In this work, microsecond isomers of the three neutron hole nuclei ${}^{129}\mathrm{Sn}$ and ${}^{130}\mathrm{Sb}$ were investigated. These nuclei were produced by the thermal neutron induced fission of ${}^{239}\mathrm{Pu}$ and ${}^{241}\mathrm{Pu}.$ The detection is based on time correlation between fission fragments selected by the LOHENGRIN spectrometer at ILL (Grenoble) and the $\gamma$ rays or conversion electrons from the isomers. The results include the identification of the $\nu {(h}_{11/2}^{-2}{d}_{3/2}^{-1}{)23/2\mathrm{}}^{+}$ aligned isomer in the odd ${}^{129}\mathrm{Sn}$ and the $\left[\pi g_{7/2}\nu {(h}_{11/2}^{-2}{d}_{3/2}^{-1}\right)]{13}^{+}$ isomer in the odd-odd ${}^{130}\mathrm{Sb}$ and their decay schemes. The interpretation of the level schemes is mainly based on a truncated shell model calculation using empirical two-body interactions. Several new $B\left(E2\mathrm{}\right)\mathrm{}$ strengths of isomeric transitions were measured and are discussed in the paper.

• Received 20 September 2001

DOI:https://doi.org/10.1103/PhysRevC.65.034322