On the Scission Point Configuration of Fisioning Nuclei

The scission of a nucleus into two fragments is at present the least understood part of the fission process, though the most important for the formation of the observables. To investigate the potential energy landscape at the largest possible deformations, i.e. at the scission point (line, hypersurface), the Strutinsky's optimal shape approach is applied. For the accurate description of the mass-asymmetric nuclear shape at the scission point, it turned out necessary to construct an interpolation between the two sets of constraints for the elongation and mass asymmetry which are applied successfully at small deformations (quadrupole and octupole moments) and for separated fragments (the distance between the centers of mass and the difference of fragments masses). In addition, a constraint on the neck radius was added, what makes it possible to introduce the so called super-short and super-long shapes at the scission point and to consider the contributions to the observable data from different fission modes. The calculated results for the mass distribution of the fission fragment and the Coulomb repulsion energy "immediately after scission" are in a reasonable agreement with experimental data.