Synthesis of superheavy nuclei in the 48Ca+244Pu reaction: 288114

In the bombardment of a ²⁴⁴Pu target with ⁴⁸Ca ions, we observed two identical decay sequences of genetically linked events, each consisting of an implanted heavy atom, two subsequent α decays, and terminated by a spontaneous fission. The measured α energies and corresponding half-lives of the sequential chain members were E_α=9.84+/-0.05 MeV (T_1/2=1.9^+3.3_-0.8 s) and 9.17+/-0.05 MeV (T_1/2=9.8⁺¹⁸_-3.8 s) for the spontaneous fission (T_1/2=7.5⁺¹⁴_-2.9 s), the total energies deposited in the detector array were 213+/-2 and 221+/-2 MeV. The decay properties of the synthesized nuclei are consistent with the consecutive α decays originating from the parent even-even nucleus ²⁸⁸114, produced in the 4n-evaporation channel with a cross section of about 1 pb. ²⁸⁸114 and ²⁸⁴112 are the heaviest known α-decaying even-even nuclides, following the production of ²⁶⁰Sg and ²⁶⁶Sg (Z=106) and the observation of α decay of ²⁶⁴Hs (Z=108). The observed radioactive properties of ²⁸⁸114 and the daughter nuclides match the decay scenario predicted by the macroscopic-microscopic theory.