    Results of a design study for an advanced scheme of a μCF based 14 MeV intense neutron source for test material irradiation including the liquid lithium primary target and a low temperature liquid deuterium-tritium (D-T) mixture as a secondary target are presented. According to this scheme negative pions are produced inside a 150-cm-long 0.75-cm-radius lithium target. Pions and muons resulting from the pion decay in flight are collected in the backward direction and stopped in the D-T mixture. The fusion chamber has the shape of a 10-cm-radius sphere surrounded by two 0.03-cm-thickness titanium shells. Assuming 100 fusions per muon in this scheme one can produce 14-MeV neutrons with a source strength up to 1017 n/s. A neutron flux of up to 1014 n/cm2/s can be achieved in a test volume of about 2.5 l and on the surface of about 350 cm2. The results of the thermophysical and thermomechanical analysis show that the technological limits are not exceeded. This source has the advantage of producing the original 14 MeV fusion spectrum without tails, isotropically into a 4π solid angle, contrary to the d-Li stripping neutron source.

  1. A version of the Trasco Intense Proton Source optimized for accelerator driven system purposes

    NASA Astrophysics Data System (ADS)

    Ciavola, G.; Celona, L.; Gammino, S.; Presti, M.; Andò, L.; Passarello, S.; Zhang, XZh.; Consoli, F.; Chines, F.; Percolla, C.; Calzona, V.; Winkler, M.

    2004-05-01

    A full set of measurements of the magnetic field has been carried out to define a different design of the TRASCO Intense Proton Source (TRIPS) magnetic system, based on permanent magnets, in order to increase the reliability of the source. The two coils of the source generate a maximum field of 150 mT and the optimum field was determined around 95 mT. The OPERA-3D package was used to simulate the magnetic field and a new magnetic system was designed as a combination of three rings of NdFeB magnets and soft iron. The high voltage insulation has been completely modified, in order to avoid any electronics at 80 kV voltage. The description of the magnetic measurements and the comparison with the simulations are presented, along with the mechanical design of the new version permanent magnet TRIPS (PM-TRIPS) and the new design of the extraction system. Finally the modification of the low energy beam transfer line (LEBT), which now includes a 30° bending magnet, will be outlined, with special regard to the accelerator availability improvement which can be obtained with the installation of two PM-TRIPS sources or more on the LEBT.

  2. Initial Operation of the Proto-MPEX High Intensity Plasma Source

    NASA Astrophysics Data System (ADS)

    Caughman, J. B. O.; Goulding, R. H.; Biewer, T. M.; Bigelow, T. S.; Diem, S. J.; Pesavento, P. V.; Rapp, J.; Ray, H. B.; Shaw, G. C.; Luo, G.-N.

    2014-10-01

    The Prototype Materials Plasma Experiment (Proto-MPEX) is a linear high-intensity rf plasma source that combines a high-density helicon plasma generator with electron and ion heating. It is being used to study the physics of heating over-dense plasmas, as well as exploring source interactions with a downstream target. The helicon plasma is produced by coupling 13.56 MHz rf power at levels up to 100 kW. Microwaves at 28 GHz (up to ~200 kW) are coupled to the electrons in the over-dense helicon plasma via Electron Bernstein Waves (EBW). Ion cyclotron heating (~30 kW) is via a magnetic beach approach. Tungsten baffles are used to help control neutral pressure between the helicon source and a tungsten target. Plasma diagnostics include Thomson Scattering and a retarding field energy analyzer to determine plasma parameters near the target, while a microwave interferometer and Langmuir probes are used to determine plasma parameters near the source and elsewhere in the system. High plasma densities have been produced in He (>3 × 1019/m3) and D (>1.5 × 1019/m3) , and operation in magnetic field strengths up to 1 T has been demonstrated. Details of the experimental results will be presented, as well as future plans for studying plasma surface interactions and rf antenna plasma interactions. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under Contract DE-AC-05-00OR22725.

  3. The determination of absolute intensity of 234mPa's 1001 keV gamma emission using Monte Carlo simulation.

    PubMed

    Begy, Robert-Csaba; Cosma, Constantin; Timar, Alida; Fulea, Dan

    2009-05-01

    The 1001 keV gamma line of (234m)Pa became important in gamma spectrometric measurements of samples with (238)U content with the advent of development of HpGe detectors of great dimension and high efficiency. In this study the emission probability of the 1001 keV (Y(gamma)) peak of (234m)Pa, was determined by gamma-ray spectrometric measurements performed on glass with Uranium content using Monte Carlo simulation code for efficiency calibration. This method of calculation was not applied for the values quoted in literature so far, at least to our knowledge. The measurements gave an average of 0.836 +/- 0.022%, a value that is in very good agreement to some of the recent results previously presented.

  4. The determination of absolute intensity of 234mPa's 1001 keV gamma emission using Monte Carlo simulation.

    PubMed

    Begy, Robert-Csaba; Cosma, Constantin; Timar, Alida; Fulea, Dan

    2009-05-01

    The 1001 keV gamma line of (234m)Pa became important in gamma spectrometric measurements of samples with (238)U content with the advent of development of HpGe detectors of great dimension and high efficiency. In this study the emission probability of the 1001 keV (Y(gamma)) peak of (234m)Pa, was determined by gamma-ray spectrometric measurements performed on glass with Uranium content using Monte Carlo simulation code for efficiency calibration. This method of calculation was not applied for the values quoted in literature so far, at least to our knowledge. The measurements gave an average of 0.836 +/- 0.022%, a value that is in very good agreement to some of the recent results previously presented. PMID:19384056

  5. Land-Use Intensity of Electricity Production: Comparison Across Multiple Sources

    NASA Astrophysics Data System (ADS)

    Swain, M.; Lovering, J.; Blomqvist, L.; Nordhaus, T.; Hernandez, R. R.

    2015-12-01

    Land is an increasingly scarce global resource that is subject to competing pressures from agriculture, human settlement, and energy development. As countries concerned about climate change seek to decarbonize their power sectors, renewable energy sources like wind and solar offer obvious advantages. However, the land needed for new energy infrastructure is also an important environmental consideration. The land requirement of different electricity sources varies considerably, but there are very few studies that offer a normalized comparison. In this paper, we use meta-analysis to calculate the land-use intensity (LUI) of the following electricity generation sources: wind, solar photovoltaic (PV), concentrated solar power (CSP), hydropower, geothermal, nuclear, biomass, natural gas, and coal. We used data from existing studies as well as original data gathered from public records and geospatial analysis. Our land-use metric includes land needed for the generation facility (e.g., power plant or wind farm) as well as the area needed to mine fuel for natural gas, coal, and nuclear power plants. Our results found the lowest total LUI for nuclear power (115 ha/TWh/y) and the highest LUI for biomass (114,817 ha/TWh/y). Solar PV and CSP had a considerably lower LUI than wind power, but both were an order of magnitude higher than fossil fuels (which ranged from 435 ha/TWh/y for natural gas to 579 ha/TWh/y for coal). Our results suggest that a large build-out of renewable electricity, though it would offer many environmental advantages over fossil fuel power sources, would require considerable land area. Among low-carbon energy sources, relatively compact sources like nuclear and solar have the potential to reduce land requirements.

  6. An enhanced Bayesian fingerprinting framework for studying sediment source dynamics in intensively managed landscapes

    NASA Astrophysics Data System (ADS)

    Abban, B.; (Thanos) Papanicolaou, A. N.; Cowles, M. K.; Wilson, C. G.; Abaci, O.; Wacha, K.; Schilling, K.; Schnoebelen, D.

    2016-06-01

    An enhanced revision of the Fox and Papanicolaou (hereafter referred to as "F-P") (2008a) Bayesian, Markov Chain Monte Carlo fingerprinting framework for estimating sediment source contributions and their associated uncertainties is presented. The F-P framework included two key deterministic parameters, α and β, that, respectively, reflected the spatial origin attributes of sources and the time history of eroded material delivered to and collected at the watershed outlet. However, the deterministic treatment of α and β is limited to cases with well-defined spatial partitioning of sources, high sediment delivery, and relatively short travel times with little variability in transport within the watershed. For event-based studies in intensively managed landscapes, this may be inadequate since landscape heterogeneity results in variabilities in source contributions, their pathways, delivery times, and storage within the watershed. Thus, probabilistic treatments of α and β are implemented in the enhanced framework to account for these variabilities. To evaluate the effects of the treatments of α and β on source partitioning, both frameworks are applied to the South Amana Subwatershed (SASW) in the U.S. midwest. The enhanced framework is found to estimate mean source contributions that are in good agreement with estimates from other studies in SASW. The enhanced framework is also able to produce expected trends in uncertainty during the study period, unlike the F-P framework, which does not perform as expected. Overall, the enhanced framework is found to be less sensitive to changes in α and β than the F-P framework, and, therefore, is more robust and desirable from a management standpoint.

  7. Cosmic gamma-ray lines - Theory

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.; Ramaty, R.

    1980-01-01

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

  8. The design of a source to simulate the gamma-ray spectrum emitted by a radioisotope thermoelectric generator

    NASA Technical Reports Server (NTRS)

    Reier, M.

    1972-01-01

    A simulated source was designed to duplicate the gamma spectrum of a uniform cylindrical 2200-watt Pu02 radioisotope thermoelectric generator containing 81% Pu-238 and 1.2 ppm Pu-236. Gamma rays from the decay of Pu-238, Am-241, Pu-239, and the 0-18(alpha,n)Ne-21 reaction were catalogued in broad energy groups. Two 46- and one 22-mc Th-228 sources provided simulation at various times in the life of the fuel capsule up to 18 years, which covers the time span of an outer planet mission. Emission from Th-228 represents the overwhelming contribution of the gamma spectrum after the first few years. The sources, in the form of 13-inch rods, were placed in a concentric hole in a cylinder of depleted uranium, which provided shielding equivalent to the self-shielding of the fuel capsule. The thickness of the U-238 cylinder (0.55cm) was determined by Monte Carlo calculations to insure that the spectrum emerging from the simulated source matched that of the fuel capsule.

  9. Chandra X-Ray Observations of the Two Brightest Unidentified High Galactic Latitude Fermi-LAT Gamma-Ray Sources

    NASA Technical Reports Server (NTRS)

    Cheung, C. C.; Donato, D.; Gehrels, N.; Sokolovsky, K. V.; Giroletti, M.

    2012-01-01

    We present Chandra ACIS-I X-ray observations of 0FGL J1311.9-3419 and 0FGL J1653.4-0200, the two brightest high Galactic latitude (absolute value (beta) >10 deg) gamma-ray sources from the three-month Fermi Large Area Telescope (LAT) bright source list that are still unidentified. Both were also detected previously by EGRET, and despite dedicated multi-wavelength follow-up, they are still not associated with established classes of gamma-ray emitters like pulsars or radio-loud active galactic nuclei. X-ray sources found in the ACIS-I fields of view are cataloged, and their basic properties are determined. These are discussed as candidate counterparts to 0FGL J1311.9-3419 and 0FGL J1653.4-0200, with particular emphasis on the brightest of the 9 and 13 Chandra sources detected within the respective Fermi-LAT 95% confidence regions. Further follow-up studies, including optical photometric and spectroscopic observations, are necessary to identify these X-ray candidate counterparts in order to ultimately reveal the nature of these enigmatic gamma-ray objects.

  10. The Tropical Cyclones as the Possible Sources of Gamma Emission in the Earth's Atmosphere

    NASA Astrophysics Data System (ADS)

    Klimov, S. I.; Sharkov, E. A.; Zelenyi, L. M.

    2009-12-01

    [*S. I. Klimov*] (Space Research Institute [IKI] of RAS; Profsoyuznaya 84/32, 117997 GSP-7 Moscow, Russia; Tel: +7 (495) 333-1100; Fax: +7 (495) 333-1248; e-mail: sklimov@iki.rssi.ru)): E. A. Sharkov (Space Research Institute [IKI] of RAS; Profsoyuznaya 84/32, 117997 GSP-7 Moscow, Russia; Tel: +7 (495) 333-1366; Fax: +7 (495) 333-1248; e-mail: e.sharkov@mail.ru): L. M. Zelenyi (Space Research Institute [IKI] of RAS; Profsoyuznaya 84/32, 117997 GSP-7 Moscow, Russia; Tel: +7 (495) 333-2588; Fax: +7 (495) 333-3311; e-mail: lzelenyi@iki.rssi.ru ): The tropical cyclones (TC) are the strongest sources of thunderstorm activity (and, correspondingly, electromagnetic activity in the wide frequency range) in the Earth's atmosphere. The area dimensions of active region comprise to 1000 km and they achieve vertical development to 16-20 km with speeds of the displacement of the charged drops of water of up to 30 m/s. In the work are evaluated the physical mechanisms of the possibility of generation by TC of gamma emission (TCGE), which can be fixed from the low-orbital spacecraft of the type of the potential Russian micro-satellite Chibis-M (MS) [Zelenyi, et al, Walter de Gruter, Berlin, New York, p. 443-451, 2005]. The study of the new physical mechanisms of the electrical discharges in the atmosphere is basic scientific task Chibis- M [Angarov et al. Wissenschaft und Technik Verlag, Berlin, 2009, p. 69-72]. Complex of scientific instruments of the Chibis-M (overall mass of 12,5 kg) including the instruments: - X-ray - gamma detector (range of X-ray and gamma emission - 50-500 keV), - UV detector (range UV - emission - 300-450 nm), - radiofrequency analyzer (20 - 50 MHz). - digital camber of optical range (spatial resolution 300 m). - plasma-wave complex (0.1-40 kHz), it can be used also for the TCGE study. Delivery Chibis-M into orbit, close to the ISS orbit is intended to carry out in second-half 2010. Micro-satellite "Chibis-M" now designed in IKI. Total mass "Chibis

  11. Classification and Ranking of Fermi LAT Gamma-ray Sources from the 3FGL Catalog using Machine Learning Techniques

    NASA Astrophysics Data System (ADS)

    Saz Parkinson, P. M.; Xu, H.; Yu, P. L. H.; Salvetti, D.; Marelli, M.; Falcone, A. D.

    2016-03-01

    We apply a number of statistical and machine learning techniques to classify and rank gamma-ray sources from the Third Fermi Large Area Telescope Source Catalog (3FGL), according to their likelihood of falling into the two major classes of gamma-ray emitters: pulsars (PSR) or active galactic nuclei (AGNs). Using 1904 3FGL sources that have been identified/associated with AGNs (1738) and PSR (166), we train (using 70% of our sample) and test (using 30%) our algorithms and find that the best overall accuracy (>96%) is obtained with the Random Forest (RF) technique, while using a logistic regression (LR) algorithm results in only marginally lower accuracy. We apply the same techniques on a subsample of 142 known gamma-ray pulsars to classify them into two major subcategories: young (YNG) and millisecond pulsars (MSP). Once more, the RF algorithm has the best overall accuracy (∼90%), while a boosted LR analysis comes a close second. We apply our two best models (RF and LR) to the entire 3FGL catalog, providing predictions on the likely nature of unassociated sources, including the likely type of pulsar (YNG or MSP). We also use our predictions to shed light on the possible nature of some gamma-ray sources with known associations (e.g., binaries, supernova remnants/pulsar wind nebulae). Finally, we provide a list of plausible X-ray counterparts for some pulsar candidates, obtained using Swift, Chandra, and XMM. The results of our study will be of interest both for in-depth follow-up searches (e.g., pulsar) at various wavelengths and for broader population studies.

  12. Intense beams from gases generated by a permanent magnet ECR ion source at PKU.

    PubMed

    Ren, H T; Peng, S X; Lu, P N; Yan, S; Zhou, Q F; Zhao, J; Yuan, Z X; Guo, Z Y; Chen, J E

    2012-02-01

    An electron cyclotron resonance (ECR) ion source is designed for the production of high-current ion beams of various gaseous elements. At the Peking University (PKU), the primary study is focused on developing suitable permanent magnet ECR ion sources (PMECRs) for separated function radio frequency quadrupole (SFRFQ) accelerator and for Peking University Neutron Imaging Facility. Recently, other kinds of high-intensity ion beams are required for new acceleration structure demonstration, simulation of fusion reactor material irradiation, aviation bearing modification, and other applications. So we expanded the ion beam category from O(+), H(+), and D(+) to N(+), Ar(+), and He(+). Up to now, about 120 mA of H(+), 83 mA of D(+), 50 mA of O(+), 63 mA of N(+), 70 mA of Ar(+), and 65 mA of He(+) extracted at 50 kV through a φ 6 mm aperture were produced by the PMECRs at PKU. Their rms emittances are less than 0.2 π mm mrad. Tungsten samples were irradiated by H(+) or He(+) beam extracted from this ion source and H∕He holes and bubbles have been observed on the samples. A method to produce a high intensity H∕He mixed beam to study synergistic effect is developed for nuclear material irradiation. To design a He(+) beam injector for coupled radio frequency quadruple and SFRFQ cavity, He(+) beam transmission experiments were carried out on PKU low energy beam transport test bench and the transmission was less than 50%. It indicated that some electrode modifications must be done to decrease the divergence of He(+) beam. PMID:22380337

  13. Intense beams from gases generated by a permanent magnet ECR ion source at PKU

    SciTech Connect

    Ren, H. T.; Chen, J. E.; Peng, S. X.; Lu, P. N.; Yan, S.; Zhou, Q. F.; Zhao, J.; Yuan, Z. X.; Guo, Z. Y.

    2012-02-15

    An electron cyclotron resonance (ECR) ion source is designed for the production of high-current ion beams of various gaseous elements. At the Peking University (PKU), the primary study is focused on developing suitable permanent magnet ECR ion sources (PMECRs) for separated function radio frequency quadrupole (SFRFQ) accelerator and for Peking University Neutron Imaging Facility. Recently, other kinds of high-intensity ion beams are required for new acceleration structure demonstration, simulation of fusion reactor material irradiation, aviation bearing modification, and other applications. So we expanded the ion beam category from O{sup +}, H{sup +}, and D{sup +} to N{sup +}, Ar{sup +}, and He{sup +}. Up to now, about 120 mA of H{sup +}, 83 mA of D{sup +}, 50 mA of O{sup +}, 63 mA of N{sup +}, 70 mA of Ar{sup +}, and 65 mA of He{sup +} extracted at 50 kV through a {phi} 6 mm aperture were produced by the PMECRs at PKU. Their rms emittances are less than 0.2 {pi} mm mrad. Tungsten samples were irradiated by H{sup +} or He{sup +} beam extracted from this ion source and H/He holes and bubbles have been observed on the samples. A method to produce a high intensity H/He mixed beam to study synergistic effect is developed for nuclear material irradiation. To design a He{sup +} beam injector for coupled radio frequency quadruple and SFRFQ cavity, He{sup +} beam transmission experiments were carried out on PKU low energy beam transport test bench and the transmission was less than 50%. It indicated that some electrode modifications must be done to decrease the divergence of He{sup +} beam.

  14. VizieR Online Data Catalog: 8yr INTEGRAL/IBIS soft gamma-ray source obs. (Bird+, 2016)

    NASA Astrophysics Data System (ADS)

    Bird, A. J.; Bazzano, A.; Malizia, A.; Fiocchi, M.; Sguera, V.; Bassani, L.; Hill, A. B.; Ubertini, P.; Winkler, C.

    2016-04-01

    Here we report an all-sky soft gamma-ray source catalog based on IBIS observations performed during the first 1000 orbits of INTEGRAL. The database for the construction of the source list consists of all good-quality data available, from the launch in 2002, up to the end of 2010. This corresponds to ~110Ms of scientific public observations, with a concentrated coverage on the Galactic Plane and extragalactic deep exposures. This new catalog includes 939 sources above a 4.5σ significance threshold detected in the 17-100keV energy band, of which 120 sources represent previously undiscovered soft gamma-ray emitters. The source positions are determined, mean fluxes are provided in two main energy bands, and these are both reported together with the overall source exposure. Indicative levels of variability are provided, and outburst times and durations are given for transient sources. A comparison is made with previous IBIS catalogs and catalogs from other similar missions. (2 data files).

  15. Galactic plane gamma-radiation

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Fichtel, C. E.; Ogelman, H. B.; Tumer, T.; Ozel, M. E.

    1979-01-01

    Analysis of the SAS 2 data together with the COS B results shows that the distribution of galactic gamma-radiation has several similarities to that of other large-scale tracers of galactic structure. The radiation is primarily confined to a thin disc which exhibits offsets from b = 0 degrees similar to warping at radio frequencies. The principal distinction of the gamma-radiation is a stronger contrast in intensity between the region from 310 to 45 degrees in longitude and the regions away from the center that can be attributed to a variation in cosmic-ray density as a function of position in Galaxy. The diffuse galactic gamma-ray energy spectrum shows no significant variation in direction, and the spectrum seen along the plane is the same as that for the galactic component of the gamma-radiation at high altitudes. The uniformity of the galactic gamma-ray spectrum, the smooth decrease in intensity as a function of altitude, and the absence of any galactic gamma-ray sources at high altitudes indicate a diffuse origin for bulk of the galactic gamma-radiation rather than a collection of localized sources.

  16. On the scaling of multicrystal data sets collected at high-intensity X-ray and electron sources

    PubMed Central

    Coppens, Philip; Fournier, Bertrand

    2015-01-01

    The need for data-scaling has become increasingly evident as time-resolved pump-probe photocrystallography is rapidly developing at high intensity X-ray sources. Several aspects of the scaling of data sets collected at synchrotrons, XFELs (X-ray Free Electron Lasers) and high-intensity pulsed electron sources are discussed. They include laser-ON/laser-OFF data scaling, inter- and intra-data set scaling. PMID:26798829

  17. Structure-specific scalar intensity measures for near-source and ordinary earthquake ground motions

    USGS Publications Warehouse

    Luco, N.; Cornell, C.A.

    2007-01-01

    Introduced in this paper are several alternative ground-motion intensity measures (IMs) that are intended for use in assessing the seismic performance of a structure at a site susceptible to near-source and/or ordinary ground motions. A comparison of such IMs is facilitated by defining the "efficiency" and "sufficiency" of an IM, both of which are criteria necessary for ensuring the accuracy of the structural performance assessment. The efficiency and sufficiency of each alternative IM, which are quantified via (i) nonlinear dynamic analyses of the structure under a suite of earthquake records and (ii) linear regression analysis, are demonstrated for the drift response of three different moderate- to long-period buildings subjected to suites of ordinary and of near-source earthquake records. One of the alternative IMs in particular is found to be relatively efficient and sufficient for the range of buildings considered and for both the near-source and ordinary ground motions. ?? 2007, Earthquake Engineering Research Institute.

  18. Initial Operation of the PhIX High Intensity Plasma Source

    NASA Astrophysics Data System (ADS)

    Caughman, J. B. O.; Goulding, R. H.; Biewer, T. M.; Bigelow, T. S.; Diem, S. J.; Pesavento, P. V.; Rapp, J.; Shaw, G. C.

    2013-10-01

    The Physics Integration eXperiment (PhIX) is a linear high-intensity rf plasma source that combines a high-density helicon plasma generator with an electron heating section. It is being used to study the physics of heating over-dense plasmas in a linear configuration, as well as exploring source interactions with a downstream target. The helicon plasma is produced by coupling 13.56 MHz rf power at levels up to 100 kW. Microwaves at 18 GHz are coupled to the electrons in the over-dense helicon plasma via whistler waves and Electron Bernstein Waves (EBW). An energy analyzer embedded in the target substrate is being used to determine the ion energy and ion flux at the target, while a microwave interferometer and Langmuir probes are used to determine plasma parameters near the source and near the target. High plasma densities have been produced in He (>5 × 1019/m3) and H (>1.5 × 1019/m3) , and operation in magnetic field strengths up to 0.5T has been demonstrated. Details of the experimental results will be presented, as well as future plans for studying plasma surface interactions and rf antenna plasma interactions. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC-05-00OR22725.

  19. Study of the Large-Scale Distribution of Gamma-Ray Burst Sources by the Method of Pairwise Distances

    NASA Astrophysics Data System (ADS)

    Gerasim, R. V.; Orlov, V. V.; Raikov, A. A.

    2015-06-01

    The method of pairwise distances developed earlier by the authors is used to study the spatial distribution of 352 sources of gamma-ray bursts with measured redshifts. Three cosmological models are considered: a model with a Euclidean metric, the "tired light" model, and the standard ΛCDM model. It is found that this set has fractal features and may be multifractal. The fractal dimensionalities are estimated.

  20. Experimental results on gamma-ray sources at E sub 0 = 10(13) - 10(14) eV

    NASA Technical Reports Server (NTRS)

    Morello, C.; Navarra, G.; Periale, L.; Vallania, P.

    1985-01-01

    The detection of very high energy gamma ray sources has been reported in the last few years by means of extensive air shower observations. The Plateau Rosa array for the registration of the arrival directions of extensive air showers has been operating since 1980 and first results on Cygnus X-3 have been reported. Here, the status of observations of Cygnus X-3 and of the Crab Pulsar are reported.

  1. Bright optical flare in Gamma-source PKS 1510-089

    NASA Astrophysics Data System (ADS)

    Jankowsky, F.; Mohamed, M.; Schwemmer, S.; Wagner, S.; Zacharias, M.

    2016-09-01

    Optical observations of the VHE gamma-ray bright, flat-spectrum radio quasar PKS 1510-089 (z=0.36) with the Automatic Telescope for Optical Monitoring (ATOM) in Namibia reveal a significant brightening.

  2. Searching for the counterpart to the unidentified gamma-ray source 2FGL J0221.4+6257c

    NASA Astrophysics Data System (ADS)

    Luque-Escamilla, Pedro; Sanchez-Ayaso, Estrella; Sanchez-Sutil, Juan Ramon; Marti, Josep

    The Fermi LAT source 2FGL J0221.4+6257c is tentatively associated in the Fermi catalogue to the SNR G132.7+01.3. However, its huge angular size of 80’ makes this identification uncertain. In an effort to find counterparts to this Fermi LAT source we used a cross-correlation between different catalogues and databases. As a result, the emission-line, early-type star VES 737 (V=11.86 mag, spectral type B9V) appeared as a possible gamma-ray binary candidate consistent at the position of the Fermi source. Trying to confirm the true nature of this source, we carried out a VLA observation which showed no radio detection in the position of VES 737, thus giving less reliability to the gamma-ray binary scenario. However, other interesting radio sources appeared consistent with the Fermi LAT error ellipse. Here we report the analysis taken so far to these sources, suggesting a possible PWN or AGN counterparts to the Fermi LAT 2FGL J0221.4+6257c.

  3. Nitrate behaviors and source apportionment in an aquatic system from a watershed with intensive agricultural activities.

    PubMed

    Lu, Lu; Cheng, Hongguang; Pu, Xiao; Liu, Xuelian; Cheng, Qianding

    2015-01-01

    Nitrate pollution in aquatic systems caused by intensive agricultural activities is a serious problem in the Sanjiang Plain. In this study, a dual isotope approach (δ(15)N-NO3(-) and δ(18)O-NO3(-)) was employed to identify potential nitrate sources (atmospheric deposition, AD; NO3(-) derived from soil organic matter nitrification, NS; NO3(-) derived from chemical fertilizer nitrification, NF; and manure and sewage, M&S) and transformation processes occurring in the Abujiao River watershed located in the Sanjiang Plain. The Bayesian model (stable isotope analysis in R, SIAR) was utilized to apportion the contribution of the potential sources. In this watershed, the nitrate concentrations in the surface water were low (mean ± SD = 1.15 ± 0.84 mg L(-1)), and were greatly influenced by precipitation and land use conditions during the two sampling periods (the high flow period, September; the low flow period, November). On the contrary, in the ground water, high NO3(-) concentrations were observed (7.84 ± 5.83 mg L(-1)) and no significant temporal variation in NO3(-) was found during the sampling periods. The sampled water δ(18)O-NO3(-) values suggest that the nitrification process was not the main N cycling process, because most of the measured δ(18)O-NO3(-) values were above the expected δ(18)O-NO3(-) from nitrification throughout the sampling periods. Both the chemical and isotopic characteristics indicated that the signs of de-nitrification were absent in the surface water. However, significant de-nitrification processes were observed in the ground water for all sample periods. Results from the SIAR model showed that source contributions differed significantly during the two sampling periods. During the high flow period, chemical fertilizers and soil N fertilizer equally contributed to the major sources of nitrate in the surface water. In contrast, manure and sewage sources dominated the source contribution during the low flow period (November). This study

  4. Induced electroencephalogram oscillations during source memory: familiarity is reflected in the gamma band, recollection in the theta band.

    PubMed

    Gruber, Thomas; Tsivilis, Dimitris; Giabbiconi, Claire-Marie; Müller, Matthias M

    2008-06-01

    Modulations of oscillatory electroencephalogram (EEG) activity in the induced gamma and theta frequency ranges (induced gamma and theta band responses; iGBRs: >30 Hz; iTBRs: approximately 6 Hz) have been associated with retrieval of information from long-term memory. However, the specific functional role of these two forms of oscillatory activity remains unclear. The present study examines theta- and gamma-oscillations within a dual-process framework, which defines "familiarity" and "recollection" as the two component processes of recognition memory. During encoding, participants were instructed to make "bigger/smaller than a shoebox" or "living/nonliving" decisions for different object pictures. During retrieval "old/new" recognition was followed (for items judged old) by a source discrimination task regarding the decision made for each item at encoding. iGBRs (35-80 Hz; 210-330 msec) were higher for correctly identified "old" relative to "new" objects. Importantly, they did not distinguish between successful and unsuccessful source judgments. In contrast, iTBRs (4-7.5 Hz; 600-1200 msec) were sensitive to source discrimination. We propose that iGBRs mirror early associative processes linked to familiarity-related retrieval processes, whereas iTBRs reflect later onsetting, episodic, recollection-related mechanisms. PMID:18211247

  5. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H.

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant. These detectors, based on silicon carbide (SiC) semiconductor are designed to have larger active volumes than previously available SiC detectors, and are being tested for their response to alpha particles, X-rays and low energy gamma rays, and fast neutrons.

  6. RHESSI Observations of Particle Acceleration and Energy Release in an Intense Solar Gamma-Ray Line Flare

    NASA Astrophysics Data System (ADS)

    Lin, R. P.; Krucker, S.; Hurford, G. J.; Smith, D. M.; Hudson, H. S.; Holman, G. D.; Schwartz, R. A.; Dennis, B. R.; Share, G. H.; Murphy, R. J.; Emslie, A. G.; Johns-Krull, C.; Vilmer, N.

    2003-10-01

    We summarize Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) hard X-ray (HXR) and γ-ray imaging and spectroscopy observations of the intense (X4.8) γ-ray line flare of 2002 July 23. In the initial rise, a new type of coronal HXR source dominates that has a steep double-power-law X-ray spectrum and no evidence of thermal emission above 10 keV, indicating substantial electron acceleration to tens of keV early in the flare. In the subsequent impulsive phase, three footpoint sources with much flatter double-power-law HXR spectra appear, together with a coronal superhot (T~40 MK) thermal source. The north footpoint and the coronal source both move systematically to the north-northeast at speeds up to ~50 km s-1. This footpoint's HXR flux varies approximately with its speed, consistent with magnetic reconnection models, provided the rate of electron acceleration varies with the reconnection rate. The other footpoints show similar temporal variations but do not move systematically, contrary to simple reconnection models. The γ-ray line and continuum emissions show that ions and electrons are accelerated to tens of MeV during the impulsive phase. The prompt de-excitation γ-ray lines of Fe, Mg, Si, Ne, C, and O-resolved here for the first time-show mass-dependent redshifts of 0.1%-0.8%, implying a downward motion of accelerated protons and α-particles along magnetic field lines that are tilted toward the Earth by ~40°. For the first time, the positron annihilation line is resolved, and the detailed high-resolution measurements are obtained for the neutron-capture line. The first ever solar γ-ray line and continuum imaging shows that the source locations for the relativistic electron bremsstrahlung overlap the 50-100 keV HXR sources, implying that electrons of all energies are accelerated in the same region. The centroid of the ion-produced 2.223 MeV neutron-capture line emission, however, is located ~20''+/-6'' away, implying that the acceleration and

  7. The first muon beam from a new highly-intense DC muon source, MuSIC

    NASA Astrophysics Data System (ADS)

    Tran, Nam Hoai; MuSIC Collaboration

    2012-09-01

    A new DC muon source, MuSIC, is now under construction at Research Center for Nuclear Physics (RCNP), Osaka University, Japan. The MuSIC adopts a new pion/muon collection system and a curved transport solenoid. These techniques are important in realization of future muon programs such as the muon to electron conversion experiments (COMET/Mu2e), neutrino factories, and muon colliders. The pion capture magnet and a part of the transport solenoid have been built and beam tests were carried out to assess the MuSIC's performance. Muon lifetime measurements and muonic X-ray measurements have been used for estimation of muon yield of the MuSIC. The result indicates that the MuSIC would be one of the most intense DC muon beams in the world.

  8. Effect of photoperiod, light intensity and carbon sources on biomass and lipid productivities of Isochrysis galbana.

    PubMed

    Babuskin, Srinivasan; Radhakrishnan, Kesavan; Babu, Packirisamy Azhagu Saravana; Sivarajan, Meenakshisundaram; Sukumar, Muthusamy

    2014-08-01

    Biomass and lipid productivities of Isochrysis galbana were optimized using nutrients of molasses (4, 8, 12 g l(-1)), glucose (4, 8, 12 g l(-1)), glycerol (4, 8, 12 g l(-1)) and yeast extract (2 g l(-1)). Combinations of carbon sources at different ratios were evaluated in which the alga was grown at three different light intensities (50, 100 and 150 μmol m(-2) s(-1)) under the influence of three different photoperiod cycles (12/12, 18/6 and 24/0 h light/dark). A maximum cell density of 8.35 g l(-1) with 32 % (w/w) lipid was achieved for mixotrophic growth at 100 μmol m(-2) s(-1) and 18/6 h light/dark with molasses/glucose (20:80 w/w). Mixotrophic cultivation using molasses, glucose and glycerol was thus effective for the cultivation of I. galbana.

  9. Swept-source OCT Angiography of the Retinal Vasculature using Intensity Differentiation Based OMAG Algorithms

    PubMed Central

    Huang, Yanping; Zhang, Qinqin; Thorell, Mariana Rossi; An, Lin; Durbin, Mary; Laron, Michal; Sharma, Utkarsh; Gregori, Giovanni; Rosenfeld, Philip J.; Wang, Ruikang K

    2014-01-01

    Background and Objective To demonstrate the feasibility of using a 1050 nm swept-source OCT (SS-OCT) system to achieve noninvasive retinal vasculature imaging in human eyes. Materials and Methods Volumetric datasets were acquired using a ZEISS 1 µm SS-OCT prototype that operated at an A-line rate of 100 kHz. A scanning protocol designed to allow for motion contrast processing, referred to as OCT angiography or optical microangiography (OMAG), was used to scan ~3 mm × 3 mm area in the central macular region of the retina within ~4.5 seconds. Intensity differentiation based OMAG algorithm was used to extract 3-D retinal functional microvasculature information. Results Intensity signal differentiation generated capillary-level resolution en face OMAG images of the retina. The parafoveal capillaries were clearly visible, thereby allowing visualization of the foveal avascular zone (FAZ) in normal subjects. Conclusion The capability of OMAG to produce retinal vascular images was demonstrated using the ZEISS 1 µm SS-OCT prototype. This technique can potentially have clinical value for studying retinal vasculature abnormalities. PMID:25230403

  10. Sources of Stress for Nurses in Neonatal Intensive Care Units of East Azerbaijan Province, Iran

    PubMed Central

    Valizadeh, Leila; Farnam, Alireza; Zamanzadeh, Vahid; Bafandehzendeh, Mostafa

    2012-01-01

    Introduction: Stress is one of the main factors affecting one's efficiency as well as staff health and quality of nursing services. Neonatal intensive care units (NICUs) can be stressful environments for nurses, infants and families as well. Since there is no evidence in this regard in Iran, the present study aimed to determine stress levels related to care delivering in NICU from the viewpoint of nurses in NICUs of East Azerbaijan Province, Iran during 2011. Methods: This was a descriptive study including a purposive sample of 110 nurses working in NICUs of hospitals in East Azerbaijan Province. The data collection tool was a self-report questionnaire. The validity and reliability of the questionnaire were assessed by content validity and Cronbach's alpha coefficient (α = 0.84). Results: According to factor analysis, the stressors included environmental and nurse and human factors. Stress sources in total and separately in each category were reported as moderate. The mean and 95% confidence interval of the factors in the categories were 2.75 (0.84); 2.59-2.91 and 3.21 (0.72); 3.07-3.35, respectively. Therefore, human factors caused significantly higher levels of stress compared to environmental factors (p < 0.05). Conclusion: Stressors involved in NICU nursing include environmental and human factors. Planning to remove or reduce their impact can improve the quality of nursing services in intensive care units and, thus, decrease the adverse effects of stress on workers. PMID:25276702

  11. FERMI/Gamma-ray Burst Monitor upper limits assuming a magnetar origin for the repeating Fast Radio Burst source, FRB 121102

    NASA Astrophysics Data System (ADS)

    Younes, George; Kouveliotou, Chryssa; Huppenkothen, Daniela; Gogus, Ersin; Kaneko, Yuki; van der Horst, Alexander

    2016-03-01

    Spitler et al. (2016, 10.1038/nature17168) reported a repeating Fast Radio Burst source, FRB 121102, with a rate of about 3 bursts/hr. We searched the FERMI/Gamma-ray Burst Monitor (GBM) for possible gamma-ray counterparts for these events.

  12. Observations of potential ultra high energy gamma-ray sources above 10(15) eV

    NASA Technical Reports Server (NTRS)

    Lambert, A.; Lloyd-Evans, J.; Perrett, J. C.; Watson, A. A.; West, A. A.

    1985-01-01

    The Haverah Park 50 m water-Cerenkov array has been used to examine a number of periodic sources for ultra high energy gamma-ray emission above 10 to the 15th power eV. The data, recorded between 1 Jan. 1979 and 31 Dec. 1984, feature a modest angular resolution of approx 3 deg with millisecond arrival time resolution post 1982. The sources investigated include the Crab pulsar, Her X-1, Au0115 + 63 and Geminga. All objects have been detected by workers in the TeV region, with varying degrees of confidence.

  13. Inspecting absorption in the spectra of extra-galactic gamma-ray sources for insight into Lorentz invariance violation

    SciTech Connect

    Jacob, Uri; Piran, Tsvi

    2008-12-15

    We examine what the absorbed spectra of extra-galactic TeV gamma-ray sources, such as blazars, would look like in the presence of Lorentz invariance violation. Pair production with the extra-galactic background light modifies the observed spectra of such sources, and we show that a violation of Lorentz invariance would generically have a dramatic effect on this absorption feature. Inspecting this effect, an experimental task likely practical in the near future, can provide unique insight on the possibility of Lorentz invariance violation.

  14. VizieR Online Data Catalog: Fermi-LAT flaring gamma-ray sources from FAVA (Ackermann+, 2013)

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Antolini, E.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Bottacini, E.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Cheung, C. C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; Dalton, M.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hewitt, J.; Hill, A. B.; Horan, D.; Hou, X.; Hughes, R. E.; Inoue, Y.; Jackson, M. S.; Jogler, T.; J! Ohannesso, N. G.; Johnson, W. N.; Kamae, T.; Kataoka, J.; Kawano, T.; Knodlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Raino, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Romoli, C.; Roth, M.; Sanchez-Conde, M.; Scargle, J. D.; Schulz, A.; Sgro, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Suson, D. J.; Takahashi, H.; Takeuchi, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Tronconi, V.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Winer, B. L.; Wood, K. S.; Wood, M.; Yang, Z.

    2015-01-01

    We applied FAVA (Fermi All-sky Variability Analysis) to the first 47 months of Fermi/LAT observations (2008 August 4 to 2012 July 16 UTC), in weekly time intervals. The total number of weeks is 206. We considered two ranges of gamma-ray energy, E>100MeV and E>800MeV, to increase the sensitivity for spectrally soft and hard flares, respectively. We generate measured and expected count maps with a resolution of 0.25deg2 per pixel. We found LAT counterparts for 192 of the 215 FAVA sources. Most of the associated sources, 177, are AGNs. (2 data files).

  15. Extended Source Gamma-Ray Emission from WIMP Annihilation in the Sagittarius Dwarf Elliptical Galaxy (SULI paper)

    SciTech Connect

    Vasu-Devan, Vidya; /Columbia U. /SLAC

    2006-01-04

    The proximity of the dark matter dominated Sagittarius Dwarf Elliptical Galaxy (position (l,b) = 5.6{sup o}, -14{sup o}) allows it to act as an ideal laboratory for the exploration of extended gamma-ray emission from Weakly Interacting Massive Particle (WIMP) annihilation processes in a dark matter-dominated system. Since the matter in our universe is predominantly dark, exploring such processes as WIMP annihilation will lead to a better understanding of cosmology. In order to study this gamma-ray emission, a model for the diffuse background gamma-radiation in the dwarf galaxy's region is extracted from the Energetic Gamma Ray Experiment Telescope (EGRET) data. After validating this model and comparing it to the EGRET diffuse model, the background model is added to effective bleeding-contamination from external point sources and multiple models for the signal-above-background emission. Various models of this emission are tested: (a) no source located in region, (b) unidentified point source 3EG J1847-3219 from the Third EGRET Catalog responsible for the emission and (c) extended emission resulting from WIMP annihilation responsible for the signal above background. These models are created through the employment of Monte Carlo simulation methods, utilizing the response functions of the EGRET instrument to simulate the point spread function, energy dispersion and effects of variable effective area depending on angle of incidence. Energy spectra for point sources are generated from the best predictions of spectral indices listed in the Third EGRET Catalog and the spectrum for the extended dark matter source is generated from Pythia high energy annihilation simulations. Hypothesis testing is conducted to assess the goodness-of-fit of these models to the data taken by EGRET. Additionally, we hope to expand our analysis by employing the response functions of the imminent Gamma Ray Large Area Space Telescope (GLAST) to our models. This extension should highlight the

  16. Suzaku Observation of the Unidentified Very High Energy Gamma-Ray Source HESS J1702-420

    NASA Astrophysics Data System (ADS)

    Fujinaga, Takahisa; Bamba, Aya; Dotani, Tadayasu; Ozaki, Masanobu; Pü:Hlhofer, Gerd; Wagner, Stefan; Reimer, Olaf; Funk, Stefan; Hinton, Jim

    2011-11-01

    A deep X-ray observation of the unidentified very high energy (VHE) gamma-ray source HESS J1702-420, for the first time, was carried out by Suzaku. No bright sources were detected in the XIS field of view (FOV), except for two faint point-like sources. The two sources, however, are considered not to be related to HESS J1702-420, because their fluxes in the 2-10 keV band (˜10-14 erg s-1 cm-2) are ˜3 orders of magnitude smaller than the VHE gamma-ray flux in the 1-10 TeV band (FTeV = 3.1 × 10-11 erg s-1 cm-2). We compared the energy spectrum of diffuse emission, extracted from the entire XIS FOV with those from nearby observations. If we consider the systematic error of background subtraction, no significant diffuse emission was detected with an upper limit of FX < 2.7 × 10-12 erg s-1 cm-2 in the 2-10 keV band for an assumed power-law spectrum of Γ = 2.1 and a source size same as that in the VHE band. The upper limit of the X-ray flux is twelve-times as small as the VHE gamma-ray flux. The large flux ratio (FTeV/FX) indicates that HESS J1702-420 is another example of a ``dark'' particle accelerator. If we use a simple one-zone leptonic model, in which VHE gamma-rays are produced through inverse Compton scattering of the cosmic microwave background and interstellar far-infrared emission, and the X-rays via the synchrotron mechanism, an upper limit of the magnetic field (1.7μG), is obtained from the flux ratio. Because the magnetic field is weaker than the typical value in the galactic plane (3-10 νG), the simple one-zone model may not work for HESS J1702-420 and a significant fraction of the VHE gamma-rays may originate from protons.

  17. Modeling olive pollen intensity in the Mediterranean region through analysis of emission sources.

    PubMed

    Rojo, J; Orlandi, F; Pérez-Badia, R; Aguilera, F; Ben Dhiab, A; Bouziane, H; Díaz de la Guardia, C; Galán, C; Gutiérrez-Bustillo, A M; Moreno-Grau, S; Msallem, M; Trigo, M M; Fornaciari, M

    2016-05-01

    Aerobiological monitoring of Olea europaea L. is of great interest in the Mediterranean basin because olive pollen is one of the most represented pollen types of the airborne spectrum for the Mediterranean region, and olive pollen is considered one of the major cause of pollinosis in this region. The main aim of this study was to develop an airborne-pollen map based on the Pollen Index across a 4-year period (2008-2011), to provide a continuous geographic map for pollen intensity that will have practical applications from the agronomical and allergological points of view. For this purpose, the main predictor variable was an index based on the distribution and abundance of potential sources of pollen emission, including intrinsic information about the general atmospheric patterns of pollen dispersal. In addition, meteorological variables were included in the modeling, together with spatial interpolation, to allow the definition of a spatial model of the Pollen Index from the main olive cultivation areas in the Mediterranean region. The results show marked differences with respect to the dispersal patterns associated to the altitudinal gradient. The findings indicate that areas located at an altitude above 300ma.s.l. receive greater amounts of olive pollen from shorter-distance pollen sources (maximum influence, 27km) with respect to areas lower than 300ma.s.l. (maximum influence, 59km).

  18. Modeling olive pollen intensity in the Mediterranean region through analysis of emission sources.

    PubMed

    Rojo, J; Orlandi, F; Pérez-Badia, R; Aguilera, F; Ben Dhiab, A; Bouziane, H; Díaz de la Guardia, C; Galán, C; Gutiérrez-Bustillo, A M; Moreno-Grau, S; Msallem, M; Trigo, M M; Fornaciari, M

    2016-05-01

    Aerobiological monitoring of Olea europaea L. is of great interest in the Mediterranean basin because olive pollen is one of the most represented pollen types of the airborne spectrum for the Mediterranean region, and olive pollen is considered one of the major cause of pollinosis in this region. The main aim of this study was to develop an airborne-pollen map based on the Pollen Index across a 4-year period (2008-2011), to provide a continuous geographic map for pollen intensity that will have practical applications from the agronomical and allergological points of view. For this purpose, the main predictor variable was an index based on the distribution and abundance of potential sources of pollen emission, including intrinsic information about the general atmospheric patterns of pollen dispersal. In addition, meteorological variables were included in the modeling, together with spatial interpolation, to allow the definition of a spatial model of the Pollen Index from the main olive cultivation areas in the Mediterranean region. The results show marked differences with respect to the dispersal patterns associated to the altitudinal gradient. The findings indicate that areas located at an altitude above 300ma.s.l. receive greater amounts of olive pollen from shorter-distance pollen sources (maximum influence, 27km) with respect to areas lower than 300ma.s.l. (maximum influence, 59km). PMID:26874763

  19. Surviving to tell the tale : Argonne's Intense Pulsed Neutron Source from an ecosystem perspective.

    SciTech Connect

    Westfall, C.; Office of The Director

    2010-07-01

    At first glance the story of the Intense Pulsed Neutron Source (IPNS), an accelerator-driven neutron source for exploring the structure of materials through neutron scattering, seems to be one of puzzling ups and downs. For example, Argonne management, Department of Energy officials, and materials science reviewers continued to offer, then withdraw, votes of confidence even though the middling-sized IPNS produced high-profile research, including work that made the cover of Nature in 1987. In the midst of this period of shifting opinion and impressive research results, some Argonne materials scientists were unenthusiastic, members of the laboratory's energy physics group were key supporters, and materials scientists at another laboratory provided, almost fortuitously, a new lease on life. What forces shaped the puzzling life cycle of the IPNS? And what role - if any - did the moderate price tag and the development of scientific and technological ideas play in the course it took? To answer these questions this paper looks to an ecosystem metaphor for inspiration, exploring how opinions, ideas, and machinery emerged from the interrelated resource economies of Argonne, the DOE, and the materials science community by way of a tangled web of shifting group interactions. The paper will conclude with reflections about what the resulting focus on relationality explains about the IPNS story as well as the underlying dynamic that animates knowledge production at U.S. national laboratories.

  20. Development of exploding wire ion source for intense pulsed heavy ion beam accelerator

    NASA Astrophysics Data System (ADS)

    Ito, Hiroaki; Ochiai, Yasushi; Murata, Takuya; Masugata, Katsumi

    2012-10-01

    A Novel exploding wire type ion source device is proposed as a metallic ion source of intense pulsed heavy ion beam (PHIB) accelerator. In the device, multiple shot operations are realized without breaking the vacuum. The basic characteristics of the device are evaluated experimentally with an aluminum wire of diameter 0.2 mm and length 25 mm. A capacitor bank of capacitance 3 μF and a charging voltage of 30 kV was used, and the wire was successfully exploded by a discharge current of 15 kA with a rise time of 5.3 μs. Plasma flux of ion current density around 70 A/cm2 was obtained at 150 mm downstream from the device. The drift velocity of ions evaluated by a time-of-flight method was 2.7×104 m/ s, which corresponds to the kinetic energy of 100 eV for aluminum ions. From the measurement of the ion current density distribution, the ion flow is found to be concentrated toward the direction where the ion acceleration gap is placed. From the experiment, the device is found to be acceptable for applying the PHIB accelerator.

  1. Intense Pulsed Neutron Source: Progress report 1991--1996. 15. Anniversary edition -- Volume 1

    SciTech Connect

    Marzec, B.

    1996-05-01

    The 15th Anniversary Edition of the IPNS Progress Report is being published in recognition of the Intense Pulsed Neutron Source`s first 15 years of successful operation as a user facility. To emphasize the importance of this milestone, the authors have made the design and organization of the report significantly different from previous IPNS Progress Reports. This report consists of two volumes. For Volume 1, authors were asked to prepare articles that highlighted recent scientific accomplishments at IPNS, from 1991 to present; to focus on and illustrate the scientific advances achieved through the unique capabilities of neutron studies performed by IPNS users; to report on specific activities or results from an instrument; or to focus on a body of work encompassing different neutron-scattering techniques. Articles were also included on the accelerator system, instrumentation, computing, target, and moderators. A list of published and ``in press` articles in journals, books, and conference proceedings, resulting from work done at IPNS since 1991, was compiled. This list is arranged alphabetically according to first author. Publication references in the articles are listed by last name of first author and year of publication. The IPNS experimental reports received since 1991 are compiled in Volume 2. Experimental reports referenced in the articles are listed by last name of first author, instrument designation, and experiment number.

  2. Intense Pulsed Neutron Source: Progress report 1991--1996. 15. Anniversary edition -- Volume 2

    SciTech Connect

    1996-05-01

    The 15th Anniversary Edition of the IPNS Progress Report is being published in recognition of the Intense Pulsed Neutron Source`s first 15 years of successful operation as a user facility. To emphasize the importance of this milestone, the author shave made the design and organization of the report significantly different from previous IPNS Progress Reports. This report consists of two volumes. For Volume 1, authors were asked to prepare articles that highlighted recent scientific accomplishments at IPNS, from 1991 to present; to focus on and illustrate the scientific advances achieved through the unique capabilities of neutron studies performed by IPNS users; to report on specific activities or results from an instrument; or to focus on a body of work encompassing different neutron-scattering techniques. Articles were also included on the accelerator system, instrumentation, computing, target, and moderators. A list of published and ``in press` articles in journals, books, and conference proceedings, resulting from work done at IPNS since 1991, was compiled. This list is arranged alphabetically according to first author. Publication references in the articles are listed by last name of first author and year of publication. The IPNS experimental reports received since 1991 are compiled in Volume 2. Experimental reports referenced in the articles are listed by last name of first author, instrument designation, and experiment number.

  3. A compact source of intense 1-100 keV monochromatic X-rays from low energy protons

    NASA Astrophysics Data System (ADS)

    Arduini, G.; Cicardi, C.; Milazzo, M.; Sangaletti, L.; Silari, M.

    1995-05-01

    The properties and possible applications of a very intense source of monochromatic X-rays, tunable in the 1-100 keV range, obtained by coupling a low energy (2-4 MeV) high current proton accelerator with an irradiation chamber provided with a multiple target system and collimator are discussed. The properties of the source are presented in terms of intensity, monochromaticity, polarizability and time structure. Fields where such a source can be employed are discussed, namely PIXE-induced XRF, X-ray photoemission spectroscopy, generation of soft X-rays, radiographic applications in archeometry and medical radiography with monoenergetic radiation.

  4. Nuclear Decay Data for the International Reactor Dosimetry Library for Fission and Fusion (IRDFF): Updated Evaluations of the Half-Lives and Gamma Ray Intensities

    NASA Astrophysics Data System (ADS)

    Chechev, Valery P.; Kuzmenko, Nikolay K.

    2016-02-01

    Updated evaluations of the half-lives and prominent gamma ray intensities have been presented for 20 radionuclides - dosimetry reaction residuals. The new values of these decay characteristics recommended for the IRDFF library were obtained using the approaches and methodology adopted by the working group of the Decay Data Evaluation Project (DDEP) cooperation. The experimental data published up to 2014 were taken into account in updated evaluations. The list of radionuclides includes 3H, 18F, 22Na, 24Na, 46Sc, 51Cr, 54Mn, 59Fe, 57Co, 60Co, 57Ni, 64Cu, 88Y, 132Te, 131I, 140Ba, 140La, 141Ce, 182Ta, 198Au.

  5. Jet emission in young radio sources: A Fermi large area telescope gamma-ray view

    SciTech Connect

    Migliori, G.; Siemiginowska, A.; Kelly, B. C.; Stawarz, Ł.; Celotti, A.; Begelman, M. C.

    2014-01-10

    We investigate the contribution of the beamed jet component to the high-energy emission in young and compact extragalactic radio sources, focusing for the first time on the γ-ray band. We derive predictions on the γ-ray luminosities associated with the relativistic jet assuming a leptonic radiative model. The high-energy emission is produced via Compton scattering by the relativistic electrons in a spherical region at the considered scales (≲10 kpc). Simulations show a wide range of γ-ray luminosities, with intensities up to ∼10{sup 46}-10{sup 48} erg s{sup –1} depending on the assumed jet parameters. We find a highly linear relation between the simulated X-ray and γ-ray luminosities that can be used to select candidates for γ-ray detection. We compare the simulated luminosity distributions in the radio, X-ray, and γ-ray regimes with observations for the largest sample of X-ray-detected young radio quasars. Our analysis of ∼4-yr Fermi Large Area Telescope (LAT) data does not yield any statistically significant detections. However, the majority of the model-predicted γ-ray fluxes for the sample are near or below the current Fermi-LAT flux threshold and compatible with the derived upper limits. Our study gives constraints on the minimum jet power (L {sub jet,} {sub kin}/L {sub disk} > 0.01) of a potential jet contribution to the X-ray emission in the most compact sources (≲ 1 kpc) and on the particle-to-magnetic field energy density ratio that are in broad agreement with equipartition assumptions.

  6. Jet Emission in Young Radio Sources: A Fermi Large Area Telescope Gamma-Ray View

    NASA Astrophysics Data System (ADS)

    Migliori, G.; Siemiginowska, A.; Kelly, B. C.; Stawarz, Ł.; Celotti, A.; Begelman, M. C.

    2014-01-01

    We investigate the contribution of the beamed jet component to the high-energy emission in young and compact extragalactic radio sources, focusing for the first time on the γ-ray band. We derive predictions on the γ-ray luminosities associated with the relativistic jet assuming a leptonic radiative model. The high-energy emission is produced via Compton scattering by the relativistic electrons in a spherical region at the considered scales (lsim10 kpc). Simulations show a wide range of γ-ray luminosities, with intensities up to ~1046-1048 erg s-1 depending on the assumed jet parameters. We find a highly linear relation between the simulated X-ray and γ-ray luminosities that can be used to select candidates for γ-ray detection. We compare the simulated luminosity distributions in the radio, X-ray, and γ-ray regimes with observations for the largest sample of X-ray-detected young radio quasars. Our analysis of ~4-yr Fermi Large Area Telescope (LAT) data does not yield any statistically significant detections. However, the majority of the model-predicted γ-ray fluxes for the sample are near or below the current Fermi-LAT flux threshold and compatible with the derived upper limits. Our study gives constraints on the minimum jet power (L jet, kin/L disk > 0.01) of a potential jet contribution to the X-ray emission in the most compact sources (lsim 1 kpc) and on the particle-to-magnetic field energy density ratio that are in broad agreement with equipartition assumptions.

  7. 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.

  8. Long lifetime, low intensity light source for use in nighttime viewing of equipment maps and other writings

    DOEpatents

    Frank, A.M.; Edwards, W.R.

    1982-03-23

    A long-lifetime light source is discussed with sufficiently low intensity to be used for reading a map or other writing at nightime, while not obscuring the user's normal night vision. This light source includes a diode electrically connected in series with a small power source and a lens properly positioned to focus at least a portion of the light produced by the diode.

  9. Long lifetime, low intensity light source for use in nighttime viewing of equipment maps and other writings

    DOEpatents

    Frank, A.M.; Edwards, W.R.

    1983-10-11

    A long-lifetime light source with sufficiently low intensity to be used for reading a map or other writing at nighttime, while not obscuring the user's normal night vision is disclosed. This light source includes a diode electrically connected in series with a small power source and a lens properly positioned to focus at least a portion of the light produced by the diode. 1 fig.

  10. Inferring the spatial and energy distribution of gamma-ray burst sources. 1: Methodology

    NASA Technical Reports Server (NTRS)

    Loredo, Thomas J.; Wasserman, Ira M.

    1995-01-01

    We describe Bayesian methods for analyzing the distribution of gamma-ray burst peak photon fluxes and directions. These methods fit the differential distribution, and have the following advantages over rival methods: (1) they do not destroy information by binning or averaging the data (as do, say, chi squared, the averaged value of V/V(sub max), and angular moment analyses); (2) they straightforwardly handle uncertainties in the measured quantities; (3) they analyze the strength and direction information jointly; (4) they use information available about nondetections; and (5) they automatically identify and account for biases and selection effects given a precise description of the experiment. In these methods, the most important information needed about the instrument threshold is not its value at the times of burst triggers, as is used in the average value of V/V(sub max) analyses, but rather the value of the threshold at times when no trigger occurred. We show that this information can be summarized as an average detection efficiency that is similar to the product of the exposure and efficiency reported in the First Burst and Transient Source Experiment (BATSE) Burst (1B) Catalog, but significantly different from it at low fluxes. We also quantify an important bias that results from estimating the peak flux by scanning the burst to find the peak number of counts in a window of specified duration, as was done for the 1B Catalog. When the duration of the peak of the light curve is longer than the window duration, a simple flux estimate based on the peak counts significantly overestimates the peak flux in a nonlinear fashion that distorts the shape of the log(N)-log(P) distribution. This distortion also corrupts analyses of the V/V(sub max) distribution that use ratios of counts above background to estimate V/V(sub max). The Bayesian calculation specifies how to account for this bias. Implementation of the Bayesian approach requires some changes in the way burst

  11. High resolution inelastic gamma-ray measurements with a white neutron source from 1 to 200 MeV

    SciTech Connect

    Nelson, R.O.; Laymon, C.M.; Wender, S.A.

    1990-01-01

    Measurements of prompt gamma rays following neutron-induced reactions have recently been made at the spallation neutron source at the WNR target area of LAMPF using germanium detectors. These experiments provide extensive excitation function data for inelastic neutron scattering as well as for other reactions such as (n,{alpha}), (n,n{alpha}), (n,p), (n,np), (n,nnp) and (n,xn) for 1 {le} {times} {le} 11. The continuous energy coverage available from 1 MeV to over 200 MeV is ideal for excitation function measurements and greatly extends the energy range for such data. The results of these measurements will provide a database for interpretation of gamma-ray spectra from the planned Mars Observer mission, aid in radiation transport calculations, allow verification of nuclear reaction models, and improve the evaluated neutron reaction data base.

  12. Spectral study of the HESS J1745-290 gamma-ray source as dark matter signal

    NASA Astrophysics Data System (ADS)

    Cembranos, J. A. R.; Gammaldi, V.; Maroto, A. L.

    2013-04-01

    We study the main spectral features of the gamma-ray fluxes observed by the High Energy Stereoscopic System (HESS) from the J1745-290 Galactic Center source during the years 2004, 2005 and 2006. In particular, we show that these data are well fitted as the secondary gamma-rays photons generated from dark matter annihilating into Standard Model particles in combination with a simple power law background. We present explicit analyses for annihilation in a single standard model particle-antiparticle pair. In this case, the best fits are obtained for the uū and dbar d quark channels and for the W+W- and ZZ gauge bosons, with background spectral index compatible with the Fermi-Large Area Telescope (LAT) data from the same region. The fits return a heavy WIMP, with a mass above ~ 10 TeV, but well below the unitarity limit for thermal relic annihilation.

  13. Spectral study of the HESS J1745-290 gamma-ray source as dark matter signal

    SciTech Connect

    Cembranos, J.A.R.; Gammaldi, V.; Maroto, A.L. E-mail: vivigamm@ucm.es

    2013-04-01

    We study the main spectral features of the gamma-ray fluxes observed by the High Energy Stereoscopic System (HESS) from the J1745-290 Galactic Center source during the years 2004, 2005 and 2006. In particular, we show that these data are well fitted as the secondary gamma-rays photons generated from dark matter annihilating into Standard Model particles in combination with a simple power law background. We present explicit analyses for annihilation in a single standard model particle-antiparticle pair. In this case, the best fits are obtained for the uū and d d-bar quark channels and for the W{sup +}W{sup −} and ZZ gauge bosons, with background spectral index compatible with the Fermi-Large Area Telescope (LAT) data from the same region. The fits return a heavy WIMP, with a mass above ∼ 10 TeV, but well below the unitarity limit for thermal relic annihilation.

  14. The Fermi All-Sky Variability Analysis: A List of Flaring Gamma-Ray Sources and the Search for Transients in our Galaxy

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Antolini, E.; Baldini, L.; Ballet, J.; Barbiellini, G; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Bloom, E. D.; Brandt, T. J.; Ferrara, E. C.; Guiriec, S.; Harding, A. K.; Hays, E.; Hewitt, J.; McEnery, J. E.; Nemmen, R.; Perkins, J. S.; Scargle, J. D; Thompson, D. J.; Troja, E.

    2013-01-01

    In this paper, we present the Fermi All-sky Variability Analysis (FAVA), a tool to systematically study the variability of the gamma-ray sky measured by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope.For each direction on the sky, FAVA compares the number of gamma-rays observed in a given time window to the number of gamma-rays expected for the average emission detected from that direction. This method is used in weekly time intervals to derive a list of 215 flaring gamma-ray sources. We proceed to discuss the 27 sources found at Galactic latitudes smaller than 10 and show that, despite their low latitudes, most of them are likely of extragalactic origin.

  15. THE FERMI ALL-SKY VARIABILITY ANALYSIS: A LIST OF FLARING GAMMA-RAY SOURCES AND THE SEARCH FOR TRANSIENTS IN OUR GALAXY

    SciTech Connect

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Bechtol, K.; Blandford, R. D.; Bloom, E. D.; Bottacini, E.; Antolini, E.; Bonamente, E.; Baldini, L.; Ballet, J.; Bastieri, D.; Bellazzini, R.; Bregeon, J.; Bouvier, A.; Brandt, T. J.; Brigida, M.; Bruel, P. E-mail: allafort@stanford.edu [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS and others

    2013-07-01

    In this paper, we present the Fermi All-sky Variability Analysis (FAVA), a tool to systematically study the variability of the gamma-ray sky measured by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. For each direction on the sky, FAVA compares the number of gamma-rays observed in a given time window to the number of gamma-rays expected for the average emission detected from that direction. This method is used in weekly time intervals to derive a list of 215 flaring gamma-ray sources. We proceed to discuss the 27 sources found at Galactic latitudes smaller than 10 Degree-Sign and show that, despite their low latitudes, most of them are likely of extragalactic origin.

  16. Carbohydrate intake and food sources of junior triathletes during a moderate and an intensive training period.

    PubMed

    Carlsohn, Anja; Nippe, Susanne; Heydenreich, Juliane; Mayer, Frank

    2012-12-01

    The study was conducted to investigate the quantity and the main food sources of carbohydrate (CHO) intake of junior elite triathletes during a short-term moderate (MOD; 12 km swimming, 100 km cycling, 30 km running per wk) and intensive training period (INT; 23 km swimming, 200 km cycling, 45 km running per wk). Self-reported dietary-intake data accompanied by training protocols of 7 male triathletes (18.1 ± 2.4 yr, 20.9 ± 1.4 kg/m(2)) were collected on 7 consecutive days during both training periods in the same competitive season. Total energy and CHO intake were calculated based on the German Food Database. A paired t test was applied to test for differences between the training phases (α = .05). CHO intake was slightly higher in INT than in MOD (9.0 ± 1.6 g · kg(-1) · d(-1) vs. 7.8 ± 1.6 g · kg(-1) · d(-1); p = .041). Additional CHO in INT was mainly ingested during breakfast (115 ± 37 g in MOD vs. 175 ± 23 g in INT; p = .002) and provided by beverages (280.5 ± 97.3 g/d vs. 174.0 ± 58.3 g/d CHO; p = .112). Altogether, main meals provided approximately two thirds of the total CHO intake. Pre- and postexercise snacks additionally supplied remarkable amounts of CHO (198.3 ± 84.3 g/d in INT vs. 185.9 ± 112 g/d CHO in MOD; p = .231). In conclusion, male German junior triathletes consume CHO in amounts currently recommended for endurance athletes during moderate to intensive training periods. Main meals provide the majority of CHO and should therefore not be skipped. CHO-containing beverages, as well as pre- and postexercise snacks, may provide a substantial amount of CHO intake in training periods with high CHO requirements.

  17. Measurement of the ambient gamma dose equivalent and kerma from the small 252Cf source at 1 meter and the small 60Co source at 2 meters

    SciTech Connect

    Carl, W. F.

    2015-07-30

    NASA Langley Research Center requested a measurement and determination of the ambient gamma dose equivalent rate and kerma at 100 cm from the 252Cf source and determination of the ambient gamma dose equivalent rate and kerma at 200 cm from the 60Co source for the Radiation Budget Instrument Experiment (Rad-X). An Exradin A6 ion chamber with Shonka air-equivalent plastic walls in combination with a Supermax electrometer were used to measure the exposure rate and free-in-air kerma rate of the two sources at the requested distances. The measured gamma exposure, kerma, and dose equivalent rates are tabulated.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  19. Multipurpose Radiation Resistant Semiconductor Detectors for Alpha, Neutron & Low Energy Gamma Ray Measurements at High Temperatures in High-Intensity Gamma Ray

    SciTech Connect

    Ruddy, Frank H

    2005-06-01

    Work scheduled under year two of DOE Grant DE-FG02-04ER63734 is on schedule and all year-two milestones have or will be met. Results to date demonstrate that unprecedented silicon carbide (SiC) energy resolution has been obtained, and that SiC detectors may achieve energy resolution that exceeds that obtainable with the best silicon alpha spectrometers. Fast-neutron energy spectrometry measurements indicate that recoil-ion energy spectrometry should be possible with SiC detectors. Furthermore, SiC detectors have been demonstrated to perform well even after gamma-ray exposures of 1.E09 Rad. This result and the previously demonstrated capability of SiC detectors to operate in elevated-temperature environments are very promising for potential DOE EMSP applications. A new class of multipurpose, radiation-resistant semiconductor detectors that can be used in elevated-temperature and high-radiation environments is being developed under this grant.

  20. UNVEILING THE NATURE OF THE UNIDENTIFIED GAMMA-RAY SOURCES. IV. THE SWIFT CATALOG OF POTENTIAL X-RAY COUNTERPARTS

    SciTech Connect

    Paggi, A.; D'Abrusco, R.; Smith, H. A.; Massaro, F.; Funk, S.; Masetti, N.; Giroletti, M.; Tosti, G.

    2013-11-01

    A significant fraction (∼30%) of the high-energy γ-ray sources listed in the second Fermi Large Area Telescope (LAT) catalog are still of unknown origin, having not yet been associated with counterparts at lower energies. To investigate the nature of these enigmatic sources, we present an extensive search of X-ray sources lying in the positional uncertainty region of a selected sample of these unidentified gamma-ray sources (UGSs) that makes use of all available observations performed by the Swift X-ray Telescope before 2013 March 31, available for 205 UGSs. To detect the fainter sources, we merged all the observations covering the Fermi LAT positional uncertainty region at a 95% level of confidence of each UGS. This yields a catalog of 357 X-ray sources, finding candidate X-ray counterparts for ∼70% of the selected sample. In particular, 25% of the UGSs feature a single X-ray source within their positional uncertainty region, while 45% have multiple X-ray sources. For each X-ray source, we also looked in the corresponding Swift UVOT merged images for optical and ultraviolet counterparts, also performing source photometry. We found ultraviolet-optical correspondences for ∼70% of the X-ray sources. We searched several major radio, infrared, optical, and ultraviolet surveys for possible counterparts within the positional error of the sources in the X-ray catalog to obtain additional information on their nature. Applying the kernel density estimation technique to infrared colors of Wide-Field Infrared Survey Explorer counterparts of our X-ray sources we select six γ-ray blazar candidates. In addition, comparing our results with previous analyses, we select 11 additional γ-ray blazar candidates.