Bilateral comparison of 1.018 V and 10 V standards between the SMD (Belgium) and the BIPM, November to December 2024 (part of the ongoing BIPM key comparison BIPM.EM-K11.a and b)

Main text As part of the ongoing BIPM key comparison BIPM.EM-K11.a and b, a comparison of the 1.018 V and 10 V voltage reference standards of the BIPM and the Service de Métrologie (SMD), Brussel, Belgium, was carried out from November to December 2024. Two BIPM Zener diode-based travelling standards (Fluke 732A), BIPM_1 (Z1) and BIPM_H (ZH), were transported to SMD and back to BIPM by road. Since the laboratories are close to each other, Fluke 732A standards that have a long metrological history were selected to serve as transfer standards. At the SMD and the BIPM, the reference standard for DC voltage is a Programmable Josephson Voltage Standard (PJVS). The output electromotive force (EMF) of each travelling standard was measured by direct comparison with the primary standard. The final result of the comparison is presented as the difference between the values assigned to DC voltage standards by SMD, at the level of 1.018 V and 10 V, at SMD, USMD, and those assigned by the BIPM, at the BIPM, UBIPM, at the reference date of the 6th of December 2024. USMD - UBIPM = -0.047 μV; u c = 0.017 μV, at 1.018 V USMD - UBIPM = 0.06 μV; u c = 0.09 μV, at 10 V where u c is the combined standard uncertainty associated with the measured difference, including the uncertainty of the realization of the volt at the BIPM and at SMD, and the uncertainty related to the comparison. To reach the main text of this paper, click on Final Report . Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/ . The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).