The Effect of Radiation on Saw Resonators

Abstract

SAW devices are known for their ability to withstand severe operating conditions. However, their data sheets generally provide very little information on their susceptibility to external factors other than temperature. In particular, no mention is made of their sensitivity to ionizing and non-ionizing radiation, even though they are being used in applications where such radiation is present. In this thesis, we report on experiments that we have conducted to measure the impact of intense gamma and neutron radiation on quartz SAW resonators. Packaged commercial 434 MHz quartz SAW resonators (RFM RP1308) were placed at the output of a Colbalt 60 source and exposed to gamma radiation of up to 50 Mrads. Additional devices were positioned in close proximity to the enriched uranium core of the McMaster University Nuclear Reactor and exposed to intense neutron radiation of 4.5 x 10^12 neutrons/cm^2s for up to 40 seconds. After waiting for a necessary cool-down period, the irradiated SAW resonators were placed in the feedback loop of a custom oscillator to measure the shift in output frequency as a function of radiation exposure. Small changes in the oscillator frequency of up to 15 ppm for the gamma radiation and of up to 10 ppm for neutron radiation were obtained in the experiments. However, no clear relationships were observed between the amount of radiation exposure and frequency shift in either case.