15 years young: The ALICE TOF detector in the LHC Run 3

Abstract

The ALICE Time Of Flight (TOF) detector consists of 1593 Multigap Resistive Plate Chambers (MRPCs) operating with a mixture of Freon (93%) and SF${}_6$ (7%), covering a total active area of about 140 m${}^2$ and accounting for more than 150,000 readout channels. During the latest LHC shutdown, the detector underwent a major upgrade of its readout, allowing for continuous data taking and, therefore, fully exploiting the increased luminosity provided by the LHC in Pb–Pb collisions. Thanks to a time resolution of 68 ps, the ALICE TOF detector provides a crucial tool for identifying charged particles produced at intermediate momenta in high energy pp, pA, and AA collisions at the LHC. This feature is fundamental in high-energy nuclear physics as it allows for basic measurements of the identified particle production, which is used to characterize the Quark Gluon Plasma created in heavy-ion collisions.

After 15 years of operations, the detector performance remains excellent, with no degradation in the stability of operation or in the efficiency of particle detection. The detector performance is presented in the paper, also in terms of operations and stability. The calibration procedures of the detector in the continuous readout scheme are discussed, along with the implications for particle identification. A few PID examples in physics analysis will also be described.