束团晕和束团纯度监测

High throughput data streaming of individual longitudinal electron bunch profiles in a storage ring with single-shot electro-optical sampling

The development of fast detection methods for comprehensive monitoring of electron bunches is a prerequisite to gain comprehensive control over the synchrontron emission in storage rings with their MHz repetition rate. Here, we present a proof-of-principle experiment with at detailed description of our implementation to detect the longitudinal electron bunch profiles via single-shot, near-field electro-optical sampling at the Karlsruhe Research Accelerator (KARA). Our experiment is equipped with an ultra-fast line array camera providing a high-throughput MHz data stream. We characterize statis…

Emission of Low-Energy Photons by Electrons at Electron-Positron and Electron-Ion Colliders with Dense Bunches

Usually, the emission of low-energy photons in electron-positron (or electron-ion) bunch collisions is calculated with the same approach as for synchrotron radiation (beamstrahlung). However, for soft photons (E_gamma < E_c where E_c is a critical photon energy), when the coherence length of the radiation becomes comparable to the bunch length, the beamstrahlung approximation becomes invalid. In this paper, we present results of our calculation for this region based on approximation of classical currents. We consider several colliders with dense bunches. The number of low-energy photons dN_gam…

用于FCC-ee的电光束团剖面监测器

An electro-optical bunch profile monitor for FCC-ee

针对FCC-ee多运行模式下束团参数范围广、需非破坏单次测量束团剖面的需求，基于KARA现有EO监测器，提出采用棱镜的真空内单程EO监测器新设计，原型机在CLEAR测试验证了原理可行性。

Compact single-shot electro-optic detection system for THz pulses with femtosecond time resolution at MHz repetition rates

Electro-optical detection has proven to be a valuable technique to study temporal profiles of THz pulses with pulse durations down to femtoseconds. As the Coulomb field around a relativistic electron bunch resembles the current profile, electro-optical detection can be exploited for non-invasive bunch length measurements at accelerators. We have developed a very compact and robust electro-optical detection system based on spectral decoding for bunch length monitoring at the European XFEL with single-shot resolution better than 200~fs. Apart from the GaP crystal and the corresponding laser opti…

基于RFSoC技术的新型束团振荡记录仪的开发

Development of a novel bunch oscillation recorder with RFSoC technology

针对SuperKEKB加速器突发束流损失（SBL）阻碍亮度提升并威胁设备的问题，开发基于RFSoC技术的新型束团振荡记录仪（BOR），其位置分辨率达0.03毫米，可实时监测并记录SBL事件，助力识别束流不稳定性来源以解决SBL问题。

High current $\mathrm{H}_2^+$ beams from a filament-driven multicusp ion source

Recently, the use of $\mathrm{H}_2^+$ ions instead of protons to overcome space charge challenges in compact cyclotrons has received much attention. This technique has the potential to increase the available beam current from compact cyclotrons by an order of magnitude, paving the way for applications in energy research, medical isotope production, and particle physics, e.g. a decisive search for sterile neutrinos through the IsoDAR experiment. For IsoDAR we go a step beyond just using $\mathrm{H}_2^+$ and add pre-bunching through a Radio-Frequency Quadrupole (RFQ) embedded in the cyclotron yo…

利用高性能轨迹拟合技术对欧洲XFEL的束流能量进行测量

Beam energy measurement at the European XFEL with high-performance trajectory fitting

本研究提出一种无需手动调整、可应用于晶格任意色散区段的高性能轨迹拟合方法，可在常规x86硬件上实时每秒测量数千个束团的能量，用于欧洲XFEL的束流能量监测。

Investigation on the Ion Motion towards Clearing Electrodes in High-Brightness Electron Accelerators

High-brightness electron beams provided by modern accelerators require several measures to preserve their high quality and to avoid instabilities. The mitigation of the impact of residual ions is one of these measures. It is particularly important if high bunch charges in combination with high repetition rates are aimed for. This is because ions can be trapped in the strong negative electrical potential of the electron beam causing emittance blow-up, increased beam halo and longitudinal and transverse instabilities. Over the last decades three ion-clearing strategies have been applied to count…

用于高电流H$_2^+$束流的MIST-1与MIST-2多尖点离子源

The MIST-1 and MIST-2 multicusp ion sources for high-current H$_2^+$ beams

本文介绍了为HCHC-XX紧凑型回旋加速器设计的两代多尖点离子源MIST-1与MIST-2，重点阐述MIST-2的改进设计，并通过实验将总引出电流提升至7 mA，达到MIST-1的2倍。

A Resonant Cavity for Single-Shot Emittance Measurement

We present a non-invasive, resonant cavity based approach to beam emittance measurement of a shot-to-shot non-circular beam pulse of multi-bunches. In a resonant cavity, desired field components can be enhanced up to Q_L_lambda/pi, where Q_L_lambda is the loaded Q of the resonance mode lambda, when the cavity resonant mode matches with the beam operating frequency. In particular, a Quad-cavity, with its quadrupole mode at beam operating frequency, extracts the beam quad-moment exclusively, utilizing the symmetry of the cavity and some simple networks to suppress common modes. Six successive be…

Measurements of beam halo diffusion and population density in the Tevatron and in the Large Hadron Collider

Halo dynamics influences global accelerator performance: beam lifetimes, emittance growth, dynamic aperture, and collimation efficiency. Halo monitoring and control are also critical for the operation of high-power machines. For instance, in the high-luminosity upgrade of the LHC, the energy stored in the beam tails may reach several megajoules. Fast losses can result in superconducting magnet quenches, magnet damage, or even collimator deformation. The need arises to measure the beam halo and to remove it at controllable rates. In the Tevatron and in the LHC, halo population densities and dif…

费米实验室 Mu2e 静电隔板高压的 GUI 控制系统

GUI Control System for the Mu2e Electrostatic Septum High Voltage at Fermilab

本文介绍费米实验室 Mu2e 静电隔板的 GUI 控制系统，基于 ACNET 与 ACSys DPM Client 实现高压老练、监控、保护和日志记录自动化。

Polarization and Centre-of-mass Energy Calibration at FCC-ee

The first stage of the FCC (Future Circular Collider) is a high-luminosity electron-positron collider (FCC-ee) with centre-of-mass energy ranging from 88 to 365 GeV, to study with high precision the Z, W, Higgs and top particles, with samples of $5 \times 10^{12}$ Z bosons, $10^8$ W pairs, $10^6$ Higgs bosons and $10^6$ top quark pairs. A cornerstone of the physics program lays in the precise (ppm) measurements of the W and Z masses and widths, as well as forward-backward asymmetries. To this effect the centre-of-mass energy distribution should be determined with the high precision. This docum…