High-K structure in ⁷⁷As

High-spin states in ⁷⁷As have been studied via the ⁷⁶Ge(α,p2n) reaction. Proton-gated excitation functions extracted from measured γ-ray yields at beam energies of 32, 36, and 40 MeV and an additional γ-γ coincidence measurement at 40 MeV have been used to assign new γ-ray decay sequences to ⁷⁷As. In particular, a positive-parity sequence up to spin 25/2 and a high-lying Δ1= 1 sequence up to 21/2 and of probably negative parity have been found to decay into the known 9/2 + isomer at 475.5 keV. Nuclear-shape calculations show a triaxial shape for the positive-parity states with moderate quadrupole deformation. The high-lying negative-parity sequence is interpreted as a high-K three-quasiparticle band similar to bands in adjacent nuclei.