Aerosol characterization at the Pierre Auger Observatory

THE PIERRE AUGER COLLABORATION.; S. J. SCIUTTO

Conferencia; 33rd International Cosmic Ray Conference; 2013

The Pierre Auger Observatory is a hybrid facility composed of surface and fluorescence detectors(denoted as SD and FD, respectively), where the FD system sets the energy scale in cosmic ray showerreconstruction. Atmospheric components attenuate the fluorescence light emitted by the de-excitation ofatmospheric nitrogen, previously excited by the charged particles of the shower. Amongst these components,atmospheric aerosols are the ones with the largest fluctuations, being responsible for one of the major uncertaintiesin shower reconstruction with FD data. We present a detailed characterization of aerosols. They are collected atthe Observatory and analyzed, in morphology and elemental composition, with experimental techniques used forthe first time in a cosmic ray observatory: gravimetry, PIXE and SEM/EDX. An analysis of wind trajectories usingthe program HYSPLIT is used to understand the sources and the evolution of aerosols. The aerosols are furthercharacterized by the FRAM, an optical telescope employed to perform CCD photometry of selected Landolt fields,in which we observe sets of precisely measured standard stars at various wavelengths. Using this photometricinformation we then compute the A° ngstro¨m coefficients that also characterize the size of aerosols.