The silicon strip detector of the ATLAS Inner Tracker: from individual sensing units to multi-module petal structures

Nowadays particle detector technology is taking big steps forwards and new devices dedicated to particle physics show very high performance. Particularly the semi-conductor detectors have advanced significantly and are used for tracking purposes in the A Toroidal LHC ApparatuS (ATLAS) experiment at CERN thanks to their excellent spacial resolution: the compact size of the silicon and its high granularity allow to reach a precision measurement of few tens of microns. This thesis is focused on the upgrade of the ATLAS tracking detector required for the High Luminosity Large Hadron Collider (HL-LHC), starting in 2027. The HL-LHC foresees an integrated luminosity of L = 3000 fb −1 , which comes with an unprecedented rate of proton collisions, with a pile-up of 200, and very high radiation doses. As the current inner detector has not been designed for the HL-LHC environmental conditions, an all-silicon Inner Tracker (ITk) will take its place during Phase-II upgrade of the ATLAS experiment. The ITk strip endcap sub-detector is the main topic of this PhD project. The investigation covers the assembly of silicon strip endcap modules and their loading on a local support structure. The building and loading procedures are presented as well as results of quality control (QC) tests carried out on prototyping components to establish their working performance and the fulfillment of the specifications. This work provides the procedure optimization in order to achieve the requirements imposed by the collaboration. Results on prototyping components, such as a fully electrical module and a semi-electrical petal, both built and tested at DESY, are presented. They are followed by tests on an electrical petal performed at low temperature with the evaporative CO2 cooling technique. The QC tests carried out on all prototypes have demonstrated that they have been properly assembled and are fully functional. Moreover they fulfill the respective requirements validating therefore the components design and the building methods.