Fission Barriers of Super-Heavy Nuclei and Search for Element 120

After a successful production of isotopes of element 116 in the reaction 48Ca + 248Cm, the reaction 54Cr + 248Cm → 302120* was investigated at the velocity filter SHIP at GSI, Darmstadt, aiming to search for isotopes of element 120. One chain of events was observed, which is not created by chance with high probability. Parts of the chain agree with model predictions and measured data from a decay chain which could start at the isotope 299120. In a complementary study, model dependent shell-correction energies and related heights of fission barriers were deduced from measured Qα values. The results are compared with predictions of macroscopic-microscopic models. The consequences for calculations of crosssections are discussed.