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BIPM Kibble balance makes significant progress towards realizing the new kilogram definition in 2019

The year 2019 marked a crucial step towards the completion of the BIPM Kibble balance for realizing the new kilogram definition.

The uncertainty due to misalignment was significantly reduced after the integration of a new interferometer, which is firmly mounted on the magnetic circuit. The electrical grounding of the whole apparatus has been improved, the measurement sequence has been optimized and the apparatus control and data processing software has been refined.

Thanks to METAS (Switzerland), a new measurement of the gravitational acceleration has been carried out with an absolute gravimeter. As a consequence, the relative standard uncertainty has been reduced to about 5 × 10−8. This will allow the BIPM to participate in the first key comparison of realizations of the new definition of the kilogram, CCM.M-K8.2019.