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The study of clustering states in neutron-rich nuclei is an important subject of research in the field of nuclear physics, steadily growing in interest in the international scientific community. In this context, break-up reactions play an important role for the characterization of exotic states in radioactive light nuclei, like neutron halos around stable cores, α-clustering structures or exotic clusters. The CLIR (Clusters in Light Ion Reactions) experiment was performed at INFN - Laboratori Nazionali del Sud (LNS), aiming at the investigation of such states in light radioactive nuclei, by producing a radioactive beam at the FRIBs facility. Reaction products were detected by the CHIMERA multidetector, coupled with four telescopes of the FARCOS array. Calibrations of the tagging system and of the FARCOS telescopes have been performed, for which accurate procedures have been carried out. In this paper, results on the analysis will be presented. Moreover, a brief review on the new fragment separator FRAISE, currently under construction at LNS, will be given.

The onset of Multifragmentation phenomenon is investigated at low excitation energies. A detailed study on the origin of Intermediate Mass Fragment (IMF, Z>=3) produced in central collisions in the 58 Ni+ 40 Ca reaction at 25 AMeV is presented. The experimental campaign was performed with CHIMERA multi-detector at INFN Laboratori Nazionali del Sud in Catania (Italy). The multiple identification techniques of the 4p apparatus, together with low detection thresholds, enable the performance of a careful selection of Fusion-evaporation residues, Multifragmentation sources and their decay products. Comparisons with dynamical approach based on Boltzmann-Langevin-One-Body (BLOB) model predictions coupled with sequential emission code, were used as useful tools to depict and understand the characteristics of fragments emitted from an equilibrated compound nucleus or formed simultaneously in the multifragmenting source. A comparison with the preliminary results obtained for fragment production in central collisions of the same system, 58 Ni+ 40 Ca, at higher incident energies E beam =35AMeV, allows to study and characterize the evolution of multifragmentation phenomenon at the lower end of Fermi energies.

A project for an upgrade of the Superconducting Cyclotron is underway at INFN-LNS. One of the goals of this project is the production of RIBs (Radioactive Ion Beams) of high intensity. To reach this purpose, a dedicated facility consisting of a new fragment separator FRAISE (FRAgment In-flight SEparator) is ongoing, exploiting primary beams with a power up to ≈ 2-3 kW. The high intensity achievable with FRAISE requires the use of appropriate diagnostics and tagging systems that can operate also in a strong radioactive environment. In this framework, a R&D program has been started to develop the FRAISE facility as well as the diagnostics and the tagging systems.

With the advent of the new radioactive beam facilities it is necessary to develop neutron detection systems integrated with charged particle ones. The integration of the neutron signal, especially in using neutron rich beams, becomes a mandatory requirement in order to study the property of the nuclear matter in extreme conditions. For this reason new detectors using new materials have to be built. In this contribution, some new results about the efficiency estimation and the cross talk problem studied through GEANT4 simulations, related to the NArCoS project, will be described with the aim to design a new detector of both good energy and angular resolution. The detection of neutrons and charged particles in the same elementary detection cell is envisaged.

In nuclear reactions at Fermi energies two and multi particles intensity interferometry correlation methods are powerful tools in order to pin down the characteristic time scale of the emission processes. In this paper we summarize an improved application of the fragment-fragment correlation function in the specific physics case of heavy projectile-like (PLF) binary massive splitting in two fragments of intermediate mass(IMF). Results are shown for the reverse kinematics reaction 124Sn+64 Ni at 35 AMeV that has been investigated by using the forward part of CHIMERA multi-detector. The analysis was performed as a function of the charge asymmetry of the observed couples of IMF. We show a coexistence of dynamical and statistical components as a function of the charge asymmetry. Transport CoMD simulations are compared with the data in order to pin down the timescale of the fragments production and the relevant ingredients of the in medium effective interaction used in the transport calculations.

Main features of fragments produced in 58Ni+40Ca and 58Ni+48Ca systems at 25 AMeV, collected by Chimera multidetector at INFN Laboratori Nazionali del Sud (Italy), are analysed in order to study properties of moderately excited systems (Ex=2-5 AMeV) formed in central collisions. By means of correlations between specific global variables, sensitive to the centrality of the collision, a stringent selection of Fusion-Evaporation residues, Multifragmentation sources and their decay products has been performed. The influence of the isospin contents of the systems on the reaction mechanism is carefully investigated and relevant observables such as isospin asymmetry N/Z or charge and mass of fragments, are discussed in order to probe the fragmentation path, characterised by short living ( ∼ 100fm/c) low density states of nuclear matter out of equilibrium. Preliminary comparisons with predictions of the BLOB model, in a semi-classical mean field framework, are presented, investigating cluster production emerging from the occurrence of low-density instabilities in central collisions.

The 02+ Hoyle state and few other excited levels of 12C are fundamental for the production of carbon in the universe. In particular, the γ decay branching ratio is of utmost importance, being the only way to produce a carbon at the ground state. For the purpose to precisely investigate the decay mechanism of such states we conducted an experiment, at Laboratori Nazionali del Sud-Istituto Nazionale di Fisica Nucleare (INFN-LNS), using the reaction α + 12 C at 64 MeV. We used the 4π CHIMERA detector to detect both α and γ 12 C decay channels. Details of the experiment and preliminary results are discussed in the paper.

The γ-decays of 12C excited levels (the Hoyle state 0+ at 7.65 MeV and the 9.64 MeV 3) are essential for its production in the universe. We present here a new attempt to precisely measure such γ-decay probabilities. The measurement was performed at INFN-LNS in Catania using the 4π CHIMERA multidetector. In order to measure these low probability decay-channels we performed 4-fold coincidence measurements. The 12C target nuclei were excited by using a beam of 64 MeV α-particles produced by the Superconducting Cyclotron (CS) of INFN-LNS. The scattered α-particles and the 12C recoils were detected and identified by? E-E and ToF methods using CHIMERA telescopes. The two emitted γ-rays in the decay chain were detected and identified by using the second stage of the telescopes, CsI(Tl) scintillators, by means of fast-slow and rise time techniques. Kinematics and energy-momentum conservation laws were used to constrain the data analysis. Also the 3-α decay channel probability was measured. Such a simultaneous measurement of all known decay channels was useful to reduce the systematic errors. Preliminary results of the data analysis are reported.

We describe the use of the 4tt CHIMERA charged particle detector as a large efficiency y-ray detector. The CsI(Tl) stage of the CHIMERA telescope is used to detect and identify y-rays. The high detection efficiency and the sufficient energy resolution guaranteed by CsI(Tl) allows us to use the detector for the study of rare decays. Two examples are reported: the low probability gamma decay (<10%) of the Pygmy resonance of a radioactive nucleus as the 68Ni; the measurement of the gamma decay probability of excited levels of 12C as the Hoyle state at 7.65 (∼10−4) MeV and the 3- level at 9.64 MeV (∼107), both important for the Carbon production in stars. Future experiments made possible at INFN-LNS by the availability of the new fragment separator FRAISE are also outlined.

Nuclear fission is a complex dynamical process, whose description involves the coupling between intrinsic and collective degrees of freedom, as well as different quantum-mechanical phenomena. For this reason, to this day it still lacks a satisfactory and complete microscopic description. In addition to the importance of describing fission itself, studies of the r-process in astrophysics depend on fission observables to constrain the theoretical models that explain the isotopic abundances in the Universe. To improve on the existing data, fission reactions of heavy nuclei in inverse kinematics are produced in quasi-free (p,2p) scattering reactions, which induce fission through particle-hole excitations that can range from few to tens of MeV. In order to study the evolution of the fission yields with temperature, the excitation energy of the fissioning system must be reconstructed, which is possible by measuring the four-momenta of the two outgoing protons. Performing this kind of experiment requires a complex experimental setup, providing full isotopic identification of both fission fragments and an accurate measurement of the momenta of the two outgoing protons. This was realized recently at the GSI/FAIR facility and some of the results obtained for the charge distributions are presented in this work.