Improvements in NIST-F1 and a Resulting Accuracy of δf/f = 0.61 × 10-15

Published

August 23, 2004

Author(s)

Thomas P. Heavner, Steven R. Jefferts, Elizabeth A. Donley, Jon H. Shirley, Thomas E. Parker

Abstract

Over the last several years we have made many improvements to NIST-F1 (a laser-cooled cesium fountain primary frequency standard) resulting in a reduction in the uncertainty by nearly a factor of 2 in the realization of the SI second at NIST. We recently submitted an evaluation with a combined standard fractional uncertainty of 0.61 × 10^-15 to the BIPM (Bureau International des Poids et Mesures). The total fractional uncertainty of the evaluation (including dead time and time transfer contributions) was 0.88 × 10^-15. This is the smallest uncertainty in a frequency standard yet submitted to the BIPM.

Proceedings Title

Proc. IEEE Intl. Ultrasonics, Ferroelectrics, and Frequency Control Anniversary Joint Conf.

Conference Dates

August 24-27, 2004

Conference Location

Montreal, CA

Conference Title

IEEE Intl. Ultrasonics, Ferroelectrics, and Frequency Control Conf.

Pub Type

Conferences

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Keywords

ces, gen, time

Citation

Heavner, T. , Jefferts, S. , Donley, E. , Shirley, J. and Parker, T. (2004), Improvements in NIST-F1 and a Resulting Accuracy of δf/f = 0.61 × 10^-15, Proc. IEEE Intl. Ultrasonics, Ferroelectrics, and Frequency Control Anniversary Joint Conf., Montreal, CA, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50084 (Accessed October 28, 2025)