Comparison of PLTS-2000 and the magnetic field fluctuation thermometer at LNE-Cnam

Abstract This paper presents a comparison between the provisional low-temperature scale of 2000 (PLTS-2000) and the magnetic field fluctuation thermometer (MFFT) scales, as realized at LNE-Cnam. The comparison was carried out using three different realizations (i.e. different melting pressure sensors) of PLTS-2000 and a magnetic field fluctuation thermometer operated with a long measurement time (about 3 h) and a more precise power spectral density model of the MFFT response that included an offset term to account for the background noise in the MFFT electronics. The comparison over the range between 8 mK and 1 K shows that the PLTS- 2000 and MFFT scales agree within about 0.2 mK. The results confirm the thermodynamic accuracy of PLTS-2000 at the same level of uncertainty, and show that, under suitable conditions, MFFT measurements can achieve comparable performance. This highlights its potential use in certain practical applications where direct realization of PLTS-2000 is not feasible.