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An improved result on the measurement of the Avogadro constant from a 28Si crystal



Yasushi Azuma, G Barat, Guido Bartl, Horst Bettin, Michael Borys, I Busch, L Cibik, G D' Agostino, K Fujii, H Fujimoto, A Hioki, Michael Krumrey, U Kuetgens, N Kuramoto, Giovanni Mana, E Massa, R Meess, Shigeki Mizushima, T Narukawa, Arnold Nicolaus, Axel Pramann, Savelas A. Rabb, Olaf Rienitz, C Sasso, M Stock, Robert D. Vocke Jr., A Waseda, S Zakel


In this paper new results of an international research project aimed at determining the Avogadro constant by counting the atoms in an isotopically enriched silicon crystal are reported. The 28Si spheres were decontaminated and reworked in order to produce surfaces without metal contamination and to improve the roundness. Then the Avogadro constant was measured again with improved methods and apparatuses yielding a value of NA = 6.022 140 75(12) × 1023 mol-1. Thus, the X-ray crystal density method reached a relative uncertainty of 2.0 × 10-8, which is aimed at for the realization of the new kilogram definition.


Avogadro constant, kilogram redefinition, IAC, AVO28


Azuma, Y. , Barat, G. , Bartl, G. , Bettin, H. , Borys, M. , Busch, I. , Cibik, L. , D' Agostino, G. , Fujii, K. , Fujimoto, H. , Hioki, A. , Krumrey, M. , Kuetgens, U. , Kuramoto, N. , Mana, G. , Massa, E. , Meess, R. , Mizushima, S. , Narukawa, T. , Nicolaus, A. , Pramann, A. , Rabb, S. , Rienitz, O. , Sasso, C. , Stock, M. , Vocke Jr., R. , Waseda, A. and Zakel, S. (2015), An improved result on the measurement of the Avogadro constant from a 28Si crystal, Metrologia (Accessed November 30, 2021)
Created March 24, 2015, Updated October 12, 2021