High-spin states in $^{83}$Se

High-spin states in $^{83}$Se 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. This is the first observation of high-spin states above the 9/2$^{+}$ ground state of this nucleus and extends the level scheme up to spin (17/2$^{+}$). The coupling of the neutron hole in the $g_{9/2}$ orbital, which forms the ground state of $^{83}$Se, to the 2$^{+}$ and 4$^{+}$ yrast states in the $^{84}$Se core can account for the first four high-spin states in $^{83}$Se. There is generally good agreement between the experimentally observed high-spin states and predictions of shell-model calculations. This work has been supported in part by the U.S. Department of Energy under Contracts No. W-7405-ENG-36 (LANL), AC03-76SF00098 (LBNL) and W-7405-ENG-48 (LLNL) and by the National Science Foundation (Rutgers).