Crab Waist Collision Studies for e+e- Factories

crab-waist（蟹腰）对撞机中束束效应与纵向尾场相互作用导致的非相干水平发射度增长

Incoherent horizontal emittance growth due to the interplay of beam-beam and longitudinal wakefield in crab-waist colliders

针对蟹腰对撞机中束束效应与纵向尾场耦合引发的水平同步-回旋共振，论文扩展理论形式体系并结合SuperKEKB多代码模拟，揭示非相干水平发射度增长机制并提出缓解策略。

Crab Waist collision scheme: a novel approach for particle colliders

A new concept of nonlinear focusing of colliding bunches, called Crab Waist (CW)collision scheme, has been proposed at LNF INFN. It has been successfully tested at the Italian lepton collider DAFNE in operational conditions providing luminosity for two different experimental detectors, SIDDHARTA and KLOE-2. Considering a high efficiency of the scheme for increasing collision luminosity and its relative simplicity for implementation several new collider projects have been proposed and are under development at present. These are the SuperKEKB B-factory ready to start commissioning in 2016 in Jap…

超级陶粲装置的蟹腰相互作用区设计与集成

Crab-waist interaction region design and integration for the Super Tau-Charm Facility

本文针对超级陶粲装置（STCF）极低垂直beta函数导致的强非线性问题，提出一种模块化光学设计，通过局部色散校正、精确-I变换及优化beta函数等手段，有效抑制了非线性效应，实现了超300s的Touschek寿命并满足项目要求。

New generation electron-positron factories

In 2010 we celebrated 50 years since commissioning of the first particle storage ring ADA in Frascati (Italy) that also became the first electron-positron collider in 1964. After that date the particle colliders have increased their intensity, luminosity and energy by several orders of magnitude. Namely, because of the high stored beam currents and high rate of useful physics events (luminosity) the modern electron-positron colliders are called "factories". However, the fundamental physics has required luminosities by 1-2 orders of magnitudes higher with respect to those presently achieved. Th…

Beam-Beam Interaction in Novel, Very High Luminosity Parameter Regimes

In order to achieve luminosities significantly higher than in existing machines, future storage-ring based colliders will need to operate in novel parameter regimes combining ultra-low emittance, large Piwinski angle and high bunch charge; implementation of techniques such as a "crab waist" will add further challenges. Understanding the beam-beam interaction in these situations will be essential for the design of future very high luminosity colliders. Recent developments in modeling tools for studying beam-beam effects, capable of investigating the relevant regimes, will be discussed and examp…

SuperKEKB中束束效应的模拟与实验结果

Simulations and experimental results on beam-beam effects in SuperKEKB

本文通过束束模拟与实验，研究SuperKEKB中束束效应、蟹腰、阻抗等多因素对亮度的影响，指出关键因素与未来研究方向。

SuperKEKB 的亮度性能

Luminosity performance of SuperKEKB

本文回顾 SuperKEKB 在2020—2022年蟹腰运行下的亮度调谐与性能，分析束流-束流效应对垂直束团增大和亮度上限的关键影响，并总结其创纪录亮度成果。

Synchrotron oscillation damping due to beam-beam collisions

In DAΦNE, the Frascati e+/e- collider, the crab waist collision scheme has been successfully implemented in 2008 and 2009. During the collision operations for Siddharta experiment, an unusual synchrotron damping effect has been observed. Indeed, with the longitudinal feedback switched off, the positron beam becomes unstable with beam currents in the order of 200-300 mA. The longitudinal instability is damped by bringing the positron beam in collision with a high current electron beam (~2A). Besides, we have observed a shift of \approx 600Hz in the residual synchrotron sidebands. Precise measur…

Suppression of the longitudinal coupled bunch instability in DA$Φ$NE in collisions with a crossing angle

In DAFNE, the Frascati $e^+e^-$ collider operating since 1998, an innovative collision scheme, the crab waist, has been successfully implemented during the years 2008-09. During operations for the Siddharta experiment an unusual synchrotron oscillation damping effect induced by beam-beam collisions has been observed. Indeed, when the longitudinal feedback is off, the positron beam becomes unstable with currents above 200-300 mA due to coupled bunch instability. The longitudinal instability is damped by colliding the positron beam with a high current electron beam (of the order of 2 A). A shift…

DAFNE Interaction Regions upgrade

DAFNE, the Frascati F-factory, has recently completed experimental runs for the three main detectors, KLOE, FINUDA and DEAR achieving 1.6x10E+32 cm-2s-1 peak and 10 pb-1 daily integrated luminosities. Improving these results by a significant factor requires changing the collision scheme. For this reason, in view of the SIDDHARTA detector installation, relevant modifications of the machine have been realized, aimed at implementing a new collision scheme based on a large Piwinski angle and crab-waist, together with several other hardware modifications involving injection kickers, bellows and bea…

Beam-Beam Resonances for Different Collision Schemes

One of the main advantages of proposed by P. Raimondi "Crab Waist" collision scheme is a strong suppression of betatron resonances excited by beam-beam interaction. Some qualitative explanations with numerical examples, describing beam-beam resonances for different collision schemes, were given in arXiv:physics/0702033. This paper can be considered as an "appendix" (additional illustration) to that one. We performed a number of full 2D betatron tune scans (beam-beam simulations) for different collision schemes, so one can easily see how the beam-beam resonances appear and disappear, depending …

Design of beam optics for the Future Circular Collider e+e- -collider rings

A beam optics scheme has been designed for the Future Circular Collider-e+e- (FCC-ee). The main characteristics of the design are: beam energy 45 to 175 GeV, 100 km circumference with two interaction points (IPs) per ring, horizontal crossing angle of 30 mrad at the IP and the crab-waist scheme [1] with local chromaticity correction. The crab-waist scheme is implemented within the local chromaticity correction system without additional sextupoles, by reducing the strength of one of the two sextupoles for vertical chromatic correction at each side of the IP. So-called "tapering" of the magnets …

Limitation on the luminosity of e+e- storage rings due to beamstrahlung

Particle loss due to the emission of single energetic beamstrahlung photons in beam collisions is shown to impose a fundamental limit on storage-ring luminosities at energies greater than 2E~140 GeV for head-on collisions and 2E~40 GeV for crab-waist collisions. Above these threshold energies, the suppression factor due to beamstrahlung scales as 1/E^{4/3}, and for a fixed power of synchrotron radiation, the luminosity L is proportional to R/E^{13/3}, where R is the collider radius. For 2E > 150 GeV, both collision schemes have similar luminosity limits. The luminosities attainable at storage-…