High-spin states in the neutron-deficient ${}^{71}\mathrm{As}$ nucleus have been studied using in-beam $\gamma$-ray spectroscopic techniques combined with mass identification. A new decay sequence of negative parity has been assigned to ${}^{71}\mathrm{As}$ and previously known sequences have been extended to higher spin and excitation. The new sequence has been identified as originating from the proton $f_{7/2}$ extruder orbital, which approaches the Fermi surface at large prolate deformations. Comparisons of experimental $B\left(M1\mathrm{}\right)/B\left(E2\mathrm{}\right)\mathrm{}$ ratios to theoretical expectations support this interpretation.

• Received 30 November 1998

DOI:https://doi.org/10.1103/PhysRevC.59.2919