How SubC delivers zero-tolerance cooling modules for CERN’s ATLAS & CMS upgrades
“It's every nerd's dream to get a call like this!”
Senior Commercial Manager, Jørgen Christoffer Feldberg-Ussler was absolutely thrilled when he received the call from CERN informing him that his team had won the contract.
Deep beneath the Swiss French border, the world’s largest and most ambitious particle-physics experiments called ATLAS and CMS are taking place. The experiments consist of gigantic, general-purpose detectors built around collision points of the LHC (Large Hadron Collider). They record and analyze the debris from protons smashed together at near-light speed.
CERN are now preparing for their next leap forward, where the two experiments are undergoing a major Phase-2 upgrade, one that demands absolute precision, extreme performance, and engineering at the very edge of what’s possible.
That's where SubC comes in.
The challenge
During CERN’s Phase-2 upgrade (LS3, 2026–2029), CERN will replace critical detector components with new silicon-based technologies. These detectors will dissipate hundreds of kilowatts of energy while operating in an environment colder than Antarctica. CERN needed a supplier that could take on the project from project brief and initial drawings to installation.
To survive and perform, the detectors require a highly specialised cooling system:
- Liquid CO₂ at -55 °C
- Operating pressures up to 100 bar
- A two-phase pumped loop scheme
- Parallel operation of multiple modular cooling units
For SubC, the task was clear and uncompromising:
Design, fabricate, assemble, and test cooling modules with virtually zero tolerance for error.
“When you’re cooling detectors designed to recreate the first moments after the Big Bang, “good enough” simply isn’t good enough.”
The main goal with the experiments is nothing less than to understand the fundamental building blocks of the universe, more specifically matter and the forces governing them. This includes testing the Standard Model of particle physics, searching for new particles or dimensions, and studying why the universe is made mostly of matter rather than antimatter. The experiments rely on superconducting magnets that only work when cooled to extremely low temperatures. At these temperatures, electrical resistance drops to zero, allowing enormous electric currents to flow without energy loss. This makes it possible to generate very strong magnetic fields that would otherwise be impractical or impossible.
The solution
SubC is delivering 16 custom-built cooling modules, engineered in three performance-based sizes to meet varying detector demands.
Each module combines:
- Structural frames manufactured to exacting tolerances
- Complex pipe systems designed for high pressure and ultra-low temperatures
- Assembly and testing where millimetres and microns matter
The real complexity lies not in a single component, but in the orchestration of all of them. Every weld, alignment, and pressure test must be flawless.
There’s no room for “close enough” when you’re cooling instruments designed to unlock the secrets of the universe.
So far, 11 out of 16 cooling modules have been delivered. The rest will follow, with final delivery planned for Q2 2026.
When fully installed, these modules will:
- Keep next-generation silicon detectors stable at –55 °C
- Enable ATLAS and CMS to operate at far higher luminosity
- Support experiments that search for dark matter, new dimensions, and physics beyond the Standard Model
In short: without cooling, there is no data. Without data, there are no discoveries.
We are honoured that CERN selected SubC as a supplier for one of the world’s most complex scientific upgrades. CERN doesn’t choose suppliers lightly. Being selected means you can deliver world-class engineering, under extreme conditions, at the very edge of what’s technically possible and with zero tolerance for failure.
That’s exactly what we do best at SubC.
