Figure 1. Group photo at SOTON during the celebration for the completion of the HiLumi LHC WP6A collaboration agreement. From right: Mark Spearing, SOTON, Vice President for Research and Enterprise; Mike Lamont, CERN, former ATS director; Amalia Ballarino, CERN, WP6A Leader; Oliver Brüning, CERN, former HiLumi LHC Project Leader and present ATS Director; Mark Smith, SOTON, President and Vice Chancellor; Yifeng Yang, SOTON, WP6a UK2 coordinator; Markus Zerlauth, CERN, HL-LHC Project Leader; Yann Leclercq, CERN, HL-LHC WP6a Deputy Leader. Credit: SOTON
By Amalia Ballarino (CERN)
In January 2026, CERN and the University of Southampton (SOTON) celebrated the successful completion of the series production of the DFX and DFH cryostats for the High-Luminosity LHC (HiLumi LHC) Cold Powering Systems.
Two types of complex cryostat units, DFX and DFM, with ten units in total (eight plus two spares) were produced in UK industry under the coordination and supervision of SOTON, within the framework of the HiLumi LHC UK2 Collaboration Agreement, signed in 2022.
These cryostats, featuring a high level of integration with both the system architecture and the LHC tunnel, operate at 4.5 K. Each receives the magnesium diboride (MgB₂) cables from its respective Superconducting Link and provides the connection to the 1.9 K superfluid helium environment of the magnets in the tunnel, allowing the current from the Superconducting Link to supply the magnet chain (see figure 2).
The series production was well aligned with the schedule of HiLumi LHC Work Package 6A (responsible for the Cold Powering Systems). The first DFX unit is now part of the Cold Powering System operated in the IT String, and the second DFX and first DFM units are used for surface testing of the Cold Powering Systems. The remaining series units will be installed underground in the HiLumi LHC during Long Shutdown 3.
The completion of this agreement marks the conclusion of a highly collaborative and successful effort, driven by strong team spirit and close collaboration, in which knowledge and expertise were shared in pursuit of a common goal. This milestone also marked the end of all collaboration and procurement activities for Work Package 6A.
Figure 2. Schematic representation of the HiLumi LHC Cold Powering Systems in the underground. The DFX (for the Triplet systems) and DFM units (for the Matching Section systems) are in the LHC tunnel, connected to the Superconducting Links which run from the HiLumi underground galleries to the LHC tunnel, to supply current to the magnets. Credit: HiLumi LHC Project / CERN
Figure 3. The first DFX unit (seen under the framing in the left-hand photo) is part of the Cold Powering System operated in the HiLumi HC IT String, a surface version of the inner triplet region which serves as a test bench for multiple systems together. On the right, you can see the Superconducting Link snaking between the DF and the DFH. Maximilien Brice / CERN