CERN has made a bold dream of building a new accelerator almost four times as long as its 27-kilometer Large Hadron Collider – currently the largest in the world – and up to six times stronger.
The European Laboratory for Particle Physics. outside Geneva, Switzerland, the plan was presented in a technical report on January 15.
The document contains several preliminary designs for a Future Circular Collider (FCC), which would be the most powerful particle smasher ever built, with various designs Types of The collision costs amounted to around 9 to 21 billion euros. It is the lab's opening bid in a priority-finding process for the next two years, called the European Strategy Update for Particle Physics, and will affect the future of the field well into the second half of the century.
"It's a giant jump, as if you were planning a trip not to Mars, but to Uranus," says Gian Francesco Giudice, who heads the CERN's theory department and represents CERN in the Physics Preparatory Group's strategy exercise.
After the historic discovery of the Higgs boson by the LHC in 201
The potential for a machine like the FCC is" very exciting, "says Halina Abramowicz, a physicist at Tel Aviv University who leads the European strategy process She adds that the potential of the FCC should be discussed in detail and compared with other proposed projects.
The CERN Council, the Scientists and government officials from the member countries will then make the final decision on financing the project.  Too expensive?
Not everyone is convinced that the Super Collider is a good investment. "There is no reason to believe that there would be such a collider with new physics in the energy regime," says Sabine Hossenfelder, theoretical physics at the Frankfurt Institute for Advanced Studies in Germany. "This is the nightmare everyone has in their heads, but he does not want to talk about it."
Hossenfelder says that the large sums may be used for other types of large-scale facilities. She says, for example, that placing a large radio telescope on the other side of the moon or a gravitational wave detector in orbit would be safer bets for the return to science.
But Michael Benedikt, a CERN physicist Who led the FCC report, said that such a facility would be worth construction regardless of the expected scientific outcome. "These kinds of biggest efforts and projects are great occasions for networks to connect institutions across borders. All these things together make a very good argument for promoting such unique science projects.
Although Hossenfelder says that a similar argument could apply to other major science projects.  The options
The FCC study began According to CERN, in 2014 more than 1,300 contributors were involved, making a financial contribution from the European Commission's Horizon 2020 research funding program, in most scenarios, a 100 km tunnel will be dug next to the existing Large Hadron Collider tunnel, costing about € 5 billion in surface area and related infrastructure , says CERN.
A € 4 billion machine built in such a tunnel could electrons and their antimatter counterparts, positrons, with energies of up to 365 gigaelectronvolts. Such collisions would allow researchers to detect known particles such as to study the Higgs boson with greater precision than at e a proton-proton collider such as the LHC is possible. This new research program would not begin until around 2040, after the LHC had embarked on its course, including a planned updated version.
Physicists have long been planning to build an International Linear Collider (ILC) after the LHC, which would also smash electrons and positrons. Japanese scientists hosted in 2012 as hosts. The failure of the LHC to find unforeseen phenomena has reduced the case for a linear collider. This is because the ILC only reaches energies sufficient to study the Higgs, but does not discover new particles that exist at higher energies, as the CERN collider has planned. The Japanese government will decide whether to host the ILC until March 7th.
Another option outlined in the report is the construction of a proton-proton collider (also called hadron collider), which costs 15 billion euros in the same tunnel, which could reach energies of up to 100,000 GeV, much higher than the maximum capacity of the LHC of 16,000 GeV. However, a more likely scenario would be to first build the electron-positron machine and later, in the late 2050s, move to the proton-proton collider. In any case, the machine with higher energy requirements would look for completely new particles that could be more massive than the known ones and therefore require more energy for production.
The hadron collider would be only 15% longer than the superconducting super collider. a project in Texas, which was abandoned for cost reasons in the 1990s, when the tunnels were already under construction. Because of technological improvements, especially with the magnets bending the path of the protons around the ring, the particles would be more than doubled in energy.
A lot of research and development is needed, which is one of the reasons why it might make sense to build the lower energy machine first. "If we had a 100 km tunnel ready tomorrow, we could immediately start building an electron-positron collider, because the technology is essentially already there," says Giudice. "However, the magnets required for a 100 teraeltroncoller kollerator require more research and development."
Wang Yifang, director of the Chinese Institute of High Energy Physics (IHEP) in Beijing, says that this is not the case doubt that the laboratory could go through such a project. "CERN has a long track record. He has the technological skills, management skills and good relationships with governments. "Wang is leading a similar project in China, and he says that both efforts have essentially come to the same conclusion scientifically in terms of goals and technical feasibility. In particular, it is a natural decision to first perform electron-positron collisions and then proceed to hadrons. Much of the extra cost for a hadron collider would result from the need for powerful superconducting magnets and the huge material cryogenic helium systems to keep them cold. The hadron-colliding FCC would target 16-tesla magnets based on the Nb3Tn superconducting alloy, which would be twice as strong as the LHC and would generally require only slightly warmer temperatures. On the other hand, China is pushing for more advanced but less well-proven iron-based superconductors that could raise temperatures even further. "If you can do it at 20 Kelvin, you'll get huge savings," says Wang.
Even if particle physicists agree that the world needs a 100 km collider, it is unclear whether it needs two. Regardless of which side of such a project gets going first, efforts on the other side are likely to anticipate. Both colliders would host experiments open to the broader international community, Wang said, so it will not make a difference which will be built in the end.