Study and comparison of the decay modes of the systems formed in the reactions $^{78}$Kr+$^{40}$Ca and $^{86}$Kr+$^{48}$Ca at 10 AMeV

The first results of the ISODEC experiment, performed at the INFN-Laboratori Nazionali del Sud (LNS) by using the CHIMERA detector, will be presented. The principal aims of this experiment is to study the competition between the various disintegration modes of 118,134Ba compound nuclei produced in the reactions 78Kr+40Ca and 86Kr+48Ca at 10 AMeV, exploring the isospin dependence of the decay modes of medium mass compound nuclei formed by fusion processes. The experiment complements data already obtained at 5.5 MeV/A for 78,82Kr+40Ca reactions [1], previously realized with beams delivered by GANIL facility and by using the INDRA detector. The studied systems allow to produce compound nuclei with a large variation of N/Z, at very high angular momentum, and with similar excitation energy. Indeed, the neutron enrichment of the compound nuclei is expected to play an important role on the various emission mechanisms, providing crucial information on fundamental nuclear quantities as level density, fission barrier or viscosity. First results show evident staggering effects in the Z distributions, as well as different isotopic composition and enrichment for the reaction products in the two systems. Absolute cross sections calculations of the reaction products are in progress, to provide important indication on the isospin influence on the reaction mechanism and fragments production. Such a set of data will in fact provide new constraint on sophisticated models attempting to describe statistical and/or dynamical properties [2] of excited nuclei