Production and de-excitation modes of hot nuclei in the 84Kr + 12C, 84Kr + 27Al, 84Kr + Nat Ti reactions at 26.4, 34.4 and 45.4 MeV/nucleon

The inclusive characteristics of nuclear fragments, of mass greater than 10 uma, from KR + C, Al and Ti reactions at 25, 35 and 45 MeV/u, are investigated. The inverse kinematic method is applied. The analysis of velocity and fragment (mass < 40 uma) spatial distribution show a stable source emission component. Monte Carlo calculations confirm these results, except in the case of Kr + Al and Ti at 45.4 MeV/nucleon. Moreover, part of the events come from non-equilibrium or dissipative processes. For the Kr + C reaction at 25 and 35 MeV/u total fusion, which corresponds to 0.1 of the evaporation croks section. In the other cases, incomplete transfer momentum, higher than the one for evaporation, is observed. Complex nuclear fragment yield determines the reaction hotest nuclei. The source velocities, associated to the evaporation residues and to the complex fragments becomes lower as a function of the system's symmetry. For the Kr + C system, the calculated and experimental data of the source velocity and the mass of evaporation residues are in good agreement. These parameters are overestimated for Ti target. The calculated maximal excitation energies increase as a function of the available energy, reaching 5.8 MeV/u. The complex fragment production cross sections increase with the target's mass. As the available energy increases, the ratio between the production of evaporation residues and complex fragments diminishes. A statistical de-excitation model, which takes into account complex fragment emissions, is applied. The excitation energy remains inferior to 4.2 MeV/nucleon and to the value of the mass transfer hypothesis