Production of Simulated Extensive Air Showers for the Pierre Auger Collaboration Using Grid Technology

The Pierre Auger Observatory detects the secondary particles generated when an Ultra High Energy Cosmic Ray (UHECR) interacts at the top of the atmosphere. Our collaboration studies the energy spectrum, chemical composition and origin of those extremely high energetic objects. The secondary particles multiply within the atmosphere creating an Extensive Air Shower (EAS). The number of particles involved in an EAS at these energies (10¹⁶- 10²¹ eV) is of the order of billions and the generation of a single simulated EAS requires many hours of computing time with current processors. In addition, the storage space consumed by the output of one simulated EAS is, in average, of the order of hundreds of MB. Therefore we have to make use of Grid resources to be able to generate sufficient quantities of showers for our physics studies in reasonable time periods. We have developed a set of highly automated scripts written in common software scripting languages in order to deal with the high number of jobs which we have to submit regularly to the Grid. In spite of the low number of sites supporting our Virtual Organization (VO) we have reached the top spot on CPU consumption among non LHC (Large Hadron Collider) VOs within EGI (European Grid Infrastructure).