The ILC baseline design for the positron source is based on radiation from a helical undulator to produce positrons in a thin target. Since the photon beam created in the helical undulator is circularly polarized, the generated positron beam is longitudinally polarized. Using a photon collimator upstream the positron target the positron polarization can be enhanced. However, the photon beam intensity yields a huge thermal load in the collimator material. In this paper the thermal load and heat dissipation in the photon collimator is discussed and design solutions are suggested.
Photon collimator system for the ILC Positron Source
高能电子直线对撞机是粒子物理学的下一个大规模项目.它们需要强光源来达到所需的亮度。具体地，正电子源必须每秒提供约10 E +14个正电子。国际直线对撞机（ILC）的正电子源是基于一个螺旋波荡器，电子束通过该波荡器产生一个强圆偏振光子束。利用这些光子，产生纵向偏振的正电子束;偏振度可以通过准直光子束来增强。然而，高光子束强度在准直器材料中引起巨大的热负荷。本文讨论了光子准直器的热负荷问题，并提出了一种灵活的设计方案。
In the future the International Linear Collider (ILC), a helical undulator-based polarized positron source, is expected to be chosen. A high energy electron beam passes through a superconducting helical undulator in order to create circularly polarized photons which will be directed to a conversion target, resulting in electron-positron pairs. The resulting positron beam is longitudinally polarized. Since the photons are produced with an opening angle and pass through a long superconducting helical undulator, some of these photons will strike the undulator walls. Therefore photon masks must be…
ILC正电子系统使用新颖的螺旋波荡器从主电子束产生强大的光子束。该束通过钛靶将其转化为电子-正电子对。目标被构造为以2000 RPM旋转的1 m直径的轮，以将1 ms ILC脉冲训练涂抹超过10 cm。脉冲磁通集中磁体用于提高正电子捕获效率。将其冷却至液氮温度以使1 ms ILC脉冲训练上的磁场的平坦度最大化。我们报告在这个系统上的原型工作。
国际直线对撞机（英语：International Linear Collider，ILC）是一个200-500 GeV的高亮度线性电子-正电子对撞机，基于1.3 GHz超导射频（SCRF）加速腔。ILC的总覆盖面积约为31 km，设计的峰值亮度为2 x 10^34 cm^-2 s^-1。该综合体包括一个极化电子源，一个基于波荡器的正电子源，两个6.7公里周长的阻尼环，两级聚束压缩器，两个11公里长的主直线加速器和一个4.5公里长的束流传输系统。本报告是四卷参考设计报告的第三卷（加速器），描述了ILC的设计和成本。
To realise a planned high-luminosity and high-energy $e^+e^-$-collider, as the ILC, a large amount of positrons have to be produced and the accelerated particles have to be captured and matched according to the damping ring acceptances. %There exist several technical possibilities. In this contribution a new promising alternative method for capturing positrons will be presented, the application of the plasma lens as an optical matching device. It will be compared with the current matching device proposed for the ILC, namely the quarter wave transformer. An advantage of the plasma lens is the d…
Mitigation of beam backgrounds via collimators is critical for the success of the Belle~II experiment at the SuperKEKB electron-positron collider. We report on an improved simulation methodology, which includes a refined physical description of the collimators and beam pipe, our first implementation of collimator tip scattering, and in which the existing beam particle tracking software has been embedded into a new sequential tracking framework. These improvements resolve longstanding discrepancies between measured and predicted Belle~II background levels, and significantly reduce the computing…
Positron sources are the key elements for the future and current lepton collider projects such as ILC, CLIC, SuperKEKB, FCC-ee, Muon Collider/LEMMA, etc., introducing challenging critical requirements for high intensity and low emittance beams in order to achieve high luminosity. In fact, due to their large production emittance and constraints given by the target thermal load, the main collider parameters such as the peak and average current, the emittances, the damping time, the repetition frequency and consequently the luminosity are determined by the positron beam characteristics. In this p…
国际直线对撞机（英语：International Linear Collider，ILC）是一个200-500 GeV的高亮度线性电子-正电子对撞机，基于1.3 GHz超导射频（SCRF）加速腔。ILC的总覆盖面积约为31 km，设计的峰值亮度为2 x 10^34 cm^-2 s ^-1。本报告是四卷参考设计报告的执行摘要（第一卷）。它概述了ILC的物理学，加速器设计和价值评估，探测器概念以及项目实现的下一步。
An unprecedented positron average current is required to fit the luminosity demands of future $e^+e^-$ high energy physics colliders. In addition, in order to access precision-frontier physics, these machines require positron polarization to enable exploring the polarization dependence in many HEP processes cross sections, reducing backgrounds and extending the reach of chiral physics studies beyond the standard model. The ILC has a mature plan for the polarized positron source based on conversion in a thin target of circularly polarized gammas generated by passing the main high energy e-beam …
We evaluate the neutron and muon fluxes produced in the ILC beam dumps by Monte Carlo simulations and discuss their potential use in irradiation fields. We show that the beam dumps can provide high-intensity neutron and muon fluxes with spectra quite similar to secondary cosmic rays, which are suitable for soft error studies. The beam dumps deliver neutrons about $10^{11}$ times the secondary cosmic rays on spaces perpendicular to the beam axis and muons $10^8$ times downstream of the beam dumps in the initial phase of the ILC. Large-area irradiation of 1\,m$^2$ or more is possible. Difference…
The current designs of future electron-positron linear colliders incorporate large and complex damping rings to produce asymmetric beams for beamstrahlung suppression. Here we present the design of an electron injector capable of delivering flat electron beams with phase-space partition comparable to the electron-beam parameters produced downstream of the damping ring in the proposed international linear collider (ILC) design. Our design does not employ a damping ring but is instead based on cross-plane phase-space-manipulation techniques. The performance of the proposed configuration, its sen…
