Low temperature nuclear orientation measurements have been made to study the nuclear magnetic dipole moments of ${}_{}{}^{72}{}_{}{}^{}\mathrm{Br}_{}^{\mathit{g},}{}_{}{}^{}$m, ${}_{}{}^{73,74}{}_{}{}^{}\mathrm{Br}_{}^{\mathit{m}}{}_{}{}^{}$, ${}_{}{}^{75,76}{}_{}{}^{}\mathrm{Br}_{}^{\mathit{g}}{}_{}{}^{}$, and ${}_{}{}^{77}{}_{}{}^{}\mathrm{Br}_{}^{\mathit{g}}{}_{}{}^{}$ implanted into Fe. The analysis of the data has been performed within the framework of a two, nonzero field, site model to describe the occupation of Br nuclei in the host Fe lattice. The two sites were associated with magnetic hyperfine fields of ±81.38(6) and ±26(2) T. A spin of 1/2 for the ${}_{}{}^{73}{}_{}{}^{}\mathrm{Br}$ ground state is deduced and magnetic dipole moments are determined for the remaining nuclides. In addition, conversion electrons were observed for ${}_{}{}^{72}{}_{}{}^{}\mathrm{Br}$, confirming the multipolarity of the isomeric transition. An interpretation of the ground-state configurations and shapes of these isotopes is given using particle-rotor calculations and it is shown that the Br nuclides can be better described as a hole in the more deformed Kr nuclides rather than a particle beyond the Se cores.

• Received 1 May 1992

DOI:https://doi.org/10.1103/PhysRevC.46.2228