Thursday, March 3, 2011, 16:00
WHGA/001
A. Eichenberger, Federal office of metrology METAS, Bern
Abstract:
Today, the kilogram is the last unit of the International System of Units (SI) still based on an
artefact: the international prototype of the kilogram K which is kept at the Bureau
International des Poids et Mesure (BIPM). The international comparisons between K and
national kilogram prototypes have clearly shown a long term relative drift. Clearly, such a
situation is no longer satisfactory for the definition of an important unit of the SI.
There is now a general consensus in the metrology community that the time for a redefinition
of the kilogram has come. The new definition should link the kilogram to fundamental
constants with a relative uncertainty of a few parts in 10-8. Several experiments have been
attempted to realize the new definition of the kilogram and the watt balance approach seems
to be the most promising one. The METAS watt balance has recently produced a
measurement of the Planck constant and the realization of a new experimental setup is
underway. After a general review, this presentation will focus on the METAS experiment and
discuss the latest results.