Hadronic excitation of the giant resonance region of 208Pb

Abstract

Calculations have been made of the inelastic spectra leaving 208Pb with excitation energies in the giant resonance region (≈ 9 to 15 MeV) following the inelastic scattering of 60 MeV protons and 115 MeV alphas. Particle-hole wave functions obtained in the RPA were used, together with an effective interaction between the projectile and each target nucleon. A “giant resonance” peak is predicted with excitation energy and strength similar to those observed. While the predominant multipole is quadrupole, considerable L = 4 and some L = 0 and L = 6 strength is concentrated in the same region. Because of this, the angular distributions are smoothed out. The use of the collective model to describe these excitations is discussed. The electric transition strengths B(E L) and the inelastic cross sections are contrasted and the use of multipole sum rules is criticized.