NIST F1: Recent improvements and a resulting accuracy of δf/f=0.53x10-15

Published

September 13, 2005

Author(s)

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

Abstract

In the last several years we have made many improvements to NIST-F1 (a laser-cooled Cs fountain primary frequency standard) resulting in over a factor of 2 reduction in the uncertainty in the realization of the SI second. The two most recent accuracy evaluations of NIST-F1 had combined standard fractional uncertainties of 0.61 x 10^-15 (June 2004) and 0.53 x 10^-15 (January 2005) which were submitted to the BIPM with total fractional uncertainties (including time transfer contributions) of 0.88 x 10^-15 and 0.97 x 10^-15 respectively. Here we discuss the improvements, evaluation methods and present an updated uncertainty budget.

Citation

Metrologia

Volume

42

Pub Type

Journals

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Keywords

Cesium Standards (CES), General Time and Frequency (GEN), Time Scale (Scale), Time/The Second (SEC)

Citation

Heavner, T. , Jefferts, S. , Donley, E. , Shirley, J. and Parker, T. (2005), NIST F1: Recent improvements and a resulting accuracy of δf/f=0.53x10^-15, Metrologia, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50098 (Accessed October 10, 2025)