Evaluation of efficiency, radiation hardness, and timing performance of the Analogue Pixel Test Structure for ALICE ITS3

Abstract A replacement of the three innermost layers of the new ALICE Inner Tracking System (ITS2), referred to as ITS3, is planned for the LHC Long Shutdown 3 (2026–2028) to further enhance tracking precision and efficiency. The ITS3 is designed as a cylindrically bent silicon vertex detector, utilizing stitched, wafer-scale sensors developed with the Tower Partners Semiconductor Co. 65 nm technology. The feasibility of this technology for ITS3 was evaluated using prototypes fabricated in the initial multi-reticle-layer run. This contribution presents the latest sensor characterization results from the analogue pixel test structures, focusing on detection efficiency, timing response, and radiation hardness.