Growth of paramagnetic defects by gamma rays irradiation in oxygen-deficient silica

We report an electron paramagnetic resonance (EPR) study of gamma rays irradiation effects on an oxygen-deficient silica obtained from fused quartz. We have found that three types of E′ centers, Eα′, Eγ′ and Eδ′, and a paramagnetic defect in a spin triplet state (S = 1) are induced. The EPR signals dependence on the microwave power have been investigated. The concentrations of these centers as a function of gamma ray irradiation show that for high dose a limit value is reached suggesting a generation process from precursors.