Angular distributions of the ${}^{208}\mathrm{Pb}$(${}^7\mathrm{Li}$,${}^6\mathrm{He}$)${}^{209}\mathrm{Bi}$ reactions with one-proton transferred to the ground, first-excited, and second-excited states of ${}^{209}\mathrm{Bi}$ were measured at $E_{\mathrm{lab}}=25.67$, 28.55, 32.55, 37.55, and 42.55 MeV. The experimental data and the data available in the literature at $E_{\mathrm{lab}}=52$ MeV were analyzed within the theoretical framework of the distorted wave Born approximation and coupled reaction channels, respectively. The optical model potentials for the exotic system ${}^6\text{He}+{}^{209}$Bi, which is the exit channel of the reaction studied, have been extracted by means of fitting the angular distributions of transfer reactions. In the analyses, interaction potentials of the entrance channel ${}^7\text{Li}+{}^{208}\text{Pb}$ were derived from the elastic scattering data. For the ${}^6\text{He}+{}^{209}$Bi system, the phenomenon of the so-called breakup threshold anomaly was observed. Furthermore, the angular distributions of elastic scattering and total reaction cross sections by direct measurement for the ${}^6\text{He}+{}^{209}$Bi system in the energy region near and above the Coulomb barrier can be satisfactorily reproduced by employing the potentials extracted through the transfer reactions.

• Received 15 January 2014
• Revised 20 March 2014

DOI:https://doi.org/10.1103/PhysRevC.89.044615