As CERN prepares to increase the LHC’s luminosity by a factor of ten, the ATLAS and CMS detectors need far stronger thermal management. These upgraded systems must keep newly installed silicon sensors extremely cold. Maintaining low temperatures is essential because the sensors face intense radiation and must deliver precise measurements during high-energy proton collisions.
Why CO₂ Cooling Is Critical
According to Jérôme Daguin, cooling engineer and CMS cooling coordinator at CERN, ATLAS and CMS will use a two-phase CO₂ cooling system for all silicon trackers and endcap calorimeter detectors.
He explains that CO₂ offers several advantages. It provides high heat transfer, low viscosity, and a temperature range well-suited for detector operations. It is also an environmentally friendly alternative to many other cooling media.
Lewa’s Engineering Adjustments for Extreme Conditions
To meet CERN’s strict technical demands, Lewa Switzerland AG introduced several design changes to its pumps. Wieland Wolff, Area Sales Manager at Lewa Switzerland AG, notes that the team had to meet an ambitious list of requirements. During prototype development, they implemented major adaptations to ensure reliable performance under ultracold and high-pressure conditions.
Key engineering changes include:
*Remote pump head design to isolate the drive unit from ultracold CO₂
*Specialised silicone oil and seals for extreme temperature stability
*Enlarged diaphragm heads to reduce mechanical stress
*PTFE-coated surfaces to eliminate even minimal CO₂ leakage
With these upgrades, 18 Lewa ecoflow LDG pumps will support the ATLAS and CMS cooling systems. Installed in radiation-free service caverns, the pumps are controlled remotely using electric stroke adjustment and frequency inverters. This setup removes the need for any on-site handling.
Looking Ahead to the 2028 Upgrade
By 2028, CERN will operate a full pump network connecting transfer lines and micro-channels that cool electronics and silicon sensors. Daguin emphasizes that these pumps form the core of the cooling units for the Phase-2 Upgrade of the ATLAS and CMS silicon detectors. As reported by worldpumpas.com, Wolff adds that Lewa and CERN will continue refining the technology. Planned diaphragm bending cycle tests aim to further improve long-term pump performance and ensure stable operation throughout the LHC’s high-luminosity era.
