Coulomb excitation of the giant dipole resonance in light-ion inelastic scattering fromPb208

Abstract

A coupled-channel calculation including Coulomb excitation has been done for excitation of the isovector giant dipole resonance in light-ion inelastic scattering from $^{208}\mathrm{Pb}$ at forward angles. It is found that the predicted cross sections for excitation of the giant dipole resonance with alpha inelastic scattering, calculated including Coulomb excitation, are much smaller than the experimental isoscalar giant monopole resonance cross section at incident energies around 100 MeV. The predicted cross section for Coulomb excitation of the giant dipole resonance increases rapidly with increasing incident energy, and the giant dipole and monopole resonance cross sections become comparable above ${E}_{\ensuremath{\alpha}}=300$ MeV. For inelastic scattering of $^{3}\mathrm{He}$, deuterons, and protons at forward angles, Coulomb excitation of the giant dipole resonance is found to be comparable to the giant monopole resonance cross section at $100l{E}^{\mathrm{lab}}l200$ MeV. Coulomb excitation of the giant dipole resonance is strongly inhibited by momentum mismatch between incident and outgoing waves due to the large negative $Q$ values. This mismatch is reduced for lighter projectile masses and higher incident energies. As the giant monopole and dipole resonances are almost coincident, giant dipole resonance excitation must be properly accounted for in studies of the giant monopole resonance.NUCLEAR REACTIONS Coupled-channel calculation of $\ensuremath{\sigma}(\ensuremath{\theta})$; for Coulomb excitation of isovector dipole resonance in $^{208}\mathrm{Pb}$; from ($\ensuremath{\alpha}$,${\ensuremath{\alpha}}^{\ensuremath{'}}$), ($^{3}\mathrm{He}$, $^{3}\mathrm{He}$'), ($d$,${d}^{\ensuremath{'}}$), and ($p$,${p}^{\ensuremath{'}}$) scattering.