Comparison of the INRIM and PTB lattice-spacing standards

TL;DR

This paper compares the silicon lattice-spacing standards of INRIM and PTB to improve the precision of the kilogram definition based on atomic mass, involving a new apparatus and cross-verification of measurements.

Contribution

It introduces a new experimental setup for high-precision lattice parameter measurement and compares standards from INRIM and PTB to evaluate measurement limits.

Findings

Comparison of lattice parameters between INRIM and PTB standards.

Assessment of measurement capabilities and limits.

Potential to reduce uncertainty in the kilogram definition.

Abstract

To base the kilogram definition on the atomic mass of the silicon 28 atom, the present relative uncertainty of the silicon 28 lattice parameter must lowered to 3E-9. To achieve this goal, a new experimental apparatus capable of a centimetre measurement-baseline has been made at the INRIM. The comparison between the determinations of the lattice parameter of crystals MO*4 of INRIM and WASO4.2a of PTB is intended to verify the measurement capabilities and to assess the limits of this experiment.