Thermal and dynamical properties of fusion-fission and fusion-evaporation processes in 20Ne + 159Tb and 20Ne + 169Tm reactions between 8 and 16 MeV/nucleon

Abstract

We have undertaken a study of the thermal and the dynamical properties of fission and evaporation processes through the observation of neutron and light charged particle (LCP) emission (p, α) in collisions of 20 Ne + 159 Tb and 20 Ne + 169 Tm at 8, 10, 13 and 16 MeV/nucleon using the neutron multidetector DEMON. Both systems lead to the formation of compound nuclei (CN) with initial excitation energies ( E x * ) ranging between 100 and 250 MeV. These CN, formed through complete (CF) or incomplete (IF) fusion reactions, decay through either fission or evaporation residue (ER) formation. Our experimental goal in this study is to establish, as a function of E x * , i) σ ER /σ fission cross-section ratios, ii) pre- and post-scission neutron and LCP multiplicities with a clear cut assignment to CF and IF processes and iii) to try to consistently interpret these data in the framework of the recently modified statistical code GEMINI, including time-dependent fission width probabilities in order to establish the fission time scales.