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Fast X-ray imaging beamline at SSRF

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NUCLEAR SCIENCE AND TECHNIQUES 2024年第9期35卷 1-14页

作者： Li, Ke Xie, Hong-Lan Fu, Ya-Nan Wang, Fei-Xiang Du, Guo-Hao Ji, Jian-Feng Deng, Biao Xiao, Ti-Qiao Chinese Acad Sci Shanghai Adv Res Inst Shanghai Synchrotron Radiat Facil Shanghai 201204 Peoples R China

The fast X-ray imaging beamline (BL16U2) at Shanghai Synchrotron Radiation Facility (SSRF) is a new beamline that provides X-ray micro-imaging capabilities across a wide range of time scales, spanning from 100 ps to mu s and ms. This beamline has been specifically designed to facilitate the investigation of a wide range of rapid phenomena, such as the deformation and failure of materials subjected to intense dynamic loads. In addition, it enables the study of high-pressure and high-speed fuel spray processes in automotive engines. The light source of this beamline is a cryogenic permanent magnet undulator (CPMU) that is cooled by liquid nitrogen. This CPMU can generate X-ray photons within an energy range of 8.7-30 keV. The beamline offers two modes of operation: monochromatic beam mode with a liquid nitrogen-cooled double-crystal monochromator (DCM) and pink beam mode with the first crystal of the DCM out of the beam path. Four X-ray imaging methods were implemented in BL16U2: single-pulse ultrafast X-ray imaging, microsecond-resolved X-ray dynamic imaging, millisecond-resolved X-ray dynamic micro-CT, and high-resolution quantitative micro-CT. Furthermore, BL16U2 is equipped with various in situ impact loading systems, such as a split Hopkinson bar system, light gas gun, and fuel spray chamber. Following the completion of the final commissioning in 2021 and subsequent trial operations in 2022, the beamline has been officially available to users from 2023.

关键词： Multiple time-scale X ray imaging Single-pulse X ray imaging Dynamic 2D imaging Dynamic micro-CT

Arabidopsis photoperiodic regulator CONSTANS feeds back to control the circadian clock

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MOLECULAR PLANT 2024年第9期17卷 1338-1340页

作者： San Martin, Abril Yanovsky, Marcelo Javier Fdn inst Leloir CONICET Inst Invest Bioquim Buenos Aires Ave Patricias Argentinas 435 RA-C1405BWE Buenos Aires Argentina

Human beings live in a world defined by daily cycles of light and darkness caused by the Earth's rotation around its ***,like most living organisms,have evolved internal circadian clocks that time biological processes in anticipation of these daily environmental changes(Young and Kay,2001).The plant clock relies on core genes encoding transcription factors(TFs),which regulate each other's expression through intricate networks of interlocking transcriptional-translational feedback loops(Nohales and Kay,2016).These loops ultimately control the expression of thousands of genes,allowing plants to adapt to daily fluctuations in light,temperature,and humidity(Covington et al.,2008).In addition to daily rhythms,the Earth experiences yearly seasonal cycles marked by longer,warmer days in spring and summer,followed by shorter,cooler days in autumn and *** changes in day length and temperature intensify with distance from the ***,the ability of plants to adjust their growth and development in anticipation of seasonal changes determines their latitudinal distribution(McMillan,1960).

关键词： CORE

A seven-crystal spectrometer for high-energy resolution X-ray spectroscopy at Shanghai Synchrotron Radiation Facility

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NUCLEAR SCIENCE AND TECHNIQUES 2024年第9期35卷 1-10页

作者： Mei, Bing-Bao Wang, Liang-Xin Gu, Song-Qi Su, Xiao-Zhi Zhang, Shuo Wei, Yao Ma, Jing-Yuan Jiang, Zheng Song, Fei Chinese Acad Sci Shanghai Adv Res Inst Shanghai Synchrotron Radiat Facil Shanghai 201800 Peoples R China Chinese Acad Sci Shanghai Inst Appl Phys Shanghai 201204 Peoples R China Univ Sci & Technol China Natl Synchrotron Radiat Lab Hefei 230026 Peoples R China

A Johann-type X-ray spectrometer was successfully developed at the hard X-ray branch (in-vacuum undulator with a 24-mm periodic length) of the energy material beamline (E-line) at the Shanghai Synchrotron Radiation Facility (SSRF). This spectrometer was utilized to implement X-ray emission spectroscopy (XES), high-energy resolution fluorescence-detected X-ray absorption spectroscopy (HERFD-XAS), and resonant inelastic X-ray scattering. Seven spherically bent crystals were positioned on the respective vertical 500-mm-diameter Rowland circles, adopting an area detector to increase the solid angle to 1.75%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\%$$\end{document} of 4 pi\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\pi$$\end{document} sr, facilitating the study of low-concentrate systems under complex reaction conditions. Operated under the atmosphere pressure, the spectrometer covers the energy region from 3.5 to 18 keV, with the Bragg angle ranging from 73 degrees\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\circ }$$\end{document} to 86 degrees\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\circ }$$\end{document} during vertical scanning. It offers a promised energy resolution of sub-eV (XES) and super-eV (HERFD-XAS). Generally, th

关键词： X-ray emission spectroscopy High-energy-resolution X-ray spectrometer Johann geometry Energy materials SSRF HETEROGENEOUS CATALYSIS EMISSION SPECTROSCOPY STRUCTURAL EVOLUTION PHTHALOCYANINE BEAMLINE XANES XAFS MN FE

Design and high-power testing of offline conditioning cavity for CiADS RFQ high-power coupler

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NUCLEAR SCIENCE AND TECHNIQUES 2024年第9期35卷 1-10页

作者： Wang, Ruo-Xu He, Yuan Shi, Long-Bo Li, Chen-Xing Xue, Zong-Heng Jiang, Tian-Cai Xu, Xian-Bo Sun, Lie-Peng Zhang, Zhou-Li Chinese Acad Sci Inst Modern Phys Lanzhou 730000 Peoples R China Lanzhou Univ Lanzhou 730000 Peoples R China

To validate the design rationality of the power coupler for the RFQ cavity and minimize cavity contamination, we designed a low-loss offline conditioning cavity and conducted high-power testing. This offline cavity features two coupling ports and two tuners, operating at a frequency of 162.5MHz\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${162.5}\,\textrm{MHz}$$\end{document} with a tuning range of 3.2MHz\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${3.2}\,\textrm{MHz}$$\end{document}. Adjusting the installation angle of the coupling ring and the insertion depth of the tuner helps minimize cavity losses. We performed electromagnetic structural and multiphysics simulations, revealing a minimal theoretical power loss of 4.3%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${4.3}\,{\%}$$\end{document}. However, when the cavity frequency varied by 110kHz\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${110}\,\textrm{kHz}$$\end{document}, theoretical power losses increased to 10%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${10}\,{\%}$$\end{document}, necessitating constant t

关键词： RFQ cavity Power coupler Offline conditioning Resonant cavity PHYSICS DESIGN

The dynamics beamline at SSRF

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NUCLEAR SCIENCE AND TECHNIQUES 2024年第9期35卷 1-12页

作者： Liu, Zhen Wang, Li-Hua Jiang, Yong Tong, Ya-Jun Zhu, Hua-Chun Ji, Te Chen, Min Jiang, Zheng Wei, Xiang-Jun Chinese Acad Sci Shanghai Adv Res Inst Shanghai 201204 Peoples R China ShanghaiTech Univ Shanghai 201210 Peoples R China

The dynamics beamline (D-Line), which combines synchrotron radiation infrared spectroscopy (SR-IR) and energy-dispersive X-ray absorption spectroscopy (ED-XAS), is the first beamline in the world to realize concurrent ED-XAS and SR-IR measurements at the same sample position on a millisecond time-resolved scale. This combined technique is effective for investigating rapid structural changes in atoms, electrons, and molecules in complicated disorder systems, such as those used in physics, chemistry, materials science, and extreme conditions. Moreover, ED-XAS and SR-IR can be used independently in the two branches of the D-Line. The ED-XAS branch is the first ED-XAS beamline in China, which uses a tapered undulator light source and can achieve approximately 2.5 x 1012 photons/s300 eV BW@7.2 keV at the sample position. An exchangeable polychromator operating in the Bragg-reflection or Laue-transmission configuration is used in different energy ranges to satisfy the requirements for beam size and energy resolution. The focused beam size is approximately 3.5 mu m (H) x 21.5 mu m (V), and the X-ray energy range is 5-25 keV. Using one- and two-dimensional position-sensitive detectors with frame rates of up to 400 kHz enables time resolutions of tens of microseconds to be realized. Several distinctive techniques, such as the concurrent measurement of in situ ED-XAS and infrared spectroscopy, time-resolved ED-XAS, high-pressure ED-XAS, XMCD, and pump-probe ED-XAS, can be applied to achieve different scientific goals.

关键词： ED-XAS SR-IR Time-resolved D-line SSRF SYNCHROTRON-RADIATION DISPERSIVE MODE SPECTROSCOPY PRESSURE EXAFS SPECTROMETER DICHROISM DETECTOR XAFS IR

Highly coupled off-resonance lattice design in diffraction-limited light sources

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NUCLEAR SCIENCE AND TECHNIQUES 2024年第9期35卷 1-11页

作者： Gong, Yi-Hao Tian, Shun-Qiang Liu, Xin-Zhong Xuan, Shou-Zhi Tan, Li-Yuan Mao, Ling-Long Chinese Acad Sci Shanghai Shanghai Adv Res Inst Shanghai Synchrotron Radiat Facil Shanghai 201204 Peoples R China Chinese Acad Sci Shanghai Shanghai Inst Appl Phys Shanghai 201800 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

The round-beam operation presents many benefits for scientific experiments regarding synchrotron radiation and the weakening influences of intra-beam scattering in diffraction-limited synchrotron light sources. A round-beam generation method based on the global setting of skew quadrupoles and the application of a non-dominated sorting genetic algorithm was proposed in this study. Two schemes, including large-emittance coupling introduced via betatron coupling and vertical dispersion, were explored in a candidate lattice for an upgrade-proposal of the Shanghai synchrotron radiation facility. Emittance variations with lattice imperfections and their influence on the beam dynamics of beam optic distortions were investigated. The results demonstrated that a precise coupling control ranging from 10 to 100% was achieved under low optical distortion, whereas full-coupling generation and its robustness were achieved by our proposed method by adjusting the skew quadrupole components located in the dispersion-free sections. The Touschek lifetime increased by a factor of 2-2.5.

关键词： Diffraction-limited storage ring (DLSR) Shanghai synchrotron radiation facility upgrade (SSRF-U) Round beam Off-resonance coupling EMITTANCE OPTICS

A real-time calibration method based on time-to-digital converter for accelerator timing system

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NUCLEAR SCIENCE AND TECHNIQUES 2024年第9期35卷 1-14页

作者： Duan, Qi-Hao Ge, Liang Jia, Yan-Hao Zhu, Jie-Yu Zhang, Wei Chinese Acad Sci Inst modern Phys Lanzhou 730000 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

The high-intensity heavy-ion accelerator facility (HIAF) is a scientific research facility complex composed of multiple cascade accelerators of different types, which pose a scheduling problem for devices distributed over a certain range of 2 km, involving over a hundred devices. The white rabbit, a technology-enhancing Gigabit Ethernet, has shown the capability of scheduling distributed timing devices but still faces the challenge of obtaining real-time synchronization calibration parameters with high precision. This study presents a calibration system based on a time-to-digital converter implemented on an ARM-based System-on-Chip (SoC). The system consists of four multi-sample delay lines, a bubble-proof encoder, an edge controller for managing data from different channels, and a highly effective calibration module that benefits from the SoC architecture. The performance was evaluated with an average RMS precision of 5.51 ps by measuring the time intervals from 0 to 24,000 ps with 120,000 data for every test. The design presented in this study refines the calibration precision of the HIAF timing system. This eliminates the errors caused by manual calibration without efficiency loss and provides data support for fault diagnosis. It can also be easily tailored or ported to other devices for specific applications and provides more space for developing timing systems for particle accelerators, such as white rabbits on HIAF.

关键词： HIAF White rabbit Calibration system Time-to-digital converter (TDC) FPGA

Changes of growth-climate relationships of Smith fir forests along an altitudinal gradient

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JOURNAL OF FORESTRY RESEARCH 2024年第1期35卷 1-10页

作者： Zheng, Jiacheng Yang, Jing Jia, Hengfeng Lyu, Lixin Langzhen, Jiayang Zhang, Qi-Bin Chinese Acad Sci Inst Bot State Key Lab Vegetat & Environm Change Beijing 100093 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Linzhou Bur Meteorol Lhasa 851611 Tibet Peoples R China Tibet Agr & Anim Husb Univ Inst Plateau Ecol Linzhi 860000 Tibet Peoples R China

Temporal changes in the relationship between tree growth and climate have been observed in numerous forests across the world. The patterns and the possible regulators (e.g., forest community structure) of such changes are, however, not well understood. A vegetation survey and analyses of growth-climate relationships for Abies georgei var. Smithii (Smith fir) forests were carried along an altitudinal gradient from 3600 to 4200 m on Meili Snow Mountain, southeastern Tibetan Plateau. The results showed that the associations between growth and temperature have declined since the 1970s over the whole transect, while response to standardized precipitation-evapotranspiration indices (SPEI) strengthened in the mid- and lower-transect. Comparison between growth and vegetation data showed that tree growth was more sensitive to drought in stands with higher species richness and greater shrub cover. Drought stress on growth may be increased by heavy competition from shrub and herb layers. These results show the non-stationary nature of tree growth-climate associations and the linkage to forest community structures. Vegetation components should be considered in future modeling and forecasting of forest dynamics in relation to climate changes.

关键词： Climate change Tree rings Altitudinal gradient Community structure Plant diversity FAGUS-SYLVATICA L. TREE-GROWTH TIBETAN PLATEAU WHITE SPRUCE TEMPERATURE ELEVATION PRECIPITATION DIVERGENCE ECOSYSTEMS DIVERSITY

Natural forests exhibit higher organic carbon concentrations and recalcitrant carbon proportions in soil than plantations: a global data synthesis

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JOURNAL OF FORESTRY RESEARCH 2024年第1期35卷 1-11页

作者： Nie, Xiuqing Wang, Hui Wang, Jian Liu, Shirong Chinese Acad Forestry Ecol & Nat Conservat Inst Key Lab Forest Ecol & Environm Natl Forestry & Gra 2 Dongxiaofu Beijing 100091 Peoples R China

Different chemical compositions of soil organic carbon (SOC) affect its persistence and whether it significantly differs between natural forests and plantations remains unclear. By synthesizing 234 observations of SOC chemical compositions, we evaluated global patterns of concentration, individual chemical composition (alkyl C, O-alkyl C, aromatic C, and carbonyl C), and their distribution evenness. Our results indicate a notably higher SOC, a markedly larger proportion of recalcitrant alkyl C, and lower easily decomposed carbonyl C proportion in natural forests. However, SOC chemical compositions were appreciably more evenly distributed in plantations. Based on the assumed conceptual index of SOC chemical composition evenness, we deduced that, compared to natural forests, plantations may have higher possible resistance to SOC decomposition under disturbances. In tropical regions, SOC levels, recalcitrant SOC chemical composition, and their distributed evenness were significantly higher in natural forests, indicating that SOC has higher chemical stability and possible resistance to decomposition. Climate factors had minor effects on alkyl C in forests globally, while they notably affected SOC chemical composition in tropical forests. This could contribute to the differences in chemical compositions and their distributed evenness between plantations and natural stands.

关键词： Global data synthesis Natural forest Plantations Soil organic carbon Soil organic carbon chemical composition STATE C-13 NMR SPATIAL-DISTRIBUTION MICROBIAL COMMUNITY MATTER FRACTIONS QUALITY SEQUESTRATION STABILIZATION DECOMPOSITION DIVERSITY