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12 September 2007 NIST cesium fountains: current status and future prospects
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We review the current status of the U.S. Primary Frequency Standard, NIST-F1. NIST-F1 is a laser-cooled cesium fountain based frequency standard with an inaccuracy of less than δ f / f ≤ 5x10-16 limited mainly by the radiation field in the room-temperature fountain (blackbody shift). NIST-F1 is one of the best cesium fountains currently contributing to international atomic time, but has reached a point that it is impractical to improve its accuracy substantially. Therefore we are building a new fountain, imaginatively named NIST-F2, with a cryogenic (77 K) Ramsey interrogation zone that lowers the blackbody shift by several orders of magnitude. NIST-F2 is currently undergoing final assembly, and we will discuss our planned (hoped for) performance, which includes frequency inaccuracy of δ f / f < 1x10-16
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
S. R. Jefferts, T. P. Heavner, T. E. Parker, and J. H. Shirley "NIST cesium fountains: current status and future prospects", Proc. SPIE 6673, Time and Frequency Metrology, 667309 (12 September 2007);


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