Contribution to the construction of the silicon pixel trajectometer of the ATLAS experiment for the high luminosity phase of the LHC

The goal of this work is to prepare the internal tracker for future challenging high luminosity working conditions of the HL-LHC. The ultimate goal of ATLAS experiment is the search of the investigation of rare decays and search for signs of new physics beyond standard model. Increasing the luminosity by a factor ten, requires the complete redesign of the inner tracker and replacement with full silicon tracker and its associated readout electronics. Near the collision point, radiation fluence will be extremely high and will cause severe damages to the sensors and associated readout integrated electronics. The challenge is to build a robust internal tracker that will sustain high radiation dose during the entire period of operation time of more five to ten years, without any major loss of performance. To face these predicted hostile working conditions, systematic studies on sensors, modules and front end electronics have been carried and in particular their performance regarding their radiation tolerance is investigated in details. Furthermore a demonstrator has been constructed at CERN and instrumented by barrel and endcap modules to verify and check in detail all the issues related to electrical and mechanical integration. Before installation in the demonstrator, quality control studies based on a series of criterias of modules have been performed; this will be detailled in a section of this manual. Moreover, Xray and proton irradiation campains of sensors and integrated readout circuits have been carried at CERN and CPPM for performance evaluation before and after irradiation. In particular a section will be dedicated to describe the study under several tuning conditions of a specific radiation monitor circuit "Ring Oscillator" embedded in the main readout chip, designed in our laboratory.