Accurate measurements of the Avogadro and Planck constants by counting silicon atoms

  title={Accurate measurements of the Avogadro and Planck constants by counting silicon atoms},
  author={H. Bettin and K. Fujii and John Man and G. Mana and E. Massa and A. Picard},
  journal={Annalen der Physik},
Fundamental constants link seemingly different fields of physics and seemingly different quantities and measurement units. Consequently, they are of the utmost interest in metrology and it has been planned to redefine the kilogram by fixing the numerical value of the Planck constant. This paper summarises the methods to measure the ratio between the Planck constant and a mass and reviews the determination of the Avogadro constant by counting the atoms in a silicon crystal highly enriched by the… Expand
A More Accurate Measurement of the 28Si Lattice Parameter
In 2011, a discrepancy between the values of the Planck constant measured by counting Si atoms and by comparing mechanical and electrical powers prompted a review, among others, of the measurement ofExpand
Model uncertainty and reference value of the Planck constant
  • G. Mana
  • Mathematics, Engineering
  • 2016
Statistical parametric models are proposed to explain the values of the Planck constant obtained by comparing electrical and mechanical powers and by counting atoms in Si 28 enriched crystals. TheyExpand
On the Choice of Fixed Fundamental Constants for New Definitions of the SI Units
Different ways of choosing the fundamental physical constants in connection with the planned transition to new definitions of the fundamental SI units (kilogram, mole, ampere, and kelvin) areExpand
Precise determination of the ratio h/m u: a way to link microscopic mass to the new kilogram
The ratio between the Planck constant and the unified atomic mass constant should have a special status in the framework of the future international system of units. Currently (before theExpand
(30)Si mole fraction of a silicon material highly enriched in (28)Si determined by instrumental neutron activation analysis.
The latest determination of the Avogadro constant was carried out by counting the atoms in a pure silicon crystal highly enriched in (28)Si, and an independent estimate of the (30)Si mole fraction was obtained by applying a relative measurement protocol based on Instrumental Neutron Activation Analysis. Expand
Alternative set of defining constants for redefinition of four SI units
We discuss different sets of defining constants, fixed values of which are considered in connection with the transition to new definitions of four SI units (the kilogram, the mole, the ampere, andExpand
Modernizing the SI: implications of recent progress with the fundamental constants
Recent proposals to re-define some of the base units of the SI make use of definitions that refer to fixed numerical values of certain constants. We review these proposals in the context of theExpand
Lattice strain at c-Si surfaces: a density functional theory calculation
The measurement of the Avogadro constant by counting Si atoms is based on the assumption that Si balls of about 94 mm diameter have a perfect crystal structure up to the outermost atom layers. ThisExpand
Josephson Voltage Metrology for Watt Balance Experiments at NIST
The Planck constant, h, is one of the seven fundamental constants proposed to redefine the SI. It has been measured by the watt balance experiments since the 1980s. In its early days, the wattExpand
What Is a Kilogram in the Revised International System of Units (SI)
The definition of the kilogram, the unit of mass in the International System of Units (SI), has not changed in more than 125 years. The kilogram is still defined by the mass of a Pt–Ir cylinderExpand


Determination of the Avogadro constant by counting the atoms in a 28Si crystal.
A new approach for the molar Planck constant determination by counting the atoms in 1 kg single-crystal spheres, which are highly enriched with the 28Si isotope, is described, which is the most accurate input datum for a new definition of the kilogram. Expand
About the existing discrepancy in the determinations of the Avogadro constant
It is proved that the discrepancy in the determinations of the Avogadro constant cannot be explained by vacancies or interstitials, and indications for macroscopic bubbles or cavities could not be found. Expand
Counting the atoms in a 28Si crystal for a new kilogram definition
This paper concerns an international research project aimed at determining the Avogadro constant by counting the atoms in an isotopically enriched silicon crystal. The counting procedure was based onExpand
New determination of the fine structure constant and test of the quantum electrodynamics
We report a new value of the fine structure constant with a relative uncertaintity of 6.6×10-10. This result is deduced from the h/m ratio measurement on Rb atoms. The comparison with the electronExpand
Reconciling Planck constant determinations via watt balance and enriched-silicon measurements at NRC Canada
The next revision to the International System of Units will emphasize the relationship between the base units (kilogram, metre, second, ampere, kelvin, candela and mole) and fundamental constants ofExpand
High-accuracy mass spectrometry with stored ions
Abstract Like few other parameters, the mass of an atom, and its inherent connection with the atomic and nuclear binding energy is a fundamental property, a unique fingerprint of the atomic nucleus.Expand
Towards an electronic kilogram: an improved measurement of the Planck constant and electron mass
The electronic kilogram project of NIST has improved the watt balance method to obtain a new determination of the Planck constant h by measuring the ratio of the SI unit of power W to the electricalExpand
Elemental characterization of the Avogadro silicon crystal WASO 04 by neutron activation analysis
Impurity measurements of the 28 Si crystal used for the determination of the Avogadro constant are essential to prevent biased results or underestimated uncertainties. A review of the existing dataExpand
History and progress on accurate measurements of the Planck constant.
  • R. Steiner
  • Physics, Medicine
  • Reports on progress in physics. Physical Society
  • 2013
A brief history of the methods to measure a combination of fundamental constants, thus indirectly obtaining the Planck constant and a review of the ongoing advances at the (currently) seven national metrology institutions where these experiments are pursued. Expand
A Preliminary Measurement of the Fine Structure Constant Based on Atom Interferometry
Using an atom interferometer method, we measure the recoil velocity of a cesium atom due to the coherent scattering of a photon. This measurement is used to obtain a value of /MCs and the fineExpand