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A comprehensive study of the evolution of the GDR properties from E* = 150 MeV to E* = 430 MeV has been undertaken in nuclei of mass A = 120 = 132. The experimental investigation was performed using MEDEA detector. An onset of a quenching of the GDR gamma yield was found at E* = 270 MeV comparing the experimental gamma-ray spectrum with statistical model calculation. The quenching effect increases at E* = 330 MeV and is even more pronounced when the analysis is extended to higher excitation energies using data from previously performed experiments. The comparison with phenomenological models describing the quenching phenomenon gives a qualitative explanation for the effect but is not able to reproduce its detailed features as a function of excitation energy. A smooth cut-off approach describes reasonably well the progressive disappearance of the dipole strength, which occurs around 220-230 MeV excitation energy, and shows that the GDR quenching is a rather sharp effect. [ABSTRACT FROM AUTHOR]

Symmetric and asymmetric aligned breakup of projectile-like fragments in 197Au + 197Au collisions at 23AMeV was studied. Independently of the asymmetry, the reaction yields have been found peaked at a common, very narrow range of impact parameters. [ABSTRACT FROM AUTHOR]

197Au+197Au collisions at 15 MeV/nucleon were studied using the multidetector array CHIMERA and heavy ion beams from the superconducting cyclotron of LNS Catania. The experiment was aimed at studying the mechanism of energy dissipation in collisions of very heavy systems. In the present contribution we report on a part of our study concentrated on a subject of basically binary damped collisions, in which only two main fragments are formed prior to secondary deexcitation processes. Such "binary" events were selected by using complete information from the exclusive-type data (including all Z ≥ 3 fragments) obtained with the CHIMERA multidetector. Results are compared with predictions of a classical dynamical model of Blocki et al., in which both scenarios of energy dissipation, one-body or two-body dissipation mechanisms, are assumed. [ABSTRACT FROM AUTHOR]