Paper detail

Upgrading the Inner Tracking System and the Time Projection Chamber of ALICE

The ALICE experiment at CERN is undergoing a major upgrade during the Long Shutdown 2 (LS2) of the LHC during 2019-2020. The key elements regarding the central barrel are the installation of a new Inner Tracking System (ITS) and the upgrade of the large Time Projection Chamber (TPC). The TPC is currently being upgraded with a new readout system, including new GEM-based Readout Chambers and new front-end electronics enabling us to operate it in continuous mode. The new ITS based on CMOS Monolithic Active Pixel Sensors will significantly improve the impact parameter resolution and the tracking efficiency, especially for particles with low transverse momenta, as well as the readout-rate capability. In the following, the upgrades and their assembly and commissioning status will be outlined. Furthermore, an outlook will be given on plans for the upgrade of the ITS foreseen for the third long shutdown of the LHC in 2025-2026. For this upgrade, the three innermost layers could be replaced by cylindrical detector layers, made of curved wafer-scale-sized CMOS sensors, to lower even further the material budget and to improve the pointing resolution.