Specific Heat ofHe3-He4Mixtures Very Near theλLine

Abstract

We have measured the specific heat of liquid ${\mathrm{He}}^4$ and four ${\mathrm{He}}^3$-${\mathrm{He}}^4$ mixtures under their saturated vapor pressure at temperatures very close to the $\lambda$ temperature of each mixture. The specific heat of mixtures with large ${\mathrm{He}}^3$ concentration is clearly cusped at the $\lambda$ line. It approaches a finite maximum with infinite slope. This supports the conjecture that the specific heat of ${\mathrm{He}}^3$-${\mathrm{He}}^4$ mixtures at constant chemical potential becomes infinite at the $\lambda$ line at all ${\mathrm{He}}^3$ concentrations.