Universality of the specific heat of He3-He4 mixtures at the λ transition

We present an analysis of specific-heat data of He3-He4 mixtures at the λ transition in which a trial function with a correction term to the leading singularity is used. For mixtures up to 0.39 mole fraction of He3 in He4 we find a universal leading exponent α=α′=-0.022 and a universal leading amplitude ratio of AA′=1.088. These results are in agreement with theoretical expectations and other experimental results along the λ line as a function of pressure. The data at pure He4 and saturated vapor pressure appear to show a small deviation from universal behavior.