Heat capacity of3He/4He mixtures

We measured the specific heat capacity of three dilute mixtures (2.6, 1.07, and 0.44%) of³He in⁴He and of pure⁴He. The⁴He contribution to the specific heat of the mixture is subtracted, leaving only the³He part. This is fitted to a theoretical expression over the whole temperature range from 10 to 700 mK. Assuming a dispersion relation of the form =²k²(1+k²)/2m*, the fits yield the value of and the effective mass m* of each mixture. The average value of is –0.076±0.01 A² and the effective mass in the limit of zero concentration is (2.23±0.02)m₃. These are compared to values deduced from other measurements.