Quasielastic scattering of 9Li on 12C.

In a previous experiment @1#, we investigated the quasielastic scattering of the exotic ‘‘two-neutron halo’’ nucleus Li from a C target. Subsequent theoretical calculations @2# of this scattering process using a four-body Glauber model confirmed, in principle, that a measurement of the elastic-scattering angular distribution can provide a useful indicator of the nature of the Li ground state. These calculations clearly showed that the elastic-scattering data are sensitive to the assumed structure of the Li wave function and that the effects are significant. Unfortunately, there are ~at least! two problems that occur in attempts to validate this result by comparison with the existing experimental data. First of all, the Glauber-model calculations were shown to be highly sensitive to the core-target ~i.e., LiC! interaction, and there exists no independent determination of the Li 1 C optical-model potential parameters. Thus, it was necessary to rely on extrapolations from elastic-scattering data obtained for nuclei of similar mass. In view of the strong sensitivity of the model to the core-target interaction ~see Ref. @2#, for example!, this procedure is suspect. The second problem that occurs in comparing elasticscattering calculations with existing data is the inability of the experimental technique to resolve inelastic scattering to low-lying states of C, so that the data of Ref. @1# are actually for quasielastic scattering. In the Li 1 C experiment inelastic excitation of Li does not pose a problem, since there are no particle-stable excited states in this nucleus and the Li projectile was detected and identified. In the Li 1 C experiment, however, contributions due to inelastic excitation of the projectile do need to be considered. The excitation of the C target was dealt with in Refs. @1# and @2# by calculating the inelastic contributions in either a coupled-