Regular Article - Experimental Physics
Shifting the closed proton shell to Z = 122 —A possible scenario to understand the production of superheavy elements Z = 112−118
GSI Darmstadt, Planckstr. 1, D-64291, Darmstadt, Germany
Published online: 25 July 2008
The recent experiments at FLNR, Dubna, demonstrated that cross-sections to produce SHEs by 48Ca-induced reactions on actinide targets increase beyond Z = 111, reach a maximum of 5 pb at Z = 114 and fall below the 1 pb level at Z = 118. A scenario is proposed to understand the findings within the frame of former experimental results of heavy-element production and theoretical predictions about the stability of the nuclides concerned. New ingredients introduced are: 1) to shift the next proton shell beyond Pb from Z = 114 to Z = 122; 2) the isotopes of the elements Z = 112 to Z = 118 are deformed and their nuclei have oblate shapes; 3) the fission barriers around the next nucleus with doubly closed shells 306184122 are larger than the neutron separation energies and reach values in the range of 10MeV. The ascent of the flat top at 306184122 is described by the proposed scenario, which likewise excludes reaching the doubly closed shell region at the top by today’s experimental methods.
PACS: 21.10.Dr Binding energies and masses – / 21.60.Fw Models based on group theory – / 25.60.Pj Fusion reactions – / 27.90.+b A ≥ 220 –
© SIF, Springer-Verlag Berlin Heidelberg 2008