Rotational sidebands in 166Er

Rotational sidebands in ¹⁶⁶Er were observed using the 24 MeV ¹⁶⁴Dy(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.