A new³He vapour-pressure based temperature scale from 0.65 K to 3.2 K consistent with the PLTS-2000

Abstract

A new 3He vapour-pressure scale, called PTB-2006, has been established for the temperature range from 0.65 K to 3.2 K. The PTB-2006 removes the thermodynamic inconsistency of the International Temperature Scale (ITS-90) below 1 K by relying on the PLTS-2000. Between 1 K and 2 K the new scale is derived from an interpolation based on the thermodynamic vapour-pressure equation for 3He. At temperatures above 2 K it is nearly identical with the ITS-90. The derivation of the PTB-2006 is described in detail and an uncertainty budget is presented with respect to thermodynamic temperature.