Experimental Investigations on the Nuclear Structure of the Neutron-Rich Nuclides ⁴⁴S and ²⁰O

Experimental results of two independent studies on the nuclear structure of the neutron-rich nuclei 44S and 20O are presented. A short introduction on the context of these studies within nuclear physics is given in chapter 1. Because of the fundamental differences between the experiments and analysis techniques the investigations have been separated in two chapters. The investigation of 44S, extracted via the two-proton knockout reaction from 46Ar with intermediate beam energy, is presented in chapter 2. Four new excited states are identified, of which the first 4+state presents evidence of deformation, as suggested by line-shape simulations of the detected γ rays. This is also indicated by a shell-model calculation, where the deformation of the first 4+state originates in a neutron particle-hole configuration which is fundamentally different from the "intruder"configuration producing the ground state deformation and from the configuration describing the relatively long-lived isomeric 0+state. Consequently, not three coexisting shapes, rather three coexisting configurations are found in 44S, corresponding to zero, one and two neutron particle-hole excitations. In chapter 3, results from the analysis of the 19O(d,p)20O reaction in inverse kinematics using the active gas target detector array ANASEN are presented. In order to study the location and fragmentation of the d3/2 orbital in 20O, a beam of the short-lived 19O was produced at the RESOLUT radioactive beam facility of the Florida State University. The ejected protons from the (d,p) reaction were measured with large solid angle coverage and for beam energies between 2.2 and 4.3 MeV/A. Data from the 17O(d,p)18O reaction was acquired to verify our experimental methods and analysis techniques.