Simulation of ultra-high energy photon showers with PRESHOWER

Abstract

The new, publicly available Monte Carlo program PRESHOWER is presented. It allows detailed studies on conversion and cascading of UHE photons in the geomagnetic field. When coupled to a standard air shower simulation program, PRESHOWER enables complete simulations of UHE photon-induced showers. 1. PRESHOWER simulations The identification of primary photons or spec-ifying stringent limits on the photon flux is of major importance for understanding the origin of ultra-high energy cosmic rays (UHECR). In such a kind of studies it is necessary to simu-late thoroughly the air showers induced by UHE photons. It implies a proper treatment of pre-cascading of UHE photons in the geomagnetic field (preshower effect) [1,2]. This effect has a significant impact on observable properties of the subsequent atmospheric showers [3–6]. An ac