Neutron skin and halo in medium and heavy nuclei within the extended Thomas-Fermi theory

The neutron skin and halo distributions in medium and heavy nuclei are calculated within the extended Thomas-Fermi approximation. Calculations are carried out for the effective Skyrme-like forces using the direct variational method. The analytical expression for the isovector shift of the rms radii $\Delta r_{np}$ as a sum of skin- and halo-like terms is obtained. The contribution of halo and skin terms to $\Delta r_{np}$ are found to be approximately equal.