Polarizability of Helium and Gas Metrology

JW Schmidt, RM Gavioso, Eric May, MR Moldover

Research output: Contribution to journalArticlepeer-review

116 Citations (Scopus)


Using a quasispherical, microwave cavity resonator, we measured the refractive index of helium to deduce its molar polarizability A(epsilon) in the limit of zero density. We obtained (A(epsilon,meas)-A(epsilon,theory))/A(epsilon)=(-1.8 +/- 9.1)x10(-6), where the standard uncertainty (9.1 ppm) is a factor of 3.3 smaller than that of the best previous measurement. If the theoretical value of A(epsilon) is accepted, these data determine a value for the Boltzmann constant that is only 1.8 +/- 9.1 ppm larger than the accepted value. Our techniques will enable a helium-based pressure standard and measurements of thermodynamic temperatures.
Original languageEnglish
Pages (from-to)254504
JournalPhysical Review Letters
Issue number25
Publication statusPublished - 2007


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