Study of fission using multi-nucleon transfer reactions

多核子移行反応による核分裂研究

西尾 勝久   

Nishio, Katsuhisa

We are promoting a study of fission using multi-nucleon transfer reactions, where excited states in neutron-rich actinide nuclei, which cannot be accessed by particle capture and/or fusion reactions, are populated. This allows us to study fission mechanism in the new region of chart of nuclei. Also, the excited states in the fissioning nucleus are widely populated by the multi-nucleon transfer reactions, from which effects of excitation energy on fission properties can be investigated. Experiments were carried out at the JAEA tandem facility in Tokai, Japan. We studied reactions using the O beam ( 9 MeV/u) and several actinide target nuclei such as Th, U, Np, Cm. Ejectile nuclei were identified by a newly developed silicon E-E detectors (E = 75 m, E = 300 m). Clear separation of oxygen isotopes (O) was obtained as well as lighter element isotopes (Be, B, C, N). Number of produced nuclei reached to more than fifteen in a single measurement. Both fission fragments were detected by multi-wire proportional counters, and fission fragment mass distributions (FFMDs) were measured for each isotopes. The data allows us to obtain the systematic trends of FFMDs in detail. Measured FFMDs are reproduced by a calculation based on the fluctuation-dissipation model, from which the shell damping energy was determined.