Speaker
Description
The study of the density dependence of the nuclear equation of state (EOS) at densities above saturation plays a crucial role in understanding a wide range of physical phenomena, both astrophysical, such as the behaviour of neutron stars, and nuclear, such as the formation of the neutron skin. To this end, in March 2025 the ASY-EOS II experiment was conducted at the GSI laboratory in Germany, aiming to provide new and robust constraints on the symmetry energy term of the EOS. The 197Au+197Au reaction was studied at beam energies of 280, 400, 600, and 1000 AMeV using an experimental setup comprising the CHIMERA, KRAB, TOFD, and NeuLAND detectors. The four double rings of the CHIMERA multidetector, transported from the INFN Laboratori Nazionali del Sud (LNS) to GSI, were used in combination with the KRAB detector for reaction plane reconstruction and event centrality selection.
The TOFD detector consists of two structures, one placed along the beam direction and the other located at about 50° in correspondence with NeuLAND. The first TOFD structure was used for reaction centrality selection, while the second was employed as a veto for charged particles in relation to NeuLAND. The NeuLAND detector, composed by 1300 scintillator bars, enabled an effective separation between protons and other hydrogen isotopes, allowing for an accurate determination of neutron–proton observables, in particular elliptic flows. Particular attention was devoted to the calibration of the TOFD (veto) system and the NeuLAND detectors, as well as to techniques for discriminating between neutrons and charged particles; these will be presented.