Volume Measurement of two Spheres from the new Avogadro Crystal Si28-24Pr11

PTB has again produced a new
²⁸
Si-crystal (Si28-24Prll) and from that two new spheres. Recently two spheres from the first PTB crystal (Si28-23Prll) had been measured and their results had been used for the special CODATA fixing of Avogadro and Planck constant in the revised International System of Units (SI). Unfortunately, this latest result showed a small deviation from former results (namely of the IAC crystal Si28-10Prll), however, with a reduced uncertainty. Also for the reason to clarify an unknown dependence on the silicon crystal the measurements of this third crystal were performed with priority.