New Insights Into the Structure of Neutron Rich Nuclei 157Sm, 163Gd, and 163Tb

Abstract

In continuation of nuclear structure studies in the neutron-rich rare earth region the isotopes of 157Sm, 163Gd and 163Tb have been investigated to establish, or expand, the ground state and low energy bands. Investigations of 157Sm were conducted with data from observations of 252Cf spontaneous fission collected by the Gammasphere in 2001 at Lawrence Berkeley National Lab. These data provided observation of 35 new transitions which have been identified extending the ground state and its signature partner band up to 29/2- and the first 5/2+ band and it's signature partner up to 37/2+ in 157Sm. Data for the study of 163Gd and 163Tb came from observations of the β-decay of 163Eu to 163Gd to 163Tb. These were collected with a Clover Array for Radioactive Decay Spectroscopy at the Low energy Radioactive Ion Beam Spectroscopy Station of the Holifield Radioactive Ion Beam Facility at Oak Ridge National Lab. For the structure of 163Gd 95 new transitions have been observed. The ground state has been identified as 7/2+, an isomeric band head at 1/2- has been proposed, and an analog to a previously postulated γ-vibrational band has been identified in the 3/2- band at 667 keV. Investigation of the structure of 163Tb has been performed confirming 3 previously tentative transitions and placing 13 previously observed but unplaced transitions into the level scheme. Additionally, 40 new transitions have been identified and placed within the structure along with 12 new levels. In the final chapter experimental details, which I helped to develop, are described for the study of fission dynamics and neutron rich nuclei from the spontaneous fission of 252Cf.