Measurements of volume and density of the new IMGC silicon standard [for Avogadro constant determination]

The IMGC has developed volume-density standards in the form of single-crystal silicon spheres within the project for the determination of the Avogadro constant. A new sphere of nearly perfect form is going to be available, made of high-purity and near-perfect silicon single-crystal. The absolute determination of its mass and volume is presented together with the expected improvements. The new standard will be then intercompared with similar artifacts within a joint international project coordinated through the WG on the Avogadro constant of the CCM.