Fission study of actinide nuclei using multi-nucleon transfer reactions

Lguillon, R.; Nishio, Katsuhisa   ; Hirose, Kentaro  ; Orlandi, R.  ; Makii, Hiroyuki   ; Nishinaka, Ichiro; Ishii, Tetsuro  ; Tsukada, Kazuaki  ; Asai, Masato  ; Chiba, Satoshi*; Otsuki, Tsutomu*; Araki, Shohei*; Watanabe, Yukinobu*; Tatsuzawa, Ryotaro*; Takaki, Naoyuki*

Nucleon-transfer reaction allows us to produce neutron-rich nuclei, which cannot be accessed by fusion-evaporation reaction. We are promoting a campaign to measure fission-fragment mass distributions for actinide nuclei populated by transfer reactions. Unique feature in this approach in this fission study is that we can populate the fissioning nuclei from its ground state up to excitation energy of several tens MeV. We thus obtain the excitation energy dependence of the mass distribution for several nuclei. The fission barrier height can be determined from the excitation function of the fission probability. These data are important to develop a fission theory. The experiment was carried out at the 20 MV JAEA tandem facility at Tokai. We report on the data obtained in the reaction O + Th. Transfer-channels and excitation energies of the fissioning nuclei were identified using silicon E-E detectors located to the forward direction of the Th target. Two fission fragments were detected in coincidence using multi-wire proportional counters. Fission fragment masses were determined by kinematic consideration. We obtained the fission fragment mass distributions for 12 nuclei of thorium, protactinium and uranium. The data include those for Th and Pa obtained for the first time. In this run, we also report prompt neutrons in fission obtained using liquid scintillation detectors.