The iMERA/EUROMET Joint Research Project for New Determinations of the Boltzmann Constant

To support new determinations of the Boltzmann constant, which has been asked for by the International Committee for Weights and Measures (CIPM) concerning preparative steps towards new definitions of the kilogram, the ampere, the kelvin and the mole, an iMERA/EUROMET joint research project is coordinating the European activities in this field in France (LNE‐INM/CNAM, University of Paris North), Italy (INRiM, Universities of Naples and Milan), the United Kingdom (NPL) and Germany (PTB). In this major European research project the Boltzmann constant will be determined with various methods. The aims and the progress to date of the project are reviewed in this paper.