Measurements on Gallium‐Doped Germanium Thermometers

Germanium doped with controlled amounts of gallium and compensated with antimony has a useful thermometric sensitivity in the liquid helium and hydrogen ranges. The effects of magnetic fields on resistance—and hence on thermometry—are reported over the 2–25°K interval. Preparation and encapsulation of germanium ``bridges'' is described, and the thermal properties of encapsulated assemblies measured, including the variation of resistance with input power, and the thermal response time (∼0.1 sec at 4°K). A simple method for checking the reproducibility of thermometers is described.