Directed and elliptic flows of neutrons and light charged particles were measured for the reaction 197 Au+ 197 Au at 400 MeV/nucleon incident energy within the ASY-EOS experimental campaign at the GSI laboratory. The detection system consisted of the Large Area Neutron Detector LAND, combined with parts of the CHIMERA multidetector, of the ALADIN Time-of-flight Wall, and of the Washington-University Microball detector. The latter three arrays were used for the event characterization and reaction-plane reconstruction. In addition, an array of triple telescopes, KRATTA, 2 was used for complementary measurements of the isotopic composition and flows of light charged particles.From the comparison of the elliptic flow ratio of neutrons with respect to charged particles with UrQMD predictions, a value γ = 0.72 ± 0.19 is obtained for the power-law coefficient describing the density dependence of the potential part in the parametrization of the symmetry energy. It represents a new and more stringent constraint for the regime of supra-saturation density and confirms, with a considerably smaller uncertainty, the moderately soft to linear density dependence deduced from the earlier FOPI-LAND data. The densities probed are shown to reach beyond twice saturation.

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Background: Near-threshold α-clustered states in light nuclei have been postulated to have a structure consisting of a diffuse gas of α-particles which condense into the 0s orbital. Experimental evidence for such a dramatic phase change in the structure of the nucleus has not yet been observed. Method:To examine signatures of this α-condensation, a compound nucleus reaction using 160, 280, and 400 MeV 16 O beams impinging on a carbon target was used to investigate the 12 C( 16 O, 7α) reaction. This permits a search for near-threshold states in the α-conjugate nuclei up to 24 Mg.Results: Events up to an α-particle multiplicity of 7 were measured and the results were compared to both an Extended Hauser-Feshbach calculation and the Fermi break-up model. The measured multiplicity distribution exceeded that predicted from a sequential decay mechanism and had a better agreement with the multi-particle Fermi break-up model. Examination of how these 7α final states could be reconstructed to form 8 Be and 12 C(0 + 2 ) showed a quantitative difference in which decay modes were dominant compared to the Fermi break-up model. No new states were observed in 16 O, 20 Ne, and 24 Mg due to the effect of the N-α penetrability suppressing the total α-particle dissociation decay mode. Conclusion:The reaction mechanism for a high energy compound nucleus reaction can only be described by a hybrid of sequential decay and multi-particle breakup. Highly α-clustered states were seen which did not originate from simple binary reaction processes. Direct investigations of near-threshold states in N-α systems are inherently impeded by the Coulomb barrier prohibiting the observation of states in the N-α decay channel. No evidence of a highly clustered 15.1 MeV state in 16 O was observed from ( 28 Si , 12 C(0 + 2 )) 16 O(0 + 6 ) when reconstructing the Hoyle state from 3 α-particles. Therefore, no experimental signatures for α-condensation were observed. arXiv:1907.05471v2 [nucl-ex]

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The present study has been carried out in order to investigate about the possibility of using EJ 299-33 scintillator in a multi-detector array to detect neutrons along with light charged particles. In a reaction induced by stable and exotic heavy-ions beams, where copious production of neutrons and other light charged particles occurs, discrimination with low identification threshold of these particles are of great importance. In view of this, EJ 299-33 scintillator having dimension of 3 cm × 3 cm × 3 cm backed by a photomultiplier tube was tested and used under vacuum to detect neutrons, gamma-rays and alpha particles emitted by radioactive sources. Anode pulses from the photomultiplier tube were digitized through GET electronics, recorded and stored in a data acquisition system for the purpose of an off-line analysis. The measurements, under vacuum and low background conditions, show good pulse shape discrimination properties characterized by low identification threshold for neutrons, gamma-rays and alpha particles. The Figures of Merit for neutron-gamma and alpha particles-gamma discriminations have been evaluated together with the energy resolution for gamma-ray and alpha particles.

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Two and multi particle correlations from the decay of sources produced in 12 C+ 24 Mg and 12 C+ 208 Pb collisions at E=35 AM eV have been studied by using the forward part (1 o < θ lab < 30 o) 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 5 Li, 6 Li, 6 Be, 8 Be and the astrophysically important state in 12 C decaying into three alpha particles. Results and future perspectives at the INFN-LNS will be presented.