3 April 2008

Speaker: James Cronin (Kavli Institute for Cosmological Physics, Enrico Fermi Institute)

Title: Sackler Lecture:
Study of the Highest Energy Cosmic Rays with the Pierre Auger Observatory

Abstract: A collaboration of 16 countries has nearly completed in Argentina the Pierre Auger Observatory for the study of cosmic rays with energies greater than 10¹⁹ eV. The observatory consists of a surface array of 1600 particle detectors covering 3000 km². The surface array is overlooked by 24 telescopes which observe shower particles by the fluorescence produced in the atmosphere. Good data has been collected since Jan 2004 while the size of the array has grown from 250 surface detectors to its nearly complete state today with 1500 surface detectors. The detector will be described and data on the high energy spectrum and the arrival directions will be reported. A strong anisotropy has been observed for the very highest energy cosmic rays.