We study the scattering of atoms, rotons and phonons at the free surface of 4He at normal incidence and calculate the evaporation, condensation and reflection probabilities. Assuming elastic one-to-one processes and using general properties of the scattering matrix, such as unitarity and time reversal, we argue that all nonzero probabilities can be written in terms of a single energy-dependent parameter. Quantitative predictions are obtained using linearized time dependent density functional theory.
@article{arxiv.cond-mat/9612042,
title = {Quantum Evaporation from Superfluid Helium at Normal Incidence},
author = {F. Dalfovo and M. Guilleumas and A. Lastri and L. Pitaevskii and S. Stringari},
journal= {arXiv preprint arXiv:cond-mat/9612042},
year = {2009}
}
Comments
12 pages, REVTeX, 2 postscript figures, available also at http://anubis.science.unitn.it/~dalfovo/papers/papers.html