In this work the microsecond isomers in ${}^{129}\mathrm{In}$ and ${}^{129}\mathrm{Sb}$ were investigated. These nuclei were produced by the thermal-neutron-induced fission of ${}^{241}\mathrm{Pu}.$ The detection is based on a time correlation between the fission fragments selected by the LOHENGRIN spectrometer at the ILL (Grenoble) and the $\gamma$ rays or conversion electrons from the isomers. The decay schemes of the new ${17/2}^{-}$ isomer in ${}^{129}\mathrm{In}$ and ${23/2}^{+}$ isomer in ${}^{129}\mathrm{Sb}$ are reported. A shell-model study of these two nuclei was performed using a realistic effective interaction derived from the CD–Bonn nucleon-nucleon potential. Comparison shows that the calculated energy levels and electromagnetic transition rates are in very good agreement with the experimental data.

• Received 5 March 2003

DOI:https://doi.org/10.1103/PhysRevC.67.054312