TESTS OF NUCLEAR FRICTION IN SADDLE-TO-SCISSION MOTION OF FISSIONING NUCLEI

A selected set of precise measurements of the mean kinetic energy of f ission fragments has been used for testing nuclear dissipation. Calcul ations of the kinetic energy release on the descent from saddle to sci ssion have been done with a dynamical model based on the classical Ray leigh-Lagrange equations of motion. Both alternative dissipation mecha nisms, one-body dissipation and two-body viscosity have been tested. A n increasing strength of the dissipation with increasing mass of a com posite system has been observed. However this effect may partly result from a specific shape parametrization used in the dynamical model.