Synthesis of heavy and superheavy elements

In two series of experiments at SHIP six new elements (Z = 107-112) were synthesized via fusion reactions using lead or bismuth targets and In-deexcitation channels. The isotopes were unambiguously identified by means of alpha-alpha correlations. Not fission, but alpha decay is the dominant decay mode. Cross-sections decrease by two orders of magnitude from bohrium (Z = 107) to element 112, for which a cross-section of 1 pb was measured. Based on our results, it is likely that the production of isotopes of element 114 close to the island of spherical Super Heavy Elements (SHE) could be achieved by fusion reactions using Pb-208 targets. Systematic studies of the reaction cross-sections indicate that the transfer of nucleons is an important process for the initiation of fusion. The data allow for the fixing of a narrow energy window for the production of SHE using In-emission channels. The likelihood of broadening the energy window by investigation of radiative capture reactions, use of neutron deficient projectile isotopes and use of actinide targets is discussed.