Influences of Thermal Annealing Temperatures on Irradiation Induced $E^{\prime }$ Centers in Silica Glass

Influences of pre-irradiation and thermal annealing on E ^´ defect concentration are studied by measuring E ^´ centers and optical absorptions using ESR and spectrophotometer, respectively. The results show that the E ^´ defect concentration decreases significantly when silica glass is pre-irradiated by gamma rays and a subsequent thermal annealing. The effect of thermal annealing on the E ^´ concentration has also been investigated for the temperature from 300degC to 1300degC. It is found from the ESR spectrum that the anti-irradiated property of the silica glass can be improved when the thermal annealing temperature is larger than 700degC. These results have been proved by optical absorption spectra.