Complex band interactions in 170Er -: art. no. 021305

Inelastic excitation of Er-170 by a U-238 beam, studied at near-barrier energies, has led to the observation of unusual features in rotational bands built on low-lying vibrations. The population of the high-spin members of the K pi = 0(+), beta-vibrational band is enhanced due to mixing with the K-pi = 2(+), gamma-vibrational band at spin 4(+). Strong mixing of the K-pi=0(+) band with a rotationally aligned 2 qp band results in this band losing its beta-vibrational character and in a rapid gain in spin alignment leading to a crossing with the ground-state band between spins 20(+) and 22(+). The low-lying K-pi = 3(+) band also is populated. It subsequently decays to both the gamma-vibrational and the ground-state bands. The occurrence of appreciable K-forbidden E2 transitions from the K-pi = 3(+) to the ground-state band is attributed to mixing with the K-pi=2(+) band, caused by the interaction between the quadrupole gamma-vibrational and the hexadecapole vibrational motions.