Prototyping of larger structures for the Phase-II upgrade of the pixel detector of the ATLAS experiment

For the high luminosity era of the Large Hadron Collider (HL-LHC) it is forseen to replace the current inner tracker of the ATLAS experiment with a new detector to cope with the occuring increase in occupancy, bandwidth and radiation damage. It will consist of an inner pixel and outer strip detector aiming to provide tracking coverage up to |η|<4. The layout of the pixel detector is foreseen to consist of five layers of pixel silicon sensor modules in the central region and several ring-shaped layers in the forward region. It results in up to 14 m² of silicon depending on the selected layout. Beside the challenge of radiation hardness and high-rate capable silicon sensors and readout electronics many system aspects have to be considered for a fully functional detector. Both stable and low mass mechanical structures and services are important. Within the collaboration a large effort is started to prototype larger detector structures for both the central and forward region of the detector. The aspect of system integration is tested with prototype components. In the paper the latest evaluation of mechanical and thermo-mechanical prototypes and fully electrical prototypes is presented. Important qualification steps of the system design are discussed.