Microsecond yrast isomers were observed in the ${}^{125,127,129}\mathrm{Sn}$ isotopes. These nuclei are produced by thermal neutron induced fission of ${}^{233}\mathrm{U}$ and ${}^{239}\mathrm{Pu}.$ 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 isomers. In this paper, the decay schemes of the new ${19/2}^{+}$ yrast isomers in ${}^{125,127,129}\mathrm{Sn}$ are reported. The measured low-lying negative parity states are compared with the results of various calculations. This work suggests also the presence of high spin $\beta$ isomers in ${}^{127,129}\mathrm{In}.$

• Received 23 September 1999

DOI:https://doi.org/10.1103/PhysRevC.61.024312