国际直线对撞机（International Linear Collider，ILC）是一台质心能量为500~GeV、峰值亮度为$2 \cdot 10^{34}~\mathrm{cm}^{-2}\mathrm{s}^{-1}$的正负电子对撞机。ILC将补充大型强子对撞机，一个质子-质子加速器，并提供精确的测量，这可能有助于解决科学研究前沿的一些基本问题，如质量的起源和新的自然原理的可能存在。线性对撞机团体已经设定了一个目标，即在ILC的光度测量上实现$10^{-4}$的精度。这可以通过建造一个细颗粒量热计来实现，它将测量小角度下的巴巴散射。巴巴截面在理论上是非常精确的，但是巴巴散射事件的速率，这将由光度探测器测量，将受到束-束效应和对撞机固有的能量扩散的影响。电弱辐射效应可以计算到高精度，并通过区分电子和光子在光度量热计中的可观测能量沉积，使用聚类算法，用具有最终状态光子辐射的事件部分检查。为了达到设计目标，需要重新评估量热计的几何参数。这必须以一种普遍的方式进行，以便于今后的修改，由于探测器概念的预期变化，预计需要进行修改。这项工作表明，聚类的方法是可行的，和光度量热计可以被设计为匹配的精度要求的光度测量。
英文摘要：
The International Linear Collider (ILC) is a proposed electron-positron collider with a center-of-mass energy of 500~GeV, and a peak luminosity of $2 \cdot 10^{34}~\mathrm{cm}^{-2}\mathrm{s}^{-1}$. The ILC will complement the Large Hadron Collider, a proton-proton accelerator, and provide precision measurements, which may help in solving some of the fundamental questions at the frontier of scientific research, such as the origin of mass and the possible existence of new principles of nature.
The linear collider community has set a goal to achieve a precision of $10^{-4}$ on the luminosity measurement at the ILC. This may be accomplished by constructing a finely granulated calorimeter, which will measure Bhabha scattering at small angles. The Bhabha cross-section is theoretically known to great precision, yet the rate of Bhabha scattering events, which would be measured by the luminosity detector, will be influenced by beam-beam effects, and by the inherent energy spread of the collider. The electroweak radiative effects can be calculated to high precision and partially checked with events with final state photon radiation by distinguishing between the observable energy deposits of electrons and of photons in the luminosity calorimeter, using a clustering algorithm.
In order to achieve the design goal, the geometrical parameters of the calorimeter need to be reevaluated. This must be done in a generalized manner, so as to facilitate future modifications, the need for which is foreseen, due to expected changes in the detector concept.
This work demonstrates that the clustering approach is viable, and that a luminosity calorimeter may be designed to match the precision requirements on the luminosity measurement.
We develop theoretical expressions for the luminosity and beam-beam tune shifts in the presence of both a crossing angle and hourglass effects for the present and next generation of symmetric e$^+$-e$^-$ colliders. The theory is applied to the design of the Fermilab site filler Higgs factory and to the FCC-ee collider.
With the best of modern standard lasers, high-energy $γγ$ colliders from electron beams of E larger than 250 GeV are only possible at the expense of photon luminosity, i.e. 10 times lower than for photon colliders at c.m. energies below 0.5 TeV. For existing state-of-the art lasers, an optimistic upper energy limit for x=4.8 is an electron beam of less than 250 GeV. This Snowmass21 Contributed Paper shows how Free Electron Lasers (FEL) pave the way for High Energy & High Luminosity $γγ$ colliders. We present and assess a conceptual design study of a FEL with wavelength of 2.4 $μ$m and an x-fac…
In response to a request from the CERN Scientific Policy Committee (SPC), the machine parameters and expected luminosity performance for several proposed post-LHC collider projects at CERN are compiled: three types of hadron colliders (HL-LHC upgrade, FCC-hh and HE-LHC), a circular lepton collider (FCC-ee), a linear lepton collider (CLIC), and three options for lepton-hadron colliders (LHeC, HE-LHeC, and FCC-eh). Particular emphasis is put on availability, physics run time, and efficiency. The information contained in this document was presented at the SPC Meeting of September 2018. It will se…
A large, world-wide community of physicists is working to realise an exceptional physics program of energy-frontier, electron-positron collisions with the International Linear Collider (ILC). This program will begin with a central focus on high-precision and model-independent measurements of the Higgs boson couplings. This method of searching for new physics beyond the Standard Model is orthogonal to and complements the LHC physics program. The ILC at 250 GeV will also search for direct new physics in exotic Higgs decays and in pair-production of weakly interacting particles. Polarised electro…
A precise determination of absolute luminosity, using the bremsstrahlung process, at the future Electron-Ion Collider (EIC) will be very demanding, and its three major challenges are discussed herein. First, the bremsstrahlung rate suppression due to the so-called beam size effect has to be well controlled. Secondly, the impact of huge synchrotron radiation fluxes should be mitigated. Thirdly, enormous bremsstrahlung event rates, in excess of 10 GHz, have to be coped with. A basic layout of the luminosity measurement setup at the EIC, addressing these issues, is proposed, including preliminary…
The International Linear Collider (ILC) being proposed in Japan is an electron-positron linear collider with an initial energy of 250 GeV. The ILC accelerator is based on the technology of superconducting radio-frequency cavities. This technology has reached a mature stage in the European XFEL project and is now widely used. The ILC will start by measuring the Higgs properties, providing high-precision and model-independent determinations of its parameters. The ILC at 250 GeV will also search for direct new physics in exotic Higgs decays and in pair-production of weakly interacting particles. …
The International Linear Collider (ILC) is now under consideration as the next global project in particle physics. In this report, we review of all aspects of the ILC program: the physics motivation, the accelerator design, the run plan, the proposed detectors, the experimental measurements on the Higgs boson, the top quark, the couplings of the W and Z bosons, and searches for new particles. We review the important role that polarized beams play in the ILC program. The first stage of the ILC is planned to be a Higgs factory at 250 GeV in the centre of mass. Energy upgrades can naturally be im…
This document provides detailed information on the status of Advanced and Novel Accelerators techniques and describes the steps that need to be envisaged for their implementation in future accelerators, in particular for high energy physics applications. It complements the overview prepared for the update of the European Strategy for particle physics, and provides a detailed description of the field. The scientific priorities of the community are described for each technique of acceleration able to achieve accelerating gradient in the GeV~range or above. ALEGRO working group leaders have coord…
A high-resolution, intratrain position feedback system has been developed to achieve and maintain collisions at the proposed future electron-positron International Linear Collider (ILC). A prototype has been commissioned and tested with a beam in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization in Japan. It consists of a stripline beam position monitor (BPM) with analogue signal-processing electronics, a custom digital board to perform the feedback calculation, and a stripline kicker driven by a high-current amplifier. The closed-loop fe…
A linear electron-positron collider operating at TeV scale energies will provide high precision measurements and allow, for example, precision studies of the Higgs boson as well as searches for physics beyond the standard model. A future linear collider should produce collisions at high energy, with high luminosity and with a good wall plug to beam power transfer efficiency. The luminosity per power consumed is a key metric that can be used to compare linear collider concepts. The plasma wakefield accelerator has demonstrated high-gradient, high-efficiency acceleration of an electron beam, and…
Construction of future Muon Collider tangential to the Large Hadron Collider will give opportunity to realize mu-p collisions at multi-TeV center of mass energies. Using nominal parameters of high luminosity and high energy upgrades of the LHC, as well as design parameters of muon colliders, it is shown that L_mu-p of order of 10^33 cm^-2s^-1 is achievable for different options with sqrt(s)_mu-p from 4.58 TeV to 12.7 TeV. Certainly, proposed mu-p colliders have a huge potential for clarifying QCD basics and searches for new physics.
This note outline the formulae of luminosity and beam-beam tune shifts applicable to flat-beam asymmetric colliders. The formulae are tested with the machine parameters of SuperKEKB.
The Compact Linear Collider is one of the two main European options for a collider in a post Large Hadron Collider era. This is a linear $e^+e^-$ collider with three centre-of-mass energy stages: 380 GeV, 1.5 TeV and 3 TeV. The luminosity performance of the first stage at 380 GeV is presented including the impact of static and dynamic imperfections. These calculations are performed with fully realistic tracking simulations from the exit of the damping rings to the interaction point and including beam-beam effects in the collisions. A luminosity of $4.3\times10^{34}\,\text{cm}^{-2}\text{s}^{-1}…
The Standing Wave (SW) TESLA niobium-based superconducting radio frequency structure is limited to an accelerating gradient of about 50 MV/m by the critical RF magnetic field. To break through this barrier, we explore the option of niobium-based traveling wave (TW) structures. Optimization of TW structures was done considering experimentally known limiting electric and magnetic fields. It is shown that a TW structure can have an accelerating gradient above 70 MeV/m that is about 1.5 times higher than contemporary standing wave structures with the same critical magnetic field. The other benefit…
A formula for the collider luminosity is derived for a head-on collision of two beams with different parameters. Three particular cases are presented: the collision of two identical axially symmetric bunches, the collision of a bunch with a coasting beam, and the collision of two coasting beams. The colliding beams have coinciding longitudinal axes. The formula is valid for colliding both counter propagating and co-propagating ("merging") beams.
A good understanding of the luminosity performance in a collider, as well as reliable tools to analyse, predict, and optimise the performance, are of great importance for the successful planning and execution of future runs. In this article, we present two different models for the evolution of the beam parameters and the luminosity in heavy-ion colliders. The first, Collider Time Evolution (CTE) is a particle tracking code, while the second, the Multi-Bunch Simulation (MBS), is based on the numerical solution of ordinary differential equations for beam parameters. As a benchmark, we compare si…
