The phase II ATLAS Pixel: The Inner Tracker (ITk)

The ATLAS experiment is expected to enter the high-luminosity programme of the LHC (HL-LHC) with a thoroughly upgraded detector. This includes an all-silicon tracking system Inner Tracker (ITk) that will completely replace the current Inner Detector. The innermost part of the ITk will consist of a five-layer pixel detector in the barrel region complemented by two end-caps characterized by annular supports leading to an extended track-reconstruction coverage. Different sensor technologies (planar, 3D and CMOS) are being investigated for instrumenting the detector, which will need to cope with the high occupancy and radiation level that are expected in the HL-LHC environment. For the same reason a new front-end chip is being developed within the RD53 Collaboration. High data rates, expected in particular in the innermost layers, require the development of new technologies allowing high bandwidth transmission and handling.