Operation and performance of the ALICE Muon IDentifier RPCs during LHC Run3

ALICE (A Large Ion Collider Experiment) investigates quark–gluon plasma (QGP) in ultrarelativistic heavy-ion collisions at the LHC. A key observable for QGP studies is heavy-quark hadron production in Pb–Pb collisions, detected via their muonic decays using a forward muon spectrometer (MS). During LHC Runs 1 and 2, a muon trigger system based on Resistive Plate Chambers (RPCs) was used. Since the start of Run 3, ALICE is working in continuous readout (triggerless) mode, and the muon trigger system was replaced by the Muon Identifier (MID). To mitigate aging and enhance RPC rate capability, the working voltage was reduced while maintaining the same gas mixture, alongside upgraded front-end and readout electronics. This paper assesses the stability and performance of MID RPCs over the first 2.5 years of Run 3 at unprecedented collision energies.