Proton decay of the highly deformed nucleus Tb

The proton decay of the highly deformed nucleus Tb has been observed following bombardment of a Mo target with a 310 MeV beam of 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. Tb decays by the emission of a proton with energy E =1179(7) keV [Q = 1188(7) keV] and half-life t =0.94 transition is assigned to a highly deformed (β ∼0.3) J =7/2 configuration by comparing the proton decay rate with calculations for deformed nuclei.