Synthesis of Superheavy Nuclei in the ⁴⁸Ca +²⁴⁴Pu Reaction

In bombardment of ²⁴⁴Pu with ⁴⁸Ca, we observed a decay sequence consisting of an implanted heavy atom, three subsequent α decays, and a spontaneous fission (SF), all correlated in time and position. The measured α energies and corresponding time intervals were E_α = 9.71 MeV ( Δt = 30.4 s), 8.67 MeV ( Δt = 15.4 min), and 8.83 MeV ( Δt = 1.6 min); for the SF ( Δt = 16.5 min), the total deposited energy was approximately 190 MeV. The α-particle energies together with the decay times and SF terminating the chain offer evidence of the decay of nuclei with high atomic numbers. This decay chain is a good candidate for originating from the α decay of the parent nucleus ²⁸⁹114, produced with a cross section of about 1 pb.