The construction of the Insertable B-Layer and the $b$-tagging performance at high-\pt of the ATLAS experiment

Although the recent discovery of the Higgs boson by the LHC experiments represented a major success of the Standard Model theory, several questions need still to be answered. The search of new physics particles beyond the Standard Model will require the LHC to collect a large amount of data. To achieve this goal the LHC collider went through a long shutdown, increasing both the energy and the luminosity. In particular the increase of luminosity will require the ATLAS Inner Detector to operate in a more track-dense environment, which mainly affects the ATLAS Pixel Detector. In order to cope with the high pile-up expected with the increase of luminosity the Pixel detector was then upgraded during the long shutdown with the insertion of a fourth innermost layer, the Insertable B-Layer (IBL). This thesis focuses on the construction of the IBL. This includes the loading of silicon pixel detector modules on the support staves, the quality assurance of these instrumented staves and the commissioning after the integration around the support structure. The energy upgrade of the LHC will increase the sensitivity to new particles with high mass, whose decay can produce $b$-quarks with a very high transverse momentum. An optimization of the impact parameters ($d_0$ and $z_0$) of the ATLAS $b$-tagging algorithm is presented in the last Chapter of this thesis.