Abstract. A key comparison has been made between the air-kerma standards of the NMIJ and the BIPM in the low-energy x-ray range. The results show the standards to be in agreement within the expanded uncertainty, although there is evidence of a trend in the results for different radiation qualities. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.

Main text. 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 kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).