Planning is well underway for the successor to the world’s most powerful particle accelerator, the Large Hadron Collider (LHC).
The new “atom smasher”, named the Future Circular Collider (FCC), will dwarf the LHC in size and power. It will extract particles along with so much energy, in fact, that scientists say it may be able to probe our Universe’s most mysterious entities: Dark energy and dark matter.
LHC operators at CERN revealed the results of a “mid-term review” of their FCC Feasibility Study to the press on Monday (5 February). The feasibility study began in 2021 and is due to be completed in 2025. The results so far represent three years of work, with scientists and engineers from around the globe determining the ring placement of the new accelerator, FCC facility implementation, concepts for detectors and funding considerations.
The FCC will run under the jurisdiction of France and Switzerland, just as the LHC currently does, but the future accelerator will stretch 56.5 miles (90.7 kilometers), making it more than three times the length of current particle accelerators CERN, which is 16.8 miles (27 kilometers) long. The LHC is the largest and most powerful particle accelerator in the world.
Related: Dark matter could be hidden in the particle jets of the Large Hadron Collider
The FCC will operate in the same way as the LHC, accelerating charged particles around a loop, using superconducting magnets, then smashing them together as they approach the speed of light.
Scientists can investigate fundamental physics by observing showers of secondary particles created when particles such as protons collide. But while the LHC can reach energies of around 13 tera electronvolts (TeV) when operating at full power, CERN says the FCC should be able to reach energies as large as 100 TeV.
“Our aim is to study the properties of matter at the smallest scale and the highest energy,” said CERN director general Fabiola Gianotti at the presentation of the interim report in Geneva on Tuesday (February 6 .)
Why do particle accelerators need more power?
There is no doubt that the discovery of the Higgs Boson, the particle that carries force in a field called the Higgs Field, is the crowning achievement of the LHC so far, which passes through the universe and dictates the mass of other particles.
The sighting of the Higgs Boson by two LHC detectors was announced on July 4, 2012, and is credited with completing the Standard Model of particle physics, humanity’s best description of the universe, which particles and their interactions on a sub-atomic scale.
However, the Standard Model still needs some tweaking – and, since 2012, scientists have been using the LHC to search for physics outside the model to make those adjustments. Success is limited. This search will get a boost when the LHC’s high-luminosity upgrade is completed, which will mean the particle accelerator can perform more collisions and offer scientists more opportunities to observe exotic physics.
Dark matter and dark energy are the two main outliers of the Standard Model (aka, why some of those tweaks are necessary).
Sometimes known collectively as the “dark universe”, these phenomena are a great mystery to scientists as dark energy makes up about 68% of the energy and matter of the universe, and dark matter makes up about 27% of these continents. But neither can be seen because they don’t interact with light, and no one has been able to pin them down through other forms of direct detection, either. That means that the matter and energy that we understand and cannot account for is no more than 5% of the matter of the universe, and we really have little idea of 95% of the universe.
And probing these features of the universe may require breaking particles along with much more energy than the high-resolution LHC is capable of.
First of all, dark matter cannot be “standard matter” like the atoms that make up the things we see around us every day, like stars, planets and our bodies. Remember how it doesn’t interact with light? Well, protons, neutrons and electrons — collectively called “baryons” do. Therefore, dark matter must be something else.
Currently, the only way scientists can infer the existence of dark matter is through the interaction with gravity and the effect this has on baryonic matter and, in turn, light.
Dark energy is more problematic. It is the force that scientists see driving the acceleration of the universe’s expansion.
It refers to a period of expansion distinct from the initial inflation of the universe, triggered by the Big Bang. That early expansion then slowed to a halt, and in the later period, the universe began to expand again without explanation. This rate of expansion is accelerating to the present day, and dark energy is used to account for that action.
But, as we have discussed, scientists do not know what dark energy is.
To see why that’s a concern, imagine pushing a child on a swing. The Big Bang is like your first and only push that sets the swing in motion. The swing may continue for a short time, even without any action from you, then it will come to half. Then, imagine that it suddenly starts moving again despite the fact that you are just standing there. And not only that, but it swings faster and faster, reaching higher and higher points. This is similar to what dark energy is doing to the fabric of space.
CERN hopes that the FCC’s high-energy collisions could reveal the nature of this persistent, late pressure and the particles that make up dark matter.
However, it will be some time before this future particle accelerator is ready to take on the investigation of the dark universe.
Timeline and cost of the Circular Collider of the Future
In 2028, three years after the FCC’s feasibility study is completed, CERN’s member states will meet to decide whether the FCC will get permission. If the future collider gets the green light, CERN says, construction will begin in the mid-2030s.
The FCC will be completed in phases. The first step is an electron-positron collider (FCC-ee) that slams together negatively charged electrons, their positive antiparticle counterparts, called positrons, and other light particles. CERN adds that FCC-ee should start operations in 2045.
The second FCC machine will be a proton collision accelerator (FCC-hh) sitting alongside the FCC-ee in the same evacuation tunnel buried under the French-Swiss Alps and Lake Geneva. This part would come online no earlier than 2070, according to CERN.
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At the CERN press conference, Gianotti outlined some of the FCC’s costs, saying that the first FCC-ee phase alone would cost about $17 billion USD.
The Director General of CERN justified the cost by adding that the FCC was the only machine that would allow humanity to make the great leap in studying matter needed to break the secrets of the dark universe.