WorldWideScience

Sample records for burst high-energy lags

  1. Spectral Lag Evolution among -Ray Burst Pulses

    Indian Academy of Sciences (India)

    Lan-Wei Jia; Yun-Feng Liang; En-Wei Liang

    2014-09-01

    We analyse the spectral lag evolution of -ray burst (GRB) pulses with observations by CGRO/BATSE. No universal spectral lag evolution feature and pulse luminosity-lag relation within a GRB is observed.Our results suggest that the spectral lag would be due to radiation physics and dynamics of a given emission episode, possibly due to the longer lasting emission in a lower energy band, and the spectral lag may not be an intrinsic parameter to discriminate the long and short GRBs.

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

    CERN Document Server

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

    1999-01-01

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

  3. A simple theory of lags in gamma-ray bursts: Comparison to observations

    Science.gov (United States)

    Mochkovitch, R.; Heussaff, V.; Atteia, J. L.; Boçi, S.; Hafizi, M.

    2016-08-01

    Context. Lags observed between the light curves of a gamma-ray burst (GRB) seen in different energy bands are related to its spectral evolution. Moreover the lags have been found to correlate with burst luminosity, therefore providing a potential distance indicator. Aims: We want to quantify the nature of the link between lags and spectral evolution to better understand the origin of the lag-luminosity relation and evaluate its interest as a distance indicator. Methods: We directly relate the lag of a pulse to the spectral parameters (peak energy Ep, low and high energy indices, α and β, and their time derivatives) evaluated at pulse maximum. Then, using a Yonetoku-like relation we obtain a theoretical lag-luminosity relation that is confronted with data. Results: We first apply our model to the initial pulse of GRB 130427A, for which high quality data are available, to check quantitatively whether the measured lags are consistent with the observed spectral evolution. We then use a Monte Carlo approach to generate a sample of synthetic lags, which we compare to an observed sample of Swift bursts. The dispersion of both the observed and modelled lag-luminosity relations appears large, which questions the value of this relation as a reliable distance indicator.

  4. Spectral Lags of Gamma-Ray Bursts from Primordial Black Hole (PBH) Evaporations

    CERN Document Server

    Ukwatta, T N; Parke, W C; Dhuga, K S; Eskandarian, A; Gehrels, N; Maximon, L; Morris, D C

    2009-01-01

    Primordial Black Holes (PBHs), which may have been created in the early Universe, are predicted to be detectable by their Hawking radiation. PBHs with an initial mass of 5.0 * 10^14 g should be expiring today with a burst of high energy particles. Evaporating PBHs in the solar neighborhood are candidate Gamma-Ray Bursts (GRBs) progenitors. We propose spectral lag, which is the temporal delay between the high energy photon pulse and the low energy photon pulse, as a possible method to detect PBH evaporation events with the Fermi Gamma-ray Space Telescope Observatory.

  5. On the Kinematic Origin of the Luminosity-Pulse Lag Relationship in Gamma-ray Bursts

    OpenAIRE

    Salmonson, Jay D.

    2000-01-01

    This paper presents an interpretation based on gamma-ray burst source kinematics for the relationship found by Norris et al. between peak luminosity and energy-dependent pulse lag. I argue that the correlation should instead be between "number" luminosity and pulse lag. This interpretation improves the least-squares fit of this correlation for the known bursts by 25 percent or more. It also suggests a distance estimation scheme. I propose that this relationship is due to the variation in line...

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

    CERN Document Server

    Margutti, R

    2010-01-01

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

  7. Gamma-Ray Bursts at high and very high energies

    CERN Document Server

    Piron, F

    2015-01-01

    Gamma-Ray Bursts (GRBs) are extra-galactic and extremely energetic transient emissions of gamma rays, which are thought to be associated with the death of massive stars or the merger of compact objects in binary systems. Their huge luminosities involve the presence a newborn stellar-mass black hole emitting a relativistic collimated outflow, which accelerates particles and produces non-thermal emissions from the radio domain to the highest energies. In this article, I review recent progresses in the understanding of GRB jet physics above 100 MeV, based on Fermi observations of bright GRBs. I discuss the physical implications of these observations and their impact on GRB modeling, and I present some prospects for GRB observation at very high energies in the near future.

  8. Gamma-ray bursts at high and very high energies

    Science.gov (United States)

    Piron, Frédéric

    2016-06-01

    Gamma-Ray Bursts (GRBs) are extra-galactic and extremely energetic transient emissions of gamma rays, which are thought to be associated with the death of massive stars or the merger of compact objects in binary systems. Their huge luminosities involve the presence of a newborn stellar-mass black hole emitting a relativistic collimated outflow, which accelerates particles and produces non-thermal emissions from the radio domain to the highest energies. In this article, I review recent progresses in the understanding of GRB jet physics above 100 MeV, based on Fermi observations of bright GRBs. I discuss the physical implications of these observations and their impact on GRB modeling, and I present some prospects for GRB observation at very high energies in the near future. xml:lang="fr"

  9. Principal Component Analysis of Long-Lag, Wide-Pulse Gamma-Ray Burst Data

    Indian Academy of Sciences (India)

    Zhao-Yang Peng; Wen-Shuai Liu

    2014-09-01

    We have carried out a Principal Component Analysis (PCA) of the temporal and spectral variables of 24 long-lag, wide-pulse gamma-ray bursts (GRBs) presented by Norris et al. (2005). Taking all eight temporal and spectral parameters into account, our analysis shows that four principal components are enough to describe the variation of the temporal and spectral data of long-lag bursts. In addition, the first-two principal components are dominated by the temporal variables while the third and fourth principal components are dominated by the spectral parameters.

  10. The Lag-Luminosity Relation in the GRB Source Frame: An Investigation with Swift BAT Bursts

    Science.gov (United States)

    Ukwatta, T. N.; Dhuga, K. S.; Stamatikos, M.; Dermer, C. D.; Sakamoto, T.; Sonbas, E.; Parke, W. C.; Maximon, L. C.; Linnemann, J. T.; Bhat, P. N.; Eskandarian, A.; Gehrels, N.; Abeysekara, A. U.; Tollefson, K.; Norris, J. P.

    2011-01-01

    Spectral lag. which is defined as the difference in time of arrival of high- and low-energy photons. is a common feature in gamma-ray bursts (GRBs). Previous investigations have shown a correlation between this lag and the isotropic peak luminosity for long duration bursts. However. most of the previous investigations used lags extracted in the observer frame only. In this work (based on a sample of 43 Swift long GRBs with known redshifts). we present an analysis of the lag-luminosity relation in the GRB source frame. Our analysis indicates a higher degree of correlation -0.82 +/- 0.05 (chance probability of approx. 5.5 x 10(exp -5) between the spectral lag and the isotropic peak luminosity, L(sub iso). with a best-fitting power-law index of -1.2 +/- 0.2. In addition, there is an anticorrelation between the source-frame spectral lag and the source-frame peak energy of the burst spectrum.

  11. High-energy charged particle bursts in the near-Earth space as earthquake precursors

    Directory of Open Access Journals (Sweden)

    S. Yu. Aleksandrin

    Full Text Available The experimental data on high-energy charged particle fluxes, obtained in various near-Earth space experiments (MIR orbital station, METEOR-3, GAMMA and SAMPEX satellites were processed and analyzed with the goal to search for particle bursts. Particle bursts have been selected in every experiment considered. It was shown that the significant part of high-energy charged particle bursts correlates with seismic activity. Moreover, the particle bursts are observed several hours before strong earthquakes; L-shells of particle bursts and corresponding earthquakes are practically the same. Some features of a seismo-magnetosphere connection model, based on the interaction of electromagnetic emission of seismic origin and radiation belt particles, were considered.

    Key words. Ionospheric physics (energetic particles, trapped; energetic particles, precipitating; magnetosphere-ionosphere interactions

  12. Very High Energy Afterglow from Gamma-ray Bursts

    CERN Document Server

    Fan, Yi-Zhong; Narayan, Ramesh; Wei, Da-Ming

    2007-01-01

    We present self-consistent calculations of the very high energy (sub-GeV to TeV) inverse Compton emission of GRB afterglows. We argue that this emission provides a powerful test of the currently accepted afterglow model. We focus on two processes: synchrotron self-Compton (SSC) emission within the afterglow blast wave, and external inverse Compton (EIC) emission which occurs when flare photons (produced by an internal process) pass through the blast wave. We show that the high energy emission can be used to distinguish between different modifications of the standard afterglow model that have been considered in view of recent Swift observations. Our predictions can be tested with high energy observatories such as GLAST, Whipple, H.E.S.S., MAGIC and Kangaroo. Under favorable conditions we expect afterglow detections in all these detectors.

  13. High Energy Afterglow from Gamma-ray Bursts

    OpenAIRE

    Fan, Yi-Zhong(Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, 210008, China); Piran, Tsvi; Narayan, Ramesh; Wei, Da-Ming

    2007-01-01

    We calculate the very high energy (sub-GeV to TeV) inverse Compton emission of GRB afterglows. We argue that this emission provides a powerful test of the currently accepted afterglow model. We focus on two processes: synchrotron self-Compton (SSC) emission within the afterglow blast wave, and external inverse Compton (EIC) emission which occurs when flare photons (produced by an internal process) pass through the blast wave. We show that if our current interpretations of the Swift XRT data a...

  14. Evidence for Post-Quiescent, High-Energy Emission from Gamma-Ray Burst 990104

    OpenAIRE

    Wren, D. N.; Bertsch, D. L.; Ritz, S.

    2002-01-01

    It is well known that high-energy emission (MeV-GeV) has been observed in a number of gamma-ray bursts, and temporally-extended emission from lower energy gamma rays through radio wavelengths is well established. An important observed characteristic of some bursts at low energy is quiescence: an initial emission followed by a quiet period before a second (postquiescent) emission. Evidence for significant high-energy, postquiescent emission has been lacking. Here we present evidence for high-e...

  15. Ultra High Energy Neutrinos from Gamma-Ray Burst Afterglows Using the Swift-UVOT Data

    CERN Document Server

    Nir, Guy; Landsman, Hagar; Behar, Ehud

    2015-01-01

    We consider a sample of 107 Gamma Ray Bursts (GRBs) for which early UV emission was measured by Swift, and extrapolate the photon intensity to lower energies. Protons accelerated in the GRB jet may interact with such photons to produce charged pions and subsequently ultra high energy neutrinos $\\varepsilon_\

  16. Search for ultra-high-energy radiation from γ-ray bursts

    International Nuclear Information System (INIS)

    Using data from the CYGNUS extensive air shower array, we have searched for evidence of emission of ultra-high-energy radiation coincident with γ-ray bursts observed by the BATSE instrument on the Compton Gamma-Ray Observatory. No statistically significant excess was found for any point in the sky within 4σ of BATSE's best location coordinates for any of the 56 bursts examined. Furthermore, no events were seen in the 2.2 degree radius circular bin surrounding γ-ray burst GRB 920720, whose location was determined accurately by the Compton/Ulysses/PVO Interplanetary Network of satellites. Flux upper limits depend greatly on the actual zenith angle of the burst. Typical fluence upper limits above 100 TeV are ∼10-6 erg cm-2. The fluence upper limits for GRB 920720 is 2 x 10-6 erg cm-2

  17. The Lag-Luminosity Relation in the GRB Source-Frame: An Investigation with Swift BAT Bursts

    CERN Document Server

    Ukwatta, T N; Stamatikos, M; Dermer, C D; Sakamoto, T; Sonbas, E; Parke, W C; Maximon, L C; Linnemann, J T; Bhat, P N; Eskandarian, A; Gehrels, N; Abeysekara, U; Tollefson, K; Norris, J P

    2011-01-01

    Spectral lag, which is defined as the difference in time of arrival of high and low energy photons, is a common feature in Gamma-ray Bursts (GRBs). Previous investigations have shown a correlation between this lag and the isotropic peak luminosity for long duration bursts. However, most of the previous investigations used lags extracted in the observer-frame only. In this work (based on a sample of 43 Swift long GRBs with known redshifts), we present an analysis of the lag-luminosity relation in the GRB source-frame. Our analysis indicates a higher degree of correlation -0.82 +/- 0.05 (chance probability of ~ 5.5 x 10^-5) between the spectral lag and the isotropic peak luminosity, Liso, with a best-fit power-law index of -1.2 +/- 0.2, such that Liso proportional to lag^-1.2. In addition, there is an anti-correlation between the source-frame spectral lag and the source-frame peak energy of the burst spectrum, E_pk(1+z).

  18. The Lag-Luminosity Relation in the GRB Source-Frame: An Investigation with Swift BAT Bursts

    Science.gov (United States)

    Ukwatta, T. N.; Dhuga, K. S.; Stamatikos, M.; Dermer, C. D.; Sakamoto, T.; Sonbas, E.; Parke, W. C.; Maximon, L. C.; Linnemann, J. T.; Bhat, P. N.; Eskandarian, A.; Gehrels, N.; Abeysekara, U.; Tollefson, K.; Norris, J. P.

    2012-01-01

    Spectral lag, which is defined as the difference in time of arrival of high and low energy photons, is a common feature in Gamma-ray Bursts (GRBs). Previous investigations have shown a correlation between this lag and the isotropic peak luminosity for long duration bursts. However, most of the previous investigations used lags extracted in the observer-frame only. In this work (based on a sample of 43 Swift long GRBs with known redshifts), we present an analysis of the lag-luminosity relation in the GRB source-frame. Our analysis indicates a higher degree of correlation -0.82+/-0.05 (chance probability of approx 5.5 X 10(exp -5) between the spectral lag and the isotropic peak luminosity, L(sub iso), with a best-fit power-law index of -1.2 +/- 0.2, such that L(sub iso) varies as lag(exp -1.2). In addition, there is an anti-correlation between the source-frame spectral lag and the source-frame peak energy of the burst spectrum, E(sub pk)(1 + z).

  19. Comparing the spectral lag of short and long gamma-ray bursts and its relation with the luminosity

    CERN Document Server

    Bernardini, M G; Campana, S; Covino, S; Salvaterra, R; Atteia, J -L; Burlon, D; Calderone, G; D'Avanzo, P; D'Elia, V; Ghisellini, G; Heussaff, V; Lazzati, D; Melandri, A; Nava, L; Vergani, S D; Tagliaferri, G

    2014-01-01

    We investigated the rest frame spectral lags of two complete samples of bright long (50) and short (6) gamma-ray bursts (GRB) detected by Swift. We analysed the Swift/BAT data through a discrete cross-correlation function (CCF) fitted with an asymmetric Gaussian function to estimate the lag and the associated uncertainty. We find that half of the long GRBs have a positive lag and half a lag consistent with zero. All short GRBs have lags consistent with zero. The distributions of the spectral lags for short and long GRBs have different average values. Limited by the small number of short GRBs, we cannot exclude at more than 2 sigma significance level that the two distributions of lags are drawn from the same parent population. If we consider the entire sample of long GRBs, we do not find evidence for a lag-luminosity correlation, rather the lag-luminosity plane appears filled on the left hand side, thus suggesting that the lag-luminosity correlation could be a boundary. Short GRBs are consistent with the long ...

  20. Prompt and Delayed High-Energy Emission from Cosmological $\\gamma$-Ray Bursts

    CERN Document Server

    Böttcher, M

    1999-01-01

    In the cosmological blast-wave model for gamma ray bursts (GRBs), high energy (> 10 GeV) gamma-rays are produced either through Compton scattering of soft photons by ultrarelativistic electrons, or as a consequence of the acceleration of protons to ultrahigh energies. We describe the spectral and temporal characteristics of high energy gamma-rays produced by both mechanisms, and discuss how these processes can be distinguished through observations with low-threshold Cherenkov telescopes or GLAST. We propose that Compton scattering of starlight photons by blast wave electrons can produce delayed flares of GeV -- TeV radiation.

  1. A search for ultra-high energy counterparts to gamma-ray bursts

    CERN Document Server

    Plunkett, S P; McBreen, B; Hurley, K J; O'Sullivan, C T

    1995-01-01

    A small air shower array operating over many years has been used to search for ultra-high energy (UHE) gamma radiation (\\geq 50 TeV) associated with gamma-ray bursts (GRBs) detected by the BATSE instrument on the Compton Gamma-Ray Observatory (CGRO). Upper limits for a one minute interval after each burst are presented for seven GRBs located with zenith angles \\theta < 20^{\\circ}. A 4.3\\sigma excess over background was observed between 10 and 20 minutes following the onset of a GRB on 11 May 1991. The confidence level that this is due to a real effect and not a background fluctuation is 99.8\\%. If this effect is real then cosmological models are excluded for this burst because of absorption of UHE gamma rays by the intergalactic radiation fields.

  2. High Energy Observations of XRF 030723: Evidence for an Off-axis Gamma-Ray Burst?

    CERN Document Server

    Butler, N R; Suzuki, M; Kawai, N; Lamb, D Q; Graziani, C; Donaghy, T Q; Dullighan, A; Vanderspek, R; Crew, G B; Ford, P; Ricker, G; Atteia, J L; Yoshida, A; Shirasaki, Y; Tamagawa, T; Torii, K; Matsuoka, M; Fenimore, E E; Galassi, M; Doty, J; Villaseñor, J D; Prigozhin, G Y; Jernigan, J G; Barraud, C; Boër, M; Dezalay, J P; Olive, J F; Hurley, K; Levine, A; Martel, F; Morgan, E; Woosley, S E; Cline, T; Braga, J; Manchanda, R K; Pizzichini, G

    2004-01-01

    We report High Energy Transient Explorer 2 (HETE-2) Wide Field X-ray Monitor/French Gamma Telescope observations of XRF030723 along with observations of the XRF afterglow made using the 6.5m Magellan Clay telescope and the Chandra X-ray Observatory. The observed peak energy E_pk_obs of the nu F_nu burst spectrum is found to lie within (or below) the WXM 2-25 keV passband at 98.5% confidence, and no counts are detected above 30 keV. Our best fit value is E_pk_obs=8.4+3.5/-3.4 keV. The ratio of X-ray to Gamma-ray flux for the burst follows a correlation found for GRBs observed with HETE-2, and the duration of the burst is similar to that typical of long-duration GRBs. If we require that the burst isotropic equivalent energy E_iso and E_pk_rest satisfy the relation discovered by Amati et al. (2002), a redshift of z=0.38+0.36/-0.18 can be determined, in agreement with constraints determined from optical observations. We are able to fit the X-ray afterglow spectrum and to measure its temporal fade. Although the be...

  3. Klein-Nishina effects on the high-energy afterglow emission of gamma-ray bursts

    CERN Document Server

    Wang, Xiang-Yu; Li, Zhuo; Wu, Xue-Feng; Dai, Zi-Gao

    2009-01-01

    Extended high-energy(>100MeV) gamma-ray emission that lasts much longer than the prompt sub-MeV emission has been detected from quite a few gamma-ray bursts (GRBs) by Fermi Large Area Telescope (LAT) recently. A plausible scenario is that this emission is the afterglow synchrotron emission produced by electrons accelerated in the forward shocks. In this scenario, the electrons that produce synchrotron high-energy emission also undergo inverse-Compton (IC) loss and the IC scattering with the synchrotron photons should be in the Klein-Nishina regime. Here we study effects of the Klein-Nishina scattering on the high-energy synchrotron afterglow emission. We find that, at early times the Klein-Nishina suppression effect on those electrons that produce the high-energy emission is usually strong and therefore their inverse-Compton loss is small with a Compton parameter Y < a few for a wide range of parameter space. This leads to a relatively bright synchrotron afterglow at high energies that can be detected by F...

  4. The First Limits on the Ultra-high Energy Neutrino Fluence from Gamma-ray Bursts

    OpenAIRE

    Vieregg, A. G.; Palladino, K.; Allison, P.; Baughman, B. M.; Beatty, J. J.; Belov, K.; Besson, D. Z.; Bevan, S; Binns, W. R.; Chen, C.; Chen, P; Clem, J. M.; Connolly, A.; Detrixhe, M.; De Marco, D.

    2011-01-01

    We set the first limits on the ultra-high energy (UHE) neutrino fluence at energies greater than 10^9 GeV from gamma-ray bursts (GRBs) based on data from the second flight of the ANtarctic Impulsive Transient Antenna (ANITA). During the 31 day flight of ANITA-II, 26 GRBs were recorded by Swift or Fermi. Of these, we analyzed the 12 GRBs which occurred during quiet periods when the payload was away from anthropogenic activity. In a blind analysis, we observe 0 events on a total background of 0...

  5. Very High Energy Observations of Gamma Ray Bursts with the Whipple/VERITAS Telescopes

    International Nuclear Information System (INIS)

    Gamma-ray Burst (GRB) observations at Very High Energies (VHE, E > 100 GeV) can impose tight constraints on some GRB emission models. Many GRB after-glow models predict a VHE component similar to that seen in blazars and supernova remnants, in which the GRB spectral energy distribution has a double-peaked shape extending into the VHE regime. Consistent with this afterglow scenario, EGRET detected delayed high energy emission from all five bright BATSE GRBs that occurred within its field of view. GRB observations have had high priority in the observing program at the Whipple 10m Telescope and will continue to be high priority targets when the next generation observatory VERITAS comes online. Upper limits on the VHE emission from ten GRBs observed with the Whipple Telescope are reported here

  6. Spectral lag of gamma-ray burst caused by the intrinsic spectral evolution and the curvature effect

    OpenAIRE

    Peng, Z. Y.; Y. Yin; Bi, X. W.; Bao, Y. Y.; Ma, L

    2011-01-01

    Assuming an intrinsic `Band' shape spectrum and an intrinsic energy-independent emission profile we have investigated the connection between the evolution of the rest-frame spectral parameters and the spectral lags measured in gamma-ray burst (GRB) pulses by using a pulse model. We first focus our attention on the evolution of the peak energy, $E_{0,p}$, and neglect the effect of the curvature effect. It is found that the evolution of $E_{0,p}$ alone can produce the observed lags. When $E_{0,...

  7. The First Limits on the Ultra-high Energy Neutrino Fluence from Gamma-ray Bursts

    CERN Document Server

    Vieregg, A G; Allison, P; Baughman, B M; Beatty, J J; Belov, K; Besson, D Z; Bevan, S; Binns, W R; Chen, C; Chen, P; Clem, J M; Connolly, A; Detrixhe, M; De Marco, D; Dowkontt, P F; DuVernois, M; Gorham, P W; Grashorn, E W; Hill, B; Hoover, S; Huang, M; Israel, M H; Javaid, A; Liewer, K M; Matsuno, S; Mercurio, B C; Miki, C; Mottram, M; Nam, J; Nichol, R J; Romero-Wolf, A; Ruckman, L; Saltzberg, D; Seckel, D; Varner, G S; Wang, Y

    2011-01-01

    We set the first limits on the ultra-high energy (UHE) neutrino fluence at energies greater than 10^9 GeV from gamma-ray bursts (GRBs) based on data from the second flight of the ANtarctic Impulsive Transient Antenna (ANITA). During the 31 day flight of ANITA-II, 26 GRBs were recorded by Swift or Fermi. Of these, we analyzed the 12 GRBs which occurred during quiet periods when the payload was away from anthropogenic activity. In a blind analysis, we observe 0 events on a total background of 0.0044 events in the combined prompt window for all 12 low-background bursts. We also observe 0 events from the remaining 14 bursts. We place a 90% confidence level limit on the E^-4 prompt neutrino fluence of 2.5x10^17 GeV^3/cm^2 between 10^8 and 10^12 GeV from GRB090107A. This is the first reported limit on the UHE neutrino fluence from GRBs above 10^9 GeV, and the strongest limit above 10^8 GeV.

  8. Neutrino emission from high-energy component gamma-ray bursts

    CERN Document Server

    Becker, Julia K; O'Murchadha, Aongus; Olivo, Martino

    2010-01-01

    Gamma-ray bursts have the potential to produce the particle energies (up to $10^{21}$\\,eV) and the energy budget ($10^{44}\\, \\rm{erg\\, yr^{-1}\\, Mpc^{-3}}$) to accommodate the spectrum of the highest energy cosmic rays; on the other hand, there is no observational evidence that they accelerate hadrons. The Fermi GST recently observed two bursts that exhibit a power-law high-energy extension of the typical (Band) photon spectrum that extends to $\\sim 30$ GeV. On the basis of fireball phenomenology we argue that they, along with GRB941017 observed by EGRET in 1994, show indirect evidence for considerable baryon loading. Since the detection of neutrinos is the only unambiguous way to establish that GRBs accelerate protons, we use two methods to estimate the neutrino flux produced when they interact with fireball photons to produce charged pions and neutrinos. While the number of events expected from the Fermi bursts detected to date is small, we conclude that an event like GRB941017 will be detected by the IceCu...

  9. Possibility of observing high energy neutrinos from gamma bursts, with the Antanares telescope, feasibility study

    International Nuclear Information System (INIS)

    The European Antares collaboration intends to build a deep-sea neutrino telescope with a detection surface of about 1/10 km2 in the Mediterranean sea. The universe is transparent to neutrinos, so their study provides a unique means of improving our knowledge of the nature and origin of cosmic rays and their emission from the most powerful astrophysical sources in the cosmos. Neutrinos also offer the possibility of opening a new energy window (E>TeV) for observation of the universe. The first part of the thesis is dedicated to a study of the possibility of using the future telescope to look for correlations between gamma-ray bursts and high-energy neutrinos. It is based, on one hand, on the predictions of neutrino fluxes from gamma-ray bursts in the framework of the theoretical model of 'fireballs', and, on the other hand, on the temporal properties of the gamma-ray bursts in the 4. BATSE catalogue. The second part of the thesis presents the results obtained with a prototype detector line deployed, at the end of 1999, some forty km south-west off Marseilles. The objective was to operate a complete apparatus, similar to the future detector lines, from the shore, and under realistic conditions. Data from 7 photomultiplier tubes disposed along the detector line were transmitted through 37 km of optical fiber to the shore, where they were used to reconstruct tracks due to atmospheric muons, thus validating the detection principles and methods. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Yi-Zhong; Piran, Tsvi

    2011-11-29

    Gamma-ray bursts (GRBs) are short and intense emission of soft {gamma}-rays, which have fascinated astronomers and astrophysicists since their unexpected discovery in 1960s. The X-ray/optical/radio afterglow observations confirm the cosmological origin of GRBs, support the fireball model, and imply a long-activity of the central engine. The high-energy {gamma}-ray emission (> 20 MeV) from GRBs is particularly important because they shed some lights on the radiation mechanisms and can help us to constrain the physical processes giving rise to the early afterglows. In this work, we review observational and theoretical studies of the high-energy emission from GRBs. Special attention is given to the expected high-energy emission signatures accompanying the canonical early-time X-ray afterglow that was observed by the Swift X-ray Telescope. We also discuss the detection prospect of the upcoming GLAST satellite and the current ground-based Cerenkov detectors.

  11. Gamma Ray Bursts: recent results and connections to very high energy Cosmic Rays and Neutrinos

    CERN Document Server

    Mészáros, Péter; Veres, Péter

    2012-01-01

    Gamma-ray bursts are the most concentrated explosions in the Universe. They have been detected electromagnetically at energies up to tens of GeV, and it is suspected that they could be active at least up to TeV energies. It is also speculated that they could emit cosmic rays and neutrinos at energies reaching up to the $10^{18}-10^{20}$ eV range. Here we review the recent developments in the photon phenomenology in the light of \\swift and \\fermi satellite observations, as well as recent IceCube upper limits on their neutrino luminosity. We discuss some of the theoretical models developed to explain these observations and their possible contribution to a very high energy cosmic ray and neutrino background.

  12. Very High Energy Observations of Gamma-Ray Burst Locations with the Whipple Telescope

    CERN Document Server

    Horan, D; Badran, H M; Blaylock, G; Bradbury, S M; Buckley, J H; Byrum, K L; Celik, O; Chow, Y C K; Cogan, P; Cui, W; Daniel, M K; Perez, I de la Calle; Dowdall, C; Falcone, A D; Fegan, D J; Fegan, S J; Finley, J P; Fortin, P; Fortson, L F; Gillanders, G H; Grube, J; Gutíerrez, K J; Hall, J; Hanna, D; Holder, J; Hughes, S B; Humensky, T B; Kenny, G E; Kertzman, M; Kieda, D B; Kildea, J; Krawczynski, H; Krennrich, F; Lang, M J; Le Bohec, S; Maier, G; Moriarty, P; Nagai, T; Ong, R A; Perkins, J S; Petry, D; Quinn, J; Quinn, M; Ragan, K; Reynolds, P T; Rose, H J; Schroedter, M; Sembroski, G H; Steele, D; Swordy, S P; Toner, J A; Valcarcel, L; Vasilev, V V; Wagner, R G; Wakely, S P; Weekes, T C; White, R J; Williams, D A; 10.1086/509567

    2008-01-01

    Gamma-ray burst (GRB) observations at very high energies (VHE, E > 100 GeV) can impose tight constraints on some GRB emission models. Many GRB afterglow models predict a VHE component similar to that seen in blazars and plerions, in which the GRB spectral energy distribution has a double-peaked shape extending into the VHE regime. VHE emission coincident with delayed X-ray flare emission has also been predicted. GRB follow-up observations have had high priority in the observing program at the Whipple 10m Gamma-ray Telescope and GRBs will continue to be high priority targets as the next generation observatory, VERITAS, comes on-line. Upper limits on the VHE emission, at late times (>~4 hours), from seven GRBs observed with the Whipple Telescope are reported here.

  13. Inspecting the supernova gamma-ray burst connection with high-energy neutrinos

    CERN Document Server

    Tamborra, Irene

    2015-01-01

    Long-duration gamma-ray bursts (GRBs) have been often considered as the natural evolution of core-collapse supernovae (SNe). While GRBs with relativistic jets emit an electromagnetic signal, GRBs with mildly relativistic jets are opaque to photons and, therefore, could be detectable through neutrinos only. We discuss the possibility that successful GRBs and choked jets belong to the same class of astrophysical transients with different Lorentz factor Gamma_b and study the production of high-energy neutrinos as a function of Gamma_b, by including both proton-photon and proton-proton interactions. By assuming a SN-GRB connection, we find that the diffuse neutrino emission from optically thick jets with intermediate Lorentz factors with respect to the ones of choked and successful GRBs can be one of the main components of the observed IceCube high-energy neutrino flux. Moreover, under the assumption that choked and successful jets belong to the same class of astrophysical transients, we show that the IceCube hig...

  14. High Energy Neutrinos and Cosmic-Rays from Low-Luminosity Gamma-Ray Bursts?

    CERN Document Server

    Murase, K; Nagataki, S; Nakamura, T; Murase, Kohta; Ioka, Kunihito; Nagataki, Shigehiro; Nakamura, Takashi

    2006-01-01

    The recently discovered gamma-ray burst (GRB) 060218/SN 2006aj is classified as an X-ray Flash with very long duration driven possibly by a neutron star. Since GRB 060218 is very near 140 Mpc and very dim, one-year observation by Swift suggests that the true rate of GRB 060218-like events might be very high so that such low luminosity GRBs (LL-GRBs) might form a different population of GRBs from the cosmological high luminosity GRBs (HL-GRBs). We found that the high energy neutrino background from such LL-GRBs could be comparable with or larger than that from HL-GRBs. If each neutrino event is detected by IceCube, later optical-infrared follow-up observations such as by Subaru could identify a Type Ibc supernova associated with LL-GRBs, even if gamma- and X-rays are not observed by Swift. This is in a sense a new window from neutrino astronomy, which might enable us to confirm the existence of LL-GRBs and to obtain information about their rate and origin. We also argue LL-GRBs as high energy gamma-ray and cos...

  15. Relations between Microwave Bursts and near-Earth High-Energy Proton Enhancements and their Origin

    CERN Document Server

    Grechnev, V V; Meshalkina, N S; Chertok, I M

    2015-01-01

    We further study the relations between parameters of bursts at 35 GHz recorded with the Nobeyama Radio Polarimeters during 25 years, on the one hand, and solar proton events, on the other hand (Grechnev et al. in Publ. Astron. Soc. Japan 65, S4, 2013a). Here we address the relations between the microwave fluences at 35 GHz and near-Earth proton fluences above 100 MeV in order to find information on their sources and evaluate their diagnostic potential. A correlation was found to be pronouncedly higher between the microwave and proton fluences than between their peak fluxes. This fact probably reflects a dependence of the total number of protons on the duration of the acceleration process. In events with strong flares, the correlation coefficients of high-energy proton fluences with microwave and soft X-ray fluences are higher than those with the speeds of coronal mass ejections. The results indicate a statistically larger contribution of flare processes to high-energy proton fluxes. Acceleration by shock wave...

  16. Dependence of Temporal Properties on Energy in Long-Lag, Wide-Pulse Gamma-Ray Bursts

    OpenAIRE

    Zhang, Fu-Wen; Qin, Yi-Ping; Zhang, Bin-Bin

    2007-01-01

    We employed a sample compiled by Norris et al. (2005, ApJ, 625, 324) to study the dependence of the pulse temporal properties on energy in long-lag, wide-pulse gamma-ray bursts. Our analysis shows that the pulse peak time, rise time scale and decay time scale are power law functions of energy, which is a preliminary report on the relationships between the three quantities and energy. The power law indexes associated with the pulse width, rise time scale and decay time scale are correlated and...

  17. High Energy Neutrinos from the Gravitational Wave event GW150914 possibly associated with a short Gamma-Ray Burst

    CERN Document Server

    Moharana, Reetanjali; Gupta, Nayantara; Meszaros, Peter

    2016-01-01

    High-energy neutrino (HEN) and gravitational wave (GW) can probe astrophysical sources in addition to electromagnetic observations. Multimessenger studies can reveal nature of the sources which may not be discerned from one type of signal alone. We discuss HEN emission in connection with the Advanced Laser Interferometer Gravitational-wave Observatory (ALIGO) event GW150914 which could be associated with a short gamma-ray burst (GRB) detected by the $Fermi$ Gamma-ray Burst Monitor (GBM) 0.4 s after the GW event and within localization uncertainty of the GW event. We calculate HEN flux from this short GRB, GW150914-GBM, and show that non-detection of a high-energy starting event (HESE) by the IceCube Neutrino Observatory can constrain the total isotropic-equivalent jet energy of this short burst to be less than $3\\times 10^{52}$ erg.

  18. Stacked search for time shifted high energy neutrinos from gamma ray bursts with the \\ANTARES neutrino telescope

    CERN Document Server

    Adrian-Martínez, S; André, M; Anton, G; Ardid, M; Aubert, J -J; Baret, B; Barrios-Marti, J; Basa, S; Bertin, V; Biagi, S; Bormuth, R; Bouwhuis, M C; Bruijn, R; Brunner, J; Busto, J; Capone, A; Caramete, L; Carr, J; Chiarusi, T; Circella, M; Coniglione, R; Costantini, H; Coyle, P; Creusot, A; Dekeyser, I; Deschamps, A; De Bonis, G; Distefano, C; Donzaud, C; Dornic, D; Drouhin, D; Dumas, A; Eberl, T; Elsasser, D; Enzenhofer, A; Fehn, K; Felis, I; Fermani, P; Folger, F; Fusco, L A; Galatà, S; Gay, P; Geisselsoeder, S; Geyer, K; Giordano, V; Gleixner, A; Gracia-Ruiz, R; Graf, K; Hallmann, S; van Haren, H; Heijboer, A J; Hello, Y; Hernàndez-Rey, J J; Hoessl, J; Hofestadt, J; Hugon, C; James, C W; de Jong, M; Kadler, M; Kadler, M; Kalekin, O; Katz, U; Kiessling, D; Kooijman, P; Kouchner, A; Kreter, M; Kreykenbohm, I; Kulikovskiy, V; Lahmann, R; Lefèvre, D; Leonora, E; Marcelin, M; Margiotta, A; Marinelli, A; Martínez-Mora, J A; Mathieu, A; Michael, T; Migliozzi, P; Moussa, A; Muller, C; Nezri, E; Pavalas, G E; Pellegrino, C; Perrina, C; Piattelli, P; Popa, V; Pradier, T; Racca, C; Riccobene, G; Richter, R; Roensch, K; Saldaña, M; Samtleben, D F E; Sánchez-Losa, A; Sanguineti, M; Sapienza, P; Schmid, J; Schnabel, J; Schussler, F; Seitz, T; Sieger, C; Spurio, M; Steijger, J J M; Stolarczyk, Th; Taiuti, M; Tamburini, C; Trovato, A; Tselengidou, M; Tonnis, C; Vallage, B; Vallée, C; Van Elewyck, V; Visser, E; Vivolo, D; Wagner, S; Wilms, J; Zornoza, J D; Zúñiga, J

    2016-01-01

    A search for high-energy neutrino emission correlated with gamma-ray bursts outside the electromagnetic prompt-emission time window is presented. Using a stacking approach of the time delays between reported gamma-ray burst alerts and spatially coincident muon-neutrino signatures, data from the Antares neutrino telescope recorded between 2007 and 2012 are analysed. One year of public data from the IceCube detector between 2008 and 2009 have been also investigated. The respective timing pro?les are scanned for statistically significant accumulations within 40 days of the Gamma Ray Burst, as expected from Lorentz Invariance Violation effects and some astrophysical models. No significant excess over the expected accidental coincidence rate could be found in either of the two data sets. The average strength of the neutrino signal is found to be fainter than one detectable neutrino signal per hundred gamma-ray bursts in the Antares data at 90% confidence level.

  19. Effects of Cosmic Infrared Background on High Energy Delayed Gamma-Rays From Gamma-Ray Bursts

    Energy Technology Data Exchange (ETDEWEB)

    Murase, Kohta; /Kyoto U., Yukawa Inst., Kyoto; Asano, Katsuaki; /Natl. Astron. Observ. of Japan; Nagataki, Shigehiro; /Kyoto U., Yukawa Inst., Kyoto /KIPAC, Menlo Park

    2007-04-06

    Regenerated high energy emissions from gamma-ray bursts (GRBs) are studied in detail. If the primary emission spectrum extends to TeV range, these very high energy photons will be absorbed by the cosmic infrared background (CIB). The created high energy electron-positron pairs up-scatter not only cosmic microwave background (CMB) photons but also CIB photons, and secondary photons are generated in the GeV-TeV range. These secondary delayed photons may be observed in the near future, and useful for a consistency check for the primary spectra and GRB physical parameters. The up-scattered CIB photons cannot be neglected for low redshift bursts and/or GRBs with a relatively low maximum photon energy. The secondary gamma-rays also give us additional information on the CIB, which is uncertain in observations so far.

  20. Features of >130 Gamma-Ray Bursts at high energy: towards the 2nd Fermi LAT GRB catalog

    Science.gov (United States)

    Vianello, Giacomo; Omodei, Nicola; Fermi LAT Collaboration

    2016-01-01

    The high-energy emission from Gamma-Ray Bursts is a formidable probe for extreme physics, calling for highly relativistic sources with very large Lorentz factors. Despite the advancements prompted by observations from the Fermi Large Area Telescope and the Fermi Gamma-Ray Burst Monitor, as well as other observatories, many questions remain open, especially on radiative processes and mechanisms. We present here the most extensive search for GRBs at high energies performed so far, featuring a detection efficiency more than 50% better than previous works, and returning more than 130 detections. With this sample size, much larger than the 35 detections presented in the first Fermi/LAT GRB catalog, we are able to assess the characteristics of the population of GRBs at high energy with unprecedented sensitivity. We will review the preliminary results of this work, as well as their interpretation.

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

    CERN Document Server

    Baerwald, Philipp; Winter, Walter

    2014-01-01

    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 corres...

  2. The Eas Bursts - High Energy Extensive Air Showers Correlated in Time

    CERN Document Server

    Barnaveli, T T; Eristavi, N A; Khaldeeva, I V; Chubenko, A P; Nesterova, N M

    2009-01-01

    Bursts of high energy EAS intensity (the series of EAS), following each other in short intervals of time were observed by means of Tien-Shan high mountain installation. For the lower boundary of EAS, uniting in one series, the size Ne= 10**6 (primary energies of the order of 4x10**15 eV) was taken. The condition of amalgamation into one series was the presence of at least two EAS of Ne >10**7. The number of EAS in a series is from 4 to 9 events, with the mean time interval between them 1-5 minutes. Five such series were found in the material treated (approximately 250 days of pure time of the installation run). For each EAS of each series, all the basic parameters are given: observation date and time, age parameter S, galactic coordinates, coordinates of EAS axes relative to the installation center, energy release in the calorimeter and its distance from EAS axes, fitting the Nishimura- Kamata- Greisen (NKG) function. It is essential, that the frequency of the appearing of such series is much higher, than the...

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

    Energy Technology Data Exchange (ETDEWEB)

    Baerwald, Philipp [Wuerzburg Univ. (Germany). Inst. fuer Theoretische Physik und Astrophysik; Pennsylvania State Univ., University Park, PA (United States). Dept. of Astronomy and Astrophysics; Pennsylvania State Univ., University Park, PA (United States). Dept. of Physics; Pennsylvania State Univ., University Park, PA (United States). Center for Particle and Gravitational Astrophysics; Pennsylvania State Univ., University Park, PA (United States). Inst. for Gravitation and the Cosmos; Bustamante, Mauricio; Winter, Walter [Wuerzburg Univ. (Germany). Inst. fuer Theoretische Physik und Astrophysik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2014-07-15

    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.

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

    International Nuclear Information System (INIS)

    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.

  5. Solution High-Energy Burst Assembly (SHEBA) results from subprompt critical experiments with uranyl fluoride fuel

    Energy Technology Data Exchange (ETDEWEB)

    Cappiello, C.C.; Butterfield, K.B.; Sanchez, R.G. [and others

    1997-10-01

    The Solution High-Energy Burst Assembly (SHEBA) was originally constructed during 1980 and was designed to be a clean free-field geometry, right-circular, cylindrically symmetric critical assembly employing U(5%)O{sub 2}F{sub 2} solution as fuel. A second version of SHEBA, employing the same fuel but equipped with a fuel pump and shielding pit, was commissioned in 1993. This report includes data and operating experience for the 1993 SHEBA only. Solution-fueled benchmark work focused on the development of experimental measurements of the characterization of SHEBA; a summary of the results are given. A description of the system and the experimental results are given in some detail in the report. Experiments were designed to: (1) study the behavior of nuclear excursions in a low-enrichment solution, (2) evaluate accidental criticality alarm detectors for fuel-processing facilities, (3) provide radiation spectra and dose measurements to benchmark radiation transport calculations on a low-enrichment solution system similar to centrifuge enrichment plants, and (4) provide radiation fields to calibrate personnel dosimetry. 15 refs., 37 figs., 10 tabs.

  6. Solution High-Energy Burst Assembly (SHEBA) results from subprompt critical experiments with uranyl fluoride fuel

    International Nuclear Information System (INIS)

    The Solution High-Energy Burst Assembly (SHEBA) was originally constructed during 1980 and was designed to be a clean free-field geometry, right-circular, cylindrically symmetric critical assembly employing U(5%)O2F2 solution as fuel. A second version of SHEBA, employing the same fuel but equipped with a fuel pump and shielding pit, was commissioned in 1993. This report includes data and operating experience for the 1993 SHEBA only. Solution-fueled benchmark work focused on the development of experimental measurements of the characterization of SHEBA; a summary of the results are given. A description of the system and the experimental results are given in some detail in the report. Experiments were designed to: (1) study the behavior of nuclear excursions in a low-enrichment solution, (2) evaluate accidental criticality alarm detectors for fuel-processing facilities, (3) provide radiation spectra and dose measurements to benchmark radiation transport calculations on a low-enrichment solution system similar to centrifuge enrichment plants, and (4) provide radiation fields to calibrate personnel dosimetry. 15 refs., 37 figs., 10 tabs

  7. Ultra-high Energy Cosmic Rays and Neutrinos from Gamma-Ray Bursts, Hypernovae and Galactic Shocks

    CERN Document Server

    Mészáros, P

    2014-01-01

    I review gamma-ray burst models (GRBs) and observations, and discuss the possible production of ultra-high energy cosmic rays and neutrinos in both the standard internal shock models and the newer generation of photospheric and hadronic GRB models, in the light of current constraints imposed by IceCube, Auger and TA observations. I then discuss models that have been proposed to explain the recent astrophysical PeV neutrino observations, including star-forming and star-burst galaxies, hypernovae and galaxy accretion and merger shocks.

  8. Ultra-high Energy Cosmic Rays and Neutrinos from Gamma-Ray Bursts, Hypernovae and Galactic Shocks

    International Nuclear Information System (INIS)

    I review gamma-ray burst models (GRBs) and observations, and discuss the possible production of ultra-high energy cosmic rays and neutrinos in both the standard internal shock models and the newer generation of photospheric and hadronic GRB models, in the light of current constraints imposed by IceCube, Auger and TA observations. I then discuss models that have been proposed to explain the recent astrophysical PeV neutrino observations, including star-forming and star-burst galaxies, hypernovae and galaxy accretion and merger shocks

  9. On the burst activity of the Crab Nebula and pulsar at high and ultra-high energies

    International Nuclear Information System (INIS)

    Recent experiments with satellite gamma-ray telescopes Fermi-LAT and AGILE in which bursts of gamma-rays from the Crab Nebula were detected in the energy range around 100 MeV have aroused keen interest, if not sensation. However, as long ago as more than 20 years from now the data on a possible burst in the Crab Nebula at much higher energies, about 100 TeV, were published. Characteristics of transient and stationary fluxes of gamma rays from the Crab Nebula in various energy ranges are discussed in this paper, and it is shown that the old data obtained at ultra-high energy can be reasonably consistent with the modern pattern of burst activity of the source.

  10. Burst train generator of high energy femtosecond laser pulses for driving heat accumulation effect during micromachining.

    Science.gov (United States)

    Rezaei, Saeid; Li, Jianzhao; Herman, Peter R

    2015-05-01

    A new method for generating high-repetition-rate (12.7-38.2 MHz) burst trains of femtosecond laser pulses has been demonstrated for the purpose of tailoring ultrashort laser interactions in material processing that can harness the heat accumulation effect among pulses separated by a short interval (i.e., 26 ns). Computer-controlled time delays were applied to synchronously trigger the high frequency switching of a high voltage Pockels cell to specify distinctive values of polarization rotation for each round-trip of a laser pulse cycling within a passive resonator. Polarization dependent output coupling facilitated the flexible shaping of the burst envelope profile to provide burst trains of up to ∼1  mJ of burst energy divided over a selectable number (1 to 25) of pulses. Individual pulses of variable energy up to 150 μJ and with pulse duration tunable over 70 fs to 2 ps, were applied in burst trains to generate deep and high aspect ratio holes that could not form with low-repetition-rate laser pulses. PMID:25927785

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

    OpenAIRE

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

    2009-01-01

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

  12. Ultra-high Energy Neutrinos from Gamma-Ray Burst Afterglows Using the Swift-UVOT Data

    Science.gov (United States)

    Nir, Guy; Guetta, Dafne; Landsman, Hagar; Behar, Ehud

    2016-02-01

    We consider a sample of 107 gamma-ray bursts (GRBs) for which early ultra-violet emission was measured by Swift and extrapolate the photon intensity to lower energies. Protons accelerated in the GRB jet may interact with such photons to produce charged pions and subsequently ultra high energy neutrinos {\\varepsilon }ν ≥slant {10}16 eV. We use simple energy conversion efficiency arguments to predict the maximal neutrino flux expected from each GRB. We estimate the neutrino detection rate at large area radio based neutrino detectors and conclude that the early afterglow neutrino emission is too weak to be detected even by next generation neutrino observatories.

  13. High-energy emission from bright gamma-ray bursts using Fermi

    International Nuclear Information System (INIS)

    Among the scientific objectives of one of the present NASA missions, the Fermi Gamma-ray Space Telescope (FGST), is the study of gamma-ray bursts (GRBs). Fermi's payload comprises two science instruments, the Large Area Telescope (LAT) and the Gamma-Ray Burst Monitor (GBM). GBM was designed to detect and localize bursts for the Fermi mission. By means of an array of 12 NaI(Tl) (8 keV to 1 MeV) and two BGO (0.2 to 40 MeV) scintillation detectors, GBM extends the energy range (20 MeV to > 300 GeV) of the LAT instrument into the traditional range of current GRB databases. The physical detector response of the GBM instrument to GRBs has been determined with the help of Monte Carlo simulations, which are supported and verified by on-ground individual detector calibration measurements. The GBM detectors have been calibrated from 10 keV to 17.5 MeV using various gamma sources, and the detector response has been derived by simulations over the entire energy range (8 keV to 40 MeV) using GEANT. The GBM instrument has been operating successfully in orbit since June 11, 2008. The total trigger count from the time GBM triggering was enabled in July 2008 through December 2009 is 655, and about 380 of these triggers were classified as GRBs. Moreover, GBM detected several bursts in common with the LAT. These amazing detections mainly fulfill the primary science goal of GBM, which is the joint analysis of spectra and time histories of GRBs observed by both Fermi instruments. For every trigger, GBM provides near-real time on-board burst locations to permit repointing of the spacecraft and to obtain LAT observations of delayed emission from bursts. GBM and LAT refined locations are rapidly disseminated to the scientific community, often permitting extensive multiwavelength follow-up observations by NASA's Swift mission or other space- based observatories, and by numerous ground-based telescopes, thus allowing redshift determinations. Calculations of LAT upper limits are mainly based

  14. High-energy emission from bright gamma-ray bursts using Fermi

    Energy Technology Data Exchange (ETDEWEB)

    Bissaldi, Elisabetta

    2010-05-25

    Among the scientific objectives of one of the present NASA missions, the Fermi Gamma-ray Space Telescope (FGST), is the study of gamma-ray bursts (GRBs). Fermi's payload comprises two science instruments, the Large Area Telescope (LAT) and the Gamma-Ray Burst Monitor (GBM). GBM was designed to detect and localize bursts for the Fermi mission. By means of an array of 12 NaI(Tl) (8 keV to 1 MeV) and two BGO (0.2 to 40 MeV) scintillation detectors, GBM extends the energy range (20 MeV to > 300 GeV) of the LAT instrument into the traditional range of current GRB databases. The physical detector response of the GBM instrument to GRBs has been determined with the help of Monte Carlo simulations, which are supported and verified by on-ground individual detector calibration measurements. The GBM detectors have been calibrated from 10 keV to 17.5 MeV using various gamma sources, and the detector response has been derived by simulations over the entire energy range (8 keV to 40 MeV) using GEANT. The GBM instrument has been operating successfully in orbit since June 11, 2008. The total trigger count from the time GBM triggering was enabled in July 2008 through December 2009 is 655, and about 380 of these triggers were classified as GRBs. Moreover, GBM detected several bursts in common with the LAT. These amazing detections mainly fulfill the primary science goal of GBM, which is the joint analysis of spectra and time histories of GRBs observed by both Fermi instruments. For every trigger, GBM provides near-real time on-board burst locations to permit repointing of the spacecraft and to obtain LAT observations of delayed emission from bursts. GBM and LAT refined locations are rapidly disseminated to the scientific community, often permitting extensive multiwavelength follow-up observations by NASA's Swift mission or other space- based observatories, and by numerous ground-based telescopes, thus allowing redshift determinations. Calculations of LAT upper limits are

  15. Variability in fluence and spectrum of high-energy photon bursts produced by lightning leaders

    Science.gov (United States)

    Celestin, Sebastien; Xu, Wei; Pasko, Victor P.

    2015-12-01

    In this paper, we model the production and acceleration of thermal runaway electrons during negative corona flash stages of stepping lightning leaders and the corresponding terrestrial gamma ray flashes (TGFs) or negative cloud-to-ground (-CG) lightning-produced X-ray bursts in a unified fashion. We show how the source photon spectrum and fluence depend on the potential drop formed in the lightning leader tip region during corona flash and how the X-ray burst spectrum progressively converges toward typical TGF spectrum as the potential drop increases. Additionally, we show that the number of streamers produced in a negative corona flash, the source electron energy distribution function, the corresponding number of photons, and the photon energy distribution and transport through the atmosphere up to low-orbit satellite altitudes exhibit a very strong dependence on this potential drop. This leads to a threshold effect causing X-rays produced by leaders with potentials lower than those producing typical TGFs extremely unlikely to be detected by low-orbit satellites. Moreover, from the number of photons in X-ray bursts produced by -CGs estimated from ground observations, we show that the proportionality between the number of thermal runaway electrons and the square of the potential drop in the leader tip region during negative corona flash proposed earlier leads to typical photon fluences on the order of 1 ph/cm2 at an altitude of 500 km and a radial distance of 200 km for intracloud lightning discharges producing 300 MV potential drops, which is consistent with observations of TGF fluences and spectra from satellites.

  16. Actively produced high-energy electron bursts within the magnetosphere: the APEX project

    Directory of Open Access Journals (Sweden)

    L. Přech

    Full Text Available The APEX project (Active Plasma Experiment has been launched into a polar orbit in December 1991 and consists of two satellites (IK-25 and MAGION-3, with a distance between them from 200 km to 10 000 km. The mission used intensive electron beam emission, complemented by a low-energy Xenon plasma generator during the electron beam injection, for the study of dynamic processes in the magnetosphere and upper ionosphere. 

    The paper deals with short, intensive bursts of field-aligned electrons observed during the APEX mission on board the MAGION-3 satellite. These events are located pre-dominantly at the middle geomagnetic latitudes in the day-side magnetosphere. The time-energy structure of these electron bursts is similar to the inverted-V one, but the pitch-angle width is less than 10°. Electrons with an energy up to 700 keV are often observed during the events. We analyze the observed events, discuss the possible mechanisms of the particle spreading, and the role of the main satellite’s activity as a possible source of these events.

    Key words. Ionosphere (particle acceleration; particle precipitation – Space plasma physics (active perturbation experiments

  17. On The Origin Of High Energy Correlations in Gamma-ray Bursts

    Energy Technology Data Exchange (ETDEWEB)

    Kocevski, Daniel

    2012-04-03

    I investigate the origin of the observed correlation between a gamma-ray burst's {nu}F{sub {nu}} spectral peak E{sub pk} and its isotropic equivalent energy E{sub iso} through the use of a population synthesis code to model the prompt gamma-ray emission from GRBs. By using prescriptions for the distribution of prompt spectral parameters as well as the population's luminosity function and co-moving rate density, I generate a simulated population of GRBs and examine how bursts of varying spectral properties and redshift would appear to a gamma-ray detector here on Earth. I find that a strong observed correlation can be produced between the source frame Epk and Eiso for the detected population despite the existence of only a weak and broad correlation in the original simulated population. The energy dependance of a gamma-ray detector's flux-limited detection threshold acts to produce a correlation between the source frame E{sub pk} and E{sub iso} for low luminosity GRBs, producing the left boundary of the observed correlation. Conversely, very luminous GRBs are found at higher redshifts than their low luminosity counterparts due to the standard Malquest bias, causing bursts in the low E{sub pk}, high E{sub iso} regime to go undetected because their E{sub pk} values would be redshifted to energies at which most gamma-ray detectors become less sensitive. I argue that it is this previously unexamined effect which produces the right boundary of the observed correlation. Therefore, the origin of the observed correlation is a complex combination of the instrument's detection threshold, the intrinsic cutoff in the GRB luminosity function, and the broad range of redshifts over which GRBs are detected. Although the GRB model presented here is a very simplified representation of the complex nature of GRBs, these simulations serve to demonstrate how selection effects caused by a combination of instrumental sensitivity and the cosmological nature of an

  18. Ultra-high-energy neutrinos and cosmic rays from gamma-ray bursts. Exploring and updating the connection

    International Nuclear Information System (INIS)

    It is natural to consider the possibility that the most energetic particles detected (>1018 eV), ultra-high-energy cosmic rays (UHECRs), are originated at the most luminous transient events observed (>1052 erg s-1), gamma-ray bursts (GRBs). As a result of the interaction of highly-accelerated, magnetically-confined protons and ions with the photon field inside the burst, both neutrons and UHE neutrinos are expected to be created: the former escape the source and beta-decay into protons which propagate to Earth, where they are detected as UHECRs, while the latter, if detected, would constitute the smoking gun of hadronic acceleration in the sources. Recently, km-scale neutrino telescopes such as IceCube have finally reached the sensitivities required to probe the neutrino predictions of some of the existing GRB models. On that account, we present here a revised, self-consistent model of joint UHE proton and neutrino production at GRBs that includes a state-of-the-art, improved numerical calculation of the neutrino flux (NeuCosmA); that uses a generalised UHECR emission model where some of the protons in the sources are able to ''leak out'' of their magnetic confinement before having interacted; and that takes into account the energy losses of the protons during their propagation to Earth. We use our predictions to take a close look at the cosmic ray-neutrino connection and find that the current UHECR observations by giant air shower detectors, together with the upper bounds on the flux of neutrinos from GRBs, are already sufficient to put tension on several possibilities of particle emission and propagation, and to point us towards some requirements that should be fulfilled by GRBs if they are to be the sources of the UHECRs. We further refine our analysis by studying a dynamical burst model, where we find that the different particle species originate at distinct stages of the expanding GRB, each under particular conditions. Finally, we consider

  19. Ultra High-Energy Cosmic Ray Production by Turbulence in Gamma-Ray Burst Jets and Cosmogenic Neutrinos

    CERN Document Server

    Asano, Katsuaki

    2016-01-01

    We propose a novel model to produce ultra-high-energy cosmic-rays (UHECRs) in gamma-ray burst (GRB) jets. After the prompt gamma-ray emission, hydrodynamical turbulence is excited in the GRB jets at or before the afterglow phase. The mildly relativistic turbulence stochastically accelerates protons. The acceleration rate is much slower than the usual first-order shock acceleration rate, but in this case it can be energy-independent. The resultant UHECR spectrum is so hard that the bulk energy is concentrated in the highest energy range, resulting in a moderate requirement for the typical cosmic ray luminosity of $\\sim 10^{53.5}~\\mbox{erg}~\\mbox{s}^{-1}$. In this model, the secondary gamma-ray and neutrino emissions initiated by photopion production are significantly suppressed. Although the UHECR spectrum at injection shows a curved feature, this does not conflict with the observed UHECR spectral shape. The cosmogenic neutrino spectrum in the $10^{17}$--$10^{18}$ eV range becomes distinctively hard in this mo...

  20. Possible High-Energy Neutrino and Photon Signals from Gravitational Wave Bursts due to Double Neutron Star Mergers

    CERN Document Server

    Gao, He; Wu, Xue-Feng; Dai, Zi-Gao

    2013-01-01

    As the technology of gravitational-wave and neutrino detectors becomes increasingly mature, a multi-messenger era of astronomy is ushered in. Advanced gravitational wave detectors are close to making a ground-breaking discovery of gravitational wave bursts (GWBs) associated with mergers of double neutron stars (NS-NS). It is essential to study the possible electromagnetic (EM) and neutrino emission counterparts of these GWBs. Recent observations and numerical simulations suggest that at least a fraction of NS-NS mergers may leave behind a massive millisecond magnetar as the merger product. Here we show that protons accelerated in the forward shock powered by a magnetar wind pushing the ejecta launched during the merger process would interact with photons generated in the dissipating magnetar wind and emit high energy neutrinos and photons. We estimate the typical energy and fluence of the neutrinos from such a scenario. We find that $\\sim$PeV neutrinos could be emitted from the shock front as long as the ejec...

  1. Model-dependent estimate on the connection between fast radio bursts and ultra high energy cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiang; Zhou, Bei; He, Hao-Ning; Fan, Yi-Zhong; Wei, Da-Ming, E-mail: yzfan@pmo.ac.cn [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Science, Nanjing 210008 (China)

    2014-12-10

    The existence of fast radio bursts (FRBs), a new type of extragalatic transient, has recently been established, and quite a few models have been proposed. In this work, we discuss the possible connection between the FRB sources and ultra high energy (>10{sup 18} eV) cosmic rays. We show that in the blitzar model and the model of merging binary neutron stars, which includes the huge energy release of each FRB central engine together with the rather high rate of FRBs, the accelerated EeV cosmic rays may contribute significantly to the observed ones. In other FRB models, including, for example, the merger of double white dwarfs and the energetic magnetar radio flares, no significant EeV cosmic ray is expected. We also suggest that the mergers of double neutron stars, even if they are irrelevant to FRBs, may play a nonignorable role in producing EeV cosmic ray protons if supramassive neutron stars are formed in a sufficient fraction of mergers and the merger rate is ≳ 10{sup 3} yr{sup –1} Gpc{sup –3}. Such a possibility will be unambiguously tested in the era of gravitational wave astronomy.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-09-01

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

  3. Upper limits on the high-energy emission from gamma-ray bursts observed by AGILE-GRID

    Science.gov (United States)

    Longo, F.; Moretti, E.; Nava, L.; Desiante, R.; Olivo, M.; Del Monte, E.; Rappoldi, A.; Fuschino, F.; Marisaldi, M.; Giuliani, A.; Cutini, S.; Feroci, M.; Costa, E.; Pittori, C.; Tavani, M.; Argan, A.; Barbiellini, G.; Bulgarelli, A.; Caraveo, P.; Cardillo, M.; Cattaneo, P. W.; Chen, A. W.; D'Ammando, F.; Di Cocco, G.; Donnarumma, I.; Evangelista, Y.; Ferrari, A.; Fiorini, M.; Galli, M.; Gianotti, F.; Giusti, M.; Labanti, C.; Lapshov, I.; Lazzarotto, F.; Lipari, P.; Mereghetti, S.; Morselli, A.; Pacciani, L.; Pellizzoni, A.; Perotti, F.; Piano, G.; Picozza, P.; Pilia, M.; Prest, M.; Pucella, G.; Rapisarda, M.; Rubini, A.; Sabatini, S.; Soffitta, P.; Striani, E.; Trifoglio, M.; Trois, A.; Vallazza, E.; Vercellone, S.; Vittorini, V.; Zanello, D.; Antonelli, L. A.; Colafrancesco, S.; Giommi, P.; Santolamazza, P.; Verrecchia, F.; Lucarelli, F.; Salotti, L.

    2012-11-01

    Context. The detection and the characterization of the highenergy emission component from individual gamma-ray bursts (GRBs) is one of the key science objectives of the currently operating gamma-ray satellite AGILE, launched in April 2007. In its first two years of operation AGILE detected three GRBs with photons of energy larger than 30 MeV. One more GRB was detected in AGILE third operation year, while operating in spinning mode. Aims: For the 64 other GRBs localized during the period July 2007 to October 2009 in the field of view of the AGILE Gamma-Ray Imaging Detector (GRID), but not detected by this instrument, we estimate the count and flux upper limits on the GRB high energy emission in the AGILE-GRID energy band (30 MeV-3 GeV). Methods: To calculate the count upper limits, we adopted a Bayesian approach. The flux upper limits are derived using several assumptions on the high-energy spectral behavior. For 28 GRBs with available prompt spectral information, a flux upper limit and the comparison with the expected flux estimated from spectral extrapolation of the Band spectrum to the 30 MeV-3 GeV band are provided. Moreover, upper limits on the flux under the assumption of an extra power law component dominating the 30 MeV-3 GeV band are calculated for all GRBs and considering four different values for the spectral photon index. Finally, we performed a likelihood upper limit on the possible delayed emission up to 1 h after the GRB. Results: The estimated flux upper limits range between 1 × 10-4 and ~2 × 10-2 photons cm-2 s-1 and generally lie above the flux estimated from the extrapolation of the prompt emission in the 30 MeV-3 GeV band. A notable case is GRB 080721, where the AGILE-GRID upper limit suggests a steeper spectral index or the presence of a cut-off in the high energy part of the Band prompt spectrum. The four GRBs detected by AGILE-GRID show high-energy (30 MeV-3 GeV) to low-energy (1 keV-10 MeV) fluence ratios similar to those estimated in this

  4. Detection, localization and study of spectral properties of high energy gamma bursts observed in the Fermi experiment

    International Nuclear Information System (INIS)

    Gamma-Ray Bursts (GRB) are among the brightest gamma-ray sources in the sky. The current standard framework associates their prompt gamma-ray emission to charged particles accelerated in relativistic jets issued by newly-formed stellar-mass black holes. The radio to X-ray afterglow emission is due to the interaction between these jets and the interstellar medium. The LAT, pair-creation instrument onboard Fermi gamma-ray space telescope, performs unprecedented observation of the gamma-ray sky at energies of 20 MeV to over 300 GeV since its launch in june 2008. Fermi's transient sources detector (GBM) observed prompt emissions of about 450 GRB between 8 keV and 40 MeV. 18 of these GRB were also studied up to GeV energies with the LAT. Accurate GRB localizations and Fermi's synergy with other observatories allows the study of GRB afterglows, and therefore a better interpretation of these observations. The analyses of GRB emissions between 8 keV to GeV energies is presented here. Localizations based on LAT data and their biases are studied. Spectral analyses of combined GBM and LAT data are shown, and their theoretical interpretations explained. An alternative analysis based on a relaxed selection of LAT data is presented and fully characterized. It allows to recover and use low-energy LAT statistics in temporal and spectral analyses of GRB prompt emission. Searches for long-lived high-energy emission from GRB are presented. The analysis of GRB 090510 afterglow emission from eV to GeV energies is described. Finally, Fermi bright GRB prompt emissions are compared to an internal shock model developed at IAP. (author)

  5. High energy emission of GRB 130821A: constraining the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow

    CERN Document Server

    Liang, Yun-Feng; He, Hao-Ning; Tam, Pak-Hin Thomas; Fan, Yi-Zhong; Wei, Da-Ming

    2013-01-01

    GRB 130821A was detected by Fermi-GBM/LAT, Konus-Wind, SPI-ACS/INTEGRAL, RHESSI and Mars Odyssey-HEND. Although the data of GRB 130821A are very limited, we show in this work that the high energy gamma-ray emission (i.e., above 100 MeV) alone imposes tight constraint on the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow. The temporal behavior of the high energy gamma-ray emission is consistent with the forward shock synchrotron radiation model and the circum-burst medium likely has a constant-density profile. The Lorentz factor is about a few hundred, similar to other bright GRBs.

  6. High energy emission of GRB 130821A: Constraining the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Yun-Feng; Zhou, Bei; He, Hao-Ning; Fan, Yi-Zhong; Wei, Da-Ming [Key laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Tam, Pak-Hin Thomas, E-mail: phtam@phys.nthu.edu.tw [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2014-02-01

    GRB 130821A was detected by Fermi-GBM/LAT, Konus-WIND, SPI-ACS/INTEGRAL, RHESSI and Mars Odyssey-HEND. Although the data of GRB 130821A are very limited, we show in this work that the high energy γ-ray emission (i.e., above 100 MeV) alone imposes tight constraint on the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow. The temporal behavior of the high energy γ-ray emission is consistent with the forward shock synchrotron radiation model, and the circum-burst medium likely has a constant-density profile. The Lorentz factor is about a few hundred, similar to other bright GRBs.

  7. A burst in a wind bubble and the impact on baryonic ejecta: high-energy gamma-ray flashes and afterglows from fast radio bursts and pulsar-driven supernova remnants

    Science.gov (United States)

    Murase, Kohta; Kashiyama, Kazumi; Mészáros, Peter

    2016-06-01

    Tenuous wind bubbles, which are formed by the spin-down activity of central compact remnants, are relevant in some models of fast radio bursts (FRBs) and super-luminous supernovae. We study their high-energy signatures, focusing on the role of pair-enriched bubbles produced by young magnetars, rapidly-rotating neutron stars, and magnetized white dwarfs. (i) First, we study the nebular properties and the conditions allowing for escape of high-energy gamma-rays and radio waves, showing that their escape is possible for nebulae with ages of ≳ 10 - 100 yr. In the rapidly-rotating neutron star scenario, we find that radio emission from the quasi-steady nebula itself may be bright enough to be detected especially at sub-mm frequencies, which is relevant as a possible counterpart of pulsar-driven SNe and FRBs. (ii) Second, we consider the fate of bursting emission in the nebulae. We suggest that an impulsive burst may lead to a highly relativistic flow, which would interact with the nebula. If the shocked nebula is still relativistic, pre-existing non-thermal particles in the nebula can be significantly boosted by the forward shock, leading to short-duration (maybe millisecond or longer) high-energy gamma-ray flashes. Possible dissipation at the reverse shock may also lead to gamma-ray emission. (iii) After such flares, interactions with the baryonic ejecta may lead to afterglow emission with a duration of days to weeks. In the magnetar scenario, this burst-in-bubble model leads to the expectation that nearby (˜10 - 100 Mpc) high-energy gamma-ray flashes may be detected by the High-Altitude Water Cherenkov Observatory and the Cherenkov Telescope Array, and the subsequent afterglow emission may be seen by radio telescopes such as the Very Large Array. (iv) Finally, we discuss several implications specific to FRBs, including constraints on the emission regions and limits on soft gamma-ray counterparts.

  8. New Fermi-LAT event reconstruction reveals more high-energy gamma rays from Gamma-ray bursts

    CERN Document Server

    Atwood, W B; Bregeon, J; Bruel, P; Chekhtman, A; Cohen-Tanugi, J; Drlica-Wagner, A; Granot, J; Longo, F; Omodei, N; Pesce-Rollins, M; Razzaque, S; Rochester, L S; Sgro, C; Tinivella, M; Usher, T L; Zimmer, S

    2013-01-01

    Based on the experience gained during the four and a half years of the mission, the Fermi -LAT collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet finalized, we can test the improvements in the new event reconstruction with the special case of the prompt phase of bright Gamma-Ray Bursts (GRBs), where the signal to noise ratio is large enough that loose selection cuts are sufficient to identify gamma- rays associated with the source. Using the new event reconstruction, we have re-analyzed ten GRBs previously detected by the LAT for which an x-ray/optical follow-up was possible and found four new gamma rays with energies greater than 10 GeV in addition to the seven previously known. Among these four is a 27.4 GeV gamma-ray from GRB 080916C, which has a redshift of 4.35, thus making it the gamma ray with the highest intrinsic energy (147 GeV) detected from a GRB. We present here the salient aspects of the new event reconstructio...

  9. On Gamma Ray Burst and Blazar AGN Origins of the Ultra-High Energy Cosmic Rays in Light of First Results from Auger

    CERN Document Server

    Dermer, Charles D

    2007-01-01

    The discoveries of the GZK cutoff with the HiRes and Auger Observatories and the discovery by Auger of clustering of >~60 EeV ultra-high energy cosmic rays (UHECRs) towards nearby <~75 Mpc) AGNs along the supergalactic plane establishes the astrophysical origin of the UHECRs. The likely sources of the UHECRs are gamma-ray bursts and radio-loud AGNs because: (1) they are extragalactic; (2) they are sufficiently powerful; (3) acceleration to ultra-high energies can be achieved in their relativistic ejecta; (4) anomalous X-ray and $\\gamma$-ray features can be explained by nonthermal hadron acceleration in relativistic blast waves; and (5) sources reside within the GZK radius. Two arguments for acceleration to UHE are presented, and limits on UHECR ion acceleration are set. UHECR ions are shown to be able to survive without photodisintegrating while passing through the AGN scattered radiation field, even if launched deep in the broad line region. UHECR injection throughout cosmic time fits the measured energy ...

  10. Observational Signatures of High-Energy Emission during the Shallow Decay Phase of Gamma-Ray Burst X-Ray Afterglows

    Science.gov (United States)

    Yu, Y. W.; Liu, X. W.; Dai, Z. G.

    2007-12-01

    The widely existing shallow decay phase of the X-ray afterglows of gamma-ray bursts (GRBs) is generally accepted to be due to long-lasting energy injection. The outflows carrying the injecting energy, based on the component that is dominant in energy, fall into two possible types: baryon-dominated and lepton-dominated ones. The former type of outflow could be ejecta that is ejected during the prompt phase of a GRB and consists of a series of baryonic shells with a distribution of Lorentz factors, and the latter type could be an electron-positron pair wind that is driven by the postburst central engine. We here provide a unified description for the dynamics of fireballs based on these two types of energy injection and calculate the corresponding high-energy photon emission by considering synchrotron radiation and inverse Compton scattering (including synchrotron self-Compton and combined inverse Compton) of electrons. We find that, in the two energy-injection models, there is a plateau (even a hump) in high-energy light curves during the X-ray shallow decay phase. In particular, a considerable fraction of the injecting energy in the lepton-dominated model can be shared by the long-lasting reverse shock since it is relativistic. Furthermore, almost all of the energy of the reverse shock is carried by leptons, and thus, the inverse Compton emission is enhanced dramatically. Therefore, this model predicts more significant high-energy afterglow emission than the baryon-dominated model. We argue that these observational signatures would be used to discriminate between different energy-injection models in the upcoming Gamma-Ray Large Area Space Telescope (GLAST) era.

  11. A burst in a wind bubble and the impact on external matter: high-energy gamma-ray flares and implications for fast radio bursts and pulsar-driven supernovae

    CERN Document Server

    Murase, Kohta; Meszaros, Peter

    2016-01-01

    Tenuous wind bubble, which are formed by spin-down activities of central compact remnants, are relevant in some models of fast radio bursts (FRBs) and super-luminous supernovae. In this work, we study the role of such pair-enriched bubbles produced by young magnetars, rapidly-rotating neutron stars, and magnetized white dwarfs. We calculate the nebular emission and the conditions allowing for escape of high-energy gamma-rays and radio waves, showing that their escape is possible for nebulae with ages of >10-100 yr. In the rapidly-rotating neutron star scenario, we find that radio emission from the quasi-steady nebula itself may be bright enough to be detected especially at submm frequencies, which is relevant as a possible counterpart of pulsar-driven SNe and FRBs. An impulsive burst may lead to a highly relativistic flow, which would interact with the nebula. If the shocked nebula is still relativistic, pre-existing non-thermal particles in the unshocked nebula can be significantly boosted by the forward sho...

  12. Timescale Analysis of Spectral Lags

    Institute of Scientific and Technical Information of China (English)

    Ti-Pei Li; Jin-Lu Qu; Hua Feng; Li-Ming Song; Guo-Qiang Ding; Li Chen

    2004-01-01

    A technique for timescale analysis of spectral lags performed directly in the time domain is developed. Simulation studies are made to compare the time domain technique with the Fourier frequency analysis for spectral time lags. The time domain technique is applied to studying rapid variabilities of X-ray binaries and γ-ray bursts. The results indicate that in comparison with the Fourier analysis the timescale analysis technique is more powerful for the study of spectral lags in rapid variabilities on short time scales and short duration flaring phenomena.

  13. High-energy square pulses and burst-mode pulses in an all-normal dispersion double-clad mode-locked fiber laser

    Science.gov (United States)

    Qiao, Zhi; Wang, Xiaochao; Wang, Chao; Jing, Yuanyuan; Fan, Wei; Lin, Zunqi

    2016-05-01

    A double-clad Yb-doped mode-locked fiber laser that can operate in burst-mode and square-pulse states is experimentally investigated. In the burst-mode state, a burst train with 55 pulses of 500 ps duration is obtained. In the square-pulse state, which is similar to noiselike pulses, the maximum pulse energy is 820 nJ and the duration can be tuned from 15.8 to 546 ns. The square pulses have a narrow and multipeak spectrum, which is quite different from that of normal noiselike pulses. The fiber laser promises an alternative formation mechanism for burst-mode and square-pulse mode-locked fiber lasers.

  14. Detection, localization and study of spectral properties of high energy gamma bursts observed in the Fermi experiment; Detection, localisation et etude des proprietes spectrales de sursauts gamma observes a haute energie avec l'experience Fermi

    Energy Technology Data Exchange (ETDEWEB)

    Pelassa, V.

    2010-12-13

    Gamma-Ray Bursts (GRB) are among the brightest gamma-ray sources in the sky. The current standard framework associates their prompt gamma-ray emission to charged particles accelerated in relativistic jets issued by newly-formed stellar-mass black holes. The radio to X-ray afterglow emission is due to the interaction between these jets and the interstellar medium. The LAT, pair-creation instrument onboard Fermi gamma-ray space telescope, performs unprecedented observation of the gamma-ray sky at energies of 20 MeV to over 300 GeV since its launch in june 2008. Fermi's transient sources detector (GBM) observed prompt emissions of about 450 GRB between 8 keV and 40 MeV. 18 of these GRB were also studied up to GeV energies with the LAT. Accurate GRB localizations and Fermi's synergy with other observatories allows the study of GRB afterglows, and therefore a better interpretation of these observations. The analyses of GRB emissions between 8 keV to GeV energies is presented here. Localizations based on LAT data and their biases are studied. Spectral analyses of combined GBM and LAT data are shown, and their theoretical interpretations explained. An alternative analysis based on a relaxed selection of LAT data is presented and fully characterized. It allows to recover and use low-energy LAT statistics in temporal and spectral analyses of GRB prompt emission. Searches for long-lived high-energy emission from GRB are presented. The analysis of GRB 090510 afterglow emission from eV to GeV energies is described. Finally, Fermi bright GRB prompt emissions are compared to an internal shock model developed at IAP. (author)

  15. GLAST's GBM Burst Trigger

    Science.gov (United States)

    Band, D.; Briggs, M.; Connaughton, V.; Kippen, M.; Preece, R.

    2003-01-01

    The GLAST Burst Monitor (GBM) will detect and localize bursts for the GLAST mission, and provide the spectral and temporal context in the traditional 10 keV to 25 MeV band for the high energy observations by the Large Area Telescope (LAT). The GBM will use traditional rate triggers in up to three energy bands, and on a variety of timescales between 16 ms and 16 s.

  16. High Energy Density Laboratory Astrophysics

    CERN Document Server

    Lebedev, Sergey V

    2007-01-01

    During the past decade, research teams around the world have developed astrophysics-relevant research utilizing high energy-density facilities such as intense lasers and z-pinches. Every two years, at the International conference on High Energy Density Laboratory Astrophysics, scientists interested in this emerging field discuss the progress in topics covering: - Stellar evolution, stellar envelopes, opacities, radiation transport - Planetary Interiors, high-pressure EOS, dense plasma atomic physics - Supernovae, gamma-ray bursts, exploding systems, strong shocks, turbulent mixing - Supernova remnants, shock processing, radiative shocks - Astrophysical jets, high-Mach-number flows, magnetized radiative jets, magnetic reconnection - Compact object accretion disks, x-ray photoionized plasmas - Ultrastrong fields, particle acceleration, collisionless shocks. These proceedings cover many of the invited and contributed papers presented at the 6th International Conference on High Energy Density Laboratory Astrophys...

  17. High-Energy Astrophysics: An Overview

    Science.gov (United States)

    Fishman, Gerald J.

    2007-01-01

    High-energy astrophysics is the study of objects and phenomena in space with energy densities much greater than that found in normal stars and galaxies. These include black holes, neutron stars, cosmic rays, hypernovae and gamma-ray bursts. A history and an overview of high-energy astrophysics will be presented, including a description of the objects that are observed. Observing techniques, space-borne missions in high-energy astrophysics and some recent discoveries will also be described. Several entirely new types of astronomy are being employed in high-energy astrophysics. These will be briefly described, along with some NASA missions currently under development.

  18. Spectral Lags Obtained by CCF of Smoothed Lightcurves

    CERN Document Server

    Li, Zhao-sheng; Wang, De-hua

    2012-01-01

    We present a new technique to calculate the spectral lags of gamma-ray bursts (GRBs). Unlike previous processing methods, we first smooth the light curves of gamma-ray bursts in high and low energy bands using the "Loess" filter, then, we directly define the spectral lags as such to maximize the cross-correlation function (CCF) between two smoothed light curves. This method is suitable for various shapes of CCF; it effectively avoids the errors caused by manual selections for the fitting function and fitting interval. Using the method, we have carefully measured the spectral lags of individual pulses contained in BAT/Swift gamma-ray bursts with known redshifts, and confirmed the anti-correlation between the spectral lag and the isotropy luminosity. The distribution of spectral lags can be well fitted by four Gaussian components, with the centroids at 0.03 s, 0.09 s, 0.15 s, and 0.21 s, respectively. We find that some spectral lags of the multi-peak GRBs seem to evolve with time.

  19. Spectral lag features of GRB 060814 from swift bat and Suzaku observations

    International Nuclear Information System (INIS)

    This work reports a study on the spectral lag of the prompt emission spectrum of a multi-pulse gamma-ray burst (GRB) GRB 060814 (z = 0.84) using the observations of the Swift Burst Alert Telescope and the Suzaku Wide Area Monitor. We found that the spectral lag for GRB 060814 is positive for the first two and the fourth pulses, while the third pulse exhibits negative lag. However, the time variation of the E peak of all the stated pulses shows a similar trend. The leading models for spectral lags in GRBs are thus found inadequate to explain the observed spectral lag features of GRB 060814. Probable causes of the spectral lag characteristics of GRB 060814 are discussed.

  20. High energy astrophysics. An introduction

    International Nuclear Information System (INIS)

    Based on observational examples this book reveals and explains high-energy astrophysical processes. Presents the theory of astrophysical processes in a didactic approach by deriving equations step by step. With several attractive astronomical pictures. High-energy astrophysics has unveiled a Universe very different from that only known from optical observations. It has revealed many types of objects in which typical variability timescales are as short as years, months, days, and hours (in quasars, X-ray binaries, and other objects), and even down to milli-seconds in gamma ray bursts. The sources of energy that are encountered are only very seldom nuclear fusion, and most of the time gravitation, a paradox when one thinks that gravitation is, by many orders of magnitude, the weakest of the fundamental interactions. The understanding of these objects' physical conditions and the processes revealed by high-energy astrophysics in the last decades is nowadays part of astrophysicists' culture, even of those active in other domains of astronomy. This book evolved from lectures given to master and PhD students at the University of Geneva since the early 1990s. It aims at providing astronomers and physicists intending to be active in high-energy astrophysics a broad basis on which they should be able to build the more specific knowledge they will need. While in the first part of the book the physical processes are described and derived in detail, the second part studies astrophysical objects in which high-energy astrophysics plays a crucial role. This two-pronged approach will help students recognise physical processes by their observational signatures in contexts that may differ widely from those presented here.

  1. High energy astrophysics. An introduction

    Energy Technology Data Exchange (ETDEWEB)

    Courvoisier, Thierry J.L. [Geneva Univ., Versoix (Switzerland). ISDC, Data Centre for Astrophysics

    2013-07-01

    Based on observational examples this book reveals and explains high-energy astrophysical processes. Presents the theory of astrophysical processes in a didactic approach by deriving equations step by step. With several attractive astronomical pictures. High-energy astrophysics has unveiled a Universe very different from that only known from optical observations. It has revealed many types of objects in which typical variability timescales are as short as years, months, days, and hours (in quasars, X-ray binaries, and other objects), and even down to milli-seconds in gamma ray bursts. The sources of energy that are encountered are only very seldom nuclear fusion, and most of the time gravitation, a paradox when one thinks that gravitation is, by many orders of magnitude, the weakest of the fundamental interactions. The understanding of these objects' physical conditions and the processes revealed by high-energy astrophysics in the last decades is nowadays part of astrophysicists' culture, even of those active in other domains of astronomy. This book evolved from lectures given to master and PhD students at the University of Geneva since the early 1990s. It aims at providing astronomers and physicists intending to be active in high-energy astrophysics a broad basis on which they should be able to build the more specific knowledge they will need. While in the first part of the book the physical processes are described and derived in detail, the second part studies astrophysical objects in which high-energy astrophysics plays a crucial role. This two-pronged approach will help students recognise physical processes by their observational signatures in contexts that may differ widely from those presented here.

  2. High energy astrophysics an introduction

    CERN Document Server

    Courvoisier, Thierry J -L

    2013-01-01

    High-energy astrophysics has unveiled a Universe very different from that only known from optical observations. It has revealed many types of objects in which typical variability timescales are as short as years, months, days, and hours (in quasars, X-ray binaries, and other objects), and even down to milli-seconds in gamma ray bursts. The sources of energy that are encountered are only very seldom nuclear fusion, and most of the time gravitation, a paradox when one thinks that gravitation is, by many orders of magnitude, the weakest of the fundamental interactions. The understanding of these objects' physical conditions and the processes revealed by high-energy astrophysics in the last decades is nowadays part of astrophysicists' culture, even of those active in other domains of astronomy. This book evolved from lectures given to master and PhD students at the University of Geneva since the early 1990s. It aims at providing astronomers and physicists intending to be active in high-energy astrophysics a broad...

  3. Possibility of observing high energy neutrinos from gamma bursts, with the Antanares telescope, feasibility study; Possibilite d'observation, par le telescope antares, de neutrinos de haute energie associes aux sursauts gamma et validation des techniques de detection a l'aide d'un prototype

    Energy Technology Data Exchange (ETDEWEB)

    Kouchner, A

    2001-04-01

    The European Antares collaboration intends to build a deep-sea neutrino telescope with a detection surface of about 1/10 km{sup 2} in the Mediterranean sea. The universe is transparent to neutrinos, so their study provides a unique means of improving our knowledge of the nature and origin of cosmic rays and their emission from the most powerful astrophysical sources in the cosmos. Neutrinos also offer the possibility of opening a new energy window (E>TeV) for observation of the universe. The first part of the thesis is dedicated to a study of the possibility of using the future telescope to look for correlations between gamma-ray bursts and high-energy neutrinos. It is based, on one hand, on the predictions of neutrino fluxes from gamma-ray bursts in the framework of the theoretical model of 'fireballs', and, on the other hand, on the temporal properties of the gamma-ray bursts in the 4. BATSE catalogue. The second part of the thesis presents the results obtained with a prototype detector line deployed, at the end of 1999, some forty km south-west off Marseilles. The objective was to operate a complete apparatus, similar to the future detector lines, from the shore, and under realistic conditions. Data from 7 photomultiplier tubes disposed along the detector line were transmitted through 37 km of optical fiber to the shore, where they were used to reconstruct tracks due to atmospheric muons, thus validating the detection principles and methods. (author)

  4. Lagged correlation networks

    Science.gov (United States)

    Curme, Chester

    Technological advances have provided scientists with large high-dimensional datasets that describe the behaviors of complex systems: from the statistics of energy levels in complex quantum systems, to the time-dependent transcription of genes, to price fluctuations among assets in a financial market. In this environment, where it may be difficult to infer the joint distribution of the data, network science has flourished as a way to gain insight into the structure and organization of such systems by focusing on pairwise interactions. This work focuses on a particular setting, in which a system is described by multivariate time series data. We consider time-lagged correlations among elements in this system, in such a way that the measured interactions among elements are asymmetric. Finally, we allow these interactions to be characteristically weak, so that statistical uncertainties may be important to consider when inferring the structure of the system. We introduce a methodology for constructing statistically validated networks to describe such a system, extend the methodology to accommodate interactions with a periodic component, and show how consideration of bipartite community structures in these networks can aid in the construction of robust statistical models. An example of such a system is a financial market, in which high frequency returns data may be used to describe contagion, or the spreading of shocks in price among assets. These data provide the experimental testing ground for our methodology. We study NYSE data from both the present day and one decade ago, examine the time scales over which the validated lagged correlation networks exist, and relate differences in the topological properties of the networks to an increasing economic efficiency. We uncover daily periodicities in the validated interactions, and relate our findings to explanations of the Epps Effect, an empirical phenomenon of financial time series. We also study bipartite community

  5. The early high-energy afterglow emission from short GRBs

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We calculate the high energy afterglow emission from short Gamma-Ray Bursts(SGRBs) in the external shock model.There are two possible components contributing to the high energy afterglow:electron synchrotron emission and synchrotron self-Compton(SSC) emission.We find that for typical parameter values of SGRBs,the early high-energy afterglow emission in 10 MeV-10 GeV is dominated by synchrotron emission.For a burst occurring at redshift z = 0.1,the high-energy emission can be detectable by Fermi LAT if the blast wave has energy E ≥ 1051 ergs and the fraction of electron energy εe≥ 0.1.This provides a possible explanation for the high energy tail of SGRB 081024B.

  6. Gamma bursts

    International Nuclear Information System (INIS)

    The Vela satellite series has recently detected gamma bursts in the 0.2-1.5MeV energy range. These bursts last an average of from 0.1 to 10s and have a fine time structure, with pulses lasting less than several tens of milliseconds. With simultaneous observations from different satellites it has been possible to determine the spatial origin of some of the bursts. No correlation, however, has been made with known objects. In spite of the fragmentary character of the information received to date, several theories have already been proposed to account for these phenomena

  7. The high energy galaxy

    International Nuclear Information System (INIS)

    The galaxy is host to a wide variety of high energy events. I review here recent results on large scale galactic phenomena: cosmic-ray origin and confinement, the connexion to ultra high energy gamma-ray emission from X-ray binaries, gamma ray and synchrotron emission in interstellar space, galactic soft and hard X-ray emission

  8. The Space System for the High Energy Transient Experiment

    OpenAIRE

    Dill, Bob; Fleeter, Rick; WARNER, RICHARD; Martel, Francois; Ricker, George

    1992-01-01

    The High Energy Transient Experiment (HETE) is an astrophysics project funded by NASA and led by the Center for Space Research (CSR) at the Massachusetts Institute of Technology (MIT). It has for principal goal the detection and precise localization of the still mysterious sources of gamma ray bursts. The project is original in many respects. HETE will provide simultaneous observations of bursts in the gamma, X-ray and UV ranges from the same small (250 Ibms) space platform. A network of grou...

  9. Time lags in biological models

    CERN Document Server

    MacDonald, Norman

    1978-01-01

    In many biological models it is necessary to allow the rates of change of the variables to depend on the past history, rather than only the current values, of the variables. The models may require discrete lags, with the use of delay-differential equations, or distributed lags, with the use of integro-differential equations. In these lecture notes I discuss the reasons for including lags, especially distributed lags, in biological models. These reasons may be inherent in the system studied, or may be the result of simplifying assumptions made in the model used. I examine some of the techniques available for studying the solution of the equations. A large proportion of the material presented relates to a special method that can be applied to a particular class of distributed lags. This method uses an extended set of ordinary differential equations. I examine the local stability of equilibrium points, and the existence and frequency of periodic solutions. I discuss the qualitative effects of lags, and how these...

  10. High-energy detector

    Science.gov (United States)

    Bolotnikov, Aleksey E.; Camarda, Giuseppe; Cui, Yonggang; James, Ralph B.

    2011-11-22

    The preferred embodiments are directed to a high-energy detector that is electrically shielded using an anode, a cathode, and a conducting shield to substantially reduce or eliminate electrically unshielded area. The anode and the cathode are disposed at opposite ends of the detector and the conducting shield substantially surrounds at least a portion of the longitudinal surface of the detector. The conducting shield extends longitudinally to the anode end of the detector and substantially surrounds at least a portion of the detector. Signals read from one or more of the anode, cathode, and conducting shield can be used to determine the number of electrons that are liberated as a result of high-energy particles impinge on the detector. A correction technique can be implemented to correct for liberated electron that become trapped to improve the energy resolution of the high-energy detectors disclosed herein.

  11. High energy excitations

    International Nuclear Information System (INIS)

    Neutron studies at high energies and large momentum transfer Q (≥ 30 A-1) are described with respect to:- some forms of n(p) and S(Q, E) [where n(p) is the probability distribution for the particle momentum and S(Q, E) is the dynamic structure factor], final state interactions, and experimental results for current reactor neutrons. Neutron studies at high energies and small Q [≤ 5 A-1] are discussed, including:-free electron gas, semiconductors, effect of Coulomb interaction, and itinerant ferromagnets. (U.K.)

  12. Theoretical high energy physics

    International Nuclear Information System (INIS)

    This report discusses theoretical research in high energy physics at Columbia University. Some of the research topics discussed are: quantum chromodynamics with dynamical fermions; lattice gauge theory; scattering of neutrinos by photons; atomic physics constraints on the properties of ultralight-ultraweak gauge bosons; black holes; Chern- Simons physics; S-channel theory of superconductivity; charged boson system; gluon-gluon interactions; high energy scattering in the presence of instantons; anyon physics; causality constraints on primordial magnetic manopoles; charged black holes with scalar hair; properties of Chern-Aimona-Higgs solitons; and extended inflationary universe

  13. Three Decades of Explosive High Energy Transients

    Science.gov (United States)

    Kouveliotou, Chryssa

    2013-01-01

    Gamma-Ray Bursts are the most brilliant explosions in space. The first GRB was discovered on 1967, just 40 years ago. It took several years and multiple generations of space and ground instruments to unravel some of the mysteries of this phenomenon. However, many questions remain open today. I will discuss the history, evolution and current status of the GRB field and its contributions in our understanding of the transient high energy sky. Finally, I will describe how GRBs can be utilized in future missions as tools, to probe the cosmic chemical evolution of the Universe and the star formation rates.

  14. High energy colliders

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, R.B.; Gallardo, J.C. [Brookhaven National Lab., Upton, NY (United States). Center for Accelerator Physics

    1997-02-01

    The authors consider the high energy physics advantages, disadvantages and luminosity requirements of hadron (pp, p{anti p}), lepton (e{sup +}e{sup {minus}}, {mu}{sup +}{mu}{sup {minus}}) and photon-photon colliders. Technical problems in obtaining increased energy in each type of machine are presented. The machines relative size are also discussed.

  15. High energy colliders

    International Nuclear Information System (INIS)

    The authors consider the high energy physics advantages, disadvantages and luminosity requirements of hadron (pp, p anti p), lepton (e+e-, μ+μ-) and photon-photon colliders. Technical problems in obtaining increased energy in each type of machine are presented. The machines relative size are also discussed

  16. Theoretical high energy physics

    International Nuclear Information System (INIS)

    This progress report discusses research by Columbia University staff in high energy physics. Some of the topics discussed are as follows: lattice gauge theory; quantum chromodynamics; parity doublets; solitons; baryon number violation; black holes; magnetic monopoles; gluon plasma; Chern-Simons theory; and the inflationary universe

  17. CONSTRAINTS ON VERY HIGH ENERGY EMISSION FROM GRB 130427A

    Energy Technology Data Exchange (ETDEWEB)

    Aliu, E.; Errando, M. [Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027 (United States); Aune, T. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Barnacka, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Beilicke, M.; Buckley, J. H.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W.; Cerruti, M. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Berger, K. [Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States); Biteau, J. [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States); Byrum, K. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Cardenzana, J. V; Dickinson, H. J.; Eisch, J. D. [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Chen, X. [Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm (Germany); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Connaughton, V. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Cui, W. [Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907 (United States); Falcone, A., E-mail: aune@astro.ucla.edu, E-mail: sjzhu@umd.edu, E-mail: veres@email.gwu.edu [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); and others

    2014-11-01

    Prompt emission from the very fluent and nearby (z = 0.34) gamma-ray burst GRB 130427A was detected by several orbiting telescopes and by ground-based, wide-field-of-view optical transient monitors. Apart from the intensity and proximity of this GRB, it is exceptional due to the extremely long-lived high-energy (100 MeV to 100 GeV) gamma-ray emission, which was detected by the Large Area Telescope on the Fermi Gamma-Ray Space Telescope for ∼70 ks after the initial burst. The persistent, hard-spectrum, high-energy emission suggests that the highest-energy gamma rays may have been produced via synchrotron self-Compton processes though there is also evidence that the high-energy emission may instead be an extension of the synchrotron spectrum. VERITAS, a ground-based imaging atmospheric Cherenkov telescope array, began follow-up observations of GRB 130427A ∼71 ks (∼20 hr) after the onset of the burst. The GRB was not detected with VERITAS; however, the high elevation of the observations, coupled with the low redshift of the GRB, make VERITAS a very sensitive probe of the emission from GRB 130427A for E > 100 GeV. The non-detection and consequent upper limit derived place constraints on the synchrotron self-Compton model of high-energy gamma-ray emission from this burst.

  18. High energy nuclear physics

    International Nuclear Information System (INIS)

    The 1988 progress report of the High Energy Nuclear Physics laboratory (Polytechnic School, France), is presented. The Laboratory research program is focused on the fundamental physics of interactions, on the new techniques for the acceleration of charged particles and on the nuclei double beta decay. The experiments are performed on the following topics: the measurement of the π0 inclusive production and the photons production in very high energy nuclei-nuclei interactions and the nucleon stability. Concerning the experiments under construction, a new detector for LEP, the study and simulation of the hadronic showers in a calorimeter and the H1 experiment (HERA), are described. The future research programs and the published papers are listed

  19. High energy photon response

    International Nuclear Information System (INIS)

    This study examines the response of the Hanford 4-chip and 5-chip dosimeter to high energy photons. The dose response of the Hanford Multipurpose Personnel Diometer (HMPD) to photons with energies greater than 0.65 MeV has been evaluated relative to the dose produced by photons from a 60Co. source. The penetrating dose determined with the HMPD is compared to the 1 cm depth dose in tissue measured with an extrapolation chamber. The results of the study indicate that the HMPD can be used to estimate the 1 cm depth dose in tissue from photons with energies between 0.65 MeV and 3.0 MeV to within an accuracy of 15%. However, the 1 cm depth dose is underestimated by 38% when the dosimeter is irradiated in a beam of very high energy photons produced by bombarding a tungsten target with 25 MeV electrons

  20. High Energy Particle Accelerators

    CERN Multimedia

    Audio Productions, Inc, New York

    1960-01-01

    Film about the different particle accelerators in the US. Nuclear research in the US has developed into a broad and well-balanced program.Tour of accelerator installations, accelerator development work now in progress and a number of typical experiments with high energy particles. Brookhaven, Cosmotron. Univ. Calif. Berkeley, Bevatron. Anti-proton experiment. Negative k meson experiment. Bubble chambers. A section on an electron accelerator. Projection of new accelerators. Princeton/Penn. build proton synchrotron. Argonne National Lab. Brookhaven, PS construction. Cambridge Electron Accelerator; Harvard/MIT. SLAC studying a linear accelerator. Other research at Madison, Wisconsin, Fixed Field Alternate Gradient Focusing. (FFAG) Oakridge, Tenn., cyclotron. Two-beam machine. Comments : Interesting overview of high energy particle accelerators installations in the US in these early years. .

  1. High Energy Transients

    CERN Document Server

    Gehrels, Neil

    2012-01-01

    We present an overview of high energy transients in astrophysics, highlighting important advances over the past 50 years. We begin with early discoveries of gamma-ray transients, and then delve into physical details associated with a variety of phenomena. We discuss some of the unexpected transients found by Fermi and Swift, many of which are not easily classifiable or in some way challenge conventional wisdom. These objects are important insofar as they underscore the necessity of future, more detailed studies.

  2. High Energy Astroparticle Physics

    International Nuclear Information System (INIS)

    We give a brief (and highly incomplete) overview of the current experimental and theoretical status of high energy cosmic rays and their secondary γ-rays and neutrinos. We focus on the role of large scale magnetic fields and on multi-messenger aspects linking these three channels. We also recall that the flavor composition of neutrino fluxes from astrophysical sources contains information on both the source conditions and neutrino physics

  3. High Energy Astroparticle Physics

    Energy Technology Data Exchange (ETDEWEB)

    Sigl, Guenter [APC - AstroParticules et Cosmologie, 10, rue Alice Domon et Lonie Duquet, 75205 Paris Cedex 13 (France) and Institut d' Astrophysique de Paris, 98bis Boulevard Arago, 75014 Paris (France)

    2007-06-15

    We give a brief (and highly incomplete) overview of the current experimental and theoretical status of high energy cosmic rays and their secondary {gamma}-rays and neutrinos. We focus on the role of large scale magnetic fields and on multi-messenger aspects linking these three channels. We also recall that the flavor composition of neutrino fluxes from astrophysical sources contains information on both the source conditions and neutrino physics.

  4. Theoretical high energy physics

    International Nuclear Information System (INIS)

    This report discusses progress on theoretical high energy physics at Columbia University in New York City. Some of the topics covered are: Chern-Simons gauge field theories; dynamical fermion QCD calculations; lattice gauge theory; the standard model of weak and electromagnetic interactions; Boson-fermion model of cuprate superconductors; S-channel theory of superconductivity and axial anomaly and its relation to spin in the parton model

  5. Three Decades of High Energy Transients

    Science.gov (United States)

    Kouveliotou, Chryssa

    2012-01-01

    Gamma-Ray Bursts are the most brilliant explosions in space. The first GRB was discovered on 1967, just over 40 years ago. It took several years and multiple generations of space and ground instruments to unravel some of the mysteries of this phenomenon. However, many questions remain open today. I will discuss the history, evolution and current status of the GRB field and its contributions in our understanding of the transient high energy sky. Finally, I will describe how GRBs can be utilized in future missions as tools, to probe the cosmic chemical evolution of the Universe Magnetars are magnetically powered rotating neutron stars with extreme magnetic fields (over 10(exp 14) Gauss). They were discovered in the X- and gamma-rays where they predominantly emit their radiation. Very few sources (roughly 24) have been found since their discovery in 1987. NASA's Fermi Gamma-ray Space Telescope was launched June 11, 2009; since then the Fermi Gamma-ray Burst Monitor (GBM) recorded emission from several magnetar sources. In total, six new sources were discovered between 2008 and 2011, with a synergy between Swift, RXTE, Fermi and the Interplanetary Network (IPN). I will give a short history of magnetars and describe how this, once relatively esoteric field, has emerged as a link between several astrophysical areas including Gamma-Ray Bursts.

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

    DEFF Research Database (Denmark)

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

    1995-01-01

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

  7. Theoretical High Energy Physics

    Energy Technology Data Exchange (ETDEWEB)

    Christ, Norman H.; Weinberg, Erick J.

    2014-07-14

    we provide reports from each of the six faculty supported by the Department of Energy High Energy Physics Theory grant at Columbia University. Each is followed by a bibliography of the references cited. A complete list of all of the publications in the 12/1/2010-04/30/2014 period resulting from research supported by this grant is provided in the following section. The final section lists the Ph.D. dissertations based on research supported by the grant that were submitted during this period.

  8. High energy hadron colliders

    International Nuclear Information System (INIS)

    The more novel and important design considerations and features of high energy hadron colliders (pp or p anti p) are discussed. The paper does not attempt to be sufficient for making a complete design, but contains enough references to other papers necessary for doing so. Formulas are generally given without derivation, and notations are not consistent from section to section. For most formulas the derivation is transparent although the mathematics may be lengthy. Whenever obscure, an explanation of the procedure for derivation will be given in physical terms. Detailed mathematical derivations can be found in the references. 10 references

  9. High energy electron cooling

    Energy Technology Data Exchange (ETDEWEB)

    Parkhomchuk, V. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation)

    1997-09-01

    High energy electron cooling requires a very cold electron beam. The questions of using electron cooling with and without a magnetic field are presented for discussion at this workshop. The electron cooling method was suggested by G. Budker in the middle sixties. The original idea of the electron cooling was published in 1966. The design activities for the NAP-M project was started in November 1971 and the first run using a proton beam occurred in September 1973. The first experiment with both electron and proton beams was started in May 1974. In this experiment good result was achieved very close to theoretical prediction for a usual two component plasma heat exchange.

  10. High energy applications

    International Nuclear Information System (INIS)

    Full text: From the point of view of high energy applications I would like to make the following recommendations: Neutron cross sections from the keV range up to 50 MeV are measured by dedicated mono- energetic fast neutron sources. For the design optimization of fast neutron sources, data files and models of proton and deuteron cross sections and their DDXs on Li and Be isotopes need to be improved utilizing recent experiments and new physics models for Ep dn,p < 2 GeV based on up-to-date physics models and available evaluated files, - identify target accuracies through sensitivity and uncertainty analyses using the recommended library; Inaccurate nuclear data can give rise to engineering margins of a factor 2 to 3 in high energy accelerator shielding design. Improving nuclear data of neutron inelastic scattering as well as activation cross sections for component, structural and shielding materials, such as Na, Al, Mn, Fe, Co, Ni, Cu, Zn for energies up to a few hundreds of MeV, is essential for the reduction of too conservative design margins, which in return would give a huge cost benefit; Radiation effects on micro-electronics (soft errors, damage) by cosmic-ray neutrons need to be predicted in a reliable way. Therefore, more reliable nuclear reaction models which can predict neutron-induced light-ion production from silicon in the incident energy range from MeV to GeV are strongly required. (author)

  11. High energy magnetic spectroscopy

    International Nuclear Information System (INIS)

    The purpose of this paper is twofold: (i) to elucidate the possibilities and limitations of neutron scattering experiments with high energy transfers at low momentum transfers from the view point of the kinematical conditions of the scattering process and (ii) to discuss some examples of high energy magnetic excitations in the field of 4f- and 5f- magnetism. The outcome of point (i) will determine the range of possible energy transfer i.e. will give a reasonable upper bound of 0.5 to leV of energy transfer for momentum transfers around 2 to 5 A-1. This extends the available omega-range by roughly a factor of 10 compared to the conventional magnetic scattering at reactors. Any further, significant increase in energy transfer, however, is not very likely even with very powerful future spallation sources. Thus it is sufficient to restrict the discussion of possible magnetic experiments to energy transfer up to 0.5 or 1 eV

  12. Estimating Redshifts for Long Gamma-Ray Bursts

    OpenAIRE

    Xiao, Limin; Schaefer, Bradley E.

    2009-01-01

    We are constructing a program to estimate the redshifts for GRBs from the original Swift light curves and spectra, aiming to get redshifts for the Swift bursts \\textit{without} spectroscopic or photometric redshifts. We derive the luminosity indicators from the light curves and spectra of each burst, including the lag time between low and high photon energy light curves, the variability of the light curve, the peak energy of the spectrum, the number of peaks in the light curve, and the minimu...

  13. Prospects at high energies

    Energy Technology Data Exchange (ETDEWEB)

    Quigg, C.

    1988-11-01

    I discuss some possibilities for neutrino experiments in the fixed-target environment of the SPS, Tevatron, and UNK, with their primary proton beams of 0.4, 0.9, and 3.0 TeV. The emphasis is on unfinished business: issues that have been recognized for some time, but not yet resolved. Then I turn to prospects for proton-proton colliders to explore the 1-TeV scale. I review the motivation for new physics in the neighborhood of 1 TeV and mention some discovery possibilities for high-energy, high-luminosity hadron colliders and the implications they would have for neutrino physics. I raise the possibility of the direct study of neutrino interactions in hadron colliders. I close with a report on the status of the SSC project. 38 refs., 17 figs.

  14. High energy physics problems

    International Nuclear Information System (INIS)

    Described are modern views on the particle structure and particle interactions at high energies. According to the latest data recieved, all particles can be classified in three groups: 1) strong interacting hadrons; 2) leptons, having no strong interactions; 3) photon. The particle structure is described in a quark model, and with the use of gluons. The elementary particle theory is based on the quantum field theory. The energy increase of interacting particles enables to check the main theory principles, such as conventions for causality, relativistic invariance and unitarity. Investigations of weak interactions are of great importance. The progress in this field is connected with unified gauge theories of weak and electromagnetic interactions. For weak interactions promissing are the experiments with colliding electron-proton rings. The new data, especially at higher energies, will lead to a further refinement of the nature of particles and their interactions

  15. Prospects at high energies

    International Nuclear Information System (INIS)

    I discuss some possibilities for neutrino experiments in the fixed-target environment of the SPS, Tevatron, and UNK, with their primary proton beams of 0.4, 0.9, and 3.0 TeV. The emphasis is on unfinished business: issues that have been recognized for some time, but not yet resolved. Then I turn to prospects for proton-proton colliders to explore the 1-TeV scale. I review the motivation for new physics in the neighborhood of 1 TeV and mention some discovery possibilities for high-energy, high-luminosity hadron colliders and the implications they would have for neutrino physics. I raise the possibility of the direct study of neutrino interactions in hadron colliders. I close with a report on the status of the SSC project. 38 refs., 17 figs

  16. Theoretical high energy physics

    International Nuclear Information System (INIS)

    Brief reports are given on the work of several professors. The following areas are included: quantum chromodynamics calculations using numerical lattice gauge theory and a high-speed parallel computer; the ''spin wave'' description of bosonic particles moving on a lattice with same-site exclusion; a high-temperature expansion to 13th order for the O(4)-symmetric φ4 model on a four-dimensional F4 lattice; spin waves and lattice bosons; superconductivity of C60; meson-meson interferometry in heavy-ion collisions; baryon number violation in the Standard Model in high-energy collisions; hard thermal loops in QCD; electromagnetic interactions of anyons; the relation between Bose-Einstein and BCS condensations; Euclidean wormholes with topology S1 x S2 x R; vacuum decay and symmetry breaking by radiative corrections; inflationary solutions to the cosmological horizon and flatness problems; and magnetically charged black holes

  17. Gamma-Ray Bursts and Cosmology

    Science.gov (United States)

    Norris, Jay P.

    2003-01-01

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

  18. FSU High Energy Physics

    Energy Technology Data Exchange (ETDEWEB)

    Prosper, Harrison B. [Florida State University; Adams, Todd [Florida State University; Askew, Andrew [Florida State University; Berg, Bernd [Florida State University; Blessing, Susan K. [Florida State University; Okui, Takemichi [Florida State University; Owens, Joseph F. [Florida State University; Reina, Laura [Florida State University; Wahl, Horst D. [Florida State University

    2014-12-01

    The High Energy Physics group at Florida State University (FSU), which was established in 1958, is engaged in the study of the fundamental constituents of matter and the laws by which they interact. The group comprises theoretical and experimental physicists, who sometimes collaborate on projects of mutual interest. The report highlights the main recent achievements of the group. Significant, recent, achievements of the group’s theoretical physicists include progress in making precise predictions in the theory of the Higgs boson and its associated processes, and in the theoretical understanding of mathematical quantities called parton distribution functions that are related to the structure of composite particles such as the proton. These functions are needed to compare data from particle collisions, such as the proton-proton collisions at the CERN Large Hadron Collider (LHC), with theoretical predictions. The report also describes the progress in providing analogous functions for heavy nuclei, which find application in neutrino physics. The report highlights progress in understanding quantum field theory on a lattice of points in space and time (an area of study called lattice field theory), the progress in constructing several theories of potential new physics that can be tested at the LHC, and interesting new ideas in the theory of the inflationary expansion of the very early universe. The focus of the experimental physicists is the Compact Muon Solenoid (CMS) experiment at CERN. The report, however, also includes results from the D0 experiment at Fermilab to which the group made numerous contributions over a period of many years. The experimental group is particularly interested in looking for new physics at the LHC that may provide the necessary insight to extend the standard model (SM) of particle physics. Indeed, the search for new physics is the primary task of contemporary particle physics, one motivated by the need to explain certain facts, such as the

  19. High energy plasma accelerators

    International Nuclear Information System (INIS)

    Colinear intense laser beams ω0, kappa0 and ω1, kappa1 shone on a plasma with frequency separation equal to the electron plasma frequency ω/sub pe/ are capable of creating a coherent large longitudinal electric field E/sub L/ = mc ω/sub pe//e of the order of 1GeV/cm for a plasma density of 1018 cm-3 through the laser beat excitation of plasma oscillations. Accompanying favorable and deleterious physical effects using this process for a high energy beat-wave accelerator are discussed: the longitudinal dephasing, pump depletion, the transverse laser diffraction, plasma turbulence effects, self-steepening, self-focusing, etc. The basic equation, the driven nonlinear Schroedinger equation, is derived to describe this system. Advanced accelerator concepts to overcome some of these problems are proposed, including the plasma fiber accelerator of various variations. An advanced laser architecture suitable for the beat-wave accelerator is suggested. Accelerator physics issues such as the luminosity are discussed. Applications of the present process to the current drive in a plasma and to the excitation of collective oscillations within nuclei are also discussed

  20. High energy physics research

    International Nuclear Information System (INIS)

    This is a progress report on the first year of the five year proposal of the UCSD high energy physics group. The main activity of our group continues to be the L3 experiment at LEP. During the last year in L3, we have worked principally on physics analysis. We have also fulfilled our duties in running the detector and contributing to L3 software and computing. In addition, we have made a major effort toward the development of the GEM detector at the SSC. Our SSC work is done in collaboration with the other UCSD groups which are primarily supported by the NSF. In this progress report, we will review our recent activities and describe the current status of the group. Some of the publications and documents which display the work of our group over the last year are included as appendices. We will also outline our research plan to continue our participation in L3 physics and upgrades and to work on the design and construction of the GEM detector

  1. High energy physics

    International Nuclear Information System (INIS)

    This proposal is for the continuation of the High Energy Physics program at the University of California at Riverside. In hadron collider physics the authors will complete their transition from experiment UA1 at CERN to the DZERO experiment at Fermilab. On experiment UA1 their effort will concentrate on data analysis at Riverside. At Fermilab they will coordinate the high voltage system for all detector elements. They will also carry out hardware/software development for the D0 muon detector. The TPC/Two-Gamma experiment has completed its present phase of data-taking after accumulating 160 pb-1 of luminosity. The UC Riverside group will continue data and physics analysis and make minor hardware improvement for the high luminosity run. The UC Riverside group is participating in design and implementation of the data acquisition system for the OPAL experiment at LEP. Mechanical and electronics construction of the OPAL hadron calorimeter strip readout system is proceeding on schedule. Data analysis and Monte Carlo detector simulation efforts are proceeding in preparation for the first physics run when IEP operation comenses in fall 1989

  2. Very high energy colliders

    Energy Technology Data Exchange (ETDEWEB)

    Richter, B.

    1985-05-01

    The conclusions are relatively simple, but represent a considerable challenge to the machine builder. High luminosity is essential. We may in the future discover some new kind of high cross section physics, but all we know now indicates that the luminosity has to increase as the square of the center of mass energy. A reasonable luminosity to scale from for electron machines would be 10/sup 33/ cm/sup -2/ s/sup -1/ at a center of mass energy of 3 TeV. The required emittances in very high energy machines are small. It will be a real challenge to produce these small emittances and to maintain them during acceleration. The small emittances probably make acceleration by laser techniques easier, if such techniques will be practical at all. The beam spot sizes are very small indeed. It will be a challenge to design beam transport systems with the necessary freedom from aberration required for these small spot sizes. It would of course help if the beta functions at the collision points could be reduced. Beam power will be large - to paraphrase the old saying, ''power is money'' - and efficient acceleration systems will be required.

  3. Synchronization of the minimal models of bursting neurons coupled by delayed chemical or electrical synapses

    Institute of Scientific and Technical Information of China (English)

    Neboj?a Vasovi; Nikola Buri; Kristina Todorovi; Ines Grozdanovi

    2012-01-01

    The minimal two-dimensional model of bursting neuronal dynamics is used to study the influence of time-delay on the properties of synchronization of bursting neurons.Generic properties of bursting and dependence of the stability of synchronization on the time-lag and the strength of coupling are described,and compared with the two common types of synaptical coupling,i.e.,time-delayed chemical and electrical synapses.

  4. Constraints on Very High Energy Emission from GRB 130427A

    CERN Document Server

    Aliu, E; Barnacka, A; Beilicke, M; Benbow, W; Berger, K; Biteau, J; Buckley, J H; Bugaev, V; Byrum, K; Cardenzana, J V; Cerruti, M; Chen, X; Ciupik, L; Connaughton, V; Cui, W; Dickinson, H J; Eisch, J D; Errando, M; Falcone, A; Federici, S; Feng, Q; Finley, J P; Fleischhack, H; Fortin, P; Fortson, L; Furniss, A; Galante, N; Gillanders, G H; Griffin, S; Griffiths, S T; Grube, J; Gyuk, G; Håkansson, N; Hanna, D; Holder, J; Hughes, G; Humensky, T B; Johnson, C A; Kaaret, P; Kar, P; Kertzman, M; Khassen, Y; Kieda, D; Krawczynski, H; Krennrich, F; Lang, M J; Madhavan, A S; Maier, G; McArthur, S; McCann, A; Meagher, K; Millis, J; Moriarty, P; Mukherjee, R; Nieto, D; de Bhróithe, A O'Faoláin; Ong, R A; Otte, A N; Park, N; Pohl, M; Popkow, A; Prokoph, H; Pueschel, E; Quinn, J; Ragan, K; Rajotte, J; Reyes, L C; Reynolds, P T; Richards, G T; Roache, E; Sembroski, G H; Shahinyan, K; Smith, A W; Staszak, D; Telezhinsky, I; Tucci, J V; Tyler, J; Varlotta, A; Vassiliev, V V; Vincent, S; Wakely, S P; Weiner, O M; Weinstein, A; Welsing, R; Wilhelm, A; Williams, D A; Zitzer, B; McEnery, J E; Perkins, J S; Veres, P; Zhu, S

    2014-01-01

    Prompt emission from the very fluent and nearby (z=0.34) gamma-ray burst GRB 130427A was detected by several orbiting telescopes and by ground-based, wide-field-of-view optical transient monitors. Apart from the intensity and proximity of this GRB, it is exceptional due to the extremely long-lived high-energy (100 MeV to 100 GeV) gamma-ray emission, which was detected by the Large Area Telescope on the Fermi Gamma-ray Space Telescope for ~70 ks after the initial burst. The persistent, hard-spectrum, high-energy emission suggests that the highest-energy gamma rays may have been produced via synchrotron self-Compton processes though there is also evidence that the high-energy emission may instead be an extension of the synchrotron spectrum. VERITAS, a ground-based imaging atmospheric Cherenkov telescope array, began follow-up observations of GRB 130427A ~71 ks (~20 hr) after the onset of the burst. The GRB was not detected with VERITAS; however, the high elevation of the observations, coupled with the low redsh...

  5. Lectures on High-Energy Neutrino Astronomy

    International Nuclear Information System (INIS)

    Kilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the observational fact that Nature produces protons and photons with energies in excess of 1020 and 1013 eV, respectively. The cosmic ray connection sets the scale of cosmic neutrino fluxes. In this context, we discuss the first results of the completed AMANDA detector and the science reach of its extension, IceCube. Similar experiments are under construction in the Mediterranean. Neutrino astronomy is also expanding in new directions with efforts to detect air showers, acoustic and radio signals initiated by super-EeV neutrinos. The outline of these lectures is as follows: Introduction Cosmic Neutrinos Associated with the Highest Energy Cosmic Rays Why Kilometer-Scale Detectors? Blueprints of Cosmic Accelerators: Gamma Ray Bursts and Active Galaxies High Energy Neutrino Telescopes: Methodologies of Neutrino Detection High Energy Neutrino Telescopes: Status

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

    DEFF Research Database (Denmark)

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

    1995-01-01

    19 Cosmic Gamma-Ray Bursts were detected by the WATCH wide field X-ray monitor during the 11 months flight of EURECA. The identification of the bursts were complicated by a high frequency of background of events caused by high energy cosmic ray interactions in the detector and by low energy......, trapped particle streams. These background events may simulate the count rate increases characteristic of cosmic gamma bursts. For 12 of the detected events, their true cosmic nature have been confirmed through consistent localizations of the burst sources based on several independent WATCH data sets. The...... derived positions of the bursts are reported. Additionally, most of the events have been confirmed by coincident detections with instruments on other spacecrafts. The features of two of the bursts and the results of searches for related events in the optical are described....

  7. Computing in high energy physics

    International Nuclear Information System (INIS)

    The increasingly important role played by computing and computers in high energy physics is displayed in the 'Computing in High Energy Physics' series of conferences, bringing together experts in different aspects of computing - physicists, computer scientists, and vendors

  8. High-energy spectroscopic astrophysics

    Science.gov (United States)

    Güdel, Manuel; Walter, Roland

    After three decades of intense research in X-ray and gamma-ray astronomy, the time was ripe to summarize basic knowledge on X-ray and gamma-ray spectroscopy for interested students and researchers ready to become involved in new high-energy missions. This volume exposes both the scientific basics and modern methods of high-energy spectroscopic astrophysics. The emphasis is on physical principles and observing methods rather than a discussion of particular classes of high-energy objects, but many examples and new results are included in the three chapters as well.

  9. Conference on High Energy Physics

    CERN Document Server

    2016-01-01

    Conference on High Energy Physics (HEP 2016) will be held from August 24 to 26, 2016 in Xi'an, China. This Conference will cover issues on High Energy Physics. It dedicates to creating a stage for exchanging the latest research results and sharing the advanced research methods. HEP 2016 will be an important platform for inspiring international and interdisciplinary exchange at the forefront of High Energy Physics. The Conference will bring together researchers, engineers, technicians and academicians from all over the world, and we cordially invite you to take this opportunity to join us for academic exchange and visit the ancient city of Xi’an.

  10. Adaptive lag synchronization and parameters adaptive lag identification of chaotic systems

    Energy Technology Data Exchange (ETDEWEB)

    Xu Yuhua, E-mail: yuhuaxu2004@163.co [College of Information Science and Technology, Donghua University, Shanghai 201620 (China) and Department of Mathematics, Yunyang Teachers' College, Hubei, Shiyan 442000 (China); Zhou Wuneng, E-mail: wnzhou@163.co [College of Information Science and Technology, Donghua University, Shanghai 201620 (China) and Key Laboratory of Wireless Sensor Network and Communication, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Fang Jian' an, E-mail: jafang@dhu.edu.c [College of Information Science and Technology, Donghua University, Shanghai 201620 (China); Sun Wen, E-mail: sunwen_2201@163.co [School of Mathematics and Information, Yangtze University, Hubei, Jingzhou 434023 (China)

    2010-07-26

    This Letter investigates the problem of adaptive lag synchronization and parameters adaptive lag identification of chaotic systems. In comparison with those of existing parameters identification schemes, the unknown parameters are identified by adaptive lag laws, and the delay time is also identified in this Letter. Numerical simulations are also given to show the effectiveness of the proposed method.

  11. Adaptive lag synchronization and parameters adaptive lag identification of chaotic systems

    International Nuclear Information System (INIS)

    This Letter investigates the problem of adaptive lag synchronization and parameters adaptive lag identification of chaotic systems. In comparison with those of existing parameters identification schemes, the unknown parameters are identified by adaptive lag laws, and the delay time is also identified in this Letter. Numerical simulations are also given to show the effectiveness of the proposed method.

  12. How Long does a Burst Burst?

    CERN Document Server

    Zhang, Bin-Bin; Murase, Kohta; Connaughton, Valerie; Briggs, Michael S

    2013-01-01

    Several gamma-ray bursts (GRBs) last much longer (~ hours) in gamma-rays than typical long GRBs (~ minutes), and recently it was proposed that these "ultra-long GRBs" may form a distinct population, probably with a different (e.g. blue supergiant) progenitor than typical GRBs. However, Swift observations have suggested that many GRBs have extended central engine activities manifested as flares and internal plateaus in X-rays. We perform a comprehensive study on a large sample of Swift GRBs with XRT observations to investigate GRB central engine activity duration and to check whether ultra-long GRBs are special. We define burst duration t_{burst} based on both gamma-ray and X-ray light curves rather than using gamma-ray observations only. We show that the distribution of t_{burst} peaks at ~ 320s for the entire sample, with 17.6% GRBs having t_{burst} > 10^3 s and 5.4% GRBs having t_{burst} > 10^4 s. The distribution shows a tail at the long t_{burst} end. The existence of a separate population is not ruled ou...

  13. [Research in high energy physics

    International Nuclear Information System (INIS)

    This report discusses progress in the following research in high energy physics: The crystal ball experiment; delco at PEP; proton decay experiment; MACRO detector; mark III detector; SLD detector; CLEO II detector; and the caltech L3 group

  14. Prospects of high energy physics

    International Nuclear Information System (INIS)

    High energy physics solves the question of the structure of matter. For experiments in this field using large accelerators it will be necessary to involve large groups of people of various orientations and specializations on a high professional level. This is manifest in the education of physicists at Moscow State University which for this purpose cooperates with the Joint Institute for Nuclear Research and the Institute for High Energy Physics in Serpukhov. International cooperation is immensely important for the development of high energy physics. Its interruption would have negative impact on development in this field both in the socialist and in the capitalist countries. The general relativity theory stands apart from this upsurge of high energy physics, mainly owing to the lack of experimental material. (Ha)

  15. High Energy Transport Code HETC

    International Nuclear Information System (INIS)

    The physics contained in the High Energy Transport Code (HETC), in particular the collision models, are discussed. An application using HETC as part of the CALOR code system is also given. 19 refs., 5 figs., 3 tabs

  16. Research in high energy physics

    International Nuclear Information System (INIS)

    This report discusses research being conducted in high energy physics in the following areas: quantum chromodynamics; drift chambers; proton-antiproton interactions; particle decays; particle production; polarimeters; quark-gluon plasma; and conformal field theory. (LSP)

  17. Computing in high energy physics

    International Nuclear Information System (INIS)

    Computing in high energy physics has changed over the years from being something one did on a slide-rule, through early computers, then a necessary evil to the position today where computers permeate all aspects of the subject from control of the apparatus to theoretical lattice gauge calculations. The state of the art, as well as new trends and hopes, were reflected in this year's 'Computing In High Energy Physics' conference held in the dreamy setting of Oxford's spires. The conference aimed to give a comprehensive overview, entailing a heavy schedule of 35 plenary talks plus 48 contributed papers in two afternoons of parallel sessions. In addition to high energy physics computing, a number of papers were given by experts in computing science, in line with the conference's aim – 'to bring together high energy physicists and computer scientists'

  18. High Energy Density Capacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA?s future space science missions cannot be realized without the state of the art energy storage devices which require high energy density, high reliability, and...

  19. Research in high energy physics

    International Nuclear Information System (INIS)

    This report discusses research being conducted in high energy physics in the following areas: quantum chromodynamics; drift chambers; proton-antiproton interactions; particle decays; particle production; polarimeters; quark-gluon plasma; and conformed field theory

  20. Problems of high energy physics

    International Nuclear Information System (INIS)

    Some problems of high energy physics are discussed. The main attention is paid to describibg the standard model. The model comprises quantum chromodynamics and electroweak interaction theory. The problem of CP breaking is considered as well. 8 refs.; 1 tab

  1. Research in high energy physics

    International Nuclear Information System (INIS)

    This report discusses research being conducted in high energy physics in the following areas; quantum chromodynamics; drift chambers; proton-antiproton interactions; particle decays; particle production; polarimeters; quark-gluon plasma; and conformed field theory

  2. High energy neutrinos from GRBs

    Energy Technology Data Exchange (ETDEWEB)

    De Paolis, F.; Ingrosso, G.; Orlando, D.; Perrone, L

    2001-05-01

    It is by now recognized that GRBs can accelerate protons to relativistic energies and that high density media may be present nearby the source. We compute the high-energy {gamma}-ray and neutrino fluxes from the decay of pions produced through the interaction of accelerated protons with nucleons in the surrounding medium. Then, we estimate the flux of high-energy muons induced on a detector by upward-going neutrinos interacting through charge current processes with the surrounding matter.

  3. High energy neutrinos from GRBs

    International Nuclear Information System (INIS)

    It is by now recognized that GRBs can accelerate protons to relativistic energies and that high density media may be present nearby the source. We compute the high-energy γ-ray and neutrino fluxes from the decay of pions produced through the interaction of accelerated protons with nucleons in the surrounding medium. Then, we estimate the flux of high-energy muons induced on a detector by upward-going neutrinos interacting through charge current processes with the surrounding matter

  4. Ultra-High Energy Cosmic Rays

    Science.gov (United States)

    Colon, Rafael Antonio; Moncada, Roberto; Guerra, Juan; Anchordoqui, Luis

    2016-01-01

    The search for the origin(s) of ultra-high energy (UHE) cosmic rays (CR) remains one of the cornerstones of high energy astrophysics. The previously proposed sources of acceleration for these UHECRs were gamma-ray bursts (GRB) and active galactic nuclei (AGN) due to their energetic activity and powerful jets. However, a problem arises between the acceleration method and the observed CR spectrum. The CRs from GRBs or AGN jets are assumed to undergo Fermi acceleration and a source injection spectrum proportional to E^-2 is expected. However, the most recent fits to the spectrum and nuclear composition suggest an injection spectrum proportional to E^-1. It is well known that such a hard spectrum is characteristic of unipolar induction of rotating compact objects. When this method is applied to the AGN cores, they prove to be much too luminous to accelerate CR nuclei without photodisintegrating, thus creating significant energy losses. Instead, here we re-examine the possibility of these particles being accelerated around the much less luminous quasar remnants, or dead quasars. We compare the interaction times of curvature radiation and photodisintegration, the two primary energy loss considerations with the acceleration time scale. We show that the energy losses at the source are not significant enough as to prevent these CRs from reaching the maximum observed energies. Using data from observatories in the northern and southern sky, the Telescope Array and the Pierre Auger Observatory respectively, two hotspots have been discerned which have some associated quasar remnants that help to motivate our study.

  5. Terrestrial Effects of High Energy Cosmic Rays

    Science.gov (United States)

    Atri, Dimitra

    2011-01-01

    On geological timescales, the Earth is likely to be exposed to an increased flux of high energy cosmic rays (HECRs) from astrophysical sources such as nearby supernovae, gamma ray bursts or by galactic shocks. These high-energy particles strike the Earth's atmosphere initiating an extensive air shower. As the air shower propagates deeper, it ionizes the atmosphere by producing charged secondary particles. Increased ionization could lead to changes in atmospheric chemistry, resulting in ozone depletion. This could increase the flux of solar UVB radiation at the surface, which is potentially harmful to living organisms. Increased ionization affects the global electrical circuit can could possibly enhance the low-altitude cloud formation rate. Secondary particles such as muons and thermal neutrons produced as a result of nuclear interactions are able to reach the ground, enhancing the biological radiation dose. The muon flux dominates radiation dose from cosmic rays causing DNA damage and increase in the mutation rates, which can have serious biological implications for terrestrial and sub-terrestrial life. This radiation dose is an important constraint on the habitability of a planet. Using CORSIKA, we perform massive computer simulations and construct lookup tables from 10 GeV - 1 PeV primaries (1 PeV - 0.1 ZeV in progress), which can be used to quantify these effects. These tables are freely available to the community and can be used for other studies, not necessarily relevant to Astrobiology. We use these tables to study the terrestrial implications of galactic shock generated by the infall of our galaxy toward the Virgo cluster. This could be a possible mechanism explaining the observed periodicity in biodiversity in paleobiology databases.

  6. Multimessenger astrophysics: When gravitational waves meet high energy neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Di Palma, Irene, E-mail: Irene.DiPalma@aei.mpg.de

    2014-04-01

    With recent development of experimental techniques that have opened new windows of observation of the cosmic radiation in all its components, multi-messenger astronomy is entering an exciting era. Many astrophysical sources and cataclysmic cosmic events with burst activity can be plausible sources of concomitant gravitational waves (GWs) and high-energy neutrinos (HENs). Such messengers could reveal hidden and new sources that are not observed by conventional photon astronomy, in particular at high energy. Requiring consistency between GW and HEN detection channels enables new searches and a detection would yield significant additional information about the common source. We present the results of the first search for gravitational wave bursts associated with high energy neutrino triggers, detected by the underwater neutrino telescope ANTARES in its 5 line configuration, during the fifth LIGO science run and first Virgo science run. No evidence for coincident events was found. We place a lower limit on the distance to GW sources associated with every HEN trigger. We are able to rule out the existence of coalescing binary neutron star systems and black hole–neutron star systems up to distances that are typically 5 Mpc and 10 Mpc respectively.

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

    Science.gov (United States)

    Hjorth, Jens

    2013-06-13

    The observed association between supernovae and gamma-ray bursts represents a cornerstone in our understanding of the nature of gamma-ray bursts. The collapsar model provides a theoretical framework for this connection. A key element is the launch of a bipolar jet (seen as a gamma-ray burst). The resulting hot cocoon disrupts the star, whereas the (56)Ni produced gives rise to radioactive heating of the ejecta, seen as a supernova. In this discussion paper, I summarize the observational status of the supernova-gamma-ray burst connection in the context of the 'engine' picture of jet-driven supernovae and highlight SN 2012bz/GRB 120422A--with its luminous supernova but intermediate high-energy luminosity--as a possible transition object between low-luminosity and jet gamma-ray bursts. The jet channel for supernova explosions may provide new insights into supernova explosions in general. PMID:23630379

  8. MAGIC upper limits on the high energy emission from GRBs

    CERN Document Server

    Albert, J; Anderhub, H; Antoranz, P; Armada, A; Baixeras, C; Barrio, J A; Bartko, H; Bastieri, D; Becker, J; Bednarek, W; Berger, K; Bigongiari, C; Biland, A; Böck, R K; Bordas, P; Bosch-Ramon, V; Bretz, T; Britvitch, I; Camara, M; Carmona, E; Chilingarian, A A; Ciprini, S; Coarasa, J A; Commichau, S C; Contreras, J L; Cortina, J; Costado, M T; Curtef, V; Danielyan, V; Dazzi, F; De Angelis, A; Delgado, C; de Reyes, R; De Lotto, B; Domingo-Santamaria, E; Dorner, D; Doro, M; Errando, M; Fagiolini, M; Ferenc, D; Fernández, E; Firpo, R; Flix, J; Fonseca, M V; Font, L; Fuchs, M; Galante, N; Garcia-Lopez, R; Garczarczyk, M; Gaug, M; Giller, M; Göbel, F; Hakobyan, D; Hayashida, M; Hengstebeck, T; Herrero, A; Höhne, D; Hose, J; Hsu, C C; al., et

    2007-01-01

    The fast repositioning system of the MAGIC Telescope has allowed during its first data cycle, between 2005 and the beginning of year 2006, observing nine different GRBs as possible sources of very high energy gammas. These observations were triggered by alerts from Swift, HETE-II, and Integral; they started as fast as possible after the alerts and lasted for several minutes, with an energy threshold varying between 80 and 200 GeV, depending upon the zenith angle of the burst. No evidence for gamma signals was found, and upper limits for the flux were derived for all events, using the standard analysis chain of MAGIC. For the bursts with measured redshift, the upper limits are compatible with a power law extrapolation, when the intrinsic fluxes are evaluated taking into account the attenuation due to the scattering in the Metagalactic Radiation Field (MRF).

  9. Did high energy astrophysical sources contribute to Martian atmospheric loss?

    CERN Document Server

    Atri, Dimitra

    2016-01-01

    Mars is believed to have had a substantial atmosphere in the past. Atmospheric loss led to depressurization and cooling, and is thought to be the primary driving force responsible for the loss of liquid water from its surface. Recently, MAVEN observations have provided new insight into the physics of atmospheric loss induced by ICMEs and solar wind interacting with the Martian atmosphere. In addition to solar radiation, it is likely that its atmosphere has been exposed to radiation bursts from high-energy astrophysical sources which become highly probable on timescales of ~Gy and beyond. These sources are capable of significantly enhancing the rates of photoionization and charged particle-induced ionization in the upper atmosphere. Here, we explore the possibility of damage from Galactic Gamma Ray Bursts, nearby supernovae, encounter with dense interstellar clouds and extreme solar events. We use Monte Carlo simulations to model the interaction of charged particles and photons from astrophysical sources in th...

  10. Toward an Understanding of GRB Prompt Emission Mechanism. I. The Origin of Spectral Lags

    Science.gov (United States)

    Uhm, Z. Lucas; Zhang, Bing

    2016-07-01

    Despite decades of investigations, the physical mechanism that powers the bright prompt γ-ray emission from gamma-ray bursts (GRBs) is still not identified. One important observational clue that still has not been properly interpreted is the existence of time lags of broad light curve pulses in different energy bands, referred to as “spectral lags.” Here, we show that the traditional view invoking the high-latitude emission “curvature effect” of a relativistic jet cannot account for spectral lags. Rather, the observed spectral lags demand the sweep of a spectral peak across the observing energy band in a specific manner. The duration of the broad pulses and inferred typical Lorentz factor of GRBs require that the emission region be in an optically thin emission region far from the GRB central engine. We construct a simple physical model invoking synchrotron radiation from a rapidly expanding outflow. We show that the observed spectral lags appear naturally in our model light curves given that (1) the gamma-ray photon spectrum is curved (as observed), (2) the magnetic field strength in the emitting region decreases with radius as the region expands in space, and (3) the emission region itself undergoes rapid bulk acceleration as the prompt γ-rays are produced. These requirements are consistent with a Poynting-flux-dominated jet abruptly dissipating magnetic energy at a large distance from the engine.

  11. Time lag in transient cosmic accreting sources

    CERN Document Server

    Bisnovatyi-Kogan, G S

    2016-01-01

    We develop models for time lag between maxima of the source brightness in different wavelengths during a transient flash of luminosity connected with a short period of increase of the mass flux onto the central compact object. We derive a simple formula for finding the time delay among events in different wavelengths, valid in general for all disk accreting cosmic sources, and discuss quantitatively a model for time lag formation in AGNs. In close binaries with accretion disks the time lag is connected with effects of viscosity defining a radial motion of matter in the accretion disk. In AGN flashes, the falling matter has a low angular momentum, and the time lag is defined by the free fall time to the gravitating center. We show the validity of these models by means of several examples of galactic and extragalactic accreting sources.

  12. The Cosmic Gamma-Ray Bursts

    Science.gov (United States)

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

    2002-12-01

    Cosmic γ-ray bursts are one of the great frontiers of astrophysics today. They are a playground of relativists and observers alike. They may teach us about the death of stars and the birth of black holes, the physics in extreme conditions, and help us probe star formation in the distant and obscured universe. In this review we summarise some of the remarkable progress in this field over the past few years. While the nature of the GRB progenitors is still unsettled, it now appears likely that at least some bursts originate in explosions of very massive stars, or at least occur in or near the regions of massive star formation. The physics of the burst afterglows is reasonably well understood, and has been tested and confirmed very well by the observations. Bursts are found to be beamed, but with a broad range of jet opening angles; the mean γ-ray energies after the beaming corrections are ~ 1051 erg. Bursts are associated with faint ( ~ 25 mag) galaxies at cosmological redshifts, with ~ 1. The host galaxies span a range of luminosities and morphologies, but appear to be broadly typical for the normal, actively star-forming galaxy populations at comparable redshifts and magnitudes. Some of the challenges for the future include: the nature of the short bursts and possibly other types of bursts and transients; use of GRBs to probe the obscured star formation in the universe, and possibly as probes of the very early universe; and their detection as sources of high-energy particles and gravitational waves.

  13. High Energy Physics Departments - Overview

    International Nuclear Information System (INIS)

    Following the tradition, the activities of the seven new units created in 1997 on the basis of the former Department of High Energy Physics are presented under a common header, they are: Department of Particle Theory (Dept 5); Department of Leptonic Interactions (Dept 11); Department of Hadron Structure (Dept 12); Department of High Energy Nuclear Interactions (Dept 13); The ALICE Experiment Laboratory (NAL); The ATLAS Experiment Laboratory (NAT); High Energy Physics Detector Construction Group (PBD). The research covers a variety of problems of the experimental and theoretical high energy particle physics: the hadronic and leptonic interactions with nucleons and nuclei (characteristics of particle production, including heavy quark physics), e+e- interactions and tests of the Standard Model (also radiative corrections), ultrarelativistic heavy ion interactions and search for the quark-gluon plasma, as well as the spectra, composition and interactions of high energy cosmic ray particles. Research on detectors and accelerator components as well as the development of the apparatus for the high energy physics experiments at future accelerators: LHC (CERN, Geneva), RHIC (Brookhaven), B-Factory (KEK, Tsukuba) and TESLA (DESY) is also presented. The technology of new materials with unique properties such as carbon-carbon composites is also worked on from the point of view of their application in high energy physics experiments. The Division is located in a separate building on the campus of the University of Mining and Metallurgy (UMM). This location, close to the Jagiellonian University (JU), facilitates the collaboration with the latter and with the UMM. The joint weekly seminars carried out for nearly 40 years prove this long term tradition. A substantial part of the activities is teaching and training students from the academic community in Cracow. Joint research, teaching and academic training in the high energy physics are carried out within the M. Miesowicz Inter

  14. How long does a burst burst?

    International Nuclear Information System (INIS)

    Several gamma-ray bursts (GRBs) last much longer (∼hours) in γ-rays than typical long GRBs (∼minutes), and it has recently been proposed that these 'ultra-long GRBs' may form a distinct population, probably with a different (e.g., blue supergiant) progenitor than typical GRBs. However, Swift observations suggest that many GRBs have extended central engine activities manifested as flares and internal plateaus in X-rays. We perform a comprehensive study on a large sample of Swift GRBs with X-Ray Telescope observations to investigate GRB central engine activity duration and to determine whether ultra-long GRBs are unusual events. We define burst duration t burst based on both γ-ray and X-ray light curves rather than using γ-ray observations alone. We find that t burst can be reliably measured in 343 GRBs. Within this 'good' sample, 21.9% GRBs have t burst ≳ 103 s and 11.5% GRBs have t burst ≳ 104 s. There is an apparent bimodal distribution of t burst in this sample. However, when we consider an 'undetermined' sample (304 GRBs) with t burst possibly falling in the gap between GRB duration T 90 and the first X-ray observational time, as well as a selection effect against t burst falling into the first Swift orbital 'dead zone' due to observation constraints, the intrinsic underlying t burst distribution is consistent with being a single component distribution. We found that the existing evidence for a separate ultra-long GRB population is inconclusive, and further multi-wavelength observations are needed to draw a firmer conclusion. We also discuss the theoretical implications of our results. In particular, the central engine activity duration of GRBs is generally much longer than the γ-ray T 90 duration and it does not even correlate with T 90. It would be premature to make a direct connection between T 90 and the size of the progenitor star.

  15. Source Coding with Fixed Lag Side Information

    OpenAIRE

    Martinian, Emin; Wornell, Gregory W.

    2004-01-01

    We consider source coding with fixed lag side information at the decoder. We focus on the special case of perfect side information with unit lag corresponding to source coding with feedforward (the dual of channel coding with feedback) introduced by Pradhan. We use this duality to develop a linear complexity algorithm which achieves the rate-distortion bound for any memoryless finite alphabet source and distortion measure.

  16. IMAGE CONSTRUCTION OF LAGGING TOURIST DESTINATION

    OpenAIRE

    Li, Yongjun

    2007-01-01

    Tourist destination image, as tourists integrated subjective cognition and evaluation, directly influences tourist choices for destinations. This paper discusses the existing problems such as indefinition of target market, unperfection of product and lack of competitive analysis at the very beginning of lagging tourist destinations. Using Luanchuan, a county in Henan province as an example, construction factors and the mode, the terminal form and its popularization of lagging tourist destinat...

  17. High energy cosmic ray astronomy

    International Nuclear Information System (INIS)

    A brief introduction to High Energy Cosmic Ray Astronomy is presented. This field covers a 17 decade energy range (2.104-1020) eV. Recent discoveries done with gamma-ray detectors on-board satellites and ground-based Cherenkov devices are pushing for a fast development of new and innovative techniques, specially in the low energy region which includes the overlapping of satellite and ground-based measurements in the yet unexplored energy range 20 keV-250 GeV. Detection of unexpected extremely high energy events have triggered the interest of the international scientific community. (orig.)

  18. Extraterrestrial high energy neutrino fluxes

    International Nuclear Information System (INIS)

    With the aid of using the most recent cosmic ray spectra up to 2x1020 eV, production spectra of high-energy neutrinos from cosmic ray interactions with interstellar gas and extragalactic interactions of ultrahigh-energy cosmic rays with 3K universal background photons are presented and discussed. Estimates of the fluxes from cosmic diffuse sources and the nearby quasar 3C273 are made using the generic relationship between secondary neutrinos and gammas and using recent gamma ray satellite data. These gamma ray data provide important upper limits on cosmological neutrinos. Quantitative estimates of the observability of high-energy neutrinos from the inner galaxy and 3C273 above atmospheric background for a DUMAND-type detector are discussed in the context of the Weinberg-Salam model with sin2 theta/sub ω/ = 0.2 and including the atmospheric background from the decay of charmed mesons. Constraints on cosmological high-energy neutrino production models are also discussed. It appears that important high-energy neutrino astronomy may be possible with DUMAND, but very long observing times are required

  19. Extraterrestrial high energy neutrino fluxes

    Science.gov (United States)

    Stecker, F. W.

    1979-01-01

    Using the most recent cosmic ray spectra up to 2x10 to the 20th power eV, production spectra of high energy neutrinos from cosmic ray interactions with interstellar gas and extragalactic interactions of ultrahigh energy cosmic rays with 3K universal background photons are presented and discussed. Estimates of the fluxes from cosmic diffuse sources and the nearby quasar 3C273 are made using the generic relationship between secondary neutrinos and gammas and using recent gamma ray satellite data. These gamma ray data provide important upper limits on cosmological neutrinos. Quantitative estimates of the observability of high energy neutrinos from the inner galaxy and 3C273 above atmospheric background for a DUMAND type detector are discussed in the context of the Weinberg-Salam model with sq sin theta omega = 0.2 and including the atmospheric background from the decay of charmed mesons. Constraints on cosmological high energy neutrino production models are also discussed. It appears that important high energy neutrino astronomy may be possible with DUMAND, but very long observing times are required.

  20. Extraterrestrial high energy neutrino fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Stecker, F.W.

    1979-06-01

    With the aid of using the most recent cosmic ray spectra up to 2x10/sup 20/ eV, production spectra of high-energy neutrinos from cosmic ray interactions with interstellar gas and extragalactic interactions of ultrahigh-energy cosmic rays with 3K universal background photons are presented and discussed. Estimates of the fluxes from cosmic diffuse sources and the nearby quasar 3C273 are made using the generic relationship between secondary neutrinos and gammas and using recent gamma ray satellite data. These gamma ray data provide important upper limits on cosmological neutrinos. Quantitative estimates of the observability of high-energy neutrinos from the inner galaxy and 3C273 above atmospheric background for a DUMAND-type detector are discussed in the context of the Weinberg-Salam model with sin/sup 2/ theta/sub ..omega../ = 0.2 and including the atmospheric background from the decay of charmed mesons. Constraints on cosmological high-energy neutrino production models are also discussed. It appears that important high-energy neutrino astronomy may be possible with DUMAND, but very long observing times are required.

  1. High Energy Neutrinos from Space

    CERN Document Server

    Gaisser, Thomas K

    2012-01-01

    This paper reviews the status of the search for high-energy neutrinos from astrophysical sources. Results from large neutrino telescopes in water (Antares, Baikal) and ice (IceCube) are discussed as well as observations from the surface with Auger and from high altitude with ANITA. Comments on IceTop, the surface component of IceCube are also included.

  2. High Energy Cosmic Electrons: Messengers from Nearby Cosmic Ray Sources or Dark Matter?

    Science.gov (United States)

    Moiseev, Alexander

    2011-01-01

    This slide presentation reviews the recent discoveries by the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-Ray Telescope in reference to high energy cosmic electrons, and whether their source is cosmic rays or dark matter. Specific interest is devoted to Cosmic Ray electrons anisotropy,

  3. Thermonuclear burst oscillations

    CERN Document Server

    Watts, Anna L

    2012-01-01

    Burst oscillations, a phenomenon observed in a significant fraction of Type I (thermonuclear) X-ray bursts, involve the development of highly asymmetric brightness patches in the burning surface layers of accreting neutron stars. Intrinsically interesting as nuclear phenomena, they are also important as probes of dense matter physics and the strong gravity, high magnetic field environment of the neutron star surface. Burst oscillation frequency is also used to measure stellar spin, and doubles the sample of rapidly rotating (above 10 Hz) accreting neutron stars with known spins. Although the mechanism remains mysterious, burst oscillation models must take into account thermonuclear flame spread, nuclear processes, rapid rotation, and the dynamical role of the magnetic field. This review provides a comprehensive summary of the observational properties of burst oscillations, an assessment of the status of the theoretical models that are being developed to explain them, and an overview of how they can be used to...

  4. A search for Gamma Ray Burst Neutrinos in AMANDA

    NARCIS (Netherlands)

    Duvoort, M.R.

    2009-01-01

    To date, no neutrinos with energies in or above the GeV range have been identified from astrophysical objects. The aim of the two analyses described in this dissertation is to observe high-energy muon neutrinos from Gamma Ray Bursts (GRBs). GRBs are distant sources, which were discovered by satellit

  5. Gamma-Ray Burst Physics with GLAST

    Energy Technology Data Exchange (ETDEWEB)

    Omodei, N.; /INFN, Pisa

    2006-10-06

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

  6. Harvard University High Energy Physics

    International Nuclear Information System (INIS)

    The mainly experimental research program in high energy physics at Harvard is summarized in a descriptive fashion according to the following outline: Proton endash antiproton colliding beam program at Fermilab -- CDF (forward/backward electromagnetic calorimeters -- FEM, central muon extension -- CMX, gas calorimetry and electronics development, front-end electronics upgrades, software development, physics analysis, timetable), electron -- positron collisions in the upsilon region -- CLEO (the hardware projects including CLEO II barrel TOF system and silicon drift detector R ampersand D, physics analysis), search for νμ to ντ oscillations with the NOMAD experiment at CERN, the solenoidal detector collaboration at the SSC, muon scattering at FNAL -- E665, the L3 experiment, and phenomenological analysis of high-energy bar pp cross sections. 149 refs

  7. A high energy physics perspective

    International Nuclear Information System (INIS)

    The status of the Standard model and role of symmetry in its development are reviewed. Some outstanding problems are surveyed and possible solutions in the form of additional open-quotes Hidden Symmetries close quotes are discussed. Experimental approaches to uncover open-quotes New Physicsclose quotes associated with those symmetries are described with emphasis on high energy colliders. An outlook for the future is given

  8. A high energy physics perspective

    Energy Technology Data Exchange (ETDEWEB)

    Marciano, W.J.

    1997-01-13

    The status of the Standard model and role of symmetry in its development are reviewed. Some outstanding problems are surveyed and possible solutions in the form of additional {open_quotes}Hidden Symmetries {close_quotes} are discussed. Experimental approaches to uncover {open_quotes}New Physics{close_quotes} associated with those symmetries are described with emphasis on high energy colliders. An outlook for the future is given.

  9. Cosmology for high energy physicists

    International Nuclear Information System (INIS)

    The standard big bang model of cosmology is presented. Although not perfect, its many successes make it a good starting point for most discussions of cosmology. Places are indicated where well understood laboratory physics is incorporated into the big bang, leading to successful predictions. Much less established aspects of high energy physics and some of the new ideas they have introduced into the field of cosmology are discussed, such as string theory, inflation and monopoles. 49 refs., 5 figs

  10. Future High Energy Neutrino Telescopes

    CERN Document Server

    Spiering, C

    2000-01-01

    This talk summarizes the main physics goals and basic methods of telescopes for high energy neutrinos. It reviews the present status of deep underwater telescopes and sketches the ICECUBE project as an example for a cube kilometer detector. It is suggested to develop techniques for radio and acoustic detection hand in hand with big optical arrays. These large arrays should be complemented by medium-size detectors in the Megaton range.

  11. [Research in high energy physics

    International Nuclear Information System (INIS)

    We review the efforts of the Notre Dame non accelerator high energy physics group. Our major effort has been directed toward the IMB deep underground detector. Since the departure of the Michigan group our responsibilities to the group have grown. We are also very active in pursuing physics with the IMB 3 detector. Currently we are studying proton decay, point neutrino sources and neutrino oscillations with the contained event sample

  12. The curious time lags of PG 1244+026: discovery of the iron K reverberation lag

    NARCIS (Netherlands)

    E. Kara; E.M. Cackett; A.C. Fabian; C. Reynolds; P. Uttley

    2014-01-01

    High-frequency iron K reverberation lags, where the red wing of the line responds before the line centroid, are a robust signature of relativistic reflection off the inner accretion disc. In this Letter, we report the discovery of the Fe K lag in PG 1244+026 from ∼120 ks of data (one orbit of the XM

  13. Quantum chromodynamics at high energy

    CERN Document Server

    Kovchegov, Yuri V

    2012-01-01

    Filling a gap in the current literature, this book is the first entirely dedicated to high energy QCD including parton saturation. It presents groundbreaking progress on the subject and describes many of the problems at the forefront of research, bringing postgraduate students, theorists and advanced experimentalists up to date with the current status of the field. A broad range of topics in high energy QCD are covered, most notably on the physics of parton saturation and the Color Glass Condensate (CGC). The material is presented in a pedagogical way, with numerous examples and exercises. Discussion ranges from the quasi-classical McLerran–Venugopalan model to the linear and non-linear BFKL/BK/JIMWLK small-x evolution equations. The authors adopt both a theoretical and experimental outlook and present the physics of strong interactions in a universal way, making it useful to physicists from various sub-communities and applicable to processes studied at high energy accelerators around the world.

  14. Astrophysics at very high energies

    International Nuclear Information System (INIS)

    Presents three complementary lectures on very-high-energy astrophysics given by worldwide leaders in the field. Reviews the recent advances in and prospects of gamma-ray astrophysics and of multi-messenger astronomy. Prepares readers for using space and ground-based gamma-ray observatories, as well as neutrino and other multi-messenger detectors. With the success of Cherenkov Astronomy and more recently with the launch of NASA's Fermi mission, very-high-energy astrophysics has undergone a revolution in the last years. This book provides three comprehensive and up-to-date reviews of the recent advances in gamma-ray astrophysics and of multi-messenger astronomy. Felix Aharonian and Charles Dermer address our current knowledge on the sources of GeV and TeV photons, gleaned from the precise measurements made by the new instrumentation. Lars Bergstroem presents the challenges and prospects of astro-particle physics with a particular emphasis on the detection of dark matter candidates. The topics covered by the 40th Saas-Fee Course present the capabilities of current instrumentation and the physics at play in sources of very-high-energy radiation to students and researchers alike. This book will encourage and prepare readers for using space and ground-based gamma-ray observatories, as well as neutrino and other multi-messenger detectors.

  15. High-energy atmospheric neutrinos

    CERN Document Server

    Sinegovsky, S I; Sinegovskaya, T S

    2010-01-01

    High-energy neutrinos, arising from decays of mesons that were produced through the cosmic rays collisions with air nuclei, form unavoidable background noise in the astrophysical neutrino detection problem. The atmospheric neutrino flux above 1 PeV should be supposedly dominated by the contribution of charmed particle decays. These (prompt) neutrinos originated from decays of massive and shortlived particles, $D^\\pm$, $D^0$, $\\bar{D}{}^0$, $D_s^\\pm$, $\\Lambda^+_c$, form the most uncertain fraction of the high-energy atmospheric neutrino flux because of poor explored processes of the charm production. Besides, an ambiguity in high-energy behavior of pion and especially kaon production cross sections for nucleon-nucleus collisions may affect essentially the calculated neutrino flux. There is the energy region where above flux uncertainties superimpose. A new calculation presented here reveals sizable differences, up to the factor of 1.8 above 1 TeV, in muon neutrino flux predictions obtained with usage of known...

  16. Jet Lag and Shift Work Disorder.

    Science.gov (United States)

    Reid, Kathryn J; Abbott, Sabra M

    2015-12-01

    Jet lag and shift work disorder are circadian rhythm sleep-wake disorders resulting from behaviorally altering the sleep-wake schedule in relation to the external environment. Not everyone who experiences trans-meridian travel or performs shift work has a disorder. The prevalence of jet lag disorder is unclear, approximately 5%-10% of shift workers have shift work disorder. Treatment aims to realign the internal circadian clock with the external environment. Behavioral therapies include sleep hygiene and management of the light-dark and sleep schedule. Pharmacologic agents are used to treat insomnia and excessive sleepiness, and melatonin is used to facilitate sleep and circadian realignment. PMID:26568127

  17. High Energy Laser for Space Debris Removal

    International Nuclear Information System (INIS)

    The National Ignition Facility (NIF) and Photon Science Directorate at Lawrence Livermore National Laboratory (LLNL) has substantial relevant experience in the construction of high energy lasers, and more recently in the development of advanced high average power solid state lasers. We are currently developing new concepts for advanced solid state laser drivers for the Laser Inertial Fusion Energy (LIFE) application, and other high average power laser applications that could become central technologies for use in space debris removal. The debris population most readily addressed by our laser technology is that of 0.1-10 cm sized debris in low earth orbit (LEO). In this application, a ground based laser system would engage an orbiting target and slow it down by ablating material from its surface which leads to reentry into the atmosphere, as proposed by NASA's ORION Project. The ORION concept of operations (CONOPS) is also described in general terms by Phipps. Key aspects of this approach include the need for high irradiance on target, 108 to 109 W/cm2, which favors short (i.e., picoseconds to nanoseconds) laser pulse durations and high energy per pulse (∼ > 10 kJ). Due to the target's orbital velocity, the potential duration of engagement is only of order 100 seconds, so a high pulse repetition rate is also essential. The laser technology needed for this application did not exist when ORION was first proposed, but today, a unique combination of emerging technologies could create a path to enable deployment in the near future. Our concepts for the laser system architecture are an extension of what was developed for the National Ignition Facility (NIF), combined with high repetition rate laser technology developed for Inertial Fusion Energy (IFE), and heat capacity laser technology developed for military applications. The 'front-end' seed pulse generator would be fiber-optics based, and would generate a temporally, and spectrally tailored pulse designed for high

  18. High Energy Laser for Space Debris Removal

    Energy Technology Data Exchange (ETDEWEB)

    Barty, C; Caird, J; Erlandson, A; Beach, R; Rubenchik, A

    2009-10-30

    The National Ignition Facility (NIF) and Photon Science Directorate at Lawrence Livermore National Laboratory (LLNL) has substantial relevant experience in the construction of high energy lasers, and more recently in the development of advanced high average power solid state lasers. We are currently developing new concepts for advanced solid state laser drivers for the Laser Inertial Fusion Energy (LIFE) application, and other high average power laser applications that could become central technologies for use in space debris removal. The debris population most readily addressed by our laser technology is that of 0.1-10 cm sized debris in low earth orbit (LEO). In this application, a ground based laser system would engage an orbiting target and slow it down by ablating material from its surface which leads to reentry into the atmosphere, as proposed by NASA's ORION Project. The ORION concept of operations (CONOPS) is also described in general terms by Phipps. Key aspects of this approach include the need for high irradiance on target, 10{sup 8} to 10{sup 9} W/cm{sup 2}, which favors short (i.e., picoseconds to nanoseconds) laser pulse durations and high energy per pulse ({approx} > 10 kJ). Due to the target's orbital velocity, the potential duration of engagement is only of order 100 seconds, so a high pulse repetition rate is also essential. The laser technology needed for this application did not exist when ORION was first proposed, but today, a unique combination of emerging technologies could create a path to enable deployment in the near future. Our concepts for the laser system architecture are an extension of what was developed for the National Ignition Facility (NIF), combined with high repetition rate laser technology developed for Inertial Fusion Energy (IFE), and heat capacity laser technology developed for military applications. The 'front-end' seed pulse generator would be fiber-optics based, and would generate a temporally, and

  19. A strategy to unveil transient sources of ultra-high-energy cosmic rays

    Directory of Open Access Journals (Sweden)

    Takami Hajime

    2013-06-01

    Full Text Available Transient generation of ultra-high-energy cosmic rays (UHECRs has been motivated from promising candidates of UHECR sources such as gamma-ray bursts, flares of active galactic nuclei, and newly born neutron stars and magnetars. Here we propose a strategy to unveil transient sources of UHECRs from UHECR experiments. We demonstrate that the rate of UHECR bursts and/or flares is related to the apparent number density of UHECR sources, which is the number density estimated on the assumption of steady sources, and the time-profile spread of the bursts produced by cosmic magnetic fields. The apparent number density strongly depends on UHECR energies under a given rate of the bursts, which becomes observational evidence of transient sources. It is saturated at the number density of host galaxies of UHECR sources. We also derive constraints on the UHECR burst rate and/or energy budget of UHECRs per source as a function of the apparent source number density by using models of cosmic magnetic fields. In order to obtain a precise constraint of the UHECR burst rate, high event statistics above ∼ 1020 eV for evaluating the apparent source number density at the highest energies and better knowledge on cosmic magnetic fields by future observations and/or simulations to better estimate the time-profile spread of UHECR bursts are required. The estimated rate allows us to constrain transient UHECR sources by being compared with the occurrence rates of known energetic transient phenomena.

  20. Lag space estimation in time series modelling

    DEFF Research Database (Denmark)

    Goutte, Cyril

    1997-01-01

    The purpose of this article is to investigate some techniques for finding the relevant lag-space, i.e. input information, for time series modelling. This is an important aspect of time series modelling, as it conditions the design of the model through the regressor vector a.k.a. the input layer...

  1. Weak interactions at high energies

    International Nuclear Information System (INIS)

    Review lectures are presented on the phenomenological implications of the modern spontaneously broken gauge theories of the weak and electromagnetic interactions, and some observations are made about which high energy experiments probe what aspects of gauge theories. Basic quantum chromodynamics phenomenology is covered including momentum dependent effective quark distributions, the transverse momentum cutoff, search for gluons as sources of hadron jets, the status and prospects for the spectroscopy of fundamental fermions and how fermions may be used to probe aspects of the weak and electromagnetic gauge theory, studies of intermediate vector bosons, and miscellaneous possibilities suggested by gauge theories from the Higgs bosons to speculations about proton decay. 187 references

  2. Simulation of High Energy Muons

    CERN Document Server

    Mashtakov, Konstantin

    2015-01-01

    Under the scope of a CERN summer student project, a Geant4 physical model has been developed and committed to the Geant4 repository to allow precise simulation of high-energy muons and hadrons transport inside a material. Resulted angular distributions produced by this model have small deviations from those that were obtained by the Geant4 model used by default. High-energetic muons energy losses inside the CMS tracker have also been estimated and may vary from 0.05% up to 2.5%.

  3. High energy ion beam mixing

    International Nuclear Information System (INIS)

    Experimental investigations have been made on the parameters which can be used to control the mixing profiles, and the width of intermixed layers in film-substrate systems being irradiated by high energy heavy ion beams. The samples were irradiated by ion beams of Au, Cu, and Si with energies of 1.5 to 3 MeV. Typical examples of the RBS spectra are presented and discussions are made on the extent of contribution of binary collisions on the interfacial mixing. The experimental and simulation results show that the interfacial mixing is dominated by the binary collisions. (author)

  4. High energy elastic hadron scattering

    International Nuclear Information System (INIS)

    The paper deals with the WA7 experiment at the CERN super proton synchrotron (SPS). The elastic differential cross sections of pion-proton, kaon-proton, antiproton-proton, and proton-proton at lower SPS energies over a wide range of momentum transfer were measured. Some theoretical models in the light of the experimental results are reviewed, and a comprehensive impact parameter analysis of antiproton-proton elastic scattering over a wide energy range is presented. A nucleon valence core model for high energy proton-proton and antiproton-proton elastic scattering is described

  5. High energy laser meteorology (HELMET)

    Science.gov (United States)

    Pries, Tom

    1990-05-01

    The present consideration of the atmospheric sensitivities of high-energy lasers intended for meteorological studies gives attention to the absorption effects of deuterium fluoride and CO2 lasers for several atmospheric gaseous species and aerosols, cloud and precipitation effects, and optical turbulence. Such nonlinear effects as thermal blooming and thermal shock waves are characterized, and the measurement characteristics of modulation transfer function devices, stellar scintillometers, isoplanometers, thermosondes, RF radars, FM-CW radars, molecular absorption/extinction lidars, wind lidars, and passive microwave temperature and humidity profilers, are presented for state-of-the-art devices.

  6. FERMI OBSERVATIONS OF HIGH-ENERGY GAMMA-RAY EMISSION FROM GRB 090217A

    International Nuclear Information System (INIS)

    The Fermi observatory is advancing our knowledge of gamma-ray bursts (GRBs) through pioneering observations at high energies, covering more than seven decades in energy with the two on-board detectors, the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM). Here, we report on the observation of the long GRB 090217A which triggered the GBM and has been detected by the LAT with a significance greater than 9σ. We present the GBM and LAT observations and on-ground analyses, including the time-resolved spectra and the study of the temporal profile from 8 keV up to ∼1 GeV. All spectra are well reproduced by a Band model. We compare these observations to the first two LAT-detected, long bursts GRB 080825C and GRB 080916C. These bursts were found to have time-dependent spectra and exhibited a delayed onset of the high-energy emission, which are not observed in the case of GRB 090217A. We discuss some theoretical implications for the high-energy emission of GRBs.

  7. High energy physics and cosmology

    International Nuclear Information System (INIS)

    This research will focus on the implications of recent theories and experiments in high energy physics of the evolution of the early universe, and on the constraints that cosmological considerations can place on such theories. Several problems are under investigation, including studies of the nature of dark matter and the signature of annihilations in the galactic halo, where the resulting γ-ray fluxes are potentially observable, and in stars, where stellar evolution may be affects. We will develop constraints on the inflationary predictions of scale-free primordial fluctuations in a universe at critical closure density by studying their linear and non-linear evolution after they re-enter the particle horizon, examining the observable imprint of primordial density fluctuations on the cosmic microwave background radiation in both flat and curved cosmological models, and implications for observations of large-scale galaxy clustering and structure formation theories. We will also study spectral distortions in the microwave background radiation that are produced by exotic particle decays in the very early universe. We expect such astrophysical considerations to provide fruitful insights both into high-energy particle physics and into possible cosmological for the early universe

  8. Duke University High Energy Physics

    International Nuclear Information System (INIS)

    The research program of the Duke High Energy Physics Group is described in this Progress Report and a separate Proposal containing their plans for 1994. These two documents are supplemented by compilations of selected publications, thesis abstracts, and the curriculum vitae of the eleven Ph.D. physicists who are carrying out this research program. This Progress Report contains a review of the research which has been done over the first half (1992 and 1993 to date) of the current three-year DOE grant, plus some earlier research to establish a broader perspective of the research interests. High energy physics research at Duke has three components. The first, Task A, is based upon experiments carried out at Fermilab's Tevatron Collider. The group is finishing the analysis of data from their first collider experiment (E735), a study of inclusive particle production from bar p p collisions at √ bar s = 1.8 TeV. The second component of the research, Task B, deals primarily with heavy flavor physics. The third part of the research program, Task D, deals with preparation for research at the SSC. The authors have been active in the development of tracking detectors for the SSC since 1989, and are now concentrating on the design and construction of straw tube drift chambers for the solenoid detector

  9. Approaches to high energy physics

    International Nuclear Information System (INIS)

    An overview of the present state of the art in high energy physics is presented highlighting the developments in hadron physics, field theory and nuclear democracy. To begin with, description of 'hadrons' is given on the basis of quantum electrodynamics. The role of the quantum numbers assigned to quarks are explained. Lepton-hadron scattering and hadron-hadron scattering are discussed. The quark-parton model of the nucleon is explained. The recently discovered Psi resonances and the consequent introduction of new quantum number 'charm' are mentioned. Next, Yang-Mills Gauge theories, the unification of weak and electromagnetic interactions and the concept of weak neutral currents are discussed. Gauge theories of strong interactions, quantum chromodynamics and the concept of 'Bags' are explained. Magnetic monopoles (solitons) are described with basis on non-linear field theories. High energy bounds in the axiomatic field theory are formulated. The general properties of S-matrix elements obtained in a quantum local field theory are mentioned. Lastly, the shifting of the reliance on field concepts to other approaches, specially through S-matrix and the application of Regge poles and cuts is explained. The duality hypothesis is postulated to explain processes such as pp→pp with the 'pomeron exchange' concept. Dual models of strong interactions are discussed. Future trends are indicated. (A.K.)

  10. Gamma Ray Bursts in the HAWC Era

    CERN Document Server

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

    2015-01-01

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

  11. Defining, modeling, and measuring system lag in virtual environments

    Science.gov (United States)

    Bryson, Steve; Fisher, Scott S.

    1990-01-01

    In such real-time interactive computer environments as those used for virtual environments and simulators, system lag dramatically affects system usability. Attention is presently given to two types of lag: (1) transmission lag time, which is the difference between the moving of a sensing device and that device's motion on a graphic display, and (2) position lag, which is the difference between the actual position of a tracker in motion and the displayed position of a tracker at the same time. A method for measuring these types of lag using a video technique was developed for the NASA-Ames Virtual Interactive Environment Workstation. The position lag can be understood in terms of the transmission lag, so that optimizing a system for small transmission lag will also optimize for small position lag.

  12. The prompt GRB high energy emission from internal shocks: synchrotron vs inverse Compton component

    International Nuclear Information System (INIS)

    We performed a detailed calculation of gamma-ray burst (GRB) prompt emission in the framework of the internal shock scenario, focusing on the high energy (GeV) bands. In order to follow the evolution of the ultrarelativistic inhomogeneous wind, we combined a model for the dynamics of internal shocks with a detailed calculation of the radiative processes occurring in the shocked medium. We present the resulting synthetic GRB light curves and spectra. We show the spectral evolution that can be expected for different sets of microphysics parameters and parameters of the dynamical evolution, and how the relative importance of synchrotron and inverse Compton components is varying during a burst.

  13. High energy particle experiment for the GEOTAIL mission

    International Nuclear Information System (INIS)

    The high energy particle experiment for GEOTAIL mission was designed to understand the particle acceleration mechanism, energy flow, boundary dynamics and magnetic reconnection mechanism in the geotail region, solar flare particle acceleration mechanism, the propagation mechanism through interplanetary space, and the origin, lifetime and propagation mechanism of cosmic ray heavy ions. In order to achieve these objectives, particle detectors, burst detectors, medium energy isotope telescopes and a high energy isotope telescope will be placed in the spacecraft which will be launched in 1992 as one of the spacecraft missions in the International Solar Terrestrial Physics program. With these detectors, electrons, protons and helium, carbon, silicon and iron particles will be detected. The characteristics and the main technique used for each instrument to observe high energy particles are summarized. The details of the scientific objectives, the basic principle of particle identification, the electronic system and data processing system, key parameter information, telemetry data formats, preflight and in-flight calibration method and data an analysis plan are described in this report. (K.I.)

  14. Temporal Shaping of High Peak Power Pulse Trains from a Burst-Mode Laser System

    Directory of Open Access Journals (Sweden)

    Jörg Körner

    2015-12-01

    Full Text Available It has been shown in the past that pulsed laser systems operating in the so-called “burst mode” are a beneficial approach to generate high peak power laser pulses at high repetition rates suitable for various applications. So far, most high-energy burst-mode laser systems put great effort into generating a homogeneous energy distribution across the burst duration, e.g., by shaping the pump pulse. In this work, we present a new shaping technique, which is able to produce arbitrary energy distributions within the burst by pre-shaping the seed pulse burst with a Pockels cell. Furthermore, this technique allows for the precompensation of any static modulations across the burst, which may be introduced during the subsequent amplification process. Therefore, a pulse burst with a uniform energy distribution can also be generated. The method is tested with an ultra-short pulse burst mode laser amplifier system producing bursts of a 1 ms duration with a pulse repetition rate of 1 MHz and a maximum output power of 800 W during the burst. Furthermore, a method to predict the influence of the amplifier on a non-uniformly shaped burst is presented and successfully tested to produce a pre-defined pulse shape after amplification.

  15. Multiplicities in high energy interactions

    International Nuclear Information System (INIS)

    This paper reviews the data on multiplicities in high energy interactions. Results from e+e- annihilation, from neutrino interactions, and from hadronic collisions, both diffractive and nondiffractive, are compared and contrasted. The energy dependence of the mean charged multiplicity, , as well as the rapidity density at Y = 0 are presented. For hadronic collisions, the data on neutral pion production shows a strong correlation with . The heavy particle fractions increase with √s up to the highest energies. The charged particle multiplicity distributions for each type of reaction show a scaling behavior when expressed in terms of the mean. Attempts to understand this behavior, which was first predicted by Koba, Nielsen, and Olesen, are discussed. The multiplicity correlations and the energy variation of the shape of the KNO scaling distribution provide important constraints on models. Some extrapolations to the energies of the Superconducting Super Collider are made. 51 refs., 27 figs

  16. High-energy atomic physics

    CERN Document Server

    Drukarev, Evgeny G

    2016-01-01

    This self-contained text introduces readers to the field of high-energy atomic physics - a new regime of photon-atom interactions in which the photon energies significantly exceed the atomic or molecular binding energies, and which opened up with the recent advent of new synchrotron sources. From a theoretical point of view, a small-parameter characteristic of the bound system emerged, making it possible to perform analytic perturbative calculations that can in turn serve as benchmarks for more powerful numerical computations. The first part of the book introduces readers to the foundations of this new regime and its theoretical treatment. In particular, the validity of the small-parameter perturbation expansion and of the lowest-order approximation is critically reviewed. The following chapters then apply these insights to various atomic processes, such as photoionization as a many-body problem, dominant mechanisms for the production of ions at higher energies, Compton scattering and ionization accompanied b...

  17. Developments in high energy theory

    Indian Academy of Sciences (India)

    Sunil Mukhi; Probir Roy

    2009-07-01

    This non-technical review article is aimed at readers with some physics back-ground, including beginning research students. It provides a panoramic view of the main theoretical developments in high energy physics since its inception more than half a century ago, a period in which experiments have spanned an enormous range of energies, theories have been developed leading up to the Standard Model, and proposals – including the radical paradigm of String Theory – have been made to go beyond the Standard Model. The list of references provided here is not intended to properly credit all original work but rather to supply the reader with a few pointers to the literature, specifically highlighting work done by Indian authors.

  18. Oxides having high energy densities

    Science.gov (United States)

    Ceder, Gerbrand; Kang, Kisuk

    2013-09-10

    Certain disclosed embodiments generally relate to oxide materials having relatively high energy and/or power densities. Various aspects of the embodiments are directed to oxide materials having a structure B.sub.i(M.sub.jY.sub.k)O.sub.2, for example, a structure Li.sub.j(Ni.sub.jY.sub.k)O.sub.2 such as Li(Ni.sub.0.5Mn.sub.0.5)O.sub.2. In this structure, Y represents one or more atoms, each independently selected from the group consisting of alkaline earth metals, transition metals, Group 14 elements, Group 15, or Group 16 elements. In some embodiments, such an oxide material may have an O3 crystal structure, and/or a layered structure such that the oxide comprises a plurality of first, repeating atomic planes comprising Li, and a plurality of second, repeating atomic planes comprising Ni and/or Y.

  19. High Energy Gas Fracturing Test

    Energy Technology Data Exchange (ETDEWEB)

    Schulte, R.

    2001-02-27

    The Rocky Mountain Oilfield Testing Center (RMOTC) has recently completed two tests of a high-energy gas fracturing system being developed by Western Technologies of Crossville, Tennessee. The tests involved the use of two active wells located at the Naval Petroleum Reserve No. 3 (NPR-3), thirty-five miles north of Casper, Wyoming (See Figure 1). During the testing process the delivery and operational system was enhanced by RMOTC, Western Technologies, and commercial wireline subcontractors. RMOTC has assisted an industrial client in developing their technology for high energy gas fracturing to a commercial level. The modifications and improvements implemented during the technology testing process are instrumental in all field testing efforts at RMOTC. The importance of well selection can also be critical in demonstrating the success of the technology. To date, significant increases in well productivity have been clearly proven in well 63-TPX-10. Gross fluid production was initially raised by a factor of three. Final production rates increased by a factor of six with the use of a larger submersible pump. Well productivity (bbls of fluid per foot of drawdown) increased by a factor of 15 to 20. The above results assume that no mechanical damage has occurred to the casing or cast iron bridge plug which could allow well production from the Tensleep ''B'' sand. In the case of well 61-A-3, a six-fold increase in total fluid production was seen. Unfortunately, the increase is clouded by the water injection into the well that was necessary to have a positive fluid head on the propellant tool. No significant increase in oil production was seen. The tools which were retrieved from both 63-TPX-10 and 61-A-3 indicated a large amount of energy, similar to high gram perforating, had been expended downhole upon the formation face.

  20. The curious time lags of PG 1244+026: Discovery of the iron K reverberation lag

    CERN Document Server

    Kara, E; Fabian, A C; Reynolds, C; Uttley, P

    2013-01-01

    High-frequency iron K reverberation lags, where the red wing of the line responds before the line centroid, are a robust signature of relativistic reflection off the inner accretion disc. In this letter, we report the discovery of the Fe K lag in PG 1244+026 from ~120 ks of data (1 orbit of the XMM-Newton telescope). The amplitude of the lag with respect to the continuum is 1000 s at a frequency of ~1e-4 Hz. We also find a possible frequency-dependence of the line: as we probe higher frequencies (i.e. shorter timescales from a smaller emitting region) the Fe K lag peaks at the red wing of the line, while at lower frequencies (from a larger emitting region) we see the dominant reflection lag from the rest frame line centroid. The mean energy spectrum shows a strong soft excess, though interestingly, there is no indication of a soft lag. Given that this source has radio emission and it has little reported correlated variability between the soft excess and the hard band, we explore one possible explanation in wh...

  1. Magnetized galactic halos and velocity lags

    CERN Document Server

    Henriksen, Richard N

    2016-01-01

    We present an analytic model of a magnetized galactic halo surrounding a Mestel gravitating disc. The magnetic field is taken to be in energy equipartition with the pressure dominant rotating halo gas ({\\it not} with the cosmic rays), and the whole system is in a steady state. A more flexible `anisotropic equipartition' model is also explored. A definite pressure law is required to maintain the equilibrium, but the halo density is constant. The velocity/magnetic system is scale-free. The objective is to find the rotational velocity lag in such a halo. The magnetic field is not force-free so that angular momentum may be transported from the halo to the intergalactic medium. We find that the `X'-shaped structure observed for halo magnetic fields can be obtained together with a simple analytic formula for the rate of decline of the velocity with height $z$. The formula also predicts the change in lag with radius, $r$.

  2. Magnetized galactic haloes and velocity lags

    Science.gov (United States)

    Henriksen, R. N.; Irwin, J. A.

    2016-06-01

    We present an analytic model of a magnetized galactic halo surrounding a Mestel gravitating disc. The magnetic field is taken to be in energy equipartition with the pressure dominant rotating halo gas (not with the cosmic rays), and the whole system is in a steady state. A more flexible `anisotropic equipartition' model is also explored. A definite pressure law is required to maintain the equilibrium, but the halo density is constant. The velocity/magnetic system is scale-free. The objective is to find the rotational velocity lag in such a halo. The magnetic field is not force-free so that angular momentum may be transported from the halo to the intergalactic medium. We find that the `X'-shaped structure observed for halo magnetic fields can be obtained together with a simple analytic formula for the rate of decline of the velocity with height z. The formula also predicts the change in lag with radius, r.

  3. IV. Workshop on High Energy Spin Physics

    International Nuclear Information System (INIS)

    In this proceedings the results on high energy spin physics are summarized. The theory of spin phenomenon and the experimental results at intermediate energy and at high energy spin physics and new technical developments in polarization experiments are presented

  4. Lasers and future high energy colliders

    International Nuclear Information System (INIS)

    Future high energy colliders, directions for particle physics and relationship to new technology such as lasers are discussed. Experimental approaches to explore New Physics with emphasis on the utility of high energy colliders are also discussed

  5. Pakistan lags behind in technical textile

    OpenAIRE

    JANJHJI, NOOR ZAMAN; MEMON, NOOR AHMED

    2007-01-01

    This paper highlights and demonstrates the technical and economical impact of technical textiles in the industrially developed countries and their future contribution to the development of economics of newly developing countries, such as China, South East Asia, and North Africa etc. Pakistan still lags behind in technical textile products as neither the government nor the textile industry has made any serious efforts towards synchronizing textile products with the emerging n...

  6. Lagged Syndesmotic Fixation: Our Clinical Experience.

    Science.gov (United States)

    Kwaadu, Kwasi Yiadom; Fleming, Justin James; Salmon, Trudy

    2015-01-01

    Ankle fractures are very common, and although algorithms are in place for osseous management, consensus has not been reached regarding treatment of associated ligamentous injuries. Although tibiofibular syndesmotic stabilization can be done using different forms of fixation, the biomedical literature has long emphasized the risk of long-term restriction of ankle mobility with the use of lagged transfixation. However, when reduction cannot be maintained with positional fixation, we found that lagging the syndesmotic screw helped to maintain the reduction without causing functional restriction. In this report, we describe our experience with patients who had undergone lagged tibiofibular transfixation and were available for short- to intermediate-term follow-up to assess ankle function. A total of 31 patients (32.63% of 95 consecutive patients) were available at a mean of 34.87 (range 18 to 52) months to complete the American Orthopedic Foot and Ankle Society ankle-hindfoot questionnaire. The mean score was 88.38 (range 42 to 100) points at a mean follow-up interval of 34.87 (range 18 to 52) months. Of 31 patients, 19 had an AOFAS score of 90 points, 9 an AOFAS score of 80 to 89 points, 2 an AOFAS score of 60 to 69 points, and 1 an AOFAS score of ankle kinematics than positional syndesmotic fixation. PMID:25736445

  7. Interplanetary Type IV Bursts

    CERN Document Server

    Hillaris, Alexander; Nindos, Alexander

    2016-01-01

    In this work we study the characteristics of moving type IV radio bursts which extend to the hectometric wavelengths (interplanetary type IV or type IV IP bursts) and their relationship with energetic phenomena on the Sun. Our dataset comprised 48 Interplanetary type IV bursts observed by the Wind/WAVES in the 13.825 MHz?20 KHz frequency range. The dynamic spec tra of the RSTN, DAM, ARTEMIS-IV, CULGOORA, Hiraiso and IZMIRAN Radio-spectrographs were used to track the evolution of the events in the low corona; these were supplemented with SXR ?ux recordings from GOES and CME data from LASCO. Positional information for the coronal bursts were obtained by the Nan\\c{c}ay radioheliograph (NRH). We examined the relationship of the type IV events with coronal radio bursts, CMEs and SXR ?ares. The majority of the events (45) were characterized as compact; their duration was on average 106 min. This type of events were, mostly, associated with M and X class ?ares (40 out of 45) and fast CMEs; 32 of these events had CME...

  8. Estimating Redshifts for Long Gamma-Ray Bursts

    CERN Document Server

    Xiao, Limin

    2009-01-01

    We are constructing a program to estimate the redshifts for GRBs from the original Swift light curves and spectra, aiming to get redshifts for the Swift bursts \\textit{without} spectroscopic or photometric redshifts. We derive the luminosity indicators from the light curves and spectra of each burst, including the lag time between low and high photon energy light curves, the variability of the light curve, the peak energy of the spectrum, the number of peaks in the light curve, and the minimum rise time of the peaks. These luminosity indicators can each be related directly to the luminosity, and we combine their independent luminosities into one weighted average. Then with our combined luminosity value, the observed burst peak brightness, and the concordance redshift-distance relation, we can derive the redshift for each burst. In this paper, we test the accuracy of our method on 107 bursts with known spectroscopic redshift. The reduced $\\chi^2$ of our best redshifts ($z_{best}$) compared with known spectrosc...

  9. High Energy Plasma Space Propulsion

    Science.gov (United States)

    Wu, S. T.

    2000-01-01

    In order to meet NASA's challenge on advanced concept activity in the propulsion area, we initiated a new program entitled "High Energy Plasma Space Propulsion Studies" within the current cooperative agreement in 1998. The goals of this work are to gain further understanding of the engine of the AIMStar spacecraft, a concept which was developed at Penn State University, and to develop a prototype concept for the engine. The AIMStar engine concept was developed at Penn State University several years ago as a hybrid between antimatter and fusion technologies. Because of limited amounts of antimatter available, and concurrently the demonstrated ability for antiprotons to efficiently ignite nuclear fusion reactions, it was felt that this was a very good match. Investigations have been made concerning the performance of the reaction trap. This is a small Penning-like electromagnetic trap, which is used to simultaneously confine antiprotons and fusion fuels. Small DHe3 or DT droplets, containing a few percent molar of a fissile material, are injected into the trap, filled with antiprotons. We have found that it is important to separate the antiprotons into two adjacent wells, to inject he droplet between them and to simultaneously bring the antiprotons to the center of the trap, surrounding the droplet. Our previous concept had the droplet falling onto one cloud of antiprotons. This proved to be inefficient, as the droplet tended to evaporate away from the cloud as it interacted on its surface.

  10. Supercollapsars and their X-ray Bursts

    CERN Document Server

    Komissarov, S S

    2009-01-01

    The very first stars in the Universe can be very massive, frequently reaching $10^3M_\\odot$. If born in large numbers such massive stars can have strong impact on the subsequent star formation producing strong ionising radiation and contaminating the primordial gas with heavy elements. They would leave behind massive black holes that could act as seeds for growing supermassive black holes of active galactic nuclei. Given the anticipated fast rotation such stars would end their live as supermassive collapsars and drive powerful magnetically-dominated jets. In this letter we investigate the possibility of observing the bursts of high-energy emission similar to the Long Gamma Ray Bursts associated with normal collapsars. We show that during the collapse of supercollapsars, the Blandford-Znajek mechanism can extract up to $10^{56}$erg at a rate of few$\\times10^{52}$erg/s. Due to the higher intrinsic time scale and higher redshift the observed burst duration increases by a factor of $\\simeq 1000$ and can reach one...

  11. Neutrinos from Gamma Ray Bursts

    CERN Document Server

    Mannheim, K

    2000-01-01

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

  12. Interplanetary Type IV Bursts

    Science.gov (United States)

    Hillaris, A.; Bouratzis, C.; Nindos, A.

    2016-08-01

    We study the characteristics of moving type IV radio bursts that extend to hectometric wavelengths (interplanetary type IV or type {IV}_{{IP}} bursts) and their relationship with energetic phenomena on the Sun. Our dataset comprises 48 interplanetary type IV bursts observed with the Radio and Plasma Wave Investigation (WAVES) instrument onboard Wind in the 13.825 MHz - 20 kHz frequency range. The dynamic spectra of the Radio Solar Telescope Network (RSTN), the Nançay Decametric Array (DAM), the Appareil de Routine pour le Traitement et l' Enregistrement Magnetique de l' Information Spectral (ARTEMIS-IV), the Culgoora, Hiraso, and the Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) Radio Spectrographs were used to track the evolution of the events in the low corona. These were supplemented with soft X-ray (SXR) flux-measurements from the Geostationary Operational Environmental Satellite (GOES) and coronal mass ejections (CME) data from the Large Angle and Spectroscopic Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO). Positional information of the coronal bursts was obtained by the Nançay Radioheliograph (NRH). We examined the relationship of the type IV events with coronal radio bursts, CMEs, and SXR flares. The majority of the events (45) were characterized as compact, their duration was on average 106 minutes. This type of events was, mostly, associated with M- and X-class flares (40 out of 45) and fast CMEs, 32 of these events had CMEs faster than 1000 km s^{-1}. Furthermore, in 43 compact events the CME was possibly subjected to reduced aerodynamic drag as it was propagating in the wake of a previous CME. A minority (three) of long-lived type {IV}_{{IP}} bursts was detected, with durations from 960 minutes to 115 hours. These events are referred to as extended or long duration and appear to replenish their energetic electron content, possibly from electrons escaping from the corresponding coronal

  13. Potentially lethal effects of astrophysical high energy explosive events

    International Nuclear Information System (INIS)

    In this work we compare the biological extinction risks posed by different types of high energy explosive events, if they occur at distances close enough to inhabited planets. These events are several kinds of supernovae and gamma ray bursts. We mainly consider the ozone depletion, leaving other effects, as photon retransmission and muon showers, for future work. In order to estimate the damage on ozonosphere, we use a simple analytical model for ozone depletion. We also mention some hints to look for the signatures of these events on Earth biogeochemical record, and evaluate the possibility of applying these results to the astrobiologically interesting sample of stars gathered by Porto de Mello, del Peloso and Ghezzi. (Author)

  14. Size distributions of air showers accompanied with high energy gamma ray bundles observed at Mt. Chacaltaya

    Science.gov (United States)

    Matano, T.; Machida, M.; Tsuchima, I.; Kawasumi, N.; Honda, K.; Hashimoto, K.; Martinic, N.; Zapata, J.; Navia, C. E.; Aquirre, C.

    1985-01-01

    Size distributions of air showers accompanied with bundle of high energy gamma rays and/or large size bursts under emulsion chambers, to study the composition of primary cosmic rays and also characteristics of high energy nuclear interaction. Air showers initiated by particles with a large cross section of interaction may develop from narrow region of the atmosphere near the top. Starting levels of air showers by particles with smaller cross section fluctuate in wider region of the atmosphere. Air showers of extremely small size accompanied with bundle of gamma rays may be ones initiated by protons at lower level after penetrating deep atmosphere without interaction. It is determined that the relative size distribution according to the total energy of bundle of gamma rays and the total burst size observed under 15 cm lead absorber.

  15. Search for Very High Energy Emission from Satellite-triggered GRBs with the Milagro Observatory

    CERN Document Server

    Parkinson, P M S; Atkins, R; Benbow, W; Berley, D; Blaufuss, E; Coyne, D G; De Young, T R; Dingus, B L; Dorfan, D E; Ellsworth, R W; Fleysher, L; Gisler, G; González, M M; Goodman, J A; Haines, T J; Hays, E; Hoffman, C M; Kelley, L A; Lansdell, C P; Linnemann, J T; McEnery, J E; Miller, R S; Mincer, A I; Morales, M F; Némethy, P; Noyes, D; Ryan, J M; Samuelson, F W; Saz-Parkinson, P M; Shoup, A; Sinnis, G; Smith, A J; Sullivan, G W; Williams, D A; Wilson, M E; Xu, X W; Yodh, G B

    2005-01-01

    The Milagro gamma-ray observatory employs a water Cherenkov detector to observe extensive air showers produced by high energy particles interacting in the Earth's atmosphere. Milagro has a wide field of view (2 sr) and high duty cycle (> 90%) making it an ideal all-sky monitor of the northern hemisphere in the 100 GeV to 100 TeV energy range. More than 45 satellite-triggered gamma-ray bursts (GRBs) have occurred in the field of view of Milagro since January 2000, with the rate of bursts increasing significantly with the launch of Swift. We discuss the most recent results of a search for very high energy (VHE) emission from these GRBs.

  16. Fermi Observations of High-Energy Gamma-Ray Emission from GRB 080916C

    International Nuclear Information System (INIS)

    Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gamma-ray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy release yet measured. The high-energy gamma rays are observed to start later and persist longer than the lower energy photons. A simple spectral form fits the entire GRB spectrum, providing strong constraints on emission models. The known distance of the burst enables placing lower limits on the bulk Lorentz factor of the outflow and on the quantum gravity mass. (authors)

  17. Fermi Observations of high-energy gamma-ray emissions from GRB 080916C

    CERN Document Server

    Abdo, A A; Arimoto, M; Asano, K; Atwood, W B; Axelsson, M; Baldini, L; Ballet, J; Band, D L; Barbiellini, Guido; Baring, Matthew G; Bastieri, Denis; Battelino, M; Baughman, B M; Bechtol, K; Bellardi, F; Bellazzini, R; Berenji, B; Bhat, P N; Bissaldi, E; Blandford, R D; Bloom, Elliott D; Bogaert, G; Bogart, J R; Bonamente, E; Bonnell, J; Borgland, A W; Bouvier, A; Bregeon, J; Brez, A; Briggs, M S; Brigida, M; Bruel, P; Burnett, Thompson H; Burrows, David N; Busetto, Giovanni; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Ceccanti, M; Cecchi, C; Celotti, Annalisa; Charles, E; Chekhtman, A; Cheung, C.C.Teddy; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, Johann; Cominsky, Lynn R; Connaughton, V; Conrad, J; Costamante, L; Cutini, S; DeKlotz, M; Dermer, C D; De Angelis, Alessandro; de Palma, F; Digel, S W; Dingus, B L; do Couto e Silva, Eduardo; Drell, P S; Dubois, R; Dumora, D; Edmonds, Y; Evans, P A; Fabiani, D; Farnier, C; Favuzzi, C; Finke, Justin D; Fishman, G; Focke, W B; Frailis, M; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giebels, B; Giglietto, N; Giommi, P; Giordano, F; Glanzman, Thomas Lynn; Godfrey, Gary L; Goldstein, A; Granot, J; Greiner, J; Grenier, I A; Grondin, M H; Grove, J.Eric; Guillemot, L; Guiriec, S; Haller, G; Hanabata, Y; Harding, Alice K; Hayashida, M; Hays, Elizabeth A; Hernando Morata, J A; Hoover, A; Hughes, R E; Johannesson, G; Johnson, A S; Johnson, R P; Johnson, T J; Johnson, W N; Kamae, Tsuneyoshi; Katagiri, H; Kataoka, J; Kavelaars, A; Kawai, N; Kelly, H; Kennea, J; Kerr, M; Kippen, R M; Knodlseder, J; Kocevski, D; Kocian, M L; Komin, N; Kouveliotou, C; Kuehn, Frederick Gabriel Ivar; Kuss, Michael; Lande, J; Landriu, D; Larsson, S; Latronico, L; Lavalley, C; Lee, B; Lee, S H; Lemoine-Goumard, M; Lichti, G G; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, Pasquale; Madejski, G M; Makeev, A; Marangelli, B; Mazziotta, M N; McBreen, Sheila; McEnery, J E; McGlynn, S; Meegan, C; Miszaros, P; Meurer, C; Michelson, P F; Minuti, M; Mirizzi, N; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Moretti, E; Morselli, A; Moskalenko, Igor Vladimirovich; Murgia, Simona; Nakamori, T; Nelson, D; Nolan, P L; Norris, J P; Nuss, E; Ohno, M; Ohsugi, Takashi; Okumura, Akira; Omodei, N; Orlando, E; Ormes, J F; Ozaki, M; Paciesas, W S; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Perri, M; Pesce-Rollins, M; Petrosian, Vahe; Pinchera, M; Piron, F; Porter, Troy A; Preece, R; Rainr, S; Ramirez-Ruiz, E; Rando, R; Rapposelli, E; Razzano, M; Razzaque, Soebur; Rea, N; Reimer, A; Reimer, O; Reposeur, Thierry; Reyes, Luis C; Ritz, S; Rochester, L S; Rodriguez, A Y; Roth, M; Ryde, F; Sadrozinski, H F W; Sanchez, D; Sander, A; Parkinson, P.M.Saz; Scargle, J D; Schalk, T L; Segal, K N; Sgro, C; Shimokawabe, T; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Stamatikos, M; Starck, Jean-Luc; Stecker, Floyd William; Steinle, H; Stephens, T E; Strickman, M S; Suson, Daniel J; Tagliaferri, G.; Tajima, Hiroyasu; Takahashi, H; Takahashi, T; Tanaka, T; Tenze, A; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, Diego F; Tosti, G; Tramacere, A; Turri, M; Tuvi, S; Usher, T L; van der Horst, A J; Vigiani, L; Vilchez, N; Vitale, V; von Kienlin, A; Waite, A P; Williams, D A; Wilson-Hodge, C; Winer, B L; Wood, K S; Wu, X F; Yamazaki, R; Ylinen, T; Ziegler, M

    2009-01-01

    Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gammaray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy release yet measured. The high-energy gamma rays are observed to start later and persist longer than the lower energy photons. A simple spectral form fits the entire GRB spectrum, providing strong constraints on emission models. The known distance of the burst enables placing lower limits on the bulk Lorentz factor of the outflow and on the quantum gravity mass.

  18. A Repeating Fast Radio Burst

    CERN Document Server

    Spitler, L G; Hessels, J W T; Bogdanov, S; Brazier, A; Camilo, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J; Ferdman, R D; Freire, P C C; Kaspi, V M; Lazarus, P; Lynch, R; Madsen, E C; McLaughlin, M A; Patel, C; Ransom, S M; Seymour, A; Stairs, I H; Stappers, B W; van Leeuwen, J; Zhu, W W

    2016-01-01

    Fast Radio Bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find additional bursts at the same dispersion measures (i.e. integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of the fast radio bursts has led several authors to hypothesise that they originate in cataclysmic astrophysical events. Here we report the detection of ten additional bursts from the direction of FRB121102, using the 305-m Arecibo telescope. These new bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and wh...

  19. High energy beam manufacturing technologies

    International Nuclear Information System (INIS)

    Technological progress continues to enable us to utilize ever widening ranges of physical and chemical conditions for material processing. The increasing cost of energy, raw materials and environmental control make implementation of advanced technologies inevitable. One of the principal avenues in the development of material processing is the increase of the intensity, accuracy, flexibility and stability of energy flow to the processing site. The use of different forms of energy beams is an effective way to meet these sometimes incompatible requirements. The first important technological applications of high energy beams were welding and flame cutting. Subsequently a number of different kinds of beams have been used to solve different problems of part geometry control and improvement of surface characteristics. Properties and applications of different specific beams were subjects of a number of fundamental studies. It is important now to develop a generic theory of beam based manufacturing. The creation of a theory dealing with general principles of beam generation and beam-material interaction will enhance manufacturing science as well as practice. For example, such a theory will provide a format approach for selection and integration of different kinds of beams for a particular application. And obviously, this theory will enable us to integrate the knowledge bases of different manufacturing technologies. The War of the Worlds by H. G. Wells, as well as a number of more technical, although less exciting, publications demonstrate both the feasibility and effectiveness of the generic approach to the description of beam oriented technology. Without any attempt to compete with Wells, we still hope that this volume will contribute to the creation of the theory of beam oriented manufacturing

  20. High energy physics and cosmology

    International Nuclear Information System (INIS)

    This research will focus on the implications of recent theories and experiments in high energy physics for the evolution of the early Universe, and on the constraints that cosmological considerations can place on such theories. Several problems are under investigation, including the development of constraints on the inflationary predictions of scale--free primordial fluctuations in a universe at critical closure density by studying their linear and non-linear evolution after they re-enter the particle horizon. We will examine the observable imprint of primordial density fluctuations on the cosmic microwave background radiation curved cosmological models. Most astronomical evidence points to an open universe: one of our goals is to reconcile this conclusion with the particle physics input. We will investigate the response of the matter distribution to a network of cosmic strings produced during an early symmetry-breaking transition, and compute the resulting cosmic microwave background anisotropies. We will simulate the formation of large-scale structures whose dynamics are dominated by weakly interacting particles such as axions, massive neutrinos or photinos in order to model the formation of galaxies, galaxy clusters and superclusters. We will study of the distortions in the microwave background radiation, both spectral and angular, that are produced by ionized gas associated with forming clusters and groups of galaxies. We will also study constraints on exotic cooling mechanisms involving axions and majorons set by stellar evolution and the energy input into low mass stars by cold dark matter annihilation galactic nuclei. We will compute the detailed gamma ray spectrum predicted by various cold dark matter candidates undergoing annihilation in the galactic halo and bulge

  1. [High energy physics and cosmology

    International Nuclear Information System (INIS)

    This research will focus on the implications of recent theories and experiments in high energy physics for the evolution of the early Universe, and on the constraints that cosmological considerations can place on such theories. Several problems are under investigation, including the development of constraints on the inflationary predictions of scale-free primordial fluctuations in a universe at critical closure density by studying their linear and non-linear evolution after they re-enter the particle horizon. We will examine the observable imprint of primordial density fluctuations on the cosmic microwave background radiation in curved cosmological models. Most astronomical evidence points to an open universe: one of our goals is to reconcile this conclusion with the particle physics input. We will investigate the response of the matter distribution to a network of cosmic strings produced during an early symmetry--breaking transition, and compute the resulting cosmic microwave background anisotropies. We will simulate the formation of large--scale structures whose dynamics are dominated by weakly interacting particles such as axions massive neutrinos or photinos in order to model the formation of galaxies, galaxy clusters and superclusters. We will study the distortions in the microwave background radiation, both spectral and angular, that are produced by ionized gas associated with forming clusters and groups of galaxies. We will also study constraints on exotic cooling mechanisms involving axions and majorons set by stellar evolution and the energy input into low mass stars by cold dark matter annihilation in galactic nuclei. We will compute the detailed gamma ray spectrum predicted by various cold dark matter candidates undergoing annihilation in the galactic halo and bulge

  2. [High energy physics]: Progress report

    International Nuclear Information System (INIS)

    During calendar year 1986 the high energy physics group at the University of Massachusetts continued its study of electron-positron annihilation reactions along with the TPC collaboration at the PEP facility of the Stanford Linear Accelerator Center (SLAC). During this year the TPC detector completed its 4th year of data collection including the 2nd year of data gathering with its full momentum resolution capabilities. In addition to assisting in the data collection, the UMass group has participated in hardware monitoring and improvement efforts, and has contributed to a number of diverse data analysis projects. The TPC collaboration has continued to publish numerous analysis results and new publications from the current data sample will continue for at least several years. Continued data taking has been approved at the PEP facility with two major improvements: the PEP luminosity will be increased by a factor of 4 or more, and the TPC will be further enhanced with the addition of a vertex detector. In addition to its continuing work with the TPC collaboration the UMass group has expanded its efforts to include a participation in the SLD project at the new linear collider (SLC) facility at SLAC. This expansion of effort has been facilitated by the addition of another UMass faculty member, Stanley Hertzbach, whose full year sabbatical, beginning this fall, will be spent working full time on the SLC project at SLAC. The UMass group has joined the ''beamline'' subgroup of the SLD project and is working on the design of the masking which is necessary near the interaction point to shield the detector from the intense halo of synchrotron radiation that accompanies the electron and positron beams

  3. Possible Class of Nearby Gamma-Ray Burst / Gravitational Wave Sources

    CERN Document Server

    Norris, J 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 ~ 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 ~ 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+/-0.04, similar to that for SNe type Ib/c within the same volume. The rate of the observed subluminous bursts is o...

  4. Adaptive lag synchronization of uncertain dynamical systems with time delays via simple transmission lag feedback

    Institute of Scientific and Technical Information of China (English)

    Gu Wei-Dong; Sun Zhi-Yong; Wu Xiao-Ming; Yu Chang-Bin

    2013-01-01

    In this paper we present an adaptive scheme to achieve lag synchronization for uncertain dynamical systems with time delays and unknown parameters.In contrast to the nonlinear feedback scheme reported in the previous literature,the proposed controller is a linear one which only involves simple feedback information from the drive system with signal propagation lags.Besides,the unknown parameters can also be identified via the proposed updating laws in spite of the existence of model delays and transmission lags,as long as the linear independence condition between the related function elements is satisfied.Two examples,i.e.,the Mackey-Glass model with single delay and the Lorenz system with multiple delays,are employed to show the effectiveness of this approach.Some robustness issues are also discussed,which shows that the proposed scheme is quite robust in switching and noisy environment.

  5. Lookup tables to compute high energy cosmic ray induced atmospheric ionization and changes in atmospheric chemistry

    OpenAIRE

    Atri, Dimitra; Melott, Adrian L.; Thomas, Brian C.

    2008-01-01

    A variety of events such as gamma-ray bursts and supernovae may expose the Earth to an increased flux of high-energy cosmic rays, with potentially important effects on the biosphere. Existing atmospheric chemistry software does not have the capability of incorporating the effects of substantial cosmic ray flux above 10 GeV . An atmospheric code, the NASA-Goddard Space Flight Center two-dimensional (latitude, altitude) time-dependent atmospheric model (NGSFC), is used to study atmospheric chem...

  6. Mixed Burst Error Correcting Codes

    OpenAIRE

    Sethi, Amita

    2015-01-01

    In this paper, we construct codes which are an improvement on the previously known block wise burst error correcting codes in terms of their error correcting capabilities. Along with different bursts in different sub-blocks, the given codes also correct overlapping bursts of a given length in two consecutive sub-blocks of a code word. Such codes are called mixed burst correcting (mbc) codes.

  7. Transient optical emission from the error box of the gamma-ray burst of 28 February 1997

    DEFF Research Database (Denmark)

    van Paradijs, J.; Groot, P.J.; Galama, T.;

    1997-01-01

    For almost a quarter of a century(1), the origin of gamma-ray bursts-brief, energetic bursts of high-energy photons-has remained unknown. The detection of a counterpart at another wavelength has long been thought to be a key to understanding the nature of these bursts (see, for example, ref. 2......), but intensive searches have not revealed such a counterpart. The distribution and properties of the bursts(3) are explained naturally if they lie at cosmological distances (a few Gpc)(4), but there is a countervailing view that they are relatively local objects(5), perhaps distributed in a very large...... halo around our Galaxy. Here we report the detection of a transient and fading optical source in the error box associated with the burst GRB970228, less than 21 hours after the burst(6,7). The optical transient appears to be associated with a faint galaxy(7,8), suggesting that the burst occurred in...

  8. Systematic Spectral Lag Analysis of Swift Known-z GRBs

    Directory of Open Access Journals (Sweden)

    Yuta Kawakubo

    2015-01-01

    arrive earlier than soft photons. The lag-luminosity relation is the empirical relationship between the isotropic peak luminosity and the spectral lag. We calculated the spectral lags for 40 known redshift GRBs observed by Swift addition to the previous 31 GRB samples. We confirmed that most of our samples follow the lag-luminosity relation. However, we noticed that there are some GRBs which show a significant scatter from the relation. We also confirm that the relationship between the break time and the luminosity of the X-ray afterglow (so-called Dainotti relation extends up to the lag-luminosity relation.

  9. Broadband Study of GRB 091127: A Sub-Energetic Burst at Higher Redshift?

    Science.gov (United States)

    Troja, E.; Sakamoto, T.; Guidorzi, C.; Norris, J. P.; Panaitescu, A.; Kobayashi, S.; Omodei, N.; Brown, J. C.; Burrows, D. N.; Evans, P. A.; Gehrels, N.; Marshall, F. E.; Mawson, N.; Melandri,; Mundell, C. G.; Oates, S. R.; Pal'shin, V.; Preece, R. D.; Racusin, J. L.; Steele, I. A.; Tanvir, N. R.; Vasileiou, V.; Wilson-Hodge, C.

    2012-01-01

    GRB 091127 is a bright gamma-ray burst (GRB) detected by Swift at a redshift z=0.49 and associated with SN 2009nz. We present the broadband analysis of the GRB prompt and afterglow emission and study its high-energy properties in the context of the GRB/SN association. While the high luminosity of the prompt emission and standard afterglow behavior are typical of cosmological long GRBs, its low energy release (E(sub gamma),bursts. We discuss the suppression of high-energy emission in this burst, and investigate whether this behavior could be connected with the sub-energetic nature of the explosion. Subject headings: gamma-ray bursts: individual (GRB 091127)

  10. DEMETER Satellite Observations of Particle Burst Prior to Chile Earthquake

    CERN Document Server

    Zhang, Zhenxia; Shen, Xuhui; Ma, Yuqian; Chen, Huaran; You, Xinzhao; Yuan, Yahong

    2010-01-01

    The lithosphere activity during seismogenic or occurrence of one earthquake may emit electromagnetic wave which propagate to ionosphere and radiation belt, then induce disturbance of electric and magnetic field and the precipitation of high energy charged particles. This paper, based on the data detected by DEMETER satellite, present the high energy charged particle burst(PB) with 4 to 6 times enhancement over the average value observed about ten days days before Chile earthquake. The obvious particle burst was also observed in the northern hemisphere mirror points conjugate of epicenter and no PB events in different years over the same epicenter region was found. The energy spectra of the PBs are different from the one averaged within the first three months in 2010. At the same time, the disturbance of the VLF electric spectrum in ionosphere over the epicenter detected by the DEMETER satellite are also observed in the same two orbits. Those observations from energetic PB and VLF electric spectrum disturbance...

  11. The Fermi view of gamma-ray bursts

    Science.gov (United States)

    Axelsson, Magnus; Fermi/LAT Collaboration

    2015-08-01

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

  12. Pair production and annihilation in gamma-ray bursts

    International Nuclear Information System (INIS)

    The results of nonlinear radiative transport calculations of relevance to gamma-ray bursts and emission from the center of our galaxy are reported. Two-photon pair production and annihilation, as well as three-photon pair annihilation, are included in the calculations; the radiation field itself acts as an absorbing medium, and the optical depth depends on the radiation field. Spherical geometry produces effective collimation of the flux. At high optical depth, the high-energy (>700keV) portion of the emergent spectrum assumes a nearly-universal form. An approximate limit is derived for the high-energy flux from a gamma-ray burst source, and the implications of this limit for the 5 March, 1979 event are briefly discussed.

  13. Ground-based high energy astronomy

    Science.gov (United States)

    McGruder, Charles H., III

    1991-10-01

    The specific aim of the project at hand is to study the changes in amplitude and phase of VLF radio waves to see if we can detect the ionospheric disturbance (the change in electron density) caused by a Gamma-Ray burst. The possible advantages of observing gamma-ray bursts through ionospheric disturbances are better localization of burst directions through a large network of VLF receiving points; measurement of total ionizing fluence of gamma-ray bursts; and comparison with satellite data (GOES and GRO) to derive properties of the ionosphere. There is a major problem here: the ionospheric disturbance caused by a Gamma-Ray burst is at best extremely difficult and at worse impossible to detect. So far only one vent has been detected via this method. Therefore, it was decided to study the ionospheric disturbance caused by solar flares first with the hope that they will teach us how to detect the elusive Gamma-Ray bursts. Much is to be learned about the ionosphere and its reaction to impulsive ionization.

  14. Jet-lag and human performance.

    Science.gov (United States)

    Loat, C E; Rhodes, E C

    1989-10-01

    The desynchronisation of an athlete's physiological and psychological cycles has adverse effects on his/her performance. The primary cause of dysrhythmia in an athlete is jet-lag, which is a rapid displacement across the earth's time zones and is often experienced while competing in international events and in continental leagues. General symptoms which arise from dysynchronization include malaise, appetite loss, tiredness during the day and disturbed sleep. The specific symptoms resulting from jet-lag are characterised as phase shifts in physiological and psychological cycles. These phase shifts occur in body temperature, ability to mobilise energy substrates, excretion of water and metabolites, arousal levels, sleep/wake cycles and reaction time. The severity of these adverse effects and therefore the time required for resynchronization depends on the ability to preset the bodily rhythms prior to flying, the number of time zones crossed, the direction of flight, the type of individual (introvert/extrovert), age, social interaction and activity, diet plan and prescribed use of chronobiotic drugs. PMID:2692117

  15. Is melatonin useful for jet lag?

    Directory of Open Access Journals (Sweden)

    Francisco Tortorolo

    2015-12-01

    Full Text Available El jet lag es un trastorno exógeno del sueño y el ritmo circadiano que ocurre frecuentemente en viajeros que cruzan múltiples zonas horarias en un tiempo reducido. La administración de melatonina oral, neurohormona epifisiaria relacionada con la regulación de ritmos circadianos, se ha utilizado con el fin de disminuir los síntomas que caracterizan esta condición. Utilizando la base de datos Epistemonikos, la cual es mantenida mediante búsquedas en 30 bases de datos, encontramos cuatro revisiones sistemáticas que en conjunto incluyen 11 estudios aleatorizados. Realizamos un metanálisis y tablas de resumen de los resultados utilizando el método GRADE. Concluimos que la administración de melatonina oral probablemente disminuye los síntomas asociados al jet lag, y que no está claro si se asocia a efectos adversos, aunque estos serían leves.

  16. Fiscal policy lags and income adjustment processes

    International Nuclear Information System (INIS)

    Highlights: ► There are delays either in the government expenditure or in the tax system. ► Both delays affect fiscal policy outcomes. ► The system of differential equations with two delays may be chaotic. ► Fiscal policy outcomes might be inconsistent with their stabilization purposes. - Abstract: The interest in the impact of fiscal policy lags on economic stability increased in the last decade. Several studies have been made on delays either in the government expenditure or in the tax system, where lags exist between the accrual and the payment of taxes. Nevertheless there is in the literature no model where time delays in government expenditures and in tax revenues are considered together as it happens in the real world. In this paper we remedied this defect and proposed a macro-dynamic model where two delays appear: the first pertains to the public expenditure, the second, to the tax revenue. The resulting system of delayed differential equations is studied qualitatively and numerically. The analysis suggests that only particular combinations of the two delays make the system stable. Prevalently the system is unstable and chaotic motions may arise. This implies that the economy may need appropriate structural changes in the public sector to improve fiscal policy outcomes in such a way they may really be consistent with their stabilization purposes.

  17. Hopf bifurcation and chaos in macroeconomic models with policy lag

    International Nuclear Information System (INIS)

    In this paper, we consider the macroeconomic models with policy lag, and study how lags in policy response affect the macroeconomic stability. The local stability of the nonzero equilibrium of this equation is investigated by analyzing the corresponding transcendental characteristic equation of its linearized equation. Some general stability criteria involving the policy lag and the system parameter are derived. By choosing the policy lag as a bifurcation parameter, the model is found to undergo a sequence of Hopf bifurcation. The direction and stability of the bifurcating periodic solutions are determined by using the normal form theory and the center manifold theorem. Moreover, we show that the government can stabilize the intrinsically unstable economy if the policy lag is sufficiently short, but the system become locally unstable when the policy lag is too long. We also find the chaotic behavior in some range of the policy lag

  18. Theory of high-energy messengers

    CERN Document Server

    Dermer, Charles D

    2016-01-01

    Knowledge of the distant high-energy universe comes from photons, ultra-high energy cosmic rays (UHECRs), high-energy neutrinos, and gravitational waves. The theory of high-energy messengers reviewed here focuses on the extragalactic background light at all wavelengths, cosmic rays and magnetic fields in intergalactic space, and neutrinos of extragalactic origin. Comparisons are drawn between the intensities of photons and UHECRs in intergalactic space, and the high-energy neutrinos recently detected with IceCube at about the Waxman-Bahcall flux. Source candidates for UHECRs and high-energy neutrinos are reviewed, focusing on star-forming and radio-loud active galaxies. HAWC and Advanced LIGO are just underway, with much anticipation.

  19. Harvard University High Energy Physics progress report

    International Nuclear Information System (INIS)

    The principal goals of this work are to carry out forefront programs in high energy physics research and to provide first rate educational opportunities for students. The experimental program supported through HEPL is carried out at the major accelerator centers in the world and addresses some of the most important questions in high energy physics. The program is based at Harvard's High Energy Physics Laboratory, which has offices, computing facilities, and engineering support, and both electronics and machine shops

  20. Ultra high energy cosmic ray horizons

    International Nuclear Information System (INIS)

    We calculate the horizons of ultra high energy cosmic rays assuming different primary nuclei ranging from proton to iron at ultra high energies (6.1019 eV). We show that sources of ultra high energy protons and heavy nuclei can originate from distances up to ∼180 Mpc, while low and intermediate mass nuclei can only originate in the local universe (<50 Mpc).

  1. Ultra high energy cosmic ray horizons

    Energy Technology Data Exchange (ETDEWEB)

    Busca, N.G. [Laboratoire d' Astroparticules at Cosmologie, 10, rue Alice Domon et Lonie Duquet, 75205 Paris Cedex 13 (France)

    2009-05-15

    We calculate the horizons of ultra high energy cosmic rays assuming different primary nuclei ranging from proton to iron at ultra high energies (6.10{sup 19} eV). We show that sources of ultra high energy protons and heavy nuclei can originate from distances up to approx180 Mpc, while low and intermediate mass nuclei can only originate in the local universe (<50 Mpc).

  2. Split School of High Energy Physics 2015

    CERN Document Server

    2015-01-01

    Split School of High Energy Physics 2015 (SSHEP 2015) was held at the Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture (FESB), University of Split, from September 14 to September 18, 2015. SSHEP 2015 aimed at master and PhD students who were interested in topics pertaining to High Energy Physics. SSHEP 2015 is the sixth edition of the High Energy Physics School. Previous five editions were held at the Department of Physics, University of Sarajevo, Bosnia and Herzegovina.

  3. Ultra High Energy Cosmic Rays and Neutrinos

    CERN Document Server

    Aloisio, Roberto

    2016-01-01

    We discuss the production of ultra high energy neutrinos coming from the propagation of ultra high energy cosmic rays and in the framework of top-down models for the production of these extremely energetic particles. We show the importance of the detection of ultra high energy neutrinos that can be a fundamental diagnostic tool to solve the discrepancy in the observed chemical composition of ultra high energy cosmic rays and, at the extreme energies, can unveil new physics in connection with the recent cosmological observations of the possible presence of tensor modes in the fluctuation pattern of the cosmic microwave background.

  4. High Energy Astrophysics Science Archive Research Center

    Data.gov (United States)

    National Aeronautics and Space Administration — The High Energy Astrophysics Science Archive Research Center (HEASARC) is the primary archive for NASA missions dealing with extremely energetic phenomena, from...

  5. High energy physics and cloud computing

    International Nuclear Information System (INIS)

    High Energy Physics (HEP) has been a strong promoter of computing technology, for example WWW (World Wide Web) and the grid computing. In the new era of cloud computing, HEP has still a strong demand, and major international high energy physics laboratories have launched a number of projects to research on cloud computing technologies and applications. It describes the current developments in cloud computing and its applications in high energy physics. Some ongoing projects in the institutes of high energy physics, Chinese Academy of Sciences, including cloud storage, virtual computing clusters, and BESⅢ elastic cloud, are also described briefly in the paper. (authors)

  6. Neutrino, Neutron, and Cosmic Ray Production in the External Shock Model of Gamma Ray Bursts

    OpenAIRE

    Dermer, Charles D.

    2000-01-01

    The hypothesis that ultra-high energy (>~ 10^19 eV) cosmic rays (UHECRs) are accelerated by gamma-ray burst (GRB) blast waves is assumed to be correct. Implications of this assumption are then derived for the external shock model of gamma-ray bursts. The evolving synchrotron radiation spectrum in GRB blast waves provides target photons for the photomeson production of neutrinos and neutrons. Decay characteristics and radiative efficiencies of the neutral particles that escape from the blast w...

  7. A repeating fast radio burst

    Science.gov (United States)

    Spitler, L. G.; Scholz, P.; Hessels, J. W. T.; Bogdanov, S.; Brazier, A.; Camilo, F.; Chatterjee, S.; Cordes, J. M.; Crawford, F.; Deneva, J.; Ferdman, R. D.; Freire, P. C. C.; Kaspi, V. M.; Lazarus, P.; Lynch, R.; Madsen, E. C.; McLaughlin, M. A.; Patel, C.; Ransom, S. M.; Seymour, A.; Stairs, I. H.; Stappers, B. W.; van Leeuwen, J.; Zhu, W. W.

    2016-03-01

    Fast radio bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find additional bursts at the same dispersion measure (that is, the integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of these bursts has led to the suggestion that they originate in cataclysmic events. Here we report observations of ten additional bursts from the direction of the fast radio burst FRB 121102. These bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB 121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB 121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and which vary on timescales of minutes or less. Although there may be multiple physical origins for the population of fast radio bursts, these repeat bursts with high dispersion measure and variable spectra specifically seen from the direction of FRB 121102 support an origin in a young, highly magnetized, extragalactic neutron star.

  8. A repeating fast radio burst.

    Science.gov (United States)

    Spitler, L G; Scholz, P; Hessels, J W T; Bogdanov, S; Brazier, A; Camilo, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J; Ferdman, R D; Freire, P C C; Kaspi, V M; Lazarus, P; Lynch, R; Madsen, E C; McLaughlin, M A; Patel, C; Ransom, S M; Seymour, A; Stairs, I H; Stappers, B W; van Leeuwen, J; Zhu, W W

    2016-03-10

    Fast radio bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find additional bursts at the same dispersion measure (that is, the integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of these bursts has led to the suggestion that they originate in cataclysmic events. Here we report observations of ten additional bursts from the direction of the fast radio burst FRB 121102. These bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB 121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB 121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and which vary on timescales of minutes or less. Although there may be multiple physical origins for the population of fast radio bursts, these repeat bursts with high dispersion measure and variable spectra specifically seen from the direction of FRB 121102 support an origin in a young, highly magnetized, extragalactic neutron star. PMID:26934226

  9. Light speed variation from gamma ray burst GRB 160509A

    CERN Document Server

    Xu, Haowei

    2016-01-01

    It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers. However, the effect of quantum gravity could bring an energy dependence of light speed. Even a tiny speed variation, when amplified by the cosmological distance, may be revealed by the observed time lags between photons with different energies from astrophysical sources. From the newly detected long gamma ray burst GRB~160509A, we find evidence to support the prediction for a linear form modification of light speed in cosmological space.

  10. Light speed variation from gamma ray burst GRB 160509A

    Science.gov (United States)

    Xu, Haowei; Ma, Bo-Qiang

    2016-09-01

    It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers. However, the effect of quantum gravity could bring an energy dependence of light speed. Even a tiny speed variation, when amplified by the cosmological distance, may be revealed by the observed time lags between photons with different energies from astrophysical sources. From the newly detected long gamma ray burst GRB 160509A, we find evidence to support the prediction for a linear form modification of light speed in cosmological space.

  11. A Lower Bound on Neutrino Mass And Its Implication on the Z-Burst Scenario

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Kwang-Chang; /Taiwan, Natl. Taiwan U.; Chen, Pisin; /KIPAC, Menlo Park

    2006-01-11

    We show that the cascade limit on ultra high energy cosmic neutrino (UHEC/nu) flux imposes a lower bound on the neutrino mass provided that super-GZK events of ultra high energy cosmic rays (UHECRs) are produced from Z-bursts. Based on the data from HiRes and AGASA, the obtained neutrino mass lower bound violates its existing cosmological upper bound. We conclude that the Z-burst cannot be the dominant source for the observed super-GZK UHECR events. This is consistent with the recent ANITA-lite data.

  12. Observing a Burst with Sunglasses

    Science.gov (United States)

    2003-11-01

    Unique Five-Week VLT Study of the Polarisation of a Gamma-Ray Burst Afterglow "Gamma-ray bursts (GRBs)" are certainly amongst the most dramatic events known in astrophysics. These short flashes of energetic gamma-rays, first detected in the late 1960's by military satellites, last from less than one second to several minutes. GRBs have been found to be situated at extremely large ("cosmological") distances. The energy released in a few seconds during such an event is larger than that of the Sun during its entire lifetime of more than 10,000 million years. The GRBs are indeed the most powerful events since the Big Bang known in the Universe, cf. ESO PR 08/99 and ESO PR 20/00. During the past years circumstantial evidence has mounted that GRBs signal the collapse of extremely massive stars, the so-called hypernovae. This was finally demonstrated some months ago when astronomers, using the FORS instrument on ESO's Very Large Telescope (VLT), documented in unprecedented detail the changes in the spectrum of the light source ("the optical afterglow") of the gamma-ray burst GRB 030329 (cf. ESO PR 16/03). A conclusive and direct link between cosmological gamma-ray bursts and explosions of very massive stars was provided on this occasion. Gamma-Ray Burst GRB 030329 was discovered on March 29, 2003 by NASA's High Energy Transient Explorer spacecraft. Follow-up observations with the UVES spectrograph at the 8.2-m VLT KUEYEN telescope at the Paranal Observatory (Chile) showed the burst to have a redshift of 0.1685 [1]. This corresponds to a distance of about 2,650 million light-years, making GRB 030329 the second-nearest long-duration GRB ever detected. The proximity of GRB 030329 resulted in very bright afterglow emission, permitting the most extensive follow-up observations of any afterglow to date. A team of astronomers [2] led by Jochen Greiner of the Max-Planck-Institut für extraterrestrische Physik (Germany) decided to make use of this unique opportunity to study the

  13. Expectations for ultra-high energy interactions

    International Nuclear Information System (INIS)

    Strong interactions at ultra-high energies are discussed with emphasis on the hadrons produced in high energy collisions. Evidence is considered that quantum chromodynamics might be the right theory, and also some estimates are given of quantum chromodynamics asymptotic-freedom phenomena, the work under discussion being very preliminary. 6 references

  14. New aspects of high energy density plasma

    International Nuclear Information System (INIS)

    The papers presented at the symposium on 'New aspects of high energy density plasma' held at National Institute for Fusion Science are collected in this proceedings. The papers reflect the present status and recent progress in the experiments and theoretical works on high energy density plasma produced by pulsed power technology. The 13 of the presented papers are indexed individually. (J.P.N.)

  15. Black holes and high energy physics

    Science.gov (United States)

    Grib, A. A.; Pavlov, Yu. V.

    2016-01-01

    Three mechanisms of getting high energies in particle collisions in the ergosphere of the rotating black holes are considered. The consequences of these mechanisms for observation of ultra high energy cosmic rays particles on the Earth as result of conversion of superheavy dark matter particles into ordinary particles are discussed.

  16. CAMAC high energy physics electronics hardware

    International Nuclear Information System (INIS)

    CAMAC hardware for high energy physics large spectrometers and control systems is reviewed as is the development of CAMAC modules at the High Energy Laboratory, JINR (Dubna). The total number of crates used at the Laboratory is 179. The number of CAMAC modules of 120 different types exceeds 1700. The principles of organization and the structure of developed CAMAC systems are described. (author)

  17. A jet model for Galactic black-hole X-ray sources: The correlation between cutoff energy and phase lag

    Science.gov (United States)

    Reig, P.; Kylafis, N. D.

    2015-12-01

    Context. Galactic black-hole X-ray binaries emit a compact, optically thick, mildy relativistic radio jet when they are in the hard and hard-intermediate states, that is, typically at the beginning and the end of an X-ray outburst. In a series of papers, we have developed a jet model and have shown through Monte Carlo simulations that our model can explain many observational results. Aims: In this work, we investigate one more constraining relationship between the cutoff energy and the phase lag during the early stages of an X-ray outburst of the black-hole X-ray binary GX 339-4: the cutoff energy decreases while the phase lag increases during the brightening of the hard state. Methods: We performed Monte Carlo simulations of the Compton upscattering of soft accretion-disk photons in the jet and computed the phase lag between soft and hard photons and the cutoff energy of the resulting high-energy power law. Results: We demonstrate that our jet model naturally explains the above correlation, with a minor modification consisting of introducing an acceleration zone at the base of the jet. Conclusions: The observed correlation between the cutoff energy and the phase lag in the black-hole binary GX 339-4 suggests that the lags are produced by the hard component. Here we show that this correlation arises naturally if Comptonization in the jet produces these two quantities.

  18. Gamma-Ray Burst Follow-up Observations with STACEE During 2003-2007

    CERN Document Server

    Jarvis, A; Carson, J E; Covault, C E; Driscoll, D D; Fortin, P; Gingrich, D M; Hanna, D S; Kildea, J; Lindner, T; Mukherjee, R; Müller, C; Ong, R A; Ragan, K; Williams, D A; Zweerink, J

    2007-01-01

    The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is an atmospheric Cherenkov telescope (ACT) that uses a large mirror array to achieve a relatively low energy threshold. For sources with Crab-like spectra, at high elevations, the detector response peaks near 100 GeV. Gamma-ray burst (GRB) observations have been a high priority for the STACEE collaboration since the inception of the experiment. We present the results of 20 GRB follow-up observations at times ranging from 3 minutes to 15 hours after the burst triggers. Where redshift measurements are available, we place constraints on the intrinsic high-energy spectra of the bursts.

  19. Temporal Shaping of High Peak Power Pulse Trains from a Burst-Mode Laser System

    OpenAIRE

    Jörg Körner; Jürgen Reiter; Joachim Hein; Kaluza, Malte C.

    2015-01-01

    It has been shown in the past that pulsed laser systems operating in the so-called “burst mode” are a beneficial approach to generate high peak power laser pulses at high repetition rates suitable for various applications. So far, most high-energy burst-mode laser systems put great effort into generating a homogeneous energy distribution across the burst duration, e.g., by shaping the pump pulse. In this work, we present a new shaping technique, which is able to produce arbitrary energy distr...

  20. Modeling high-energy cosmic ray induced terrestrial and atmospheric neutron flux: A lookup table

    CERN Document Server

    Overholt, Andrew; Atri, Dimitra

    2013-01-01

    Under current conditions, the cosmic ray spectrum incident on the Earth is dominated by particles with energies < 1 GeV. Astrophysical sources including high energy solar flares, supernovae and gamma ray bursts produce high energy cosmic rays (HECRs) with drastically higher energies. The Earth is likely episodically exposed to a greatly increased HECR flux from such events, some of which lasting thousands to millions of years. The air showers produced by HECRs ionize the atmosphere and produce harmful secondary particles such as muons and neutrons. Neutrons currently contribute a significant radiation dose at commercial passenger airplane altitude. With higher cosmic ray energies, these effects will be propagated to ground level. This work shows the results of Monte Carlo simulations quantifying the neutron flux due to high energy cosmic rays at various primary energies and altitudes. We provide here lookup tables that can be used to determine neutron fluxes from primaries with total energies 1 GeV - 1 PeV...

  1. Implications of Lag-Luminosity Relationship for Unified GRB Paradigms

    CERN Document Server

    Norris, J P

    2002-01-01

    Spectral lags are deduced for 1437 long GRBs with peak fluxes extending to near the BATSE trigger threshold. The lags are modeled to approximate the observed distribution in the peak flux-lag plane, realizing a noise-free representation. Assuming a two-branch lag-luminosity relationship, the lags are self- consistently corrected for cosmological effects to yield distributions in luminosity, distance, and redshift. The results have several consequences for GRB populations -- including a possible nearby subpopulation of low-luminosity, long-lag GRBs -- and for unified gamma-ray/afterglow scenarios which would account for afterglow break times and gamma-ray spectral evolution in terms of jet opening angle, viewing angle, or a profiled jet with variable Lorentz factor.

  2. Phase-lag Distances of OH Masing AGB Stars

    OpenAIRE

    Engels, D.; Etoka, S.; Gerard, E.; Richards, A.

    2015-01-01

    Distances to AGB stars with optically thick circumstellar shells cannot be determined using optical parallaxes. However, for stars with OH 1612 MHz maser emission emanating from their circumstellar shells, distances can be determined by the phase-lag method. This method combines a linear diameter obtained from a phase-lag measurement with an angular diameter obtained from interferometry. The phase-lag of the variable emission from the back and front sides of the shells has been determined for...

  3. When Does Lag Structure Really Matter in Optimizing Advertising Expenditures?

    OpenAIRE

    Wesley A. Magat; McCann, John M; Richard C. Morey

    1986-01-01

    A paper by Bultez and Naert in the May 1979 issue of Management Science tentatively concludes that profits are relatively insensitive to misspecification of the lag structure of advertising. We examine the conditions under which a firm's profits are most likely to be sensitive to the misspecification of the lag structure. Our analysis indicates how this sensitivity is related to (a) the form of the true lag structure, (b) the demand function, (c) the cost function, and (d) the firm's discount...

  4. Replisome mechanics: lagging strand events that influence speed and processivity

    OpenAIRE

    Georgescu, Roxana E.; Yao, Nina; Indiani, Chiara; Yurieva, Olga; O'Donnell, Mike E

    2014-01-01

    The antiparallel structure of DNA requires lagging strand synthesis to proceed in the opposite direction of the replication fork. This imposes unique events that occur only on the lagging strand, such as primase binding to DnaB helicase, RNA synthesis, and SS B antigen (SSB) displacement during Okazaki fragment extension. Single-molecule and ensemble techniques are combined to examine the effect of lagging strand events on the Escherichia coli replisome rate and processivity. We find that pri...

  5. Transmission Lags of Monetary Policy: A Meta-Analysis

    OpenAIRE

    Havránek, Tomáš; Rusnák, Marek

    2012-01-01

    The transmission of monetary policy to the economy is generally thought to have long and variable lags. In this paper we quantitatively review the modern literature on monetary transmission to provide stylized facts on the average lag length and the sources of variability. We collect 67 published studies and examine when prices bottom out after a monetary contraction. The average transmission lag is 29 months, and the maximum decrease in prices reaches 0.9% on average after a one-percentage-p...

  6. Corporate Governance and Audit Report Lag in Malaysia

    OpenAIRE

    Mohamad Naimi Mohamad-Nor; ; Rohami Shafie; Wan Nordin Wan-Hussin

    2010-01-01

    This paper examines audit report lag in Malaysian public listed companies, following the implementation of the Malaysian Code on Corporate Governance in 2001. It departs from the standard audit report lag studies by incorporating characteristics of the board of directors and the audit committee. Multivariate analysis using 628 annual reports for the year ended 2002 indicates that active and larger audit committees shorten audit lag. However, we fail to find evidence that audit committee indep...

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

    CERN Document Server

    Böttcher, M

    1998-01-01

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

  8. Solution High-Energy Burst Assembly (SHEBA) results from subprompt critical experiments with uranyl fluoride fuel

    Energy Technology Data Exchange (ETDEWEB)

    Cappiello, C.C.; Butterfield, K.B.; Sanchez, R.G.; Bounds, J.A.; Kimpland, R.H.; Damjanovich, R.P.; Jaegers, P.J.

    1997-08-01

    Experiments were performed to measure a variety of parameters for SHEBA: behavior of the facility during transient and steady-state operation; characteristics of the SHEBA fuel; delayed-critical solution height vs solution temperature; initial reactor period and reactivity vs solution height; calibration of power level vs reactor power instrumentation readings; flux profile in SHEBA; radiation levels and neutron spectra outside the assembly for code verification and criticality alarm and dosimetry purposes; and effect on reactivity of voids in the fuel.

  9. Solution High-Energy Burst Assembly (SHEBA) results from subprompt critical experiments with uranyl fluoride fuel

    International Nuclear Information System (INIS)

    Experiments were performed to measure a variety of parameters for SHEBA: behavior of the facility during transient and steady-state operation; characteristics of the SHEBA fuel; delayed-critical solution height vs solution temperature; initial reactor period and reactivity vs solution height; calibration of power level vs reactor power instrumentation readings; flux profile in SHEBA; radiation levels and neutron spectra outside the assembly for code verification and criticality alarm and dosimetry purposes; and effect on reactivity of voids in the fuel

  10. Viscous time lags between starburst and AGN activity

    CERN Document Server

    Blank, Marvin

    2016-01-01

    There is strong observational evidence indicating a time lag of order of some 100 Myr between the onset of starburst and AGN activity in galaxies. Dynamical time lags have been invoked to explain this. We extend this approach by introducing a viscous time lag the gas additionally needs to flow through the AGN's accretion disc before it reaches the central black hole. Our calculations reproduce the observed time lags and are in accordance with the observed correlation between black hole mass and stellar velocity dispersion.

  11. Intermittent lag synchronization in a driven system of coupled oscillators

    Indian Academy of Sciences (India)

    Alexander N Pisarchik; Rider Jaimes-Reátegui

    2005-04-01

    We study intermittent lag synchronization in a system of two identical mutually coupled Duffing oscillators with parametric modulation in one of them. This phenomenon in a periodically forced system can be seen as intermittent jump from phase to lag synchronization, during which the chaotic trajectory visits a periodic orbit closely. We demonstrate different types of intermittent lag synchronizations, that occur in the vicinity of saddle-node bifurcations where the system changes its dynamical state, and characterize the simplest case of period-one intermittent lag synchronization.

  12. Sensitivity of the FERMI Detectors to Gamma-Ray Bursts from Evaporating Primordial Black Holes (PBHs)

    CERN Document Server

    Ukwatta, T N; Parke, W C; Dhuga, K S; Rhodes, S; Eskandarian, A; Gehrels, N; Maximon, L; Morris, D C

    2010-01-01

    Primordial Black Holes (PBHs), which may have been created in the early Universe, are predicted to be detectable by their Hawking radiation. The Fermi Gamma-ray Space Telescope observatory offers increased sensitivity to the gamma-ray bursts produced by PBHs with an initial mass of $\\sim 5\\times 10^{14}$ g expiring today. PBHs are candidate progenitors of unidentified Gamma-Ray Bursts (GRBs) that lack X-ray afterglow. We propose spectral lag, which is the temporal delay between the high and low energy pulses, as an efficient method to identify PBH evaporation events with the Fermi Large Area Telescope (LAT).

  13. The Kolmogorov-Smirnov test for three redshift distributions of long gamma-ray bursts in the Swift Era

    Institute of Scientific and Technical Information of China (English)

    Yun-Ming Dong; Tan Lu

    2009-01-01

    We investigate redshift distributions of three long burst samples, with the first sample containing 131 long bursts with observed redshifts, the second including 220 long bursts with pseudo-redshifts calculated by the variability-luminosity relation, and the third including 1194 long bursts with pseudo-redshifts calculated by the lag-luminosity relation, respectively. In the redshift range 0-1 the Kolmogorov-Smirnov probability of the observed redshift distribution and that of the variability-luminosity relation is large. In the redshift ranges 1-2, 2-3, 3-6.3 and 0-37, the Kolmogorov-Smimov probabilities of the redshift distribution from lag-luminosity relation and the observed redshift distri-bution are also large. For the GRBs, which appear both in the two pseudo-redshift burst samples, the KS probability of the pseudo-redshift distribution from the lag-luminosity relation and the observed reshifi distribution is 0.447, which is very large. Based on these results, some conclusions are drawn: I) the V-Liso relation might be more believable than the τ-Liso relation in low redshift ranges and the τ-Liso relation might be more real than the V-Liso relation in high redshift ranges; ii) if we do not consider the redshift ranges, the τ-Liso relation might be more physical and intrinsical than the V-Liso relation.

  14. Introduction to Optical Burst Switching

    OpenAIRE

    KERNÁCS János; SZILÁGYI Szabolcs

    2010-01-01

    Optical Burst Switching (OBS) isconsidered a popular switching paradigm for therealization of all-optical networks due to the balance itoffers between the coarse-grained Optical CircuitSwitching (OSC) and fine-grained Optical PacketSwitching (OPS). Given that the data are switched allopticallyat the burst level, Optical Burst Switchingcombines the transparency of Optical CircuitSwitching with the benefits of statistical multiplexingin Optical Packet Switching.

  15. High energy hadrons in extensive air showers

    Science.gov (United States)

    Tonwar, S. C.

    1985-01-01

    Experimental data on the high energy hadronic component in extensive air showers of energies approx. 10 to the 14 to 10 to the 16 eV when compared with expectations from Monte Carlo simulations have shown the observed showers to be deficient in high energy hadrons relative to simulated showers. An attempt is made to understand these anomalous features with more accurate comparison of observations with expectations, taking into account the details of the experimental system. Results obtained from this analysis and their implications for the high energy physics of particle interactions at energy approx. 10 to the 15 eV are presented.

  16. New accelerators in high-energy physics

    International Nuclear Information System (INIS)

    First, I should like to mention a few new ideas that have appeared during the last few years in the accelerator field. A couple are of importance in the design of injectors, usually linear accelerators, for high-energy machines. Then I shall review some of the somewhat sensational accelerator projects, now in operation, under construction or just being proposed. Finally, I propose to mention a few applications of high-energy accelerators in fields other than high-energy physics. I realize that this is a digression from my title but I hope that you will find it interesting

  17. High energy physics in the United States

    International Nuclear Information System (INIS)

    The US program in high energy physics from 1985 to 1995 is reviewed. The program depends primarily upon work at the national accelerator centers, but includes a modest but diversified nonaccelerator program. Involvement of universities is described. International cooperation in high energy physics is discussed, including the European, Japanese, USSR, and the People's Republic of China's programs. Finally, new facilities needed by the US high energy physics program are discussed, with particular emphasis given to a Superconducting Super Collider for achieving ever higher energies in the 20 TeV range

  18. CERN and the high energy frontier

    Directory of Open Access Journals (Sweden)

    Tsesmelis Emmanuel

    2014-04-01

    Full Text Available This paper presents the particle physics programme at CERN at the high-energy frontier. Starting from the key open questions in particle physics and the large-scale science facilities existing at CERN, concentrating on the Large Hadron Collider(LHC, this paper goes on to present future possibilities for global projects in high energy physics. The paper presents options for future colliders, all being within the framework of the recently updated European Strategy for Particle Physics, and all of which have a unique value to add to experimental particle physics. The paper concludes by outlining key messages for the way forward for high-energy physics research.

  19. Practical neutron dosimetry at high energies

    International Nuclear Information System (INIS)

    Dosimetry at high energy particle accelerators is discussed with emphasis on physical measurements which define the radiation environment and provide an immutable basis for the derivation of any quantities subsequently required for risk evaluation. Results of inter-laboratory dosimetric comparisons are reviewed and it is concluded that a well-supported systematic program is needed which would make possible detailed evaluations and inter-comparisons of instruments and techniques in well characterized high energy radiation fields. High-energy dosimetry is so coupled with radiation transport that it is clear their study should proceed concurrently

  20. Cosmic-Rays and Gamma Ray Bursts

    Science.gov (United States)

    Meli, A.

    2013-07-01

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

  1. Sky Coverage and Burst Repetition

    OpenAIRE

    Band, David L.

    1996-01-01

    To investigate the repeater content of gamma ray burst samples I develop two models where sources burst at a constant average rate. I find that the sky coverage affects the number of repeaters in a sample predominantly through the detector livetime, and that the number of bursts in the sample is the primary parameter. Thus the repeater content of burst samples should be compared within the context of a repetition model; a direct comparison between two samples is possible only if the samples h...

  2. UWB dual burst transmit driver

    Science.gov (United States)

    Dallum, Gregory E.; Pratt, Garth C.; Haugen, Peter C.; Zumstein, James M.; Vigars, Mark L.; Romero, Carlos E.

    2012-04-17

    A dual burst transmitter for ultra-wideband (UWB) communication systems generates a pair of precisely spaced RF bursts from a single trigger event. An input trigger pulse produces two oscillator trigger pulses, an initial pulse and a delayed pulse, in a dual trigger generator. The two oscillator trigger pulses drive a gated RF burst (power output) oscillator. A bias driver circuit gates the RF output oscillator on and off and sets the RF burst packet width. The bias driver also level shifts the drive signal to the level that is required for the RF output device.

  3. NEW BURST ASSEMBLY AND SCHEDULING TECHNIQUE FOR OPTICAL BURST SWITCHING NETWORKS

    OpenAIRE

    V.KAVITHA; Palanisamy, V.

    2013-01-01

    The Optical Burst Switching is a new switching technology that efficiently utilizes the bandwidth in the optical layer. The key areas to be concentrated in Optical Burst Switching (OBS) networks are the burst assembly and burst scheduling i.e., assignment of wavelengths to the incoming bursts. This study presents a New Burst Assembly and Scheduling (NBAS) technique in a simultaneous multipath transmission for burst loss recovery in OBS networks. A Redundant Burst Segmentation (RBS) is used fo...

  4. Gamma Ray Bursts

    Science.gov (United States)

    Gehrels, Neil; Meszaros, Peter

    2012-01-01

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

  5. Gamma-Ray Bursts

    Science.gov (United States)

    Gehrels, Neil; Mészáros, Péter

    2012-08-01

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

  6. Gamma Ray Bursts

    CERN Document Server

    Gehrels, Neil; 10.1126/science.1216793

    2012-01-01

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

  7. Dark Gamma Ray Bursts

    OpenAIRE

    Brdar, Vedran; Kopp, Joachim; Liu, Jia

    2016-01-01

    Many theories of dark matter (DM) predict that DM particles can be captured by stars via scattering on ordinary matter. They subsequently condense into a DM core close to the center of the star and eventually annihilate. In this work, we trace DM capture and annihilation rates throughout the life of a massive star and show that this evolution culminates in an intense annihilation burst coincident with the death of the star in a core collapse supernova. The reason is that, along with the stell...

  8. Corotation lag and magnetospheric energetics of Jupiter

    International Nuclear Information System (INIS)

    Jupiter exerts an enormous torque upon its magnetospheric plasma to force the latter to corotate. However, the corotation is generally not perfect due to internal production of plasma and/or its outward transport. In a steady state in which the magnetosphere rotationally lags behind the ionosphere, a Birkeland current system is formed to couple the two regions. This current is found to play a dual role in the magnetospheric energetics of Jupiter. On the one hand, it transfers energy from the planetary rotation to the magnetosphere; on the other hand, it returns part of this transferred energy back to the ionosphere to drive the ionospheric current required for the maintenance of the current system. Owing to this partition of energy, the magnetosphere gets only about one third of the energy extracted from the planetary rotation, with the rest going to the ionosphere as Joule heating. The total energy delivery from the planetary rotation amounts to over 1014W, considerably larger than the solar wind contribution. (author)

  9. Physics at high energy photon photon colliders

    International Nuclear Information System (INIS)

    I review the physic prospects for high energy photon photon colliders, emphasizing results presented at the LBL Gamma Gamma Collider Workshop. Advantages and difficulties are reported for studies of QCD, the electroweak gauge sector, supersymmetry, and electroweak symmetry breaking

  10. The evolution of high energy accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Courant, E.D.

    1989-10-01

    In this lecture I would like to trace how high energy particle accelerators have grown from tools used for esoteric small-scale experiments to gigantic projects being hotly debated in Congress as well as in the scientific community.

  11. 1570 nm High Energy Fiber Laser Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR phase I project proposes a single frequency high energy fiber laser for remote sensing. Current state-of-art technologies can not provide all features of...

  12. Parton distributions with high energy proton beams

    International Nuclear Information System (INIS)

    The opportunities for using high energy proton beams to advance our current knowledge in parton distributions are discussed. Highlights from some Fermilab dimuon production experiments with 800 GeV proton beams are presented. Possible future directions are discussed

  13. The evolution of high energy accelerators

    International Nuclear Information System (INIS)

    In this lecture I would like to trace how high energy particle accelerators have grown from tools used for esoteric small-scale experiments to gigantic projects being hotly debated in Congress as well as in the scientific community

  14. High Energy Single Frequency Resonant Amplifier Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR phase I project proposes a single frequency high energy resonant amplifier for remote sensing. Current state-of-art technologies can not provide all...

  15. High-energy black hole production

    OpenAIRE

    Giddings, Steven B.

    2007-01-01

    Black hole production in high-energy collisions is briefly surveyed. Included is a summary of recent developments and open problems relevant to collider (LHC) production, as well as of some theoretical issues pointing towards fundamental principles of quantum gravity.

  16. Research in High Energy Physics. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Conway, John S.

    2013-08-09

    This final report details the work done from January 2010 until April 2013 in the area of experimental and theoretical high energy particle physics and cosmology at the University of California, Davis.

  17. Physics at High Energy Photon Photon Colliders

    OpenAIRE

    Chanowitz, Michael S.

    1994-01-01

    I review the physics prospects for high energy photon photon colliders, emphasizing results presented at the LBL Gamma Gamma Collider Workshop. Advantages and difficulties are reported for studies of QCD, the electroweak gauge sector, supersymmetry, and electroweak symmetry breaking.

  18. Observation of solar high energy gamma and X-ray emission and solar energetic particles

    CERN Document Server

    Struminsky, Alexei

    2015-01-01

    We considered 18 solar flares observed between June 2010 and July 2012, in which high energy >100 MeV {\\gamma}-emission was registered by the Large Area Telescope (LAT) aboard FermiGRO. We examined for these {\\gamma}-events soft X-ray observations by GOES, hard X-ray observations by the Anti-Coincidence Shield of the SPectrometer aboard INTEGRAL (ACS SPI) and the Gamma-Ray burst Monitor (GBM) aboard FermiGRO. Hard X-ray and {\\pi}0-decay {\\gamma}-ray emissions are used as tracers of electron and proton acceleration, respectively. Bursts of hard X-ray were observed by ACS SPI during impulsive phase of 13 events. Bursts of hard X-ray >100 keV were not found during time intervals, when prolonged hard {\\gamma}-emission was registered by LAT/FermiGRO. Those events showing prolonged high-energy gamma-ray emission not accompanied by >100 keV hard X-ray emission are interpreted as an indication of either different acceleration processes for protons and electrons or as the presence of a proton population accelerated du...

  19. Elementary particle physics and high energy phenomena

    International Nuclear Information System (INIS)

    This report discusses the following research in high energy physics: the properties of the z neutral boson with the SLD detector; the research and development program for the SDC muon detector; the fixed-target k-decay experiments; the Rocky Mountain Consortium for HEP; high energy photoproduction of states containing heavy quarks; and electron-positron physics with the CLEO II and Mark II detectors. (LSP)

  20. Elementary particle physics and high energy phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Barker, A.R.; Cumalat, J.P.; de Alwis, S.P.; DeGrand, T.A.; Ford, W.T.; Mahanthappa, K.T.; Nauenberg, U.; Rankin, P.; Smith, J.G.

    1992-06-01

    This report discusses the following research in high energy physics: the properties of the z neutral boson with the SLD detector; the research and development program for the SDC muon detector; the fixed-target k-decay experiments; the Rocky Mountain Consortium for HEP; high energy photoproduction of states containing heavy quarks; and electron-positron physics with the CLEO II and Mark II detectors. (LSP).

  1. A unified treatment of high energy interactions

    Energy Technology Data Exchange (ETDEWEB)

    Drescher, H.J.; Werner, K. [Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Physique Subatomique et des Technologies Associees; Hladik, M. [Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Physique Subatomique et des Technologies Associees]|[SAP AG, Berlin (Germany); Ostapchenko, S. [Moscow State Univ. (Russian Federation). Inst. of Nuclear Physics]|[Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Physique Subatomique et des Technologies Associees

    1999-11-01

    It is well known that high energy interactions as different as electron-positron annihilation, deep inelastic lepton-nucleon scattering, proton-proton interactions, and nucleus-nucleus collisions have many features in common. Based upon this observation, a model for all these interactions is constructed which relies on the fundamental hypothesis that the behavior of high energy interactions is universal. (author) 19 refs.

  2. 49 CFR 230.64 - Leaks under lagging.

    Science.gov (United States)

    2010-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Steam Leaks § 230.64 Leaks under lagging. The steam locomotive owner and/or operator shall take out of service at once any boiler that has developed a leak under the lagging due to a crack in the shell, or...

  3. Dark Gamma Ray Bursts

    CERN Document Server

    Brdar, Vedran; Liu, Jia

    2016-01-01

    Many theories of dark matter (DM) predict that DM particles can be captured by stars via scattering on ordinary matter. They subsequently condense into a DM core close to the center of the star and eventually annihilate. In this work, we trace DM capture and annihilation rates throughout the life of a massive star and show that this evolution culminates in an intense annihilation burst coincident with the death of the star in a core collapse supernova. The reason is that, along with the stellar interior, also its DM core heats up and contracts, so that the DM density increases rapidly during the final stages of stellar evolution. We argue that, counterintuitively, the annihilation burst is more intense if DM annihilation is a p-wave process than for s-wave annihilation because in the former case, more DM particles survive until the supernova. If among the DM annihilation products are particles like dark photons that can escape the exploding star and decay to Standard Model particles later, the annihilation bu...

  4. Modeling gamma-ray bursts

    Science.gov (United States)

    Maxham, Amanda

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

  5. Burst propagation in Texas Helimak

    Science.gov (United States)

    Pereira, F. A. C.; Toufen, D. L.; Guimarães-Filho, Z. O.; Caldas, I. L.; Gentle, K. W.

    2016-05-01

    We present investigations of extreme events (bursts) propagating in the Texas Helimak, a toroidal plasma device in which the radial electric field can be changed by application of bias. In the experiments analyzed, a large grid of Langmuir probes measuring ion saturation current fluctuations is used to study the burst propagation and its dependence on the applied bias voltage. We confirm previous results reported on the turbulence intermittency in the Texas Helimak, extending them to a larger radial interval with a density ranging from a uniform decay to an almost uniform value. For our analysis, we introduce an improved procedure, based on a multiprobe bidimensional conditional averaging method, to assure precise determination of burst statistical properties and their spatial profiles. We verify that intermittent bursts have properties that vary in the radial direction. The number of bursts depends on the radial position and on the applied bias voltage. On the other hand, the burst characteristic time and size do not depend on the applied bias voltage. The bias voltage modifies the vertical and radial burst velocity profiles differently. The burst velocity is smaller than the turbulence phase velocity in almost all the analyzed region.

  6. Short duration gamma ray bursts

    Indian Academy of Sciences (India)

    Patrick Das Gupta

    2004-10-01

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

  7. Burst Mode Transmission in GPON

    Institute of Scientific and Technical Information of China (English)

    LI Liang-chuan; ZHANG Yan-gan; LI Ling; XU Da-xiong

    2004-01-01

    In this paper, a newly approved standard G.984 for Gigabit-capable Passive Optical Networks (GPON) is introduced. Technical challenges about high-speed burst-mode data transmission in GPON are discussed and key issues such as Forward Error Correction (FEC), timing to uplink performance of burst mode are high-lighted.

  8. Scheduling start time in CDMA burst admission

    OpenAIRE

    Zhuge, L; Li, VOK

    2002-01-01

    Burst transmission protocols have been proposed in the next generation CDMA cellular systems to support short-time high-speed data communications. The existing burst admission algorithm considers only the current interference condition in the system. The burst transmission request will be rejected if the interference in the system will exceed the acceptable level with the burst admitted. In this paper we propose a new burst admission algorithm where a currently-unacceptable burst request can ...

  9. Burst Detector Sensitivity: Past, Present & Future

    OpenAIRE

    Band, David L.

    2006-01-01

    I compare the burst detection sensitivity of CGRO's BATSE, Swift's BAT, the GLAST Burst Monitor (GBM) and EXIST as a function of a burst's spectrum and duration. A detector's overall burst sensitivity depends on its energy sensitivity and set of accumulations times Delta t; these two factors shape the detected burst population. For example, relative to BATSE, the BAT's softer energy band decreases the detection rate of short, hard bursts, while the BAT's longer accumulation times increase the...

  10. Testing Special Relativity at High Energies with Astrophysical Sources

    Science.gov (United States)

    Stecker, F. W.

    2007-01-01

    Since the group of Lorentz boosts is unbounded, there is a question as to whether Lorentz invariance (LI) holds to infinitely short distances. However, special and general relativity may break down at the Planck scale. Various quantum gravity scenarios such as loop quantum gravity, as well as some forms of string theory and extra dimension models may imply Lorentz violation (LV) at ultrahigh energies. The Gamma-Ray Large Area Space Telescope (GLAST), to be launched in mid-December, will measure the spectra of distant extragalactic sources of high energy gamma-rays, particularly active galactic nuclei and gamma-ray bursts. GLAST can look for energy-dependent gamma-ray propagation effects from such sources as a signal of Lorentz invariance violation. These sources may also exhibit the high energy cutoffs predicted to be the result of intergalactic annihilation interactions with low energy photons having a flux level as determined by various astronomical observations. With LV the threshold for such interactions can be significantly raised, changing the predicted absorption turnover in the observed spectrum of the sources. Stecker and Glashow have shown that the existence such absorption features in the spectra of extragalactic sources puts constraints on LV. Such constraints have important implications for some quantum gravity and large extra dimension models. Future spaceborne detectors dedicated to measuring gamma-ray polarization can look for birefringence effects as a possible signal of loop quantum gravity. A very small LV may also result in the modification or elimination of the GZK effect, thus modifying the spectrum of ultrahigh energy cosmic rays. This possibility can be explored with ground-based arrays such as Auger or with a space based detector system such as the proposed OWL satellite mission.

  11. Neutrinos from Gamma Ray Bursts in the IceCube and ARA Era

    Directory of Open Access Journals (Sweden)

    Guetta Dafne

    2016-01-01

    I discuss the constraints on the hadronic component of GRBs derived from the search of four years of IceCube data for a prompt neutrino fux from gamma-ray bursts (GRBs and more in general I present the results of the search for high-energy neutrinos interacting within the IceCube detector between 2010 and 2013.

  12. How Else Can We Detect Fast Radio Bursts?

    Science.gov (United States)

    Lyutikov, Maxim; Lorimer, Duncan R.

    2016-06-01

    We discuss possible electromagnetic signals accompanying Fast Radio Bursts (FRBs) that are expected in the scenario where FRBs originate in neutron star magnetospheres. For models involving Crab-like giant pulses, no appreciable contemporaneous emission is expected at other wavelengths. However, magnetar giant flares, driven by the reconfiguration of the magnetosphere, can produce both contemporaneous bursts at other wavelengths as well as afterglow-like emission. We conclude that the best chances are: (i) prompt short GRB-like emission, (ii) a contemporaneous optical flash that can reach naked eye peak luminosity (but only for a few milliseconds), and (iii) a high-energy afterglow emission. Case (i) could be tested by coordinated radio and high-energy experiments. Case (ii) could be seen in a coordinated radio-optical surveys, e.g., by the Palomar Transient Factory in a 60 s frame as a transient object of m = 15–20 mag with an expected optical detection rate of about 0.1 hr‑1, an order of magnitude higher than in radio. Shallow, but large-area sky surveys such as ASAS-SN and EVRYSCOPE could also detect prompt optical flashes from the more powerful Lorimer-burst clones. The best constraints on the optical to radio power for this kind of emission could be provided by future observations with facilities like Large Synoptic Survey Telescope. Case (iii) might be seen in relatively rare cases that the relativistically ejected magnetic blob is moving along the line of sight.

  13. Light Dawns on Dark Gamma-ray Bursts

    Science.gov (United States)

    2010-12-01

    Gamma-ray bursts are among the most energetic events in the Universe, but some appear curiously faint in visible light. The biggest study to date of these so-called dark gamma-ray bursts, using the GROND instrument on the 2.2-metre MPG/ESO telescope at La Silla in Chile, has found that these gigantic explosions don't require exotic explanations. Their faintness is now fully explained by a combination of causes, the most important of which is the presence of dust between the Earth and the explosion. Gamma-ray bursts (GRBs), fleeting events that last from less than a second to several minutes, are detected by orbiting observatories that can pick up their high energy radiation. Thirteen years ago, however, astronomers discovered a longer-lasting stream of less energetic radiation coming from these violent outbursts, which can last for weeks or even years after the initial explosion. Astronomers call this the burst's afterglow. While all gamma-ray bursts [1] have afterglows that give off X-rays, only about half of them were found to give off visible light, with the rest remaining mysteriously dark. Some astronomers suspected that these dark afterglows could be examples of a whole new class of gamma-ray bursts, while others thought that they might all be at very great distances. Previous studies had suggested that obscuring dust between the burst and us might also explain why they were so dim. "Studying afterglows is vital to further our understanding of the objects that become gamma-ray bursts and what they tell us about star formation in the early Universe," says the study's lead author Jochen Greiner from the Max-Planck Institute for Extraterrestrial Physics in Garching bei München, Germany. NASA launched the Swift satellite at the end of 2004. From its orbit above the Earth's atmosphere it can detect gamma-ray bursts and immediately relay their positions to other observatories so that the afterglows could be studied. In the new study, astronomers combined Swift

  14. High energy physics advisory panel's subpanel on vision for the future of high-energy physics

    International Nuclear Information System (INIS)

    This report was requested by the Secretary of Energy to (1) define a long-term program for pursuing the most important high-energy physics goals since the termination of the Superconducting Super Collider (SSC) project, (2) assess the current US high-energy physics program, and (3) make recommendations regarding the future of the field. Subjects on which recommendations were sought and which the report addresses were: high-energy physics funding priorities; facilitating international collaboration for future construction of large high-energy physics facilities; optimizing uses of the investment made in the SSC; how to encourage displaced scientists and engineers to remain in high-energy physics and to attract young scientists to enter the field in the future. The report includes a description of the state of high-energy physics research in the context of history, a summary of the SSC project, and documentation of the report's own origins and development

  15. High-energy gamma-rays from GRB X-ray flares

    International Nuclear Information System (INIS)

    The recent detection of X-ray flares during the afterglow phase of gamma-ray bursts (GRBs) suggests an inner-engine origin, at radii inside the forward shock. There must be inverse Compton (IC) emission arising from such flare photons scattered by forward shock afterglow electrons when they are passing through the forward shock. We find that this IC emission produces high energy gamma-ray flares, which may be detected by AGILE, GLAST and ground-based TeV telescopes. The anisotropic IC scattering between flare photons and forward shock electrons does not affect the total IC component intensity, but cause a time delay of the IC component peak relative to the flare peak. We speculate that this IC component may already have been detected by EGRET from a very strong burst--GRB940217. Future observations by GLAST may help to distinguish whether X-ray flares originate from late central engine activity or from external shocks

  16. The observations of high energy electrons and associated waves by DSP satellites during substorm

    International Nuclear Information System (INIS)

    Double Star Program (DSP) is a CNSA-ESA cooperation mission. DSP consists of two satellites: Equatorial satellite (TC-1) and Polar satellite (TC-2). This paper presents important observations of long duration loss of high energetic electrons and relevant waves in the recovery phase of substorm, that are made by LFEW and HEED of the polar satellite of DSP (TC-2). The HEED of TC-2 observed a loss event of high energetic electrons which lasted about 4 minute. At the same time, the LFEW of TC-2 observed a wave burst. The wave burst began 1 minute earlier than the loss event of energetic electrons. The frequency of waves ranges form 600 Hz to over 10 kHz. The analyses of wave characteristics indicate that the wave was whistler-mode. Thus it is very possible that the loss of high energy electrons was caused by wave activities through wave-particle interactions

  17. FERMI OBSERVATIONS OF HIGH-ENERGY GAMMA-RAY EMISSION FROM GRB 080825C

    International Nuclear Information System (INIS)

    The Fermi Gamma-ray Space Telescope has opened a new high-energy window in the study of gamma-ray bursts (GRBs). Here we present a thorough analysis of GRB 080825C, which triggered the Fermi Gamma-ray Burst Monitor (GBM), and was the first firm detection of a GRB by the Fermi Large Area Telescope (LAT). We discuss the LAT event selections, background estimation, significance calculations, and localization for Fermi GRBs in general and GRB 080825C in particular. We show the results of temporal and time-resolved spectral analysis of the GBM and LAT data. We also present some theoretical interpretation of GRB 080825C observations as well as some common features observed in other LAT GRBs.

  18. Quantum key based burst confidentiality in optical burst switched networks.

    Science.gov (United States)

    Balamurugan, A M; Sivasubramanian, A

    2014-01-01

    The optical burst switching (OBS) is an emergent result to the technology concern that could achieve a feasible network in future. They are endowed with the ability to meet the bandwidth requirement of those applications that require intensive bandwidth. There are more domains opening up in the OBS that evidently shows their advantages and their capability to face the future network traffic. However, the concept of OBS is still far from perfection facing issues in case of security threat. The transfer of optical switching paradigm to optical burst switching faces serious downfall in the fields of burst aggregation, routing, authentication, dispute resolution, and quality of service (QoS). This paper deals with employing RC4 (stream cipher) to encrypt and decrypt bursts thereby ensuring the confidentiality of the burst. Although the use of AES algorithm has already been proposed for the same issue, by contrasting the two algorithms under the parameters of burst encryption and decryption time, end-to-end delay, it was found that RC4 provided better results. This paper looks to provide a better solution for the confidentiality of the burst in OBS networks. PMID:24578663

  19. Are short Gamma Ray Bursts similar to long ones?

    Science.gov (United States)

    Ghirlanda, G.; Bernardini, M. G.; Calderone, G.; D'Avanzo, P.

    2015-09-01

    The apparent separation of short and long Gamma-Ray Bursts (GRBs) in the hardness ratio vs duration plot has been considered as a direct evidence of the difference between these two populations. The origin of this diversity, however, has been only confirmed with larger GRB samples but not fully understood. In particular, the hardness ratio is only a proxy of the shape of the spectra of GRBs and itself, together with the observed duration, does not consider the possible different redshift distribution of short and long bursts, which might arise from their different progenitors' nature. By correcting the spectral shape of short and long GRBs for the redshift effects, short GRBs are harder than long ones due to a harder low energy spectral component while the two populations have similar (rest frame) peak energy. In the rest frame, the temporal break of the long/short duration distribution is blurred away and short and long GRBs have a continuous differential duration distribution. Moreover, they show similar luminosities but their energetics differ by a factor proportional to their different average duration. The spectral evolution of long GRBs shows that the initial phase (of the order of 0.3 s rest frame) has similar spectral properties of that of short GRBs. As a consequence, the different hardness at low energies might be due to a prolonged spectral evolution of long GRBs with respect to short ones. Finally, we show that long GRBs can have a null lag similarly to short bursts. Moreover, we find that a considerable fraction of long (and most of short) GRBs are inconsistent with the lag-luminosity relation which could be a boundary in the corresponding plane, rather than a correlation.

  20. High Energy Neutrino Astrophysics With Super-kamiokande

    CERN Document Server

    Desai, S

    2004-01-01

    This dissertation presents various physics and astronomy results with upward going muons using the first five years of data from the Super-Kamiokande detector, which is a 50 kiloton water Cherenkov detector located in Japan. Upward muons produced by neutrinos interacting in the rock below the detector represent the highest energy neutrinos seen in Super-Kamiokande. Using these events, I have searched for the signatures of annihilations of dark matter particles to high energy neutrinos in the center of Earth, Sun and the Galactic Center. Constraints on dark matter scattering cross- sections with nuclei using these results will be presented. Space-time coincidences from astrophysical transient sources such as gamma-ray bursts and soft gamma-ray repeaters are reported. I have developed an algorithm to isolate a sample of events, called “showering upward going muons”, which lose energy through radiative processes. We shall use this subset, whose parent neutrino energy is approximately 1 TeV, t...

  1. High Energy Processes in Pulsar Wind Nebulae

    CERN Document Server

    Bednarek, W

    2006-01-01

    Young pulsars produce relativistic winds which interact with matter ejected during the supernova explosion and the surrounding interstellar gas. Particles are accelerated to very high energies somewhere in the pulsar winds or at the shocks produced in collisions of the winds with the surrounding medium. As a result of interactions of relativistic leptons with the magnetic field and low energy radiation (of synchrotron origin, thermal, or microwave background), the non-thermal radiation is produced with the lowest possible energies up to $\\sim$100 TeV. The high energy (TeV) gamma-ray emission has been originally observed from the Crab Nebula and recently from several other objects. Recent observations by the HESS Cherenkov telescopes allow to study for the first time morphology of the sources of high energy emission, showing unexpected spectral features. They might be also interpreted as due to acceleration of hadrons. However, theory of particle acceleration in the PWNe and models for production of radiation ...

  2. Experimental and theoretical high energy physics research

    International Nuclear Information System (INIS)

    Progress in the various components of the UCLA High-Energy Physics Research program is summarized, including some representative figures and lists of resulting presentations and published papers. Principal efforts were directed at the following: (I) UCLA hadronization model, PEP4/9 e+e- analysis, bar P decay; (II) ICARUS and astroparticle physics (physics goals, technical progress on electronics, data acquisition, and detector performance, long baseline neutrino beam from CERN to the Gran Sasso and ICARUS, future ICARUS program, and WIMP experiment with xenon), B physics with hadron beams and colliders, high-energy collider physics, and the φ factory project; (III) theoretical high-energy physics; (IV) H dibaryon search, search for KL0 → π0γγ and π0ν bar ν, and detector design and construction for the FNAL-KTeV project; (V) UCLA participation in the experiment CDF at Fermilab; and (VI) VLPC/scintillating fiber R ampersand D

  3. Scientific applications for high-energy lasers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, R.W. [comp.

    1994-03-01

    The convergence of numerous factors makes the time ripe for the development of a community of researchers to use the high-energy laser for scientific investigations. This document attempts to outline the steps necessary to access high-energy laser systems and create a realistic plan to implement usage. Since an academic/scientific user community does not exist in the USA to any viable extent, we include information on present capabilities at the Nova laser. This will briefly cover laser performance and diagnostics and a sampling of some current experimental projects. Further, to make the future possibilities clearer, we will describe the proposed next- generation high-energy laser, named for its inertial fusion confinement (ICF) goal, the multi-megaJoule, 500-teraWatt National Facility, or NIF.

  4. Future high energy colliders symposium. Summary report

    International Nuclear Information System (INIS)

    A 'Future High Energy Colliders' Symposium was held October 21-25, 1996 at the Institute for Theoretical Physics (ITP) in Santa Barbara. This was one of the 3 symposia hosted by the ITP and supported by its sponsor, the National Science Foundation, as part of a 5 month program on 'New Ideas for Particle Accelerators'. The long term program and symposia were organized and coordinated by Dr. Zohreh Parsa of Brookhaven National Laboratory/ITP. The purpose of the symposium was to discuss the future direction of high energy physics by bringing together leaders from the theoretical, experimental and accelerator physics communities. Their talks provided personal perspectives on the physics objectives and the technology demands of future high energy colliders. Collectively, they formed a vision for where the field should be heading and how it might best reach its objectives

  5. Fast Radio Bursts and Radio Transients from Black Hole Batteries

    CERN Document Server

    Mingarelli, Chiara M F; Lazio, T Joseph W

    2015-01-01

    Most black holes (BHs) will absorb a neutron star (NS) companion fully intact, without tidal disruption, suggesting the pair will remain dark to telescopes. Even without tidal disruption, electromagnetic luminosity is generated from the battery phase of the binary when the BH interacts with the NS magnetic field. Originally the luminosity was expected in high-energy X-rays or gamma-rays, however we conjecture that some of the battery power is emitted in the radio bandwidth. While the luminosity and timescale are suggestive of fast radio bursts (FRBs; millisecond-scale radio transients) NS--BH coalescence rates are too low to make these a primary FRB source. Instead, we propose the transients form a FRB sub-population, distinguishable by a double peak with a precursor. The rapid ramp-up in luminosity manifests as a precursor to the burst which is $20\\%-80\\%$ as luminous, given 0.5~ms timing resolution. The main burst is from the peak luminosity before merger. The post-merger burst follows from the NS magnetic ...

  6. Sensitivity of HAWC to Primordial Black Hole Bursts

    CERN Document Server

    Ukwatta, T N; MacGibbon, D Stump J H; Marinelli, S S; Yapici, T; Tollefson, K

    2015-01-01

    Primordial Black Holes (PBHs) are black holes that may have been created in the early Universe and could be as large as supermassive black holes or as small as the Planck scale. It is believed that a black hole has a temperature inversely proportional to its mass and will thermally emit all species of fundamental particles. PBHs with initial masses of 5.0 x 10^14 g should be expiring today with bursts of high-energy gamma radiation in the GeV/TeV energy range. The High Altitude Water Cherenkov (HAWC) observatory is sensitive to the high end of the PBH gamma-ray burst spectrum. Due to its large field of view, duty cycle above 90% and sensitivity up to 100 TeV, the HAWC observatory is well suited to perform a search for PBH bursts. We report that if the PBH explodes within 0.25 light years from Earth and within 26 degrees of zenith, HAWC will have a 95% probability of detecting the PBH burst at the 5 sigma level. Conversely, a null detection from a 2 year or longer HAWC search will set PBH upper limits which ar...

  7. Integral test for JENDL high energy file

    International Nuclear Information System (INIS)

    As activities of the Intermediate and High Energy Nuclear Data Integral Test Working Group in the Japanese Nuclear Data Committee, integral tests of JENDL High Energy File (JENDL-HE) have started. Processing method of JENDL-HE with the NJOY code has been established. As a result of benchmark tests for the 56Fe data in JENDL-HE with the two neutron incident experiments conducted at TIARA and RCNP, calculations with JENDL-HE agreed excellently with the experimental data. The data were found to be adequate for nuclear design calculations as far as the energy range tested, below 68-MeV, was concerned. (author)

  8. On the Future High Energy Colliders

    CERN Document Server

    Shiltsev, Vladimir

    2015-01-01

    High energy particle colliders have been in the forefront of particle physics for more than three decades. At present the near term US, European and international strategies of the particle physics community are centered on full exploitation of the physics potential of the Large Hadron Collider (LHC) through its high-luminosity upgrade (HL-LHC). A number of the next generation collider facilities have been proposed and are currently under consideration for the medium and far-future of accelerator-based high energy physics. In this paper we offer a uniform approach to evaluation of various accelerators based on the feasibility of their energy reach, performance potential and cost range.

  9. High Energy Physics Research at Louisiana Tech

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Lee [Louisiana State Univ., Baton Rouge, LA (United States); Greenwood, Zeno [Louisiana State Univ., Baton Rouge, LA (United States); Wobisch, Marcus [Louisiana State Univ., Baton Rouge, LA (United States)

    2013-06-28

    The goal of this project was to create, maintain, and strengthen a world-class, nationally and internationally recognized experimental high energy physics group at Louisiana Tech University, focusing on research at the energy frontier of collider-based particle physics, first on the DØ experiment and then with the ATLAS experiment, and providing leadership within the US high energy physics community in the areas of jet physics, top quark and charged Higgs decays involving tau leptons, as well as developing leadership in high performance computing.

  10. Elementary particle physics and high energy phenomena

    International Nuclear Information System (INIS)

    Experimental and theoretical high-energy physics programs at the University of Colorado are reported. Areas of concentration include the following: study of the properties of the Z0 with the SLD detector; fixed-target K-decay experiments; the R ampersand D program for the muon system: the SDC detector; high-energy photoproduction of states containing heavy quarks; electron--positron physics with the CLEO II detector at CESR; lattice QCD; and spin models and dynamically triangulated random surfaces. 24 figs., 2 tabs., 117 refs

  11. Looking for High Energy Peaked Blazars

    OpenAIRE

    Costamante, L.; Ghisellini, G.; Celotti, A.; Giommi, P.; Padovani, P.; Tagliaferri, G.; Wolter, A.; Chiaberge, M.; Fossati, G; Pian, E.; L. Maraschi(INAF National Institute for Astrophysics, I-00136 Rome, Italy); Tavecchio, F.; Treves, A.

    2000-01-01

    Blazars can be classified on the basis of their overall Spectral Energy Distribution (SED). BL Lac objects are usually divided in LBL or HBL (Low or High energy peaked BL Lacs), according to the peak frequency of the synchrotron emission, if in the optical or UV-soft-X band respectively. FSRQs instead are characterized by synchrotron peaks mainly at IR-optical frequencies, similarly to LBLs. Here we report on recent BeppoSAX observations which are unveiling the high energy branch of the range...

  12. Beam dynamics in high energy particle accelerators

    CERN Document Server

    Wolski, Andrzej

    2014-01-01

    Particle accelerators are essential tools for scientific research in fields as diverse as high energy physics, materials science and structural biology. They are also widely used in industry and medicine. Producing the optimum design and achieving the best performance for an accelerator depends on a detailed understanding of many (often complex and sometimes subtle) effects that determine the properties and behavior of the particle beam. Beam Dynamics in High Energy Particle Accelerators provides an introduction to the concepts underlying accelerator beam line design and analysis, taking an approach that emphasizes the elegance of the subject and leads into the development of a range of powerful techniques for understanding and modeling charged particle beams.

  13. COMPILATION OF CURRENT HIGH ENERGY PHYSICS EXPERIMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Wohl, C.G.; Kelly, R.L.; Armstrong, F.E.; Horne, C.P.; Hutchinson, M.S.; Rittenberg, A.; Trippe, T.G.; Yost, G.P.; Addis, L.; Ward, C.E.W.; Baggett, N.; Goldschmidt-Clermong, Y.; Joos, P.; Gelfand, N.; Oyanagi, Y.; Grudtsin, S.N.; Ryabov, Yu.G.

    1981-05-01

    This is the fourth edition of our compilation of current high energy physics experiments. It is a collaborative effort of the Berkeley Particle Data Group, the SLAC library, and nine participating laboratories: Argonne (ANL), Brookhaven (BNL), CERN, DESY, Fermilab (FNAL), the Institute for Nuclear Study, Tokyo (INS), KEK, Serpukhov (SERP), and SLAC. The compilation includes summaries of all high energy physics experiments at the above laboratories that (1) were approved (and not subsequently withdrawn) before about April 1981, and (2) had not completed taking of data by 1 January 1977. We emphasize that only approved experiments are included.

  14. High energy experimental physics: Progress report

    International Nuclear Information System (INIS)

    This report contains papers of high energy physics experiments and detector equipment design. Proposals are also given for future experiments. Some of the topics covered in this report are: high energy predictions for /bar char/pp and pp elastic scattering and total cross sections; D0 forward drift chambers; polarized beam facility; analyzing power measurment in inclusive pion production at high transverse momentum; Skyrme model for baryons; string models for color flux tubes; hadronic decays for the /tau/ lepton; and meson form factors in perturbative QCD

  15. Status of High-Energy Neutrino Astronomy

    CERN Document Server

    Kowalski, Marek

    2014-01-01

    With the recent discovery of high-energy neutrinos of extra-terrestrial origin by the IceCube neutrino observatory, neutrino-astronomy is entering a new era. This review will cover currently operating open water/ice neutrino telescopes, the latest evidence for a flux of extra-terrestrial neutrinos and current efforts in the search for steady and transient neutrino point sources. Generalised constraints on potential astrophysical sources are presented, allowing to focus the hunt for the sources of the observed high-energy neutrinos.

  16. FERMI DETECTION OF DELAYED GeV EMISSION FROM THE SHORT GAMMA-RAY BURST 081024B

    International Nuclear Information System (INIS)

    We report on the detailed analysis of the high-energy extended emission from the short gamma-ray burst (GRB) 081024B detected by the Fermi Gamma-ray Space Telescope. Historically, this represents the first clear detection of temporal extended emission from a short GRB. The light curve observed by the Fermi Gamma-ray Burst Monitor lasts approximately 0.8 s whereas the emission in the Fermi Large Area Telescope lasts for about 3 s. Evidence of longer lasting high-energy emission associated with long bursts has been already reported by previous experiments. Our observations, together with the earlier reported study of the bright short GRB 090510, indicate similarities in the high-energy emission of short and long GRBs and open the path to new interpretations.

  17. Adaptive Multi-Lag for Synthetic Aperture Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Jensen, Jørgen Arendt

    2014-01-01

    ulti- lag method, which is performed in synthetic aperture vector flow data. Measurements are made on laminar and pulsatile, transverse flow profiles. A 7 MHz linear array is connected to t he SARUS research, and acquisitions are made on a vessel phanto m with recirculating blood mimicking fluid driven...... by a softwar e controlled pump. A multi-lag velocity estimation is perfor med, and a lag is adaptively selected for every estimation point. Results from the constant flow compared to a true parabolic profile sho w an improvement in relative bias from 76.99% to 0.91% and standard deviation from 13...

  18. The Effect of Jet Lag on Postural Stability

    OpenAIRE

    Mubarak, Faisal Al; Johnson, Eric; Daher, Noha; Gaikwad, Shilpa; Cordett, Tim; Aranda, Heidi

    2016-01-01

    Crossing time zones can disrupt our body clock and lead to jet lag. Some studies reported that jet lag affects human physical and cognitive functions. To the best of the authors’ knowledge, none of these studies examined the effects of jet lag on postural stability. Twenty-two healthy young adult males between 23 and 36 years of age who had a round trip flight planned between the United States and Saudi Arabia were recruited. Participants attended one preflight assessment and three post-fligh...

  19. X-ray Time Lags in TeV Blazars

    Indian Academy of Sciences (India)

    X. Chen; G. Fossati; E. Liang; M. Böttcher

    2011-03-01

    We use Monte Carlo/Fokker–Planck simulations to study the X-ray time lags. Our results show that soft lags will be observed as long as the decay of the flare is dominated by radiative cooling, even when acceleration and cooling time scales are similar. Hard lags can be produced in the presence of a competitive achromatic particle energy loss mechanism if the acceleration process operates on a time scale such that particles are slowly moved towards higher energy while the flare evolves. In this type of scenario, the -ray/X-ray quadratic relation is also reproduced.

  20. Statistical properties of Fourier-based time-lag estimates

    Science.gov (United States)

    Epitropakis, A.; Papadakis, I. E.

    2016-06-01

    Context. The study of X-ray time-lag spectra in active galactic nuclei (AGN) is currently an active research area, since it has the potential to illuminate the physics and geometry of the innermost region (i.e. close to the putative super-massive black hole) in these objects. To obtain reliable information from these studies, the statistical properties of time-lags estimated from data must be known as accurately as possible. Aims: We investigated the statistical properties of Fourier-based time-lag estimates (i.e. based on the cross-periodogram), using evenly sampled time series with no missing points. Our aim is to provide practical "guidelines" on estimating time-lags that are minimally biased (i.e. whose mean is close to their intrinsic value) and have known errors. Methods: Our investigation is based on both analytical work and extensive numerical simulations. The latter consisted of generating artificial time series with various signal-to-noise ratios and sampling patterns/durations similar to those offered by AGN observations with present and past X-ray satellites. We also considered a range of different model time-lag spectra commonly assumed in X-ray analyses of compact accreting systems. Results: Discrete sampling, binning and finite light curve duration cause the mean of the time-lag estimates to have a smaller magnitude than their intrinsic values. Smoothing (i.e. binning over consecutive frequencies) of the cross-periodogram can add extra bias at low frequencies. The use of light curves with low signal-to-noise ratio reduces the intrinsic coherence, and can introduce a bias to the sample coherence, time-lag estimates, and their predicted error. Conclusions: Our results have direct implications for X-ray time-lag studies in AGN, but can also be applied to similar studies in other research fields. We find that: a) time-lags should be estimated at frequencies lower than ≈ 1/2 the Nyquist frequency to minimise the effects of discrete binning of the

  1. A Concept for a High-Energy Gamma-ray Polarimeter

    OpenAIRE

    P. F. BloserNASA/GSFC; Hunter, S D; G. O. Depaola(National University of Cordoba, Argentina); Longo, F.

    2003-01-01

    We present a concept for an imaging gamma-ray polarimeter operating from ~50 MeV to ~1 GeV. Such an instrument would be valuable for the study of high-energy pulsars, active galactic nuclei, supernova remnants, and gamma-ray bursts. The concept makes use of pixelized gas micro-well detectors, under development at Goddard Space Flight Center, to record the electron-positron tracks from pair-production events in a large gas volume. Pixelized micro-well detectors have the poten...

  2. Ultra-high energy cosmic rays clustering, GUT scale and neutrino masses

    CERN Document Server

    Fodor, Z

    2002-01-01

    The clustering of ultra high energy (above 5\\cdot 10^{19} eV) cosmic rays (UHECR) suggests that they might be emitted by compact sources. We present a statistical analysis on the source density based on the multiplicities. The propagation of UHECR protons is studied in detail. The UHECR spectrum is consistent with the decay of GUT scale particles and/or with the Z-burst. The predicted GUT mass is m_X=10^b GeV, where b=14.6_{-1.7}^{+1.6}. Our neutrino mass prediction depends on the origin of the power part of the spectrum: m_\

  3. The second Konus-Wind catalog of short gamma-ray bursts

    CERN Document Server

    Svinkin, D S; Aptekar, R L; Golenetskii, S V; Pal'shin, V D; Oleynik, Ph P; Tsvetkova, A E; Ulanov, M V; Cline, T L; Hurley, K

    2016-01-01

    In this catalog, we present the results of a systematic study of 295 short gamma-ray bursts (GRBs) detected by Konus-Wind (KW) from 1994 to 2010. From the temporal and spectral analyses of the sample, we provide the burst durations, the spectral lags, the results of spectral fits with three model functions, the total energy fluences and the peak energy fluxes of the bursts. We discuss evidence found for an additional power-law spectral component and the presence of extended emission in a fraction of the KW short GRBs. Finally, we consider the results obtained in the context of the Type I (merger-origin) / Type II (collapsar-origin) classifications.

  4. The Second Konus-Wind Catalog of Short Gamma-Ray Bursts

    Science.gov (United States)

    Svinkin, D. S.; Frederiks, D. D.; Aptekar, R. L.; Golenetskii, S. V.; Pal'shin, V. D.; Oleynik, Ph. P.; Tsvetkova, A. E.; Ulanov, M. V.; Cline, T. L.; Hurley, K.

    2016-05-01

    In this catalog, we present the results of a systematic study of 295 short gamma-ray bursts (GRBs) detected by Konus-Wind (KW) from 1994 to 2010. From the temporal and spectral analyses of the sample, we provide the burst durations, the spectral lags, the results of spectral fits with three model functions, the total energy fluences, and the peak energy fluxes of the bursts. We discuss evidence found for an additional power-law spectral component and the presence of extended emission in a fraction of the KW short GRBs. Finally, we consider the results obtained in the context of the Type I (merger-origin)/Type II (collapsar-origin) classifications.

  5. Concept for LEU Burst Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Steven Karl [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kimpland, Robert Herbert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-07

    Design and performance of a proposed LEU burst reactor are sketched. Salient conclusions reached are the following: size would be ~1,500 kg or greater, depending on the size of the central cavity; internal stresses during burst require split rings for relief; the reactor would likely require multiple control and safety rods for fine control; the energy spectrum would be comparable to that of HEU machines; and burst yields and steady-state power levels will be significantly greater in an LEU reactor.

  6. Concept for LEU Burst Reactor

    International Nuclear Information System (INIS)

    Design and performance of a proposed LEU burst reactor are sketched. Salient conclusions reached are the following: size would be ~1,500 kg or greater, depending on the size of the central cavity; internal stresses during burst require split rings for relief; the reactor would likely require multiple control and safety rods for fine control; the energy spectrum would be comparable to that of HEU machines; and burst yields and steady-state power levels will be significantly greater in an LEU reactor.

  7. Observations of Gamma-ray Bursts in the Fermi era

    CERN Document Server

    Vianello, Giacomo

    2013-01-01

    The Fermi observatory, with its Gamma-Ray Bursts monitor (GBM) and Large Area Telescope (LAT), is observing Gamma-ray Bursts with unprecedented spectral coverage and sensitivity, from ~10 keV to > 300 GeV. In the first 3 years of the mission it observed emission above 100 MeV from 35 GRBs, an order of magnitude gain with respect to previous observations in this energy range. In this paper we review the main results obtained on such sample, highlighting also the relationships with the low-energy features (as measured by the GBM), and with measurements from observatories at other wavelengths. We also briefly discuss prospects for detection of GRBs by future Very-High Energy observatories such as HAWC and CTA, and by Gravitational Wave experiments.

  8. THE BATSE 5B GAMMA-RAY BURST SPECTRAL CATALOG

    International Nuclear Information System (INIS)

    We present systematic spectral analyses of gamma-ray bursts (GRBs) detected with the Burst and Transient Source Experiment (BATSE) on board the Compton Gamma-Ray Observatory during its entire nine years of operation. This catalog contains two types of spectra extracted from 2145 GRBs, and fitted with five different spectral models resulting in a compendium of over 19,000 spectra. The models were selected based on their empirical importance to the spectral shape of many GRBs, and the analysis performed was devised to be as thorough and objective as possible. We describe in detail our procedures and criteria for the analyses, and present the bulk results in the form of parameter distributions. This catalog should be considered an official product from the BATSE Science Team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center (HEASARC)

  9. Physics of Gamma-Ray Bursts Prompt Emission

    CERN Document Server

    Pe'er, Asaf

    2015-01-01

    In recent years, our understanding of gamma-ray bursts (GRB) prompt emission has been revolutionized, due to a combination of new instruments, new analysis methods and novel ideas. In this review, I describe the most recent observational results and the current theoretical interpretation. Observationally, a major development is the rise of time-resolved spectral analysis. These led to (I) identification of a distinguished high energy component, with GeV photons often seen at a delay; and (II) firm evidence for the existence of a photospheric (thermal) component in a large number of bursts. These results triggered many theoretical efforts aimed at understanding the physical conditions in the inner jet regions from which the prompt photons are emitted, as well as the spectral diversity observed. I highlight some areas of active theoretical research. These include: (I) understanding the role played by magnetic fields in shaping the dynamics of GRB outflow and spectra; (II) understanding the microphysics of kinet...

  10. High-energy transients with Fermi/GBM

    International Nuclear Information System (INIS)

    For most of mankind's history, astronomy was performed on-ground in the optical energy range. It was only when space-based missions, built more than 50 years ago, detected photons with mind-boggling energies that the exploration of the violent Universe really began. These γ-ray photons still provide us with an unprecedented wealth of information for the most energetic processes taking place in the cosmos. Faithful to the olympic slogan ''higher, faster, further'', an increasing armada of γ-ray satellites was built and launched over the last couple of decades with Fermi being the youngest of its kind. In this thesis, I use data from the Gamma-Ray Burst Monitor (GBM) onboard the Fermi satellite. The focus of this work lies on three very different classes of high-energy astrophysical transients: Gamma-Ray Bursts (GRBs), solar flares and Soft Gamma Repeaters (SGRs). In Chapter 2, I present GRB 091024A, a burst of very long duration in γ-rays where optical data could be acquired well during its active phase. The optical light curve shows very intriguing features which I subsequently interpret as the so called ''optical flash'', a fundamental property of the ''fireball'' model. Although predicted by the latter model, only a handful of GRBs show such a behavior, making them interesting transients to study. Furthermore, I present the fundamental temporal and spectral properties of 47 GBM-detected GRBs with known redshifts. As GRBs explode at cosmological distances it is of uttermost importance to study them in their restframe to get a better understanding of their emission mechanisms. I confirm several correlations already found in the past together with an intriguing connection between redshift and the peak energy (Epeak) of GRBs. Although this correlation is heavily influenced by instrumental effects, it is not unexpected from other experimental results, giving it more credibility. Finally, I present the results of the search for untriggered GRBs in GBM data. This

  11. Interference Resilience of Burst-by-burst Adaptive Modems

    OpenAIRE

    Torrance, J.M.; Hanzo, L.; Keller, T

    1997-01-01

    Adaptive modulation can achieve channel capacity gains by adapting t h e number of bits per transmission symbol on a burst-by-burst basis, in harmony with channel quality fluctuations. In this treatise their interference resilience is quantified and the modem mode switching levels are determined under interfered conditions. The associated performance curves are portrayed in Figures 6, 7 and 8 for target bit error rates of 1 and 0.01 %, respectively. The corresponding modem mode switching leve...

  12. Analysis of Burst Assembly Modeling for Optical Burst Switched Network

    Directory of Open Access Journals (Sweden)

    Bhumika Patel

    2013-11-01

    Full Text Available In this paper, we have study the current state of the technology, the Optical burst Switched (OBS network is the most practical in all-optical architecture. Here we define how Burst Assembly will carried out and also here in the network architecture each node is consist of Core router and Edge router. Moreover we define challenges faced at practical implementation of OBS and proposed its unique solution at the node as Delay model.

  13. Astrophysics, cosmology and high energy physics

    International Nuclear Information System (INIS)

    A brief survey is given of some topics in astrophysics and cosmology, with special emphasis on the inter-relation between the properties of the early Universe and recent ideas in high energy physics, and on simple order-of-magnitude arguments showing how the scales and dimensions of cosmic phenomena are related to basic physical constants. (orig.)

  14. DOE is Funding Young High- Energy Physicists

    Science.gov (United States)

    Waff, Craig B.

    1978-01-01

    Reports on some recommendations made by a subpanel on High Energy Physics Manpower for the purpose of employing additional physicists through the transfer of some postdoctoral monies to produce long-term positions, and the creation of a five-year national fellowship program. (GA)

  15. Theoretical and experimental high energy physics

    International Nuclear Information System (INIS)

    This report discusses experimental and theoretical work in High Energy Physics. Some topics discussed are: quantum field theory; supersymmetry; cosmology; superstring model; relic photinos; inflationary universe; dark matter; standard model; supernovae; semileptonic decay; quantum Langevin equation; underground neutrino detection at Soudan; strange quark systems; cosmic ray detection; superconducting super collider detectors; and studies of direct photon production

  16. HIGH ENERGY PHYSICS POTENTIAL AT MUON COLLIDERS

    Energy Technology Data Exchange (ETDEWEB)

    PARSA,Z.

    2000-04-07

    In this paper, high energy physics possibilities and future colliders are discussed. The {mu}{sup +} {mu}{sup {minus}} collider and experiments with high intensity muon beams as the stepping phase towards building Higher Energy Muon Colliders (HEMC) are briefly reviewed and encouraged.

  17. Wigner Functions in High Energy Physics

    CERN Document Server

    Csörgö, T

    2004-01-01

    Recent developments are (meta)reviewed in the applications of Wigner functions to describe the observed single particle spectra and two-particle Bose-Einstein (or Hanbury Brown -- Twiss) correlations in high energy particle and nuclear physics, with examples from hadron-proton and Pb + Pb collisions at CERN SPS.

  18. Indiana University High Energy Physics, Task A

    International Nuclear Information System (INIS)

    This report discusses research in High Energy Physics under the following experiments: Meson spectroscopy at BNL; dimuon production at FNAL; the DO collider experiment at FNAL; the Mark II experiment at SLC and PEP; the OPAL experiment at CERN; and the superconducting supercollider

  19. Indiana University High Energy Physics, Task A

    International Nuclear Information System (INIS)

    This report discusses research at Indians University on the following high energy physics experiments: A search for mesons with unusual quantum numbers; hadronic states produced in association with high-mass dimuons; FNAL E740 (D0); superconducting super collider; and OPAL experiment at CERN

  20. Phenomenology of extragalactic high energy sources

    International Nuclear Information System (INIS)

    The course is divided in two main bodies: Chapters 1 and 2 deal with some of the fundamental properties of the production of high energy radiation, while chapter 3 is devoted to the observations of active galaxies; chapter 4 presents the X-ray emission of clusters of galaxies and the sky background

  1. Quark deconfinement and high energy nuclear collisions

    International Nuclear Information System (INIS)

    Statistical QCD predicts that with increasing density, strongly interacting matter will undergo a transition to a plasma of deconfined quarks and gluons. High energy heavy ion collisions are expected to permit experimental studies of this transition and of the predicted new state of matter. 22 refs., 6 figs

  2. ACCELERATION FOR A HIGH ENERGY MUON COLLIDER

    International Nuclear Information System (INIS)

    The authors describe a method for designing the acceleration systems for a muon collider, with particular application and examples for a high energy muon collider. This paper primarily concentrates on design considerations coming from longitudinal motion, but some transverse issues are briefly discussed

  3. Density Estimation Trees in High Energy Physics

    CERN Document Server

    Anderlini, Lucio

    2015-01-01

    Density Estimation Trees can play an important role in exploratory data analysis for multidimensional, multi-modal data models of large samples. I briefly discuss the algorithm, a self-optimization technique based on kernel density estimation, and some applications in High Energy Physics.

  4. On high energy scattering inside gravitational backgrounds

    OpenAIRE

    Nastase, Horatiu

    2004-01-01

    We analyze the high energy scattering inside gravitational backgrounds using 't Hooft's formalism. The scattering is equivalent to geodesic shifts accross Aichelburg-Sexl waves inside the gravitational backgrounds. We find solutions for A-S waves inside various backgrounds and analyze them.

  5. Neutrino physics at very high energies

    Energy Technology Data Exchange (ETDEWEB)

    Sciulli, F.; Barish, B.; Ford, W.; Oddone, P.; Peck, C.; /Caltech; Maschke, A.; /Fermilab; Barish, B.; /Caltech

    1970-06-01

    NAL presents the opportunity to expand our knowledge of neutrino interactions from energies of less than 10 GeV up to more than 300 GeV. We propose an exploratory experiment which is designed to emphasize the physics of very high energy interactions ({approx}300 GeV).

  6. SPACE: More high energy gamma sources

    International Nuclear Information System (INIS)

    Ultra high energy (TeV) gamma rays have been observed by an international team working at the Whipple observatory in Arizona. These also correlate with some of the signals seen by NASA's big Gamma Ray Observatory (GRO) satellite launched by the Space Shuttle Atlantis last year

  7. The interaction region of high energy protons

    OpenAIRE

    Dremin, I. M.; White, S. N.

    2016-01-01

    The spatial view of the interaction region of colliding high energy protons (in terms of impact parameter) is considered. It is shown that the region of inelastic collisions has a very peculiar shape. It saturates for central collisions at an energy of 7 TeV. We speculate on the further evolution with energy, which is contrasted to the "black disk" picture.

  8. Deep underground intensities of high energy muons

    International Nuclear Information System (INIS)

    The experiment of the deep underground emulsion chamber has been started in order to measure the energy spectra of muons deep underground at high energies. Preliminary results based on the emulsion chamber with 0.9 ton of lead are presented. This test exposure has been performed at the vertical depth of 850 hg/cm2 underground in the road tunnel. (orig.)

  9. Ultra- and extremely high energy neutrino astronomy

    OpenAIRE

    I. SokalskiINFN, Bari

    2014-01-01

    Scientific motivations for ultra- and extremely high energy neutrino astronomy are considered. Sources and expected fluxes of EHE/UHE neutrinos are briefly discussed. Operating and planned experiments on astrophysical neutrino detection are reviewed focusing on deep underwater/ice Cherenkov neutrino telescopes.

  10. High-Energy Gamma and Neutrino Astronomy

    OpenAIRE

    Bergstrom, L.

    1997-01-01

    An overview is given of high-energy gamma-ray and neutrino astronomy, emphasizing the links between the two fields. With several new large detectors just becoming operational, the TeV gamma-ray and neutrino sky will soon be surveyed with unprecedented sensitivity.

  11. SU(5) at very high energies

    International Nuclear Information System (INIS)

    By exhibiting the relationship between the full SU(5) theory in the unitary gauge and the underlying Higgs-Goldstone system in the t'Hooft-Feynman gauge the high energy limits of amplitudes (involving gauge and Higgs bosons) can be calculated easily. As an application tree unitarity bounds on Higgs parameters and masses are discussed. (Author)

  12. Studies in theorectical high energy particles physics

    International Nuclear Information System (INIS)

    This paper discusses the research being done at the University of Illinois in theoretical high energy physics. Some areas discussed are string models, collider physics, symmetries in gauge theories, sigma model, radiative decay of mesons, supersymmetry, superconducting, and hydroproduction of charm

  13. Theoretical and experimental high energy physics

    International Nuclear Information System (INIS)

    This report discusses the following topics: The Soudan enterprise; study of strange quarks at Fermilab; direct photons at Fermilab; the Brookhaven programs; AMY and CLEO: studies of e+e- annihilations; cosmic ray studies with the DO muon chamber; progress report on HEP computer upgrade; muon triggering and reconstruction at SSC; and, theoretical high energy physics

  14. PC database for high energy preprint collections

    International Nuclear Information System (INIS)

    We describe a microcomputer database used by the high energy group to keep track of preprints in our collection. It is used as a supplement to the SLAC-SPIRES database to retrieve preprints on hand. This was designed as a low overhead system for a small group

  15. Wigner Functions in High Energy Physics

    OpenAIRE

    Csorgo, T.

    2003-01-01

    Recent developments are (meta)reviewed in the applications of Wigner functions to describe the observed single particle spectra and two-particle Bose-Einstein (or Hanbury Brown -- Twiss) correlations in high energy particle and nuclear physics, with examples from hadron-proton and Pb + Pb collisions at CERN SPS.

  16. Resume: networking in high energy physics

    International Nuclear Information System (INIS)

    Networking in High Energy Physics covers communications inside the experiment and internationally. Inside the experiment the need for agreed 'codes of practice' is now accepted. Within Europe it is accepted that a common infrastructure based on the use of the ISO OSI protocols should be used. In the USA a community initiative has been proposed. The background to these approaches is discussed. (author)

  17. Extra galactic sources of high energy neutrinos

    CERN Document Server

    Waxman, E

    2005-01-01

    The main goal of the construction of large volume, high energy neutrino telescopes is the detection of extra-Galactic neutrino sources. The existence of such sources is implied by observations of ultra-high energy, >10^{19} eV, cosmic-rays (UHECRs), the origin of which is a mystery. The observed UHECR flux sets an upper bound to the extra-Galactic high energy neutrino intensity, which implies that the detector size required to detect the signal in the energy range of 1 TeV to 1 PeV is >=1 giga-ton, and much larger at higher energy. Optical Cerenkov neutrino detectors, currently being constructed under ice and water, are expected to achieve 1 giga-ton effective volume for 1 TeV to 1 PeV neutrinos. Coherent radio Cerenkov detectors (and possibly large air-shower detectors) will provide the >> 1 giga-ton effective volume required for detection at ~10^{19} eV. Detection of high energy neutrinos associated with electromagnetically identified sources will allow to identify the sources of UHECRs, will provide a uniq...

  18. AFM phase lag mapping for protein-DNA oligonucleotide complexes

    International Nuclear Information System (INIS)

    Atomic force microscope phase lag imaging of protein-DNA oligonucleotide complexes has been performed to visualize the immobilized oligonucleotides on the protein surface. In normal sample conditions, neither the topographic nor phase lag images show any discriminate signals for the immobilized oligonucleotides. Use of a highly humid incubator, controls the surface humidity of the sample. Thereby, the phase lag image reveals the oligonucleotide location by the local difference of tip adhesion distribution. The resultant phase lag image shows extremely strong signals in the center of the protein surface, indicating the location of the oligonucleotides with resolution better than 20 nm. The signal frequency was strongly influenced by the used oligonucleotide concentration in the range 5 nM-50 μM

  19. Temperature lags of luminescence measurements in a commercial luminescence reader

    Energy Technology Data Exchange (ETDEWEB)

    Kitis, George [Aristotle University of Thessaloniki, Nuclear Physics Laboratory, 54124 Thessaloniki (Greece); Kiyak, Nafiye G. [ISIK University, Faculty of Science and Arts, Physics Department, Sile, 34980 Istanbul (Turkey); Polymeris, George S., E-mail: gspolymeris@ankara.edu.tr [Ankara University, Institute of Nuclear Sciences, Beşevler, 06100 Ankara (Turkey)

    2015-09-15

    The temperature recorded in thermoluminescence and optically stimulated luminescence equipments is not the temperature of the sample but that of the heating element on which the thermocouple is attached. Depending upon the rate of heating, a temperature difference appears between the samples and the heating element, termed as temperature lag, which could have serious effects on the curve shapes and trapping parameters. In the present work the temperature lag effect is studied in a newly developed luminescence equipment measuring both thermoluminescence and optically stimulated luminescence. It is found that the temperature lag could be large for heating rates above 2 K/s and it is strongly dependent upon the sample holder. A simple approximation method is proposed in order to both predict as well as correct for temperature lag effects in luminescence measurements.

  20. Southern States Lagging in Tough Smoking Bans, CDC Says

    Science.gov (United States)

    ... 159529.html Southern States Lagging in Tough Smoking Bans, CDC Says Only 6 in 10 Americans covered ... federal government report says. This type of law bans smoking in all indoor areas of workplaces, restaurants ...

  1. Temperature lags of luminescence measurements in a commercial luminescence reader

    International Nuclear Information System (INIS)

    The temperature recorded in thermoluminescence and optically stimulated luminescence equipments is not the temperature of the sample but that of the heating element on which the thermocouple is attached. Depending upon the rate of heating, a temperature difference appears between the samples and the heating element, termed as temperature lag, which could have serious effects on the curve shapes and trapping parameters. In the present work the temperature lag effect is studied in a newly developed luminescence equipment measuring both thermoluminescence and optically stimulated luminescence. It is found that the temperature lag could be large for heating rates above 2 K/s and it is strongly dependent upon the sample holder. A simple approximation method is proposed in order to both predict as well as correct for temperature lag effects in luminescence measurements

  2. Correlation of high energy muons with primary composition in extensive air shower

    Science.gov (United States)

    Chou, C.; Higashi, S.; Hiraoka, N.; Ozaki, S.; Sato, T.; Suwada, T.; Takahasi, T.; Umeda, H.

    1985-01-01

    An experimental investigation of high energy muons above 200 GeV in extensive air showers has been made for studying high energy interaction and primary composition of cosmic rays of energies in the range 10 to the 14th power approx. 10 to the 15th power eV. The muon energies are estimated from the burst sizes initiated by the muons in the rock, which are measured by four layers of proportional counters, each of area 5 x 2.6 sq m, placed at 30 m.w.e. deep, Funasaka tunnel vertically below the air shower array. These results are compared with Monte Carlo simulations based on the scaling model and the fireball model for two primary compositions, all proton and mixed.

  3. High energy neutrinos from choked GRBs and their flavor ratio measurement by the IceCube

    International Nuclear Information System (INIS)

    The high energy neutrinos produced in a choked gamma-ray burst can undergo matter oscillation before emerging out of the stellar envelope. Before reaching the detector on Earth, these neutrinos can undergo further vacuum oscillation and then Earth matter oscillation when crossing the diameter of the Earth. In the context of IceCube we study the Earth matter effect on neutrino flux in the detector. For the calculation of the track-to-shower ratio R in the IceCube, we have included the shadowing effect and the additional contribution from the muon track produced by the high energy tau lepton decay in the vicinity of the detector. We observed that R is different for different CP phases in vacuum but the matter effect suppresses these differences. We have also studied the behavior of R when the spectral index α varies. (orig.)

  4. High-energy air shock study in steel and grout pipes

    International Nuclear Information System (INIS)

    Voitenko compressors are used to generate 43 mm/μs air shocks in both a steel and a grout outlet pipe containing ambient atmospheric air. Fiber-optic ports provide diaphragm burst times, time-of-arrival (TOA) data, and velocities for the shock front along the 20-mm-ID exit pipes. Pressure profiles are obtained at higher enthalpy shock propagation than ever before and at many locations along the exit pipes. Numerous other electronic sensors and postshot observations are described, as well as experimental results. The primary objectives of the experiments are as follows: (1) provide a data base for normalization/improvement of existing finite-difference codes that describe high-energy air shocks and gas propagation; (2) obtain quantitative results on the relative attenuation effects of two very different wall materials for high-energy air shocks and gas flows. The extensive experimental results satisfy both objectives

  5. High-energy air shock study in steel and grout pipes

    Energy Technology Data Exchange (ETDEWEB)

    Glenn, H.D.; Kratz, H.R.; Keough, D.D.; Duganne, D.A.; Ruffner, D.J.; Swift, R.P.; Baum, D.

    1979-10-05

    Voitenko compressors are used to generate 43 mm/..mu..s air shocks in both a steel and a grout outlet pipe containing ambient atmospheric air. Fiber-optic ports provide diaphragm burst times, time-of-arrival (TOA) data, and velocities for the shock front along the 20-mm-ID exit pipes. Pressure profiles are obtained at higher enthalpy shock propagation than ever before and at many locations along the exit pipes. Numerous other electronic sensors and postshot observations are described, as well as experimental results. The primary objectives of the experiments are as follows: (1) provide a data base for normalization/improvement of existing finite-difference codes that describe high-energy air shocks and gas propagation; (2) obtain quantitative results on the relative attenuation effects of two very different wall materials for high-energy air shocks and gas flows. The extensive experimental results satisfy both objectives.

  6. Can regional policy affect firms' innovation potential in lagging regions?

    OpenAIRE

    Amnon Frenkel

    2000-01-01

    The initiation of innovation in lagging regions has become one of the most pressing issues in regional policy. Several studies have attempted to identify the factors that influence the creation and development of product innovation in firms located in lagging regions. The identification of these factors could assist regional decision-makers in promoting technological innovation in such regions. The research question investigated in this study is whether the effectiveness of such regional poli...

  7. An empirical explanation of the flash-lag effect

    OpenAIRE

    Wojtach, William T.; Sung, Kyongje; Truong, Sandra; Purves, Dale

    2008-01-01

    When a flash of light is presented in physical alignment with a moving object, the flash is perceived to lag behind the position of the object. This phenomenon, known as the flash-lag effect, has been of particular interest to vision scientists because of the challenge it presents to understanding how the visual system generates perceptions of objects in motion. Although various explanations have been offered, the significance of this effect remains a matter of debate. Here, we show that: (i)...

  8. The phase lag of temperature behind global solar radiation

    International Nuclear Information System (INIS)

    This paper presented the relationship between the air temperature and the global solar radiation, which can be conveniently represented by the three characteristics: mean, amplitude and phase lag of the first harmonic of global radiation and air temperatures. A good correlation between the air temperature and the global solar radiation has been found when the phase lag between them is nearly of 30 days. (author). 4 refs, 9 figs, 1 tab

  9. The Lag in Effect of Inflation Targeting and Policy Evaluation

    OpenAIRE

    WenShwo Fang; Miller, Stephen M.

    2010-01-01

    The lag in effect of monetary policy contains vital information for the policy evaluation. Allowing for a time-varying treatment effect, we show that inflation targeting effectively lowers inflation for both developed and developing countries. Developed countries reach their targets rapidly with a two-year lag in effect. Developing countries, however, reduce inflation gradually toward their targets and do not reach their ultimate goal by the end year of 2007.

  10. FERMIGBRST - Fermi GBM Burst Catalog

    Data.gov (United States)

    National Aeronautics and Space Administration — This table lists all of the triggers observed by a subset of the 14 GBM detectors (12 NaI and 2 BGO) which have been classified as gamma-ray bursts (GRBs). Note...

  11. SWIFT and BATSE bursts' classification

    CERN Document Server

    Horvath, I; Balazs, L G; Tusnady, G; Veres, P

    2009-01-01

    Two classes of gamma-ray bursts were identified in the BATSE catalogs characterized by their durations. There were also some indications for the existence of a third type of gamma-ray bursts. Swift satellite detectors have different spectral sensitivity than pre-Swift ones for GRBs. Therefore in this paper we analyze the bursts' duration distribution and also the duration-hardness bivariate distribution, published in The First BAT Catalog. Similarly to the BATSE data, to explain the BAT GRBs' duration distribution three components are needed. Although, the relative frequencies of the groups are different than they were in the BATSE GRB sample, the difference in the instrument spectral sensitivities can explain this bias in a natural way. This means theoretical models may have to explain three different type of gamma-ray bursts.

  12. Discovery of Fourier-dependent time lags in cataclysmic variables

    CERN Document Server

    Scaringi, S; Groot, P J; Uttley, P; Marsh, T; Knigge, C; Maccarone, T; Dhillon, V S

    2013-01-01

    We report the first study of Fourier-frequency-dependent coherence and phase/time lags at optical wavelengths of cataclysmic variables (MV Lyr and LU Cam) displaying typical flickering variability in white light. Observations were performed on the William Herschel Telescope using ULTRACAM. Lightcurves for both systems have been obtained with the SDSS filters $u'$, $g'$ and $r'$ simultaneously with cadences between $\\approx0.5-2$ seconds, and allow us to probe temporal frequencies between ~10^{-3} Hz and ~1 Hz. We find high levels of coherence between the u', g' and r' lightcurves up to at least ~10^{-2} Hz. Furthermore we detect red/negative lags where the redder bands lag the bluer ones at the lowest observed frequencies. For MV Lyr time lags up to ~3 seconds are observed, whilst LU Cam displays larger time lags of ~10 seconds. Mechanisms which seek to explain red/negative lags observed in X-ray binaries and Active Galactic Nuclei involve reflection of photons generated close to the compact object onto the s...

  13. Disinhibition Bursting of Dopaminergic Neurons

    Directory of Open Access Journals (Sweden)

    Collin J Lobb

    2011-05-01

    Full Text Available Substantia nigra pars compacta (SNpc dopaminergic neurons receive strong tonic inputs from GABAergic neurons in the substantia nigra pars reticulata (SNpr and globus pallidus (GP, and glutamatergic neurons in the subthalamic nucleus. The presence of these tonic inputs raises the possibility that phasic disinhibition may trigger phasic bursts in dopaminergic neurons. We first applied constant NMDA and GABAA conductances onto a two-compartment single cell model of the dopaminergic neuron (Kuznetsov et al., 2006. The model exhibited disinhibition bursting upon stepwise removal of inhibition. A further bifurcation analysis suggests that disinhibition may be more robust than excitation alone in that for most levels of NMDA conductance, the cell remains capable of bursting even after a complete removal of inhibition, whereas too much excitatory input will drive the cell into depolarization block. To investigate the network dynamics of disinhibition, we used a modified version of an integrate-and-fire based model of the basal ganglia (Humphries et al., 2006. Synaptic activity generated in the network was delivered to the two-compartment single cell dopaminergic neuron. Phasic activation of the D1-expressing medium spiny neurons in the striatum (D1STR produced disinhibition bursts in dopaminergic neurons through the direct pathway (D1STR to SNpr to SNpc. Anatomical studies have shown that D1STR neurons have collaterals that terminate in GP. Adding these collaterals to the model, we found that striatal activation increased the intra-burst firing frequency of the disinhibition burst as the weight of this connection was increased. Our studies suggest that striatal activation is a robust means by which disinhibition bursts can be generated by SNpc dopaminergic neurons, and that recruitment of the indirect pathway via collaterals may enhance disinhibition bursting.

  14. Chimera states in bursting neurons

    OpenAIRE

    Bera, Bidesh K.; Ghosh, Dibakar; Lakshmanan, M.

    2015-01-01

    We study the existence of chimera states in pulse-coupled networks of bursting Hindmarsh-Rose neurons with nonlocal, global and local (nearest neighbor) couplings. Through a linear stability analysis, we discuss the behavior of stability function in the incoherent (i.e. disorder), coherent, chimera and multi-chimera states. Surprisingly, we find that chimera and multi-chimera states occur even using local nearest neighbor interaction in a network of identical bursting neurons alone. This is i...

  15. Use of water-Cherenkov detectors to detect Gamma Ray Bursts at the Large Aperture GRB Observatory (LAGO)

    International Nuclear Information System (INIS)

    The Large Aperture GRB Observatory (LAGO) project aims at the detection of high energy photons from Gamma Ray Bursts (GRB) using the single particle technique in ground-based water-Cherenkov detectors (WCD). To reach a reasonable sensitivity, high altitude mountain sites have been selected in Mexico (Sierra Negra, 4550 m a.s.l.), Bolivia (Chacaltaya, 5300 m a.s.l.) and Venezuela (Merida, 4765 m a.s.l.). We report on detector calibration and operation at high altitude, search for bursts in 4 months of preliminary data, as well as search for signal at ground level when satellites report a burst

  16. Burst Suppression: A Review and New Insights

    OpenAIRE

    Jonathan Dillon Kenny; M. Brandon Westover; ShiNung Ching; Brown, Emery N.; Ken Solt

    2014-01-01

    Burst suppression is a pattern of brain electrical activity characterized by alternating periods of high-amplitude bursts and electrical silence. Burst suppression can arise from several different pathological conditions, as well as from general anesthesia. Here we review current algorithms that are used to quantify burst suppression, its various etiologies, and possible underlying mechanisms. We then review clinical applications of anesthetic-induced burst suppression. Finally, we report the...

  17. Mining Gamma-Ray Burst Data

    OpenAIRE

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

    2000-01-01

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

  18. Search for Ultra-High Energy Tau Neutrinos in IceCube

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Dawn

    2014-08-15

    The IceCube Neutrino Observatory at the geographic South Pole was designed with the primary goal of discovering high energy neutrinos from astrophysical objects such as active galactic nuclei and gamma ray bursts. IceCube completed construction in 2010 and has been collecting data throughout the construction phase. IceCube is sensitive to all three flavors of neutrinos, each of which has a distinct topological signature within the detector. At sufficiently high energies, the tau neutrino signature is a “double bang” from the charged current interaction of the neutrino and the decay of the tau lepton. At high energies, the tau neutrino has negligible background and would be an intriguing astrophysical signature. A dedicated search for ultra-high energy tau neutrinos (340 TeV–200 PeV) was performed using data from the partial IceCube detector, yielding a 90% CL upper limit of E{sub ν}{sup 2}Φ{sub 90}(ν{sub x})<16.3×10{sup −8}GeVcm{sup −2}sr{sup −1}s{sup −1} on a diffuse astrophysical flux of UHE neutrinos.

  19. Search for Ultra-High Energy Tau Neutrinos in IceCube

    International Nuclear Information System (INIS)

    The IceCube Neutrino Observatory at the geographic South Pole was designed with the primary goal of discovering high energy neutrinos from astrophysical objects such as active galactic nuclei and gamma ray bursts. IceCube completed construction in 2010 and has been collecting data throughout the construction phase. IceCube is sensitive to all three flavors of neutrinos, each of which has a distinct topological signature within the detector. At sufficiently high energies, the tau neutrino signature is a “double bang” from the charged current interaction of the neutrino and the decay of the tau lepton. At high energies, the tau neutrino has negligible background and would be an intriguing astrophysical signature. A dedicated search for ultra-high energy tau neutrinos (340 TeV–200 PeV) was performed using data from the partial IceCube detector, yielding a 90% CL upper limit of Eν2Φ90(νx)<16.3×10−8GeVcm−2sr−1s−1 on a diffuse astrophysical flux of UHE neutrinos

  20. Gamma-ray bursts and collisionless shocks

    Science.gov (United States)

    Waxman, E.

    2006-12-01

    Particle acceleration in collisionless shocks is believed to be responsible for the production of cosmic-rays over a wide range of energies, from a few GeV to > 1020 eV, as well as for the non-thermal emission of radiation from a wide variety of high energy astrophysical sources. A theory of collisionless shocks based on first principles does not, however, exist. Observations of γ-ray burst (GRB) 'afterglows' provide a unique opportunity for diagnosing the physics of relativistic collisionless shocks. Most GRBs are believed to be associated with explosions of massive stars. Their 'afterglows', delayed low energy emission following the prompt burst of γ-rays, are well accounted for by a model in which afterglow radiation is due to synchrotron emission of electrons accelerated in relativistic collisionless shock waves driven by the explosion into the surrounding plasma. Within the framework of this model, some striking characteristics of collisionless relativistic shocks are implied. These include the generation of downstream magnetic fields with energy density exceeding that of the upstream field by ~8 orders of magnitude, the survival of this strong field at distances ~1010 skin-depths downstream of the shock and the acceleration of particles to a power-law energy spectrum, d log n/d logɛ ap -2, possibly extending to 1020 eV. I review in this talk the phenomenological considerations, based on which these characteristics are inferred, and the challenges posed to our current models of particle acceleration and magnetic field generation in collisionless shocks. Some recent theoretical results derived based on the assumption of a self-similar shock structure are briefly discussed. Invited review presented at the 33rd annual European Physical Society Conference, Rome, 2006.

  1. Observing Gamma Ray Bursts with the RHESSI satellite

    International Nuclear Information System (INIS)

    The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) was launched successfully on the 5th of February 2002 into a low Earth orbit. It is a NASA Small Explorer satellite designed to study hard X-rays and gamma-rays from solar flares. In addition, its lightly shielded array of 9 germanium detectors can see photons from high-energy sources throughout the Universe, in particular also from Gamma Ray Bursts (GRBs). With its wide field of view, RHESSI observes about one GRB per week, the sensitive energy band ranging from about 30 keV to 15 MeV. By presenting preliminary lightcurves and raw spectra from three very strong GRBs observed with RHESSI we demonstrate its high time and energy resolution. Since the arrival time and energy of each photon is recorded, combined time/energy studies, e.g. time dependent hardness ratios, can be studied

  2. High energy physics at UC Riverside

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-07-01

    This report discusses progress made for the following two tasks: experimental high energy physics, Task A, and theoretical high energy physics, Task B. Task A1 covers hadron collider physics. Information for Task A1 includes: personnel/talks/publications; D0: proton-antiproton interactions at 2 TeV; SDC: proton-proton interactions at 40 TeV; computing facilities; equipment needs; and budget notes. The physics program of Task A2 has been the systematic study of leptons and hadrons. Information covered for Task A2 includes: personnel/talks/publications; OPAL at LEP; OPAL at LEP200; CMS at LHC; the RD5 experiment; LSND at LAMPF; and budget notes. The research activities of the Theory Group are briefly discussed and a list of completed or published papers for this period is given.

  3. Origin of the universe and high energy

    International Nuclear Information System (INIS)

    In this book it is briefly exposed what it is done in the world in relation with the high energy physics. Also, it is presented a brief historical description of the earth evolution, the universe and physics in general. This book counts with eight chapters. The first chapter deals with the relationship of man with science. The second chapter speaks about the origin of universe. The third chapter comments about the stars and galaxies formation. The fourth chapter treats how the scientists and researchers continue to studying the subnuclear world. The fifth chapter deals with subjects and models of nuclear physics. In the sixth chapter it is described the function of the particles accelerator. The seventh chapter comments about the multidisciplinary aspects of the research of elementary particles. Finally, the eighth chapter deals with the advances of high energy physics in the andean region of Latin America. (author)

  4. Identifying the nature of high energy Astroparticles

    CERN Document Server

    Mora, Karen Salomé Caballero

    2016-01-01

    High energy Astroparticles include Cosmic Ray, gamma ray and neutrinos, all of them coming from the universe. The origin and production, acceleration and propagation mechanisms of ultrahigh-energy CR (up to $10^{20}$ eV) are still unknown. Knowledge on particle interactions taking place at those energies, useful for studying current theories on particle physics, can be obtained only from measurements of high energy astroparticles. In the present document some techniques on data analysis of mass composition of UHECR with the Pierre Auger Observatory are described. The relevance of the muon component of air showers produced by the primary CR, as well as some low energy simulations of that component, are explained.

  5. Compilation of current high energy physics experiments

    International Nuclear Information System (INIS)

    This compilation of current high-energy physics experiments is a collaborative effort of the Berkeley Particle Data Group, the SLAC library, and the nine participating laboratories: Argonne (ANL), Brookhaven (BNL), CERN, DESY, Fermilab (FNAL), KEK, Rutherford (RHEL), Serpukhov (SERP), and SLAC. Nominally, the compilation includes summaries of all high-energy physics experiments at the above laboratories that were approved (and not subsequently withdrawn) before about June 1978, and had not completed taking of data by 1 January 1975. The experimental summaries are supplemented with three indexes to the compilation, several vocabulary lists giving names or abbreviations used, and a short summary of the beams at each of the laboratories (except Rutherford). The summaries themselves are included on microfiche

  6. High Energy Studies of Pulsar Wind Nebulae

    CERN Document Server

    Slane, Patrick

    2008-01-01

    The extended nebulae formed as pulsar winds expand into their surroundings provide information about the composition of the winds, the injection history from the host pulsar, and the material into which the nebulae are expanding. Observations from across the electromagnetic spectrum provide constraints on the evolution of the nebulae, the density and composition of the surrounding ejecta, the geometry of the systems, the formation of jets, and the maximum energy of the particles in the nebulae. Here I provide a broad overview of the structure of pulsar wind nebulae, with specific examples that demonstrate our ability to constrain the above parameters. The association of pulsar wind nebulae with extended sources of very high energy gamma-ray emission are investigated, along with constraints on the nature of such high energy emission.

  7. High energy physics at UC Riverside

    International Nuclear Information System (INIS)

    This report discusses progress made for the following two tasks: experimental high energy physics, Task A, and theoretical high energy physics, Task B. Task A1 covers hadron collider physics. Information for Task A1 includes: personnel/talks/publications; D0: proton-antiproton interactions at 2 TeV; SDC: proton-proton interactions at 40 TeV; computing facilities; equipment needs; and budget notes. The physics program of Task A2 has been the systematic study of leptons and hadrons. Information covered for Task A2 includes: personnel/talks/publications; OPAL at LEP; OPAL at LEP200; CMS at LHC; the RD5 experiment; LSND at LAMPF; and budget notes. The research activities of the Theory Group are briefly discussed and a list of completed or published papers for this period is given

  8. ACCELERATING POLARIZED PROTONS TO HIGH ENERGY.

    Energy Technology Data Exchange (ETDEWEB)

    BAI, M.; AHRENS, L.; ALEKSEEV, I.G.; ALESSI, J.; BEEBE-WANG, J.; BLASKIEWICZ, M.; BRAVAR, A.; BRENNAN, J.M.; BRUNO, D.; BUNCE, G.; ET AL.

    2006-10-02

    The Relativistic Heavy Ion Collider (RHIC) is designed to provide collisions of high energy polarized protons for the quest of understanding the proton spin structure. Polarized proton collisions at a beam energy of 100 GeV have been achieved in RHIC since 2001. Recently, polarized proton beam was accelerated to 250 GeV in RHIC for the first time. Unlike accelerating unpolarized protons, the challenge for achieving high energy polarized protons is to fight the various mechanisms in an accelerator that can lead to partial or total polarization loss due to the interaction of the spin vector with the magnetic fields. We report on the progress of the RHIC polarized proton program. We also present the strategies of how to preserve the polarization through the entire acceleration chain, i.e. a 200 MeV linear accelerator, the Booster, the AGS and RHIC.

  9. Ultra-High-Energy Cosmic Rays

    CERN Document Server

    Dova, M T

    2015-01-01

    The origin of the ultra high energy cosmic rays (UHECR) with energies above E > 10 17 eV, is still unknown. The discovery of their sources will reveal the engines of the most energetic astrophysical accelerators in the universe. This is a written version of a series of lectures devoted to UHECR at the 2013 CERN-Latin-American School of High-Energy Physics. We present anintroduction to acceleration mechanisms of charged particles to the highest energies in astrophysical objects, their propagation from the sources to Earth, and the experimental techniques for their detection. We also discuss some of the relevant observational results from Telescope Array and Pierre Auger Observatory. These experiments deal with particle interactions at energies orders of magnitude higher than achieved in terrestrial accelerators.

  10. Power Supplies for High Energy Particle Accelerators

    Science.gov (United States)

    Dey, Pranab Kumar

    2016-06-01

    The on-going research and the development projects with Large Hadron Collider at CERN, Geneva, Switzerland has generated enormous enthusiasm and interest amongst all to know about the ultimate findings on `God's Particle'. This paper has made an attempt to unfold the power supply requirements and the methodology adopted to provide the stringent demand of such high energy particle accelerators during the initial stages of the search for the ultimate particles. An attempt has also been made to highlight the present status on the requirement of power supplies in some high energy accelerators with a view that, precautionary measures can be drawn during design and development from earlier experience which will be of help for the proposed third generation synchrotron to be installed in India at a huge cost.

  11. High Energy Particles in the Solar Corona

    CERN Document Server

    Widom, A; Larsen, L

    2008-01-01

    Collective Ampere law interactions producing magnetic flux tubes piercing through sunspots into and then out of the solar corona allow for low energy nuclear reactions in a steady state and high energy particle reactions if a magnetic flux tube explodes in a violent event such as a solar flare. Filamentous flux tubes themselves are vortices of Ampere currents circulating around in a tornado fashion in a roughly cylindrical geometry. The magnetic field lines are parallel to and largely confined within the core of the vortex. The vortices may thereby be viewed as long current carrying coils surrounding magnetic flux and subject to inductive Faraday and Ampere laws. These laws set the energy scales of (i) low energy solar nuclear reactions which may regularly occur and (ii) high energy electro-weak interactions which occur when magnetic flux coils explode into violent episodic events such as solar flares or coronal mass ejections.

  12. Virtual compton scattering at high energy

    International Nuclear Information System (INIS)

    The virtual Compton scattering (VCS) reaction (ep→e'p' gamma) at high energy will provide new information on the proton structure. The invariant momentum transfer (t=(q-q')2) de pendence of high energy VCS is related to the flavor dependent vector and axial-vector form factors of the the proton. Thus VCS can provide information that is complementary to parity violating electron scattering measurements. For small t and large Q2, VCS generalizes the structure functions of deep inelastic lepton scattering. These generalized structure functions have a sum rule which yields the net contribution of quark spin and orbital angular momentum to the proton spin. A large acceptance detector such as the MEMUS design, capable of running at a luminosity 1035/cm2/sec at incident electron energies from 10 to 30 GeV can measure the VCS process in a broad and exciting kinematic range. (orig.)

  13. Semiconductor High-Energy Radiation Scintillation Detector

    CERN Document Server

    Kastalsky, A; Spivak, B

    2006-01-01

    We propose a new scintillation-type detector in which high-energy radiation produces electron-hole pairs in a direct-gap semiconductor material that subsequently recombine producing infrared light to be registered by a photo-detector. The key issue is how to make the semiconductor essentially transparent to its own infrared light, so that photons generated deep inside the semiconductor could reach its surface without tangible attenuation. We discuss two ways to accomplish this, one based on doping the semiconductor with shallow impurities of one polarity type, preferably donors, the other by heterostructure bandgap engineering. The proposed semiconductor scintillator combines the best properties of currently existing radiation detectors and can be used for both simple radiation monitoring, like a Geiger counter, and for high-resolution spectrography of the high-energy radiation. The most important advantage of the proposed detector is its fast response time, about 1 ns, essentially limited only by the recombi...

  14. New Prospects in High Energy Astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Blandford, Roger; /KIPAC, Menlo Park

    2011-11-15

    Recent discoveries using TeV, X-ray and radio telescopes as well as Ultra High Energy Cosmic Ray arrays are leading to new insights into longstanding puzzles in high energy astrophysics. Many of these insights come from combining observations throughout the electromagnetic and other spectra as well as evidence assembled from different types of source to propose general principles. Issues discussed in this general overview include methods of accelerating relativistic particles, and amplifying magnetic field, the dynamics of relativistic outflows and the nature of the prime movers that power them. Observational approaches to distinguishing hadronic, leptonic and electromagnetic outflows and emission mechanisms are discussed along with probes of the velocity field and the confinement mechanisms. Observations with GLAST promise to be very prescriptive for addressing these problems.

  15. Why is High Energy Physics Lorentz Invariant?

    CERN Document Server

    Afshordi, Niayesh

    2015-01-01

    Despite the tremendous empirical success of equivalence principle, there are several theoretical motivations for existence of a preferred reference frame (or aether) in a consistent theory of quantum gravity. However, if quantum gravity had a preferred reference frame, why would high energy processes enjoy such a high degree of Lorentz symmetry? While this is often considered as an argument against aether, here I provide three independent arguments for why perturbative unitarity (or weak coupling) of the Lorentz-violating effective field theories put stringent constraints on possible observable violations of Lorentz symmetry at high energies. In particular, the interaction with the scalar graviton in a consistent low-energy theory of gravity and a (radiatively and dynamically) stable cosmological framework, leads to these constraints. The violation (quantified by the relative difference in maximum speed of propagation) is limited to $\\lesssim 10^{-10} E({\\rm eV})^{-4}$ (superseding all current empirical bound...

  16. Solar flares and solar high energy particles

    International Nuclear Information System (INIS)

    Generally, the solar high energy particles in the flares are believed to be accelerated in two stages: acceleration by abrupt release of magnetic energy in the first stage and coronal diffusive shock wave or stochastic acceleration in the second stage. We consider the diffusive shock wave acceleration in gradual solar flare associated with fast coronal shock wave. The results indicate: (1) the characteristics of the particle distribution with time depends on the momentum and with the increasing of transition time, the distribution increases to maximum quickly and turns to decrease then; the higher energy, the more time of moving to maximum; (2) the corresponding time integral spectrum is proportional to the power of the particle momentum. The possibility of accelerating particles to high energy range is also discussed

  17. Ultra High Energy Cosmic Rays: Strangelets?

    Institute of Scientific and Technical Information of China (English)

    徐仁新; 吴飞

    2003-01-01

    The conjecture that ultra-high-energy cosmic rays (UHECRs) are actually strangelets is discussed. Besides the reason that strangelets can do as cosmic rays beyond the Greisen-Zatsepin-Kuzmin-cutoff, another argument to support the conjecture is addressed by the study of formation of Te V-scale microscopic black holes when UHECRs bombarding bare strange stars. It is proposed that the exotic quark surface of a bare strange star could be an effective astro-laboratory in the investigations of the extra dimensions and of the detection of ultra-high-energy neutrino fluxes. The flux of neutrinos (and other point-like particles) with energy larger than 2.3 × 1020 eV could be expected to be smaller than 10-26 cm-2 s-1 if there are two extra spatial dimensions.

  18. Power Supplies for High Energy Particle Accelerators

    Science.gov (United States)

    Dey, Pranab Kumar

    2015-05-01

    The on-going research and the development projects with Large Hadron Collider at CERN, Geneva, Switzerland has generated enormous enthusiasm and interest amongst all to know about the ultimate findings on `God's Particle'. This paper has made an attempt to unfold the power supply requirements and the methodology adopted to provide the stringent demand of such high energy particle accelerators during the initial stages of the search for the ultimate particles. An attempt has also been made to highlight the present status on the requirement of power supplies in some high energy accelerators with a view that, precautionary measures can be drawn during design and development from earlier experience which will be of help for the proposed third generation synchrotron to be installed in India at a huge cost.

  19. Strongly Interacting Matter at High Energy Density

    Energy Technology Data Exchange (ETDEWEB)

    McLerran,L.

    2008-09-07

    This lecture concerns the properties of strongly interacting matter (which is described by Quantum Chromodynamics) at very high energy density. I review the properties of matter at high temperature, discussing the deconfinement phase transition. At high baryon density and low temperature, large N{sub c} arguments are developed which suggest that high baryonic density matter is a third form of matter, Quarkyonic Matter, that is distinct from confined hadronic matter and deconfined matter. I finally discuss the Color Glass Condensate which controls the high energy limit of QCD, and forms the low x part of a hadron wavefunction. The Glasma is introduced as matter formed by the Color Glass Condensate which eventually thermalizes into a Quark Gluon Plasma.

  20. IC model of pulsar high energy emission

    CERN Document Server

    Lyutikov, Maxim

    2012-01-01

    We discuss growing evidence that pulsar high energy is emission is generated via Inverse Compton mechanism. We reproduce the broadband spectrum of Crab pulsar, from UV to very high energy gamma-rays - nearly ten decades in energy, within the framework of the cyclotron-self-Compton model. Emission is produced by two counter-streaming beams within the outer gaps, at distances above ~ 20 NS radii. The outward moving beam produces UV-X-ray photons via Doppler-booster cyclotron emission, and GeV photons by Compton scattering the cyclotron photons produced by the inward going beam. The scattering occurs in the deep Klein-Nishina regime, whereby the IC component provides a direct measurement of particle distribution within the magnetosphere. The required plasma multiplicity is high, ~ 10^6-10^7, but is consistent with the average particle flux injected into the pulsar wind nebula.

  1. Perspectives in high energy nuclear collisions

    International Nuclear Information System (INIS)

    This report gives an overview of some aspects of hadronic physics relevant for the conception of a research facility devoted to the study of high energy nuclear collisions. Several concepts to be studied in nuclear collisions are selected, with emphasis placed on the properties and nature of the quark-gluon plasma, the formation of the plasma state in the central region and its anticipated lifetime, and the observability, through strangeness content of this new form of nuclear matter. (orig.)

  2. High energy bosons do not propagate

    Energy Technology Data Exchange (ETDEWEB)

    Kurkov, M.A., E-mail: Kurkov@na.infn.it [Dipartimento di Fisica, Università di Napoli Federico II (Italy); INFN, Sezione di Napoli (Italy); Lizzi, Fedele, E-mail: fedele.lizzi@na.infn.it [Dipartimento di Fisica, Università di Napoli Federico II (Italy); INFN, Sezione di Napoli (Italy); Departament de Estructura i Constituents de la Matèria, Institut de Ciéncies del Cosmos, Universitat de Barcelona, Barcelona, Catalonia (Spain); Vassilevich, Dmitri, E-mail: dvassil@gmail.com [CMCC, Universidade Federal do ABC, Santo André, S.P. (Brazil)

    2014-04-04

    We discuss the propagation of bosons (scalars, gauge fields and gravitons) at high energy in the context of the spectral action. Using heat kernel techniques, we find that in the high-momentum limit the quadratic part of the action does not contain positive powers of the derivatives. We interpret this as the fact that the two-point Green functions vanish for nearby points, where the proximity scale is given by the inverse of the cutoff.

  3. High-energy accelerators in medicine

    CERN Document Server

    Mandrillon, Pierre

    1992-01-01

    The treatment of tumours with charged particles, ranging from protons to "light ions" ( Carbon, Oxygen, Neon) has many advantages, but up to now has been little used because of the absence of facilities. After the successful pioneering work carried out with accelerators built for physics research, machines dedicated to this new radiotherapy are planned or already in construction. The rationale for this new radiotherapy, the high energy accelerators and the beam delivery systems are presented in these two lectures.

  4. Physics with nuclei at high energies

    International Nuclear Information System (INIS)

    Physics with nuclei at high energy is not reducible to a superposition of interactions involving individual nucleons; rather, qualitatively new phenomena show up. This is what one concludes from recent data on dilepton production off nuclei and on elastic proton-nucleus scattering. Furthermore, recent analyses of ion collisions at BNL and CERN reveal a number of non-conventional features. The relevant contributions to this Rencontre are summarized here. 37 refs., 16 figs

  5. An experimental high energy physics program

    International Nuclear Information System (INIS)

    The theoretical and experimental high energy physics program is reviewed, including particle detectors. Topics discussed include τ and B physics, gamma-ray astronomy, neutrino oscillations in matter with three flavors applied to solar and supernova neutrinos, effective field theories, a possible fifth force, the dynamics of hadrons and superstrings, mathematics of grand unified theories, chiral symmetry breaking, physics at the Fermilab collider, and development of the TOPAZ detector

  6. High Energy Photon-Photon Collisions -

    OpenAIRE

    Brodsky, Stanley J.; SLAC; Zerwas, Peter M.; DESY

    1994-01-01

    The collisions of high energy photons produced at an electron-positron collider provide a comprehensive laboratory for testing QCD, electroweak interactions, and extensions of the Standard Model. The luminosity and energy of the colliding photons produced by back-scattering laser beams is expected to be comparable to that of the primary $e^+e^-$ collisions. In this overview, we shall focus on tests of electroweak theory in photon-photon annihilation, particularly $\\gamma\\gamma \\rightarrow W^+...

  7. Measuring high energy excitations - the future

    International Nuclear Information System (INIS)

    The performance of the main neutron techniques for measuring high energy excitations: the reactor triple axis, and the pulsed source rotor spectrometers, crystal analyzer methods, and resonance detector and absorption methods, will be reviewed in turn. The possibilities opened up the order of magnitude increased in source fluxes now in sight will be explored having in mind in particular the measurement of single crystal excitations to higher energies

  8. High energy interactions and extensive air showers

    International Nuclear Information System (INIS)

    We report on papers presented in the high energy sessions of the conference that do not deal with the theory and observations of muons and neutrinos. We concentrate on the development and testing of hadronic interaction models, their extension to ultrahigh energy and their importance for the analysis and interpretation of air shower data. We also summarize data on the cosmic ray spectrum and composition obtained with air showers

  9. Semiconductor High-Energy Radiation Scintillation Detector

    OpenAIRE

    Kastalsky, A.; Luryi, S.; Spivak, B

    2006-01-01

    We propose a new scintillation-type detector in which high-energy radiation produces electron-hole pairs in a direct-gap semiconductor material that subsequently recombine producing infrared light to be registered by a photo-detector. The key issue is how to make the semiconductor essentially transparent to its own infrared light, so that photons generated deep inside the semiconductor could reach its surface without tangible attenuation. We discuss two ways to accomplish this, one based on d...

  10. The first high energy neutrino experiment

    International Nuclear Information System (INIS)

    The design and implementation of the first high-energy neutrino experiment are described. The experiment was carried out at the proton synchrotron at Brookhaven National Laboratory in the early 1960s. Its major outcome was the experimental evidence of the existence of the muon neutrino. It was demonstrated that this neutrino is different from the electron neutrino. The review is a translation of the lecture delivered by the author during the Nobel Prize awarding ceremony in 1988. (Z.J.). 9 figs

  11. Emerging Computing Technologies in High Energy Physics

    OpenAIRE

    Farbin, Amir

    2009-01-01

    While in the early 90s High Energy Physics (HEP) lead the computing industry by establishing the HTTP protocol and the first web-servers, the long time-scale for planning and building modern HEP experiments has resulted in a generally slow adoption of emerging computing technologies which rapidly become commonplace in business and other scientific fields. I will overview some of the fundamental computing problems in HEP computing and then present the current state and future potential of empl...

  12. Networking for High Energy and Nuclear Physics

    OpenAIRE

    Newman, Harvey B.

    2007-01-01

    This report gives an overview of the status and outlook for the world's research networks and major international links used by the high energy physics and other scientific communities, network technology advances on which our community depends and in which we have an increasingly important role, and the problem of the Digital Divide, which is a primary focus of ICFA's Standing Committee on Inter-regional Connectivity (SCIC). Wide area networks of sufficient, and rapidly increasing end-to...

  13. HIGH ENERGY RATE EXTRUSION OF URANIUM

    Science.gov (United States)

    Lewis, L.

    1963-07-23

    A method of extruding uranium at a high energy rate is described. Conditions during the extrusion are such that the temperature of the metal during extrusion reaches a point above the normal alpha to beta transition, but the metal nevertheless remains in the alpha phase in accordance with the Clausius- Clapeyron equation. Upon exiting from the die, the metal automatically enters the beta phase, after which the metal is permitted to cool. (AEC)

  14. Quark model and high energy collisions

    International Nuclear Information System (INIS)

    The aim of the present review is to show that the additive quark model describes well not only the static features of hadrons but also the interaction processes at high energies. Considerations of the hadron-hadron and hadron-nucleus interactions and of the hadron production in multiparticle production processes suggest serious arguments in favour of the nucleus-like hadron structure and show the possibility to apply the rules of quark statistics to the description of the secondary particle production. (author)

  15. Automatic Keywording of High Energy Physics

    OpenAIRE

    Dallman, David (CERN); Le Meur, Jean-Yves; GreyNet, Grey Literature Network Service

    2000-01-01

    Bibliographic databases were developed from the traditional library card catalogue in order to enable users to access library documents via various types of bibliographic information, such as title, author, series or conference date. In addition these catalogues sometimes contained some form of indexation by subject, such as the Universal (or Dewey) Decimal Classification used for books. With the introduction of the eprint archives, set up by the High Energy Physics (HEP) Community in the ear...

  16. High energy excitations in itinerant ferromagnets

    International Nuclear Information System (INIS)

    Itinerant magnets, those whose electrons move throughout the crystal, are described by band theory. Single particle excitations offer confirmation of band theory, but their description requires important corrections. The energetics of magnetism in iron and nickel is also described in band theory but requires complex bands. Magnetism above the critical temperature and the location of the critical temperature offer discriminants between the two major models of magnetism at high temperature and can be addressed by high energy excitations

  17. Statistical Learning in High Energy and Astrophysics

    OpenAIRE

    Zimmermann, J.

    2005-01-01

    This thesis studies the performance of statistical learning methods in high energy and astrophysics where they have become a standard tool in physics analysis. They are used to perform complex classification or regression by intelligent pattern recognition. This kind of artificial intelligence is achieved by the principle ``learning from examples'': The examples describe the relationship between detector events and their classification. The application of statistical learning ...

  18. Galactic Ultra-High-Energy Cosmic Rays

    OpenAIRE

    Olinto, A. V.; Epstein, R. I.; P. Blasi(INAF Arcetri)

    1999-01-01

    The absence of the expected GZK cutoff strongly challenges the notion that the highest-energy cosmic rays are of distant extragalactic origin. We discuss the possibility that these ultra-high-energy events originate in our Galaxy and propose that they may be due to iron nuclei accelerated from young, strongly magnetic neutron stars. Newly formed pulsars accelerate ions from their surface through relativistic MHD winds. We find that pulsars whose initial spin periods are shorter than $\\sim 4 (...

  19. High Energy Phenomena in Clusters of Galaxies

    OpenAIRE

    P. Blasi(INAF Arcetri); Colafrancesco, S.

    1998-01-01

    Several phenomena in high energy astrophysics have been recently related to clusters of galaxies and to cosmic ray interactions occurring inside these structures. In many of these phenomena the observable effects depend on the energy density of cosmic rays confined in the Intra Cluster (IC) medium, which is a poorly known quantity. We propose here that useful indications about this quantity can be obtained from present and future observations of galaxy clusters in the radio and hard X-ray fre...

  20. Balance Function in High-Energy Collisions

    OpenAIRE

    Tawfik, A.; Shalaby, Asmaa G.

    2015-01-01

    Aspects and implications of the balance functions (BF) in high-energy physics are reviewed. The various calculations and measurements depending on different quantities, for example, system size, collisions centrality, and beam energy, are discussed. First, the different definitions including advantages and even short-comings are highlighted. It is found that BF, which are mainly presented in terms of relative rapidity, and relative azimuthal and invariant relative momentum, are se...

  1. Data preservation in High Energy Physics

    International Nuclear Information System (INIS)

    Data from high-energy physics experiments are collected with significant financial and human effort and are mostly unique. However, until recently no coherent strategy existed for data preservation and re-use, and many important and complex data sets have simply been lost. While the current focus is on the LHC at CERN, in the current period several important and unique experimental programs at other facilities are coming to an end, including those at HERA, b-factories and the Tevatron. To address this issue, an inter-experimental study group on HEP data preservation and long-term analysis (DPHEP) was convened at the end of 2008. The group now aims to publish a full and detailed review of the present status of data preservation in high energy physics. This contribution summarises the results of the DPHEP study group, describing the challenges of data preservation in high energy physics and the group's first conclusions and recommendations. The physics motivation for data preservation, generic computing and preservation models, technological expectations and governance aspects at local and international levels are examined.

  2. Proposal for a High Energy Nuclear Database

    Energy Technology Data Exchange (ETDEWEB)

    Brown, D A; Vogt, R

    2005-03-31

    The authors propose to develop a high-energy heavy-ion experimental database and make it accessible to the scientific community through an on-line interface. This database will be searchable and cross-indexed with relevant publications, including published detector descriptions. Since this database will be a community resource, it requires the high-energy nuclear physics community's financial and manpower support. This database should eventually contain all published data from Bevalac, AGS and SPS to RHIC and CERN-LHC energies, proton-proton to nucleus-nucleus collisions as well as other relevant systems, and all measured observables. Such a database would have tremendous scientific payoff as it makes systematic studies easier and allows simpler benchmarking of theoretical models to a broad range of old and new experiments. Furthermore, there is a growing need for compilations of high-energy nuclear data for applications including stockpile stewardship, technology development for inertial confinement fusion and target and source development for upcoming facilities such as the Next Linear Collider. To enhance the utility of this database, they propose periodically performing evaluations of the data and summarizing the results in topical reviews.

  3. High-energy fluxes of atmospheric neutrinos

    CERN Document Server

    Sinegovskaya, T S; Sinegovsky, S I

    2013-01-01

    High-energy neutrinos from decays of mesons, produced in collisions of cosmic ray particles with air nuclei, form unavoidable background for detection of astrophysical neutrinos. More precise calculations of the high-energy neutrino spectrum are required since measurements in the IceCube experiment reach the intriguing energy region where a contribution of the prompt neutrinos and/or astrophysical ones should be discovered. Basing on the referent hadronic models QGSJET II-03, SIBYLL 2.1, we calculate high-energy spectra, both of the muon and electron atmospheric neutrinos, averaged over zenith-angles. The computation is made using three parameterizations of cosmic ray spectra which include the knee region. All calculations are compared with the atmospheric neutrino measurements by Frejus and IceCube. The prompt neutrino flux predictions obtained with thequark-gluon string model (QGSM) for the charm production by Kaidalov & Piskunova do not contradict to the IceCube measurements and upper limit on the astr...

  4. Detector for high-energy photon backscatter

    Science.gov (United States)

    Silver, Michael D.; Erker, Joseph W.; Duncan, Michael Z.; Hartford, Thomas J.; Sivers, E. A.; Hopkinson, James F.

    1993-12-01

    High energy photon backscatter uses pair production to probe deep beneath surfaces with single side accessibility or to image thick, radiographically opaque objects. At the higher photon energies needed to penetrate thick and/or highly attenuating objects, Compton backscatter becomes strongly forward peaked with relatively little backscatter flux. Furthermore, the downward energy shift of the backscattered photon makes it more susceptible to attenuation on its outbound path. Above 1.022 MeV, pair production is possible; at about 10 MeV, pari production crosses over Compton scatter as the dominant x-ray interaction mechanism. The backscattered photons can be hard x rays from the bremsstrahlung of the electrons and positrons or 0.511 MeV photons from the annihilation of the positron. Monte Carlo computer simulations of such a backscatter system were done to characterize the output signals and to optimize a high energy detector design. This paper touches on the physics of high energy backscatter imaging and describes at some length the detector design for tomographic and radiographic imaging.

  5. Advances in High Energy Materials (Review Paper

    Directory of Open Access Journals (Sweden)

    U. R. Nair

    2010-03-01

    Full Text Available Research and development efforts for realizing higher performance levels of high energy materials (HEMs are continued unabated all over the globe. Of late, it is becoming increasingly necessary to ensure that such materials are also eco-friendly. This has provided thrust to research in the area of force multiplying HEMs and compounds free from pollution causing components. Enhancement of the performance necessitates introduction of strained structure or increase in oxygen balance to achieve near stoichiometry. The search for environment friendly molecules is focused on chlorine free propellant compositions and lead free primary explosives. Energetic polymers offer added advantage of partitioning of energy and thus not necessitating the concentration of only solid components (HEMs and metal fuels in the formulations, to achieve higher performance, thereby leading to improvement in energetics without adversely affecting the processability and mechanical properties. During recent times, research in the area of insensitive explosives has received impetus particularly with the signature of STANAG. This paper gives a review of the all-round advances in the areas of HEMs encompassing oxidizers, high-energy dense materials, insensitive high-energy materials, polymers and plasticizers. Selected formulations based on these materials are also included.Defence Science Journal, 2010, 60(2, pp.137-151, DOI:http://dx.doi.org/10.14429/dsj.60.327

  6. High energy behaviour of nonabelian gauge theories

    International Nuclear Information System (INIS)

    The high energy behavior (in the Regge limit) of nonabelian gauge theories is reviewed. After a general remark concerning the question to what extent the Regge limit can be approached within perturbation theory, we first review the reggeization of elementary particles within nonabelian gauge theories. Then the derivation of a unitary high energy description of a massive (= spontaneously broken) nonabelian gauge model is described, which results in a complete reggeon calculus. There is strong evidence that the zero mass limit of this reggeon calculus exists, thus giving rise to the hope that the Regge behavior in pure Yang-Mills theories (QCD) can be reached in this way. In the final part of these lectures two possible strategies for solving this reggeon calculus (both for the massive and the massless case) are outlined. One of them leads to a geometrical picture in which the distribution of the wee partons obeys a diffusion law. The other one makes contact with reggeon field theory and predicts that QCD in the high energy limit is described by critical reggeon field theory. (orig.)

  7. Evaluation of Burst Loss Rate of an Optical Burst Switching (OBS) Network with Wavelength Conversion Capability

    OpenAIRE

    Reza, Md. Shamim; Hossain, Md. Maruf; Majumder, Satya Prasad

    2010-01-01

    This paper presents a new analytical model for calculating burst loss rate (BLR) in a slotted optical burst switched network. The analytical result leads to a framework which provides guidelines for optical burst switched networks. Wavelength converter is used for burst contention resolution. The effect of several design parameters such as burst arrival probability, wavelength conversion capability, number of slots per burst and number of wavelengths is incorporated on the above performance m...

  8. Search for high-energy neutrinos from GRB130427A with the ANTARES neutrino telescope

    Science.gov (United States)

    Celli, Silvia

    2016-02-01

    ANTARES is the first deep under-sea high-energy astrophysical neutrino telescope, in operation since 2008, in the Northern Hemisphere. In the light of a multi-messenger approach, one of the most ever intense (photon fluence Fγ ≃10-3 erg/cm2) and close (redshift z = 0.34) transient γ-source, GRB130427A, is considered in the ANTARES physics program for a co-incident search for photons and high-energy neutrinos. The first time-dependent analysis on GRBs neutrino emissions has been performed for this source: Konus-Wind parameters of the γ time-dependent spectrum are used to predict the expected neutrino flux from each peak of the burst, through the numerical calculation code NeuCosmA. An extended maximum likelihood ratio search is performed in order to maximize the discovery probability of prompt neutrinos from the burst: at the end, ANTARES sensitivity to this source is evaluated to be E2Φv ∼ 1 -10 GeV/cm2 in the energy range from 2 x 105 GeV to 2 x 107 GeV.

  9. The Transient High Energy Sky and Early Universe Surveyor

    Science.gov (United States)

    O'Brien, P. T.

    2016-04-01

    The Transient High Energy Sky and Early Universe Surveyor is a mission which will be proposed for the ESA M5 call. THESEUS will address multiple components in the Early Universe ESA Cosmic Vision theme:4.1 Early Universe,4.2 The Universe taking shape, and4.3 The evolving violent Universe.THESEUS aims at vastly increasing the discovery space of the high energy transient phenomena over the entire cosmic history. This is achieved via a unique payload providing an unprecedented combination of: (i) wide and deep sky monitoring in a broad energy band(0.3 keV-20 MeV; (ii) focusing capabilities in the soft X-ray band granting large grasp and high angular resolution; and (iii) on board near-IR capabilities for immediate transient identification and first redshift estimate.The THESEUS payload consists of: (i) the Soft X--ray Imager (SXI), a set of Lobster Eye (0.3--6 keV) telescopes with CCD detectors covering a total FOV of 1 sr; (ii) the X--Gamma-rays spectrometer (XGS), a non-imaging spectrometer (XGS) based on SDD+CsI, covering the same FOV than the Lobster telescope extending the THESEUS energy band up to 20 MeV; and (iii) a 70cm class InfraRed Telescope (IRT) observing up to 2 microns with imaging and moderate spectral capabilities.The main scientific goals of THESEUS are to:(a) Explore the Early Universe (cosmic dawn and reionization era) by unveiling the Gamma--Ray Burst (GRBs) population in the first billion years}, determining when did the first stars form, and investigating the re-ionization epoch, the interstellar medium (ISM) and the intergalactic medium (IGM) at high redshifts.(b) Perform an unprecedented deep survey of the soft X-ray transient Universe in order to fill the present gap in the discovery space of new classes of transient; provide a fundamental step forward in the comprehension of the physics of various classes of Galactic and extra--Galactic transients, and provide real time trigger and accurate locations of transients for follow-up with next

  10. 14 CFR 27.1461 - Equipment containing high energy rotors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 27... Equipment containing high energy rotors. (a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section. (b) High energy rotors contained in equipment must be able to...

  11. 14 CFR 29.1461 - Equipment containing high energy rotors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 29... § 29.1461 Equipment containing high energy rotors. (a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section. (b) High energy rotors contained in equipment must...

  12. 14 CFR 25.1461 - Equipment containing high energy rotors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 25... § 25.1461 Equipment containing high energy rotors. (a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section. (b) High energy rotors contained in equipment must...

  13. A Soft X-Ray Lag Detected in Centaurus A

    CERN Document Server

    Tachibana, Yutaro; Ueda, Yoshihiro; Shidatsu, Megumi; Arimoto, Makoto; Yoshii, Taketoshi; Yatsu, Yoichi; Saito, Yoshihiko; Pike, Sean; Kawai, Nobuyuki

    2015-01-01

    We performed time lag analysis on the X-ray light curves of Centaurus A (Cen A) obtained by the Gas Slit Camera (GSC) aboard the Monitor of All-sky X-ray Image (MAXI) in three energy bands (2--4 keV, 4--10 keV, and 10--20 keV). We discovered a soft X-ray lag relative to higher energies (soft lag) on a time scale of days by employing the discrete correlation function (DCF) and the z-transformed discrete correlation function (ZDCF) method in a flare episode. A peak in the DCF and the ZDCF was observed at a soft lag of $\\sim 5$ days in 2--4 keV versus 4--10 keV and in 4--10 keV versus 10--20 keV, and $\\sim 10$ days in 2--4 keV versus 10--20 keV. We found it difficult to explain the observed X-ray variation with the one-zone synchrotron self-Compton (SSC) model, in which the soft lags reflect the different cooling times of the relativistic electrons in these three energy bands. Alternatively, if the X-ray variation was produced in a corona surrounding or along the inner part of the accretion disk, we can explain ...

  14. Variable lag variography using k-means clustering

    Science.gov (United States)

    Kapageridis, I. K.

    2015-12-01

    Experimental variography in three dimensions based on drillhole data and current modelling software requires the selection of particular directions (azimuth and plunge) and a basic lag distance. Variogram points are then calculated on distances which are multiples of that basic lag. As samples rarely follow a regular grid, directional and distance tolerances are applied in order to have sufficient pairs to calculate reliable variogram points. This process is adequate when drillholes follow a drilling pattern (even if not an exactly regular grid) but can be time consuming and hard when the drilling pattern is irregular or when drillhole orientations vary considerably. Having all variogram points being calculated on multiples of a fixed lag, and the same tolerance being applied throughout the range of distances used, can be very restrictive and a reason for considerable time wasting or even failure to calculate an interpretable experimental variogram. The method discussed in this paper is using k-means clustering of sample pairs based on pair separation distance leading to a number of clusters each representing a different variogram point. This way, lag parameters are adjusted automatically to match the spatial distribution of sample locations and the resulting variogram is improved. Case studies are provided showing the benefits of this method over current fixed-lag experimental variogram calculation techniques.

  15. Light speed variation from gamma-ray bursts

    CERN Document Server

    Xu, Haowei

    2016-01-01

    The effect of quantum gravity can bring a tiny light speed variation which is detectable through energetic photons propagating from gamma ray bursts (GRBs) to an observer such as the space observatory. Through an analysis of the energetic photon data of the GRBs observed by the Fermi Gamma-ray Space Telescope (FGST), we reveal a surprising regularity of the observed time lags between photons of different energies with respect to the Lorentz violation factor due to the light speed energy dependence. Such regularity suggests a linear form correction of the light speed $v(E)=c(1-E/E_{\\rm LV})$, where $E$ is the photon energy and $E_{\\rm LV}=(3.60 \\pm 0.26) \\times 10^{17}~ \\rm GeV$ is the Lorentz violation scale measured by the energetic photon data of GRBs. The results support an energy dependence of the light speed in cosmological space.

  16. THE HIGH-ENERGY IMPULSIVE GROUND-LEVEL ENHANCEMENT

    Energy Technology Data Exchange (ETDEWEB)

    McCracken, K. G. [Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742 (United States); Moraal, H. [Centre for Space Research, School for Physical and Chemical Sciences, North-West University, Potchefstroom 2520 (South Africa); Shea, M. A. [CSPAR, University of Alabama at Huntsville, Huntsville, AL 35899 (United States)

    2012-12-20

    We have studied short-lived (21 minute average duration), highly anisotropic pulses of cosmic rays that constitute the first phase of 10 large ground-level enhancements (GLEs), and which extend to rigidities in the range 5-20 GV. We provide a set of constraints that must be met by any putative acceleration mechanism for this type of solar-energetic-particle (SEP) event. The pulses usually have very short rise-times (three to five minutes) at all rigidities, and exhibit the remarkable feature that the intensity drops precipitously by 50% to 70% from the maximum within another three to five minutes. Both the rising and falling phases exhibit velocity dispersion, which indicates that there are particles with rigidities in the range 1 < P (GV) < 3 in the beam, and the evidence is that there is little scattering en route from the Sun. We name these events the high-energy impulsive ground-level enhancement (HEI GLE). We argue that the time-dependence observed at Earth at {approx}5 GV is a close approximation to that of the SEP pulse injected into the open heliospheric magnetic field in the vicinity of the Sun. We conclude that the temporal characteristics of the HEI GLE impose nine constraints on any putative acceleration process. Two of the HEI GLEs are preceded by short-lived, fast-rising neutron and >90 MeV gamma-ray bursts, indicating that freshly accelerated SEPs had impinged on higher-density matter in the chromosphere prior to the departure of the SEP pulse for Earth. This study was based on an updated archive of the 71 GLEs in the historic record, which is now available for public use.

  17. Search for Prompt Neutrino Emission from Gamma-Ray Bursts with IceCube

    CERN Document Server

    Aartsen, M G; Adams, J; Aguilar, J A; Ahlers, M; Ahrens, M; Altmann, D; Anderson, T; Arguelles, C; Arlen, T C; Auffenberg, J; Bai, X; Barwick, S W; Baum, V; Bay, R; Beatty, J J; Tjus, J Becker; Becker, K -H; BenZvi, S; Berghaus, P; Berley, D; Bernardini, E; Bernhard, A; Besson, D Z; Binder, G; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Bos, F; Bose, D; Böser, S; Botner, O; Brayeur, L; Bretz, H -P; Brown, A M; Buzinsky, N; Casey, J; Casier, M; Cheung, E; Chirkin, D; Christov, A; Christy, B; Clark, K; Classen, L; Clevermann, F; Coenders, S; Cowen, D F; Silva, A H Cruz; Daughhetee, J; Davis, J C; Day, M; de André, J P A M; De Clercq, C; De Ridder, S; Desiati, P; de Vries, K D; de With, M; DeYoung, T; Díaz-Vélez, J C; Dunkman, M; Eagan, R; Eberhardt, B; Ehrhardt, T; Eichmann, B; Eisch, J; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Felde, J; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Frantzen, K; Fuchs, T; Gaisser, T K; Gaior, R; Gallagher, J; Gerhardt, L; Gier, D; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Golup, G; Gonzalez, J G; Goodman, J A; Góra, D; Grant, D; Gretskov, P; Groh, J C; Groß, A; Ha, C; Haack, C; Ismail, A Haj; Hallen, P; Hallgren, A; Halzen, F; Hanson, K; Hebecker, D; Heereman, D; Heinen, D; Helbing, K; Hellauer, R; Hellwig, D; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, R; Homeier, A; Hoshina, K; Huang, F; Huelsnitz, W; Hulth, P O; Hultqvist, K; Ishihara, A; Jacobi, E; Jacobsen, J; Japaridze, G S; Jero, K; Jlelati, O; Jurkovic, M; Kaminsky, B; Kappes, A; Karg, T; Karle, A; Kauer, M; Keivani, A; Kelley, J L; Kheirandish, A; Kiryluk, J; Kläs, J; Klein, S R; Köhne, J -H; Kohnen, G; Kolanoski, H; Koob, A; Köpke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Kriesten, A; Krings, K; Kroll, G; Kroll, M; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Lanfranchi, J L; Larsen, D T; Larson, M J; Lesiak-Bzdak, M; Leuermann, M; Lünemann, J; Madsen, J; Maggi, G; Maruyama, R; Mase, K; Matis, H S; Maunu, R; McNally, F; Meagher, K; Medici, M; Meli, A; Meures, T; Miarecki, S; Middell, E; Middlemas, E; Milke, N; Miller, J; Mohrmann, L; Montaruli, T; Morse, R; Nahnhauer, R; Naumann, U; Niederhausen, H; Nowicki, S C; Nygren, D R; Obertacke, A; Odrowski, S; Olivas, A; Omairat, A; O'Murchadha, A; Palczewski, T; Paul, L; Penek, Ö; Pepper, J A; Heros, C Pérez de los; Pfendner, C; Pieloth, D; Pinat, E; Posselt, J; Price, P B; Przybylski, G T; Pütz, J; Quinnan, M; Rädel, L; Rameez, M; Rawlins, K; Redl, P; Rees, I; Reimann, R; Relich, M; Resconi, E; Rhode, W; Richman, M; Riedel, B; Robertson, S; Rodrigues, J P; Rongen, M; Rott, C; Ruhe, T; Ruzybayev, B; Ryckbosch, D; Saba, S M; Sander, H -G; Sandroos, J; Santander, M; Sarkar, S; Schatto, K; Scheriau, F; Schmidt, T; Schmitz, M; Schoenen, S; Schöneberg, S; Schönwald, A; Schukraft, A; Schulte, L; Schulz, O; Seckel, D; Sestayo, Y; Seunarine, S; Shanidze, R; Smith, M W E; Soldin, D; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stanisha, N A; Stasik, A; Stezelberger, T; Stokstad, R G; Stößl, A; Strahler, E A; Ström, R; Strotjohann, N L; Sullivan, G W; Taavola, H; Taboada, I; Tamburro, A; Tepe, A; Ter-Antonyan, S; Terliuk, A; Tešić, G; Tilav, S; Toale, P A; Tobin, M N; Tosi, D; Tselengidou, M; Unger, E; Usner, M; Vallecorsa, S; van Eijndhoven, N; Vandenbroucke, J; van Santen, J; Vanheule, S; Vehring, M; Voge, M; Vraeghe, M; Walck, C; Wallraff, M; Weaver, Ch; Wellons, M; Wendt, C; Westerhoff, S; Whelan, B J; Whitehorn, N; Wichary, C; Wiebe, K; Wiebusch, C H; Williams, D R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, D L; Xu, X W; Xu, Y; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Ziemann, J; Zoll, M

    2014-01-01

    We present constraints derived from a search of four years of IceCube data for a prompt neutrino flux from gamma-ray bursts (GRBs). A single low-significance neutrino was found in coincidence with one of the 506 observed bursts, consistent with the expectation from atmospheric backgrounds. Although GRBs have been proposed as candidate sources for ultra-high energy cosmic rays, our limits on the neutrino flux disfavor much of the parameter space for the latest models. We also find that no more than $\\sim1\\%$ of the recently observed astrophysical neutrino flux consists of prompt emission from GRBs that are potentially observable by existing satellites.

  18. THE FERMI GBM GAMMA-RAY BURST CATALOG: THE FIRST TWO YEARS

    Energy Technology Data Exchange (ETDEWEB)

    Paciesas, William S.; Bhat, P. N.; Briggs, Michael S.; Burgess, J. Michael; Chaplin, Vandiver; Connaughton, Valerie; Goldstein, Adam; Guiriec, Sylvain [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Meegan, Charles A.; Van der Horst, Alexander J. [Universities Space Research Association, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Von Kienlin, Andreas; Diehl, Roland; Foley, Suzanne; Greiner, Jochen; Gruber, David [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching (Germany); Bissaldi, Elisabetta [Institute of Astro and Particle Physics, University Innsbruck, Technikerstrasse 25, 6176 Innsbruck (Austria); Fishman, Gerald J. [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Fitzpatrick, Gerard [School of Physics, University College Dublin, Belfield, Stillorgan Road, Dublin 4 (Ireland); Gibby, Melissa; Giles, Misty [Jacobs Technology, Inc., 1525 Perimeter Pkwy NW, Huntsville, AL 35806 (United States); and others

    2012-03-01

    The Fermi Gamma-ray Burst Monitor (GBM) is designed to enhance the scientific return from Fermi in studying gamma-ray bursts (GRBs). In its first two years of operation GBM triggered on 491 GRBs. We summarize the criteria used for triggering and quantify the general characteristics of the triggered GRBs, including their locations, durations, peak flux, and fluence. This catalog is an official product of the Fermi GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center.

  19. The Fermi GBM Gamma-Ray Burst Catalog: The First Two Years

    CERN Document Server

    Paciesas, William S; von Kienlin, Andreas; Bhat, P N; Bissaldi, Elisabetta; Briggs, Michael S; Burgess, J Michael; Chaplin, Vandiver; Connaughton, Valerie; Diehl, Roland; Fishman, Gerald J; Fitzpatrick, Gerard; Foley, Suzanne; Gibby, Melissa; Giles, Misty; Goldstein, Adam; Greiner, Jochen; Gruber, David; Guiriec, Sylvain; van der Horst, Alexander J; Kippen, R Marc; Kouveliotou, Chryssa; Lichti, Giselher; Lin, Lin; McBreen, Sheila; Preece, Robert D; Rau, Arne; Tierney, Dave; Wilson-Hodge, Colleen

    2012-01-01

    The Fermi Gamma-ray Burst Monitor (GBM) is designed to enhance the scientific return from Fermi in studying gamma-ray bursts (GRBs). In its first two years of operation GBM triggered on 491 GRBs. We summarize the criteria used for triggering and quantify the general characteristics of the triggered GRBs, including their locations, durations, peak flux, and fluence. This catalog is an official product of the Fermi GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center (HEASARC).

  20. Self-organized criticality in X-ray flares of gamma-ray burst afterglows

    OpenAIRE

    Wang, F.Y.; Dai, Z. G.

    2013-01-01

    X-ray flares detected in nearly half of gamma-ray burst (GRB) afterglows are one of the most intriguing phenomena in high-energy astrophysics. All the observations indicate that the central engines of bursts, after the gamma-ray emission has ended, still have long periods of activity, during which energetic explosions eject relativistic materials, leading to late-time X-ray emission. It is thus expected that X-ray flares provide important clues to the nature of the central engines of GRBs, an...

  1. A first search for coincident gravitational waves and high energy neutrinos using LIGO, Virgo and ANTARES data from 2007

    Energy Technology Data Exchange (ETDEWEB)

    Adrián-Martínez, S.; Ardid, M.; Bou-Cabo, M. [Institut d' Investigació per a la Gestió Integrada de les Zones Costaneres (IGIC) - Universitat Politècnica de València. C/ Paranimf 1 , 46730 Gandia, Spain. (Spain); Samarai, I. Al; Aubert, J-J.; Bertin, V.; Brunner, J. [CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille (France); Albert, A. [GRPHE - Institut universitaire de technologie de Colmar, 34 rue du Grillenbreit BP 50568 - 68008 Colmar (France); André, M. [Technical University of Catalonia, Laboratory of Applied Bioacoustics, Rambla Exposició, 08800 Vilanova i la Geltrú, Barcelona (Spain); Anghinolfi, M. [INFN - Sezione di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Anton, G. [Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany); Anvar, S. [Direction des Sciences de la Matière - Institut de recherche sur les lois fondamentales de l' Univers - Service d' Electronique des Détecteurs et d' Informatique, CEA Saclay, 91191 Gif-sur-Yvette Cedex (France); Astraatmadja, T.; Bogazzi, C.; Bouwhuis, M.C. [Nikhef, Science Park, Amsterdam (Netherlands); Baret, B.; Bouhou, B. [APC, Université Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cité, 75205 Paris (France); Basa, S. [LAM - Laboratoire d' Astrophysique de Marseille, Pôle de l' Étoile Site de Château-Gombert, rue Frédéric Joliot-Curie 38, 13388 Marseille Cedex 13 (France); Biagi, S. [INFN - Sezione di Bologna, Viale C. Berti-Pichat 6/2, 40127 Bologna (Italy); Bigongiari, C., E-mail: antares.spokesperson@in2p3.fr, E-mail: lsc-spokesperson@ligo.org, E-mail: virgo-spokesperson@ego-gw.it, E-mail: Irene.DiPalma@aei.mpg.de, E-mail: thierry.pradier@iphc.cnrs.fr [IFIC - Instituto de Física Corpuscular, Edificios Investigación de Paterna, CSIC - Universitat de València, Apdo. de Correos 22085, 46071 Valencia (Spain); and others

    2013-06-01

    We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.

  2. A first search for coincident gravitational waves and high energy neutrinos using LIGO, Virgo and ANTARES data from 2007

    International Nuclear Information System (INIS)

    We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events

  3. A First Search for Coincident Gravitational Waves and High Energy Neutrinos Using LIGO, Virgo and ANTARES Data from 2007

    Science.gov (United States)

    Adrian-Martinez, S.; Samarai, Al; Albert, A.; Andre, M.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M; Astraatmadja, T.; Aubert, J.-J.; Baret, B.; Basa, S.; Bertin, V.; Biagi, S.; Bigongiari, C.; Bogazzi, C; Bou-Cabo, M.; Bouhou, B.; Bowhuis, M. C.; Bertin, V.; Brunner, J.; Busto, J.; Blackburn, L.; Camp, J. B.; Kanner, J. B.

    2013-01-01

    We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.

  4. A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007

    CERN Document Server

    Adrián-Martínez, S; Samarai, I Al; Albert, A; André, M; Anghinolfi, M; Anton, G; Anvar, S; Ardid, M; Jesus, A C Assis; Astraatmadja, T; Aubert, J-J; Baret, B; Basa, S; Bertin, V; Biagi, S; Bigi, A; Bigongiari, C; Bogazzi, C; Bou-Cabo, M; Bouhou, B; Bouwhuis, M C; Brunner, J; Busto, J; Camarena, F; Capone, A; Cârloganu, C; Carr, J; Cecchini, S; Charif, Z; Charvis, Ph; Chiarusi, T; Circella, M; Coniglione, R; Costantini, H; Coyle, P; Curtil, C; Decowski, M P; Dekeyser, I; Deschamps, A; Distefano, C; Donzaud, C; Dornic, D; Dorosti, Q; Drouhin, D; Eberl, T; Emanuele, U; Enzenhöfer, A; Ernenwein, J-P; Escoffier, S; Fermani, P; Ferri, M; Flaminio, V; Folger, F; Fritsch, U; Fuda, J-L; Galatà, S; Gay, P; Giacomelli, G; Giordano, V; Gómez-González, J P; Graf, K; Guillard, G; Halladjian, G; Hallewell, G; van Haren, H; Hartman, J; Heijboer, A J; Hello, Y; Hernández-Rey, J J; Herold, B; Hößl, J; Hsu, C C; de Jong, M; Kadler, M; Kalekin, O; Kappes, A; Katz, U; Kavatsyuk, O; Kooijman, P; Kopper, C; Kouchner, A; Kreykenbohm, I; Kulikovskiy, V; Lahmann, R; Lamare, P; Larosa, G; Lattuada, D; Lefèvre, D; Lim, G; Presti, D Lo; Loehner, H; Loucatos, S; Mangano, S; Marcelin, M; Margiotta, A; Martínez-Mora, J A; Meli, A; Montaruli, T; Morganti, M; Moscoso, L; Motz, H; Neff, M; Nezri, E; Palioselitis, D; Păvălaş, G E; Payet, K; Payre, P; Petrovic, J; Piattelli, P; Picot-Clemente, N; Popa, V; Pradier, T; Presani, E; Racca, C; Reed, C; Richardt, C; Richter, R; Rivière, C; Robert, A; Roensch, K; Rostovtsev, A; Ruiz-Rivas, J; Rujoiu, M; Russo, G V; Salesa, F; Samtleben, D F E; Sapienza, P; Schöck, F; Schuller, J-P; Schüssler, F; Seitz, T; Shanidze, R; Simeone, F; Spies, A; Spurio, M; Steijger, J J M; Stolarczyk, Th; Sánchez-Losa, A; Taiuti, M; Tamburini, C; Toscano, S; Vallage, B; Van Elewyck, V; Vannoni, G; Vecchi, M; Vernin, P; Wagner, S; Wijnker, G; Wilms, J; de Wolf, E; Yepes, H; Zaborov, D; Zornoza, J D; Zúñiga, J; Aasi, J; Abadie, J; Abbott, B P; Abbott, R; Abbott, T D; Abernathy, M; Accadia, T; Acernese, F; Adams, C; Adams, T; Addesso, P; Adhikari, R; Affeldt, C; Agathos, M; Agatsuma, K; Ajith, P; Allen, B; Allocca, A; Ceron, E Amador; Amariutei, D; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Ast, S; Aston, S M; Astone, P; Atkinson, D; Aufmuth, P; Aulbert, C; Aylott, B E; Babak, S; Baker, P; Ballardin, G; Ballmer, S; Bao, Y; Barayoga, J C B; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Bastarrika, M; Basti, A; Batch, J; Bauchrowitz, J; Bauer, Th S; Bebronne, M; Beck, D; Behnke, B; Bejger, M; Beker, M G; Bell, A S; Bell, C; Belopolski, I; Benacquista, M; Berliner, J M; Bertolini, A; Betzwieser, J; Beveridge, N; Beyersdorf, P T; Bhadbade, T; Bilenko, I A; Billingsley, G; Birch, J; Biswas, R; Bitossi, M; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Bland, B; Blom, M; Bock, O; Bodiya, T P; Bogan, C; Bond, C; Bondarescu, R; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, S; Bosi, L; Braccini, S; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Breyer, J; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Britzger, M; Brooks, A F; Brown, D A; Bulik, T; Bulten, H J; Buonanno, A; Burguet--Castell, J; Buskulic, D; Buy, C; Byer, R L; Cadonati, L; Cagnoli, G; Calloni, E; Camp, J B; Campsie, P; Cannon, K; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C; Cesarini, E; Chalermsongsak, T; Charlton, P; Chassande-Mottin, E; Chen, W; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Chow, J; Christensen, N; Chua, S S Y; Chung, C T Y; Chung, S; Ciani, G; Clara, F; Clark, D E; Clark, J A; Clayton, J H; Cleva, F; Coccia, E; Cohadon, P -F; Colacino, C N; Colla, A; Colombini, M; Conte, A; Conte, R; Cook, D; Corbitt, T R; Cordier, M; Cornish, N; Corsi, A; Costa, C A; Coughlin, M; Coulon, J -P; Couvares, P; Coward, D M; Cowart, M; Coyne, D C; Creighton, J D E; Creighton, T D; Cruise, A M; Cumming, A; Cunningham, L; Cuoco, E; Cutler, R M; Dahl, K; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daudert, B; Daveloza, H; Davier, M; Daw, E J; Day, R; Dayanga, T; De Rosa, R; DeBra, D; Debreczeni, G; Degallaix, J; Del Pozzo, W; Dent, T; Dergachev, V; DeRosa, R; Dhurandhar, S; Di Fiore, L; Di Lieto, A; Di Palma, I; Emilio, M Di Paolo; Di Virgilio, A; Díaz, M; Dietz, A; Donovan, F; Dooley, K L; Doravari, S; Dorsher, S; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Dumas, J -C; Dwyer, S; Eberle, T; Edgar, M; Edwards, M; Effler, A; Ehrens, P; Endrőczi, G; Engel, R; Etzel, T; Evans, K; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Farr, B F; Favata, M; Fazi, D; Fehrmann, H; Feldbaum, D; Ferrante, I; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R P

    2012-01-01

    We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.

  5. Phase-lag Distances of OH Masing AGB Stars

    CERN Document Server

    Engels, D; Gerard, E; Richards, A

    2015-01-01

    Distances to AGB stars with optically thick circumstellar shells cannot be determined using optical parallaxes. However, for stars with OH 1612 MHz maser emission emanating from their circumstellar shells, distances can be determined by the phase-lag method. This method combines a linear diameter obtained from a phase-lag measurement with an angular diameter obtained from interferometry. The phase-lag of the variable emission from the back and front sides of the shells has been determined for 20 OH/IR stars in the galactic disk. These measurements are based on a monitoring program with the Nancay radio telescope ongoing for more than 6 years. The interferometric observations are continuing. We estimate that the uncertainties of the distance determination will be ~20%.

  6. Phase-lag Distances of OH Masing AGB Stars

    Science.gov (United States)

    Engels, D.; Etoka, S.; Gérard, E.; Richards, A.

    2015-08-01

    Distances to AGB stars with optically thick circumstellar shells cannot be determined using optical parallaxes. However, for stars with OH 1612 MHz maser emission emanating from their circumstellar shells, distances can be determined by the phase-lag method. This method combines a linear diameter obtained from a phase-lag measurement with an angular diameter obtained from interferometry. The phase-lag of the variable emission from the back and front sides of the shells has been determined for 20 OH/IR stars in the galactic disk. These measurements are based on a monitoring program with the Nançay radio telescope ongoing for more than 6 years. The interferometric observations are continuing. We estimate that the uncertainties of the distance determination will be ˜20%.

  7. Temporal Profiles and Spectral Lags of XRF 060218

    CERN Document Server

    Liang, E W; Stamatikos, M; Zhang, B; Norris, J; Gehrels, N; Zhang, J; Dai, Z G; Liang, En-Wei; Zhang, Bin-Bin; Stamatikos, Mike; Zhang, Bing; Norris, Jay; Gehrels, Neil; Zhang, Jin

    2006-01-01

    The spectral and temporal properties of the non-thermal emission ofthe nearby XRF 060218 in 0.3-150 keV band are studied. We show that both the spectral energy distribution and the light curve properties suggest the same origin of the non-thermal emission detected by {\\em Swift} BAT and XRT. This event has the longest pulse duration and spectral lag observed to date among the known GRBs. The pulse structure and its energy dependence are analogous to typical GRBs. By extrapolating the observed spectral lag to the {\\em CGRO/BATSE} bands we find that the hypothesis that this event complies with the same luminosity-lag relation with bright GRBs cannot be ruled out at $2\\sigma$ significance level. These intriguing facts, along with its compliance with the Amati-relation, indicate that XRF 060218 shares the similar radiation physics as typical GRBs.

  8. The evolution of high energy accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Courant, E.D.

    1994-08-01

    Accelerators have been devised and built for two reasons: In the first place, by physicists who needed high energy particles in order to have a means to explore the interactions between particles that probe the fundamental elementary forces of nature. And conversely, sometimes accelerator builders produce new machines for higher energy than ever before just because it can be done, and then challenge potential users to make new discoveries with the new means at hand. These two approaches or motivations have gone hand in hand. This lecture traces how high energy particle accelerators have grown from tools used for esoteric small-scale experiments to the gigantic projects of today. So far all the really high-energy machines built and planned in the world--except the SLC--have been ring accelerators and storage rings using the strong-focusing method. But this method has not removed the energy limit, it has only pushed it higher. It would seem unlikely that one can go beyond the Large Hadron Collider (LHC)--but in fact a workshop was held in Sicily in November 1991, concerned with the question of extrapolating to 100 TeV. Other acceleration and beam-forming methods are now being discussed--collective fields, laser acceleration, wake-field accelerators etc., all aimed primarily at making linear colliders possible and more attractive than with present radiofrequency methods. So far it is not entirely clear which of these schemes will dominate particle physics in the future--maybe something that has not been thought of as yet.

  9. The evolution of high energy accelerators

    International Nuclear Information System (INIS)

    Accelerators have been devised and built for two reasons: In the first place, by physicists who needed high energy particles in order to have a means to explore the interactions between particles that probe the fundamental elementary forces of nature. And conversely, sometimes accelerator builders produce new machines for higher energy than ever before just because it can be done, and then challenge potential users to make new discoveries with the new means at hand. These two approaches or motivations have gone hand in hand. This lecture traces how high energy particle accelerators have grown from tools used for esoteric small-scale experiments to the gigantic projects of today. So far all the really high-energy machines built and planned in the world--except the SLC--have been ring accelerators and storage rings using the strong-focusing method. But this method has not removed the energy limit, it has only pushed it higher. It would seem unlikely that one can go beyond the Large Hadron Collider (LHC)--but in fact a workshop was held in Sicily in November 1991, concerned with the question of extrapolating to 100 TeV. Other acceleration and beam-forming methods are now being discussed--collective fields, laser acceleration, wake-field accelerators etc., all aimed primarily at making linear colliders possible and more attractive than with present radiofrequency methods. So far it is not entirely clear which of these schemes will dominate particle physics in the future--maybe something that has not been thought of as yet

  10. Grid Computing in High Energy Physics

    International Nuclear Information System (INIS)

    Over the next two decades, major high energy physics (HEP) experiments, particularly at the Large Hadron Collider, will face unprecedented challenges to achieving their scientific potential. These challenges arise primarily from the rapidly increasing size and complexity of HEP datasets that will be collected and the enormous computational, storage and networking resources that will be deployed by global collaborations in order to process, distribute and analyze them.Coupling such vast information technology resources to globally distributed collaborations of several thousand physicists requires extremely capable computing infrastructures supporting several key areas: (1) computing (providing sufficient computational and storage resources for all processing, simulation and analysis tasks undertaken by the collaborations); (2) networking (deploying high speed networks to transport data quickly between institutions around the world); (3) software (supporting simple and transparent access to data and software resources, regardless of location); (4) collaboration (providing tools that allow members full and fair access to all collaboration resources and enable distributed teams to work effectively, irrespective of location); and (5) education, training and outreach (providing resources and mechanisms for training students and for communicating important information to the public).It is believed that computing infrastructures based on Data Grids and optical networks can meet these challenges and can offer data intensive enterprises in high energy physics and elsewhere a comprehensive, scalable framework for collaboration and resource sharing. A number of Data Grid projects have been underway since 1999. Interestingly, the most exciting and far ranging of these projects are led by collaborations of high energy physicists, computer scientists and scientists from other disciplines in support of experiments with massive, near-term data needs. I review progress in this

  11. [Experimental and theoretical high energy physics

    International Nuclear Information System (INIS)

    We are carrying out a research program in high energy experimental particle physics. Studies of high energy hadronic interactions and leptoproduction processes continue using several experimental techniques. Progress has been made on the study of multiparticle production processes in nuclei. Ultra-high energy cosmic ray nucleus-nucleus interactions have been investigated by the Japanese American Cosmic Emulsion Experiment (JACEE) using balloon-borne emulsion chamber detectors. In the area of particle astrophysics, our studies of cosmic ray nuclear interactions have enabled us to make the world's most accurate determination of the composition of the cosmic rays above 1013 eV. We have the only detector that can observe interaction vertices and identify particles at energies up to 10--15 eV. Our observations are getting close to placing limits on the acceleration mechanisms postulated for pulsars in which the spin and magnetic moment axes are at different angles. In June, 1989 approval was given by NASA for our participation in the Space Station program. The SCINATT experiment will make use of emulsion chamber detectors, similar to the planned JACEE hybrid balloon flight detectors. These detectors will permit precise determination of secondary particle charges, momenta and rapidities, and the accumulation of data will be at least a factor of 10 to 100 greater than in balloon experiments. Emulsion chamber techniques are also employed in an experiment using accelerator heavy ion beams at CERN and Brookhaven National Laboratory to investigate particle production processes in central collisions of nuclei in the energy range 15--200A GeV. Our study of hadroproduction in lepton interactions is continuing with approval of another 8 months run for deep inelastic muon scattering experiment E665 at Fermilab

  12. Chimera states in bursting neurons

    Science.gov (United States)

    Bera, Bidesh K.; Ghosh, Dibakar; Lakshmanan, M.

    2016-01-01

    We study the existence of chimera states in pulse-coupled networks of bursting Hindmarsh-Rose neurons with nonlocal, global, and local (nearest neighbor) couplings. Through a linear stability analysis, we discuss the behavior of the stability function in the incoherent (i.e., disorder), coherent, chimera, and multichimera states. Surprisingly, we find that chimera and multichimera states occur even using local nearest neighbor interaction in a network of identical bursting neurons alone. This is in contrast with the existence of chimera states in populations of nonlocally or globally coupled oscillators. A chemical synaptic coupling function is used which plays a key role in the emergence of chimera states in bursting neurons. The existence of chimera, multichimera, coherent, and disordered states is confirmed by means of the recently introduced statistical measures and mean phase velocity.

  13. Bursts in intermittent aeolian saltation

    CERN Document Server

    Carneiro, M V; Herrmann, H J

    2014-01-01

    Close to the onset of Aeolian particle transport through saltation we find in wind tunnel experiments a regime of intermittent flux characterized by bursts of activity. Scaling laws are observed in the time delay between each burst and in the measurements of the wind fluctuations at the critical Shields number $\\theta_c$. The time delay between each burst decreases on average with the increase of the Shields number until saltation becomes non-intermittent and the sand flux becomes continuous. A numerical model for saltation including the wind-entrainment from the turbulent fluctuations can reproduce these observations and gives insight about their origin. We present here also for the first time measurements showing that with feeding it becomes possible to sustain intermittent flux even below the threshold $\\theta_c$ for natural saltation initiation.

  14. A soft X-ray lag detected in Centaurus A

    Science.gov (United States)

    Tachibana, Yutaro; Kawamuro, Taiki; Ueda, Yoshihiro; Shidatsu, Megumi; Arimoto, Makoto; Yoshii, Taketoshi; Yatsu, Yoichi; Saito, Yoshihiko; Pike, Sean; Kawai, Nobuyuki

    2016-06-01

    We performed time-lag analysis on the X-ray light curves of Centaurus A (Cen A) obtained by the Gas Slit Camera (GSC) aboard the Monitor of All-sky X-ray Image (MAXI) in three energy bands (2-4 keV, 4-10 keV, and 10-20 keV). We discovered a soft X-ray lag relative to higher energies (soft lag) on a timescale of days in a flaring episode by employing the discrete correlation function (DCF) and the z-transformed discrete correlation function (ZDCF) method. In the episode, a peak and a centroid in the DCF and the ZDCF was observed at a soft lag of ˜ 5 d in 2-4 keV versus 4-10 keV and in 4-10 keV versus 10-20 keV, and ˜ 10 d in 2-4 keV versus 10-20 keV. We found it difficult to explain the observed X-ray variation by a single energy injection with the one-zone synchrotron self-Compton (SSC) model, in which the soft lags in these three energy bands reflect the different cooling times of the relativistic electrons, by assuming the magnetic field and minimum Lorentz factor estimated from a broad-band spectral energy distribution. Alternatively, if the phenomenon is interpreted as cooling of Comptonizing electrons in a corona covering the accretion disk, the temperature of the corona producing the variable X-rays should be ˜ 10 keV for reconciliation with the soft lag in the energy range of 2-20 keV.

  15. Studies of high energy phenomena using muons

    International Nuclear Information System (INIS)

    This report covers the activities of the NIU high energy physics group as supported by DOE contract AC02-87ER40368 during the period from July of 1990 to June of 1991 and from February to March 1992. Our group has three main efforts which will be discussed in this paper. The first is the D0 experiment at the Fermilab proton-antiproton collider, with major emphasis on its muon system. The second is the involvement of a portion of the group in Fermilab Experiment 789 which involved detection of meson decays. Finally, we discuss our work with the SDC collaboration at the SSC

  16. High energy photons production in nuclear reactions

    International Nuclear Information System (INIS)

    Hard photon production, in nucleus-nucleus collisions, were studied at beam energies between 10 and 125 MeV. The main characteristics of the photon emission are deduced. They suggest that the neutron-proton collisions in the early stage of the reaction are the main source of high energy gamma-rays. An overview of the theoretical approaches is given and compared with experimental results. Theoretical attempts to include the contribution of charged pion exchange currents to photon production, in calculations of proton-nucleus-gamma and nucleus-nucleus-gamma reactions, showed suitable fitting with experimental data

  17. Future high energy colliders. Formal report

    International Nuclear Information System (INIS)

    This Report includes copies of transparencies and notes from the presentations made at the Symposium on Future High Energy Colliders, October 21-25, 1996 at the Institute for Theoretical Physics, University of California, Santa Barbara California, that was made available by the authors. Editing, reduction and changes to the authors contributions were made only to fulfill the printing and publication requirements. We would like to take this opportunity and thank the speakers for their informative presentations and for providing copies of their transparencies and notes for inclusion in this Report

  18. [Experimental and theoretical high energy physics program

    Energy Technology Data Exchange (ETDEWEB)

    Finley, J.; Gaidos, J.A.; Loeffler, F.J.; McIlwain, R.L.; Miller, D.H.; Palfrey, T.R.; Shibata, E.I.; Shipsey, I.P.

    1993-04-01

    Experimental and theoretical high-energy physics research at Purdue is summarized in a number of reports. Subjects treated include the following: the CLEO experiment for the study of heavy flavor physics; gas microstrip detectors; particle astrophysics; affine Kac{endash}Moody algebra; nonperturbative mass bounds on scalar and fermion systems due to triviality and vacuum stability constraints; resonance neutrino oscillations; e{sup +}e{sup {minus}} collisions at CERN; {bar p}{endash}p collisions at FNAL; accelerator physics at Fermilab; development work for the SDC detector at SSC; TOPAZ; D-zero physics; physics beyond the standard model; and the Collider Detector at Fermilab. (RWR)

  19. Very high energy gamma ray astrophysics

    International Nuclear Information System (INIS)

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

  20. Data Preservation in High Energy Physics

    CERN Document Server

    Mount, Richard; Le Diberder, Francois; Dubois-Felsmann, Gregory; Neal, Homer; Bellis, Matt; Boehnlein, Amber; Votava, Margaret; White, Vicky; Wolbers, Stephen; Konigsberg, Jacobo; Roser, Robert; Snider, Rick; Lucchesi, Donatella; Denisov, Dmitri; Soldner-Rembold, Stefan; Li, Qizhong; Varnes, Erich; Jonckheere, Alan; Gasthuber, Martin; Gülzow, Volker; Kemp, Yves; Ozerov, Dmitri; Diaconu, Cristinel; South, David; Lobodzinski, Bogdan; Olsson, Jan; Haas, Tobias; Wrona, Krzysztof; Szuba, Janusz; Schnell, Gunar; Sasaki, Takashi; Katayama, Nobu; Hernandez, Fabio; Mele, Salvatore; Holzner, Andre; Hemmer, Frederic; Schroeder, Matthias; Barring, Olof; Brun, Rene; Maggi, Marcello; Igo-Kemenes, Peter; Van Wezel, Jos; Heiss, Andreas; Chen, Gang; Wang, Yifang; Asner, David; Riley, Daniel; Corney, David; Gordon, John

    2009-01-01

    Data from high-energy physics (HEP) experiments are collected with significant financial and human effort and are mostly unique. At the same time, HEP has no coherent strategy for data preservation and re-use. An inter-experimental Study Group on HEP data preservation and long-term analysis was convened at the end of 2008 and held two workshops, at DESY (January 2009) and SLAC (May 2009). This document is an intermediate report to the International Committee for Future Accelerators (ICFA) of the reflections of this Study Group.

  1. High energy ion implantation for IC processing

    International Nuclear Information System (INIS)

    In this thesis the results of fundamental research on high energy ion implantation in silicon are presented and discussed. The implantations have been carried out with the 500 kV HVEE ion implantation machine, that was acquired in 1981 by the IC technology and Electronics group at Twente University of Technology. The damage and anneal behaviour of 1 MeV boron implantations to a dose of 1013/cm2 have been investigated as a function of anneal temperature by sheet resistance, Hall and noise measurements. (Auth.)

  2. GEM applications outside high energy physics

    CERN Document Server

    Duarte Pinto, Serge

    2013-01-01

    From its invention in 1997, the Gas Electron Multiplier has been applied in nuclear and high energy physics experiments. Over time however, other applications have also exploited the favorable properties of GEMs. The use of GEMs in these applications will be explained in principle and practice. This paper reviews applications in research, beam instrumentation and homeland security. The detectors described measure neutral radiations such as photons, x-rays, gamma rays and neutrons, as well as all kinds of charged radiation. This paper provides an overview of the still expanding range of possibilities of this versatile detector concept.

  3. Correlations in high-energy interactions

    International Nuclear Information System (INIS)

    The short-range correlations in rapidity whose existence has been firmly established in high-energy interactions are used to explain chaotic multiplicity behavior in proton-nucleon collisions at 800 GeV. In order to determine the values of higher-order moments from the second-order moment, we have used the pure birth approximation which is in agreement with the ''linked pair'' approximation of Carruthers. The calculated values of the normalized factorial moments for a given bin size show a good agreement with our data

  4. High energy physics after the SPS collider

    International Nuclear Information System (INIS)

    A review is given of high energy hadronic data after the coming in operation of the CERN-SPS Collider. The data are discussed with reference to theoretical models. After an Introduction (Sec. 1), the low-Psub(T) data are presented in Sec. 2. Sec. 3 deals with large-Psub(T) data and (briefly) jets. Sec. 5 is devoted to a brief review of the problems left open from a comparison with cosmic ray physics. In Sec. 6, finally, some conclusions are drawn

  5. A high energy photon polarimeter for astrophysics

    OpenAIRE

    Eingorn, Maxim; Fernando, Lakma; Vlahovic, Branislav; Ilie, Cosmin; Wojtsekhowski, Bogdan; Urciuoli, Guido Maria; De Persio, Fulvio; Meddi, Franco

    2015-01-01

    A high-energy photon polarimeter for astrophysics studies in the energy range from 20 MeV to 1000 MeV is considered. The proposed concept uses a stack of silicon micro-strip detectors where they play the roles of both a converter and a tracker. The purpose of this paper is to outline the parameters of such a polarimeter and to estimate the productivity of measurements. Our study supported by a Monte Carlo simulation shows that with a one-year observation period the polarimeter will provide 6%...

  6. UNIVERSITY OF ARIZONA HIGH ENERGY PHYSICS PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    Rutherfoord, John P. [University of Arizona; Johns, Kenneth A. [University of Arizona; Shupe, Michael A. [University of Arizona; Cheu, Elliott C. [University of Arizona; Varnes, Erich W. [University of Arizona; Dienes, Keith [University of Arizona; Su, Shufang [University of Arizona; Toussaint, William Doug [University of Arizona; Sarcevic, Ina [University of Arizona

    2013-07-29

    The High Energy Physics Group at the University of Arizona has conducted forefront research in elementary particle physics. Our theorists have developed new ideas in lattice QCD, SUSY phenomenology, string theory phenomenology, extra spatial dimensions, dark matter, and neutrino astrophysics. The experimentalists produced significant physics results on the ATLAS experiment at CERN's Large Hadron Collider and on the D0 experiment at the Fermilab Tevatron. In addition, the experimentalists were leaders in detector development and construction, and on service roles in these experiments.

  7. Grid Computing in High Energy Physics Experiments

    Czech Academy of Sciences Publication Activity Database

    Adamová, Dagmar; Saiz, P.

    Rijeka: InTech, 2012 - (Maad, S.), s. 181-219 ISBN 978-953-51-0604-3 R&D Projects: GA MŠk LA08015; GA MŠk 1P04LA211; GA MŠk LC07048 Institutional support: RVO:61389005 Keywords : grid computing * CERN * Partide physics Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders http://www.intechopen.com/ books /grid-computing-technology- and -applications-widespread-coverage- and -new-horizons/grid-computing-in-high-energy-physics-experiments

  8. Predictions of High Energy Experimental Results

    Directory of Open Access Journals (Sweden)

    Comay E.

    2010-10-01

    Full Text Available Eight predictions of high energy experimental results are presented. The predictions contain the $Sigma ^+$ charge radius and results of two kinds of experiments using energetic pionic beams. In addition, predictions of the failure to find the following objects are presented: glueballs, pentaquarks, Strange Quark Matter, magnetic monopoles searched by their direct interaction with charges and the Higgs boson. The first seven predictions rely on the Regular Charge-Monopole Theory and the last one relies on mathematical inconsistencies of the Higgs Lagrangian density.

  9. Weak interactions at high energies. [Lectures, review

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, J.

    1978-08-01

    Review lectures are presented on the phenomenological implications of the modern spontaneously broken gauge theories of the weak and electromagnetic interactions, and some observations are made about which high energy experiments probe what aspects of gauge theories. Basic quantum chromodynamics phenomenology is covered including momentum dependent effective quark distributions, the transverse momentum cutoff, search for gluons as sources of hadron jets, the status and prospects for the spectroscopy of fundamental fermions and how fermions may be used to probe aspects of the weak and electromagnetic gauge theory, studies of intermediate vector bosons, and miscellaneous possibilities suggested by gauge theories from the Higgs bosons to speculations about proton decay. 187 references. (JFP)

  10. [Studies of high energy phenomena using muons

    International Nuclear Information System (INIS)

    This report covers the activities of the NIU high energy physics group as supported by DOE contract FG02-91ER40641 during the period from March 1991 to December 1991. Our group has three main efforts. The first is the D0 experiment at the Fermilab proton-antiproton collider, with major emphasis on its muon system. The second is the involvement of a portion of the group in Fermilab Experiment 789. Finally, we are also members of the SDC collaboration at the SSC

  11. Studies in theoretical high energy particle physics

    International Nuclear Information System (INIS)

    Theoretical work on the following topics is briefly summarized: symmetry structure of conformal affine Toda model and KP hierarchy; solitons in the affine Toda and conformal affine Toda models; classical r-matrices and Poisson bracket structures on infinite-dimensional groups; R-matrix formulation of KP hierarchies and their gauge equivalence; statistics of particles and solitons; charge quantization in the presence of an Alice string; knotting and linking of nonabelian flux; electric dipole moments; neutrino physics in gauge theories; CP violation in the high energy colliders; supersymmetric quantum mechanics; parton structure functions in nuclei; dual parton model. 38 refs

  12. [Experimental and theoretical high energy physics program

    International Nuclear Information System (INIS)

    Experimental and theoretical high-energy physics research at Purdue is summarized in a number of reports. Subjects treated include the following: the CLEO experiment for the study of heavy flavor physics; gas microstrip detectors; particle astrophysics; affine Kac endash Moody algebra; nonperturbative mass bounds on scalar and fermion systems due to triviality and vacuum stability constraints; resonance neutrino oscillations; e+e- collisions at CERN; bar p endash p collisions at FNAL; accelerator physics at Fermilab; development work for the SDC detector at SSC; TOPAZ; D-zero physics; physics beyond the standard model; and the Collider Detector at Fermilab

  13. High energy permanent magnets in electromechanics

    International Nuclear Information System (INIS)

    A review of fields of application of permanent magnets is given. Magnetic, electrical, mechanical and service properties of sintered hard-magnetic alloys based on rare earths and 3d metals SmCo5, Sm(Co, Fe, Cu, Zr)2 Nd2, Fe14B, Nd1.8Dy0.2Fe14B are given. The merits of high-energy magnetic materials are stated, and it is noted that it is important to improve fabrication practice of large permanent magnets

  14. Computing support for High Energy Physics

    Energy Technology Data Exchange (ETDEWEB)

    Avery, P.; Yelton, J. [Univ. of Florida, Gainesville, FL (United States)

    1996-12-01

    This computing proposal (Task S) is submitted separately but in support of the High Energy Experiment (CLEO, Fermilab, CMS) and Theory tasks. The authors have built a very strong computing base at Florida over the past 8 years. In fact, computing has been one of the main contributions to their experimental collaborations, involving not just computing capacity for running Monte Carlos and data reduction, but participation in many computing initiatives, industrial partnerships, computing committees and collaborations. These facts justify the submission of a separate computing proposal.

  15. Photomask specifications for high energy physics detectors

    CERN Document Server

    Pindo, M

    2002-01-01

    Planar technologies used for radiation detector fabrication imply an extensive use of photomasks whose characteristics are critical in determining final detector performance. Compatibly with their manufacturing process, photomasks must satisfy the application-specific requirements dictated both by wafer manufacturers and detector final users. The design and realization of microstrip and pixel detectors, widely used in high energy physics experiments, ask for intensive scientific effort, advanced technology and important economical investments. Photomask specification definition is one of the fundamental steps to optimize detector fabrication processes and fulfill experimental requirements at the most appropriate cost.

  16. High energy approximations in quantum field theory

    International Nuclear Information System (INIS)

    New theoretical methods in hadron physics based on a high-energy perturbation theory are discussed. The approximated solutions to quantum field theory obtained by this method appear to be sufficiently simple and rich in structure to encourage hadron dynamics studies. Operator eikonal form for field - theoretic Green's functions is derived and discussion is held on how the eikonal perturbation theory is to be renormalized. This method is extended to massive quantum electrodynamics of scalar charged bosons. Possible developments and applications of this theory are given

  17. Stochastic aspects of QCD at high energy

    International Nuclear Information System (INIS)

    I present a pedagogical discussion of the influence of particle number fluctuations on the high energy evolution in QCD. I emphasize the event-by-event description and the correspondence with the problem of ''fluctuating pulled fronts'' in statistical physics. I explain that the correlations generated by fluctuations reduce the phase space for BFKL evolution up to saturation. Because of that, the evolution slows down, and the rate for the energy increase of the saturation momentum is considerably decreased. I discuss the diagrammatic interpretation of the particle number fluctuations in terms of pomeron loops. (orig.)

  18. The First FERMI-LAT Gamma-Ray Burst Catalog

    Science.gov (United States)

    Ackermann, M.; Ajello, M.; Asano, K.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bhat, P. N.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Burgess, J. Michael; Buson, S.; Byrne, D.; Caliandro, G. A.; Ferrara, E. C.; Gehrels, N.; Guiriec, S.; McEnery, J. E.; Nemmen, R.; Perkins, J. S.; Racusin, J. L.; Thompson, D. J.; Kouveliotou, C.

    2013-01-01

    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy great than (20 MeV) gamma-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected above 100 MeV and 7 GRBs above approximately 20 MeV. The first Fermi-LAT catalog of GRBs is a compilation of these detections and provides a systematic study of high-energy emission from GRBs for the first time. To generate the catalog, we examined 733 GRBs detected by the Gamma-Ray Burst Monitor (GBM) on Fermi and processed each of them using the same analysis sequence. Details of the methodology followed by the LAT collaboration for the GRB analysis are provided. We summarize the temporal and spectral properties of the LAT-detected GRBs. We also discuss characteristics of LAT-detected emission such as its delayed onset and longer duration compared with emission detected by the GBM, its power-law temporal decay at late times, and the fact that it is dominated by a power-law spectral component that appears in addition to the usual Band model.

  19. How else can we detect Fast Radio Bursts?

    CERN Document Server

    Lyutikov, Maxim

    2016-01-01

    We discuss possible electromagnetic signals accompanying Fast Radio Bursts (FRBs) that are expected in the scenario where FRBs originate in neutron star magnetospheres. For models involving Crab-like giant pulses, no appreciable contemporaneous emission is expected at other wavelengths. Magnetar giant flares, driven by the reconfiguration of the magnetosphere, however, can produce both contemporaneous bursts at other wavelengths as well as afterglow-like emission. We conclude that the best chances are: (i) prompt short GRB-like emission; (ii) a contemporaneous optical flash that can reach naked eye peak luminosity (but only for a few milliseconds); (iii) a high energy afterglow emission. Case (i) could be tested by coordinated radio and high-energy experiments. Case (ii) could be seen by the Palomar Transient Factory in a 60-second frame as a transient object of $m=15-20$ magnitude with an expected optical detection rate of about 0.1~hr$^{-1}$, an order of magnitude higher than in radio. EVRYSCOPE could also ...

  20. The First Fermi-LAT Gamma-Ray Burst Catalog

    Science.gov (United States)

    Ackermann, M.; Ajello, M.; Asano, K.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bhat, P. N.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burgess, J. Michael; Buson, S.; Byrne, D.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Connaughton, V.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Desiante, R.; Digel, S. W.; Dingus, B. L.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Favuzzi, C.; Ferrara, E. C.; Fitzpatrick, G.; Foley, S.; Franckowiak, A.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Goldstein, A.; Granot, J.; Grenier, I. A.; Grove, J. E.; Gruber, D.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Hayashida, M.; Horan, D.; Hou, X.; Hughes, R. E.; Inoue, Y.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Kataoka, J.; Kawano, T.; Kippen, R. M.; Knödlseder, J.; Kocevski, D.; Kouveliotou, C.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lee, S.-H.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McBreen, S.; McEnery, J. E.; McGlynn, S.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Murgia, S.; Nemmen, R.; Nuss, E.; Nymark, T.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Paciesas, W. S.; Paneque, D.; Panetta, J. H.; Pelassa, V.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Preece, R.; Racusin, J. L.; Rainò, S.; Rando, R.; Rau, A.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Romoli, C.; Roth, M.; Ryde, F.; Saz Parkinson, P. M.; Schalk, T. L.; Sgrò, C.; Siskind, E. J.; Sonbas, E.; Spandre, G.; Spinelli, P.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takeuchi, Y.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tierney, D.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Tronconi, V.; Usher, T. L.; Vandenbroucke, J.; van der Horst, A. J.; Vasileiou, V.; Vianello, G.; Vitale, V.; von Kienlin, A.; Winer, B. L.; Wood, K. S.; Wood, M.; Xiong, S.; Yang, Z.

    2013-11-01

    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy (gsim 20 MeV) γ-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected above 100 MeV and 7 GRBs above ~20 MeV. The first Fermi-LAT catalog of GRBs is a compilation of these detections and provides a systematic study of high-energy emission from GRBs for the first time. To generate the catalog, we examined 733 GRBs detected by the Gamma-Ray Burst Monitor (GBM) on Fermi and processed each of them using the same analysis sequence. Details of the methodology followed by the LAT collaboration for the GRB analysis are provided. We summarize the temporal and spectral properties of the LAT-detected GRBs. We also discuss characteristics of LAT-detected emission such as its delayed onset and longer duration compared with emission detected by the GBM, its power-law temporal decay at late times, and the fact that it is dominated by a power-law spectral component that appears in addition to the usual Band model.