Year: 2005
Type: article
Abstract: In the last several years we have made many improvements to NIST-F1 (a laser-cooled Cs fountain primary frequency standard at the National Institute of Standards and Technology (NIST) in Boulder, Colorado) resulting in a reduction by over a factor of 2 in the uncertainty of the realization of the SI second. The two most recent accuracy evaluations of NIST-F1 had combined standard fractional uncertainties of 0.61 × 10 −15 (June 2004) and 0.53 × 10 −15 (January 2005), which were submitted to the Bureau International des Poids et Mesures with total fractional uncertainties (including time-transfer contributions) of, respectively, 0.88 × 10 −15 and 0.97 × 10 −15 . Here we discuss the improvements and evaluation methods and present an updated uncertainty budget.
Source: Metrologia
Institution: National Institute of Standards and Technology
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2132308827