${}^{178}$Hg and asymmetric fission of neutron-deficient pre-actinides

Abstract

Fission at low excitation energy is an ideal playground to probe the impact of nuclear structure on nuclear dynamics. While the importance of structural effects in the nascent fragments is well-established in the (trans-)actinide region, the observation of asymmetric fission in several neutron-deficient pre-actinides can be explained by various mechanisms. To deepen our insight into that puzzle, an innovative approach based on inverse kinematics and an enhanced version of the VAMOS++ heavy-ion spectrometer was implemented at the GANIL facility, Caen. Fission of ${}^{178}$Hg was induced by fusion of ${}^{124}$Xe and ${}^{54}$Fe. The two fragments were detected in coincidence using VAMOS++ supplemented with a new SEcond Detection arm. For the first time in the pre-actinide region, access to the pre-neutron mass and total kinetic energy distributions, and the simultaneous isotopic identification of one the fission fragment, was achieved. The present work describes the experimental approach, and discusses the pre-neutron observables in the context of an extended asymmetric-fission island located south-west of $^{208}Pb. A comparison with different models is performed, demonstrating the importance of this "new" asymmetric-fission island for elaborating on driving effects in fission.

References in corpus (9)

• Brownian shape motion on five-dimensional potential-energy surfaces: Nuclear fission-fragment mass distributions
• Future of Nuclear Fission Theory
• Excitation energy dependence of fission in the mercury region
• Fission fragment distributions and their impact on the r-process nucleosynthesis in neutron star mergers
• Microscopic Calculation of Fission Product Yields with Particle Number Projection
• Correlation studies of fission fragment neutron multiplicities
• Scission configuration of ${}^{239}$U from yields and kinetic information of fission fragments
• Improvements to the macroscopic-microscopic approach of nuclear fission
• Fission fragment mass distribution in ${}^{210}$Po and ${}^{213}$At

Cited by in corpus (2)

• Fast trajectory reconstruction techniques for the large acceptance magnetic spectrometer VAMOS++
• Isotopic fission yields of ${}^{240}$Pu as a function of the excitation energy