Comparison of ITS-90 realizations from 13 K to 273 K between LNE-CNAM and INRIM

TL;DR

This paper reports a bilateral comparison of ITS-90 temperature realizations between 13 K and 273 K by LNE-CNAM and INRIM, demonstrating substantial agreement within uncertainties and supporting the laboratories' thermometric capabilities.

Contribution

First bilateral comparison of cryogenic fixed point realizations between LNE-CNAM and INRIM covering 13 K to 273 K, providing evidence of consistent thermometric performance.

Findings

Results show substantial agreement within combined uncertainties.

Comparison covers all cryogenic fixed points of the ITS-90 scale.

Supports the thermometric capabilities of both laboratories.

Abstract

Since Key Comparison CCT-K2, only few comparisons on realizations of cryogenic fixed points have been carried out, be they bilateral (three, of which one still pending) or multilateral (two trilateral). Since a forthcoming general follow-up is unlikely, any bilateral comparison, not only key comparisons, is most welcome to provide evidence of the continuing thermometric capabilities of the laboratories involved in the realization of the ITS-90. Not too long after the creation in 2018 of the Joint Research Laboratory for Fluid Metrology Evangelista Torricelli between LNE-CNAM and INRIM, the two laboratories agreed to perform a bilateral comparison at all the cryogenic fixed points of the scale between 13 K and 273 K, including the two hydrogen vapour-pressure temperatures required for the full platinum resistance thermometer range 3.3.1 of the ITS-90. The results are reported here and show a substantial agreement, within the combined uncertainties.