NEUTRON-INDUCED LUMINESCENCE OF CERAMICS

In order to investigate dynamic effects of neutron irradiation on cera mics, we have carried out in-situ luminescence measurements of Al2O3 a nd SiO2 in the nuclear reactor YAYOI at the University of Tokyo and co mpared with ion-induced luminescence measured in parallel. The observe d luminescence spectra for Al2O3 and SiO2 under the in-reactor irradia tion are very similar to those observed in the ion induced luminescenc e, 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 Si O2 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 decr eases but not monotonously, corresponding to the loss of transparency and/or coloring. Peak structure is also modified, which suggests an ad ditional production of luminescence centers by the displacement effect of neutrons.