At the Large Hadron Collider (LHC), the interplay between a series of effects, including intrabeam scattering (IBS), synchrotron radiation, longitudinal beam manipulations, two beam effects (beam-beam, e-cloud) and machine nonlinearities, can change the population of the core and tails and lead to non-Gaussian beam distributions, at different periods during the beam cycle. By employing generalized distribution functions, it can be demonstrated that the modified non-Gaussian beam profiles have an impact in the beam emittance evolution by itself and thereby to the collider luminosity. This paper focuses on the estimation of beam distribution modification and the resulting rms beam size due to the combined effect of IBS and synchrotron radiation by employing a Monte-Carlo simulation code which is able to track 3D generalized particle distributions (SIRE). The code is first benchmarked over classical semianalytical IBS theories and then compared with measurements from the LHC at injection and collision energies, including projections for the High-Luminosity LHC (HL-LHC) high brightness regime. The impact of the distribution shape on the evolution of the bunch characteristics and machine performance is finally addressed.

中文翻译：

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非高斯光束轮廓对强子对撞机性能的影响

在大型强子对撞机（LHC）上，一系列效应之间的相互作用，包括光束内散射（IBS），同步辐射，纵向光束操纵，两个光束效应（光束，电子云）和机器非线性，都可以改变在波束周期的不同时期，核心和尾部的大量填充会导致非高斯波束分布。通过采用广义分布函数，可以证明，修改后的非高斯光束轮廓本身会影响光束发射率的演变，从而影响对撞机的发光度。本文将重点介绍通过使用能够跟踪3D广义粒子分布（SIRE）的蒙特卡罗模拟代码，对由于IBS和同步加速器辐射的组合效应而导致的光束分布修正的估计以及由此产生的均方根光束大小。该代码首先在经典的半分析IBS理论上进行基准测试，然后与LHC在注入和碰撞能量下的测量结果进行比较，包括针对高亮度LHC（HL-LHC）高亮度方案的预测。最终解决了分布形状对成束特性和机器性能演变的影响。包括针对高亮度LHC（HL-LHC）高亮度方案的预测。最终解决了分布形状对成束特性和机器性能演变的影响。包括针对高亮度LHC（HL-LHC）高亮度方案的预测。最终解决了分布形状对成束特性和机器性能演变的影响。