Probing The He-8 Ground State Via The He-8(P, T)He-6 Reaction

The weakly-bound He-8 nucleus exhibits a neutron halo or thick neutron skin and is generally considered to have an alpha + 4n structure in its ground state, with the four valence neutrons each occupying 1p(3/2) states outside the alpha core. The He-8(p, t)He-6 reaction is a sensitive probe of the ground state structure of He-8, and we present a consistent analysis of new and existing data for this reaction at incident energies of 15.7 and 61.3 A MeV, respectively. Our results are incompatible with the usual assumption of a pure (1p(3/2))(4) structure and suggest that other configurations such as (1p(3/2))(2) (1p(1/2))(2) may be present with significant probability in the ground state wave function of He-8. (c) 2007 Elsevier B.V. All rights reserved.