Shot Noise Thermometry down to 10 mK

We report measurements of the Shot Noise Thermometer (SNT), a primary thermometer based on the electronic noise from a tunnel junction, in the range from 10 mK to 200 mK. We demonstrate operation of the SNT down to 10 mK with 10\% accuracy at the lowest measured temperature. At 10 mK, where for a measurement frequency of f=450 MHz, $hf=2.5k_BT$, we demonstrate that, provided that quantum corrections are taken into account, the SNT continues to be a practical thermometer. We also show that self-heating is not a measurable problem and demonstrate a simplified readout of the SNT.