Phase-II upgrade of the ATLAS Pixel Detector

The Large Hadron Collider (LHC) will be upgraded to the High Luminosity-LHC (HL-LHC), which will deliver proton-proton collisions at a much higher instantaneous luminosity than that of present LHC from 2026 on. In order to cope with the significantly higher pile-up at the HL-LHC, the tracking detector of the ATLAS experiment will be upgraded to an all silicon tracking detector, the ATLAS Inner Tracker (ITk), which will consist of a pixel detector in the innermost layers and a strip detector in the outermost layers. There are strong requirements on the ITk pixel detector to perform over ten years in the harsh environment at the HL-LHC, during which the ATLAS experiment is expected to record a dataset of 4000fb$^{−1}$. The large number of modules in the ITk pixel detector in combination with the limited available space and the expected tracking performance make the design of this detector challenging, in particular the powering scheme and the transmission of the hit data from the front-end electronics to the readout backend at high data rates are more complicated than in the current tracking detector. The expected performance of the ITk pixel detector will, however, enable a rich physics programme, for instance a significantly improved understanding of the Higgs sector.