THE EFFECTIVE-MASS AND BINDING-ENERGY OF HE-4 IN HE-3 IN THE FERMI-LIQUID REGION

We have measured the solubility of He-4 in liquid He-3 down to about 4 0 mK and at pressures from zero up to similar to 24 atm. The solubilit y was obtained from the thickness of the superfluid film in contact wi th unsaturated solutions of He-4 in He-3 as a function of temperature. By fitting the solubility data to Fermi liquid theory, we obtained th e parameters m(4) and Delta as a function of pressure. Here, m(4)* is the effective mass of He-4 in liquid He-3 and Delta the difference in binding energy between He-4 in pure( 4)He and He-4 in liquid He-3. Th is difference has a minimum near 10 atm. The average of the results fo r m(4), at different pressures, is (1.3 +/- 0.2)m(4). This agrees wit h the many body calculations of de Saavedra et al., and with the Stoke s hydrodynamic mass using the partial volume of He-4 in He-3, v(4)() The partial volume was obtained by taking the derivative of Delta with respect to pressure.