Preparing ATLAS for the high-luminosity LHC: system testing and performance evaluation of the ITk Strip detector

Abstract The new ATLAS Inner Tracker (ITk) will replace the current tracking system in ATLAS to cope with the challenging conditions during the high-luminosity phase of the Large Hadron Collider. ITk is an all-silicon detector consisting of a pixel inner tracker and a silicon microstrip outer tracker. This contribution focuses on the results of the large-scale system testing of the ITk Strip detector, which is the testbed for verifying the design and evaluating the performance of detector components prior to production. This setup is also being used to develop detector control and data acquisition systems required for the eventual operation of the ITk Strip detector. Two sets of experiments at CERN and DESY (Hamburg, Germany) target the design verification of the central barrel section around the interaction point and the end-cap section covering the forward region. In both setups, silicon sensors mounted on support structures are connected to electrical, optical and cooling services as realistic as possible as in the latter detector integration. As such, it is possible to validate the detector design, verify the detector DAQ and perform tests with the services, e.g. concerning the dual-phase CO2 cooling. This contribution gives an overview of the developed system tests for the ITk strip detector, summarizes the current status of the two sites, and shows a selection of performance measurements.