Evidence for the giant monopole resonance inPb208from strong energy dependence inαscattering

Abstract
The giant-resonance region of Pb208 was studied using α beams of energies between 100 and 172 MeV. Relative to the excitation of the giant quadrupole resonance located at Ex=10.9 MeV the new resonance at Ex=13.8 MeV was found to be more strongly excited at higher incident energies. This yields a new piece of evidence for the monopole character of this new resonance.