The proton decay of the highly deformed nucleus ${}^{135}\mathrm{Tb}$ has been observed following bombardment of a ${}^{92}\mathrm{Mo}$ target with a $310\text{MeV}$ beam of ${}^{50}\mathrm{Cr}$ ions. This is the first instance of a proton-decaying isotope being produced via the $1p6n$ fusion-evaporation channel. Evaporation residues were separated in-flight using the Argonne fragment mass analyzer and implanted into a new design double-sided silicon strip detector. ${}^{135}\mathrm{Tb}$ decays by the emission of a proton with energy $E_p=1179\left(7\right)\text{keV}\left[Q_p=1188\left(7\right)\text{keV}\right]$ and half-life $t_{1∕2}={0.94}_{-0.22}^{+0.33}\text{ms}$. The transition is assigned to a highly deformed $\left({\beta }_2\sim 0.3\right)J^{\pi }=7∕2^{-}$ configuration by comparing the proton decay rate with calculations for deformed nuclei.

• Received 20 February 2004

DOI:https://doi.org/10.1103/PhysRevC.69.051302