Quasi-free scattering with 6,8He beams.

This paper presents the results of experimental investigations of (p,pn), (p,pα) and (p,p 6He) reactions with relativistic 6He and 8He beams impinging on a hydrogen target. Information on the structure of extremely neutron-rich nuclei was obtained by using the unique characteristic of quasi-free scattering processes and inverse kinematics. For the first time, momentum distributions of complex clusters inside 6He and 8He were measured. Spectroscopic factors for valence neutrons, α- and 6He clusters were deduced from the experimental data. They demonstrate that the filling of the p½ shell is the essential feature of the 8He structure. It is shown that the 8He cluster structure can be considered as a 6He core plus two valence neutrons. [Copyright &y& Elsevier]