Decay properties of low- and high-spin beta-decaying isomers in ¹⁴⁶La

The properties of neutron-rich nuclei in the fission-product region are of significant interest to the nuclear-structure and astrophysics fields. These data are also of importance to various applied areas, such as reconstruction of antineutrino spectra for non-proliferation applications and accurate determination of fission product yields. We have studied the beta-decay properties of ¹⁴⁶La using the high-purity beams provided by the ANL CARIBU facility and the recently commissioned Gammasphere decay station. For the first time, comprehensive decay schemes for the low- and high-spin isomers in ¹⁴⁶La were established and these were found to differ significantly compared to what is presently available in the literature. The spins of the ground and isomeric states were also re-evaluated, and the proposed new values are consistent with the presence of deformed shapes in ¹⁴⁶La. Results from these measurements will be presented, together with predictions based on deformed shell model calculations.