ITS-90 SPRT calibration from the Ar TP to the Zn FP

Main text This is a report to the Consultative Committee for Thermometry (CCT) on the key comparison 9 of Standard Platinum Resistance Thermometer (SPRT) calibration on the International Temperature Scale of 1990 (ITS-90) [1] from 83.8058 K (the Ar triple point) to 692.677 K (the Zn freezing point). The comparison followed a collapsed star protocol, with each of the fourteen participating laboratories shipping two standard platinum resistance thermometers (SPRTs) as transfer standards to the pilot laboratory (National Institute of Standards and Technology, NIST) for a direct comparison of SPRT calibration at the National Metrology Institute (NMI) of origin to calibration at NIST. Measurements were taken at the participating laboratories before and after measurement at NIST to assess the effect of transportation on the transfer standards. The pooled results from all laboratories were combined to calculate a key comparison reference value (KCRV). This report includes the calculation of, and comparisons to, the KCRV as well as bilateral comparisons between labs. In addition, there is space devoted to analysis of the shifts in SPRT values following travel. 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 CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).