Time-dependent decay rate and angular distribution of the scission neutrons by a dynamical approach
Résumé
A dynamical model is employed to determine some peculiar properties of the scission neutrons, i.e., those emitted at the rupture of the neck between the fragments during low energy nuclear fission. Thus, by a specially adapted procedure, we calculate the time-dependent decay rate. This, defines the character of the emission process: pulsed or exponentially. From the time dependence of the survival probability, we deduced the “half-life” of the scission neutron emission. The angular distribution of the scission neutrons with respect to the fission axis is calculated as well. This is obtained for sets of neutron wave functions defined by a given quantum number Ω (projection of the total angular momentum on the symmetry axis). A strong dependence on Ω was found, namely, wave functions with different Ω have different most probable emission angles: from emission along the fission axis (1/2) to emission perpendicular to the fission axis (9/2). This result leads to a new interpretation of the measured angular distribution of the prompt fission neutrons. Finally, an extension of the dynamical model (i.e., with a time-dependent potential also after scission) is presented.