A determination of the Boltzmann constant from speed of sound measurements in helium at a single thermodynamic state

摘要

We report on acoustic and microwave measurements made with a purified helium sample maintained close to a single thermodynamic state (T_(exp) approx 273.16 K, p_(exp) approx 410 kPa) within a 2.1 L volume stainless steel spherical cavity. From these measurements and ab initio calculations of the non-ideality and the refractive index of helium, we determine a value for the Boltzmann constant kB which is consistent with the recommended 2006 CODATA value: (k_(B) - k_(2006))/k_(2006) velence (-7.5 +- 7.5) X 10~(-6). We discuss the current limits of the experiment and the prospects of a further reduction in the uncertainty associated with the determination of k_(B).