Abstract
Performance of a 3.8 × 3.8 cm BGO detector used as a gamma ray spectrometer was tested after thermal neutron bombardment. The drift of photopeak channel as well as change of absolute counting efficiency and photopeak energy resolution became severe as the BGO detector was bombarded with thermal neutrons to 10 13 n th /cm 2 . Irradiation with thermal neutrons beyond 10 15 n th /cm 2 disabled the BGO detector as a gamma ray spectrometer due to the intense interference from internal radioactivity induced by neutron reactions. © 1991.