PTB‐96: The Ultra‐Low Temperature Scale of PTB

The temperature scale PTB‐96 for the range from 0.9 mK to 1 K is one of the melting‐pressure scales, on which the Provisional Low Temperature Scale of 2000, PLTS‐2000, is based. The construction and the thermodynamic significance of the PTB‐96 are discussed in detail considering the now available comprehensive information including recently obtained experimental data. The thermodynamic significance has been evaluated primarily by means of noise thermometry. The internal consistency has been checked by applying platinum NMR (nuclear magnetic resonance) thermometry and CMN (cerous magnesium nitrate) thermometry. Considering the results both of primary noise thermometry and the consistency checks, a detailed uncertainty budget is presented.