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Phys. Rev. Lett. 81, 1163–1166 (1998)

Extension of the Cosmic-Ray Energy Spectrum beyond the Predicted Greisen-Zatsepin-Kuz'min Cutoff

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M. Takeda et al.
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Received 26 May 1998; published in the issue dated 10 August 1998

The cosmic-ray energy spectrum above 1018.5eV is reported using the updated data set of the Akeno Giant Air Shower Array from February 1990 to October 1997. The energy spectrum extends beyond 1020eV and the energy gap between the highest energy event and the others is being filled up with recently observed events. The spectral shape suggests the absence of the 2.7 K cutoff in the energy spectrum or a possible presence of a new component beyond the 2.7 K cutoff.

© 1998 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.81.1163
DOI:
10.1103/PhysRevLett.81.1163
PACS:
98.70.Sa, 96.40.De, 96.40.Pq