CLOSED-FORM EXPRESSIONS FOR CROSS-SECTIONS OF EXOTIC NUCLEI

We study p+Li-11 cross sections, in the intermediate-energy region, wi th the nucleus characterized by a halo structure. The eikonal approxim ation and ''trho'' optical potential are used to get an intuitive pict ure of the reaction mechanism. By using gaussian nucleon densities for Li-11, Li-9 and the halo, we obtain similar expressions for the total nuclear reaction and two-neutron removal cross section in the Glauber approximation. Closed-form analytical expressions for those cross sec tions are derived. By comparing the results with the exact ones, we ca n conclude that we have derived a fair approximation to them. We also estimate the ''in-medium'' Pauli-blocking effect on the cross sections .