Discovery of collective states in 208Pb by complete spectroscopy

Most neutron and proton bound states in 208Pb are described in the shell model as one-particle onehole configurations. Besides precise data obtained with the Q3D magnetic spectrograph of the MLL (Garching, Germany) an important reaction is the inelastic proton scattering via isobaric analog resonances in 209Bi. It yields amplitudes of neutron one-particle one-hole configurations with relative signs in each stateof 208Pb. The orthogonality, normality, and sum rule relations allow to investigate the completeness of the transformation matrices of one-particle one-hole configurations describing the states in 208Pb with spins from 0− to 14− and 0+ to 12+. By this method amplitudes of unobservable one-particle one-hole configurations can be determined.The comparison of spin, parity, and dominant particle-hole components thus derived in up to 30 states of a certain spin to shell model calculations allows to identify states described as collective excitations of the entire nucleus.