Heat capacity of 3 He/ 4 He 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 e=ħ2 k 2(1+γk 2)/2m*, the fits yield the value of γ and the effective mass m* of each mixture. The average value of γ is −0.076±0.01 A2 and the effective mass in the limit of zero concentration is (2.23±0.02)m 3. These are compared to values deduced from other measurements.