Soliton excitations as emitted clusters on nuclear surfaces

This work reports on calculations of the deformation energy of a nucleus fo r nonlinear deformations. The working hypothesis is that, beyond the usual linear approximation, the nonlinear analysis yields soliton solutions movin g on its surface. The potential barrier against the emission of a soliton i s calculated within the macroscopic-microscopic method. The outer turning p oint of the barrier determines limitations on the geometrical and kinematic al parameters for the formation of a surface soliton. For large asymmetry, the two-centre shell model is used to assign a structure to the soliton. Ca lculations for No-248 With the emission of a Ca-40 soliton are reported; li kewise for Th-224 With the emission of O-16. Except for necked shapes at th e very first stages of soliton formation, the greatest portion of the defor mation path displays rather compact configurations with large neck radii. T hese shape sequences correspond to allowable soliton velocities. Close to a nd just beyond the touching point configuration, where the shape becomes co ncave, the width and the velocity of the soliton approaches zero. The calcu lations suggest that the emission of a Ca-40 structure is quite probable du e to a low potential barrier, whereas the emission of an O-16-type soliton is rather unlikely due to the higher penetration barrier.