[10p-S011-1~5] Recent topics in measurement standards

[10p-S011-3] Planck constant for the new definition of the kilogram

〇Kenichi Fujii¹ (1.National Metrology Institute of Japan)

Keywords:kilogram, Planck constant, Avogadro constant

In order to revise the present definition of the kilogram, the only SI base unit still defined by a material artefact, the Planck constant has been determined by the X-ray crystal density (XRCD) method using isotopically enriched silicon crystals. Using the data measured by the XRCD method and some other results determined by the Kibble (watt) balance method, the CODATA Task Group on Fundamental Constants (TGFC) determined the value of the Planck constant for the new definition of the kilogram. The TGFC also determined the values of the elementary charge, the Boltzmann constant and the Avogadro constant to revise the present definitions of the ampere, kelvin and mole. The concept of the new definition of the kilogram and the method for realizing the kilogram from the defined value of the Planck constant are presented, as well as what would be expected from the new definition.