A determination of the molar gas constantRby acoustic thermometry in helium

This is the authors' abstract. We don't add key points for this paper.

We have determined the acoustic and microwave frequencies of a misaligned spherical resonator maintained near the temperature of the triple point of water and filled with helium with carefully characterized molar mass g mol −1 , with a relative standard uncertainty . From these data and traceable thermometry we estimate the speed of sound in our sample of helium at K and zero pressure to be m 2 s −2 and correspondingly deduce the value J mol −1 K −1 for the molar gas constant. We estimate the value J K −1 for the Boltzmann constant using the currently accepted value of the Avogadro constant N A . These estimates of R and k , with a relative standard uncertainty of 1.06 × 10 −6 , are 1.47 parts in 10 6 above the values recommended by CODATA in 2010.