Description and performance of track and primary-vertex reconstruction with the CMS tracker
Description and performance of track and primary-vertex reconstruction with the CMS tracker
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DOI：
10.1088/1748-0221/9/10/p10009
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发表时间：
2014-10-01
影响因子：
1.3
通讯作者：
Woods, N.
中科院分区：
文献类型：
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作者：
Chatrchyan, S.;Khachatryan, V.;Woods, N.
描述了为CMS跟踪器开发的软件算法，用于重建质子-质子相互作用中的带电粒子轨迹，并使用所得到的轨迹来估计LHC发光区域和单个主相互作用顶点的位置。尽管在大型强子对撞机的环境非常恶劣，这些算法获得的性能被发现是优秀的。对于2011年典型堆积条件下的t (t) over bar事件，对于横向动量为p(t) > 0.9 gev的瞬时产生的带电粒子，当赝速度为垂直杆eta垂直杆< 0.9时，平均轨道重建效率为94%，当伪速度为0.9 <垂直杆eta垂直杆< 2.5时，平均轨道重建效率为85%。低效率主要是由于强子在跟踪材料中发生核相互作用造成的。对于孤立的μ子，相应的效率基本上是100%。在垂直杆eta垂直杆< 1.4处发射的p(T) = 100GeV的孤立μ子，在p(T)上的分辨率约为2.8%，在横向和纵向撞击参数上分别为10 μ m m和30 μ m m。在三个空间维度上，对应于感兴趣的pp碰撞的重建初级顶点的位置分辨率为10-12 μ m。跟踪和顶点化软件快速灵活，并且很容易适应其他功能，例如触发器的快速跟踪，或考虑到轫致辐射的电子的专用跟踪。
A description is provided of the software algorithms developed for the CMS tracker both for reconstructing charged-particle trajectories in proton-proton interactions and for using the resulting tracks to estimate the positions of the LHC luminous region and individual primary-interaction vertices. Despite the very hostile environment at the LHC, the performance obtained with these algorithms is found to be excellent. For t (t) over bar events under typical 2011 pileup conditions, the average track-reconstruction efficiency for promptly-produced charged particles with transverse momenta of p(T) > 0.9GeV is 94% for pseudorapidities of vertical bar eta vertical bar < 0.9 and 85% for 0.9 < vertical bar eta vertical bar < 2.5. The inefficiency is caused mainly by hadrons that undergo nuclear interactions in the tracker material. For isolated muons, the corresponding efficiencies are essentially 100%. For isolated muons of p(T) = 100GeV emitted at vertical bar eta vertical bar < 1.4, the resolutions are approximately 2.8% in p(T), and respectively, 10 m m and 30 mu m in the transverse and longitudinal impact parameters. The position resolution achieved for reconstructed primary vertices that correspond to interesting pp collisions is 10-12 mu m in each of the three spatial dimensions. The tracking and vertexing software is fast and flexible, and easily adaptable to other functions, such as fast tracking for the trigger, or dedicated tracking for electrons that takes into account bremsstrahlung.