Asymmetric fission from egg shape deformation

Asymmetric mass distributions have proved to be one of the most persistent puzzles in the fission process. The asymmetric fission of heavy nucleus is considered to occur because of the shell effects. In the fissioning process however, at some point of deformation the nucleus has to assume an asymmetrical shape in the fissioning direction. Simplest asymmetrical shape is like an egg. This egg shape is obtained basically from two hemi-ellipsoids of revolution (about the major axis, b and c with equal minor axis, a), by joining the equal circular faces. With the increase of b and c values the value of a decreases so as to conserve the total volume. The fission occurs when the joint is snapped as a result of the total surface energy increasing beyond the total surface energy of the spherical fragments. It is important that the fission process or the cleavage starts in this proceedings of elongation at a point where the surface curvature is least and it is at the joint of the two hemi-ellipsoids. For the first time the Coulomb energy of this egg shaped 235U92 nucleus has been evaluated. Most importantly the Coulomb energy for various fragment combinations is seen to decreases from that of the symmetric fission. This behaviour will lead to lower Coulomb barriers and shapes varying around the saddle point. So far this aspect of P3(cosθ) deformation has not been investigated and present work indicates smaller amount of shell corrections (due to smaller fission barriers) to be applicable in the asymmetric fission