[Background]Sextupoles are an important component of storage ring octonal unit in high energy synchrotron radiation sources.They require complex technological processes and precise center extraction.Therefore,it is necessary to find out the most reasonable calibration scheme for the mechanical center.[Purpose]This study aims at the calibration scheme for the mechanical center extraction of high energy photon Ssurce(HEPS)sextupoles,and obtaining the corrected mechanical central coordinate system.[Methods]The method of directly measuring the reference plane of the sextupole was adopted for the mechanical center calibration of magnets.By rotating the conventional calibration coordinate system with a given pole seam deviation angle,the three polar seam surfaces were brought closer to the theoretical positions to decrease the main diagonal component of the sextupoles.The mechanical center calibrations were performed twice for each hexacode iron to further reduce the impact of the polar seam error.[Results]The calibration results show that the calibration repeat accuracy is 0.005 mm for the sextupole.The standard deviation between the measured value and the design value of the pole seam spacing is 0.015 mm.Additionally,the standard deviation of the reference point before and after the rotation of the coordinate system is 0.09 mm,with a maximum rotation angle of 0.6 mrad.[Conclusions]The calibration scheme of this study can be used to improve the calibration accuracy and provide reference for the calibration of similar equipment.It ensures smooth installation of accelerator devices and is of significant importance for accelerator collimation measurements.

Achieving high performance in synchrotron radiation light sources demands increased precision in fiducialization and alignment of insertion devices (IDs). Conventional sensor systems utilizing Hall probes for high-precision magnetic field measurements face limitations in determining the absolute position of the magnetic center of IDs. In this paper, the Magnetic Landmark (MLK), a novel solution based on a magnetized block structure, is designed to address this challenge. The MLK serves as an intermediary, establishing contact between the magnetic center of IDs and their externally accessible fiducials, thus enabling high-precision alignment. Through analysis of magnetic field distribution, self-calibration precision, and practical application of the MLK, the following conclusions are drawn: when the Hall probe is positioned within 0.5 mm of the magnetic field zero point inside the MLK, the measurement accuracy of the zero point for normal and skew quadrupole magnetic fields reaches 7 and 2 mu m, respectively. Additionally, the self-measurement accuracy of the MLK is 10 and 4 mu m in the transverse and vertical directions, respectively. These accuracies meet our usage requirements. The MLK demonstrates efficacy in aligning the magnetic center of High Energy Photon Source (HEPS) In-air undulators, achieving alignment accuracies of 16 mu m in the transverse direction and 11 mu m in the vertical direction, surpassing the 30 mu m accuracy stipulated in the physical design. Furthermore, the device proves applicable for measuring the magnetic center of other types of HEPS insertion devices, including Cryogenic undulators.

The Chinese high energy photon source is the fourth-generation light source that is currently under construction, with the booster being a significant component that has been completed by October 2022. In order to meet this timeline, 218 magnets requiring calibration were fitted with a rotating coil system and a three-coordinate measuring machine to optimize magnet center calibration. The rotating coil system is specially designed for magnetic center measurements. It employs a single-turn coil instead of the traditional complex compensated coil and uses a three-coordinate measuring machine imaging probe for precise positioning of the wire in space. This system has high accuracy, high speed, and high reliability. However, it is limited by the size of the three-coordinate measuring machine, meaning that larger magnets cannot be measured, thus limiting scalability. In September 2022, all of the magnets had been calibrated. This paper introduces the various aspects of coil design and examines the efficacy of employing three-coordinate measuring machine imaging for coil rotation center positioning and sag measurement, and provides a statistical analysis of calibration performance alongside mechanical calibration errors, the deviation between the magnet center and the mechanical center, and also a scatter analysis. Additionally, this paper also outlines the changes in the measuring time for each magnet, providing a reference for future magnet center calibration tasks.

高能同步辐射光源(HEPS)的预准直单元数量庞大,且磁铁准直精度要求极高,为检验HEPS增强器预准直单元磁铁准直精度,需要在实验厅按照一定比例对其进行振动线磁中心验证测量.基于预研阶段已研发的振动线系统,详细介绍了振动线磁中心测量原理及扫描方法,研究了HEPS增强器两铁单元的磁中心准直精度检测方法并进行了验证实验.设计并搭建了振动线高精度重复定位夹持机构装置,研究了振动线下垂量的修正方法,并对增强器两铁单元的磁中心扫描结果进行拟合分析.实验结果表明,HEPS增强器两铁单元满足磁铁间相对位置误差优于 50 μm的预准直精度要求.

High-precision pre-alignment of the magnet components is an important step in the construction and operation of the High Energy Photon Source (HEPS). In order to achieve 10 mu m pre-alignment accuracy of storage ring in transverse and vertical, four laser trackers were used for set up a four-station multilateration measurement system. A Rank-defect Free-network adjustment model was used to analysis the measurement accuracy of different arrangements of multilateration measurement system. By simulation, it shows when the four stations form a right-angled regular triangular pyramid the highest point measurement accuracy can be gotten. A multilateration measurement system formed by four laser tracker was built in the laboratory. Experiment results show that the absolute position measurement accuracy is within 7.1 mu m and the relative displacement measurement accuracy is better than 3 mu m in a 4 m x 1.2 m x 1.5 m volume, which can satisfy the real-time position feedback accuracy of the magnets in the process of ultra-high-precision pre-alignment. Then, a pre -alignment experiment for High Energy Photon Source based on this system was carried out, and finally the 10 mu m pre-alignment accuracy goal in transverse and vertical was achieved.

To ensure high-precision alignment of large quantities of magnets in Chinese high energy photon source, a high magnetic center measurement efficiency is required. To achieve this, a unique single-turn rotating coil magnetic center calibration system was designed, which simplifies the traditional multi-turn compensated coil with two sets of windings that can be connected. This design reduces measurement time significantly while increasing precision by incorporating a three-coordinate measuring machine. The study presents the system’s general design, mathematical theory, and test results. Tests replacing the coil and magnets and realigning them demonstrated that the precision and measurement efficiency meet the design requirements. The displacement between the magnetic and mechanical axes was within 20 μm, indicating good performance of the well-fabricated and tested ultra-high gradient quadrupole magnet. The optimized rotating coil system design reduces the entire procedure, including magnet installation and alignment, magnetic axis measurement, and magnetic center extraction to fixed points on the magnet, to only a few hours. Several magnets participating in pre-alignment were measured, and tests and practical operation resulted in small magnetic center displacements.

Symmetry manipulation can be used to effectively tailor the physical order in solid-state systems. With the breaking of both the inversion and time-reversal symmetries, nonreciprocal magneto-transport may arise in nonmagnetic systems to enrich spin-orbit effects. Here, the observation of unidirectional magnetoresistance (UMR) in lattice-matched InSb/CdTe films is investigated up to room temperature. Benefiting from the strong built-in electric field of 0.13 V nm-1 in the heterojunction region, the resulting Rashba-type spin-orbit coupling and quantum confinement result in a distinct sinusoidal UMR signal with a nonreciprocal coefficient that is 1-2 orders of magnitude larger than most non-centrosymmetric materials at 298 K. Moreover, this heterostructure configuration enables highly efficient gate tuning of the rectification response, wherein the UMR amplitude is enhanced by 40%. The results of this study advocate the use of narrow-bandgap semiconductor-based hybrid systems with robust spin textures as suitable platforms for the pursuit of controllable chiral spin-orbit applications.

在高能同步辐射光源中,为了提高磁铁的准直精度,采用磁中心代替机械中心进行磁铁标定,通过振动线或旋转线等技术获得磁铁的磁中心位置,以及通过电容式位移传感器测量得到丝线的位置,从而实现磁中心与准直靶标的关联.为了实现丝线位置的高精度测量,必须对电容传感器进行精确标定,因此介绍了一种电容式位移传感器,并对其标定方法进行了研究,提出了网格化的数据采集方式以及高阶多项式拟合的数据处理方法,搭建了传感器标定平台并开发了相应的标定控制程序,实现了对传感器的自动控制、数据采集和高精度标定过程.经过分析与对比,标定后的电容传感器达到μm级的位移测量精度,为磁铁的高精度准直提供了基础.

Background Currently, laser tracker is the primary instrument used to carry out three-dimensional position measurement in accelerator alignment. Theoretically, three-dimensional measuring data processed by three-dimensional adjustment are more rigorous, however, error accumulation is found in practice. Purpose In order to control error accumulation and further improve the measurement accuracy of accelerator alignment, this research introduces the laser alignment system into the activity of measurement and data processing. Methods A measurement scheme combining laser tracker and laser alignment system is proposed. To construct the constraint condition, the offset values from the measuring points to the laser straight-line datum were used. To carry out the three-dimensional adjustment with offset constraint, the laser tracker observations were used. Results A three-dimensional adjustment function model of laser tracker observations is given. The construction method of the constraint equation is researched, and the calculation formulas of the three-dimensional adjustment with offset constraint are derived. A 200 m linac tunnel control network is designed, using simulation measurement method, the measuring data of laser tracker and the offset values from the measuring points to the laser straight-line datum were generated. The simulated data are calculated by the method given in this paper and the result is analyzed. Conclusion Simulation result shows introducing the laser alignment system into laser tracker measurement and applying the three-dimensional adjustment with offset constraint can effectively suppress the error accumulation caused by long distance move station measurement.

Antiferromagnetic materials, which have ordered but alternating magnetic moments, exhibit fast spin dynamics and produce negligible stray fields, and could be used to build high-density, high-speed memory devices with low power consumption. However, the efficient electrical detection and manipulation of antiferromagnetic moments is challenging. Here we show that the spin current and antiferromagnetic moments in the topological insulator/antiferromagnetic insulator bilayer (Bi,Sb) 2 Te 3 /α-Fe 2 O 3 can be controlled via topological surface states. In particular, the orientation of the antiferromagnetic moments in α-Fe 2 O 3 can modulate the spin current reflection at the bilayer interface. In turn, the spin current can control the moment rotation in the antiferromagnetic insulator by means of a giant spin–orbit torque generated by the topological surface state. The required threshold switching current density is 3.5 × 10 6 A cm −2 at room temperature, which is one order of magnitude smaller than that required in heavy-metal/antiferromagnetic insulator systems.

当前加速器准直主要采用激光跟踪仪进行三维空间位置测量,三维测量数据用三维平差方法计算从理论上讲更为严密,但在实践中却发现存在误差累积现象,其中在高程方向的误差累积十分明显.为了控制三维平差高程方向的误差累积,研究将大地水准面做为基准引入测量和数据处理过程之中,获得基于大地水准面的高程测量数据,用高程数据构建约束条件方程,进行附有高程约束的三维平差.以激光跟踪仪为例给出了三维平差函数模型,研究了约束方程的构建方法,推导了附有高程约束的三维平差计算公式.研究了附有高程约束的三维平差函数模型的两种应用方法,通过模拟计算展示了这两种方法对高程方向误差累积的控制效果.最后对一组实测数据采用多种平差方法进行计算对比,结果显示附有高程约束的三维平差相比无高程约束的三维平差能够更有效的控制平差中高程方向的误差累积.

以中国散裂中子源CSNS的直线加速器控制网为例,对其数据处理方法进行研究,采用平面与高程二维平差以及三维定向平差两种方式对准直控制网进行处理分析.同时,为了使准直数据处理更加简易便利,提出利用激光跟踪仪的测量软件SA实现三维定向平差的方法.通过不同软件及不同数据处理方法的对比,验证准直控制网数据处理的正确性,最终200 m长直线控制网点位精度优于0.2 mm,这为准直控制网的数据处理提供了指导.

BackgroundCompared with 2D+1D adjustment, three dimensional adjustment has a more rigorous theoretical basis. However, when the unconstrained three dimensional adjustment is applied to the observation values processing of the accelerator alignment control network, serious error accumulation will occur and resulting in obvious distortion of the results.PurposeThis study aims to expound the ways and characteristics of three dimensional adjustment error accumulation for accelerator alignment control network.MethodsFirstly, based on the layout of accelerator alignment control network and the moving station measurement method of laser tracker, the three dimensional adjustment mathematical model was analyzed, and the least-squares collocation theory was used to clearly explain the error propagation. Secondly, the characters of laser tracker measurement accuracy, station positioning and orientation accuracy and single station measurement error propagation were studied by analyzing the laser tracker 3D coordinate measurement model, measurement point error model and simulation measurement experiments. Finally, adjustment calculation of the linac control network was verified by simulation measurement, and two error accumulation suppression methods were tested.ResultsThe source and propagation mode of error accumulation are explained theoretically, and verified by simulation calculation, so are the serious error accumulation of elevation and lateral errors in three dimensional adjustment of control network in accelerator.ConclusionsProviding high-precision point coordinate constraint for three dimensional adjustment can effectively suppress error accumulation, and providing high-precision orientation constraint for station coordinate system can also achieve the effect of suppressing error accumulation.

We report the temperature dependence of the spin–orbit torque (SOT) in the in situ grown Bi2Te3/MnTe heterostructures by molecular beam epitaxy. By appropriately designing the film stack, robust ferromagnetic order with high Curie temperature and strong perpendicular magnetic anisotropy is established in the MnTe layer. Meanwhile, the sharp hetero-interface warrants highly efficient spin current injection from the conductive topological insulator (TI) channel. Accordingly, SOT-driven magnetization switching is observed up to 90 K with the critical current density within the 106 A⋅cm−2 range. More importantly, the temperature-dependent harmonic measurement data can be divided into two categories, namely, the spin Hall effect of the TI bulk states gives rise to a relatively small spin Hall angle in the high-temperature region, whereas the spin-momentum locking nature of the interfacial Dirac fermions leads to the enhancement of the SOT strength once the topological surface states become the dominant conduction channel at deep cryogenic temperatures. Our results offer direct evidence of the underlying mechanism that determines the SOT efficiency and may set up a suitable platform to realize TI-based spin–orbit applications toward room temperature.

Engineering the anomalous Hall effect (AHE) is the key to manipulate the magnetic orders in the emerging magnetic topological insulators (MTIs). In this letter, we synthesize the epitaxial Bi2Te3/MnTe magnetic heterostructures and observe pronounced AHE signals from both layers combined together. The evolution of the resulting hybrid AHE intensity with the top Bi2Te3 layer thickness manifests the presence of an intrinsic ferromagnetic phase induced by the topological surface states at the heterolayer interface. More importantly, by doping the Bi2Te3 layer with Sb, we are able to manipulate the sign of the Berry phase-associated AHE component. Our results demonstrate the unparalleled advantages of MTI heterostructures over magnetically doped TI counterparts in which the tunability of the AHE response can be greatly enhanced. This in turn unveils a new avenue for MTI heterostructure-based multifunctional applications.

Quantum anomalous Hall effect has been observed in magnetically doped topological insulators. However, full quantization, up until now, is limited within the sub-1 K temperature regime, although the material's magnetic ordering temperature can go beyond 100 K. Here, we study the temperature limiting factors of the effect in Cr-doped (BiSb)2Te3 systems using both transport and magneto-optical methods. By deliberate control of the thin-film thickness and doping profile, we revealed that the low occurring temperature of quantum anomalous Hall effect in current material system is a combined result of weak ferromagnetism and trivial band involvement. Our findings may provide important insights into the search for high-temperature quantum anomalous Hall insulator and other topologically related phenomena.

Integration of a quantum anomalous Hall insulator with a magnetically ordered material provides an additional degree of freedom through which the resulting exotic quantum states can be controlled. Here, an experimental observation is reported of the quantum anomalous Hall effect in a magnetically-doped topological insulator grown on the antiferromagnetic insulator Cr2 O3 . The exchange coupling between the two materials is investigated using field-cooling-dependent magnetometry and polarized neutron reflectometry. Both techniques reveal strong interfacial interaction between the antiferromagnetic order of the Cr2 O3 and the magnetic topological insulator, manifested as an exchange bias when the sample is field-cooled under an out-of-plane magnetic field, and an exchange spring-like magnetic depth profile when the system is magnetized within the film plane. These results identify antiferromagnetic insulators as suitable candidates for the manipulation of magnetic and topological order in topological insulator films.

We report the study of current-induced magnetization switching in the Ta/CoFeB heterostructures by simultaneous magneto-electrical transport and magneto-optical Kerr effect (MOKE) microscopy measurements. Although the anomalous Hall hysteresis loop summarizes the general switching behaviors, the supplementary MOKE data can provide spatial and temporal information to visualize the magnetic domain evolution as functions of the applied current and the in-plane magnetic field. More importantly, when the initial magnetic field is not sufficient enough, the interfacial Dzyaloshinskii–Moriya interaction (DMI) would modulate the spin-orbit torque (SOT) current switching dynamics and lead to the formation of the intermediate Hall resistance plateau with meta-stable tilted domain texture. Our work elucidates the importance of the applied in-plane field and unveils an effective approach to investigate the SOT/DMI-related phenomena in symmetry-breaking magnetic heterostructures.

Spin-orbit coupling (SOC), the relativistic effect describing the interaction between the orbital and spin degrees of freedom, provides an effective way to tailor the spin/magnetic orders using electrical means. Here, we report the manipulation of the spin-orbit interaction in the lattice-matched InSb/CdTe heterostructures. Owing to the energy band bending at the heterointerface, the strong Rashba effect is introduced to drive the spin precession where pronounced weak antilocalization cusps are observed up to 100 K. With effective quantum confinement and suppressed bulk conduction, the SOC strength is found to be enhanced by 75% in the ultrathin InSb/CdTe film. Most importantly, we realize the electric-field control of the interfacial Rashba effect using a field-effect transistor structure and demonstrate the gate-tuning capability which is 1-2 orders of magnitude higher than other materials. The adoption of the InSb/CdTe integration strategy may set up a general framework for the design of strongly spin-orbit coupled systems that are essential for CMOS-compatible low-power spintronics.

We report the electrical transport properties of topological Dirac semimetal Cd3As2. Unlike the ordinary Hall resistance with linear slope and the parabolic magnetoresistance (MR) in conventional semiconductors, the linear-band dispersion in this system give rise to a high electron mobility of 3.4 x 10(4) cm/V s and a giant linear MR exceeding 5 x 10(3) % at 2.1 K. More importantly, the large Hall angle-induced phenomena can be captured by applying a generic two-band magneto-transport model on both the Hall and MR data, and the fitting results are consistent over the entire temperature range from 2.1K to 350 K. Furthermore, the large-Hall-angle condition also enables the observation of distinct quantum oscillations with non-trivial band topology of the Cd3As2 sample at low temperatures. Our work provides a general approach to investigate the high-mobility topological Dirac semimetals and their potential applications. Published by AIP Publishing.