The transportable cesium fountain clock NIM5: its construction and performance

Abstract

The second laser cooling cesium fountain clock NIM5 at the National Institute of Metrology (NIM) China adopts the (1,1,1) direct optical molasses ( OM) configuration. NIM5 has been running with a stability of 3×10^-15/d and an operation ratio of 99% since 2007. Preliminary evaluations of NIM5 in 2008 showed a typical combined uncertainty of 3×10^-15. The NIM5 clock is operating in parallel with NIM’s first fountain clock NIM4. NIM4 and NIM5 are used to steer the frequency of the calculated NIM atomic time TA-c(NIM) and the first set of results are promising. We are now at the stage of comparing the frequency of NIM5 with UTC to support the independent frequency shift evaluations of NIM5 and contribute to the international atomic time in the near future.

Keywords

metrology / time and frequency standard / fountain clock

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2014 Higher Education Press and Springer-Verlag Berlin Heidelberg