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https://hdl.handle.net/2440/122677
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Type: | Journal article |
Title: | Physics of even-even superheavy nuclei with 96 < Z < 110 in the quark-meson-coupling model |
Author: | Stone, J.R. Morita, K. Guichon, P.A.M. Thomas, A.W. |
Citation: | Physical Review C, 2019; 100(4):044302-1-044302-15 |
Publisher: | American Physical Society |
Issue Date: | 2019 |
ISSN: | 2469-9985 2469-9993 |
Statement of Responsibility: | J.R. Stone, K. Morita, P.A.M. Guichon, A.W. Thomas |
Abstract: | The quark-meson-coupling (QMC) model has been applied to the study of the properties of even-even superheavy nuclei with 96 ≤ Z ≤ 110, over a wide range of neutron numbers. The aim is to identify the deformed shell gaps at N=152 and N=162, predicted in macroscopic-microscopic (macro-micro) models, in a model based on the mean-field Hartree-Fock + BCS approximation. The predictive power of the model has been tested on proton and neutron spherical shell gaps in light doubly closed (sub)shell nuclei ⁴⁰Ca, ⁴⁸Ca, ⁵⁶Ni, ⁵⁶Ni, ⁷⁸Ni, ⁹⁰Zr, ¹⁰⁰Sn, ¹³²Sn, ¹⁴⁶Gd, and ²⁰⁸Pb, with results in a full agreement with experiment. In the superheavy region, the ground-state binding energies of 98 ≤ Z ≤ 110 and 146 ≤ N ≤ 160 differ, in the majority of cases, from the measured values by less than ±2.5MeV, with the deviation decreasing with increasing Z and N. The axial quadrupole deformation parameter, β₂, calculated over the range of neutron numbers 138 ≤ N ≤ 184, revealed a prolate-oblate coexistence and shape transition around N=168, followed by an oblate-spherical transition towards the expected N=184 shell closure in Cm, Cf, Fm, and No. The closure is not predicted in Rf, Sg, Hs, and Ds as another shape transition to a highly deformed (β₂ ≈ 0.4) shape in Sg, Hs, and Ds for N > 178 appears, while ²⁸⁸Rf (N=184) remains oblate. The bulk properties predicted by QMC, such as ground-state binding energy, two-neutron separation energy, the empirical shell-gap parameter δ₂n and Qα values, are found to have a limited sensitivity to the deformed shell gaps at N=152 and 162. However, the evolution of the neutron single-particle spectra with 0 ≤ β₂ ≤0.55 of ²⁴⁴Cm, ²⁴⁸Cf, ²⁵²Fm, ²⁵⁶No, ²⁶⁰Rf, ²⁶⁴Sg, ²⁶⁸Hs, and ²⁷²Ds, as representative examples, gives a (model-dependent) evidence for the location and size of the N=152 and 162 gaps as a function of Z and N. In addition, the neutron number dependence of neutron pairing energies provides supporting indication for existence of the energy gaps. Based on these results, the mean-field QMC and macro-micro models and their predictions of deformed shell structure of superheavy nuclei are compared. Clearly the QMC model does not give results as close to the experiment as the macro-micro models. However, considering that it has only four global variable parameters (plus two parameters of the pairing potential), with no local adjustments, the results are promising. |
Rights: | ©2019 American Physical Society |
DOI: | 10.1103/PhysRevC.100.044302 |
Grant ID: | http://purl.org/au-research/grants/arc/CE110001104 http://purl.org/au-research/grants/arc/DP150103101 http://purl.org/au-research/grants/arc/DP180100497 |
Published version: | http://dx.doi.org/10.1103/physrevc.100.044302 |
Appears in Collections: | Aurora harvest 8 Physics publications |
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