Observation of the Suppression of the Flux of Cosmic Rays above 4

THE PIERRE AUGER COLLABORATION (AUTOR 369 DE 395); M. TUEROS

PHYSICAL REVIEW LETTERS

The American Physical Society

Año: 2008 vol. 101 p. 611011 - 611017

0031-9007

The energy spectrum of cosmic rays above 2:5
1018 eV, derived from 20 000 events recorded at the Pierre Auger Observatory, is described. The spectral index
of the particle flux, J / E
, at energies between 4
1018 eV and 4
1019 eV is 2:69  0:02stat  0:06syst, steepening to 4:2  0:4stat  0:06syst 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.