Transient changes in quartz resonators following exposure to pulse ionization

Abstract

Abstract This paper is a review of the transient effect of pulse ionization on the resonant frequency and Q of quartz resonators. A number of different samples of both natural and synthetic quartz crystals have been used. Fifth-overtone 5, 32, and 125 MHz thickness shear (AT-cut) crystal units were fabricated and studied using several different oscillator circuits, one of which was designed such that the resistance Rs (αQ −1) of the crystal unit at series resonance as well as frequency could be measured after pulse exposure. With the exception of one purposely altered crystal, all the resonators exhibited a negative-transient frequency offset after irradiation which thereafter anneals as a function of t −1/2 over nearly four decades of time. The pulse irradiation effect on Q −1 is most striking at 5 MHz in natural quartz units, which suffer a thirty-fold increase in acoustic absorption after exposure to 104 rad. The transient increase in the acoustic absorption in natural quartz anneals within 10 seconds to a value somewhat larger than the preirradiation absorption. Theoretical models are described which account for these observations.