Low-Temperature Density and Solubility ofHe3in LiquidHe4under Pressure

Abstract

The molar volumes of liquid mixtures of ${\mathrm{He}}^3$ in ${\mathrm{He}}^4$ up to 10 molar% have been measured to 22 atm pressure and to 50 mK using a dielectric technique. The single-phase measurements provide a determination of the Bardeen-Baym-Pines (BBP) parameter $\alpha$ under pressure. A weaker pressure dependence is found than in the measurements of Boghosian and Meyer. The ground-state kinetic energy for pure ${\mathrm{He}}^4$ is deduced from $\alpha$. The two-phase measurements indicate that the solubility at 50 mK of ${\mathrm{He}}^3$ in ${\mathrm{He}}^4$ rises from (6.6 ± 0.1)% at $P=0\mathrm{}$ to a maximum of (9.5 ± 0.12)% at 10 atm; it then drops to (8.3 ± 0.14)% at 22.5 atm. This behavior is found to be consistent with the BBP effective interaction theory using the Ebner potential.