Rotational sidebands in 166Er

Rotational sidebands in 166 Er were observed using the 24 MeV 164 Dy(α, 2nγ) reactions. The ground-state band was observed up to spin 16 + and does not backbend. A strong backbend is, however, observed in a K π = ( O + ) sideband, indicating that the 12 + state of the previously unknown S-band is at 2656 keV. The γ-band shows significant rotational alignment above I = 10 + . Levels of at least two negative-parity bands, one of which is primarily the K π = 2 − octupole vibration, are also observed.