Deseree Meyer Brittingham
This thesis addresses two very different topics. The first part explores the structure of 209Fr. Excited states in 209Fr were produced following the 176Yb(37Cl, 4n) reaction. Measurement of an excitation function was possible since data were taken at 173, 179, and 185 MeV. The SASSYER gas-filled spectrometer was used to separate recoiling fusion-evaporation products. Prompt and delayed gamma rays were detected with HPGe detectors at the target position and at the spectrometer focal plane, providing the first spectroscopic information about transitions in 209Fr. The decay from a proposed πi13/2 configuration isomer was observed in 209Fr, and its measured halflife was 446(14)ns. States above the isomer were also observed up to ∼2.6 MeV in this first spectroscopic study of 209Fr, and they are explained in the context of the trans-lead region.
The second part investigates the nature of 0+ excitations in transitional and deformed nuclei. They are not very well understood and have attracted new attention. Following a recent experiment studying 158Gd, 15 additional nuclei have been studied in the rare earth region with the (p, t) pickup reaction. Outgoing tritons were recorded at various lab angles, and their angular distributions are compared to those calculated using the distorted wave Born approximation (DWBA). Using the unique shape of the L = 0 angular distribution, more than double the number of 0 + states than were previously known are identified. The energy distribution of 0+ states and cross sections is discussed. The first experimental confirmation of a specific, inherent prediction of a first order phase transition is also addressed.