Recent results and highlights from the CHIMERA Collaboration

The CHIMERA Collaboration uses three main devices in its experimental activities: the CHIMERA 4π detector, the FARCOS correlator (Femtoscope Array for Correlation and Spectroscopy) and the new NARCOS plastic scintillators array prototype for neutrons and light charged particles detection. We discuss two recent examples of physics results obtained with these devices: the first one will focus on the AsyEos-II experiment that studies the EoS (Equation-of-State) of neutron rich matter at high baryon densities. The AsyEos-II experiment will be realized in 2025 at GSI/FAIR and it proposes to probe the EoS at densities around 2ρ0 in Au+Au collisions and beam incident energies from 250 to 800MeV/A. The second one, in the Fermi energy regime, studies dynamical emission of particles at 20MeV/A beam energy as a function of projectile and target isospin (CHIFAR experiment). Contributions of the CHIMERA Collaboration for the diagnostic and tagging system of the FraISe facility at LNS based on SiC (Silicon Carbide) technology and recent advances of the NARCOS array project will be briefly discussed

Investigations of structure effects in heavy-ion fusion above the Coulomb barrier

We investigated the occurrence of nuclear structure effects in the fusion of heavy ions at above-barrier energies. To unveil the presence of such tiny effects, we developed a semi-classical model based on the modified Sum-of-Difference method of nuclear reactions, able to reproduce the gross trend of the whole database available to date. The deviations between the model predictions and the data can be linked, at low bombarding energies, to the occurrence of shell closures; at larger energies, such effects are washed out, while phenomena due to the cluster structure of projectile or target are observed

Hidden puzzle of the correlation femtoscopy at the top RHIC and LHC energies and its possible solution

Two paradoxical results (puzzles) related to correlation femtoscopy of high-energy nucleus-nucleus collisions at the RHIC and the LHC accelerators are considered within the integrated hydrokinetic model (iHKM), describing all the stages of the produced system’s evolution —from the initial non-equilibrium partonic state formation to the final expansion of interacting hadron-resonance gas. Possible solutions of the analyzed puzzles are proposed

Search for collective behavior in very small and in large systems

Signs of collectivity were initially seen in AuAu collisions at RHIC through measurements of two-particle long-range correlations in (pseudorapidity) Δη, within small (azimuthal) Δφ angles. In 2010 a similar ridge-like behavior was observed in high multiplicity pp collisions at 7 TeV at the LHC by CMS, extended afterwards also to pPb and PbPb collisions. In addition, several orders of anisotropic flow Fourier harmonics were measured later, showing a collective behavior compatible with hydrodynamic expectations. This posed the question about the threshold on system size and conditions for collectivity to arise. Signs of possible collectivity were then searched for in e+e− and ep at LEP, in γpandγAattheLHC,but usually limited to lower multiplicity ranges (< 40 particles per event), where collectivity was not expected, with negative results. However, more recent investigations with higher multiplicity data collected with the ALEPH experiment at LEP II energies seem to indicate a different picture. This talk shows recent results from the CMS Collaboration for two extreme sizes of colliding systems. On the lowest side, the results focus on the search for a ridge-like behavior in high multiplicity pp collisions at 13 TeV inside a single jet, originated from a highly energetic parton. On the other extreme, PbPb collisions at √ sNN = 5.02 TeV are employed to probe deeper into the quark-gluon plasma formed in such collisions, by measuring the speed of sound and the effective temperature in this medium

NArCoS: A new correlator for neutrons and charged particles with high angular and energy resolution (Neutron Array for Correlation Studies)

An overview concerning the electronic frontend and readout system for the first version prototype of the neutron correlator NArCoS is reported. The proposed prototype of electronic is designed for the next source and beam commissioning experiments like CROSSTEST performed in November 2023 at LNL

Strumenti legali per l’incentivazione della stabilità aziendale e degli investimenti a lungo termine: un’analisi comparata del voto maggiorato in Francia

Il policy brief esamina il voto maggiorato, introdotto in Francia nel 2014 con la Legge Florange e successivamente in Italia, come strumento per incentivare la stabilità aziendale e promuovere investimenti a lungo termine. In Francia, il voto maggiorato è stato reso automatico, a meno che le imprese decidessero di rinunciarvi. Tuttavia, le analisi sulle cento principali aziende francesi hanno mostrato che questa legge non ha avuto un impatto significativo sulle loro performance economiche, come redditività o valore di mercato. In Italia, il voto maggiorato è stato introdotto nel 2014 e rafforzato nel 2024, con l’obiettivo di facilitare la quotazione delle imprese italiane in borsa senza perdere il controllo gestionale. A differenza della Francia, in Italia il voto maggiorato è applicato solo se deciso dall’assemblea degli azionisti. L’esperienza francese suggerisce che, da solo, il voto maggiorato non garantisce effetti positivi. Per renderlo più efficace in Italia, si raccomanda di affiancarlo a incentivi per gli investitori, monitorare attentamente i risultati della normativa e introdurre misure che migliorino la governance aziendale e attraggano nuovi capitali, creando un ambiente favorevole alla crescita sostenibile delle imprese

Deuteron-Ξ correlation function studied with three-body model

Many-baryon forces play a crucial role in shaping the structure and dynamics of many-baryon systems. Utilizing three-body correlation functions in femtoscopy offers a promising tool for probing three-baryon forces. However, the dynamics of three-body systems necessary for obtaining these correlation functions remains incompletely understood. In this study, we employ the continuum-discretized coupled channels method, a precise and cost-effective three-body model, to explore the influence of deuteron excitation to its continuum states on the deuteron-Ξ correlation function. Our findings reveal that the deuteron-Ξ interaction derived from lattice quantum chromodynamics does not yield a bound state. Moreover, we determine that the effect of deuteron excitation leads to less than a 10% increase in the correlation function, suggesting the predominance of direct deuteron formation through heavy-ion collisions. Overall, our work lays the groundwork for further investigations aimed at elucidating many-baryon forces

The equation of state of nuclear matter above saturation density from intermediate energy heavy-ion collisions

The dcQMD transport model has been used to study different aspects of the in-medium nucleon-nucleon interaction, in particular the equation of state of nuclear matter by comparing theoretical predictions for nucleonic (stopping, directed and elliptic flows) and pionic (charged multiplicity ratio) observables in heavy-ion collisions at intermediate impact energies to available experimental data measured by the FOPI and SπRIT Collaborations, respectively. These studies have demonstrated the feasibility of constraining the equation of state of both symmetric and asymmetric matter up to twice the saturation density with unprecedented accuracy. Precise values for the compressibility modulus of symmetric matter and slope and L = 63+10 of the symmetry energy were extracted from nucleonic flow data: K0 = 230+9 −11 MeV −13 MeV at 68% CL. The study of charged pion spectral ratios has led to L =79.9±37.6 MeV in full agreement with nucleonic observables. Perspectives on improving the accuracy of these results and probing higher densities with heavy-ion collisions are also discussed

Energia, sicurezza e transizione verde: una roadmap per il Mediterraneo

Il Mediterraneo si trova al centro di dinamiche energetiche, ambientali e geopolitiche sempre più complesse. La transizione verso fonti rinnovabili, accelerata dalla crisi climatica e dai conflitti recenti (Ucraina, Israele-Gaza), si intreccia con l’urgenza di garantire sicurezza energetica e stabilità regionale. Questo policy brief analizza la struttura della produzione e del consumo energetico nell’area, evidenziando come i paesi MENA restino fortemente dipendenti dai combustibili fossili, mentre in Europa cresce l’impiego di rinnovabili, pur con persistenti vulnerabilità. Il potenziale solare dell’area mediterranea è significativo, ma sfruttato in modo disomogeneo. Le misure di sostegno alla decarbonizzazione – tra cui investimenti europei nel solare, eolico e idrogeno verde – si accompagnano a politiche emergenziali sui prezzi e a progetti transfrontalieri strategici (es. ELMED-TUNITA). Tuttavia, la transizione energetica presenta anche sfide economiche e sociali, soprattutto per i paesi esportatori di idrocarburi del Sud. Il documento propone una serie di raccomandazioni chiave di policy: sviluppare partenariati euro-mediterranei per le rinnovabili; istituire un quadro comune per la transizione; rafforzare la sicurezza energetica tramite diversificazione e interconnessioni; promuovere una transizione giusta e inclusiva; integrare energia, acqua e cibo nelle strategie climatiche; allineare politiche energetiche e stabilità geopolitica. Una governance condivisa e multilivello della transizione energetica nel Mediterraneo è fondamentale per coniugare sostenibilità ambientale, inclusione sociale e sicurezza internazionale

WLS System for the Pressurized Helium Calorimeter ``PHeSCAMI''

The possible presence of low-energy anti-deuterons in cosmic rays is a golden channel to test the antimatter asymmetry in the Universe or to identify annihilating Dark Matter particles in the galactic halo. The PHeSCAMI (Pressurized Helium Scintillating Calorimeter for AntiMatter Identification) project aims to study a new signature for the identification of anti-deuteron and anti-protons in cosmic rays. In particular, when a Z=-1 heavy antiparticle is stopping in Helium, it can produce an exotic atom having lifetime of microseconds. Helium gas is a fast scintillator, thus a relatively simple calorimetric measurement of the stopping particle kinetic energy is possible. A two-stage Wavelength Shifter (WLS) system is necessary to convert the VUV (80 nm) scintillation light into visible. The perfor mances of the FB118 WLS, manufactured by “Glass to Power”, are investigated. A promising usage of FB118 as a high-efficiency Cherenkov radiator is also inferred