Test Beam Studies of ATLAS ITk Strip Modules for the ATLAS Phase-II Upgrade

The ATLAS experiment will replace its Inner Detector with an all-silicon Inner Tracker (ITk) to cope with the occupancy and radiation doses expected at the High-Luminosity LHC. The ITk is composed of pixel and strip subsystems. The strip subsystem is built from modules consisting of one n+-in-p silicon sensor, one or two PCB hybrids containing the front-end electronics, and one powerboard with high voltage, low voltage, and monitoring electronics. A series of test beam campaigns have been performed over several years to validate the expected performance of the ITk strip detector. EUDET telescopes consisting of six Mimosa26 pixel planes provide tracking, while a dedicated pixel or strip plane improves the timing resolution. Tracks are reconstructed using the General Broken Lines algorithm, resulting in a spatial resolution of several microns. The data allow for thorough tests of the module performance, including charge collection, noise occupancy, detection efficiency, and tracking performance. Studies before and after irradiation to the expected end-of-lifetime fluence of modules with preproduction-ready components are shown. Excellent tracking resolution and hit reconstruction efficiency are found. The results give confidence that the ITk strip detector will meet the requirements of the ATLAS experiment.