Low and High Dose Photon Irradiation of Quartz Crystal Resonators

J.J. Suter and R.H. Maurer

Abstract:	The Johns Hopkins University Applied Physics Laboratory has been I involved in studies concerning the radiation susceptibility of quartz 1 crystal resonators for several years. In this paper we will report on results of a study of the sensitivity of AT cut quartz crystal resonators to low [4.0 Rads (si)] and high [1000 Rads (si)] accumulated doses which were generated by 1.25 MeV photons from two Cobalt 60 sources. In previous experiments, the same AT quartz crystal resonators were subjected to low level [4.0 Rads (Si)] photon irradiation and higher levels [12.0 Rads (si)] of proton radiation from the Harvard University Cyclotron (Ref. 1). It was concluded from those tests that the frequency susceptibility of AT quartz crystal resonators to proton radiation is approximately equal in magnitude to the frequency shifts induced in the resonator by photon irradiation from Cobalt 60 sources. These experiments also showed, as was previously reported, that the frequency susceptibility of AT quartz crystal resonators to low level radiation [4.0 Rads (Si)] can not be extrapolated from high level [> 10 kRads (sill radiation tests (Refs, 2, 3, 4 and 5). This paper will discuss the results of radiation tests performed on AT quartz crystal I resonators in which their frequency susceptibility as a function of accumulated photon radiation over an interval from 0 to 1000 Rads (Si) was measured. It is shown that the frequency shift (?f/f) per rad is a function of total accumulated dose and that this slope (? f/f/ per rad) is the largest for low [4.0 Rads (Si)] accumulated doses. Furthermore, the paper will report on the recovery of AT quartz crystal resonators after radiation exposure and the magnitude of the oscillator's Allan Variances before, during and after the radiation events.
Published in:	Proceedings of the 17th Annual Precise Time and Time Interval Systems and Applications Meeting December 3 - 5, 1985 DuPont Plaza Hotel Washington, DC
Pages:	393 - 404
Cite this article:	Suter, J.J., Maurer, R.H., "Low and High Dose Photon Irradiation of Quartz Crystal Resonators," Proceedings of the 17th Annual Precise Time and Time Interval Systems and Applications Meeting, Washington, DC, December 1985, pp. 393-404.
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