Observation of the suppression of the flux of cosmic rays above 4x10(19) eV

Abstract

The energy spectrum of cosmic rays above 2.5 x 10(18) eV, derived from 20 000 events recorded at the Pierre Auger Observatory, is described. The spectral index gamma of the particle flux, J proportional to E-gamma, at energies between 4 x 10(18) eV and 4 x 10(19) eV is 2.69 +/- 0.02(stat) +/- 0.06(syst), steepening to 4.2 +/- 0.4(stat) +/- 0: 06 (syst) at higher energies. The hypothesis of a single power law is rejected with a significance greater than 6 standard deviations. The data are consistent with the prediction by Greisen and by Zatsepin and Kuz'min.

Description
Keywords
UPPER LIMIT, ENERGY, AIR, SHOWERS, ARRAY, Physics, Multidisciplinary, Physics
Citation
Abraham, J., et al. (2008): Observation of the Suppression of the Flux of Cosmic Rays above 4 × 1019 eV. Physical Review Letters, 101(6). DOI: http://dx.doi.org/10.1103/PhysRevLett.101.061101