On January 20, CERN celebrated the completion of the civil-engineering work for the High-Luminosity Large Hadron Collider (HL-LHC), the major upgrade of its flagship collider, the LHC. Approved in June 2016 and due to start operating in 2029, the HL-LHC will considerably improve the performance of the LHC by increasing the number of particle collisions and thus boosting the potential for discoveries. The completion of the civil-engineering work marks the start of the transition towards the HL-LHC era; the new components for the collider will be installed in the caverns and galleries that are now ready. 

The HL-LHC is CERN’s main scientific goal of the decade, recognized as one of the highest priorities for the field in the 2020 update of the European Strategy for Particle Physics. This major upgrade builds on the success of the LHC since it started operating in 2010. While the LHC is able to produce up to 1 billion proton–proton collisions per second, the HL-LHC will increase this number, known as “luminosity”, by a factor of between five and seven, allowing about ten times more data to be accumulated between 2029 and 2041, the period during which it will be operating.

To achieve this increase in luminosity, several innovative and challenging key technologies are being developed. These include new superconducting quadrupole magnets (based on niobium–tin instead of niobium–titanium) that will better focus the beam, and compact crab cavities to tilt the beams at the collision points thus maximizing the overlap of protons. Other innovations include high-temperature superconducting links, new technologies for beam vacuum (prolonging the lifetime of the magnets) and beam collimation (protection from quenching), as well as very precise high-current power converters.

Most of these HL-LHC components will be integrated at Point 1 (Meyrin, Switzerland) and Point 5 (Cessy, France) of the LHC ring, where the high-luminosity detectors ATLAS and CMS are located.

“The civil-engineering work started in June 2018 and, despite the difficult global context, was successfully completed at the end of 2022. The technological developments are well advanced, so we really are at the start of the transition towards the HL-LHC era, one that will push the boundaries of technology and knowledge even further. It will allow physicists to study known mechanisms in greater detail, such as the Higgs boson, and observe rare new phenomena that might reveal themselves,” says Oliver Brüning, HL-LHC project leader.

The HL-LHC is an international endeavor involving 43 institutions in 19 countries, including in CERN’s Member and Associate Member States, as well as in the United States, Canada, Japan and China.

****

Image: Aerial view of the HL-LHC Point 5 surface buildings (Cessy, France) Credit: CERN