Radiation Induced Transient Thermal Effects in 5 MHz AT-Cut Quartz Resonators

Abstract

A bulk resonator's response to ionizing radiation is concerned with a number of factors, including: (a) Induced photoconductivity in the quartz, (b) Changes in the elastic modulus and the Q of the resonator, (c) Temperature rise in the quartz from the deposited ionizing radiation, and (d) Induced stress gradients in the crystal stemming from non-uniform temperature changes throughout the resonator structure. Heretofore the factors causing the largest radiation-induced effects have been due to crystal impurities which manifested themselves as frequency and resistance changes. In very high quality quartz which has been swept, frequency variations originating from the temperature factors mentioned above are observed. A thermal model of the quartz resonator structure and associated oven led to a transient frequency response description in good agreement with the experimental data. Short-term transient frequency excursions in very pure, swept quartz are primarily determined by thermal phenomena. Further reductions in radiation effects on quartz crystal oscillators may require thermal transient compensated cuts or modified AT resonator structures and ovens.