Microscopic theory of angular momentum distributions across the full range of fission fragments

Abstract

Modern nuclear theory provides qualitative insights into the fundamental mechanisms of nuclear fission and is increasingly capable of making reliable quantitative predictions. Most quantities of interest pertain to the primary fission fragments, whose subsequent decay is typically modeled using statistical reaction models. Consequently, a key objective of fission theory is to inform these models by predicting the initial conditions of the primary fragments. In this work, we employ a framework that combines joint angular momentum and particle number projection with time-dependent configuration mixing to calculate the angular momentum distributions of primary fragments. Focusing on the benchmark cases of neutron-induced fission of ${}^{235}$U and ${}^{239}$Pu, we predict - for the first time - microscopic angular momentum distributions for all fragments observed in experiments. Our results reveal a pronounced sawtooth pattern in the average angular momentum as a function of fragment mass, consistent with recent measurements. Additionally, we observe substantial variations in angular momentum distributions along isobaric chains, indicating that commonly used empirical formulas lack sufficient accuracy. We also quantify a strong correlation between the angular momentum and the deformation of the fragments at scission, and a weak correlation in the magnitude of the angular momentum between fragment partners. The generated data will enable estimation of the impact of microscopic distributions on fission spectra, paving the way toward fission modeling based on microscopic inputs.

20 pages, 11 figures

References in corpus (47)

• Microscopic Theory of Nuclear Fission: A Review
• Microscopic approach of fission dynamics applied to fragment kinetic energy and mass distributions in 238U
• Induced Fission of ${}^{240}$Pu within a Real-Time Microscopic Framework
• Particle transfer reactions with the time-dependent Hartree-Fock theory using a particle number projection technique
• Future of Nuclear Fission Theory
• Formation and dynamics of fission fragments
• Effect of pairing on one- and two-nucleon transfer below the Coulomb barrier: a time-dependent microscopic description
• Fission fragment charge and mass distributions in 239Pu(n,f) in the adiabatic nuclear energy density functional theory
• Symmetry restoration in mean-field approaches
• Description of Induced Nuclear Fission with Skyrme Energy Functionals: I. Static Potential Energy Surfaces and Fission Fragment Properties
• Theory of Nuclear Fission
• Fission barriers and probabilities of spontaneous fission for elements with Z$\ge$100
• Fission Dynamics of 240Pu from Saddle-to-Scission and Beyond
• Fission properties of superheavy nuclei for r-process calculations
• Microscopic calculation of 240Pu scission with a finite-range effective force
• Formation Of The Rare Earth Peak: Gaining Insight Into Late-Time r-Process Dynamics
• Fission Fragment Decay Simulations with the CGMF Code
• Numerical search of discontinuities in self-consistent potential energy surfaces
• Microscopic study of induced fission dynamics of ${}^{226}$Th with covariant energy density functionals
• Microscopic and non-adiabatic Schrödinger equation derived from the Generator Coordinate Method based on 0 and 2 quasiparticle HFB states
• Nuclear Scission and Quantum Localization
• From Asymmetric to Symmetric Fission in the Fermium Isotopes within the Time-Dependent GCM Formalism
• Generation of fragment angular momentum in fission
• Microscopic description of production cross sections including deexcitation effects
• Microscopic self-consistent description of induced fission dynamics: finite temperature effects
• Fission fragments intrinsic spins and their correlations
• The time-dependent generator coordinate method in nuclear physics
• Angular Momentum of Fission Fragments from Microscopic Theory
• Particle-number projection method in time-dependent Hartree-Fock theory: Properties of reaction products
• Time-dependent generator coordinate method study of mass-asymmetric fission of actinides
• Study of angular momentum effects in fission
• Axially-deformed solution of the Skyrme-Hartree-Fock-Bogoliubov equations using the transformed harmonic oscillator basis (IV) hfbtho (v4.0): A new version of the program
• FELIX-2.0: New version of the finite element solver for the time dependent generator coordinate method with the Gaussian overlap approximation
• Microscopic Calculation of Fission Product Yields with Particle Number Projection
• Angular momentum of fission fragments
• Number of Particles in Fission Fragments
• Fission of ${}^{240}$Pu with symmetry-restored density functional theory
• Time-dependent generator coordinate method study of fission: dissipation effects
• Improved modeling of photon observables with FREYA
• Generalized time-dependent generator coordinate method for induced fission dynamics
• The angular correlation between the fission fragment intrinsic spins
• Coupled fission fragment angular momenta
• Spatial orientation of the fission fragment intrinsic spins and their correlations
• Generation, dynamics, and correlations of the fission fragments' angular momenta
• Microscopic description of the torque acting on fission fragments
• Microscopic Calculation of Fission Product Yields for Odd-Mass Nuclei
• Time-dependent density functional theory study of induced-fission dynamics of ${}^{226}$Th