E. Henry

Decay competition in IMF production in the collisions 78 Kr+ 40 Ca and 86 Kr+ 48 Ca at 10 AMeV

De-excitation modes of compound systems 118 Ba and 134 Ba, produced respectively in the 78 Kr+ 40 Ca and 86 Kr+ 48 Ca collisions at 10 A.MeV, are investigated. In particular, the competition between the various disintegration decay paths of medium mass compound nuclei, formed by fusion processes and the isospin (related to N/Z) of the entrance channel influence on the decay process, are studied. Data were taken at the INFN-Laboratori Nazionali del Sud (LNS) in ISODEC experiment, by using the CHIMERA array. The experiment complements and improves the previous experiment performed at GANIL where the same mechanisms were studied at lower excitation energies. The results show the presence of a relaxed component in the reaction mechanism, evident staggering effects in the Z distributions, as well as different isotopic composition and neutron enrichment for the reaction products in the two systems.

Decay Competition in IMF Production in the Collisions

De-excitation modes of compound systems 118Ba and 134Ba, produced respectively in the 78Kr+40Ca and 86Kr+48Ca collisions at 10 AMeV, are investigated. In particular, the competition among the various disintegration decay paths and the neutron richness dependence of the decay process are studied. Experimentally, the different reaction products were detected and identified with different methods by means of the CHIMERA array at the INFN-Laboratori Nazionali del Sud. Global decay patterns and fragment emission characteristics are presented for the two systems.

^{78}

The de-excitation of medium mass nuclei 118,134 Ba produced in fusion process of 78,86 Kr on 40,48 Ca targets at 10 AMeV is studied, in order to investigate the isospin dependence of the decay modes; the neutron enrichment of the compound nuclei is in fact expected to play an important role on the emission mechanisms, providing crucial information on fundamental nuclear quantities such as level density, fission barrier, viscosity and symmetry energy. The experiment was performed at INFN-LNS with the 4π multidetector for charged particles CHIMERA, used for the first time in this low energy regime, thanks to a suitable Pulse Shape Discrimination method for charge identification applied to the silicon detectors. Preliminary results show a different isotopic composition and relative enrichment for the same Z in the two systems. The yields of the Intermediate Mass Fragments (IMF, 3<Z<12) exhibits a strong even-odd staggering, more pronounced for the n-poor system. The IMF energy spectra show some differences according to the entrance channel and to the charge and mass of the fragment.

Kr+

The de-excitation of medium mass nuclei 118,134 Ba produced in fusion process of 78,86 Kr on 40,48 Ca targets at 10 AMeV is studied, in order to investigate the isospin dependence of the decay modes; the neutron enrichment of the compound nuclei is in fact expected to play an important role on the emission mechanisms, providing crucial information on fundamental nuclear quantities such as level density, fission barrier, viscosity and symmetry energy. The experiment was performed at INFN-LNS with the 4π multidetector for charged particles CHIMERA, used for the first time in this low energy regime, thanks to a suitable Pulse Shape Discrimination method for charge identification applied to the silicon detectors. Preliminary results show a different isotopic composition and relative enrichment for the same Z in the two systems. The yields of the Intermediate Mass Fragments (IMF, 3<Z<12) exhibits a strong even-odd staggering, more pronounced for the n-poor system. The IMF energy spectra show some differences according to the entrance channel and to the charge and mass of the fragment.

^{40}

The de-excitation of medium mass nuclei 118,134 Ba produced in fusion process of 78,86 Kr on 40,48 Ca targets at 10 AMeV is studied, in order to investigate the isospin dependence of the decay modes; the neutron enrichment of the compound nuclei is in fact expected to play an important role on the emission mechanisms, providing crucial information on fundamental nuclear quantities such as level density, fission barrier, viscosity and symmetry energy. The experiment was performed at INFN-LNS with the 4π multidetector for charged particles CHIMERA, used for the first time in this low energy regime, thanks to a suitable Pulse Shape Discrimination method for charge identification applied to the silicon detectors. Preliminary results show a different isotopic composition and relative enrichment for the same Z in the two systems. The yields of the Intermediate Mass Fragments (IMF, 3<Z<12) exhibits a strong even-odd staggering, more pronounced for the n-poor system. The IMF energy spectra show some differences according to the entrance channel and to the charge and mass of the fragment.