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8 results on '"O. A. Brusova"'

1. Search for correlations between HiRes stereo events and active galactic nuclei

Author

R. C. Gray, B. T. Stokes, C. Song, B. C. Knapp, J. R. Thomas, John N. Matthews, J. H. Boyer, Segev BenZvi, L. M. Scott, A. O’Neill, R. Riehle, C. Cannon, O. A. Brusova, Pierre Sokolsky, Dale Tupa, G. Archbold, P. Hüntemeyer, Konstantin Belov, W. Deng, Douglas Bergman, N. Sasaki, C. B. Finley, M. M. Maestas, M. A. Kirn, S. A. Blake, Gordon Thomson, M. D. Roberts, R. W. Springer, E. J. Mannel, C. C. H. Jui, Steve Schnetzer, E. C. Loh, G. Sinnis, Gareth Hughes, S. B. Thomas, C. M. Hoffman, Michael H. Holzscheiter, Tareq Abu-Zayyad, B. F. Jones, M. Seman, Y. Fedorova, J. D. Smith, Kevin Reil, N. Manago, J. F. Amman, J. Findlay, D. Rodriguez, Z. Cao, Lawrence Wiencke, Dmitri Ivanov, R. Snow, John Belz, S. A. Moore, L. Perera, Xiang Zhang, L. J. Marek, K. Kim, M. Allen, William Hanlon, Rasha Abbasi, C. A. Painter, K. Martens, A. Zech, G. W. Burt, and S. R. Stratton

Subjects
Physics, Active galactic nucleus, 010308 nuclear & particles physics, Astrophysics (astro-ph), Northern Hemisphere, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Cosmic ray, Astrophysics, Positive correlation, 01 natural sciences, Auger, Data set, Correlation, 0103 physical sciences, 010303 astronomy & astrophysics, Southern Hemisphere
Abstract

We have searched for correlations between the pointing directions of ultrahigh energy cosmic rays observed by the High Resolution Fly's Eye experiment and Active Galactic Nuclei (AGN) visible from its northern hemisphere location. No correlations, other than random correlations, have been found. We report our results using search parameters prescribed by the Pierre Auger collaboration. Using these parameters, the Auger collaboration concludes that a positive correlation exists for sources visible to their southern hemisphere location. We also describe results using two methods for determining the chance probability of correlations: one in which a hypothesis is formed from scanning one half of the data and tested on the second half, and another which involves a scan over the entire data set. The most significant correlation found occurred with a chance probability of 24%., 13 pages, 1 table, 5 figures

Published
2008

2. Studies of systematic uncertainties in the estimation of the monocular aperture of the HiRes experiment

Author

B. F. Jones, A. O’Neill, K. Martens, John Belz, G. W. Burt, O. A. Brusova, A. Zech, Pierre Sokolsky, P. Hüntemeyer, L. M. Scott, C. B. Finley, L. J. Marek, Dale Tupa, William Hanlon, Rasha Abbasi, C. C. H. Jui, John N. Matthews, E. C. Loh, John Matthews, S. B. Thomas, B. T. Stokes, J. R. Thomas, R. W. Springer, Konstantin Belov, B. C. Connolly, G. Archbold, Lawrence Wiencke, N. Manago, W. Deng, Douglas Bergman, C. Song, S. Y. Ben Zvi, Steve Schnetzer, L. Perera, J. D. Smith, S. A. Blake, M. Sasaki, Xiang Zhang, M. D. Roberts, Kevin Reil, Gareth Hughes, J. F. Amman, M. M. Maestas, R. Riehle, Tareq Abu-Zayyad, Z. Cao, C. A. Painter, C. M. Hoffman, D. Rodriguez, G. Sinnis, S. A. Moore, S. Westerhoff, Y. Fedorova, K. Kim, M. A. Kirn, R. C. Gray, Gordon Thomson, and Michael H. Holzscheiter

Subjects
Physics, Monocular, business.industry, Aperture, Astrophysics (astro-ph), Monte Carlo method, Detector, FOS: Physical sciences, Astronomy and Astrophysics, Cosmic ray, Interaction model, Astrophysics, 01 natural sciences, Power law, 3. Good health, Computational physics, Air shower, Optics, 0103 physical sciences, 010306 general physics, business, 010303 astronomy & astrophysics
Abstract

We have studied several sources of systematic uncertainty in calculating the aperture of the High Resolution Fly's Eye experiment (HiRes) in monocular mode, primarily as they affect the HiRes-II site. The energy dependent aperture is determined with detailed Monte Carlo simulations of the air showers and the detector response. We have studied the effects of changes to the input energy spectrum and composition used in the simulation. A realistic shape of the input spectrum is used in our analysis in order to avoid biases in the aperture estimate due to the limited detector resolution. We have examined the effect of exchanging our input spectrum with a simple E^{-3} power law in the "ankle" region. Uncertainties in the input composition are shown to be significant for energies below about 10^{18} eV for data from the HiRes-II detector. Another source of uncertainties is the choice of the hadronic interaction model in the air shower generator. We compare the aperture estimate for two different models: QGSJet01 and SIBYLL 2.1. We also describe the implications of employing an atmospheric database with hourly measurements of the aerosol component, instead of using an average as has been used in our previously published measurements of the monocular spectra., Comment: 27 pages, 15 figures, revision

Published
2007

3. Analysis of large-scale anisotropy of ultra-high energy cosmic rays in HiRes data

Author

B. F. Jones, James F. Amann, Dale Tupa, P. Tinyakov, Kevin Reil, Konstantin Belov, R. Riehle, C. Cannon, J. Findlay, John Belz, William Hanlon, K. Kim, O. A. Brusova, P. Hüntemeyer, Hylke B. J. Koers, R. W. Springer, K. Martens, Lawrence Wiencke, M. Sasaki, M. M. Maestas, Steve Schnetzer, Gordon Thomson, Michael H. Holzscheiter, Dmitri Ivanov, L. J. Marek, G. W. Burt, Rasha Abbasi, J. D. Smith, Gareth Hughes, Tareq Abu-Zayyad, C. B. Finley, A. Zech, Douglas Bergman, Ben Stokes, L. M. Scott, R. C. Gray, N. Manago, Pierre Sokolsky, Xiang Zhang, D. C. Rodriguez, C. Song, Gus Sinnis, L. Perera, M. Allen, G. Archbold, S. R. Stratton, A. O’Neill, J. R. Thomas, M. D. Roberts, C. M. Hoffman, Y. Fedorova, W. Deng, John N. Matthews, C. A. Painter, Z. Cao, S. A. Moore, C. C. H. Jui, S. B. Thomas, M. A. Kirn, John Matthews, Samuel Blake, and E. C. Loh

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, Isotropy, FOS: Physical sciences, Flux, Astronomy and Astrophysics, Cosmic ray, Astrophysics, 01 natural sciences, Universe, Space and Planetary Science, TRACER, 0103 physical sciences, ddc:520, Ultra-high-energy cosmic ray, Astrophysics - High Energy Astrophysical Phenomena, 010306 general physics, Anisotropy, 010303 astronomy & astrophysics, media_common, Free parameter
Abstract

Stereo data collected by the HiRes experiment over a six year period are examined for large-scale anisotropy related to the inhomogeneous distribution of matter in the nearby Universe. We consider the generic case of small cosmic-ray deflections and a large number of sources tracing the matter distribution. In this matter tracer model the expected cosmic ray flux depends essentially on a single free parameter, the typical deflection angle theta. We find that the HiRes data with threshold energies of 40 EeV and 57 EeV are incompatible with the matter tracer model at a 95% confidence level unless theta is larger than 10 degrees and are compatible with an isotropic flux. The data set above 10 EeV is compatible with both the matter tracer model and an isotropic flux., 9 pages, 5 Postscript figures

Published
2010

4. Measurement of the Flux of Ultra High Energy Cosmic Rays by the Stereo Technique

Author

B. F. Jones, M. A. Kirn, C. Cannon, O. A. Brusova, Gordon Thomson, P. Hüntemeyer, James F. Amann, W. Deng, B. K. Zhang, C. B. Finley, Michael H. Holzscheiter, R. Riehle, S. A. Blake, Steve Schnetzer, K. Martens, A. Zech, G. Sinnis, John Matthews, R. C. Gray, C. M. Hoffman, Y. Fedorova, J. D. Smith, R. W. Springer, D. Rodriguez, R. Snow, S. R. Stratton, Gareth Hughes, John N. Matthews, Tareq Abu-Zayyad, Dmitri Ivanov, K. Kim, G. Archbold, Z. Cao, Kevin Reil, S. A. Moore, Dale Tupa, L. M. Scott, E. C. Loh, L. Perera, Konstantin Belov, C. C. H. Jui, M. M. Maestas, S. B. Thomas, B. T. Stokes, J. R. Thomas, M. Al-Seady, Y. Zhang, Pierre Sokolsky, A. O’Neill, G. W. Burt, Lawrence Wiencke, M. Sasaki, J. Findlay, John Belz, M. D. Roberts, L. J. Marek, Douglas Bergman, C. A. Painter, William Hanlon, Rasha Abbasi, N. Manago, Xiang Zhang, and M. Allen

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Flux, High resolution, Stereoscopy, Cosmic ray, 01 natural sciences, law.invention, Optics, law, 0103 physical sciences, Ultra-high-energy cosmic ray, Ultrahigh energy, 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Monocular, 010308 nuclear & particles physics, business.industry, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, business, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The High Resolution Fly's Eye experiment has measured the flux of ultrahigh energy cosmic rays using the stereoscopic air fluorescence technique. The HiRes experiment consists of two detectors that observe cosmic ray showers via the fluorescence light they emit. HiRes data can be analyzed in monocular mode, where each detector is treated separately, or in stereoscopic mode where they are considered together. Using the monocular mode the HiRes collaboration measured the cosmic ray spectrum and made the first observation of the Greisen-Zatsepin-Kuzmin cutoff. In this paper we present the cosmic ray spectrum measured by the stereoscopic technique. Good agreement is found with the monocular spectrum in all details., 20 pages, 10 figures

Published
2009

5. Indications of Proton-Dominated Cosmic Ray Composition above 1.6 EeV

Author

R U, Abbasi, T, Abu-Zayyad, M, Al-Seady, M, Allen, J F, Amman, R J, Anderson, G, Archbold, K, Belov, J W, Belz, D R, Bergman, S A, Blake, O A, Brusova, G W, Burt, C, Cannon, Z, Cao, W, Deng, Y, Fedorova, C B, Finley, R C, Gray, W F, Hanlon, C M, Hoffman, M H, Holzscheiter, D, Ivanov, G, Hughes, P, Hüntemeyer, B F, Jones, C C H, Jui, K, Kim, M A, Kirn, E C, Loh, J, Liu, J P, Lundquist, M M, Maestas, N, Manago, L J, Marek, K, Martens, J A J, Matthews, J N, Matthews, S A, Moore, A, O'Neill, C A, Painter, L, Perera, K, Reil, R, Riehle, M, Roberts, D, Rodriguez, N, Sasaki, S R, Schnetzer, L M, Scott, G, Sinnis, J D, Smith, P, Sokolsky, C, Song, R W, Springer, B T, Stokes, S, Stratton, S B, Thomas, J R, Thomas, G B, Thomson, D, Tupa, A, Zech, and X, Zhang

Subjects
Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Proton, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Astrophysics::Instrumentation and Methods for Astrophysics, General Physics and Astronomy, FOS: Physical sciences, Cosmic ray, Astrophysics, Composition (combinatorics), Energy spectrum, ddc:550, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report studies of ultra-high energy cosmic ray composition via analysis of depth of airshower maximum (Xmax), for airshower events collected by the High Resolution Fly's Eye (HiRes) observatory. The HiRes data are consistent with a constant elongation rate d/d(log(E)) of 47.9 +- 6.0 (stat.) +- 3.2 (syst.)g/cm^2/decade for energies between 1.6 EeV and 63 EeV, and are consistent with a predominantly protonic composition of cosmic rays when interpreted via the QGSJET01 and QGSJET-II high-energy hadronic interaction models. These measurements constrain models in which the galactic-to-extragalactic transition is the cause of the energy spectrum "ankle' at 4 EeV., Comment: 11 pages, 4 figures, accepted for publication in Physical Review Letters

Published
2009
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6. An upper limit on the electron-neutrino flux from the HiRes detector

Author

S. Y. Ben Zvi, M. Allen, B. F. Jones, J. Findlay, John Belz, R. C. Gray, Konstantin Belov, N. Manago, R. Riehle, J. D. Smith, Dmitri Ivanov, L. Perera, Ben Stokes, R. W. Springer, L. J. Marek, E. C. Loh, Douglas Bergman, L. M. Scott, G. Archbold, C. A. Painter, Xiang Zhang, P. Huentemeyer, J. R. Thomas, M. D. Roberts, J. H. Boyer, E. J. Mannel, C. Cannon, S. R. Stratton, Kevin Reil, O. A. Brusova, Z. Cao, C. M. Hoffman, A. O’Neill, Samuel Blake, G. W. Burt, C. B. Finley, S. A. Moore, K. Martens, Gareth Hughes, Pierre Sokolsky, Y. Fedorova, D. C. Rodriguez, John Matthews, Tareq Abu-Zayyad, Steve Schnetzer, William Hanlon, Rasha Abbasi, G. Sinnis, M. A. Kirn, C. Song, A. Zech, B. C. Knapp, M. M. Maestas, M. Seman, W. Deng, Lawrence Wiencke, James F. Amann, M. Sasaki, C. C. H. Jui, S. B. Thomas, John N. Matthews, Dale Tupa, R. Snow, K. Kim, A. Biesiadecka, Gordon Thomson, and Michael H. Holzscheiter

Subjects
Physics, 010308 nuclear & particles physics, Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, Monte Carlo method, Detector, Astrophysics (astro-ph), Bremsstrahlung, Flux, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, 7. Clean energy, Charged particle, Nuclear physics, Pair production, 13. Climate action, Space and Planetary Science, 0103 physical sciences, High Energy Physics::Experiment, Neutrino, 010306 general physics, Electron neutrino
Abstract

Air-fluorescence detectors such as the High Resolution Fly's Eye (HiRes) detector are very sensitive to upward-going, Earth-skimming ultrahigh energy electron-neutrino-induced showers. This is due to the relatively large interaction cross sections of these high-energy neutrinos and to the Landau-Pomeranchuk-Migdal (LPM) effect. The LPM effect causes a significant decrease in the cross sections for bremsstrahlung and pair production, allowing charged-current electron-neutrino-induced showers occurring deep in the Earth's crust to be detectable as they exit the Earth into the atmosphere. A search for upward-going neutrino-induced showers in the HiRes-II monocular dataset has yielded a null result. From an LPM calculation of the energy spectrum of charged particles as a function of primary energy and depth for electron-induced showers in rock, we calculate the shape of the resulting profile of these showers in air. We describe a full detector Monte Carlo simulation to determine the detector response to upward-going electron-neutrino-induced cascades and present an upper limit on the flux of electron-neutrinos., Comment: 13 pages, 3 figures. submitted to Astrophysical Journal

Published
2008
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7. First Observation of the Greisen-Zatsepin-Kuzmin Suppression

Author

R. W. Springer, Steve Schnetzer, B. T. Stokes, J. R. Thomas, N. Manago, John N. Matthews, Gordon Thomson, Kevin Reil, Douglas Bergman, Konstantin Belov, Michael H. Holzscheiter, Xiang Zhang, Naruo Sasaki, A. O’Neill, W. Deng, L. M. Scott, S. A. Blake, John Matthews, M. D. Roberts, Z. Cao, B. C. Connolly, C. M. Hoffman, S. A. Moore, Y. Fedorova, J. F. Amman, John Belz, M. Allen, L. J. Marek, C. A. Painter, E. C. Loh, Gareth Hughes, G. Archbold, Tareq Abu-Zayyad, G. W. Burt, William Hanlon, Rasha Abbasi, C. C. H. Jui, R. Riehle, S. B. Thomas, Lawrence Wiencke, A. Zech, C. Song, Dale Tupa, M. A. Kirn, G. Sinnis, S. Y. Ben Zvi, J. D. Smith, R. C. Gray, D. Rodriguez, L. Perera, S. Westerhoff, K. Kim, B. F. Jones, C. Cannon, O. A. Brusova, P. Hüntemeyer, C. B. Finley, K. Martens, M. M. Maestas, and Pierre Sokolsky

Subjects
Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), General Physics and Astronomy, High resolution, FOS: Physical sciences, Cosmic ray, Astrophysics, 01 natural sciences, 0103 physical sciences, Energy spectrum, Cutoff, Ultrahigh energy, 010303 astronomy & astrophysics, Energy (signal processing)
Abstract

The High Resolution Fly's Eye (HiRes) experiment has observed the Greisen-Zatsepin-Kuzmin suppression (called the GZK cutoff) with a statistical significance of five standard deviations. HiRes' measurement of the flux of ultrahigh energy (UHE) cosmic rays shows a sharp suppression at an energy of $6 \times 10^{19}$ eV, consistent with the expected cutoff energy. We observe the ``ankle'' of the cosmic-ray energy spectrum as well, at an energy of $4 \times 10^{18}$ eV. We describe the experiment, data collection, analysis, and estimate the systematic uncertainties. The results are presented and the calculation of the statistical significance of our observation is described., Comment: 4 pages, 3 figures, accepted by and to appear in PRL

Published
2007
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8. The Telescope Array experiment: status and prospects

Author

I. S. Cho, Shigeharu Udo, R. W. Springer, Hiroyuki Sagawa, Inkyu Park, Tomoyuki Nakamura, John Belz, Y. Murano, Samuel Blake, Shoichi Ogio, R. Azuma, T. Benno, Taka Tomida, Koichi Tanaka, L. M. Scott, Y. H. Yun, Shingo Kawana, Y. Hayashi, T. Iguchi, Noritaka Shimizu, Toshiyuki Nonaka, F. Cohen, Tomohiro Matsuda, Rasha Abbasi, S. Suzuki, J. Yang, Douglas Bergman, Shunsuke Ozawa, T.-A. Shibata, M Teshima, K Kasahara, Gordon Thomson, John N. Matthews, Robert Cady, K. Martens, S. Oh, Hideaki Shimodaira, B. G. Cheon, J. R. Thomas, K. Hiyama, J. H. Park, O. A. Brusova, J. D. Smith, Miguel Mostafa, Hideki Tanaka, Michael J. Taylor, Y. J. Kwon, S. Machida, K. Doura, Pierre Sokolsky, Akimichi Taketa, R. Torii, Hideyuki Ohoka, Naoaki Hayashida, P. Huentemeyer, Gareth Hughes, J A J Matthews, A. Ohshima, Nobuyuki Sakurai, S. Kawakami, Hisono Tokuno, Tareq Abu-Zayyad, M. Takeda, Y. Yamakawa, Akira Endo, Y. Kondo, T. Chung, M. Chikawa, Vincent B Wickwar, Hideyuki Kawai, K. Ikuta, H. Yoshii, S. Yoshida, Z. Cao, Eiji Kido, K. Kadota, K. Miyata, K. Hibino, Mayuko Minamino, K. Honda, Fumio Kakimoto, Masaaki Tanaka, H. Fujii, Jonathan F. Ormes, Y. Wada, Lawrence Wiencke, Y. Uchihori, T. Matsuyama, Gus Sinnis, Takaaki Ishii, D. C. Rodriguez, T. D. Wilkerson, T. Kanbe, H. Yamaoka, Yoshiki Tsunesada, Daisuke Ikeda, Y. Unno, S. R. Stratton, Jyunsei Chiba, T. Fukuda, Masaki Fukushima, Takeshi Okuda, T. Doyle, N. Inoue, M. Ohnishi, C. C. H. Jui, K. Hayashi, Yuichiro Tameda, S. B. Thomas, S. W. Nam, and Masato Takita

Subjects
Physics, History, Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Cosmic ray, Computer Science Applications, Education, law.invention, Telescope, law, Energy spectrum, High Energy Physics::Experiment, Detector array, Energy (signal processing)
Abstract

Telescope Array (TA) is a hybrid detector of a surface detector array and fluorescence telescopes. This hybrid detector will measure the energy spectrum, anisotropy and composition of ultra-high energy cosmic rays (UHECRs) to identify their origin. The almost construction of the detector has been completed in May 2007, and the detector is running under test and adjustments. The first hybrid observation with the full configuration is planned in beginning of 2008. In this paper the status and prospects of TA detector is described.

Published
2008

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