Synthesis of superheavy nuclei in the 48Ca+244Pu reaction:: 288114 -: art. no. 041604

In the bombardment of a Pu-244 target with Ca-48 ions, we observed two identical decay sequences of genetically linked events, each consisting of an implanted heavy atom, two subsequent alpha decays, and terminated by a spontaneous fission. The measured alpha energies and corresponding half-lives of the sequential chain members were E-alpha = 9.84 +/- 0.05 MeV (T-1/2 = 1.9(-0.8)(+3.3) s) and 9.17 +/- 0.05 MeV (T-1/2 = 9.8(-3.8)(+18) s); for the spontaneous fission (T-1/2 = 75(-2.9)(+14) 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 a decays originating from the parent even-even nucleus (288)114, produced in the 4n-evaporation channel with a cross section of about 1 pb. (288)114 and (284)112 are the heaviest known alpha-decaying even-even nuclides, following the production of (260)Sg and (266)Sg (Z = 106) and the observation of alpha decay of (264)Hs (Z = 108). The observed radioactive properties of (288)114 and the daughter nuclides match the decay scenario predicted by the macroscopic-microscopic theory.