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arXiv · 2610.03018

Energy-Resolved Spin and Parity Distributions of Fission Fragments

Petar Marević·Nicolas Schunck·Antonio Bjelčić·Guillaume Scamps
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Abstract

Fission fragments are born rotating rapidly, but the evolution of this spin with excitation energy and its impact on fission observables remain largely unknown. Combining state-of-the-art microscopic and statistical reaction theory, we simulate the full fission process - from the initial state, through scission, to fragment decay - and report the first microscopic, energy-resolved spin and parity distributions of the fragments produced in $^{239}$Pu(n,f). From thermal energy to $E_n = 10$ MeV, the spin of individual fragments evolves non-monotonically, tracking their deformation. The parity content, strongly non-statistical at thermal energy, remains correlated with spin throughout this range. For the first time, we quantify the impact of microscopic spin-parity distributions on prompt photon multiplicities, demonstrating the predictive potential of parameter-free microscopic inputs.

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Petar Marević, Nicolas Schunck, Antonio Bjelčić, Guillaume Scamps. 2026-10-02. Energy-Resolved Spin and Parity Distributions of Fission Fragments. https://arxiv.org/abs/2610.03018

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