Expérience française de balance du watt : composantes d’incertitude associées à l’étalon de masse pour la détermination de la constante de Planck

¹ Conservatoire national des arts et métiers, Laboratoire commun de métrologie, 61 rue du Landy 93210 La Plaine Saint-Denis, France
² Laboratoire national de métrologie et d’essais, Laboratoire commun de métrologie, 29 avenue Roger Hennequin 78197 Trappes cedex, France

^a patrick.pinot@cnam.fr

Abstract

The Planck constant h was determined in 2014 by means of the French watt balance experiment at the LNE (Trappes). The relative standard uncertainty was 3.1×10^–7. This first French determination was performed in air with a 500 g mass standard made from a Co-based superalloy. The two main corrections are the buoyancy correction of the order of 66 mg, and the magnetic interaction correction of about 37 μg. This interaction force appears between the mass artifact and the residual magnetic field coming from the permanent magnet used in the experiment. The main uncertainty components associated with the mass are the calibration uncertainty, the stability uncertainty, the buoyancy correction uncertainty and the magnetic interaction correction uncertainty. The combined uncertainty component due to the mass is about 36 μg, i.e. 7.2×10⁻⁸ in relative value.