In situ luminescence and optical absorption measurements of silica in reactor core

In situ optical measurements of silica glasses under in-reactor and γ-ray irradiation have been carried out. Two types of emission bands attributed to B2α and B2β oxygen deficient centers were clearly distinguished from their different behavior with irradiation time. The B2α center was created mainly by the atomic displacement effect due to neutron irradiation. On the other hand, the B2β center, which has two origins, intrinsic and newly formed (from its precursor states), was transformed to E′ centers through the electronic excitation effect of γ-ray irradiation. The present in situ experiments also showed the possibility that the B2β center can also be created by the displacement process caused by Compton electrons under γ-ray irradiation.