The LHC's Final Shutdown: CERN Begins a Four-Year, $1.5 Billion Transformation

The LHC era, from first collisions in 2010 through Run 3 ending in 2026, produced the landmark discovery of the Higgs boson on July 4, 2012, by the ATLAS and CMS collaborations—a breakthrough that completed the Standard Model and earned the 2013 Nobel Prize in Physics . Run 1 (2010–2012) set world records with 3.5 TeV per beam; Run 2 (2015–2018) ran at 6.5 TeV per beam; and Run 3 (2022–2026) operated at a record centre-of-mass energy of 13.6 TeV, collecting hundreds of inverse femtobarns of data .

LS3 Timeline and Scope

LS3 is expected to last up to four years, involving thousands of experts across CERN's sites and tunnels . The LHC's last beams were scheduled to be dumped on June 29, 2026, according to CERN's internal schedule . The injectors will continue producing beams through August 2026 before their own shutdown begins .

The LS3 programme includes major maintenance, consolidation, and the installation of the HL-LHC's core components: new 12-tesla niobium-tin quadrupole magnets (inner triplets) that will focus beams more tightly than the current 8-tesla niobium-titanium magnets, and superconducting radio-frequency crab cavities that will tilt proton bunches before collision to maximize head-on overlap and correct geometric luminosity loss . About 1.2 km of the LHC tunnel will be replaced with new technologies .

The restart of data-taking is scheduled for 2030 at the earliest, after hardware and beam commissioning . The accelerator complex is expected to gradually resume operation from mid-2028 onwards, but full physics collisions will take longer to achieve .

The $1.5 Billion Upgrade: Cost and Technical Details

The HL-LHC project is a multi-billion-Swiss-franc investment. The figure of roughly $1.5 billion (approximately 1.5–1.6 billion Swiss francs) is consistent with the project's approved budget envelope, though exact reported numbers vary by currency and year . CERN press materials describe it as a major multi-year investment covering new magnets, cryogenics, collimators, shielding, and upgraded detectors including ATLAS, CMS, ALICE, and LHCb .

The core goal is a tenfold increase in integrated luminosity, from the LHC's original design of about 300 fb⁻¹ to up to 3000 fb⁻¹ for the HL-LHC . Peak luminosity is expected to reach 5×10³⁴ cm⁻² s⁻¹, with potential to push higher . This tenfold boost means roughly 15 million Higgs bosons produced per year, enabling precision studies of Higgs couplings and self-interactions that are impossible today.

Scientific Achievements of the LHC Era (2010–2026)

• Higgs boson discovery (2012): ATLAS and CMS announced the discovery of a new boson with a mass of about 125 GeV, consistent with the Standard Model Higgs boson, completing a five-decade search . The discovery was awarded the 2013 Nobel Prize in Physics .
• Run 1 (2010–2012): First collisions at 3.5 TeV per beam, a world record, culminating in the Higgs discovery .
• Run 2 (2015–2018): Collisions at 6.5 TeV per beam; precision measurements of the Higgs boson, confirmation of Yukawa couplings to third-generation fermions, and observation of rare processes .
• Run 3 (2022–2026): Continued proton-proton and heavy-ion collisions at 13.6 TeV centre-of-mass energy, doubling the total collected dataset .

The LHC's operational era is often described as an "18-year run," though this is a round approximation of the calendar span from first collisions (2010) to the end of Run 3 (2026). The actual collision time was closer to 13 years, interrupted by Long Shutdown 1 (2013–2015), Long Shutdown 2 (2019–2021), and annual year-end technical stops .

What the HL-LHC Will Enable

Once operational, the HL-LHC will allow physicists to:

• Study the Higgs boson with unprecedented precision, measuring its couplings to other particles and searching for signs of self-interaction, which could reveal deviations from the Standard Model.
• Search for dark matter with higher sensitivity to weakly interacting massive particles and other beyond-Standard-Model signatures.
• Extend discovery reach for new heavy particles by roughly 30%, because the vastly larger dataset allows scientists to detect or exclude particles at higher masses than the current LHC could .

The HL-LHC is projected to continue operations until approximately 2041, after which CERN will decide on its successor—possibly the Future Circular Collider (FCC) . The machine will retire having served as the flagship instrument for particle physics for over three decades.

The LHC's final shutdown is not an ending but a metamorphosis. When the collider reawakens around 2030, it will be a fundamentally different machine, designed to answer the deepest questions left open by the Higgs discovery: what lies beyond the Standard Model, what dark matter is made of, and whether the universe's fundamental forces unify at higher energies.