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arXiv 1909.00761hep-ex
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LHC运行2期间ATLAS中电子和光子触发的性能

Performance of electron and photon triggers in ATLAS during LHC Run 2

ATLAS Collaboration

摘要:

电子和光子触发器涵盖了从5 GeV到几TeV的横向能量,对于ATLAS实验记录各种物理学的信号至关重要:从标准模型过程到质子-质子和重离子碰撞中的新现象。为了应对从2015年到2018年(运行2)峰值LHC亮度增加四倍,达到2.1 $\times$ 10 $^{34}$ cm $^{-2}$ s $^{-1}$,以及每个光束交叉的相互作用数量增加到大约60,触发算法和选择被优化以控制速率,同时保持物理分析的高效率。对于质子-质子碰撞,对于31 GeV的离线电子,相对于单电子离线选择的单电子触发效率至少为75%,并且在60 GeV时上升到96%;对于30 GeV的离线光子,相对于紧密离线光子选择的初级双光子触发器的25 GeV腿的触发效率超过96%。对于重离子碰撞,初级电子和光子触发效率相对于相应的标准离线选择,分别为至少84%和95%,在5 GeV以上的相应的触发阈值。

英文摘要:

Electron and photon triggers covering transverse energies from 5 GeV to several TeV are essential for the ATLAS experiment to record signals for a wide variety of physics: from Standard Model processes to searches for new phenomena in both proton-proton and heavy-ion collisions. To cope with a fourfold increase of peak LHC luminosity from 2015 to 2018 (Run 2), to 2.1$\times$10$^{34}$cm$^{-2}$s$^{-1}$, and a similar increase in the number of interactions per beam-crossing to about 60, trigger algorithms and selections were optimised to control the rates while retaining a high efficiency for physics analyses. For proton-proton collisions, the single-electron trigger efficiency relative to a single-electron offline selection is at least 75% for an offline electron of 31 GeV, and rises to 96% at 60 GeV; the trigger efficiency of a 25 GeV leg of the primary diphoton trigger relative to a tight offline photon selection is more than 96% for an offline photon of 30 GeV. For heavy-ion collisions, the primary electron and photon trigger efficiencies relative to the corresponding standard offline selections are at least 84% and 95%, respectively, at 5 GeV above the corresponding trigger threshold.

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