Performance of the ATLAS Resistive Plate Chamber detector and Level-1 muon barrel trigger at √s = 13 TeV

H Li

doi:10.1088/1748-0221/15/11/c11008

Abstract

The ATLAS experiment at the Large Hadron Collider (LHC) utilises a trigger system consisting of a first level (Level-1) trigger based on custom hardware and a higher level trigger based on computer farms. The Level-1 muon trigger system selects muon candidates with six thresholds of transverse momentum and associates them with correct LHC bunch crossings. The Level-1 muon barrel trigger uses Resistive Plate Chamber (RPC) detectors to form trigger decisions in the region of |η | < 1.05. The RPC detectors are arranged in three concentric double layers, for a total of 3700 gas volumes, with a total surface of more than 4000 square meters, operating in a toroidal magnetic field. The performance of the RPC detector system and of the Level-1 muon barrel trigger during the 2018 data-taking period is discussed in this contribution. 60.8 fb−1 out of 62.2 fb−1 of data recorded by the ATLAS detector at LHC are used. Measurements of the RPC detector response and time resolution, obtained using muon candidates produced in LHC collisions, are presented. Trigger performance and efficiency are measured with muons originating from the decay of Z bosons. Finally, studies of the RPC detector response at different high voltage and threshold settings are shown, as a preview of the expected detector performance after the High Luminosity LHC upgrade.

Highlights

The RPC detector response is measured with muons produced in proton-proton collisions
Muon candidates are reconstructed primarily with Monitored Drift Tube (MDT) detectors [1] and the φ coordinate is measured by the RPC
The hit multiplicity in response to a muon passage is shown in Figure 5 (a) for three selections of hits: all hits, in-time hits and signal hits

Summary

Introduction

The RPC detector response is measured with muons produced in proton-proton collisions. One RPC detector, η side view all hits s= 13 TeV, Run 358395, 0.72 fb-1 The RPC panel efficiency is computed as the fraction of muons that generate a hit from the readout panel. Panel efficiencies of the RPC detector calculated using the three hit selection criteria have a difference less than 1%, which illustrates typical good timing performance and efficiency of RPC panels.

Results

Conclusion