Observation of a Very Energetic Cosmic Ray Well Beyond the Predicted 2.7 K Cutoff in the Primary Energy Spectrum

N. Hayashida, K. Honda, M. Honda, S. Imaizumi, N. Inoue, K. Kadota, F. Kakimoto, K. Kamata, S. Kawaguchi, N. Kawasumi, Y. Matsubara, K. Murakami, M. Nagano, H. Ohoka, M. Takeda, M. Teshima, I. Tsushima, S. Yoshida, and H. Yoshii
Phys. Rev. Lett. 73, 3491 – Published 26 December 1994
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Abstract

A very energetic cosmic ray of energy about (1.7-2.6) × 1020 eV was observed by the Akeno Giant Air Shower Array on 3 December 1993 from the direction of galactic longitude l=131° and galactic latitude b=41° within an error circle of 1.0° radius. If this cosmic ray were a proton; its origin could be extragalactic. However, the distance of the source cannot be much more than a few times 10 Mpc due to the energy loss during its travel from interactions with universal background radiation.

  • Received 12 August 1994

DOI:https://doi.org/10.1103/PhysRevLett.73.3491

©1994 American Physical Society

Authors & Affiliations

N. Hayashida1, K. Honda3, M. Honda1, S. Imaizumi4, N. Inoue4, K. Kadota2, F. Kakimoto2, K. Kamata5, S. Kawaguchi6, N. Kawasumi3, Y. Matsubara7, K. Murakami8, M. Nagano1, H. Ohoka1, M. Takeda2, M. Teshima1, I. Tsushima3, S. Yoshida2,*, and H. Yoshii9

  • 1Institute for Cosmic Ray Research, University of Tokyo, Tokyo 188 Japan
  • 2Department of Physics, Tokyo Institute of Technology, Tokyo 152, Japan
  • 3Faculty of Education, Yamanashi University, Kofu 400, Japan
  • 4Department of Physics, Saitama University, Urawa 338, Japan
  • 5Nishina Memorial Foundation, Tokyo 188, Japan
  • 6Faculty of General Education, Hirosaki University, Hirosaki 036, Japan
  • 7Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-01, Japan
  • 8Nagoya University of Foreign Studies, Aichi 470-01, Japan
  • 9Faculty of General Education, Ehime University, Matsuyama 790, Japan

  • *Present address: High Energy Astrophysics Institute, Department of Physics, University of Utah, Salt Lake City, UT 84112.

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Vol. 73, Iss. 26 — 26 December 1994

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