Tri And Rot Effects In Ternary Fission: What Can Be Learned?

Inducing fission by polarized neutrons allows studying subtle effects of the dynamics of the process. In the present experiments ternary fission of 235U and 239Pu was investigated with cold neutrons in the (n,f) reaction at the Institut Laue-Langevin, Grenoble. Asymmetries in the emission of ternary particles were discovered by making use of the neutron spin flipping. It was found that two effects are interfering. There is first an asymmetry in the total yields of ternary particles having been called the TRI-effect. Second, it was observed that the angular distributions of ternary particles are shifted back and forth when flipping the neutron spin. This shift was named ROT effect. Guided by trajectory calculations of the three-body decay, the signs and sizes of the ROT effect are interpreted in terms of the K-numbers of the transition states at the saddle point of fission.