Interaction distances for weakly bound nuclei at near barrier energies

Interaction distances were estimated for the weakly bound systems $^{6}\mathrm{Li}$ and $^{7}\mathrm{Li}$, from elastic scattering data, as a function of energy in the vicinity of the barrier and as a function of target mass number. For comparison purposes, such distances were also estimated for some stable systems. It was found that interaction distances vary appreciably between stable and weakly bound projectiles while depending strongly on target mass number. The implications to calculations of the potential in the vicinity of the barrier are discussed.