Spectroscopy of Heavy Nuclei with GAMMASPHERE

We report on analysis of data from a recent experiment carried out using the ATLAS heavy-ion accelerator facility at Argonne National Laboratory. A beam of \hspace{2pt}$^{208}$Pb was incident on a $^{244}$Pu target evaporated on a $^{197}$Au backing. The target and projectile nuclei were mutually excited to high-energy states via inelastic collisions. The GAMMASPHERE detector array, made up of 108 Compton-suppressed germanium detectors positioned in a spherical geometry around the target, was used to detect the resulting gamma radiation as the nuclei decayed to ground state. The data from the experiment was then sorted into a three-dimensional $\gamma$-$\gamma$-$\gamma$ ``cube,'' which was analyzed using gating techniques in Radware software to investigate the decay structure of the excited nuclei produced by the experiment. A two-dimensional ``matrix'' was also created using an early-delayed technique, allowing for short-lived isomers produced in-beam to be observed. This data was analyzed using time gates to measure half-lives of observable isomers. Results will be presented and discussed.