Monte Carlo simulations of photohadronic processes in astrophysics

A new Monte Carlo program for photohadronic interactions of relativistic nu cleons with an ambient photon radiation field is presented. The event gener ator is designed to fulfill typical astrophysical requirements, but can als o be used for radiation and background studies at high energy colliders suc h as LEP2 and HERA, as well as for simulations of photon induced air shower s. We consider the full photopion production cross section from the pion pr oduction threshold up to high energies. it includes resonance excitation an d decay, direct single pion production and diffractive and non-diffractive multiparticle production. The cross section of each individual process is c alculated by fitting experimental data, while the kinematics is determined by the underlying particle production process. We demonstrate that our mode l is capable of reproducing known accelerator data over a wide energy range . (C) 2000 Elsevier Science B.V. All rights reserved.