Specific heat of He-3/He-4 mixtures at low temperatures and high He-3 concentrations

The specific heat capacity of dilute, liquid mixtures of He-3 in He-4 was measured for concentrations from 1.3% up to 9.45%, and for temperatures between about 15 mK and 200 mK. Pressures ranged from the saturated vapor pressure up to 20 bar. The effective mass of the He-3 quasiparticles was determined from the heat capacities and was found to increase monotonically with concentration at each of the pressures, in contrast to some previous reports[1,2]. These new results agree well with the values of effective mass determined from isochoric pressure measurements by Yorozo et al [2] in the overlapping region of pressure and concentration but also include accurate data for higher concentrations not covered in that experiment.