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

Abstract

High-spin states in the 68164Er96 region were studied using 9Be + 160Gd reactions. Pulsed beam conditions were exploited for enhanced sensitivity to delayed γ-ray transitions. New isomers were identified in 161Dy, 163Ho, 162Er, and 165Er. The 162Er isomer is interpreted to decay by E1 transitions to the ground-state band with a reduced hindrance of f ν=33. A plot of fν values for all ΔK=7, E1 transitions from two-quasiparticle isomers to the ground-state bands 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 ground-state band. 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. © 2012 American Physical Society.