Effects of nuclear orientation on fusion and fission in the reaction using U target nucleus

西尾 勝久; 池添 博; 光岡 真一; 西中 一朗; 永目 諭一郎; 大槻 勤*; 廣瀬 健太郎*; Hofmann, S.*

EPJ Web of Conferences, 2, p.10001_1 - 10001_3, 2010/03

https://doi.org/10.1051/epjconf/20100210001

We have measured the (1) evaporation residue (ER) cross-sections for Si, S + U and (2) fission fragment mass distributions for Si,S, Ar. Measurement of ER cross-section was carried out at GSI by using the velocity filter SHIP. Measurement of fission fragment mass distribution was made by using the JAEA tandem accelerator. In the reaction Si + U, the ER cross-section for Sg(5n) suggested no fusion hindrance at above-barrier energy, whereas the one for Sg(4n) suggested competition between fusion and fission at sub-barrier energy. This conclusion is consistent with the measured fragment mass distributions, where the asymmetric fission component associated with quasi-fission appears only at sub-barrier energies. In the reaction of S + U, the ER cross-sections for Hs(5n) and Hs(4n, new isotope) suggested fusion hindrance both for above- and sub-barrier energies. With the results of fission fragment mass distributions, it is found that quasi-fission has symmetric fission components when projectile mass is relatively large. We will also discuss the variation of the fragment mass distributions for Si,S, Ar + U.