Measured and simulated heavy-ion beam loss patterns at the CERN Large Hadron Collider
Measured and simulated heavy-ion beam loss patterns at the CERN Large Hadron Collider
复制标题
在 CERN 大型强子对撞机上测量和模拟的重离子束损失模式
DOI：
10.1016/j.nima.2016.02.050
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发表时间：
2016
影响因子：
1.4
通讯作者：
D. Wollmann
中科院分区：
文献类型：
--
作者：
P. Hermes;R. Bruce;J. Jowett;S. Redaelli;B. S. Ferrando;G. Valentino;D. Wollmann
摘要欧洲核子研究中心的大型强子对撞机（LHC）在束流能量和强度方面推进了新的领域。考虑到高能和强束与敏感机器部件（特别是超导磁体）的组合，LHC配备了准直系统，以提供保护并拦截不受控制的束流损失。束流损失可能导致超导磁体失超，或者在最坏的情况下，损坏硬件。准直系统，这是优化的质子束提供良好的保护，已显示出与重离子束的清洁效率，这是差了高达两个数量级。这种降低的清洁效率的原因是重离子束由于与准直器材料的相互作用而分裂成具有不同质荷比的同位素。为了确保在未来的离子运行中有足够的准直性能，需要对离子准直有详细的理论了解。重离子准直的模拟必须包括Pb 82+ 208离子分裂成几十种新同位素的过程。离子和它们的碎片必须在LHC的磁晶格中被追踪，以确定它们的丢失位置。本文概述了重离子损失模式的描述重要的物理过程。利用ICOSIM [1]、[2]和新开发的STIER（SixTrack with Ion-Equivalent Rigidities）两种工具模拟的损失图与LHC运行期间测量的实验数据进行了比较。比较表明，工具STIER是在更好的协议。
Abstract The Large Hadron Collider (LHC) at CERN pushes forward to new regimes in terms of beam energy and intensity. In view of the combination of very energetic and intense beams together with sensitive machine components, in particular the superconducting magnets, the LHC is equipped with a collimation system to provide protection and intercept uncontrolled beam losses. Beam losses could cause a superconducting magnet to quench, or in the worst case, damage the hardware. The collimation system, which is optimized to provide a good protection with proton beams, has shown a cleaning efficiency with heavy-ion beams which is worse by up to two orders of magnitude. The reason for this reduced cleaning efficiency is the fragmentation of heavy-ion beams into isotopes with a different mass to charge ratios because of the interaction with the collimator material. In order to ensure sufficient collimation performance in future ion runs, a detailed theoretical understanding of ion collimation is needed. The simulation of heavy-ion collimation must include processes in which Pb 82+ 208 ions fragment into dozens of new isotopes. The ions and their fragments must be tracked inside the magnetic lattice of the LHC to determine their loss positions. This paper gives an overview of physical processes important for the description of heavy-ion loss patterns. Loss maps simulated by means of the two tools ICOSIM [1],[2] and the newly developed STIER (SixTrack with Ion-Equivalent Rigidities) are compared with experimental data measured during LHC operation. The comparison shows that the tool STIER is in better agreement.