Systematic errors in shot noise thermometer measurements

We report comparisons between the Shot Noise Thermometer (SNT), a primary thermometer based on the electronic noise from a tunnel junction, and the ITS-90 in the temperature range from 4 K to 30 K. The SNT indicates a temperature that is systematically high compared to T
₉₀
, and we explain the probable origin of this effect. We characterize other systematic effects in the SNT and provide a roadmap for future extensions in the accuracy of the SNT which could make it metrologically useful in the lower-most ranges of the ITS-90 and especially in the range of the PLTS-2000.