National Research Council of Canada. Measurement Science and Standards
primary thermometry; thermodynamic temperature; T−T90; polarizing gas thermometry; refractive index gas thermometry; RIGT
The implementation of microwave refractive index gas thermometry at the
National Research Council between 24.5 K and 84 K is reported. A new gas-handling
system for accurate control and measurement of experimental gas pressure has been
constructed and primary thermometry measurements have been performed using a
quasi-spherical copper resonator and helium gas at temperatures corresponding to
three defining fixed points of the International Temperature Scale of 1990 (ITS-90).
These measurements indicate differences between the thermodynamic temperature T
and ITS-90 temperature T90 of (T −T90) = −0:60±0:56 mK at T90 = 24:5561 K,
(T −T90) = −2:0±1:3 mK at T90 = 54:3584 K, and (T −T90) = −4:0±2:9 mK at
T90 = 83:8058 K. The present results at T90 = 24:5561 K and T90 = 83:8058 K agree
with previously reported measurements from other primary thermometry techniques
of acoustic gas thermometry and dielectric constant gas thermometry, and the result
at T90 = 54:3584 K provides new information in a temperature region where there is
a gap in other recent data sets.
International Journal of Thermophysics38, no. 107.