Key comparison BIPM.RI(I)-K4 of the absorbed dose to water standards of the NMIJ, Japan, and the BIPM in ⁶⁰Co gamma radiation

Main text A new key comparison of the standards for absorbed dose to water of the National Metrology Institute of Japan (NMIJ), Japan, and the Bureau International des Poids et Mesures (BIPM) was carried out in the 60Co radiation beam of the BIPM in February 2022. The comparison result, based on the calibration coefficients for two transfer standards and evaluated as a ratio of the NMIJ and the BIPM standards for absorbed dose to water, is 0.9952 with a combined standard uncertainty of 4.0 parts in 103. The result agrees within the uncertainties with the comparison carried out in 2009. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database. 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 CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).