Performance of the LHCb muon detector in Run 3

TL;DR

The LHCb muon detector was upgraded and operated successfully in Run 3, achieving high efficiency and low misidentification rates despite increased luminosity and particle rates.

Contribution

This paper reports on the hardware upgrades, improved algorithms, and performance evaluation of the LHCb muon detector during Run 3.

Findings

Muon detection efficiency above 90% achieved.

Sub-percent hadron misidentification probability.

Successful operation and calibration at higher luminosity.

Abstract

In Run 3 of the LHC, the instantaneous luminosity at the LHCb interaction point has been increased by a factor of five, from $4\times 10^{32}\rm{cm}^{-2}\rm{s}^{-1}$ to $2\times 10^{33}\rm{cm}^{-2}\rm{s}^{-1}$. Several hardware interventions, including a complete overhaul of the readout electronics, have been carried out on the muon detector. The muon identification algorithms in the software trigger were improved with the aim of ensuring Run 2 performance under a higher particle rate. The operation and calibration of the upgraded muon detector are presented. The muon detection efficiency and muon identification performance are evaluated on data calibration samples collected during the year 2024. A muon identification efficiency above 90\% with sub-percent hadron misidentification probability is achieved by exploiting the pattern of hits in the muon detector.