Effects of nuclear orientation on fusion and fission process for reactions using U target nucleus

Nishio, Katsuhisa   

Motivated by the production of superheavy elements (SHEs) up to Z=118 in the actinide-based reactions, we measured the evaporation residue (ER) cross-sections for Si + U and S + U to investigate the effects of nuclear deformation on fusion. Measurement was carried out at GSI. In the sub-barrier reaction, we produced the isotopes Sg and Hs (new isotope), respectively, as 4 channel by taking advantage of the lowering of Coulomb barrier due to prolate deformation of U. From the cross-sections of Sg and Hs (5) measured at the above-barrier, we conclude that fusion dominates in Si + U, whereas quasifission dominates in S + U. We also measured the fission fragment mass distributions at the JAEA tandem accelerator. We observed enhanced asymmetric fission when beam energies were decreased to sub-barrier. The results were reproduced by the fluctuation - dissipation model. The calculated fusion probabilities are consistent with the results obtained from the ER cross-sections.