Optical model and coupled-channels analysis ofLi7+Si28andLi7+Ca40scattering

Abstract

Angular distributions for elastic scattering and for excitation of the 1.78 MeV state in $^{28}\mathrm{Si}$ and for elastic scattering and excitation of the 3.73 and 3.90 states in $^{40}\mathrm{Ca}$ by $^{7}\mathrm{Li}$ scattering at a bombarding energy of 45 MeV have been measured and analyzed. Double folding model calculations using a realistic effective nucleon-nucleon interaction similar to that performed for $^{9}\mathrm{Be}$ + $^{28}\mathrm{Si}$ and $^{9}\mathrm{Be}$ + $^{40}\mathrm{Ca}$ scattering have been carried out for the elastic angular distributions and the real potential must be renormalized to yield agreement with the measured cross sections. Coupled channels calculations using a Woods-Saxon potential were performed in an effort to describe the inelastic angular distributions. The extracted deformation parameters are in reasonable agreement with those obtained from light and heavier ion scattering from the same target nuclei. The effect of strong excitation of the 0.48 MeV state in $^{7}\mathrm{Li}$ and of mutual excitation of target and projectile is considered in a qualitative manner.NUCLEAR REACTIONS $^{28}\mathrm{Si}$($^{7}\mathrm{Li}$, $^{7}\mathrm{Li}$)$^{28}\mathrm{Si}$, $^{28}\mathrm{Si}$($^{7}\mathrm{Li}$, $^{7}\mathrm{Li}$*)$^{28}\mathrm{Si}$* $Q=\ensuremath{-}0.48, \ensuremath{-}1.78, \mathrm{and} \ensuremath{-}2.26$ MeV, $E(^{7}\mathrm{Li})=45$ MeV; $^{40}\mathrm{Ca}$ ($^{7}\mathrm{Li}$, $^{7}\mathrm{Li}$)$^{40}\mathrm{Ca}$, $^{40}\mathrm{Ca}$($^{7}\mathrm{Li}$, $^{7}\mathrm{Li}$*)$^{40}\mathrm{Ca}$* $Q=\ensuremath{-}0.48, \ensuremath{-}3.73, \mathrm{and} \ensuremath{-}3.90$ MeV, $E(^{7}\mathrm{Li})=45$ MeV; measured $\ensuremath{\sigma}(\ensuremath{\theta})$, ${\ensuremath{\theta}}_{\mathrm{lab}}=10\ensuremath{-}70\ifmmode^\circ\else\textdegree\fi{}$;; performed optical model calculations using Woods-Saxon potential and double folding procedure, deduced optical model parameters; performed coupled-channels calculations, deduced deformation parameters.