First observation of the competing fission modes in the neutron-deficient sub-lead region

Abstract

Fragment mass distributions from fission of excited compound nucleus ${}^{178}$Pt have been deduced from the measured fragment velocities. The ${}^{178}$Pt nucleus was created at the JAEA tandem facility in a complete fusion reaction ${}^{36}$Ar + ${}^{142}$Nd, at beam energies of 155, 170 and 180 MeV. The data are indicative of a mixture of the mass-asymmetric and mass-symmetric fission modes associated with higher and lower total kinetic energies of the fragments, respectively. The measured fragment yields are dominated by asymmetric mass splits, with the symmetric mode contributing at the level of $\approx 1/3$. This constitutes the first observation of a multimodal fission in the sub-lead region. Most probable experimental fragment-mass split of the asymmetric mode, $A_L/A_H\approx 79/99$, is well reproduced by nuclear density functional theory using the UNEDF1-HFB and D1S potentials. The symmetric mode is associated by theory with very elongated fission fragments, which is consistent with the observed total kinetic energy/fragment mass correlation.

arXiv comment6 pages, 4 figures

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Cited by in corpus (10)

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• Efficient method for estimation of fission fragment yields of r-process nuclei
• Description of the multidimensional potential energy surface in fission of ${}^{252}$Cf and ${}^{258}$No
• Scission configuration in the self-consistent calculations with neck constraint
• ${}^{178}$Hg and asymmetric fission of neutron-deficient pre-actinides
• Fission of 215Fr studied with gamma spectroscopic methods
• Multimodality of ${}^{187}$Ir fission studied by Langevin approach
• Description of the mass-asymmetric fission of the Pt isotopes, obtained in the reaction ${}^{36}$Ar + ${}^{142}$Nd within the two-stage fusion-fission model
• Multimodal fission from self-consistent calculations
• Probing the structural evolution along the fission path in the superheavy nucleus ${}^{256}$Sg