Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Physics

A universal curve is one of the simple ways to get preliminary information about the Ü-decay half-life times of heavy nuclei. We try to find parameterization for the universal curve of Ü decay based on semi-microscopic calculations, starting from the realistic M3Y-Reid nucleon-nucleon interaction. Within the deformed density- dependent cluster model, the penetration probability and the assault frequency are calculated using the Wentzel-Kramers-Brillouin (WKB) approximation. The deformations of daughter nuclei and the ground-state spin and parity of the involved nuclei are considered. For all studied decays, we found that it is accurate enough to express the assault frequency either as a function of the mass number of the parent nuclei or as a constant average value. The average preformation probability of the Ü cluster inside four groups of 166 even (Z)-even (N), 117 odd-even, 140 even-odd, and 73 odd-odd Ü-emitters are obtained, individually. We suggested a single universal curve for Ü decay with only one parameter. This parameter varies according to the classified four groups. Finally, we suggested a simpler universal curve based on the simple phenomenological form of penetrability but fitted to the microscopically calculations

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