PROTON ELASTIC-SCATTERING WITH LI-9 AND LI-11 AND ITS HALO STRUCTURE

We have studied the proton elastic scattering of Li-9 and Li-11 using the Born approximation and the optical potential approach. We first studied the data qualitatively by the Born approximation and found that the small cross section of p+Li-11, which had been observed at E(p) = 62 MeV, can be understood as the break-up effect of halo neutrons from Li-11. We then searched for the optical potential parameters for both p+Li-9 and p+Li-11 under the assumption that Li-11 has a halo structure of two weakly bound neutrons around the Li-9 core. We found a good parameter set and concluded that the break-up effect of halo neutrons is essential to understand the p+Li-11 data.