CLUSTER PREFORMATION IN CLOSED-SHELL AND MID-SHELL NUCLEI

By using our semiclassical method to estimate the preformation probabi lity of the touching point configuration as the penetrability of the i nner part of the barrier, it is shown that this quantity is strongly d ependent on the nuclear structure. We are illustrating this dependence by comparing the low probability of cluster preformation in a doubly magic nucleus (208)pb, With much higher values obtained in a heavier p arent nucleus leading to (208)pb heavy fragment, for different emitted clusters like He-4, C-12, Ne-20, Mg-24, etc.