Caratterizzazione di MAPS a risposta veloce per l'ITS3 di ALICE

Monolithic Active Pixel Sensors are silicon detectors based on the same produc- tion processes of CMOS imaging sensors commonly found on most digital cameras: they include readout electronics in the sensor itself making them the most effective solution for particle tracking for material budget and cost. ALICE has pioneered their use in High Energy Physics with the ALPIDE sensor used in the ITS2 (Inner Tracking System 2), its current vertex detector that offers unprecedented performance in tracking resolution and efficiency. However the rapid progress of CMOS imaging sensors technology, still offers ample possibilities for improvement to MAPS: a new generation of ultra thin, flexible and large sensors is under development for the next generation of ALICE ITS. The ITS3 will be made of three layers of curved wafer-size Monolithic Active Pixel Sensors, with a Layer 0 radius of 18mm compared to the 23 of the current design. Development of large area MAPS is made possible thanks to stitching, a technique that is made available to the designers by switching to the 65nm TPSCo processing node. Stitching allows to include in the silicon sensor design all the lines neces- sary for powering and data transfer removing the need of an external FPC (flex printed circuit). The targeted low power budget of 20mW/cm2 will allow to use airflow to remove the heat dissipated by the sensor in place of a traditional water cooling system. The silicon will be self sustained, fixed at the edges by carbon foam ribs that double up as heat exchanger for the sensor end-cap circuitry. All together, these solutions will grant a drastic reduction in the material budget in the detector acceptance from 0.36% of the ITS2 to 0.05%, greatly improving the tracking performance at the lowest transverse momenta. My thesis dissertation collects and describes the first results of the R&D work in which I participated in order to characterize the first batch of the sensor test structures named MLR1 (Multi Layer Reticule), in particular to the Analogue Pixel Test Structure with an Opamp as output buffer (APTS-Opamp).