Interference between spherical and deformed states in 190Pb

The level scheme of 190Pb identified in the 166Er(28Si,4n)190Pb reaction includes several long isomers and exhibits structures which can be associated with co-existing spherical, oblate and prolate configurations. A chance near-degeneracy between 8+ states from the competing configurations causes mixing and fragmentation of the observed E3 and E2 decays from the yrast 11− and 10+ states, through interference. The candidate identified for the prolate band is approximately 500 keV higher than that observed in 188Pb.