Sanchez, C A*; Wood, B M*; Inglis, D*; Robinson, I A (2013) Elimination of mass exchange errors in the NRC watt balance. IEEE Trans. Instrum. Meas., 62 (6). pp. 1506-1511.

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Abstract

We report on the evaluation, correction and subsequent elimination of the mass exchange errors in the NRC watt balance. Two effects arising from mass exchanges during the weighing phase initially produced significant systematic errors in measurements of the Planck constant (h). These effects were estimated and corresponding corrections were applied to measurements of h made at NRC between August and September of 2011 An effect due to tilting of the beam required an estimated correction of (0.238 ± 0.018) uJs/(J s) and an effect due to tilting of the flat, which supports the beam, required an estimated correction of (-0.636 ± 0.056) uJ s/(J s). After the initial measurements were completed, we made several modifications to the balance that achieved a reduction of the two errors to negligible levels. A second set of measurements, made with the modified apparatus in May and June of 2012, shows very good agreement with the first measurements.

Item Type:	Article
Keywords:	Beam balance, fundamental constants, electronic kilogram, Planck's constant, watt balance
Subjects:	Engineering Measurements Engineering Measurements > Mass, Force, Pressure
Identification number/DOI:	10.1109/TIM.2012.2225957
Last Modified:	02 Feb 2018 13:14
URI:	https://eprintspublications.npl.co.uk/id/eprint/5815