The binding of He-3 impurities to a superfluid vortex

Using many-body wave functions we have calculated the binding energies of a He-3 impurity and a fictitious He-4 impurity to a superfluid vortex. We use both a shadow wave function with distributed vorticity, Psi(D), and the Onsagar-Feynman function with singular vorticity, Psi(O-F). For both wave functions there was no difference in the binding energies of the mass 3 and mass 4 impurities. The binding energy was independent of the density for Psi(D), but strongly density dependent for Psi(O-F) The value of 2.3 K for Psi(D), is somewhat smaller than the experimental estimate. Our results strongly suggest that the binding is due to the displacement of high-velocity He-4 atoms from the vortex core by the impurity. (C) 2000 Elsevier Science B.V. All rights reserved.