Speakers
Description
The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) will increase the integrated luminosity to 3000fb^{-1} and the instantaneous luminosity up to $7.5\times 10^{34} cm^{−2} s^{−1}$ in the ATLAS experiment. This results in an average of 200 proton-proton collisions per bunch-crossing compared to 48 in the current Run-3. This increases radiation damage and device occupancy. To cope with this challenge, the present ATLAS Inner Detector (ID) will be completely replaced with a new silicon-based Inner Tracker (ITk), made of five layers instrumented with Pixel detector at a radius below 300 mm and 4 layers of Strip detector surrounding it up to a radius of 1000 mm. The Pixel tracker is based on hybrid detectors with most of the system consisting of quad modules, where a single planar silicon sensor is flip-chip bonded to an array of 2x2 readout chips to produce the bare module. For the inner most layer, where the radiation level is highest, the 3D sensor is used, and the module consists of 3 individual bare modules of sensor and front-end chip. The pixel system consists of 8016 quad modules and 452 triplet modules made from 1356 3D bare modules.
The ITk is targeting the same or better physics performance than the current ID which necessitates a lower mass approach than the present system. To deliver this serial powering has been chosen for the LV power delivery solution. The increased power density and radiation levels calls for a lower cooling temperature than the ID and an evaporative CO$_{2}$ systems has been developed.
The talk presents the design requirements of the quad module with validation data including: the validation of the bump performance; the robustness of the hybridisation to thermal cycles from -55C to +60C; the module coating used for HV performance; assembly tolerances, and the design of the module powering for a serial powering chain.
Over 300 quad modules have been assembled and tested during the per-production phase. The pre-production QC results will be summarised.
