Electroexcitation of Giant Multipole Resonances inAu197andPb208between 5 and 40 MeV Excitation Energy with 90-MeV Electrons

Abstract

Inelastic electron scattering with 90-MeV electrons shows previously observed giant resonances at excitation energies of $63A^{-\frac{1}{3}}$ ($E2\mathrm{}$), $81A^{-\frac{1}{3}}$ ($E1\mathrm{}$), $105A^{-\frac{1}{3}}$ ($E3\mathrm{}$), and $130A^{-\frac{1}{3}}$ MeV ($E2\mathrm{}$). Distorted-wave-Born-approximation analysis of additional structure at $53A^{-\frac{1}{3}}$ and $195A^{-\frac{1}{3}}$ MeV suggests a monopole assignment. Transverse contributions to the $E1\mathrm{}$ matrix element are compatible with an electric spin-flip. Differing widths of the respective resonances in the two nuclei are explained through dynamic deformation of Au. The reduced electric transition strengths $B\left(\mathrm{EL}\right)\mathrm{}$ are given.