arXiv subjects

Kyoungsu Heo

Publications and source records attributed to Kyoungsu Heo.

9 recordsLinked to original sources

arXiv2026

Charge-symmetry-breaking effects on displacement energies and charge radius differences in mirror nuclei

We study the effect of charge symmetry breaking (CSB) energy density function (EDF) on the mirror displacement energies (MDEs) and charge radius differences of mirror nuclei within the self-consistent Hartree-Fock-Bogolyubov (HFB) model taking Skyrme EDFs, SLy4 and SkM* as the central part of nuclear potential. We introduce the volume and the derivative terms in CSB EDF and calibrate the strength adopting four reference mirror pairs $^{34}$Ar--$^{34}$S, $^{36}$Ca--$^{36}$S, $^{38}$Ca--$^{38}$Ar, and $^{54}$Ni--$^{54}$Fe, for which experimental data of both MDEs and mirror charge-radius differences are available. We introduce a sensitivity matrix which connects two CSB terms to residuals of MDEs and mirror charge-radius differences after subtracting the effect of Coulomb interaction. By using the sensitivity matrix, we found out that the derivative term is important to reproduce both observables in a good accuracy together with the volume term, especially for the residual of mirror charge radii. The optimized CSB EDF are further applied to predict the charge radius differences of mirror pairs, $^{40}$Ti--$^{40}$Ar, $^{42}$Ti--$^{42}$Ca, $^{46}$Cr--$^{46}$Ti, and $^{50}$Fe--$^{50}$Cr. We pointed out also that the CSB effects change neutron skins of mirror proton-rich nuclei at the $10^{-2}$ fm level so that the CSB contributions must be included before charge-radius differences between mirror nuclei are used to extract neutron-skin or symmetry-energy parameters.

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arXiv2026

Spin-Dependent Nucleon-Nucleus Interactions Constrained by Neutron Observables and Their Impact on Near-Barrier Proton Fusion

We investigate the role of spin-dependent nucleon-nucleus interactions in nuclear reactions. To this end, we use neutron spin observables to constrain the dominant central spin-spin form factors and then apply the corresponding like-channel interactions to near-barrier fusion in the $p+{}^{93}$Nb system. The interactions are constructed within a folding framework based on a finite-range effective nucleon-nucleon force and organized in terms of radial form factors associated with their spin-spin, tensor, and spin-orbit components. Neutron spin observables in the $n+{}^{27}$Al, $n+{}^{59}$Co, and $n+{}^{93}$Nb target systems are analyzed within a distorted-wave Born approximation (DWBA) framework to constrain the sign and normalization in the central spin-spin parts of the radial form factors and to examine the assembled operator conventions. The calculation reproduces the observed sign systematics of the neutron spin observables for the three targets, indicating that the essential spin-dependent structure is properly incorporated. The unlike-channel (neutron-proton) interaction constrained by neutron scattering is then reconstructed for the corresponding like-channel (proton-proton) interaction and applied to a coupled-channels description of near-barrier fusion for the $p+{}^{93}$Nb system. The resultant spin-dependent interactions lead only to a weak modification of the effective barrier and change the fusion cross section by about $0.01$-$0.03\%$ in the present calculation. These results show that the corresponding real spin-dependent correction in the like-channel is strongly suppressed in near-barrier fusion in $p+{}^{93}\mathrm{Nb}$. The present work thus connects the neutron-scattering constraints on the operator conventions with the fusion calculation in the proton channel, and quantifies the magnitude of the corresponding real spin-dependent correction in near-barrier fusion.

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arXiv2026

Phenomenological Criteria of Halo Nuclei in Ne Isotopes via Diffuseness and Helm-Model Approaches with Reaction Cross Sections

We present a systematic study of halo characteristics in the neutron-rich isotopes 28-32Ne within the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc). Microscopic density distributions are analyzed in coordinate space, momentum space, and reaction observables to establish a quantitative and locally defined criterion for halo identification in medium-mass nuclei. The DRHBc densities reveal a pronounced neutron extension in 31Ne. A phenomenological analysis based on deformed Woods-Saxon fits shows a clear isotopic anomaly in the surface diffuseness parameter, with a value of about 1.1 fm for 31Ne, significantly larger than those of neighboring isotopes. The anomalously large diffuseness is therefore treated as the primary phenomenological halo signature, whereas the reduced fitted radius parameter is used only as a supporting consequence of the chosen normalization and tail-sensitive fit. Helm-model form-factor analysis demonstrates that deformation contributes to geometric smearing but does not fully account for the extended spatial structure, as reflected in the enhanced difference between microscopic and folded rms radii. Glauber reaction cross section calculations further confirm a robust relative enhancement of the interaction cross section for 31Ne that persists across reasonable nucleon-nucleon interaction prescriptions. These complementary analyses consistently identify 31Ne as the most prominent halo candidate within the 28-32Ne isotopic chain, while 32Ne exhibits intermediate features and 29Ne shows no clear halo signature. The present framework provides a practical and quantitative approach for identifying halo phenomena in deformed, neutron-rich nuclei beyond the light-mass region.

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arXiv2026

Probing Neutron Skins with KDAR Neutrinos: From Coherent to Diffractive Elastic Neutrino--Nucleus Scattering

We investigate coherent elastic neutrino--nucleus scattering (CE$ν$NS) induced by pion--decay--at--rest ($π$DAR) and kaon--decay--at--rest (KDAR) neutrinos, with emphasis on the transition from strict coherence to the diffractive regime. Organizing CE$ν$NS observables in terms of the dimensionless variable $qR$, we show that $π$DAR measurements remain confined to the near--coherent region for all nuclei, whereas KDAR neutrinos ($E_ν=236$~MeV) extend the kinematics into $qR\gtrsim1$, where recoil spectra develop genuine shape sensitivity to the nuclear weak form factor. Using representative light, medium--mass, and heavy nuclei ($^{12}$C, $^{40}$Ca, $^{48}$Ca, and $^{208}$Pb), we examine relevant cross sections and quantify the statistical sensitivity to the neutron skin thickness achievable at a JSNS$^2$--like facility. For a total exposure of 10~ton$\cdot$year and realistic KDAR fluences, projected $1σ$ sensitivities reach $ΔR_{np}^{\,(1 σ)}$ $\simeq0.09$--$0.02$~fm for $^{48}$Ca and $\simeq0.07$--$0.02$~fm for $^{208}$Pb as the fluence increases. These sensitivities are competitive with, and complementary to, parity--violating electron--scattering measurements such as CREX and PREX, while relying on an electroweakly clean neutral--current probe with distinct systematic uncertainties. Our results establish KDAR--based CE$ν$NS as a quantitatively robust and complementary avenue for probing neutron skins and nuclear weak densities beyond the coherent limit.

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arXiv2025

Visualization of quantum interferences in heavy-ion elastic scattering

We investigate various interference effects in elastic scattering of the $α+ {}^{40}\text{Ca}$ system at $E_{\rm lab}=29$ MeV. To this end, we use an optical potential model and decompose the scattering amplitude into four components, that is, the near-side and the far-side components, each of which is further decomposed into the barrier-wave and the internal-wave components. Each component contributes distinctively to the angular distributions, revealing unique quantum interference patterns. We apply the Fourier transform technique to visualize these interference effects. By analyzing the images at specific scattering angles, we identify the positions and intensities of peaks corresponding to each interference component. This analysis offers insight into structural features of the angular distribution which are not apparent from the differential cross sections alone.

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arXiv2024

Suppression of the elastic scattering cross section for 17Ne + 208Pb system

We investigated the elastic scattering, inelastic scattering, breakup reaction, and total fusion reactions of 17Ne + 208Pb system using the optical model (OM) and a coupled channel (CC) approaches. The aim of this study is to elucidate the suppress of the elastic cross-section that is invisible in proton-rich nuclei such as 8B and 17F projectiles but appears in neutron-rich nuclei such as 11Li and 11Be projectiles. The results revealed that this suppression was caused mainly by the nuclear interaction between the projectile and target nucleus rather than the strong Coulomb interaction observed in neutron-rich nuclei and the contributions of Coulomb excitation interaction due to two low-lying E2 resonance states are relatively small. From the simultaneous chi-square analysis of the 17Ne + 208Pb system, we can infer a strong suppression effect in the elastic scattering cross-section due to the nuclear interaction between the projectile and target nucleus, rather than the Coulomb interaction as observed in neutron-rich nuclei. Also, the contribution of the direct reaction, comprising the inelastic scattering and breakup reaction cross-sections, accounted for almost half of the total reaction. Finally, we perform the CC calculation using the parameters obtained from our OM calculation but our CC calculations could not explain the 15O production cross section.

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arXiv2024

Folding potential with modern nuclear density functionals and application to 16O+208Pb reaction

Double folding potential is constructed using the M3Y interaction and the matter densities of the projectile and target nuclei obtained from four microscopic energy density functional (EDF) models. The elastic scattering cross sections for the 16O+208Pb system are calculated using the optical model with the double folding potentials of the four EDF models. We focus on the correlation between the matter densities and the behavior the double folding potential and the elastic scattering cross sections. First, the matter and charge densities are examined by comparing the results of the four EDF models. There is a slight difference in the density in the internal region, but it is negligible in the outer region. Next, we calculate the double folding potential with the matter densities obtained from the four EDF models. Differences between the models are negligible in the outer region, but the potential depth in the internal region shows model dependence, which can be understood from the behavior of matter densities in the internal region. Another point is that the double folding potential is shown to be weakly dependent on the incident energy. Finally, the elastic scattering cross sections have no significant model dependence except for the slight difference in the backward angle.

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arXiv2023

Revisiting the Gamow Factor of Reactions on Light Nuclei

This study provides an improved understanding of the penetration probabilities (PPs) in nuclear reactions of light nuclei by correcting the assumptions used in the conventional Gamow factor. The Gamow factor effectively describes the PP in nuclear reactions based on two assumptions: low particle energy than the Coulomb barrier and neglecting the dependence of nuclear interaction potential. However, we find that the assumptions are not valid for light nuclei. As a result of a calculation that excludes the assumptions, we obtain the PP that depends on the nuclear interaction potential depth for the light nuclei. For the potential depth fitted by the experimental fusion cross-section, we present that PPs of light nuclei (D+D, D+T, D+$^3$He, p+D, p+$^6$Li, and p+$^7$Li) become higher than the conventional one near the Coulomb barrier. We also discuss the implications of the modified PP, such as changes in the Gamow peak energy, which determine the measurement of the energy range of the nuclear cross-section in experiments, and the electron screening effect.

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arXiv2018

Extended optical model analyses of $^{11}$Be+$^{197}$Au with dynamic polarization potentials

We discuss angular distributions of elastic, inelastic, and breakup cross sections for $^{11}$Be + $^{197}$Au system, which were measured at energies below and around Coulomb barrier. To this end, we employ Coulomb dipole excitation (CDE) and long-range nuclear (LRN) potential to take into account long range effects by halo nuclear system and break up effects by weakly-bound structure. We then analyze recent experimental data including 3-channes i.e. elastic, inelastic, and breakup cross sections, at $E_{\textrm{c.m.}}$=29.6 MeV and $E_{\text{c.m.}}$=37.1 MeV. From the extracted parameter sets using $χ^{2}$ analysis, we successfully reproduce the experimental angular distributions of the elastic, inelastic, and breakup cross sections for $^{11}$Be+$^{197}$Au system simultaneously. Also we discuss the necessity of LRN potential around Coulomb barrier from analyzed experimental data.

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