The acoustic loss peak near 50 K in 5‐MHz 5th overtone AT‐cut synthetic quartz resonators has been used to determine the behavior of the Al‐Na+center under irradiation. The center was found to be stable for irradiations carried out at temperatures below 200 K. Above 200 K the Na+was found to be mobile in the radiation field and was replaced by a hydrogen to form the Al‐OH−center. The decrease in the height of the sodium acoustic loss peak following irradiation at temperatures between 200 and 250 K correlates strongly with the growth of the Al‐OH−and (Ale+)0centers over the same temperature range. Electrodiffusion has been carried out directly on plano‐convex AT‐cut resonator blanks. Using the technique Na has been swept into, as well as removed from AT‐cut resonators. Direct sweeping of AT‐cut resonator blanks should reduce the number of steps needed in the fabrication of radiation‐hardened crystals.