Structure of Two-Neutron Halo in Light Exotic Nuclei

Structure of two-neutron halo in light exotic nuclei is studied by a three-body model using the neutron–neutron interaction fixed at the low-energy scattering limit. The model is applied to the dripline nucleus 22 C assuming a pure s-wave halo with “correlated” 20 C-core, and a unique relation between two-neutron separation energy and halo radius is derived. It is also applied to 29 F, where 2 p 3 / 2 -orbit is shown to be important for forming the halo. The estimated halo radii in 22 C and 29 F are found to be consistent with the recent experimental data. The halos in 17 B and 19 B are analyzed by the three-body model with mixed configurations of 2 s 1 / 2 2 and 1 d 5 / 2 2 . The dominance of the d-orbit is found in 17 B, while the s-orbit component is found to be about 40 % in 19 B.