arXiv subjects

Ban Zhang

Publications and source records attributed to Ban Zhang.

4 recordsLinked to original sources

arXiv2025

Mock Observations for the CSST Mission: Main Surveys--the Stray Light

Stray light significantly influences the detection capabilities of astronomical telescopes. The actual stray-light level during observations depends not only on the telescope's inherent stray-light suppression capability but also on its operational orbit conditions. Accurate estimation of stray-light levels is crucial for assessing image quality and performing realistic scientific simulations. To rapidly estimate stray-light levels under realistic, complex operational conditions, we developed an analytical model tailored to the China Space Station Telescope (CSST). Our model simulates stray-light backgrounds generated by off-field sources such as moonlight, starlight, and earthshine, incorporating the effects of zodiacal light, as well as scattering and ghost images induced by bright in-field stars. The proposed method allows quick and accurate evaluation of stray-light conditions, facilitating both image simulation and observational scheduling.

astro-ph.IM↗

arXiv2025

Probing the neutron-skin thickness via the double-charge exchange reactions in pion-nucleus collisions

Within the framework of Lanzhou quantum molecular dynamics (LQMD) transport model, we investigate the influence of the neutron-skin thickness of neutron-rich nuclei on the pion emission in the double-charge exchange reactions near the $\triangle$-resonance energy, in particular, the rapidity and transverse momentum spectra, charged pion ratios et al. The reactions induced by pions are associated with the multiple processes of pions, nucleons and $\triangle$-resonances, correlated with the neutron-skin thickness. It is found that the kinetic energy spectra of $\pi^{-}$/$\pi^{+}$ ratio are sensitive to the neutron-skin thickness of neutron-rich nuclei for extracting the subsaturation-density symmetry energy. The double-charge exchange reactions are influenced by the neutron-skin thickness, in-medium properties of resonances, pion-nucleon potential and pion-nucleon scattering.

nucl-th↗

arXiv2024

Correlation of the symmetry energy at subsaturation densities and neutron-skin thickness in low-energy antiproton induced reactions

Within the framework of Lanzhou quantum molecular dynamics transport model, the neutron-skin thickness and its impact on the nuclear dynamics induced by low-energy antiprotons are investigated thoroughly. The correlation of the neutron-skin thickness and stiffness of symmetry energy is implemented into the transport model via the Fermi distributions of the proton and neutron density profiles. It is found that antiprotons are predominantly annihilated in the subsaturation density region (0.4$\rho_{0}$-0.8$\rho_{0}$). The isospin ratios of free neutrons to protons (n/p) and charged pion yields ($\pi^{-}$/$\pi^{+}$) in collisions of antiprotons on $^{48}\rm{Ca}$ and $^{208}\rm{Pb}$ are analyzed systematically for extracting the symmetry energy in the domain of subsaturation densities. The n/p ratio is sensitive to the stiffness of symmetry energy in the low-density region and a soft symmetry energy leads to the larger n/p ratio, in particular with decreasing the beam momentum. The $\pi^-/\pi^+$ ratio is also enhanced with the soft symmetry energy at kinetic energies below 150 MeV.

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arXiv2023

Shedding light on the pion production in heavy-ion collisions and application into the neutron star matter properties

Within the framework of the quantum molecular dynamics transport model, the pion production and constraint of the high-density symmetry energy in heavy-ion collisions near threshold energy have been thoroughly investigated. The energy conservation in the decay of resonances and reabsorption of pions as well as in the inelastic nucleon-nucleon and nucleon-resonance collisions are taken into account. The isospin diffusion in the low-density region (0.2$\rho_{0}$ - 0.8$\rho_{0}$) and high-density region (1.2$\rho_{0}$ - 1.8$\rho_{0}$) is investigated by analyzing the spectra of neutron/proton and $\pi^{-}/\pi^{+}$ ratios in the isotopic reactions of $^{132}$Sn + $^{124}$Sn and $^{108}$Sn + $^{112}$Sn at the incident energy of 270 MeV/nucleon, in which the symmetry energy manifests the opposite effect in the different density domain. The controversial conclusion of the $\pi^{-}/\pi^{+}$ ratio for constraining the high-density symmetry energy by different transport models with the FOPI data has been clarified. A soft symmetry energy with the slope parameter of $L(\rho_{0}) = 42\pm 25$ MeV by using the standard error analysis within the range of $1\sigma$ is obtained by analyzing the experimental data from the S$\pi$RIT collaboration. The neutron stars with the maximal mass of 2 $M_{\odot}$ and radius of 11-13 km are obtained with the constrained symmetry energy.

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