First bent wafer-scale sensor in truly-cylindrical geometry for the ALICE ITS3 detector

Abstract

An upgrade of the three innermost layers of the ALICE ITS, intended to be installed during the LHC Long Shutdown 3, is under development. The detector concept foresees the usage of curved, wafer-scale Monolithic Active Pixel Sensors. Extensive characterization studies of bent single ALPIDE chips (used for the current ITS), have been carried out to evaluate their performance under the mechanical stress involved in the bending process. These tests on small sensors have opened the way to the investigation of a large scale sensor: a full size demonstrator of a half-layer in a truly cylindrical shape based on so called super-ALPIDE chips. Such activity has required the development of special tools and procedures dedicated to bend and read out the new pixel matrix.