Upgrade of the ATLAS Muon Trigger for the SLHC
Upgrade of the ATLAS Muon Trigger for the SLHC
复制标题
SLHC 的 ATLAS Muon 触发器升级
DOI：
10.1088/1748-0221/5/12/c12016
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发表时间：
2010
影响因子：
1.3
通讯作者：
R. Richter
中科院分区：
文献类型：
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作者：
J. Dubbert;S. Horvat;O. Kortner;H. Kroha;R. Richter
大型强子对撞机ATLAS实验的外壳由一个环形空芯磁体系统组成，以便精确测量μ子的横向动量（pT），这在许多物理通道中是有趣的物理过程的标志[1,2]。为了精确测定μ子动量，采用了位置精度高的监测漂移管室（MDT），而快速识别μ子轨迹采用了时间分辨率高的室，能够选择超过预定义pT阈值的μ子用于ATLAS触发系统的第一级（1级触发）。当大型强子对撞机1034 cm−2s−1的峰值亮度在大约十年后将增加4-5倍时（“SLHC”），ATLAS 1级触发系统的选择性将被强制提高，以应对100 kHz的最大允许触发率。对于ATLAS μ子谱仪的一级触发，这意味着单个μ子的pT阈值的增加。然而，由于触发室的空间分辨率有限，对~ 20 GeV/c以上的磁道的选择性不足以有效降低一级速率。我们描述了如何利用MDT精密室测量的轨迹坐标来决定性地提高高动量轨迹的选择性。我们还将讨论由此导致的延迟增加。
The outer shell of the ATLAS experiment at the LHC consists of a system of toroidal air-core magnets in order to allow for the precise measurement of the transverse momentum (pT) of muons, which in many physics channels are a signature of interesting physics processes [1,2]. For the precise determination of the muon momentum Monitored Drift Tube chambers (MDT) with high position accuracy are used, while for the fast identification of muon tracks chambers with high time resolution are used, able to select muons above a predefined pT threshold for use in the first Level of the ATLAS triggering system (Level-1 trigger). When the LHC peak luminosity of 1034 cm−2s−1 will be increased by a factor of 4–5 in about a decade from now (''SLHC''), an improvement of the selectivity of the ATLAS Level-1 triggering system will be mandatory in order to cope with the maximum allowed trigger rate of 100 kHz. For the Level-1 trigger of the ATLAS muon spectrometer this means an increase of the pT threshold for single muons. Due to the limited spatial resolution of the trigger chambers, however, the selectivity for tracks above ~ 20 GeV/c is insufficient for an effective reduction of the Level-1 rate. We describe how the track coordinates measured in the MDT precision chambers can be used to decisively improve the selectivity for high momentum tracks. The resulting increase in latency will also be discussed.