The Velocity Distribution of Atoms Evaporating from Superfluid Helium.

S. Stringari, F. Dalfovo, M. Guilleumas +2 more

Johan W. Bakker, Herman van Kempen, Huub W. M. Salemink +1 more

T. R. Sosnick

Milton W. Cole

We calculate the angular and spectral distribution of atoms evaporating from superfluid helium using a kinetic-theory description of the liquid quasiparticles. Phase-space analysis indicates that the evaporation spectrum exhibits information about the single-particle properties of the liquid, but in particular does not manifest the quasiparticle density of states. The latter conclusion is in agreement with recent experimental results.

S. Balibar

A few years after the discovery of Bose Einstein condensation in several gases, it is interesting to look back at some properties of superfluid helium. After a short historical review, I comment shortly on boiling and evaporation, then on the role of rotons and vortices in the existence of a critical velocity in superfluid helium. I finally discuss the existence of a condensate in a liquid with strong interactions, and the pressure variation of its superfluid transition temperature.

Juha Kopu