CERN Shuts Down Large Hadron Collider Until 2030: Unveiling Secrets of Upcoming Transformations

Geneva, July 1, 2026 – As the clock struck the early hours of Monday, June 29, 100 meters underground, in the 27-kilometer circular tunnel that snakes between Switzerland and France, the currents cooling the superconducting magnets of the Large Hadron Collider (LHC) came to a definitive halt. The world’s largest and most powerful particle accelerator, the machine that confirmed the existence of the Higgs boson in 2012, has entered a deep slumber that will last for four years.

A Legacy of Milestones: The Scientific Harvest That Changed Physics Forever

Before undergoing its metamorphosis, the LHC leaves behind one of the most fruitful eras in the history of science. Since its first beam in 2008, its detectors have led to discoveries that have rewritten textbooks:

The Higgs boson (2012): The star discovery. The confirmation of the mechanism that grants mass to fundamental particles, predicted by Peter Higgs and François Englert in the 1960s, earned them the Nobel Prize in Physics in 2013 and closed the loop of the Standard Model, the theory that describes elementary particles and three of the four fundamental forces.
The Era of Exotic Hadrons: The LHC didn’t just corroborate the known but opened a new window to the unknown. It discovered over 85 new hadrons, including the elusive pentaquarks and tetraquarks, particles composed of five and four quarks respectively, that challenge the classical model of quarks grouped in pairs or triplets.
The Quark-Gluon Plasma (ALICE experiment): By colliding heavy lead ions, the machine recreated the conditions of the early universe, mere microseconds after the Big Bang, generating a «soup» of free quarks and gluons that allowed the study of the hottest and densest matter ever created in a laboratory.
CP Violation and Antimatter (LHCb): The experiment dedicated to beauty (the b quark) found subtle differences in the behavior of matter and antimatter, known as CP violation, helping to explain why our universe is made of matter and didn’t annihilate itself in the initial moments.
Cracks in the Standard Model: Although dark matter has not been directly detected, the LHC has set the tightest constraints on numerous theories beyond the Standard Model, ruling out entire versions of supersymmetry and guiding physicists on where to look in the future. Each precision measurement has revealed small anomalies in the behavior of the muon or the mass of the W boson, clues that the HL-LHC must address.

The Largest Underground Engineering Project

This is not a goodbye, but a «see you later» that marks the beginning of one of the greatest technical transformations in the history of science. This scheduled shutdown, known as Long Shutdown 3 (LS3), does not mean the end of the LHC, but the start of its rebirth as the High-Luminosity Large Hadron Collider (HL-LHC). When it is reactivated in June 2030, it will not be a faster or higher-energy machine, butten times more powerful in terms of collisions per second.

LS3, which has been delayed seven and a half months from the original schedule and will extend four months longer than planned, represents a logistical and technical challenge of epic proportions. During these four years, an army of thousands of engineers, physicists, and technicians from around the globe will work in the depths of the CERN complex.

The most critical intervention will focus on replacing 1.2 kilometers of magnets and components in the LHC ring. The current focusing magnets will be replaced by next-generation ones, made from niobium-tin, a material that can withstand much stronger magnetic fields. Additionally, superconducting «crab cavities» will be installed, which will tilt the proton beams just before collision to maximize head-on encounters.

CERN’s Director-General, Mark Thomson, described the moment as the start of a new era: «This is a real opportunity to explore the universe in ways we haven’t been able to before». Meanwhile, the HL-LHC project leader, Markus Zerlauth, emphasized the magnitude of the change: «This is a very important moment. Starting Monday, we enter a new phase».

The Quantum Leap in the Search for Dark Matter

The key to this transformation is not energy, but luminosity, meaning the number of collisions that occur in a given time. The HL-LHC is expected to produce ten times more collisions than the current LHC, translating into six times more analysable data than what was collected during the entire previous operational phase (Run 3).

This exponential increase in data is crucial for precision physics. So far, the LHC has produced about 55 million Higgs bosons. With the HL-LHC, it is expected to generate 380 million, a volume of information that will allow scientists to study this elusive particle in unprecedented detail.

However, the ultimate goal goes beyond that. Physicists hope this new capability will enable the detection of dark matter, that invisible substance which, along with dark energy, makes up about 95% of the universe and whose nature remains one of science’s greatest mysteries. CERN physicist Nedaa-Alexandra Asbah explained the enhancement with a photographic analogy: «It’s like replacing the camera at the heart of the detector with one that has much finer pixels».

The Next Generational Leap: The Future Circular Collider (FCC)

As the HL-LHC gears up for its golden decade (2030-2040), CERN is already eyeing an even more colossal project: the Future Circular Collider (FCC). Conceived as the natural successor to the LHC, this infrastructure represents a quantum leap in scale and ambition.

With a tunnel of 91 kilometers in circumference—over three times the size of the current one—and an average depth of 200 meters, the FCC would host magnets capable of reaching collision energies of up to 100 teraelectronvolts (TeV), far exceeding the LHC’s 14 TeV. Its preliminary construction cost is estimated at around 15 billion euros, but construction would not commence until the next decade, even though its design is already underway.

The project will unfold in two historic phases. The first, known as FCC-ee, will be an electron-positron collider that acts as a “Higgs factory”: it will produce millions of Higgs bosons in a clean collision environment (without proton interference), enabling physicists to measure the properties of this particle with surgical precision, capable of detecting minimal deviations that reveal new forces or extra dimensions.

The second phase, FCC-hh, will reintroduce proton collisions (and eventually heavy ions) to reach 100 TeV, an extreme energy that, for the first time, could directly produce dark matter particles in the laboratory instead of inferring their existence through indirect effects as is done now. This will also allow exploration of energy scales where the fundamental forces unify, venturing into entirely untouched territory for physics.

Jean-Philippe Tock, the LS3 coordinator, summed up the spirit of this roadmap: «LS3 represents a massive logistical and engineering undertaking, but it’s just the prelude to what is to follow». For now, silence has settled in the LHC tunnel. But in 2030, the HL-LHC will begin to write its own legend, paving the way for the FCC to perhaps in the 2040s play the ultimate anthem of particle physics: to answer whether the Standard Model is just the first chapter of a much larger cosmic book, or if nature still holds unsuspected secrets at its deeper scales.

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