Dynamical aspects of heavy-ion collisions

Two independent studies on heavy-ion collisions are presented. In the first part, the charge and mass of the projectile-like fragments produced in the 15-MeV per nucleon {dollar}sp{lcub}40{rcub}Ca+sp{lcub}209{rcub}{dollar} Bi reaction were determined for products detected near the grazing angle. Neutron number-charge ({dollar}N-Z){dollar} distributions were generated as a function of the total kinetic energy loss and parameterized by their centroids, variances and correlation coefficients. After the interaction, a drift of the charge and mass centroids towards asymmetry is observed. The production of projectile-like fragments is consistent with a tendency of the projectile-like fragments to retain the projectile neutron-to-proton ratio {dollar} / {dollar} = 1. The correlation coefficient remains well below 1.0 for the entire range of total kinetic energy lost. Predictions of two nucleon exchange models, Randrup's and Tassan-Got's, are compared to the experimental results. The models are not able to reproduce the evolution of the experimental distributions, especially the fact that the variances reach a maximum and then decrease as function of the energy loss. This behavior supports the hypothesis that some form of projectile-like fragmentation or cluster emission is perturbing the product distribution from that expected from a damped mechanism.; In the second part of the thesis a clustering model that allows the recognition of mass fragments from dynamical simulations has been developed. Studying the evolution of a microscopic computation based on the nuclear-Boltzman transport equation, a suitable time is chosen to identify the bound clusters. At this time the number of binding surfaces for each test nucleon is found. Based on the number of nucleon bindings the interior nucleons are identified, and the cluster kernels are formed. An iterative routine is then applied to determine the coalescence of the surrounding free nucleons. Once the fragment formation has been established, a statistical decay code is used to determine the final fragment distributions. Applications are given for the two systems, {dollar}sp{lcub}139{rcub}La{dollar} on {dollar}sp{lcub}27{rcub}Al{dollar} and {dollar}sp{lcub}nat{rcub}Cu{dollar} 45 Mev/u, and model predictions are then compared to experimental data. An overall agreement of the calculations with the experiment is found.