Measurement of proton-evaporation rates in fusion reactions leading to transfermium nuclei

The analysis of fission events following the implantation of evaporation residues produced in the fusion reaction of 50Ti and 209Bi at different bombarding energies has revealed 5 millisecond decays, which are attributed to the spontaneous fission of proton-evaporation channels. The average cross sections for proton evaporation are found to be ∼100 and 10 times smaller than the largest neutron-evaporation channel cross section at the same excitation energy. These results suggest that the proton evaporation channel, albeit weak, may represent a realistic alternative to synthesize new, more neutron rich super heavy nuclei.