Low-energy Li 11 +p and Li 11 +d scattering in a multicluster model

The Li11+p and Li11+d reactions are investigated in the continuum discretized coupled channel (CDCC) method with a three-body description (Li9+n+n) of Li11. I first discuss the properties of Li11, and focus on E1 transition probabilities to the continuum. The existence of a 1- resonance at low excitation energies is confirmed, but the associated E1 transition from the ground state does not have an isoscalar character, as suggested in a recent experiment. In a second step, I study the Li11+p elastic cross section at Elab=66 MeV in the CDCC framework. I obtain a fair agreement with experiment, and show that breakup effects are maximal at large angles. The breakup cross section is shown to be dominated by the 1- dipole state in Li11, but the role of this resonance is minor in elastic scattering. From CDCC equivalent Li11+p and Li11+n potentials, I explore the Li11+d cross section within a standard three-body Li11+(p+n) model. At small angles, the experimental cross section is close to the Rutherford scattering cross section, which is not supported by the CDCC. A five-body (Li9+n+n)+(p+n) calculation is then performed. Including breakup states in Li11 and in the deuteron represents a numerical challenge for theory, owing to the large number of channels. Although a full convergence could not be reached, the CDCC model tends to overestimate the data at small angles. I suggest that measurements of the Li9+p elastic scattering would be helpful to determine more accurate optical potentials. The current disagreement between experiment and theory on Li11+d scattering also deserves new experiments at other energies.
SCOPUS: ar.j
info:eu-repo/semantics/published