Problem of the conservation of the fissile-nucleus-spin projection onto the fissile-nucleus symmetry axis and quantum dynamics of the low-energy fission process

Within quantum-mechanical fission theory, it is shown that, in the low-energy fission of actinide nuclei, the projection K of the spin of a fissile nucleus onto its symmetry axis is conserved as this nucleus traverses the second well of the deformation potential and the region of descent from the external fission barrier to the scission point, this spin projection being an integral of motion despite the effect of Coriolis interaction. This leads to the conclusion that the fission probability is determined by the concerted effect of the internal- and external-fission-barrier penetration factors. A global analysis of information that can be extracted from experimental investigations of (n, f) and (γ, f) reactions and which can be employed in theoretically describing fission mechanisms is performed.