Fusion-fission study at JAEA for heavy-element synthesis

Fission fragment mass distributions were measured in the heavy-ion induced fission using U-238 target nucleus. The mass distributions changed drastically with incident energy. The results are explained by a change of the ratio between fusion and qasifission with nuclear orientation. A calculation based on a fluctuation dissipation model reproduced the mass distributions and their incident energy dependence. Fusion probability was determined in the analysis. Evaporation residue cross sections were calculated with a statistical model in the reactions of Si-30+U-238 and S-34+U-238 using the obtained fusion probability in the entrance channel. The results agree with the measured cross sections of (263,264)Sg and (267,268)Hs, produced by Si-30+U-238 and S-34+U-238, respectively. It is also suggested that the sub-barrier energies can be used for heavy element synthesis. (C) 2013 K. Nishio. Published by Elsevier B.V.