CLUSTERING ASPECTS OF LIGHT EXOTIC NUCLEI

The discovery of light nuclei with neutron halos has opened new perspe ctives for nuclear structure and a possibility to study genuine few-bo dy aspects of matter. A number of borromean systems where the system i s bound but where no binary subsystems are bound, are realized by natu re in the context of nuclei, Li-11 being the nucleus which has had mos t recent attention. Although a large number of calculations have addre ssed the detailed structure of the Li-11 neutron halo, no single model has yet explained all the data presently available. This is in part d ue to uncertainties in the n+Li-9 interaction. For He-6, also a borrom ean system, where the n + core interaction is known, the best three-bo dy and reaction models succeed in reproducing the data. In the Li-11 c ase, a major uncertainty concerns the effect of possible Is intruder s tates.