Characteristics of germanium resistance thermometers from 1 to 35 K and the ISU magnetic temperature scale.

A low-temperature comparator cryostat with a self-balancing ac resistance bridge and a data acquisition system have been used over the past several years to calibrate approximately 45 germanium resistance thermometers, many of them several times. Examples are given of typical thermometer reproducibility results, together with algorithms for estimating self-heating and ac-dc resistance differences for these thermometers. Recent experiences with rhodium-iron resistance thermometry are described in terms of a comparison of previous ISU magnetic thermometry with gas thermometry results from the National Physical Laboratory in England.