Study on the damaging process of silica by in-reactor luminescence

We have carried out in situ luminescence measurements of silica glasses in a fission reactor. In the in-reactor-luminescence (IRL) spectra, the 300-nm band was observed for all the samples and its intensity stayed constant during irradiation. For low-OH fused silica glass, the 400-nm IRL band was also observed and reduced rapidly with irradiation, while for high-OH fused and synthesized silica glasses, the 450-nm IRL band grew slowly. The comparison with photoluminescence (PL) and electron spin resonance (ESR) spectra showed that the decrease of the 400-nm IRL band reflects the transition of B2β center to E′ center by electron excitation by γ-rays, while the growth of the 450-nm IRL band related to defect formation from neutron irradiation. However, single crystal silica showed only a 300-nm IRL band, suggesting that the damaging processes are influenced by the local structure around defects as well as the OH content in silica.