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27Ne has been investigated through the one neutron transfer reaction 26Ne(d,p)27Ne in inverse kinematics at 9.7 MeV/nucleon. The results support the existence of a low lying negative parity state in 27Ne which is a signature of a reduced sd-fp shell gap in the N = 16 neutron rich region, at variance with stable nuclei.

We present a three source analysis of velocity spectra of light charged particles (LCP) and neutrons emitted in the reaction 40Ar+27Al at 44A MeV. The light particle (LP) velocity spectra are studied as a function of the detection angle (1.5°<θ<172°) and of the charge of the forward detected projectile-like fragment (PLF). The temperature parameter, the velocity and the intensity of each source are extracted as a function of the PLF charge. While the temperature parameters for PLF and target-like fragments (TLF) are very similar and show a dependence on the PLF charge, the temperature parameter for the intermediate source is approximately 15 MeV, independent of the PLF charge. Comparison with temperature values extracted from double isotopic ratios, shows an agreement only between the temperature values extracted from formula involving 3He, 4He, d, tratios and the PLF proton temperature parameter. The characteristics of the PLF sources are derived. Present results are discussed with regards to the degree of thermalization which could be achieved in the PLF and TLF sources.

Abstract:: The prompt component at intermediate velocity of light charged particles is investigated. An improved coalescence model coupled to the intra-nuclear cascade code ISABEL is used to obtain light complex particle energy spectra and multiplicities as a function of impact parameter. The results are compared with experimental data from the 36Ar + 58Ni experiment at 95 MeV/nucleon, performed with the INDRA 4π detection system. The calculated prompt component is found to rather well reproduce proton spectra. For complex light charged particles the calculated components well populate the high energy part of spectra. Prompt emission can therefore explain the large transverse energies experimentally observed at mid-rapidity.

Recent experimental results concerning heavy systems (Pb+Au, Pb+Ag, Pb+Al, Gd+C, Gd+U, Xe+Sn, …) obtained at GANIL with the INDRA and NAUTILUS 4πarrays will be presented. The study of reaction mechanisms has shown the dominant binary and highly dissipative character of the process. The two heavy and excited fragments produced after the first stage of the interaction can decay into various decay modes from evaporation to multifragmentation including fission. However, deviations from this simple picture have been found by analyzing angular and velocity distributions of light charged particles, and fragments. Indeed, there is a certain amount of matter in excess emitted between the two primary sources suggesting either the existence of a mid-rapidity source similar to the one observed in the relativistic regime (participants) or a strong deformation induced by the dynamics of the collision (neck instability). This last possibility has been suggested by analyzing in detail the angular distributions of the fragments. More precisely, we observe an isotropic component which is compatible with the prediction of statistical models and a second one corresponding to breakup aligned with the recoil direction of the projectile like source which should be compared with the predictions of dynamical calculations based on microscopic transport models.

Abstract:: Proton and deuteron correlation functions have been investigated with both impact parameter and emission source selections. The correlations of the system 129Xe+NatSn at 50 AMeV have been measured with the 4π INDRA which provides a complete kinematical description of each event. The emission time scale analyzed with a quantum model reveals the time sequence of the light particles emitted by the projectile-like fragment. The short and constant emission time of the proton, independent of the impact parameter, can be attributed to a preequilibrium process.

Abstract:: Vaporized sources produced in collisions between 36Ar and 58Ni at 95 MeV per nucleon have been detected with the multidetector INDRA. Complete information concerning the deexcitation properties of quasi-projectiles, including second moments of chemical composition, is compared to a quantum statistical model describing a gas of fermions and bosons in thermal and chemical equilibrium. Inclusions in the calculation of all known discrete levels of nuclear species which deexcite into light particles and of a final state excluded volume interaction are found decisive to very well reproduce the experimental data, which strongly supports that thermodynamical equilibrium was achieved at freeze-out for such sources.

Abstract:: Fusion-fission and fully energy-damped binary processes of the 35Cl+24Mg reaction were investigated using particle-particle coincidence techniques at a 35Cl bombarding energy of Elab≈ 8 MeV/nucleon. Inclusive data were also taken in order to determine the partial wave distribution of the fusion process. The fragment-fragment correlation data show that the majority of events arises from a binary-decay process with a relatively large multiplicity of secondary light-charged particles emitted by the two primary excited fragments in the exit channel. No evidence is observed for ternary-breakup processes, as expected from the systematics recently established for incident energies below 15 MeV/nucleon and for a large number of reactions. The binary-process results are compared with predictions of statistical-model calculations. The calculations were performed using the Hauser-Feshbach method, based on the available phase space at the scission point of the compound nucleus. This new method uses temperature-dependent level densities and its predictions are in good agreement with the presented experimental data, thus consistent with the fusion-fission origin of the binary fully-damped yields.

In order to verify the effect of the ablation stage on the fast abrasion mechanism, detailed evaporative calculations have been performed on the primary projectile and target-like fragments issued from the reactions40Ar+27Al and40Ca+27Al. The results account for many of the experimental features observed in the projectile and target-like fragments produced at intermediate energies. However it is pointed out that, in order to get a better agreement between theory and experimental data, the primary projectile and target-like fragments should carry a more substantial excitation energy than predicted by a purely geometric abrasion model.

Inclusive cross sections of intermediate mass fragments (6⩽Z⩽16) have been measured in 20Ne induced reactions on silver and gold targets at 20, 30, 40, 50 and 60 MeV/u incident energies. Whereas the production yields remain approximately constant for the Ne+Ag system, they increase by a factor of two for the Ne+Au system over the same bombarding energy range. These results are discussed in the framework of two fragmentation models.

Abstract.: 27Ne has been investigated through the one neutron transfer reaction 26Ne(d,p)27Ne in inverse kinematics at 9.7 MeV/nucleon. The results support the existence of a low lying negative parity state in 27Ne which is a signature of a reduced sd-fp shell gap in the N = 16 neutron rich region, at variance with stable nuclei.

27Ne has been investigated through the one neutron transfer reaction 26Ne(d,p)27Ne in inverse kinematics at 9.7?MeV/nucleon. The results support the existence of a low lying negative parity state in 27Ne which is a signature of a reduced sd-fp shell gap in the N = 16 neutron rich region, at variance with stable nuclei.

The properties of the two-body channels populated in the35Cl +12C reaction, at a bombarding energy of 180 KeV, have been studied by means of a kinematical coincidence technique. Binary reaction products show full energy equilibration and isotropic angular distributions in the center-of-mass frame. The asymmetrical elemental distribution of the fully-damped yields, similar to that observed previously in the32S +24Mg reaction, suggests the occurence of fusion-fission rather than orbiting.

The properties of the two-body channels in the35Cl+24Mg reaction at a bombarding energy of 275 MeV, have been investigated by using fragment-fragment coincident techniques. The exclusive data show that the majority of events arises from a binary-decay process. The rather large number of secondary light charged-particles emitted from the two excited exit fragments are consistent with the expectations of the Extended Hauser-Feshbach Method. Therefore no evidence for the occurence of ternary break-up events is observed.