Speaker
Description
The ALICE experiment at the Large Hadron Collider (LHC) currently uses the Inner Tracking System 2 (ITS2) for tracking during LHC Run 3. ITS2 is based on Monolithic Active Pixel Sensor (MAPS) technology, known as ALPIDE (ALICE Pixel Detector). During Long Shutdown 3 (LS3), scheduled for 2026–2030, the innermost three layers of ITS2 will be replaced by ITS3. The ITS3 upgrade relies on wafer-scale stitching, which enables sensors substantially larger than previous generations. Thinning these wafer-scale sensors to 50 μm allows them to be bent into a truly cylindrical structure. The first prototype built on this stitched-sensor technology is the Monolithic Stitched Sensor (MOSS), consisting of ten Repeated Sensor Units (RSUs). Each RSU is divided into top and bottom half-units fabricated with different pixel pitches, 18.0 μm and 22.5 μm, respectively, to study the impact of pixel density on performance. To evaluate sensor performance under realistic conditions, beam telescopes are used, comprising reference sensors for tracking, a scintillator for triggering, and a babyMOSS sensor as the Device Under Test (DUT). This setup extends the scope of sensor qualification beyond lab-based characterisation. This talk presents the design, implementation, and results of ITS3 beam tests carried out with beam telescopes, with emphasis on their relevance to the ongoing development of the ALICE ITS3 upgrade.
