MEASUREMENT OF THE ANISOTROPY OF COSMIC-RAY ARRIVAL DIRECTIONS WITH ICECUBE
- Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)
- Department of Subatomic and Radiation Physics, University of Gent, B-9000 Gent (Belgium)
- Department of Physics, University of Wisconsin, River Falls, WI 54022 (United States)
- Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch (New Zealand)
- Department of Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom)
- Department of Physics, University of Wuppertal, D-42119 Wuppertal (Germany)
- Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)
- Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States)
- Department of Physics, University of California, Berkeley, CA 94720 (United States)
- DESY, D-15735 Zeuthen (Germany)
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)
- Department of Physics and Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210 (United States)
- Science Faculty CP230, Universite Libre de Bruxelles, B-1050 Brussels (Belgium)
We report the first observation of an anisotropy in the arrival direction of cosmic rays with energies in the multi-TeV region in the Southern sky using data from the IceCube detector. Between 2007 June and 2008 March, the partially deployed IceCube detector was operated in a configuration with 1320 digital optical sensors distributed over 22 strings at depths between 1450 and 2450 m inside the Antarctic ice. IceCube is a neutrino detector, but the data are dominated by a large background of cosmic-ray muons. Therefore, the background data are suitable for high-statistics studies of cosmic rays in the southern sky. The data include 4.3 billion muons produced by downward-going cosmic-ray interactions in the atmosphere; these events were reconstructed with a median angular resolution of 3{sup 0} and a median energy of {approx}20 TeV. Their arrival direction distribution exhibits an anisotropy in right ascension with a first-harmonic amplitude of (6.4 {+-} 0.2 stat. {+-} 0.8 syst.) x 10{sup -4}.
- OSTI ID:
- 21450991
- Journal Information:
- Astrophysical Journal Letters, Vol. 718, Issue 2; Other Information: DOI: 10.1088/2041-8205/718/2/L194; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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