In-beam γ-ray spectroscopy aboveSn100using the new technique of recoil decay tagging

A novel method of selecting γ-ray transitions in heavy nuclei (A>100) at the proton drip-line has been attempted. The characteristic charged-particle radioactivity of these nuclei (alpha decay, ground-state proton decay, and β-delayed proton emission) has been used to tag γ-ray transitions recorded by the highly efficient Eurogam spectrometer. The ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ ${+}^{54}$Fe and ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ ${+}^{58}$Ni fusion-evaporation reactions, at a beam energy of 240 MeV, have been used to populate specific states of these neutron-deficient nuclei and results are presented for ${}_{}{}^{108,109}{}_{}{}^{}\mathrm{Te}$, ${}_{}{}^{109}{}_{}{}^{}\mathrm{I}$, and ${}_{}{}^{113}{}_{}{}^{}\mathrm{Xe}$, where γ-ray transitions have been identified. In the case of ${}_{}{}^{109}{}_{}{}^{}\mathrm{I}$, this represents the first observation of γ-rays from a ground-state proton emitter.