Techniques for measuring aerosol attenuation using the Central Laser Facility at the Pierre Auger Observatory

THE PIERRE AUGER OBSERVATORY (PATRICIA HANSEN PERTENECE A LA COLABORACION)

JOURNAL OF INSTRUMENTATION

IOP PUBLISHING LTD

Lugar: Londres; Año: 2013 vol. 8 p. 1 - 24

1748-0221

The Pierre Auger Observatory in Malarg¨ue, Argentina, is designed to study the propertiesof ultra-high energy cosmic rays with energies above 1018 eV. It is a hybrid facility thatemploys a Fluorescence Detector to perform nearly calorimetric measurements of Extensive AirShower energies. To obtain reliable calorimetric information from the FD, the atmospheric conditionsat the observatory need to be continuously monitored during data acquisition. In particular,light attenuation due to aerosols is an important atmospheric correction. The aerosol concentrationis highly variable, so that the aerosol attenuation needs to be evaluated hourly. We use light fromthe Central Laser Facility, located near the center of the observatory site, having an optical signaturecomparable to that of the highest energy showers detected by the FD. This paper presents twoprocedures developed to retrieve the aerosol attenuation of fluorescence light from CLF laser shots.Cross checks between the two methods demonstrate that results from both analyses are compatible,and that the uncertainties are well understood. The measurements of the aerosol attenuationprovided by the two procedures are currently used at the Pierre Auger Observatory to reconstructair shower data.