Particle accelerator: CERN presents feasibility study for LHC successor

The Large Hadron Collider (LHC) is currently the largest and most powerful particle accelerator in the world. Groundbreaking discoveries have been made there, such as the experimental detection of the Higgs boson in 2012. However, the facility, which was commissioned in 2008, is no longer sufficient. The European Organization for Nuclear Research (CERN) is planning a successor.

The Future Circular Collider (FCC) is also to be built under the Swiss-French border region near Geneva. It is to be located 200 meters below the surface and have a circumference of 91 kilometers – the LHC has 27 kilometers.

CERN has published a feasibility study which – according to CERN – "reflects the expertise of more than a thousand physicists and engineers from all over the world". Around 100 different scenarios were run through.

Effects on fauna and flora

For the study, the subsurface was examined using seismic measurements and test drillings. It was checked whether there was enough water and electricity available and how well the construction sites were accessible by road. The effects of the tunnel bores on flora and fauna were also considered. The conclusion: the project is basically feasible.

The question is: how? Two variants are being discussed. One envisages a two-stage approach. In the first step, an electron-positron collider is to be created in which electrons and positrons collide. In the second step, the FCC is to be expanded into a proton-proton collider that works with collision energies of around 100 teraelectronvolts (TeV) –, which is around eight times as much as the LHC.

Ring or linear accelerator?

The other faction would like to build the proton-proton collider straight away. However, the technology required for this is not yet fully available. Finally, there are other proposals, such as building a linear accelerator around 50 kilometers long instead of a new ring.

The FCC as an electron-positron collider could be ready by the early 2040s. CERN estimates the costs over the twelve-year construction period at 15 billion Swiss francs, the equivalent of almost 16 billion euros.

The study will first be reviewed by various expert committees and then by the CERN Council. The CERN Council could decide "around 2028" on whether and how the FCC project should be implemented. Planning for the FCC began in 2014.

(wpl)