HIGH-K STRUCTURE IN AS-77

High-spin states in As-77 have been studied via the Ge-76(alpha,p2n) r eaction. Proton-gated excitation functions extracted from measured gam ma-ray yields at beam energies of 32, 36, and 40 MeV and an additional gamma-gamma coincidence measurement at 40 MeV have been used to assig n new gamma-ray decay sequences to As-77. In particular, a positive-pa rity sequence up to spin 25/2 and a high-lying Delta I=1 sequence up t o 21/2 and of probably negative parity have been found to decay into t he known 9/2(+) isomer at 475.5 keV. Nuclear-shape calculations show a triaxial shape for the positive-parity states with moderate quadrupol e deformation. The high-lying negative-parity sequence is interpreted as a high-K three-quasiparticle band similar to bands in adjacent nucl ei.