aInstitute of Nuclear Physics PAN, ul. Radzikowskiego 152, 31-342 Kraków, Poland
bForschungszentrum Karlsruhe, Institut für Kernphysik, 76021 Karlsruhe, Germany
Abstract:
The light intensity distribution in a shower image and its implications to the primary energy reconstructed by the fluorescence technique are studied. Based on detailed CORSIKA energy deposit simulations, a universal analytical formula is derived for the lateral distribution of light in the shower image and a correction factor is obtained to account for the fraction of shower light falling into outlying pixels in the detector. The expected light profiles and the corresponding correction of the primary shower energy are illustrated for several typical event geometries. This correction of the shower energy can exceed 10%, depending on shower geometry.