In 2005, the Consultative Committee for Thermometry (CCT) recommended the creation of a Mise en pratique for the definition of the kelvin and envisioned that future versions of the Mise en pratique would recommend values of the differences between thermodynamic temperatures and ITS-90 temperatures (T − T90). At the CCTs request, Working Group 4 (WG4) critically reviewed all available measurements of T − T90, the uncertainties, and documented the conversion of older data to the ITS-90. From the review, we provide consensus estimates of T T90 for selected measurements from 4.2 K to 1358 K as well as a recommendation for T − T90 spanning the range 0.65 K to 4.2 K. WG4 identified certain temperature ranges where researchers are encouraged to undertake additional high-accuracy measurements of T T90. In order to disseminate the differences T T90 via the Mise en pratique, we provide two analytic functions for T T90, one for use below TTPW and one for use above TTPW. The discontinuity of the derivative dT90/dT at TTPW is discussed and the consistency with the results of recent acoustic gas thermometry and with the resistance ratios of platinum resistance thermometers is investigated.
Proceedings Title: 2010 TEMPMEKO & ISHM
Conference Dates: May 31-June 4, 2010
Conference Location: Portoro, -1
Conference Title: Joint International Symposium on Temperature, Humidity, Moisture and Thermal Measurements in Industry and Science
Pub Type: Conferences
differences, T T90, International Temperature Scale ITS-90, primary thermometry, thermodynamic temperature