Module Loading for ATLAS Upgrade ITk Silicon Pixel Inner System

The Inner Tracker (ITk) is an all-silicon replacement for the current Inner Detector of the ATLAS experiment at CERN. The ITk has silicon strip detectors and silicon pixel detectors integrated into a common volume. The two pixel detector layers closest to the LHC beam line, known as the Inner Pixel System, will be loaded and integrated at SLAC National Accelerator Laboratory using modules and supports from other institutes. Module loading is the process of securing the silicon pixel modules to the carbon fiber local supports inside the structure of the ITk. Different geometries of these modules and their supports make up the barrel and endcaps for the two detector layers of the Inner System. The modules must be precisely loaded onto the rigid supports to provide the best detector coverage and ensure module functionality in the tightly-packed, high-radiation environment near the interaction point. Position tolerances for the modules range from 150 microns to as little as 75 microns for some locations in the detector. This report will cover the methods developed at SLAC for loading modules at these precisions, including the testing and verification process to meet design specifications, as the ITk Inner Pixel System begins production.