Yrast states of neutron-richN=83nuclei from fission productγ-ray studies

Prompt $\gamma$-ray cascades in $N=83\mathrm{}$ fission product nuclei near ${}^{132}$Sn have been studied at Eurogam II using a ${}^{248}$Cm source. Cross coincidences observed between $\gamma$ rays from complementary light and heavy fission fragments were vital for isotopic assignments. Yrast states in the $N=83\mathrm{}$ isotones ${}^{134}$Sb, ${}^{135}$Te, and ${}^{136}$I are reported. The interpretation of the level schemes is based mainly on results of shell model calculations using empirical proton-proton interaction energies from ${}^{134}$Te, and proton-neutron interactions estimated from the well-known ${}^{210}$Bi level spectrum.