Johnson Noise Thermometry - Page 19

Making a driftless Johnson Noise Thermometer


The only solution so far has been to match the frequency characteristics of the two cables very precisely (by adjusting capacitances).

BUT this means: With cable capacitances of a few tens of picofarad, resistance is limited to around 100 ohm, and bandwidth to around 100kHz.

System cannot tolerate any change in the sense resistance – so is only suitable for measuring a single fixed temperature.

All previous attempts have been limited by this constraint, but no longer!


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