Monopole Excitation in the Giant-Resonance Region ofPb208

Abstract

Inelastic scattering of 45-MeV protons and 70-MeV ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ particles has been used to study the giant-resonance region of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. The giant resonance is found to be highly structured with states of different multipolarities, such as dipole, quadrupole, and octupole. A monopole state is found at 9.11 MeV which exhausts about 2% of the monopole-sum-rule strength.