In-beam γ-ray spectroscopy above ¹⁰⁰Sn using 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 ⁵⁸Ni+⁵⁴Fe and ⁵⁸Ni+⁵⁸Ni 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 ^108,109Te, ¹⁰⁹I, and ¹¹³Xe, where γ-ray transitions have been identified. In the case of ¹⁰⁹I, this represents the first observation of γ-rays from a ground-state proton emitter.