Radioactive Decay of 23-min Sb131 to Levels of Te131

The levels of $^{131}\mathrm{Te}$ have been investigated by studying the $\ensuremath{\gamma}$ rays following the $\ensuremath{\beta}$ decay of 23-min $^{131}\mathrm{Sb}$ using Ge(Li) detectors. The $^{131}\mathrm{Sb}$ sources were produced by rapid separation of Sb from $^{235}\mathrm{U}$ thermal-neutron-fission products. 60 $\ensuremath{\gamma}$ rays attributed to $^{131}\mathrm{Sb}$ decay have been observed and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence relationships have been obtained for the prominent lines. A level scheme has been constructed which incorporates 40 of these $\ensuremath{\gamma}$ transitions between 23 levels in $^{131}\mathrm{Te}$. This level scheme is compared with the level structure of other odd-$A$ Te isotopes and is discussed within the framework of the pairing-plus-quadrupole model.