Orientation effects of deformed U target nuclei on the fusion probability for heavy element synthesis

Nishio, Katsuhisa   ; Hofmann, S.*; Ikezoe, Hiroshi; Ackermann, D.*; Antalic, S.*; Comas, V. F.*; Gan, Z.*; Heinz, S.*; Heredia, J. A.*; Heberger, F. P.*; Khuyagbaatar, J.*; Kindler, B.*; Kojouharov, I.*; Kuusiniemi, P.*; Lommel, B.*; Mann, R.*; Mazzocco, M.*; Mitsuoka, Shinichi; Nagame, Yuichiro ; Otsuki, Tsutomu*; Popeko, A. G.*; Saro, S.*; Schtt, H. J.*; Sulignano, B.*; Svirikhin, A.*; Tsukada, Kazuaki  ; Yeremin, A. V.*

Effects of the prolate deformation of U on the fusion probability was investigated in the reactions of O+U and Si+U. The experiment was carried out at the JAEA tandem accelerator and GSI of Darmstadt. For O+U, the evaporation residue cross-sections for fermium isotopes were measured down to deep sub-barrier. The results indicate that the projectile O fuses from every colliding angle to the symmetric axis of the U target nucleus. In the reacion of Si+U, fusion hindrance was implied in the deep sub-barrier energies, but no fusion hindrance was suggested at the above barrier energy where the collision on the equatorial side of U starts to contribute. The results suggest that the equatorial collisions has advantage to produce heavy elements in the reaction using heavier projectiles.