EVIDENCE OF DOUBLE PHONON EXCITATIONS IN THE FUSION OF O-16-208(PB)

The fusion cross-sections for O-16 + Pb-208, measured to high precisio n, enable the extraction of the distribution of fusion barriers. This shows a structure markedly different from the single barrier which mig ht be expected for fusion of two doubly-closed shell nuclei. The resul ts of exact coupled-channel calculations performed to understand the o bservations are presented. These calculations indicate that coupling t o a double octupole phonon excited state in Pb-208 is necessary to exp lain the experimental barrier distributions.