Nuclear densities in the neutron-halo region

Loosely bound Exotic Nuclei in the neutron-halo region have very small neutron/proton separation energy implying a long tail of the last loosely bound nucleon. An accurate treatment of this tail is crucial for the description of several reaction observables. We propose, for such loosely bound Exotic Nuclei, a simple analytic expression for nucleon densities which incorporates correctly two basic physical requirements: a) The asymptotic behavior (r --> infinity). b) The behavior near the center (r --> 0). The expression provides, separately, the neutron and proton densities and is suitable for the description of Exotic Nuclei in the neutron-halo region. In addition it provides a simple physical insight into the density in the outer (halo) region. Glauber type calculations for reaction cross-sections, using these densities have been carried out for such nuclei. The calculated cross-sections are found to be consistent with the experimental values. The calculated densities are in good agreement with the corresponding so-called experimentally deduced densities (where available) indicating the reliability of the proposed model densities