Speaker
Description
The ALICE Inner Tracking System (ITS2) will be upgraded for LHC Run 4. The upgrade project foresees the replacement of the three innermost layers of the ITS2 with a truly cylindrical vertex detector, the ITS3. This innovative tracker will be composed of three self-supporting layers, each comprising two large-area (O(10×26 cm2)), ultra-thin (20 – 40 µm) and flexible stitched Monolithic Active Pixel silicon Sensors (MAPS). Such MAPS detectors will be fabricated with the 65 nm CMOS imaging process. Multiple test structures were included in the first test production run Multiple Layer Reticle 1 to validate the process. A wide campaign of laboratory and in-beam measurements is ongoing to characterize the prototypes. An excellent performance in terms of detection efficiency (> 99%), spatial resolution (4-5 µm) and response to X-rays was achieved, also for test structures irradiated up to 1×1013 1 MeV neq cm-2 (NIEL) and 10 kGy (TID), thus demonstrating the radiation hardness of the 65 nm CMOS process up to the expected level for the ALICE ITS3 operating environment. The first large-area sensors realized with the stitching technique in the 65 nm CMOS imaging process were included in the second production run Engineering Run 1 and are now under test. In addition to the development and validation of the sensor technology, an extensive R&D is ongoing to validate the functionalities of bent MAPS, for the realization of the ultra-light support structure in carbon foam and for the air-cooling system. This contribution aims to provide an up-to-date overview of the most recent R&D achievements for the ITS3.
