Shape coexistence and high-K states in 74Se populated following the β decay of 74Br

Excited states in Se-74 were populated following the epsilon/beta(+) decay of Br-74, mainly from the J = K = 4, 13.8-keV beta-decaying isomer. Off-beam gamma-ray spectroscopy was performed with the array of Clover HPGe detectors at WNSL Yale. Many new transitions were observed and rigorous spin assignments were made based on gamma-gamma angular correlations. The beta-decay strength was found to proceed almost entirely to a few high-lying states near 4500 keV, which are consistent with deformed two-quasineutron high-K configurations. These doorway states then provide an effective tool for populating and identifying the lower prolate structures. Once categorized, the low-lying states of Se-74 can be described as a set of near-spherical vibrational levels mixing strongly with a spectrum of prolate states which have an unperturbed bandhead near 1350 keV. DOI: 10.1103/PhysRevC.87.014307