| Author(s): |
James W. Schmidt; R Gavioso; E May; Michael R. Moldover; |
| Title: |
The Polarizability of Helium and Gas Metrology |
| Published: |
June 22, 2007 |
| Abstract: |
Using a quasi-spherical, microwave cavity resonator, we measured the refractive index of helium to deduce its molar polarizability Aε in the limit of zero density. We obtained (Aε,meas - Aε,theory)/Aε = (-1.8{plus or minus} 8.4)× 10-6, where the standard uncertainty (8.4 ppm) is factor of 3.6 smaller than that of the best previous measurement. If the theoretical value of Ae is accepted, these data determine a value for the Boltzmann constant that is only (1.8 {plus or minus} 8.4) ppm larger than the accepted value. Our techniques will enable a helium-based pressure standard and measurements of thermodynamic temperatures. |
| Citation: |
Physical Review Letters |
| Volume: |
98 |
| Issue: |
06/22/07 |
| Pages: |
pp. 254504-1 - 254504-4 |
| Keywords: |
Boltzmann constant;dielectric constant;fundamental constant;helium;index of refraction;microwave resonator;polarizability;pressure standard;temperature standard |
| Research Areas: |
Measurement Standards, Gas Metrology, Physical Properties, SI (Thermodynamics Units), Standards, Chemical Engineering & Processing, Chemistry, Fluids, Thermodynamics |
