The current Large Hadron Collider. Image: CERN
Not content with the 27-kilometre-round Large Hadron Collider, researchers at CERN have their sights set on a new beast of a particle collider that could have a circumference of 80 to 100 kilometres.
The nuclear research organisation announced that it was hatching plans for an ambitious successor to the LHC with an international study called the Future Circular Colliders (FCC) programme, which will kick off with a meeting next week.
The idea is to consider different hadron collider designs similar to the existing LHC but more powerful—much more powerful. CERN wrote it was looking for a collider “capable of reaching unprecedented energies in the region of 100 TeV.” The existing LHC will reach a maximum of around 14 TeV (tera electron Volts).
A map of where an 80-100km tunnel could be built to house a new circular collider. Image: CERN
A more powerful collider could help push research into aspects of particle physics including the Higgs boson, dark matter, and supersymmetry. But don’t expect any answers soon, because there’s no word on exactly when, or even whether we could see one built. CERN points out that the LHC was initially conceived in 80s but didn’t get finished until 2008. They stress that for now, the “High Luminosity” LHC—an upgraded configuration of the LHC set for 2024 that will increase the number of collisions in experiments tenfold—is its priority.
One proposal for a future, circular collider is called TLEP, and it’s this design that would require an 80km tunnel. “Effectively, TLEP would be two machines in one,” researchers behind the project explain in a video. “The first stage of this collider, TLEP, would be able to measure the coupling, the properties of the Higgs boson to a [new level of] precision,” one says. “The other would be constraining the electroweak parameters of the theory,” adds another.
A brief introduction to the TLEP design. Video: Cristina M/Youtube
John Ellis at Kings College London sums that up: “those measurements could be sensitive to particles inaccessible to the LHC.” In a nutshell: It could discover new stuff important to our understanding of how physics works.
But not everyone’s down with the idea of another big circular collider. The FCC programme will run alongside another that’s been in the works for a while—the Compact Linear Collider, or CLIC, study. That’s looking at linear machines, which would use a different accelerating technology to what we’re used to. Physics World explains that a linear collider would “study the Higgs boson in great detail through the ‘clean’ collisions that can be made from colliding electron and positrons rather than smashing protons together.”
Both approaches will be studied ready for CERN’s next European Strategy update in four or five years, and as the organisation’s director for research and computing Sergio Bertolucci explained, ongoing research with the current LHC could help make the decision. “The forthcoming results from the LHC will be crucial in showing us which research paths to follow in the future and what will be the most suitable type of accelerator to answer the new questions that will soon be asked," he said.