NEUTRON-PROTON HALO STRUCTURE OF THE 3.563-MEV O+ STATE IN LI-6

We explore the possibility that a stable nucleus has halolike structure in high isospin excited states. As an example the structure of the 3.563 MeV 0+ state of Li6 is studied in a fully microscopic α+p+n three-cluster model, because it is an isobaric analog state of He6 with two-neutron halo structure. An extensive calculation with isospin mixing has shown that the state has spatially extended halolike structure formed by the neutron and the proton outside the α particle. Electron scattering form factors related with the state are reproduced fairly well. © 1995 The American Physical Society.