Study of bent monolithic active pixel sensors for the ALICE inner tracking system 3

The ALICE experiment at CERN has planned an upgrade of the Inner Tracking System (ITS), named ITS3, for the LHC Long Shutdown 3, in 2025. The cornerstone of the upgrade is a new CMOS pixel sensor built in 65 nm technology and in bent-cylindrical configuration, replacing the inner layers of the existing detector, the ITS2. The ITS3 will reach much better tracking and vertexing performance, thanks to the improved spatial resolution and the much reduced material budget with respect to the previous Inner Tracking System. The aim of this thesis is to report on the analysis of the data collected at beam tests on new ALPIDE chips (used for ITS2, based on Monolithic Active Pixel Sensor, MAPS) which have been bent in a cylindrical configuration as foreseen for the ITS3. This is the first bending proof of concept for a silicon detector. In particular, data from beam test taken in 2020 have been studied through a data analysis framework that I have personally written to accomplish this task; the complexity of the data analysis is driven by the fact that each ALPIDE chip has a total of 1024x512 pixel MAPS and by the bent geometry of the sensor. In this thesis, the promising performances obtained by studying the sensor total efficiency and spatial resolution in different experimental configurations will be presented and discussed.