An Investigation into quasi-free scattering of light neutron-rich nuclei around N=14

Abstract

In August 2010, the S393 experiment was performed at the laboratory GSI Helmholtzzentrum für Schwerionenforschung, in Darmstadt, Germany. The main goal of this experiment was to study light neutron-rich nuclei using inverse and complete kinematic measurements via quasi-free scattering reactions at relativistic energies. In about twenty days, data for six different settings centred at different A/Q ratios, were collected in the LAND-R3B experimental area at Cave C. An 40Ar primary beam was accelerated in the SchwerIonenSynchrotron (SIS-18) up to an energy of about 490 MeV/u. The beam was then directed to the FRagment Separator area (FRS) where using a beryllium production target a secondary beam produced via fragmentation was selected depending on the A/Q ratio of the desired species. Following this selection, the isotopes of interest were guided to Cave C, where the reaction target and the detectors needed for the analysis were located. Two key observables have been studied with an aim to shed light upon the structure of these nuclei. The inclusive cross sections and transversal momentum distributions for the (p,pn) channels reveal a change in the structure of these nuclei when we move from the N=14 to the N=15, i.e. from the 0d5/2 shell to the 1s1/2. For the (p,2p) reactions, the measurement of the same observables allowed the study for the 0p3/2, 0p1/2 proton shells. The comparison of the experimental data with the theoretical calculations allowed to extract spectroscopic information for the neutron shell for the projectiles 21N and 22O.