New measurement of the Boltzmann constant k by acoustic thermometry of helium-4 gas

Published

September 11, 2017

Author(s)

Laurent Pitre, Fernando Sparasci, Michael R. Moldover, Cecile Guianvarch, Catherine Martin, Martin Himbert, Mark Plimmer, James B. Mehl, Giuliano Albo, Bo Gao, Lara Risegari

Abstract

The SI unit of temperature will soon be redefined in terms of a fixed value of the Boltzmann constant k derived from an ensemble of measurements worldwide. We report on a new determination of k using acoustic thermometry of helium-4 gas in a 3-litre quasi-sphere. The method is similar to that used in our own experiments on helium and argon with a 0.5-litre resonator. We find for the universal gas constant R = 8.3144597 (49) J·mol-1·K-1. Using the current best available value of the Avogadro constant, we obtain k = 1.38064849 (81) ×10-23 J·K-1 and ur(k) = 0.59x10-6, where the uncertainty is one standard uncertainty corresponding to a 68 % confidence level. This value is in good agreement with those of our earlier measurements and with that of the 2014 CODATA adjustment of the fundamental constants, within the standard uncertainties.

Citation

Metrologia

Volume

54

Issue

6

Pub Type

Journals

Download Paper

https://doi.org/10.1088/1681-7575/aa7bf5

Local Download

Keywords

Boltzmann constant, acoustic thermometry, temperature scale, resonator, Gas constant, fundamental constants

Citation

Pitre, L. , Sparasci, F. , Moldover, M. , Guianvarch, C. , Martin, C. , Himbert, M. , Plimmer, M. , Mehl, J. , Albo, G. , Gao, B. and Risegari, L. (2017), New measurement of the Boltzmann constant k by acoustic thermometry of helium-4 gas, Metrologia, [online], https://doi.org/10.1088/1681-7575/aa7bf5, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=923465 (Accessed October 14, 2025)