Experimental cluster production in heavy-ion collisions: a terrestrial tool to understand stellar phenomena.

Knowledge of the nuclear equation of state, NEOS, is one of the central issues in nuclear physics. This includes the fundamental properties of the nuclear environment, which is present not only on Earth but also in many objects and astrophysical phenomena. The magnitude of the NEOS N/Z component, the symmetry energy, is not precisely known.
Nuclear equation of state plays a fundamental role in the understanding of core-collapse supernovae,
mergers of compact stars and cooling proto-neutron stars for example. In the collapse of the supernova, the accretion of matter forms the central object called the proto-neutron star, which cools by a neutrino emission process. Much of this process takes place at the surface which is composed of hot, low-density, neutron-rich matter. The presence of clusters and the magnitude of the symmetry energy influence the cooling process. Heavy ion collisions are the only way to create high-density and low-density nuclear material in the form of laboratory clusters. The main issues are therefore as follows: (1) what is the equation of state of asymmetric nuclear material? (2) How does low-density nuclear material cluster? As a matter of fact, a crucial aspect that has not been much explored so far is the tendency of the material to be clustered at very low density. This phenomenon, which is predicted by certain theoretical approaches, would have a profound influence on the equation of state at densities and temperatures of astrophysical interest. The correct description of such « clustering » depends on another major unknown: how do environmental effects modify the structural properties (binding energy etc.) of light nuclei (d, t, 3He, α, 6Li, etc.)?
The subject concerns an experiment at GANIL/SPIRAL2 using the INDRA multi-detector coupled to the
FAZIA demonstrator. The experiment involving 192 telescopes (silicon/silicon/CsI(Tl)) for FAZIA and 240
telescopes (from 14 to 45 degrees: ionization chamber/silicon/CsI(Tl) and from 45 to 176 degrees: ionization chamber/CsI(Tl)) for INDRA. The experiment was done in 2019 and another one is scheduled in 2021. Data from older INDRA experiments will also be analyzed in the project.
The thesis will be composed of data analysis, model comparison and also experiment preparation phases within the European FAZIA collaboration.