This proposal requests support for an Ohio State University (OSU) group to work on the Pierre Auger Observatory (PAO). The PAO is an international project aimed at the study of the highest energy cosmic rays, beyond 10^19 eV. These highest energy particles in the Universe are very rare, and the elucidation of the mystery of their origin is one of the key challenges in modern astrophysics. This mystery is further confounded by an apparent disagreement between the AGASA surface array and the HiRes air fluorescence experiments concerning the existence of a cutoff due to energy loss in interactions with the cosmic microwave background radiation, as proposed by Greisen(1966) and by Zatzepin and Kuz'min(1966).
The southern PAO site, located in western Argentina, is now the largest air shower array ever constructed, with over 450 surface detectors operating and half of the fluorescence telescopes installed. The OSU group has played a vital role in the design, integration, commissioning, and management of the surface detector electronics chain. The PI serves as the surface detector electronics task leader in the project's management structure. Members of the group have spent considerable time in the field commissioning the engineering array and pre-production detectors, and have participated in the development and debugging of much of the software used in operating the surface array. They plan to continue their activities in support of detector installation, commissioning, and operation, and their participation in analysis of the Auger data.
They have been active in engaging the public and providing opportunities for understanding of the fascinating science involved, by conducting tours of the facilities both in the U.S. and in Argentina for schoolchildren and others.
