Fission fragment anisotropy in heavy-ion-induced fission of actinides

Nishinaka, Ichiro; Nishio, Katsuhisa   ; Tanikawa, Masashi*; Makii, Hiroyuki   ; Wakabayashi, Yasuo; Mitsuoka, Shinichi; Yokoyama, Akihiko*

In order to study the effects of entrance channel mass asymmetry =(-)/(+) on fission fragment anisotropy, we measured fission fragment angular distributions in the reactions of Ne+Th (=0.827) and C+Pu (=0.906), populating the same compound nucleus Fm. At the JAEA tandem accelerator fission fragments from the compound nucleus at excitation energies of 56.1, 52.5, 48.8 and 45.2 MeV were measured by position-sensitive parallel plate avalanch counters and silicon surface barrier detectors. The anisotropy for Ne+Th with smaller entrance channel mass asymmetry =0.827 shows large values compared with those for C+Pu with =0.906. This implies that entrance channel mass asymmetry plays a role for fission fragment anisotropy in the present systems.