Nuclear viscosity of hot rotating Th-224 - art. no. 024613

In a detailed investigation of giant dipole resonance (GDR) gamma-ray yield from the O-16+Pb-208 system, the absolute gamma-ray/fission multiplicities are extracted and reported over a wide range of excitation energy and angu lar momentum. The enhanced yield of GDR decay gamma rays from the compound system has been analyzed within the framework of a modified statistical mod el containing the nuclear viscosity as a foe parameter. The nuclear viscosi ty parameter gamma has been studied over a much wider range of excitation e nergy and angular momentum than in earlier works. The measured gamma-ray mu ltiplicities as well as known neutron multiplicities and evaporation residu e cross sections indicate a strongly damped fission motion. The systematics of the extracted dissipation coefficient is fitted equally well with eithe r temperature or a deformation-dependent nuclear viscosity.