Investigation by Second Sound of the Inertial Mass ofHe3in SuperfluidHe4at Low Temperatures

Abstract

From measurements of the velocity of second sound and the osmotic pressure the inertial mass of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in superfluid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ has been obtained as a function of temperature and concentration. The results indicate that (i) the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ quasiparticle spectrum is not quite parabolic and (ii) part of the quasiparticle effective interaction is velocity dependent or "non-local" and resembles the interaction of spheres moving through a nonviscous classical fluid.