FRAGMENT ANGULAR-DISTRIBUTION AS A PROBE OF FISSION DYNAMICS IN NUCLEI WITH 2 CLASSES OF EXCITED-STATES

The fragment angular distribution from the multichance fission of exci ted nuclei with a double humped fission barrier is considered. It is s hown that the fragment angular distribution is determined by contribut ions related to both the saddle points. The relative weights of these contributions are calculated in the framework of the diffusion model. The possibility of determining the nuclear dissipation is discussed. A comparison of the experimental data with the calculations leads to a value of the reduced dissipation coefficient beta = (0.2-0.5) x 10(21) s(-1) for the Pu isotopes produced in the U-238 + alpha reaction at E (alpha) = 37 and 43 MeV.