Evaporation from Superfluid Helium

Abstract

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.