Thermoluminescence, phosphorescence, and ac conductivity measurements have been performed at room temperature on as‐grown or Li‐, Na‐, and Cu‐ electrodiffused synthetic quartz, beta or x ray irradiated, to confirm the ionic nature of the charge carriers in the radiation‐induced conductivity (RIC). Comparison between RIC and phosphorescence time dependence has allowed us to propose a mechanism for the annealing process of the RIC.