Study of the magicity of 13B nucleus through quasi-free reaction 13B(p,pn)12B

by Antoine Barriere

Abstract: The aim of this internship is to study for the first time the magicity (N=8) of the 13B nucleus, using the Quasi-free scattering reaction 13B(p,pn)12B. This experiment was carried out at GSI (Germany), using the Cristall Ball for the detection of knocked-out light particles and gamma-rays, the Aladin focal plane for the detection of the B residues, and the LAND detector array for the detection of neutrons, when 12B is produced in an unbound state.  In case of a strong N=8 shell closure, mostly the p orbits will be filled and the valence s and d orbitals will be very weakly populated, contrary to the 12Be isotone where magicity collapsed. As most of the states of interest in 12B are already known, the present analysis focuses on determining cross sections and occupancy values across the neutron Fermi surface. If proven that the ground state of 13B is spherical, it would be an ideal tool to identify the spherical states in 12Be through 13B(p,2p)12Be reaction, as done in the PhD thesis of A. Kamenyero.