Measuring Atmospheric Aerosol Attenuation at the Pierre Auger Observatory

THE PIERRE AUGER COLLABORATION (AUTOR 434 DE 474); M. TUEROS

Rio de Janeiro

Conferencia; 33rd International Cosmic Ray Conference (ICRC 2013); 2013

International Union of Pure and Applied Physics (IUPAP)

Abstract: The Fluorescence Detector (FD) of the Pierre Auger Observatory provides a nearly calorimetric measurement of the primary particle energy, since the fluorescence light produced is proportional to the energy dissipated by an Extensive Air Shower (EAS) in the atmosphere. For this reason, the FD is used to calibrate the absolute energy scale of the Surface Detector (SD) by means of hybrid events. Of the major correction terms applied to the FD, atmospheric transmission through aerosols has the largest time variation. The correspondingcorrection to an EAS energy can range from a few percent to more than 40%, depending on the aerosol attenuation conditions, the distance of the shower, and the energy. We report on 9 years of hourly aerosol optical depth profile measurements, including revised statistical and systematic error estimates, that are propagated through EAS reconstruction. To accumulate these hourly aerosol optical depth profiles, the Central Laser Facility (CLF) and the eXtreme Laser Facility (XLF) of the Auger Observatory generated more than 4 million laser tracks that were recorded by the FD telescopes. Finally we describe major upgrades in progress to the CLF and to the elastic LIDAR stations at the Pierre Auger Observatory. The main features of these complementary upgrades arediscussed together with the expected results of their applications.