CERN shuts down the Large Hadron Collider for upgrade, with restart targeted for 2030

CERN has shut down the Large Hadron Collider for a planned upgrade campaign that is expected to keep the machine offline until 2030.

The shutdown began on June 29, 2026, at 06:00 local time. It marks the start of a multi-year maintenance and modernization phase for CERN's 27-kilometer accelerator ring near Geneva, one of the most important machines in particle physics.

The next operating phase is the High-Luminosity Large Hadron Collider, or HL-LHC, also referred to in reporting as HiLumi-LHC. Current reporting and CERN's planning point to a restart target in June 2030.

A planned pause, not an accident

CERN describes the move as a scheduled transition rather than an unexpected outage. The current LHC run has ended so engineers can carry out upgrades and replacements before the machine returns to service.

That distinction matters. This is not a failure of the accelerator or an emergency shutdown. It is a planned handoff from the current operating era to the next one.

The work is expected to continue for several years and will affect both the accelerator complex and the experiments that depend on it.

Why the machine is going offline

The shutdown is part of the HL-LHC program, a long-running effort to increase luminosity, the measure of how many collisions can be produced over time.

Higher luminosity gives scientists more chances to capture rare processes and to improve measurements of known particles and interactions. That is the central scientific argument for taking the machine offline now.

The modernization is expected to include new or improved magnets and detector systems, so the accelerator can handle a more intense beam environment when operations resume.

For CERN, the goal is not merely to restart the machine in 2030. It is to return with a more powerful instrument that can produce much larger datasets for the next phase of high-energy physics.

The timeline to 2030

The immediate chronology is straightforward. The LHC was shut down on June 29, 2026, and the upgrade phase is now underway.

CERN and reporting sources point to June 2030 as the target for the next operating phase. The broader plan is to complete installation and upgrade work across the accelerator complex before that restart.

That date should be treated as a planning target, not a guarantee. Large accelerator projects can slip, and future CERN updates will show whether the schedule holds.

Even so, the current milestone is significant: it marks the end of one LHC operating chapter and the formal transition to the high-luminosity era.

Who is affected

The shutdown affects CERN directly, but the consequences go wider than the organization itself.

The international collaborations behind ATLAS, CMS, LHCb and ALICE depend on beam time from the collider to collect the data that drives their research. A multi-year shutdown means a long pause in the main data-taking program for those teams.

It also reshapes the schedule for the broader particle physics community, which tracks the LHC closely because it remains one of the field's central instruments.

The pause gives CERN time to prepare the machine and the experiments for a more demanding operating environment once the beam returns.

What the upgrade is supposed to deliver

The HL-LHC phase is designed to make the collider substantially more productive once it comes back online.

More collisions should improve the odds of observing rare processes and sharpen precision measurements. That matters for questions around known particles, subtle deviations in standard models and the search for effects that may point toward dark matter-related physics.

Researchers see the upgrade as a way to extend the scientific life of the LHC, rather than replace it. The next run is meant to deepen what the machine can already do well.

The scale of the investment also shows how central the collider remains to CERN's long-term research agenda.

The broader CERN context

The LHC is CERN's 27-kilometer ring collider near Geneva, and the current shutdown is part of a larger operational cycle, not a standalone event.

In the reporting, the next phase is often described as Run 4, beginning after the upgrade work is completed. That phase is expected to start in 2030 if the schedule stays on track.

CERN's role in this transition is both technical and strategic. It must complete the hardware work, keep the experiments aligned with the new operating conditions and manage the financing and planning needed for the next decade of research.

The shutdown therefore carries significance beyond the machine room. It is a marker for the future direction of European high-energy physics.

What happens next

The most immediate work now moves to the upgrade and installation phase.

CERN will continue modifying the accelerator complex and its experiments over the coming years, with further updates expected on the status of the HL-LHC program and the readiness of specific components.

One open question is whether the June 2030 restart target remains stable as the work advances. Another is which systems are replaced first and how the schedule evolves in practice.

For now, the main fact is clear: the LHC has entered a planned long shutdown so CERN can prepare the machine for a more intense scientific era starting in 2030.