Nucleon localization and fragment formation in nuclear fission

Abstract

An electron localization measure was originally introduced to characterize chemical bond structures in molecules. Recently, a nucleon localization based on Hartree-Fock densities has been introduced to investigate $\alpha$-cluster structures in light nuclei. Compared to the local nucleonic densities, the nucleon localization function has been shown to be an excellent indicator of shell effects and cluster correlations. Using the spatial nucleon localization measure, we investigate the emergence of fragments in fissioning heavy nuclei. To illustrate basic concepts of nucleon localization, we employ the self-consistent energy density functional method with a quantified energy density functional optimized for fission studies. We study the particle densities and spatial nucleon localization distributions along the fission pathways of ${}^{264}$Fm, ${}^{232}$Th and ${}^{240}$Pu. We demonstrate that the fission fragments are formed fairly early in the evolution, well before scission. We illustrate the usefulness of the localization measure by showing how the hyperdeformed state of ${}^{232}$Th can be understood in terms of a quasimolecular state made of ${}^{132}$Sn and ${}^{100}$Zr fragments. Compared to nucleonic distributions, the nucleon localization function more effectively quantifies nucleonic clustering: its characteristic oscillating pattern, traced back to shell effects, is a clear fingerprint of cluster/fragment configurations. This is of particular interest for studies of fragment formation and fragment identification in fissioning nuclei.

7 pages, 8 figures

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• Time-dependent electron localization function
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• Localization in light nuclei
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Cited by in corpus (15)

• Formation and distribution of fragments in the spontaneous fission of 240Pu
• Cluster formation in pre-compound nuclei in the time-dependent framework
• Clusterization and deformation of multi-$\Lambda$ hypernuclei within relativistic mean-field model
• Theoretical description of fission yields: towards a fast and efficient global model
• Microscopic description of the torque acting on fission fragments
• Nuclear Quantum Many-Body Dynamics: From Collective Vibrations to Heavy-Ion Collisions (2nd edition)
• Clustering in nuclei at finite temperature
• Visualization of nuclear many-body correlations with the most probable configuration of nucleons
• Local alpha-removal strength in the mean-field approximation
• Extraction of ground-state nuclear deformations from ultra-relativistic heavy-ion collisions: Nuclear structure physics context
• Examining the justification for the introduction of a fermion localization function
• Octupole deformation of nuclei near the spherical closed-shell configurations
• Non-local orbital-free density functional theory incorporating nuclear shell effects
• Impact of pion tensor force on alpha clustering in ${}^{20}$Ne
• Two-Center Gaussian potential well for studying light nucleus in cluster structure