Observation of the Suppression of the Flux of Cosmic Rays above 4×1019eV
Abstract
The energy spectrum of cosmic rays above 2.5×1018eV, derived from 20 000 events recorded at the Pierre Auger Observatory, is described. The spectral index γ of the particle flux, J∝E-γ, at energies between 4×1018eV and 4×1019eV 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.
- Publication:
-
Physical Review Letters
- Pub Date:
- August 2008
- DOI:
- 10.1103/PhysRevLett.101.061101
- arXiv:
- arXiv:0806.4302
- Bibcode:
- 2008PhRvL.101f1101A
- Keywords:
-
- 98.70.Sa;
- 95.85.Ry;
- 96.50.sb;
- 96.50.sd;
- Cosmic rays;
- Neutrino muon pion and other elementary particles;
- cosmic rays;
- Composition energy spectra and interactions;
- Extensive air showers;
- Astrophysics
- E-Print:
- 7 pages, 2 figues, accepted for publication in Physics Review Letters