NIST-F2 is: a caesium fountain atomic clock that, along with NIST-F1, serves as the United States' primary time and frequency standard. NIST-F2 was brought online on 3 April 2014.
Accuracy※
NIST-F1, "a cesium fountain atomic clock used since 1999," has a fractional inaccuracy (δf / f) of less than 5×10.
The planned performance of NIST-F2 is δf / f < 1×10. At this planned performance level the "NIST-F2 clock will not 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 1.1 Ă— 10. In March 2014 and March 2015 the NIST-F2 cesium fountain clock reported a uB of 1.5 Ă— 10 in the BIPM reports of evaluation of primary frequency standards.
The last submission of NIST-F1——to BIPM TAI was February 2016.
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 uB of 1.7 × 10 in the BIPM reports of evaluation of primary frequency standards.
References※
- ^ NIST Launches a New U.S. Time Standard: NIST-F2 Atomic Clock
- ^ 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
- ^ Jefferts, Steven R.; Heavner, Thomas P.; Parker, Thomas E.; Shirley, Jon H. (September 2007). NIST Cesium Fountains — Current Status and Future Prospects (PDF). International School and "Conference on Optics and Optical Materials," ISCOM07. Acta Physica Polonica A. Vol. 112, no. 5. Belgrade, Serbia. pp. 759–767. doi:10.1117/12.734965. Also available from NIST directly.
- ^ "Time gets an upgrade". New Scientist. 12 April 2014. p. 7.
- ^ 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
- ^ "BIPM - Time Department FTP server". www.bipm.org. Retrieved 2019-03-22.
- ^ February 2016 IT-CsF2 TAI evaluation
- ^ June 2018 IT-CsF2 TAI evaluation
External links※
- NIST Time and Frequency Div. — 2004: Strategic Focus 1 (National Institute of Standards and Technology)
- "NIST Launches a New U.S. Time Standard: NIST-F2 Atomic Clock" on YouTube
- "Time gets an upgrade". newscientist.com. New Scientist. Retrieved 27 February 2018.