Performance of the ATLAS Trigger System

The ATLAS Trigger System reduces the event rate from the bunch-crossing rate of 40 MHz to an average recording rate of 200 Hz by selecting primarily high-p(T) events. The ATLAS Trigger is composed of three levels. The first level (L1) is implemented in custom-built electronics, the two-stage High Level Trigger (HLT) is implemented in software executed on large computing farms. The L1 consists of calorimeter, muon and forward triggers to identify electron, photon, jet and muon candidates, as well as event features such as missing transverse energy. These inputs are used by the L1 Central Trigger to generate an L1 Accept (L1A) decision. L1A and timing information is sent to all sub-detectors and summary information is sent to the subsequent levels of the Trigger System. In this paper the performance of the ATLAS Trigger System in 2010 and 2011 is presented.


Performance of the CMS Level-1 trigger during commissioning with cosmic ray muons and LHC beams
Chatrchyan, S.; et. al. (IOP Publishing, 2010-03-01)
The CMS Level-1 trigger was used to select cosmic ray muons and LHC beam events during data-taking runs in 2008, and to estimate the level of detector noise. This paper describes the trigger components used, the algorithms that were executed, and the trigger synchronisation. Using data from extended cosmic ray runs, the muon, electron/photon, and jet triggers have been validated, and their performance evaluated. Efficiencies were found to be high, resolutions were found to be good, and rates as expected.
Performance of the CMS drift-tube chamber local trigger with cosmic rays
Chatrchyan, S.; et. al. (IOP Publishing, 2010-03-01)
The performance of the Local Trigger based on the drift-tube system of the CMS experiment has been studied using muons from cosmic ray events collected during the commissioning of the detector in 2008. The properties of the system are extensively tested and compared with the simulation. The effect of the random arrival time of the cosmic rays on the trigger performance is reported, and the results are compared with the design expectations for proton-proton collisions and with previous measurements obtained ...
Performance of the CMS drift tube chambers with cosmic rays
Chatrchyan, S.; et. al. (IOP Publishing, 2010-03-01)
Studies of the performance of the CMS drift tube barrel muon system are described, with results based on data collected during the CMS Cosmic Run at Four Tesla. For most of these data, the solenoidal magnet was operated with a central field of 3.8 T. The analysis of data from 246 out of a total of 250 chambers indicates a very good muon reconstruction capability, with a coordinate resolution for a single hit of about 260 mu m, and a nearly 100% efficiency for the drift tube cells. The resolution of the trac...
Energy calibration and resolution of the CMS electromagnetic calorimeter in pp collisions at root s=7 TeV
Chatrchyan, S.; et. al. (IOP Publishing, 2013-09-01)
The energy calibration and resolution of the electromagnetic calorimeter (ECAL) of the CMS detector have been determined using proton-proton collision data from LHC operation in 2010 and 2011 at a centre-of-mass energy of root s = 7 TeV with integrated luminosities of about 5 fb(-1). Crucial aspects of detector operation, such as the environmental stability, alignment, and synchronozation, are presented. The in-situ calibration procedures are discussed in detail and include the maintenance of the calibratio...
Performance of electron reconstruction and selection with the CMS detector in proton-proton collisions at root s=8 TeV
Khachatryan, V.; et. al. (IOP Publishing, 2015-06-01)
The performance and strategies used in electron reconstruction and selection at CMS are presented based on data corresponding to an integrated luminosity of 19.7 fb(-1), collected in proton-proton collisions at root s = 8TeV at the CERN LHC. The paper focuses on prompt isolated electrons with transverse momenta ranging from about 5 to a few 100 GeV. A detailed description is given of the algorithms used to cluster energy in the electromagnetic calorimeter and to reconstruct electron trajectories in the trac...
Citation Formats
M. B. Demirköz, “Performance of the ATLAS Trigger System,” JOURNAL OF INSTRUMENTATION, pp. 0–0, 2012, Accessed: 00, 2020. [Online]. Available: