The world's largest particle accelerator is about to take a long break. After years of smashing protons together, the Large Hadron Collider (LHC) enters a scheduled four-year shutdown. But don't be fooled: this is no simple nap, it's a full-scale metamorphosis. Upon its awakening in 2030, it will become the High-Luminosity LHC, capable of producing ten times more collisions. This paves the way for groundbreaking discoveries about dark matter and antimatter.
Why this transformation? The main goal is to increase luminosity, i.e., the number of collisions per second. With more data, physicists will be able to study rare events and test theories with unprecedented precision. For example, the Higgs boson, discovered in 2012, will be produced in much larger quantities: about 380 million units over the coming decade, compared to 55 million so far. This data could help resolve the shortcomings of the Standard Model.
At the LHC, magnets bend protons along a 17-mile (27 km) ring, built beneath the Franco-Swiss border.
Credit: CERN This is not the first time the LHC has stopped for an extended period. The first interruption, in 2013, allowed for the consolidation of connections between the superconducting magnets and an increase in beam energy. The second, from 2018 to 2022, involved a series of upgrades and replacements. Today, Long Shutdown 3 (LS3) will see the replacement of 0.75 mile (1.2 km) of magnets and components. Thousands of engineers, physicists, and technicians are mobilized.
The technical undertaking is colossal. Jean-Philippe Tock, LS3 coordinator, stated that this project represents an immense logistical and engineering endeavor. Meanwhile, researchers will continue to analyze the data already collected. Once operational, the HiLumi LHC will run into the 2040s, after which an even more powerful new accelerator could replace it.
The scientific payoffs could be considerable. With more Higgs bosons and other particles, physicists will be able to probe the limits of the Standard Model. This model fails to explain dark matter and dark energy, which nevertheless make up the vast majority of the Universe. Perhaps the HiLumi LHC will reveal new particles or interactions capable of filling these gaps.
Beyond fundamental research, the technologies developed for this upgrade find applications in everyday life. Instruments stemming from CERN are already used in medical imaging, sensors, and art restoration. This shutdown period is also an opportunity for innovation and knowledge transfer.