β-decay spectroscopy of the light rare-earth nuclei ¹⁵⁸Pm and ¹⁶⁰Sm

Probing the intrinsic and collective structure of nuclei in the light rare-earth region, provides important insight into the evolution of nuclear deformation and the properties of neutron-rich nuclei. This understanding is critical for exploring the formation of the rare-earth peak in the r-process abundance pattern, where new data can influence constraints on the astrophysical sites and conditions. The odd-odd nucleus ¹⁵⁸Pm is a particularly interesting case as a predicted isomeric state has yet to be clearly established and its lifetime determined (T_1/2 >16μs). Investigating such isomers is critical to determining their structure as well as to remove ambiguities that can arise in direct mass measurements. To investigate this region a β-decay experiment was performed at ANL which combined the HPGe detectors of X-Array with the SATURN tape system. Radioactive ions produced by the CARIBU facility were isobarically separated and delivered to the decay station and βγγ-coincidence measurements performed. Tape cycles were optimized for the decay of ¹⁵⁸Pm and ¹⁶⁰Sm. Preliminary results and a summary of ongoing analysis will be presented.