Speer Carbon Resistors as Thermometers for Use Below 1°K

Abstract

A survey has been made of the properties of certain resistors made by the Speer Carbon Company to determine whether they might be suitable for resistance thermometry below 1°K. It is found that resistors of grade 1002 in various nominal resistance values from 100–500 Ω are the most suitable for very low temperature work. Resistors of the same nominal size matched at room temperature and at 4°K have rather similar characteristics down to 0.02–0.03°K. The resistors may also be baked at a sufficiently high temperature to allow them to be sealed into apparatus using thermocuring epoxy resins. A magnetic field perpendicular to the axis of the resistors decreases the resistance at constant temperature.