HEAVY-ION EXCITATION OF ONE-PHONON AND 2-PHONON GIANT-DIPOLE STATES AS AN EXIT DOORWAY PHENOMENON

We develop a detailed theory for mutiphonon excitation in heavy-ion co llisions. This theory fully accounts for the effects of the finite lif etimes of the states involved and allows the treatement of both format ion and decay of multiphonon states through explicit consideration of spreading and escape widths. A schematic model is used to study the in fluence of the widths on the formation cross sections. We find that th e finite width of the one-phonon resonance leads to a decrease in the two-phonon state cross section.