Final report on the CCM key comparison of density measurements of a silicon sphere (1 kg) by hydrostatic weighing (CCM.D-K1.2023)

Main text This report presents the results of the key comparison CCM.D-K1.2023 of solid density measurements by hydrostatic weighing, which was carried out through May 2022 to June 2024. As transfer standard act a 1 kg sphere made of natural silicon, which is compared directly or indirectly to primary density standards calibrated by mass and dimensional measurements. Ten laboratories participated in this key comparison of five regional metrology organizations (RMO): three of European association metrology institutes (EURAMET), three of Asia pacific metrology programme (APMP), two of inter-American metrology system (SIM), one of intra-Africa metrology system (AFRIMET) and one of Gulf association for metrology (GULFMET). This CIPM key comparison, was coordinated by the Physikalisch-Technische Bundesanstalt (PTB, DE) as the pilot laboratory, and Centro Nacional de Metrología (CENAM) and Istituto Nazionale di Ricerca Metrologica (INRIM) as co-pilot laboratories. The Key Comparison Reference Values (KCRVs) have been obtained for the volume and density values related to the transfer standard by the results of participants, whereby the method of least squares χ2 is estimated. The KCRVs and the corresponding uncertainties were calculated by the weighted mean in case of consistent results. Only two laboratories differed and were excluded from the analysis (En-value greater than 1). For each participant, the degree of equivalence (DoE) was determined with respect to the corresponding KCRV and between the other laboratories. 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 CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).