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An asymmetric fission island driven by shell effects in light fragments

Morfouace, P. ; Zhukov, M. ; Cederkäll, J. LU and Holl, M. LU orcid (2025) In Nature
Abstract
Nuclear fission leads to the splitting of a nucleus into two fragments1,2. Studying the distribution of the masses and charges of the fragments is essential for establishing the fission mechanisms and refining the theoretical models3,4. It has value for our understanding of r-process nucleosynthesis5,6, in which the fission of nuclei with extreme neutron-to-proton ratios is pivotal for determining astrophysical abundances and understanding the origin of the elements7 and for energy applications8,9. Although the asymmetric distribution of fragments is well understood for actinides (elements in the periodic table with atomic numbers from 89 to 103) based on shell effects10, symmetric fission governs the scission process for lighter elements.... (More)
Nuclear fission leads to the splitting of a nucleus into two fragments1,2. Studying the distribution of the masses and charges of the fragments is essential for establishing the fission mechanisms and refining the theoretical models3,4. It has value for our understanding of r-process nucleosynthesis5,6, in which the fission of nuclei with extreme neutron-to-proton ratios is pivotal for determining astrophysical abundances and understanding the origin of the elements7 and for energy applications8,9. Although the asymmetric distribution of fragments is well understood for actinides (elements in the periodic table with atomic numbers from 89 to 103) based on shell effects10, symmetric fission governs the scission process for lighter elements. However, unexpected asymmetric splits have been observed in neutron-deficient exotic nuclei11, prompting extensive further investigations. Here we present measurements of the charge distributions of fission fragments for 100 exotic fissioning systems, 75 of which have never been measured, and establish a connection between the neutron-deficient sub-lead region and the well-understood actinide region. These new data comprehensively map the asymmetric fission island and provide clear evidence for the role played by the deformed Z = 36 proton shell of the light fragment in the fission of sub-lead nuclei. Our dataset will help constrain the fission models used to estimate the fission properties of nuclei with extreme neutron-to-proton ratios for which experimental data are unavailable. (Less)
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type
Contribution to journal
publication status
epub
subject
in
Nature
publisher
Nature Publishing Group
external identifiers
  • pmid:40307545
  • scopus:105003971123
ISSN
1476-4687
DOI
10.1038/s41586-025-08882-7
language
English
LU publication?
yes
id
c04086c0-124b-4569-9f03-f8cf800a0039
date added to LUP
2025-05-02 15:18:58
date last changed
2025-07-15 04:03:17
@article{c04086c0-124b-4569-9f03-f8cf800a0039,
  abstract     = {{Nuclear fission leads to the splitting of a nucleus into two fragments1,2. Studying the distribution of the masses and charges of the fragments is essential for establishing the fission mechanisms and refining the theoretical models3,4. It has value for our understanding of r-process nucleosynthesis5,6, in which the fission of nuclei with extreme neutron-to-proton ratios is pivotal for determining astrophysical abundances and understanding the origin of the elements7 and for energy applications8,9. Although the asymmetric distribution of fragments is well understood for actinides (elements in the periodic table with atomic numbers from 89 to 103) based on shell effects10, symmetric fission governs the scission process for lighter elements. However, unexpected asymmetric splits have been observed in neutron-deficient exotic nuclei11, prompting extensive further investigations. Here we present measurements of the charge distributions of fission fragments for 100 exotic fissioning systems, 75 of which have never been measured, and establish a connection between the neutron-deficient sub-lead region and the well-understood actinide region. These new data comprehensively map the asymmetric fission island and provide clear evidence for the role played by the deformed Z = 36 proton shell of the light fragment in the fission of sub-lead nuclei. Our dataset will help constrain the fission models used to estimate the fission properties of nuclei with extreme neutron-to-proton ratios for which experimental data are unavailable.}},
  author       = {{Morfouace, P. and Zhukov, M. and Cederkäll, J. and Holl, M.}},
  issn         = {{1476-4687}},
  language     = {{eng}},
  publisher    = {{Nature Publishing Group}},
  series       = {{Nature}},
  title        = {{An asymmetric fission island driven by shell effects in light fragments}},
  url          = {{http://dx.doi.org/10.1038/s41586-025-08882-7}},
  doi          = {{10.1038/s41586-025-08882-7}},
  year         = {{2025}},
}