Simulation of induced radioactivity in collimating materials under cosmic proton irradiation

γ-ray spectra from lead and tungsten targets irradiated by cosmic protons, corresponding to near-Earth orbits, are calculated using a Monte Carlo method. The influence of the South-Atlantic anomaly is taken into account. Prompt radiation (in the interval of 10-6 to 10-15 s) and γ-radiation from induced activity have been studied depending on exposure time (in the interval from several days up to a year). The induced γ-activity is found to be of similar magnitude as the background radiation, however, in some cases it can even be somewhat higher than the background. (orig.)