Search

The systems of intermediate fissility 132Ce and 158Er have been studied experimentally and theoretically in order to investigate the dissipation properties of nuclear matter. Cross sections of fusion-fission and evaporation residues channels together with charged particles multiplicities in both channels, their spectra, angular correlations and mass-energy distribution of fission fragments have been measured. Theoretical analysis has been performed using multi-dimensional stochastic approach with realistic treatment of particle evaporation. The results of analysis show that full one-body or unusually strong two-body dissipation allows to reproduce experimental data. No temperature dependent dissipation was needed.

Studies on the isospin dependence of the level density have been recently reported in the literature for nuclei with 20 ≤ A ≤ 110. Corrections to the level density have been deduced which would imply a significant reduction of this quantity for nuclei far from the valley of stability. Isospin effects on the level density are also expected through the symmetry energy contribution to the nuclear masses, which is predicted to increase with the temperature. According to these findings, we have implemented the statistical model in order to account for isospin effects on the level density parameter a and on the temperature-dependent symmetry energy. We present the results of calculations for the decay of a variety of neutron-rich composite systems. We found that isospin produces sizable eïňĂects on difierent observables, this result being promising for future experiments with the second generation RIB facilities SPES and SPIRAL2. We report the results of a first experiment aimed at searching for isospin effects in the decay of 139 Eu composite nuclei produced by a stable beam at E x =90 MeV.