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Minimum emittance in TBA and MBA lattices

Chinese physics C 2015年第3期39卷 77-82页

作者：徐刚彭月梅 Key Laboratory of Particle Acceleration Physics and Technology Institute of High Energy PhysicsChinese Academy of Sciences

For reaching a small emittance in a modern light source, triple bend achromats （TBA）, theoretical minimum emittance （TME） and even multiple bend achromats （MBA） have been considered. This paper derived the necessary condition for achieving minimum emittance in TBA and MBA theoretically, where the bending angle of inner dipoles has a factor of 31/3 bigger than that of the outer dipoles. Here, we also calculated the conditions attaining the minimum emittance of TBA related to phase advance in some special cases with a pure mathematics method. These results may give some directions on lattice design.

关键词： minimum emittance dipole achromats light source

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Exploring New physics with PandaX-4T Low Energy Electronic Recoil Data

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Physical Review Letters 2025年第4期134卷 041001-041001页

作者： Xinning Zeng Zihao Bo Wei Chen Xun Chen Yunhua Chen Zhaokan Cheng Xiangyi Cui Yingjie Fan Deqing Fang School of Physics and Astronomy Shanghai Jiao Tong University Key Laboratory for Particle Astrophysics and Cosmology (MoE) Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai 200240 China New Cornerstone Science Laboratory Tsung-Dao Lee Institute Shanghai Jiao Tong University Shanghai 201210 China Shanghai Jiao Tong University Sichuan Research Institute Chengdu 610213 China Jinping Deep Underground Frontier Science and Dark Matter Key Laboratory of Sichuan Province Yalong River Hydropower Development Company Ltd. 288 Shuanglin Road Chengdu 610051 China Sino-French Institute of Nuclear Engineering and Technology Sun Yat-Sen University Zhuhai 519082 China Department of Physics Yantai University Yantai 264005 China Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) Institute of Modern Physics Fudan University Shanghai 200433 China

New particles beyond the standard model of particle physics, such as axions, can be effectively searched through their interactions with electrons. We use the large liquid xenon detector PandaX-4T to search for novel electronic recoil signals induced by solar axions, neutrinos with anomalous magnetic moment, axionlike particles, dark photons, and light fermionic dark matter. A detailed background model is established using the latest datasets with 1.54 ton yr exposure. No significant excess above the background has been observed, and we have obtained competitive constraints for axion couplings, neutrino magnetic moment, and fermionic dark matter interactions.

关键词： Magnetic moments

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Pressure-induced structure change and anomalies in thermodynamic quantities and transport properties in liquid lithium hydride

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Physical Review B 2025年第2期111卷 024102-024102页

作者： Xiao Z. Yan Yang M. Chen Hua Y. Geng Yi F. Wang Yi Sun Lei L. Zhang Hao Wang Yin L. Xu National Key Laboratory of Shock Wave and Detonation Physics Institute of Fluid Physics CAEP P.O. Box 919-102 Mianyang 621900 Sichuan People's Republic of China School of Science Jiangxi University of Science and Technology Ganzhou 341000 Jiangxi People's Republic of China Jiangxi Provincial Key Laboratory of Particle Technology Ganzhou 341000 Jiangxi People's Republic of China HEDPS Center for Applied Physics and Technology and College of Engineering Peking University Beijing 100871 People's Republic of China

Understanding the nature of liquid structure and its evolution under different conditions is a major challenge in condensed-matter physics and materials science. Here, we report a pressure-induced structure change spanning a wide pressure range in liquid-state lithium hydride (LiH) by first-principles molecular dynamic simulations. This behavior can be described as a continuous crossover from low pressure liquid with Li+−H− duality symmetry to a high pressure one with broken duality symmetry. The thermodynamic quantities such as heat capacity and ionic transport properties such as diffusivity are also saliently impacted. It is important to stress that such behavior is first predicted for this category of materials, which is ubiquitous in the universe as well as in industry applications. Last, a comprehensive high-pressure high-temperature phase diagram of LiH is constructed, which embodies rich physics in this previously thought simple ionic compound.

关键词： Specific heat

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Atmospheric Antideuteron Flux Within a Dynamical Coalescence Approach

arXiv

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arXiv 2025年

作者： Pu, Jie Li, Xin Sun, Kai-Jia Ma, Chun-Wang Chen, Lie-Wen College of Physics Henan Normal University Xinxiang453007 China Institute of Nuclear Science and Technology Henan Academy of Science Zhengzhou450046 China Shanghai Research Center for Theoretical Nuclear Physics NSFC and Fudan University Shanghai200438 China School of Physics and Astronomy Shanghai Key Laboratory for Particle Physics and Cosmology Key Laboratory for Particle Astrophysics and Cosmology MOE Shanghai Jiao Tong University Shanghai200240 China Key Laboratory of Nuclear Physics and Ion-Beam Application MOE Institute of Modern Physics Fudan University Shanghai200433 China

Cosmic antideuterons are considered as one of the most promising tools for the indirect detection of dark matter due to their ultra-low astrophysical backgrounds. Currently only upper limits on the antideuteron flux exist, but advancements in experimental detection technology may soon lead to positive signals. A major source of background is the production of secondary antideuterons through collisions of cosmic rays with the surrounding medium. In this study, antideuteron production is modeled using a multiphase transport model (AMPT) coupled with a dynamical coalescence model. By applying a widely used leaky box model and incorporating specific processes, we present a new theoretical baseline for atmospheric secondary antideuteron flux, including a tertiary contribution, from primary cosmic rays interacting with Earth’s atmosphere. Our results indicate that the atmospheric antideuteron flux are within the range of various existing calculations and remain well below the upper limits set by the Balloon-borne Experiment with a Superconducting Spectrometer (BESS). The atomospheric antideuteron is found to dominate the antideuteron background at kinetic energies below 0.26 GeV/n. © 2025, CC BY.

关键词： Kinetic energy

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Generating a uniform transverse distributed electron beam along a beam line

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Chinese physics C 2015年第11期39卷 87-90页

作者：焦毅崔小昊 Key Laboratory of Particle Acceleration Physics and Technology Institute of High Energy PhysicsChinese Academy of Sciences

It has been reported that transverse distribution shaping can help to further enhance the energy extraction efficiency in a terawatt, tapered X-ray free-electron laser. Thus, methods of creating and keeping an almost uniform transverse distributed（UTD） beam within undulators are required. This study shows that a UTD electron beam can be generated within evenly distributed drift sections where undulators can be placed, by means of octupoles and particular optics. A specific design is presented, and numerical simulations are performed to verify the proposed method.

关键词： uniform transverse distributed beam octupoles particular optics

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AlMn-Al dual TES bolometer development for CMB telescopes

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Experimental Astronomy 2025年第3期59卷 1-15页

作者： Sun, Jiamin Zhu, Lin Chai, Ye Gao, He Liu, Zhouhui Shu, Shibo Li, Yaqiong Zhang, Yifei Li, Zhengwei Gu, Yudong Jiang, Mengqi Xiu, Qinglei Sun, Zhijia Yan, Daikang Liu, Congzhan Particle Physics Research Center Shandong Institute of Advanced Technology Jinan 250100 China Key Laboratory of Particle Astrophysics Institute of High Energy Physics CAS Beijing 100049 China School of Physics and Optoelectronics Xiangtan University Xiangtan 411105 China School of Physical Science University of Chinese Academy of Sciences Beijing 100049 China Spallation Neutron Source Science Center Institute of High Energy Physics CAS Dongguan 523803 China

Transition-edge sensor (TES) as a type of low-temperature superconducting bolometers offers excellent signal-to-noise-ratio, and is one of the most up-to-date technologies used for cosmic microwave background (CMB) observations. The Ali CMB polarization telescope (AliCPT) project in China uses TES bolometers as the focal plane detector through an international collaborative effort. To increase collecting efficiency of the telescope, and include bolometers of different frequency bands, large-scale production of TES bolometer arrays needs to be accomplished in the future. In this work, we developed single pixel TES bolometers, the saturation power and noise equivalent power (NEP) of which satisfy the requirements of 90 GHz and 150 GHz CMB applications. Each of the bolometers consist of a 1200 ppm AlMn alloy TES for CMB science observation and an Al TES for laboratory optical tests. Dark characterization is applied on these bolometers. Their heat capacities are in the range of 0.7∼1.6 pJ/K and the NEP values are below 30 aW/Hz. The Tc values are about 360 mK and can be adjusted to about 410 mK by additional annealing. © The Author(s), under exclusive licence to Springer Nature B.V. 2025.

关键词： Bolometer Cosmic microwave background Superconducting device Transition-edge sensor

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Ripples of the QCD critical point

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Physical Review D 2025年第3期111卷 L031502-L031502页

作者： Wei-jie Fu Xiaofeng Luo Jan M. Pawlowski Fabian Rennecke Shi Yin School of Physics Dalian University of Technology Dalian 116024 People’s Republic of China Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics Central China Normal University Wuhan 430079 People’s Republic of China Institut für Theoretische Physik Universität Heidelberg Philosophenweg 16 69120 Heidelberg Germany ExtreMe Matter Institute EMMI GSI Planckstraße 1 D-64291 Darmstadt Germany Institut für Theoretische Physik Justus-Liebig-Universität Gießen 35392 Gießen Germany Helmholtz Research Academy Hesse for FAIR Campus Gießen 35392 Gießen Germany

We investigate the impact of a critical end point (CEP) on the experimentally accessible baryon-number fluctuations of different orders. By now, its potential location has been constrained fairly accurately within first principles functional QCD, together with the location of the chiral crossover line and further thermodynamic observables. This information is incorporated in an advanced QCD-assisted low-energy effective theory which is used for the computation of baryon-number fluctuations at the chemical freeze-out. This computation also takes care of global baryon-number conservation at larger density, where the system changes from grand-canonical to canonical statistics. We observe a prominent peak structure, whose amplitude depends on the location of the CEP, while its position is more sensitive to the location of the freeze-out curve. Our results provide guidance for future low-energy heavy-ion experiments.

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Search for Solar Boosted Dark Matter particles at the PandaX-4T Experiment

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Physical Review Letters 2025年第16期134卷 161003-161003页

作者： Guofang Shen Zihao Bo Wei Chen Xun Chen Yunhua Chen Zhaokan Cheng Xiangyi Cui Yingjie Fan Deqing Fang Zhixing Gao Lisheng Geng Karl Giboni Xunan Guo Xuyuan Guo Zichao Guo Chencheng Han Ke Han Changda He Jinrong He Di Huang Houqi Huang Junting Huang Ruquan Hou Yu Hou Xiangdong Ji Xiangpan Ji Yonglin Ju Chenxiang Li Jiafu Li Mingchuan Li Shuaijie Li Tao Li Zhiyuan Li Qing Lin Jianglai Liu Congcong Lu Xiaoying Lu Lingyin Luo Yunyang Luo Wenbo Ma Yugang Ma Yajun Mao Yue Meng Xuyang Ning Binyu Pang Ningchun Qi Zhicheng Qian Xiangxiang Ren Dong Shan Xiaofeng Shang Xiyuan Shao Manbin Shen Wenliang Sun Yi Tao Anqing Wang Guanbo Wang Hao Wang Jiamin Wang Lei Wang Meng Wang Qiuhong Wang Shaobo Wang Siguang Wang Wei Wang Xiuli Wang Xu Wang Zhou Wang Yuehuan Wei Weihao Wu Yuan Wu Mengjiao Xiao Xiang Xiao Kaizhi Xiong Yifan Xu Shunyu Yao Binbin Yan Xiyu Yan Yong Yang Peihua Ye Chunxu Yu Ying Yuan Zhe Yuan Youhui Yun Xinning Zeng Minzhen Zhang Peng Zhang Shibo Zhang Shu Zhang Tao Zhang Wei Zhang Yang Zhang Yingxin Zhang Yuanyuan Zhang Li Zhao Jifang Zhou Jiaxu Zhou Jiayi Zhou Ning Zhou Xiaopeng Zhou Yubo Zhou Zhizhen Zhou Haipeng An Haoming Nie School of Physics Beihang University Beijing 102206 China School of Physics and Astronomy Shanghai Jiao Tong University Key Laboratory for Particle Astrophysics and Cosmology (MoE) Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai 200240 China New Cornerstone Science Laboratory Tsung-Dao Lee Institute Shanghai Jiao Tong University Shanghai 201210 China Shanghai Jiao Tong University Sichuan Research Institute Chengdu 610213 China Jinping Deep Underground Frontier Science and Dark Matter Key Laboratory of Sichuan Province China Yalong River Hydropower Development Company Ltd. 288 Shuanglin Road Chengdu 610051 China Sino-French Institute of Nuclear Engineering and Technology Sun Yat-Sen University Zhuhai 519082 China Department of Physics Yantai University Yantai 264005 China Key Laboratory of Nuclear Physics and Ion-beam Application (MoE) Institute of Modern Physics Fudan University Shanghai 200433 China Peng Huanwu Collaborative Center for Research and Education Beihang University Beijing 100191 China International Research Center for Nuclei and Particles in the Cosmos and Beijing Key Laboratory of Advanced Nuclear Materials and Physics Beihang University Beijing 100191 China Southern Center for Nuclear-Science Theory (SCNT) Institute of Modern Physics Chinese Academy of Sciences Huizhou 516000 China SJTU Paris Elite Institute of Technology Shanghai Jiao Tong University Shanghai 200240 China School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China Department of Physics University of Maryland College Park Maryland 20742 USA School of Physics Nankai University Tianjin 300071 China School of Physics Sun Yat-Sen University Guangzhou 510275 China State Key Laboratory of Particle Detection and Electronics University of Science and Technology of China Hefei 230026 China Department of Modern Physics University of Science and Technology of China Hefei 230026 China Research Center for Particle Science and Technology

We present a novel constraint on light dark matter utilizing 1.54 metric ton/year of data acquired from the PandaX-4T dual-phase xenon time projection chamber. This constraint is derived through detecting electronic recoil signals resulting from the interaction with solar-enhanced dark matter flux. Low-mass dark matter particles, lighter than a few MeV/c2, can scatter with the thermal electrons in the Sun. Consequently, with higher kinetic energy, the boosted dark matter component becomes detectable via contact scattering with xenon electrons, resulting in a few keV energy deposition that exceeds the threshold of PandaX-4T. We calculate the expected recoil energy in PandaX-4T considering the Sun’s acceleration with heavy mediators and the detection capabilities of the xenon detector. The first experimental search results using the xenon detector yield the most stringent upper limits cross section of 3.51×10−39 cm2 at 0.08 MeV/c2 for a solar boosted dark matter mass ranging from 0.02 to 10 MeV/c2, achieving a 23-fold improvement compared with earlier experimental studies.

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Preliminary study on detection and cleaning of parasitic bunches

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Nuclear Science and Techniques 2021年第10期32卷 1-11页

作者： Jun He Yan-Feng Sui Yan-Hua Lu Di Yin Zhe Duan Sai-Ke Tian De-Chong Zhu Ying Zhao Jun-Hui Yue Jian-She Cao Key Laboratory of Particle Acceleration Physics and Technology Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China

To establish a nuclear resonant scattering beamline at the High Energy Photon Source(HEPS),it is essential to develop tools for detection and cleaning of parasitic bunches,for meeting the stringent demands on bunch *** this end,a novel time-correlated single-photon counting system was implemented at the electron storage ring of the Beijing Electron–Positron Collider II(BEPCII).The purity deterioration process over a week-long operation was recorded by the *** this study,the mechanism of impurity growth was analyzed by numerical methods and validated on *** agreement between the experimental results and the cal-culation was fairly *** main sources of parasitic bunches,pre-accelerators and the Touschek scattering were confirmed.A bunch-cleaning technique,based on a sinu-soidal signal mixed with a pseudo-square wave,was also developed and implemented,and its capability to improve the bunch purity to the level of 10–7 was experimentally *** present the experimental setup,princi-ple,and measurement results of a system for detection and cleaning of parasitic bunches.

关键词： Parasitic bunches Impurity growth High energy photon source(HEPS)

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Bunch length manipulation in a diffraction-limited storage ring

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Chinese physics C 2015年第12期39卷 62-66页

作者：田赛克焦毅王九庆 Key Laboratory of Particle Acceleration Physics and Technology Institute of High Energy PhysicsChinese Academy of Sciences

In an electron storage ring, the bunch length can be increased or decreased by using harmonic cavities. Taking the High Energy Photon Source as an example, we test the bunch length manipulation with harmonic cavities in a diffraction-limited storage ring （DLSR）. The most important collective effects in a DLSR, intra-beam scattering and Touschek effects, are evaluated for different bunch-length patterns. Our study shows that it is feasible to produce long and short bunches simultaneously in a DLSR, without causing severe emittance growth and reduction in lifetime.

关键词： high harmonic cavity diffraction-limited storage ring intra-beam scattering Touschek effects

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