INFLUENCE OF THE NUCLEAR-SURFACE DIFFUSENESS ON EXOTIC CLUSTER DECAY HALF-LIFE TIMES

The role of nuclear surface diffuseness in exotic cluster decays is studied for the preformed cluster model. It is found that, even for spherical nuclei, these effects are much larger-of the order of four to five powers of ten for half-life estimates-compared to the deformation effects of the parent and daughter nuclei. Regarding the cluster deformations versus surface diffuseness, the two effects are of similar orders, but act in opposite directions. The surface effects are shown to be important for both the preformation and penetration probabilities and are mainly due to the emitted cluster. As the mass number of the emitted cluster becomes larger than about 20, these effects become small for the lifetime estimates.