InK - Implementing the new kelvin

SIB01: Implementing the new kelvin "InK"

Currently almost all temperature measurement around the world is based on traceability to a defined scale either the International Temperature Scale of 1990, ITS-90 or, below 1 K, the Provisional Low Temperature Scale of 2000, PLTS-2000. These scales are empirical in basis, reliant upon a set of fixed points whose temperatures were determined a priori by primary thermometry.

Recent technical advances in temperature metrology, the advent of the developing mise en pratique for the definition of the kelvin (MeP-K) and the proposed kelvin redefinition in terms of the Boltzmann constant provide a unique opportunity to fundamentally change the practice of temperature measurement. The aim of this project is to make a step change improvement in primary thermometry over six orders of magnitude; 0.0009 K to 3000+ K.

This change will be effected through developing primary thermometry methods that both challenge and supplant the defined scales at high (>1000 C) and low (<1 K) temperatures. This will effect a paradigm shift in the practice of thermometry. At these extremes thermodynamic temperature will be, for the first time (anticipating the new kelvin defined in terms of the Boltzmann constant) directly realised and disseminated, instead of one of the defined scales.

Between these temperature extremes new values of T - T90 with the lowest uncertainties (<1 mK) are required in the a) short term to provide ultra-reliable T - T90 data for the MeP-K and b) longer term to develop the primary thermometry techniques needed to progressively supplant defined scales in the next decade.

The InK project started in Oct 2012 and will run until Sep 2015. The coordinator is Prof Graham Machin from NPL. There are 16 formal participants (link to participant page) and three collaborators (NIST, NRC and KRISS).

Individual collections of T - T90 data on which the present best estimates are based.

Coordinator: Prof Graham Machin, Head, Temperature Standards, NPL

Contact details: Tel 00 44 20 8943 6742   |   Email