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This study [1] explores the role of nucleon exchange for the generation of the fission fragment angular momenta. For a number of typical fission cases, samples of 10,000 shape evolutions are generated by Langevin simulation [2] and, subsequently, for each such evolution, the nucleon exchange transport theory previously developed for damped nuclear reactions [3] is used to obtain the development of the fragment spin-spin distribution within the Fokker-Planck transport framework. The characteristic evolution of both parallel and perpendicular spin components is discussed. A common feature is that the rotational modes fall out of equilibrium before scission when the temperature rises rapidly while the concurrent shrinking of the neck suppresses further exchange. A number of fission observables are extracted from the event ensembles: the distribution of the magnitude of the fragment spin and its orientation relative to the fission axis, as well as the correlation between the two spins and the distribution of their opening angle. The dependence of these observables on the mass asymmetry is also examined.
[1] J. Randrup, P. Nadtochy, C. Schmitt, K. Mazurek, Correlated fission fragment spin dynamics, Phys. Rev. C, 113 (2026) 044605
[2] G.D. Adeev, A.V. Karpov, P.N. Nadtochii, and D.V.Vanin, Multidimensional Stochastic Approach to the Fission Dynamics of Excited Nuclei, Phys. Part. Nucl. 36, 378 (2005)
[3] J. Randrup, Theory of transfer-induced transport in nuclear collisions, Nucl. Phys. A 327, 490 (1979).