Calibration of two mass standards with the LNE Kibble balance in 2024

Abstract Kibble balances are complex electromechanical instruments that enable the determination of mass within the SI by linking it to the Planck constant h , the defining constant of the mass unit. The LNE has been developing its own Kibble balance since 2002, with the most recent improvements focusing on the implementation of a contactless linear motor for the dynamic phase and the fine adjustment of the beam’s orientation with respect to the horizontal plane for the static phase. In 2024, two mass calibration campaigns were carried out using the LNE Kibble balance: first with an iridium standard (DB1), and then with a platinum-iridium standard (W1). Both artefacts have a nominal mass of 500 g, and their masses were determined with relative standard uncertainties of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>3.1</mml:mn> <mml:mo>⋅</mml:mo> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>8</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>3.5</mml:mn> <mml:mo>⋅</mml:mo> <mml:mrow> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>8</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:mrow> </mml:math> respectively ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mrow> <mml:mtext>k </mml:mtext> </mml:mrow> <mml:mo>=</mml:mo> <mml:mrow> <mml:mtext> </mml:mtext> </mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> </mml:math> ).