EXISTENCE OF PROTON HALOS NEAR THE DRIP-LINE

The proton drip-line nucleus Ne-17 is studied in a three-body model of O-15 plus two protons. The Ne-17 nucleus has a Borromean binding stru cture, and calculations show arms matter radius of 2.77-2.81 fm, in ag reement with experiment. The model gives a proton radius excess about 0.26-0.32 fm over the neutron radius, showing that a proton skin is pr esent. The 73% probability of a valence proton being outside the rms c ore radius is sufficiently large, however, to indicate a halo. Predict ions for the momentum distributions of O-15 fragments are given, and t hese, if verified, would also suggest a two-proton halo structure for Ne-17. This would be the first identification of a two-proton halo nuc leus.