Dynamic polarization potentials and dipole polarizabilities of11Li,6He and6Li compared

Abstract

Elastic scattering data for ${}^{11}$Li, ${}^{6}$Li, and ${}^{6}$He $+$ ${}^{208}$Pb at incident energies of 29.8 MeV, 29 MeV, and 18 MeV, respectively, were analyzed by means of coupled discretized continuum channels (CDCC) calculations. Dynamic polarization potentials (DPPs) of the trivially equivalent local potential (TELP) type were derived from these calculations and compared. The dipole polarizability factor $\ensuremath{\alpha}$ for ${}^{11}$Li obtained by fitting a Coulomb polarization potential to the long-range part of the real DPP is consistent with the theoretical value of $5.7$ fm${}^{3}$. These results point to the dineutron model providing a very good description of ${}^{11}$Li breakup coupling effects. The much larger Coulomb dipole polarizability of ${}^{11}$Li suggests the persistence of large deviations from Rutherford scattering at sub-barrier energies for medium mass targets, a prediction confirmed by CDCC calculations.