Acoustic properties of supersaturated superfluid 3He 4He solutions

Abstract

The first sound velocity in metastable long-lived superfluid 3He 4He mixtures are measured in the temperature range 30–200 mK and the pressure interval 0–20 atm. The metastable state is reached by continuously increasing the 3He concentration in situ due to changing the osmotic and fountain pressure. The experimental data on the relative sound velocity show a linear dependence for all pressures and can be described by scattering of acoustic phonons by 3He quasiparticles in the solution. The experimental data show no essential anomaly under transition from saturated to supersaturated state.