FISSION DYNAMICS USING THE DECAY OF THE GIANT-DIPOLE RESONANCE

High-energy gamma-rays from the decay of the giant dipole resonance bu ilt on excited states were measured in coincidence with fission for th e S-32 + W-nat, Pb-208 reactions. Both the gamma-ray multiplicity and the gamma-fission angular correlation were determined; the latter quan tity is sensitive to the deformation of the fissioning nucleus. This s ensitivity has been used in order to estimate the breakdown of dynamic al fission time tau(f) into its pre- tau(pre) and post-saddle tau(post ) components. A statistical model analysis, using a version of CASCADE modified to include pre- and post-saddle delay times in order to simu late the effects of dynamics, can reproduce the data with tau(pre)appr oximate to 10x10(-21) s and t(post)approximate to 20x10(-21) s for a d ynamical fission time tau(f) approximate to 30x10(-21).