Synthesis and properties of even-even nuclei with Z=114-116 produced in 48Ca induced reactions

In the irradiation of targets made from enriched Pu-244 and Cm-248 isotopes with beam doses of 1.5 x 10(19) and 2.3 x 10(19), respectively, the detector array situated in the focal plane of the gas-filled separator registered heavy atoms of new elements undergoing sequential a decays terminated by spontaneous fission. The time of the decay chains is approximately 1 min. Decay properties of the synthesized nuclei are consistent with the consecutive a decays originating from the parent nuclides (288)114 and (292)116 produced with the cross section of about 0.5 picobarn. Comparison of T-SF and T-alpha values for the nuclei with Z = 110 and 112 with those obtained earlier for more light isotopes of these elements points to an enhanced stability of heavy nuclei with an increase in the neutron number. The alpha-decay energies Q(alpha), measured experimentally in the chains 116 -->(alpha1) 114 -->(alpha2) 112 -->(alpha3) 110, are compared with theoretical predictions of different nuclear models. 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. Some preliminary data, obtained in the first experiment aimed at the synthesis of element 118 in the reaction Cf-249 + Ca-48, are presented in the paper. The prospects of further investigations in the field of superheavy nuclei are discussed briefly.