Ternary Fission Mass Distributions of Superheavy Nuclei Within a Statistical Model

Abstract

Theoretical models predict the existence of an island of stability at the proton shell closures Z = 114 or 120 or 126 and at the neutron shell closure N = 184 due to the microscopic shell effects. In this article, mass distributions of fragments from ternary fission of superheavy nuclei are investigated with the aid of the statistical theory. We have computed the fission mass distributions for the simultaneous decay into three fragments of nuclei ²⁹⁸Fl, $^{304}_{120}$X and $^{310}_{126}$X, at the two excitation energies E^∗ = 20 and 50 MeV, with the constraint on one of the fragment to be ⁵⁰Ca and ⁷²Ni. With the fixed third fragments of mass number A₃ = 50, 72, asymmetric breakup (A₁ ≠ A₂) has a larger ternary fission yield for Z = 114, 120 and 126 isotopes. Predominantly, one of the fragments with the neutron closed-shell nucleus (N ≈ 82, 50) is favoured at higher excitation energies. Subsequently, we have considered the ternary fragmentation of the neutron-rich superheavy elements $^{314}_{120}$X and $^{320}_{126}$X again for the same excitation energies and fixed third fragment. Interestingly, for the superheavy nucleus $^{314}_{120}$X, symmetric fission (A₁ ≈ A₂) with doubly closed-shell nuclei ¹³²Sn for the third fragment ⁵⁰Ca is favoured at higher E^∗. For the isotope $^{320}_{126}$X, relative yields of fragments with closed shell increase at higher excitation energy.