Coupled reaction channel analysis of elastic, inelastic, transfer, and fusion cross sections for ¹²C+²⁰⁸Pb

Abstract

Elastic, inelastic, and transfer angular distributions were measured for ¹²C+²⁰⁸Pb in the energy range from 58.9 to 84.9 MeV. While the fission fragment angular distributions were measured over the energy range from 58.9 to 79 MeV, the residue cross sections after 2n evaporation from the compound nucleus (²²⁰Ra) were measured by a counting at 58.9, 60.9, and 62.9 MeV. Combining the above data with the ones from the literature, the fusion cross sections have been obtained. Quasielastic excitation function at 170° was also measured to obtain the fusion barrier distribution. Optical model analysis of the elastic scattering data, using both phenomenological and microscopic models, brought out the pronounced energy dependence of the optical potential at near barrier energies. A simultaneous description of the elastic and all the nonelastic channels was obtained from the coupled reaction channel (CRC) calculations using a consistent set of parameters at all the energies. The effective nucleus-nucleus real potential, obtained from CRC calculations, explained the observed energy dependence of the real part of the optical potential. Thus, the real potential used in these calculations with such a large number of constraints can be considered as the bare nucleus-nucleus potential.