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International audience; In this contribution the status of the FAZIA project is presented, with a particular focus on the first experiment (identified as ISO-FAZIA) after the R&D phase. In this experiment four complete FAZIA blocks in a fully operating configuration were used. They were mounted in a planar “belt” geometry, symmetrically positioned with respect to the beam axis, covering the polar angles between 2.5◦ and 17.4◦ degrees. The investigated systems were 84Kr + 48,40Ca at 35 AMeV. The main goal of the experiment was the study of the isospin transport phenomena, extending a previous analysis. This contribution will report on the isotopic identi- fication capability of the FAZIA detector as well as preliminary results concerning the average isospin of the quasi-projectile produced in semiperipheral collisions as a function of the isospin of the target.

The systems 32S+40,48Ca and 32S+48Ti at 17.7 MeV/nucleon were investigated with the setup general array for fragment identification and for emitted light particles in dissipative collisions (GARFIELD) plus ring counter (RCo) at Laboratori Nazionali di Legnaro (LNL) of Istituto Nazionale di Fisica Nucleare (INFN). Fusion evaporation (FE), fusion fission (FF), and deep inelastic (DIC) events were identified, also through the comparison with the prediction of a transport model (stochastic mean field, SMF), coupled to GEMINI++ as an afterburner. This work mainly deals with the study of isospin transport phenomena in DIC events. In particular, the isospin diffusion is highlighted by comparing the average isotopic content of the quasiprojectile (QP) remnants observed when the target is the N=Z nucleus 40Ca and when it is the neutron-rich 48Ca. Also, the d/p and t/p ratios for particles forward emitted with respect to the QP were found to increase with increasing N/Z of the target. ispartof: Physical Review C vol:96 issue:3 status: published

Cluster structure effects in nuclei have been investigated looking to the pre-equilibrium particles emitted in the O-16+Cu-65 and F-19+Ni-62 reactions at the same beam velocity of 16 A MeV which lead to the same Rb-81* compound nucleus. Despite the slight difference in excitation energies, the same fast emission should be expected from the two systems; unless major effects induced by the projectile's cluster structure, which should influence the pre-equilibrium a-particle production during the non-equilibrium stage, are present. The experimental data have been collected with the GARFIELD+RCo apparatus at Laboratori Nazionali di Legnaro. In this contribution we report on the preliminary spectra of light-charged particles, obtained in coincidence with evaporation residues, and their comparison with the results obtained from model calculations.

Heavy-ion collisions at lower energies provide a rich environment for investigating reaction dynamics. Recent theory has suggested a sensitivity to the symmetry energy and the equation of state via deformations of the reaction system and ternary breaking of the deformed reaction partners into three heavy fragments. A new detection system has been commissioned at Texas A&M University in an attempt to investigate some of the observables sensitive to the nuclear equation of state.

Heavy-ion collisions around the Fermi energy provide a rich environment for investigating reaction dynamics and provide an opportunity to explore the transition from quasi-fission to multi-fragmentation. A new detection system, FAUST-QTS, has been commissioned at Texas A&M University in order to investigate the reaction dynamics in this transitional energy regime. FAUST-QTS is constructed through the coupling of the FAUST array to a large bore quadrupole triplet spectrometer, and designed to detect heavy fragments near the beam axis coincident with lighter particles. © 2015 Elsevier B.V. All rights reserved.

Despite the long-standing interest in the symmetry energy by the nuclear physics community, much work remains to characterize the equation of state away from the valley of stability and normal density. Although the correlations between the thermodynamic properties (temperature, density, pressure) has been explored, the dependence of these correlations on the neutron-proton asymmetry has only recently been probed experimentally. In this work, we provide evidence for the asymmetry dependence of the nuclear caloric curve using multiple independent probes. Correlations between the temperature, density and pressure when normalized to their critical values exhibit scaling, allowing extraction of the critical point. The location of the critical point shows a dependence on the neutron-proton asymmetry. © 2014 SIF, Springer-Verlag Berlin Heidelberg.

Suppression of multiplicity fluctuations has been observed for three light fermions (protons, tritons and 3He) in the multifragmentation of reconstructed hot quasi-projectiles produced in collisions of 32S (45 MeV/nucleon) with 112Sn. This suppression, predicted by recent calculations, is attributed to Pauli blocking and has also been observed in experiments with trapped Fermi gases. Experimental results on nuclear temperature and density employing a quantal approach based on momentum and multiplicity fluctuations are also presented. The extracted temperatures show a noticeable reduction when compared to a similarly derived classical method. This reduction in temperature is in agreement with previous predictions indicating that classically derived methods overpredict nuclear temperature as they do not take into account the Fermi motion of the nucleons. The present results underline the role of quantum statistics in nuclear disassembly and suggest the need for proper quantum treatment when dealing with the thermodynamic properties of fragmenting heavy ions. © 2014 IOP Publishing Ltd.

The investigation of the isospin dependence of multifragmentation reactions relies on precise reconstruction of the fragmenting source. The criteria used to assign free emitted neutrons, detected with the TAMU Neutron Ball, to the quasi-projectile source are investigated in the framework of two different simulation codes. Overall and source-specific detection efficiencies for multifragmentation events are found to be model independent. The equivalence of the two different methods used to assign experimentally detected charged particles and neutrons to the emitting source is shown. The method used experimentally to determine quasi-projectile emitted free neutron multiplicity is found to be reasonably accurate and sufficiently precise as to allow for the study of well-defined quasi-projectile sources. Experimental QP neutron multiplicity distributions for three similar reactions with different isospin content are also presented. An increase in neutron emission is found for more n-rich systems. © 2012 Elsevier B.V.

The thermodynamics of excited nuclear systems allows the exploration of a phase transition in a two-component quantum mixture. Temperatures and densities are derived from quantum fluctuations of fermions. The pressures are determined from the grand partition function of Fisher's model. Critical scaling of observables is found for the first time for fragmenting systems which differ in neutron to proton concentrations thus constraining the equation of state (EOS) of asymmetric nuclear material. The derived critical exponent, β = 0.35 ± 0.01, belongs to the liquid-gas universality class. The critical compressibility factor Pc/ρcTc increases with increasing neutron concentration, which could be due to finite-size and/or Coulomb effects. © 2013 World Scientific Publishing Company.

The shapes of correlation functions are known to give information about the spatial and temporal extent of an emitting source. Since these two properties can be sensitive to the density-dependence of the asymmetry energy, these functions have been constructed using transport models in the past. In this work, correlation functions extracted using Constrained Molecular Dynamics (CoMD) are used to investigate the possibility of experimentally probing the density-dependence of the asymmetry energy using these correlation functions and detectors with high angular resolution.

Fragment yield data have been analyzed using the Landau free energy approach to investigate the critical phenomena of fragmenting quasi-projectiles formed in Zn-64 + Zn-64, Ni-64 + Ni-64, and Zn-70 + Zn-70 reactions at beam energy of 35 MeV/nucleon. Pairing coefficients normalized to the temperature of the fragmenting source (a(p)/T) were extracted from yield data of N = Z fragments in order to correct for odd-even effects in free energy calculations. Plots of fragment free energy (F/T) versus the neutron-proton asymmetry show three minima, indicating the system to be in a first-order phase transition regime. Values of fitting parameters to the Landau free energy equation as well as a(p)/T, which are related to thermodynamic properties of the fragmenting systems, exhibit a dependence on the neutron-proton asymmetry in addition to their dependence on the excitation energy of the fragmenting source. DOI: 10.1103/PhysRevC.87.017603

A basic feature of the nuclear equation of state is not yet understood: the dependence of the nuclear caloric curve on the neutron-proton asymmetry. Predictions of theoretical models differ on the magnitude and even the sign of this dependence. In this work, the nuclear caloric curve is examined for fully reconstructed quasi-projectiles around mass A= 50. The caloric curve extracted with the momentum quadrupole fluctuation thermometer shows that the temperature varies linearly with quasi-projectile asymmetry N-ZA. An increase in asymmetry of 0.15 units corresponds to a decrease in temperature on the order of 1 MeV. These results also highlight the importance of a full quasi-projectile reconstruction in the study of thermodynamic properties of hot nuclei. © 2013 Elsevier B.V.

A systematic study on the effect of secondary decay on the symmetry energy coefficient extracted by isoscaling and the recently proposed isobaric yield ratio methods within the statistical multifragmentation model (SMM) is performed. The correlations between the input symmetry energy coefficients and the calculated ones from both primary and secondary fragment yields are analyzed. Results for secondary fragments show that the best estimation of the input symmetry energy coefficient within SMM is obtained by the isoscaling method, using the yields of light fragments. A comparison to experimental results is also presented. © 2013 American Physical Society.

Results of a study of the (p, p ) reaction on 12C with polarized incident protons of 100 MeV are reviewed. Experimental cross section and analyzing power distributions are compared with predictions of a distorted wave impulse approximation (DWIA) theory. The theory reproduces the data reasonably well, suggesting that a quasifree knockout mechanism dominates the reaction. Spectroscopic information extracted from the cross section data is in agreement with a shell model prediction.

Direct binary projectile fragmentation is being investigated for the case where a 400 MeV 12C projectile breaks up into an particle and a 8Be fragment in the interaction with a thin 93Nb and 197Au target. While the 8Be fragments were measured at 9 , the correlated particles were detected in an angular range between 16 and 30 on the opposite side of the beam. From the preliminary results presented here one may obtain information on the amount of quasi-elastic fragmentation (both fragments do not suffer any further interactions after they are produced). These experimental results indicate that the quasi-elastic break-up process is the dominant contribution to the measured correlation spectra. As was also observed in earlier work, the most forward quasi-elastically emitted particles have energies exceeding the beam velocity.