Strongly perturbed positive-parity bands in odd-mass erbium isotopes

Alpha-particle irradiation of enriched dysprosium targets has been used to populate states in 161Er, 163Er and 165Er. Cascade and crossover transitions are observed within a strongly perturbed rotational band which is populated up to spin 252. The observed band structure can be understood to be the lowest-energy band which results from strong coupling through the Coriolis force of the Nilsson orbitals 12+[660], 32+[651], 52+[642], 72+[633] and 92+[624]. The wave functions are calculated from a fit to the experimental energies and the theoretical and experimental transition probabilities are compared. Rotational bands built on the intrinsic states 32−[521], 52−[523] and 112−[505] are also observed.