Synthesis of Superheavy Nuclei in 48Ca Induced Reactions

Abstract

The paper presents results on the synthesis of superheavy nuclides with Z=114 and 116 produced in the fusion reactions with 48Ca ions, performed within the JINR-LLNL collaboration in 2000-2001 using the heavy ion accelerator U-400 of the Flerov Laboratory of Nuclear Reactions (Dubna).In the irradiation of targets made from enriched 244Pu and 248Cm isotopes with beam doses of 1.5·1019 and 2.3·1019, 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 range of the decay chains is approximately one min. 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 more light isotopes of these elements 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 theoretical predictions concerning the existence of the islands of stability in the region of superheavy elements has been experimentally confirmed not only qualitatively but also to some extent quantitatively.The prospects of further investigations in the field of superheavy nuclei are discussed briefly.