Shaping The Archipelago Of Stability By The Competition Of Proton And Neutron Shell Closures

The evolution of superheavy nuclei in proton and neutron number is explored by investigating the ground-state shell correction energy in the Z = 112-126 and N = 170-190 region of the (Z, N) plane. Cuts through the (Z, N)-dependent distribution of shell corrections are chosen for constant neutron-proton differences as accessible in a-decay chains and varying the neutron number at fixed charge number. A new approach is used, integrating elements of energy-density functional theory into the microscopic-macroscopic method. The topology of the shell correction implies for binding energies a distribution resembling in shape a ridge on a coral reef, formed by the competition of proton and neutron shell closures at Z = 114 and Z = 120, and N = 174 and N = 184, respectively. (288)F1 is predicted as the next double magic nucleus after Pb-208, and (304)120 is identified as the most likely candidate for next-to-next double magic nucleus.