Proposals for the successor to the LHC accelerator under consideration

The examination of proposals for the successor to the world's largest particle accelerator , the Large Hadron Collider (LHC) at CERN in Geneva, in which Italy is participating with the National Institute for Nuclear Physics, is underway. The LHC, now fully operational, should retire in 2041 and a further upgrade is planned starting in 2026 that will keep it closed for about 3 years . The world of European physics is therefore looking at its possible successor , examining the various proposals on the table . The opportunity for a comparison is the European meeting on particle physics organized in Venice by the INFN with the support of CERN in Geneva. "There are a number of possible options ," Gianluigi Arduini, a physicist at CERN and coordinator of the group tasked with evaluating the proposals, told ANSA, "the Future Circular Collider is among the most promising . It is a machine with a circumference of around 90 kilometres that would have two successive phases: an initial one for the second half of the century, in which electrons and positrons, their antiparticles, would collide; another phase where the machine would become a proton-proton collider. This second phase," Arduini continued, "would see the light around 2070, so we are talking about a truly long-term program." The FCC would therefore be more than three times larger than the LHC and would be built between France and Switzerland at a depth of around 200 metres . "The feasibility study was completed this year," Arduini added, "with an estimated cost for the first phase of around 15 billion Swiss francs ." Other proposals concern non-circular, but linear, particle accelerators . "There are at least 2 options of similar scope ," says Arduini. "The advantage of linear machines would be to eliminate the loss of energy of the particles that instead occurs in circular ones - he underlines - however in linear colliders the beam can produce a single collision event at a time ." Furthermore, while circular accelerators can host 4 experiments that collect data simultaneously, linear ones can have a maximum of 2, which collect data alternately. In any case, the heir to the LHC will have a fundamental role: "We expect, first of all, to be able to study the Higgs boson in an even more in-depth manner - concludes Arduini - in order to understand how it behaves in different situations. And then, to see if there are any signs of new physics ": the Standard Model, that is, the reference theory of modern physics, "works well, but we know that it is not complete."