Interpretation of mass asymmetry in fission based on deformation energy surfaces

摘要: Abstract The deformation energy surfaces of fissioning nuclei have been studied to quantitatively interpret the experimentally observed mass asymmetry in fission. These studies use calculated which recently shown reflection asymmetric saddle-point shapes second (outer) fission barriers actinide nuclei. Quantitative estimates fission, characterized by peak-to-valley mass-yield ratio, from an analysis probabilities over outer barrier. probability distributions were determined using simple Fermi-gas level density and WKB barrier-penetration formulae. Good correlations obtained for all known radiochemically ratios doubly even surface calculations are available. One is able understand this discovered apparently anomalous results that thermal-neutron-induced 257Fm yields a symmetric division while spontaneous 256Fm asymmetric. Apossible explanation triple-peaked near 226Ra proposed based also on surfaces. Further experiments suggested test present theory, particular, discriminate between analyses barrier those fragment shell effects.