Generation, dynamics, and correlations of the fission fragments' angular momenta

Journal Article · Thu Sep 21 00:00:00 EDT 2023 · Physical Review. C

DOI:https://doi.org/10.1103/physrevc.108.034616· OSTI ID:2202345

Scamps, Guillaume ^[1]; Bertsch, George ^[2]

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1. University of Washington, Seattle, WA (United States); Laboratoire des 2 infinis
2. University of Washington, Seattle, WA (United States)

The generation of angular momentum in fissioning nuclei is not well understood. The predictions of different models disagree, particularly concerning the correlation between the fragments' angular momenta. In this article, a time-dependent collective Hamiltonian model is proposed to treat the generation of the angular momentum in the fission fragments due to the quantum uncertainty principle as well as the dynamics of the collective wave function during and after scission. The model is constructed in the framework of the frozen Hartree-Fock approximation using a Skyrme energy functional to extract deformations of the fission fragments as well as the interactions in a derived collective Hamiltonian. The fission reactions studied are $$^{240}$$Pu $$\rightarrow$$ $$^{132}$$Sn+$$^{108}$$Ru and $$^{240}$$Pu $$\rightarrow$$ $$^{144}$$Ba+$$^{96}$$Sr. The model can account for a large part of the angular momentum found in experimental data. The orientation of the angular momentum of each fragment is found to be mainly in the plane perpendicular to the fission axis, in agreement with the experiment. The magnitudes of the angular momenta in the two fragments are nearly uncorrelated, in agreement with the recent experimental data of Wilson et al., Nature (London) 590, 566 (2021). Some of the conclusions of the traditional collective vibration model are supported by the present model but some are not. Surprisingly, it is found that the angular momenta of the fragments are slightly correlated positively as in a wriggling mode. As a result, it is also found that the presence of an octupole deformation in a fragment can significantly increase the generated angular momentum.

• Research Organization: University of Washington, Seattle, WA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: AC05-00OR22725; FG02-00ER41132; FG02-97ER41014
• OSTI ID: 2202345
• Alternate ID(s): OSTI ID: 2229437
• Journal Information: Physical Review. C, Journal Name: Physical Review. C Journal Issue: 3 Vol. 108; ISSN 2469-9985
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
Scission point
angular momentum
fission
nuclear reactions