NEUTRON-INDUCED LUMINESCENCE OF CERAMICS

In order to investigate dynamic effects of neutron irradiation on ceramics, we have carried out in-situ luminescence measurements of Al2O3 and SiO2 in the nuclear reactor YAYOI at the University of Tokyo and compared with ion-induced luminescence measured in parallel. The observed luminescence spectra for Al2O3 and SiO2 under the in-reactor irradiation are very similar to those observed in the ion induced luminescence, indicating that the luminescence originates from the oxygen vacancy related color centers of F and F+ for Al2O3 or E', E'' and B-2 for SiO2 due to an electron excitation by the neutron and gamma irradiation. The luminescence spectra change with the irradiation time or fluence. The total intensity first increases with the dose but afterwards decreases but not monotonously, corresponding to the loss of transparency and/or coloring. Peak structure is also modified, which suggests an additional production of luminescence centers by the displacement effect of neutrons.