Surface Tension of LiquidHe4

Abstract

We have measured the surface tension of liquid ${\mathrm{He}}^4$ down to 0.35°, using the capillary-rise method. The results are consistent with the theory that this temperature variation is mainly due to the excitation of surface modes similar to capillary waves. However, the results do not exclude an alternative theory, due to Singh, which considers the effect of the surface on the wave functions of an ideal degenerate Bose-Einstein gas. At the $\lambda$ point, we observed a discontinuity (or at least a very rapid variation) of the first derivative with respect to temperature.