Fission studies using multinucleon transfer reactions

Nishio, Katsuhisa   

Fission studies using multinucleon transfer (MNT) reactions at the JAEA tandem facility will be presented. The MNT reaction allows us to produce neutron-rich actinide nuclei, which cannot be populated by particle capture reactions. Taking advantage of many MNT channels opened in the O induced reactions, fission fragment mass distributions (FFMDs) for various actinide nuclei can be obtained in one reaction. Many data were accumulated using various actinide-targets nucleus, including Th, U, Np, Am, and Cm. Also, fission barrier height was derived by finding the excitation energy of the compound nucleus that fission probability starts to appear. The FFMDs at higher excitation energies are explained only by invoking a concept of multi-chance fission, i.e. neutron-evaporation before fission. The obtained data set was used to improve the Langevin model to describe low-energy fissions, which resulted in a clear explanation of the transition from the mass-asymmetric fission to the sharp symmetric fission observed in the fermium isotopes.