Frustrated fragmentation and re-aggregation in nuclei: a non-equilibrium description in spallation

Abstract

Heavy nuclei bombarded with protons and deuterons in the 1 GeV range have a large probability of undergoing a process of evaporation and fission; less frequently, the prompt emission of few intermediate-mass fragments can also be observed. We employ a recently developed microscopic approach, based on the Boltzmann-Langevin transport equation, to investigate the role of mean-field dynamics and phase-space fluctuations in these reactions. We find that the formation of few IMF's can be confused with asymmetric fission when relying on yield observables, but it can not be assimilated to the statistical decay of a compound nucleus when analysing the dynamics and kinematic observables: it can be described as a fragmentation process initiated by phase-space fluctuations, and successively frustrated by the mean-field resilience. As an extreme situation, which corresponds to non-negligible probability, the number of fragments in the exit channel reduces to two, so that fission-like events are obtained by re-aggregation processes. This interpretation, inspired by nuclear-spallation experiments, can be generalised to heavy-ion collisions from Fermi to relativistic energies, for situations when the system is closely approaching the fragmentation threshold.

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Cited by in corpus (15)

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• Comparison of heavy-ion transport simulations: Collision integral in a box
• Dynamics of clusters and fragments in heavy-ion collisions
• Comparison of Heavy-Ion Transport Simulations: Mean-field Dynamics in a Box
• Transport approaches for the Description of Intermediate-Energy Heavy-Ion Collisions
• Progress of Quantum Molecular Dynamics model and its applications in Heavy Ion Collisions
• Inhomogeneity growth in two-component fermionic systems
• One-body Langevin dynamics in heavy-ion collisions at intermediate energies
• Dynamical description of heavy-ion collisions at Fermi energies
• Nuclear jets in heavy-ion collisions recall a stream of sand
• Light fragment and neutron emission in high-energy proton induced spallation reactions
• Cluster formation in nuclear reactions from mean-field inhomogeneities
• Dynamic description of ternary and quaternary splits of heavy nuclear systems in the deep-inelastic regime
• Violent Nuclear Reactions: Large-Amplitude Nuclear Dynamic Phenomena in Fermionic Systems
• Transport Model Comparison Studies of Intermediate-Energy Heavy-Ion Collisions