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A constant from a mass, a mass from a constant



Jon R. Pratt, Stephan Schlamminger, David B. Newell, Leon S. Chao, Zeina J. Kubarych, Patrick J. Abbott, Yusi A. Cao, Frank C. Seifert, Darine El Haddad


NIST recently used a watt balance instrument known as NIST-3 to measure the Planck constant in terms of IPK with a relative uncertainty of approximately 45 parts in 10e9. Along the way to this new NIST value of h, the instrument was also employed to perform the reciprocal experiment: h was “fixed” and the unknown mass of a stainless steel mass standard was “calibrated” with reference only to standards of length, time (frequency), and electrical quantities, all derivable from fixed fundamental constants. This paper reviews the basic principles of a watt balance experiment and shares the results of a trial dissemination of mass directly from an instrument, rather than from an artifact.
Proceedings Title
ASPE Annual Meeting Proceedings
Conference Dates
November 9-15, 2014
Conference Location
Boston, MA
Conference Title
29th Annual Meeting of the American Society of Precision Engineering


watt balance, kilogram, SI, quantum electrical standards


Pratt, J. , Schlamminger, S. , Newell, D. , Chao, L. , Kubarych, Z. , Abbott, P. , Cao, Y. , Seifert, F. and El, D. (2014), A constant from a mass, a mass from a constant, ASPE Annual Meeting Proceedings, Boston, MA, [online], (Accessed May 25, 2024)


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Created November 9, 2014, Updated November 29, 2019