The Euramet Metrology Research Programme Project Implementing the New Kelvin (InK)

Abstract

The kelvin, along with the ampere, kilogram, and the mole are likely to be redefined in terms of fundamental constants, in line with Conférence Générale des Poids et Mesures resolution 1 (2011), sometime before 2020. In advance of, and to support, the redefinition, a mise en pratique of the definition of the kelvin (MeP-K) is currently being prepared. The Euramet Metrology Research Programme Implementing the new kelvin (InK) project will coordinate research activity in this field with the objective of improving primary thermometry over the range from 0.0009 K to ${>}3000\,\mathrm{K}$. Specifically, the project will aim to pursue the following three broad objectives: (1) Support the development of primary thermometry techniques for the realization and dissemination of thermodynamic temperatures, particularly at high $({>}1300\,\mathrm{K})$ and low $({<}1\,\mathrm{K})$ temperatures. This is a major objective of InK because primary thermometry methods at the extremes of temperature should, in principle, have lower uncertainties than defined scales. (2) Determine low uncertainty values of $T -T_{90}$ in the temperature region where the defined scale is expected to continue providing the lowest uncertainties. This will support the development of the MeP-K and help in the construction of a reliable data set for any possible future temperature scale. (3) Use different thermodynamic thermometry methods to re-determine $T-T_{2000}$ and therefore hopefully understand the cause of the discrepancy in the background data that constitutes the Provisional Low Temperature Scale of 2000 (PLTS-2000). An overview of the InK project, activities, and intended outcomes is given in this paper.