Evidence for hindrance in fusion between sulfur and lead nuclei

Khuyagbaatar, J.*; Nishio, Katsuhisa   ; Hofmann, S.*; Ackermann, D.*; Block, M.*; Heinz, S.*; Heberger, F. P.*; Hirose, Kentaro  ; Ikezoe, Hiroshi; Kindler, B.*; Lommel, B.*; Makii, Hiroyuki   ; Mitsuoka, Shinichi; Nishinaka, Ichiro; Otsuki, Tsutomu*; Wakabayashi, Yasuo*; Yan, S.*

The influence of the structure of projectile and target nuclei on the capture cross-sections was investigated for the reactions S+Pb and S+Pb. Capture cross-sections were deduced by measuring the fission fragments using multi-wire proportional counters. An enhancement of the capture cross-sections relative to an one-dimensional barrier penetration model was observed for all reactions at energies below the interaction barriers. The enhancement is larger in the case of reactions with S than with S. This observation is explained by a stronger coupling to the vibrational states in the reactions with S. Comparing the capture cross-sections and the evaporation-residue cross-sections for the reactions S+Pb and S+Pb, both yielding the same compound nucleus Cf, it is shown that the latter reaction has a lower fusion probability.