Now showing 1 - 6 of 6
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Preformation probability and kinematics of cluster emission yielding Pb-daughters

2023 , Joshua T. Majekodunmi , Muruthujaya Bhuyan , Khairul Anwar Mohamad Khazali , Nooraihan Abdullah , Raj Kumar

In the present study, the newly established preformation formula is applied for the first time to study the kinematics of the cluster emission from various radioactive nuclei, especially those that decay to the double shell closure Pb nucleus and its neighbors as daughters. The recently proposed universal cluster preformation formula has been established based on the concepts that underscore the influence of mass and charge asymmetry ( and ), cluster mass , and the Q-value, paving the way to quantify the energy contribution during preformation as well as during the tunneling process separately. The cluster-daughter interaction potential is obtained by folding the relativistic mean-field (RMF) densities with the recently developed microscopic R3Y using the NL and the phenomenological M3Y NN potentials to compare their adaptability. The penetration probabilities are calculated from the WKB approximation. With the inclusion of the new preformation probability , the predicted half-lives of the R3Y and M3Y interactions are in good agreement with the experimental data. Furthermore, a careful inspection reflects slight differences in the decay half-lives, which arise from their respective barrier properties. The for systems with double magic shell closure Pb daughter are found to be an order of higher than those with neighboring Pb daughter nuclei. By exploring the contributions of the decay energy, the recoil effect of the daughter nucleus is evaluated, in contrast to several other conjectures. Thus, the centrality of the -value in the decay process is demonstrated and redefined within the preformed cluster-decay model. Additionally, we have introduced a simple and intuitive set of criteria that governs the estimation of recoil energy in the cluster radioactivity.

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Numerical study of Magnetohydrodynamic blood flow through an artery with multiple stenosis

2020 , T Majekodunmi Joshua , Khairul Anwar Mohamad Khazali , Nooraihan Abdullah

The study theoretically accounts for the impact of Magnetohydrodynamics on streaming blood through an artery having multiple stenosis regions using the non-Newtonian Cross-rheological model. It is regarded that the streaming blood is unsteady and pulsative. The use of appropriate conditions is predicated on the assumption that the flow is laminar and axisymmetric which makes the problem two-dimensional. The geometry of stenosis was immobilized into a rectangular grid using the radial coordinate transformation. The finite difference scheme was employed for the numerical simulations. Specifically, magnetic field (Hartmann number), Reynolds number and severity of stenosis were varied over the entire arterial length. The results obtained predicted that increase in the Hartmann number and stenosis severity reduces the magnitude of the flow velocity, flow rate but the reverse is the case when the Reynolds number is increased. However, the wall shear stress and the resistance to flow are aided by increasing the Hartman number and the stenosis severity but reduces with increase in the Reynolds number. Hence, it is germane to apply the appropriate magnetic field in treatments otherwise, such patient may be vulnerable.

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The α-particle clustering and half-lives of the newly discovered 207,208Th decay chains within relativistic-Hartree-Bogoliubov approach

2023 , Joshua T. Majekodunmi , Deepika Jain , Khairul Anwar Mohamad Khazali , Theeb Y.T. Alsultan , Raj K. , Nujud Mohammed Badawi , M. Bhuyan

The structural and decay properties of the ground state of recently discovered neutron-deficient 207Th and remeasured 208Th isotopes Yang et al. (2022) [26] is examined using the Relativistic-Hartree-Bogoliubov (RHB) formalism using the DD-ME2 parameter set within the preformed cluster-decay model (PCM). The relativistic medium-dependant R3Y so-called DD-R3Y NN potentials are for the first time used to obtain the nucleus-nucleus potential as input into the PCM. The penetration probability is calculated using the WKB approximation, and the preformation probability (Pα) is estimated using our newly derived formula, which is based on parameters well known to influence the α -particle radioactivity. A close correlation is observed between the α-preformation factor and the crucial role of the pairing correlation in the α-decay process. Furthermore, the Pα values for the even-even nuclei are generally found to be of higher magnitude than those for the odd-A nuclei. Our results further affirm that the odd-even staggering effect on the Qα 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.

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A review on the Skyrme Hartree-Fock model and related topics

2017 , Nooraihan Abdullah , Khairul Anwar Mohamad Khazali , Zaliman Sauli

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Decay properties of 253, 255Rf using the relativistic Mean-Field framework within the preformed Cluster-Decay model

2023 , Joshua T. Majekodunmi , Nishu Jain , Khairul Anwar Mohamad Khazali , Nooraihan Abdullah , Raj Kumar , Muruthujaya Bhuyan

Most neutron-deficient α emitters are known to be of great relevance to the astrophysical rapid neutron capture process in superheavy nuclei. Therefore, in the present work, the decay properties of newly observed superheavy nuclei with Z = 102, i.e., 249No isotope from the α-decay of 253Rf is theoretically investigated using the relativistic mean field (RMF) framework and the NL3* parameter set within the preformed cluster-decay model (PCM). The α-decay chain of 255f is also considered. The RMF densities are folded with the R3Y nucleon-nucleon (NN) potential to deduce the nuclear interaction potential between the decaying fragments. A complete understanding of the penetration of an α-particle across the nuclear Coulomb barrier gives outstanding credence to the assumptions of quantum mechanics. The presence of shell/sub-shell closure is indicated by the formation of peaks along the decay chain and was found to alter the conventional scaling factor observed earlier in the results of the PCM. The calculated half-lives are in close agreement with recent experimental measurements.

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Variational Monte Carlo study of light nuclei

2015 , Khairul Anwar Mohamad Khazali

An outstanding problem in Variational Monte Carlo (VMC) calculations with realistic interactions like Argonne V18 and Urbana IX three-body interactions is that p-shell nuclei turn out to be grossly under bound as compared to the Green’s Function Monte Carlo (GFMC) calculations. A similar situation exists in Diffusion Monte Carlo calculations with somewhat simplified interactions. In this thesis, we improve upon the VMC calculations by bringing about several variations in the established procedure of performing variational calculations. In the first variation, the effect of the errors as a function of the number of particles in the variational wave function are analyzed and then a correction through expanding the radial part in terms of a complete set are made and treat the expansion coefficients as variational parameters. Second variation consists in modifying the variational wave function structure. The state of the art variational wave function for s- and p-shell nuclei consists of two parts, where the first part is a Jastrow part operated upon by a symmetrized sum of two-body operatorial correlations and in the second part this outcome is then operated by a sum of unity, operatorial threebody and spin-orbit two-body correlations. A considerable improvement is obtained over the binding energies, wave functions and variance for the light nuclei 3H, 4He and 6Li by using these two variations. We obtain noticeable improvement in the quality of the wave function and lowering of the energies compared to earlier results. The new energies are –8.38 MeV, –28.07 MeV and –29.90 MeV for 3H, 4He, and 6Li respectively. All the computations have been taken away on a multiprocessor machine developed indigenously