Groundstate proton radioactivity of nuclei in the tin region
Proton radioactivities with decay energies of (0.98±0.08) MeV and (0.83±0.08) MeV were produced by the fusion reactions58Ni+58Ni→116Ba ⋆ and58Ni+54Fe→112Xe ⋆, and their halflives were measured to be (33±7) μs and (109±17) μs, respectively. The intensities of the lines correspond to production cross sections of about 30 μb and 40 μb. The two activities are assigned to the direct proton decay of113Cs and109I. The measured halflives are compared with values calculated ford5/2 andg7/2 groundstates of109I and113Cs and spectroscopic factors are deduced for the decays. An extensive search for the proton decay of105Sb, produced in the reaction50Cr(58Ni,p2n)105Sb, had a negative result, excluding decay energies between 0.5 MeV and 1.5 MeV for halflives between 10 ns and 5 s.