Lifetime measurements of levels in ${}_{}{}^{121}{}_{}{}^{}\mathrm{I}$, populated via the ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$${+}^{114}$Cd reaction at 51 MeV, have been undertaken using the recoil-distance (plunger) method. Transitions from the noncollective oblate (γ=+60°) state associated with band termination and from the collective oblate (γ=-60°) band head to prolate states have been observed to be significantly hindered; mean lifetimes of τ=(379±32) ps for the 39/$2^{\mathrm{-}}$ state at 5433 keV and τ=(83±17) ps for the 11/$2^{\mathrm{-}}$ state at 1327 keV, respectively, have been measured. In addition, a mean lifetime of τ=(273±10) ps was determined for the 11/$2^{\mathrm{-}}$ state at 811 keV.

• Received 5 January 1994

DOI:https://doi.org/10.1103/PhysRevC.49.1878