The quantum second virial coefficient of 3He at low density in the temperature range 0.005-10 K

The quantum second virial coefficient B-q for He-3 is calculated from first principles at low density in the temperature range 0.005-10 K. By "first principles", it is meant that the many-body phase shifts are first determined within the Galitskii-Migdal-Feynman formalism; they are then plugged into the Beth-Uhlenbeck formula for B-q. A positive B-q corresponds to an overall repulsive interaction; a negative B-q represents an overall attractive interaction. The s-wave scattering length a(o) is calculated quite accurately as a function of the temperature T. The effect of the (low-density) medium on B-q is studied. B-q is then used to determine the volume of He-3 at the saturation curve. The compressibility is evaluated as a measure of the non-ideality of the system.