Nuclear Fission Dynamics: Past, Present, Needs, and Future

TL;DR

Recent advances in computational power and theoretical models are enabling the development of a fully microscopic, real-time description of nuclear fission, which can improve understanding and guide phenomenological models despite computational challenges.

Contribution

The paper argues that a microscopic approach to nuclear fission challenges the assumption of adiabaticity and provides insights into fission dynamics and trends.

Findings

Microscopic models can describe real-time fission dynamics.

Adiabaticity assumption in fission is not supported by microscopic approaches.

Microscopic approaches can predict unmeasurable observables in astrophysics.

Abstract

Recent developments in theoretical modeling and in computational power have allowed us to make significant progress on a goal not achieved yet in nuclear theory: a fully microscopic theory of nuclear fission. The complete microscopic description remains a computationally demanding task, but the information that can be provided by current calculations can be extremely useful to guide and constrain phenomenological approaches. First, a truly microscopic framework that can describe the real-time dynamics of the fissioning system can justify or rule out assumptions and approximations incompatible with an accurate quantum treatment or with our understanding of the inter nucleon interactions. Second, the microscopic approach can be used to obtain trends such as: the excitation energy sharing mechanism between fission fragments (FFs) with increasing excitation energy of the fissioning system, the angular momentum content of the FFs, or even to compute observables that cannot be otherwise calculated in phenomenological approaches or even measured, as in the case of astronomical environments. Merely the characterization of the trends would be of great importance for various application. We present here arguments that a truly microscopic approach to fission does not support the assumption of adiabaticity of the large amplitude collective motion in fission, particularly starting from the outer saddle down to the scission configuration.