Deformation properties of drip-line nuclei

Deformation properties of weakly bound drip-line nuclei are discussed in the de-formed single-particle model and, in particular, those of the drip-line sulfur isotopes are investigated in the framework of the self-consistent mean-field theory. In the deformed single-particle model, it is demonstrated that in the limit of very small binding energy the valence particles in specific orbitals, characterized by a very small projection of single-particle angular momentum onto the symmetry axis of a nucleus, can give rise to the halo structure which is completely decoupled from the rest of the system. The quadrupole deformation of the resulting halo is com-pletely determined by the intrinsic structure of a weakly bound orbital, irrespective of the shape of the core. Similarly, the self-consistent mean-field calculations show large differences between the proton and neutron quadrupole deformations in the drip-line sulfur isotopes, which can be understood in terms of the significant radial contribution to the quadrupole moment in such spatially extended systems.