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The ASY-EOS experiment at GSI laboratory measured the direct and elliptic flow of neutrons and light charged particles in the reaction 197Au+197 Au at 400 A MeV incident energy. The ratio of elliptic flow of neutrons with respect to that of the light charged particles was used as main experimental observable to probe the density dependence of the symmetry energy term of the nuclear equation of state. Results, obtained by comparison of the experimental data with the UrQMD model predictions, strongly support a moderately soft to linear density dependence of the symmetry energy at suprasaturation densities below 2ρ0.

The results of the analysis of the reactions 78,86Kr +40,48 Ca at 10 AMeV are presented. The experiment was performed at the INFN Laboratori Nazionali del Sud (LNS) in Catania by using the 4π multidetector CHIMERA, with beams delivered by the Superconductive Cyclotron. The competition among the various disintegration paths and in particular the isospin effects on the decay modes of the produced composite systems are investigated; this provides information about fundamental nuclear quantities such as level density, fission barrier and viscosity. Different isotopic composition and relative richness are observed among the reaction products of the two systems. An odd-even staggering effect is present in the charge distributions, in particular for the light fragments produced by the neutron-poor system. The kinematical characteristics of the IMF seem to indicate a high degree of the relaxation of the formed system. Besides, global features analysis seems to show some differences in the contribution arising from the various reaction mechanisms for the two reactions.

The study of the decay modes competition of the compound systems produced in the collisions 78Kr+40Ca and 86Kr+48Ca at 10AMeV is presented. In particular, the N/Z entrance channel influence on the decay paths of the compound systems, directly connected to the isospin influence, is investigated. The experiment was performed at the INFN Laboratori Nazionali del Sud (LNS) in Catania by using the 4π multi-detector CHIMERA. Charge, mass, angular distributions and kinematical features of the reaction products were studied. The analysis shows some differences in the contribution arising from the various reaction mechanisms for the neutron poor and neutron rich systems. Comparison with theoretical statistical and dynamical models are presented for the two systems. Besides a study of the influence of the energy on the entrance channel is performed for the 78Kr+40Ca reaction, by comparing the results of this experiment to those obtained for the same system at 5.5 AMeV with the INDRA device at GANIL.

Two and multi particle correlations from the decay of sources produced in 12C+24Mg and 12C+208Pb collisions at E=35 AMeV have been studied by using the forward part (1° < θlab < 30°) of the CHIMERA multi-detector. Correlations and invariant mass spectroscopy are used to explore simultaneous and sequential decays of resonances in light isotopes with Z∼3-6, produced in peripheral collisions via the break-up of excited quasi-projectiles. Among them we mention 5Li, 6Li, 6Be, 8Be and the astrophysically important state in 12C decaying into three alpha particles. Results and future perspectives at the INFN-LNS will be presented.

The experimental investigation of Heavy Ion reactions at Fermi energies requires an accurate measurement of observables, such as linear momentum and energy of the detected particles. In order to address this problem, dedicated and flexible correlator arrays are useful tools to be coupled with 4π detectors. One of these arrays is FARCOS, presently under construction at the INFN Sezione di Catania and Laboratori Nazionali del Sud (LNS).

The elliptic-flow ratio of neutrons with respect to protons or light complex particles in reactions of heavy ions at pre-relativistic energies has been proposed as an observable sensitive to the strength of the symmetry term of the nuclear equation of state at supra-saturation densities. In the ASY-EOS experiment at the GSI laboratory, flows of neutrons and light charged particles were measured for 197Au+197Au collisions at 400 MeV/nucleon. Flow results obtained for the Au+Au system, in comparison with predictions of the UrQMD transport model, confirm the moderately soft to linear density dependence of the symmetry energy deduced from the earlier FOPI-LAND data.

The binary break-up of projectile-like fragments in non central heavy-ion collisions follows different decay patterns, from equilibrated emission towards dynamical (prompt) fission. Recently, comparing two systems with different N/Z in the entrance channel, it has been shown that the dynamical emission cross-section is enhanced for the most neutron rich system while the statistical emission cross-section is independent from the isotopic composition. In order to understand this dependence and disentangle it from the initial size of the nuclei, we have studied the two isobaric systems 124Xe+64 Zn and 124Xe+64 Ni at 35 A MeV (InKiIsSy experiment), in comparison with the previous studied reactions (124Sn +64 Ni and 112Sn +58 Ni) at the same bombarding energy. We present the first results evidencing a striking similar effect in the dynamical decay as a function of the N/Z of the target for equal size systems.

Projectile break-up reactions induced on polyethylene (CH2) target are used in order to study the spectroscopy of 10Be and 16C nuclei. For the present experiment we used 10Be and 16C beams delivered by the FRIBs facility at INFN-LNS, and the CHIMERA 4π multi-detector. 10Be and 16C structures are studied via a relative energy analysis of break-up fragments. The 4He+6He break-up channel allowed us to study the spectroscopy of 10Be; in particular we find evidence of a new state in 10Be at 13.5 MeV excitation energy. The 16C nucleus is studied via 6He-10Be correlation; we find the fingerprint of a possible state at about 20.6 MeV

The elliptic-flow ratio of neutrons with respect to protons or light complex particles in reactions of heavy ions at pre-relativistic energies has been proposed as an observable sensitive to the strength of the symmetry term of the nuclear equation of state at supra-saturation densities. In the ASY-EOS experiment at the GSI laboratory, flows of neutrons and light charged particles were measured for 197Au+197Au, 96Zr+96Zr and 96Ru+96Ru collisions at 400 MeV/nucleon with the Large Area Neutron Detector LAND as part of a setup with several additional detection systems used for the event characterization. Flow results obtained for the Au+Au system, in comparison with predictions of the UrQMD transport model, confirm the moderately soft to linear density dependence of the symmetry energy deduced from the earlier FOPI-LAND data.

The systems 124Sn+64Ni and 112Sn+58Ni at 35 AMeV were analyzed in previous experiments, by using the 4π multi-detector CHIMERA in order to investigate the time-scale and mechanisms of fragments formation. By comparing the two systems, effects that have been correlated to Isospin transport in reaction dynamics and symmetry energy term of nuclear equation of state at sub-saturation density were found. Recently, in order to disentangle the Isospin effects from size effects the 124Xe+64Ni reaction was investigated at the same beam energy of 35 AMeV.

Nuclear matter under extreme conditions can be studied in the laboratory with heavy-ion collisions. In this case one can indeed vary the incident energy and explore different impact parameter and rapidity regions to access densities that extend above and below saturation. This opportunity allows one to learn about the nuclear equation of state and its implications in astrophysics phenomena such as supernovae explosions and neutron stars properties. All these phenomena involve time scales that need to be accessed with two- and multi-particle correlation measurements. In this contribution a brief report of the FARCOS array will be presented. In particular, tests with alpha sources and beams and preliminary results from a recent experiment INKIISSY performed using a FARCOS prototype made of four telescopes will be presented.

Decay modes of excited compound systems 118Ba and 134Ba, produced respectively in the 78Kr+40Ca and 86Kr+48Ca collisions at 10 A·MeV, are investigated. In particular, the competition between the various disintegration path of medium mass compound nuclei, formed by fusion processes, the production of the so referred Intermediate Mass Fragments (IMF), and the isospin dependence of the decay process are studied. Data were taken at the INFN-Laboratori Nazionali del Sud (LNS) by using the CHIMERA array. Data analysis is in progress; a first indication on the average-energy angular distributions suggests pre-equilibrium effects affecting the data and the presence of isotopical effects.

Latest results concerning the study of central collisions in 58Ni+48Ca reactions at Elab(Ni)=25 AMeV are presented. The experimental data, collected with the CHIMERA 4π device, have been analyzed in order to investigate the competition among different reaction mechanisms for central collisions in the Fermi energy domain. The method adopted to perform the centrality selection refers to the global variable “flow angle”, that is related to the event shape in momentum space, as it is determined by the eigenvectors of the experimental kinetic-energy tensor. The main features of the reaction products were explored by using different constraints on some of the relevant observables, such as mass and velocity distributions and their correlations. Much emphasis was devoted to the competition between fusion-evaporation processes with subsequent identification of a heavy residue and a prompt multifragmentation mechanism. The reaction mechanism was simulated in the framework of transport theories (dynamical stochastic BNV calculations, followed by sequential SIMON code) and further comparison with dynamical calculations from transport model (QMD, CoMD) are in progress. Moreover, an extension of this study taking into account for the light particles has been envisaged.

Semi-peripheral collisions of 64Ni + 124Sn in direct and inverse kinematics, at 35 A MeV incident energy, are studied to characterize the dynamical origin and align-ments properties of fragments emission at midrapidity. This emission is partly due to the fragmentation of a transient neck joining the projectile and target in the early stages of the reaction. Recently we exploited observable from neck fragmentation to constraint the density dependence of the symmetry energy. In this contribution we focus on the density evolution of the mid-rapidity source. An experimental survey is suggested to check if data are consistent with the formation of neck fragments in a dilute density region in contact with the projectile-like and target-like spectators at normal saturation density.

The elliptic-flow ratio of neutrons with respect to protons or light complex particles in reactions of heavy-ions at pre-relativistic energies has been proposed as an observable sensitive to the strength of the symmetry term of the nuclear equation of state at supra-saturation densities. The results obtained from the existing FOPI/LAND data for 197Au+197Au collisions at 400 MeV/nucleon in comparison with the UrQMD model simulations favoured a moderately soft symmetry term, but suffer from a considerable statistical uncertainty. These results have been confirmed by an independent analysis based on the Tübingen QMD simulations. In order to obtain an improved data set for Au+Au collisions and to extend the study to other systems, a new experiment was carried out at the GSI laboratory by the ASY-EOS collaboration. The present status of the data analysis is reported

The elliptic-flow ratio of neutrons with respect to protons in reactions of neutron rich Heavy-Ion at intermediate energies has been recently proposed as an observable sensitive to the strength of the symmetry term in the nuclear equation of state (EOS) at supra-saturation densities. The recent results obtained from the existing FOPI/LAND data for 197Au+197Au collisions at 400 MeV/nucleon in comparison with the UrQMD model allowed a first estimate of the symmetry term of the EOS but suffer from a considerable statistical uncertainty. In order to obtain an improved data set for Au+Au collisions and to extend the study to other systems, a new experiment was carried out at the GSI laboratory by the ASY-EOS collaboration in May 2011.

Correlations between two or more particles can be used as a tool to explore the space-time features of nuclear reactions as well as spectroscopic properties of produced unbound clusters. In order to have new options to study the mentioned correlations, FARCOS (Femtoscope ARray for COrrelations and Spectroscopy) has been conceived as a compact high resolution array, composed of square telescopes. In this work the main features of FARCOS array as well as part of the physics cases are described.

Preliminary outcome of ISODEC experiment, performed at INFNLNS with the CHIMERA array, are presented. Disintegration path dependence on the entrance-channel N/Z ratios (isospin asymmetries) for the reactions 78Kr+40Ca and 86Kr+48Ca at 10 A·MeV, which give origin to the intermediate systems 118Ba and 134Ba, is being investigated. Staggering effects seem to be present as it was the case of a complementary measurement performed at GANIL at lower energy, i.e. 78,82Kr+40Ca at 5.5 A·MeV.

The recent intensity upgrade of the LNS fragmentation beam is discussed. The available beams, the tagging procedures and details on the beam quality are reported. The experimental program started with the CHIMERA detector using such beams is also discussed with preliminary results and future perspectives.

Effects related to the neutron to proton ratio (N/Z) degree of freedom in 40,48Ca+40,48Ca reactions at 25 MeV/nucleon have been investigated. Isotopic effect and even-odd staggering characterize the emission of light fragments at forward angles. The study of isobaric ratio 7Li/7Be for quasi-projectile source in semi-peripheral event of reactions allows moreover to investigate isospin diffusion effects in heavy ion collisions.

Dynamical breakup of projectile-like fragments (PLF) following dissipative reactions of 48 Ca projectiles with 112 Sn and 124 Sn is shown to exhibit “isoscaling” regularities that can be understood in terms of phase space governed by ground state masses. Ambiguities in isoscaling parameters obscure information on nuclear symmetry energy at subnormal densities.

The first results of the ISODEC experiment, performed at the INFN Laboratori Nazionali del Sud (LNS) by using the CHIMERA detector, are presented. The principal aim of this experiment is to explore the isospin dependence of the decay modes of medium mass compound nuclei formed by fusion processes, by studying the competition between the various disintegration modes of 118,134Ba nuclei produced in the reactions 78Kr+40Ca and 86Kr+48Ca at 10 AMeV. The studied systems allow in fact to produce compound nuclei with a large variation of N/Z, and such data will also provide new constraint on sophisticated models attempting to describe statistical and/or dynamical properties of excited nuclei. The experiment complements data already obtained at 5.5 AMeV for 78,82Kr+40Ca reactions, previously realized at GANIL by using the INDRA detector. First results show a strong staggering effects in the Z distributions, as well as different isotopic composition and enrichment for the reaction products in the two systems.

We present the first results of the ISODEC experiment, performed at the INFN-LNS with the CHIMERA device, in order to study the competition between the various disintegration modes of 118,134Ba compound nuclei produced by bombarding 40,48Ca targets with beams of 78,86Kr at 10 AMeV. This work aims thus to explore 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, studied by Ademard et al. with beams delivered by GANIL facility and by using the INDRA detector.

We will discuss results concerning the fate of hot nuclear systems populated in 40,48Ca+40,48Ca reactions at 25 MeV/nucleon. Due to the complexity of events, we used the Chimera 4π device as detection system. By selecting central events of reaction, we found that the interplay between binary-like and evaporation residue emissions is strongly sensitive on the N/Z of the entrance channels. In particular, evaporation residue emission increases at increasing the neutron content of colliding system. By comparing or data with CoMD-II model calculations, we can extract information about the density depend part of Symmetry Potential in the Nuclear Equation of State at near-saturation densities.