Observation of the suppression of the flux of cosmic rays above 4x10^19eV.

J. ABRAHAM, M.T.DOVA ET AL

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Año: 2008 vol. 101 p. 1 - 7

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 flux, J / E−, at energies between 4 × 1018 eV and 4 × 1019 eV is 2.69±0.02 (stat) ±0.06 (syst), steepening to 4.2±0.4 (stat) ±0.06 (syst) at higher energies, consistent with the prediction by Greisen and by Zatsepin and Kuz’min.