Performance of the ATLAS RPC detector and Level-1 muon barrel trigger at √(s)=13 TeV

Abstract

Large Hadron Collider (LHC) employs a trigger system consisting of a first-level hardware trigger (L1) and a software-based high-level trigger. The L1 muon trigger system selects muon candidates, assigns them to the correct LHC bunch crossing and classifies them into one of six transverse-momentum threshold classes. The L1 muon trigger system uses resistive-plate chambers (RPCs) to generate the muon-induced trigger signals in the central (barrel) region of the ATLAS detector. The ATLAS RPCs are arranged in six concentric layers and operate in a toroidal magnetic field with a bending power of 1.5 to 5.5 Tm. The RPC detector consists of about 3700 gas volumes with a total surface area of more than 4000 m 2 . This paper reports on the performance of the RPC detector and L1 muon barrel trigger using 60.8 fb −1 of proton-proton collision data recorded by the ATLAS experiment in 2018 at a centre-of-mass energy of 13 TeV. Detector and trigger performance are studied using boson decays into a muon pair. Measurements of the RPC detector response, efficiency, and time resolution are reported. Measurements of the L1 muon barrel trigger efficiencies and rates are presented, along with measurements of the properties of the selected sample of muon candidates. Measurements of the RPC currents, counting rates and mean avalanche charge are performed using zero-bias collisions. Finally, RPC detector response and efficiency are studied at different high voltage and front-end discriminator threshold settings in order to extrapolate detector response to the higher luminosity expected for the High Luminosity LHC.

Producing and detecting long-lived particles at different experiments at the LHC

“…For muons which pass directional and kinetic cuts, the trigger efficiency is taken as ∼100%. The current typical L1 muon trigger efficiency is around 80% for barrel and close to 100% for endcap [32]. Taking into account the similarity of our LLP signal trigger strategies JHEP02(2022)069 and current ATLAS L1 muon trigger, our LLP signal trigger efficiency hopefully will reach a similar order: the exact trigger efficiency however needs further detector simulation.…”

Performance of the ATLAS RPC detector and L1 Muon Barrel trigger at 13 TeV

“…The barrel region of the Muon Spectrometer (MS) of the ATLAS experiment [1] at the Large Hadron Collider (LHC) covers a pseudo-rapidity range up to | | < 1.05 and it employs Resistive Plate Chambers (RPCs) [2] for triggering events containing muons.…”

“…• the high-T trigger requires an additional confirmation on the third external station (RPC3) and selects muons with T above the thresholds of 10 GeV (called MU11, to be distinguished from MU10) and 20 GeV (MU20). A third high-T threshold, MU21, is defined in such a way the muon transverse momentum requirement is the same of MU20 but the trigger signals from some RPC chambers, located in sectors 12 and 14 (two small sectors located in the bottom region of the ATLAS detector), are not taken into account [2].…”

Development of a resource-efficient FPGA-based neural network regression model for the ATLAS muon trigger upgrades

“…These FPGA-based networks will be used to improve performance of standard muon trigger algorithms and to search for new exotic particles. For example, a new trigger can be developed to search for slow-moving heavy charged particles using the resistive plate chamber (RPC) detector [20] for time-of-flight measurements [21]. Deploying such triggers for analysing collision data will improve sensitivity of the LHC experiments for detecting new long-lived particles that are predicted by well-motivated extensions of the standard model (e.g., Refs.…”