Discovery of isomers in dyprosium, holmium and erbium isotopes with N=94 to 97

High-spin states in the 164 68Er96 region were studied using Be + Gd reactions. Pulsed beam conditions were exploited for enhanced sensitivity to delayed γ-ray transitions. New isomers were identified in Dy, Ho, Er and Er. The Er isomer is interpreted to decay by E1 transitions to the ground-state-band (g.s.b.) with a reduced hindrance of fν=33. A plot of fν values for all ∆K=7, E1 transitions from two-quasiparticle isomers to the g.s.b. of even-even nuclei reveals only a small influence from the dynamic to kinematic moment-of-inertia ratio, which provides a measure of Coriolis K-mixing within the g.s.b. This is interpreted to imply that the relatively low hindrances are due to K-mixing in the isomer, caused by a combination of Coriolis and octupole band mixing.