ALICE has been conceived and constructed as a heavy-ion experiment at the CERN Large Hadron Collider (LHC). During LHC Runs 1 and 2, ALICE produced a wide range of physics results using all collision systems available at the collider. In order to best exploit new physics opportunities opening up with the upgraded LHC and new detector technologies, the experiment has undergone a significant upgrade during the LHC Long Shutdown 2 (2019–2022). This comprises the move to the continuous readout, the complete overhaul of core detectors, and a new online event processing farm with a redesigned online-offline software framework. These improvements will allow ALICE to record Pb–Pb collisions at rates up to 50 kHz, while ensuring sensitivity for signals without a triggerable signature. The major upgrade of the experiment has now been documented in an extensive technical publication, which will be part of a special issue of the Journal of Instrumentation on the LS2 upgrades of the LHC machine and experiments.
ALICE Collaboration, arXiv:2302.01238