Development of a Highly Selective First-Level Muon Trigger for ATLAS at HL-LHC Exploiting Precision Muon Drift-Tube Data

TL;DR

This paper presents a novel first-level muon trigger for the ATLAS experiment at HL-LHC, utilizing precision Muon Drift-Tube data to improve selectivity and reduce trigger rates under high luminosity conditions.

Contribution

It introduces a new trigger concept that exploits MDT data for fast, precise muon track reconstruction, with hardware demonstration at CERN.

Findings

Significant reduction in muon trigger rate achieved

Successful hardware demonstration with testbeam data

Enhanced momentum resolution for first-level muon triggers

Abstract

The High-Luminosity LHC (HL-LHC) will provide the unique opportunity to explore the nature of physics beyond the Standard Model of strong and electroweak interactions. Highly selective first-level triggers are essential for the physics programme of the ATLAS experiment at HL-LHC, where the instantaneous luminosity will exceed the instantaneous LHC Run 1 luminosity by about an order of magnitude. The ATLAS first-level muon trigger rate is dominated by low momentum muons, which are accepted because of the moderate momentum resolution of the RPC and TGC trigger chambers. This limitation can be overcome by exploiting the data of the precision Muon Drift-Tube (MDT) chambers in the first-level trigger decision. This requires continuous fast transfer of the MDT hits to the off-detector trigger logic and fast track reconstruction algorithms. The reduction of the muon trigger rate achievable with the proposed new trigger concept, the performance of a novel fast track reconstruction algorithm, and the first hardware demonstration of the scheme with muon testbeam data taken at the CERN Gamma Irradiation Facility are discussed.