An optical model analysis of the quasielastic scattering of ${}_{}{}^{12}{}_{}{}^{}\mathrm{Be}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{Be}$ on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ target nuclei has been performed, for measurements at 679 and 796 MeV laboratory incident energy, respectively. The data are from the group of the University of Notre Dame. The automatic searches on the optical model parameters were constrained by fitting the total reaction cross sections to values extrapolated from measurements performed at much higher incident energy. It has turned out for both projectiles that a surface term is necessary for the real as well as for the imaginary part of the potential, in order to reproduce correctly the experimental data. This diffractive-refractive behavior favors the existence of a neutron halo for both projectiles.

• Received 25 April 1994

DOI:https://doi.org/10.1103/PhysRevC.50.2620