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

Journal Article · Wed Jan 28 00:00:00 EST 2026 · Physical Review. C

DOI:https://doi.org/10.1103/yr2c-nvf3· OSTI ID:3018101

Marević, Petar ^[1]; Schunck, Nicolas ^[2]; Verriere, Marc ^[3]

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1. Univ. of Zagreb (Croatia)
2. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
3. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); CEA, DAM, DIF, Arpajon (France)

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. Here, 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 ²³⁵U and ²³⁹Pu , 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.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR). Scientific Discovery through Advanced Computing (SciDAC); USDOE Office of Science (SC), Nuclear Physics (NP)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 3018101
• Report Number(s): LLNL--JRNL-2007093
• Journal Information: Physical Review. C, Journal Name: Physical Review. C Journal Issue: 1 Vol. 113; ISSN 2469-9985; ISSN 2469-9993
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

Physics - Nuclear physics and radiation physics