Important Influence of Entrance Channel Reorientation Coupling on Proton Stripping

While it is well established that the ground state reorientation coupling can have a significant influence on the elastic scattering of deformed nuclei, the effect of such couplings on transfer channels has been much less well investigated. In this letter we demonstrate that the ${}^{208}$Pb(${}^7$Li,${}^6$He)${}^{209}$Bi proton stripping reaction at an incident energy of 52 MeV can be well described by the inclusion of the ${}^7$Li ground state reorientation coupling within the coupled channels Born approximation formalism. Full finite-range distorted wave Born approximation calculations were previously found to be unable to describe these data. Addition of coupling to the 0.478-MeV 1/2${}^{\text{â}}\text{ˆ}\text{’}$ excited state of ${}^7$Li, together with the associated two-step transfer path, has little or no influence on the shape of the angular distributions (except that for stripping leading to the 1.61-MeV 13/2${}^{+}$ level of ${}^{209}$Bi which is significantly improved) but does affect appreciably the values of the ${}^{209}$Bi→${}^{208}$Pb+p spectroscopic factors. Implications for experiments with weakly-bound light radioactive beams are discussed.