Symmetric and asymmetric scission properties in the fission of pre-actinides through heavy actinides

Nagame, Yuichiro ; Nishinaka, Ichiro; Zhao, Y. L.*; Nakahara, Hiromichi*

Existence of two kinds of scission configurations associated with symmetric and asymmetric fission modes is pointed out in the fission of actinides: elongated and compact configurations. Each scission property is discussed in terms of shape elongation evaluated from fragment total kinetic energy (TKE). Fragment deformation at scission is also discussed based on neutron multiplicity measurements. From the systematic study of the scission properties in a wide range of actinides, the bimodal fission observed in the spontaneous fission (SF) of the heavy actinides would be interpreted as the result of the presence of the two fission paths; the ordinary asymmetric fission path is still exiting while the symmetric one is bifurcated by strongly shell-influenced effects.