Soliton excitations as emitted clusters on nuclear surfaces

Abstract

This work reports on calculations of the deformation energy of a nucleusfor nonlinear deformations. The working hypothesis is that, beyond theusual linear approximation, the nonlinear analysis yields soliton solutionsmoving on its surface. The potential barrier against the emission of asoliton is calculated within the macroscopic-microscopic method. Theouter turning point of the barrier determines limitations on thegeometrical and kinematical parameters for the formation of a surfacesoliton. For large asymmetry, the two-centre shell model is used to assigna structure to the soliton. Calculations for 248No withthe emission of a 40Ca soliton are reported; likewise for224Th with the emission of 16O. Except for neckedshapes at the very first stages of soliton formation, the greatest portionof the deformation path displays rather compact configurations with largeneck radii. These shape sequences correspond to allowable solitonvelocities. Close to and just beyond the touching point configuration,where the shape becomes concave, the width and the velocity of thesoliton approaches zero. The calculations suggest that the emission of a40Ca structure is quite probable due to a low potentialbarrier, whereas the emission of an 16O-type soliton is ratherunlikely due to the higher penetration barrier.