Structure of 80Ge revealed by the β decay of isomeric states in 80Ga: Triaxiality in the vicinity of 78Ni

The decays of two long-lived low-lying isomeric states of 80Ga were studied at the PARRNe mass separator of the ALTO ISOL facility. Over the 75 γ rays previously attributed to the 80Ga decay, the decay time of 67 individual β-delayed γ activities were measured. This allowed the determination of the decay time of these two recently reported long-lived--actually β-decaying--states as well as to partially disentangle the two decay schemes. Thanks to the relatively high spin difference between these two 80Ga isomers spin assignments of the daughter 80Ge states could be further constrained rendering the comparison with calculations easier. From this comparison it appears that the suspected maximum of collectivity at Z = 32 along the N = 50 line should express itself through the coexistence of spherical and collective γ -soft structures.