Sound propagation in superfluid solutions 3He- 4He with variable concentration

Abstract

In the temperature region above 25mk, the relative measurements of the first sound velocity are made in superfluid solutions whose concentration may be directly controlled during the experiment. A two-chamber cell is described, which permits a 0.88 to 6.2% 3He variation of the concentration through changing the temperature in one of the chambers. It is shown that the concentration estimated from the acoustic measurements is in agreement with the thermodynamic calculation based on the data for the osmotic pressure and the fountain pressure.