Effect of radiation on quartz glass

Many studies have been reported on the relations of the water content with the radiation resistance of wet silica (containing ∼ 1,000 ppm water), but there are large variations among the results of these studies. The present report describes some observations of the effect of previous heat treatment on the behavior of irradiated wet silica. Wet silica samples are irradiated with X-ray and absorption spectra are observed. Two peaks appear at about 4.6eV (N) and 5.7eV (E'), respectively. They increase with increasing irradiation time. The coloring sensitivity increases if heat treatment (1,000degC) is carried out before irradiation. The rate of increase for the N peak is different from that for the E' peak. A wet silica sample subjected to repeated heat treatment-irradiation cycles indicates that the coloring sensitivity increases continuously for about 10 hours and then levels off. Compared with this, dry silica does not show such variations with thermal history, and is much higher in coloring sensitivity. Photoluminescence spectra and photoluminescence excitation spectra of X-ray irradiated synthetic quartz glass are also observed and discussed. (N.K.)