Fission study using multi-nucleon transfer reaction at JAEA tandem

Nishio, Katsuhisa   

This talk will discuss the use of multi-nucleon transfer (MNT) reactions to study fission properties of multitude exotic nuclei in the neutron-rich actinide region. Most of these nuclei cannot be accessed by the traditional method of complete-fusion reactions. The MNT transfer channels of the O+Th reaction were used to study fission of fourteen nuclei Th, Pa, and U. Fission fragment mass distributions (FFMDs) are measured for each transfer channel. In particular, the FFMDs of Th and Pa were measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. By using the same method, the measurements with U, Np, Cm, and Cf targets were recently performed. The obtained FFMDs are compared with a calculation based on the fluctuation-dissipation model, where effect of multi-chance fission (neutron evaporation prior to fission) was considered. It was found that multi-chance fission has significant role on the shape of FFMD, particularly at the high-excitation energies.