Synthesis and properties of even-even isotopes with Z = 110-116 in 48Ca induced reactions

The paper presents results on the synthesis of superheavy nuclides with Z= 114 and 116 in the fusion reactions with 48Ca ions. In the irradiation of targets made from enriched 244Pu and 248Cm isotopes with beam doses of 1.5 x 1019 and 2.3 x 1019, respectively, the detector array situated in the focal plane of the gas-filled separator registered heavy atoms of new elements undergoing sequential α decays terminated by spontaneous fission. The time of the decay chains is approximately one minute. Decay properties of the synthesized nuclei are consistent the consecutive α decays originating from the parent nuclides 288114 and 296116 produced in the 4n-evaporation channels with the cross section of about a picobarn. Comparison of TSF and Tα values for the nuclei with Z = 110 and 112 with those obtained earlier for lighter isotopes of these element points to an enhanced stability of heavy nuclei with an increase in the neutron number. The α - decay energies Qα measured experimentally in the chains 116-α1 - 114-α2 - 112-α3 - 110 are compared with theoretical predictions of different nuclear models. This comparison shows that the difference between the experiment and theory is in the range of ± 0.5 MeV. From this it follows that the theoretical models predicting the decisive influence of the nuclear structure on the stability of superheavy elements are well-founded not only qualitatively but in some sense also quantitatively. The prospects of further investigations in the field of superheavy nuclei are discussed briefly. (author)