Speaker
Description
The ALICE (A Large Ion Collider Experiment) collaboration is gearing up for an upgrade of the Inner Tracking System (ITS2) during the LHC Long Shutdown 3 (2026 - 2028). The upgrade will replace the three innermost layers of ITS2 with a truly cylindrical vertex detector, ITS3. This innovative tracker is composed of a 65 nm CMOS Monolithic Active Pixel Sensor (MAPS) employing stitching technology to produce a large sensor size O(10 x 26 cm$^{2}$). Its ultra-thin thickness, O(20 - 50 $\mu$m), allows flexibility to be bent into a half-cylindrical shape without additional supporting material. Finally, the three layers of the tracker consist of only six silicon sensors and light carbon forms to hold each layer to keep it in shape and location.
This detector configuration of ITS3 can reduce the material budget to 0.07\% X$_{0}$ per layer. As a result, it foresees the tracking performance, in particular at low transverse momentum ($p_{\text{T}} >$ 0.1 GeV/\textit{c}), is improved by a factor of 2 to the current ITS2. The development and validation of the sensor technology are in progress, with the prototype sensors from the first and the second test production runs: Multi-reticle-Layer Run 1 (MLR1) and Engineering Run 1 (ER1). Sensor design and its characteristics fabricated with 65 nm CMOS technology are the main interests in MLR1 prototypes whereas the validation of stitching technology is a crucial task in the R\&D with the ER1 ones.
This talk will introduce the design and structure of ITS3 and discuss extensive R\&D for bent MAPS detectors focusing on the Korean ALICE ITS3 team's activities.
