Spontaneous ternary fission of Nobelium 260 / Ahmed Sayed Hashem Kotb ; Supervised Mahmoud Yahia Ismail , Walaa Mohamed Seif , Ali Yahia Ellithi

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

The ternary fragmentation of ²⁶{u⁰⁰B⁰}No for even mass third fragments ranging from A₃ = 4 to A₃ = 52 has been studied within the framework of the three-cluster model based on collinear configuration, with the light charged particle A₃ located along the other two fragments A₁ and A₂ , and equatorial configuration assuming spherical shape of the fragments satisfying the condition A₁ {u2265} A₂ {u2265} A₃ . The nuclear and Coulomb potentials are calculated from double folding model assuming sharp surfaces for the three fragments. The nuclear contribution of the heavy ion potential was derived from the effective M3Y-Reid nucleon-nucleon interaction. For every fixed mass pair (A₁ , A₂ ), a pair of charges is singled out for which fragmentation potential is searched for minimizing and eventually the relative yield is maximized. The most probable ternary fragment combinations in the spherical case are predicted and their independent relative yields are calculated. In these fragment combinations it is found that, among the three fragments, at least one (or two) of the fragment(s) associates itself with the neutron (or proton) closed shell and in some cases even with the doubly closed shell in the spherical case. The most probable fragment combinations of equatorial configuration have relatively higher fragmentation potentials, higher relative yields, higher potential barrier heights, larger barrier positions and lower penetration probabilities than those of collinear configuration. The effect of the inclusion of quadrupole and hexadecapole deformations on both the behavior and magnitude of the ternary fragmentation potential which is calculated at four different orientations of the two heavy fragments A₁ and A₂, 0{u00B0} - 0{u00B0}, 90{u00B0} - 90{u00B0} 0{u00B0} - 90{u00B0} and 90{u00B0} - 0{u00B0}, is also , studied. We see that the ternary fragmentation potential corresponding to 0{u00B0} - 0{u00B0} orientation has the lowest values compared to the other orientations due to very high positive quadrupole and hexadecapole deformations of the fragments A₁ and A₂ and the most probable fragment combinations are found to be changed ompared to the spherical case.

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