A new small nano-kelvin resolution thermometer for low-temperature experiments

A small, high-resolution paramagnetic susceptibility thermometer was developed using a GdCl3 paramagnetic salt. The device uses a superconducting quantum interference device (SQUID) magnetometer to determine the temperature dependent magnetization of the salt in a magnetic field, The magnetic field is provided by a pair of small samarium cobalt permanent magnet disks situated inside the thermometer housing. This eliminates the need for a heavy, charging solenoid used in a conventional SQUID-based magnetic thermometer system. This thermometer can resolve approximately 10(-9) K near the liquid-gas critical point of He-3 (similar to 3.31 K). The drift rate of the thermometer was measured to be < 2 x 10(-13) K/s, This light weight thermometer (similar to 7 g) is a candidate fur use in future tow-temperature Space Shuttle and International Space Station experiments.