Title :
The IMGC volume-density standards for the Avogadro constant
Author :
Sacconi, A. ; Peuto, A.M. ; Mosca, M. ; Panciera, R. ; Pasin, W. ; Pettorruso, S.
Author_Institution :
Istituto di Metrol., Torino Univ., Italy
fDate :
4/1/1995 12:00:00 AM
Abstract :
Volume-density standards in the form of single-crystal silicon spheres have been introduced and developed at the IMGC. A new sphere of nearly perfect form has been characterized on the basis of a comprehensive set of interferometric, roundness, mass and hydrostatic measurements. From its mass and volume and from the evaluation of the oxide layer and of impurities, a density of (2.32908350±0.00000036) g/cm3 has been assigned to a near-perfect silicon crystal. In comparison to the measurements based on a previous sphere, the relative combined uncertainty has been reduced from 4.1×10-7 to 1.5×10-7
Keywords :
atomic mass; constants; density measurement; lattice constants; mass measurement; measurement standards; silicon; spatial variables measurement; Avogadro constant; IMGC; IMGC volume-density standards; Si; Si single-crystal spheres; dimensional measurement; hydrostatic measurements; impurities; interferometric measurement; mass measurements; oxide layer; relative combined uncertainty; roundness measurements; volume measurement; Atomic measurements; Density measurement; Helium; Impurities; Optical interferometry; Position measurement; Silicon; Standards development; Volume measurement; Wavelength measurement;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
