Bilateral comparison of the NRC and PTB local realizations of the ITS-90 between the silver point and 1700 °C using vacuum tungsten strip lamps as transfer standards

Abstract

At its 19th session in September 1996, the Consultative Committee for Thermometry (CCT) agreed to conduct an international key comparison of the local realizations of the International Temperature Scale (ITS) of 1990 above the silver point. High-stability tungsten-strip lamps were selected as transfer standards. The measurements began in 1997 and ended in July 1999. The comparison was piloted by the NMi-VSL and co-piloted by the NPL. The national metrology institutes of 12 countries participated in this key comparison and the initial Draft A report was circulated in October 1999. With the circulation of the report, some participants became aware of problems with their local scale realizations. To link their improved local scale realization to the CCT-K5 results, the NRC asked the PTB to pilot a bilateral comparison of the realization of the ITS-90 between the silver point and 1700 °C using a pair of tungsten-strip lamps as transfer standards. The measurements were carried out from June 2001 to October 2002.The results of the bilateral comparison presented in figures 1 and 2 clearly demonstrate that the NRC and PTB local scale realizations of the ITS-90 between the silver point and 1700 °C agree within the combined standard uncertainty. As the scale realization of the PTB remained unchanged since the measurements performed for the CCT-K5, this bilateral comparison has successfully linked the improved scale realization of the NRC to the results of the key comparison via the stable scale realization of the PTB. Figure 1. Differences between the radiance temperatures of lamp C598 measured at the NRC and the PTB. (NRC_I, NRC_II, NRC_average: temperature measured at the NRC for the first and second run, and average temperature measured at the NRC, respectively. Dotted line: combined standard uncertainty at k = 1.) Figure 2. Differences between the radiance temperatures of lamp 644C measured at the NRC and the PTB. (NRC_I, NRC_II, NRC_average: temperature measured at the NRC for the first and second run, and average temperature measured at the NRC, respectively. Dotted line: combined standard uncertainty at k = 1.)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 CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).