Permanent Radiation Effects in Swept and Unswept Optical Grade Synthetic Quartz at Resonators

Permanent changes in the frequency versus temperature characteristics of unswept and swept optical grade synthetic quartz AT resonators which are caused by fast neutron and Co60 irradiations have been investigated. Neutron damage shifts the frequency versus temperature characteristics of the unswept resonators upwards in frequency across the entire zero to + 120°C temperature range at a rate of 0.56 × 10-15 ppm per N/cm2, which is the smallest value yet reported in the literature. The observed erratic results for swept resonators were attributed to effects of ionizing radiation accompanying the neutron fluence and led to the Co60> investigation. The unswept optical grade quartz was found to provide AT resonators which are more resistant to ionizing radiation than any other unswept material yet investigated in the literature. Appreciable amounts of acoustically active defects attributed to Na inpurities which were apparently gaded during sweeping were indicated by the Co results for the swept devices and made the swept devices useless as radiation resistant resonators.