CMS ECAL upgrade for higher luminosity: Cooling test of an ECAL supermodule for future operation at 9°C and Evaluation and radiation testing of power distribution system components

A method was devised to measure cooling-induced stress in the mechanical structure of CMS (Compact Muon Solenoid) barrel ECAL (electromagnetic calorimeter) supermodules. Specifically, the stress amount and distribution occurring consequent to cooling to the new design specification for the HL-LHC (High Luminosity Large Hadron Collider) was analyzed. The results were then put into context by comparison with supermodule lifting, an impossible to circumvent operation during installation, to demonstrate absence of cooling-related structural threats. Furthermore, the radiation hardness of several devices, intended for future use in the power distribution system of ECAL trigger tower electronics, was investigated. No adverse effects, ensuing from the radiative conditions imposed by the HL-LHC, could be observed for the examined components.