重离子储存环CSRe上类钠Kr^(25+)离子的双电子复合精密谱学实验研究

高电荷态离子的双电子复合精密谱学实验研究,不仅对天体等离子体和聚变等离子体的研究具有重要意义,而且可以作为一种新的精密谱学工具,用来检验强场量子电动力学效应、测量同位素移动及提取原子核电荷半径等.在兰州重离子储存环CSRe上,安装了专门用于电子-离子复合精密谱学实验的电子束能量调制系统,质心系下电子-离子碰撞能量的调制范围达到0—1 keV.在CSRe电子冷却器下游安装了自主研制的塑料闪烁体探测器和多丝正比探测器,用于探测复合离子.在此基础上,使用Kr^(25+)离子在CSRe上进行了首次双电子复合测试实验,实验测量了质心系能量0—70 eV的双电子复合速率系数.为了更好地理解实验测量结果,利用FAC(flexible atomic code)程序计算了Kr^(25+)离子的双电子复合速率系数,并与实验做了细致对比,整体符合很好,而且发现3s→41(△n=1)的共振跃迁对实验谱线有很大的贡献.实验结果表明,CSRe双电子复合实验平台具有非常好的稳定性和可重复性,能够为下一步开展更高电荷态离子的双电子复合精密谱学实验、检验强场量子电动力学效应以及原子核性质精密测量等前沿实验提供支持.

合肥先进光源:赋能关联电子系统研究

合肥先进光源是一个第四代衍射极限储存环光源,计划于2028年投入运行,凭借其高亮度和高相干性X射线,将突破当前X射线技术研究关联电子系统所面临的时空分辨率瓶颈,为理解这些材料中新奇物性的本质和微观起源提供关键信息.本文介绍了合肥先进光源的主要科学目标和技术优势,重点阐述了角分辨光电子能谱、磁圆二色、相干X射线散射和相干X射线成像等核心技术在量子材料和关联电子系统研究中的应用前景.这些技术将能精细解析电子/自旋/轨道态的分布和动力学过程,揭示各种新奇量子现象,以及关联电子体系中各种序参量的涨落.合肥先进光源的建成将为解码复杂量子态和非平衡演化行为提供先进的技术支持,最终推动量子材料和关联电子系统在能源、信息等前沿领域的应用.

高能同步辐射光源科学数据传输系统设计和实现

【目的】高能同步辐射光源HEPS(High Energy Photon Source)是我国第一台高能量同步辐射光源,预计2025年建成。HEPS建成后,首批投入使用的15条光束线站预计每天会产生200TB实验数据。为满足不同阶段对实验数据的读写需求,会对海量实验数据进行分级存储和长期备份。如何将这些数据在不同存储介质之间稳定和高效地传输是HEPS实验中需要解决的重要问题。【方法】HEPS科学数据传输系统设计了多源DAQ接口、任务调度、消息队列、集群传输、日志监控、配置管理和消息通知等功能模块。【结论】系统实现了海量数据在不同存储介质间的高效、可靠传输。【结果】系统现部署在北京同步辐射多个线站,用作HEPS数据传输的前期验证,运行稳定、效果良好,为科研人员和用户提供了良好的数据传输服务。

基于粒子群优化算法设计超级陶粲装置中的螺线管蛇装置

在环形对撞机中等方位角间隔安装奇数个西伯利亚蛇是用来获得纵向极化束对撞的通常方案。根据超级陶粲装置的特点,选取螺线管型西伯利亚蛇作为维持束流极化的装置。详细介绍了如何把粒子群优化算法与螺线管蛇去耦合和光学匹配问题相结合,对它进行快速优化设计,并对设计结果进行了展示。结果显示,基于粒子群算法的螺线管蛇优化设计有效且高效。

The dynamics beamline at SSRF

The dynamics beamline(D-Line),which combines synchrotron radiation infrared spectroscopy(SR-IR)and energy-disper-sive 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 2.5×10^(12)photons/s·300 eV BW@7.2 keV at the sample position.An exchange-able 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 3.5μm(H)×21.5μm(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.

Bunch-length measurement at a bunch-by-bunch rate based on time–frequency-domain joint analysis techniques and its application

This paper presents a new technique for measuring the bunch length of a high-energy electron beam at a bunch-by-bunch rate in storage rings.This technique uses the time–frequency-domain joint analysis of the bunch signal to obtain bunch-by-bunch and turn-by-turn longitudinal parameters,such as bunch length and synchronous phase.The bunch signal is obtained using a button electrode with a bandwidth of several gigahertz.The data acquisition device was a high-speed digital oscilloscope with a sampling rate of more than 10 GS/s,and the single-shot sampling data buffer covered thousands of turns.The bunch-length and synchronous phase information were extracted via offline calculations using Python scripts.The calibration coefficient of the system was determined using a commercial streak camera.Moreover,this technique was tested on two different storage rings and successfully captured various longitudinal transient processes during the harmonic cavity debugging process at the Shanghai Synchrotron Radiation Facility(SSRF),and longitudinal instabilities were observed during the single-bunch accumulation process at Hefei Light Source(HLS).For Gaussian-distribution bunches,the uncertainty of the bunch phase obtained using this technique was better than 0.2 ps,and the bunch-length uncertainty was better than 1 ps.The dynamic range exceeded 10 ms.This technology is a powerful and versatile beam diagnostic tool that can be conveniently deployed in high-energy electron storage rings.

Beam based alignment using a neural network

Beams typically do not travel through the magnet centers because of errors in storage rings.The beam deviating from the quadrupole centers is affected by additional dipole fields due to magnetic field feed-down.Beam-based alignment(BBA)is often performed to determine a golden orbit where the beam circulates around the quadrupole center axes.For storage rings with many quadrupoles,the conventional BBA procedure is time-consuming,particularly in the commissioning phase,because of the necessary iterative process.In addition,the conventional BBA method can be affected by strong coupling and the nonlinearity of the storage ring optics.In this study,a novel method based on a neural network was proposed to determine the golden orbit in a much shorter time with reasonable accuracy.This golden orbit can be used directly for operation or adopted as a starting point for conventional BBA.The method was demonstrated in the HLS-II storage ring for the first time through simulations and online experiments.The results of the experiments showed that the golden orbit obtained using this new method was consistent with that obtained using the conventional BBA.The development of this new method and the corresponding experiments are reported in this paper.

合肥先进光源储存环超导纵向梯度弯铁样机研制

介绍了合肥先进光源储存环超导纵向梯度弯铁样机的研制工作,基于已发展的一种磁体结构参数优化方法,综合考虑磁场空间分布需求和超导线圈工作负载,完成了磁铁结构的设计和优化。为了验证磁体设计方案,应用一种矩形铌钛线材和DT4C电工纯铁材料,研制了一台纵向长度0.30 m、磁极间隙46 mm的磁体样机。并搭建了一套简易低温测试装置,对该磁体进行了励磁特性测量,经过10余次失超,测得磁体最大工作电流大于275 A。磁体纵向磁场分布测量结果表明,该磁体在约196 A工作电流下,纵向磁场积分值达到0.4 T·m,峰值磁场约4.5 T。测试结果与理论设计结果基本一致,表明该种超导磁体的设计是可行的。

合肥光源1 nm发射度的储存环初步物理设计研究

针对合肥光源未来升级为纳米级发射度储存环的计划,设计了一个紧凑的H6BA lattice物理方案。在800 MeV束流能量下,自然发射度为1.2 nm·rad,达到了所辐射的极紫外光的衍射极限发射度。考虑误差效应的6D动力学孔径在水平正方向上大于20 mm,可满足离轴注入的需要。由于束流能量和发射度均较低,束内散射和Touschek效应显著,考虑10%耦合情况下,平衡发射度增长了约50%,Touschek寿命为4.2 h,采用全耦合模式可较为有效地抑制这2种效应。

HIRFL-CSR上全剥离同核异能态离子的寿命测量

高电荷态离子的寿命数据被广泛应用于核物理及核天体物理等多个研究领域,在核废料处理等应用领域具有潜在应用价值。在兰州重离子加速器装置(HIRFL-CSR)上建立了一套基于等时性质量谱仪测量全剥离同核异能态离子寿命的实验方法。该实验方法在测量几十微秒到几百微秒时间尺度上发生的核衰变具有独特优势,尤其适用于开展全剥离同核异能态离子的衰变研究。飞行时间探测器记录离子的时间信号,通过这些时间信号可提取出每个离子的飞行时间信息并得到飞行时间与循环圈数的直线拟合残差。直线拟合残差就可以来鉴别衰变事件,基于衰变事件可得到全剥离同核异能态离子^(94)m Ru^(44+)的寿命。实验证明了基于储存环开展短寿命高电荷同核异能态离子衰变研究的可行性。

Event plane determination from the zero degree calorimeter at the cooling storage ring external-target experiment

The Cooling Storage Ring external-target experiment(CEE)spectrometer is used to study the nuclear matter created in heavy-ion collisions at√sNN=2.1-2.4 GeV with the aim to reveal the quantum chromodynamics phase structure in the high-baryon-density region.Collective flow is considered an effective probe for evaluating the properties of media during high-energy nuclear collisions.One of the main functions of the zero-degree calorimeter(ZDC),a subdetector system in the CEE,is to determine the reaction plane in heavy-ion collisions.This step is crucial for measuring the collective flow and other reaction-plane-related analyses.In this paper,we illustrate the procedures for event plane determination using the ZDC.Finally,isospin-dependent quantum molecular dynamics model-based predictions of the rapidity dependence of the directed and elliptical flows for p,d,t,3He,and 4He,produced in 2.1 GeV U+U collisions,are presented.

ID effects on beam dynamics in the SSRF-U storage ring

This paper introduces the proposed insertion device(ID)scheme for the Shanghai Synchrotron Radiation Facility Upgrade.Based on this scheme,the influences of the ID radiation on the intra-beam scattering emittance and energy spread were evaluated.Optical distortion caused by the IDs was comprehensively examined and compensated using both local and global corrections.Subsequently,a frequency map analysis method was used to identify potentially dangerous resonance lines.In addition,the dynamic aperture,energy acceptance,and Touschek lifetime were calculated after considering high-order magnetic field errors to ensure that the ID effect did not affect the operation of the storage ring.

Design and comparison of hybrid multi-bend achromat lattices for HALF storage ring

The Hefei Advanced Light Facility(HALF)proposed by the National Synchrotron Radiation Laboratory is a green-field vacuum ultraviolet and soft X-ray diffraction-limited storage ring light source with a beam energy of 2.2 GeV and emittance goal of less than 100 pm rad.Inspired by the ESRF-EBS hybrid multi-bend achromat(HMBA),SLS-2,and Diamond-II lattices,we have proposed and designed a modified H6BA lattice as the baseline lattice of the HALF storage ring with 20 identical cells and a natural emittance of approximately 86 pm rad.In this paper,three other types of HMBA lattices including two H7BA lattices and a H6BA lattice are designed for HALF with the same number of cells.The main storage ring proper-ties of these four HMBA lattices are compared.Because the intra-beam scattering(IBS)effect is significant in the HALF storage ring,we calculate and compare the equilibrium emittances of the four lattices with IBS included.These comparisons show that the present modified H6BA lattice,which has a relatively low equilibrium emittance and more straight sections,is preferred for the HALF storage ring after a comprehensive consideration.

Design and optimization of diffraction-limited storage ring lattices based on many-objective evolutionary algorithms

Multi-objective evolutionary algorithms(MOEAs) are typically used to optimize two or three objectives in the accelerator field and perform well. However, the performance of these algorithms may severely deteriorate when the optimization objectives for an accelerator are equal to or greater than four. Recently, many-objective evolutionary algorithms(MaOEAs)that can solve problems with four or more optimization objectives have received extensive attention. In this study, two diffraction-limited storage ring(DLSR) lattices of the Extremely Brilliant Source(ESRF-EBS) type with different energies were designed and optimized using three MaOEAs and a widely used MOEA. The initial population was found to have a significant impact on the performance of the algorithms and was carefully studied. The performances of the four algorithms were compared, and the results demonstrated that the grid-based evolutionary algorithm(GrEA) had the best performance.Ma OEAs were applied in many-objective optimization of DLSR lattices for the first time, and lattices with natural emittances of 116 and 23 pm·rad were obtained at energies of 2 and 6 GeV, respectively, both with reasonable dynamic aperture and local momentum aperture(LMA). This work provides a valuable reference for future many-objective optimization of DLSRs.

High-precision high-voltage detuning system for HIAF-SRing electron target

The development of a detuning system for the precision control of electron energy is a major challenge when electron targets are used in ion-storage rings.Thus,a high-precision,high-voltage,detuning system was developed for the electron target of a high-intensity heavy-ion accelerator facility-spectrometer ring(HIAF-SRing)to produce accurate electron-ion relative energies during experiments.The system consists of auxiliary,and high-voltage detuning power supplies.The front stage of the auxiliary power supply adopts an LCC resonant converter operating in the soft-switching state and an LC filter for a sinusoidal waveform output in the post-stage.The detuning power supply is a high-voltage pulse amplifier(HVPA)connected with a high-voltage DC(HVDC)module in series.In this paper,the design and development of the detuning system are described in detail,and the test bench is presented.The test results demonstrated that the detuning system conforms to the technical specifications of the dielectronic recombination(DR)experiment.Finally,a Fe15+DR spectrum was measured using the detuning system.The experimental data demonstrated a good experimental resolution and verified the reliability and feasibility of the design.

Absolute dielectronic recombination rate coefficients of highly charged ions at the storage ring CSRm and CSRe

Dielectronic recombination(DR)is one of the dominant electron-ion recombination mechanisms for most highly charged ions(HCIs)in cosmic plasmas,and thus,it determines the charge state distribution and ionization balance therein.To reliably interpret spectra from cosmic sources and model the astrophysical plasmas,precise DR rate coefficients are required to build up an accurate understanding of the ionization balance of the sources.The main cooler storage ring(CSRm)and the experimental cooler storage ring(CSRe)at the Heavy-Ion Research Facility in Lanzhou(HIRFL)are both equipped with electron cooling devices,which provide an excellent experimental platform for electron-ion collision studies for HCIs.Here,the status of the DR experiments at the HIRFL-CSR is outlined,and the DR measurements with Na-like Kr25^(+)ions at the CSRm and CSRe are taken as examples.In addition,the plasma recombination rate coefficients for Ar12^(+),14^(+),Ca14^(+),16^(+),17^(+),Ni19^(+),and Kr25^(+)ions obtained at the HIRFL-CSR are provided.All the data presented in this paper are openly available at https://doi.org/10.57760/sciencedb.j00113.00092.

Classifier for centrality determination with zero-degree calorimeter at the cooling-storage-ring external-target experiment

The zero-degree calorimeter(ZDC)plays a crucial role toward determining the centrality in the Cooling-Storage-Ring External-target Experiment(CEE)at the Heavy Ion Research Facility in Lanzhou.A boosted decision tree(BDT)multi-classification algorithm was employed to classify the centrality of the collision events based on the raw features from ZDC such as the number of fired channels and deposited energy.The data from simulated^(238)U+^(238)U collisions at 500 MeV∕u,generated by the IQMD event generator and subsequently modeled using the GEANT4 package,were employed to train and test the BDT model.The results showed the high accuracy of the multi-classification model adopted in ZDC for centrality determination,which is robust against variations in different factors of detector geometry and response.This study demon-strates the good performance of CEE-ZDC in determining the centrality in nucleus-nucleus collisions.

Study on crab-cavity-based longitudinal injection scheme and prototype realization of C-band crab cavity for electron storage rings

A diffraction-limited storage ring with a multi-bend achromat lattice suffers from a small dynamic aperture for conventional off-axis injection.Thus,a longitudinal on-axis injection scheme based on a new type of crab cavity is proposed in this paper.Particle tracking simulations were performed to study the disturbance of the stored beam and the motion of the injected beam during the injection process.The possibility of multi-bunch injections was discussed.In addition,the effect of the long-range wake field induced by the stored beam was analyzed.A C-band standing-wave crab cavity was designed and produced as requested,and its field distribution was measured.The corresponding results are consistent with the simulation results.

基于对数比电路的HLS turn-by-turn系统

较详细地介绍了合肥光源逐圈束流位置测量 (turn- by- turn)系统设计思想和理论分析。该系统是为了判定二期工程升级后的注入系统的注入效率和 Damping率 ,研究 Beta振荡和轨迹瞬时变化以及其他束流动力学问题如工作点变化等的研究而研制。选择了新近受到广泛重视的对数比电路服务束流瞬时位置信号的处理。利用工作在 2 0 4MHz的对数比电路完成被激励束的 turn- by- turn位置测量和相空间检测。给出了该系统各部分性能和理论分析结果 ,介绍了快速多通道 ADC在该系统的数据获取中的应用。

合肥光源利用电阻分流法的基于束流准直系统的研制

介绍了合肥光源基于束流准直系统的研制 ,该系统利用可开关的电阻分流法构成 ,并采用固态继电器进行四极铁分流控制。利用该系统可以测量束流位置检测器的电中心相对相邻四极铁磁中心的位置偏移。