Isospin transport phenomena in nuclear reactions in the Fermi energy range

This thesis work has been done within the NUCL-EX group of the INFN group II. The work has consisted of the preparation and the first measurement of the coupled apparatus INDRA-FAZIA, in the identification of data obtained in the previous measurement with FAZIA and in the analysis of data that were already calibrated in a precedent measurement with INDRA coupled with the spectrometer VAMOS. The FAZIA apparatus was built with a collaboration that involves more than 10 institutions in six different countries. A long phase of research and development was necessary to obtain what today can be considered one of the best apparatus for measurements of charged particles emitted in nuclear reactions. The measurement made with INDRA-VAMOS was analyzed in order to verify the isospin effects (N/Z content) in peripheral and semi-peripheral reactions Ca(40,48)+Ca(40,48) at 35 MeV/u. In these collisions, the transport models predict the formation of a low-density neck between two hot fragments kinematically similar to the projectile (PLF) and target (TLF). The isotopic identification of PLF provided by VAMOS, together with those of light charged particles (LCP) revealed in coincidence with INDRA allow, through their correlation, to reconstruct the primary fragment. During the reconstruction phase, the mass number (A) is made without the emitted neutron contribution, because these are not detected. To estimate the excitation of the source is necessary to make some assumption about the evaporated neutrons, to obtain the most realistic estimate. Finally, in order to extrapolate information about the energy symmetry term of the Nuclear Equation of State, it is shown the study of the width of isotopic distributions. The preliminary result obtained is the trend of the symmetry energy coefficient (Csym) as a function of the charge of the reconstructed primary fragment, which is dependent on the surface term, present in the liquid drop model of the nucleus.