63U ATCA rack thermal performance and its integration in the undergound areas

Since for the High Luminosity LHC the instantaneous luminosity will be increased by a factor 3, an efficient trigger selection will be crucial. Therefore, the ATLAS hardware trigger and the calorimeter read-out will be upgraded for HL-LHC to base the trigger decision on much more fine-grained information. A custom designed 63U rack has been chosen as a house for the ATCA based systems allowing installation of 50% more shelves in the detector proximity. Higher power dissipation requires an assessment of the impact on the existing underground infrastructures and cooling apabilities verification in a test setup, which also became the cooling facility to qualify the detector boards prototypes