Improved spectral aberration in Johnson Noise Thermometry

Spectral aberration has been the main source of uncertainty in Johnson Noise Thermometry approach to measuring the Boltzmann constant. Recently, with newly developed hardware and the introduction of a novel fitting algorithm for analyzing the data, we have achieved a frequency independent spectral aberration for measurements with the NIST JNT system. Consequently, we performed a data drift analysis and an electromagnetic interference investigation to explain a residual offset that affects the Boltzmann constant.