Speaker
Description
In the LHC Long Shutdown 3, the ALICE experiment at the LHC will upgrade the three innermost layers of its Inner Tracking System (ITS). This next-generation tracking detector will feature wafer-scale, truly cylindrical Monolithic Active Pixel Sensors (MAPS) fabricated using a 65 nm CMOS imaging process. The sensors, thinned to 50 $\mu m$, will be flexible enough to form ultra-lightweight cylindrical layers without stiff mechanical support, achieving an unprecedented material budget of just 0.07 X/X$_0$ per layer. This breakthrough will enhance tracking performance and improve pointing resolution by a factor $\sim$2, particularly for low-momentum particles ($\sim$ 0.1 GeV/$c$).
A key milestone in this development has been the fabrication and characterization of the MOnolithic Stitched Sensors (MOSS) and MOnollithic stitches Sensors with timing (MOST), 27 cm-long stitched CMOS sensors designed to validate the feasibility of wafer-scale integration, on-chip power segmentation timing performance and on chip transmission. Since mid-2023, MOSS chips have undergone extensive testing in laboratory and beam environments. These studies demonstrated a detection efficiency above 99% with a fake-hit rate below the ITS3 requirement of 10$^{-6}$ hits/pixel/trigger.
This presentation will summarize the key results from the MOSS studies, highlighting their impact on the ITS3 upgrade and the advancements in ultra-thin, large-area stitched MAPS sensors. These include improved charge collection, reduced material budget, and seamless curved sensor integration, setting new benchmarks for high-resolution tracking in future collider experiments. Additionally, I will provide a brief overview of the next foundry submission, which will include a set of test structures with improved implantation, aimed at further enhancing charge collection and reducing sensor capacitance.
