Microscopic description of fission dynamics: Toward a 3D computation of the time dependent GCM equation

D Regnier,M Verrière,N Dubray,N Schunck,A Plompen,S Oberstedt,S Kopecky,P Siegler,W Mondelaers,P Schillebeeckx,J Heyse,F.-J Hambsch

doi:10.1051/epjconf/201714604043

Abstract

Accurate knowledge of fission fragment yields is an essential ingredient of numerous applications ranging from the formation of elements in the r-process to fuel cycle optimization in nuclear energy. The need for a predictive theory applicable where no data is available, together with the variety of potential applications, is an incentive to develop a fully microscopic approach to fission dynamics. One of the most promising theoretical frameworks is the time dependent generator coordinate method (TDGCM) applied under the Gaussian overlap approximation (GOA). However, the computational cost of this method makes it difficult to perform calculations with more than two collective degree of freedom. Meanwhile, it is well-known from both semi-phenomenological and fully microscopic approaches that at least four or five dimensions may play a role in the dynamics of fission. To overcome this limitation, we develop the code FELIX aiming to solve the TDGCM+GOA equation for an arbitrary number of collective variables. In this talk, we report the recent progress toward this enriched description of fission dynamics. We will briefly present the numerical methods adopted as well as the status of the latest version of FELIX. Finally, we will discuss fragments yields obtained within this approach for the low energy fission of major actinides.

Highlights

The growing need for nuclear data in applications such as the r-process study in astrophysics is an incentive to determine the fission yields for a wide range of systems, observables, and input channels
Part of the theoretical effort has been focused on predicting induced fission yields based on the time-dependent generator coordinate method (TDGCM) associated with the Gaussian overlap approximation (GOA) [5, 6]
Because of the computational resources required by this approach, fission dynamics was only studied in 2-dimensional collective spaces

Summary

Introduction

The growing need for nuclear data in applications such as the r-process study in astrophysics is an incentive to determine the fission yields for a wide range of systems, observables, and input channels. Part of the theoretical effort has been focused on predicting induced fission yields based on the time-dependent generator coordinate method (TDGCM) associated with the Gaussian overlap approximation (GOA) [5, 6]. This formalism provides a fully quantum mechanical description of the time evolution of large collective motions in nuclei. In the third and final step, we extract fission product yields from the time-dependent solution of the dynamic equation by defining a frontier in the collective space This frontier separates a domain mainly composed of scissioned configurations from configurations where the system is still a whole nucleus. A detailed description of the whole procedure can be found in [10]

Prediction of actinide fission yields based on two collective variables

Conclusion