Thermal stability of gamma irradiation induced defects for different fused silica

In this work, we have studied the effects of isochronal thermal annealing up to 850 °C for seven types of silica with different impurity and OH contents, previously gamma irradiated under identical conditions up to 11.6 MGy. The results obtained suggest that both the OH content and impurities play an important role in the thermal stability of E′ defects. These defects show the lowest thermal stability in high purity KU1 silica (820 ppm OH), annealing out by 400 °C. For silicas with the lowest OH concentration, the E′ defects show the highest thermal stability.