Skyrme-Hartree-Fock description of the nuclear structure in Ca isotopes (II) Neutron halo, skin and particles in the classically forbidden area

The pure-neutron-matter together with the neutron skin or halo in Ca isotop es is studied using the Skyrme-Hartree-Fock model. It is shown that the pur e-neutron-matter thickness depends not only on the Fermi levels of the neut rons, but also on the orbital angular momentum of the valence neutrons. A n ew definition for the thickness of pure-neutron-matter is proposed. Particl es in classically forbidden area are also studied. The number of neutrons i n the classically forbidden area increases with mass number A, because of t he increase in the number of neutrons occupied in the weaklybound open shel l. The number of protons in the classically forbidden area, in contrast, de creases with mass number A, because the orbits of protons become more deepl y bound. It is shown that the number of particles in the classically forbid den area can give information on the appearance of the halo or skin.