分类： 物理学 >> 核物理学 提交时间： 2025-04-01
Xia, Dr. Sida
Zhu, Dr. Jian
Liu, Prof. Wenguan
yang, Mr. guo
Li, Dr. Wen-Jie
Sun, Miss Dan
Chen, Dr. Xue-Kun
WU, Dr. Xi Jun
摘要： As one of the candidate materials for reactors, uranium alloys face environmental challenges from neutron irradiation during operation. Metal uranium is prone to radiation defects upon irradiation. The addition of metal stabilizers to uranium alloys can enhance their adaptability to the irradiation environment. Among various stabilizers, molybdenum and niobium metals have been extensively studied due to their good solubility and compatibility with metal uranium. In this paper, molecular dynamics methods were employed to simulate the micro-irradiation defect evolution process in the U-Mo-Nb ternary alloy fuel. A potential function suitable for the U-Mo-Nb ternary alloy was trained using machine learning-based approaches. The simulation involves the irradiation cascade damage evolution process under different temperatures, various primary collision atom energies, and incident directions along different lattice vectors, analyzing the impact of different environmental factors on the defect extent of the U-Mo-Nb ternary alloy fuel. The results indicate that the maximum difference in the peak number of defects between the highest and lowest values, depending on the incidence angle, is 7.6%. Higher temperatures lead to a greater number of defect peaks, and fewer defects remain after annealing. The greater the energy of the primary collision atoms, the more defects are produced, and the longer it takes to reach the peak defect number. The number of defects generated in the uranium-molybdenum-niobium ternary alloy under irradiation at similar temperature conditions is approximately 25% that of uranium dioxide, with smaller void and interstitial cluster sizes. Under the impact of primary knock-on atoms with the same energy, the peak number of defects is about 50% of that in the uranium-molybdenum alloy, and the void cluster size is smaller. This indicates that the uranium-molybdenum-niobium ternary alloy has better radiation resistance than uranium-molybdenum alloys, uranium-niobium alloys, and other uranium alloys.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2025-03-27
摘要： We investigate the influence of quark anomalous magnetic moments (AMM) on the mass spectra of neutral pseudoscalar mesons ($\pi$, $K$, $\eta$, $\eta^{’}$) under external magnetic fields, finite temperatures, and quark chemical potentials using the three-flavor Nambu-Jona-Lasinio (NJL) model. By incorporating AMM at the quark level, we reveal that AMM significantly alters the magnetic field dependence of constituent quark masses, inducing first-order phase transitions for light quarks at critical fields, while strange quarks exhibit non-monotonic mass behavior. The inclusion of AMM reshapes the QCD phase diagram, suppressing chiral transition temperatures and shifting critical endpoints (CEP) toward lower $\mu$ and $T$. Notably, crossover transitions observed without AMM are replaced by first-order transitions under strong fields, aligning with lattice QCD predictions for IMC. For mesons, AMM triggers abrupt mass collapses and enhances flavor mixing, accelerating chiral restoration for $K$ and $\eta$ mesons via thresholds tied to strange quark masses. The $\eta^{’}$ meson, as a resonance state, shows suppressed mass growth and instability at strong fields, highlighting limitations in handling non-perturbative decay widths within the NJL framework. These findings underscore AMM critical role in reconciling effective model predictions with LQCD results, particularly in explaining IMC and phase transition dynamics.
分类： 物理学 >> 核物理学 提交时间： 2025-03-26
摘要： We systematically explore the interplay between time-dependent magnetic fields and energy density evolution in relativistic magnetohydrodynamics (RMHD), focusing on ultra-relativistic and magnetized conformal fluids. Three characteristic magnetic field evolution models (Type-1, Type-2, Type-3), parameterized to reflect temporal profiles observed in relativistic heavy-ion collisions, are integrated into a (1 + 1) D Bjorken-flow framework. For both fluid types, stronger magnetic fields universally suppress energy dissipation, with suppression magnitudes ordered as Type-1 $>$ Type-2 $>$ Type-3, driven by distinct decay rates of magnetic energy.To bridge QCD physics with macroscopic dynamics, we further incorporate a temperature-dependent magnetic susceptibility ($\chi_{m}(T)$) derived from lattice QCD, capturing the transition from diamagnetic hadronic matter ($\chi_{m} 0$). Our simulations reveal that $\chi_{m}(T)$ introduces a feedback loop: delayed energy dissipation sustains higher temperatures, reinforcing paramagnetic behavior and altering field evolution. These results quantify the critical role of magnetic field dynamics in regulating QGP thermalization and highlight the necessity of QCD-informed susceptibilities for realistic RMHD modeling.
分类： 天文学 >> 天文仪器与技术 提交时间： 2024-12-27 合作期刊: 《Astronomical Techniques and Instruments》
摘要： We present preliminary investigations of a potential optics system for wideband X-ray telescopes. The optical design adopts the conical approximation of the Wolter-I configuration and a combination of multilayer coatings and silicon pore optics. The total number of mirror modules is 79, distributed in 8 rows with the radii at the intersection plane between 250 mm and 500 mm. The optimization of the total effective area using the figure of merits method suggests that the focal length is 30 m and the mirror coating is a combination of the W/Si and Pt/C multilayers. This fulfills the on-axis effective area requirements of 2 000 cm2 at 10 keV and 300 cm2 at 60 keV and provides a broad energy response between 3 keV and 78.4 keV. With the current geometry and coating compositions, we implement a mass modeling of the telescope in Geant4 to predict mirror performances via the ray-tracing algorithm, including the angular resolution and effective area. With the presumed metrological data as input, this can provide precision and finishing requirements for the manufacture of optics. This work demonstrates the feasibility of combining multilayer coatings and silicon pore optics for potential use in wideband X-ray telescopes and advances the development and progress of such missions.
分类： 天文学 >> 天文仪器与技术 提交时间： 2024-12-27 合作期刊: 《Astronomical Techniques and Instruments》
Kai Huang
Yongzhang Yang
Rufeng Tang
Jin Cao
Marco Muccino
Luca Porcelli
Simone Dell'Agnello
Yuqiang Li
摘要： This paper provides a comprehensive overview of the development of Lunar Laser Ranging (LLR), covering key components such as ground observatories, lunar retro-reflectors, and data formats. The paper details the evolution of LLR experiments conducted by some major world-class observatories, with a particular focus on addressing critical issues associated with LLR technology. Additionally, the article highlights the latest advancements in the field, elucidating scientific achievements derived from LLR data, including its contributions to gravitational theory, Earth Orientation Parameters, lunar physics exploration, and lunar librations. The review summarizes new challenges in LLR modeling and concludes with prospects for the future development of LLR.
分类： 物理学 >> 核物理学 提交时间： 2023-06-20
S. Zhang
G. Li
W. Jiang
D.X. Wang
J. Ren
M. Huang
E.T. Li
J.Y. Tang
X.C. Ruan
H.W. Wang
Z.H. Li
Y.S. Chen
L.X. Liu,
X.X. Li
Q.W. Fan
R.R. Fan
X.R. Hu
J.C. Wang
X. Li
D.D. Niu
摘要： The stellar (n, ) cross section data for the mass numbers around A 160 are of key importance to nucleosynthesis in the main component of the slow neutron capture process, which occurs in the thermally pulsing asymptotic giant branch (TPAGB). The new measurement of (n, ) cross sections for 159Tb was performed using the C6D6 detector system at the back streaming white neutron beam line (Back-n) of the China spallation neutron source (CSNS) with neutron energies ranging from 1 eV to 1 MeV. Experimental resonance capture kernels are reported up to 1.2 keV neutron energy with this capture measurement. Maxwellian-averaged cross sections (MACS) are derived from the measured 159Tb (n, ) cross sections at kT = 5100 keV and are in good agreement with the recommended data of KADoNiS-v0.3 and JEFF-3.3, while KADoNiS-v1.0 and ENDF-VIII.0 signifificantly overestimate the present MACS up to 40% and 20%, respectively. A sensitive test of the s-process nucleosynthesis is also performed with the stellar evolution code MESA. Signifificant changes in abundances around A 160 are observed between the ENDF/B-VIII.0 and present measured rate of 159Tb(n, ) 160Tb in the MESA simulation.
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