Phys. Rev. D
75,
062003
(2007)
[17 pages]
Observation of the anisotropy of 10 TeV primary cosmic ray nuclei flux with the Super-Kamiokande-I detector
G. Guillian et al. Super-Kamiokande Collaboration
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G. Guillian10,*, J. Hosaka1, K. Ishihara1, J. Kameda1, Y. Koshio1, A. Minamino1, C. Mitsuda1, M. Miura1, S. Moriyama1, M. Nakahata1, T. Namba1, Y. Obayashi1, H. Ogawa1, M. Shiozawa1, Y. Suzuki1, A. Takeda1, Y. Takeuchi1, S. Yamada1, I. Higuchi2, M. Ishitsuka2, T. Kajita2, K. Kaneyuki2, G. Mitsuka2, S. Nakayama2, H. Nishino2, A. Okada2, K. Okumura2, C. Saji2, Y. Takenaga2, S. Desai3,†, E. Kearns3, J. L. Stone3, L. R. Sulak3, W. Wang3, M. Goldhaber4, D. Casper5, W. Gajewski5, J. Griskevich5, W. R. Kropp5, D. W. Liu5, S. Mine5, M. B. Smy5, H. W. Sobel5, M. R. Vagins5, K. S. Ganezer6, J. Hill6, W. E. Keig6, K. Scholberg7, C. W. Walter7, R. W. Ellsworth8, S. Tasaka9, A. Kibayashi10, J. G. Learned10, S. Matsuno10, M. D. Messier11, Y. Hayato12, A. K. Ichikawa12, T. Ishida12, T. Ishii12, T. Iwashita12, T. Kobayashi12, T. Nakadaira12, K. Nakamura12, K. Nitta12, Y. Oyama12, Y. Totsuka12, A. T. Suzuki13, M. Hasegawa14, I. Kato14, H. Maesaka14, T. Nakaya14, K. Nishikawa14, H. Sato14, S. Yamamoto14, M. Yokoyama14, T. J. Haines15, S. Dazeley16, S. Hatakeyama16, R. Svoboda16, E. Blaufuss17, J. A. Goodman17, G. W. Sullivan17, D. Turcan17, A. Habig18, Y. Fukuda19, Y. Itow20, M. Sakuda21, M. Yoshida22, S. B. Kim23, J. Yoo23, H. Okazawa25, T. Ishizuka26, C. K. Jung27, T. Kato27, K. Kobayashi27, M. Malek27, C. Mauger27, C. McGrew27, E. Sharkey27, C. Yanagisawa27, Y. Gando28, T. Hasegawa28, K. Inoue28, J. Shirai28, A. Suzuki28, K. Nishijima29, H. Ishino30, Y. Watanabe30, M. Koshiba31, D. Kielczewska5,32, H. G. Berns33, R. Gran18,33, K. K. Shiraishi33, A. L. Stachyra33, K. Washburn33, R. J. Wilkes33, and K. Munakata24 (Super-Kamiokande Collaboration)
1Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Hida, Gifu, 506-1205, Japan
2Research Center for Cosmic Neutrinos, Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan
3Department of Physics, Boston University, Boston, Massachusetts 02215, USA
4Physics Department, Brookhaven National Laboratory, Upton, New York 11973, USA
5Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-4575, USA
6Department of Physics, California State University, Dominguez Hills, Carson, California 90747, USA
7Department of Physics, Duke University, Durham, North Carolina 27708, USA
8Department of Physics, George Mason University, Fairfax, Virginia 22030, USA
9Department of Physics, Gifu University, Gifu, Gifu 501-1193, Japan
10Department of Physics and Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA
11Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
12High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
13Department of Physics, Kobe University, Kobe, Hyogo 657-8501, Japan
14Faculty of Science, Kyoto University, Kyoto 606-8502, Japan
15Physics Division, P-23, Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
16Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA
17Department of Physics, University of Maryland, College Park, Maryland 20742, USA
18Department of Physics, University of Minnesota Duluth, Minnesota 55812-2496, USA
19Department of Physics, Miyagi University of Education, Sendai, Miyagi 980-0845, Japan
20Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
21Okayama University, Okayama 700-8530, Japan
22Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
23Department of Physics, Seoul National University, Seoul 151-742, Korea
24Shinshu University, Matsumoto 390-8621, Japan
25International and Cultural Studies, Shizuoka Seika College, Yaizu, Shizuoka 425-8611, Japan
26Department of Systems Engineering, Shizuoka University, Hamamatsu, Shizuoka 432-8561, Japan
27Department of Physics and Astronomy, State University of New York, Stony Brook, New York 11794-3800, USA
28Research Center for Neutrino Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
29Department of Physics, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan
30Department of Physics, Tokyo Institute for Technology, Meguro, Tokyo 152-8551, Japan
31The University of Tokyo, Tokyo 113-0033, Japan
32Institute of Experimental Physics, Warsaw University, 00-681 Warsaw, Poland
33Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
Received 23 August 2005; published 23 March 2007
The relative sidereal variation in the arrival direction of primary cosmic ray nuclei of median energy 10 TeV was measured using downward, through-going muons detected with the Super-Kamiokande-I detector. The projection of the anisotropy map onto the right ascension axis has a first harmonic amplitude of (6.64±0.98 stat±0.55 syst)×10-4 and a phase at maximum at (33.2°±8.2° stat±5.1° syst) right ascension. A sky map in equatorial coordinates indicates an excess region in the constellation of Taurus and a deficit region toward Virgo. The excess region is centered at (αT,δT)=(75°±7°,-5°±9°) with a half-opening angle χT=(39±7)°; the excess flux is (0.104±0.020)% above the isotropic expectation. The corresponding parameters for the deficit region are (αV,δV)=(205°±7°,5°±10°), χV=(54±7)°, and (-0.094±0.014)%. The data do not allow us to rule out a pure dipole form for the anisotropy (allowed at 13% confidence level); they are better described by the excess and deficit cones described above. We explored the implications under the assumption that the true anisotropy is not distorted too much by the analysis filter so that it is well-described by the observed excess and deficit cones.
© 2007 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevD.75.062003
DOI:
10.1103/PhysRevD.75.062003
PACS:
95.85.Ry, 96.50.Bh, 98.35.Hj, 98.35.Pr
*Present address: Physics Department, Queen’s University, Kingston, Ontario, Canada K7L 3N6 †Present address: Center for Gravitational Wave Physics, PA State University, University Park, PA 16802 USA
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