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Physics package based on intracavity laser cooling ^(87)Rb atoms for space cold atom microwave clock

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Chinese Physics B 2024年第7期33卷 22-26页

作者：邓思敏达任伟项静峰赵剑波李琳张迪万金银孟艳玲蒋小军李唐刘亮吕德胜 Aerospace Laser Technology and System Department Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Mechanics Chinese Academy of SciencesShanghai 201800China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

This article proposes a new physics package to enhance the frequency stability of the space cold atom clock with the advantages of a microgravity environment. Clock working processes, including atom cooling, atomic state preparation,microwave interrogation, and transition probability detection, are integrated into the cylindrical microwave cavity to achieve a high-performance and compact physics package for the space cold atom clock. We present the detailed design and ground-test results of the cold atom clock physics package in this article, which demonstrates a frequency stability of 1.2×10^(-􀀀12) τ^(-1/2) with a Ramsey linewidth of 12.5 Hz, and a better performance is predicted with a 1 Hz or a narrower Ramsey linewidth in microgravity environment. The miniaturized cold atom clock based on intracavity cooling has great potential for achieving space high-precision time-frequency reference in the future.

关键词： atomic clock microgravity microwave cavity space station frequency stability

Ultrafast Carrier Dynamics in Ba_(6)Cr_(2)S_(10)Modified by Toroidal Magnetic Phase Transition

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Chinese Physics Letters 2024年第4期41卷 164-172页

作者：姜丽桐姜聪颖田义超赵惠张俊田珍耘付少华梁二军望贤成靳常青赵继民 Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Strong-Field and Ultrafast Photonics Lab Institute of Laser EngineeringBeijing University of TechnologyBeijing 100124China School of Physics&Laboratory of Zhongyuan Light Zhengzhou UniversityZhengzhou 450052China Songshan Lake Materials Laboratory Dongguan 523808China

Ba_(6)Cr_(2)S_(10)is a recently discovered magnetic material,in which the spins are aligned ferromagnetically in the ab-plane and anti-parallelly in a paired form along the *** is characterized as a quasi-one dimensional(1D)dimerized structure with a ferrotoroidic order,forming the simplest candidate toroidal magnetic(TM)order and exhibiting an anti-ferromagnetic-like transition at around 10 ***-resolved ultrafast dynamics investigation of the novel A-Cr-S(A:metal elements)family of quantum materials has rarely been ***,we investigate the time-resolved pump-probe ultrafast dynamics of a Ba6Cr2S10 single crystal.A prominent change in the photo-excited carrier dynamics is observed at T_(c)=10 K,corresponding to the reported TM-paramagnetic phase transition.A potential unknown magnetic transition is also found at T^(*)=29 *** results provide new evidence for the TM magnetic transition in Ba_(6)Cr_(2)S_(10),and shed light on phase transitions in TM quantum materials.

关键词： ferromagnetic magnetic transition

New insights into the effect of hard carbons microstructure on the diffusion of sodium ions into closed pores

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Chinese Chemical Letters 2024年第6期35卷 155-160页

作者： Mingxin Song Lijing Xie Fangyuan Su Zonglin Yi Quangui Guo Cheng-Meng Chen cas Key Laboratory of Carbon Materials Institute of Coal ChemistryChinese Academy of SciencesTaiyuan 030001China University of Chinese Academy of Sciences Beijing 100049China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Closed pores formed in hard carbons play an essential role in sodium storage at plateau ***,the effect of different structural features on the diffusion of sodium ions into closed pores remains ***,a precursor reconstruction strategy is conducted to regulate carbon microstructures including interlayer spacing,defect concentration,and closed pore volume by changing the ratio of aromatic and polysaccharide *** structure parts tend to develop disordered carbons with fewer defects,larger interlayer spacing,and smaller closed pore volume,while polysaccharide components prefer to form disordered carbons with more defects,smaller interlayer spacing,and larger closed pore *** the correlation analysis of microstructure features and the sodium storage capacity below 0.1 *** finds that the intercalation capacity is proportional to the ratio of pseudo-graphitic domains,whereas the pore filling capacity appeared at lower potential gradually decreases with the increasing defect concentration due to homo-ionic repulsion effect,without linear correlation with shortrange microcrystalline and closed pore *** optimized sample with suitable interlayer spacing and defect concentration exhibits a high plateau capacity of 241.7 m Ah/*** work provides insights into the exploitation of closed pore sodium storage performance.

关键词： Precursor reconstruction Hard carbons Structural features Closed pore filling Sodium-ion batteries

Feasibility study of the photonuclear reaction cross section of medical radioisotopes using a laser Compton scattering gamma source

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Nuclear Science and Techniques 2024年第9期35卷 168-177页

作者： Yu-Ning Gu Wei-Juan Zhao Xi-Guang Cao Yu-Xuan Yang Ting-Kai Ma Zheng-Li Liao Fei-Long Xu Yu-Gang Ma School of Physics and Microeletronics Zhengzhou UniversityZhengzhou 450001China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201210China Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China School of Nuclear Science and Technology University of South ChinaHengyang 421001China Key Laboratory of Nuclear Physics and Ion-beam Application(MOE) Institute of Modern PhysicsFudan UniversityShanghai 200433China Shanghai Research Center for Theoretical Nuclear Physics NSFC and Fudan UniversityShanghai 200438China

In recent years,the gap between the supply and demand of medical radioisotopes has increased,necessitating new methods for producing medical *** reactions based on gamma sources have unique advantages in terms of producing high specific activity and innovative medical ***,the lack of experimental data on reaction cross sections for photonuclear reactions of medical radioisotopes of interest has severely limited the development and production of photonuclear transmutation medical *** this study,the entire process of the generation,decay,and measurement of medical radioisotopes was simulated using online gamma activation and offline gamma measurements combined with a shielding gamma-ray *** on a quasi-monochromatic gamma beam from the Shanghai Laser Electron Gamma Source(SLEGS),the feasibility of this measurement of production cross section for surveyed medi-cal radioisotopes was simulated,and specific solutions for measuring medical radioisotopes with ultra-low production cross sections were *** feasibility of this method for high-precision measurements of the reaction cross section of medical radioisotopes was demonstrated.

关键词： Medical radioisotope Photonuclear reaction GEANT4 Shanghai Laser Electron Gamma Source(SLEGS) Low-background gamma-ray spectrometer

Effects of Hydrogen Charging Time and Pressure on the Hydrogen Embrittlement Susceptibility of X52 Pipeline Steel Material

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 293-307页

作者： Hong-Jiang Wan Xiao-Qi Wu Hong-Liang Ming Jian-Qiu Wang En-Hou Han School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China cas Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering Northeastern UniversityShenyang110819China Institute of Corrosion Science and Technology Guangzhou510530China

The effects of hydrogen charging time and pressure on the hydrogen embrittlement(HE)susceptibility of X52 pipeline steel material are studied by slow strain rate tensile *** fracture morphologies of the specimens are observed by scanning electron *** HE susceptibility of the X52 pipeline steel material increases with an increase in both hydrogen charging time and hydrogen *** a charging time of 96 h,the HE susceptibility index reaches 45.86%,approximately 3.6 times that at a charging time of 0 ***,a charging pressure of 4 MPa results in a HE susceptibility index of 31.61%,approximately 2.5 times higher than that at a charging pressure of 0.3 MPa.

关键词： Hydrogen embrittlement X52 pipeline steel material Tubular specimen Hydrogen charging time Hydrogen charging pressure

Room-temperature ferrimagnetism and size-modulated electronic structures in two-dimensional cluster-based metal-organic frameworks

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Science China Chemistry 2024年第4期67卷 1334-1340页

作者： Jing Cheng Xingxing Li Jinlong Yang Key Laboratory of Precision and Intelligent Chemistry University of Science and Technology of ChinaHefei 230026China Department of Chemical Physics University of Science and Technology of ChinaHefei 230026China Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China

Cluster-assembled materials have attracted particular attention for their complex hierarchical structures and unique ***,the majority of cluster-based assemblies developed so far are either non-magnetic or only exhibit magnetic ordering with a relatively low Curie temperature,limiting their applications in ***,two-dimensional(2D)cluster-assembled materials with room-temperature magnetism remain highly *** this purpose,based on first principles calculations,we design a series of thermodynamically stable 2D cluster-based metal-organic frameworks(MOFs)Fe_(n)-(pyz)(n=1-6)by utilizing Fenmetal clusters as nodes and nitrogen-containing pyrazine ligands as organic *** 2D cluster-based MOFs exhibit robust ferrimagnetic ordering due to the strong d-p direct exchange interaction between d-electron spin of Fe_(n)(n=1-6)clusters and charge transfer-induced p-electron spin of pyrazine *** particular,the ferrimagnetic Curie temperatures are well above room temperature(up to 836 K).Additionally,altering the size of Fe_(n)clusters in Fe_(n)-(pyz)(n=1-6)MOFs results in diverse functional spintronic properties,including bipolar magnetic semiconductors,half semiconductors and Dirac half ***,these 2D assembled MOFs possess sizable magnetic anisotropy energies,up to 9.16 me V per formula.

关键词： metal-organic framework two-dimensional material half metal bipolar magnetic semiconductor magnet

Simulation study of the performance of the Very Large Area gamma-ray Space Telescope

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Nuclear Science and Techniques 2024年第9期35卷 1-17页

作者： Xu Pan Wei Jiang Chuan Yue Shi-Jun Lei Yu-Xin Cui Qiang Yuan Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China

The Very Large Area gamma-ray Space Telescope(VLAST)is a mission concept proposed to detect gamma-ray photons through both Compton scattering and electron–positron pair production mechanisms,thus enabling the detection of photons with energies ranging from MeV to *** project aims to conduct a comprehensive survey of the gamma-ray sky from a low-Earth orbit using an anti-coincidence detector,a tracker detector that also serves as a low-energy calorimeter,and a high-energy imaging *** developed a Monte Carlo simulation application of the detector using the GEANT4 toolkit to evaluate the instrument performance,including the effective area,angular resolution,and energy resolution,and explored specific optimizations of the detector *** simulation-based analysis indicates that the current design of the VLAST is physically feasible,with an acceptance above 10 m^(2)sr which is four times larger than that of the Fermi-LAT,an energy resolution better than 2%at 10 GeV,and an angular resolution better than 0.2◦at 10 *** VLAST project promises to make significant contributions to the field of gamma-ray astronomy and enhance our understanding of the cosmos.

关键词： Space astronomy Gamma-ray telescope Calorimeter Monte Carlo simulation

Riverine sulfate sources and behaviors in arid environment,Northwest China:Constraints from sulfur and oxygen isotopes

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Journal of Environmental Sciences 2024年第3期137卷 716-731页

作者： Yifu Xu Wenjing Liu Bing Xu Zhifang Xu Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

The fate of riverine sulfate ion (SO_(4)^(2-)) and its environmental effects in arid environment are difficult to evaluate due to its complicated sources and strongly coupled behaviors with water cycle which is significantly modified by *** understand the sulfur cycle in aquatic systems in arid environment,the chemical and sulfur and oxygen isotopic compositions (δ^(34)S_(SO4)and δ^(18)O_(SO4)) of major rivers around the Badain Jaran Desert,northwestern China,were *** rivers had averaged SO_(4)^(2-)content at 1336μmol/L,over 10times higher than the global *** δ^(34)S_(SO4)and δ^(18)O_(SO4)values ranged from-5.3‰to+11.8‰and+1.6‰to+12.8‰,*** end-member analysis and the inverse model showed that riverine sulfate was mainly derived from evaporites dissolution (0-87%),sulfide oxidation (13%-100%) and precipitation (0-33%),indicating heterogeneity in sulfur sources and behaviors along the river drainage with the lithology variations and climate *** isotopic tools combining with hydro-chemistry compositions could be applied to reveal sulfur cycle in arid *** on the calculation,sulfide oxidation plays the primary role in the headwater and upstream in the Qilian-Mountains area,where sulfide is widely *** the proportion of evaporites dissolution contributing to riverine sulfate is much higher in downstream in a drier ***,less precipitation and higher temperature can lead to more intensive evaporation,affecting the process of sulfide oxidation and enhancing the rates of evaporites dissolution and sulfate precipitation in the basin.

关键词： Sulfur and oxygen isotopes Source apportionment Inverse model Arid environment Inland rivers Northwestern China

A synthetic diagnostics platform for microwave imaging diagnostics in tokamaks

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Plasma Science and Technology 2024年第3期26卷 38-45页

作者：李子涵杨尚川徐新航张立夫渠承明李诚普庄革谢锦林 Department of Plasma Physics and Fusion Engineering University of Science and Technology of ChinaHefei 230026People's Republic of China

Interpreting experimental diagnostics data in tokamaks,while considering non-ideal effects,is challenging due to the complexity of *** address this challenge,a general synthetic diagnostics(GSD)platform has been established that facilitates microwave imaging reflectometry and electron cyclotron emission *** platform utilizes plasma profiles as input and incorporates the finite-difference time domain,ray tracing and the radiative transfer equation to calculate the propagation of plasma spontaneous radiation and the external electromagnetic field in *** tests for classical cases have been conducted to verify the accuracy of every core module in the GSD ***,2D imaging of a typical electron temperature distribution is reproduced by this platform and the results are consistent with the given real experimental *** platform also has the potential to be extended to 3D electromagnetic field simulations and other microwave diagnostics such as cross-polarization scattering.

关键词： synthetic diagnostics tokamak plasmas microwave imaging diagnostics microwave imaging reflectometer electron cyclotron emission imaging