The presence of isospin mixing in the $T=5/2$ ground state of ${}^{71}\mathrm{As}$ was studied via anisotropic positron emission from oriented nuclei. A small isospin-forbidden Fermi component in the predominantly Gamow-Teller β decay was established, corresponding to an isospin mixing probability of $(13\pm 4)\times {10}^{-6}$. The sign of the magnetic moment of ${}^{71}\mathrm{As}$ was determined to be positive.

• Received 2 December 2004

DOI:https://doi.org/10.1103/PhysRevC.71.064310