Possible decay modes in the heavy to superheavy island of range 98 < Z < 120 within the relativistic mean-field approach / Theeb Y. T. Alsultan

Theeb Y. T. , Alsultan (2024) Possible decay modes in the heavy to superheavy island of range 98 < Z < 120 within the relativistic mean-field approach / Theeb Y. T. Alsultan. PhD thesis, Universiti Malaya.

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Abstract

This thesis aims to explore alpha radioactivity in superheavy nuclei using semi-empirical and microscopic approaches. The primary objectives include: firstly, examining the influence of nuclear rotation on the decay half-lives of superheavy nuclei within the range 98 ::; Z ::; 120 using the axially deformed relativistic Hartree-Bogoliubov theory in the continuum (DRHBc), which incorporates recent semi-empirical formulae to provide a systematic understanding of alpha-radioactivity. The findings suggest that the predictions made by all semi-empirical formulae align more closely with the available experimental data when considering the rotation effect. However, it has been demonstrated that the impact of nuclear rotation gradually diminishes as the atomic nucleus becomes heavier. Secondly, the in-medium effects are incorporated into the R3Y NN potential through density-dependent nucleon-meson coupling within the relativistic Hartree-Bogoliubov (RHB) framework. This relativistic medium-dependent R3Y, called DD-R3Y NN potentials, are for the first time used to obtain the nucleus-nucleus potential as input into the Preformed cluster-decay model (PCM). The penetration probability is calculated using the WKB approximation, and the preformation probability (Pa) is estimated using a recently derived formula, which is based on parameters well known to influence the radioactivity of the a -particles. A close correlation is observed between the a-preformation factor and the crucial role of the pairing correlation in the a-decay process. Furthermore, the Pa values for the even-even nuclei are generally found to be of higher magnitude than those for the odd-A nuclei. The results further affirm the odd-even staggering effect on the Qa values and its accompanying effects on other observables such as the charge radii and the decay half-lives, which can be largely attributed to the pairing correlation and Pauli blocking of the unpaired valence nucleons. Thus, correlations are established between bulk properties and decay properties in the ground state of207•208Th isotopic chains.

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