Contact: Graham Machin

Implementing the new kelvin

The SI unit of temperature – the kelvin – is to be redefined in terms of the Boltzmann constant, which relates energy at the individual particle level with temperature. This redefinition, along with other recent advances in temperature metrology, will enable a fundamental change in the way we measure temperature.

Current temperature scales rely upon a set of fixed points determined by primary thermometry. This project will improve primary thermometry at temperatures ranging from 0.0009 K to over 3000 K and will assign definitive thermodynamic temperatures to a set of high temperature fixed points for the first time. This, along with new sensing methods and techniques, will allow extreme temperature measurements to be linked to a direct realisation of the kelvin.

The results will benefit the large number of industries that measure temperature on a daily basis, in particular low temperature industries such as cryogenics and high temperature industries such as steel production.

Contact: Stuart Davidson

Developing a practical means of disseminating the new kilogram 

The SI unit of mass - the kilogram - is the last of the seven base measurement units defined in terms of a material artefact However, progress is being made towards a redefinition in terms of the Planck constant, realised via the watt balance and silicon sphere Avogadro experiments.

The current definition of the kilogram is realised by the international prototype of the kilogram in air, but the new definition will be under vacuum conditions. This means that a link between the mass of the kilogram in air and its mass in vacuum must be established.

This project will produce new mass standards to enable traceability between the existing mass scale and the new experiments. This will enable the implementation and dissemination of the new kilogram and ultimately lead to a redefinition of the unit of mass.