arXiv subjects

Minh-Loc Bui

Publications and source records attributed to Minh-Loc Bui.

10 recordsLinked to original sources

arXiv2025

Pairing Strength and Quadrupole-Soft Tin Isotopes

Background: Understanding the experimental $B(E2)$ values for Sn isotopes around $^{110}$Sn has been a significant challenge in nuclear structure studies for over a decade. Both experimental data and many, though not all, calculations suggest a picture of the light Sn isotopes as being quadrupole-soft, that is, spherical, yet easy to deform. Purpose: To investigate the delicate interplay of quadrupole deformation and pairing correlations in these nuclides. In particular, by using slightly enhanced pairing, we ask: can we generate spherical mean-field solutions that describe the data? Method: First, we apply the standard spherical Skyrme HFBCS-QRPA calculation with default pairing parameters, allowing us to identify nuclides that are unstable against quadrupole deformation among Sn isotopes. Next, we moderately enhance the pairing strength to reproduce the experimental binding energy in the deformation-unstable isotopes. Result: Within our choice of Skyrme parameters and use of density-independent pairing, this moderate adjustment sufficiently stabilizes the HFBCS ground states against deformation, ensuring a successful QRPA calculation and, more importantly, leading to more realistic properties for the quadrupole $2^+$ states. Conclusion: Careful attention to the sensitive interplay of pairing and shell effects in deformation-soft nuclides can be crucial to their correct descriptions. This sensitivity can be exploited to optimize the treatment of pairing in phenomenological approaches such as the present Skyrme-QRPA.

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arXiv2024

Landscape of nuclear deformation softness with spherical quasi-particle random phase approximation

We investigate the stability and softness of nuclei against quadrupole, octupole, and hexadecapole deformation. By applying the spherical Skyrme-force Hartree-Fock Bardeen-Cooper-Schrieffer quasi-particle random phase approximation, we diagnose ground-state deformation when imaginary solutions are obtained, i.e., the spherical ground state {\em collapses}. We also calculate the multipole polarizability in spherical nuclei with no collapse, as a measure of softness. This numerically light and theoretically sound method is found able to capture deformation patterns across the nuclide chart. The connection between the intrinsic shape of nuclei and the dynamics of their low-lying collective states is established and the role of shell structure is discussed.

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arXiv2023

Origin of octupole deformation softness in atomic nuclei

Recent high-energy heavy ion collision experiments have revealed that some atomic nuclei exhibit unusual softness and significant shape fluctuations. In this work, we use the fully self-consistent mean-field theory to identify all even-even nuclei that are unstable or soft against octupole deformation. All exceptional cases of enhanced octupole transition strengths in stable even-even nuclei throughout the nuclide chart are resolved and the origin is found in basic shell structure. The presence of atomic nuclei exhibiting significant softness to quadrupole-octupole deformation is suggested. These results represent a significant advance in our understanding of the underlying mechanisms of nuclear octupole deformation and have implications for further experimental and theoretical studies.

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arXiv2023

Proton \textit{s}-resonance states of $^{12}$C and $^{14,15}$O within the Skyrme Hartree-Fock mean-field framework

The excitation functions of proton elastic scattering on $^{12}$C and $^{14,15}$O nuclei at the energies near the proton-emission threshold are calculated using the Skyrme Hartree-Fock (SHF) in continuum approach. For each excitation function, the first resonance is identified as the $s$-state resonance of the mean-field theory. For $^{15}$O, whose ground-state spin is nonzero, the $s$-state resonance splits into two resonances via the spin-spin component of the optical potential. With a slight adjustment of the strength of central potential, which is obtained from the SHF in continuum approach, the excitation functions of proton elastic scattering for the three nuclei can be explained with high accuracy. The proposed framework can provide a practical method to explain nuclear scattering at the energies near the proton-emission threshold with minimal experimental input.

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arXiv2022

Coulomb corrections to Fermi beta decay in nuclei

We study the influence of the Coulomb force on the Fermi beta-decays in nuclei. This work is composed of two main parts. In the first part, we calculate the Coulomb corrections to super-allowed beta decay. We use the notion of the isovector monopole state and the self-consistent charge-exchange Random Phase Approximation to compute the correction. In the second part of this work, we examine the influence of the anti-analog state on isospin mixing in the isobaric analog state and the correction to the beta-decay Fermi transition.

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arXiv2022

Low-energy $^7$Li($n,\gamma$)$^8$Li and $^7$Be($p,\gamma$)$^8$B radiative capture reactions within the Skyrme Hartree-Fock approach

The electromagnetic dipole transitions in $^7$Be($p,\gamma$)$^8$B and $^7$Li($n,\gamma$)$^8$Li reactions at the keV-energy region were analyzed simultaneously within the Skyrme Hartree-Fock potential model. The Skyrme Hartree-Fock calculation is adopted as a microscopic approach to obtain consistently the single-particle bound and scattering states in the calculation of the radial overlap function within the potential model. All non-resonant and resonant electromagnetic dipole transitions are taken into account. The electric dipole transitions are successfully described with the slightest adjustment. The resonant magnetic dipole transitions at $633$ keV and $2184$ keV of $^7$Be($p,\gamma$)$^8$B reaction, and the one at $222$ keV of $^7$Li($n,\gamma$)$^8$Li are also analyzed. The astrophysical $\mathcal{S}_{17}(0)$ factor of $^7$Be($p,\gamma$)$^8$B reaction is found to be $22.3$ eV\,b.

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arXiv2022

Single-particle properties of the near-threshold proton-emitting resonance in $^{11}$B

The excitation function of proton elastic scattering from $^{10}$Be at keV energy is calculated using the self-consistent Skyrme Hartree-Fock in the continuum method. The calculation successfully reproduces the narrow near-threshold proton-emitting resonance ($E_x = 11.4$ MeV, $\Gamma = 6$ keV, and quantum number $J^{\pi} = 1/2^+$) in $^{11}$B relevant to the $\beta$-delayed proton emission of $^{11}$Be. This supports the recent experimental result of Y. Ayyad \textit{et al.} at the ReA3 re-accelerator facility of the National Superconducting Cyclotron Laboratory (NSCL) at the Michigan State University. The resonance is interpreted as the $s_{1/2}$ single-proton resonance state in the Skyrme Hartree-Fock mean-field theory.

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arXiv2021

Potential model with bound-to-continuum approach for low-energy nucleon radiative capture by $^{12}$C and $^{16}$O

The nucleon radiative capture reactions are important in pure and applied nuclear physics, especially in nuclear astrophysics. The keV-nucleon radiative capture reactions are studied with $^{12}$C and $^{16}$O targets using the bound-to-continuum potential model in which both scattering and bound states are treated simultaneously and based on the Skyrme Hartree-Fock approximation. The obtained results are shown to be in good agreement with the available experimental data. Alongside astrophysical aspects, the nuclear structure features were revisited for enlarging the prospect of adopting the nucleon radiative capture processes as a spectroscopic tool.

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arXiv2021

Bound-to-continuum potential model for the $(p,γ)$ reactions of the CNO cycle

The study of CNO cycle involves the examination of the proton radiative capture, or the $(p,γ)$ reactions below 2 MeV. The astrophysical $\mathcal{S}$ factor characterizing the $(p,γ)$ reaction is usually reduced to the electric dipole transition $E1$ from the scattering state to the bound state. In this work, the partial scattering and the single-particle bound wave functions in the reduced matrix element of the transition are obtained from the single self-consistent mean-field potential deduced from the Skyrme Hartree-Fock calculation. The astrophysical $\mathcal{S}$ factors of the $(p,γ)$ reactions in the CNO cycle were successfully reproduced. The self-consistent Hartree-Fock calculation from the discrete to the continuum is a promising approach for the microscopic analysis of the nucleon-induced reactions in nuclear astrophysics.

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arXiv2018

Study of the double Gamow-Teller transitions using the shell model approach

The double Gamow-Teller strength distributions in the lightest double beta-decay candidate $^{48}$Ca and its isotope $^{46}$Ca were calculated using the nuclear shell model by applying the single Gamow-Teller operator two times sequentially on the ground state of parent nucleus. The nuclear matrix element of the double Gamow-Teller transition from the ground state to the ground state that goes into the double beta decay calculation was shown as a small fraction of the total transition.

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