Recommendation 3 of the 85th CIPM (1996)

Temperature scale below 1 K

The Comité International des Poids et Mesures,

considering

• that many important research activities are in progress at temperatures below 1 K,
• that these researches require an accepted temperature scale which c1osely represents thermodynamic temperatures,
• that the ITS-90 ³He vapour pressure equation is believed to deviate from thermodynamic temperatures between 1 K and its lower limit of 0,65 K, noting that several discrepant laboratory scales below 0,65 K have been developed,

recommends

• that the deviation of the ITS-90 ³He vapour pressure equation from thermodynamic temperature below 1 K be further investigated,
• that research be undertaken to resolve discrepancies between existing ³He melting pressure scales,
• that national laboratories collaborate to develop a ³He melting pressure equation to serve as the basis for an extension of the ITS-90 down to a temperature of about 1 mK.

DOI : 10.59161/CIPM1996REC3E