I. Measurements on the nuclear magnetism in liquid HE_. II. A HE_ cryostat for nuclear magnetic resonance measurements

The technique of adiabatic fast passage has been used to measure the nuclear susceptibility of liquid He3. Measurements along the vaporization curve from 1.2°K to 2.1°K indicate that anti-parallel alignment of the He3 spin system in this temperature range is more important than suggested by previous measurements. Unless existing data at temperatures below 1°K are incorrect, it appears that the susceptibility of He3 is not given precisely by the ideal Fermi-Dirac expression. A He3 cryostat has been constructed to extend the measurements to lower temperatures. Both the operating characteristics of a preliminary cryostat and the design of the final cryostat are discussed