Simulation of Ultra-High Energy Photon Propagation in the Geomagnetic Field

摘要

The identification of primary photons or specifying stringent limits on thephoton flux is of major importance for understanding the origin of ultra-highenergy (UHE) cosmic rays. We present a new Monte Carlo program allowingdetailed studies of conversion and cascading of UHE photons in the geomagneticfield. The program named PRESHOWER can be used both as an independent tool ortogether with a shower simulation code. With the stand-alone version of thecode it is possible to investigate various properties of the particle cascadeinduced by UHE photons interacting in the Earth's magnetic field beforeentering the Earth's atmosphere. Combining this program with an extensive airshower simulation code such as CORSIKA offers the possibility of investigatingsignatures of photon-initiated showers. In particular, features can be studiedthat help to discern such showers from the ones induced by hadrons. As anillustration, calculations for the conditions of the southern part of thePierre Auger Observatory are presented.