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Your search keyword '"Gray, R. C."' showing total 3 results
Start Over Author "Gray, R. C." Publisher american physical society

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3 results on '"Gray, R. C."'

1. Indications of proton-dominated cosmic-ray composition above 1.6 EeV.

Author

Abbasi RU, Abu-Zayyad T, Al-Seady M, Allen M, Amman JF, Anderson RJ, Archbold G, Belov K, Belz JW, Bergman DR, Blake SA, Brusova OA, Burt GW, Cannon C, Cao Z, Deng W, Fedorova Y, Finley CB, Gray RC, Hanlon WF, Hoffman CM, Holzscheiter MH, Ivanov D, Hughes G, Hüntemeyer P, Ivanov D, Jones BF, Jui CC, Kim K, Kirn MA, Loh EC, Liu J, Lundquist JP, Maestas MM, Manago N, Marek LJ, Martens K, Matthews JA, Matthews JN, Moore SA, O'Neill A, Painter CA, Perera L, Reil K, Riehle R, Roberts M, Rodriguez D, Sasaki N, Schnetzer SR, Scott LM, Sinnis G, Smith JD, Sokolsky P, Song C, Springer RW, Stokes BT, Stratton S, Thomas SB, Thomas JR, Thomson GB, Tupa D, Zech A, and Zhang X

Abstract

We report studies of ultrahigh-energy cosmic-ray composition via analysis of depth of air shower maximum (X(max)), for air shower 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/cm2/decade for energies between 1.6 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 4x10(18) eV.

Published
2010
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2. First observation of the Greisen-Zatsepin-Kuzmin suppression.

Author

Abbasi RU, Abu-Zayyad T, Allen M, Amman JF, Archbold G, Belov K, Belz JW, Ben Zvi SY, Bergman DR, Blake SA, Brusova OA, Burt GW, Cannon C, Cao Z, Connolly BC, Deng W, Fedorova Y, Finley CB, Gray RC, Hanlon WF, Hoffman CM, Holzscheiter MH, Hughes G, Hüntemeyer P, Jones BF, Jui CC, Kim K, Kirn MA, Loh EC, Maestas MM, Manago N, Marek LJ, Martens K, Matthews JA, Matthews JN, Moore SA, O'Neill A, Painter CA, Perera L, Reil K, Riehle R, Roberts M, Rodriguez D, Sasaki N, Schnetzer SR, Scott LM, Sinnis G, Smith JD, Sokolsky P, Song C, Springer RW, Stokes BT, Thomas SB, Thomas JR, Thomson GB, Tupa D, Westerhoff S, Wiencke LR, Zhang X, and Zech A

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 cosmic rays shows a sharp suppression at an energy of 6 x 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 x 10(18) eV. We describe the experiment, data collection, and analysis and estimate the systematic uncertainties. The results are presented and the calculation of the statistical significance of our observation is described.

Published
2008
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3. Measurement of the flux of ultrahigh energy cosmic rays from monocular observations by the High Resolution Fly's Eye experiment.

Author

Abbasi RU, Abu-Zayyad T, Amann JF, Archbold G, Bellido JA, Belov K, Belz JW, Bergman DR, Cao Z, Clay RW, Cooper MD, Dai H, Dawson BR, Everett AA, Fedorova YA, Girard JH, Gray RC, Hanlon WF, Hoffman CM, Holzscheiter MH, Hüntemeyer P, Jones BF, Jui CC, Kieda DB, Kim K, Kirn MA, Loh EC, Manago N, Marek LJ, Martens K, Martin G, Matthews JA, Matthews JN, Meyer JR, Moore SA, Morrison P, Moosman AN, Mumford JR, Munro MW, Painter CA, Perera L, Reil K, Riehle R, Roberts M, Sarracino JS, Sasaki M, Schnetzer SR, Shen P, Simpson KM, Sinnis G, Smith JD, Sokolsky P, Song C, Springer RW, Stokes BT, Taylor SF, Thomas SB, Thompson TN, Thomson GB, Tupa D, Westerhoff S, Wiencke LR, VanderVeen TD, Zech A, and Zhang X

Abstract

We have measured the cosmic ray spectrum above 10(17.2) eV using the two air-fluorescence detectors of the High Resolution Fly's Eye observatory operating in monocular mode. We describe the detector, phototube, and atmospheric calibrations, as well as the analysis techniques for the two detectors. We fit the spectrum to a model consisting of galactic and extragalactic sources.

Published
2004
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