Spectra of radioactivity induced in caesium iodide scintillator crystals by 155 MeV protons

Previous work has shown the importance of induced radioactivity as a source of background counts in X- and -ray astronomy experiments which use scintillation detectors. Comprehensive data on the decay spectra observed in Caesium Iodide crystals following irradiation by 155 MeV protons has been obtained by the Imperial College group and is presented here. The spectra cover the energy loss range from 20 keV to 3.4 MeV and were collected at times after irradiation ranging from 1 min until 200 d. A sufficient selection of spectra is given to enable calculations to be made of the time variations in radioactivity which would be observed in similar space-borne detectors subjected to irradiation by inner belt and cosmic ray protons. Examples of such calculations are given.