Cecile Roucelle
Lawrence Berkeley National Laboratory
Abstract:
The Pierre Auger Observatory aims at determining the nature and origin of the ultra-high energy cosmic rays (E > 10^18 eV). The Auger hybrid detector combines fluorescent observations of longitudinal profiles of extensive air showers initiated in the atmosphere by these ultra high energetic particles, with measures of the shower front at the ground level by its large array of Cherenkov water tanks. The South Auger site located in Argentina is now close to its completion, with more than 1000 out of 1600 surface detectors, and 3 out of 4 fluorescent telescopes in operation. The Pierre Auger observatory has been collecting data since 2004 with a growing detector and has already been able to produce its very first results concerning the energy spectrum and the eventual presence of anisotropies. It also can give severe constraints on several non-astrophysics scenarii invoqued for the production of UHECR above 1020 eV as seen by AGASA. These results will be discussed here.