A Partial Analysis of Drift Gas Cell Atomic in the Rubidium Frequency Standard

J.C. Camparo

Abstract: Uncorrected frequency drift in the rubidium (Rb) vapor atomic frequency standard can be a significant source or ti me error for systems based on this standard, and has thus drastically limited this standard's range of application. Not only are the origins of this drift not well understood, but its characteristics have never been fully documented. As a first step in correcting this situation we have reviewed the available experimental data concerning drift, and have arrived at a consistent set of general Rb clock drift characteristics: 1) on an individual standard the sign of the drift coefficient may be variable; 2) the magnitude and sign of the drift coefficient are typically only stable over a period of roughly three months, and 3) the general Rb clock drift coefficient is (5 + 2) x 10-12 /month. Using these characteristics we then discuss eleven possible mechanisms capable of inducing drift. It is found that only four of these mechanisms are consistent with the drift characterization: 1) a temperature-induced pressure shift mechanism, 2) a quadratic Zeeman shirt mechanism, 3) a spectrum dependent light shirt mechanism, and 4) a position shirt mechanism. It is suggested that these four mechanisms receive more theoretical and experimental attention to see if any one of them is capable or explaining all the vagaries of Rb clock frequency drift.
Published in: Proceedings of the 18th Annual Precise Time and Time Interval Systems and Applications Meeting
December 2 - 4, 1986
DuPont Plaza Hotel
Washington, DC
Pages: 565 - 588
Cite this article: Camparo, J.C., "A Partial Analysis of Drift Gas Cell Atomic in the Rubidium Frequency Standard," Proceedings of the 18th Annual Precise Time and Time Interval Systems and Applications Meeting, Washington, DC, December 1986, pp. 565-588.
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