Isospin Effects Studied with the CHIMERA Detector at 35 MeV/Nucleon

NIMInternational audienceThe yield of light charged particles and intermediate mass fragments is studied for the neutron-rich, $^{124}$Sn+$^{64}$Ni, and neutron-poor, $^{112}$Sn+$^{58}$Ni, reactions at 35 MeV/nucleon as a function of the impact parameter. Our main observations are: (i) The yields of $^{1}$H, $^{3}$He and $^{4}$He particles in the neutron-poor system are enhanced with respect to the neutron-rich system and the yield of $^{3}$H is suppressed at all impact parameters, (ii) The ratio of $^{3}H to$^{3}$He yield is three times larger for neutron poor system, (iii) The N/Z ratio of the emitted intermediate-mass fragments shows dependence on the isospin of the system, (iv) The neutron richness of detected intermediate mass fragments depends strongly on their rapidity. The gross features of the experimental data are reproduced by quantum molecular dynamics model calculations

Isospin Effects Studied with the CHIMERA Detector at 35 MeV/Nucleon

NIMInternational audienceThe yield of light charged particles and intermediate mass fragments is studied for the neutron-rich, $^{124}$Sn+$^{64}$Ni, and neutron-poor, $^{112}$Sn+$^{58}$Ni, reactions at 35 MeV/nucleon as a function of the impact parameter. Our main observations are: (i) The yields of $^{1}$H, $^{3}$He and $^{4}$He particles in the neutron-poor system are enhanced with respect to the neutron-rich system and the yield of $^{3}$H is suppressed at all impact parameters, (ii) The ratio of $^{3}H to$^{3}$He yield is three times larger for neutron poor system, (iii) The N/Z ratio of the emitted intermediate-mass fragments shows dependence on the isospin of the system, (iv) The neutron richness of detected intermediate mass fragments depends strongly on their rapidity. The gross features of the experimental data are reproduced by quantum molecular dynamics model calculations

Present status of the CHIMERA-ISOSPIN experiment

INDRA NIM Matière NucléaireInternational audienc

Dynamical fission in 124^{124}Sn+64^{64}Ni collision at 35A MeV

NIM, Matière NucléaireSome properties of fast, nonequilibrium splitting of projectiles in the $^{124}$Sn+$^{64}$Ni reaction at 35A MeV were determined using the 4$\pi$ CHIMERA detector system. In particular the charge distributions, in- and out-of-plane angular distributions, and relative velocities of projectilelike fragments were measured. The time scale of the process was estimated and it turned out that the process is sequential but much faster than the ordinary, equilibrated fission

Fragmentation studies with the CHIMERA detector at LNS in Catania: recent progress

The new detector CHIMERA, in its final 4pi configuration, has been installed at Laboratori Nazionali del Sud (LNS) in Catania in January 2003. Beams of different energies ranging from protons to An ions were delivered by the, Tandem and the Super Conducting Cyclotron for nuclear reaction studies, in agreement with the approval of the Scientific Advisory Committee of LNS. Recent experimental results confirm very low energy thresholds of the trigger (below 0.5 MeV/nucleon), ensured within a wide dynamical range. Good characteristics of identification of light charged particles and heavy fragments have been obtained by using three detection techniques: DeltaE-E, DeltaE-time of flight, and the Pulse-Shape discrimination method. We present results of recent analysis concerning the production of intermediate mass fragments (IMF) in semi-peripheral collisions. Our results combined with theoretical Boltzmann-Nordheim-Vlasov simulations clearly demonstrate the presence of very fast processes of IMF production in the overlapping region of the target and projectile nuclei during re-separation, i.e. in the time scale comparable with the collision time. Evidence for slower, sequential-like production of IMF's is also shown

Dynamical aspects of fragment productions in the reaction 124Sn+64Ni^{124}Sn+^{64}Ni and 112n+58Ni^{112}n+^{58}Ni at 35 A.MeV

Matière Nucléaire NI