High-spin states in $^{135}$Cs

High-spin states in $^{135}$Cs have been studied following the fission of the $^{226}$Th compound nucleus formed in a fusion-evaporation reaction ($^{18}$O at 91~MeV on $^{208}$Pb). The Gammasphere array was used to detect $\gamma$-ray coincidences. A sequence of transitions was observed in coincidence with the previously known 786.8-keV, $11/2^{+} \rightarrow 7/2^{+}$ transition from the 786.8-keV level of $^{135}$Cs extending the level scheme up to spin 23/2 and $\sim$3.3~MeV excitation energy. The assignment of this sequence to $^{135}$Cs is also supported by coincidences with known transitions in the complementary fragments. The observed experimental states are compared with states in the neighboring $^{137}$Cs nucleus, as well as with the states in the Z=54 core of $^{134}$Xe. The coupling of the odd proton occupying the $g_{7/2}$ orbital to the yrast states in $^{134}$Xe can account for the first excited states of $^{135}$Cs. This work was supported by the U.S. Department of Energy under Contracts No. DE-AC52-06NA25396 (LANL), DE-AC52-07NA27344 (LLNL) and AC03-76SF00098 (LBNL) and by the National Science Foundation (Rutgers).