NIST-F2 is a caesium fountain atomic clock that, along with NIST-F1, serves as the United States' primary time and frequency standard.NIST Launches a New U.S. Time Standard: NIST-F2 Atomic Clock NIST-F2 was brought online on 3 April 2014.First Accuracy Evaluation of NIST-F2, T. P. Heavner, S. R. Jefferts, J. H. Shirley, T. E. Parker, E. A. Donley, N. Ashby, S. Barlow, F. Levi, and G. Costanzo, May 2014
Accuracy
NIST-F1, a cesium fountain atomic clock used since 1999, has a fractional inaccuracy (δf / f) of less than .
Anticipated accuracy The planned performance of NIST-F2 is δf / f < . Also available from NIST directly. At this planned performance level the NIST-F2 clock will not gain or lose a second in at least 300 million years.
Evaluated accuracy The evaluated accuracy (uB) reports of various primary frequency and time standards are published online by the International Bureau of Weights and Measures (BIPM). The first in-house accuracy evaluation of NIST-F2 reported a uB of .Heavner T P, Donley E A, Levi F, Costanzo G, Parker TE, Shirley J H, Ashby N, Barlow S and Jefferts SR, “First accuracy evaluation of NIST-F2,” 2014 Metrologia 51, 174–182, May 2014 In March 2014 and March 2015 the NIST-F2 cesium fountain clock reported a uB of in the BIPM reports of evaluation of primary frequency standards.
The last submission of NIST-F1 to BIPM TAI was February 2016.
Replicas At the request of the Italian standards organization, NIST manufactured many duplicate components for a second version of NIST-F2, known as IT-CsF2 to be operated by the Istituto Nazionale di Ricerca Metrologica (INRiM), NIST's counterpart in Turin, Italy. As of February 2016 the IT-CsF2 cesium fountain clock started reporting a uB of in the BIPM reports of evaluation of primary frequency standards.February 2016 IT-CsF2 TAI evaluationJune 2018 IT-CsF2 TAI evaluation
References
External links NIST Time and Frequency Div. — 2004: Strategic Focus 1 (National Institute of Standards and Technology)