A report on an investigation of the change in the natural frequency of quartz crystal oscillators produced by high intensity, long-wavelength x-rays
Corbly, John Bunyan
Master of Science
During World War II it was discovered that the elastic constants and hence the natural frequencies of quartz crystal oscillator plates could be changed by radiation v/ith high intensity, long-wavelength X-rays. This discovery was made possible by the development of a beryllium window X-ray tube which provided longer wavelength X-rays of much greater intensity than those from conventional Pyrex Glass window X-ray tubes. This investigation involved the radiation of commercial high frequency quartz crystals with these long-wavelength X-rays and the observation of their effects on frequency and temperature coefficient. Much of the effort of this problem was expended in the development of a suitable method and the necessary apparatus for measuring these effects. The results of this investigation show that the frequency of crystals having suitable mounts can be lowered as much as 0.08$ by the use of X-rays. No appreciable effect on the temperature coefficient for the crystals tested was noted. The amount of frequency change possible is dependent on the individual crystal. Consequently, no qualitative method of expressing the frequency change as a function of frequency or X-ray intensity is possible. The amount of frequency reduction is sufficient to make the process commercially desirable as its use will eliminate much of the tedious lapping necessary for the final frequency adjustment of close tolerance crystal oscillators. It is known that commercial use was made of this phenomena during World War II, but it is believed the details have never been published.