Réalisation de la Masse (RealMass)

• Research unit: METAS
• Project number: F-5212.30096

Key words (English)

Mass realization, on-going key comparison, watt balance, Kibble balance, Planck constant, kilogram

Short description (English)

The watt balance is meant to become a realization of the mass unit according to the new definition of the kilogram. In the last years, the METAS experiment has shown some limitations, mainly linked to the stability of the alignment. Several modifications will now be implemented to the present apparatus in order to reach the required uncertainty level to participate to the on-going key comparison that should start in 2019.

Project aims (English)

The main objective of the project is to reliably realize the new mass unit in a long term basis with a relative uncertainty of the order of 5 x 10^-8. A first step consists in publishing a value of the Planck constant before CGPM 2018. A second step is then to participate to the on-going key comparison between the primary realizations.

Abstract (English)

After several years of development and continuous improvement, the Kibble balance at the Federal Institute of Metrology (METAS) is now operational. Its stability and reliability allows high precision measurements to be performed under vacuum. Two measurement campaigns were conducted in 2021 with 1 kg stainless steel test masses. The result differs from the value deduced from the calibration following the dissemination process after the redefinition of the kilogram by 6 μg with a total standard uncertainty of 43 μg (k = 1).