Advancements and plans for the LHC upgrade detector thermal management with CO2 evaporative cooling

Following its pioneering application in the present LHCb Velo detector, CO2 evaporative cooling has become the consolidated technology for the thermal management of low-temperature operated silicon detectors at LHC. ATLAS Insertable B-Layer and CMS Phase I Pixel are successfully operating with such cooling system since a few years and LHCb has selected the same technology for the new Upstream Tracker and the upgraded Velo, both to be installed during LS2. The design of the ATLAS and CMS upgrade silicon detectors is well advanced, and both experiments heavily rely on CO2 evaporative cooling. In order to cope with the new detector requirements, several studies are on-going, in particular on the scaling of the cooling plants, their integration in the existing space and infrastructure, the low temperature operation. A demonstrator cooling system, the "Demo", is presently in the design phase at CERN. This paper discusses the challenges of the CO2 systems for the phase 2 upgrade of the LHC experiments, the design of the "Demo" cooling system and the integration and operational issues under study, presenting a time-line for the CO2 system development from now up to operation.