Commissioning of the new ALICE Inner Tracking System

Abstract

The upgrade of the Inner Tracking System (ITS) of ALICE (A Large Ion Collider Experiment) will extend measurements of heavy-flavour hadrons and low-mass dileptons to a lower transverse momentum than currently achieved and increase the readout capabilities to incorporate the full interaction. Furthermore, the tracking efficiency will be improved at low transverse momentum. To achieve this, the new ALICE ITS is comprised of seven layers of a custom Monolithic Active Pixel Sensor design known as ALPIDE, with a spatial resolution of 5 μm. The use of the ALPIDE-based detector design will reduce the material budget to 0.35% X0 per layer for the innermost three layers, and to 1.0% X0 per layer for the outermost four layers, compared to 1.14% X0 per layer in the previous ITS. The construction effort in numerous sites around the world has resulted in a fully assembled and connected detector, which is currently undergoing on surface commissioning before its installation in the ALICE cavern. This contribution discusses the design and the current status of the commissioning of the new ITS detector, including the methods used to characterise the detector and the results obtained so far.