Low-lying Dipole Strength Distribution Inpb204

Dipole and quadrupole strength distribution of 204Pb was investigated via a nuclear resonance fluorescence experiment using bremsstrahlung produced using an electron beam at a kinetic energy of 10.5 MeV at the linear accelerator ELBE. We identified 136 states resonantly excited at energies from 3.6 to 8.4 MeV. Spins of the excited states were deduced by angular distribution ratios of gamma rays observed at scattering angles of 90 degrees and 127 degrees with respect to the incident gamma beam. The analysis of the measured gamma-ray spectra includes the quasicontinuum of levels at high energy. Monte Carlo simulation of gamma-ray cascades were performed to obtain the intensities of inelastic transitions and branching ratios of the ground-state transitions. The present experimental results were used to investigate the electric dipole (E 1) strengths by comparison with predictions from the quasiparticle-phonon model with the self-consistent energy density functional.