Presaddle and postsaddle dissipative effects in fission using complete kinematics measurements

International audience; A complete kinematics measurement of the two fission fragments was used for the first time to investigatefission dynamics at small and large deformations. Fissioning systems with high excitation energies, compactshapes, and low angular momenta were produced in inverse kinematics by using spallation reactions of leadprojectiles. A new generation experimental setup allowed for the first full and unambiguous identification inmass and atomic number of both fission fragments. This measurement permitted us to accurately determinefission cross sections, the charge distribution, and the neutron excess of the fission fragments as a function of theatomic number of the fissioning system. These data are compared with different model calculations to extractinformation on the value of the dissipation parameter at small and large deformations. The present results do notshow any sizable dependence of the nuclear dissipation parameter on temperature or deformation.