Generation of Fragment Angular Momentum in Fission
Journal Article
·
· Physical Review Letters
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of California, Davis, CA (United States)
A recent analysis of experimental data [J. Wilson et al., Nature (London) 590, 566 (2021)] found that the angular momenta of nuclear fission fragments are uncorrelated. Based on this finding, the authors concluded that the spins are therefore determined only after scission has occurred. We show here that the nucleon-exchange mechanism, as implemented in the well-established event-by-event fission model freya, while agitating collective rotational modes in which the two spins are highly correlated, nevertheless leads to fragment spins that are largely uncorrelated. We find that this counterexample invalidates the conclusion in [J. Wilson et al.] that uncorrelated spins must necessarily have been generated after scission (a potentious conclusion that would rule out all models that generate the fragment spins prior to scission). Furthermore, it was reported [J. Wilson et al.] that the mass dependence of the average fragment spin has a sawtooth structure. We demonstrate that such a behavior naturally emerges when shell and deformation effects are included in the moments of inertia of the fragments at scission.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC), Nuclear Physics (NP)
- Grant/Contract Number:
- AC02-05CH11231; AC52-07NA27344
- OSTI ID:
- 1814687
- Alternate ID(s):
- OSTI ID: 1821157
- Report Number(s):
- LLNL-JRNL--820697; 1032305
- Journal Information:
- Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 6 Vol. 127; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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