Fusion reaction Ca48+Bk249 leading to formation of the element Ts (Z=117)

The heaviest currently known nuclei, which have up to 118 protons, have been produced in 48Ca induced reactions with actinidetargets. Among them, the element tennessine (Ts), which has 117 protons, has been synthesized by fusing 48Ca with the radioactive target 249Bk, which has a half-life of 327 d. The experiment was performed at the gas-filled recoilseparator TASCA. Two long and two short α decay chainswere observed. The long chains were attributed to the decay of 294Ts. The possible origin of the short- decay chainsis discussed in comparison with the known experimental data. They are found to fit with the decay chainpatterns attributed to 293Ts. The present experimental results confirm the previous findings at the Dubna Gas-Filled RecoilSeparator on the decay chainsoriginating from the nuclei assigned to Ts. (Less)