Microscopic pairing in fission dynamics

Abstract

Nuclear fission can be modelled as a quantum tunneling process driven by the interplay between the nuclear binding energy and the collective inertia. Within the Wentzel-Kramers-Brillouin formalism, spontaneous fission half-lives can be obtained by minimizing the action integral in the multidimensional space of collective degrees of freedom. Hence, including the relevant collective variables is crucial for properly describing spontaneous fission probabilities. Pairing correlations play an essential role in this evaluation since the collective inertia decreases as the inverse of the square of the pairing gap, and, therefore, they should be considered as a relevant degree of freedom on the same footing as deformation parameters. In this work, we show that the spontaneous fission half-lives in fermium isotopes can be reproduced in a microscopic theory by considering the least-action fission path in a two-dimensional space with constraints on the quadrupole moment and pairing correlations. We consider two microscopic quantities as degrees of freedom associated with pairing: the pairing gap parameter $\Delta$, and the particle number fluctuations $⟨\Delta N^2⟩$. Least-action paths, computed using the Dijkstra algorithm, are compared with minimum-energy paths, highlighting the importance of pairing correlations as a dynamical degree of freedom.

References in corpus (18)

• Spontaneous fission modes and lifetimes of super-heavy elements in the nuclear density functional theory
• Future of Nuclear Fission Theory
• Selfconsistent calculations of fission barriers in the Fm region
• Fission barriers and probabilities of spontaneous fission for elements with Z$\ge$100
• Pairing-induced speedup of nuclear spontaneous fission
• Multidimensionally-constrained relativistic mean-field study of spontaneous fission: coupling between shape and pairing degrees of freedom
• Title: Quadrupole collective inertia in nuclear fission: cranking approximation
• Dynamic versus static fission paths with realistic interactions
• Application of the gradient method to Hartree-Fock-Bogoliubov theory
• Fission properties of the BCPM functional
• On the stability of super-heavy nuclei
• Least action description of spontaneous fission in fermium and nobelium nuclei based on the Gogny energy density functional
• Role of dynamic pairing correlations in fission dynamics
• Description of the multidimensional potential energy surface in fission of ${}^{252}$Cf and ${}^{258}$No
• Non-perturbative collective inertias for fission: a comparative study
• Least action description of dynamic pairing correlations in the fission of Curium and Californium isotopes based on the Gogny energy density functional
• State dependent $\delta$-pairing and spontaneous fission
• Pairing in fission: Mean-field and collective inertias study