Different continuum approaches to giant resonances in 208Pb with 400-MeV protons.

Abstract

New $^{208}\mathrm{Pb}$(p,p') measurements at 400 MeV are reported and analyzed using new approaches to the continuum in the giant resonance region. These approaches include a phenomenological procedure, and calculations based on the free surface response function of semi-infinite nuclear matter. These methods are found to lead to giant resonance parameters which are consistent and in agreement with established results. We interpret this to mean that both approaches provide empirically consistent representations of the continuum underlying the giant resonances. In addition to the well-known resonances, evidence of possible 3\ensuremath{\Elzxh}\ensuremath{\omega} L=5 resonance strength is observed at 18-MeV excitation accounting for 10\ifmmode\pm\else\textpm\fi{}3 % of the energy-weighted sum rule.