Microscopic description of the fission process including intrinsic excitations. Part III: 240Pu fission dynamics along 1D asymmetric paths within the Schrodinger Collective Intrinsic Model

Abstract

This last article of the trilogy focuses on the dynamical equation of the Schrodinger Collective-Intrinsic Model (SCIM). First, we motivate and discuss the need to regularize the adiabatic and excited dynamical ingredients entering the collective-intrinsic Hamiltonian, namely the collective potential, the collective inertia tensor, and the collective dissipative tensor. In particular, we introduce a Savitzky-Golay low-pass filter to remove numerical fluctuations incompatible with the second-order truncation in the Symmetric Ordered Product of Operators used to derive the SCIM equations. The diagonal and off-diagonal properties of the three dynamical ingredients are then analyzed along the asymmetric fission path in 240Pu. This study highlights the dominant role of neutron and proton excitation channels, especially in the second well and scission regions, whereas proton-neutron couplings remain essentially negligible. Furthermore, in the adiabatic limit of the SCIM, we perform a comparison with the GOA which reveals very close predictions. Second, we discuss the construction of the initial wave packet and the numerical resolution of the collective-intrinsic Schrodinger equation. Using a continuity equation, we derive the probability fluxes associated with the different components of the wave function, which provide direct access to the contribution of the different excitations to the final observables for the fission problem. The excited states are found to account for more than 80% of the total flux at scission. Finally, we evaluate, the neutron and proton fragment distributions as well as the energy balance, including the total kinetic and excitation energies. The obtained results are found to be consistent with available experimental data and demonstrate the importance of explicitly including intrinsic excitations in the description of fission dynamics.