Fragment Intrinsic Spins and Fragments' Relative Orbital Angular Momentum in Nuclear Fission

TL;DR

This study uses advanced microscopic calculations to analyze the intrinsic spins and orbital angular momentum of fission fragments, revealing dynamics dominated by bending modes, challenging existing models and interpretations.

Contribution

First fully unrestricted microscopic calculations of fission fragment spins and orbital angular momentum using time-dependent density functional theory.

Findings

Fragment spins and orbital angular momentum are dominated by bending collective modes.

Results challenge predictions of phenomenological models.

Provides new insights into the dynamics of nuclear fission fragments.

Abstract

We present the first fully unrestricted microscopic calculations of the primary fission fragment intrinsic spins and of the fission fragments' relative orbital angular momentum for $^{236}$U$^*$, $^{240}$Pu$^*$, and $^{252}$Cf using the time-dependent density functional theory framework. Within this microscopic approach, free of restrictions and unchecked assumptions and which incorporates the relevant physical observables for describing fission, we evaluate the triple distribution of the fission fragment intrinsic spins and of their fission fragments' relative orbital angular momentum and show that their dynamics is dominated by their bending collective modes, in contradistinction to the predictions of the existing phenomenological models and some interpretations of experimental data.