A calculable and correlation-based magnetic field fluctuation thermometer

We have developed a new Magnetic Field Fluctuation Thermometer (MFFT) specifically designed for operation in primary mode, which requires the determination of the relation between thermal flux noise density and thermodynamic temperature. The noise thermometer combines a correlation-based SQUID readout and an integrated conductivity measurement on the metallic temperature sensor with an in situ flux calibration. The operation of the MFFT is modelled theoretically. First temperature measurements in secondary mode between 9 mK and 4.2 K showed excellent agreement with a copy of the PLTS-2000 within 0.5%.