COMPARISON BETWEEN GAS THERMOMETER ACOUSTIC AND PLATINUM RESISTANCE TEMPERATURE SCALES BETWEEN 2 AND 20 K

A constant volume gas thermometer (CVGT), which was constructed at the National Standards Laboratory, Australia, has been used to determine the resistance vs temperature relationships for a number of germanium thermometers to a accuracy of ± 3 millideg. in the temperature range from 2 to 16 K using the NBS Platinum Resistance Thermometer Scale (1955) for reference temperatures. One of these thermometers subsequently was calibrated against the NBS Acoustic Thermometer Scale [National Bureau of Standards Provisional Scale, 2 to 20 K (1965)]. A complete description is given of the CVGT and the data which were obtained with it, as well as a discussion of comparisons which were made between the CVGT scale and the NBS-Acoustic, liquid helium vapor pressure (T58), and NBS Platinum Resistance Thermometer (1955) scales. In general, the NSL CVGT and the NBS-Acoustic scales are in agreement within their combined experimental error (± 5 millideg.) if a slight shift (+ 0.015%) is made in the NBS Platinum Resistance Thermometer Scale (1955) on which the CVGT data are based. These data agree with the Acoustic Thermometry data in suggesting that the boiling point of helium (T58) is low on the Kelvin Thermodynamic scale by as much as 8 (± 3) millideg.