Speaker
Description
The ALICE experiment will install the Inner Tracking System 3 (ITS3) during LHC Long Shutdown 3 (2026–2030), replacing the three innermost ITS2 layers with the first fully cylindrical, wafer-scale silicon vertex detector. ITS3 employs Monolithic Active Pixel Sensors (MAPS) fabricated in a 65 nm CMOS process, thinned to 50 µm and bent to radii of 19, 25, and 32 mm. Wafer-scale stitching enables 27 cm-long seamless sensors, with integrated power and signal distribution that eliminates flexible printed circuits over the sensors and drastically reduces passive material. Bending allows for self-supporting layers of the ultra-thin sensors without the need for heavy support structures, while maintaining >99 % detection efficiency and ~5 µm spatial resolution even after bending. Carbon-foam supports with air cooling replace traditional integration methods, further reducing the material budget to less than 0.09% X₀ per-layer .
The ITS3 sensor R&D program has been validated through laboratory characterisation and in-beam measurements of prototype pixel matrices. Early devices (MOSS, MOST) demonstrated stitching feasibility, large-scale yield, and radiation tolerance under TID and NIEL. Development has advanced toward the final integrated ITS3 sensor prototype (MOSAIX), supported by full-scale engineering models that verified the integration and cooling concept for the nominal 40 mW/cm² power dissipation, achieving <1 µm vibration with 8 m/s airflow.
This contribution will summarise ITS3’s key R&D advances in stitched sensor development, thinning, bending, radiation hardness, mechanical integration, and air-cooling through engineering models to the final qualification model.
| Position | Postdoc |
|---|---|
| Affiliation | Sejong University |
| Country | South Korea |
