The Structure of the Neutron-Rich 22O and 23F Nuclides

This thesis reports on the measurements of the nuclear structure of the light neutron rich 22O and 23F nuclides. The excited states of 23F were studied via a one-neutron removal reaction, using the high-resolution γ-ray detector array, GRETINA, coupled to the
S800 spectrometer at NSCL. Several new transitions have been observed in the γ-ray spectrum and by performing γ-γ coincidence analysis, an extended level scheme has been built for 23F. Additionally, the relative populations of the excited states and branching ratios were studied using detailed Monte Carlo GEANT4 simulations and the spin assignments were determined through the analysis of the γ-ray angular distributions. These findings were compared to the calculations from the phenomenological USD-type interactions, where it was found that the USDB calculations were the most consistent with the experimental data
on the structure of 23F.

The experiment to measure the electromagnetic transition rates in 22O was carried out at ANL, using the GRETINA array coupled to the FMA. A novel 10Be target was developed in order to populate the excited 22O recoils via the 14C(10Be,2p)22O fusion-evaporation reaction. The molecular plating technique was used to prepare the 10Be target on a thin platinum backing, however a low deposition yield of about 20% significantly reduced the 10Be content to be between 22-32 µg/cm2 . The measured rates of the 22O recoils were too low for the DSAM technique, with a potential 3199 keV transition of 14 ± 5 counts being observed in a single experimental setting. The analysis of the stronger exit channels of the fusion evaporation reaction, namely 21O and 22Ne, suggested that the low rates of the 22O could be primarily attributed to the low recoil acceptance into the FMA.