Improving photon-hadron discrimination based on cosmic ray surface detector data

Semi-analytical and numerical studies are performed in order to optimize Sb for the discrimination of photons from a proton background in the energy range from 1018.5 to 1019.6 eV. Although not shown explicitly, the same analysis has been performed for Fe nuclei and the corresponding results are discussed when appropriate. The effects of different array geometries and the underestimation of the muon component in the shower simulations are analyzed, as well as the Sb dependence on primary energy and zenith angle.