The European Organization for Nuclear Research (CERN) has officially commenced a planned, multi-year shutdown of the Large Hadron Collider (LHC), the world’s largest and most powerful particle accelerator. Operations at the facility, which straddles the border between France and Switzerland, were suspended on Monday, June 29, to facilitate a comprehensive upgrade of the machine’s systems. Known as Long Shutdown 3 (LS3), this maintenance period is designed to transform the current apparatus into the High-Luminosity Large Hadron Collider (HiLumi LHC), with the facility expected to resume operations in 2030.
This transition marks a significant milestone for particle physics research. By increasing the collider’s luminosity—a measure of the number of potential collisions per unit area over time—by a factor of 10, scientists aim to triple the rate of particle collisions compared to the current configuration. According to CERN, this enhancement will allow researchers to collect significantly more data, increasing the probability of observing rare subatomic events and further testing the limits of the Standard Model of particle physics.
“This is a very important moment,” HiLumi LHC project chief Markus Zerlauth stated, as reported by Agence France-Presse. “From Monday, we will be entering a new phase.”
Engineering the High-Luminosity Future
The current dormancy period is the third major, long-term pause in the history of the LHC since its first successful proton collision in 2009. The facility, which consists of a 17-mile (27-kilometer) ring, requires extensive physical modifications to meet the updated performance goals. Jean-Philippe Tock, head of the LS3 coordination team, described the project as a massive logistical and engineering undertaking. The plan involves the removal and replacement of approximately 1.2 kilometers (0.75 miles) of magnets and critical infrastructure within the collider tunnel, requiring the coordination of thousands of physicists, engineers, and support staff.
Civil engineers work on upgrades to turn the Large Hadron Collider into the High Luminosity Large Hadron Collider, significantly increasing the facility’s rate of particle collisions. (Image credit: Samuel Joseph Hertzog, CERN)
The primary objective of these upgrades is to deepen our understanding of the fundamental building blocks of the universe. Since the discovery of the Higgs boson in 2012, which confirmed the mechanism by which particles acquire mass, the LHC has been central to modern physics research. The HiLumi upgrade is projected to produce roughly 380 million Higgs bosons over its operational decade, a substantial increase from the approximately 55 million produced to date. This influx of data is intended to help physicists investigate phenomena that remain outside the current Standard Model, including the nature of dark matter and dark energy.
Beyond Fundamental Research
While the primary mission of the collider remains pure research, the technologies developed for the HiLumi upgrade often yield practical applications in other sectors. Techniques originally pioneered at CERN for particle detection and beam management have previously been adapted for use in advanced medical imaging, sensor technologies, and even art restoration. As the facility enters this period of dormancy, the global physics community will continue to analyze the vast datasets collected during the previous operational run, ensuring that research output remains constant despite the temporary suspension of physical collisions.
“It really is an opportunity to explore the universe in a way we haven’t done before,” Mark Thomson, director general of CERN, said in comments reported by New Scientist.
The upgraded collider is scheduled to remain in operation until the 2040s. At that point, the facility is earmarked for replacement by a new, higher-energy particle accelerator in the years that follow. For now, the focus at the Geneva site remains squarely on the complex task of installing the next generation of superconducting magnets and beam-focusing equipment.