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    Investigation of Gamow-Teller strength of 186Hg within deformed pn-QRPA
    (Canadian Science Publishing, 2022) Nabi, Jameel-Un; Ullah, Asim; Kabir, Abdul; Muneem, Abdul; Boyukata, Mahmut
    Recently, the total absorption gamma spectroscopy technique was used to determine the Gamow-Teller (GT) distribution of beta-decay of Hg-186. It was concluded that the best description of the measured data was obtained with dominantly prolate components for both parent Hg-186 and daughter Au-186. Motivated by the recent findings, we investigate the effect of nuclear deformation on the energy distribution of the GT strength of the decay of Hg-186 into Au-186 within the framework of proton-neutron quasiparticle random phase approximation (pn-QRPA) based on the deformed Nilsson potential. To do the needful, we first calculate the energy levels and shape prediction of Hg-186 within the interacting boson model. The computed GT strength distribution satisfied the model-independent Ikeda sum rule 100% (99.98%) for the prolate (oblate) case. Based on the strength distributions, the deformed pn-QRPA model with separable interaction prefers a prolate shape for the ground state of Hg-186 and supports the shape coexistence for this nucleus.
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    Investigation of Gamow–Teller strength of186 Hg within deformed pn-QRPA
    (Canadian Science Publishing, 2022) Nabi, Jameel-Un; Ullah, Asim; Kabir, Abdul; Muneem, Abdul; Böyükata, Mahmut
    Recently, the total absorption gamma spectroscopy technique was used to determine the Gamow–Teller (GT) distribution of ?-decay of186 Hg. It was concluded that the best description of the measured data was obtained with dominantly prolate components for both parent186 Hg and daughter186 Au. Motivated by the recent findings, we investigate the effect of nuclear deformation on the energy distribution of the GT strength of the decay of186 Hg into186 Au within the framework of proton– neutron quasiparticle random phase approximation (pn-QRPA) based on the deformed Nilsson potential. To do the needful, we first calculate the energy levels and shape prediction of186 Hg within the interacting boson model. The computed GT strength distribution satisfied the model-independent Ikeda sum rule 100% (99.98%) for the prolate (oblate) case. Based on the strength distributions, the deformed pn-QRPA model with separable interaction prefers a prolate shape for the ground state of186 Hg and supports the shape coexistence for this nucleus. © 2022 The Author(s).
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    Nuclear structure properties and weak interaction rates of even-even Fe isotopes
    (Elsevier, 2024) Nabi, Jameel-Un; Boyukata, Mahmut; Ullah, Asim; Riaz, Muhammad
    Nuclear structure properties and weak interaction rates of neutron -rich even-even iron (Fe) isotopes (A = 50 - 70) are investigated using the Interacting Boson Model -1 (IBM -1) and the proton-neutron Quasiparticle Random Phase Approximation (pn-QRPA) model. The IBM -1 is used for the calculation of energy levels and the B(E2) values of neutron -rich Fe isotopes. Later their geometry was predicted within the potential energy formalism of the IBM -1 model. Weak interaction rates on neutron -rich nuclei are needed for the modeling and simulation of presupernova evolution of massive stars. In the current study, we investigate the possible effect of nuclear deformation on stellar rates of even-even Fe isotopes. The pn-QRPA model is applied to calculate the weak interaction rates of selected Fe isotopes using three different values of deformation parameter. It is noted that, in general, bigger deformation values led to smaller total strength and larger centroid values of the resulting Gamow-Teller distributions. This later translated to smaller computed weak interaction rates. The current finding warrants further investigation before it may be generalized. The reported stellar rates are up to 4 orders of magnitude smaller than previous calculations and may bear astrophysical significance.
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    Nuclear structure properties of even-even chromium isotopes and the effect of deformation on calculated electron capture cross sections
    (ELSEVIER, 2020) Nabi, Jameel-Un; Boyukata, Mahmut; Ullah, Asim; Riaz, Muhammad
    In this study, we investigate the role of the nuclear deformation on the calculated electron capture cross section (ECC) of even-even chromium (Cr) isotopes. We first determined the nuclear structure properties of these nuclei within the interacting boson model-1 (IBM-1). The energy spectra and E2 transition probabilities were calculated by fitting the parameters in the model formalism. The analysis of the potential energy surface were also performed to predict the geometric shape of the Cr nuclei by plotting their contour plot in the plane of (beta, gamma ) deformation parameters. Later, we calculated the ECC within the proton-neutron quasiparticle random phase approximation (pn-QRPA) model. In particular we studied how the calculated ECC changed with different values of nuclear deformation parameter. The calculated Gamow-Teller (GT) strength distributions were widely spread among the daughter states. The total GT strength decreased with increasing value of the beta parameter. The computed ECC values, however, increased with increase in the beta value of the Cr isotopes. (c) 2020 Elsevier B.V. All rights reserved.
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    Re-examination of nuclear structure properties and shape co-existence of nuclei around A ∼ 70
    (Elsevier, 2024) Nabi, Jameel-Un; Bayram, Tuncay; Böyükata, Mahmut; Ullah, Asim; Hayder, Anes; Naqvi, Syeda Zainab
    We re-examine the nuclear structure properties of waiting point nuclei around A similar to 70 using the interacting boson model-1 (IBM-1) and the relativistic mean field (RMF) model. Effective density-dependent meson-exchange functional (DD-ME2) and density-dependent point-coupling functional (DD-PC1) were used for the RMF calculations. We calculated the energy levels, the geometric shapes, binding and separation energies of nucleons and quadrupole deformation parameters (beta 2). The shape co-existence phenomena in A similar to 70 nuclei (Se-68, Se-70, Br-70, Kr-70, Kr-72, Kr-74, Rb-74 and Sr-74) was later investigated. Spherical and deformed shapes of the selected waiting point nuclei were computed using the IBM-1 and RMF models, respectively. The proton-neutron quasiparticle random phase approximation (pn-QRPA) model was used to calculate beta-decay properties (Gamow-Teller strength distributions, beta-decay half-lives and branching ratios) of selected nuclei as a function of beta 2. The results revealed a significant variation in calculated half-lives and Gamow-Teller strength distributions as the shape parameter was changed. The beta 2 computed via DD-ME2 functional resulted in half-lives in best agreement with the measured data.
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    Re-examination of β-decay in Hg, Pb and PoIsotopes
    (Iop Publishing Ltd, 2023) Nabi, Jameel-Un; Bayram, Tuncay; Riaz, Muhammad; Ullah, Asim; Hayder, Anes; Şentürk, Şevki; Böyükata, Mahmut
    This study re-examines the effect of nuclear deformation on the calculated Gamow-Teller (GT) strength distributions of neutron-deficient (Hg178-192, Pb185-194 and Po196-206) nuclei. The nuclear ground state properties and shape parameters were calculated using the Relativistic Mean Field model. Three different density-dependent interactions ((DC)-C-3, DD-ME2 and DD-PC1) were used in the calculation. Estimated shape parameters were later used within the framework of deformed proton-neutron quasi-random phase approximations model, with a separable interaction, to calculate the GT strength distributions, half-lives and branching ratios for these neutron-deficient isotopes. It was concluded that half-lives and GT strength distributions vary considerably with change in shape parameter.