الفهرس 
Exotic alpha decays of radioactive nuclei
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Abstract
The preformation of Ü-particle as a distinct entity inside the Ü-emitter is the first move towards Ü- decay. The present work is a theoretical study concerning the influence of the nuclear structure to the ordinary and exotic Ü-decays from radioactive nuclei and on the preformation probability of the alpha particle and the daughter nucleus inside them. We consider favored and unfavored decays at which the Ü-emitters and the produced daughter nuclides being in their ground or isomeric states. The study of 244 Ü-decay modes with 62 {u2264} Z {u2264} 81 and 53 {u2264} N {u2264} 112 is accomplished using the preformed cluster model. The Ü-particle preformation probabilities (SÜ) were estimated from the experimental half-lives and the computed decay widths based on the Wentzel-Kramers-Brillouin tunneling penetrability and knocking frequency. The alpha-daughter interaction potential is computed microscopically based on the Skyrme-SLy4 nucleon-nucleon force. The nuclear structure effects on the decay width and the half-life time of the exotic nucleus are taken into account. For instance, the influence of the excitation energies of the involved nuclei in their isomeric states and their spin-parity assignments are considered. We found that the favored Ü-decay mode from a ground state to an isomeric state shows larger Ü-preformation probability than the favored and unfavored decays of the same isotope but from isomeric to ground states. The favored decay mode from isomeric- to ground-state exhibits rather less SÜ relative to the other decay modes from the same nuclide. The favored decay modes between two isomeric states tend to yield larger SÜ and less partial half-life compared with the favored and unfavored decays from the same nuclides but between two ground states. For the decays involving two ground states, the preformation probability is larger for the favored decay modes than for the unfavored ones. The unfavored Ü -decay modes from ground- to isomeric-states are rare. The unfavored decay modes from isomeric- to groundstates show less SÜ than that for the favored decays from the ground states of the same emitters. The unfavored Ü-decay modes between two isomeric states exhibit larger SÜ than the other Ü-decay modes from the same isomers